Three-Dimensional Analytical Modeling of Axial-Flux Permanent Magnet Drivers

In this paper, the axial-flux permanent magnet driver is modeledand analyzed in a simple and novel way under three-dimensional cylindricalcoordinates. The inherent three-dimensional characteristics of the deviceare comprehensively considered, and the governing equations are solved bysimplifying the boundary conditions. The axial magnetization of the sectorshapedpermanent magnets is accurately described in an algebraic form bythe parameters, which makes the physical meaning more explicit than thepurely mathematical expression in general series forms. The parameters of theBessel function are determined simply and the magnetic field distribution ofpermanent magnets and the air-gap is solved. Furthermore, the field solutionsare completely analytical, which provides convenience and satisfactoryaccuracy for modeling a series of electromagnetic performance parameters,such as the axial electromagnetic force density, axial electromagnetic force,and electromagnetic torque. The correctness and accuracy of the analyticalmodels are fully verified by three-dimensional finite element simulations and a15 kW prototype and the results of calculations, simulations, and experimentsunder three methods are highly consistent. The influence of several designparameters on magnetic field distribution and performance is studied and discussed.The results indicate that the modeling method proposed in this papercan calculate the magnetic field distribution and performance accurately andrapidly, which affords an important reference for the design and optimizationof axial-flux permanent magnet drivers.

Application of Three-Dimensional Magnetic Resonance Imaging in the Diagnosis of Perianal Abscess

Perianal abscess is a common disease in anorectal surgery. If the diagnosis is not clear and the cure is thoroughly cleared, the recurrence and spread of anal fistula will cause life-long pain. Objective: To investigate the application of 3.0T MRI 3D CUBE T2WI lipid suppression sequence in the diagnosis of perianal abscess. Methods: Thirty-six patients with perianal abscess confirmed by operation were examined with 2D T2WI and 3D CUBE T2WI lipid suppression sequences before operation. Two imaging techniques were evaluated to show the types of perianal abscess, the number of abscesses, the number of internal orifices of abscess, and the number of fistula branches with anal fistula in abscess. Results: Among 36 cases of perianal abscess, there were 5 cases of anal subcutaneous abscess, 12 cases of ischiorectal space abscess (8 cases complicated with anal fistula), 6 cases of posterior anal space abscess, 5 cases of anal sphincter abscess (3 cases complicated with anal fistula), 2 cases of high intermuscular abscess, 2 cases of rectal submucosal abscess, 3 cases of complex abscess (3 cases complicated with anal fistula), 1 case of misdiagnosis, 2D T2WI lipid suppression sequence and 3D CUBE T2WI suppression. The accuracy of lipid sequence abscess typing was 80.6% (29/36) and 88.9% (32/36), respectively, with no significant difference (P > 0.05). Thirty-six patients were surgically diagnosed as having 32 internal orifices, 68.8% (22/32) and 93.8% (30/32) of 2D T2WI and 3D CUBE T2WI lipid-suppressing sequences, respectively, with significant difference (P Conclusion: 3D CUBE T2WI lipid suppression sequence is superior to 2D T2WI lipid suppression sequence in the classification of perianal abscess, the number of internal orifices of abscess and the number of fistula branches of abscess complicated with anal fistula. It can also determine the number of internal orifices of abscess complicated with anal fistula, the number of fistula branches, the shape of primary and branch fistula and the relationship among pelvic floor muscle tissues. It can provide more accurate images for preoperative and intraoperative clinical surgery.

Three-dimensional reconstructed magnetic resonance scans:Accuracy in identifying and defining knee meniscal tears

AIM To determine whether three-dimensional(3D) reconstruction from conventional magnetic resonance imaging(MRI) is able to accurately detect a meniscal tear, and define the configuration.METHODS Thirty-three patients' 3T MRI scan data were collected and sagittal uni-planar 3D reconstructions performed from the preoperative MRI. There were 24 meniscal tears in 24 patients, and nine controls. All patients had arthroscopic corroboration of MRI findings. Two independent observers prospectively reported on all 33 reconstructions. Meniscal tear presence or absence was noted, and tear configuration subsequently categorised as either radial, bucket-handle, parrot beak, horizontal or complex.RESULTS Identification of control menisci or meniscal tear presence was excellent(Accuracy: observer 1 = 90.9%; observer 2 = 81.8%). Of the tear configurations, bucket handle tears were accurately identified(Accuracy observer 1 and 2 = 80%). The remaining tear configurations were notaccurately discernable.CONCLUSION Uni-planar 3D reconstruction from 3T MRI knee scan sequences are useful in identifying normal menisci and menisci with bucket-handle tears. Advances in MRI sequencing and reconstruction software are awaited for accurate identification of the remaining meniscal tear configurations.

Magnetic resonance imaging-three-dimensional printing technology fabricates customized scaffolds for brain tissue engineering

Conventional fabrication methods lack the ability to control both macro- and micro-structures of generated scaffolds. Three-dimensional printing is a solid free-form fabrication method that provides novel ways to create customized scaffolds with high precision and accuracy. In this study, an electrically controlled cortical impactor was used to induce randomized brain tissue defects. The overall shape of scaffolds was designed using rat-specific anatomical data obtained from magnetic resonance imaging, and the internal structure was created by computer- aided design. As the result of limitations arising from insufficient resolution of the manufacturing process, we magnified the size of the cavity model prototype five-fold to successfully fabricate customized collagen-chitosan scaffolds using three-dimensional printing. Results demonstrated that scaffolds have three-dimensional porous structures, high porosity, highly specific surface areas, pore connectivity and good internal characteristics. Neural stem cells co-cultured with scaffolds showed good viability, indicating good biocompatibility and biodegradability. This technique may be a promising new strategy for regenerating complex damaged brain tissues, and helps pave the way toward personalized medicine.

Three-dimensional time-of-flight magnetic resonance angiography combined with high resolution T2-weighted imaging in preoperative evaluation of microvascular decompression

BACKGROUND Neurovascular compression(NVC) is the main cause of primary trigeminal neuralgia(TN) and hemifacial spasm(HFS). Microvascular decompression(MVD) is an effective surgical method for the treatment of TN and HFS caused by NVC. The judgement of NVC is a critical step in the preoperative evaluation of MVD, which is related to the effect of MVD treatment. Magnetic resonance imaging(MRI) technology has been used to detect NVC prior to MVD for several years. Among many MRI sequences, three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA) is the most widely used. However, 3D TOF MRA has some shortcomings in detecting NVC. Therefore, 3D TOF MRA combined with high resolution T2-weighted imaging(HR T2WI) is considered to be a more effective method to detect NVC.AIM To determine the value of 3D TOF MRA combined with HR T2WI in the judgment of NVC, and thus to assess its value in the preoperative evaluation of MVD.METHODS Related studies published from inception to September 2022 based on PubMed, Embase, Web of Science, and the Cochrane Library were retrieved. Studies that investigated 3D TOF MRA combined with HR T2WI to judge NVC in patients with TN or HFS were included according to the inclusion criteria. Studies without complete data or not relevant to the research topics were excluded. The Quality Assessment of Diagnostic Accuracy Studies checklist was used to assess the quality of included studies. The publication bias of the included literature was examined by Deeks’ test. An exact binomial rendition of the bivariate mixed-effects regression model was used to synthesize data. Data analysis was performed using the MIDAS module of statistical software Stata 16.0. Two independent investigators extracted patient and study characteristics, and discrepancies were resolved by consensus. Individual and pooled sensitivities and specificities were calculated. The I_(2) statistic and Q test were used to test heterogeneity. The study was registered on the website of PROSERO(registration No. CRD42022357158).RESULTS Our search identified 595 articles, of which 12(including 855 patients) fulfilled the inclusion criteria. Bivariate analysis showed that the pooled sensitivity and specificity of 3D TOF MRA combined with HR T2WI for detecting NVC were 0.96 [95% confidence interval(CI): 0.92-0.98] and 0.92(95%CI: 0.74-0.98), respectively. The pooled positive likelihood ratio was 12.4(95%CI: 3.2-47.8), pooled negative likelihood ratio was 0.04(95%CI: 0.02-0.09), and pooled diagnostic odds ratio was 283(95%CI: 50-1620). The area under the receiver operating characteristic curve was 0.98(95%CI: 0.97-0.99). The studies showed no substantial heterogeneity(I2 = 0, Q = 0.001 P = 0.50).CONCLUSION Our results suggest that 3D TOF MRA combined with HR T2WI has excellent sensitivity and specificity for judging NVC in patients with TN or HFS. This method can be used as an effective tool for preoperative evaluation of MVD.

Three-dimensional gravity and magnetic data acquisition and study on its joint gradient Euler deconvolution method

Three-dimensional(3 D)gravitational and magnetic exploration is performed using aerial measurement tools,however,this has difficulties with measuring-height design and the construction of a joint-interpretation scheme.At present,the height in such experiments is set according to the measurement scale,and the distribution characteristics of anomalies are not fully considered.Here,we present the idea of using the attenuation characteristics of a singular-value spectrum to evaluate the contributions of various measurement heights and multi-height combinations for inversion to correctly and reasonably design appropriate measuring heights and the number of various measurement heights to be set.The jointgradient Euler-deconvolution method can accurately obtain the distribution of geological bodies from 3 D gravitational and magnetic data at an improved resolution,and experimental tests confirm these findings.Therefore,an actual 3 D aeromagnetic-data-acquisition and inversion test were carried out in the vicinity of the Zhurihe Iron Mine in Inner Mongolia.The fl ight-height diff erence was set to 60 m,and the specifi c distribution of lodes was obtained by the joint-gradient Euler-deconvolution method.This provides a reliable basis for future detailed exploration and proves that the methods presented in this paper have good practicalapplication eff ects and prospects.

Avian magnetic compass:Its functional properties and physical basis

The avian magnetic compass was analyzed in bird species of three different orders - Passeriforms, Columbiforms and Galliforms - and in three different behavioral contexts, namely migratory orientation, homing and directional conditioning. The respective findings indicate similar functional properties： it is an inclination compass that works only within a functional window around the ambient magnetic field intensity; it tends to be lateralized in favor of the fight eye, and it is wavelength-dependent, requiring light from the short-wavelength range of the spectrum. The underlying physical mechanisms have been identified as radical pair processes, spin-chemical reactions in specialized photopigments. The iron-based receptors in the upper beak do not seem to be involved. The existence of the same type of magnetic compass in only very distantly related bird species suggests that it may have been present already in the common ancestors of all modem birds, where it evolved as an all-purpose compass mechanism for orientation within the home range [Current Zoology 56 （3）： 265-276, 2010].

Three-Dimensional Finite Element Numerical Simulation and Physical Experiment for Magnetism-Stress Detecting in Oil Casing

The casing damage has been a big problem in oilfield production. The current detection methods mostly are used after casing damage, which is not very effective. With the rapid development of China's offshore oil industry, the number of offshore oil wells is becoming larger and larger. Because the cost of offshore oil well is very high, the casing damage will cause huge economic losses. What's more, it can also bring serious pollution to marine environment. So the effective methods of detecting casing damage are required badly. The accumulation of stress is the main reason for the casing damage. Magnetic anisotropy technique based on counter magnetostriction effect can detect the stress of casing in real time and help us to find out the hidden dangers in time. It is essential for us to prevent the casing damage from occurring. However, such technique is still in the development stage. Previous studies mostly got the relationship between stress and magnetic signals by physical experiment, and the study of physical mechanism in relative magnetic permeability connecting the stress and magnetic signals is rarely reported. The present paper uses the ANSYS to do the three-dimensional finite element numerical simulation to study how the relative magnetic permeability works for the oil casing model. We find that the quantitative relationship between the stress' s variation and magnetic induction intensity's variation is: Δδ =K* ΔB, K = 8.04×109, which is proved correct by physical experiment.

Reduced Imaging Time and Improved Image Quality of 3D Isotropic T2-Weighted Magnetic Resonance Imaging with Compressed Sensing for the Female Pelvis

This study is to compare three-dimensional(3D)isotropic T2-weighted magnetic resonance imaging(MRI)with compressed sensing-sampling perfection with application optimized contrast(CS-SPACE)and the conventional image(3D-SPACE)sequence in terms of image quality,estimated signal-to-noise ratio(SNR),relative contrast-to-noise ratio(CNR),and the lesions’conspicuous of the female pelvis.Thirty-six females(age:51,28-73)with cervical carcinoma(n=20),rectal carcinoma(n=7),or uterine fibroid(n=9)were included.Patients underwent magnetic resonance(MR)imaging at a 3T scanner with the sequences of 3D-SPACE,CS-SPACE,and twodimensional(2D)T2-weighted turbo-spin echo(TSE).Quantitative analyses of estimated SNR and relative CNR between tumors and other tissues,image quality,and tissue conspicuity were performed.Two radiologists assessed the difference in diagnostic findings for carcinoma.Quantitative values and qualitative scores were analyzed,respectively.The estimated SNR and the relative CNR of tumor-to-muscle obturator internus,tumor-to-myometrium,and myometrium-to-muscle obturator internus was comparable between 3D-SPACE and CS-SPACE.The overall image quality and the conspicuity of the lesion scores of the CS-SPACE were higher than that of the 3D-SPACE(P<0.01).The CS-SPACE sequence offers shorter scan time,fewer artifacts,and comparable SNR and CNR to conventional 3D-SPACE,and has the potential to improve the performance of T2-weighted images.

Regional magnetic anomaly fields:3D Taylor polynomial and surface spline models

We used data from 1960.0,1970.0,1980.0,1990.0,and 2000.0 to study the geomagnetic anomaly field over the Chinese mainland by using the three-dimensional Taylor polynomial（3DTP） and the surface spline（SS） models.To obtain the pure anomaly field,the main field and the induced field of the ionospheric and magnetospheric fields were removed from measured data.We also compared the SS model anomalies and the data obtained with Kriging interpolation（KI）.The geomagnetic anomaly distribution over the mainland was analyzed based on the SS and 3DTP models by transferring all points from 1960.0-1990.0 to 2000.0.The results suggest that the total intensity F anomalies estimated based on the SS and KI for each year are basically consistent in distribution and intensity.The anomalous distributions in the X-,Y-,and Z-direction and F are mainly negative.The 3DTP model anomalies suggest that the intensity in the X-direction increases from-100 nT to 0 nT with longitude,whereas the intensity in the Y-direction decreases from 400 nT to 20 nT with longitude and over the eastern mainland is almost negative.The intensity in the Z-direction and F are very similar and in most areas it is about-50 nT and higher in western Tibet.The SS model anomalies overall reflect the actual distribution of the magnetic field anomalies;however,because of the uneven distribution of measurements,it yields several big anomalies.Owing to the added altitude term,the 3DTP model offers higher precision and is consistent with KI.

Three-dimensional magnetization reconstruction from electron optical phase images with physical constraints

The ability to characterize three-dimensional(3D)magnetization distributions in nanoscale magnetic materials and devices is essential to fully understand their static and dynamic magnetic properties.Phase contrast techniques in the transmission electron microscope(TEM),such as electron holography and electron ptychography,can be used to record two-dimensional(2D)projections of the in-plane magnetic induction of 3D nanoscale objects.Although the 3D magnetic induction can in principle be reconstructed from one or more tilt series of such 2D projections,conventional tomographic reconstruction algorithms do not recover the 3D magnetization within a sample directly.Here,we use simulations to describe the basis of an improved model-based algorithm for the tomographic reconstruction of a 3D magnetization distribution from one or more tilt series of electron optical phase images recorded in the TEM.The algorithm allows a wide range of physical constraints,including a priori information about the sample geometry and magnetic parameters,to be specified.It also makes use of minimization of the micromagnetic energy in the loss function.We demonstrate the reconstruction of the 3D magnetization of a localized magnetic soliton—a hopfion ring—and discuss the influence of noise,choice of magnetic constants,maximum tilt angle and number of tilt axes on the result.The algorithm can in principle be adapted for other magnetic contrast imaging techniques in the TEM,as well as for other magnetic characterization techniques,such as those based on X-rays or neutrons.

Flow Field and Temperature Field of Water-Cooling-Type Magnetic Coupling

At present, the water-cooling simulation of the water-cooled magnetic coupler is based on the water-cooled motor and the hydraulic coupler, which cannot accurately characterize the temperature distribution of the rotating watercooled coupling of the coupler. Focusing on rotating water cooling radiating, the present paper proposes simulating the water cooling temperature field as well as the flow field through the method of combining fluid-solid coupled heat transfer and MRF(Multiphase Reference Frame). In addition, taking an 800 kW magnetic coupling as an example, the paper optimizes the shape, number, cooling water inlet speed? and so on? of the cooling channel. Considering factors such as the complete machine’s temperature, and drag torque, it is proved that the cooling e ect is best when there are 36 involute curved channels and when the inlet speed is 3 m/s. Further, through experiments, the actual temperature values at six di erent positions when 50 kW and 70 kW thermal losses di er are measured. The measured values agree with the simulation results, proving the correctness of the proposed method. Further, data have been collected during the entire experimental procedure? and the variation in the coupling’s temperature is analyzed in depth, with the objective of laying a foundation for the estimation of the inner temperature rise as well as for the optimization of the structural design.

Direct loading of atoms from a macroscopic quadrupole magnetic trap into a microchip trap

We demonstrate the direct loading of cold atoms into a microchip 2-mm Z-trap, where the evaporative cooling can be performed efficiently, from a macroscopic quadrupole magnetic trap with a high loading efficiency. The macroscopic quadrupole magnetic trap potential is designed to be moveable by controlling the currents of the two pairs of anti-Helrnholtz coils. The cold atoms are initially prepared in a standard six-beam magneto-optical trap and loaded into the macroscopic quadrupole magnetic trap, and then transported to the atom chip surface by moving the macroscopic trap potential. By means of a three-dimensional absorption imaging system, we are able to optimize the position alignment of the atom cloud in the macroscopic trap and the microchip Z-shaped wire. Consequently, with a proper magnetic transfer scheme, we load the cold atoms into the microchip Z-trap directly and efficiently. The loading efficiency is measured to be about 50%. This approach can be used to generate appropriate ultracold atoms sources, for example, for a magnetically guided atom interferometer based on atom chip.

A three-dimensional digital visualization model of cervical nerves in a healthy person

Three-dimensional reconstruction nerve models are classically obtained from two-dimensional images of ＂visible human＂ frozen sections. However, because of the flexibility of nerve tissues and small color differences compared with surrounding tissues, the integrity and validity of nerve tissues can be impaired during milling. Thus, in the present study, we obtained two-dimensional data from a healthy volunteer based on continuous CT angiography and magnetic resonance myelography. Semi-automatic segmentation and reconstruction were then conducted at different thresholds in different tissues using Mimics software. Small anatomical structures such as muscles and cervical nerves were reconstructed using the medical computer aided design module. Three-dimensional digital models of the cervical nerves and their surrounding structures were successfully developed, which allowed visualization of the spatial relation of anatomical structures with a strong three-dimensional effect, distinct appearance, clear distribution, and good continuity, precision, and integrality. These results indicate the validity of a three-dimensional digital visualization model of healthy human cervical nerves, which overcomes the disadvantages of milling, avoids data loss, and exhibits a realistic appearance and three-dimensional image.

Low Cost,Low Power Magnetic IEDs Detection Method Using Biaxial Magnetometry Digital Sensors

The magnetic improvised explosive devices （IEDs）, also commonly known as a type of a sticky bomb, is simply constructed devices yet very lethal. This paper puts forward the idea of an electronic compass that is capable of sensing the change of a magnetic field generated by a magnet and translating it into interpretable data, which could act as the base for the further studies and assist in developing a greener automated system for detecting this device. The electronic compass is specifically chosen for reducing power consumption of systems in addition to the fact that it is available at a low cost.

Radial magnetic field in magnetic confinement device

The intrinsic radial magnetic field（B r） in a tokamak is explored by the solution of the Grad–Shafranov equation in axisymmetric configurations through an expansion of the four terms of the magnetic surfaces. It can be inferred from the simulation results that at the core of the device, the tokamak should possess a three-dimensional magnetic field configuration, which could be reduced to a two-dimensional one when the radial position is greater than 0.6a. The radial magnetic field and the amzimuthal magnetic field have the same order of magnitude at the core of the device. These results can offer a reference for the analysis of the plasma instability, the property of the core plasma, and the magnetic field measurement.

3D Magnetic Field Computation of a Permanent MagnetDisc-Type Generator Using Scalar Potential Method

The three-dimensional magnetic field of a permanent permanent (PM) disc-type generator is analyzed by the scalar potential method. In the analysis the permanent magnets are taken as magnetic charges. Hexahedron element meshes are automatically generated by a prc-proccssing program developed by the authors. The flux densily is computed by a 3D scalar potential method program. Based on the linite elcment analysis the induced emf, current, armaturc reaction effects and electromagnetic torque of the disc machine are all calculated.

Cerebral blood flow volume measurements of the carotid artery and ipsilateral branches using two-dimensional phase-contrast magnetic resonance angiography

The optimal velocity encoding of phase-contrast magnetic resonance angiography （PC MRA） in measuring cerebral blood flow volume （BFV） ranges from 60 to 80 cm/s. To verify the accuracy of two-dimensional （2D） PC MRA, the present study localized the region of interest at blood vessels of the neck using PC MRA based on three-dimensional time-of-flight sequences, and the velocity encoding was set to 80 cm/s. Results of the measurements showed that the error rate was 7.0±6.0% in the estimation of BFV in the internal carotid artery, the external carotid artery and the ipsilateral common carotid artery. There was no significant difference, and a significant correlation in BFV between internal carotid artery ＋ external carotid artery and ipsilateral common carotid artery. In addition, the BFV of the common carotid artery was correlated with that of the ipsilateral internal carotid artery. The main error was attributed to the external carotid artery and its branches. Therefore, after selecting the appropriate scanning parameters and protocols, 2D PC MRA is more accurate in the determination of BFV in the carotid arteries.

Numerical investigation of radio-frequency negative hydrogen ion sources by a three-dimensional fluid model

A three-dimensional fluid model is developed to investigate the radio-frequency inductively coupled H2 plasma in a reactor with a rectangular expansion chamber and a cylindrical driver chamber,for neutral beam injection system in CFETR.In this model,the electron effective collision frequency and the ion mobility at high E-fields are employed,for accurate simulation of discharges at low pressures(0.3 Pa-2 Pa)and high powers(40 kW-100 kW).The results indicate that when the high E-field ion mobility is taken into account,the electron density is about four times higher than the value in the low E-field case.In addition,the influences of the magnetic field,pressure and power on the electron density and electron temperature are demonstrated.It is found that the electron density and electron temperature in the xz-plane along permanent magnet side become much more asymmetric when magnetic field enhances.However,the plasma parameters in the yz-plane without permanent magnet side are symmetric no matter the magnetic field is applied or not.Besides,the maximum of the electron density first increases and then decreases with magnetic field,while the electron temperature at the bottom of the expansion region first decreases and then almost keeps constant.As the pressure increases from 0.3 Pa to 2 Pa,the electron density becomes higher,with the maximum moving upwards to the driver region,and the symmetry of the electron temperature in the xz-plane becomes much better.As power increases,the electron density rises,whereas the spatial distribution is similar.It can be summarized that the magnetic field and gas pressure have great influence on the symmetry of the plasma parameters,while the power only has little effect.

A three-dimensional matrix system containing melatonin and neural stem cells repairs damage from traumatic brain injury in rats

Brain lesions can cause neural stem cells to activate,proliferate,diffe rentiate,and migrate to the injured area.However,after traumatic brain injury,brain tissue defects and microenvironment changes greatly affect the survival and growth of neural stem cells;the resulting reduction in the number of neural stem cells impedes effective repair of the injured area.Melatonin can promote the survival,proliferation,and differentiation of neural stem cells under adverse conditions such as oxidative stress or hypoxia that can occur after traumatic brain injury.Therefore,we investigated the therapeutic effects of melatonin combined with neural stem cells on traumatic brain injury in rats.First,in vitro studies confirmed that melatonin promoted the survival of neural stem cells deprived of oxygen and glucose.Then,we established a three-dimensional Matrigel-based transplantation system containing melatonin and neural stem cells and then used it to treat traumatic brain injury in rats.We found that treatment with the Matrigel system containing melatonin and neural stem cells decreased brain lesion volume,increased the number of surviving neuro ns,and improved recove ry of neurological function compared with treatment with Matrigel alone,neural stem cells alone,Matrigel and neural stem cells combined,and Matrigel and melatonin combined.Our findings suggest that the three-dimensional Matrigelbased transplantation system containing melatonin and neural stem cells is a potential treatment for traumatic brain injury.