Pole Distance Research Articles

Improved Method for Calculating Magnetic Field of Surface-Mounted Permanent Magnet Machines Accounting for Slots and Eccentric Magnet Pole

This paper presented an improved analytical method for calculating the open-circuit magnetic field in the surface-mounted permanent magnet machines accounting for slots and eccentric magnet pole. Magnetic field produced by radial and parallel permanent magnet is equivalent to that produced by surface current according to equivalent surface-current method of permanent magnet. The model is divided into two types of subdomains. The field solution of each subdomain is obtained by applying the interface and boundary conditions. The magnet field produced by equivalent surface current is superposed according to superposition principle of vector potential. The investigation shows harmonic contents of radial flux density can be reduced a lot by changing eccentric distance of eccentric magnet poles compared with conventional surface-mounted permanent-magnet machines with concentric magnet poles. The FE(finite element) results confirm the validity of the analytical results with the proposed model.

Diffusion tensor imaging tractography of Meyer's loop in planning resective surgery for drug-resistant temporal lobe epilepsy

Whether Meyer's loop (ML) tracking using diffusion tensor imaging tractography (DTIT) can be utilized to avoid post-operative visual field deficits (VFD) after anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) using a large cohort of controls and patients. Also, we wanted to create a normative atlas of ML in normal population. DTIT was used to study ML in 75 healthy subjects and 25 patients with and without VFD following ATL. 1.5T MRI echo-planar DTI sequences with DTI data were processed in Nordic ICE using a probabilistic method; a multiple region of interest technique was used for reconstruction of optic radiation trajectory. Visual fields were assessed in patients pre- and post-operatively. Results of ANOVA showed that the left ML-TP distance was less than right across all groups (p = 0.01). The average distance of ML from left temporal pole was 37.44 ± 4.7 mm (range: 32.2-46.6 mm) and from right temporal pole 39.08 ± 4.9 mm (range: 34.3-49.7 mm). Average distance of left and right temporal pole to tip of temporal horn was 28.32 ± 2.03 mm (range: 26.4-32.8 mm) and was 28.92 ± 2.09 mm, respectively (range: 25.9-33.3 mm). If the anterior limit of the Meyer's loop was ≤38 mm on the right and ≤35 mm on the left from the temporal pole, they are at a greater risk of developing VFDs. DTIT is a novel technique to delineate ML and plays an important role in planning surgical resection in TLE to predict post-operative visual performance and disability.

Optimisation Design of a Taguchi-Based Real-Code Genetic Algorithm for Thermal Reducing of Air-Core Linear Brushless Permanent Magnet Motor

This study combined the Taguchi method with the genetic algorithm (GA) to analyse the optimal design parameters of the thermal distribution in an air-core linear brushless permanent magnet motor (ALBPMM). First, this study adopted an L18(21×37) orthogonal array to determine the significant factors, including active currents, the length of magnets, pole distance of magnets, air-gap length, and thickness and width of coils. Then, the study uses response surface methodology (RSM) to construct the predictive model. Finally, the optimal combinations of design parameters that involve using real-code GA were obtained and verified by finite element modelling. The simulation results show that the thermal distribution in the optimal design of parameters is 41% more effective than that of any models in which the parameters are not optimised. Therefore, the proposed approach can be used as the basis for designing and predicting the temperature effects of the ALBPMM..

Metabolically Optimal Gait Transitions in Cross-Country Skate Skiing

With increasing speeds of locomotion, animals change their gait pattern to minimize metabolic cost. For ex- ample, a horse will walk at low speeds, trot at intermediate speeds and gallop at high speeds [1]. Likewise, cross-country skiers use the 2-skate technique at slow speeds, switch to the 1-skate technique at intermediate speeds, but then, in contrast to everything known about locomotion in humans and animals, they revert back to the previously rejected 2-skate technique at very high speeds of locomotion. This pattern of gait transitions suggests that the metabolic efficiency curves for 1-skate and 2-skate skiing intersect twice, rather than just once as they do for human walking and running. The purpose of this study was to test if the metabolic efficiency curves of 1-skate and 2-skate skiing intersect twice, and if so, find an explanation for this surprising result. Eight nationally competitive skiers were tested on a roller ski treadmill. Subjects were asked to ski at speeds of 6-33km/h at 3km/h increments, once with the 1-skate technique and once with the 2-skate technique. Oxygen consumption and 3d kinematics were recorded continuously. We found that the metabolic efficiency curves intersected twice. We also found that pole contact time and distance was much shorter per stride when using the 1-skate technique, especially at very low and very high speeds.

Predicting return to play after hamstring injuries

BackgroundPrevious studies on the prognostic value of clinical and MRI parameters for the time to return to play (TTRTP) in acute hamstring injuries showed only limited to moderate evidence for...

Design of Haul Road Illumination System for an Opencast Coal Mining Project—A Case Study

This article presents a design of an effective haul road illumination system for a mechanized opencast coal mining project. It included an illumination survey of the existing lighting system of the haul road followed by analysis and improvement measures, which include a suitable design plan for an illumination system using DIALux software. The illumination survey was conducted to assess the existing illumination level of the haul road. The methodology involved calculation of horizontal illuminance in a grid fashion, which involved a maximum number of measuring points for achieving better accuracy. A model of haul road illumination system was designed in the DIALux and simulated that gave improved results compared to the existing system of haul road illumination. The model was designed according to CIE 140/EN 13201 illumination standard and the existing design was as per Directorate General of Mines Safety (DGMS) standards. The luminaires used for the design were 400 W high pressure sodium vapor (HPSV) lamps. The simulation was performed by varying the luminaires’ parameters; that is, pole distance, height, inclination, light overhang, etc. The result of the simulation showed that uniformity of light could be achieved by maintaining the effective pole height at 15 m and inclination of luminaires at 15°, by keeping the pole spacing at 40-m intervals. The average to minimum value of the illuminance (uniformity ratio) was obtained from the design. It was also noted that a wet surface resulted in a lower uniformity ratio (0.03) compared to a dry surface (0.10).

Analytical Calculation of Magnetic Field and Cogging Torque in Surface-Mounted Permanent Magnet Machines Accounting for Any Eccentric Rotor Shape

This paper presents an improved analytical method for calculating the magnetic field and cogging torque in the surface-mounted permanent-magnet (PM) machines accounting for any eccentric rotor shape. The magnetic field in the surface-mounted PM machines is predicted according to the surface-current method of the PM, the subdomain model, and the superposition principle of vector potential. The cogging torque is calculated based on Maxwell stress theory and the air-gap magnetic field. The investigation shows that harmonic contents of radial flux density can be reduced a lot by changing eccentric distance of eccentric magnet poles compared with conventional surface-mounted PM machines with concentric magnet poles. Moreover, the analysis has made it clear that the cogging torque of motor with eccentric magnet poles is much smaller than the cogging torque of motor with concentric magnet poles. The finite-element results confirm that the developed analytical method has high accuracy for predicting the magnetic field and cogging torque.

Comparison of vertical and inverted-T mammaplasties using photographic measurements.

Surgeons have long debated the relative merits of vertical and inverted-T mammaplasties. These debates have centered on surgeons' opinions. Without measurements, this controversy is unlikely to be resolved. This study compares these common techniques using a recently published measurement system. Such a study using measurements on photographs matched for size and orientation has not been previously published. A prospective group of women undergoing primary vertical mastopexies, augmentation/mastopexies, and reductions (n = 78) was compared with a retrospective group of women treated with inverted-T mastopexies, augmentation/mastopexies, and reductions (n = 35). Consecutive patients with photographs at least 3 months after surgery and no subsequent procedures were evaluated. All patient groups demonstrated a significant elevation (P < 0.001) of the breast mound. Vertical mastopexy, but not inverted-T mastopexy, increased breast projection and upper pole projection (P < 0.008). Neither vertical nor inverted-T breast reduction significantly increased breast projection. Vertical breast reduction better preserved breast projection (P < 0.017) than the inverted-T technique. Vertical reduction significantly increased upper pole projection (P < 0.008), but inverted-T reduction did not. The inverted-T breast reduction caused greater breast constriction (reduced lower pole distance) than the vertical technique. Lower pole ratios were significantly higher for inverted-T patients (P < 0.01), indicating boxier lower poles. Photographic measurements of relevant breast parameters favor the vertical technique over the inverted-T technique and are consistent with anatomical considerations and clinical experience.

Experiment Study on Spatial Magnetic Field of Large Gap Magnetic Drives System

On the basis of the working principle of the large gap magnetic drives system, the distribution principle of system’s spatial magnetic field under the 4 pole states of T78 electromagnet along the direction and the direction was measured. The experiment results were analyzed. The study results show that the permanent magnet can be placed in a more powerful magnetic field in its rotating period and could get large magnetic field’s coupling force by increasing the current properly, decreasing the coupling distance of magnetic pole between electromagnet and permanent magnet, and putting the permanent magnet into the ±5-10mm range of electromagnet.

The Study of Movement Encoder with Low Cost and High Performance

The paper proposes a design scheme of movement encoder with low cost and high performance. The scheme can provide higher precise rotor position signal for motor by a hall-effect latch and a linear hall-effect sensor, and it can also provide rotational speed and direction of motor by a winding with full pole distance, at last we deduce a torque balance equation based on speed and acceleration of motor. The study shows that the scheme with low cost have much higher position precision than traditional rotational transformer and hall-effect position sensor, and it does not exist amplitude error and phase error, function error is small. It is very worthy to the wide application of motor of electric bicycle, wind-driven generator, electric car, and servomotor, etc.

Latitude dependency of the geomagnetic secular variation S parameter: A mathematical artifact

Secular variation, the change in the Earth's magnetic field through time, reflects the energy state of the geodynamo. Secular variation is commonly quantified by paleomagnetists as the standard deviation of the angular distances of the virtual geomagnetic poles to their mean pole, known as the S value. This parameter has long been thought to exhibit latitude dependence [S(λ)], whose origin is widely attributed to a combination of time‐varying dipole and non‐dipole components. The slope and magnitude ofS(λ) are taken as a basis to understand the geomagnetic field and its evolution. Here we show that S(λ) stems from a mathematical aberration of the conversion from directions to poles, hence directional populations better quantify local estimates of paleosecular variation.

Association between myelin basic protein expression and left entorhinal cortex pre-alpha cell layer disorganization in schizophrenia

There is evidence for migrational disturbances in the entorhinal cortex (ERC) in schizophrenia that supports a neurodevelopmental origin of the disorder. Since impaired myelin basic protein (MBP) gene expression during the migration phase could lead to abnormalities in final laminar position, we performed layer specific measurements of MBP expression in the ERC and hypothesised that migrational disturbances of pre-alpha-cell clusters relate to decreased MBP expression. Paraffin embedded sections of the left entorhinal cortex of 16 schizophrenia patients and 10 control subjects were stained for MBP using routine immunohistochemistry. On each section representative regions of interest were scanned to attain optimal quality images of the gray matter. Results were correlated to previous published disturbed dispersion of pre-alpha-cell clusters in adjacent brain sections. Mean MBP stain-intensity was significantly reduced in schizophrenia patients. Absolute MBP stain-intensity was significantly reduced in layers III and IV in patients. A significant correlation of MBP stain-intensity with the distance of the deep pole of the pre-alpha-cell cluster from the gray–white matter junction was observed in the ERC of schizophrenia patients. The present data provide evidence for reduced MBP expression in the ERC in schizophrenia, which implies deficits in axonal myelination and disturbed connectivity. MBP gene is expressed in oligodendrocytes and neuronal populations during embryonic development, which are important in establishing the structure of the cerebral cortex. Correlation between reduced MBP as a sign of down-regulated MBP gene expression and disorganization of pre-alpha-cell clusters supports a neurodevelopmental origin of pathological processes in schizophrenia.

Irc15 Is a Microtubule-Associated Protein that Regulates Microtubule Dynamics in Saccharomyces cerevisiae

Microtubules are polymers composed of alpha-beta tubulin heterodimers that assemble into microtubules. Microtubules are dynamic structures that have periods of both growth and shrinkage by addition and removal of subunits from the polymer. Microtubules stochastically switch between periods of growth and shrinkage, termed dynamic instability. Dynamic instability is coupled to the GTPase activity of the beta-tubulin subunit of the tubulin heterodimer. Microtubule dynamics are regulated by microtubule-associated proteins (MAPs) that interact with microtubules to regulate dynamic instability. MAPs in budding yeast have been identified that bind microtubule ends (Bim1), that stabilize microtubule structures (Stu2), that bundle microtubules by forming cross-bridges (Ase1), and that interact with microtubules at the kinetochore (Cin8, Kar3, Kip3). IRC15 was previously identified in four different genetic screens for mutants affecting chromosome transmission or repair [11-14]. Here we present evidence that Irc15 is a microtubule-associated protein, localizing to microtubules in vivo and binding to purified microtubules in vitro. Irc15 regulates microtubule dynamics in vivo and loss of IRC15 function leads to delayed mitotic progression, resulting from failure to establish tension between sister kinetochores.

Economic feasibility of solar-powered led roadway lighting

The optical efficacy of light emitting diode (LED) has exceeded 72 lm/W in 2006. This implies that energy can be saved about 75%, as compared to mercury lamps widely used in roadway lighting. In some remote areas where the grid power cannot reach, independent solar-powered lighting using high-power LED provides a promising solution. However, the cost of solar photovoltaic device may cause the application of solar-powered LED roadway lighting to be not economically feasible. The present study investigates the design of the solar-powered LED roadway lighting using high-power LED luminaire (100 W) and estimates the installation cost for a 10 km highway with 2 lanes. LED luminaries are installed on both side of the road with staggered arrangement. The pole distance is 30 m. The cost comparison of LED lighting using grid and solar power with the conventional mercury lamps was carried out. It shows that the installation cost is 22 million USD for LED powered by grid power and 26 million USD for solar-powered. The total installation cost of conventional mercury lighting is 18 million USD. The excess cost of LED mainly comes from the cost of LED lamp and solar PV. But, the cost of power generation and electrical transmission line can be greatly reduced since about 75% energy was saved for LED. This permits the use of smaller copper wire and shorter line length for solar-powered system which in turn saves installation cost. The payback time for the excess investment of LED is 2.2 years for LED using grid power and 3.3 years for LED using solar power.

The human Nup107–160 nuclear pore subcomplex contributes to proper kinetochore functions

We previously demonstrated that a fraction of the human Nup107-160 nuclear pore subcomplex is recruited to kinetochores at the onset of mitosis. However, the molecular determinants for its kinetochore targeting and the functional significance of this localization were not investigated. Here, we show that the Nup107-160 complex interacts with CENP-F, but that CENP-F only moderately contributes to its targeting to kinetochores. In addition, we show that the recruitment of the Nup107-160 complex to kinetochores mainly depends on the Ndc80 complex. We further demonstrate that efficient depletion of the Nup107-160 complex from kinetochores, achieved either by combining siRNAs targeting several of its subunits excluding Seh1, or by depleting Seh1 alone, induces a mitotic delay. Further analysis of Seh1-depleted cells revealed impaired chromosome congression, reduced kinetochore tension and kinetochore-microtubule attachment defects. Finally, we show that the presence of the Nup107-160 complex at kinetochores is required for the recruitment of Crm1 and RanGAP1-RanBP2 to these structures. Together, our data thus provide the first molecular clues underlying the function of the human Nup107-160 complex at kinetochores.

ROBUSTNESS GRADIENTS FOR DISCRETE-TIME CONTROL SYSTEMS

ABSTRACT This article addresses gradients for discrete-time control system design. First, the stability margin is investigated based on the minimum distance of the Mikhailov hodograph to the origin or on the minimum distance of the closed-loop poles to the unit circle. The gradients with respect to the output state controller matrix are derived and applied for stepwise, improving the dynamics of the closed-loop system. Second, the maximum admissible uncertainty of the plant is considered based on the unstructured type of uncertainty. For robustification, gradients to attain maximum admissible uncertainty are introduced.

Modelling and construction of a compact 500 kg HTS magnetic bearing

The progress of heavy-load HTS bearings depends on improvements in design,material quality and reliable cooling. We have constructed, manufacturedand tested a 200 mm HTS journal bearing with a thermally encapsulatedYBCO ring. For maximum force the larger gap due to the bearing cryostat(>4 mm) requires adjustment of the magnetic excitation pole distance and the Fe collector shimthickness. HTS material progress is obtained by top-seeded single- or multiple-grain growth whichincreases the averaged trapped magnetic flux density. Successful YBCO ring growth with radialc axis distribution by seeding the inner ring surface has been performed. The encapsulationensures a substantially reduced cryogenic effort and stabilizes bearing operation at 78–79 K.

Precision septum-like dipole magnet for the HERA luminosity upgrade

Within the framework of the HERA luminosity upgrade project Scanditronix Magnet AB has designed in collaboration with AMACC AB, IBA S.A. and DESY a septum-like dipole for the compensation of orbit differences between e/sup +/-p and e~-p collisions at HERA. The magnet yoke is 640 mm long, 415 mm wide and 550 mm high. The total magnet length is 930 mm. The pole distance is 70 mm, the "good field" region is /spl plusmn/ 20 mm centered around the nominal proton orbit. To meet the high field quality requirements for the whole range of field excitation between 0.1 T and 1.1 T VACOFLUX shims have been added to the pole edges to reduce saturation effects. The air gap is extended from the pole region by 235 mm to allow incoming synchrotron radiation light to pass through the magnet without being scattered. The separation between proton and electron beam at the magnet position at 18.88 m away from the interaction point is 121 mm. Carefully chosen thickness of the return yoke, a 13 mm thick shielding plate between proton and electron beam and 40 mm thick mirror plates on the front faces of the magnet reduce the field outside the magnet well below the tolerable value of 0,5/sub */10/sup -3/ T/sub */m integrated along the e-orbit.

Construction and measurement of the pre-series twin aperture resistive quadrupole magnet for the LHC beam cleaning insertions

CERN's Large Hadron Collider (LHC) requires 48 twin aperture resistive quadrupoles in the beam cleaning insertions. Canada is contributing these magnets to CERN in the framework of the TRIUMF-LHC collaboration contracts. A pre-series magnet was produced by Canadian industry and delivered in March 2001. This magnet incorporates important design changes that resulted from experience with a prototype magnet. The construction of this pre-series magnet and the measurements made at ALSTOM and at CERN are reported. A comparison is made between high precision pole distance measurements and the magnetic measurements performed with a rotating coil mole. Conclusions for series production and possibilities for multipole corrections are outlined.

Cytoarchitectonic basis for safe entry into the brainstem.

This work is a continuation of the anatomical study in which safe approach zones through the floor of the fourth ventricle--infrafacial and suprafacial--were morphologically and morphometrically defined (Acta Neurochir (1997) 139: 1014-1019). The purpose of cytoarchitectonic study was to analyze correlation between morphometry of the facial colliculus and hypoglossal triangle and localization of the corresponding cranial nerves nuclei in the brainstem tegmentum in order to verify morphometrical borders of the previously defined zones. Morphometrical evaluation of the fourth ventricle floor of 10 examined brainstems was initially performed. Distances from obex to the rostral portion of hypoglossal triangle and facial colliculus were determined. Then a series of axial sections of each specimen, stained for Nissl substance, were analyzed to define the distance from obex to the rostral portion of the hypoglossal and abducens nuclei. Distances of motor trigeminal and facial nuclei from the midline sagittal plane were also measured. The obtained results allowed morphometrical determination of the infra-abducental and supra-abducental region of safe entry into the brainstem tegmentum. Infra-abducental region corresponds to infrafacial safe approach zone and supra-abducental to suprafacial zone. The distance of the rostral portion of facial colliculus from obex was longer than the distance of the rostral pole of abducens nucleus from obex in every examined specimen (by 0.7 mm on average). A very similar correlation between the distance of the rostral margin of hypoglossal triangle and localization of the rostral pole of hypoglossal nucleus was found. The rostral portion of hypoglossal triangle was longer by 1.5 mm on average. The obtained results show that previously defined infrafacial and suprafacial safe approach zones via the fourth ventricle floor correspond morphometrically to tegmental regions of safe entry--infra-abducental and supra-abducental respectively. It suggests that morphometrical evaluation of the fourth ventricle floor proposed by the authors could be useful in the intra-operative determination of safe entry via the rhomboid fossa into the brainstem tegmentum.