No-Load Iron Loss Model for a Fractional-Slot Surface-Mounted Permanent Magnet Motor Based on Magnetic Field Analytical Calculation

The common analytical models for the no-load iron loss of permanent magnet(PM)motors usually neglect the iron loss caused by the rotating magnetic field in the tooth tips and the harmonics of the magnetic fields in the teeth and yokes.This paper presents an analytical model for no-load iron loss of a fractional-slot surface-mounted permanent magnet motor.According to the existing analytical model of the magnetic field distribution in the slotted air gap,the magnetic flux densities considering the harmonics of the stator tooth and yoke are both derived based on the continuity of magnetic flux.Due to the complexity of the magnetic field in the tooth tip,the tangential flux density of the tooth tip is approximated by an equivalent sine wave and the radial component is regarded to be the same as that of the corresponding tooth.After obtaining the magnetic fields in stator different regions,the analytical iron loss is calculated by using the Bertotti model and the orthogonal decomposition model.A 20-pole/24-slot PM synchronous motor is taken as an example.The maximum error between the analytical model and finite element model(FEM)is 5.46%,which verifies the validity of the proposed method.

Effect of no-load rate on recast layer cutting by ultra fine wire-EDM

Via material erosion in wire electrical discharge machining(WEDM),recast layers form on the surfaces of workpiece.In addition,ultra fine Wire-EDM can be usually cut once.To reduce the thickness of the recast layer as much as possible,the wire electrical discharge-electrochemical machining(WEDCM)method was proposed,which is based on the micro conductivity of the dielectric and microelectrolytic characteristics by adjusting the no-load rate of the pulse in the machining process.Furthermore,a state discrimination and servo control system based on discharge current was designed.The experiment results of different no-load rates show that the electrolytic effects increase as the no-load rate increases,and the main machining process is spark discharge erosion with a no-load rate in the range of 10%to 80%.At 90%no-load rate,the amount of recast layer formation in the forward direction of the wire electrode is almost the same as that of electrolytic dissolution,and it can be practically processed without a recast layer.Compared with10%no-load rate,the kerf width only increases by 7.5%.

Research on Digital Dynamic Testing Technique for Electrohydraulic Servovalve

The digital testing technique based on computers for dynamic characteristics of electrohydraulic servovalves via frequency scan method is researched. The no-load piston which measures the servo's transient output flow is designed properly. The velocity testing method by which the speed signal can be obtained indirectly by means of a piezoelectral accelerometer is given. High speed sampling has been realized in Windows OS. Wavelet denoising and Fourier transform are adopted in data processing and analyses. The testing technique discussed has been applied to actual testing systems and the experimental results have proved it to be correct.

Analysis of Permanent Magnet-assisted Synchronous Reluctance Motor Based on Equivalent Reluctance Network Model

In this paper,the equivalent reluctance network model(ERNM)is used to calculate the magnetic circuit of a permanent magnet-assisted synchronous reluctance motor(PMASynRM)and calculate no-load air-gap magnetic field and electromagnetic torque.Iteration method is used to solve the relative permeability of iron core.A novel reluctance network model based on actual distribution of the magnetic flux inside the motor is established.The magnetomotive force(MMF)generated by armature winding affects the relative permeability of iron core,which is considered in the calculation of ERNM to improve the accuracy when the motor is under load.ERNM can be used to measure air-gap flux density,no-load back electromotive force(EMF),the average value of motor torque,the armature winding voltage under load,and power factor.The method of calculating the motor performance is proposed.The results of calculation are consistent with finite element method(FEM)and the computational complexity is much less than that of the FEM.The results of ERNM has been verified,which will provide a simple method for motor design and analysis.

不同运动负荷对心脏超微结构与NO、NOS的影响

采用大鼠 8周递增负荷游泳训练模型 ,观察不同运动负荷方式对大鼠心脏超微结构的影响 ,以及血浆和心肌中舒血管因子一氧化氮NO、一氧化氮合酶NOS的变化 ,探讨不同运动负荷对大鼠的影响 ,并对其产生机制进行初步探讨。研究结果表明有氧训练能够使心肌的超微结构改善 ,提高心肌的cNOS活性、血浆NO水平 ,促进内皮组织舒张反应 ;大强度长时间的训练使心肌微细损伤出现 ,内皮组织损伤 ,但血浆NO水平变化不大。

不同负荷跑台训练对大鼠坐骨神经NOSⅠ表达的影响

目的:研究运动训练对坐骨神经内NO含量影响.方法:通过选用2mo龄雄性纯种SD大鼠45只,随机等分成3组,正常对照组(SC15),一般负荷组(MT15),过度负荷组(OT15).跑台坡度为10度,每周训练6d,周日休息,每日1次,共训练8wk.结果:整个实验中大鼠饮食量发生了显著的变化.过度负荷组以上指标均显著低于对照组与一般负荷组.结论:一般负荷运动训练大鼠有益于运动能力的提高,过度负荷运动训练,可能对神经纤维对信息的传导起抑制的作用,导致运动能力下降.

Effect of Refiner Plate Bar Angle and Pulp Properties on the Low Consistency Refining Efficiency in Terms of Power Consumption

Power consumption is the energy source of the impact on fibers or pulp during low-consistency(LC)pulp refining,and the strength of refining affects refining quality and efficiency.The pulp properties,operating parameters,and bar parameters of the refiner plates are important parameters affecting refining efficiency,which can be defined as the ratio of net to total refining power.In this study,LC refining trials for pulps with different consistencies and fiber lengths were conducted using five isometric straightbar plates with different bar angles to explore the influences of the plate bar angle and pulp properties on the no-load power,impact capacity on fibers and refining efficiency.It was found that the no-load power of the LC refining process decreased with an increase in the plate bar angle while increased when pulp with higher consistency was refined under the same refining conditions.However,the effect of pulp consistency on the no-load power can be neglected when refining is conducted using plates with larger bar angles.Meanwhile,a critical bar angle for straight-bar plates in LC refining may exist,which has the strongest impact on the pulp and highest refining efficiency under the same refining conditions.In addition,the impact capacity of the plate on the pulp and refining efficiency in LC refining can be enhanced by appropriately increasing the pulp consistency and average fiber length when the bar angle of the refiner plate with a sector angle of 40°is less than 30°.Therefore,the efficiency and power consumption of the LC refining process can be adjusted by optimizing the pulp consistency and bar parameters of the refining plates.

沙漠负重行军者热休克蛋白与一氧化氮的关系

目的 探讨沙漠干热环境负重应激行军者热休克蛋白 (HSPs)与机体一氧化氮 (NO)及其一氧化氮合成酶 (NOS)的关系。方法 对在沙漠干热环境中 15kg负重、分别以 3 5km/h和 5 0km/h速度行军 1,2 ,3h的 57名战士和 14名对照血浆HSP70和HSP2 7、NOS和NOS等进行研究。结果 在 15kg负重条件下 ,不管是 3 5km /h还是5 0km /h ,各行军组HSP70与对照组及各行军时间组间HSP70均无显著性差异 (P >0 0 5) ;各行军时间组HSP2 7明显高于对照组 (P <0 0 5) ,各行军时间组间HSP2 7无显著性差异 (P >0 0 5) ;各行军时间组NO明显低于对照组(P <0 0 5)。 3 5km /h行军 3h组NO明显低于行军 1,2h组 (P <0 0 5) ;3 5km/h行军 1h组NOS明显高于对照和行军 3h组 (P <0 0 5) ;5 0km/h行军 2h组NOS明显低于对照和其它行军时间组 (P <0 0 5)。结论 沙漠干热环境应激负重行军者血浆HSP2 7与NO及其NOS密切相关 。

Study on S-shaped characteristic of Francis reversible unit by on-site test and CFD simulation

The operation parameters （vibration, shaft displacement and pressure fluctuation） of No. 1 Francis reversible unit of Baoquan pumped-storage power station were measured on site in the no-load mode at net heads of 518.04, 522.01 and 530.38 m, re- spectively. The rotational speed fluctuations in the no-load mode at three net heads were beyond synchronization requirement with obvious S-shaped characteristic, and misaligned guide vanes （MGV） had to be put into use for synchronization. Further analysis demonstrated that the rotating frequency signal was generally dominant in vibration and shaft displacement mixing signal in the no-load mode, while the frequency domain was wide without an obvious main frequency in pressure fluctuation mixing signal. Besides, the SSTκ-ω turbulence model was adopted to simulate the four quadrant characteristic curves of Baoquan model pump-turbine at three gate openings, and the relative error between simulation results and model test data was within ±6%, indicating that the simulation method in this paper is feasible and S-shaped characteristic of the pump-turbine can be simulated with CFD method.

Opening angles and residual strains in normal rat trachea

The no-load state and zero-stress state of the normal rat trachea were analyzed. It was found that there exist compressive residual strains in the inner wall region of the rat trachea and tensile residual strains in the outer wall region. The fact that the opening angle of the rat trachea cut at the cartilaginous region is significantly larger than that cut at the muscular portion shows that residual strains exist mainly in the muscular region in the rat trachea. It was also indicated that the opening angles and residual strains expressed by cutting at the muscular portion are basically identical along longitudinal location and those expressed by cutting in the cartilaginous region tend to increase in the longitudinal direction in the normal rat, and that there exists quantitatively positive correlation between the opening angles and residual strains in rat trachea. The results will help to further understand the opening angles and residual strains in the trachea and study tracheal remodeling in response to mechanical environment.

在沙漠干热环境中负重行军者血浆中NO和NOS与生理应激的关系

目的探讨沙漠干热环境负重行军者NO和一氧化氮合酶(NOS)与生理应激的关系。方法 60名战士在沙漠干热环境中负重15 kg分别以3.5和5.0 km/h行军1、2、3 h,检测试验组和对照组战士血浆中NO含量和NOS活力、心律增值、肛温增值和积热指数。结果所有行军时间组NO(17.26~23.28μmol/L)含量均明显低于对照组(31.84μmol/L)(P<0.05),心率增值(7.6~23.9次/min)均明显高于对照(1.2次/min)(P<0.05)。15 kg负重3.5 km/h行军时,行军3 h组NO(17.26μmol/L)含量明显低于行军1 h组(22.62μmol/L)和2 h组(23.10μmol/L)(P<0.05);行军1 h组NOS(47.35 U/L)活力明显高于行军3 h组(40.90 U/L)和对照组(40.89 U/L)(P<0.05);行军3 h组肛温增值(0.17℃)明显高于行军1 h组(0.02℃)和对照组(0.00℃)(P<0.05);行军1和2 h组积热指数(-18.94^-18.31 kJ/m2)明显低于行军3 h组(22.67 kJ/m2)和对照组(0.41 kJ/m2)(P<0.05),行军3 h组积热指数明显高于对照组(P<0.05)。15 kg负重5.0 km/h行军时,行军2 h组NOS(39.44 U/L)活力明显低于对照组(40.89 U/L)和其他行军时间组(34.23~40.43U/L)(P<0.05);行军1 h组(23.9次/min)和3 h组(21.3次/min)心率增值明显高于行军2 h组(7.6次/min)(P<0.05);机体肛温随行军时间的延长而增高;各行军组积热指数(51.04~71.12 kJ/m2)明显高于对照组(0.41 kJ/m2)。结论在沙漠干热环境中行军者血浆中NO含量和NOS活力与热应激有关,沙漠干热环境劳动强度以不超过重度为宜,持续劳动时间不应超过2 h。

递增负荷运动对少年男篮运动员血浆NO代谢的影响

为探讨递增负荷运动过程中少年男篮血浆NO含量和NOS活性的变化规律,选取少年男篮运动员12名,普通健康少年学生12人作为对照组,同时进行递增负荷运动。测试结果表明:少年男篮组在安静时的NO的含量和NOS活性比普通少年组高(P<0.05);运动后即刻各组NO的含量和NOS活性均升高,男篮组升高率大于普通组;恢复期各组NO的含量均降低,男篮组的恢复速度大于普通组。说明运动可以提高人体血清内NO的含量以及NOS活性;在运动过程中,有训练史者调节NO代谢的能力增强。

慢性盐负荷诱导高血压大鼠胸主动脉重构作用

目的观察慢性盐负荷诱导高血压大鼠胸主动脉重构的影响并探讨其可能机制。方法雄性大鼠分为2组,分别采用4%高盐和0.4%低盐饮食持续诱导16周,每隔4周监测血压、尿量和尿钠;采集胸主动脉切片,观察病理变化,测量管壁厚度、管腔直径,比较管壁厚度/管腔直径比值;免疫组化法测定胸主动脉管壁转化生长因子β1(TGFβ1)、内皮型一氧化氮合酶(eNOS)的蛋白表达。结果观察期各周,高盐组收缩压、尿量及尿钠均高于低盐组,高盐摄入、大鼠周龄对血压变化有影响(P<0.05);2组大鼠胸主动脉管壁均随周龄增加逐渐增厚,管腔逐渐变狭窄;第8、12、16周时,高盐组胸主动脉管壁厚度分别为(117.0±8.8)、(124.7±8.8)、(168.1±32.7)μm,均高于低盐组(P<0.05或P<0.01);第4、8周时高盐组胸主动脉TGFβ1、eNOS表达明显增加,第12、16周时逐渐减少;各观察期内,高盐组TGFβ1表达的吸光度值分别为(11795.8±1079.4)、(17773.8±928.3)、(6019.4±433.4)、(5455.6±380.2);eNOS表达的吸光度值分别为(14970.1±1249.2)、(18236.6±2723.9)、(7201.9±1006.5)、(8068.2±1418.2),均高于低盐组(P<0.05或P<0.01)。结论慢性盐负荷可加重实验大鼠胸主动脉重构,盐负荷后大鼠胸主动脉局部TGFβ1含量的增加可能是其导致血管重构的原因之一。

不同运动负荷对大鼠股外肌一氧化氮合酶体系的影响

目的:测定不同运动负荷时大鼠股外肌组织中一氧化氮-一氧化氮合酶(NO-NOS)体系的各成分含量或活性的变化,探讨运动训练对股外肌的影响。方法:将60只雄性SD大鼠随机分为3组,即安静对照组、中等运动强度组、运动疲劳组,每组20只。对安静对照组大鼠进行常规饲养,不加任何干预,对中等运动强度组大鼠进行中等强度游泳训练,对运动疲劳组大鼠建立运动性疲劳模型。采用生化试剂盒测定各组大鼠末次训练后股外肌组织NO-NOS体系含量或活性。结果:与安静对照组比较,中等运动强度组大鼠股外肌组织中NO含量、总一氧化氮合酶(tNOS)、内皮型一氧化氮合酶(eNOS)、神经元型一氧化氮合酶(nNOS)、诱导型一氧化氮合酶(iNOS)活性水平均显著升高(P<0.05或P<0.01);运动疲劳组大鼠的股外肌组织NO含量,tNOS,eNOS,nNOS活性水平均无显著变化,其中NO含量,tNOS,nNOS活性水平有升高趋势。与中等运动强度组比较,运动疲劳组大鼠iNOS活性水平显著降低(P<0.05)。结论:股外肌组织中NO-NOS体系各成分不同运动负荷作用下会产生不同程度的变化,中等强度运动可导致股外肌组织中的NO含量和tNOS,eNOS,nNOS,iNOS活性的升高,而疲劳运动则有引起iNOS,eNOS活性降低的趁势。