PM Shape Research Articles

Chemically speciated mass size distribution, particle density, shape and origin of non-refractory PM<sub>1</sub> measured at a rural background site in central Europe

Abstract. Seasonal variability of non-refractory PM1 (NR-PM1) was studied at a rural background site (National Atmospheric Observatory Košetice – NAOK) in the Czech Republic to investigate the effect of regional and long-range atmospheric transport in central Europe. NR-PM1 measurements were performed by compact time-of-flight aerosol mass spectrometry (C-ToF-AMS), and the chemically speciated mass size distributions, density, shape, and origin were discussed. Average PM1 concentrations, calculated as the sum of the NR-PM1 and the equivalent black carbon (eBC) concentrations measured by an aethalometer (AE), were 8.58 ± 3.70 µg m−3 in summer and 10.08 ± 8.04 µg m−3 in winter. Organics were dominant during both campaigns (summer/winter: 4.97 ± 2.92/4.55 ± 4.40 µg m−3), followed by SO42-in summer (1.68 ± 0.81/1.36 ± 1.38 µg m−3) and NO3- in winter (0.67 ± 0.38/2.03 ± 1.71 µg m−3). The accumulation mode dominated the average mass size distribution during both seasons, with larger particles of all species measured in winter (mode diameters: Org: 334/413 nm, NO3-: 377/501 nm, SO42-: 400/547 nm, and NH4+: 489/515 nm) indicating regional and long-range transport. However, since the winter aerosols were less oxidized than the summer aerosols (comparing fragments f44 and f43), the importance of local sources in the cold part of the year was still enough to be considered. Although aged continental air masses from the south-east (SE) were rare in summer (7 %), they were related to the highest concentrations of PM1, eBC, and all NR-PM1 species, especially SO42- and NH4+. In winter, slow continental air masses from the south-west (SW) (44 %) were linked to inversion conditions over central Europe and were associated with the highest concentrations among all NR-PM1 species as well as PM1 and eBC. Average PM1 material density (ρm) corresponded to higher inorganic contents in both seasons (summer: ∼ 1.30 g cm−3 and winter: ∼ 1.40 g cm−3). During episodes of higher mass concentrations ρm ranged from 1.30–1.40 g cm−3 in summer and from 1.30–1.50 g cm−3 in winter. The dynamic shape factors (χ) decreased slightly with particle mobility diameter (Dm) in both seasons. This study provides insights into the seasonal effects and air mass variability on aerosol particles, focusing on episodes of high mass and number concentrations measured at a central European rural background site.

Performances analysis of interior permanent magnet motors having different rotor iron pole shapes

<p><span lang="EN-US">Interior permanent magnet motors (IPMMs) have been increasing in popularity, since the emergence of permanent magnet material with high energy products, i.e. rare earth permanent magnet material. This paper analyses the performances of IPMMs having different rotor iron pole shapes including eccentric, sinusoidal and sinusoidal with 3th order harmonic injected rotor pole arc shapes IPMMs. Cogging torque, static torque, torque ripple, torque-speed and power-speed curves of the mentioned motors have been compared. It must be noted that the mentioned motors have been designed with the same stator, PM shape and the same dimensions, in order to highlight the effect of the rotor pole arc shape on the performance of the such motors. Two-dimensional (2D) finite element analysis (FEA) has been utilized to design and analyze the mentioned machines. It has been found that rotor iron pole shape of the IPM has notably influence on the machine performance, practically on output electromagnetic torque and its ripple. The highest value of average electromagnetic torque as well as torque capability in the constant torque reign is delivered by 3th order harmonic injected rotor pole arc shapes machine, while the lowest torque ripple is obtained by the sinusoidal rotor pole arc machine.</span></p>

Screw rolling between moving and fixed axodes traced by lower-mobility parallel mechanism

Analogous to the null space map, this work proposes a “unit space map” to identify the generalized transmission wrench screw, which plays an important role in the general method determining the multi-parameter instantaneous screw of lower-mobility parallel mechanism which can be expressed as the linear combination of several proper basis screws of a twist screw system. Based on the fundamental equation, the screw rolling between moving and fixed axodes is decomposed into the linear superposition of several coupling screw rollings associated with several pairs of moving and fixed envelope axodes of proper basis screw, respectively. Moreover, several numerical examples of SP+SPR+SPU and 3-UPU parallel mechanisms are presented to verify the linear superposition, unit space map, and the method determining the multi-parameter instantaneous screw. Finally, the graph of the velocity-ratio parameter is employed to analyze the influence of input velocities on the axode shape of the 3-UPU PM when it undergoes two motion patterns: constant velocity-ratio and variable velocity-ratio.

Reduction of Torque Ripples in Multi-Stack Slotless Axial Flux Machine by Using Right Angled Trapezoidal Permanent Magnet

The aim of this paper is to design, analyze and optimize the “Multi-Stack Slotless Axial Flux Switching Permanent Magnet Machine”. In the design process, mathematical models are implemented, and the Finite Element Method (FEM) is performed to analyze the machine performances. The paper aims to minimize the occurrence of cogging torque and torque ripple in the multi-stack slotless stator AFPM machine. As a consequence, it reduces the vibrations in the machine and increases its life span. Multi-stack slotless stator AFPM machine with a right-angled trapezoid-shaped PM is proposed and comparison is done with conventional shape AFPM machine. In order to examine the performance of multi-stack slotless stator AFPM machine Finite Element Analysis (FEA) is used. To further enhance the characteristics of the designed machine with the proposed right-angled PM shape, optimization is done by considering inner and outer pole pitch as the design variables. In optimization process, krigging method assigned with Latin Hyper-cube Sampling and a genetic algorithm (GA) is performed due to suitability with non-linear data. Then, finite element analysis by JMAG-Designer is performed to verify the results. It is determined that optimized model has achieved 65% reduction in torque ripples as compared with the conventional design. Hence, this work attempts to optimize the performance of the AFPM machine.

Performance Improvement of Dual Stator Axial Flux Spoke Type Permanent Magnet Vernier Machine

This paper presents performance improvement of dual stator axial-flux spoke type permanent magnet vernier machine (DSAFST-PMVM), which has the capability to generate high torque at a lower speed due to magnetic gearing effect. Flux focusing effect is created by means of dual stator single rotor topology with spoke type permanent magnets. It is best suitable for high-performance industrial applications such as servo motors, robot arms, wind power, electric vehicles, and elevator applications. A PM shape is proposed in this paper which has notches in such a way that it produces discrete skew effect which reduces the cogging torque and torque ripples. Optimization of magnet shape is done to make the optimized model more competitive than the proposed and basic models. Main parameters such as back emf, cogging torque, torque ripples, electromagnetic torque, VTHD, airgap flux densities, flux density distribution, power factor, and power of the machine are compared among the basic model, proposed model, and optimized models. The comparative analysis is done by using the time stepped 3D finite element method.

Design and Analysis of a Multi-Flux-Modulated Permanent Magnet Motor

In this paper, a new multiple flux-modulated permanent magnet (M-FMPM) motor is proposed, where three flux modulations and two modulation forms are implemented to enhance the torque density. Firstly, a new topology of the motor and the corresponding multi-flux-modulation theory are presented. And thus the flux modulation forms can be enriched and the torque performance can also be further effectively improved. Then, according to the proposed geometric model, the shape of PM is artfully designed to obtain the desirable torque performance. Based on the finite element method (FEM), the magnetic distributions, airgap harmonic group are analyzed, and torque capability are compared between the forms of multi-flux-modulation (MFM) and single-flux-modulation (SFM). Finally, both the theoretical analysis and finite element analysis results verify the effectiveness of the proposed multi-flux-modulation theory and the M-FMPM motor.

Optimization of palm oil biodiesel blends and engine operating parameters to improve performance and PM morphology in a common rail direct injection diesel engine

In this paper, the characteristics of five palm oil biodiesel blends (B0, B10, B20, B30, and B100) have been tested in a common rail direct injection (CRDI) diesel engine with various EGR rates and pilot injection timings under 25% and 75% engine loads. The following were evaluated: combustion characteristics, including in-cylinder pressure, heat release rate (HRR), and mass fraction burned (MFB); engine performance parameters, including brake specific fuel consumption (BSFC) and coefficient of variation of the indicated mean effective pressure (COVimep); and emission characteristics, including CO, HC, NOx, PM and its morphology. By considering the combustion and emission characteristics, we found that the diesel engine fueled with B30 blend fuel with a 10% EGR rate, or with a pilot injection timing of 24° CA BTDC, can effectively reduce PM emissions and simultaneously keep NOx emissions at a low level. In addition, we found that the variations of the engine load and EGR rate, as well as the biodiesel blend ratio, have direct impacts on the PM particle diameter, shape, and other morphology.

Викиди зважених часток від повітряних суден під час експлуатації в межах аеропорту

Мета: Викиди авіадвигунів в межах приземного граничного шару під час етапів зльоту та посадки призводять до значного погіршення якості повітря в межах аеропорту та на прилеглих житлових територіях. На сьогодні, основними об'єктами забруднення повітря в аеропортах є оксиди азоту і зважені частки (ЗЧ10, ЗЧ2.5 і ультрадісперсні ЗЧ), які спричиняють виникнення відповідно фотохімічного смогу та туману з наступними несприятливими наслідками для здоров’я населення. Аналіз результатів інвентаризації викидів ЗЧ у головних аеропортах Європи вказує на домінантність викидів авіадвигунів та допоміжної силової установки. Стаття спрямована на аналіз теоретичних та експериментальних досліджень із розподілу часток за розміром у викидах авіадвигунів, а також особливостей їх морфології та внутрішньої структури, оскільки зазначені властивості мають важливе значення для розуміння потенційного впливу ЗЧ на здоров'я населення. Стаття також надає детальний опис основних методів розрахунку викидів та дисперсії ЗЧ від авіадвигуна протягом злітно-посадкового циклу повітряного судна. Методи: аналітичне розв'язання рівняння атмосферної дифузії використовується для розрахунку максимальної концентрації ЗЧ від точкового джерела емісії. Концентрація ЗЧ змінюється обернено пропорційно швидкості вітру u1 і прямо пропорційно вертикальній складовій коефіцієнту турбулентного обміну k1/u1. Оцінка концентрації нелетучої ЗЧ враховує розмір і форму ЗЧ. Модель PolEmiCa обчислює розподіл фракцій ЗЧ у викидах від авіадвигунів та ДСУ (висота установки H = 4,5 м для Ту-154). Результати: Максимальна концентрація ЗЧ у викидах ДСУ вища, а відповідна відстань менша, у порівнянні з випадком для газу. Полідисперсність призводить до розподілу максимумів концентрацій в просторі для окремих фракцій за напрямком вітру, що призводить до зменшення загальної максимальної концентрації. Обговорення: Хоча емісія ДСУ сягає рівня авіадвигунів, викиди ДСУ не сертифіковані ІСАО. Отже, зазначена проблема є актуальною для місцевої якості повітря, зокрема для розробки моделі та визначення методів виявлення складової викидів авіадвигунів і ДСУ у загальне забруднення повітря аеропорту ЗЧ.

Design of Ultrahigh Speed Axial-Flux Permanent Magnet Machine With Sinusoidal Back EMF for Energy Storage Application

This paper focuses on the design and the analysis of an ultrahigh speed axial-flux permanent magnet (AFPM) machine for an aerospace flywheel energy storage system. The superiority of the proposed AFPM machine is the material-efficient PM shape, which contributes to obtain a sinusoidal back electromotive force (back EMF) and, hence, reduces the torque pulsations of the machine such as torque ripple. The harmonics present in back EMF have a large influence on iron loss and torque pulsations, which are always unacceptable in the applications involving the speed as high as 1 000 000 r/min. Analytical modeling is first performed to determine the PM shape for the proposed models. Then, the advantages of the proposed models are verified by comparing with the basic model with the conventional ring-shaped PMs using the 3-D finite-element method. The results show that the proposed models have a nearly ideal sinusoidal back-EMF waveform that significantly reduces the torque ripples compared with the basic model.

Influence of Edge Permanent-Magnet Shape on the Performance of an Arc-Linear Permanent-Magnet Synchronous Machine

A kind of arc-linear permanent-magnet synchronous machine (AL-PMSM) used for scanning system, which requires high positioning accuracy, high response performance, and wide scanning range, is proposed and researched. Due to the finite length of stator core and rotor core, the AL-PMSM suffers from stator end effect and rotor end effect. The cogging torque caused by stator end effect can be reduced significantly by stator length optimization, PM shape optimization, and so on. The cogging torque caused by rotor end effect is mainly analyzed and reduced in this paper. The rotor end effect occurs when the rotor end region is close to the stator end region and the influence of rotor end effect is mainly two pole pitches. In order to reduce the cogging torque caused by rotor end effect, shape optimization of the edge permanent magnets, especially the first edge PM and second edge PM, is researched and compared. After optimization, the smooth scanning range is improved from ±47.8° to ±56.2° by 17.6% with the peak-to-peak value of cogging torque less than 0.19 Nm. The effectiveness of the optimization method is verified by the finite-element method.

Optimization of Permanent Magnet Surface Shapes of Electric Motors for Minimization of Cogging Torque Using FEM

A novel algorithm which minimizes the cogging torque of surface-mounted permanent magnet (SPM) brushless motors by optimizing the surface profile of PM is presented. An efficient strategy for using finite element method (FEM) is proposed to calculate the cogging torque of PM motors with different PM shape designs. Compared with the use of general FEM, the computing time with this proposed method is significantly reduced, which is only 0.017% of that required by the former. Because of the considerable reduction of computing time in the magnetic field analysis of PM motors, it becomes feasible to use genetic algorithm (GA) to optimize the PM shape in order to realize cogging torque minimization. A numerical experiment is used to validate the proposed method.