scholarly journals A Method for Reducing Cogging Torque of Integrated Propulsion Motor

2019 ◽  
Vol 7 (7) ◽  
pp. 236
Author(s):  
Ou ◽  
Hu ◽  
Mao ◽  
Li
Keyword(s):  
Analytical Model ◽  
Torque Ripple ◽  
Optimal Size ◽  
Key Factors ◽  
Cogging Torque ◽  
Halbach Array ◽  
Sample Data ◽  
Before And After ◽  
Radial Thickness ◽  
Important Means

How to reduce the cogging torque of the integrated propeller motor is an important means to improve its noise performance because cogging torque is one of the key factors causing torque ripple. We proposed a method to reduce the cogging torque by optimizing the size of the Halbach array’s auxiliary pole. First, an analytical model for the airgap magnetic field of Halbach array based on different dimensions (including the circumference ratio and the radial thickness) of the auxiliary pole is given. Then the finite element method is used to verify the analytical model. On the basis, we calculated the cogging torque of different size of auxiliary poles as sample data by combining different circumference ratio and radial thickness. Furthermore, using the two-variable single-objective neural network genetic optimization algorithm based on Backpropagation (BP), we obtain the optimal size of the auxiliary pole. Finally, comparing the motor cogging torque and torque ripple before and after optimization indicated that the cogging torque and torque ripple are effectively reduced after optimizing the size of the auxiliary pole.

Performance analysis of magnetic gear with Halbach array for high power and high speed

2020 ◽  
Vol 64 (1-4) ◽  
pp. 959-967
Author(s):  
Se-Yeong Kim ◽  
Tae-Woo Lee ◽  
Yon-Do Chun ◽  
Do-Kwan Hong
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
High Power ◽  
High Speed ◽  
Torque Ripple ◽  
Eddy Current Loss ◽  
Element Analysis ◽  
Current Loss ◽  
Halbach Array ◽  
Magnetic Gear

In this study, we propose a non-contact 80 kW, 60,000 rpm coaxial magnetic gear (CMG) model for high speed and high power applications. Two models with the same power but different radial and axial sizes were optimized using response surface methodology. Both models employed a Halbach array to increase torque. Also, an edge fillet was applied to the radial magnetized permanent magnet to reduce torque ripple, and an axial gap was applied to the permanent magnet with a radial gap to reduce eddy current loss. The models were analyzed using 2-D and 3-D finite element analysis. The torque, torque ripple and eddy current loss were compared in both models according to the materials used, including Sm2Co17, NdFeBs (N42SH, N48SH). Also, the structural stability of the pole piece structure was investigated by forced vibration analysis. Critical speed results from rotordynamics analysis are also presented.

scholarly journals Design and Analysis of a Novel Axial-Radial Flux Permanent Magnet Machine with Halbach-Array Permanent Magnets

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3639
Author(s):  
Rundong Huang ◽  
Chunhua Liu ◽  
Zaixin Song ◽  
Hang Zhao
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Torque Ripple ◽  
Axial Flux ◽  
Element Analysis ◽  
Torque Density ◽  
Axial Forces ◽  
Halbach Array ◽  
Radial Flux ◽  
High Torque

Electric machines with high torque density are needed in many applications, such as electric vehicles, electric robotics, electric ships, electric aircraft, etc. and they can avoid planetary gears thus reducing manufacturing costs. This paper presents a novel axial-radial flux permanent magnet (ARFPM) machine with high torque density. The proposed ARFPM machine integrates both axial-flux and radial-flux machine topologies in a compact space, which effectively improves the copper utilization of the machine. First, the radial rotor can balance the large axial forces on axial rotors and prevent them from deforming due to the forces. On the other hand, the machine adopts Halbach-array permanent magnets (PMs) on the rotors to suppress air-gap flux density harmonics. Also, the Halbach-array PMs can reduce the total attracted force on axial rotors. The operational principle of the ARFPM machine was investigated and analyzed. Then, 3D finite-element analysis (FEA) was conducted to show the merits of the ARFPM machine. Demonstration results with different parameters are compared to obtain an optimal structure. These indicated that the proposed ARFPM machine with Halbach-array PMs can achieve a more sinusoidal back electromotive force (EMF). In addition, a comparative analysis was conducted for the proposed ARFPM machine. The machine was compared with a conventional axial-flux permanent magnet (AFPM) machine and a radial-flux permanent magnet (RFPM) machine based on the same dimensions. This showed that the proposed ARFPM machine had the highest torque density and relatively small torque ripple.

A Critical Assessment and Review of Artificial Intelligence in Facial Paralysis Analysis: Uncovering the Truth

FACE ◽  
2021 ◽  
pp. 273250162110228
Author(s):  
David T. Mitchell ◽  
David Z. Allen ◽  
Matthew R. Greives ◽  
Phuong D. Nguyen
Keyword(s):  
Artificial Intelligence ◽  
Facial Paralysis ◽  
Critical Assessment ◽  
Facial Emotion ◽  
Data Systems ◽  
Computer Algorithms ◽  
Future Directions ◽  
Sample Data ◽  
Before And After ◽  
Facial Reanimation

Machine learning is a rapidly growing subset of artificial intelligence (AI) which involves computer algorithms that automatically build mathematical models based on sample data. Systems can be taught to learn from patterns in existing data in order to make similar conclusions from new data. The use of AI in facial emotion recognition (FER) has become an area of increasing interest for providers who wish to quantify facial emotion before and after interventions such as facial reanimation surgery. While FER deep learning algorithms are less subjective when compared to layperson assessments, the databases used to train them can greatly alter their outputs. There are currently many well-established modalities for assessing facial paralysis, but there is also increasing interest in a more objective and universal measurement system to allow for consistent assessments between practitioners. The purpose of this article is to review the development of AI, examine its existing uses in facial paralysis assessment, and discuss the future directions of its implications.

scholarly journals Changes in the Portfolio Management and Construction under the Pandemic Era

2021 ◽  
Vol 275 ◽  
pp. 01005
Author(s):  
Ruipeng Tan
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Stock Returns ◽  
Financial Market ◽  
Portfolio Management ◽  
Portfolio Construction ◽  
Sample Data ◽  
Before And After ◽  
Reduce Risk ◽  
The Impact

This paper focuses on comparing portfolio management and construction before and after the coronavirus. First, this paper presents the importance of building up portfolios for investors to diversify their risks. Theories on portfolio management are discussed in this section to show how they have been developed to help on investing and reduce risk. Then, the paper moves on to show the impact of the pandemic on the financial market and portfolio management. Sample data on tech stock returns are collected to perform a Monte Carlo simulation on portfolio construction to find out the efficient portfolio before and after the COVID-19 outbreak. The efficient portfolio is build based on the Markowitz theory to find the combination. Comparisons between these portfolio constructions are made to find out the changes in portfolio management and construction under the pandemic era. In conclusion, this paper presents how pandemic has changed and impacted the investments and lists recommendations on future portfolio management and construction.

scholarly journals Is Organizing Knowledge Effective in Primary Education?

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Marisol Cueli ◽  
Ana Isabel Álvarez ◽  
Stephen Loew ◽  
Paloma González-Castro ◽  
Celestino Rodríguez
Keyword(s):  
Primary Education ◽  
Teaching And Learning ◽  
Reading Skills ◽  
Lexical Processing ◽  
Control Group ◽  
Traditional Teaching ◽  
Key Factors ◽  
Early School ◽  
Before And After ◽  
Key Aspects

The acquisition of reading comprehension abilities and written expression is one of the key factors among learning processes in which students show many difficulties. For this reason, it is necessary to implement effective intervention strategies from early school years. The program EPI.com is aimed at improving lexical, semantic, and syntactic processes related to the reading process. This work aims to analyze the efficiency of EPI.com in years 1&2 of Primary Education. Participants in the research were 62 students (ages 6–8), who were assigned to an Experimental Group (EG; 38 students receiving the EPI.com intervention) and a Control Group (CG; 24 following traditional teaching and learning methods). The Illinois Test of Psycholinguistic Abilities and the Peabody test were applied before and after the intervention was carried out. Results showed that the strategy was effective in EG in improving the psycholinguistic aspects measured by the ITPA, with better results in the variables related to syntactic and lexical processing. Taking the results into account, it was concluded that EPI.com allows students to improve the abilities relating to reading skills. Also, the results highlight the need to incorporate interventions aimed at favoring maturation in some key aspects at early ages.

Differential sympathetic nerve responses to nitric oxide synthase inhibition in anesthetized rats

1995 ◽  
Vol 269 (4) ◽  
pp. R807-R813 ◽  
Author(s):  
T. Hirai ◽  
T. I. Musch ◽  
D. A. Morgan ◽  
K. C. Kregel ◽  
D. E. Claassen ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Sympathetic Nerve ◽  
Sprague Dawley ◽  
Arterial Blood ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Important Means ◽  
Nos Inhibitor ◽  
Oxide Synthase ◽  
Tonic Excitation

Recent studies have suggested that the interaction between the sympathetic nervous system and nitric oxide (NO) or nitrosyl factors may be an important means by which arterial blood pressure is regulated. We investigated whether NO synthase (NOS) inhibition modulates basal sympathetic nerve discharge (SND) in baroreceptor-innervated and -denervated, chloralose-anesthetized Sprague-Dawley rats. We recorded mean arterial pressure (MAP), renal SND, and lumbar SND before and after administration of the NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 20 mg/kg iv). Two minutes after L-NAME administration in baroreceptor-innervated rats, MAP increased (+23 +/- 3 mmHg), whereas renal (-45 +/- 6%, n = 7) and lumbar (-35 +/- 2%, n = 6) SND significantly decreased from control levels. These changes persisted for up to 20 min after L-NAME administration. In baroreceptor-denervated rats, L-NAME increased MAP (+40 +/- 6 mmHg) and decreased lumbar SND (n = 7) (-37 +/- 10% from control at 20 min post-L-NAME). In contrast, renal SND progressively increased (+33 +/- 8% at 20 min post-L-NAME) from control after L-NAME administration in baroreceptor-denervated rats (n = 7). These results demonstrate that NOS inhibition can produce nonuniform changes in SND in baroreceptor-denervated rats and suggest that endogenous nitrosyl factors provide tonic excitation to lumbar SND, whereas they provide a tonic restraint to renal SND.

How to Start or Improve a KM System in a Hospital or Healthcare Organization

2011 ◽  
pp. 1395-1398
Author(s):  
A.H. Rubenstein ◽  
E. Geisler
Keyword(s):  
Knowledge Management ◽  
Health Sector ◽  
Healthcare Organization ◽  
Management Systems ◽  
Knowledge Management Systems ◽  
Key Factors ◽  
Important Means

One of the key factors that distinguishes enterprises of the 21s t Century is the emphasis on knowledge and information. Knowledge management is an important means by which organizations can better manage information, and more importantly, knowledge. Unlike other techniques, knowledge management is not always easy to define, because it encompasses a range of concepts, management tasks, technologies, and practices, all of which come under the umbrella of the knowledge management. This chapter deals with two aspects of knowledge management systems: (a) why KM systems are needed, and (b) how to get started on designing and rolling out a new or improved KM system. The inferences are drawn from the direct experiences the authors have had during their academic and consulting activities in many health sector organizations.

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