scholarly journals Impact of Tolerances on the Cogging Torque of Tooth-Coil-Winding PMSMs with Modular Stator Core by Means of Efficient Superposition Technique

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1594
Author(s):  
Carlos Madariaga ◽  
Werner Jara ◽  
Danilo Riquelme ◽  
Gerd Bramerdorfer ◽  
Juan A. Tapia ◽  
...  
Keyword(s):  
Angular Displacement ◽  
Full Range ◽  
Tolerance Analysis ◽  
Stator Core ◽  
Cogging Torque ◽  
Torque Generation ◽  
Dimensional Parameters ◽  
Superposition Technique ◽  
Coil Winding ◽  
The Impact

This paper analyzes the impact of manufacturing tolerances on the cogging torque of a 24-slot 28-pole tooth-coil-winding permanent magnet synchronous machine with a modular stator core (TCW-MPMSM). Dimensional tolerances and asymmetries associated with the modular topology are studied by means of finite element simulations in order to identify key parameters that increase the cogging torque above the expected values of a faultless machine. Among five selected dimensional parameters, it was found that angular displacement, radial displacement, and tooth–tip width deviations of the stator segments have the most significant impact on the cogging torque. Considering these three key parameters, a full-range tolerance analysis is carried out by means of a proposed superposition-based approach, evaluating all possible combinations of typical deviation values. It is concluded that the cogging torque increment, generated by tolerances, is relatively independent of the faultless tooth–tip width of the stator segments and the arc-to-pole ratio. Robustness of the TCW-MPMSM, regarding cogging torque generation, depends on both the tightness of the tolerances handled in the manufacturing process and the rated cogging torque: the lower the cogging torque of the ideal machine, the less robust is the machine and, therefore, manufacturing imperfections will be required to be tightened.

scholarly journals Analysis of the stator topology impact on cogging torque for surface permanent magnet motor

2015 ◽  
Vol 34 (2) ◽  
pp. 456-474 ◽  
Author(s):  
Lidija Petkovska ◽  
Goga Cvetkovski ◽  
Paul Lefley
Keyword(s):  
Permanent Magnet ◽  
Generic Model ◽  
The Novel ◽  
Permanent Magnet Motor ◽  
Stator Core ◽  
Cogging Torque ◽  
Content Type ◽  
Slot Opening ◽  
The Impact ◽  
Static Torque

Purpose – The purpose of this paper is to investigate the impact of the stator core design for a surface permanent magnet motor (SPMM) on the cogging torque profile. The objective is to show how the cogging torque of this type of motor can be significantly reduced by implementing an original compound technique by skewing stator slots and inserting wedges in the slot openings. Design/methodology/approach – At the beginning generic model of a SPMM is studied. By using FEA, for this idealised assembly, characteristics of cogging and electromagnetic torque are simulated and determined for one period of their change. Afterwards, actual stator design of the original SPMM is described. It is thoroughly investigated and the torque characteristics are compared with the generic ones. While the static torque is slightly decreased, the peak cogging torque is almost doubled and the curve exhibits an uneven profile. The first method for cogging torque reduction is skewing the stator stack. The second technique is to insert wedges of SMC in the slot openings. By using 2D and 2 1/2D numerical experiment cogging curves are calculated and compared. The best results are achieved by combining the two techniques. The comparative analyses of the motor models show the advantages of the proposed novel stator topology. Findings – It is presented how the peak cogging torque can be substantially decreased due to changes in the stator topology. The constraint is to keep the same stator lamination. By skewing stator stack for one slot pitch 10° the peak cogging torque is threefold reduced. The SMC wedges in slot opening decrease the peak cogging almost four times. The novel stator topology, a combination of the former ones, leads to peak cogging of respectable 0.182 Nm, which is reduced for 7.45 times. Originality/value – The paper presents an original compound technique for cogging torque reduction, by combining the stator stack skewing and inserting SMC wedges in the slot openings.

Unfunded Public Employee Health Care Benefits and GASB No. 45

2007 ◽  
Vol 21 (3) ◽  
pp. 245-263 ◽  
Author(s):  
Elizabeth K. Keating ◽  
Eric S. Berman
Keyword(s):  
Health Care ◽  
Financial Reporting ◽  
Full Range ◽  
Financial Reports ◽  
Employment Benefits ◽  
Care Plans ◽  
Advantages And Disadvantages ◽  
Government Accounting ◽  
The Government ◽  
The Impact

The Government Accounting Standards Board (GASB) recently released Statement No. 45, Accounting and Financial Reporting by Employers for Post-Employment Benefits Other Than Pensions and its companion Statement No. 43 for pooled stand-alone health care plans, which will profoundly affect American governmental finance. The goal of this article is to encourage governments to consider carefully a full range of options in funding and restructuring other post-employment benefits (OPEB). This article will review Statement No. 45's potential impact on governments and review existing disclosures in financial reports as well as bond offering statements. The article will discuss the statement's impact on budgets and governmental operations, including collective bargaining. Funding options under Statement No. 45 will be detailed, including the advantages and disadvantages of irrevocable trusts and OPEB bonds. The article will also discuss the impact of Medicare Part D subsidies received by governments, as well as the bond rating implications of policy decisions surrounding OPEB. As the largest government entities are just now implementing GASB Statement No. 45, estimates of the magnitude of unfunded OPEB liabilities are limited as are the strategies likely to be adopted to cover these obligations. This article offers a summary of the unfunded OPEB liabilities reported by states and major cities and suggests some measures for assessing the ability of these entities to address these costs.

High-Resolution Climate Change Impact Analysis on Expected Future Water Availability in the Upper Jordan Catchment and the Middle East

2014 ◽  
Vol 15 (4) ◽  
pp. 1517-1531 ◽  
Author(s):  
Gerhard Smiatek ◽  
Harald Kunstmann ◽  
Andreas Heckl
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Water Availability ◽  
Impact Analysis ◽  
River Flow ◽  
Climate Model ◽  
Mesoscale Model ◽  
Global Climate Model ◽  
Full Range ◽  
The Impact

Abstract The impact of climate change on the future water availability of the upper Jordan River (UJR) and its tributaries Dan, Snir, and Hermon located in the eastern Mediterranean is evaluated by a highly resolved distributed approach with the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) run at 18.6- and 6.2-km resolution offline coupled with the Water Flow and Balance Simulation Model (WaSiM). The MM5 was driven with NCEP reanalysis for 1971–2000 and with Hadley Centre Coupled Model, version 3 (HadCM3), GCM forcings for 1971–2099. Because only one regional–global climate model combination was applied, the results may not give the full range of possible future projections. To describe the Dan spring behavior, the hydrological model was extended by a bypass approach to allow the fast discharge components of the Snir to enter the Dan catchment. Simulation results for the period 1976–2000 reveal that the coupled system was able to reproduce the observed discharge rates in the partially karstic complex terrain to a reasonable extent with the high-resolution 6.2-km meteorological input only. The performed future climate simulations show steadily rising temperatures with 2.2 K above the 1976–2000 mean for the period 2031–60 and 3.5 K for the period 2070–99. Precipitation trends are insignificant until the middle of the century, although a decrease of approximately 12% is simulated. For the end of the century, a reduction in rainfall ranging between 10% and 35% can be expected. Discharge in the UJR is simulated to decrease by 12% until 2060 and by 26% until 2099, both related to the 1976–2000 mean. The discharge decrease is associated with a lower number of high river flow years.

Compressor Performance and Operability in Swirl Distortion

2010 ◽  
Author(s):  
Yogi Sheoran ◽  
Bruce Bouldin ◽  
P. Murali Krishnan
Keyword(s):  
Gas Turbine ◽  
Complex Geometry ◽  
Full Range ◽  
Axial Compressor ◽  
Cfd Model ◽  
Generator System ◽  
Sliding Mesh ◽  
Wide Range ◽  
Compressor Performance ◽  
The Impact

Inlet swirl distortion has become a major area of concern in the gas turbine engine community. Gas turbine engines are increasingly installed with more complicated and tortuous inlet systems, like those found on embedded installations on Unmanned Aerial Vehicles (UAVs). These inlet systems can produce complex swirl patterns in addition to total pressure distortion. The effect of swirl distortion on engine or compressor performance and operability must be evaluated. The gas turbine community is developing methodologies to measure and characterize swirl distortion. There is a strong need to develop a database containing the impact of a range of swirl distortion patterns on a compressor performance and operability. A recent paper presented by the authors described a versatile swirl distortion generator system that produced a wide range of swirl distortion patterns of a prescribed strength, including bulk swirl, twin swirl and offset swirl. The design of these swirl generators greatly improved the understanding of the formation of swirl. The next step of this process is to understand the effect of swirl on compressor performance. A previously published paper by the authors used parallel compressor analysis to map out different speed lines that resulted from different types of swirl distortion. For the study described in this paper, a computational fluid dynamics (CFD) model is used to couple upstream swirl generator geometry to a single stage of an axial compressor in order to generate a family of compressor speed lines. The complex geometry of the analyzed swirl generators requires that the full 360° compressor be included in the CFD model. A full compressor can be modeled several ways in a CFD analysis, including sliding mesh and frozen rotor techniques. For a single operating condition, a study was conducted using both of these techniques to determine the best method given the large size of the CFD model and the number of data points that needed to be run to generate speed lines. This study compared the CFD results for the undistorted compressor at 100% speed to comparable test data. Results of this study indicated that the frozen rotor approach provided just as accurate results as the sliding mesh but with a greatly reduced cycle time. Once the CFD approach was calibrated, the same techniques were used to determine compressor performance and operability when a full range of swirl distortion patterns were generated by upstream swirl generators. The compressor speed line shift due to co-rotating and counter-rotating bulk swirl resulted in a predictable performance and operability shift. Of particular importance is the compressor performance and operability resulting from an exposure to a set of paired swirl distortions. The CFD generated speed lines follow similar trends to those produced by parallel compressor analysis.

scholarly journals Damping Studies on PMLG-Based Wave Energy Converter under Oceanic Wave Climates

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 920
Author(s):  
Yue Hong ◽  
Irina Temiz ◽  
Jianfei Pan ◽  
Mikael Eriksson ◽  
Cecilia Boström
Keyword(s):  
Wave Energy ◽  
Energy Production ◽  
Full Range ◽  
Electrical Power ◽  
Damping Coefficient ◽  
Irregular Wave ◽  
Ocean Wave Energy ◽  
Optimal Damping ◽  
The Impact

Wave energy converters (WECs), which are designed to harvest ocean wave energy, have recently been improved by the installation of numerous conversion mechanisms; however, it is still difficult to find an appropriate method that can compromise between strong environmental impact and robust performance by transforming irregular wave energy into stable electrical power. To solve this problem, an investigation into the impact of varied wave conditions on the dynamics of WECs and to determine an optimal factor for WECs to comply with long-term impacts was performed. In this work, we researched the performance of WECs influenced by wave climates. We used a permanent magnet linear generator (PMLG)-based WEC that was invented at Uppsala University. The damping effect was first studied with a PMLG-type WEC. Then, a group of sea states was selected to investigate their impact on the power production of the WEC. Two research sites were chosen to investigate the WEC’s annual energy production as well as a study on the optimal damping coefficient impact. In addition, we compared the WEC’s energy production between optimal damping and constant damping under a full range of sea states at both sites. Our results show that there is an optimal damping coefficient that can achieve the WEC’s maximum power output. For the chosen research sites, only a few optimal damping coefficients were able to contribute over 90% of the WEC’s annual energy production. In light of the comparison between optimal and constant damping, we conclude that, for specific regions, constant damping might be a better choice for WECs to optimize long-term energy production.

scholarly journals A Design Method for the Cogging Torque Minimization of Permanent Magnet Machines with a Segmented Stator Core Based on ANN Surrogate Models

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1880
Author(s):  
Elia Brescia ◽  
Donatello Costantino ◽  
Paolo Roberto Massenio ◽  
Vito Giuseppe Monopoli ◽  
Francesco Cupertino ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Design Method ◽  
Heuristic Approach ◽  
Topological Optimization ◽  
Permanent Magnet Machines ◽  
Stator Core ◽  
Cogging Torque ◽  
Design Formula ◽  
Harmonic Components

Permanent magnet machines with segmented stator cores are affected by additional harmonic components of the cogging torque which cannot be minimized by conventional methods adopted for one-piece stator machines. In this study, a novel approach is proposed to minimize the cogging torque of such machines. This approach is based on the design of multiple independent shapes of the tooth tips through a topological optimization. Theoretical studies define a design formula that allows to choose the number of independent shapes to be designed, based on the number of stator core segments. Moreover, a computationally-efficient heuristic approach based on genetic algorithms and artificial neural network-based surrogate models solves the topological optimization and finds the optimal tooth tips shapes. Simulation studies with the finite element method validates the design formula and the effectiveness of the proposed method in suppressing the additional harmonic components. Moreover, a comparison with a conventional heuristic approach based on a genetic algorithm directly coupled to finite element analysis assesses the superiority of the proposed approach. Finally, a sensitivity analysis on assembling and manufacturing tolerances proves the robustness of the proposed design method.

Biblical Criticism

2021 ◽  
Author(s):  
Richard Briggs
Keyword(s):  
21St Century ◽  
Full Range ◽  
Biblical Criticism ◽  
Early 21St Century ◽  
Authorial Intention ◽  
The Bible ◽  
Interpretive Method ◽  
Interpretive Practices ◽  
History Of Biblical Interpretation ◽  
The Impact

The Bible as a text can be read with or without reference to its compilation as a theologically constructed collection of sacred Jewish and Christian books. When read without such framing concerns, it may be approached with the full range of literary and theoretical interpretive tools and read for whatever purpose readers value or wish to explore. Less straightforwardly, in the former case where framing concerns come into play, the Bible is both like and unlike any other book in the way that its very nature as a “canon” of scripture is related to particular theological and religious convictions. Such convictions are then in turn interested in configuring the kinds of readings pursued in certain ways. Biblical criticism has undergone many transformations over the centuries, sometimes allowing such theological convictions or practices to shape the nature of its criticism, and at other times—especially in the modern period—tending to relegate their significance in favor of concerns with interpretive method, and in particular questions about authorial intention, original context, and interest in matters of history (either in the world behind the text, or in the stages of development of the text itself). From the middle of the 20th century onwards the interpretive interests of biblical critics have focused more on certain literary characteristics of biblical narratives and poetry, and also a greater theological willingness to engage the imaginative vision of biblical texts. This has resulted in a move toward a theological form of criticism that might better be characterized as imaginative and invites explicit negotiation of readers’ identities and commitments. A sense of the longer, premodern history of biblical interpretation suggests that some of these late 20th- and early 21st-century emphases do themselves have roots in the interpretive practices of earlier times, but that the Reformation (and subsequent developments in modern thinking) effectively closed down certain interpretive options in the name of better ordering readers’ interpretive commitments. Though not without real gains, this narrowing of interpretive interests has resulted in much of the practice of academic biblical criticism being beholden to modernist impulses. Shifts toward postmodern emphases have been less common on the whole, but the overall picture of biblical criticism has indeed changed in the 21st century. This may be more owing to the impact of a renewed appetite for theologically imaginative readings among Christian readers, and also of the refreshed recognition of Jewish traditions of interpretation that pose challenging framing questions to other understandings.

Adaptation and Psychometric Evaluation of the Parenting Concerns Questionnaire—Advanced Disease

2021 ◽  
pp. 104990912110498
Author(s):  
Eliza M. Park ◽  
Mian Wang ◽  
Savannah M. Bowers ◽  
Anna C. Muriel ◽  
Paula K. Rauch ◽  
...  
Keyword(s):  
Functional Status ◽  
Advanced Cancer ◽  
Internal Consistency ◽  
Convergent Validity ◽  
Advanced Disease ◽  
Full Range ◽  
Psychometric Evaluation ◽  
Face Validity ◽  
Concept Elicitation ◽  
The Impact

Purpose: When patients with advanced cancer have minor children (age < 18), their health-related quality of life is closely linked to their concerns about the impact of progressive illness and death on their children. The Parenting Concerns Questionnaire (PCQ), a validated measure for parents with cancer, does not capture the full range of concerns in advanced cancer. The aim of this was study was to adapt and establish psychometrics for the PCQ for advanced disease (PCQ-AD). Methods: After generating an initial item-bank, we conducted concept elicitation interviews with clinicians (n = 8) and cognitive interviews with patients (n = 23) for face validity. New items addressed concerns about impact of parental death, making every moment count, communication, and financial impact of cancer on children. We administered 21 candidate items to 151 parents with advanced cancer. We conducted confirmatory factor analysis (CFA), calculated internal consistency, and assessed convergent and known-groups validity. Results: We removed 8 redundant items due to residual covariation between items. CFA of the 13-item PCQ-AD demonstrated satisfactory fit (CFI = 0.971, TLI = 0.966, RMSEA = 0.081) and high internal consistency (Cronbach’s alpha = 0.94, composite reliability = 0.95). The PCQ-AD demonstrated convergent validity and known-groups validity; patients with poor functional status reported higher scores than patients with better functional status (Cohen’s d = 0.56, p = 0.002). Conclusion: Adaptation of the PCQ yielded the addition of constructs important in advanced cancer. The PCQ-AD appears to be a reliable and valid measure of parenting concerns in advanced cancer, but future studies are needed to examine measure performance in diverse populations and responsiveness of the PCQ-AD to interventions.

scholarly journals Q-Learning Neural Controller for Steam Generator Station in Micro Cogeneration Systems

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5334
Author(s):  
Krzysztof Lalik ◽  
Mateusz Kozek ◽  
Szymon Podlasek ◽  
Rafał Figaj ◽  
Paweł Gut
Keyword(s):  
Numerical Model ◽  
Control Systems ◽  
Steam Generator ◽  
Full Range ◽  
Combustion Process ◽  
Liquid Fuels ◽  
Control Algorithms ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
The Impact

This article presents the results of the optimization of steam generator control systems powered by mixtures of liquid fuels containing biofuels. The numerical model was based on the results of experimental research of steam generator operation in an open system. The numerical model is used to build control algorithms that improve performance, increase efficiency, reduce fuel consumption and increase safety in the full range of operation of the steam generator and the cogeneration system of which it is a component. In this research, the following parameters were monitored: temperature and pressure of the circulating medium, exhaust gas temperature, oxygen content in exhaust gas, percentage control of oil burner power. Two methods of controlling the steam generator were proposed: the classic one, using the PID regulator, and the advanced one, using artificial neural networks. The work shows how the model is adapted to the real system and the impact of the control algorithms on the efficiency of the combustion process. The example is considered for the implementation of advanced control systems in micro-, small- and medium-power cogeneration and trigeneration systems in order to improve their final efficiency and increase the profitability of implementation.

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