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Permanent magnet synchronous motors (PMSMs) have a scale of applications linking to the industrial machines. As these machines often work in a wide temperature range, the PMSM quality consistency is threatened by the temperature fluctuate. In fact, at the start of the production of the PMSMs, the quality consistency distribution already exist due to the manufacturing dispersion. However, traditional experiment‐based consistency analysis method is inadequate for the PMSM, due to its inevitable destructive measurement for the magnetic properties. To deal with the problem, this paper proposed a model‐based quality consistency analysis method. In this paper, mechanism analysis of the temperature influence on PMSMs is carried out by the finite element analysis and the digital modeling method, so that the impact of dispersion can be depicted by model rather than destructive measurement. The relationship between the temperature and PMSM cogging torque as well as other features is quantitatively revealed. To obtain the NdFeB temperature coefficient, magnetic samples were prepared and measured. Then, the temperature characteristics of the sensitive components of PMSM are established, and the PMSM temperature characteristics can be simulated by integrating temperature coefficients into the PMSM digital model. The qualitative and quantitative temperature characteristics of cogging torque are verified by experiments with a batch of PMSMs. [ABSTRACT FROM AUTHOR]

The lithium thionyl chloride (Li/SOCl2) battery is widely used as an important long‐life backup power source. Accurate battery life prediction is essential to ensure the reliability of equipment and systems. In this paper, a novel method was proposed for the life prediction of Li/SOCl2 batteries based on the pulse load test and accelerated degradation test (ADT). The proposed pulse load test method can estimate the primary battery capacity accurately and nondestructively, which solves the challenge of quantifying degradation due to unknown initial values. Furthermore, we noticed a new phenomenon that capacity loss was affected by electrolyte fluidity, and unexpected capacity loss was observed for batteries at different discharge angles. By analyzing the mechanism of this phenomenon, we avoided serious capacity measurement errors in the 24‐week ADT. A life prediction model with a satisfactory ability to approximate the measured data was established depending on the exponential influence of time and temperature on capacity degradation. [ABSTRACT FROM AUTHOR]

Minimax optimization (MMO), which aims at pursuing the solutions with the best performances in the worst case, is widely used in the robust design. However, there are still fundamental limitations for MMO to converge to the optimum when solving asymmetric problems. Moreover, when MMO is employed in robust design where the objective function is evaluated through costly simulations, the efficiency of the optimization becomes crucial. To address these issues, in this paper, A novel efficient global optimization algorithm based on co‐evolutionary strategy is proposed to solve the asymmetry MMO problem with satisfactory efficiency. Furthermore, the new algorithm is tested on eight analytical benchmark problems and compared with the state‐of‐the‐art methods. Lastly, the methodology has been successfully applied to the robust design of a practical engineering product. [ABSTRACT FROM AUTHOR]

Accelerated degradation test (ADT) is generally used to accelerate degradation processes in products to estimate their lifespan and to assess their reliability in a short period of time. How to perform the failure mechanism consistency test is crucial in the application of the ADT method. Existing failure mechanism consistency test methods assume that degradation rates among individual products are the same. However, these methods do not take degradation dispersions caused by manufacturing technologies into consideration. To address this issue, a failure mechanism consistency test method for ADT based on the activation energy invariant method and the likelihood ratio test is proposed. First, a degradation modeling method for ADT is introduced. Then, the logarithmic maximum likelihood function values of the degradation models are estimated based on the two‐step maximum likelihood estimation (MLE) method. Finally, the decision rule is proposed based on the likelihood ratio test. The method mentioned above is, then, used on the real degradation data of carbon‐film resistors and bullet O‐rings, and its effectiveness is verified. Furthermore, based on the failure mechanism change point in RTV5370 siloxane rubbers, the simulated degradation data are degenerated to compare the proposed method with the method not considering individual differences in different ADT programs and degradation dispersions. [ABSTRACT FROM AUTHOR]

The cross‐linking effects of cross‐linked ethylene‐tetrafluoroethylene copolymer (XETFE)‐insulated cables at different electron beam radiation doses were analyzed in this paper. Evaluation of the mechanical performance of the cables revealed that the highest tensile and breaking elongation was achieved at a radiation dose of 8 × 104 Gy and that XETFE had a good resistance to extreme electron beam irradiation. This is attributed to the cross‐linking effects induced by electron beam irradiation, and this takes full advantage of the strength of molecular chain crosslink to each other. The crystallization kinetics of XETFE at different electron beam radiation doses were studied in detail in terms of the non‐isothermal and isothermal crystallization processes. The results indicated that the crystallinity of the XETFE domain increased with an increase in the radiation dose as a result of heterogeneous nucleation. Moreover, the highest ΔEa was obtained, indicating that XETFE absorbed some energy at a radiation dose of 8 × 104 Gy. These kinetic parameters had help in carrying out a comprehensive evaluation of the performance of XETFE‐insulated cables for aerospace applications. Moreover, the fluoride precipitation observed in this study indicated that upon electron beam irradiation, XETFE could internally produce hydrogen fluoride, which is corrosive to metals. Thus, optimizing the radiation dose was necessary to achieve the desired performance. We could believe that the improvement for properties of electron beam XETFE insulation cables would expand their range of applications in the aerospace field. [ABSTRACT FROM AUTHOR]

Due to the effects of manufacturing tolerances and environmental conditions, component parameters vary and degrade with time. This may cause performance measures of electronic circuits to deviate from design specifications. Therefore, a tolerance design method based on performance degradation is proposed for electronic circuits, so as to improve the robustness of output characteristics. First, sensitive components causing output fluctuation are determined via orthogonal experiment and PSpice simulation. Then, degradation path models are established to describe the degradation process of sensitive components. The predicted values worked out by the degradation path models are substituted into the simulation model for Monte Carlo analysis. Besides, output characteristics and performance reliability are evaluated according to Monte Carlo simulation. Finally, optimum allocation is carried out for component tolerances as per minimum life cycle cost. The proposed method is illustrated by a case study of light-emitting diode (LED) driver. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]