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The direct-drive type high-torque-density motor is one of the most promising solutions of electric propulsion for aircraft. The cogging torque of the direct-drive motor causes torque ripple, vibration, and noise, which seriously affect the stability and reliability of the electric propulsion system for aircraft. In this paper, a novel direct-drive type high-torque-density dual-rotor radial flux permanent magnet synchronous motor (DRPMSM) is proposed, and its cogging torque is weakened by permanent magnet shape design and pole-arc coefficient combination. An eccentric and chamfered permanent magnet shape is proposed, and the influence of eccentric distance and chamfer angle on cogging torque is clarified. Through the pole-arc coefficient combination design of the inner and outer rotors of the DRPMSM, the cogging torques of the inner and outer rotor are phase reversed, thus further reducing the total cogging torque of the DRPMSM. By employing the response surface method, a mathematical model is established for the cogging torque of the DRPMSM in relation to the pole-arc coefficients, chamfer angle, and eccentric distance of the permanent magnets. The parameters that minimize the cogging torque of the DRPMSM are obtained using a genetic algorithm. A prototype is manufactured according to the optimized parameters, and experimental results validate the correctness of the theoretical analysis and the effectiveness of the optimization design method.

The design of a modern Global Navigation Satellite System (GNSS) has been exceptionally valued by the military and civilians of various countries. The inclusion of the pilot channel in addition to the navigation data channel is considered one of the major changes in GNSS modernization. Schemes of an equal weight combination (1:1 combination) and power ratio combination for data and pilot are primarily adopted by traditional receivers. With the emergence of the new data and pilot modulation signals with unequal power, such as L1C at Global Positioning System (GPS) L1 frequency and B1C at BeiDou Navigation Satellite System (BDS) B1 frequency, the traditional combination coefficient cannot achieve optimal reception performance. Considering the influence of the combination coefficient on the reception performance, the optimal coefficient of the correlator joint is estimated in this paper. The entire architecture of the data/pilot correlator joint tracking and positioning with unequal power is given. Based on the equivalence principle of the correlator joint and the discriminator joint, the optimal coefficient of the carrier loop is determined. A mathematical model of joint code tracking accuracy is established, and the optimal coefficient of the code loop is determined. The real-life satellite signal and simulation results show that the amplitude–ratio combined scheme is the best for receiving of correlator joints, followed by the power–ratio combination scheme and, finally, the 1:1 combination scheme. It is worth mentioning that the positioning accuracy of the amplitude–ratio combination is improved by 2% compared to the 1:1 combination, and by 1.3% compared to the power–ratio combination for B1C signal. The positioning accuracy of the amplitude–ratio combination is improved by 2.37% compared to the 1:1 combination, and by 1.6% compared to the power–ratio combination for L1C signal. The conclusions of this paper are validated for the traditional data/pilot with an equal power allocation. The techniques and test results provide technical support for GNSS high-precision-user receivers.

This study focuses on quantifying wind–temperature load combination coefficients for long-span hybrid cable-stayed suspension bridges (HCSSBs) to overcome limitations of traditional methods in ignoring load correlation and geometry nonlinearity. A probabilistic framework is proposed to use site-specific load data to determine load combination coefficients, focusing on load correlation and geometric nonlinearity while assuming that stress reflects load effects and that 100-year samples are statistically representative. Long-sequence meteorological data, including wind and temperature measurements, were used to construct marginal and bivariate joint distributions, which characterize the randomness and correlation of wind and temperature loads. Load samples covering the design reference period were generated and validated via convergence tests. Four load scenarios (individual temperature, individual wind, linear superposition, and nonlinear coupling) were designed, and key control points are screened using indicators reflecting the comprehensive load effect EII-, combined load proportion ζ, and nonlinear influence η. Based on stress responses of key control points, load combination coefficients were derived with probability modeling. A case study for a bridge with span length of 2300 m shows that the load combination coefficients for the main girder are 0.60 (east wind) and 0.59 (west wind), while they are 0.51 (east wind) and 0.58 (west wind) for the main tower. These results demonstrate that the proposed method enables the provision of rational load combination coefficients.

Under the action of the same wind azimuth, the extreme values of the wind load effect components of building structures are generated in the along-wind, cross-wind, vertical, and torsional directions. In designing the wind-resistant structure, the extreme values of effect components need to be combined to determine the internal force envelope values of members. Complete quadratic combination (CQC) and Turkstra combination rules are often used to determine the combination value of extreme values of wind effect components. The extreme probability distribution expressions of the CQC, and the Turkstra and approximate rules, are derived. The simplified combination Equations and combination coefficients of the CQC and Turkstra approximate rules are proposed in this paper. We use the combination Equations and Monte Carlo simulation method to analyze the accuracy of Turkstra and its approximate rules. The results show that the combination extreme is associated with the correlation coefficients, mean values, ratios of standard deviations, and fluctuating extremes of effect components. The errors between Turkstra and its approximate rules are small when load effect components show a positive correlation. The errors are largest when the standard deviations of components are equal. Our research results provide a theoretical basis for the combination method of wind load effect components of building structures.

In the context of e-commerce trade between enterprises, there are problems such as price wars, false advertising, and unreasonable operations aimed at seizing market share. However, traditional estimation methods cannot provide a reasonable evaluation of the marketing competitiveness of e-commerce enterprises from an overall perspective. To help enterprises better clarify their own position and quantify their marketing competitiveness, a competitiveness evaluation model based on optimized deep learning networks is proposed. By combining subjective and objective evaluation methods, the indicators that affect the marketing competitiveness of enterprises are assigned to obtain the final competitiveness value. The research outcomes expressed that the max absolute error of the model constructed by the research institute was 0.0006, the max relative error was 0.0045, and the model accuracy was 99.85%. In the secondary indicator experiment of marketing competition, the model determined that the turnover rate of fixed assets had the greatest impact, with a weight value of 0.1263. Nine companies were randomly selected for market value estimation, and the average relative error of the model was 14.90%, which was lower than the mean relative error of the relative valuation, cash flow and absolute valuation methods, with numerical differences of 8.03%, 2.94%, and 0.12%, respectively. The research findings illustrated that the model constructed by the research institute had good performance and certain reference values for evaluating the marketing competitiveness of e-commerce enterprises.

An impact sprinkler loaded on a remote control trailer can be used for motion to improve the efficiency of a single Hard Hose Traveler in small and medium-sized irregular fields. Herein, a model for calculating the combination uniformity coefficient (CU) was established in the square test area under two-directional motion. The accuracy of the irrigation uniformity model was verified using the test data of application depth (hn). The results revealed that the nozzle diameter, speed of sprinkler motion (v), and motion methods can significantly impact the average application depth ( h − ) and the CU value of sprinkler irrigation performance. The motion methods included uniform motion and a constant speed combination motion. The highest CU values were recorded when the primary and secondary nozzle diameters were 10.5 and 4.5 mm, respectively (overall value, about 81.7%). The CU value gradually decreased with the increasing v value of the sprinkler. The CU value was higher under the constant speed combination motion than the uniform motion. The h ¯ value gradually decreased with increasing v value. The h ¯ value was classified based on the water requirement of different crops. The optimal CU value corresponding to each grade of the h ¯ value was obtained in different schemes of the combination of sprinkler speeds. This research guides the realization of variable spraying of a Hard Hose Traveler and the intelligent uniform motion of the sprinklers.

The closure temperature refers to the temperature at which a structure forms an overall constrained structural system, also called the initial temperature. A reasonable closure temperature can avoid large additional stresses caused by excessive air temperature changes in large-span structures. To study the thermal action of the closure temperature on a structure, a probability distribution function of uniform temperature action is proposed. The effect of closure temperature is studied by introducing an adjustment coefficient. The partial factor and combination value coefficient of thermal action are presented, and their reliabilities are verified by the first-order second-moment method. The results show that with increasing adjustment coefficient, the probability distribution of thermal action tends to be uniformly divergent, the partial factor of thermal action increases, and the combination value coefficient decreases. The optimal closure temperature times are in March, April, October, and November for six cities in China. In this case, an adjustment coefficient of 0.3, a partial factor of 1.5, and the combination value coefficient of 0.45 are recommended. In addition, the partial factor of 1.5 and the combination value coefficient of 0.45 can be verified by reliability verification, which is more economical and reasonable with regard to ensuring safety.

The focus of face recognition is a classifying problem based on similarity measurement. This paper presents a color image correlation similarity discriminant (CICSD) model after defining within-class correlation and between-class correlation for color face recognition. The CICSD model unifies the color face image representation and recognition into one framework. Thus classifying performance while representing a color face image can be considered. Therefore, the present model involves in two sets of variables: the color component combination coefficients for color face image presentation and the projection basis vectors for color face recognition. An iterative CICSD algorithm is designed to find the optimal color component combination coefficients and the optimal projection basis vectors. Experimental results on the FERET and AR color face database show the effectiveness of the present model and algorithm.

In this paper, a new spatial coherence model of seismic ground motions is proposed by a fitting procedure. The analytical expressions of modal combination (correlation) coefficients of structural response are developed for multi-support seismic excitations. The coefficients from both the numerical integration and analytical solutions are compared to verify the accuracy of the solutions. It is shown that the analytical expressions of numerical modal combination coefficients are of high accuracy. The results of random responses of an example bridge show that the analytical modal combination coefficients developed in this paper are accurate enough to meet the requirements needed in practice. In addition, the computational efficiency of the analytical solutions of the modal combination coefficients is demonstrated by the response computation of the example bridge. It is found that the time required for the structural response analysis by using the analytical modal combination coefficients is less than 1/20 of that using numerical integral methods.

The interaction of tidal surges and fluvial flows in any river system results in a prevailing combined condition that requires accurate consideration in the reaches of the system not directly influenced by either phenomenon. The combined return period of the system should be deduced based on the combined effects of the two phenomena, which may usually be considered independent of one another. It is therefore imperative to consider both the return periods of the upstream flood condition and the downstream tidal surge condition to determine the combined return period for design flood analysis in tidal river systems. The task of obtaining a suitable and practical combination of the two phenomena encompasses preparation of an interactive scenario most closely and practically verified against the actual design event. In the present research, a combination coefficient has been introduced using the joint probability method. The combination coefficient is used to combine return periods of tidal surges and fluvial floods. A numerical and stochastic model has been developed for hydraulic routing in tidal rivers. The model is applied to the Karun River in Iran and the Severn River in the United Kingdom. The model can generally be utilized for river management and determination of safe bank height for tidal rivers.Key words: combination coefficient, tidal surges, river floods, joint probability method.