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A comprehensive study of a ferrite magnet assisted synchronous reluctance machine (FMaSynRM) for the forklift applications by using open-source platform is introduced in detail in this paper including both modelling and electromagnetic design aspects. On the electromagnetism modelling side, this paper uses Elmer as the core and combines other open-source packages covering the preprocessing, solving, and postprocessing sections to build the finite element model of the FMaSynRM. On the electromagnetic design side of the FMaSynRM, this paper mainly discusses the single-double layer winding arrangement, rotor topology, and demagnetization performance. And the power, efficiency, and current maps of the finalized machine at different speeds and loads are estimated by the finite element method (FEM) using the open-source platform, which takes different control logics into consideration. Finally, the predicted results by FEM are verified by the tested results. The modelling method by using open-source platform and design procedure of the FMaSynRM presented in this paper can also be used in the design of other electrical machine types in the adjustable speed applications.

Skewed slots are widely used in many industrial applications because they can effectively reduce electromagnetic vibration and noise. In order to eliminate axial electromagnetic force in ordinary skewed slots rotor, a double skewed slot was proposed, which can useful reduce axial electromagnetic force and is superior to traditional skewed slots on reducing the electromagnetic vibration and noise. However, it still suffers from the problem of the difficult manufacturing process in large-sized submersible motors. In this paper, a radial skewed slot to reduce the electromagnetic vibration and noise is proposed, which has the advantages of a simple manufacturing process and obvious effect about reducing noise. Large-sized submersible motors are noisier than ordinary motors but lack effective means to reduce electromagnetic vibration and noise. So this paper adopts 2-D FFT and multi-physics coupling analysis method to analyze and compare the performances of the straight slot and the radial skewed slot in large-sized submersible motors.

Aiming to improve the efficiency of the water-filled submersible motor, the method of optimizing the ratio of diameter to shaft length and air-gap length of the motor is proposed to reduce the water friction loss of the water-filled submersible motor. By analyzing the composition of the mechanical loss and the research status of the water friction loss of the water-filled submersible motor, the optimization methods of the water-filled submersible motor efficiency are determined. Two-dimensional time-harmonic field solutions are employed in this paper to accurately estimate the electromagnetic performance of the submersible motor, which costs less time and computational resources compared to the transient solution. By fitting the curves of water friction loss and electromagnetic losses with the optimized parameters, the influence of the ratio of diameter to shaft length and the length of the air-gap on the efficiency of the motor is analyzed. Finally, the parameters of the motor are determined, with the consideration of the influence of the radial to axial ratio and the air-gap length on the performance parameters of the motor and the requirements of actual working conditions. The results show that the two methods can effectively reduce the water friction loss of the water-filled submersible motor and improve the efficiency of the water-filled submersible motor in the motor design stage.

The torque ripple is affected by both the stator and the rotor magnetic field harmonics. In synchronous reluctance motors (SynRM), there are only rotor permeance harmonics existing on the rotor side for the absence of the rotor windings. Since the asymmetric rotor flux barriers are widely applied in the SynRM rotor, it is difficult to calculate the rotor permeance accurately by the analytical method. In this article, the effects of the rotor permeance harmonics on the air-gap magnetic field are studied by a virtual permanent magnet harmonic machine (VPMHM), which is a finite-element (FE) based magnetostatic analysis model. The air-gap flux density harmonics produced by the SynRM rotor are extracted from the VPMHM model and used as the intermediate variables for the torque ripple optimization. The proposed method does not need to solve the transient process of motor motion. Hence, the time of the optimization process can be significantly shortened. Finally, a full electric cycle is simulated by dynamic FE simulation, and the torque ripple is proved to be effectively reduced.

Silty sand slopes are prone to damage due to seepage or rainfall. A partial reinforcement method using short polypropylene fiber and sand mixtures was proposed to protect silty sand slopes from seepage flow failure. The effects and the reinforcement mechanism were explored. First, triaxial tests were performed on sand samples reinforced with fiber lengths (6 and 12 mm) and contents (0.25 and 0.50%) to verify the reinforcement effect. Then, model tests were conducted on sand slopes under lateral seepage flow and the failure mode with different fiber contents and reinforcement method were examined. The results showed that the cohesion and shear strength of sand were significantly improved with the increase of fiber content and length. The suction of unsaturated sand was also enhanced by the fibers. The change in stress-strain behavior from strain softening to strain hardening indicated that static liquefaction could be effectively prevented. The failure mode and extent of slope damage depended on the fiber content. However, it was noted that the slope surface with small reinforcement range performed similarly to that with large reinforcement range. In conclusion, the partial reinforcement method with short discrete synthetic fibers can be used as an effective alternative for slope reinforcement.

Synchronous Reluctance Motors (SynRMs) have been widely used in some industrial fields because of their attractive characteristics, such as high efficiency, low cost, and simple structure. In order to reduce the torque ripple of the SynRMs, a non-parametric model is usually used to optimize the rotor structure. However, the conventional method has the problems of the low-accuracy and poor generalization ability. In this paper, an optimization method of the rotor structure is proposed to reduce the torque ripple by utilizing the deep learning algorithm. Firstly, the sample data of the relationship between the rotor structural parameters and torque ripple are obtained with the finite element analysis (FEA). The fast calculation model is established by the deep neural network (DNN). Then, with the goal of not weakening the torque density and minimizing the torque ripple, the immune clone algorithm (ICA) is utilized to optimize the structural parameters of the rotor at different operating points. Finally, the correctness and validity of the method are verified by the simulation analysis. It is concluded that the accuracy of the model established by DNN is acceptable. The proposed method can significantly reduce the torque ripple and increase the torque density.

Saturated silty sand is more likely to cause landslide due to static liquefaction behavior. In this study, easily dispersible short synthetic carbon fibers (CF), with larger aspect ratio and smaller diameter (7 μm) compared with conventional polypropylene fibers, were used to improve the liquefaction resistance behavior of silty sand. A series of triaxial tests under different confining pressures were carried out on reinforced samples with different fiber contents (0.2, 0.5, 1.0%) and lengths (3, 6, 10 mm). The properties of stress and strain relationships, development of pore water pressure, effective stress path, liquefaction brittleness index, critical state line and volumetric strain were examined. The results from undrained tests showed that both the peak and post-peak deviator stresses of CF reinforced samples did not show a regular increase with fiber length. The 6 mm CF fiber showed the best reinforcement effect at a confining pressure of 100 kPa while 3 mm CF fiber achieved the best results at a confining pressure of 200 kPa. CF-reinforced sand was confirmed to be an effective liquefaction mitigation method compared with the method using conventional polypropylene fibers. This study provides an effective improvement method in particular to prevent a geological hazard in backfilling engineering projects.

Copper bars are often utilized in the rotor of a high power induction motor in order to reduce joule loss and improve overall efficiency. In this article, a kind of rotor convex copper bar is introduced instead of the conventional rectangle copper bar in the case of inverter-fed induction motors. The difference in the leakage reactance between the convex and the rectangle copper bar is analyzed. The use of convex copper bars can reduce the leakage reactance to some extent as the frequency rises. The decrease of the leakage reactance can contribute to restraining the ascending trend of the rotor reactive current. Finite-element method is taken to carry out the simulation, and a 550 kW prototype is produced to validate the proposed method. Experimental results indicate that the application of convex copper bars can help to lower the rotor reactive current and improve the power factor when the motor works near the end of the constant power area.

Tunnel engineering is affected by a variety of factors, which results in large detection errors in tunnel engineering. In order to improve the monitoring effect of tunnel engineering, based on BPNN and MARS machine learning regression algorithm, this research constructs a tunnel engineering monitoring and prediction model. Moreover, the gray residual BP neural network designed in this study uses a series combination, and the residuals obtained from the gray model are used as the input data of the BP neural network, and the output of the combined model is used as the prediction result. By applying the monitoring data of the convergence of the upper surrounding of the tunnel surface section and deformation of the arch subsidence, it is verified that the proposed method based on the combined model of BPNN and MASR can predict and analyze the tunnel deformation monitoring data very well.

The intermediate ring (IR) in the novel squirrel-cage rotor is vulnerable to electrical faults for its relatively small dimension. With the investigation of IR current features, this study mainly proposes an optimisation design strategy of IR to avoid excessive thermal stress at a start-up instant. The amplitude and phase relations of various rotor currents are reflected in the proposed current phasor diagram. In terms of the internal distribution of one concrete current, the circuit analysis theory is applied by dividing the whole conductor into multiple subconductors. The leakage flux around the conductors is simplified, respectively, according to the spatial symmetry. With reference to the existing bar design, the IR design scheme is mainly guided by two essential principles regarding the current-related parameters. Finally, the validity of the designing process of IR is verified by the coupled simulations and temperature-rise experiments. The surface temperature of the designed IR is not the highest, and the partial temperature difference is limited and reasonable.

A new stiffened composite pipe pile was developed for improving the foundation of reclaimed ground in ocean engineering. To study the bearing capacity of the stiffened composite pipe pile group, a combination of field test and finite element method was used. Firstly, field tests were performed on the proposed single stiffened composite pipe pile. The single stiffened composite pipe pile model was verified by comparing the numerical simulation results with the field test results. The load transfer mechanism from the stiffened core to the cemented soil and the surrounding soil was clarified. Further, a 3D finite element model of the stiffened composite pipe pile group was established based on the single stiffened composite pipe pile model. Finally, the bearing capacity of the pile group and the stress distribution of each pile were analysed and the influence of the pile spacing on the pile bearing capacity was discussed. The results showed that the axial stress of both the side and corner piles decreased rapidly with an increase in the pile spacing, and the stress-bearing ratio decreased. The stress-bearing ratio of the central pile increases with an increase in pile spacing. The smaller the pile spacing, the larger the load proportion of the composite pile group and the larger the foundation settlement. The optimal design scheme was a composite pile with a 500 mm stiffened core diameter, 700 mm outer cemented soil diameter, and a spacing between piles of four times the cemented soil diameter (2.8 m) considering the group pile bearing capacity and the economic benefits of the project. These results provide a reference for the design and construction of stiffened composite piles for ground improvement projects.

Multiproduct firms are responsible for the vast majority of global trade. A prior literature examines how multiproduct firms respond to trade liberalizations that simultaneously affect all of the firms' products and inputs. In contrast, our study uses Chinese firm-product-level export data to examine how an AD action, a very targeted trade policy against a specific product in a specific export destination, affects a multiproduct firms' price and quantity decisions across its other products and export destinations. We find robust evidence for a new phenomenon we call within-firm cross-product trade deflection whereby an AD duty against one of the firm's products in one of its export destinations is associated with reduced prices and increased sales of its other products across all markets. This type of effect depends on increasing costs from joint production within multiproduct firms, something that is often assumed away in many models of the multiproduct firm. We also document for the first time a within-firm chilling effect whereby an AD action in one export destination on a product leads the firm to raise price and lower quantity of the product in other export destinations to lower the risk of AD actions in these other markets.

A proper treatment of granite residual soil (GRS) in geotechnical practices requires both macro and microscopic evaluations. In this study, uniaxial and oedometric compression tests were conducted to investigate the mechanical properties of the saturated untreated and cement-treated GRS. Meanwhile, XRD, SEM, and MIP tests were conducted to identify the presence and types of C–S–H and the changes in the pore structure after cement treatment. The effects of cement treatment on the uniaxial compressive strength, secant modulus, compressibility, and vertical yielding pressure were revealed and the mechanisms of the soil structure to be modified through cement treatment were clarified based on the test results. A threshold volumetric cement content of 2–3% was determined based on the mechanical properties and microstructural characteristics of the saturated cement-treated GRS. Cement contents below this threshold would produce inadequate cementation between the soil particles. In contrast, cement contents above this threshold are considered inefficient because the transformation of the soil structure from single-porosity to dual-porosity increases the total porosity and retards the strength and stiffness gains.