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Stator slot skewing and rotor step-skewing methods are the most commonly used methods to reduce the torque ripple and electromagnetic vibration in the electric vehicle (EV) drive motor industry. However, these two methods have limitations on the suppression of the 0th-order vibration component and multiples of rotor magnetic pole number order vibration components. This article presents a novel rotor-segmented motor with different pole widths to reduce electromagnetic vibration for EVs. The principle of the presented new rotor segmented motor to mitigate the 0th-order and the multiples of rotor magnetic pole number orders vibration components are analytically analyzed and illustrated. Three multiphysics field models, i.e., conventional motor, rotor step-skewing motor, and the presented motor, were established. The electromagnetic vibration properties related performances, including air-gap flux density, radial force, torsional force, and vibration response, are extensively compared. Finally, the rotor step-skewing motor and the presented motor were prototyped, and extensive tests were conducted. The results show that the presented motor has a specific mitigating effect on electromagnetic vibration, with a significant decrease in the 0th-order vibration amplitude and the overall vibration level is the same as that of the rotor step-skewing motor.

Interior permanent magnet machines (IPMSMs) have attractive features, including high power density, high efficiency, and excellent control performance. However, the unsuppressed torque ripple of IPMSM will cause declined torque quality, increased vibration, and reduced reliability. This article presents a novel composed T-shaped notching rotor to suppress torque ripple for IPMSM. The mathematical models of cogging torque and winding factors considering T- shaped notches are established, respectively. Although the principle of the novel rotor design is clearly explained by mathematical models, the accurate dimensions of the composed T-shaped notch are difficult to calculate. Therefore, two-dimensional finite element analysis and multiobjective design optimization are employed to calculate the T-shaped notch dimensions. The electromagnetic performance of the proposed rotor machine is compared with that of the commonly notching rotor machine. In addition, the mechanical strength of the novel rotor is verified by calculations of stress and deformation. Finally, the proposed prototype with a novel rotor is fabricated, and extensive experiments are conducted. The results show that the torque ripple of IPMSM can be significantly reduced by the novel composed T-shaped notching rotor.

Grinding is a fundamental operation in craniotomy. Suitable grinding parameters will not only reduce force damage, but also ensure grinding efficiency. In this study, the regression equations of material removal rate and grinding force were obtained based on the theory of cortical bone grinding and full factorial test results, a multi-objective optimization based on the particle swarm algorithm was proposed for optimizing the grinding parameters: spindle speed, feed speed, and grinding depth in the grinding process. Two conflicting objectives, minimum grinding force and maximum material removal rate, were optimized simultaneously. The results revealed that the optimal grinding parameter combination and optimization results were as follows: spindle speed of 5000 rpm, feed rate of 60 mm/min, grinding depth of 0.6 mm, grinding force of 15.1 N, and material removal rate of 113.8 mm3/min. The parameter optimization result can provide theoretical guidance for selecting cortical bone grinding parameters in actual craniotomy.

There has an increasing demand for a low cost brushless alternative to the series universal motor and single phase induction motor in domestic appliance and automotive applications. Single phase FSM with field winding has relatively low efficiency and low power factor. This paper tries to investigate a topology of single phase FSM which uses low cost magnet, i.e., Ferrite instead of field winding to provide field excitation. By using field focusing effect, the magnets are properly arranged to provide the required airgap flux. A standard design procedure for the presented FSM is developed. Extensive comparisons to the single phase induction motor, single phase permanent magnet motor and universal motor are made. A prototype with 8/4 pole configuration is fabricated. The experiment results are given and compared to the FEA simulated results. In addition, the electromagnetic vibrations and acoustic noises are also considered and measured which is always seen as the main disadvantage of this kind of motor.

A novel power and cooling cogeneration system which combines a supercritical CO2recompression cycle (SCRC), an ammonia-water absorption refrigeration cycle (AARC) and a Kalina cycle (KC) is proposed and investigated for the recovery of medium-temperature waste heat. The system is based on energy cascade utilization, and the waste heat can be fully converted through the simultaneous operation of the three sub-cycles. A steady-state mathematical model is built for further performance study of the proposed system. When the exhaust temperature is 505°C, it is shown that under designed conditions the thermal efficiency and exergy efficiency reach 30.74% and 61.55%, respectively. The exergy analysis results show that the main exergy destruction is concentrated in the heat recovery vapor generator (HRVG). Parametric study shows that the compressor inlet pressure, the SCRC pressure ratio, the main compressor and the turbine I inlet temperature, and the AARC generator pressure have significant effects on thermodynamic and economic performance of the combined system. The findings in this study could provide guidance for system design to achieve an efficient utilization of medium-temperature waste heat (e.g., exhaust heat from gas turbine, high-temperature fuel cells and internal combustion engine).

Industrial wastewater contains abundant organic dyes, antibiotics, pesticides, chemical fertilizers or heavy metal ions, which seriously deteriorate the ecological environment. Among the practical techniques for reducing water pollution, photocatalysis is a kind of sustainable solar energy conversion technique for removing organic contaminants. In this review, the advances in the preparation, modification, and doping of graphitic carbon nitride (g-C3N4), including non-metal doping, metal doping, dual- or tri-doping, are introduced firstly. Then, we systematically reviewed the recent progress of g-C3N4/metal oxide composite photocatalysts, including a g-C3N4/n-type metal oxide, such as TiO2, ZnO, SnO2, WO3, FexOy, CeO2, V2O5, MoO3, MnO2, Nb2O5, In2O3, and a g-C3N4/p-type metal oxide, such as Co3O4, Bi2O3, NiO and Cu2O. At last, we summarized the design principles for preparing heteroatom doped g-C3N4 and g-C3N4/metal oxide composites, and forecast the promising research directions. The main objective is to provide a guideline for designing highperformance heteroatom doped g-C3N4 and g-C3N4/metal oxide photocatalysts.

In order to determine the carbon sequestration content of waste leather dander biochar (W-BC) at different pyrolysis temperatures and its effect on soil organic carbon mineralization, waste leather dander (WLD) was prepared into BC-300, BC-400 and BC-500 at different temperatures (300, 400 and 500 ℃). The results show that the highest carbon sequestration content of BC-400 is 18.23% when the pyrolysis temperature is 400 ℃. In addition, after applying BC-400 to the soil for 60 days, the mineralization rate of soil organic carbon decreased to 0.499mg CO2/ (g ·d), and the content of soil moisture, pH and total organic carbon (TOC) increased to 42.35%, 7.25% and 30.94%, respectively. At the same time, the addition of biochar promoted the transformation of bacteria into stable C-dominant phylum (Firmicutes) and the carbon sequestration capacity of soil was enhanced. The data of this study have certain reference value in the field of soil remediation and resource treatment of WLD.

Objectives Although laparoscopic distal gastrectomy has been widely used for distal gastric cancer, the best functional reconstruction type has not yet been established. Based on previous experience, we propose a modified uncut Roux-en-Y anastomosis. This study aimed to compare the outcomes of different intracorporeal anastomoses after laparoscopic distal gastrectomy.Methods From April 2015 to August 2020, the data of 215 patients who underwent laparoscopic distal gastrectomy was collected. The patients were divided into 4 groups according to the digestive tract reconstruction method, Billroth-I, Billroth-II, Roux-en-Y, and the modified uncut Roux-en-Y. Clinicopathologic characteristics, surgery details, short-term outcomes, and postoperative nutritional status were analyzed.Results The operation time of Billroth-I anastomosis was significantly shorter (216.2 ± 25.8 min, P < .001) than that of other methods. There was no difference in postoperative complications and OS among the 4 reconstruction methods. The incidences of esophagitis, gastritis, and bile reflux were significantly lower in the Roux-en-Y and uncut Roux-en-Y group (P < .001) 1 year after surgery. And the postoperative albumin and PNI levels in uncut Roux-en-Y group were higher than those in other groups(P < .05). On multivariate analysis, age and reconstruction type were independently related to esophagitis, gastritis, and bile reflux. Serum albumin and the prognostic nutritional index were significantly higher in the uncut Roux-en-Y group than other groups (P < .05).Conclusions All 4 reconstruction techniques are feasible and safe. The Roux-en-Y and uncut Roux-en-Y are superior to Billroth-Ⅰ and Billroth-Ⅱ+Braun in terms of reflux esophagitis, gastritis, and bile reflux. Uncut Roux-en-Y may result in better PNI than the others.

Molybdenum disulfide (MoS2), as a kind of adsorbent, can selectively remove Pb2+from water. However, agglomeration and fewer active S sites are the two factors that spoil the adsorption performance of MoS2. In order to solve these problems, a new type of adsorbent: 1T/2H mixed phase MoS2(D-MoS2)/montmorillonite (MMT) composites (D-Mt) are proposed via one-step hydrothermal method, associating with filling cations. Among them, S defects are intentionally introduced to promote the conversion of the 2H phase in MoS2into 1T phase, contributing by adding excessive amount of CH4N2S and using hydrothermal method. Moreover, owing to filling with Na+, D-MoS2is uniformly dispersed driven by electrostatic force. Consequently, D-Mt has a large density of edge active sites, contributing to a greatly improved adsorption capacity with 175.57 mg·g-1, which can be attributed to the different growth directions of MoS2nanosheets and its unique defect structure as well as the inhibited masking effect on -OH that existing on the edge of MMT. Additionally, the adsorption mechanism is confirmed via theoretical calculations, which suggests that there are electron transfers between O 2p, S 3p and Pb 6p, indicating that Pb2+could be adsorbed via three paths, including interlayer ion exchange, -OH on the edge as well as S defects in D-Mt.

Background: Increasing evidence indicated that the tumor microenvironment (TME) plays a critical role in tumor progression. This study aimed to identify and evaluate mRNA signature involved in lymph node metastasis (LNM) in TME for gastric cancer (GC).Methods: Gene expression and clinical data were downloaded from The Cancer Genome Atlas (TCGA). The ESTIMATE algorithm was used to evaluate the TME of GC. The heatmap and Venn plots were applied for visualizing and screening out intersect differentially expressed genes (DEGs) involved in LNM in TME. Functional enrichment analysis, gene set enrichment analysis (GSEA) and protein-protein interaction (PPI) network were also conducted. Furthermore, binary logistic regression analysis were employed to develop a 4-mRNAs signature for the LNM prediction. ROC curves were applied to validate the LNM predictive ability of the riskscore. Nomogram was constructed and calibration curve was plotted to verify the predictive power of nomogram.Results: A total of 88 LNM related DEGs were identified. Functional enrichment analysis and GSEA implied that those genes were associated with some biological processes, such as ion transportation, lipid metabolism and thiolester hydrolase activity. After univariate and multivariate logistic regression analysis, 4 mRNAs (RASSF2, MS4A2, ANKRD33B and ADH1B) were eventually screened out to develop a predictive model. ROC curves manifested the good performance of the 4-mRNAs signature. The proportion of patients with LNM in high-risk group was significantly higher than that in low-risk group. The C-index of nomogram from training and test cohorts were 0.865 and 0.765, and the nomogram was well calibrated.Conclusions: In general, we identified a 4-mRNAs signature that effectively predicted LNM in GC patients. Moreover, the 4-mRNAs signature and nomogram provide a guidance for the preoperative evaluation and postoperative treatment of GC patients.

It is well proven that hydraulic fracturing may cause a complex fracture network or an asymmetric fracture pattern. This study aims to develop a model to analyze the pressure transient behaviors for asymmetric fracture patterns. Some physical models were built to describe the asymmetric of fracture length and conductivity. In order to solve the model, each fracture was discreted to several segments and each segment was treated as a line source. According to theory of superposition, we coupled the flow rate and pressure in the boundaries and the middle point of segments. After a Laplace transform to the mathematical model, the flow rate of each line source can be calculated. We used Stehfest inversion algorithm to determine the simulation results in a real-time domain. The calculation results show that the asymmetry of fracture patterns or properties can make a significant change in pressure and derivation curves. If only primary fracture is considered, it is difficult to differentiate the flow period. If the fracture patterns contain several secondary fractures, the derivation curve shows an obvious pseudo-radial flow in the early period.