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In response to the problem of high stubble damage rate during sugarcane harvesting, the interaction between sugarcane stalks and basecutter was analyzed, and a sugarcane stubble basecutting device was designed based on the combination of "sliding cutting and shearing cutting" to improve the cutting quality. The principle of unsupported cutting of traditional disc basecutters and supported cutting of sliding shear combination basecutters was analyzed. The result was shown that supported cutting could effectively reduce the bending resistance and inertia force of stems, thus preventing significant deformation of stems to a certain extent, effectively ensuring the cutting quality of stems, and sliding cutting can effectively reduce cutting resistance. The parameters of the key components of the basecutter were determined by establishing the force model of the stem. The sliding cutting operation is carried out using an equal sliding angle blade curve, and the sliding cutting angles and blade bevel angles were 40 ° and 45 °, respectively. The statics and modal analysis of the basecutter were conducted to prevent insufficient tool strength and resonance between the basecutter and the motor during shearing using ANSYS/Workbench. An optimal combination was achieved to fully meet the performance requirements, in terms of structural strength, where the yield strength of the basecutter was 450-650 MPa, while the maximum stress on the basecutter was 102 MPa, and the maximum displacement was 4.94×10-5m. The excitation frequencies of the cutting and the feeding motors were 0- 6.667 and 0-11.667 Hz, respectively. The modal analysis results show that the excitation frequencies of the two motors were much smaller than the first-order natural frequency of the basecutter (60.89 Hz). Therefore, the smooth operation of indoor experiments was obtained without any resonance. A basecutting test bench was built with adjustable cutting disc rotational speed, feeding speed, and cutting angle. The results of the single-factor test showed that when the cutting angle, cutting disc rotational speed, and feeding speed were 10-15 °, 140-220 r/min, and 1.1-1.7 m/s, respectively, the comprehensive evaluation value y was small and the cutting quality was better. The results of orthogonal experiment analysis of variance showed that each factor had a significant impact on the comprehensive evaluation value y. The range analysis of orthogonal experiments shows that the optimal experimental level is the cutting angle was 15 °, the cutting disc rotational speed was 180r/min, and the feeding speed is 1.4m/s. After experimental verification, the comprehensive evaluation values y were 0.256 and 0.298 at this time, indicated the cutting quality was better. Referring to the DG/T 117-2021 sugarcane harvesting machinery test method, the sugarcane stubble damage rate was inspected. The shear qualification rate was as high as 90.4%, and the stubble damage rate was reduced to below 10%. The operation quality of the sliding shear combined sugarcane basecutter met industry requirements. [ABSTRACT FROM AUTHOR]

Machine-harvested sugarcane usually contains too many impurities, and subsequently the cane loss often occurs when the impurities were separated by the extractor. These problems make it difficult for the mechanized harvesting of sugarcane to be recognized by sugar mills and farmers, which seriously restricts the promotion of mechanized harvesting in China. In this study, taking the extractor of a segmented sugarcane harvester (model: 4GZQ-180) as the optimization object, a CFD method was used to explore the aerodynamic performance of a extractor, and thereby to propose the improvement scheme, finally to manufacture a prototype for the test. The impurity rate and cane loss rate were used as the main indexes to evaluate the performance of the extractor before and after optimization. The commercial CFD software Fluent was selected to analyze the airflow field nearby the whole extractor and the blade, in order to investigate the performance and defects of the prototype extractor. The SST k-ω model and the realizable k-ε model were utilized to calculate the turbulence near the blade and the turbulence in the extractor, respectively. The simulation results of flow field near the blade showed that the cusp of leading edge and trailing edge of blade can lead to the decrease of the lift, while, the increase of the drag. The simulation results of extractor flow field showed that: the discharge hood changed dramatically, and the airflow was blocked by the main shaft. These defects led to the serious separation of flow in the extractor. In the numerical simulation, the shape of blade was improved, and the maximum lift-to-drag ratio of the improved blade was significantly higher than that of the current blade. The cusp of discharge hood was eliminated after optimization, and the axis direction of main shaft was the same as the air flow direction. In order to further eliminate the flow separation, the cowl was installed outside the hydraulic motor, whereas, the cross-section shape of support frame was set to a streamline. The numerical simulation results showed that the air flow rate and efficiency of optimized extractor were greatly improved. The flow rate and power were selected as evaluation indexes to verify the accuracy of numerical simulation, indicating that the error between the calculated and measured value was about 10%. The experiments related to the impurity rate and cane loss rate were carried out to evaluate the performance of the extractor. The determination of impurity rate showed that the impurity rate of the optimized extractor was similar to the prototype extractor at a high speed (1 650 r/min), but it was significantly lower than that of the prototype extractor at medium (1 350 r/min) and low (1 050 r/min) speed. The determination of cane loss rate show that the cane loss rate of the optimized extractor was similar to that of the prototype extractor at low speed, but the cane loss rate was significantly reduced at medium and high speed. [ABSTRACT FROM AUTHOR]

目的 分析婴儿晚发型B族链球菌（GBS)化脓性脑膜炎的特点、治疗效果及转归情况，并与非GBS化脓 性脑膜炎进行比较。方法 GBS化脓性脑膜炎患儿24例纳人GBS组，以同期收治的21例非GBS化脓性脑膜炎 患儿作为对照组,收集两组患儿的的临床表现、实验室检查结果、影像学检查结果、治疗转归及预后资料并比较。 结果两组常见表现为发热、喂养困难、反应差、气促呻吟等。GBS组患儿外周血CRP高于对照组（P <0.01),脑 脊液葡萄糖水平低于对照组（P <0.05) ,GBS组合并轻中度贫血比例高于对照组（P <0.05)。GBS组头颅MRI检 查发现并发症发生率高于对照组(P <0.05)。GBS组采用青霉素类联合头孢曲松治疗4例，余均予万古霉素联合 三代头孢或美罗培南治疗;对照组选择三代头孢、美罗培南或万古霉素治疗。GBS组患儿住院时间、脑脊液葡萄糖 水平恢复正常所需时间较对照组延长(P均<0.05)。随访2个月~3.5年,GBS组生长发育基本正常7例、运动发 育落后8例、癫痫发作1例、放弃治疗后死亡3例、失访5例。对照组生长发育基本正常8例、运动发育落后4例、 癫痫发作2例、放弃治疗后死亡4例、失访3例。两组预后情况差异无统计学意义。结论晚发型GBS化脓性脑 膜炎临床表现无特异性，与非GBS化脓性脑膜炎相比更易合并贫血、治疗周期长、并发症发生率较高。 [ABSTRACT FROM AUTHOR]

Sugarcane Cutting Quality (SCQ) has been one of the most important limiting factors in a sugarcane harvester. The sugarcane ratoons can be broken to reduce the budding rate, thus leading to the sugarcane yield decrease in the subsequent year. It is an extremely serious threat to the sugarcane yield for cost-saving planting. This study aims to investigate the effects of axial blade disk vibration and cutting parameters on the cutting quality of sugarcane harvesters. A series of cutting tests were performed on a self-developed test platform of a sugarcane harvester. The SCQ evaluating indexes were selected as the number of sugarcane cracks, the crack thickness, the crack depth, and the number of sugarcanes with broken ratoons. Then, the Comprehensive sugarcane Cutting Quality Evaluating Value (CCQEV) was calculated with the four parameters through the improved entropy as the test index. A regressive equation was established using single-factor tests, the orthogonal test, and the quadratic regressive orthogonal rotary combination test. The axial blade disk vibration was characterized by the vibration amplitude, frequency, and rotation velocity of the blade disk, together with the moving velocity of the sugarcane harvester, the blade installing angle, and their interactions on the SCQ. The results showed that there were strong linear negative relationships between the SCQ and the axial blade disk vibration amplitude, the SCQ and the axial blade disk vibration frequency. The significance coefficients of the axial blade disk vibration amplitude and frequency were 0.002 and 0.035, respectively. There were significant effects on the SCQ. By contrast, the significance coefficients of the sugarcane harvester moving velocity, the blade disk rotation velocity, and the blade disk installing angle were greater than 0.05, indicating no significant effect on the SCQ. The significance coefficients were 0.045 and 0.036 for the interaction of the axial blade disk vibration amplitude and frequency, as well as that of the axial blade disk vibration amplitude and the blade disk rotation velocity, respectively, indicating the significant effects on the SCQ. The significance coefficients of other interactions were greater than 0.05, indicating no significant effect on the SCQ. The significance levels were ranked in the descending order of the axial blade disk vibration amplitude > frequency > the sugarcane harvester moving velocity > the blade disk rotation velocity > the blade disk installing angle. There was a specific interaction between the axial blade disk vibration amplitude and frequency and that between the axial blade disk vibration amplitude and the blade disk rotation velocity. The greater the blade disk vibration amplitude and frequency were, the greater the CCQEV was, and the worse the SCQ was. The greater the blade disk vibration on axial amplitude and the blade disk rotation velocity were, the greater the CCQEV was, and the worse the SCQ was. Moreover, a high-speed camera was used to capture the sugarcane-cutting process. Several times of cutting rather than one time were implemented in the sugarcane harvester, due to the axial blade disk vibration. There was an outstanding height difference between the cut-in points. The significance levels of the axial blade disk vibration amplitude and frequency were higher than those of the rest. There was also some effect of the interaction between the axial blade disk vibration amplitude and frequency on the SCQ. Therefore, an analysis was made to clarify the influencing mechanisms of the axial blade disk vibration amplitude and frequency as well as their interaction with the SCQ from the angle of the multi-cutting process. The vibration amplitude of sugarcane harvesters decreased to improve the natural frequencies of the body frame, whereas, the cutting system of sugarcane harvesters increased to avoid the resonance phenomenon. This finding can provide a strong reference for the higher SCQ in sugarcane harvesters. [ABSTRACT FROM AUTHOR]