摘要：
The three-row and four-column slewing bearing is used as the slewing guarantee for large equipment, such as TBM. This particular structure provides an improvement in the bearing capacity, meanwhile, it also has different behaviors compared to conventional roller slewing bearing. In order to pay attention to different roller design parameters and axial clearance for the effect on its roller safety factor, specific analysis tools must be developed. First, this paper presents a set of load distribution and contact stress analytical method based on the actual contact behavior, and FEM is used to assure its reliability. Secondly, the influence of different roller crownings on the generatrix contact stress is analyzed by using the proposed method, and the optimization algorithms get involved in improving the roller crowning and reduce the max contact stress by about 5%. Finally, taking the roller safety factor as the evaluation index, the orthogonal experiment is carried out with 6 key design parameters, and their influence characteristics and priorities are analyzed.
摘要：
目的应用动态信号分析法评估无创正压通气(NPPV)时不同吸气努力对肺力学模型呼吸力学参数测算的影响。方法选择ASL5000机械模拟肺模拟体重为65~70 kg的半卧位健康成年人、慢性阻塞性肺疾病和急性呼吸窘迫综合征患者。吸气压力(P_(mus))分别为0、5.0、10.0和15.0 cm H_(2)O。Respironics V60呼吸机以自主/时间控制模式运行,呼气末正压为5.0 cm H_(2)O,调整P_(mus)使呼吸机输出潮气量为7.0 mL/kg,后备通气频率为10次/min。收集系统泄漏量为25~28 L/min时的通气参数变化并计算呼吸力学参数系统顺应性(C_(rs))和气道阻力(Raw)。结果随着P_(mus)增大,三种肺力学模型的驱动压(DP)逐渐减小;P_(mus)超过10.0 cm H_(2)O后健康成年人模型的呼出潮气量显著超过7.0 mL/kg,DP降至1.0 cm H_(2)O。高水平P_(mus)时C_(rs)呈过高测算,而Raw测算值显著降低。低水平P_(mus)时慢性阻塞性肺疾病和急性呼吸窘迫综合征模型的呼气阻力(R_(exp))和C_(rs)测算误差≤10%,不同P_(mus)水平时吸气阻力(Rinsp)测算值均显著低于预设值(P<0.01)。结论通过应用动态信号分析法,可实现NPPV时在不阻断自主呼吸条件下连续监测C_(rs)和Raw(尤其是R_(exp)),过强的P_(mus)会导致呼吸力学测算误差增大。
摘要：
Response surface methodology (RSM) was used to optimize the preparation conditions of nano-hybrid wood/polymer composites with montmorillonite (MMT) and furfuryl alcohol (FA). The effects of MMT amount, impregnation pressure and impregnation time on weigh percent gain (WPG) of treated samples were evaluated with Box-Behnken design (BBD) of a 3-level-3-factor from RSM. The predictive model for the response was extremely significant (p < 0.01). The determination coefficient (R-2) and the adjusted determination coefficient (root R-2 ) of this model were 0.9651 and 0.9203, respectively. The optimal preparation conditions obtained by RSM design with the assistance of Design Expert were determined as follows: 4 wt% MMT amount, 0.8 MPa impregnation pressure, and 80 min impregnation time. It could be concluded from the SEM images that MMT and FA coated the cell walls and filled cell lumens. Moreover, the thermal stability was also investigated. The effects of preparation conditions were further validated by analyzing the water uptake ratio (WU), modulus of elasticity (MOE) and modulus of rupture (MOR) of the pristine samples and the treated samples prepared under optimized conditions.
期刊：
ISA Transactions,2021年112:315-325 ISSN：0019-0578
通讯作者：
Chen, Jie
作者机构：
[Nian, Xiaohong; Hou, Hailiang; Su, Mei; Chen, Jie] Cent South Univ, Sch Automat, Changsha 410083, Hunan, Peoples R China.;[Hou, Hailiang; Chen, Jie] Hunan Univ Humanities Sci & Technol, Sch Informat, Loudi 417000, Hunan, Peoples R China.;[Yang, Tongguang] Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413000, Hunan, Peoples R China.
通讯机构：
[Jie Chen] S;School of Automation, Central South University, Changsha, Hunan Province, 410083, China<&wdkj&>School of Information, Hunan University of Humanities, Science and Technology, Loudi, Hunan Province, 417000, China
关键词：
Coordination variable;Decentralized coordinated optimal guaranteed cost control (DCOGCC);Interval matrix;Linear matrix inequality(LMI);Roll-to-roll web machine
摘要：
This article investigates a coordinated optimal guaranteed cost control (DCOGCC) for a multi-motor roll-to-roll web machine with time-varying and uncertain parameters. The state-space oriented DCOGCC law is designed to ensure that each subsystem of the web machine is stable and the upper bound of performance index is minimum. Linear matrix inequality (LMI) conditions to guarantee the stability of the systems with DCOGCC are derived. A decentralized model is adopted by regarding the entire machine as a synthetic system, then the original decentralized model is transformed into an equivalent one. By choosing appropriate information of consecutive subsystems as coordination variables, the DCOGCC scheme may attenuate the interaction effects between subsystems. The results of some simulations and experiments are given to verify the feasibility and effectiveness of the DCOGCC. (C) 2020 ISA. Published by Elsevier Ltd. All rights reserved.
摘要：
Mg-2.6Sm-1.3Gd-0.6Zn-0.5Zr (wt.%) alloy is prepared with metal mold casting and followed hot extruded at 400 degrees C with the extrusion ratio of 25:1. Microstructure and mechanical properties of the as-extruded alloy are investigated using optical microscope (OM), scanning electron microscope (SEM) with electron backscatter diffraction (EBSD), X-ray diffraction (XRD) and transmission electron microscope (TEM). The results show that the as-extruded alloy is fully dynamically recrystallized, which develops rare earth (RE) texture component. The as-extruded alloy shows an age-hardening response at 200 degrees C, in which there are numerous nano-scale plate strengthening phase beta' precipitated in the matrix. The as-extruded alloy in the peak-aged condition exhibits ultimate tensile strength, yield strength, and elongation of 332 MPa, 220 MPa and 22.7% at room temperature, respectively. The dominant strengthening mechanisms of the investigated alloy are fine-grain strengthening, solid solution strengthening and precipitate strengthening. (C) 2021 The Author(s). Published by Elsevier B.V.
作者机构：
[陈长青; 阳同光] College of Mechanical and Electrical Engineering, Hunan City University, Yiyang;413000, China;Hunan Key Laboratory of Energy Perception and Edge Computing in Smart City, Yiyang;[陈长青; 阳同光] 413000, China<&wdkj&>Hunan Key Laboratory of Energy Perception and Edge Computing in Smart City, Yiyang;[陈长青; 阳同光] 413000, China
关键词：
柔性负荷;合同策略;削峰填谷;时序互补;光伏消纳
摘要：
具有"虚拟储能"作用的柔性负荷能够从时空上改变原有负荷分布,降低峰谷差,然而现有规划并未对其进行深入研究。为此,通过构建柔性负荷响应模型,并提出优先将高峰时段柔性负荷转移至光伏出力高峰期的合同策略,进而提高光伏利用率。其次,构建计及柔性负荷的储能和光伏协调规划模型,以便充分发挥柔性负荷"削峰填谷"及光储时序互补作用。最后,通过对10k V 37节点实际配电网进行仿真。结果表明,从经济角度分析,柔性负荷相比储能更具优势,能有效降低储能容量配置和提高光伏消纳能力。
关键词：
finite element method;laminated cylindrical nanoshell;sensitivity analysis;bi-directional thermal loading;FGDQM
摘要：
In this article, frequency characteristics, and sensitivity analysis of a size-dependent laminated composite cylindrical nanoshell under bi-directional thermal loading using Nonlocal Strain-stress Gradient Theory (NSGT) are presented. The governing equations of the laminated composite cylindrical nanoshell in thermal environment are developed using Hamilton's principle. The thermodynamic equations of the laminated cylindrical nanoshell are obtained using First-order Shear Deformation Theory (FSDT) and Fourier-expansion based Generalized Differential Quadrature element Method (FGDQM) is implemented to solve these equations and obtain natural frequency and critical temperature of the presented model. The novelty of the current study is to consider the effects of bi-directional temperature loading and sensitivity parameter on the critical temperature and frequency characteristics of the laminated composite nanostructure. Apart from semi-numerical solution, a finite element model was presented using the finite element package to simulate the response of the laminated cylindrical shell. The results created from finite element simulation illustrates a close agreement with the semi-numerical method results. Finally, the influences of temperature difference, ply angle, length scale and nonlocal parameters on the critical temperature, sensitivity, and frequency of the laminated composite nanostructure are investigated, in details.
期刊：
Journal of International Medical Research,2021年49(2) ISSN：0300-0605
通讯作者：
Chen, Yuqing
作者机构：
[Chen, Yuqing; Li, Feng; Zhou, Xin; Zhang, Hai] Shanghai Jiao Tong Univ, Shanghai Chest Hosp, Dept Pulm & Crit Care Med, Shanghai, Peoples R China.;[Yuan, Yueyang] Hu Nan City Univ, Sch Mech & Elect Engn, Yi Yang, Peoples R China.;[Chen, Yuqing] Shanghai Jiao Tong Univ, Shanghai Chest Hosp, 241 Huahai West Rd, Shanghai 20030, Peoples R China.
通讯机构：
[Chen, Yuqing] S;Shanghai Jiao Tong Univ, Shanghai Chest Hosp, 241 Huahai West Rd, Shanghai 20030, Peoples R China.
关键词：
Dynamic respiratory mechanics;pressure support ventilation;pulmonary compliance;resistance;tidal volume;airway compliance;airway resistance
摘要：
Objective To evaluate the accuracy of respiratory mechanics using dynamic signal analysis during noninvasive pressure support ventilation (PSV). Methods A Respironics V60 ventilator was connected to an active lung simulator to model normal, restrictive, obstructive, and mixed obstructive and restrictive profiles. The PSV was adjusted to maintain tidal volumes (V-T) that achieved 5.0, 7.0, and 10.0 mL/kg body weight, and the positive end-expiration pressure (PEEP) was set to 5 cmH(2)O. Ventilator performance was evaluated by measuring the flow, airway pressure, and volume. The system compliance (C-rs) and airway resistance (inspiratory and expiratory resistance, R-insp and R-exp, respectively) were calculated. Results Under active breathing conditions, the C-rs was overestimated in the normal and restrictive models, and it decreased with an increasing pressure support (PS) level. The R-insp calculated error was approximately 10% at 10.0 mL/kg of V-T, and similar results were obtained for the calculated R-exp at 7.0 mL/kg of V-T. Conclusion Using dynamic signal analysis, appropriate tidal volume was beneficial for R-rs, especially for estimating R-exp during assisted ventilation. The C-rs measurement was also relatively accurate in obstructive conditions.
