DRNN神经网络逆控制方法在DDV伺服系统中的应用

对于直接驱动阀(DDV)式作动器伺服系统,由于很难找到最佳的参数匹配以及回路中存在死区非线性因素,使得传统的PID控制无法取得令人满意的控制效果.为此提出一种动态对角回归神经网络(DRNN)逆控制方法,该逆系统控制方法是将对象的逆模型作为控制器加入到控制回路里面,并与控制对象串联构成一个伪单位环节,使得系统的输出能够跟踪系统的输入,经过仿真实验,可以看出该神经网络逆控制比单一PID控制器的动态性能要好.     

Epidermal growth factor receptor and transforming growth factor alpha expression in papillary and nonpapillary renal cell carcinoma: correlation with metastatic behavior and prognosis

Papillary renal carcinomas are a cytogenetically unique subset of renal carcinomas that have been reported to be clinically less aggressive. We have examined 19 papillary tumors for immunohistochemical expression of the epidermal growth factor receptor (EGF-R) and its ligand, transforming growth factor alpha (TGF-alpha). EGF-R and TGF-alpha expression was also studied in 149 nonpapillary tumors and 7 mixed papillary/solid tumors. EGF-R and TGF-alpha expression were compared to histology, stage, metastatic behavior, and survival. Formalin-fixed, paraffin-embedded nephrectomy specimens collected between 1977 and 1986 were stained with antibodies to EGF-R and TGF-alpha. Patients with papillary tumors were found to present with earlier stage disease and had significantly longer survival. Papillary tumors had a significantly lower rate of EGF-R positivity than solid pattern tumors (21% versus 73%, P < 0.001). Intermediate or strong cell membrane immunoreactivity for EGF-R was associated with high tumor grade and poor disease-specific survival. EGF-R positivity in the primary tumor was associated with the presence of metastatic disease and with metastatic spread to lung versus bone. Tumor parenchymal TGF-alpha staining was present in 50% of the cases and was not associated with stage or grade. Unrelated to tumor parenchymal TGF staining, tumor vessels stained for TGF-alpha in 56% of the cases. Vessel TGF-alpha staining was absent in papillary tumors (P < 0.001). The improved clinical behavior of papillary tumors as compared to nonpapillary renal tumors may be related, in part, to their relatively lower levels of EGF-R expression.     

Epitope mapping using histidine-tagged protein fragments: application to Escherichia coli RNA polymerase sigma 70

The pathogenic Neisseria have exploited the processes of horizontal DNA transfer and genetic recombination as mechanisms for the generation of extensive protein variation and modulation of gene expression. Localized recombinations have been well documented in members of multigene families as have alterations in short repetitive sequences. Here we report an analysis of the chromosomal structure of a defined lineage of Neisseria gonorrhoeae strain MSl1 pilin variants. This study reveals the occurrence of large rearrangements, including the amplification of a 26 kb region and an inversion involving more than a third of the chromosome. Additionally, a restriction site polymorphism that correlates with pilin expression has been observed. These findings highlight the flexibility of the gonococcal genome.     

低压散绕变频电机绝缘薄弱点定位方法研究

根据IEC相关标准,采用重复脉冲和正弦电压测定变频电机绝缘系统PDIV,是评估低压散绕变频电机绝缘性能的关键手段.然而,现行IEC标准难以识别定子绕组绝缘薄弱点.对此,联合重复脉冲和正弦PDIV离线测试技术,提出定位变频电机绝缘薄弱点的三步法:首先采用重复脉冲电压测定电机匝间绝缘PDIV;然后利用正弦电压测定相间及...     

兼顾操纵性与节能性的ECHPS可变助力特性与控制策略

转向系统的助力特性设计与控制对重型车辆的操纵稳定性和节能性具有重要影响。以重型商用车旁通比例阀式电控液压转向系统(Electronically controlled hydraulic power steering system,ECHPS)为研究对象,在Matlab/Simulink中建立包含比例电磁阀子模型、机械系统子模型、液压系统子模型和3自由度整车转向动力学模型的ECHPS系统仿真模型,基于能量流原理分析转向助力特性对转向系统节能性的影响,设计了兼顾操纵性与节能性的ECHPS可变助力特性曲线。采用模糊比例积分微分(Proportional integral derivative, PID)控制策略对比例电磁阀的阀芯位移进行控制,使旁通流量随车速可变。搭建ECHPS性能试验台,对ECHPS在不同车速下的助力特性进行测试,试验结果与仿真设计的理想可变助力特性基本一致,可以实现重型车辆低速时转向轻便性和高速时的良好路感,同时改善了转向系统的节能性。     

Evaluation of the injured wrist on the field and in the office

The wrist is a common site of injury in sports, both acute and chronic. Evaluation of wrist injuries requires knowledge of anatomy kinematics, attention to the mechanism of injury, the intensity of training, and a focus on the physical examination for specific injuries.     

热喷涂焊层车削加工工艺的探讨

本文针对轴类热喷涂焊层中喷涂层、喷焊层的车削加工工艺进行分析 ,从设备调整、刀具牌号选择、刀具几何参数选择三个方面进行研究 ,对加工工艺进行改进 ,在实际生产中具有一定的价值     

船舶液压推进系统螺旋桨负载转矩模拟研究

针对船舶液压推进实验装置模拟加载的需要,提出一种基于液压系统的双向加载负载模拟系统。采用面向系统原理建模的LMS AMESim软件搭建船舶液压推进系统仿真模型,利用Simulink仿真工具建立船桨模型,联合二者完成了船舶液压推进负载模拟整体仿真模型,仿真结果表明液压推进负载模拟系统能够较好地模拟螺旋桨的各工况的负载转矩,为下一步搭建船舶液压推进负载模拟装置提供研究基础。     

STL文件快速分层及填充算法研究

在研究STL文件的基础上,充分分析了分层时切面与三角面片可能存在的关系。提出的填充算法,在充分保证速度的同时,能够避免以往分层之后还需对轮廓按外轮廓逆时针、内轮廓顺时针排序的做法,可以高效地处理以往采用传统算法难以处理奇点的问题。     

油液检测技术在工程机械中的应用

分析了工程机械油液检测技术的主要目的、内容和技术现状,提出了在工程机械中应用油液检测技术的对策,提出了未来工程机械油液检测技术的发展方向。