为进一步增强Ni/CNTs复合镀层的耐腐蚀性、耐摩擦以及耐磨损性,采用多巴胺(DA)对碳纳米管(CNTs)进行表面改性处理,增强CNTs的亲水性以及与镀层金属间的结合力.高分辨透射电镜(HRTEM)和能谱仪(XPS)检测表明,处理后的CNTs被聚多巴胺(pDA)膜包裹,膜厚最高达3.6 nm.其后本研究使用球盘式摩擦磨损实验机和电化学工作站对复合镀层的摩擦学性能和腐蚀性能进行了测试.结果表明:Ni/CNTs@pDA复合镀层的性能优于纯镍镀层.最后本研究使用氟硅烷(FAS)对镀层表面进行改性,从而构建超疏水表面,接触角测试仪分析表明静态接触角最高可达152.7°.

文章提出基于建构主义理论的工程制图教学改革,使学生由被动参与变为主动参与,不断实现从支架内一个重要支点向另一重要支点攀升.同时,纳入结果考核与过程考核进行效果评价,并兼顾拔尖教育思维.教学实践表明,实验组比对照组学生的课堂氛围更活跃,教学效果显著提高.

Maintainability is used to evaluate product’s ability to return to normal operation state when a product is in use. In this paper, a comprehensive maintainability evaluation model for subsystems of CNC machine tools is proposed by building a hierarchy-structured model based on the AHP and incorporating information entropy method. The model is used to evaluate maintainability for subsystems of CNC machine tools. At last, we use a type of machining centers as an illustrative example to comprehensively evaluate maintainability of subsystems and draw the conclusion that CNC system has the best maintainability. The analysis result shows that the method is effective and feasible with important value in engineering application.

To improve the deficiency of previous reliability evaluation methods of CNC machine tools, an evaluation method based on function monotonicity is proposed to evaluate the reliability of CNC machine tools. First, residual correlation method is used to eliminate abnormal data. Second, an empirical distribution function of CNC machine tools is established through mean rank method. Furthermore, reliability models of CNC machine tools are developed, and model parameters are estimated through maximum likelihood method. A comprehensive evaluation method is adopted to select the optimal distribution function, which is the model used in our study. Finally, the interval of mean time between failures is estimated on the basis of function monotonicity. The proposed method is also used to evaluate the reliability of a certain CNC lathe. Results verify the feasibility and effectiveness of the proposed method.

Different abrasive particles and polishing pads have important impact on ultrasonic flexural vibration assisted chemical mechanical polishing (UFV-CMP) for the sapphire. Such effect was investigated using a self-made UFV-CMP equipment. The particles were diamond, alumina and silica. The pads were polyurethane pad with porous surface and no grooves, IC1000 pad, and IC1000/Suba. compound pad. The MRRs based on weight reduction show that the sapphire MRR of the silica slurry is 3.2 mu m/h. It is close to 3.8 mu m/h for the alumina slurry and much bigger than that of of the diamond slurry, 0.3 mu m/h. Moreover, the sapphire surface polished by the silica slurry is smooth without damage observing from AFM. The roughness of the polished sapphire caused by different polishing pads is similar to be about 0.1 nm. However, the sapphire MRR of the polyurethane pad is 3.2 mu m/h, much bigger than 1.9 mu m/h of the IC1000 pad and 1.6 mu m/h of the IC1000/Suba. compound pad. Therefore, the silica slurry and polyurethane pad are suitable for sapphire UFV-CMP to simultaneously obtain high MRR and atomically smooth surface.

The excellent wear resistance and corrosion resistance are needed for composite coating of remanufacturing parts.The composite coatings of Ni-CNTs,Ni-CNTs/PTFE and Ni-WC/PTFE-CNTs were prepared on 45 steel surfaces with brush plating.The surface morphology and microstructure of coatings were observed by XRD or SEM,and the properties of dry friction and wear were measured by ball on disc wear tester,then the corrosion resistance was tested with potentiodynamic polarization curve in 3.5％ NaCl solution.The results showed that the Ni-WC/PTFE-CNTs composite coating had the best wear resistance,and was followed by that of Ni-CNTs/PTFE and Ni-CNTs,which were all better than pure Ni coating.The wear resistance of the Ni-CNTs composite coating with 1.5 g/L was the best.The corrosion resistance of the Ni-CNTs composite coating with 1.0 g/L was the best,and was followed by the wear and corrosion resistance of Ni-WC/PTFE-CNTs,Ni-CNTs/PTFE composite coatings.The worn mechanism of pure Ni coating and Ni-CNTs composite coating were adhesive wear,while the worn mechanism of Ni-CNTs/PTFE composite coating was mainly adhesive wear,and was followed by abrasive wear,and the worn mechanism of Ni-WC/PTFE-CNTs composite coating was mainly abrasive wear and contact fatigue wear.

Based on the new generation geometrical product specifications(GPS),the calculation methods of measurement uncertainty,such as the Monte Carlo simulation method,the gray system model method,and the guide to the expression of uncertainty in measurement(GUM)method,were analyzed. The results were shown that the val﹣ues of calculated uncertainty were similar,which were computed by the Monte Carlo simulation and the GUM meth﹣od. The calculation results became more accurate with the Monte Carlo simulation method,which overcame some de﹣fects of traditional GUM method. Grey system model method was suited for the small sample data. Then its uncer﹣tainty calculation was simplification with less limiting conditions to calculation process,and it doesn't have to distin﹣guish class A and class B in uncertainty system.

针对原有不确度理论体系的不足,对基于新一代产品几何技术规范(GPS)依从不确定度的理论与应用进行研究.通过对偶性原理,使认证操作链和规范操作链一致,根据依从不确定度的缺省理论,评定依从不确定度.利用依从不确定度代替一般的测量不确定度分析,应用到机加工表面.研究表明:采用依从不确定度对机加工表面进行评定,能使新一代的GPS不确定度更具有实用性;不同加工方法的依从不确定度存在差异,铣加工的不确定度最大,其次是车加工、刨加工、镗加工;不同测量方法和拟合方法对依从不确定度也存在影响,其中依从不确定度从小到大依次为蒙特卡洛、GUM、灰色系统模型.

结合近些年在理工科大学生创新创业能力培养方面的探索和实践,总结出一条将创新创业教育教学理论体系与创新创业实践相结合的大学生创新创业能力培育体系.主要培育体系包括:以全方位系统化的创新创业教育教学体系和创新创业基地作为基础和保障,为培养大学生创新创业能力提供理论基础和支撑平台;以多层次立体化的大学生创新创业实践活动作为载体和核心,为锻炼和提高大学生创新创业能力提供实践机会和施展平台;以学生创新创业硕果和用人单位认可为效果体现,为培养大学生创新创业能力发挥示范作用.

针对太阳能存在着低密度、间歇性、空间分布不断变化的缺点,为了达到更充分高效地利用太阳能,设计了一种双轴液压全景太阳能自动跟踪系统.该系统采用液压装置作为动力源,同时为液压马达和液压缸提供动力,合理地分配系统动力;机械系统具有自锁以及较强的抗风、抗干扰、稳定性能;通过电控系统控制电磁阀开关,实现系统的三维运动;通过传感与控制系统实现太阳能的全方位自动跟踪.

基于MC9S12XS128单片机,采用光电跟踪原理和传感器定位跟踪方式,设计高精度太阳智能跟踪系统.控制系统包括LCD显示模块、实时时钟模块、光电传感器模块、风力传感模块、无线通信模块、液压驱动模块等.该系统通过人工智能和自动化控制,实现全景式、稳定、准确的自动追踪.该太阳能跟踪系统结构简单、价格低廉、功能全面、系统稳定以及具有自我保护功能,既可以保证系统追光的精确性,又可以满足不同地域和环境的使用要求.

研究了聚氨酯纳米氧化锡锑(ATO)透明隔热涂料的分散工艺,分析了水性浆料分散剂(螯合型、离子型、嵌段型分散剂)和分散方法(高速剪切、超声分散)、分散时间等对涂料可见光透过率和近红外阻隔率的影响.结果表明,螯合型分散剂效果最优,因其与ATO形成的螯合物更稳定;高速剪切分散与超声分散结合比采用单一分散工艺分散效果更好.综合来看,采用螯合型分散剂,对水性浆料高速剪切分散2h与超声分散20min相结合所制得的涂料隔热效果最好.

Machined surfaces were simulated by WM fractal function. The Areal characterization parameters (14+3)system was analyzed completely with the least square plane as the datum plane,which included four types of parameters of the amplitude parameters,the space parameters,the integrated parameters,and the function parame-ters. The relation between the fractal dimension of 3D WM surfaces and characterization parameters were analyzed in order to research the effect of surface roughness parameters on the surface function. The results showed that the 3D WM surfaces were similar to the Gauss surfaces and obeyed the Gauss distribution. The relation existed between the fractal dimension of 3D WM surfaces and characterization parameters. The linear relationship between amplitude pa-rameters ,comprehensive parameters and fractal dimension indicated the close relationship of the two parameters and surface function. The little change of the space parameters and the function parameters with the fractal dimension of surfaces explained that the effect of the two parameters on surface function was little.

为了制备隔热性能和透光性均较好的建筑物玻璃隔热涂料,以水性聚氨酯为成膜物质,纳米氧化锡锑(ATO)和纳米二氧化钛(TiO2)为填料,制备了水性纳米透明隔热玻璃涂料.采用扫描电镜、隔热膜温度测试仪及紫外分光光度计对纳米ATO与TiO2粒子在涂料涂膜中的分散稳定性、涂料涂膜的隔热性能及光学性能进行了分析,研究了纳米TiO2与ATO浆料配比及涂膜厚度对涂料涂膜性能的影响.结果表明:纳米ATO与TiO2浆料通过硅烷偶联剂KH-570改性,再辅以分散剂分散,经过高速分散和超声波分散后,与聚氨酯复合制得了分散稳定的复合透明涂料;该涂料不仅具有良好的成膜性能,且涂膜经红外灯照射60 s后,与空白玻璃对比,隔热温差最高达6.23℃,在保证良好的可见光透过率及隔热性能的前提下,最佳纳米TiO2与ATO浆料体积比为2∶20,最佳涂膜厚度为75μm,此时涂料涂膜隔热温差达3.60℃.

Wenzel and Cassie models are two main kinds of solid-liquid wetting models on the rough surfaces.Cassie wetting model is helpful to super-hydrophobic and self-clean function of micro-structure surfaces,so that it is a must for su-per-hydrophobic surfaces to prevent solid-liquid interface transiting from Cassie model to Wenzel model.The transition mechanism of Cassie /Wenzel(C /W)wetting model and the condition to prevent C /W wetting model transition were re-searched.The results show that the size of surface energy is the decisive factor for wetting model transition.In order to pre-vent C /W wetting model transition,the suitable micro structural parameters are selected so that the Cassie model’s energy is under Wenzel model’s.For single grade micro structure surfaces of column /square concave and column /square convex, the C /W wetting model transition can be prevented by increasing the concave depth and convex height or reducing the spacing of concave and convex.The concave micro-structures are helpful to prevent C /W wetting model transition and even more suitable to prepare super-hydrophobic surfaces.

In this paper,a fuzzy adaptive adjusted mold variable structure control(VSC) approach was proposed by combining normal VSC with the theory of fuzzy control.This approach not only keeps good robustness and adaptively,but also decreases the chattering produced by sliding mold variable structure control.In case of given parameters,this approach is applied to the missile attitude control system and its effectiveness is shown via the result of simulation.

On the basis of lotus leaf surface with irregular self-similar micro/nano dual structure,fractal geo-metry was used to construct random fractal structure similar to the lotus leaf.The corresponding contact angle equations with Cassie,Wenzel model were established,and the effects of fractal dimension and structural parameters on wettability of the random fractal structure were analyzed.The results show that the structure becomes compacter and the contact angle becomes bigger with the increasing of fractal dimension for the surface fractal structure,and the contact angle becomes greater with the larger ratio of micro/nano scale parameter.However,the apparent contact angle of Wenzel model can not reach 150° with super hydrophobic even if the fractal dimension is tend to the maximum 3.0.The maximum apparent contact angle of Cassie model is larger than 150°.So Cassie model is more suitable for superhydrophobic surface.

In order to find the key subsystems which affect the reliability of the CNC machine tools is an important and yet harder problem due to the lack of failure data and statistical analysis. A novel method based on posterior probability function for identifying the key subsystems of the CNC machine tools was proposed. Firstly, subsystem reliability of the CNC machine tools was estimated using the John estimator, since the failure data were censored. Secondly, parametric fitting was conduct with Weibull distribution using the maximum likelihood estimation (MLE) or the least square estimation (LSE). Thirdly, the probability function of each subsystems were attained by the reliability modes of the systems and the whole system. Finally, a case study was given, which proved that the proposed method could find out the key subsystems rapidly and accurately.

针对当前高等学校工科课程教学存在的不足,探索了以工程教育为目标的课程教学设计方法。结合工程制图、机械设计等高校工科基础课程的教学,依据教学设计理论与模型,以培养大学生的动手实践能力、分析解决实际问题的能力和创新能力等为目标,充分运用各种先进的教学手段,探索合适的课堂教学设计、教学方法与教学评价等,以改善教学效果、提高教学质量,培养具有较强实践工作能力与创新能力的高素质工程技术型人才。

One algorithm of sliding terminal guidance law,which can effectively intercept the target of the reentry aerosphere,is devised based on the zero effort miss(ZEM).Firstly,the model of the missile and target movement is built;then,the target acceleration information is estimated by using the extended state observer(ESO),and the zero effort miss algorithm is analyzed so that the thinking of the designing is carried out;then the guidance law is reduced by using the back stepping control;at last,the simulation result shows that the designed guidance law intercept the target effectively and the virtual command can track the actual command well so that the validity of the algorithm is tested.