Micro dimple milling on cylinder surfaces

The paper presents a micro dimple machining on a cylinder surface with a two-flutes ball end mill. When the cutter axis is inclined and the depth of cut is less than the tool radius, non-cutting time, during which neither of the two cutting edges contacts the workpiece, appears in a rotation of the cutter. The rotation of the workpiece and the feed of the tool are controlled so that the cutting areas do not overlap each other. In order to incline the tool with respect to the tangential direction on the cylinder surface, the tool is located at a position oriented at 45° from the top of the cylinder. An analytical model is presented to control the shapes of the dimples with the cutting parameters. The presented machining is verified in cutting tests with measuring the shape and the profile of the dimples. Pre-machining operations are conducted to have a high cylindricity of the workpiece in longitudinal turning and polishing. The cutter runout of the tool is also eliminated by adjusting the orientation and the position of the tool in the collet chuck with measuring the cutting force. The micro dimples are machined accurately as they are simulated.     

Smooth surface fabrication in mask projection based stereolithography

The surface finish is critical for applications such as optics, micro-fluid flow and mechanical assembly, in which optical lenses, fluidic channels and rotating components are all required to be smooth. However, the stair-stepping effect is well known in the layer-based additive manufacturing processes, in which a three-dimensional model is approximated by a set of two-dimensional layers. Consequently the fabricated surfaces have poor surface finishes especially those that are close to the horizontal plane. In this paper, a novel approach for achieving improved surface finish is presented for the mask-image-projection-based stereolithography (MIP-SL) process. Theoretical models and parameter characterization are presented for the developed methods. Accordingly, the process planning and calibration approaches for fabricating smooth up-facing surfaces in the MIP-SL process have been developed. Multiple test cases based on various types of curved surfaces have been performed. A comparison of the build results based on the traditional and the newly developed approaches illustrates the effectiveness of our method.     

滚筒式高温堆肥中微生物种类数量的研究

定量地研究了城市生活垃圾高温好氧堆肥中微生物的种类和数量分离鉴定出了细菌5属20株、霉菌8属13株、放线菌1属3株、酵母菌2属2株．探明了高温好氧堆肥能杀灭绝大多数细菌,细菌和霉菌是堆肥的优势类群,芽孢杆菌和曲霉菌是优势种．     

Enhancement of photocatalytic efficiency by in situ fabrication of BiOBr/BiVO4 surface junctions

Surface junctions between Bi OBr and BiVO_4 were synthesized. The BiOBr/BiVO_4 with 1 wt.%of Bi OBr exhibited the highest photocatalytic activity in the degradation of Rh B under visible-light irradiation. It was found that the highly efficient adsorption of Rh B molecules via the electrostatic attraction between Br-and cationic \N(Et)_2 group played a key role for the high photocatalytic activities of BiOBr/BiVO_4. This efficient adsorption promoted the N-deethylation of Rh B and thus accelerated the photocatalytic degradation of Rh B.Moreover, the metal-to-metal charge transfer(MMCT) mechanism was proposed, which revealed the concrete path paved with Bi–O–Bi chains for the carrier migration in BiOBr/BiVO_4. The interaction between photoexcited Rh B* and the Bi~(3+) in BiVO_4 provided the driving force for the migration of photo-generated carriers along the Bi–O–Bi chains. This work has not only demonstrated the important role of efficient adsorption in the photocatalytic degradation of organic contaminants, but also developed a facile strategy to improve the efficiency of photocatalysts.     

河道生态护坡对地表径流的污染控制

在上海市进木港生态河道示范区,通过现场模拟径流试验,研究了柴笼、灌丛垫、植草3种不同类型的生态护坡对地表径流的延滞作用和污染控制作用.结果表明,生态护坡在控制地表径流污染方面具有良好的生态效益,柴笼对地表径流的平均延滞时间为28.00～33.33min,可拦截80.95%粒径为30.07～111.05μm的悬浮固体,可截留92.58%～97.15%的水溶态营养盐和75.75%～91.24%的泥沙结合态营养盐.灌丛垫使地表径流进入河道的时间比对照裸坡滞后9.70～15.33min,可有效截留88.53%～92.94%的水溶态营养盐;但其对悬浮颗粒的拦截能力比柴笼和植草护坡弱.植草护坡延滞地表径流的能力不及柴笼和灌丛垫,但其对地表径流中较小粒径的悬浮固体(14.89～52.63μm)和泥沙结合态营养盐的拦截率分别达到85.93%和80.53%～85.33%.研究还探讨了生态护坡对地表径流污染的控制与植被覆盖度、土壤含水率以及土壤抗剪强度等指标的关系,并提出了控制地表径流污染的生态护坡优化组合方案.     

微电解工艺处理染料工业废水研究

该文研究了采用微电解工艺处理染料工业废水。经过微电解工艺处理的染料工业废水色度和化学需氧量（COD）去除率分别为93．94％和64．62％。废水的可生化性提高．生化速率常数K从0．02876提高到0，04754。微电解工艺预处理该染料工业废水的吨水远行成本为0．91元。     

微生物絮凝剂菌株的培养条件优化

近年来国内外微生物絮凝剂的研制开发已经成为热点,本实验对微生物絮凝剂产生菌种筛选、培养条件等进行较为系统地研究与探讨。以活性污泥作为菌种来源,高岭土悬液为絮凝对象,在特定筛选培养基中进行菌种培养增殖,从中筛选出具有絮凝活性菌种,记为J3。在原特定的培养基基础上,对培养基的组成和培养条件进行优化,进行了正交实验设计,选择影响微生物絮凝剂发酵培养基的碳氮源(Ⅰ)、培养温度(Ⅱ)、pH值(Ⅲ)和通气量(Ⅳ)等4因素进行试验,得到了J3菌最佳培养条件。     

水处理滤料润湿性的实验研究

基于Washburn方程用亲油亲水比(LHR)比较了无烟煤、沸石和石英砂滤料对油的润湿选择性,并对其表面结构进行了表征.结果表明,无烟煤、沸石和石英砂的LHR值依次为2.41、0.64和0.65,沸石和石英砂的亲水性明显好于无烟煤,而无烟煤的亲油性好于沸石和石英砂.这主要取决于滤料的表面化学组成,同时与其表面形貌有一定的关系,与SEM、XPS、FTIR分析结果基本吻合.     

差压式测风微传感器敏感元件的设计

目的提高测风微传感器的测量准确性。方法首先通过有限元仿真软件对差压式测风微传感器敏感元件材料进行仿真,确定结构参数;其次对风测量元件结构周边的风压分布进行模拟,建立最佳风压分布方程,并基于风压分布方程设计风速风向解算算法。结果通过对风压分布的仿真与分析,提出了多导风孔的结构设计及带硅岛压力膜作为风压感压膜的方法。结论该方法提高了测风微传感器的测量准确性。     

微量／痕量有机污染物前处理技术研究进展

由于有毒有机物在环境中含量极低,且受到共存基质的干扰,前处理成为整个有毒有机物分析工作的重要一环。本文主要介绍了当前常用的前处理技术（如液液萃取、固相萃取、固相微萃取、顶空法、吹扫捕集、索氏提取、超声提取、加压溶剂萃取、超临界流体萃取）,并对一些方法进行了归纳对比。在此基础上,对环境中有毒有机物前处理技术的发展方向进行了展望。     

Hybrid hierarchical fabrication of three-dimensional scaffolds

Three-dimensional (3D) porous structures facilitating cell attachment, growth, and proliferation is critical to tissue engineering applications. Traditional solid freeform fabrication (SFF) methods have limited capabilities in the fabrication of high resolution micro-scale features to implement advanced biomedical functions. In this work, we present a hybrid scaffold fabrication approach by integrating electrohydrodynamic (EHD) printing technology with extrusion deposition together to fabricate hierarchical 3D scaffolds with well controlled structures at both macro and micro scale. We developed a hybrid fabrication platform and a robust fabrication process to achieve 3D hierarchical structures. The melting extrusion by pneumatic pressure was used to fabricate 3D scaffolds with filaments dimension of hundreds of microns using thermoplastic biopolymer polycaprolactone (PCL). An electrohydrodynamic (EHD) melt jet plotting process was developed to fabricate micro-scale features on the scaffolds with sub-10 μm resolution, which has great potential in advanced biomedical applications, such as cell alignment and cell guidance.     

基于响应面模型的区域大气污染控制辅助决策工具研发

基于CMAQ模型结果,利用高维克里金插值算法,建立了排放控制因子与污染物环境浓度的响应面模型(RSM),实现了大气污染可控源排放与复合污染水平的实时函数响应.研究结果显示,RSM对PM2.5的预测结果与CMAQ实际模拟结果的误差在容许范围内(最大误差小于0.20μg.m-3,3.89%).基于所建立的RSM,开发了RSM-VAT区域大气污染控制可视化辅助决策工具.使用RSM-VAT对美国8个典型城市的PM2.5污染状况进行了控制情景分析,通过"可视化展示"和"图表分析"二大模块,输出不同控制情景下的环境污染物浓度的实时响应图、可视化展示和数据分析图表等结果.     

纳米TiO2光催化氧化微量丙酮气的研究

采用溶胶-凝胶法制备了纳米TiO2膜。测试了TiO2光催化剂对微量丙酮气的催化氧化反应性能的测试。结合TG,XRD及TEM等对催化剂的表征,研究了纳米TiO2膜的制备条件对其结构和反应性能的影响,探索了纳米TiO2膜光催化氧化的机理。结果表明：制得的TiO2膜平均粒径为20nm,TiO2膜经550℃焙烧后呈现锐钛型和少量金红石型晶体的混晶。当金红石型的质量分数为13．6％时,TiO2光催化剂表现出较好的催化活性,丙酮的转化率最高达到45．26％。     

铝合金微弧氧化技术应用研究

目的研究铝合金微弧氧化技术在产品三防方面的应用。方法选取四种不同牌号的常用铝合金结构件材料进行微弧氧化处理,并通过各种检测手段测定铝合金微弧氧化膜层的成分及形貌、硬度及耐磨、耐腐蚀等性能指标,并与硬质阳极氧化技术作对比。结果微弧氧化膜层厚度为20～120μm,氧化膜致密层硬度（Hv）〉900,致密层磨损率〈10^-4mm^3／（N·m）,盐雾试验时间〉96h,湿热试验时间〉10个周期,膜层性能优于硬质阳极氧化膜。结论微弧氧化技术能大大提高铝合金的耐磨和耐腐蚀性能,可应用于提升产品三防性能。     

微米炭介导下4-硝基氯苯的还原-氧化耦合修复

针对土壤和地下水中难以去除的污染物4-硝基氯苯(4CNB),本文提出了微米级活性炭(MAC)介导的先还原后氧化的耦合修复工艺.通过序批实验、密度泛函分析、电子顺磁共振分析等手段研究了MAC表面性质、温度对强化硫化物还原4CNB的影响,探究了4CNB还原-氧化反应机理.结果表明在MAC介导下,4CNB可能发生了热力学有利的双电子还原过程,并且MAC对污染物的吸附富集作用减轻硫化物对过硫酸盐氧化过程的影响,高效去除了难以被硫化物还原和过硫酸盐氧化的4CNB.MAC强化下,4CNB还原速率相比单独硫化物作还原剂时提高8～82倍,35℃以上反应4h其降解率超99%.当4CNB还原为4-氯苯胺(CAN)后在炭表面经自由基氧化和过硫酸盐直接氧化去除.本研究提出了一种新的微米炭介导的4CNB还原-氧化耦合修复路线,为利用热处理工艺余热,实现低能耗、低成本修复4CNB污染土壤和地下水提供了新的思路.     

活性炭应用测试新技术——微型快速穿透实验

进行了微型快速穿透(MCRB)实验与中小型、小型传统穿透实验方法的对照实验,结果表明,MCRB实验适用于模拟大型活性炭床的穿透情况,预测处理费用以及精选活性炭.MCRB实验加快了实验速度,避免了传统穿透实验中常见的问题.空床接触时间(EBCT)、活性炭粒径对MCRB实验有一定影响.使用粒径120～180目的活性炭,MCRB实验的压力一般小于3.03×10⁵Pa.MCRB实验对2,4-二氯苯酚(2,4-DCP)和甲基叔丁基醚(MTBE)模拟废水的吸附处理获得合理的研究结果.     

微型轴流风机低温失效分析

目的研究分析风机低温失效的问题。方法通过研究目前市场上及工程中常用的轴流风机驱动的机电模式及结构形式,分析正常产品驱动电路板的组成,采用替换法,并结合目前装备所处的环境条件综合分析。结果微型轴流风机的润滑油在长期低温储存后发生凝冻转动阻力增大,结合轴承的一种特定失效模式,低温加剧了这一模式的进行的速度,使得转子的转动阻力增大进一步恶化。在加电启动时,由于低温时电路的阻抗小,直流无刷电机的堵转电流较常温时增大约2倍以上,从而导致电机驱动电路烧毁。同时由于电机堵转,电机铁芯热损增大,长期堵转后进一步导致线圈漆包线漆皮的烧毁,直至风机电机彻底烧毁。结论与通常认为低温下出现失效的情况很少相反,低温状态下,由于润滑油的凝冻,轴承可能加速失效,可使风机在低温存储后的一次启动或多次启动中出现烧毁现象。     

动态渗透压力法研究水处理滤料的润湿性

润湿性是水处理滤料的一个十分重要的表面性质.以Washburn方程为原理,用动态渗透压力法研究了无烟煤、铝矾土陶瓷及磁铁矿滤料的亲油亲水润湿性.实验结果表明,方法的重现性较好,误差在10%以内.当滤料的粒径范围在0.6～0.9mm之间时.以该法测得无烟煤、铝矾土陶瓷及磁铁矿滤料的亲油亲水比(LHR)值依次为2.511、1.748和1.317,说明无烟煤滤料的亲油性最好,铝矾土陶瓷次之,而磁铁矿的亲油性最差.XPS和FTIR分析结果表明,无烟煤、铝矾土陶瓷及磁铁矿滤料润湿性差别主要归因于其表面化学结构的不同.     

Dimensional analysis and scaling in mechanical mixing for fabrication of metal matrix nanocomposites

For a successful enhancement of mechanical properties of metal matrix nanocomposites, a homogeneous nanoparticle dispersion and distribution in the solidified metal is required. Mechanical mixing can be used for initial break-up of agglomerates, and its study can be simplified with dimensional analysis. Using this technique, mixing time and vortex height were assessed while varying fluid properties, impeller angle, and angular speed. Three relevant dimensionless numbers were recognized: the Reynolds (Re), Froude and Galilei (Ga) numbers. Based on blade and impeller shaft angles, a modified Froude number (Fr*) was defined. These parameters were calculated experimentally, varying angular speed from 200 to 1000 rpm for three different impeller angles: 0°, 15° and 30°. This procedure was performed with three fluids: water, and two aqueous glycerin solutions (25% and 50% by volume). Digital images were taken and processed to measure vortex height. Mixing time was measured for water at 0° impeller angle, angular speed ranging from 200 to 1200 rpm. Results showed an optimal dimensionless mixing time with respect to Re. A linear relationship was found between dimensionless vortex height and Fr*. The first had a second order polynomial relationship with the product ReFr*, regardless of impeller angle. This relationship, together with the Ga, specific for each fluid, allows scaling the results to other fluids such as molten pure aluminum. This study allows experimenting in simpler systems that involve transparent fluids, room temperature and low cost, to then elaborate a prediction of vortex height in fluids where measurements are difficult and costly, such as molten metals.