Vibrational energy loss analysis in battery tab ultrasonic welding

In ultrasonic metal welding processes, high-frequency ultrasonic energy is used to generate friction and heat at the interface between weld parts to produce solid-state bonds. It has been observed that sufficient energy is required to produce proper bonding, while excessive energy can cause such quality issues as weld fracture and perforation. Therefore, it is important to have a product/process design in ultrasonic welding to ensure efficient energy conversion from ultrasonics to welding energy, minimizing energy loss in the process. In this work, vibrational energy loss associated with the longitudinal and flexural vibrations of the Cu coupon during ultrasonic welding is studied by applying one-dimensional continuous vibration models. To facilitate our modeling, experimental results from the free response of Cu coupon were obtained to determine the damping characteristics of the Cu coupon in the welding process. Our analysis shows that substantial energy loss can occur during welding due to the flexural vibration of the Cu coupon, especially when the overhang (the upper part of the Cu coupon extended from the anvil) of the Cu coupon resonates at or close to the welding frequency (about 20 kHz), degrading the weld quality of battery tabs. This study contributes to understanding the fundamental dynamics of the Cu coupon during ultrasonic welding and its impact on weld quality.     

Measurement of tool internal temperatures in the tool–chip contact region by embedded micro thin film thermocouples

Sensors capable of providing fast and reliable feedback signals for monitoring and control of existing and emerging machining processes are an important research topic, that has quickly gained academic and industrial interest in recent years. Generally, high-precision machining processes are very sensitive to variation in local machining conditions at the tool–workpiece interface and lack a thorough understanding of fundamental thermomechanical phenomena. Existing sensors to monitor the machining conditions are not suitable for robust in-process control as they are either destructively embedded and/or do not possess the necessary spatial and temporal resolution to monitor local tool internal temperatures during machining at the cutting tip/edge effectively. This paper presents a novel approach for assessing transient tool internal temperature fields in the close vicinity of less than 300 μm of the tool cutting edge. A revised array layout of 10 micro thin film micro thermocouples, fabricated using adapted semiconductor microfabrication methods, has been embedded into polycrystalline cubic boron nitride (PCBN) cutting inserts by means of a modified diffusion bonding technique. Scanning electron microscopy was used to examine material interactions at the bonding interface and to determine optimal bonding parameters. Sensor performance was statically and dynamically characterized. They show good linearity, sensitivity and very fast response time. Initial machining tests on aluminum alloys are described herein. The tests have been performed to demonstrate the functionality and reliability of tool embedded thin film sensors, and are part of a feasibility study with the ultimate goal of applying the instrumented insert in hard machining operations. The microsensor array was used for the acquisition of tool internal temperature profiles very close to the cutting tip. The influence of varying cutting parameters on transient tool internal temperature profiles was measured and discussed. With further study, the described instrumented cutting inserts could provide more valuable insight into the process physics and could improve various aspects of machining processes, e.g. reliability, tool life, and workpiece quality.     

Wireless acquisition of temperature data from embedded thin film sensors in cutting insert

This paper presents the results of wireless data acquisition experiments from embedded micro thin film sensors in cutting inserts for machining. A bluetooth module is used to acquire data and establish communication with a receiver PC over the serial port profile (SPP). A signal conditioning circuit is designed and developed to increase the signal-to-noise ratio of the embedded micro thin film sensors. Moreover, an averaging filter algorithm is implemented as a software interface. To characterize the wireless data acquisition (DAQ) system, laser heating and turning tests are conducted. Both tests show that the wireless DAQ system is able to provide desirable capabilities as well as the wired one for the embedded thin film sensors in cutting inserts.     

Arc welding induced residual stress in butt-joints of thin plates under constraints

The purpose of this work is to assess the effect of welding fixtures on distributions and values of residual stresses during Gas Tungsten Arc Welding (GTAW). The butt-joint GTAW of AA5251 plate is investigated using a transient thermo-mechanical analysis performed by the finite element program, ABAQUS. The model considers two different welding conditions including unconstrained and perfectly constrained conditions while macro examination and residual stress measurements by implementing hole drilling techniques are utilized to evaluate the predictions. The results show that the utilizing of a welding fixture alters the temperature field within the plate being welded and the depth of the weld pool decreases by about 21% in this case. In addition, the application of a welding fixture effectively changes both distributions and maximum values of transverse and longitudinal residual stresses.     

The effect of heating temperature of thin film transistor-liquid crystal display (TFT-LCD) optical waste glass as a partial substitute partial for clay in eco-brick

In order to fulfill the current WEEE directives, the traditional approach to manage thin film transistor-liquid crystal display (TFT-LCD) waste glass is inadequate. It is a serious opportunity to achieve resource conservation, reduction, stabilization and safety of management of TFT-LCD in the near future. To assist in achieving these goals, this study investigated the sintering characteristics and material properties of TFT-LCD waste glass, which can be pulverized and ground and subsequently blended with clay, at various substitution levels (0–40%) and finally fired from 800 °C to 1000 °C to make eco-brick. The brick thus produced was analyzed to determine variations in weight losses on ignition, 24-h absorption, bulk density, shrinkage, compressive strength and microstructure changes. The results for specific gravity, water adsorption, and compressive strength revealed that bricks made from mixtures containing TFT-LCD waste glass met the general requirements for bricks. The advantages of less water absorption, less weight loss on ignition, and a gain in compressive strength in the clay-TFT-LCD waste glass bricks should encourage the use of TFT-LCD waste glass as a brick additive.     

Numerical analysis of keyhole geometry and temperature profiles in plasma arc welding

In keyhole plasma arc welding (PAW), the formation of the keyhole involves complicated thermo-physical mechanism. The shape and dimensions of the keyhole directly determine the heat deposition along the thickness direction of the test plates, the penetration depth and the weld bead quality. Based on analysis of the forces acting on the weld pool, a keyhole model is established according to the force-balance condition on the keyhole wall. The shape and dimensions of quasi-steady state keyhole are numerically predicted. The keyhole shape and size are used to calibrate some distribution parameters of the combined volumetric heat source which takes into consideration the geometrical feature of welds with larger ratio of penetration depth to width and volumetric distribution characteristic of the plasma heat intensity along the plate thickness direction. The temperature fields on stainless steel plates are numerically simulated. The calculated fusion line at the transverse cross-section of PAW welds are compared with the experimental measurements. It is found that the predicted results are in agreement with the experimental data.     

Determination of in situ metal partitioning between particulate matter and ground water

This research was supported by a grant from the National Council for Research and Development, Israel, and the KFK, Karlsruhe, Germany.     

Recent advances in thin film composites membranes for brackish groundwater treatment with critical focus on Saskatchewan water sources

Drinking water scarcity is an ever-increasing global concern. This issue appears as a greater threat to the countries with no access to sea water resources or rivers, since their potential water resources are only limited to ground waters only. There are serious concerns with the treatment of ground water resources, including landfill leachates, agricultural contaminations (pesticides, herbicides, and fertilizers), and rural contaminations. Membrane separation has been proved to be the governing technology in water and wastewater treatment plants, as these methods are responsible for more than half of the market share of the world's desalination capacity. This study intends to offer a holistic view of the groundwater contamination with specific focus on Saskatchewan province in Canada, and the recent efforts in the groundwater treatment using thin film composite membrane technology. This study begins with an introduction of the general aspects of ground water and membrane separation, polluting agents, and their sources. It is followed by a discussion of Saskatchewan's groundwater status and various issues. Furthermore, the recent research that became available since 2010 is reviewed in details and the results are summarized with respect to purification efficiency. Different affecting parameters in a groundwater-thin film composite system are synthesized and an in-depth overview is presented.     

以梭鱼金属硫蛋白基因表达监测海洋重金属污染

分离了梭鱼金属硫蛋白132个碱基对应44个氨基酸的部分基因序列,以此为基础建立了分析梭鱼金属硫蛋白基因表达的实时定量PCR方法,并用于分析渤海南戴河和大神堂近岸海域野生梭鱼金属硫蛋白基因的表达.结果表明,南戴河野生梭鱼金属硫蛋白基因的表达水平(雄鱼:0.012 ± 0.0064 copies/copy β-actin;雌鱼:0.0099 ± 0.0042 copies/copy β-actin)明显高于大神堂野生梭鱼的表达水平(雄鱼:0.0017± 0.0011 copies/copy β-actin;雌鱼:0.0014 ± 0.00095 copies/copy β-actin).该结果与两地野生梭鱼体内重金属残留水平相一致,提示梭鱼金属硫蛋白基因可作为监测海洋重金属污染的敏感标志物之一.     

用多光路在线监测烟气中烟尘排放量的研究

提出一种基于Lambert-Beer定律,用激光作光源,经多光路在线监测烟气中烟尘(颗粒物)浓度分布,统计浓度平均值求得烟尘排放量的方法.论证了该方法在理论上的正确性和在 实践上的可行性.可将该方法应用于一般情况下气固二相流有关参数的在线测量.     

温敏性线型共聚物对金属离子的吸附

利用合成的ＮＩＰＡＡｍ－ＡＡｃ温敏性线型共聚研究了其对无机金属离子的吸附性能，以期应用于水污染的治理，结果表明其有明显的浓度效果，在ＰＨ＝４时，对Ｙ＾３＋，Ｅｒ＾３＋和ＵＯ＾２＋２的浓集率分别达到８４％、６５％和５６％，相应的浓集量分别为１１．２ｍｇ．ｇ＾－１，４．４５ｍｇ．ｇ＾－１和１１．３ｍｇ．ｇ＾－１，并讨论了影响浓集的条件和吸附机理。     

新乡市某电池厂附近污灌农田重金属污染特征与分类管理

在河南省新乡市某电池厂东南污灌农田区不同距离处挖掘土壤剖面6个,高密度采集剖面样品,并在污灌农田区和电池厂西部不同距离处采集表层混合样12个,共获得土壤样品238份,同时在污灌农田区采集粮食样品13份.用ICP-MS法测定Cd、Ni、Pb、Cr、Cu和Zn含量,AFS法测定Hg和As含量,并对土壤重金属的垂直迁移、污染状况、来源及污染农田的分类管理进行了探讨.结果表明：污灌农田耕层Cd平均含量均高于其风险管制值（GB 15618-2018）,其他重金属几乎全部低于筛选值.Cd是最主要的致污因子,其他重金属对土壤污染的贡献可以忽略.耕层Cd、Ni和As含量随着距电池厂距离的增加呈递减趋势.大多数剖面中Cd、Ni、Cr、Cu、Zn和As含量呈现不同程度的表聚性,Pb含量自上而下逐渐递减,Hg含量上下基本一致.污灌农田Cd、Ni和As主要来自污灌,同时受电池厂的干湿沉降影响,是工业源重金属;Cu、Zn、Cr和Pb属于农业源重金属;Hg是自然和人为混合源重金属.根据土壤环境质量类别及农产品质量综合确定距离电池厂大约3.5 km以内的污灌农田属于严格管控类农用地,应尽快禁止食用农产品的种植,代之以苗圃、林地.     

利用微型后生动物进行污泥原位减量的试验研究

在A/A/O普通活性污泥工艺中引入非寡毛类微型后生动物考察其生长条件和对剩余污泥的减量效果及对系统处理效果的影响。结果表明,当进水负荷小于0.5 mg(/mg MLSS·d)时,非寡毛类微型后生动物可大量生长;当内回流比升高、外回流比降低时,更有利于虫体的繁殖。经过适时的运行工艺调整可使生化系统虫体密度和稳定性提高,污泥减量效果可达到40%以上。非寡毛类后生动物的活动与摄食作用提高了系统污泥的沉降性能,并对系统出水COD、NH3-N、TN、TP、SS没有影响。。     

Investigation of the common intermediates over Fe-ZSM-5 in NH3-SCR reaction at low temperature by in situ DRIFTS

The surface species formed in the reaction of NO and NO₂ with pre-adsorbed NH₃ over a FeZSM-5 catalyst(1.27 wt.% Fe, SiO₂/Al₂O₃ = 25) at low temperature(140 °C) were studied by in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS). Through using a background spectrum of NH 3-saturated Fe-ZSM-5, we clearly observed the formation of common intermediates resulting from the reaction of NO₂ or NO + O₂ w...     

基于PM2.5站点监测数据的京津冀AOD补值研究

以京津冀2020年318个地面监测站点的PM_2.5数据为估算因子,构建了时空线性混合效应模型(STLME)和时空嵌套线性混合效应模型(STNLME),为AOD数据的补值研究提供了一种新方法.结果表明:在有AOD-PM_2.5匹配数据的日期,上述两个模型估算精度相近,交叉验证后决定系数R²分别为0.868和0.874,均方根误差RMSE分别为0.112和0.109;在无AOD-PM_2.5匹配数据的日期,嵌套模型估算精度明显高于非嵌套模型,交叉验证后决定系数R²分别为0.63和0.26.经过模型补值后,研究区监测站点所在网格AOD数据空间维有效比率从原始数据的44.35%提高到99.35%,时间维有效比率从87.94%提高到100%;同时,每个站点的年均AOD值都有明显提高,弥补了高PM_2.5浓度条件下缺失的AOD数据,可以减少空气污染和健康研究中暴露评估的偏差.     

营养盐现场采样和实验室分析的质量控制

介绍了营养盐现场采样和实验室分析中的质量控制方法和手段,依据近两年质控数据结果,分析了选用的质量控制方法与所进行监测工作类型和工作量相适应的程度.     

In situ hybridization studies for the detection of common aneuploidies in CVS

We have attempted to evaluate the efficiency of interphase cytogenetics in the detection of specific aneuploidies in chorionic villus samples. For this purpose, we used alphoid repetitive sequences specific for the chromosomes involved in the common aneuploidies, namely probes for chromosomes 13, 18, 21, X, and Y. These probes were applied to normal and abnormal CVS cases, as well as to a few mosaic cases. Results from these preliminary studies indicate that the technique can be very efficient for the detection of specific aneuploidies and can be particularly useful in the analysis of mosaic cases, which usually requires the screening of high number of metaphases.     

基于柔性SERS基底的快速原位检测环境污染物的方法

采用自组装方法,在新生的聚甲基丙烯酸甲酯(PMMA)薄膜上形成有序的纳米金粒子(AuNPs)层结构,制备AuNPs/PMMA薄膜.因PMMA支撑层具有柔韧性和透光性的特点,可直接将AuNPs/PMMA薄膜置于被检测物表面,通过表面增强拉曼散射技术实现物体表面污染物的快速原位检测.相比于其它检测方法,该方法快速、简单、成本低,在环境监测、食品安全及医疗卫生等领域有着极为广泛的应用前景.     

无机-有机混合改良剂对酸性重金属复合污染土壤的修复效应

本研究首先通过土壤培养实验,研究了在"石灰+沸石"的基础上,配施不同无机磷、不同有机物对酸性重金属复合污染土壤的改良效果,从中筛选4个最佳改良剂配方,并设置两种改良剂浓度梯度,以空心菜为供试植物进行盆栽实验.土壤培养实验显示,在施加"石灰+沸石"的基础上,配施有机肥或(和)无机磷能够进一步提高土壤pH,降低土壤重金属Cd、Pb、Cu、Zn的有效态含量;蘑菇渣和猪粪对土壤中4种重金属的固化效果优于鸡粪,钙镁磷肥的效果优于羟基磷灰石和磷矿粉.盆栽实验发现,8种处理均显著增加了土壤pH和降低了Cd、Pb、Cu、Zn的有效态含量,其中,处理H1、H2、H4(即在4 g·kg~(-1)沸石+2 g·kg~(-1)石灰石+3 g·kg~(-1)钙镁磷肥(磷矿粉)基础上,配施4 g·kg~(-1)有机物(猪粪或蘑菇渣))改良土壤后,空心菜生长健康,其地上部Cd、Pb、Cu、Zn含量均可达到食品卫生标准.比较土壤中重金属的化学形态,改良剂可能通过增加土壤pH及与重金属发生沉吸、附淀、络合等一系列反应,促进重金属由可交换态向铁锰氧化物结合态转换,从而显著降低了土壤重金属的生物有效性和减少空心菜对重金属的吸收.