中低浓度印染废水处理工程实例

根据印染废水的特点,采用"预处理+混凝沉淀+生物接触氧化+生物滤塔"的方法进行处理。运行结果表明,在进水COD、BOD5、SS的质量浓度分别为480、200、300 mg/L,色度为300倍的情况下,这些指标的去除率分别为86%、91%、83%和85%。出水均优于污水综合排放标准(GB8978-1996)中的一级排放标准,系统处理废水的运行费用为0.734元/m3。     

Subtle gate oxide defect elimination to improve the reliability of a 32M-bit SRAM product

Tiny defects may escape from in-line defect scan and pass WAT (Wafer Acceptance Test), CP (Chip Probing), FT (Final Test) and SLT (System Level Test). Chips with such kind of defects will cause reliability problem and impact revenue significantly. It is important to catch the defects and derive the prevention strategy earlier in the technology development stage. In this paper, we investigate an SRAM with tiny defects which passed in-line defect scan, WAT, CP and FT but failed in HTOL (High Temperature Operation Life) test, one of the product reliability qualification items. FA (Failure Analysis) reveals gate oxide missing defect is the root cause. The goal is to pass reliability qualification and release product into production on schedule. The failure mechanism, optimization of gate oxide process, enhancement of defect scan and testing methodology will be introduced. Experiment results show very good HTOL performance by the combination of process and testing optimization.     

The importance of grain boundary complexions in affecting physical properties of polycrystals

In recent decades researchers have revealed a rich variety of grain boundary segregation phenomena, including interfacial phase, or complexion, transitions. Grain boundary complexion transitions have been shown to induce discontinuous changes in materials properties as a function of temperature and chemical potential, and have been used to explain phenomena that had previously evaded satisfactory explanation. This review article discusses how grain boundary complexions relate to mass transport and mechanical properties, by highlighting both what is understood and emphasizing topics requiring additional study.     

Delineating the dimensions of social support on social networking sites and their effects: A comparative model

Social networking sites (SNSs) allow users to connect with each other by overcoming geographical and temporal boundaries and thus empower people to search for social support from online. Social support has been considered a key social value that online users can obtain from SNSs. However, few studies have systematically investigated social support in such a context. Motivated to address this gap, we have developed an advanced and theoretical framework to delineate social support on SNSs by clearly revealing the dimensions of online social support on SNSs and examining their effects on users' commitment and SNS continuance. Further, we introduce gender as a key moderator and explain in theory how differently men and women perceive the importance of the dimensions in evaluating online social support over SNSs. Our research results indicate that the identified three dimensions (informational support, emotional support, and network management) are important components of the online social support on SNSs, which is positively associated with commitment and continuance. In addition, the weight of each dimension in the evaluation of online social support varies by gender. This study is among the very first to explore online social support in the context of SNS and its effects, and has rich theoretical and practical implications.     

A cloud-based learning environment for developing student reflection abilities

Students learn new knowledge effectively through relevant reflection. Reflection affects how students interact with learning materials. Studies have found that good reflection abilities allow students to attain better learning motivation, comprehension, and performance. Thus, it is important to help students develop and strengthen their reflection abilities as this can enable them to engage learning materials in a meaningful manner. Face-to-face dialectical conversations are often used by instructors to facilitate student reflection. However, such conventional reflection methods are usually only usable in classroom environments, and could not be adopted for distance learning or after class. Cloud computing could be used to solve this issue. Instructor guidance and prompting for initiating reflection could be seamlessly delivered to the students’ digital devices via cloud services. Thus, instructors would be able to facilitate student reflective activities even when outside the classroom. To achieve this objective, this study proposed a cloud-based reflective learning environment to assist instructors and students in developing and strengthening reflection ability during and after actual class sessions. An additional experiment was conducted to evaluate the effectiveness of the proposed approach in an industrial course. Results show that the learning environment developed by this study is able to effectively facilitate student reflection abilities and enhance their learning motivation.     

基于总体统筹控制计划的工程项目管理研究

以中国石化大型项目为例,阐述了总体统筹控制计划编制的意义、方法、内容以及在项目实践中执行的方法和取得的成果,从而证明编制总体统筹控制计划是一种科学的项目管理方法,应该得到推广运用。     

GSA算法在管壁余氯衰减系数校正中的应用

为了提高余氯浓度的计算精度,拟采用GSA算法对余氯衰减模型中的管壁余氯衰减系数进行校正。结合某管网仿真控制系统提供的样本数据进行仿真计算,余氯浓度计算值比较接近实测值,结果表明:GSA算法在管壁余氯衰减系数校正中具有良好的工程应用价值。     

Optimizing the thermal effectiveness of an insulation wrap with internal folded polypropylene film for the transportation of frozen food

The paper presents an investigation of the thermal performance of an innovative insulation wrap for food freezing, transportation and storage. The wrap is made of two outer polypropylene films and an internal folded polypropylene film welded together to form rectangular internal air cells. A mathematical model of heat transfer is presented and experimentally validated, with discrepancies less than 10% when there is no internal convection effect and generally less than 12% when internal convection is present. A thermal effectiveness of film usage was proposed and analyzed in order to find the best fold geometry. A mathematical model of the effectiveness and its experimental validation showed good agreement (discrepancies less than 13%). By using a criteria map, we recommend the following geometry: wrap thickness more than 5 and less than 10 mm; fold spacing more than 6 and less than 10 mm.     

A decoupled inversion-based iterative control approach to multi-axis precision positioning: 3D nanopositioning example

System inversion provides a nature avenue to utilize the priori knowledge of system dynamics in iterative learning control, resulting in rapid convergence and exact tracking (for nonminimum-phase systems). The benefits of system inversion, however, are not fully exploited in the time-domain ILC approach due to the lack of uncertainty quantification. This critical limit was alleviated in the frequency-domain formulated inversion-based iterative control (IIC) techniques. The existing IIC techniques, however, are for single-input–single-output (SISO) systems only, and the time-domain properties of the IIC techniques are unclear. The contributions of the proposed multi-axis inversion-based iterative control (MAIIC) approach are twofold: First, the IIC technique is extended from SISO systems to multi-input–multi-output systems and is easy to implement in practice. The iterative control law is optimized by using the quantification of the system uncertainty. Secondly, the time-domain properties of the MAIIC law are discussed. The proposed MAIIC technique is illustrated through 3D nanopositioning experiments using piezoelectric actuators. The experimental results clearly demonstrated that by using the proposed technique, precision tracking in all 3D axes can be achieved in the presence of a pronounced cross-axis dynamics coupling effect.     

Metallic glass–steel composite with improved compressive plasticity

A Zr_52.5Cu₁₈Ni_14.5Al₁₀Ti₅ bulk metallic glass toughened with a commercially available spring-shaped steel wire has been produced by centrifugal casting. The addition of the steel spring significantly affects shear band nucleation and propagation through the blockage, deflection and multiplication of shear bands at the glass–spring interface. As a result of the more homogeneous distribution of the plastic strain, the room temperature plasticity increases from 0.9% for the monolitic glass to about 4% for the glass–spring composite. Given the low volume fraction of the spring used in the composite (4.2 vol.%), these results demonstrate the extreme effectiveness of the steel spring for improving the plasticity of the metallic glass.