Process Intensification of Living Cationic Polymerization of Isobutylene by a Flow Reaction System

Increasing the reaction temperature of the living cationic polymerization of isobutylene is crucial for industrial production due to the cost of refrigeration. The reaction temperature increase was achieved with an accelerated reaction rate using a flow reaction system. The polymerization conditions, including the flow reactor design, were based on the results of kinetic studies. Utilizing a milli‐scale flow reactor, polyisobutylene, which has a narrow molecular weight distribution, was obtained within a considerably short residence time at a high temperature. Furthermore, it was confirmed that the value of M_w/M_n correlates with the product of the Reynolds number and the angle of collision.     

Thermodynamic performance analysis and environmental impact assessment of an integrated system for hydrogen and ammonia generation

A novel multigeneration plant that's using natural gas for power, hydrogen, ammonia, and hot water generation, is planned and analyzed, in the current paper. The suggested combined plant integrated with four sub-systems, which are the Brayton cycle, reheat Rankine cycle, the high-temperature steam electrolyzer for hydrogen production, and ammonia synthesis processes. Also, thermodynamic analysis and environmental impact assessment are conducted for the designed plant and sub-systems. Moreover, the sustainability index analysis of this proposed study is conducted. The effects of some important indicators on the performance and on the environmental impact of the modeled system and sub-processes are also studied. According to analyses results, it is noted that the energetic and exergetic efficiencies of the suggested system are 51.83% and 70.27%, respectively, and also the total CO₂ emission rate is 11.4 kg/kWh for the integrated plant. Furthermore, the total irreversibility rate is computed as 40007.68 kW, and furthermore, the combustion chamber has a maximum irreversibility rate with 20,033 kW, among the proposed plant components.     

基于儿童使用主体的建成环境评价尺度研究

评价尺度是建筑使用后评价的基 本问题之一，它是使用者评判建成环境好 坏、优劣的重要测度标准。为弥补目前环境 评价尺度研究方面的缺失，建立与儿童使用 主体相一致的建成环境评价尺度，对儿童常 用语义量词进行汇总和筛选，采用五级线 分刻度方法进行问卷调查研究。基于儿童的 理解，通过问卷试验分析，结果表明：双侧 5级区间评价尺度为：很（负面）；有点（负 面）；中等；有点（正面）；很（正面）；单侧 5级区间评价尺度为：不；好像有点；比较； 很；特别。     

Effect of preparation method on physicochemical properties and catalytic performances of LaCoO_3 perovskite for CO oxidation

Perovskite oxides LaCoO_3 prepared by templating, co-precipitation and sol-gel method with different complexants were systematically characterized and its catalytic performances for CO oxidation were investigated. The samples were characterized by X-ray diffraction, thermogravimetry analysis and differential scanning calorimetry, N_2 physisorption, transmission electron microscopy, temperature program reduction of hydrogen, temperature program desorption of oxygen and X-ray photoelectron spectroscopy measurement, results of which show that the properties of LaCoO_3, such as surface morphology, surface area, surface compositions, redox capability, oxygen vacancy, as well as the calcination temperature and formation mechanism, depend intimately on the preparation method. Catalytic tests indicate that the sample prepared by carbon templating method shows the best activity for CO oxidation, with full CO conversion obtained at 135 ℃. In particular, the catalyst can be activated and significant increase of activity can be obtained with the increase of reaction time. The cyclic and longterm stability of catalysts were discussed and compared.     

An agile model for the eco-design of electric vehicle Li-ion batteries

Numerous design choices need to be made at several levels when designing high-tech products: technology, processes, architecture, components, materials… and these choices need to be made in relation to the product life cycle with the corresponding experts for each stage of the life cycle. At the same time, to ensure product sustainability, a specific focus on the future potential environmental impacts is highly recommended. In this research, an agile model is proposed to help designers make decisions while monitoring environmental performance indicators of high-tech solutions. The concept of Critical Product Life Cycle Parameters had to be introduced to facilitate the eco-design of the final product. The approach is illustrated by the Electric Vehicle Li-Ion Batteries case study.     

Variation-aware approaches with power improvement in digital circuits

In submicron technology, during the fabrication process factors like lithography and lens defect can change some of the physical parameters of transistors and interconnects. This change can modify the transistor electrical characteristics such as current, threshold voltage and gate capacitance, and thus it causes variation in power, delay and performance of the circuit. Process variation has become one of designer׳s challenges to the point that in below 45 nm technology it is considered as the most important issue in reliability. Power consumption and transistors variation are limiting factors to physical scalability. In this paper, we propose two approaches to reduce D2D and WID variations effects on digital CMOS circuits, at design time. The first approach concerns a variation-aware algorithm capable of extracting optimal design parameters to decrease variation and power. The second approach, using transistor stacking will help further reduce variation and power. Applying the algorithm on a digital design and according to parameters behavior in the presence of variation, we extract for each parameter value that will lead to power and variation reduction. On the other hand, with the stacking approach only basic gates are considered and subsequently gate configurations that reduce power and variation are proposed. The proposed approaches could be used identically for synchronous and asynchronous circuits. To prove this claim, we apply our approaches to a network-on-chip asynchronous router and a circuit from the ISCAS85 benchmark. All simulations are done in 32 nm technology using the HSPICE tool. The proposed algorithm similar to Monte Carlo simulation achieves the same results; however with lower execution time. The application of stacking approach to both asynchronous router and ISCAS85 circuit reduces variation effects up to 40.9% and 13.35%, respectively.     

A methodological approach for manufacturers to enhance value-in-use of service-based offerings considering three dimensions of sustainability

To shift towards a sustainable society, lifecycle engineering methodologies addressing the social dimension need to be advanced. A new methodological approach is proposed for manufacturers to address the three dimensions of sustainability. This approach aims to enhance value-in-use of service-based offerings and supports designers with two social indicators and five generally applicable recommendations involving multiple product lives towards a circular economy. For validation, it was applied to the case of a manufacturer of washing machines for European consumer markets. Results show that the approach supports designers to incorporate the social dimension efficiently while improving resource efficiency.     

Biodegradability Study of the Biosurfactant Contained in a Crude Extract from Corn Steep Water

Over the last few years, the global biosurfactant market has raised due to the increasing awareness among consumers, for the use of biological or bio-based products. Because of their composition, it can be speculated that these are more biocompatible and more biodegradable than their chemical homologous. However, at the moment, no studies exist in the literature about the biodegradability of biosurfactants. In this work, a biosurfactant contained in a crude extract, obtained from a corn wet-milling industry stream that ferments spontaneously in the presence of lactic acid bacteria, was subjected to a biodegradation study, without addition of external microbial biomass, under different conditions of temperature (5–45 °C), biodegradation time (15–55 days), and pH (5–7). For that, a Box–Behnken factorial design was applied, which allowed to predict the percentage of biodegradation for the biosurfactant contained in the crude extract, between the range of the independent variables selected in the study, obtaining biodegradation values between 3 and 80%. The percentage of biodegradation for the biosurfactant was calculated based on the increase in the surface tension of samples of the crude extract. Furthermore, it was also possible to predict the variation in t_1/2 for the biosurfactant (time to achieve the 50% of biodegradation) under different conditions.     

高速铁路绝缘块耐环境能力的研究

铁路扣件系统是将钢轨固定在轨枕上,阻止钢轨相对于轨枕发生横纵向移动,保持轨距,在高速铁路运行过程中起到缓冲减震作用的系统。经过长期使用及列车的运行,有些尼龙产品扣件存在不同程度的损坏,产生松动现象,进而影响铁路运行安全。以扣件系统中的绝缘轨距块为研究对象,从环境及气候等多种因素研究其对轨距块性能的影响,找寻较为关键的影响因素。研究结果发现,室外环境放置的轨距块极限剪切性能下降更明显,耐冲击性更差。经过研究不同恶劣环境下轨距块性能的变化,发现高温高湿及高温环境下产品性能下降幅度较大,其中高温高湿影响最大。     

Living labs as an opportunity for experiential learning in building engineering education

Building performance – spanning energy use, greenhouse gas emissions, indoor environmental quality, etc. – is fundamental to the field of building engineering, yet it is typically taught with idealistic assumptions and traditional, teacher-centred, lecture-based methods. A promising emerging approach for university-level building engineering education is experiential learning, whereby students actively engage in complex tasks with real building data that reflect the kinds of problems graduates are likely to encounter in the workplace. To bridge the academic and employability skills and knowledge that they are developing through these tasks, students participate in reflective activities that help them to articulate the relevance and implications of the experience for lifelong learning. The objective of this paper is to assess the teaching and learning effectiveness of a data- and information-centric experiential learning approach to university-level engineering education. This paper reflects upon a particular course-based initiative informed by experiential learning theory that engaged fourth-year students in the life cycle of a new building on a university campus that was equipped with state-of-the-art building controls technologies. Students were provided access to a living lab resource with diverse artefacts from the building: drawings and building information models, guest lectures and technical tours, and live/historic data for the building. A series of assignments provided students with simulated problem scenarios to solve through the application of the building data as well as reflection prompts about their problem-solving process. The present paper details the assignments and the nature of the living lab data, students’ assignment results, and students and teaching assistants’ feedback on the overall teaching approach. The findings indicate a significant and continuous improvement in the reception and perceived educational value of the experiential assignments over the four-month term, suggesting living labs are a promising source of educational material for experiential learning. The paper concludes with lessons learned from the current course about experiential learning in building engineering education that can be applied more broadly to future courses in the field.