化学分离法分析大型纸浆发电厂废渣中生物质底灰和飞灰成分(英文)

采用三步分离法,其中第一步用水,第二步用乙酸铵,第三步用盐酸,提取纸浆发电厂生物质飞灰和底灰的组分,以评估这些残渣的浸出行为。除了Mo、S、Na以及那些浓度低于检测范围的元素外,在这两种灰份中,对于其他元素这三种浸出剂的浸出能力从弱到强的顺序为:水、乙酸铵和盐酸。采用三步分离法处理的废渣中元素浓度比前期用BCR连续提取法得到的低。     

Physicochemical characterization of sweet potato starches popularly used in Chinese starch industry

Physicochemical properties of starches isolated from 11 sweet potato cultivars popularly used in Chinese starch industry were studied. Moisture, protein, ash, lipid and phosphorus content of the starches varied from 3.86 to 6.52%, 0.28 to 0.75%, 0.10 to 0.47% and 0.00 to 0.02%, respectively. Amylose content varied between 13.33 and 26.83%. The starches differed in their mean granule sizes, particle size distribution, and susceptibility to pancreatin hydrolysis. Swelling power and solubility ranged from 13.46 to 26.13 g/g and 8.56 to 18.77%, respectively. Higher retrogradation tendency was observed in pastes of starches of high amylose content. Gelatinization temperature and enthalpy ranged from 55.54 to 69.11 °C and 6.40 to 11.89 J/g, respectively. Pasting properties including peak viscosity (134–255 BU), breakdown viscosity (91–162 BU), setback viscosity (26–112 BU), peak time (5.97–7.03 min) and pasting temperature (67.20–73.00 °C) varied significantly among the sweet potato starches. Pearson's correlation analysis showed that phosphorus content of the starches had substantial effect on their swelling power (r = 0.70, p ≤ 0.05) showing positive correlations. There was significant positive correlation between swelling power and solubility of the starches (r = 0.64, p ≤ 0.05). Thermal and pasting parameters also showed significant correlations.     

环氧树脂基覆铜板耐热老化性研究

利用Arrhenius方程的老化动力学模型研究了环氧树脂基覆铜板的耐热老化性能。研究结果表明,固化体系、阻燃体系以及主体环氧树脂的结构直接影响覆铜板的耐老化性能。酚醛树脂固化体系覆铜板的耐热老化性优于双氰胺固化体系,磷系阻燃的覆铜板耐热老化性优于溴系阻燃体系,配方中添加具有刚性结构的环氧树脂有利于提高覆铜板的耐热老化性。     

Effects of the Encapsulating Resin on the Junction Temperature of the QFN16 and QFN32 Electronic Packages Subjected to Free Convection

The junction temperature of the quad flat no-lead with 16 and 32 leads (QFN16 and QFN32) electronic packages subjected to free convection is highly affected by their encapsulating resin's thermal conductivity. This study considers a variation of this conductivity between ?80% and +100% of the average value measured on an industrial prototype by means of the Transient Plane Source method. The three dimensional numerical solution based on the control volume formulation shows that the thermal trend is of exponential type for these components but with different functions. The proposed relationships allow the calculation of the junction temperature of both QFN16 and QFN32 according to the power generated varying between 0.1 and 1W, and the inclinations relative to the horizontal plane in the range 0–90° (horizontal and vertical positions respectively). The law governing the influence of conductivity on the junction temperature shows that a more conductive resin does not significantly lower the junction temperature. However, for low conductivity values, the temperature can exceed the maximum recommended by the manufacturers, causing possible malfunction of the QFN and altering its technical performance that are directly related to its thermal state. In some cases, the device can be decommissioned.     

Automatic Multiscale Approach for Water Networks Partitioning into Dynamic District Metered Areas

Water distribution systems (WDSs) today are expected to continuously provide clean water while meeting users demand, and pressure requirements. To accomplish these targets is not an easy task due to extreme weather events, operative accidents and intentional attacks; as well as the progressive deterioration of the WDS assets. Therefore, water utilities should be ready to deal with a range of disruption scenarios such as abrupt variations on the water demand e.g. caused by pipe bursts or topological changes in the water network. This paper presents a novel methodology to automatically split a WDS into self-adapting district metered areas (DMAs) of different size in response to such scenarios. Complex Networks Theory is proposed for creating novel multiscale network layouts for a WDS. This makes it possible to automatically define the dynamic partitioning of WDSs to support further DMA aggregation / disaggregation operations. A real, already partitioned, water utility network shows the usefulness of an adaptive partitioning when the network is affected by an abnormal increase of the peak demand of up to 15%. The dynamic DMA reuses the assets of the static partitioning and, in this case, up to the 82% of resilience is restored using 94% of the assets already installed. The results also show that the overall computational and economic management costs are reduced compared to the static DMA partition while the hydraulic performance of the WDS is simultaneously preserved.

     

Teaching Construction Contracts: Mutual Learning Experience

Construction contract modules are delivered to second-year architectural technology and construction/construction management students undertaking foundation and undergraduate degree programs. Feedback and assessment results from recent years showed that students generally found these modules difficult. Studies were conducted to further understand students’ experiences and expectations, to assess quality of teaching, and to evaluate the dissemination of theoretical and practical knowledge during the delivery of construction contract modules. The objective was to review the methods used for teaching, learning, and assessment of construction contract modules and make recommendations to inform and improve future module development and delivery. This paper is based on a first-time experience of teaching a law-related subject to construction students. Reflection on the teaching and assessment methods implemented during the term and on student responses permits conclusions to be drawn on how best to improve students’ learning experience and simultaneously maintain the university’s quality standards.