Decomposing regional business change at plant level in Italy: A novel spatial shift‐share approach

In this paper, spatial shift‐share decomposition is analysed when applied to Italian data on regional business change at plant level, over the period 2004–2009. A new type of spatial decomposition, which looks more effectively at neighbourhood influence, is introduced here. Notable results emerge from the empirical investigation. First, it can be seen that the spatial level of aggregation greatly affects results. Second, evidence of neighbourhood advantage in the Southern NUTS 3 regions is found, together with opposite results for the Central‐Northern NUTS 3 regions. Finally, evidence of positive industrial mix effects is only found in Central‐Northern Italy.     

Substitution bias and the construction of a spatial cost of living index*

We estimate the spatial substitution bias based on the difference between a price index (PI) and the true cost of living (COL). This bias is computed at three geographical scales, using several fixed baskets and across different expenditures quartiles. Our results show a significant substitution bias for small geographical units. The choice of the base basket is also relevant for the bias estimation. Finally, the spatial substitution bias is larger for upper side of the expenditure distribution due to the heterogeneity in the consumption basket. This exercise shows that the spatial dimension affects the construction of a price index and that the approach of fixed baskets should be carefully considered in the estimation of spatial price differentials.     

Evaluation of performance of Active,Beautiful and Clean (ABC) on stormwater runoff management using MIKE URBAN: a case study in a residential estate in Singapore

ABSTRACT

Singapore has adopted a low impact development equivalent of stormwater management philosophy under a national program called ‘Active, Beautiful and Clean’ (ABC) employing soft-engineering techniques to manage rainfall runoff in the face of climate change and rapid urbanisation. This study makes use of the MIKE URBAN modelling tool to evaluate the performance of ABC units in a new residential precinct based on flow data collected. Calibration results show an overall good fit between the measured data and simulated results based on three goodness-of-fit stats. The runoff factors computed for scenarios with and without the presence of ABC units show an improvement in the range of 21–72%. This study demonstrates the usefulness of using a calibrated model to evaluate the performance of constructed units using measurements. It is recommended that this modelling tool be also used for evaluating water quality performance of the units as well as applying it for use in the planning and implementation process.     

LF21铝合金双轴肩搅拌摩擦焊组织与性能

利用光学显微镜、扫面电子显微镜、显微硬度仪、拉伸试验机等方法,分析6 mm厚LF21铝合金单道对接双轴肩搅拌摩擦焊焊焊缝的微观组织、力学性能、缺陷成因。实验结果表明,转速1 200 r/min、焊接速度100 mm/min时可以获得较好的焊接性能;焊缝组织呈不完全对称的沙漏状;焊缝硬度在焊缝两侧的热影响区处发生不对称的软化,前进侧组织析出相发生了明显的长大现象;抗拉强度达到103.25 MPa,焊接强度系数为基材强度的70.4%,接头断口形貌呈典型的韧性断裂。     

基于响应曲面法的钛合金TC21铣削参数优化

针对新型损伤容限型钛合金TC21的难加工性,通过基于响应曲面法的中心复合设计铣削试验研究工艺参数对切削力的影响规律,建立二阶响应曲面模型,以最小切削力为目标优化工艺参数。研究结果表明:轴向切深和每齿进给对切削力影响显著,径向切深和切削速度对切削力影响较小,最优加工参数为v_c=119.71m/min,f_z=0.06mm/z,a_e=0.87mm,a_p=16.01mm。将最优加工参数应用到工程实践中,可提高整体硬质合金刀具寿命和各类型零件的加工效率。     

21世纪前期我国煤炭科技重点发展领域探讨

分析了国内外煤炭科技发展的概况及趋势，提出了21世纪前期我国煤炭工业将向“高效、安全、洁净、结构优化”的方向发展，以及煤炭科技发展要解决的重大问题：① 煤炭资源（含煤层气）精细勘查与高效开采地质保障；② 东部深厚冲积层下建井综合技术与装备研究；③ 煤矿高效集约化开采技术与机电一体化装备研究；④ 以矿井瓦斯灾害综合防治技术为重点的煤矿安全新技术；⑤ 以“煤基液体燃料”和煤化工多联产为目标的新型煤转化技术；⑥矿区生态环境综合整治与废弃物处理利用技术.     

ITU-T误码性能建议之二

对于用于传送广播电视节目的国家和城域干线网，误码性能是一个关键的传输性能指标。本文介绍了ITU—T的几个主要的误码性能建议，希望能对干线网传输系统的建设和维护有所帮助。