总体规划或是一种控制方法？——蒙特利尔城市地下空间开发案例

我们会经常提到利用地下空间的优点,以及除公共设施以外地下空间作为其他用途时的不便,甚至是地下空间的隧道施工方法。但遗憾的是,我们很少提到地下空间的规划,也几乎从来没提到过地下空间开发的制度措施。除了蒙特利尔,也许只有日本使用规章制度对地下空间用途逐层地实行管理。最近,上海编制了第一个关于地下空间的规章,成为中国首个采取类似措施的城市。新的规章第一次明确了地下空间的定义,并且对土地审批和所有权注册等事项进行了说明。上海决定给城市所有区域的地下空间编制一个总体规划,成为中国在该领域的先行者．     

A classification of methods for efficient power amplification of signals

This paper presents a classification of methods that have been proposed to address nonlinear power amplification of highly fluctuating signals in telecommunications. The classification proposed uses a tree-like representation wherein each branch refers to a group of methods that all have a common characteristic. By virtue of this representation, each node corresponds to a test used to discriminate between different methods. From top to bottom, these tests are “What is the target of the method?,” Is the method downward-compatible?,” “Is the bit error rate degraded?,” “Is there a useful data rate loss?,” and “Does the method require changes in the amplification function?” By collating all these requirements, an original classification is proposed that is open enough to allow new methods to be added. It only concerns methods located either only at the transmitter or at both transmitter and receiver. The context of this study generally concerns multicarrier signals (especially orthogonal frequency division modulation) but can be applied to any multiplex of modulated signals.     

Review: degradation-induced embrittlement in semi-crystalline polymers having their amorphous phase in rubbery state

The literature dealing with degradation-induced embrittlement mechanisms in semi-crystalline polymers having their amorphous phase in rubbery state is reviewed. It is first demonstrated that the decrease of molar mass resulting from a quasi-homogeneous chain scission process is responsible for embrittlement. The main specificity of the polymer family under study is that embrittlement occurs at a very low conversion of the degradation process, while the entanglement network in the amorphous phase is slightly damaged. In these polymers, chain scission induces chemicrystallization. The analyses of available data on this process show that it is characterized by a relatively high yield: about one half entanglement strands integrate the crystalline phase after one chain scission. A simple relationship expressing the chemicrystallization yield for a given polymer structure is proposed. Chain scission and chemicrystallization can lead to embrittlement through two possible causal chains: (1) chain scission → molar mass decrease → chemicrystallization → decrease of the interlamellar spacing → embrittlement. (2) Chain scission → molar mass decrease → chemicrystallization → decrease of the tie-macromolecule concentration → embrittlement. At this state of our knowledge, both causal chains are almost undistinguishable.     

Understanding pregnant women's decision making concerning prenatal screening.

Objective: This study is aimed at enhancing understanding prenatal screening decision making through testing a hypothesized decision model based on decision theory and health behavior theory. Design: We obtained questionnaires from 1,666 pregnant women who were offered prenatal screening for Down's syndrome. Path analysis (using LISREL) resulted in a final model with reasonable model fit, which was verified by split-sample cross-validation. Main outcome measures: These included perceived probability, perceived severity, attitude toward termination, response efficacy, attitude toward prenatal screening, subjective norm, child-related anxiety, and intention to undergo prenatal screening. Results: Attitude toward termination of pregnancy, perceived test efficacy, and subjective norm regarding the desirability of having prenatal screening determined a woman's attitude toward having a prenatal test. Anxiety was influenced by perceived risk and perceived severity of having a child with Down's syndrome, and by subjective norm, but this appeared to be a weak predictor of intention to test. Pregnant women with a positive attitude toward prenatal screening, and who perceived a subjective norm in favor of undergoing prenatal screening, showed a greater intention to have prenatal screening done. Conclusion: These findings suggest that more attention should be paid toward the values and social context of pregnant women during the counseling process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of band selection and target estimation error on the performance of the matched filter in hyperspectral imaging

The matched filter is a widely used detector in hyperspectral detection applications because of its simplicity and its efficiency in practical situations. We propose to estimate its performance with respect to the number of spectral bands. These spectral bands are selected thanks to a genetic algorithm in order to optimize the contrast between the target and the background in the detection plane. Our band selection method can be used to optimize not only the position but also the linewidth of the spectral bands. The optimized contrast always increases with the number of selected bands. However, in practical situations, the target spectral signature has to be estimated from the image. We show that in the presence of estimation error, the maximum number of bands may not always be the best choice in terms of detection performance.     

Improvement of cooking quality of maize pasta products by heat treatment

A new process has been developed to manufacture good pasta products from a blend of durum wheat semolina and maize flour (ratio 33: 66). It consists of submitting, to a high temperature (90 to 120°C) for 90 to 180 min, pasta previously processed and dried under the usual industrial conditions. Colour characteristics (yellowness, brownness and red index) are not affected when the treatment is kept below 100°C; at a higher temperature the red index increases sharply. There is a distinct improvement in cooking quality (cooking losses, surface condition) and this is inversely related to the water content of the pasta before treatment. The viscoelasticity of cooked pasta is dramatically modified when the temperature of treatment is 120°C.     

A simple method for electroanalytical determination of ceftiofur in UHT milk samples using square-wave voltammetry technique

A simple electroanalytical method was developed to determine the antibiotic ceftiofur (CF) in milk. The method is based on the adsorptive accumulation of the drug on a hanging mercury-drop electrode (HMDE) and the accompanying initiation of a negative square wave, which yielded well-defined cathodic peaks at −0.60 V (1C) and −0.91 V (2C) vs. Ag/AgCl. Calibration graphs were constructed and statistical parameters were evaluated. At pH 2.5, the square-wave voltammetry method revealed linearity from 52.4 to 524 ng mL⁻¹ (r = 0.997), which is in accordance with the tolerance level of 100 ng mL⁻¹ for CF as a residue in bovine milk established by the Food and Drug Administration (FDA) and the European Union. The limits of detection and quantification were 1.86 and 6.20 ng mL⁻¹, respectively. The method was tested to determine CF in spiked milk samples using HPLC as reference method.