示波极谱滴定法测定工业氯化钙主要成份

在氯化铵-氨水(pH=11)支持电解质中用微银汞膜电极进行试验,锰、铁不干扰测定,用EDTA滴定氯化钙获得令人满意的结果。对三种样品进行分析,变异系数为0.08％—0.11％。该法快速准确,适用于氯化钙主要成份的测定。     

Fast dynamic casting

We describe a scheme for implementing dynamic casts suitable for systems where the performance and predictability of performance is essential. A dynamic cast from a base class to a derived class in an object‐oriented language can be performed quickly by having the linker assign an integer type ID to each class. A simple integer arithmetic operation verifies whether the cast is legal at run time. The type ID scheme presented uses the modulo function to check that one class derives from another. A 64‐bit type ID is sufficient to handle class hierarchies of large size at least nine levels of derivation deep. We also discuss the pointer adjustments required for a C++ dynamic_cast. All examples will be drawn from the C++ language. Copyright © 2005 John Wiley & Sons, Ltd.     

Household energy consumption versus income and relative standard of living: A panel approach

Our fundamental premise is that energy consumption at the household level is a key indicator of standard of living. We employ state-of-the-art panel cointegration techniques to evaluate the nature of the relationship between income measures and energy consumption measures for seven East Indian Ocean countries. The general finding is that income and household electricity consumption are not cointegrated. Given this finding, we conclude that standard of living measures that rely on income measures and do not include household-level energy consumption information will necessarily miss important indications of both levels and changes of standard of living.     

镁法海绵钛生产工艺中大型无隔板镁电解槽的节能实践

以镁法海绵钛生产工艺中大型无隔板镁电解槽的实际节能情况为例，探讨了在镁电解生产中的非生产耗电、生产耗电、漏电等因素造成的能量浪费，阐述了生产中粗镁直流电耗、电流效率、工作电压3者之间的关系，指出了影响电解槽工作电压的有关因素及降低电解槽工作电压的途径。     

Isothermal Gas Forming of Mg Alloy AZ31 Sheet

There have been reports on sheet forming of Mg alloy in industry via the punch and die method;this paper is probably the first formal one for studying the sheet formability of AZ31 employing pressurized gas to press the sheet into a female die cavity at various elevated temperatures.The results indicate it is feasible to form a rectangular box via pressurized gas from extruded sheets of 0.5 and 1.7 mm thick.The formed box has 1:2 depth over width ratio,which should be large enough when dealing with realistic industrial sheet forming parts.Presently,forming a sheet of 0.5 mm thick is considered a technical challenge by industry,and it is conquered as demonstrated in this paper.Gas forming technique applied to Mg alloy is unprecedented and shows potential for industrial utilization.     

硅粉/酚醛制备低成本碳化硅陶瓷复合材料

以低成本的硅粉和酚醛为原料 ,采用浆料浸渍 热压成型 反应烧结法制备了Cf SiC单向板 ,并对工艺条件进行了探讨。制备得到的单向板的弯曲强度达到 45 6 .8MPa ,断裂韧性达到 7.94MPa·m1 2 。     

The radiation crosslinking and scission of ethylene-propylene copolymers studied by solid-state nuclear magnetic resonance

Methyl groups from chain scission and H-crosslinks have been identified by solid-state nuclear magnetic resonance in amorphous ethylene-propylene copolymers containing 23 and 36 mole % propylene after γ-irradiation to 10 MGy at 30°C. G (scission) and G (crosslink) values determined from the n.m.r. spectra and by extraction are in agreement, which suggests that the crosslinks are not clustered. This may differ from the situation in polyethylene where there is a substantial crystalline content. G(S). G(X) and the ratio G(S)/G(X) increase with increasing propylene content of the copolymers.     

Determination of instantaneous corrosion rates and runoff rates of copper from naturally patinated copper during continuous rain events

Instantaneous corrosion rates of naturally patinated copper of varying age (16 months, 138 and 145 years) have been determined during continuous rain events in the laboratory with electrochemical impedance spectroscopy using a two-electrode cell. The two-electrode cell was found to yield the same information in bulk rainwater as a conventional three-electrode cell.Relatively constant corrosion rates, between 0.2 and 0.6 μm/y, were determined for samples having a two-layer structure with an inner brownish layer of cuprous oxide and an outer greenish layer of basic copper salts (138, 145 years). Samples with cuprous oxide as the dominating phase of the patina (16 months) showed higher and somewhat increasing corrosion rates during a rain event (from 0.6 to 1.2 μm/y). During a continuous rain event, corrosion rates were found to be approximately 10 (brownish patina) and 25 times (greenish patina) lower than corresponding instantaneous runoff rates. The first flush phenomena of the runoff process, with an increased concentration during first flush and a relatively constant concentration during steady state, was indirectly seen as an increase in solution conductivity during the first rain volume followed by relative constant value. The contribution of the concentration in the first flush to the total annual runoff rate was significant for panels having a greenish layer (138, 145 years) whereas it was negligible for panels having a brownish layer (16 months).     

Preparation and characterization of organic-inorganic poly(ethylene glycol)/WS2 nanocomposite

Layered nanocomposite PEG/WS₂, intercalating oligomeric poly(ethylene glycol) (PEG6000) into the tungsten disulfide host galleries, was synthesized using the exfoliation-adsorption technique. X-ray diffraction revealed that the intercalated oligomer within the host galleries is in a double-layer arrangement with an interlayer expansion of about 8.8 Å. The optimum conditions were explored to prepare the single-phase product with a composition of Li_0.12(PEG)_1.51WS₂. Thermal analyses suggested that the resulting material shows good thermal stability, with the decomposition of the interacted oligomeric chains within the disulfide galleries occurring at around 258 °C. Despite high conductivity of the host material, those of the PEG/WS₂ nanocomposite were found to be high in the order of 1 × 10⁻² S cm⁻¹ at ambient temperature, resulted from the host guest-host charge transfers.     

《C语言程序设计》课堂教学方法的探讨

《C语言程序设计》一直是计算机专业及相关专业的专业基础课。该课程既难教又难学。传统的教学方法往往过分注重语法形式的介绍，却忽视了算法的讲解，使得学生无法解决一些实际编程，也很容易挫伤学生的学习兴趣。为此应以算法教学为主。因材施教，合理使用教材，在改用多媒体教学的同时，适当配以板书。调动学生的主观能动性，提高其编程能力。