The social organisation of communication in the home of the twenty-first century: an analysis of the future of paper-mail and implications for the design of electronic alternatives

This paper reports ongoing investigations into the use and role of paper-mail communications in domestic environments. It utilises ethnographically informed data to analyse how paper-mail supports various social roles within the home, particularly a division of labour whereby women tend to be largely responsible for what may be called "managing the home". Implications for the future of paper-mail are considered, as well as suggestions made about how email tools may be designed to reflect the patterns of social organisation within the home. Electronic Publication     

Pasture intake and substitution rate effects on nutrient digestion and nitrogen metabolism during continuous culture fermentation

A continuous culture system was used to investigate ruminal digestion in response to increased pasture intake and three different substitution rates (SR) in a 4 x 4 Latin square design. The treatments were 1) low pasture (55 g dry matter (DM)/d, 2) medium pasture (MP, 65 g DM/d), 3) high pasture (75 g DM/d), and 4) pasture (45 g DM/d) plus concentrate (PC, 30 g DM/d). Treatments were designed to produce a low (0.33), medium (0.67), and high (1.00) SR (g of pasture/g of concentrate) by contrasting the low, medium, and high pasture intake treatments with the pasture plus concentrate treatment, respectively. Pasture was fed at 0630, 1000, 1730, and 2100 h, and concentrate at 0600 and 1700 h. Digestibility of DM and neutral detergent fiber were not affected by the amount of pasture. As the amount of pasture increased, pH decreased linearly, and total volatile fatty acid and NH3-N concentrations, and nonammonia N and bacterial N flows increased linearly. Concentrate supplementation did not affect DM digestibility at high SR but increased DM digestibility at low SR. Concentrate supplementation reduced pH and NH3-N concentrations at the three SR. Concentrate supplementation reduced the ratio of rumen degradable N to rumen degradable organic matter; however, the mechanism depended on the SR. High SR, concentrate supplementation reduced rumen degradable N, which reduced NIH-N concentration without affecting bacterial N flow. At low SR, concentrate supplementation increased rumen degradable organic matter, which reduced NH3-N concentration and increased bacterial N flow. Based on these results, at low SR, concentrate supplementation may enhance animal performance because of higher total DM intake and synthesis of microbial protein.     

Effect of Nb Doping on (Sr,Ba)TiO3 (BST) Ceramic Samples

The effect of doping the Sr_0.3Ba_0.7Ti_(1–5y/4)Nb _y O₃ ceramic with different concentration of Nb is studied by scanning electron microscopy (SEM), X-ray diffraction and thermoelectric analysis. It is observed that the grain size decreases as the Nb concentration increases. The critical temperature T _c has a linear decrease at a rate of 19°C/mol% of Nb. The temperature dependence of the dielectric permittivity presents strongly broadened curves, which suggest a non Curie-Weiss behavior near the transition temperature. The diffuse phase transition coefficient () was also determined and its value leads to the conclusion that the degree of disorder in the system increases with the presence of the Nb cation.     

Synthesis of the Bi-2222 Compounds of Bi–Sr–Ln(Zr)–Cu–O (Ln = Sm,Eu, Gd,and Dy)

Bi-based superconducting compounds with the 2222 structure has been already synthesized in the Bi₂Sr₂- (Ln_1−x Ce _x )₂Cu₂O_10+y (Ln = Sm, Eu, and Gd) systems. One of the characteristics of these compounds is the existence of the fluorite-like (Ln_1−x Ce _x )₂O₂ block between two CuO₅ pyramids in the crystal structure. The tetravalent ions of Ce⁴⁺ are reported to be necessary to stabilize the 2222 structure. Recently, we have discovered that the Bi-2222 phase could be composed in the Bi₂Sr₂(Ln_2−x Zr _x )Cu₂O _z (Ln = Sm, Eu, Gd, and Dy) systems, where Zr⁴⁺ is used as a new tetravalent ion stabilizing the 2222 structure in stead of Ce⁴⁺. In the new system, nearly single 2222 phase samples have been obtained at the nominal composition of x=0.5 (Ln = Sm, Eu, and Gd) and in the range of 0.1≤x≤0.3 (Ln = Dy). Among them, the sample with Ln = Gd has the smallest resistivity at 273 K. But it is a semiconductor, and the conduction process at low temperatures is assumed to be followed by a two-dimensional VRH. The experimental results for the Gd samples with a partial substitution of Pb for Bi in the Bi₂Sr₂(Gd_2−x Zr _x )Cu₂O _z system are also reported.     

The behavior of angle-ply laminated cylindrical shells with viscoelastic interfaces in cylindrical bending

The behavior of a simply supported angle-ply laminated cylindrical shell in cylindrical bending with viscoelastic interfaces is studied. The Kelvin–Voigt model is adopted to represent the character of interfaces. State-space formulations are developed based on the exact elasticity equations, and in particular, a variable substitution technique is used to derive the state equations with constant coefficients. Since the behavior of this structure under static loading is time-dependent, the power series expansion technique is used to approximate the variations of physical variables with time. The response for a laminated shell with viscous interfaces is also investigated as a particular case. Results show that the displacements as well as the maximum stresses in the panel increase rapidly with time. Thus, the imperfect bonding properties should be considered carefully in the design of laminated structures.     

基于遗传算法的密码分析方法

论文基于遗传算法的基本思想,给出了一个运用遗传算法进行密码分析的一种方法和算法,并验证了该方法的有效性。     

B位取代对钛酸锌相结构及介电性能的影响

通过固相烧结法结合半化学法制备了ZnO-(1-x)TiO2-xSnO2(x=0.04~0.20)陶瓷,掺杂1.0%3V2O5(质量分数)-B2O3降低陶瓷的烧结温度,研究了B位取代对ZnTiO3相结构及介电性能的影响。结果表明,Sn的加入促进了六方相分解,形成了立方尖晶石结构的固溶相Zn2(Ti1-xSnx)O4;随烧结温度升高,Sn的固溶量增加,900℃时,最大固溶量为0.08 mol。900℃烧结试样,随x增加,其介电常数ε先增大后减小,而介电损耗tanδ恰好相反,先减小后增大,当x=0.12时,得到ε的最大值(ε=29)和tanδ的最小值(tanδ=9.86×10-5)。900℃烧结的具有优良介电性能的ZnO-(1-x)TiO2-xSnO2(x=0.04~0.20)陶瓷有很好的实际应用前景。     

以置换法求静定刚架的位移

给出了各梁位移的置换法位移方程.提出了一种解静定刚架位移的新方法,并举例应用.     

高等数学中"变量替换法"应用探讨

文章阐述了"变量替换法"在高等数学计算中的重要意义和应用特点,以使学生在高等数学的学习中能充分注意把握并能熟练、灵活地运用好"变量替换法",提高学生的解题能力。     

电压稳定分析中支路型故障筛选及排序算法研究

提出了一种用于电压稳定性分析的支路型故障筛选和排序的快速算法，该方法分为4个阶段：①依据正常运行状态下的潮流解从所有预想事故中筛选出严重事故；②通过分析线路被置换后系统雅克比矩阵的最小奇异值，从所筛选出的事故中再次筛选出更严重的事故；③在指定的负荷水平下解潮流方程，从第二次筛选出的事故中再次筛选出最严重的事故；④对每个最严重的事故进行1次潮流计算，估计其最大负荷能力。通过New-England 39节点系统和IEEE 118节点系统算例表明，此算法计算量少，简单有效，易于实现。