测定陶瓷材料阻力曲线的包络线法的改进

本文通过对压痕弯曲梁的压痕载荷和断裂强度关系的理论分析和推导,介绍了一种确定切点(即K曲线和R曲线的交点)的方法,这些切点的轨迹组成了R曲线,并通过实验对这种方法进行了验证。结果发现这种改进的包络线法与常规的包络线法所测得的阻力曲线相吻合。这种方法完善了常规的K曲线切点包络线法,更为重要的是它揭示了压痕弯曲梁的压痕载荷和断裂强度关系的物理内涵。     

高铝质强化日用瓷釉料

通过调整软质熔剂和硬质熔剂的种类和数量 ,研制出了适合刚玉质强化瓷的釉面硬度 7373MPa、白度 75 .9%、光泽度 89.3%且高热稳定性的透明釉料     

Nitrous oxide emission from upland crops and crop-soil systems in northeastern China

Although it is known that crops can directly emit N₂O, their contribution to the total N₂O emission from crop-soil systems under field conditions is not well understood. This study was conducted to study the contribution of crops to total N₂O emission from soybean-soil and maize-soil systems in northeastern China. The effects of N fertilization on N₂O emission and NO ₃ ⁻ -N concentration in plants were also studied. The emission from crop-soil systems was measured with the closed chamber method, whereas the direct emission from crops was measured with the soil surface-sealed method. The addition of fertilizer N significantly increased the NO ₃ ⁻ -N concentration in crops and enhanced the N₂O emission from crop-soil systems and from crops alone. The amount of N₂O emitted directly from soybean plants accounted for 6 to 11% of the total soybean-soil emission. Similarly, the amount of N₂O emitted directly from maize plants accounted for 8.5 to 16% of the total maize-soil emission. The proportion of the applied N lost through direct N₂O emission from plants ranged from 0.19 to 0.34%, whereas the proportion of the applied N lost through N₂O emission from the crop-soil system ranged from 1.1 to1.9%. These results suggest that the use of chambers that do not include plants may lead to an underestimation of the total N₂O emission from crop-soil systems. This revised version was published online in November 2006 with corrections to the Cover Date.     

涤纶切片的结晶性能及其对POY结构均匀性的影响

采用ＤＳＣ等方法研究了几种涤纶切片的等速降温结晶性能，提出了用熔融结晶峰的半高宽／峰高的比值、过冷度和结晶度来定量表征的方法，并结合纺丝过程讨论了其对ＰＯＹ成形时结构均匀性的影响。结晶性能差的切片，易得到结构均匀的ＰＯＹ。     

甲基葡萄糖甙（MeG）水溶液工艺改进试验

介绍了用５次以上的母液生产ＭｅＧ水溶液工艺的改进试验。     

用瞬时法测定液体导热系数

以珠状热敏电阻为加热元件,建立了用瞬时法测定液体导热系数的装置,在25℃下用乙二醇等7个标准样品,对该装置进行了标定,平均偏差为2%.为了核实装置和所得关系式的可靠性,又测定了13个已知导热系数的样品,多数偏差在2%以内,最大偏差为5%.单次测量的精度为0.2%.本文叙述了这一方法的原理,并对实验结果进行了讨论.     

Non-existence of finite-time stable equilibria in fractional-order nonlinear systems

We note that in the literature it is often taken for granted that for fractional-order system without delays, whenever the system trajectory reaches the equilibrium, it will stay there. In fact, this is the well-known phenomenon of finite-time stability. However, in this paper, we will prove that for fractional-order nonlinear system described by Caputo’s or Riemann–Liouville’s definition, any equilibrium cannot be finite-time stable as long as the continuous solution corresponding to the initial value problem globally exists. In addition, some examples of stability analysis are revisited and linear Lyapunov function is used to prove the asymptotic stability of positive fractional-order nonlinear systems.     

压力容器用封头制造质量控制和专业化生产发展方向

中国法规首次对压力容器等特种设备用封头实施制造资格许可和强制的监督检验制度。本文根据法规标准的规定,对压力容器封头制造质量控制和专业化生产发展方向的要求作一系统的综述,以提高压力容器产品的整体质量,确保特种设备安全万无一失。     

New approach for the preparation of nanoporous polyorganosilicate low‐k films

The distribution of pores and the mechanical properties of materials are the key factors in preparing satisfactory low‐k films. In the present study, a kind of silsesquioxane‐polyethylene glycol (SSQ‐PEG) was synthesized and used as a template to make the distribution of pores more even in the low‐k films. The crosslinking density of films could be adjusted by the sol‐gel of tetramethoxysilane/dimethoxydimethylsilane with various proportions. The porosity of films could also be adjusted with different proportions of pendant PEG chains introduced. A dielectric constant as low as 2.1 had been achieved for nanoporous polyorganosilicate films with good tenacity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1238–1243, 2007     

聚乙二醇酯磷酸锌三元配合物在水中的摩擦性能研究

合成了 3种聚乙二醇酯磷酸锌 (铈 )水溶性润滑添加剂 ,采用红外光谱表征其结构 ,四球摩擦磨损试验机测定其摩擦学性能。结果表明 ,分子中聚乙二醇作为水溶性基团 ,相对分子质量以 1 0 0 0为宜 ,相对分子质量太小 ,聚合物在水中溶解性差 ,影响其润滑性能 ;聚乙二醇的相对分子质量过大 ,导致聚合物在水中的溶解性太好 ,影响其在金属表面的吸附 ,同样影响其润滑性能。作为油性剂作用的疏水基团 ,碳链较长者润滑性能好 ,润滑性能优劣顺序 :C1 7H35>C1 1 H2 3>C7H1 5。金属元素作为活性元素 ,铈的抗磨性能优于锌的抗磨性能。一个分子中同时具有亲水性、疏水性、反应性等几类官能团 ,则兼具油性剂和极压剂功能 ,是性能优良的水溶性润滑添加剂