Functional copolymer/organo‐MMT nanoarchitectures. II. Dynamic mechanical behavior of poly(MA‐co‐BMA)s‐organo‐MMT clay nanocomposites

Functional copolymer/organo‐silicate [N,N′‐dimethyldodecyl ammonium cation surface modified montmorillonite (MMT)] layered nanocomposites have been synthesized by interlamellar complex‐radical copolymerization of preintercalated maleic anhydride (MA)/ organo‐MMT complex as a ‘nano‐reactor’ with n‐butyl methacrylate (BMA) as an internal plasticization comonomer in the presence of radical initiator. Synthesized copolymers and their nanocomposites were investigated by dynamic mechanic analysis, X‐ray diffraction, SEM, and TEM methods. It was found that nanocomposite dynamic mechanical properties strongly depend on the force of interfacial MA … organo‐MMT complex formation and the amount of flexible n‐butyl ester linkages. An increase in both of these parameters leads to enhanced intercalation and exfoliation in situ processes of copolymer chains and the formation of hybrid nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Interpolated LIR Mth-band filter design with allpass subfilters

We propose a new allpass-based structure for the IIR Mth-and 2Mth-band filters. These filters consist of M allpass filters and an interpolation filter (sum of two allpasses). Consequently, the proposed structure is very efficient in implementation. By choosing the allpass phase appropriately, the resulting phase response of the IIR Mth-band filter becomes approximately linear. An example is designed and compared with FIR Mth-band filters     

Turbulent boundary layers with assigned wall shear

In this paper we consider the problem of computing the external velocity distribution on a two-dimensional body in an incompressible boundary-layer flow for a specified wall shear. This leads to an ‘overdetermined’ boundary-value problem for a partial differential equation containing the edge velocity as an unknown parameter. A numerical procedure for determining the external velocity is given, together with several examples for laminar and turbulent boundary layers.     

Surface stress measurement techniques in metal forming

This paper describes and classifies stress measurement techniques used in metal forming to provide research workers with a critical evaluation of usable methods. Eight techniques are considered; pressure transmitting pins, photoelasticity, ridged metallic sheets, paper sheets, split tools, strain gauged tools, orifices in tools and visioplasticity. In addition to these, some new transducer designs using optics and conical pins are presented. These are particularly useful for pressure measurement in hot forming operations.     

Thermal response of an unsteady laminar boundary layer on a flat plate due to step changes in wall temperature and in wall heat flux

The prediction of the entire time-history of the heat transfer process due either to a step change in plate surface temperature or to heat flux is studied for two-dimensional, incompressible laminar flows. The study utilizes a very efficient numerical method for solving the nonsteady energy equation. Numerical results for several Prandtl numbers are compared with analytical results obtained with the restriction of small and large time values, and the range of applicability of these analytical solutions is established.     

Piezoelectric two-layer stacks of cellular polypropylene ferroelectrets: transducer response at audio and ultrasound frequencies

Piezoelectric cellular polypropylene films, so-called ferroelectrets, are assembled in a stack with two active transducer layers. The stack is characterized with respect to its linear and quadratic response in a frequency range from 1 kHz to 80 kHz. A relatively smooth frequency response in the sound-pressure level is found for the individual layers as well as for both layers driven in phase. The piezoelectric response of the two-layer stack is twice the response of an individual layer over a rather broad frequency range. Furthermore, the influence of the preparation conditions on the resonance frequency and the effect of the quadratic distortion on the radiated sound are investigated both for the individual transducer films in the stack and for the stack system as a whole.     

新的分析仪器在中国纺织厂的应用经验

<正>1介绍质量的许多定义之一是产品的某些属性满足客户或是用户的需要,对纺织工艺来说,质量常常通过纤维、纱线或是织物的不同属性来定义,这些属性必须得到系统的控制。