On the interpretation of random forces derived by projection operators

We study the derivation of a Langevin equation from a microscopic basis in order to elucidate the nature of the random force. We arrive at the conclusion that the consistent interpretation of the microscopic Langevin equation in terms of a stochastic differential equation (SDE) is according to I o rules. In addition, the random force is in general not Gaussian, and it is hence not completely characterized by its second moments.     

Everything you always wanted to know about SDPD<Superscript>⋆</Superscript> (<Superscript>⋆</Superscript>but were afraid to ask)

An overview of the smoothed dissipative particle dynamics (SDPD) method is presented in a format that tries to quickly answer questions that often arise among users and newcomers. It is hoped that the status of SDPD is clarified as a mesoscopic particle model and its potentials and limitations are highlighted, as compared with other methods.     

Thermal analysis of Mn50Ni50−x(Sn,In)x Heusler shape memory alloys

Journal of Thermal Analysis and Calorimetry - This paper reports the effects of welan gum on the hydration and hardening behaviors of Portland cement (PC) by using X-ray diffractometry, mercury...     

On one approach to a posteriori error estimates for evolution problems solved by the method of lines

Summary. In this paper, we describe a new technique for a posteriori error estimates suitable to parabolic and hyperbolic equations solved by the method of lines. One of our goals is to apply known estimates derived for elliptic problems to evolution equations. We apply the new technique to three distinct problems: a general nonlinear parabolic problem with a strongly monotonic elliptic operator, a linear nonstationary convection-diffusion problem, and a linear second order hyperbolic problem. The error is measured with the aid of the -norm in the space-time cylinder combined with a special time-weighted energy norm. Theory as well as computational results are presented. Received September 2, 1999 / Revised version received March 6, 2000 / Published online March 20, 2001     

Thermal analysis of aged hdpe based composites

HDPE based composites were produced with 10-20-30 and 40% composite mass of wood fiber. The coupling agents were epolene and silane. The thermal behavior of composite samples was analyzed as a function of the coupling agent content, the exposure time and the wood fibers content by means of differential scanning calorimetry. Calorimetric curves of all samples of first and second heating shows a similar behavior. Some significant relation has been observed between the exposure time and the degree of crystallinity for the same percentage of fiber samples. A linear relation between the melting enthalpy average vs. content in cellulosic fibers is detected. Nevertheless, the fibers non-pretreated with coupling agent show a lower loss of crystallinity of the HDPE matrix at low wood fiber content (10%). A slight diminution of the melting peak temperature is detected as increasing the exposure time. This revised version was published online in July 2006 with corrections to the Cover Date.     

Martensitic transformation in Mn–Ni–Sn Heusler alloys

Three magnetic shape memory alloys: Mn₅₀Ni_50−x Sn _x (x = 5, 7.5, and 10) were produced as bulk polycrystalline ingots by arc melting. The structural austenite–martensite transformation was checked by calorimetry. The transformation temperatures decrease as increasing the Sn content. The same trend is found in the entropy and enthalpy changes related to the transformation. The control of the valence electron by atom e/a determines the transformation temperatures range in this kind of alloys and it is possible to develop alloys that can be candidates in applications as sensors and actuators. Furthermore, X-ray diffraction was performed to check the crystalline structure at room temperature.     

Thermal analysis of Fe(Co,Ni) based alloys prepared by mechanical alloying

In this work several Fe(Co,Ni) based nanocrystalline alloys were obtained by mechanical alloying. Thermal study was performed by differential scanning calorimetry and thermogravimetry. After 80 h milling, all DSC scans show several reactions on heating. At low temperature, about 400 K, the exothermal process detected is associated to structural relaxation. In all alloys, the main crystallization process begins over 700 K and has apparent activation energy values between 3.7 and 3.1 eV at^–1. The Co content increases the thermal stability of this process. Furthermore, thermomagnetic measurements confirm the Co solid solution into Fe. The ferromagnetic–paramagnetic transition occurs at about 900 K.