Slowness surfaces study of the ferroelastic phase transition of LiCsSO4 crystal
The method of slowness surface is used to study the ferroelastic phase transition of LiCsSO4. The slowness surfaces of the crystal have been plotted between 202K and 293K. The direction of the maximum slowness is on the XZ plane and the angle of it and X axis is -49.5 degree when temperature is above 206K. At 206K, the direction of the maximum slowness is along X axis. As the temperature decreases from 206K to 202K, the direction of the maximum slowness doesn't change anymore but the slowness surfaces change dramatically. According to the soft mode theory and the elastic constitutive relations, we obtained that LiCsSO4 crystal is in the same symmetry between 202K and 206K.
Raman study of LiCsSO4
Polarized Raman spectra of single crystals of LiCsSO4 are obtained. It is found that factor group analysis isolated fails to give a consistent interpretation of the spectra. Hence, a complementary calculation, based on a group theoretical method, is employed to obtain the relative intensities for all of the internal modes. This calculation yields zero intensity for the B1g mode of the v1-type of vibration, so that the corresponding observed band is/assumed to be the Ag symmetry mode, exclusively. Several calculated intensities result in almost negligible values for other Ag and B1g modes. This fact is particularly helpful in the analysis of experimental data thus improving assignments of the Raman bands. 
 
 
 
Des spectres Raman polarises du monocristal LiCsSO4 ont ete etudies. On a montre que l'analyse isolee de groupe facteur ne conduit pas a l'interpretation precise des resultats experimentaux. Alors, on a employe une methode theorique auxiliaire pour calculer les intensites relatives des raies, pour toutes les vibrations internes du cristal. On obtient ainsi la valeur zero pour l'intensite du mode B1g relatif a la vibration v1 de l'ion libre, et pourtant la raie correspondante observee provient d'un mode de symetrie Ag seulement. D'autre part, ce calcul a resulte en des intensities trop faibles pour certains autres modes Ag et B1g. Ces faits ont donne l'explication d'un certain nombre d'observations experimentales en apportant des avantages pour l'interpretation des spectres.
A model for predicting heat transfer through gypsum‐board/wood‐stud walls exposed to fire
To facilitate the development of cost-effective and flexible design options there is a need to develop models to predict the fire resistance of wood-frame building assemblies. Such assemblies often derive much of their fire resistance from a protective membrane composed of gypsum board. A simple two-dimensional computer model is presented to predict heat transfer through gypsum-board/wood-stud walls exposed to fire. Input data for the thermophysical properties of gypsum board were measured exploying standard bench-scale tests. Input data for wood were selected from the literature. Small-and full-scale fire resistance tests were conducted on gypsum-board/wood-stud wall assemblies to provide data for the validation of the model. The model is shown to predict heat transfer through these walls rather well.