THERMO PHYSICAL PROPERTIES OF TERNARY MIXTURES OF 1-HEXANOL/1- OCTANOL CONTAINING N-N-DIMETHYLFORMAMIDE AND TOLUENE AT 303.15 K

In the present work, ultrasonic velocity (u), viscosity (η) and density (ρ) of ternary mixtures of 1-hexonal and 1-octanol with dimethylformamide in toluene at 303.15 K have been measured over the entire composition range. From the experimental data, acoustical parameters such as adiabatic compressibility (β), intermolecular free length (L ), free volume (V ), acoustic impedance (Z), excess adiabatic compressibility , excess free length , excess free f f E E (b ) (L )f volume and excess acoustic impedance have been computed. The variation of these properties with composition are E E (V ) (Z ) f discussed in terms of molecular interactions between unlike molecules of the mixtures.

Thermo Acoustic Study of Salicylaldehyde in Carbon Tetra Chloride at 303.15K, 308.15K, 313.15K

Thermo-acoustic study in binary mixture of salicylaldehyde and carbon tetra chloride were reported at 303.15K, 308.15K, 313.15K. The molecular interaction have been carried out by computing various thermo acoustical parameters i.e. Intermolecular free length (Lf), Specific acoustic Impedance (Z), Molar Volume (Vm), Available Volume (Va), Isentropic compressibility (S) and other constant and the excess value of foresaid parameters have been evaluated by using ultrasonic velocity, density, viscosity data, the results of these parameters conclude the strength of molecular interaction. Keywords: Excess values of Salicylaldehyde, Acoustic Parameters, Molecular Interaction.

Study of Acoustical and Physico-chemical Properties for the Ternary Mixture of (Toluene+ Chlorobenzene + Cyclohexane) at 298.15 K Temperature

Ultrasonic velocity (U), density (ρ) for the ternary mixture of (Toluene + Chlorobenzene + Cyclohexane) in the various range of composition has been carried out at 298.15K. The observed data have been utilized to calculate various acoustical parameters like Isentropic compressibility (KS), Intermolecular free length (Lf) and acoustic impedance (Z). The various excess properties like excess ultrasonic velocity(UE ), excess acoustic impedance (ZE ), excess Isentropic compressibility (KS E ) and excess Inter molecular free length (Lf E ) have been calculated and using standard relations to the Redlich-Kister equation. The trend of acoustical and physicochemical parameters confirm the dynamics of molecules at temperature and the magnitude of intermolecular interactions among the constituents of the mixture always reflects the nature of substance. The variations in sign and values of these parameters are help us to know the interaction between component molecules and structural arrangement of the liquid mixture.

An Investigation on the Effects of Architectural Features on Acoustical Environment of Historical Mosques

In the historical period, different mosques were built in the Anatolian side; the differences in size, typology and style were affected by the climate conditions, cultural and social aspects, availability of materials and the construction techniques of the region they were built in. The ceiling structure, which is the most influencing factor for mosque acoustics, is designed with either curvilinear elements or a flat ceiling for mosques. In the context of our case study, the eight historical mosques in Turkey, with different materials and types of ceiling structures, are investigated in terms of acoustical characteristics in the main prayer hall. Acoustical data are collected by measurements to reveal how the formal differences and material change in ceiling structures affect the acoustic environments of mosques with similar volume. Distribution of acoustical parameters and the suitability of the values obtained through measurements are compared to reflect the effect of architectural features on the acoustical characteristics of the prayer hall.

The effects of different ceiling structures and plan typologies on acoustical conditions of historical mosques

Mosque is a building type used by Muslim people consists of speech and music rituals. Good acoustical condition in mosques is an important issue to provide desired acoustical environment for prayers and Imams during different worship rituals. Prayers need to feel individuality in praying and the sense of unity in recitation of the Quran, hymns. Worship activities need a high level of speech intelligibility and to satisfy prayers in the spiritual aspects which make people feel closed to the God. In the context of study, six historical mosques in Turkey, with different types of cover structures and plan typologies, are designated as study areas. The present study contains two methods which the first one is collecting acoustical data by measurements and the second consists of mathematical modelling software program. The purpose of study to investigate effects of different plan typology and ceiling structures on acoustical characteristics in mosques with similar volume. Also, distribution of acoustical parameters and the suitability of the values obtained through acoustic simulations and measurements to the recommended values are aimed to be investigated. As a result of the investigations, it was concluded that the objective acoustic parameters of mosques changed according to the geometric parameter properties.

An Energy Model for the Calculation of Room Acoustic Parameters in Rectangular Rooms with Absorbent Ceilings

The most common acoustical treatment of public rooms, such as schools, offices, and healthcare premises, is a suspended absorbent ceiling. The non-uniform distribution of the absorbent material, as well as the influence of sound-scattering objects such as furniture or other interior equipment, has to be taken into account when calculating room acoustic parameters. This requires additional information than what is already inherent in the statistical absorption coefficients and equivalent absorption areas provided by the reverberation chamber method ISO 354. Furthermore, the classical diffuse field assumption cannot be expected to be valid in these types of rooms. The non-isotropic sound field has to be considered. In this paper, a statistical energy analysis (SEA) model is derived. The sound field is subdivided into a grazing and non-grazing part where the grazing part refers to waves propagating almost parallel to the suspended ceiling. For estimation of all the inherent parameters in the model, the surface impedance of the suspended ceiling has to be known. A method for estimating the scattering and absorbing effects of furniture and objects is suggested in this paper. The room acoustical parameters reverberation time , speech clarity , and sound strength were calculated with the model and compared with calculations according to the classical diffuse field model. Comparison with measurements were performed for a classroom configuration. With regard to all cases, the new model agrees better with measurements than the classical one.

Effect of Temperature and Concentration on the Physical Properties of Cholesteryl Pelargonate Near Transition Temperatures

Thermodynamic and acoustical study of cholesteric liquid crystal (CLC) was carried out near phase transition temperatures using an ultrasonic interferometer. The study of ultrasonic waves and related thermo-acoustical parameters provides information in understanding the nature of molecular interactions associated with liquid crystals. A statistical mechanical approach is used to calculate the viscosity of samples. The characteristic textures and phase transition temperatures are obtained with Polarizing Microscopy (POM). Fabry Perot scattering studies (FPSS) are used to ascertain the phase transition temperatures of CLC. The thermo-acoustical parameters have been calculated using experimental data with well-known formulae. The acoustical parameters show variation with temperature as well as with concentration of CLC. Anomalous behavior of these parameters is noticed at the clearing temperature of CLC. The variation of the parameters is explained in terms of solute-solvent molecular interactions in the solution. The molecular behavior, structural changes, and intermolecular interactions between CLC and solvent are discussed in detail.