Papers by Keyword: Compressibility

Abstract: Be aimed at the development and application of aerospace high-temperature resistant ceramic fiber felt, in this paper, as the common ceramic fiber felt in the field of high temperature resistance, quartz fiber felt, high silica fiber felt and mullite fiber felt were compared. The microstructure, thermal insulation, temperature resistance and mechanical properties were analyzed respectively, the performance advantages and disadvantages of three kinds of ceramic fiber felt were given, and its internal causes were studied. The results show that, the temperature resistance of mullite fiber felt is better than that of quartz fiber felt and high silica fiber felt, mainly due to its polycrystalline mullite structure, the thermal insulation performance of mullite fiber felt and high silica fiber felt is better than quartz fiber felt at high temperature, mainly due to the thermal reflection of polycrystalline mullite and the small pore structure of high silica fiber felt, the compressibility of quartz fiber felt is better than high silica fiber felt and mullite fiber felt.

Abstract: Peat is commonly described as a soil that is possess to high rate of compressibility due to present of high organic substance derived from plant origins. Peat soil naturally associated with settlement and consolidation characterized by its high initial void ratio, organic content and water holding capacity. This paper presents the performance of peat soil treated with powdered melamine urea formaldehyde resin (MUF-P) in term of compression and consolidation behaviour under standard compressibility test. In this study, series of one-dimensional oedometer test were carried out with the load increment method from 12.5 to 400 kPa after 24 hours of each loading. Peat soils under high moisture condition were mixed with MUF-P within 3 days of stipulated periods of curing times. The results indicate that increasing the MUF-P proportion has improved the compressibility characteristics of peat soil. The result shows the values of compression index (C_c) decreased from 4.12 to 0.9, and secondary compression index (C_α) were also decreased from the range of 0.026 to 0.320 to the range of 0.080 to 0.161 with the increase of peat MUF-P proportions up to maximum 350 kg/m³.

Abstract: The effect of adding sand on clayey soil compressibility is investigated in this study. Four different percentage of clay-sand mixtures are used; 100% clay with 0% sand named 100C, 30% clay with 70% sand named 30C-70S, 15% clay with 85% sand named 15C-85S, and 100% sand named 100S. The used clay was obtained from Baghdad city in Iraq and classified as CH soil, while the used sand was taken from the sand quarry in Al-Khider area from Al-Muthana Governorate in Iraq and classified as SW soil. The initial dry unit weight for all mixtures is 18 kN/m³. The results show that the variations of the soil compressibility properties with soil components content changes almost linearly The results show that the preconsolidation stress (P_c) decreases with 19% and 38% and the rebound index (C_r) decreases with 4 and 53% and the compression index (C_c) decreases with 39 and 68% as the sand percentage increases with 70 and 85% respectively. Finally, predicted (fitting) Equations are achieved for the change of the soil compressibility properties with clay content with good agreement.

Abstract: Densification process of biomass to the form of high-grade solid biofuel (briquette or pellet) is influenced by amount of technological factors. Size fraction and moisture content of raw material have the most importance. The densification process may be describing by complicated mathematical models based on behaviour of pressed particular matter. Therefore it is complicated to energy optimize the process. This paper deals with a methodology for determining the compressibility for pine sawdust on the basis of experiments. It also specifies the effectiveness criterion for biomass densification in order to optimize the densification process in terms of energy input. The experiments were performed in two stages. The first stage was an experimental investigation of the influence of size fraction and moisture content on the final compressibility of pine sawdust. High-pressure binderless densification of pine processing residues in the form of sawdust was studied. A piston-and-die process was used to produce densified briquettes under 20 °C temperature and at pressure up to 159 MPa. The results show the behaviour of the pressure load when the parameters of the particulate matter are changed. In the second stage, the experiments were evaluated and optimized to achieve minimum energy input of the process and a maximum degree of densification. For this purpose the Effectiveness Criterion for Densification was designed

Abstract: The more increasing severe impact of the mercury use on health, particularly as the amalgam material, has required an alternative innovation in order to eliminate the composition of mercury and amalgam. The objective of this research was to proposed a new biocompatible material which was called zinc oxide (ZnO). One of the innovative breakthroughs is by applying nanotechnology to ZnO, an alternative material expectedly to have better physical features and compressibility. Those physical features here including morphology, dimensions, and the comparison ratio of atom were analyzed through the test of XRD, XRF, SEM, and EDX characterization. Further, for its compressibility features, the test of compressibility was carried out using the hydraulic pressing machine with the power of 100-4000 kgf. This test was treated variously on the compression loading (500, 1000, and 2000 kg) with the variety of dwelling times (30, 60 and 90 seconds) purposely to observe its effect on the density of nanoparticles ZnO. The result of this research then shows that the physical properties of the analyzed ZnO has the particle in the size of 14,34 nm with the morphology classified as nano­rods. In the compressibility test, the variation of compression loadings has brought an effect on the significant increase of density of nanoparticles ZnO. In the compression loading at 500 kg, the average of density of ZnO is at 3,170 (g/cm³) with the increase of 4,763% with the addition of the compression loading into 1000 kg. Subsequently, another increase of density again takes place by 7, 539 % in the compression load changed into 2000 kg. The variation of the dwelling times also contributed to an equal effect in which at the dwelling time of 30 seconds, the average of density of ZnO was at 3,260 (g/cm³), at the dwelling time of 60 seconds, it increased at 0,583%, and the dwelling time of 90 seconds, it again increased at 3,098%.

Abstract: Ultrasonic parameters of CuO: Diethylamine-Isopropaonol binary nanofluids at six different concentrations have been reported at three different temperatures like 298K, 308K and 318K. The acoustical parameters such as Ultrasonic sound velocity (v), Compressibility (β), Inter molecular free length (Lf), Acoustic impedance (Z) are calculated from experimental data. The variation of these parameters with composition of the mixture helps us in understanding the nature and extent of interaction between particles and the binary liquid mixtures. Keywords Ultrasonic velocity, Compressibility, Acoustic impedance, Inter molecular free length, Nanofluids

Abstract: The study of compressibility in deformable porous media is of interest in many industrial processes, such as, filtration, thickening and during oil well drilling processes in the petrochemical sector. In this work the compressibility of porous media was evaluated by the comparison of solid concentration profiles in sediments using fluids with Newtonian and non-Newtonian behavior. For this, consolidation tests in distillated water, solutions of xanthan and glycerol were performed in a vertical column from the gravitational settling of suspensions. The porosity distribution in the formed sediment was obtained after the complete settling of particulate material. The local porosity measurements were performed using the ionizing radiation emitted by americium-241. The gamma-ray attenuation technique used in this study allowed the realization of nondestructive measurements for achieving local concentration of solids. The results showed that the rheological behavior of the fluid does not change significantly the compressibility of the porous matrix.

Abstract: In order to reliably design and operate different powder processes, an understanding of the dynamic flow, shear and bulk properties of powders is required. Generally, powders are evaluated by several techniques that determine their flow, shear and bulk properties. The techniques can include compression tests, shear tests, angle of repose, flow of powder in a funnel, tapped density and many others. In order to minimize the number of instruments required to characterise the powder and eliminate operator error, automated powder rheometers that can do most of the required tests have been developed. The FT4 powder rheometer is one of these and has found widespread use in the pharmaceutical industry. In this study, the FT4 powder rheometer was used to characterise two metallic titanium powders with different particle sizes, namely CSIR Ti-45μm (Fine Powder) and CSIR Ti +45-180μm (Coarse Powder). Their particle size, particle size distribution, bulk densities, compressibility, cohesion, flowability index, effective angle of internal friction and wall friction angle were determined. Preliminary results of the study indicated that fine powder had a lower bulk density, was more compressible and more cohesive than the coarse powder. The fine powder had a lower flowability index compared to the coarse powder for both the Jenike and Peschl classification. The varying degrees of cohesion of these powders were confirmed by the cohesion values that were higher for the fine powder. The fine powder had a lower angle of internal friction but higher wall friction angle compared to the coarse powder.

Abstract: Mathematical background for static analysis of impulse gas seal is created in current paper. It includes evaluation of gap and flow rates of gas in turbocompressors. This paper consists of two parts. In the first one all logical steps of creation of the theoretical model for impulse gas seals are given. It should be mentioned, that they are valid for isothermal steady process which is observed here. The verification of derived theory is shown in the second part on a calculation example.

Abstract: This work involves the preparation of Cu-Al-SiC composite powders by a high-energy milling process and the study of their densification behavior by cold compaction. The goal of the milling process is to get embedded the ceramic particles in the metal matrix to enhance the distribution of the metal and ceramic phases in the compacts, an important condition to derive in isotropic properties of consolidated materials. For comparison purposes, compressibility tests of a Cu-5Al matrix prepared by high-energy milling were performed; while additions of 1, 5 and 10 vol.% SiC were added to the matrix. It was found that the high-energy milling process leads to Cu-Al-SiC composite powders with a homogeneous distribution of the reinforcement in the matrix. Compressibility essays showed that densification of the powders decreased with SiC content; a densification of 73.7% was obtained for composites with 10% SiC compared to 76.0% for samples with 1% SiC at the maximum load applied. Milling time reduced the plastic deformation capacity of the matrix leading to fracture of the cold welded aggregates; the fracture process was accelerated by the addition of the hard reinforcement particles. Thus, morphology of the powders changed from laminar, to fine fragments and coarse aggregates, affecting the compaction behavior.