Papers by Keyword: Interaction Energy

Abstract: In this paper, the phase behaviour of a cellulose nanocrystal (CNCs) dispersion in sulphuric acid solutions was investigated, aimed at the development of an energy efficient separation method for this mixture. The system in consideration was a mixture of 30 wt% aqueous sulphuric acid (ρ_l = 1219 kg/m³) containing 12.6 mg/ml of cellulose nanocrystals (CNCs) (ρ_s = 1590 kg/m³, volume fraction of CNCs less than 1%). This volume filling mixture was obtained directly from a CNC extraction process, as obtained after the hydrolysis of cotton using 64 wt% sulphuric acid at ca. 45 ̊C for 45 minutes (this condition was required for the extraction of CNCs from cotton) followed by quenching the hydrolysis with water. The CNCs form the desired product and need to be separated from the acid that can then be recycled. Conventionally this separation has been difficult and requires a large input of energy. This work addresses this problem by investigating into the phase behaviour and physicochemical and hydrodynamic character of this mixture. This understanding led to the development of a very energy efficient separation mechanism for this mixture, which is 5 orders of magnitude more energy efficient than the most widely used centrifugation systems.

Abstract: The mechanism governing activated sludge flocculation under Al³⁺ dosing was studied in this paper. Activated sludge was cultivated in sequencing batch reactors (SBR) at 22°C. Batch dosages of Al³⁺ were 0.00, 0.125, 0.5, 1 and 1.5meq/L respectively, and continuous dosage was 0.1meq/L. As batch dosage increased, the total interaction energy, zeta potential and turbidity tended to decline, which suggested that batch dosing promoted sludge flocculation. Under the equivalent dose, the zeta potential of continuous dosing was higher, while the LB-EPS content showed the opposite tendency and turbidity reduction was similar. Both batch and continuous dosing promoted flocculation performance: in terms of interaction energy, batch dosing was more effective; while in terms of EPS, it was on the contrary.

Abstract: The interaction between amorphous silicon dioxide (SiO2) with surface (100) and mixture of glycerol and 1,6-hexanediol was simulated with periodic boundary conditions using the method of molecular dynamics. The properties of silicon dioxide depend on polarity of the groups of the surface. The simulation was respectively calculated that silicon dioxide surface with all silanol groups (Si-OH bonds) or all Si-O bonds interacts with hydroxyl of mixture of glycerol and 1,6-hexanediol in the paper. The results show that the peak of radial distribution function of hydroxyl of mixture on silicon dioxide surface with Si-O bonds is higher than that of the hydroxyl of the mixture on the surface with Si-OH bonds. And self-diffusion coefficient of hydroxyl of the mixture on the surface with the Si-O bonds was smaller than that of hydroxyl of the mixture on the surface with the Si-OH bonds. Interaction energy of silicon dioxide surface with Si-O bonds and the mixture is stronger than that of silicon dioxide surface with Si-O bonds and the mixture at different temperature respectively.

Abstract: Effects of temperature (conventional (25°С) vs. mesophilic (35°С) vs. thermophilic (55°С)) on activated sludge properties (production and composition of EPS and interaction potential) and their roles in bioflocculation and settling were studied using well-controlled sequencing batch reactors fed with a synthetic wastewater comprised of glucose and inorganic nutrients. The results show that thermophilic sludge had a poorer bioflocculation ability and settleability than that of conventional and mesophilic sludge. Analysis of extracellular polymeric substances (EPS) indicates that thermophilic sludge had a higher level of loosely bound EPS (LB-EPS) content than that of conventional and mesophilic sludge. The LB-EPS content of thermophilic sludge was ten times more than TB-EPS content of it, which coincided with higher supernatant turbidity. Therefore, the worse bioflocculation and settling ability of thermophilic sludge could be explained from the perspective of LB-EPS. Calculating the interaction energy of three kinds of sludge, the interaction barrier of thermophilic sludge disappeared which meant the attractive potential was dominant in the system. Thus, it should have led to a better flocculation, which did not agree with the actual performance. It indicates that the worse bioflocculation and settling ability of thermophilic sludge could be explained from the perspective of interaction energy.

Abstract: In this paper input-output pairing is done based on concept of energy. Parseval theorem and cross-covariance samples of input-output are used for estimation of energy. After approximating interaction energy between input and output of the plant, input-output pairing is fulfilled. Through examples, it is illustrated that proposed method is appropriate for input-output pairing. The result is compared with Effective Relative Energy Array (EREA) as another energy based approach for input-output pairing.

Abstract: Austenitic steels can exhibit a complex transformation sequence during deformation. Indeed, the austenitic phase transforms first into bands of ε (HCP) martensite. This transformation is then followed by the formation of α’ (BCC) martensite. In this study, the crystallography of the transformation together with the occurrence of variant selection is studied at the scale of individual austenite grains. About ten prior austenite grains deformed at different strain levels in uniaxial tension were analysed by means of EBSD techniques. One of the classical approaches to predict the variant selection phenomenon is based on the calculation of the interaction energy between the macroscopic stress and the shape deformation associated with the formation of the product phase. The formation of the α’ variants was observed to lead to a very strong variant selection that cannot be fully explained by energetic criterion. It is suggested that the crystallography of the transformation sequence can account for the unexpected variants.

Abstract: The influence of an external stress on the nucleation and growth of disk-shaped G.P. zones has been investigated for a Cu-1.2wt%Be-0.1wt%Co alloy aged at 220 °C. A compressive stress applied in the [001] direction during aging preferentially accelerates the nucleation and growth of the G.P. zones perpendicular to the [001] axis, whereas a tensile stress does not significantly affect those of G.P. zones. The promotion of the nucleation and growth of the G.P. zones perpendicular to the compressive-stress axis can be well understood through the interaction energy between the applied stress and the misfit strains of G.P. zones. The critical diameter of the disk-shaped G.P. zone nucleus was estimated as about 1.3 nm from evaluation of the interaction energy.