Papers by Keyword: Scaling Law

Abstract: Polyaniline emeraldine salt (PAni-ES) was successfully deposited on paper through layer-by-layer technique. In this method, a paper was alternately dipped in aniline monomer and an oxidizing agent for different dipping cycles. This process produced green PAni-ES on paper. The morphology of the samples showed polymeric networks with pores, fiber-like structures and aggregates. There is a transition from frequency-independent to frequency-dependent conductivities of the samples. The conductivity increased with increasing number of dipping cycles. The frequency-dependent conductivities follow the power-law behavior reflecting conducting network and hopping mechanisms. Lastly, the conductivities with frequency followed a scaling behavior reflecting a common physical mechanism in PAni-ES on paper.

Abstract: Dynamic fragmentation of ceramic samples with different porosity were carried out using modified Hopkinson bar setup, which allow us to keep samples safe (in order to define fragment size distribution) and to measure fractoluminescence impulses occurred on the fracture surfaces (in order to establish the distribution of intervals between impulses). The analysis of experimental data reveals that the fragment size distribution and distribution of interval between fractoluminescence impulses obeys a power law, which exponent depends on ceramics porosity.

Abstract: The adsorption and diffusion of polydimethylsiloxane (PDMS) with different chain lengths on a silicon (111) surface were studied by molecular dynamics simulations. The relative dielectric constant was selected to be 1 to mimic a vacuum. The chains were all present as two dimensional (2D) adsorption conformation on the surface but different conformations and dynamic properties were found in the two absolutely different environments. The relationship between the adsorption energy of the different chain lengths and the degree of polymerization follows a linear function and the average adsorption energy per segment is -0.42 kcal/mol. In addition, the diffusion coefficient (D) of these chains scales with the degree of polymerization (N) as N_-3/2.

Abstract: This paper presents the similarity conditions between aeroelastic instability (flutter) and the free vibration frequency of cross-ply laminated plate. The method is based upon the direct use of governing equation of the system. Both complete and partial similarities are discussed. This approach, the natural frequency analysis of models and prototype is used to predict the flutter boundary of laminated plate. The results present herein indicate that there are some constrains such as geometry of the model, model material, and stacking sequence of laminates in designing a model with complete similarity. As working with complete similar scale model is usually difficult, some certain types of distortion (distortion in number of plies, and stacking sequence) are considered. According to the results, cross ply composite models can be found which have this ability to predict flutter boundary of the prototype accurately using free vibration data.

Abstract: Electrospinning is a convenient method used in the preparation of ultrafine oil sorptive fibers based on Ethylene-propylene-diene (EPDM), Electrospun fiber diameter, varying in large from micrometer to nanometer, mainly depends upon the solution concentration, which has great influence on this function fiber’s sorption ability. The non-linear relation between mean fiber diameter (d) and solution concentration (C) was investigated and it follows a simple scaling law in the form . This relationship can be used to predict the target fiber diameter and guide the processing technique. The effects of various C on oil sorption ability were investigated in a batch-sorption technique. A comparison of the kinetic models, showed that the removal rate fit the first order kinetic model well, which suggested the sorption process is rapid, can reach equilibrium within a short time.

Abstract: An allometrical scaling relationship between the solution concentration and the nanofiber diameter in bubble electrospinning was established. The scaling law was validated with experimental results using bubble-electrospun Polyvinylpyrrolidone (PVP) nanofibers at different concentration PVP solutions. The results showed that the average diameter of PVP nanofibers increased approximately exponentially with solution concentration in bubble electrospinning process. The experimental data agreed well with the theoretical predictions, and showed that the present model had high prediction accuracy.

Abstract: The development study of blast containment vessels for anti-terrorism has been conducted. The goal of this study is to develop safe disposal vessel for 10 kg of explosives. Considering of the use at the airport or railroad stations, it needs to be more compact compared with the conventional explosion chamber. By introducing both the internal structure and attenuation technology in the vessel, sufficient blast proof ability to contain internal explosion is realized. The blast containment vessel can be used repeatedly by exchanging the internal structure. To realize these concepts, model experiments were carried out using high speed photography, strain and pressure measurements. By introducing these technologies, the vessel for the 1 kg of explosive materials has been made, and the experiments employing 1 kg C4 explosive have been conducted. Finally, the compact blast containment vessel for 10 kg explosives was made, and its blast proof ability was shown by the internal blast test.

Abstract: A significant amount of research has been conducted on the buckling behavior of delaminated composite laminates. However, none of the investigations has been focused on establishing similarity and scaling laws for buckling response of composite laminated with delamination. The main objective of this study is to demonstrate the applicability of similitude theory in designing scaled down models for predicting the buckling behavior of delaminated laminated beam subjected to uni-axial compression. The results presented herein indicate that, for buckling response of delaminated beam-plates, based on structural similitude, a set of scaling laws can be found which use to develop design rules for small scale models. For models with the same material properties and stacking sequence as prototype, distorted models with different number of delaminations, delamination length and depth than those of the prototype can predict the behavior of the prototypes with good accuracy.