Inelastic interactions in the dynamic response of structures

The dynamic response of structures is examined under a general condition of loading. It is shown that the inelastic response of structures depends on the interaction between forces and displacements existing at a section during yielding. A theory of yielding is developed in terms of forces and displacements incorporating the effects of such interactions. Based on this theory, a force-displacement relationship is derived under a general condition of loading. The use of this relationship to study the response of structures is discussed and equations of motion are derived for a simple frame subjected to simultaneous base excitation along its principal directions. To study the inelastic response of structures, under a general condition of loading, it is necessary to derive the equation of the yield surface in terms of forces acting at a section. For the special case of bending about the principal axes of a section, equations of yield surfaces are derived for various structural sections. The response of a simple frame, subjected to sinusoidal base excitation, is obtained for elastic behavior, elasto-plastic behavior and elasto-plastic behavior with interaction. The response for these behaviors is compared and it is shown that interaction causes significant changes in the response. The response of the frame is also investigated for earthquake type excitation and a series of curves are presented to show the effect of interaction on various response parameters. Use of these curves for inelastic design of structures is indicated and the implications of the effects of interaction are examined

Effect of Methanol Content on Specific Adsorption of Chloride Ions at Hg/HCI Interface

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FABRICATION AND CHARACTERIZATION OF RALOXIFENE LOADED SOLID-LIPID NANOPARTICLES

Objective:  The poor water solubility of the drug presents a great challenge for the formulation development and results in low oral bioavailability. The oral bioavailability of Raloxifene HCl (RLX) is very low (<2%) in humans due to its poor solubility. The objective of the present study was to develop RLX loaded solid-liquid nanoparticles for effective drug delivery. Methods: Compritol 888 ATO-based RLX-loaded solid lipid nanoparticles (SLNs) were formulated using the oil in water microemulsion method. Drug-excipients compatibility was confirmed through Fourier transform infrared spectroscopy, Differential scanning calorimetry methods. The SLN was characterized for particle size, surface morphology, entrapment efficiency. Results: A total of seventeen formulations (SLN1-SLN17) were developed as per the 3 levels 3 factor Box–Behnken design. The model used for the analysis was statistically analyzed using ANOVA and the goodness of fit was evaluated using diagnostic plots. As per the response-surface plots, the amount of lipid, poloxamer 407, and ultrasonication time have a significant effect on the particle size and entrapment efficiency (%EE). The developed RLX-loaded SLNs have the size and %EE in the range of 165.63±2.62 nm to 315.33±4.87 nm and 75.21±2.32% to 95.32±2.11%. The TEM analysis showed that the developed RLX-loaded SLNs were almost spherical and has a small size range. Conclusion: The high biocompatibility, biodegradability, ability to protect drugs in GIT, and sustained release properties make SLNs an ideal candidate to resolve poor oral bioavailability challenges

Chain Reconnections observed in Sympathetic Eruptions

The nature of various plausible causal links between sympathetic events is still a controversial issue. In this work, we present multi-wavelength observations of sympathetic eruptions, associated flares and coronal mass ejections (CMEs) occurring on 2013 November 17 in two close-by active regions. Two filaments i.e., F1 and F2 are observed in between the active regions. Successive magnetic reconnections, caused by different reasons (flux cancellation, shear and expansion) have been identified during the whole event. The first reconnection occurred during the first eruption via flux cancellation between the sheared arcades overlying filament F2, creating a flux rope and leading to the first double ribbon solar flare. During this phase we observed the eruption of overlaying arcades and coronal loops, which leads to the first CME. The second reconnection is believed to occur between the expanding flux rope of F2 and the overlying arcades of the filament F1. We suggest that this reconnection destabilized the equilibrium of filament F1, which further facilitated its eruption. The third stage of reconnection occurred in the wake of the erupting filament F1 between the legs of overlying arcades. This may create a flux rope and the second double ribbon flare and a second CME. The fourth reconnection was between the expanding arcades of the erupting filament F1 and the nearby ambient field, which produced the bi-directional plasma flows towards both upward and downward. Observations and a nonlinear force-free field extrapolation confirm the possibility of reconnection and the causal link between the magnetic systems.Comment: 37 pages, 17 figures, Accepted for publication in Ap

Contact angle hysteresis can modulate the Newtonian rod climbing effect

The present work investigates the role of contact angle hysteresis at the liquid-liquid-solid interface (LLS) on the rod climbing effect of two immiscible Newtonian liquids using experimental and numerical approaches. Experiments revealed that the final steady state contact angle, $\theta_{w}$ at the LLS interface varies with the rod rotation speed, $\omega$. For the present system, $\theta_{w}$ changes from $\sim$69$^{\circ}$ to $\sim$83$^{\circ}$ when the state of the rod is changed from static condition to rotating at 3.3 Hz. With further increase in $\omega$, the $\theta_{w}$ exceeds 90$^{\circ}$ which cannot be observed experimentally. It is inferred from the simulations that the input value of $\theta_{w}$ saturates and attains a constant value of $\sim$120$^{\circ}$ for $\omega>$ 5 Hz. Using numerical simulations, we demonstrate that this contact angle hysteresis must be considered for the correct prediction of the Newtonian rod climbing effect. Using the appropriate values of the contact angle in the boundary condition, an excellent quantitative match between the experiments and simulations is obtained in terms of: the climbing height, the threshold rod rotation speed for onset of climbing, and the shape of liquid-liquid interface. This resolves the discrepancy between the experiments and simulations in the existing literature where a constant value of the contact angle has been used for all speeds of rod rotation

Interaction of Two Filament Channels of Different Chiralities

We present observations of interactions between the two filament channels of different chiralities and associated dynamics that occurred during 2014 April 18 -- 20. While two flux ropes of different helicity with parallel axial magnetic fields can only undergo a bounce interaction when they are brought together, the observations at the first glance show that the heated plasma is moving from one filament channel to the other. The SDO/AIA 171 A observations and the PFSS magnetic field extrapolation reveal the presence of fan-spine magnetic configuration over the filament channels with a null point located above them. Three different events of filament activations, partial eruptions, and associated filament channel interactions have been observed. The activation initiated in one filament channel seems to propagate along the neighbour filament channel. We believe that the activation and partial eruption of the filaments bring the field lines of flux ropes containing them closer to the null point and trigger the magnetic reconnection between them and the fan-spine magnetic configuration. As a result, the hot plasma moves along the outer spine line toward the remote point. Utilizing the present observations, for the first time we have discussed how two different-chirality filament channels can interact and show interrelation.Comment: 30 pages, 13 figures, Accepted for Publication in Ap