Global and local cutoff frequencies for transverse waves propagating along solar magnetic flux tubes

The propagation of linear transverse waves along a thin isothermal magnetic flux tube is affected by a global cutoff frequency that separates propagating and non-propagating waves. In this paper, wave propagation along a thin but non-isothermal flux tube is considered and a local cutoff frequency is derived. The effects of different temperature profiles on this local cutoff frequency are studied by considering different power-law temperature distributions as well as the semi-empirical VAL C model of the solar atmosphere. The results show that the conditions for wave propagation strongly depend on the temperature gradients. Moreover, the local cutoff frequency calculated for the VAL C model gives constraints on the range of wave frequencies that are propagating in different parts of the solar atmosphere. These theoretically predicted constraints are compared to observational data and are used to discuss the role played by transverse tube waves in the atmospheric heating and dynamics, and in the excitation of solar atmospheric oscillations.Comment: To be publishd in ApJ Vol. 763. 10 pages, 3 Postscript figure

The Occurrence of Alexithymia in Children and Adolescents with Posttraumatic Stress Disorder

Previous studies of the relationship between alexithymia and posttraumatic stress disorder (PTSD) have utilized samples of combat veterans with PTSD. However, children and adolescents who have experienced trauma and are diagnosed with PTSD exhibit similar or identical symptomology. The current study examined alexithymia in a sample of children and adolescents diagnosed with PTSD. It was hypothesized that the sample, when compared to non-PTSD and control samples, would reveal a significantly greater severity of alexithymia and PTSD. Although overall results were not consistent with previous research, trends of group means supported a relationship between alexithymia and PTSD.

Image Interpretation Using Appraisal Analysis

In geophysical inversion, a significant effort is invested to obtain images of the Earth from finite data. The first step is to obtain an image i.e. solve the inverse problem. This step alone provides significant challenges that are not addressed inthis paper. The next step is to interpret the image in terms of specific questions. For example, what can we say about the average value of a physical property within a certain region of the model? What scale information can we resolve from the data? These questions are problem dependent and may require that inversion be carried out several times to arrive at a satisfactory answer. Therefore the solution to an inverse problem is only a step towards answering these questions. Appraisal analysis of the solution takes the next step by providing a set of tools to judge and select from the possibly infinite suite of images that adequately fit our observations. We discuss the use of point spread functions and averaging kernels in the interpretation of images. We use a controlled source electromagnetic example to demonstrate the methodology

Towards a Global Controller Design for Guaranteed Synchronization of Switched Chaotic Systems

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.In this paper, synchronization of identical switched chaotic systems is explored based on Lyapunov theory of guaranteed stability. Concepts from robust control principles and switched linear systems are merged together to derive a sufficient condition for synchronization of identical master-slave switched nonlinear chaotic systems and are expressed in the form of bilinear matrix inequalities (BMIs). The nonlinear controller design problem is then recast in the form of linear matrix inequalities (LMIs) to facilitate numerical computation by standard LMI solvers and is illustrated by appropriate examples

Stabilization Based Networked Predictive Controller Design for Switched Plants

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record.Stabilizing state feedback controller has been designed in this paper for a switched DC motor plant, controlled over communication network. The switched system formulation for the networked control system (NCS) with additional switching in a plant parameter along with the switching due to random packet losses, have been formulated as few set of non-strict Linear Matrix Inequalities (LMIs). In order to solve non-strict LMIs using standard LMI solver and to design the stabilizing state feedback controller, the Cone Complementary Linearization (CCL) technique has been adopted. Simulation studies have been carried out for a DC motor plant, operating at two different sampling times with random switching in the moment of inertia, representing sudden jerks

Wavelet Deconvolution in a Periodic Setting Using Cross-Validation

The wavelet deconvolution method WaveD using band-limited wavelets offers both theoretical and computational advantages over traditional compactly supported wavelets. The translation-invariant WaveD with a fast algorithm improves further. The twofold cross-validation method for choosing the threshold parameter and the finest resolution level in WaveD is introduced. The algorithm’s performance is compared with the fixed constant tuning and the default tuning in WaveD

Thin, binary liquid droplets, containing polymer: An investigation of the parameters controlling film shape

For the fabrication of P-OLED displays, using inkjet printing, it is important to control the final shape resulting from evaporation of droplets containing polymer. Due to peripheral pinning and consequent outward capillary flow, a ring-like final shape is typically observed. This is often undesirable, with a spatially uniform film usually required. Several experimental studies have shown that binary liquid inks can prevent ring formation. There is no consensus of opinion on the mechanism behind this improvement. We have developed a model for the drying of thin, binary liquid droplets, based on thin-film lubrication theory, and we solve the governing equations to predict the final shape. White-light interferometry experiments are conducted to verify the findings. In addition, we present the results of a linear stability analysis that identifies the onset of an instability driven by a difference in surface tension. If the more volatile liquid is more abundant, an instability becomes increasingly likely.This research has been funded by the Engineering & Physical Sciences Research Council, UK and CASE studentship funding from Cambridge Display Technology Ltd., UK. We thank Dr Mark Dowling of Cambridge Display Technology Ltd., for help with the experimental setup.This is the author accepted manuscript. The final version is available from Cambridge University Press via http://dx.doi.org/10.1017/jfm.2016.16

Thin, binary liquid droplets, containing polymer: an investigation of the parameters controlling film shape

For the fabrication of P-OLED displays, using inkjet printing, it is important to control the final shape resulting from evaporation of droplets containing polymer. Due to peripheral pinning and consequent outward capillary flow, a ring-like final shape is typically observed. This is often undesirable, with a spatially uniform film usually required. Several experimental studies have shown that binary liquid inks can prevent ring formation. There is no consensus of opinion on the mechanism behind this improvement. We have developed a model for the drying of thin, binary liquid droplets, based on thin-film lubrication theory and solve the governing equations to predict the final shape. White light interferometry experiments are conducted to verify the findings. In addition, we present the results of a linear stability analysis that identifies the onset of a surface tension differential driven instability. If the more volatile liquid is more abundant, an instability becomes increasingly likely.This research has been funded by the Engineering & Physical Sciences Research Council, UK and CASE studentship funding from Cambridge Display Technology Ltd., UK. We thank Dr Mark Dowling of Cambridge Display Technology Ltd., for help with the experimental setup.This is the author accepted manuscript. The final version is available from Cambridge University Press via http://dx.doi.org/10.1017/jfm.2016.16