Influence of Structure Forming Components on The Viscosity of Oils

In the oil industry almost all flow models have viscosity as an intrinsic variable. Many flow behaviours will be affected by the oil viscosity. In this work model oil systems were used to study the influence of paraffin wax and asphaltenes on the viscosity of oils. In these systems the content of paraffin wax varied in the range of 3.2–8%, and asphaltenes in the range of 1.2–5.2%. It was found that the viscosity of light oils changes slightly with increasing the content of asphaltenes or paraffin wax . It was also found that the viscosity of heavy oils increases with asphaltenes content growth and decreases almost twice with the increase of paraffin wax content.

Influence of Structure Forming Components on The Viscosity of Oils

In the oil industry almost all flow models have viscosity as an intrinsic variable. Many flow behaviours will be affected by the oil viscosity. In this work model oil systems were used to study the influence of paraffin wax and asphaltenes on the viscosity of oils. In these systems the content of paraffin wax varied in the range of 3.2–8%, and asphaltenes in the range of 1.2–5.2%. It was found that the viscosity of light oils changes slightly with increasing the content of asphaltenes or paraffin wax . It was also found that the viscosity of heavy oils increases with asphaltenes content growth and decreases almost twice with the increase of paraffin wax content.

Artificial multimodal receptors based on ion relaxation dynamics

Human skin has different types of tactile receptors that can distinguish various mechanical stimuli from temperature. We present a deformable artificial multimodal ionic receptor that can differentiate thermal and mechanical information without signal interference. Two variables are derived from the analysis of the ion relaxation dynamics: the charge relaxation time as a strain-insensitive intrinsic variable to measure absolute temperature and the normalized capacitance as a temperature-insensitive extrinsic variable to measure strain. The artificial receptor with a simple electrode-electrolyte-electrode structure simultaneously detects temperature and strain by measuring the variables at only two measurement frequencies. The human skin–like multimodal receptor array, called multimodal ion-electronic skin (IEM-skin), provides real-time force directions and strain profiles in various tactile motions (shear, pinch, spread, torsion, and so on).

Sparse Multicategory Generalized Distance Weighted Discrimination in Ultra-High Dimensions

Distance weighted discrimination (DWD) is an appealing classification method that is capable of overcoming data piling problems in high-dimensional settings. Especially when various sparsity structures are assumed in these settings, variable selection in multicategory classification poses great challenges. In this paper, we propose a multicategory generalized DWD (MgDWD) method that maintains intrinsic variable group structures during selection using a sparse group lasso penalty. Theoretically, we derive minimizer uniqueness for the penalized MgDWD loss function and consistency properties for the proposed classifier. We further develop an efficient algorithm based on the proximal operator to solve the optimization problem. The performance of MgDWD is evaluated using finite sample simulations and miRNA data from an HIV study.

The role of the hypothalamus in cortical arousal and sleep homeostasis

Sleep and wakefulness are not simple homogenous all-or-none states, but instead are characterized by rich dynamics of brain activity across many temporal and spatial scales. Rapid global state transitions between waking and sleeping are believed to be controlled by hypothalamic circuits, but the contribution of the hypothalamus to within-state changes of sleep and wake “intensity” remains largely unexplored. Here we show that stimulation of inhibitory neurons in the preoptic hypothalamus does not merely trigger awakening from sleep, but the resulting awake state is also characterized by increased cortical activity. This activation is associated with a faster build-up of sleep pressure, proportional to the arousal level. These findings show that hypothalamic systems thought to exclusively control global state switching, also regulate within-state “intensity”, which we propose as a key intrinsic variable in shaping the architecture of sleep/wake states across the 24h day.

Subaru and Salt Spectroscopy of Chemically Peculiar Hot Subdwarfs

The majority of hot subdwarfs lie on or close to the helium main-sequence. Many have hydrogen-rich surfaces, but a substantial fraction of the hotter subdwarfs have hydrogen-depleted or hydrogen-deficient surfaces. Amongst the former, three were known to show extraordinary overabundances of heavy elements including zirconium and lead. Using Subaru/HDS,we commenced a high-resolution survey of hydrogen-depleted subdwarfs to discover new members of the class. UVO 0825+15, was found to exhibit strong lead lines, to be an intrinsic variable in K2 field 5, and to have a relatively high space motion. Two other lead-rich subdwarfs have been found in the Subaru sample. A much wider survey is in progress using SALT/HRS. Discoveries so far include one extreme helium star similar to V652 Her, and an intermediate helium star with possible comparison to HD144941. Analyses of the hotter and more compact members of the sample are continuing.

A Low-Dimensional Principal Manifold as the "Attractor Backbone" of a Chaotic Beam System

We model an elastic beam subject to a contact load which displaces under a chaotic external forcing, motivated by application of a ship carrying either a crane, or fluids in internal tanks. This model not only has rich dynamics and relevance in its own right, it gives rise to a Partial Differential Equation (PDE) whose solutions are chaotic, with an attractor whose points lie "near" a low-dimensional curve. This form identifies a data-driven dimensionality reduction which encapsulates a Cartesian product, approximately, of a principal manifold, corresponding to spatial regularity, against a temporal complex dynamics of the intrinsic variable of the manifold. The principal manifold element serves to translate the complex information at one site to all other sites on the beam. Although points of the attractor do not lie on the principal manifold, they lie sufficiently close that we describe that manifold as a "backbone" running through the attractor, allowing the manifold to serve as a suitable space to approximate behaviors.

Augmented State Approach in Quasi-Sliding-Mode Controlled PEBB-Based Power Converters

A wide class of high power converters have modular structures as they are constituted of the connection of two-level modules, according to the power electronic building block (PEBB) concept. Moreover, the intrinsic variable structure nature of PEBBs makes sliding mode control an attractive solution. When complex configurations are considered the number of PEBBs can be different from the number of switching relations, and modularity concept is not still valid at control level. The present paper proposes and discusses a general and systematic approach which makes it possible to have a one-to-one correspondence between the number of PEBBs and the switching control laws. It makes it possible to preserve the modularity of PEBB allowing to have an embedded modulation strategy. In such a way, standard current-tracking algorithm can be applied at PEBB level. The approach is based on augmented state method and makes it possible to verify separately for each PEBB both sliding and reaching conditions. The proposed approach is verified and supported through simulation tests.