Dynamic properties of calcareous and siliceous sands under isotropic and anisotropic stress conditions

The strain-dependent dynamic properties of sand are generally described by their relative density and mean effective stress, while the contribution of other factors, like soil origin, mineralogy, grain morphology, and initial stress anisotropy, have not been fully recognized. This paper presents the results of an experimental study on the shear modulus and damping ratio of calcareous and siliceous sands of different origins and their identical grain size distribution and stress-density states. Resonant column and cyclic triaxial tests were conducted on reconstituted samples of these two sands obtained from coastal areas. The significance of the initial effective confining pressure and stress anisotropy on the dynamic properties of the sands is evaluated and compared. It is demonstrated that the small-strain shear modulus of the calcareous sand is more affected by an increase in mean effective confining pressure than the siliceous sand. However, the effect of the initial shear on the secant shear modulus of the sands is unique. Based on the test data, a rigorous correction factor is proposed to account for the influence of the initial stress anisotropy on the small-strain shear modulus of the sands. A comparison between the strain-dependent dynamic properties of the calcareous and siliceous sands reveals that the calcareous sand has a higher secant shear modulus, lower damping ratio, and higher linear and volumetric threshold strain. Since the stress-density states and grain size distribution of the two sands were identical in the experiments, the discrepancy in the dynamic properties can be attributed to other factors, including sand origin, grain angularity, mineralogy, and formation processes, which are not commonly taken into account in the current practice.     

An Evaluation of Public Concerns About Water Management in the Palestinian Territory Pre,During, and Post the National Uprising

We have evaluated the extent of public concerns about water management in the Palestinian Territory (PT) through a survey of the main Palestinian newspaper over the last thirteen years divided in three periods: pre (1984–1987), during (1988–1991), and post national uprising period (1992–1996). The public concern in the PT about various water management aspects was clear and influenced by the prevailing political conditions indicating (1) poor concerns in the first and second period where full Israeli military control of the PT and harsh practices prevailed with relatively more emphasis on regional water issues and (2) extensive-strong concerns in the third period when the peace process started and a partial lift of some of the Israeli water practices took place, along with an increased freedom in expressing public concerns which was granted with more emphasis on local issues and problems. Lack and limitation of water available to Palestinians, alternative solutions, and water quality and pollution control constituted the overwhelming majority of the topics of concern to the public for the three periods studied. Palestinian concerns were always greater than regional ones for the three periods and all of the topics considered. Public concern in the PT about all other water management aspects was poor and negligible especially in the first two periods. A massive increase in public concern has been observed in the third period in which the public expressed their concern over most water management aspects, indicating a possible change in public attitude toward water and water management and reflecting the change of the political status by the start of the peace process and the signing of the peace agreements.     

A statistical framework for few-shot action recognition

Along with the exponential growth of online video creation platforms such as Tik Tok and Instagram, state of the art research involving quick and effective action/gesture recognition remains crucial. This work addresses the challenge of classifying short video clips, using a domain-specific feature design approach, capable of performing significantly well using as little as one training example per action. The method is based on Gunner Farneback’s dense optical flow (GF-OF) estimation strategy, Gaussian mixture models, and information divergence. We first aim to obtain accurate representations of the human movements/actions by clustering the results given by GF-OF using K-means method of vector quantization. We then proceed by representing the result of one instance of each action by a Gaussian mixture model. Furthermore, using Kullback-Leibler divergence (KL-divergence), we attempt to find similarities between the trained actions and the ones in the test videos. Classification is done by matching each test video to the trained action with the highest similarity (a.k.a lowest KL-divergence). We have performed experiments on the KTH and Weizmann Human Action datasets using One-Shot and K-Shot learning approaches, and the results reveal the discriminative nature of our proposed methodology in comparison with state-of-the-art techniques.

     

Pyrene-adamantane-β-cyclodextrin: An efficient host–guest system for the biofunctionalization of SWCNT electrodes

The design of nanostructured biological architectures based on host–guest interactions between β-cyclodextrin and adamantane was investigated on SWCNT coatings using glucose oxidase (GOX) as biomolecule model. β-Cyclodextrin tagged GOX was immobilized on adamantane functionalized carbon nanotubes, deposited on platinum electrodes. Different functionalization techniques to attach “pyrene adamantane” on nanotubes were studied and compared in terms of the performances of the subsequently constructed glucose biosensors. The best results were obtained by dipping the nanotube deposit into a pyrene-adamantane solution followed by electropolymerization of the adsorbed pyrene monolayer. The constructed biosensor exhibited a good linear response toward glucose concentrations between 2 × 10⁻⁷ M and 1.6 × 10⁻³ M. The maximum current density and glucose sensitivity were 154.9 μA cm⁻² and 14.4 mA M⁻¹ cm⁻², respectively.     

Influence of organic liquids on the nanostructure of precipitated cellulose

Organic liquids have been used in pretreatments to improve the digestibility of lignocellulosic biomass, ultimately reducing the amount of enzyme required to digest the material to its constituent sugars. To understand the influence of these solvents on cellulose nanostructure, phosphoric acid was used to solubilize cellulose (PAS cellulose) followed by washing of the PAS cellulose with organic liquids previously demonstrated to aid pretreatment. PAS cellulose washed using methanol, ethanol, and ethylene glycol had gel‐like properties with disrupted nanostructures. PAS cellulose washed with acetone, 2‐propanol, and water yielded an opaque white precipitate. Small‐angle neutron scattering indicated the formation of loosely bundled rods of cellulose in the gel‐like material. Fourier transform infrared resonance of solvent‐washed, flash‐dried PAS cellulose suggested an increase in interchain hydrogen bonds in the gel‐like precipitates relative to the more obvious precipitates formed in other solvents. The optimal wash liquid was determined to be 40% by volume ethanol in water to induce a highly digestible, gel‐like material. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Infiltration behavior of Cu and Ti fillers into Ti2AlC/Ti3AlC2 composites during tungsten inert gas (TIG)brazing

Herein we study the infiltration behavior of Ti and Cu fillers into a Ti₂AlC/Ti₃AlC₂MAX phase composites using a TIG-brazing process. The microstructures of the interfaces were investigated by scanning electron microscopy and energy dispersive spectrometry. When Ti₂AlC/Ti₃AlC₂ comes into contact with molten Ti, it starts decomposing into TiC_x, a Ti-richandTi₃AlC; when in contact with molten Cu, the resulting phases are Ti₂Al(Cu)C, Cu(Al), AlCu₂Ti and TiC. In the presence of Cu at approximately 1630 °C, a defective Ti₂Al(Cu)C phase was formed having a P63/mmc structure. Ti₃AlC₂ MAX phase was completely decomposed in presence of Cu or Ti filler-materials. The decomposition of Ti₂AlC to Ti₃AlC₂ was observed in the heat-affected zone of the composite. Notably, no cracks were observed during TIG-brazing of Ti₂AlC/Ti₃AlC₂ composite with Ti or Cu filler materials.     

Synthesis and characterisation of fluorescent pyrene‐end‐capped polylactide fibres

Fluorescent markers are critical for tracking the position and movement of molecules both in vivo and in vitro. Conventionally, synthetic dyes are non‐covalently added to polymers for fluorescent tracking, but often diffuse away. Here we demonstrate, for the first time, a facile method for the synthesis of fluorescent poly(lactic acid) nano‐/microfibres for biomedical applications using solution spin blowing. Pyrene‐end‐capped poly(l ‐lactide) (PLLA) derivatives were synthesised using the ring‐opening polymerisation of l ‐lactide and they were characterised using spectroscopic and thermal analyses. Submicrometre‐sized fluorescent fibres were produced from these PLLA derivatives using solution blow spinning techniques generating polymer blends and core–shell fibres. Such system could be further exploited to incorporate electrically conductive carbon allotropes via the pyrene aromaticity, producing fluorescent and electrically active fibres for in vitro monitoring and electrical stimulation. © 2018 Society of Chemical Industry     

Easy mass spectrometry for metabolomics and quality control of vegetable and animal fats

Easy ambient sonic spray ionization (EASI), a novel desorption/ionization technique for ambient mass spectrometry analysis, is shown to permit the characterization of different types of vegetable and animal fats. The taxonomic markers of the oils, mainly fatty acids and phenols, are extracted with methanol/water (1:1) solution and made alkaline with NH₄OH, then placed and dried on the surface of a glass tip and directly analyzed by EASI‐MS in the negative‐ion mode. EASI provides a supersonic cloud of charged droplets that causes efficient desorption and ionization of the oil markers directly from the surface of the glass tip. As proof‐of‐principle cases, EASI(?)‐MS was applied to genuine samples of olive oil, hazelnut oil, soybean oil, grape seed oil, canola oil, butter, and lard. Characteristic metabolomics EASI(?)‐MS profiles of fatty acids and eventually phenols were obtained.     

Neuroadaptive output feedback control for nonlinear nonnegative dynamical systems with actuator amplitude and integral constraints

A neuroadaptive output feedback control architecture for nonlinear nonnegative dynamical systems with input amplitude and integral constraints is developed. Specifically, the neuroadaptive controller guarantees that the control amplitude as well as the integral of the control input over a given time interval are constrained, and the physical system states remain in the nonnegative orthant of the state space. The proposed approach is used to control the infusion of the anesthetic drug propofol for maintaining a desired constant level of depth of anesthesia for noncardiac surgery in the face of infusion rate constraints and an integral drug dosing constraint over a specified time period. Copyright © 2010 John Wiley & Sons, Ltd.     

Bake induced charge gain in NOR flash cells

Charge gain, caused by localized defects in the tunnel oxide of floating gate devices, is one of the central reliability concerns of flash memory. In this work, we show that charge motion in the poly sidewall spacers of flash cells can also result in substantial charge gain, for nonoptimized processes. Data showing the time, temperature, and field dependencies of this charge gain mechanism are presented. It is shown that the threshold voltage shift caused by charge motion in the poly sidewall spacers follows the simple factorial expression: ΔV _th=C·V_fg·t^α ·e^-ϵ(a)kT/