Detection of river/sea ice deformation using satellite interferometry: limits and potential

In this paper, we present a study consisting of the application of radar interferometry for river/sea ice monitoring in inhabited regions and on commercial waterways. The sites studied are located in Canadian regions where ice jams constitute a common winter hazard that can cause extensive socio-economic damage and impose severe restrictions on ship traffic. ERS and Radarsat images were jointly used with traditional in situ observations to detect ice break-up in order to prevent ice jams and related problems. A coherence study served to define the synthetic aperture radar interferometry (InSAR) limits for river/sea ice dynamics monitoring. Other factors that also help to define the limits of InSAR technology for this application include the frequency of image acquisition, the minimum dimension of detected ice floes and the determination of appropriate ice types. Significant phase shifts were found for small ice floes of several hundred metres with ERS-tandem images. The analysis of the interferograms showed that it is possible to detect deformations in the ice shelf and to discriminate quantitatively the horizontal and vertical components of ice movement when the interferograms are combined with traditional observations such as meteorological data, water level, water flow and ice charts. The deformation estimated on a piece of fast river ice can be interpreted as the first sign of the ice break-up. On an estuary river that is a busy seaway, a qualitative interpretation of the interferograms served to highlight the interaction of river and tidal flows affecting the ice cover. We showed, in particular, the potential of radar interferometry and its integration with other techniques to help the authorities to prevent problems related to ice jams.     

IDFC: A new approach to control bifurcation in TCP/RED

The main objective of this research is to analyze the bifurcation phenomenon in Internet congestion model for Transmission Control Protocol (TCP) with Random Early Detection (RED). This problem can be divided to many categories considering different viewpoints. Different approaches of modeling (continuous and discrete models) and various system structures (control in end node or routers) are some of these categories. The most significant method in control of such systems is Delayed Feedback Controller (DFC). In this paper, a discrete model is considered and a new algorithm Integral DFC (IDFC) is presented that has many preferences over similar algorithms, which are illustrated by simulation results and analytical discussions.     

An adaptive sliding mode controller design to cope with unmatched uncertainties and disturbance in a MEMS voltage reference source

Tunable micro-electro-mechanical systems (MEMS) capacitors as the fundamental parts are embedded in MEMS AC voltage reference sources (VRS). Being concerned with the accuracy of the output voltage in the reference sources, it gets important to address uncertainties in the physical parameters of the MEMS capacitor. The uncertainties have the great inevitable potentiality of bringing about output voltage perturbation. The output deterioration is more remarkable when the uncertainties are accompanied by disturbance and noise. Manufacturers have been making great attempts to make the MEMS adjustable capacitor with desired rigorous physical characteristics. They have also tried to mitigate physical parameter veracity. However, ambiguity in the values of the parameters inescapably occurs in fabrication procedures since the micro-machining process might itself suffer from uncertainties. Employing a proportional integral (PI) adaptive sliding mode controller (ASMC), both terms of matched and unmatched uncertainties as well as the disturbance, are addressed in this work for the MEMS AC VRS so that a strict voltage is stabilized while the system is simultaneously subjected into uncertainties and exogenous disturbance. Cross-talk, some inertial forces, and electrostatic coercions may appear as matched and unmatched disturbances. Alteration in stiffness and damping coefficients might also take place as matched uncertainties due to variations in the fabrication process or even working environment. The simulation results in the paper are persuasive and the controller design has shown a satisfactory tracking performance.     

Sensitivity analysis of influencing parameters in cavern stability

In order to analyze the stability of the underground rock structures, knowing the sensitivity of geomechanical parameters is important. To investigate the priority of these geomechanical properties in the stability of cavern, a sensitivity analysis has been performed on a single cavern in various rock mass qualities according to RMR using Phase 2. The stability of cavern has been studied by investigating the side wall deformation. Results showed that most sensitive properties are coefficient of lateral stress and modulus of deformation. Also parameters of Hoek–Brown criterion and σ_c have no sensitivity when cavern is in a perfect elastic state. But in an elasto-plastic state, parameters of Hoek–Brown criterion and σ_c affect the deformability; such effect becomes more remarkable with increasing plastic area. Other parameters have different sensitivities concerning rock mass quality (RMR). Results have been used to propose the best set of parameters for study on prediction of sidewall displacement.     

Practical Output Regulation of Uncertain Strict‐Feedback Form Systems

In this paper, an output feedback control is proposed to solve the practical output regulation problem of a class of nonlinear systems. In the first step of the design procedure, two sets of coordinate transformations are used to convert the output regulation problem of the system in the strict‐feedback form into the regulation problem of the transformed system in the uncertain normal form. Then, for the resulting system, a state feedback in the cast of nested sliding mode control is designed. Finally, by using the nonlinear separation principle, the output feedback controller is achieved by substituting the estimated states, resulting from the high‐gain observer, instead of real states. It can be shown that the states of the closed‐loop system are ultimately bounded. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Exploiting Kondo spin chains for generating long range distance independent entanglement

We investigate the entanglement properties of the Kondo spin chain when it is prepared in its ground state as well as its dynamics following a single bond quench. We show that a true measure of entanglement such as negativity enables to characterize the unique features of the gapless Kondo regime. We determine the spatial extent of the Kondo screening cloud and propose an ansatz for the ground state in the Kondo regime accessible to this spin chain; we also demonstrate that the impurity spin is indeed maximally entangled with the Kondo cloud. We exploit these features of the entanglement in the gapless Kondo regime to show that a single local quench at one end of a Kondo spin chain may always induce a fast and long lived oscillatory dynamics, which establishes a high quality entanglement between the individual spins at the opposite ends of the chain. This entanglement is a footprint of the presence of the Kondo cloud and may be engineered so as to attain—even for very large chains—a constant high value independent of the length; in addition, it is thermally robust. Moreover, we show that high entanglement between very distant boundary spins is generated by suddenly connecting two long Kondo spin chains. We show that this procedure provides an efficient way to route entanglement between multiple distant sites. To better evidence the remarkable peculiarities of the Kondo regime, we carry a parallel analysis of the entanglement properties of the Kondo spin chain model in the gapped dimerised regime where these remarkable features are absent.     

Toward mechanistic understanding the effect of aspect ratio of carbon nanotubes upon different properties of polyurethane/carbon nanotube nanocomposite foam

This study investigated the carbon nanotube's aspect ratio's influence on the nanocomposite foams' cellular structure and mechanical, acoustic absorption characteristics. The free-rising foaming process has been used for producing different flexible polyurethane (PU) foams embedded with other multi-walled carbon nanotubes (MWCNT's). Dynamic mechanical and thermal analysis, flow resistivity, and compressive mechanical measurements were achieved on the prepared samples. The acoustic absorption coefficient in a wide range of frequencies was estimated for the prepared PU/CNT foamed nanocomposite samples. Results indicated that by increasing the aspect ratio of MWCNT, the absorption coefficient's peak shifts toward the lower frequencies and improved sound absorption characteristics of PU foam in the low-frequency region. Moreover, the Young modulus of nanocomposite samples increases by increasing the aspect ratio of MWCNT's, whereas the stored strain energy or area under the stress–strain curve increases. Based on the obtained results, it is observed that the acoustic absorption coefficient of produced nanocomposite foams at the frequency of 800 Hz has been reported to have a 70% improvement in 2 cm samples and a 40% improvement in 3 cm samples compared to obtained results from pure PU foam.     

Quantum dots: synthesis, bioapplications, and toxicity

ABSTRACT: This review introduces quantum dots (QDs) and explores their properties, synthesis, applications, delivery systems in biology, and their toxicity. QDs are one of the first nanotechnologies to be integrated with the biological sciences and are widely anticipated to eventually find application in a number of commercial consumer and clinical products. They exhibit unique luminescence characteristics and electronic properties such as wide and continuous absorption spectra, narrow emission spectra, and high light stability. The application of QDs, as a new technology for biosystems, has been typically studied on mammalian cells. Due to the small structures of QDs, some physical properties such as optical and electron transport characteristics are quite different from those of the bulk materials.     

Crystallization and Drying of Milk Powder in a Multiple-Stage Fluidized Bed Dryer

The rationale of this study has been to use fluidized beds to crystallize amorphous spray-dried skim milk powders with multiple stages of processing at different temperatures and humidities with the aim of rapidly making mostly crystalline powders. This paper discusses the performance of a multiple-stage fluidized bed dryer, and a combination of crystallization of lactose in spray drying at high humidity (lactose nuclei formation) and subsequent fluidized bed drying. Two different combinations of spray dryer and multi-stage fluidized-bed dryer have been suggested to crystallize lactose in skim milk powder. The results show significant improvements in the crystallinity of the powders. Moisture sorption test and X-ray diffraction analysis were used to assess the crystallinity of the powders. The processed powders that were crystallized in a humid-loop spray drying combined with a two-stage fluidized-bed dryer/crystallizer showed 92% improvement in lower amorphicity by processing at different stages of 70°C, 50% RH and 80°C, 50% RH for 15 minutes. The conventionally spray-dried powders that were crystallized in a three-stage fluidized-bed dryer/crystallizer showed 87% improvement in lower amorphicity (less moisture sorption) by processing at different stages of 60°C, 50% RH; 70°C, 40% RH; and 80°C, 40% RH for 20 minutes. The multiple-stage fluidized bed system showed distinctive potential to crystallize lactose significantly in skim milk powder using an industrial-feasible process.     

Liposome: classification,preparation, and applications

Liposomes, sphere-shaped vesicles consisting of one or more phospholipid bilayers, were first described in the mid-60s. Today, they are a very useful reproduction, reagent, and tool in various scientific disciplines, including mathematics and theoretical physics, biophysics, chemistry, colloid science, biochemistry, and biology. Since then, liposomes have made their way to the market. Among several talented new drug delivery systems, liposomes characterize an advanced technology to deliver active molecules to the site of action, and at present, several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles to ‘second-generation liposomes’, in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. This paper summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations in respect to industrial applicability and regulatory requirements concerning liposomal drug formulations based on FDA and EMEA documents.