Interesting Features In Terms Research Articles

Integral backstepping improvement versus classical and multiscalar backstepping controllers for water IM‐pump fed by backstepping MPPT PV source based on solar measurements in a tropical insular region

The work presented here deals with a comparison between integral, classical and multiscalar backstepping controllers applied for a PV water pumping system. The solar pumping system is controlled in its first part by a backstepping maximum power point tracking approach in order to extract a maximum power from solar panels. The second part, composed mainly by induction motor–pump is controlled by backstepping structures. The integral backstepping control structure gives interesting features in terms of stability using recursive Lyapunov design, increases robustness despite parameters variation, and provides good tracking and optimization performance. In order to validate the study with a real solar data, a measured irradiance profile is used to fed the PV system, based on solar measurements in tropical insular context. The measurements are collected at Sonapi site located in Haiti country. The fast variability of the tropical irradiance profile will allow to test the robustness of the used control algorithms and determine their limits. Simulation of the proposed solution is validated under Matlab/Simulink. Results demonstrate clearly that integral backstepping provides the best solution with a good tracking, and optimization performance: fast dynamic response and stable static power output, even when weather conditions (irradiation) are rapidly changing.

Mechanical and Microstructural Analysis of an Ultra-Flexible Nano-Silver Paste Sintered Joint

Soldering using common lead-free solder alloys is still one of the main die attach technology, in particular for applications in power electronics where high temperatures have to be met. However, some newly developed attach technologies promise to offer more interesting features in terms of both mechanical and thermal properties. Among these new methods, sintering of nano-silver particles allows to obtain a high thermal conductivity needed in the assemblies of electronic or optical components, as well as a relatively low elastic modulus for better stress accommodation and enhanced thermo-mechanical reliability. The sintering processing parameters, mainly the bonding pressure, the sintering temperature profile, and the sintering atmosphere, are known to have a critical effect on the properties of the sintered layer, such as its mechanical strength and electrical/thermal performances.In this study, copper substrates are fabricated and assembled by sintering using a nano-silver paste. The objective is to obtain a bonding joint with high mechanical flexbility, capable of addressing the thermomechanical stresses for systems operating under high temperatures. The measured mechanical properties of the sintered material show on the one hand low elastic modulus of the joint which is appropriate for strong difference in thermal expansion between components, and on the other hand sufficient mechanical strength for the assembly. Microstructure analyses reveal a highly porous silver network structure of the joint, with submicrometric silver grains and large micrometric porosities homogeneously distributed.

Smart Designing of Tragacanth Gum by Graft Functionalization for Advanced Materials

AbstractTragacanth gum is a novel polysaccharide which offers interesting features in terms of high hydrophilicity, good biocompatibility, and biodegradability. The engineering of hydrogels requires careful designing of their macromolecular structures so that desirable features may be incorporated into the material. Graft polymerization has come up as an interesting approach to develop molecules for drug delivery, wound care systems, and infection‐resistant materials. The most important aspect of graft functionalization is the proper control over physico‐chemical properties of the grafted matrix. The extent of functionalization may be governed by the grafting parameters and may lead to the chemical designing of the molecule in a controlled manner. This opens up enormous possibilities of developing materials for a wide range of applications as advanced materials.

Molten salt fast reactor SAMOFAR: Safety issues of the chemical plant

The concept of Molten Salt Fast Reactor (MSFR) has been selecting by the Generation IV International forum as it presents interesting features in terms of safety, sustainability and economics. SAMOFAR project aims to provide the safety assessment of the MSFR concept based on the Thorium fuel cycle. This document provides the radiological assessments for the chemical plant, including shielding requirements and decay heat evaluations.

4-Bit serial shift register with reset ability and 4-bit LFSR in QCA technology using minimum number of cells and delay

Quantum-dot cellular automata (QCA) nanotechnology is one of the proposed technologies for replacing CMOS technology. Shift registers are one of the important areas in the design of digital circuits and memory structures. Given the importance of shift registers, in this paper, new structures have been proposed for shift registers in QCA nanotechnology. At first, proposed D-latch is presented to be used in the main block of shift registers, which has only 18 cells, a delay of 0.5 cycles and less area than previous designs. Subsequently, a 4-bit series register will be presented using the proposed D-latch, which is at least 30% lower than the previous ones in terms of cell numbers and area. In addition, a reset pin is needed in shift registers which are used in microprocessors. Most of the previous designs did not have the reset pins and therefore a new version of 4-bit shift register which has the reset pin will be presented in this paper. New and former designs have been expanded from 2 bits to 8 bits, and parameters variations are presented in the table and diagrams. The proposed new designs have interesting features in terms of stability, number of cells and occupied area, compared to previous designs that do not have the reset capability. In addition, the proposed shift register is used to design an optimized LFSR circuit in QCA nanotechnology with only 157 cells and 0.2 µm2 area.

A combined experimental and computational study on peptide nucleic acid (PNA) analogues of tumor suppressive miRNA-34a

MicroRNAs are a ubiquitous class of non-coding RNAs able to regulate gene expression in diverse biological processes. Widespread miRNAs deregulation was reported in numerous diseases including cancer, with several miRNAs playing oncogenic and/or tumor suppressive role by targeting multiple mRNAs simultaneously. Based on these findings, miRNAs have emerged as promising therapeutic tools for cancer treatment. Herein, for the first time, peptide nucleic acids (PNAs) were studied to develop a new class of molecules able to target 3′UTR on MYCN mRNA without a fully complementary base pairing sequence (as miRNAs). For our proof of concept study we have selected as a model the miRNA-34a, which acts as a tumor suppressor in a number of cancers including neuroblastoma. In particular, miRNA-34a is a direct regulator of MYCN oncogene, whose overexpression is a prominent biomarker for the highly aggressive neuroblastoma phenotype. The design and synthesis of three PNA-based oligomers of different length was described, and their interaction with two binding sites on the target MYCN mRNA was investigated by molecular dynamics simulation, and spectroscopic techniques (CD, UV). Intake assay and confocal microscopy of PNA sequences were also carried out in vitro on neuroblastoma Kelly cells. Despite the presence of multiple mismatches, the PNA/RNA hetero duplexes retain very interesting features in terms of stability, affinity as well as of cellular uptake.

Continuous Hydrothermal Liquefaction of Biomass: A Critical Review

Hydrothermal liquefaction (HTL) of biomass is emerging as an effective technology to efficiently valorize different types of (wet) biomass feedstocks, ranging from lignocellulosics to algae and organic wastes. Significant research into HTL has been conducted in batch systems, which has provided a fundamental understanding of the different process conditions and the behavior of different biomass. The next step towards continuous plants, which are prerequisites for an industrial implementation of the process, has been significantly less explored. In order to facilitate a more focused future development, this review—based on the sources available in the open literature—intends to present the state of the art in the field of continuous HTL as well as to suggest means of interpretation of data from such plants. This contributes to a more holistic understanding of causes and effects, aiding next generation designs as well as pinpointing research focus. Additionally, the documented experiences in upgrading by catalytic hydrotreating are reported. The study reveals some interesting features in terms of energy densification versus the yield of different classes of feedstocks, indicating that some global limitations exist irrespective of processing implementations. Finally, techno-economic considerations, observations and remarks for future studies are presented.

Comparative study of three types of controllers for DFIG in wind energy conversion system

This paper presents an enhanced control strategy for Wind Energy Conversion System (WECS) using Doubly-Fed Induction Generator (DFIG). A robust Super-Twisting (STW) sliding mode control for variable speed wind turbine is developed to produce the optimal aerodynamic torque and improve the dynamic performance of the WECS. The electromagnetic torque of the DFIG is directly tracked using the proposed control to achieve maximum power extraction. The performance and the effectiveness of the STW control strategy are compared to conventional Sliding Mode (SM) and Proportional-Integral (PI) controllers. The proposed STW algorithm shows interesting features in terms of chattering reduction, finite convergence time and robustness against parameters variations and system disturbances.

Preparation of drug-loaded small unilamellar liposomes and evaluation of their potential for the treatment of chronic respiratory diseases

The aim of the present investigation was to evaluate the influence of liposome formulation on the ability of vesicles to penetrate a pathological mucus model obtained from COPD affected patients in order to assess the potential of such vesicles for the treatment of chronic respiratory diseases by inhalation. Therefore, Small Unilamellar Liposomes (PLAIN-LIPOSOMEs), Pluronic® F127-surface modified liposomes (PF-LIPOSOMEs) and PEG 2000PE-surface modified liposomes (PEG-LIPOSOMEs) were prepared using the micelle-to-vesicle transition (MVT) method and beclomethasone dipropionate (BDP) as model drug. The obtained liposomes showed diameters in the range of 40–65 nm, PDI values between 0.25 and 0.30 and surface electric charge essentially close to zero. The encapsulation efficiency was found to be dependent on the BDP/lipid ratio used and, furthermore, BDP-loaded liposomes were stable in size both at 37 °C and at 4 °C. All liposomes were not cytotoxic on H441 cell line as assessed by the MTT assay. The liposome uptake was evaluated through a cytofluorimetric assay that showed a non-significant reduction in the internalization of PEG-LIPOSOMEs as compared with PLAIN-LIPOSOMEs. The penetration studies of mucus from COPD patients showed that the PEG-LIPOSOMEs were the most mucus-penetrating vesicles after 27 h. In addition, PEG- and PF-LIPOSOMEs did not cause any effect on bronchoalveolar lavage fluid proteins after aerosol administration in the mouse. The results highlight that PEG-LIPOSOMEs show the most interesting features in terms of penetration through the pathologic sputum, uptake by airway epithelial cells and safety profile.

Three-dimensional modeling in the Weymouth Fore River

The Weymouth Fore River in Eastern Massachusetts is an estuary that presents an interesting example of a constrained environment. The river bank, of course, channels the energy. Man-made features such as the Fore River Bridge, several piers, and the USS Salem (a heavy cruiser) also present interesting features in terms of the sound propagation. We are using this site as the first of several to validate acoustic modeling tools in such constrained spaces. A detailed bathymetric survey was done providing centimeter level resolution using the Woods Hole Jetyaks. The environmental information is the input to a three-dimensional beam tracing model. This talk will present preliminary comparisons of the measured and modeled acoustic data.The Weymouth Fore River in Eastern Massachusetts is an estuary that presents an interesting example of a constrained environment. The river bank, of course, channels the energy. Man-made features such as the Fore River Bridge, several piers, and the USS Salem (a heavy cruiser) also present interesting features in terms of the sound propagation. We are using this site as the first of several to validate acoustic modeling tools in such constrained spaces. A detailed bathymetric survey was done providing centimeter level resolution using the Woods Hole Jetyaks. The environmental information is the input to a three-dimensional beam tracing model. This talk will present preliminary comparisons of the measured and modeled acoustic data.

A Simplified Microgrid Model for the Validation of Islanded Control Logics

Microgrids (MGs) may represent a solution in the near future to many problems in the energy and electric world scenarios; such as pollution, high reliability, efficiency and so on. In particular, MGs’ capability to work in an islanded configuration represents one of their most interesting features in terms of the improvement of the reliability of the system, the integration of renewable energy sources and the exploitation of the quick response and flexibility of power electronic devices in a stand-alone system. In order to study and validate innovative solutions and control strategies for islanded operation, there is a need to develop models for MG structures that can be reliable and sufficiently simple to be used for the purpose of the design and validation of innovative control systems. This paper proposes a simplified, first harmonic model for a generic structure of MG characterized by its use of only electronic power converter interfaced generation. The main advantages of the proposed method lie in the model’s simplicity and its reduced solving time, thanks to the limited number of necessary parameters to describe the system. Moreover, the developed formulation allows the avoidance of specific (and often licensed) software to simulate the system. The performances of the proposed model have been validated by means of a comparative analysis of the results obtained against a more accurate representation of the system performed in the power system CAD—electromagnetic transient and DC (PSCAD—EMTDC) environment, which allows for the representation of each component with a very high level of detail. Such comparison has been performed using the University of Genoa Savona Campus Smart Polygeneration Microgrid testbed facility, due to the availability of all the necessary numerical values.

A novel kinematic architecture for portable hand exoskeletons

Basing on strict requirements of portability, low cost and modularity, an assistive device for hand-opening impairment, characterized by an innovative mechanism, has been developed and tested by the authors. This robotic orthosis is designed to be a low-cost and portable hand exoskeleton to assist people with hand-opening impairment in their everyday lives. The mechanism has been especially studied for this kind of applications and presents some interesting features in terms of limited encumbrances and costs. Concerning the hand-opening impairment, the authors have also developed a methodology which, starting from the geometrical characteristics of the patient’s hand, properly defines the novel kinematic mechanism that better fits the finger trajectories. The authors have tested and validated the proposed approach by building a functional Hand Exoskeleton System (HES) prototype. The preliminary testing phase of the prototype with a single subject is concluded; currently, a group of subjects is testing the proposed HES methodology in collaboration with a rehabilitation center.

Improved Operation of SiC–BJT-Based Series Resonant Inverter With Optimized Base Drive

New semiconductor technology is enabling the design of more reliable and high performance power converters. In particular, silicon carbide (SiC) technology provides faster switching times, higher operating temperature, and higher blocking voltage. Among the new SiC devices, bipolar junction transistors (BJTs) present interesting features in terms of conduction and switching losses. However, one of the main drawbacks is that these devices have low gain, requiring high base current to activate them. As a consequence, the base drive circuit becomes more complex and the final efficiency is decreased. This letter presents an optimized base drive circuit for a zero-voltage switching series resonant inverter. The proposed circuit maximizes the driver efficiency and minimizes the driver current requirements. Moreover, the proposed circuit optimizes the power converter switching conditions, increasing the converter efficiency. The proposed base drive circuit has been tested with a SiC-BJT-based series resonant inverter applied to induction heating.

Analysis and implementation of a modular isolated zero‐voltage switching bidirectional dc–dc converter

A new topology of modular isolated bidirectional dc-dc converter is proposed. The proposed modular converter has interesting features in terms of low switching losses, bidirectional power flow and less number of switching device. In comparison with similar topologies, the reduction in the switching device number does not decrease the proposed converter power rating. Also, the simple modular structure, high-frequency operation, zero-voltage switching (ZVS) capability and less number of switching device make the extended configuration of the proposed converter suitable for high-power applications. The ZVS capability without using any auxiliary circuit is one of the most important specifications of the proposed converter. The design of the proposed converter, based on the connection of basic modules, is described and the steady-state operation analysis is presented. The ZVS of the proposed converter both in turn-on and turn-off instants are studied and their criteria are derived in detail. The simulation and measurement results are presented to verify the effectiveness of the proposed converter.

Complementary Germanium Electron–Hole Bilayer Tunnel FET for Sub-0.5-V Operation

In this letter, we present a novel device, the germanium electron-hole (EH) bilayer tunnel field-effect transistor, which exploits carrier tunneling through a bias-induced EH bilayer. The proposed architecture provides a quasi-ideal alignment between the tunneling path and the electric field controlled by the gate. The device principle and performances are studied by 2-D numerical simulations. This device allows interesting features in terms of low operating voltage (<; 0.5 V), due to its super-steep subthreshold slope (SSAVG ~ 13 mV/dec over six decades of current), ION/IOFF ratio of ~ 109, and drive current of ION ~ 10 μA/μm at VDD = 0.5 V. The same structure with symmetric voltages can be used to achieve a p-type device with ION and IOFF levels comparable to the n-type, which enables a straightforward implementation of complementary logic that could theoretically reach a maximum operating frequency of 1.39 GHz when VDD = 0.25 V.

Innovative design of hollow polymeric microneedles for transdermal drug delivery

Hypodermic injections give the best results in terms of drug administration efficiency, but benefit from a negative image among patients due to the fear of pain linked to needles. Transdermal drug delivery (TDD) has thus been greatly developed in the past ten years in order to be able to by-pass the skin protective layers in a minimally invasive way. With the advent of micro electro mechanical systems, opportunities have appeared, particularly in the area of microneedles. In this paper we present a new design of hollow polymeric microneedles aimed at being used for TDD by allowing injection of a liquid in the non-innerve part of the dermis. The design has been studied in order to be able to manufacture these microneedles arrays using techniques that may be applicable to industrial production at low cost. The envisioned microfabrication processes and their stacking are presented which involve injection micromolding and excimer laser ablation. Microneedles are also numerically characterized in terms of mechanics and microfluidics showing that the design also involves interesting features in terms of needles resistance and microfluidic. Due to the innovative double-molding technique, the micro-needles are indeed emptied leaving a cavity. An outlet channel on the side of the needle allows fluid flowing out of the needles. The characteristics of this outlet channel contribute to flow homogenization when several needles are placed in an array pattern. This microneedle design thus combines interesting characteristics in terms of ease of fabrication at large scale, mechanical resistance and fluid dynamics.

Numerical Simulations of a 4H-SiC BMFET Power Transistor with Normally-Off Characteristics

A numerical simulation study focused on an oxide-free 4H-SiC power device that is based on a normally-off Bipolar Mode Field Effect Transistor (BMFET) structure, and therefore on the principle of conductivity modulation from minority carrier injection, is presented. Starting from a n-/n+ 4H-SiC epi-wafer, with an epitaxial layer thickness of a few microns, and considering the presently available 4H-SiC ion implantation technology, a completely planar SiC-based BMFET has been designed. Such a device has interesting features in terms of static forward and blocking I V characteristics for high power applications. The 4H-SiC fundamental physical models, such as the doping incomplete ionization and the carrier recombination processes, were taken into account during the simulations.

The Lament over the River Nile—Isaiah xix 5-10 in Its Wider Context

AbstractThe 'Lament over the River Nile' in Isaiah xix 5-10 has attracted little interest from scholars yet demonstrates some interesting features in terms of poetic form and structure as well as its relationship to the larger unit of Isaiah xix 1-15. Comparison with ancient Egyptian prophecy suggests that this larger section is a unity and draws heavily on the author's awareness of Egyptian geography and culture. In the lament itself, the author uses various forms of parallelism in order to emphasise the effect of the drought, and in so doing to highlight the superiority of YHWH over the gods of Egypt.

A Current-Mode Power Sigma–Delta Modulator for Audio Applications

Linear and switching techniques are currently adopted to implement current-mode power stages. Pulsewidth modulation (PWM) is usually employed with the switching technique for both industrial and audio applications. In this paper, the Sigma-Delta modulation is considered as an alternative to the PWM in devising a switching current-mode power stage suitable for audio amplification. The proposed modulator is analyzed and simulated. The whole system was realized on an experimental breadboard. The results carried out on the prototype are reported and discussed. The electrical characterization presents interesting features in terms of linearity, noise, and power efficiency.

Compact dual-profile corrugated circular waveguide horn

A new type of corrugated horn is presented. It is designed to have a dual-profile corrugation, yielding a more compact structure with respect to standard linear or sinusoidal profiled horns. It is also shown that the new design has some interesting features in terms of the phase centre location and its level of variation over the operating bandwidth.