Modelling and Characterization of Planar Components

2014 ◽  
Vol 1025-1026 ◽  
pp. 1055-1061 ◽  
Author(s):  
M. Ourabia
Keyword(s):  
Numerical Simulation ◽  
Integral Method ◽  
Building Blocks ◽  
Scattering Matrix ◽  
New Method ◽  
Contour Integral ◽  
Mode Matching ◽  
Wide Range ◽  
Matching Techniques

An approach for modeling and numerical simulation of planar components using the edge line concept is developed. With this method, we develop an efficient modeling technique for microstrip discontinuities. The structure presents an arbitrary number of ports, each one with different orientation and dimensions. This article presents a hybrid method based on multimode contour integral and mode matching techniques. The process is based on segmentation and dividing the structure into key building blocks. We use the multimode contour integral method to analyze the blocks including irregular shape discontinuities. Finally, the multimode scattering matrix of the whole structure can be found by cascading the blocks. Therefore, the new method is suitable for analysis of a wide range of waveguide problems. Therefore the present approach can be applied easily to the analysis of any multiport junctions and cascade blocks. The accuracy of the method is validated comparing with results for several complex problems found in the literature. CPU times are also included showing the efficiency of the new method proposed.

scholarly journals Meso-Scale Digital Materials: Modular, Reconfigurable, Lattice-Based Structures

2016 ◽  
Author(s):  
Benjamin Jenett ◽  
Daniel Cellucci ◽  
Christine Gregg ◽  
Kenneth Cheung
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Building Blocks ◽  
Simplified Approach ◽  
Large Structures ◽  
Reconfigurable System ◽  
Structural Applications ◽  
Meso Scale ◽  
Good Agreement

We present a modular, reconfigurable system for building large structures. This system uses discrete lattice elements, called digital materials, to reversibly assemble ultralight structures that are 99.7% air and yet maintain sufficient specific stiffness for a variety of structural applications and loading scenarios. Design, manufacturing, and characterization of modular building blocks are described, including struts, nodes, joints, and build strategies. Simple case studies are shown using the same building blocks in three different scenarios: a bridge, a boat, and a shelter. Field implementation and demonstration is supplemented by experimental data and numerical simulation. A simplified approach for analyzing these structures is presented which shows good agreement with experimental results.

NUMERICAL SIMULATION OF EXTRACTING MODAL BACK-SCATTERING MATRIX FROM REVERBERATION IN SHALLOW-WATER WAVEGUIDE

2005 ◽  
Vol 13 (02) ◽  
pp. 279-285 ◽  
Author(s):  
LINHUI PENG ◽  
NING WANG ◽  
ER CHANG SHANG
Keyword(s):  
Numerical Simulation ◽  
Shallow Water ◽  
A Priori ◽  
Scattering Matrix ◽  
New Method ◽  
Source Depth ◽  
Back Scattering

Modal back-scattering matrix is the key component for reverberation predicting and also important for understanding the mechanism of bottom back-scattering. To extract the modal back-scattering matrix from reverberation data is a challening topic. So far, inversion of modal back-scattering matrix from reverberation data is based on some a priori assumptions. A new method for extracting modal back-scattering matrix from reverberation data in shallow-water waveguide is proposed recently [Shang et al., 2002]. In this paper numerical simulation of extracting the modal back-scattering matrix has been performed, it is shown that the inversion by changing the source depth works very well for lower frequency. Alternatively, the inversion by using the reverberation data at different ranges is proposed and it is shown that this approach is suitable on certain conditions.

scholarly journals Discovery and Characterization of a 5-Hydroxymethylfurfural Oxidase from Methylovorus sp. Strain MP688

2013 ◽  
Vol 80 (3) ◽  
pp. 1082-1090 ◽  
Author(s):  
Willem P. Dijkman ◽  
Marco W. Fraaije
Keyword(s):  
Building Blocks ◽  
Degradation Pathway ◽  
Enzyme Characterization ◽  
Bacterial Degradation ◽  
Primary Alcohols ◽  
Content Type ◽  
Wide Range ◽  
Furandicarboxylic Acid ◽  
Ph Range

ABSTRACTIn the search for useful and renewable chemical building blocks, 5-hydroxymethylfurfural (HMF) has emerged as a very promising candidate, as it can be prepared from sugars. HMF can be oxidized to 2,5-furandicarboxylic acid (FDCA), which is used as a substitute for petroleum-based terephthalate in polymer production. On the basis of a recently identified bacterial degradation pathway for HMF, candidate genes responsible for selective HMF oxidation have been identified. Heterologous expression of a protein fromMethylovorussp. strain MP688 inEscherichia coliand subsequent enzyme characterization showed that the respective gene indeed encodes an efficient HMF oxidase (HMFO). HMFO is a flavin adenine dinucleotide-containing oxidase and belongs to the glucose-methanol-choline-type flavoprotein oxidase family. Intriguingly, the activity of HMFO is not restricted to HMF, as it is active with a wide range of aromatic primary alcohols and aldehydes. The enzyme was shown to be relatively thermostable and active over a broad pH range. This makes HMFO a promising oxidative biocatalyst that can be used for the production of FDCA from HMF, a reaction involving both alcohol and aldehyde oxidations.

Factors Affecting Molecular Self-Assembly and Its Mechanism

2012 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Hueyling Tan
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
Molecular Engineering ◽  
Molecular Structures ◽  
Polymer Science ◽  
New Approach ◽  
Factors Affecting ◽  
Dna Structures ◽  
Self Assembling ◽  
Wide Range

Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use ofpeptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study ofbiological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries ofexisting disciplines. Many self-assembling systems are rangefrom bi- andtri-block copolymers to DNA structures as well as simple and complex proteins andpeptides. The ultimate goal is to harness molecular self-assembly such that design andcontrol ofbottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes oflife and non-life science applications. Such aspirations can be achievedthrough understanding thefundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.

Stereospecific, Palladium-catalyzed C(sp3)–H Alkenylation and Alkynylation of a Proline Derivative Enabled by 8-Aminoquinoline as a Directing Group

2020 ◽  
Author(s):  
Aleksandra Balliu ◽  
Aaltje Roelofje Femmigje Strijker ◽  
Michael Oschmann ◽  
Monireh Pourghasemi Lati ◽  
Oscar Verho
Keyword(s):  
Carboxylic Acid ◽  
Building Blocks ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
High Yields ◽  
Vinyl Iodides ◽  
Initial Results

<p>In this preprint, we present our initial results concerning a stereospecific Pd-catalyzed protocol for the C3 alkenylation and alkynylation of a proline derivative carrying the well utilized 8‑aminoquinoline directing group. Efficient C–H alkenylation was achieved with a wide range of vinyl iodides bearing different aliphatic, aromatic and heteroaromatic substituents, to furnish the corresponding C3 alkenylated products in good to high yields. In addition, we were able show that this protocol can also be used to install an alkynyl group into the pyrrolidine scaffold, when a TIPS-protected alkynyl bromide was used as the reaction partner. Furthermore, two different methods for the removal of the 8-aminoquinoline auxiliary are reported, which can enable access to both <i>cis</i>- and <i>trans</i>-configured carboxylic acid building blocks from the C–H alkenylation products.</p>

Efficient Prediction of Structural and Electronic Properties of Hybrid 2D Materials Using DFT and Machine Learning

2018 ◽  
Author(s):  
Sherif Tawfik ◽  
Olexandr Isayev ◽  
Catherine Stampfl ◽  
Joseph Shapter ◽  
David Winkler ◽  
...  
Keyword(s):  
Machine Learning ◽  
Band Gap ◽  
Density Functional ◽  
2D Materials ◽  
Van Der Waals ◽  
Building Blocks ◽  
Machine Learning Techniques ◽  
Interlayer Distance ◽  
Computational Screening ◽  
Wide Range

Materials constructed from different van der Waals two-dimensional (2D) heterostructures offer a wide range of benefits, but these systems have been little studied because of their experimental and computational complextiy, and because of the very large number of possible combinations of 2D building blocks. The simulation of the interface between two different 2D materials is computationally challenging due to the lattice mismatch problem, which sometimes necessitates the creation of very large simulation cells for performing density-functional theory (DFT) calculations. Here we use a combination of DFT, linear regression and machine learning techniques in order to rapidly determine the interlayer distance between two different 2D heterostructures that are stacked in a bilayer heterostructure, as well as the band gap of the bilayer. Our work provides an excellent proof of concept by quickly and accurately predicting a structural property (the interlayer distance) and an electronic property (the band gap) for a large number of hybrid 2D materials. This work paves the way for rapid computational screening of the vast parameter space of van der Waals heterostructures to identify new hybrid materials with useful and interesting properties.

Directed, Palladium(II)-Catalyzed Enantioselective anti-Carboboration of Alkenyl Carbonyl Compounds

2019 ◽  
Author(s):  
Zhen Liu ◽  
Xiaohan Li ◽  
Tian Zeng ◽  
Keary Engle
Keyword(s):  
Carbonyl Compounds ◽  
Building Blocks ◽  
New Method ◽  
Carbon Based

A substrate-directed enantioselective <i>anti</i>-carboboration reaction of alkenes has been developed, wherein a carbon based nucleophile and a boron moiety are installed across the C=C bond through a 5- or 6-membered palladacycle intermediate. The reaction is promoted by a palladium(II) catalyst and a mondentate oxzazoline ligand. A range of enantioenriched secondary alkylboronate products were obtained with moderate to high enantioselectivity that could be further upgraded by recrystallization. This work represents a new method to synthesize versatile and valuable alkylboronate building blocks. Building on an earlier mechanistic proposal by Peng, He, and Chen, a revised model is proposed to account for the stereoconvergent nature of this transformation.

Software system for numerical simulation of broadband laser gas analysis of the atmosphere

2018 ◽  
pp. 66-73 ◽  
Author(s):  
S. A. Sadovnikov
Keyword(s):  
Numerical Simulation ◽  
Laser Radiation ◽  
Gas Analysis ◽  
Modular System ◽  
Software System ◽  
Transmission Spectra ◽  
Molecular Absorption ◽  
Molecular Scattering ◽  
Atmospheric Transmission ◽  
Wide Range

Introduction: Successful monitoring of environmental parameters requires the development of flexible software complexes with evolvable calculation functionality. Purpose: Developing a modular system for numerical simulation of atmospheric laser gas analysis. Results: Based on differential absorption method, a software system has been developed which provides the calculation of molecular absorption cross-sections, molecular absorption coefficients, atmospheric transmission spectra, and lidar signals. Absorption line contours are calculated using the Voigt profile. The prior information sources are HITRAN spectroscopic databases and statistical models of the distribution of temperature, pressure and gas components in the atmosphere. For modeling lidar signals, software blocks of calculating the molecular scattering coefficient and aerosol absorption/scattering coefficients were developed. For testing the applicability of various laser sources in the problems of environmental monitoring of the atmosphere, a concentration reconstruction error calculation block was developed for the atmospheric gas components, ignoring the interfering absorption of laser radiation by foreign gases. To verify the correct functioning of the software, a program block was developed for comparing the results of the modeling of atmospheric absorption and transmission spectra by using the standard SPECTRA information system. The discrepancy between the calculation of the atmospheric transmission spectra obtained using the developed system as compared to the SPECTRA results is less than 1%. Thus, a set of the presented program blocks allows you to carry out complex modeling of remote atmospheric gas analysis. Practical relevance: The software complex allows you to rapidly assess the possibilities of using a wide range of laser radiation sources for the problems of remote gas analysis.

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