414 research outputs found
An Investigation of Aural Space inside Mousa Broch by Observation and Analysis of Sound and Light
No full textThis project emphasises the unique character and construction of Mousa broch, questions the model of Mousa broch as a roofed home (an interpretation adopted by Historic Scotland in 2002) and considers the way in which sound and light informs our understanding of the spaces contained within its structure. Underpinning the approach to data collection was the architectural concept of aural space. The author attempts to convey an impression of aural space inside Mousa broch by the creation of an audio-visual record supported by acoustic analysis, archaeological discussion, and an architectural breakdown of the spaces within the broch structure. Audio recordings, sound samples, photographs and movies were made on Mousa island and inside Mousa broch during the period of the Summer solstice of 2009
Author Correction: the Influence of Nano Filter Elements on Pressure Drop and Pollutant Elimination Efficiency in Town Border Stations
No full textThe original version of this Article contained an error in the order of the author names, which was incorrectly given as Hamed Ebadiyan, Saeed Zeinali Heris, Seyed Borhan Mousavi, Shamin Hosseini Nami ; Mousa Mohammadpourfard. Consequently, in the Author Contributions section, “H.E. Investigation. S.Z.H. Supervision, Conceptualization, Methodology, Validation. S.B.M. Formal analysis, Writing original draft. S.H.N. Formal analysis, Writing original draft. M.M. Validation.” now reads: “S.Z.H. Supervision, Conceptualization, Methodology, Validation. H.E. Investigation. S.B.M. Formal analysis, Writing original draft. S.H.N. Formal analysis, Writing original draft. M.M. Validation.” The original Article has been corrected. © 2023, The Author(s)
SYNTHESIS OF C-GLYCOSYL AMINO ACIDS AS STABLE BUILDING BLOCKS FOR MODIFIED GLYCOPEPTIDE SYNTHESIS
No full textIn this thesis, we have studied and synthesized new class of C-glycosly amino acids whose structure features a
hetrocycle ring holding the carbohydrate and the amino acid fragments. Pyridine and tetrazole rings were used as
hetrocycle linkers in this project. This class of C-glycosyl amino acids is of interest as new chealtors and as building
building blocks for cotranslational glycopeptides synthesis. In the first part, C-Glycosylmethyl pyridylalanines were
synthesized via thermally induced Hantzsch-type cyclocondensation using an aldehyde-ketoester-enamino ester system.
To one of these reagents was attached a C-glycosyl residue, while to another was bound an amino acid fragment. In a
one-pot optimized methodology, the dihydropyridine was not isolated while its purification was carried out by removal
of unreacted material and side products using polymer-supported scavengers. Then the dihydropyridine (mixture of
diastereoisomers) was oxidized by a polymer-bound oxidant to give the target pyridine bearing the two bioactive
residues. In this way, a range of eight compounds (58-68% yield) was prepared in which the elements of diversity were
(i) the gluco and galacto configurations of the pyranose ring, (ii) the α- and β-configurations at the anomeric center, and
(iii) the positions of the carbohydrate and amino acid sectors in the pyridine ring. The orthogonal functional group
protection in these amino acids allowed their easy incorporation into oligopeptides via sequential amino and carboxylic
group coupling.
In the second part, tetrazole moiety was constructed via Huisgen 1,3-dipolar cycloaddition between nitriles and organic
azides. Two sets of compounds have been prepared, one being constituted of C-galactosyl and C-ribosyl O-tetrazolyl
serines, while the other contains S-tetrazolyl cysteine derivatives. In both cases, the synthetic scheme involved a twostep
route: the first one being the thermal cycloaddition of a sugar azide with p-toluensulfonyl cyanide (TsCN) to give a
1-substituted 5-sulfonyl tetrazole and the second the replacement of the tosyl group with a serine or cysteine residue.
For the high efficiency and operational simplicity, the azide-TsCN cycloaddition appears to be a true click process.
Finally, one of the amino acids prepared was incorporated into a tripeptid
Lyapunov-Based Model Predictive Control for Stable Operation of a 9-Level Crossover Switches Cell Inverter in Grid Connection Mode
No full textThis study proposes the application of a Lyapunov-based Model Predictive Control (L-MPC) approach to a 9-level Crossover Switches Cell (CSC9) converter operating in grid connection mode. The proposed method utilizes the structure of the classical finite-control-set MPC (FCS-MPC) technique while integrating a cost function that requires no tuning. By deriving the cost function based on Lyapunov theory, the system stability is ensured. Notably, the suggested approach offers several advantages over traditional MPC controllers. Firstly, it eliminates the need for gain tuning, thereby simplifying the implementation process. Secondly, the proposed controller prioritizes stability as a key design aspect. The presented simulation results prove that the proposed controller effectively regulates the voltage of the DC capacitor around its desired value and feed a smooth sinusoidal current to the grid with low total harmonic distortion (THD) while operating at a unity power factor.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.DC systems, Energy conversion & Storag
The Role of Nanoparticle Shapes and Structures in Material Characterisation of Polyvinyl Alcohol (PVA) Bionanocomposite Films
No full textThree different types of nanoparticles, 1D Cloisite 30B clay nanoplatelets, 2D halloysite nanotubes (HNTs), and 3D nanobamboo charcoals (NBCs) were employed to investigate the impact of nanoparticle shapes and structures on the material performance of polyvinyl alcohol (PVA) bionanocomposite films in terms of their mechanical and thermal properties, morphological structures, and nanomechanical behaviour. The overall results revealed the superior reinforcement efficiency of NBCs to Cloisite 30B clays and HNTs, owing to their typical porous structures to actively interact with PVA matrices in the combined formation of strong mechanical and hydrogen bondings. Three-dimensional NBCs also achieved better nanoparticle dispersibility when compared with 1D Cloisite 30B clays and 2D HNTs along with higher thermal stability, which was attributed to their larger interfacial regions when characterised for the nanomechanical behaviour of corresponding bionanocomposite films. Our study offers an insightful guidance to the appropriate selection of nanoparticles as effective reinforcements and the further sophisticated design of bionanocomposite materials
Towards Sophisticated 3D Interphase Modelling of Advanced Bionanocomposites via Atomic Force Microscopy
No full textNanomechanical properties and interphase dimensions of PVA bionanocomposites reinforced with halloysite nanotubes (HNTs)
and Cloisite 30B montmorillonite (MMT) were evaluated by means of peak force quantitative nanomechanical mapping
(PFQNM). A three-phase theoretical composite model was established based on hard-core–soft-shell structures consisting of
hard mono-/polydispersed anisotropic particles and soft interphase and matrices. Halpin-Tsai model and Mori-Tanaka model
were employed to predict experimentally determined tensile moduli of PVA bionanocomposites where effective volume fraction
of randomly oriented nanoparticles resulted from the inclusion of interphase properties and volume fractions. Overall, it was
suggested that the estimation of elastic modulus according to effective volume fraction of nanoparticles revealed better
agreement with experimental data as opposed to that based upon their nominal volume fraction. In particular, the use of
polydispersed HNTs and Cloisite 30B MMT clays with Fuller particulate gradation was proven to yield the best prediction when
compared with experimental data among all proposed theoretical models. This study overcomes the neglected real interphase
characteristics in modelling nanocomposite materials with much more accurate estimation of their mechanical properties
A benchmark study of the multiscale and homogenization methods for fully implicit multiphase flow simulations
No full textAccurate simulation of multiphase flow in subsurface formations is challenging, as the formations span large length scales (km) with high-resolution heterogeneous properties. To deal with this challenge, different multiscale methods have been developed. Such methods construct coarse-scale systems, based on a given high-resolution fine-scale system. Furthermore, they are amenable to parallel computing and allow for a-posteriori error control. The multiscale methods differ from each other in the way the transition between the different scales is made. Multiscale (finite element and finite volume) methods compute local basis functions to map the solutions (e.g. pressure) between coarse and fine scales. Instead, homogenization methods solve local periodic problems to determine effective models and parameters (e.g. permeability) at a coarser scale. It is yet unknown how these two methods compare with each other, especially when applied to complex geological formations, with no clear scale separation in the property fields. This paper develops the first comparison benchmark study of these two methods and extends their applicability to fully implicit simulations using the algebraic dynamic multilevel (ADM) method. At each time step, on the given fine-scale mesh and based on an error analysis, the fully implicit system is solved on a dynamic multilevel grid. The entries of this system are obtained by using multiscale local basis functions (ADM-MS), and, respectively, by homogenization over local domains (ADM-HO). Both sets of local basis functions (ADM-MS) and local effective parameters (ADM-HO) are computed at the beginning of the simulation, with no further updates during the multiphase flow simulation. The two methods are extended and implemented in the same open-source DARSim2 simulator (https://gitlab.com/darsim2simulator), to provide fair quality comparisons. The results reveal insightful understanding of the two approaches, and qualitatively benchmark their performance. It is re-emphasized that the test cases considered here include permeability fields with no clear scale separation. The development of this paper sheds new lights on advanced multiscale methods for simulation of coupled processes in porous media.Reservoir EngineeringNumerical Analysi
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