scholarly journals Indirect Reconstruction of Structural Responses Based on Transmissibility Concept and Matrix Regularization

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Chudong Pan ◽  
Liwen Zhang ◽  
Zhuo Sun
Keyword(s):  
Initial Conditions ◽  
Time Windows ◽  
Experimental Studies ◽  
Physical Sensors ◽  
Norm Values ◽  
The Matrix ◽  
Structural Responses ◽  
Novel Method ◽  
Matrix Regularization ◽  
Critical Locations

A novel method is proposed based on the transmissibility concept and matrix regularization for indirectly measuring the structural responses. The inputs are some measured responses that are obtained via physical sensors. The outputs are the structural responses corresponding to some critical locations where no physical sensors are installed. Firstly, the transmissibility concept is introduced for expressing the relationship between the measured responses and the indirectly measured ones. Herein, a transmissibility matrix is formulated according to the theory of force identification under unknown initial conditions. Then, in order to reduce the size of the transmissibility matrix, structural responses are reshaped in a form of a matrix by using the concept of moving time windows. According to the matrix form of input-output relationship, indirect reconstruction of responses is boiled down to an optimization equation. Since inverse problem may be ill-conditioned, matrix regularization such as F-norm regularization is then recommended for improving the optimization problem. Herein, the penalty function is defined by using a weighted sum of two F-norm values, which correspond to the estimated responses of physical sensors and the ones of the concerned critical locations, respectively. Numerical simulations and experimental studies are finally carried out for verifying the effectiveness and feasibility of the proposed method. Some results show that the proposed method can be applied for indirectly measuring the responses with good robustness.

Dispersion of a solute in a fully developed laminar tube flow

1970 ◽  
Vol 317 (1528) ◽  
pp. 91-99 ◽  
Keyword(s):  
Initial Conditions ◽  
Experimental Studies ◽  
Local Concentration ◽  
Eigenvalues And Eigenvectors ◽  
Transient Dispersion ◽  
The Matrix ◽  
Method Of Solution ◽  
Laminar Tube Flow ◽  
Diffusion Convection ◽  
Mean Concentration

The diffusion-convection equation, which is used to model the transient dispersion of a solute in a circular tube, has been solved by the linear combination of the eigenvalues and eigenvectors of the matrix form of the equation. The solution, which is valid for all time, gives the local concentration as well as the integrated mean concentration. The results compare well with other analytical and experimental studies in the region of common validity. Comparisons with numerical results show small discrepancies. The method of solution may be applied to similar problems with different boundary and initial conditions.

Computational studies of the mitochondrial carrier family SLC25. Present status and future perspectives

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Andrea Pasquadibisceglie ◽  
Fabio Polticelli
Keyword(s):  
Transport Mechanism ◽  
Experimental Studies ◽  
Intermembrane Space ◽  
Mitochondrial Carrier ◽  
Mitochondrial Homeostasis ◽  
The Matrix ◽  
Mitochondrial Carrier Family ◽  
Mitochondrial Intermembrane Space ◽  
Computational Analyses

Abstract The members of the mitochondrial carrier family, also known as solute carrier family 25 (SLC25), are transmembrane proteins involved in the translocation of a plethora of small molecules between the mitochondrial intermembrane space and the matrix. These transporters are characterized by three homologous domains structure and a transport mechanism that involves the transition between different conformations. Mutations in regions critical for these transporters’ function often cause several diseases, given the crucial role of these proteins in the mitochondrial homeostasis. Experimental studies can be problematic in the case of membrane proteins, in particular concerning the characterization of the structure–function relationships. For this reason, computational methods are often applied in order to develop new hypotheses or to support/explain experimental evidence. Here the computational analyses carried out on the SLC25 members are reviewed, describing the main techniques used and the outcome in terms of improved knowledge of the transport mechanism. Potential future applications on this protein family of more recent and advanced in silico methods are also suggested.

Graphite/UPE Nanocomposite: Transport, Thermal, Mechanical and Viscoelastic Properties

2019 ◽  
Vol 23 ◽  
pp. 201-212
Author(s):  
Shivkumari Panda ◽  
Dibakar Behera ◽  
Tapan Kumar Bastia
Keyword(s):  
Transport Properties ◽  
Unsaturated Polyester ◽  
Homogeneous Distribution ◽  
Thermo Gravimetric ◽  
New Class ◽  
The Matrix ◽  
Novel Method ◽  
Water Transport Properties ◽  
First Time

This chapter presents the preparation and characterization of some unique properties of nanocomposites by dispersing graphite flakes in commercial unsaturated polyester (UPE) matrix. The composite was prepared by a novel method with the use of solvent swelling technique. Three different specimens of UPE/graphite nanocomposites were fabricated with addition of 1, 2 and 3 wt% of graphite flakes. Except mechanical, viscoelastic and thermo gravimetric properties, transport properties like electrical conductivity, thermal conductivity and water transport properties were studied for the first time. Graphite flakes propose enhanced properties to the composites suggesting homogeneous distribution of the nanofiller in the matrix and strong interaction with the matrix. 2wt% nanofiller loading showed superior essential characteristics and after that the properties reduced may be due to the nucleating tendency of the nanofiller particles. The XRD pattern showed the compatibility of the graphite flakes by introducing a peak around 26.550 in the nanocomposites. SEM Properties are also in agreement with the compatibility. Nanocomposite with 2wt% graphite also showed remarkable enhancement in transport, mechanical, viscoelastic and thermo gravimetric properties. So by introduction of a small quantity of graphite endow the new class of multiphase nanocomposites with inimitable structure and tremendous application.

scholarly journals Theoretical and experimental studies of a gas stamping device with a piston pressure multiplier

2019 ◽  
Vol 18 (1) ◽  
pp. 163-173
Author(s):  
A. Yu. Botashev ◽  
R. A. Bayramukov
Keyword(s):  
Theoretical Analysis ◽  
Experimental Studies ◽  
Fuel Mixture ◽  
Small Scale ◽  
Scale Production ◽  
Pressure Treatment ◽  
Energy Of Combustion ◽  
Stamping Process ◽  
Pressure Multiplier ◽  
The Matrix

In many industries, the share of small-scale production plants is significant. In these conditions, compared with traditional methods of pressure treatment, pulse pressure treatment methods, one of the varieties of which is gas stamping, are more efficient. However, the known devices of gas stamping provide mainly stamping of thin-walled parts. To expand the technological capabilities of gas stamping, the authors developed a gas stamping device with a piston pressure multiplier, in which heating and deformation of the stamping workpiece is carried out using the energy of combustion of fuel mixtures in the combustion chamber, in the working cylinder and in the cavity of the matrix. This article is devoted to the study of the workflow of this device. Theoretical analysis of the workflow was carried out, and, as a result, a pattern was determined for the variation of the pressure that performs the stamping process in the working cylinder. In particular, it was found that at the final stage of the stamping process, due to the energy of combustion of the fuel mixture, the pressure in the working cylinder increases 1.5...2 times, which allows a significant increase in the thickness of the parts to be stamped. An experimental gas stamping device with a piston pressure multiplier was developed, and experimental studies were carried out. The studies confirmed the main results of the theoretical analysis: the discrepancy between the theoretical and experimental values of the degree of pressure multiplication in the working cylinder does not exceed 11%.

Tropylium Salt Promoted Hydroboration Reactions: Mechanistic Insights via Experimental and Computational Studies

2021 ◽  
Author(s):  
Nhan Nu Hong Ton ◽  
Binh Khanh Mai ◽  
Thanh Vinh Nguyen
Keyword(s):  
Dft Calculations ◽  
Lewis Acids ◽  
Experimental Studies ◽  
Cross Coupling ◽  
Computational Studies ◽  
Metal Free ◽  
Hydride Abstraction ◽  
Novel Method ◽  
Tropylium Salts

Abstract: Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross coupling chemistry. This type of reaction has traditionally been mediated by transition metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to efficiently promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic paradigm, which is triggered by a hydride abstraction of pinacolborane with tropylium ion. This is followed by a series of <i>in situ</i> counterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.

Micromechanical Analysis of Nonlinear Response of Unidirectional Composites: A Fundamental Approach

2001 ◽  
Author(s):  
Virendra R. Jadhav ◽  
Srinivasan Sridharan
Keyword(s):  
Mechanical Model ◽  
Nonlinear Response ◽  
Experimental Studies ◽  
Matrix Cracking ◽  
Type Model ◽  
Unidirectional Composites ◽  
The Matrix ◽  
Experimental Response ◽  
Square Cells ◽  
Experimental Comparisons

Abstract Micromechanical models with different representative volume elements have been developed to study their ability to predict nonlinear response of unidirectional composites. A simple, square cells type micro-mechanical model similar to those widely used by other researchers is compared with a more advanced 3-phase finite element based micro-mechanical model. The models utilize the “bulk” properties of the matrix without attempting to “tune” the model to fit with experimental response of laminae. This is a more fundamental approach and constitutes a departure from current practice. The models account for shear softening, matrix cracking and the presence of residual stresses. A smeared cracking approach was used to characterize the micro-cracking in matrix. Experimental studies were performed on laminae, laminates and cylinders made from carbon epoxy composites. Experimental comparisons show that the more accurate micro-mechanical model with proper partial cracking options provides good bounds on experimental response with consistent accuracy. A square cells type model however is not consistent in its predictions, thus raising questions about its applicability in any general micro-mechanics based analysis.

Entrainment and growth of vortical disturbances in the channel-entrance region

2021 ◽  
Vol 927 ◽  
Author(s):  
Pierre Ricco ◽  
Claudia Alvarenga
Keyword(s):  
Initial Conditions ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Analytical Description ◽  
Reynolds Numbers ◽  
Boundary Region ◽  
Shear Layers ◽  
Base Flow ◽  
Open Boundary ◽  
Classical Stability

The entrainment of free-stream unsteady three-dimensional vortical disturbances in the entry region of a channel is studied via matched asymptotic expansions and by numerical means. The interest is in flows at Reynolds numbers where experimental studies have documented the occurrence of intense transient growth, despite the flow being stable according to classical stability analysis. The analytical description of the vortical perturbations at the channel mouth reveals how the oncoming disturbances penetrate into the wall-attached shear layers and amplify downstream. The effects of the channel confinement, the streamwise pressure gradient and the viscous/inviscid interplay between the oncoming disturbances and the boundary-layer perturbations are discussed. The composite perturbation velocity profiles are employed as initial conditions for the unsteady boundary-region perturbation equations. At a short distance from the channel mouth, the disturbance flow is mostly confined within the shear layers and assumes the form of streamwise-elongated streaks, while farther downstream the viscous disturbances permeate the whole channel although the base flow is still mostly inviscid in the core. Symmetrical disturbances exhibit a more significant growth than anti-symmetrical disturbances, the latter maintaining a nearly constant amplitude for several channel heights downstream before growing transiently, a unique feature not reported in open boundary layers. The disturbances are more intense as the frequency decreases or the bulk Reynolds number increases. We compute the spanwise wavelengths that cause the most intense downstream growth and the threshold wall-normal wavelengths below which the perturbations are damped through viscous dissipation.

scholarly journals Hashing Based Answer Selection

2020 ◽  
Vol 34 (05) ◽  
pp. 9330-9337
Author(s):  
Dong Xu ◽  
Wu-Jun Li
Keyword(s):  
Question Answering ◽  
Matrix Representation ◽  
Matrix Representations ◽  
Binary Matrix ◽  
Large Memory ◽  
The Matrix ◽  
Novel Method ◽  
Online Prediction ◽  
Memory Cost ◽  
Vector Representations

Answer selection is an important subtask of question answering (QA), in which deep models usually achieve better performance than non-deep models. Most deep models adopt question-answer interaction mechanisms, such as attention, to get vector representations for answers. When these interaction based deep models are deployed for online prediction, the representations of all answers need to be recalculated for each question. This procedure is time-consuming for deep models with complex encoders like BERT which usually have better accuracy than simple encoders. One possible solution is to store the matrix representation (encoder output) of each answer in memory to avoid recalculation. But this will bring large memory cost. In this paper, we propose a novel method, called hashing based answer selection (HAS), to tackle this problem. HAS adopts a hashing strategy to learn a binary matrix representation for each answer, which can dramatically reduce the memory cost for storing the matrix representations of answers. Hence, HAS can adopt complex encoders like BERT in the model, but the online prediction of HAS is still fast with a low memory cost. Experimental results on three popular answer selection datasets show that HAS can outperform existing models to achieve state-of-the-art performance.

Efficient Multi-Scale Registration of 3D Reconstructions Based on Camera Center Constraint

2014 ◽  
Vol 998-999 ◽  
pp. 1018-1023
Author(s):  
Rui Bin Guo ◽  
Tao Guan ◽  
Dong Xiang Zhou ◽  
Ke Ju Peng ◽  
Wei Hong Fan
Keyword(s):  
Experimental Results ◽  
Cayley Transform ◽  
3D Reconstructions ◽  
Multi Scale ◽  
The Matrix ◽  
Novel Method ◽  
3D Scene ◽  
Coordinates Transformation

Recent approaches for reconstructing 3D scenes from image collections only produce single scene models. To build a unified scene model that contains multiple subsets, we present a novel method for registration of 3D scene reconstructions in different scales. It first normalizes the scales of the models building on similarity reconstruction by the constraint of the 3D position of shared cameras. Then we use Cayley transform to fit the matrix of coordinates transformation for the models in normalization scales. The experimental results show the effectiveness and scalability of the proposed approach.

Reproduction of Monopile Ringing Events in Reduced-Duration Model Tests

2017 ◽  
Author(s):  
Erin E. Bachynski ◽  
Trygve Kristiansen
Keyword(s):  
Time Windows ◽  
Full Scale ◽  
Offshore Wind ◽  
Maximum Deviation ◽  
Wave Loads ◽  
Traditional Practice ◽  
Hydrodynamic Loads ◽  
Offshore Wind Turbines ◽  
Irregular Wave ◽  
Structural Responses

Monopile support structures for offshore wind turbines may experience ringing-type responses in steep wave conditions. In order to experimentally capture the statistical distribution of the hydrodynamic loads and structural responses, traditional practice is to generate many 3-hour (full scale) realizations of the relevant sea states. An experimental campaign at 1:48 scale was carried out in the Lilletanken wave tank at NTNU/MARINTEK in order to examine the possibility of using shorter time windows to recreate irregular wave ringing events. Wave elevations and hydrodynamic loads on a rigid vertical circular cylinder in 27 m water depth were measured for a variety of 3-hour, 450 s (7.5-minute), 800 s (13.3-minute), 1150 s (19.2-minute), and 1500 s (25-minute) wave realizations, where all durations are listed in full scale. Wavelet transformations and a single degree-of-freedom oscillator were used to investigate the magnitude and repeatability of the high-frequency content of the wave loads. Large variations in the repeatability were seen among events. On average, the repeatability in the ringing response was 4.2 % for 3-hour tests, while 13.3-minute tests reproduced the same events within 9.1 %. The maximum deviation was, nonetheless, much higher when only 13.3 minutes were used.

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