Multi-layer Partition Research Articles

Basic research on layered geopolymer composites with insulating materials of natural origin

New restrictions on carbon dioxide emissions and electricity consumption are currently being introduced around the world. Innovative solutions are being adopted in many countries to reduce CO2 emissions and material and energy consumption. The present work is related to the study of innovative binders based on geopolymers for the production of layered building envelopes. The binders are reinforced with composite bars and containing fibers of natural origin. The natural materials used to produce the samples are completely biodegradable. A 10-mol sodium hydroxide solution with an aqueous solution of sodium silicate was used for alkaline activation of geopolymers. The purpose of the study was to compare and determine the insulating properties of natural fiber-based materials such as coconut mat, jute felt, hemp felt, flax felt, flax wool, hemp wool, flax-jute wool, and to determine the effect of these materials on geopolymer composites, in which 4 layers of natural insulating materials were used, and the composites were reinforced by fiberglass bars. The publication presents the results of physicochemical studies of geopolymerization precursors and natural insulating materials, studies of thermal properties of fibers, mats, felts and wools, morphology of fiber structure and texture, as well as physical and thermal properties of finished multi-layer partitions. The results indicate the great potential of these materials in prefabrication and structural-insulation applications. The fabricated composites using 4 layers of natural fibers showed improved thermal conductivity by as much as 40% (reduced thermal conductivity from 1.36 W/m × K to about 0.8 W/m × K). The work may have future applications in energy-saving and low-carbon construction.

Effect of Acoustic Enclosure on the Sound Transmission Loss of Multi-Layered Micro-Perforated Plates

This study presents an examination of the transmission properties of multilayered partitions made up of multiple micro-perforated plates (MPPs) coupled to acoustic enclosures with general impedance boundaries. Multi-layered MPPs can lower the transmission while minimizing reflection in the source and receiving enclosure. Previous research has mainly focused on the double MPPs or triple MPPs partition itself. However, it is vital to analyze the in-situ sound transmission loss of the multi-layered MPP and their efficiency in a complex vibro-acoustic environment. The case when the multilayered MPPs are coupled to a receiving enclosure or coupled to both a source and receiving enclosure is investigated. The objective is to provide an analytical method to evaluate the transmission properties of multilayered MPPs coupled to acoustic enclosures while being computationally more efficient than the finite element method (FEM). Using the modified Fourier series for the acoustic pressure, a variational form for the acoustic and structure medium yields a completely coupled vibroacoustic system. A comparison between the sound transmission loss of the double MPPs, when mounted on an impedance tube and coupled to acoustics enclosures, shows the modal effect of the enclosures. The effect of enclosure shape, impedance boundary, perforation ratio, air gap thickness on the sound transmission properties of the double MPPs structure is examined for both cases. Finally, in both situations, the performance of triple MPP structure insulation is evaluated.

Combining layered label correction and mixup supervised contrastive learning to learn noisy labels

Deep neural networks trained using standard cross-entropy loss often induce overfitting of noisy labels that degrades performance. Label correction and contrastive learning have been theoretically demonstrated to be mutually beneficial in noisy label learning. However, the fusion of these two modules in practice has not been researched adequately, and the influence of each module on performance improvement has not been clarified. In this paper, we propose an effective noisy label learning framework that combines layered label correction with mixup supervised contrastive learning, based on hierarchical clustering using first neighbor relations and mixup contrastive loss. In particular, the framework consists of two modules—Layered Label Correction (LLC) and Mixup Supervised Contrastive Loss (MSCL). The LLC module aggregates the first neighbor's soft labels via label propagation among multilayer partitions based on the hierarchical clustering of the feature representation. Its purpose is to capture the underlying structure of learning representations at different levels of granularity. The MSCL module incorporates pseudo-labels into mixup contrastive learning directly to learn class-related representations of all instances of each class. Ablation studies are conducted to evaluate the contribution of individual modules to the overall performance enhancement of the framework. Moreover, experiments on synthetic datasets comprising noise of various patterns and levels demonstrate that the proposed framework yields a superior classification accuracy in comparison with existing alternatives.

INVESTIGATION OF INFLUENCE OF FACTORS ON FIRE RESISTANCE OF PARTITIONS MADE OF SANDWICH PANELS

The authors describe the results of studies of thermal processes in partitions made of sandwich panels under one-sided influence of fire. Analysis of the thermal state of multilayer partitions with mineral wool plates and development of recommendations for the design of buildings from such structures is possible using the simulation of thermal processes that occur during fire exposure to the studied samples. There is a certain number of models of the thermal state of multilayer partitions with mineral wool plates of different levels of complexity and purpose. However, in these models there are parameters that are individual for each partition and are known with insufficient accuracy. The authors provided an improved mathematical model of heat conduction in partitions, the difference of which is the application of heat transfer coefficients from the unheated surface of the partition in boundary conditions. A comparison of the fire resistance limits for a partition made of a sandwich panel indicates a strong influence of the accuracy of setting the heat transfer coefficient on the dependence of the thickness of the partition on the fire resistance limit. The accuracy of the task of the heat transfer coefficient on the dependence of the thickness of the partition on the fire resistance limit was scientifically substantiated, which showed a strong influence of the boundary condition describing the processes of heat transfer on the surface of the partition, which is not heated, on the accuracy of determining the limits of fire resistance of the structure under study. The influence of the accuracy of the assignment of the coefficient of heat transfer from the object to the environment on the fire resistance of the investigated building structures, which during the test are subject to both natural (mobility) of air and forced blowing, as, for example, during tests of air ducts with fire protection, must be taken into account convectively radiation heat exchange, which will allow to obtain the most accurate result regarding the determination of their fire resistance characteristics. Keywords: fire-resistance, methodological support, parameters, modeling.

Optimization of space-constrained micro-perforated absorbers by causality criteria

The problem of space-constrained absorbers in the low frequency range constitutes an area of continuous research. Micro-perforated panels are advantageous because they can be tuned by a proper selection of their constitutive physical parameters including the diameter of the perforations and their separation distance, their thickness and the length of the backing cavity. However, such optimal selection is not straightforward, especially when considering multi-layer partitions. Current optimization algorithms are based on the maximization of the total absorption coefficient averaged over a frequency band, that requires a compromise between the bandwidth and the thickness of the control device. In this work, the problem is analysed on the basis of a causality criterion. This principle is generalized from its formulation in the field of electromagnetism to obtain a relation that correlates the thickness-to-bandwidth performance of a micro-perforated absorber to its total absorption coefficient. Using this relation, an optimization procedure is presented for the sequential selection of the optimal physical parameters for single-layer partitions. An excellent agreement has been found between the optimal values obtained by the causality criterion and those achieved by critical coupling conditions.

Enhanced modal matching method for perforated and micro-perforated partitions

Perforated multilayer partitions are widely used in many problems for the aerospace and automotive industries and air-conditioning systems. Combinations of macro and micro-perforated perforations across the constitutive partition layers can provide different physical mechanisms for diverse control strategies depending on the problem requirements. However, there is a lack of unified numerical or analytical description able to provide accurate results over a broad frequency range for a wide range of diameter perforations ranging from supra-millimetric to sub-millimetric apertures. Furthermore, most of them do not account for the beneficial effects on the partition dissipation of the in-hole non-planar modes, albeit evanescent. In this work, an enhanced modal matching (EMM) method is presented that accounts for in-hole high-order modes as well as visco-thermal boundary layer effects inside the holes and over the outer surfaces surrounding the holes. The analytical results have been compared against effective models, numerical models and impedance tube measurements. They show good agreement for single and multi-layer partitions within the corresponding bandwidths of validity. Parametric studies have concluded that the panel thickness-to-hole diameter ratio is a key factor that plays a crucial role on the prominence of the in-hole radial modes and outer visco-thermal effects in the dissipation properties.

Enhanced modal matching method for macro- and micro-perforated plates

Theoretical, numerical and experimental results are presented on the reactive and dissipative properties of backed or unbacked multilayer partitions made up of macro- or micro-perforated rigid panels in linear regime. The objective is to provide an enhanced multi-modal (EMM) formulation that accounts for high-order modes within the panel holes as well as visco-thermal boundary layers (VTBLs) over the panel surfaces while being computationally more efficient than the finite element method (FEM). The proposed model accounts for oblique incidence and finite-sized panel vibrations. Validation cases show that the EMM well captures the visco-thermal dissipation modelled by FEM on rigidly-backed macro- and micro-perforates. It also well correlates with a number of effective impedance models provided suitable end-corrections are used. The measured acoustical properties of unbacked multi-layer partitions are accurately predicted by the EMM, well beyond the validity range of the effective models. The thickness-to-hole diameter aspect ratio is found to be a key parameter that determines the relative contribution of the in-hole radial modes and VTBLs to the partition dissipation properties. For aspect ratios greater than unity where micro-perforates normally are operated, the dissipation is dominated by the high-order in-hole modes. Otherwise, both the VTBLs and in-hole modes contribute to the transmission and dissipation. The VTBLs also dominate the reactive and dissipative properties of acoustic fishnets embedding small air gaps comparable to the VTBL thickness. Despite the constant hole pitch limitation, the EMM appears to be well-suited for the optimisation study of the dissipative and reactive properties of backed or unbacked multi-layer partitions.

Graph simulation on large scale temporal graphs

Graph simulation is one of the most important queries in graph pattern matching, and it is being increasingly used in various applications, e.g., protein interaction networks, software plagiarism detection. Most previous studies mainly focused on the simulation problem on static graphs, which neglected the temporal factors in daily life. In this paper, we investigate a novel problem, namely, temporal bounded simulation on temporal graphs. Specifically, given a pattern query Q with bound constraint and a temporal graph G, we aim to find out the matches Q(G) of Q on G, such that Q(G) satisfies temporal reachability and bound constraint of Q. To tackle this problem efficiently, we propose a simulation matching framework, which consists of three phases, namely pattern segmentation, temporal bounded simulation of pattern segments, and result integration. We first divide the Q into simple small subgraphs (segments). We construct a temporal reachable tree of G. Based on the tree, we propose a basic matching algorithm for the pattern segments. Furthermore, we propose two optimization algorithms by leveraging multi-layer partition strategy to accelerate query processing. After that, we integrate the simulation results obtained from the pattern segments according to the constraints of temporal reachability and the bound of query pattern. Finally, we use real temporal and synthetic datasets to empirically verify the efficiency and effectiveness of our solutions for temporal bounded simulation matching.

Characterization of New Sustainable Acoustic Solutions in a Reduced Sized Transmission Chamber

In order to assess the airborne sound insulation of a new material or building solution, access to standardized laboratories, large and expensive facilities, and a sample area of at least 10 m2 are required. At the research and development stages of new sustainable acoustic materials for construction, it is not easy to make large sample areas available. Moreover, the financial investment in acoustic testing of materials during the research stage in standardized laboratories is excessive. In this work, the assessment of the airborne sound insulation of multi-layer partitions designed with new sustainable materials is presented. The assessed solutions are formed by green composite fiber boards as lightweight elements and a new material designed from sheep wool as absorbent material. The results of these 100% recyclable solutions are compared with lightweight element based solutions, which are commonly used for acoustic insulation. Characterization of those new sustainable solutions for building is leveraged in a reduced sized transmission chamber. The design, construction, and validation of this kind of laboratory are provided. This laboratory enables the assessment of the airborne sound insulation of a material in its research stage.

Exploring inside a shaggy aorta using non-obstructive angioscopy

A shaggy aorta is reportedly related to atheromatous embolisation, which causes serious ischaemic damage to various organs. However, its characteristics are poorly understood. Non-obstructive angioscopy (NOA) has been developed to...

Error Resilient for Multiview Video Transmissions with GOP Analysis

The work in this paper examines the effects of group of pictures on H.264 multiview video coding bitstream over an erroneous network with different error rates. The study considers analyzing the bitrate performance for different GOP and error rates to see the effects on the quality of the reconstructed multiview video. However, by analyzing the multiview video content it is possible to identify an optimum GOP size depending on the type of application used. In a comparison test, the H.264 data partitioning and the multi-layer data partitioning technique with different error rates and GOP are evaluated in terms of quality perception. The results of the simulation confirm that Multi-layer data partitioning technique shows a better performance at higher error rates with different GOP. Further experiments in this work have shown the effects of GOP in terms of visual quality and bitrate for different multiview video sequences.

SOUND INSULATION OF A MECHANICAL WORKSHOP

The paper presents a design process related to sound insulation of a small mechanical workshop for storing eccentric presses, which is located in a densely populated housing estate. Starting from the theoretical model of acoustic insulation power of a single solid partition, a complex partition and a multi-layer partition, the acoustic insulation power of the walls and the ceiling in the workshop was determined. The results of calculation of workshop isolation coincide to a great extent with the experimental results of measuring noise levels. Key words: noise, mechanical workshop, sound insulation

Multi-layer coarse-graining polarization model for treating electrostatic interactions of solvated α-conotoxin peptides

A multi-layer coarse-graining (CG) model is presented for treating the electrostatic interactions of solvated α-conotoxin peptides. According to the sensitivity to the electrostatic environment, a hybrid set of electrostatic parameters, such as secondary-structure- and residue-based dipoles, and atom-centered partial charges, are adopted. For the polarization "inert" secondary-structures and residues, the fragment dipole moments are distributed within narrow ranges with the magnitude close to zero. The coarse-graining fragment dipoles are parameterized from a large training set (10,000 configurations) to reproduce the electrostatic features of molecular fragments. In contrast, the electrostatically "sensitive" atoms exhibit large fluctuations of charges with the varied environments. The environment-dependent variable charges are updated in each energetic calculation. The electrostatic interaction of the whole chemical system is hence partitioned into several sub-terms coming from the fragment dipole-dipole, (fragment) dipole-(atom) charge, and atom charge-charge interactions. A large number of test calculations on the relative energies of cyclo-peptide conformers have demonstrated that the multi-layer CG electrostatic model presents better performance than the non-polarized force fields, in comparison with the density-functional theory and the fully polarized force field model. The selection of CG fragment centers, mass or geometric center, has little influence on the fragment-based dipole-dipole interactions. The multi-layer partition of electrostatic polarization is expected to be applied to many biologically interesting and complicated phenomena.

Sound transmission between partitioned contiguous enclosures

By increasing the application of lightweight constructions, sound transmission between the adjacent enclosures becomes a more important consideration in designing new buildings. In this article, the parameters that may significantly affect the sound transmission level through a partition between two adjacent enclosures are investigated, i.e. geometrical dimensions, arrangement of enclosures, boundary conditions, multi-layered partitions, and framed (or reinforced) conditions of the partitions. For this purpose, sound transmission is modelled using the finite-element method. The obtained results from sound transmission using Perspex party walls with different width and boundary conditions are compared with those obtained from a double-layered wall with an air layer. The effects of an enclosure's arrangements and dimensions on sound transmission of the party walls are also studied. Using the cross-framed party wall causes more noise reduction than the double-layered party wall. The results also show that sound transmission between rooms with an asymmetric arrangement is less than that obtained from a symmetric configuration.

Computational analysis and design of lattice structures with integral compliant mechanisms

This paper introduces a unique technique for the design of single and multi-layered, periodic lattice structures. Specifically, small-scale compliant mechanisms are integrated into large-scale structures for specific dynamic functionality. Accordingly, the mid-frequency computational analysis of such structures at multiple scales is reviewed, and the results from several recent design studies are presented to illustrate the methodology. Highlighted applications include the design of alternative material structures, multi-layered partitions having enhanced vibro-acoustic characteristics, lightweight truss structures with multi-functional properties, and three-dimensional lattices.

Partitioned Distinct Element Method Simulation of Granular Flow within Industrial Silos

A method for performing discrete element simulations of granular flow and pressures within industrial silos is presented. Special attention is devoted to complex problems involving large numbers of particles and sophisticated boundary conditions due to the presence of inserts. The proposed method consists of partitioning the silo into layers that are analyzed sequentially, and in determining stresses and velocities at the virtual interlayer boundaries. The method is first validated by simulating the discharge of a single insert hopper containing 20,000 particles, performing both a simulation of the whole silo and a multilayer partition. The results show a small discrepancy in the displacement fields produced by the two simulations. Then the discharge of an industrial silo containing 170,000 particles with several inserts of different size and shape is simulated. The relevance of the stress and velocity fields obtained confirms the feasibility and the efficiency of the procedure. The method allows for managing huge numbers of particles with a limited memory capacity and a gain of computational time that may be significant depending on each particular case.

Experimental sound insulation improvement in multi-layered sandwich partitions

Experimental sound insulation improvement in multi-layered sandwich partitions

Design of lightweight multilayer partitions based on sonic crystals

The sound transmission coefficient of different multilayer partitions commonly encountered in buildings has been measured as a function of frequency. Most of the samples studied showed an increase in the sound transmission coefficient over a specific frequency, called the critical frequency, depending on the layer material. However, for partitions built with the same materials, but built with a periodic arrangement of layers, this behavior has not been observed. This kind of periodic multilayer partition can be considered as a sonic crystal, because the stopband corresponding to a one-dimensional sonic crystal with a constant lattice equal to the modulation of the partition is in the same range as the critical frequency of the panel.

Transmission loss measurement of multilayered partitions in time domain

Transmission loss through single-layered partitions depends on the superficial specific mass m of the material. A multilayered partition has, at each interface, an impedance jump that improves its transmission loss. Due to these characteristics, multilayered partitions can provide better sound insulation than a single-layered partition with the same thickness, being much lighter. In this work an experimental setup was built to study the transmission loss of a sample inside a duct. The partition is inserted between two sections of the duct and a pulse is generated at one side. The incident and the transmitted signals are captured by free-field microphones, and the time domain series, acquired with a two channel digital oscilloscope, provides the transmission loss. The impedance of the materials tested was found experimentally and compared with tables, when available. The experiment was performed in order to evaluate transmission loss in single-, double- and three-layered partitions. The experimental results were compared with numerical simulation using the software layer, developed in our laboratory, showing good agreement.

Transmission loss measurement in time domain using an impulse technique in ducts

The method proposed is an option to the one described by ISO-140, which needs two reverberant chambers. It consists of a duct 3 m long with a cutoff frequency around 1300 Hz, with a loudspeaker at one end and an anechoic termination at the other. The sample is placed 1 m from the loudspeaker and two microphones are placed around 500 mm from the sample, the first between the loudspeaker and the sample and the second between the sample and the anechoic termination. An impulse is generated and captured at microphone 1 as the incident pulse at the sample and at microphone 2 as the transmitted pulse through the sample. The impulse size is controlled in order to have enough energy in the frequency range desired and not to be too long to mix with the pulse reflected by the sample. In the frequency domain, the energy difference between the signals is compared with the mass law. The ultimate goal of this research is achieving a simple technique for evaluation of transmission loss in multilayered partitions.