New Approach for Large-Area Thermoelectric Junctions with a Liquid Eutectic Gallium–Indium Electrode

The multi-layer nature of airport pavement structures is susceptible to the generation of voids at the bonding parts of the structure, which is also called interlayer debonding. Observations have shown that the thickness of the resulting voids is usually at the scale of millimeters, which makes it difficult to inspect. The efficient and accurate characteristics of ground penetrating radar (GPR) make it suitable for large area inspections of airport pavement. In this study, a multi-static GPR system was used to inspect the interlayer debonding of a large area of an airport pavement. A special antenna arrangement can obtain common mid-point (CMP) gathers during a common offset survey. The presence of interlayer debonding affects the phase of the reflection signals, and the phase disturbance can be quantified by wavelet transform. Therefore, an advanced approach that uses the average entropy of the wavelet transform parameters in CMP gathers to detect the interlayer debonding of airport pavement is proposed. The results demonstrate that the regions with high entropy correspond to the regions where tiny voids exist. The new approach introduced in this study was then evaluated by a field-base experiment at an airport taxiway model. The results show that the proposed approach can detect interlayer debonding of the pavement model accurately and efficiently. The on-site coring results confirm the performance of the proposed approach.

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Unbaked materials from mixtures of waste sludge of a water purification plant, fly ash, and water glass

Science & Technology Development Journal - Engineering and Technology ◽

10.32508/stdjet.v4i1.754 ◽

2021 ◽

Vol 4 (1) ◽

pp. 663-669

Author(s):

Do Quang Minh ◽

Huynh Ngoc Minh ◽

Nguyen Vu-Uyen Nhi

Keyword(s):

Fly Ash ◽

Water Purification ◽

Water Glass ◽

National Standards ◽

Ho Chi Minh City ◽

Large Area ◽

New Approach ◽

Waste Sludge ◽

Alkaline Activity ◽

Purification Plant

In water purification plants, a large area of urban land is using to store waste sludge (WS). The waste sludge from water filtration plants is aluminosilicate, which can be form a geopolymer. However, the waste sludge has low alkaline activity, so it must be used in combination with fly ash (FA) to create geopolymer products. Fly ash is a solid waste containing amorphous silica so that has high alkaline activity, suitable for treatment by geopolymer method. The geopolymerization of waste sludge from water purification plants is a relatively new method. The geopolymer is a binder formed by the chemical reaction between aluminosilicate materials and alkaline activated solutions. The alkaline activated solution used in these experiments was water glass (WG). The water glass is solution of sodium silicate (Na2O.nSiO2) dissolved in water. The research results of geopolymer materials from the mixture of fly ash, the waste sludge of Thu Duc water purification plant, Ho Chi Minh City (Vietnam), and water glass (WG) were introduced in this study. The activated Al2O3 and SiO2 oxides in the fly ash and the waste sludge can be dissolved in the water glass and polymerized into a geopolymer material. The test samples had pressed at a high pressure of 225 MPa to form cylindrical ones weighing approximately 3 grams, height about 18 mm, and 10 mm in diameter. These samples were then cured at 110 ◦C for 24 hours and at room temperature (30 +/- 5 ◦C). The methods of Fourier infrared spectroscopy (FTIR) and scanning electron microscope (SEM) had used to detect the microscopic structure and geopolymer bond formation of the samples. The compressive strength of the tested samples at 28 days old was higher than 3.5 MPa, the pH was less than 12.5, meeting the Vietnamese National Standards for unbaked materials (TCVN 6477:2016) and National Technical Regulation on environmental impact (QCVN 50:2013 / BTNMT), respectively. The results show a new approach of solidifying the waste sludge for further applications such as the manufacture of geopolymer concretes or landfill materials.

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Electrochromic Performance of V2O5 Thin Films Grown by Spray Pyrolysis

Materials ◽

10.3390/ma13173859 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3859 ◽

Cited By ~ 3

Author(s):

Kyriakos Mouratis ◽

Valentin Tudose ◽

Cosmin Romanitan ◽

Cristina Pachiu ◽

Oana Tutunaru ◽

...

Keyword(s):

Thin Films ◽

Spray Deposition ◽

Cost Effective ◽

Active Surface ◽

X Ray Diffraction ◽

Large Area ◽

New Approach ◽

X Ray ◽

Area Deposition ◽

Scanning Electron

A new approach regarding the development of nanostructured V2O5 electrochromic thin films at low temperature (250 °C), using air-carrier spray deposition and ammonium metavanadate in water as precursor is presented. The obtained V2O5 films were characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy, while their electrochromic response was studied using UV-vis absorption spectroscopy and cyclic voltammetry. The study showed that this simple, cost effective, suitable for large area deposition method can lead to V2O5 films with large active surface for electrochromic applications.

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Integrating Backdating and Transfer Learning in an Object-Based Framework for High Resolution Image Classification and Change Analysis

Remote Sensing ◽

10.3390/rs12244094 ◽

2020 ◽

Vol 12 (24) ◽

pp. 4094

Author(s):

Yuguo Qian ◽

Weiqi Zhou ◽

Wenjuan Yu ◽

Lijian Han ◽

Weifeng Li ◽

...

Keyword(s):

Transfer Learning ◽

Sample Selection ◽

Urban Landscapes ◽

Target Area ◽

Large Area ◽

Change Analysis ◽

Entire Study ◽

New Approach ◽

Novel Approach ◽

Object Based

Classification and change analysis based on high spatial resolution imagery are highly desirable for urban landscapes. However, methods with both high accuracy and efficiency are lacking. Here, we present a novel approach that integrates backdating and transfer learning under an object-based framework. Backdating is used to optimize the target area to be classified, and transfer learning is used to select training samples for classification. We further compare the new approach with that of using backdating or transfer learning alone. We found: (1) The integrated new approach had higher overall accuracy for both classifications (85.33%) and change analysis (88.67%), which were 2.0% and 4.0% higher than that of backdating, and 9.3% and 9.0% higher than that of transfer learning, respectively. (2) Compared to approaches using backdating alone, the use of transfer learning in the new approach allows automatic sample selection for supervised classification, and thereby greatly improves the efficiency of classification, and also reduces the subjectiveness of sample selection. (3) Compared to approaches using transfer learning alone, the use of backdating in the new approach allows the classification focusing on the changed areas, only 16.4% of the entire study area, and therefore greatly improves the efficiency and largely avoid the false change. In addition, the use of a reference map for classification can improve accuracy. This new approach would be particularly useful for large area classification and change analysis.

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Deposition of High Quality Amorphous Silicon by a New “Hot Wire” CVD Technique

MRS Proceedings ◽

10.1557/proc-557-85 ◽

1999 ◽

Vol 557 ◽

Cited By ~ 2

Author(s):

Scott Morrison ◽

Ken Coates ◽

Jianping Xi ◽

Arun Madan

Keyword(s):

Amorphous Silicon ◽

Chemical Vapor ◽

Dark Conductivity ◽

Hot Wire ◽

Large Area ◽

New Approach ◽

Vapor Deposition Technique ◽

Photovoltaic Applications ◽

Technical Issues ◽

Silicon Materials

AbstractFor the “Hot Wire” chemical vapor deposition technique (HWCVD) method to be applicable for photovoltaic applications, certain critical technical issues need to be addressed and resolved such as: lifetime of the filaments, reproducibility, large area demonstration of the material and stable devices. We have developed a new approach (patent applied for) which addresses some of these problems, specifically longevity of the filaments and reproducibility of the materials produced. The new filament material used has so far shown no appreciable degradation even after deposition of >200 μm of amorphous silicon (a-Si). We report that this can produce “state-ofthe-art” a-Si with a dark conductivity of <10-10 (Ohm*cm)-1 and photoconductivity of >10-5 (Ohm*cm)-1 this material can also be doped p- or n-type. We also provide data using XRD as well as the Raman spectra. These materials have been incorporated into simple Schottky barrier structures. The development of microcrystalline silicon materials is also discussed.

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A new approach to mapping permafrost and change incorporating uncertainties in ground conditions and climate projections

The Cryosphere ◽

10.5194/tc-8-2177-2014 ◽

2014 ◽

Vol 8 (6) ◽

pp. 2177-2194 ◽

Cited By ~ 23

Author(s):

Y. Zhang ◽

I. Olthof ◽

R. Fraser ◽

S. A. Wolfe

Keyword(s):

Land Cover ◽

Land Use Planning ◽

Computation Time ◽

Climate Projections ◽

Field Observations ◽

Infrastructure Development ◽

Climate Scenarios ◽

Large Area ◽

New Approach ◽

Ground Conditions

Abstract. Spatially detailed information on permafrost distribution and change with climate is important for land use planning, infrastructure development, and environmental assessments. However, the required soil and surficial geology maps in the North are coarse, and projected climate scenarios vary widely. Considering these uncertainties, we propose a new approach to mapping permafrost distribution and change by integrating remote sensing data, field measurements, and a process-based model. Land cover types from satellite imagery are used to capture the general land conditions and to improve the resolution of existing permafrost maps. For each land cover type, field observations are used to estimate the probabilities of different ground conditions. A process-based model is used to quantify the evolution of permafrost for each ground condition under three representative climate scenarios (low, medium, and high warming). From the model results, the probability of permafrost occurrence and the most likely permafrost conditions are determined. We apply this approach at 20 m resolution to a large area in Northwest Territories, Canada. Mapped permafrost conditions are in agreement with field observations and other studies. The data requirements, model robustness, and computation time are reasonable, and this approach may serve as a practical means to mapping permafrost and changes at high resolution in other regions.

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