scholarly journals Synthesis of Micro- and Nanoparticles in Sub- and Supercritical Water: From the Laboratory to Larger Scales

2020 ◽  
Vol 10 (16) ◽  
pp. 5508
Author(s):  
F. Ruiz-Jorge ◽  
J. R. Portela ◽  
J. Sánchez-Oneto ◽  
E. J. Martínez de la Ossa
Keyword(s):  
Supercritical Fluids ◽  
Supercritical Water ◽  
Metal Particles ◽  
High Pressure And Temperature ◽  
Particle Generation ◽  
Innovative Method ◽  
Wide Range ◽  
Active Research ◽  
Main Operating ◽  
Temperature Water

The use of micro- and nanoparticles is gaining more and more importance because of their wide range of uses and benefits based on their unique mechanical, physical, electrical, optical, electronic, and magnetic properties. In recent decades, supercritical fluid technologies have strongly emerged as an effective alternative to other numerous particle generation processes, mainly thanks to the peculiar properties exhibited by supercritical fluids. Carbon dioxide and water have so far been two of the most commonly used fluids for particle generation, the former being the fluid par excellence in this field, mainly, because it offers the possibility of precipitating thermolabile particles. Nevertheless, the use of high-pressure and -temperature water opens an innovative and very interesting field of study, especially with regards to the precipitation of particles that could hardly be precipitated when CO2 is used, such as metal particles with a considerable value in the market. This review describes an innovative method to obtain micro- and nanoparticles: hydrothermal synthesis by means of near and supercritical water. It also describes the differences between this method and other conventional procedures, the most currently active research centers, the types of particles synthesized, the techniques to evaluate the products obtained, the main operating parameters, the types of reactors, and amongst them, the most significant and the most frequently used, the scaling-up studies under progress, and the milestones to be reached in the coming years.

scholarly journals An Overview on the Rheology, Mechanical Properties, Durability, 3D Printing, and Microstructural Performance of Nanomaterials in Cementitious Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2950
Author(s):  
Hongwei Song ◽  
Xinle Li
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Research Area ◽  
Cementitious Composites ◽  
Split Tensile Strength ◽  
Contour Crafting ◽  
Wide Range ◽  
Active Research

The most active research area is nanotechnology in cementitious composites, which has a wide range of applications and has achieved popularity over the last three decades. Nanoparticles (NPs) have emerged as possible materials to be used in the field of civil engineering. Previous research has concentrated on evaluating the effect of different NPs in cementitious materials to alter material characteristics. In order to provide a broad understanding of how nanomaterials (NMs) can be used, this paper critically evaluates previous research on the influence of rheology, mechanical properties, durability, 3D printing, and microstructural performance on cementitious materials. The flow properties of fresh cementitious composites can be measured using rheology and slump. Mechanical properties such as compressive, flexural, and split tensile strength reveal hardened properties. The necessary tests for determining a NM’s durability in concrete are shrinkage, pore structure and porosity, and permeability. The advent of modern 3D printing technologies is suitable for structural printing, such as contour crafting and binder jetting. Three-dimensional (3D) printing has opened up new avenues for the building and construction industry to become more digital. Regardless of the material science, a range of problems must be tackled, including developing smart cementitious composites suitable for 3D structural printing. According to the scanning electron microscopy results, the addition of NMs to cementitious materials results in a denser and improved microstructure with more hydration products. This paper provides valuable information and details about the rheology, mechanical properties, durability, 3D printing, and microstructural performance of cementitious materials with NMs and encourages further research.

scholarly journals Two-Dimensional Optical Metasurfaces: From Plasmons to Dielectrics

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Bo Liu ◽  
Kerui Song ◽  
Jiangnan Xiao
Keyword(s):  
Metal Particles ◽  
Subwavelength Structures ◽  
Metal Structures ◽  
Unit Structure ◽  
Wide Range ◽  
Different Types ◽  
Working Principle ◽  
Physical Fields ◽  
Near Future ◽  
Polarization Phase

Metasurfaces, kinds of planar ultrathin metamaterials, are able to modify the polarization, phase, and amplitude of physical fields of optical light by designed periodic subwavelength structures, attracting great interest in recent years. Based on the different type of the material, optical metasurfaces can be separated in two categories by the materials: one is metal and the other is dielectric. Metal metasurfaces rely on the surface plasma oscillations of subwavelength metal particles. Nevertheless, the loss caused by the metal structures has been a trouble, especially for devices working in transmit modes. The dielectric metasurfaces are based on the Faraday-Tyndall scattering of high-index dielectric light scattering particles. By reasonably designing the relevant parameters of the unit structure such as the size, direction, and shape, different functions of metasurfaces can realize and bring a wide range of applications. This article focuses on the metasurface concepts such as anomalous reflections and refractions and the working principle of different types of metasurfaces. Here, we briefly review the progress in developing optical over past few years and look into the near future.

scholarly journals In-situ Neutron Tomography on Mixing Behavior of Supercritical Water and Room Temperature Water in a Tubular Flow Reactor

2015 ◽  
Vol 69 ◽  
pp. 564-569 ◽  
Author(s):  
Seiichi Takami ◽  
Ken-ichi Sugioka ◽  
Kyohei Ozawa ◽  
Takao Tsukada ◽  
Tadafumi Adschiri ◽  
...  
Keyword(s):  
Supercritical Water ◽  
Room Temperature ◽  
Flow Reactor ◽  
Neutron Tomography ◽  
Mixing Behavior ◽  
Tubular Flow Reactor ◽  
Tubular Flow ◽  
Temperature Water

Investigation of Oxide-Removal of Various Metal Particles for Fabricating MEMS-Based Corrosion Sensor

2009 ◽  
Author(s):  
Feng Pan ◽  
Adam Huang
Keyword(s):  
Oxide Coating ◽  
Metal Particles ◽  
Operating Life ◽  
Metallic Particles ◽  
Sensing Material ◽  
Corrosion Sensor ◽  
Mems Fabrication ◽  
Wide Range ◽  
Titanium Aluminum ◽  
Oxide Removal

Recently, our research group has proposed a MEMS-based solid state corrosion sensor, which is based on embedding metal particle into elastomeric polymers to form a composite-based sensing material. The chemical and dimensional properties of the metal particles and polymer matrix will provide the tailorability in sensor sensitivity, selectivity, time response, and operating life-span. However, the oxidization of metallic particles prior to embedding is adverse for electrical transduction of such sensor. This paper will be based on the investigation of chemical etching protocols used to remove the oxide coating from metal particles without adversely alter the particle itself. The etching process must also be compatible with common MEMS fabrication processes and not limited by the wide range of particle sizes used (30nm–100um). More specifically, metal particles such as Titanium, Aluminum, Nickel, and Stainless Steel are currently being used and investigated.

Heat Transfer to Supercritical Water in Smooth-Bore Tubes

1965 ◽  
Vol 87 (4) ◽  
pp. 477-483 ◽  
Author(s):  
H. S. Swenson ◽  
J. R. Carver ◽  
C. R. Kakarala
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Supercritical Water ◽  
Convection Heat Transfer ◽  
Physical Property ◽  
Transfer Coefficients ◽  
Property Variation ◽  
Wide Range ◽  
Fully Developed Turbulent Flow ◽  
Data Points

Local forced convection heat-transfer coefficients for supercritical water flowing inside smooth-bore tubes were obtained experimentally over a range of pressures (3300 to 6000 psia) and bulk temperatures (167 to 1068 F). Because the thermophysical properties of supercritical fluids change rapidly with temperature in the pseudocritical range, conventional forced convection correlations were unable to fit the data. However, a satisfactory correlation for fully developed turbulent flow was obtained by properly modifying the conventional nondimensional model to account for the physical property variation across the boundary layer. Out of 2951 data points, 95 percent lie within ±15 percent of the correlation. It was also found that the same equation correlated supercritical pressure heat-transfer data of carbon dioxide over a wide range of conditions with good accuracy.

Effect of Buoyancy on Heat Transfer in Supercritical Water Flow in a Horizontal Round Tube

2005 ◽  
Vol 127 (8) ◽  
pp. 897-902 ◽  
Author(s):  
Majid Bazargan ◽  
Daniel Fraser ◽  
Vijay Chatoorgan
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Local Heat Transfer ◽  
Heat Fluxes ◽  
Supercritical Water Oxidation ◽  
Transfer Coefficients ◽  
Horizontal Pipe ◽  
Free Region ◽  
Wide Range

Heat transfer to supercritical water and buoyancy∕natural convection effects are becoming increasingly important areas of research due to current trends in nuclear reactor design and supercritical water oxidation facilities. A pilot-scale supercritical water oxidation loop was constructed at the University of British Columbia. For this work, the facility was used to study the relative importance of buoyancy effects on supercritical water flowing in a horizontal pipe. Local heat transfer coefficients at the top and bottom surfaces of the horizontal test section were systematically measured over a wide range of conditions at supercritical pressures between 23 to 27 MPa, uniform heat fluxes were up to 310kW∕m2, and the mass flux ranged from 330 to 1230kg∕m2s. It was found that neglecting buoyancy effects could cause large discrepancies between the predictions of available empirical correlations and the experimental data. The data was used to assess available criteria for the buoyancy-free region during horizontal supercritical fluid flows. The criterion of Petukhov and Polyakov, which, for the range of parameters in this study, was found to be accurate in predicting the onset of buoyancy effects. The experimental investigation is confined to supercritical flows with heat addition only. Hence, no heat loss conditions at supercritical temperatures were investigated.

High-Sensitivity Raman Spectroscopy of Supercritical Water and Methanol over a Wide Range of Density

2007 ◽  
Vol 80 (9) ◽  
pp. 1764-1769 ◽  
Author(s):  
Yoshiro Yasaka ◽  
Masahito Kubo ◽  
Nobuyuki Matubayasi ◽  
Masaru Nakahara
Keyword(s):  
Raman Spectroscopy ◽  
Supercritical Water ◽  
High Sensitivity ◽  
Wide Range

Organometallic alkane and noble-gas complexes in conventional and supercritical fluids

2001 ◽  
Vol 73 (3) ◽  
pp. 443-447 ◽  
Author(s):  
Gavin I. Childs ◽  
David C. Grills ◽  
Xue Z. Sun ◽  
Michael W. George
Keyword(s):  
Ambient Temperature ◽  
Supercritical Fluids ◽  
Noble Gas ◽  
Fast Time ◽  
Time Resolved ◽  
Wide Range

Fast time-resolved infrared (TRIR) spectroscopy has been used to study a wide range of organometallic alkane and noble-gas complexes at ambient temperature. We have shown that the reactivity of the n-heptane complexes decreases both across and down Groups V, VI, and VII, and that the corresponding xenon complexes have similar reactivities.

scholarly journals Behavior signal processing for vehicle applications

2013 ◽  
Vol 2 ◽  
Author(s):  
Chiyomi Miyajima ◽  
Pongtep Angkititrakul ◽  
Kazuya Takeda
Keyword(s):  
Signal Processing ◽  
Research Field ◽  
Driving Safety ◽  
Human Machine Interaction ◽  
Lane Changing ◽  
The Road ◽  
Wide Range ◽  
Active Research ◽  
On The Road ◽  
Driver Identification

Within the past decade, analyzing and modeling human behavior by processing large amounts of collected data has become an active research field in the area of human–machine interaction. The research community is striving to find principled ways to explain and represent important behavioral characteristics of humans, with the goal of developing more efficient and more effective cooperative interactions between humans, machines, and environment. This paper provides a summary of the progress we have achieved to date in our study, which has focused specifically on interactions between driver, vehicle, and driving environment. First, we describe the method of data collection used to develop our on-the-road driving data corpus. We then provide an overview of the data-driven, signal processing approaches we used to analyze and model driver behavior for a wide range of practical vehicle applications. Next, we perform experimental validation by observing the actual driving behavior of groups of real drivers. In particular, the vehicle applications of our research include driver identification, behavior prediction related to car following and lane changing, detection of emotional frustration, and improving driving safety through driver coaching. We hope this paper will provide some insight to researchers with an interest in this field, and help identify areas and applications where further research is needed.

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