scholarly journals Optical Methods Applied to Hydrodynamics of Cohesive Sediments

2018 ◽  
Author(s):  
Juan Antonio Garcia Aragon ◽  
Salinas Tapia Humberto ◽  
Diaz Palomarez Victor ◽  
Klever Izquierdo Ayala
Keyword(s):  
Optical Methods ◽  
Cohesive Sediments

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

Investigation of cluster layers of small netal particles by TEM, SEM, EELS and by photoacoustic spectroscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 250-251
Author(s):  
H. Seiler ◽  
U. Haas ◽  
K.H. Körtje
Keyword(s):  
Bulk Material ◽  
High Vacuum ◽  
Optical Methods ◽  
Metal Particles ◽  
Silver Particles ◽  
Low Loss ◽  
Plasmon Excitation ◽  
First Results ◽  
Diffraction Patterns ◽  
Small Metal Particles

The physical properties of small metal particles reveal an intermediate position between atomic and bulk material. Especially Ag has shown pronounced size effects. We compared silver layers evaporated in high vacuum with cluster layers of small silver particles, evaporated in N2 at a pressure of about 102 Pa. The investigations were performed by electron optical methods (TEM, SEM, EELS) and by Photoacoustic (PA) Spectroscopy (gas-microphone detection).The observation of cluster layers with TEM and high resolution SEM show small silver particles with diameters of about 50 nm (Fig. 1 and Figure 2, respectively). The electron diffraction patterns of homogeneous Ag layers and of cluster layers are similar, whereas the low loss EELS spectra due to plasmon excitation are quite different. Fig. 3 and Figure 4 show first results of EELS spectra of a cluster layer of small silver particles on carbon foil and of a homogeneous Ag layer, respectively.

Comparison of sensitivity of the refractometric methods of frustrated total internal reflection and surface plasmon resonance

2020 ◽  
pp. 44-49
Author(s):  
I. N. Pavlov
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Total Internal Reflection ◽  
Resonance Method ◽  
Internal Reflection ◽  
Optical Methods ◽  
Thin Boundary Layer ◽  
Experimental Conditions ◽  
Frustrated Total Internal Reflection

Two optical methods, namely surface plasmon resonance imaging and frustrated total internal reflection, are described in the paper in terms of comparing their sensitivity to change of refractive index of a thin boundary layer of an investigated medium. It is shown that, despite the fact that the theoretically calculated sensitivity is higher for the frustrated total internal reflection method, and the fact that usually in practice the surface plasmon resonance method, on the contrary, is considered more sensitive, under the same experimental conditions both methods show a similar result.

APPLICATION OF PHYSICAL AND OPTICAL METHODS FOR SOOT EVALUATION IN A FULL-SCALE POWER PLANT

1995 ◽  
Author(s):  
Loretta Bonfanti ◽  
Leonardo Castellano ◽  
Sauro Pasini ◽  
Nice Pintus ◽  
Christine Mounaim-Rousselle
Keyword(s):  
Power Plant ◽  
Full Scale ◽  
Optical Methods

Design options for self-cleansing storm sewers

1996 ◽  
Vol 33 (9) ◽  
pp. 215-220 ◽  
Author(s):  
Chandramouli Nalluri ◽  
Aminuddin Ab. Ghani
Keyword(s):  
Cohesive Sediments ◽  
Stress Criterion ◽  
Sediment Bed ◽  
Sediment Size ◽  
Codes Of Practice ◽  
Design Charts ◽  
Design Options ◽  
Minimum Velocity ◽  
Limited Depth ◽  
Storm Sewers

A list of available codes of practice for self-cleansing sewers is presented and a review of appraisals of minimum velocity criterion is summarised. Comparisons of newly developed “minimum velocity” criteria and “minimum shear stress” criterion are presented. Some design charts are also given. These charts are applicable to non-cohesive sediments (typically storm sewers). It appears that sediment size and concentration need to be taken into account, and that a limited depth of sediment bed is recommended for large pipes (diameters > 1000 mm) to maximise their transport capacity.

scholarly journals Dynamic Manipulation of THz Waves Enabled by Phase-Transition VO2 Thin Film

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 114
Author(s):  
Chang Lu ◽  
Qingjian Lu ◽  
Min Gao ◽  
Yuan Lin
Keyword(s):  
Optical Methods ◽  
Stimuli Responsive ◽  
Device Structure ◽  
Current State ◽  
Insulator Metal Transition ◽  
Potential Applications ◽  
Fs Laser ◽  
External Stimuli ◽  
Thz Applications ◽  
Thz Waves

The reversible and multi-stimuli responsive insulator-metal transition of VO2, which enables dynamic modulation over the terahertz (THz) regime, has attracted plenty of attention for its potential applications in versatile active THz devices. Moreover, the investigation into the growth mechanism of VO2 films has led to improved film processing, more capable modulation and enhanced device compatibility into diverse THz applications. THz devices with VO2 as the key components exhibit remarkable response to external stimuli, which is not only applicable in THz modulators but also in rewritable optical memories by virtue of the intrinsic hysteresis behaviour of VO2. Depending on the predesigned device structure, the insulator-metal transition (IMT) of VO2 component can be controlled through thermal, electrical or optical methods. Recent research has paid special attention to the ultrafast modulation phenomenon observed in the photoinduced IMT, enabled by an intense femtosecond laser (fs laser) which supports “quasi-simultaneous” IMT within 1 ps. This progress report reviews the current state of the field, focusing on the material nature that gives rise to the modulation-allowed IMT for THz applications. An overview is presented of numerous IMT stimuli approaches with special emphasis on the underlying physical mechanisms. Subsequently, active manipulation of THz waves through pure VO2 film and VO2 hybrid metamaterials is surveyed, highlighting that VO2 can provide active modulation for a wide variety of applications. Finally, the common characteristics and future development directions of VO2-based tuneable THz devices are discussed.

Pickup rate of non-cohesive sediments in low-velocity flows

2021 ◽  
pp. 1-11
Author(s):  
Dake Chen ◽  
Bruce Melville ◽  
Jinhai Zheng ◽  
Yigang Wang ◽  
Chi Zhang ◽  
...  
Keyword(s):  
Cohesive Sediments ◽  
Low Velocity
Sign in / Sign up

Export Citation Format

Share Document