scholarly journals Inverse Problem of Air Filtration of Nanoparticles: Optimal Quality Factors of Fibrous Filters

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Dahua Shou ◽  
Jintu Fan ◽  
Lin Ye ◽  
Heng Zhang ◽  
Xiaoming Qian ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Structural Parameters ◽  
Single Layer ◽  
Air Filtration ◽  
Quality Factors ◽  
Fibrous Filters ◽  
Lognormal Size Distribution ◽  
Face Velocity ◽  
Filter Thickness ◽  
Optimal Quality

Application of nanofibers has become an emerging approach to enhance filtration efficiency, but questions arise about the decrease in Quality factor (QF) for certain particles due to the rapidly increasing pressure drop. In this paper, we theoretically investigate the QF of dual-layer filters for filtration of monodisperse and polydisperse nanoparticles. The inverse problem of air filtration, as defined in this work, consists in determining the optimal construction of the two-layer fibrous filter with the maximum QF. In comparison to a single-layer substrate, improved QF values for dual-layer filters are found when a second layer with proper structural parameters is added. The influences of solidity, fiber diameter, filter thickness, face velocity, and particle size on the optimization of QF are studied. The maximum QF values for realistic polydisperse particles with a lognormal size distribution are also found. Furthermore, we propose a modified QF (MQF) accounting for the effects of energy cost and flow velocity, which are significant in certain operations. The optimal MQF of the dual-layer filter is found to be over twice that of the first layer. This work provides a quick tool for designing and optimizing fibrous structures with better performance for the air filtration of specific nanoparticles.

scholarly journals DESIGN AND CONSTRUCTION OF THE WESTERN BREAKWATER FOR THE OUTER PORT AT PUNTA LANGOSTEIRA (A CORUÑA, SPAIN)

2017 ◽  
pp. 14 ◽  
Author(s):  
Antonio Corredor Molguero ◽  
M. Esther Gómez-Martín ◽  
Enrique Peña ◽  
Josep R. Medina
Keyword(s):  
Design Process ◽  
Double Layer ◽  
Atlantic Coast ◽  
Single Layer ◽  
Significant Problem ◽  
Stability Tests ◽  
Final Design ◽  
New Challenges ◽  
Filter Thickness ◽  
Hydraulic Stability

This paper describes the design process, hydraulic stability tests and construction of the Cubipod® armored Western breakwater at Punta Langosteira (Outer Port of A Coruña, Spain), located on the Atlantic coast of Spain. The environmental, geotechnical, economic and logistic conditions favored randomly-placed Cubipods for single-layer armoring of the trunk. 3D hydraulic stability tests were carried out to validate the final design of the Western Breakwater; two models were tested with single- and double-layer Cubipod armors in the trunk and roundhead, respectively. Single-layer 25- and 30-tonne Cubipod® armors were used for the trunk section and a double-layer 45-tonne Cubipod® armor was used for the roundhead. During this project, new challenges were overcome, such as constructing a transition between single and double-layer armors, and manufacturing and handling of 45-tonne Cubipods. The transition in the armor thickness was solved by modifying the filter thickness under the main armor, to ensure a homogeneous external armor profile. Breakwater construction finished in November 2016 with no significant problem or delay in the original schedule.

scholarly journals Numerical Study of an Ultra-Broadband All-Silicon Terahertz Absorber

2020 ◽  
Vol 10 (2) ◽  
pp. 436 ◽  
Author(s):  
Jinfeng Wang ◽  
Tingting Lang ◽  
Tingting Shen ◽  
Changyu Shen ◽  
Zhi Hong ◽  
...  
Keyword(s):  
Numerical Study ◽  
Structural Parameters ◽  
Impedance Matching ◽  
Single Layer ◽  
Transverse Magnetic ◽  
Absorption Efficiency ◽  
Absorption Mechanism ◽  
Loss Mechanism ◽  
Perfect Absorption ◽  
Terahertz Absorber

In this article we present and numerically investigate a broadband all-silicon terahertz (THz) absorber which consists of a single-layer periodic array of a diamond metamaterial layer placed on a silicon substrate. We simulated the absorption spectra of the absorber under different structural parameters using the commercial software Lumerical FDTD solutions, and analyzed the absorption mechanism from the distribution of the electromagnetic fields. Finally, the absorption for both transverse electric (TE) and transverse magnetic (TM) polarizations under different incident angles from 0 to 70° were investigated. Herein, electric and magnetic resonances are proposed that result in perfect broadband absorption. When the absorber meets the impedance matching principle in accordance with the loss mechanism, it can achieve a nearly perfect absorption response. The diamond absorber exhibits an absorption of ~100% at 1 THz and achieves an absorption efficiency >90% within a bandwidth of 1.3 THz. In addition, owing to the highly structural symmetry, the absorber has a polarization-independent characteristic. Compared with previous metal–dielectric–metal sandwiched absorbers, the all-silicon metamaterial absorbers can avoid the disadvantages of high ohmic losses, low melting points, and high thermal conductivity of the metal, which ensure a promising future for optical applications, including sensors, modulators, and photoelectric detection devices.

Dynamic Stability and Ultimate Capacity of Suspended Dome under Earthquakes

2013 ◽  
Vol 639-640 ◽  
pp. 875-881
Author(s):  
Yong Mei Li ◽  
Kun Hu ◽  
Wei Jing Zhang
Keyword(s):  
Dynamic Stability ◽  
Structural Parameters ◽  
Single Layer ◽  
Element Model ◽  
Ultimate Capacity ◽  
Maximum Displacement ◽  
Structural Dynamic ◽  
Long Span ◽  
Small Ratio ◽  
Lattice Shell

Suspended dome is a reasonable and novel type of long-span hybrid spatial structures based upon single-layer spherical lattice shell and tensegrity system. Based upon the structural force-bearing characteristics, the combined finite element model of beam elements, truss elements and cable elements is set up. A method taking the maximum displacement on nodes under earthquake acceleration of each level as dynamic response representative parameter is proposed to study the dynamic stable ultimate capacity of suspended dome by application of the incremental dynamic analysis in combination with B-R kinetic criterion. Furthermore, considering suspended dome has the clear advantage over Single-Layer Spherical Lattice Shell for a structure with a long span and a small ratio of rise to span, the influences of factors such as structural parameters, geometric parameters, and different earthquake input are investigated on dynamic stability for a kiewitt-type suspended dome with a long span and a small ratio of rise to span. Finally of suspended dome some conclusions are obtained such as the initial defects can clearly reduce dynamic stable ultimate capacity, and since the rise-span ratio, pre-stressing level and cross section area are not monotonous as variety to the structural dynamic stability, they should be optimized to enhance or improve the structural dynamic stability, which can be rules for engineering design.

Calculation of Horizontal Rigidity of the Plate Type Elastomeric Pad Bearing for Highway Bridge

2012 ◽  
Vol 204-208 ◽  
pp. 2244-2247
Author(s):  
Jie Wang ◽  
Jian Xin Liu
Keyword(s):  
Structural Parameters ◽  
Single Layer ◽  
Highway Bridges ◽  
Highway Bridge ◽  
Rubber Layer ◽  
Republic Of China ◽  
Communications Industry ◽  
Industry Standard ◽  
Bridge Bearings ◽  
Plate Type

The plate type elastomeric pad bearing is the most commonly used in highway bridge bearings. In the seismic design of bridges, the horizontal rigidity of the bearing is an important calculation parameters. The specific values of each parameter in the formula are not clear, and it can not provide a clear computation measures, although the formula of horizontal rigidity is given in the specification. Against Series bearings in plate type elastomeric pad bearing for Highway Bridge (JT/T4-2004), the People's Republic of China Communications Industry Standard, the structural parameters of the bearing are systematically introduced, including the shape factor, the bearing thickness, the thickness of the single-layer rubber and the total thickness of rubber layer. The methodology and detailed steps of the bearing horizontal rigidity are then analyzed and summarized by the formulas above. At last several examples of the different type of bearings are given. Some reference are Provided for the calculation of the stiffness frequently of plate type elastomeric pad bearing which are frequently used for highway bridges.

scholarly journals Quantitative method for determining the solution error of the inverse problem in the electrometry of oil and gas wells

2021 ◽  
Vol 280 ◽  
pp. 09003
Author(s):  
Mykyta Myrontsov ◽  
Oleksiy Karpenko ◽  
Volodymyr Horbulin
Keyword(s):  
Inverse Problem ◽  
Quantitative Method ◽  
Oil And Gas ◽  
Low Frequency ◽  
Single Layer ◽  
Gas Wells ◽  
Actual Measurement ◽  
Induction Logging ◽  
Oil And Gas Wells ◽  
Unstable Solutions

Determining the quantitative degree of connection between logging error and the corresponding error of oil and gas wells electrometry inverse problem solving is considered. A quantitative method to determine the magnitude of the error of solving the inverse problem depending on the magnitude of the logging error for a given model of a single layer or section as a whole is described. Examples of determining the error of the inverse problem for real well materials, taking into account the actual measurement error, are given. A method for determining the characteristics of the spatial resolution of electrometry methods is described. Examples of its use for low-frequency induction logging equipment are given. The proposed methods allow to determine the areas of equivalent solutions and the areas of existence of stable / unstable solutions of the inverse electrometry problem.

scholarly journals Estimation of the dependence of aerodynamic resistance of the bulk tank on porosity and rate of filtration

Vestnik IGEU ◽  
2019 ◽  
pp. 16-24
Author(s):  
G.A. Perevezentsev ◽  
V.A. Gorbunov ◽  
O.B. Kolibaba
Keyword(s):  
Experimental Study ◽  
Structural Parameters ◽  
Aerodynamic Resistance ◽  
Heating Time ◽  
Air Filtration ◽  
Gas Filtration ◽  
Filtration Process ◽  
Fluid Filtration ◽  
Application Range ◽  
Bulk Tank

One of the effective ways to intensify heat exchange processes in the bulk tank is organization of gas filtration through the tank. However, it is necessary to compare the positive effect obtained by reducing the heating time and, hence, the required amount of heat input with the resistance of the bulk tank, which affects the choice of equipment. The existing formulas for determining tank layer resistance, as a rule, have a limited application range due to a number of structural parameteres. Thus, obtaining the value of the aerodynamic resistance of bulk tanks of different structures is an important task for determining the amount of energy consumed for the organization of the filtration process. The work employed the data obtained in the experimental study of fluid filtration through a porous medium in the range of porosity values. The method of nonlinear regression analysis was used to approximate the desired dependence. Based on the data on the resistance of bulk tanks of different porosity obtained in the experimental study, the authors have derived an empirical polynomial dependence of the resistance of bulk tanks on the fluid mass flow rate and porosity. This equation can be applied for the filtration rate values from 2 to 8 m/s and porosity values from 0,345 to 0,888 regardless of the structural parameters of the bulk tank layer. The authors carried out mathematical modeling of the air filtration process through the tank by replacing the real structure with a fractal-like model. The obtained results allow optimizing the operating parameters of the equipment in thermal heating furnaces, and the presented dependence can be used to determine the aerodynamic resistance of bulk tanks, affecting the choice of traction equipment in the reconstruction of furnaces. The accuracy of the obtained results is determined by the experiment error, which does not exceed 7 %.

Computational Methods for the Detection of the Source of Acoustical Noise

2000 ◽  
Author(s):  
Thomas DeLillo ◽  
Victor Isakov ◽  
Nicolas Valdivia ◽  
Lianju Wang
Keyword(s):  
Inverse Problem ◽  
Computational Methods ◽  
Single Layer ◽  
Singular Value ◽  
Pressure Measurements ◽  
Single Layer Potential ◽  
Interior Region ◽  
Layer Potential ◽  
Representation Of Solutions ◽  
Value Decomposition

Abstract Computational methods for the inverse problem of detecting the source of acoustical noise in an interior region from pressure measurements in the nearfield are discussed. The methods are based on a single layer potential representation of solutions to the Helmholtz equation. Regularization is peformed using the singular value decomposition and the conjugate gradient method.

Performance of Thin-Film Silicon MEMS Resonators in Vacuum

2003 ◽  
Vol 762 ◽  
Author(s):  
J. Gaspar ◽  
V. Chu ◽  
J. P. Conde
Keyword(s):  
Thin Film ◽  
Single Layer ◽  
Quality Factors ◽  
Gate Electrode ◽  
Glass Substrates ◽  
Mems Resonators ◽  
Resonance Frequencies ◽  
Heavily Doped ◽  
Processing Steps

AbstractThis paper reports on the fabrication and characterization of microelectromechanical bridge resonators on glass substrates using thin-film technology and surface micromachining. All the processing steps are performed at temperatures below 110°C. The microbridges consist of either a single layer of heavily doped n-type amorphous silicon (n+-a-Si:H) or bilayers of aluminum (Al) and intrinsic a-Si:H. The bridge is suspended over a gate electrode with a 1 μm air-gap. Applying a voltage between the bridge and an underlying Al gate electrode electrostatically actuates the microstructures. The resulting deflection is monitored optically. The resonance of the microbridges is measured in air and in vacuum. Resonance frequencies up to 70 MHz and quality factors up to 3000 are obtained at pressures below 1 Torr. The energy dissipation mechanisms of the resonators are discussed.

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