Theoretical study on photoemission of double-layer AlxGa1−xAs/GaAs nanocone array photocathode

2021 ◽  
Author(s):  
Yan Sun ◽  
Lei Liu ◽  
Zhisheng Lv ◽  
Xingyue Zhangyang ◽  
Feifei Lu ◽  
...  
Keyword(s):  
Cross Section ◽  
Light Trapping ◽  
Spectral Response ◽  
Circular Cross Section ◽  
Geometrical Parameters ◽  
Internal Electric Field ◽  
Surface Emission ◽  
The Difference ◽  
Section Structure ◽  
Light Capture

In the design of photocathode, the internal electric field could be formed due to the graded Al compositional [Formula: see text] nanostructure, which can improve the top surface emission probability of carriers. In this paper, [Formula: see text] nanostructure array photocathode composed of two sub-layers is presented. Based on the finite element method, the influence of graded geometrical parameters on their optoelectronic characteristics is investigated. The results show that when the thickness of the sublayer is equal, the difference of the Al composition between the two sublayers of nanostructure is larger, the sub-layers are less, and the quantum efficiency is higher. The light capture ability of the photocathode can be enhanced by increasing the thickness and the array spacing of the first sublayer. Compared with the hexagonal cross-section structure, the light trapping effect and spectral response of the circular cross-section structure are better.

scholarly journals On the self-induction of electric currents in a thin anchor-ring

1912 ◽  
Vol 86 (590) ◽  
pp. 562-571 ◽  
Keyword(s):  
Cross Section ◽  
Circular Cross Section ◽  
The Self ◽  
Electric Currents ◽  
Fourth Term ◽  
Starting Point ◽  
Axis Of Symmetry ◽  
The Difference ◽  
Circular Axis ◽  
Mutual Induction

In their useful compendium of "Formulæ and Tables for the Calculation of Mutual and Self-Inductance," Rosa And Cohen remark upon a small discrepancy in the formulæ given by myself and by M. Wien for the self-induction of a coil of circular cross-section over which the current is uniformly distributed . With omission of n , representative of the number of windings, my formula was L = 4 πa [ log 8 a / ρ - 7/4 + ρ 2 /8 a 2 (log 8 a / ρ + 1/3) ], (1) where ρ is the radius of the section and a that of the circular axis. The first two terms were given long before by Kirchhoff. In place of the fourth term within the bracket, viz., +1/24 ρ 2 / a 2 , Wien found -·0083 ρ 2 / a 2 . In either case a correction would be necessary in practice to take account of the space occupied by the insulation. Without, so far as I see, giving a reason, Rosa and Cohen express a preference for Wien's number. The difference is of no great importance, but I have thought it worth while to repeat the calculation and I obtain the same result as in 1881. A confirmation after 30 years, and without reference to notes, is perhaps almost as good as if it were independent. I propose to exhibit the main steps of the calculation and to make extension to some related problems. The starting point is the expression given by Maxwell for the mutual induction M between two neighbouring co-axial circuits. For the present purpose this requires transformation, so as to express the inductance in terms of the situation of the elementary circuits relatively to the circular axis. In the figure, O is the centre of the circular axis, A the centre of a section B through the axis of symmetry, and the position of any point P of the section is given by polar co-ordinates relatively to A, viz.

Damage Detection in Composite Cylindrical Multilayered Shells with Delaminations

2010 ◽  
Vol 123-125 ◽  
pp. 887-890 ◽  
Author(s):  
Aleksander Muc ◽  
Adam Stawiarski
Keyword(s):  
Wave Propagation ◽  
Numerical Analysis ◽  
Dynamic Behavior ◽  
Cross Section ◽  
Circular Cross Section ◽  
Piezoelectric Sensors ◽  
Structural Dynamic ◽  
Cylindrical Panels ◽  
The Difference ◽  
Computational Procedures

In this study, effective computational procedures are introduced and used to characterize the dynamic behavior of cylindrical panels with circular cross-section having the single delamination between laminate layers. Based on the computed results it is possible to determine the effect of delamination on the overall structural dynamic behavior. Those results are used to quantify the difference between the results of the relevant parameters in the cases of perfect and defected structures. Usually, the wave propagation can be observed with the use of piezoelectric sensors. Therefore, in the next step of our analysis we modeled delaminated structures with a finite number of PZT sensors to consider also their influence on the structural dynamic response. The numerical analysis have been conducted with the use of 3D finite elements. A lot of numerical results allow us to understand better the influence of various parameters on the form of wave propagation in cylindrical multilayered shells.

scholarly journals Visible Light Shielding Performance of Fabrics with Non-Circular Cross Section Fiber

2012 ◽  
Vol 7 (3) ◽  
pp. 155892501200700
Author(s):  
Xiaosong Liu ◽  
Fumei Wang
Keyword(s):  
Numerical Simulation ◽  
Light Intensity ◽  
Cross Section ◽  
Circular Cross Section ◽  
Transmitted Light ◽  
Characteristic Parameters ◽  
Intensity Ratios ◽  
Shielding Properties ◽  
The Difference ◽  
Better Than

The models of polyethylene terephthalate (PET) non-circular cross-section (NCCS) fibers were established, and the characteristic parameters of non-circular cross-section fiber used in this numerical simulation were extracted. Furthermore, the differences of refracted light intensity ratio Irz and the direction of refracted light βt among circular, trilobal and quadri-lobal cross-section fibers were analyzed theoretically. The results show that the refracted light intensity ratios Irz of these fibers were in the range of 0.94~0.95. Both the trilobal and quadri-lobal cross-section fibers’ βt, which was the angle of refracted light to Y-axis, changed non-monotonically and much more intricately than that of circular cross-section ones. Moreover, according to the theory of geometrical optics, the effects of trilobal and quadri-lobal cross-section shapes on the changes of internal refracted light and transmitted light in fibers were also conducted. The results suggested that the refracted and transmitted light were changed more effectively in the quadri-lobal cross-section fiber. The results of the experiment show that the shielding properties of quadri-lobal cross-section filament fabrics were better than that of the counterparts with circular fibers, but the difference was limited or insignificant.

scholarly journals Behavior of an Internally Confined Hollow Reinforced Concrete Column with a Polygonal Cross-Section

2021 ◽  
Vol 11 (9) ◽  
pp. 4302
Author(s):  
Sungwon Kim ◽  
Hyemin Hong ◽  
Taek Hee Han
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Circular Cross Section ◽  
Material Model ◽  
Maximum Load ◽  
Lateral Force ◽  
Analysis Model ◽  
Reinforced Concrete Column ◽  
The Difference ◽  
Saving Effect

The new supporting structure, internally confined hollow reinforced concrete (ICH RC), was suggested by former researchers. It maintains the material saving effect, which is the advantage of the hollow concrete structure, and it solves the brittle fracture problem of the inner wall by the inner steel pipe to make it into the 3-axis confinement state. However, until now, its design and analysis model has been limited to a circular cross-section. In this study, to expand the applicability, research and development of an ICH RC structure with a polygonal cross-section were performed. The material model was developed by defining the constraint stress in the members of the concrete and deriving a reasonable stress-strain relationship. For the column model, it was developed to predict the behavior of the polygonal ICH RC columns by analyzing the axial force-moment correlation, moment-curvature, and lateral force-displacement relationship. Each model was verified not only by comparing with the results of previous experiments but also by analyzing the results according to parameters. The maximum load and ultimate displacement values through the developed model showed the difference with the experimental results within 6% of mean error. It was verified that the proposed analytical model reasonably reflects the behavior of actual columns.

scholarly journals Note on the selectivity of meshes used by the Santos fishing fleet

1962 ◽  
Vol 12 (1) ◽  
pp. 33-52 ◽  
Author(s):  
I. D. Richardson ◽  
E. P. dos Santos
Keyword(s):  
Normal Form ◽  
Cross Section ◽  
Circular Cross Section ◽  
The Other ◽  
Fishing Fleet ◽  
Fish Market ◽  
The Difference ◽  
The One ◽  
Marketable Size ◽  
The Relationship

In this paper the relationship between total length and girth (circumference) of seven species: "Corvina" (Micropogon furnieri), "Pescada-foguete" (Macrodon ancylodori), "Goete" (Cynoscion petranus), "Tortinha" (Isopisthus parvipinnis), "Cangaua" (Bairdiella ronchus), "Maria Luisa" ("Paralonchurus brasiliensis), and "Oveva" (Larimus breviceps), are expressed in the form of fitted regressions. Theoretical selection lengths assuming, at the one extreme, the mesh to be completely flexible, and at the other extreme to be rigid with axes of 2:3 are calculated. The fish is assumed to be able to adopt a circular cross section. If the fish is not circular but retains its normal form, the difference in the selection length is shown to be little different. The Brazilian commercial boats fishing from Santos are shown to use a mesh which has a very low selection point well below the size of fish which are acceptable on the fish market. The Japanese boats use a much larger mesh, which select fish of marketable size.

Comparison Between Traditional Microchannels Heat Sinks and Microchannels Heat Sinks Based on Biomimical Tendencies

2008 ◽  
Author(s):  
Carlos A. Rubio-Jimenez ◽  
Abel Hernandez-Guerrero ◽  
Cuauhtemoc Rubio-Arana ◽  
Daniela Popescu
Keyword(s):  
Cross Section ◽  
Heat Sink ◽  
Single Phase ◽  
Electronic Devices ◽  
Circular Cross Section ◽  
Heat Sinks ◽  
Channel Cross Section ◽  
Geometrical Parameters ◽  
High Tendency ◽  
Cooling Fluid

In the last few years high-tendency electronic devices have improved to a larger processing capability with smaller physical dimensions. This fact coupled to traditional cooling mechanisms, are not able to dissipate the high heat fluxes generated by these devices (around 200 W/cm2.) Microchannel heat sinks are the new tendency in heat dissipation. Many of the studies done before had used single-phase water as cooling fluid in laminar flow. Operating within this regimen, and using water as the cooling fluid, the dissipated heat flux is not enough to keep optimal operational conditions in the electronic devices. Therefore, this work presents a thermal and hydraulic numerical analysis for a microchannel heat sink with circular cross section, fabricated in a silicon substrate. The channel cross section is variable, being a function of the heat sink longitudinal position, decreasing as the cooling fluid passes through the channel. The ratio between the inlet and outlet diameters is given as a function of the Biomimic tendency. These theories are based on the behavior that nature has for the mass transport in circular ducts. The cooling fluid used in this study is water in single-phase. These microchannels heat sink arrangements are based in the operational and geometrical parameters of previous works developed by several authors on microchannels heat sinks with constant and conventional cross sections.

A General Model for Predicting Low Reynolds Number Flow Pressure Drop in Non-Uniform Microchannels of Non-Circular Cross Section in Continuum and Slip-Flow Regimes

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
M. Akbari ◽  
A. Tamayol ◽  
M. Bahrami
Keyword(s):  
Pressure Drop ◽  
Cross Section ◽  
General Model ◽  
Circular Cross Section ◽  
Numerical Data ◽  
Creeping Flow ◽  
Geometrical Parameters ◽  
Cross Sectional ◽  
Flow Pressure ◽  
The Cross

A general model that predicts single-phase creeping flow pressure drop in microchannels of a noncircular cross section under slip and no-slip regimes is proposed. The model accounts for gradual variations in the cross section and relates the pressure drop to geometrical parameters of the cross section, i.e., area, perimeter, and polar moment of inertia. The accuracy of the proposed model is assessed by comparing the results against experimental and numerical data collected from various studies in the literature for a wide variety of cross-sectional shapes. The suggested model can be used for the design and optimization of microsystems that contain networks of microchannels with noncircular cross sections resulting from different fabrication techniques.

SAF file: It's really three dimensional file

2018 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Prof. Dr. Jamal Aziz Mehdi
Keyword(s):  
Cross Section ◽  
Root Canal ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Circular Motion ◽  
Root Canal Treatment ◽  
Metal Core ◽  
Rotating Blade

The biological objectives of root canal treatment have not changed over the recentdecades, but the methods to attain these goals have been greatly modified. Theintroduction of NiTi rotary files represents a major leap in the development ofendodontic instruments, with a wide variety of sophisticated instruments presentlyavailable (1, 2).Whatever their modification or improvement, all of these instruments have onething in common: they consist of a metal core with some type of rotating blade thatmachines the canal with a circular motion using flutes to carry the dentin chips anddebris coronally. Consequently, all rotary NiTi files will machine the root canal to acylindrical bore with a circular cross-section if the clinician applies them in a strictboring manner

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