Power Dependence and Turn-On Dynamics of Polymer Photocells - Extracting Mobilities and Analyzing Morphologies

2005 ◽  
Vol 871 ◽  
Author(s):  
Noam Rappaport ◽  
Nir Tessler
Keyword(s):  
Simple Technique ◽  
Analytic Description ◽  
Power Dependence ◽  
Measured Intensity ◽  
Semiconducting Polymer ◽  
Charge Effects ◽  
Intensity Dependence ◽  
Turn On ◽  
Independent Verification ◽  
Good Agreement

AbstractWe present an analytic description for the loss of photocurrent efficiency at moderate light intensities and demonstrate a simple technique for extracting the mobility of electrons in semiconducting polymer layers. The underlying theoretical analysis, which is based on a simple drift-recombination scheme, shows good agreement with the measured intensity dependent photocurrent quantum efficiency. The electron mobility extraction is demonstrated for pristine MEH-PPV. The same physical framework is then used to describe the switch on of the photocurrent and the buildup of electron and hole concentrations inside the device. By analyzing the time evolution of the measured photocurrent transient we find an independent verification for the results extracted from the intensity dependence measurements. We use the combination of theoretical and experimental study to discuss the role recombination and space charge effects in reducing photocurrent efficiency.

scholarly journals Role of base strength, cluster structure and charge in sulfuric-acid-driven particle formation

2019 ◽  
Vol 19 (15) ◽  
pp. 9753-9768 ◽  
Author(s):  
Nanna Myllys ◽  
Jakub Kubečka ◽  
Vitus Besel ◽  
Dina Alfaouri ◽  
Tinja Olenius ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Cluster Structure ◽  
Particle Formation ◽  
Charge Effects ◽  
Low Concentrations ◽  
Base Strength ◽  
Small Clusters ◽  
Ammonia Medium ◽  
Good Agreement

Abstract. In atmospheric sulfuric-acid-driven particle formation, bases are able to stabilize the initial molecular clusters and thus enhance particle formation. The enhancing potential of a stabilizing base is affected by different factors, such as the basicity and abundance. Here we use weak (ammonia), medium strong (dimethylamine) and very strong (guanidine) bases as representative atmospheric base compounds, and we systematically investigate their ability to stabilize sulfuric acid clusters. Using quantum chemistry, we study proton transfer as well as intermolecular interactions and symmetry in clusters, of which the former is directly related to the base strength and the latter to the structural effects. Based on the theoretical cluster stabilities and cluster population kinetics modeling, we provide molecular-level mechanisms of cluster growth and show that in electrically neutral particle formation, guanidine can dominate formation events even at relatively low concentrations. However, when ions are involved, charge effects can also stabilize small clusters for weaker bases. In this case the atmospheric abundance of the bases becomes more important, and thus ammonia is likely to play a key role. The theoretical findings are validated by cluster distribution experiments, as well as comparisons to previously reported particle formation rates, showing a good agreement.

scholarly journals Role of Base Strength, Cluster Structure and Charge in Sulfuric Acid-Driven Particle Formation

2019 ◽  
Author(s):  
Nanna Myllys ◽  
Jakub Kubečka ◽  
Vitus Besel ◽  
Dina Alfaouri ◽  
Tinja Olenius ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Cluster Structure ◽  
Particle Formation ◽  
Charge Effects ◽  
Low Concentrations ◽  
Base Strength ◽  
Small Clusters ◽  
Ammonia Medium ◽  
Good Agreement

Abstract. In atmospheric sulfuric acid-driven particle formation, bases are able to stabilize the initial molecular clusters, and thus enhance particle formation. The enhancing potential of a stabilizing base is affected by different factors, such as the basicity and abundance. Here we use weak (ammonia), medium strong (dimethylamine) and very strong (guanidine) bases as representative atmospheric base compounds, and systematically investigate their ability to stabilize sulfuric acid clusters. Using quantum chemistry, we study proton transfer as well as intermolecular interactions and symmetry in clusters, of which the former is directly related to the base strength and the latter to the structural effects. Based on the theoretical cluster stabilities and cluster population kinetics modeling, we provide molecular-level mechanisms of cluster growth and show that in electrically neutral particle formation, guanidine can dominate formation events even at relatively low concentrations. However, when ions are involved, charge effects can stabilize small clusters also for weaker bases. In this case the atmospheric abundance of the bases becomes more important, and thus ammonia is likely to play a key role. The theoretical findings are validated by cluster distribution experiments, as well as comparisons to previously reported particle formation rates, showing a good agreement.

scholarly journals An Approximate Linear Analysis of Structures Utilizing Incremental Loading of Force Method

2020 ◽  
Vol 4 (6) ◽  
pp. 37-44
Author(s):  
Najmadeen Mohammed Saeed ◽  
Ahmed Aulla Manguri
Keyword(s):  
Simple Technique ◽  
Geometrical Property ◽  
Current Approach ◽  
Geometrically Nonlinear ◽  
Force Method ◽  
Internal Forces ◽  
Small Change ◽  
Nodal Displacements ◽  
Good Agreement ◽  
Incremental Loading

A relatively simple technique has been introduced in this paper. The approach is based on the Linear Force Method (FM) with discretion of the applied loads to the subsequence steps and updating coordinates in each iteration to have new geometrical property. The accuracy of the technique depends on the size of the discretion which depends on the number of iterations. A small change in the configuration could hugely affect the displacement and internal forces in geometrically nonlinear structures, that’s why the current approach is vital. The proposed technique is validated with other techniques of nonlinear analysis of the structures with a very good agreement in both terms of external nodal displacements and internal bar forces.

scholarly journals Impact Energy and Angular Dependence of L X-ray Emission from a Thick Polycrystalline Tungsten Element Induced by 15–25 keV Electrons

Atoms ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 82
Author(s):  
Bhupendra Singh ◽  
Suman Prajapati ◽  
Bhartendu K. Singh ◽  
R. Shanker
Keyword(s):  
Angular Dependence ◽  
Impact Energy ◽  
Intensity Ratio ◽  
Incidence Angle ◽  
Angular Variation ◽  
Measured Intensity ◽  
Polycrystalline Tungsten ◽  
Simulation Results ◽  
The Impact ◽  
Good Agreement

The impact energy and angular dependence of L X-rays of a thick polycrystalline tungsten (W; atomic number, Z = 74) target induced by 15–25 keV electrons has been measured at different angles varying from 15° to 75° at intervals of 5° using a Si PIN photodiode detector. The variation of measured relative intensity of Ll, Lα, Lβ and Lγ characteristic lines as a function of incidence angle is found to be anisotropic and the measured variation compares well with the PENELOPE simulation results. The angular variation of intensity ratio of Ll/Lα and Lβ/Lα shows anisotropic distribution, whereas the angular variation of the Lγ/Lα ratio exhibits almost isotropic distribution within the uncertainty of measurements. These measured ratios are found to be in good agreement with Monte Carlo (MC) calculations. The measured intensity ratios of Lβ/Lα and Lγ/Lα at a given incidence angle show a linear dependence with impact energy and exhibit good agreement with simulation results; however, the measured intensity ratio of Ll/Lα shows a non-linear variation with the impact energy and yields poor agreement with theoretical calculations.

scholarly journals A survey of beach pollution at a seaside resort

1954 ◽  
Vol 52 (1) ◽  
pp. 71-86 ◽  
Author(s):  
B. Moore
Keyword(s):  
Local Authority ◽  
Simple Technique ◽  
Sea Water ◽  
Sampling Point ◽  
Local Charge ◽  
Seaside Resort ◽  
Before And After ◽  
Beach Pollution ◽  
Complex Methods ◽  
Good Agreement

Bacteriological surveys of beach pollution were made at a seaside resort before and after the installation of a new sewer outfall.The presumptive coliform count on samples of sea water was found to be a satisfactory index of contamination, and showed good agreement with sanitary survey and with the results of float-test observations. The faecal coli count was in general constantly related to the results of the presumptive test, but there was some indication that coliform bacilli of the I.A.C. groups persisted or multiplied in the sand around the outfall.The degree of contamination of the sea water at a given sampling point was shown to depend not only on its distance from the outfall but on various meteorological and tidal factors.For bacteriological surveys of beach pollution, it is suggested that a large series of tests by a relatively simple technique is preferable to a more limited investigation by more complex methods.The possibility of laying down bacteriological standards for bathing beaches is discussed. An upper permitted limit of the order of 1000 coliform organisms per 100 ml. would discriminate between areas on the beach investigated which were unsatisfactory by sanitary survey before and after the installation of the new sewerage scheme, and those parts of the beach which were apparently not subject to serious pollution with sewage.I am greatly indebted to Lt.-Col. J. M. Linton Bogle, consulting engineer responsible for the sewerage scheme described, for his interest in and practical help with this investigation; to members of the staff of the local authority concerned for help with sampling, and to Dr A. F. Ollerenshaw and Mr A. Partridge, who were in local charge of the temporary laboratory where the presumptive tests were carried out, in 1950 and 1948 respectively.

scholarly journals An Approximate Linear Analysis of Structures Utilizing Incremental Loading of Force Method

2020 ◽  
Vol 4 (6) ◽  
pp. 37-44
Author(s):  
Najmadeen Mohammed Saeed ◽  
Ahmed Aulla Manguri
Keyword(s):  
Simple Technique ◽  
Geometrical Property ◽  
Current Approach ◽  
Geometrically Nonlinear ◽  
Force Method ◽  
Internal Forces ◽  
Small Change ◽  
Nodal Displacements ◽  
Good Agreement ◽  
Incremental Loading

A relatively simple technique has been introduced in this paper. The approach is based on the Linear Force Method (FM) with discretion of the applied loads to the subsequence steps and updating coordinates in each iteration to have new geometrical property. The accuracy of the technique depends on the size of the discretion which depends on the number of iterations. A small change in the configuration could hugely affect the displacement and internal forces in geometrically nonlinear structures, that’s why the current approach is vital. The proposed technique is validated with other techniques of nonlinear analysis of the structures with a very good agreement in both terms of external nodal displacements and internal bar forces.

Reconfigurable bandstop filter using active frequency selective surface, design and fabrication

Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hamed Babaei ◽  
Seyyed Amir Gohari
Keyword(s):  
Resonant Frequency ◽  
Band Gap ◽  
Frequency Selective Surface ◽  
Pin Diodes ◽  
Frequency Shifts ◽  
Surface Design ◽  
Turn On ◽  
Measurement Results ◽  
Bandstop Filter ◽  
Good Agreement

Abstract In this paper a novel FSS array is proposed, that provides dynamic band-gap in C-band. Inside the band-gap, the FSS acts as a bandstop filter. Outside the band-gap the amplitude of the reflected wave from the FSS array decreases. Therefore, the outside band is very useful in radar cross section (RCS) reduction. In this paper, at first a new FSS unit cell is designed, then in order to achieve the maximum bandwidth (1.2 GHz), dimensions of the cell are optimized. In the next step, the FSS cell is equipped with PIN diodes. Turning the diodes ON or OFF, shifts the resonant frequency of the band-gap electronically. When diodes are OFF, the resonant frequency and −10 dB bandwidth of the FSS are 5.23 and 0.9 GHz respectively. When the diodes turn ON, the resonant frequency shifts to 4.75 GHz over a bandwidth of about 1 GHz. While the band-gap is shifted dynamically, the bandwidth is kept wide, which is the novelty of this paper. In order to validate the design process, an array of active cells consisting of 128 pin diodes was designed, fabricated and then tested. Finally, the simulation and measurement results are compared with each other and a good agreement is observed between them.

Simple Technique for Measuring Air Humidity Using an IBM Microcomputer

1995 ◽  
Vol 209 (2) ◽  
pp. 145-150
Author(s):  
M B Abdul Wahab ◽  
M Z Badros ◽  
A R Ramli
Keyword(s):  
Relative Humidity ◽  
Simple Technique ◽  
Digital Signal ◽  
Digital Data ◽  
Digital Converter ◽  
Air Humidity ◽  
Data Output ◽  
Analogue To Digital ◽  
Relative Humidity Data ◽  
Good Agreement

A thermocouple consisting of copper and constantant wires has been used as a relative humidity detector and was interfaced to an IBM microcomputer. The temperature differences between the wet and dry junction of the thermocouple were used to calibrate the relative humidity of air. The generated e.m.f. signal was amplified and thus converted to a digital signal using an analogue-to-digital converter (ADC). The digital data output of the ADC was then passed to an IBM microcomputer via a programmable peripheral interface (PPI) chip to process, display and store the relative humidity data. The relative humidity profile in the range 23–32°C of the dry bulb temperatures for a specific day can also be plotted and analysed. The measured relative humidity was compared to a commercial humidity meter and showed good agreement.

The Effect of Surface Roughness on Fitting Strength of Shrink Fit Between Ceramic and Metal Elements

1989 ◽  
Vol 111 (3) ◽  
pp. 318-325 ◽  
Author(s):  
K. Kato ◽  
T. Kayaba ◽  
I. Nitta ◽  
S. Shimoda
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Elevated Temperatures ◽  
Simple Technique ◽  
Accurate Estimation ◽  
Metal Elements ◽  
Experimental Values ◽  
Shrink Fit ◽  
Effect Of Surface ◽  
Good Agreement

Shrink fit is a basic and simple technique for joining metal elements. But it is not suitable for ceramic and metal elements, especially at elevated temperatures. For the accurate estimation of fitting strength between ceramic and metal elements, an understanding of the deformation of surface micro-asperities during contact is introduced in this paper. The elastic deformation of a shaft and a cylinder and the elastic-plastic deformation of the asperities were taken into consideration for the theoretical fitting strength. Theoretical estimations of fitting strength between a ceramic shaft and a metal cylinder showed good agreement wtih experimental values in various fitting interferences and at temperatures of 20°C–180°C.

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