The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Debabrata Biswas - One of the best experts on this subject based on the ideXlab platform.
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shielding effects in random large area field Emitters the field enhancement factor distribution and current calculation
Physics of Plasmas, 2018Co-Authors: Rashbihari Rudra, Debabrata BiswasAbstract:A finite-size uniform random distribution of vertically aligned field Emitters on a planar surface is studied under the assumption that the asymptotic field is uniform and parallel to the Emitter axis. A formula for field enhancement factor is first derived for a 2-Emitter system and this is then generalized for N-Emitters placed arbitrarily (line, array, or random). It is found that geometric effects dominate the shielding of field lines. The distribution of field enhancement factor for a uniform random distribution of Emitter locations is found to be closely approximated by an extreme value (Gumbel-minimum) distribution when the mean separation is greater than the Emitter height but is better approximated by a Gaussian for mean separations close to the Emitter height. It is shown that these distributions can be used to accurately predict the current emitted from a large area field Emitter.A finite-size uniform random distribution of vertically aligned field Emitters on a planar surface is studied under the assumption that the asymptotic field is uniform and parallel to the Emitter axis. A formula for field enhancement factor is first derived for a 2-Emitter system and this is then generalized for N-Emitters placed arbitrarily (line, array, or random). It is found that geometric effects dominate the shielding of field lines. The distribution of field enhancement factor for a uniform random distribution of Emitter locations is found to be closely approximated by an extreme value (Gumbel-minimum) distribution when the mean separation is greater than the Emitter height but is better approximated by a Gaussian for mean separations close to the Emitter height. It is shown that these distributions can be used to accurately predict the current emitted from a large area field Emitter.
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shielding effects in random large area field Emitters the field enhancement factor distribution and current calculation
Physics of Plasmas, 2018Co-Authors: Debabrata Biswas, Rashbihari RudraAbstract:A finite-size uniform random distribution of vertically aligned field Emitters on a planar surface is studied under the assumption that the asymptotic field is uniform and parallel to the Emitter axis. A formula for field enhancement factor is first derived for a 2-Emitter system and this is then generalized for N-Emitters placed arbitrarily (line, array, or random). It is found that geometric effects dominate the shielding of field lines. The distribution of field enhancement factor for a uniform random distribution of Emitter locations is found to be closely approximated by an extreme value (Gumbel-minimum) distribution when the mean separation is greater than the Emitter height but is better approximated by a Gaussian for mean separations close to the Emitter height. It is shown that these distributions can be used to accurately predict the current emitted from a large area field Emitter.
Xiaohong Zhang - One of the best experts on this subject based on the ideXlab platform.
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novel strategy to develop exciplex Emitters for high performance oleds by employing thermally activated delayed fluorescence materials
Advanced Functional Materials, 2016Co-Authors: Jiaxiong Chen, Caijun Zheng, Dongyang Chen, Xuemei Ou, Yuping Dong, Fan Li, Kai Wang, Xiaohong ZhangAbstract:To develop high-performance thermally activated delayed fluorescence (TADF) exciplex Emitters, a novel strategy of introducing a single-molecule TADF Emitter as one of the constituting materials has been presented. Such a new type of exciplex TADF Emitter will have two reverse intersystem crossing (RISC) routes on both the pristine TADF molecules and the exciplex Emitters, benefiting the utilization of triplet excitons. Based on a newly designed and synthesized single-molecule TADF Emitter MAC, a highly efficient exciplex Emitter MAC:PO-T2T has been obtained. The device based on MAC:PO-T2T with a weight ratio of 7:3 exhibits a low turn-on voltage of 2.4 V, high maximum efficiency of 52.1 cd A−1 (current efficiency), 45.5 lm W−1 (power efficiency), and 17.8% (external quantum efficiency, EQE), as well as a high EQE of 12.3% at a luminance of 1000 cd m−2. The device shows the best performance among reported organic light-emitting devices based on exciplex Emitters. Such high-efficiency and low-efficiency roll-off should be ascribed to the additional reverse intersystem crossing process on the MAC molecules, showing the advantages of the strategy described in this study.
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prediction and design of efficient exciplex Emitters for high efficiency thermally activated delayed fluorescence organic light emitting diodes
Advanced Materials, 2015Co-Authors: Zhan Chen, Caijun Zheng, Xuemei Ou, Fan Li, Xiaohong ZhangAbstract:: High-efficiency, thermally activated delayed-fluorescence organic light-emitting diodes based on exciplex Emitters are demonstrated. The best device, based on a TAPC:DPTPCz Emitter, shows a high external quantum efficiency of 15.4%. Strategies for predicting and designing efficient exciplex Emitters are also provided. This approach allow prediction and design of efficient exciplex Emitters for achieving high-efficiency organic light-emitting diodes, for future use in displays and lighting applications.
Rashbihari Rudra - One of the best experts on this subject based on the ideXlab platform.
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shielding effects in random large area field Emitters the field enhancement factor distribution and current calculation
Physics of Plasmas, 2018Co-Authors: Rashbihari Rudra, Debabrata BiswasAbstract:A finite-size uniform random distribution of vertically aligned field Emitters on a planar surface is studied under the assumption that the asymptotic field is uniform and parallel to the Emitter axis. A formula for field enhancement factor is first derived for a 2-Emitter system and this is then generalized for N-Emitters placed arbitrarily (line, array, or random). It is found that geometric effects dominate the shielding of field lines. The distribution of field enhancement factor for a uniform random distribution of Emitter locations is found to be closely approximated by an extreme value (Gumbel-minimum) distribution when the mean separation is greater than the Emitter height but is better approximated by a Gaussian for mean separations close to the Emitter height. It is shown that these distributions can be used to accurately predict the current emitted from a large area field Emitter.A finite-size uniform random distribution of vertically aligned field Emitters on a planar surface is studied under the assumption that the asymptotic field is uniform and parallel to the Emitter axis. A formula for field enhancement factor is first derived for a 2-Emitter system and this is then generalized for N-Emitters placed arbitrarily (line, array, or random). It is found that geometric effects dominate the shielding of field lines. The distribution of field enhancement factor for a uniform random distribution of Emitter locations is found to be closely approximated by an extreme value (Gumbel-minimum) distribution when the mean separation is greater than the Emitter height but is better approximated by a Gaussian for mean separations close to the Emitter height. It is shown that these distributions can be used to accurately predict the current emitted from a large area field Emitter.
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shielding effects in random large area field Emitters the field enhancement factor distribution and current calculation
Physics of Plasmas, 2018Co-Authors: Debabrata Biswas, Rashbihari RudraAbstract:A finite-size uniform random distribution of vertically aligned field Emitters on a planar surface is studied under the assumption that the asymptotic field is uniform and parallel to the Emitter axis. A formula for field enhancement factor is first derived for a 2-Emitter system and this is then generalized for N-Emitters placed arbitrarily (line, array, or random). It is found that geometric effects dominate the shielding of field lines. The distribution of field enhancement factor for a uniform random distribution of Emitter locations is found to be closely approximated by an extreme value (Gumbel-minimum) distribution when the mean separation is greater than the Emitter height but is better approximated by a Gaussian for mean separations close to the Emitter height. It is shown that these distributions can be used to accurately predict the current emitted from a large area field Emitter.
Bo Zhou - One of the best experts on this subject based on the ideXlab platform.
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Influence of operating pressure on Emitter anti-clogging performance of drip irrigation system with high-sediment water
Agricultural Water Management, 2019Co-Authors: Yang Xiao, Yunkai Li, Bo Zhou, Ji Feng, Tahir MuhammadAbstract:Abstract Reducing Emitters operating pressure has been widely acknowledged as one of the most effective approach to reduce drip irrigation system maintenance and operation costs. However, utilization of low-quality water, such as high-sediment water, reclaimed water, and brackish water, inevitably increases the Emitters clogging risks. To examine the influence of different pressure levels on Emitter clogging behavior and regulation path, an in-situ accelerated experiment of Emitter clogging with high-sediment water was conducted with five operating pressure levels. The experiment was conducted from July 15, 2016, to October 15, 2016 with a total running time of 720 h. The results showed that Emitter anti-clogging capability was gradually decreased as the operating pressure decreased below 100 to 60 kPa and was significant decreased as the operating pressure decreased below 60 to 40 kPa or lower. Therefore, the operating pressure should be kept above 60 kPa to maintain the favorable Emitter anti-clogging performance. The change of the operating pressure directly and indirectly influenced the formation of clogging substance in the Emitters. In addition, at different operating pressures, the anti-clogging performance parameters discharge ratio variation (Dra), coefficient of uniformity (CU), statistical uniformity coefficient (Us), Emitter discharge variation (qvar), clogging substance within Emitters (CSE) and clogging substance within laterals (CSL) were linearly correlated with anti-clogging performance parameters (Dra, CU, Us, qvar, CSE, CSL) of 100 kPa. Therefore, basing the Dra, CU, Us, qvar, CSE and CSL at 100 kPa, a simple linear model was established to predict anti-clogging performance parameters at the different pressures e.g. 20, 40, 60 and 80 kPa. This study could provide technical support for the application and promotion of the drip irrigation system with high-sediment water.
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effects of microbial community variation on bio clogging in drip irrigation Emitters using reclaimed water
Agricultural Water Management, 2017Co-Authors: Bo Zhou, Tianzhi Wang, Vincent F BraltsAbstract:Abstract Drip irrigation Emitter clogging is one of the key barriers to the development and application of reclaimed water drip irrigation technology. Reclaimed water typically contains large amounts of bacteria, and their excretions, the sticky extracellular polymeric substances (EPS). Indeed, different amounts and types of microorganisms affect drip irrigation Emitter clogging, especially bio-clogging process, via excretive EPS. Therefore, it is important to study the dynamic microbial community structure and its effect on the Emitter bio-clogging process. In this paper, a drip irrigation experiment using reclaimed water was carried out. Phospholipid fatty acids (PLFAs) in biofilm (bio-clogging substance) were taken as the biomarker of microbial community inside Emitters, and the dynamic variation of microbial community in drip irrigation Emitter and its effect on the clogging process were studied. The results showed that the microbial growth of biofilms inside 9 types of drip irrigation Emitters could enhance Emitter clogging, and the PLFAs showed S-shaped pattern with Emitter clogging degrees (R2 > 0.95, p
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eight Emitters clogging characteristics and its suitability under on site reclaimed water drip irrigation
Irrigation Science, 2014Co-Authors: Yiting Pei, Bo Zhou, Yaoze Liu, Ze Shi, Yinguang JiangAbstract:Drip irrigation is the most effective and reliable method for reclaimed water irrigation. The water usually contains a lot of suspended particles, metal salt ions, organisms and microbial communities, which will enhance the possibility of Emitter clogging or more complex clogging mechanism. Emitter clogging has become one of the key problems to the application and popularization of the drip irrigation technology. In this paper, we selected four kinds of pressure-compensating Emitters and four kinds of non-pressure-compensating Emitters, and executed the experiment of drip irrigation with on-site reclaimed water treated with cyclic activated sludge system (CASS). The Emitter discharge ratio variation (Dra), coefficient of uniformity (CU) and clogging rate distribution were analyzed to evaluate the Emitter clogging characteristics after eliminating the effect of temperature and pressure on the Emitter outflow by data correction. The results showed that Dra and CU varied in three periods as system operation. The beginning of experiment was the fluctuated balance period, Dra and CU recurrent fluctuated in 5 %, and the Emitters clogged at some spots after the system run 36–48 h. Then the two parameters varied linearly in 60–108 h, tuning into the initiate linear period, as the non-pressure-compensating Emitters got an obvious linear change than the pressure-compensating ones with the gradient changed from −0.094 to 0.042 and −0.073 to 0.047, respectively. Some of the Emitters have a significant difference on these two parameters at this stage. After the restarting in the second year, Dra and CU decreased sharply. The maximum decrement was, respectively, 9.6 and 10.7 %. Then they varied in line with a greater slope degree as all Emitters reached the significant level, the gradient ranges were −0.176 to 0.115 and −0.216 to 0.117, respectively. This stage was called the accelerated linear period. Seriously clogged and completely clogged Emitters appeared, and both Dra and CU dropped down to 38.7 and 41.5 %. Various degrees of clogged Emitters often emerged in the end part of lateral at first then propelled to the head gradually, the completely clogged Emitters in the end accounted for more than 73.0 % when the system run 540 h. Comprehensively considered, the pressure-compensating Emitters and cusp-shaped saw-tooth non-pressure-compensating Emitters with short flow path are recommended in reclaimed water drip irrigation. These researches are aimed to provide references explaining the Emitter clogging mechanism of reclaimed water drip irrigation as well as its technological application and popularization.
Richard G Forbes - One of the best experts on this subject based on the ideXlab platform.
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physical electrostatics of small field Emitter arrays clusters
Journal of Applied Physics, 2016Co-Authors: Richard G ForbesAbstract:This paper aims to improve qualitative understanding of electrostatic influences on apex field enhancement factors (AFEFs) for small field Emitter arrays/clusters. Using the “floating sphere at Emitter-plate potential” (FSEPP) model, it re-examines the electrostatics and mathematics of three simple systems of identical post-like Emitters. For the isolated Emitter, various approaches are noted. An adequate approximation is to consider only the effects of sphere charges and (for significantly separated Emitters) image charges. For the 2-Emitter system, formulas are found for charge-transfer (“charge-blunting”) effects and neighbor-field effects, for widely spaced and for “sufficiently closely spaced” Emitters. Mutual charge-blunting is always the dominant effect, with a related (negative) fractional AFEF-change δtwo. For sufficiently small Emitter spacing c, |δtwo| varies approximately as 1/c; for large spacing, |δtwo| decreases as 1/c3. In a 3-Emitter equispaced linear array, differential charge-blunting a...
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physical electrostatics of small field Emitter arrays clusters
arXiv: Mesoscale and Nanoscale Physics, 2016Co-Authors: Richard G ForbesAbstract:This paper improves understanding of electrostatic influences on apex field enhancement factors (AFEFs) for small field Emitter arrays. Using the "floating sphere at Emitter-plate potential" (FSEPP) model, it re-examines the electrostatics and mathematics of three simple systems of identical post-like Emitters. For the isolated Emitter, various approaches are noted. On need consider only the effects of sphere charges and (for separated Emitters) image charges. For the 2-Emitter system, formulas are found for "charge-blunting" and "neighbour-field" effects, for widely spaced and "sufficiently closely spaced" Emitters. Mutual charge-blunting is always dominant, with a related (negative) fractional AFEF-change {\delta}_two. For sufficiently small Emitter spacing c, |{\delta}_two| varies as 1/c; for large spacing, |{\delta}_two| decreases as 1/c^3. In a 3-Emitter linear array, differential charge-blunting and differential neighbor-field effects occur, but the former are dominant, and cause the "exposed" outer Emitters to have higher AFEF ({\gamma}_0) than the central Emitter ({\gamma}_1). Formulas are found for the exposure ratio {\Xi}={\gamma}_0/{\gamma}_1, for large and for sufficiently small separations. The FSEPP model for an isolated Emitter has accuracy around 30%. Line-charge models (LCMs) are an alternative, but an apparent difficulty with recent LCM models is identified. Better descriptions of array electrostatics may involve developing good fitting equations for AFEFs derived from accurate numerical solution of Laplace's equation, perhaps with equation form(s) guided qualitatively by FSEPP-model results. In existing fitting formulas, the AFEF-reduction decreases exponentially as c increases, which differs from FSEPP-model formulas. FSEPP models might provide a useful guide to the qualitative behaviour of small field Emitter clusters larger than those investigated.
