171 results on '"device optimization"'
Search Results
2. Emergent role of dynamic optimization in cardiac resynchronization therapy: Systematic review and network meta‐analysis.
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Zsigmond, Előd‐János, Masszi, Richárd, Ehrenberger, Réka, Turan, Caner, Fehérvári, Péter, Gede, Noémi, Hegyi, Péter, Molnár, Zsolt, Trásy, Domonkos, and Duray, Gábor Zoltán
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PATIENT experience ,MATHEMATICAL optimization ,PATIENTS' attitudes ,HEART failure ,ODDS ratio ,CARDIAC pacing - Abstract
Aims: Suboptimal device programming is frequent in non‐responders to cardiac resynchronization therapy (CRT). However, the role of device optimization and the most appropriate technique are still unknown. The aim of our study was to analyse the effect of different CRT optimization techniques within a network meta‐analysis. Methods: A systematic search was conducted on MEDLINE, Embase and CENTRAL for studies comparing outcomes with empirical device settings or optimization using echocardiography, static algorithms or dynamic algorithms. Studies investigating the effect of optimization in non‐responders were also analysed. Results: A total of 17 studies with 4346 patients were included in the quantitative analysis. Of the treatments and outcomes examined, a significant difference was found only between dynamic algorithms and echocardiography, with the former leading to a higher echocardiographic response rate [odds ratio (OR): 2.02, 95% confidence interval (CI) 1.21–3.35], lower heart failure hospitalization rate (OR: 0.75, 95% CI 0.57–0.99) and greater improvement in 6‐minute walk test [mean difference (MD): 45.52 m, 95% credible interval (CrI) 3.91–82.44 m]. We found no significant difference between empirical settings, static algorithms and dynamic algorithms. Seven studies with 228 patients reported response rates after optimization in non‐responders. Altogether, 34.3%–66.7% of initial non‐responders showed improvement after optimization, depending on response criteria. Conclusions: At the time of CRT implantation, dynamic algorithms may serve as a resource‐friendly alternative to echocardiographic optimization, with similar or better mid‐term outcomes. However, their superiority over empirical device settings needs to be investigated in further trials. For non‐responders, CRT optimization should be considered, as the majority of patients experience improvement. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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3. Emergent role of dynamic optimization in cardiac resynchronization therapy: Systematic review and network meta‐analysis
- Author
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Előd‐János Zsigmond, Richárd Masszi, Réka Ehrenberger, Caner Turan, Péter Fehérvári, Noémi Gede, Péter Hegyi, Zsolt Molnár, Domonkos Trásy, and Gábor Zoltán Duray
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cardiac resynchronization therapy ,device optimization ,dynamic algorithms ,echocardiography ,empirical settings ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
Abstract Aims Suboptimal device programming is frequent in non‐responders to cardiac resynchronization therapy (CRT). However, the role of device optimization and the most appropriate technique are still unknown. The aim of our study was to analyse the effect of different CRT optimization techniques within a network meta‐analysis. Methods A systematic search was conducted on MEDLINE, Embase and CENTRAL for studies comparing outcomes with empirical device settings or optimization using echocardiography, static algorithms or dynamic algorithms. Studies investigating the effect of optimization in non‐responders were also analysed. Results A total of 17 studies with 4346 patients were included in the quantitative analysis. Of the treatments and outcomes examined, a significant difference was found only between dynamic algorithms and echocardiography, with the former leading to a higher echocardiographic response rate [odds ratio (OR): 2.02, 95% confidence interval (CI) 1.21–3.35], lower heart failure hospitalization rate (OR: 0.75, 95% CI 0.57–0.99) and greater improvement in 6‐minute walk test [mean difference (MD): 45.52 m, 95% credible interval (CrI) 3.91–82.44 m]. We found no significant difference between empirical settings, static algorithms and dynamic algorithms. Seven studies with 228 patients reported response rates after optimization in non‐responders. Altogether, 34.3%–66.7% of initial non‐responders showed improvement after optimization, depending on response criteria. Conclusions At the time of CRT implantation, dynamic algorithms may serve as a resource‐friendly alternative to echocardiographic optimization, with similar or better mid‐term outcomes. However, their superiority over empirical device settings needs to be investigated in further trials. For non‐responders, CRT optimization should be considered, as the majority of patients experience improvement.
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- 2024
- Full Text
- View/download PDF
4. Towards the CdS/SnSe solar cell optimization: Understanding the transport mechanisms
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A. Carrillo-Osuna, F.J. Sánchez-Rodríguez, K.G. Rodriguez-Osorio, I. Montoya De Los Santos, J.P. Morán-Lázaro, M. Ojeda-Martínez, Laura M. Pérez, David Laroze, and Maykel Courel
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SnSe solar cell ,Modeling and simulation ,Loss transport mechanisms ,Device optimization ,Physics ,QC1-999 - Abstract
In this work, numerical simulation results on SnSe solar cells are presented. The influence of loss mechanisms such as radiative recombination, SnSe bulk recombination, and CdS/SnSe interface recombination on the device is studied in detail under and without the influence of resistances for the first time. In the first step, our model is validated by accurately reproducing the experimental available data. We found that non-radiative recombination originated by SnSe bulk defects in combination with high series resistances are dominant loss mechanisms, resulting in efficiency values lower than 2 %. In addition, the important role of the CdS/SnSe interface is also evidenced, since SnSe solar cells without bulk defects and resistances would not be able to overcome the efficiency barrier of 10 % because of the cliff-like band alignment. The role of each loss mechanism on SnSe solar cell performance was studied as a function of material thicknesses, carrier concentrations, bulk and interface defects, and resistances for device optimization. We demonstrated that conversion efficiency of 21.8 % with an open-circuit voltage, short-circuit current density, and fill factor values of 0.82 V, 31.6 mA/cm2, 84.6 %, respectively can be achieved in the optimized device under the standard conditions of AM 1.5G illumination and 300 K.
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- 2024
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5. Scrutinizing transport phenomena and recombination mechanisms in thin film Sb2S3 solar cells
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Z. Younsi, F. Meddour, H. Bencherif, M. Khalid Hossain, Latha Marasamy, P. Sasikumar, M. S. Revathy, Suresh Ghotekar, Mohammad R. Karim, Manikandan Ayyar, Rajesh Haldhar, and Mirza H. K. Rubel
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Sb2S3 solar cells ,Recombination mechanisms ,Analytical modeling ,Device optimization ,Medicine ,Science - Abstract
Abstract The Schockley–Quisser (SQ) limit of 28.64% is distant from the Sb2S3 solar cells’ record power conversion efficiency (PCE), which is 8.00%. Such poor efficiency is mostly owing to substantial interface-induced recombination losses caused by defects at the interfaces and misaligned energy levels. The endeavor of this study is to investigate an efficient Sb2S3 solar cell structure via accurate analytical modeling. The proposed model considers different recombination mechanisms such as non-radiative recombination, Sb2S3/CdS interface recombination, Auger, SRH, tunneling-enhanced recombination, and their combined impact on solar cell performance. This model is verified against experimental work (Glass/ITO/CdS/Sb2S3/Au) where a good coincidence is achieved. Several parameters effects such as thickness, doping, electronic affinity, and bandgap are scrutinized. The effect of both bulk traps located in CdS and Sb2S3 on the electrical outputs of the solar cell is analyzed thoroughly. Besides, a deep insight into the effect of interfacial traps on solar cell figures of merits is gained through shedding light into their relation with carriers’ minority lifetime, diffusion length, and surface recombination velocity. Our research findings illuminate that the primary contributors to Sb2S3 degradation are interfacial traps and series resistance. Furthermore, achieving optimal band alignment by fine-tuning the electron affinity of CdS to create a Spike-like conformation is crucial for enhancing the immunity of the device versus the interfacial traps. In our study, the optimized solar cell configuration (Glass/ITO/CdS/Sb2S3/Au) demonstrates remarkable performance, including a high short-circuit current (J SC ) of 47.9 mA/cm2, an open-circuit voltage (V OC ) of 1.16 V, a fill factor (FF) of 54%, and a notable improvement in conversion efficiency by approximately 30% compared to conventional solar cells. Beyond its superior performance, the optimized Sb2S3 solar cell also exhibits enhanced reliability in mitigating interfacial traps at the CdS/Sb2S3 junction. This improved reliability can be attributed to our precise control of band alignment and the fine-tuning of influencing parameters.
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- 2024
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6. Scrutinizing transport phenomena and recombination mechanisms in thin film Sb2S3 solar cells.
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Younsi, Z., Meddour, F., Bencherif, H., Hossain, M. Khalid, Marasamy, Latha, Sasikumar, P., Revathy, M. S., Ghotekar, Suresh, Karim, Mohammad R., Ayyar, Manikandan, Haldhar, Rajesh, and Rubel, Mirza H. K.
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SOLAR cells ,TRANSPORT theory ,PHOTOVOLTAIC power systems ,THIN films ,SURFACE recombination ,OPEN-circuit voltage - Abstract
The Schockley–Quisser (SQ) limit of 28.64% is distant from the Sb
2 S3 solar cells' record power conversion efficiency (PCE), which is 8.00%. Such poor efficiency is mostly owing to substantial interface-induced recombination losses caused by defects at the interfaces and misaligned energy levels. The endeavor of this study is to investigate an efficient Sb2 S3 solar cell structure via accurate analytical modeling. The proposed model considers different recombination mechanisms such as non-radiative recombination, Sb2 S3 /CdS interface recombination, Auger, SRH, tunneling-enhanced recombination, and their combined impact on solar cell performance. This model is verified against experimental work (Glass/ITO/CdS/Sb2 S3 /Au) where a good coincidence is achieved. Several parameters effects such as thickness, doping, electronic affinity, and bandgap are scrutinized. The effect of both bulk traps located in CdS and Sb2 S3 on the electrical outputs of the solar cell is analyzed thoroughly. Besides, a deep insight into the effect of interfacial traps on solar cell figures of merits is gained through shedding light into their relation with carriers' minority lifetime, diffusion length, and surface recombination velocity. Our research findings illuminate that the primary contributors to Sb2 S3 degradation are interfacial traps and series resistance. Furthermore, achieving optimal band alignment by fine-tuning the electron affinity of CdS to create a Spike-like conformation is crucial for enhancing the immunity of the device versus the interfacial traps. In our study, the optimized solar cell configuration (Glass/ITO/CdS/Sb2 S3 /Au) demonstrates remarkable performance, including a high short-circuit current (JSC ) of 47.9 mA/cm2 , an open-circuit voltage (VOC ) of 1.16 V, a fill factor (FF) of 54%, and a notable improvement in conversion efficiency by approximately 30% compared to conventional solar cells. Beyond its superior performance, the optimized Sb2 S3 solar cell also exhibits enhanced reliability in mitigating interfacial traps at the CdS/Sb2 S3 junction. This improved reliability can be attributed to our precise control of band alignment and the fine-tuning of influencing parameters. [ABSTRACT FROM AUTHOR]- Published
- 2024
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- View/download PDF
7. Charge balance in OLEDs: Optimization of hole injection layer using novel p‐dopants.
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Xie, Menglan, Pang, Huiqing, Wang, Jing, Cui, Zhihao, Ding, Hualong, Zheng, Renjie, Kwong, Ray, and Xia, Sean
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ORGANIC light emitting diodes , *DELAYED fluorescence , *ELECTRON transport , *DIGITAL cinematography , *QUANTUM efficiency , *CHARGE carriers - Abstract
Charge balance is one of the most important factors for realizing high performance organic light emitting devices (OLEDs). In this work, we provide a novel strategy to improve the charge balance in OLEDs by optimizing the hole injection layer (HIL) as well as the electron transporting layer (ETL) and thereby controlling the charge carrier supplies in the device. First, we develop a p‐dopant material (PD02), with a lowest unoccupied molecular orbit (LUMO) of −4.63 eV, much shallower than that of the commercial material (PD01) of which the LUMO is −5.04 eV. Nevertheless, this enables us to modulate the supply of holes to the emissive layer through tuning doping concentration. We demonstrate that device performances are significantly improved by employing such a scheme. With a 23% molar doping of PD02, a bottom emission red OLED achieves an external quantum efficiency (EQE) of over 30%, an operating voltage of 3.4 V and a LT95 ~15,000 h at 10 mA/cm2, with a Digital Cinema Initiative P3 (DCI‐P3) chromaticity of CIE (X, Y) = (0.68, 0.32). Moreover, the efficiency roll‐off is suppressed up till ~3500 cd/m2, a desirable feature in display applications. The lateral conductivity of by using such HIL is also found to be much lower than that of PD01, resulting in reduced crosstalk among RGB pixels. Next, a new electron transporting material (ETM‐02) with a deep LUMO of −2.86 eV is also introduced to further optimize the charge balance. Although devices with ETM‐02 shows lower voltage and higher EQE, lifetime is compromised. In order to improve lifetime, additional fine tuning of the charge balance is essential. Finally, a second p‐dopant PD03 with a LUMO of −4.91 eV is added to the HIL to further extend the modulation flexibility in the hole injection. A double‐layer HIL consisting of 8 nm of HTM:16% PD02 and 2 nm of HTM:3% PD03, where the former is in contact with anode, is adopted in the device structure. The bottom emission deep red device achieve EQE over 30%, an operating voltage of 3.2 V and an improved LT95 ~13,000 h at 10 mA/cm2 with a BT.2020 range chromaticity of CIE (X, Y) = (0.701, 0.299). In the double HIL configuration, the introduction of PD03 provides one more parameter for tuning and therefore improves the overall device performances. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Theoretical analysis of earth-abundant solar cell based on green absorber CuFeO2.
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Prasad, D., Anitha, G., Leo, L. Megalan, and Kumar, Atul
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SOLAR cells , *PHOTOVOLTAIC power systems , *SOLAR energy , *SURFACE recombination , *CONDUCTION bands , *CHARGE carrier mobility , *IRON oxides , *FERRIC oxide - Abstract
Huge advancements in the understanding of photovoltaic (PV) physics have been made, but still, PV has not overtaken conventional energy sources due to PV materials cost, toxicity, and stability concerns. In the pursuit of discovering a new solar energy harvester which satisfies criteria such as low cost, earth-abundance, non-toxicity, high efficiency and long-term stability, extensive research has been conducted on the potential of copper iron oxide (CuFeO2), also known as delafossite oxide. CuFeO2 possesses optimal bandgap (1.5 eV), with a high absorption coefficient and carrier mobility, suitable for potentially cost-effective solar cells. Theoretical modelling based on the optical and electrical characteristics of the CuFeO2 system is performed here on delafossite CuFeO2 to examine its photovoltaic performance. We explored various buffer counterparts for CuFeO2 absorber, and a stack of p–n+–n++is simulated for device optimization. ZnO showed zero conduction band offset with CuFeO2 and a corresponding efficiency of 28% for CuFeO2/ZnO/ITO (p–n+–n++) device. The optimal range of crucial design parameters, such as doping profile, absorber thickness, surface recombination velocity, back contact work function, resistances, and bulk defects, that allow CuFeO2 solar cells to reach power conversion efficiencies above 25% are quantified. The spectrum loss (thermalization and non-absorption loss) stands at 59.6%, extrinsic recombination loss at 12.3%, and the performance ceiling of CuFeO2 at 28.1%. Theoretical analysis shows that the maximum achievable efficiency of 28% is close to the Shockley–Queisser (S–Q) limit and comparable to contemporary inorganic solar cells. The findings presented in this study are anticipated to stimulate experimentalists to fabricate stable, high-efficiency CuFeO2-based thin film solar cells. [ABSTRACT FROM AUTHOR]
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- 2023
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9. Theoretical analysis of earth-abundant solar cell based on green absorber CuFeO2.
- Author
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Prasad, D., Anitha, G., Leo, L. Megalan, and Kumar, Atul
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SOLAR cells ,PHOTOVOLTAIC power systems ,SOLAR energy ,SURFACE recombination ,CONDUCTION bands ,CHARGE carrier mobility ,IRON oxides ,FERRIC oxide - Abstract
Huge advancements in the understanding of photovoltaic (PV) physics have been made, but still, PV has not overtaken conventional energy sources due to PV materials cost, toxicity, and stability concerns. In the pursuit of discovering a new solar energy harvester which satisfies criteria such as low cost, earth-abundance, non-toxicity, high efficiency and long-term stability, extensive research has been conducted on the potential of copper iron oxide (CuFeO
2 ), also known as delafossite oxide. CuFeO2 possesses optimal bandgap (1.5 eV), with a high absorption coefficient and carrier mobility, suitable for potentially cost-effective solar cells. Theoretical modelling based on the optical and electrical characteristics of the CuFeO2 system is performed here on delafossite CuFeO2 to examine its photovoltaic performance. We explored various buffer counterparts for CuFeO2 absorber, and a stack of p–n+ –n++ is simulated for device optimization. ZnO showed zero conduction band offset with CuFeO2 and a corresponding efficiency of 28% for CuFeO2 /ZnO/ITO (p–n+ –n++ ) device. The optimal range of crucial design parameters, such as doping profile, absorber thickness, surface recombination velocity, back contact work function, resistances, and bulk defects, that allow CuFeO2 solar cells to reach power conversion efficiencies above 25% are quantified. The spectrum loss (thermalization and non-absorption loss) stands at 59.6%, extrinsic recombination loss at 12.3%, and the performance ceiling of CuFeO2 at 28.1%. Theoretical analysis shows that the maximum achievable efficiency of 28% is close to the Shockley–Queisser (S–Q) limit and comparable to contemporary inorganic solar cells. The findings presented in this study are anticipated to stimulate experimentalists to fabricate stable, high-efficiency CuFeO2 -based thin film solar cells. [ABSTRACT FROM AUTHOR]- Published
- 2023
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10. Design Simulation of Chalcogenide Absorber‐Based Heterojunction Solar Cell Yielding Manifold Enhancement in Efficiency.
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Islam, Md Tasirul and Thakur, Awalendra Kumar
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PHOTOVOLTAIC power systems , *SOLAR cells , *COPPER-zinc alloys , *OPEN-circuit voltage , *BUFFER layers , *CARRIER density , *HETEROJUNCTIONS - Abstract
A large efficiency improvement, ≈4.5 times, in a solar cell based on earth‐abundant low‐cost SnS absorber with configuration glass/Mo/SnS/CdS/i‐ZnO/AZO/Al is reported in sharp contrast to prior experimental reports in the literature. Efficiency enhancement is attributed to tailored design at the absorber/buffer interface implemented via two‐step design modification vis‐à‐vis experimental benchmark. Design tailoring using simulation comprises substitution of sulfur composition in SnS by Se followed by replacing CdS buffer layer with wide bandgap, nontoxic Zn (O, S). The effect of sulfur composition variation by Se (i.e., SnS1−xSex) indicates an optimal Se mole fraction (x = 0.4) exhibiting maximum efficiency. In addition, optimization of the thickness, carrier density, and bulk defect density of the SnS1−xSex absorber result in an improved design. Replacing CdS buffer layer by ZnO1−ySy in SnS absorber‐based solar cell results in substantial improvement in device parameters; open circuit voltage (VOC) of ≈86% and current density (JSC) of ≈78% due to optimal band alignment at the SnS1−xSex/ZnO1−ySy heterojunction. It occurs when the sulfur mole fraction is 60% in the absorber layer and 70% in the buffer layer causing efficiency to rise to ≈17.87%. An optimal design comprising all the parameters including metal back contact work function, series and shunt resistance deliver an efficiency of ≈19.2%. [ABSTRACT FROM AUTHOR]
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- 2023
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11. Numerical simulation and optimal design of perovskite solar cell based on sensitized zinc oxide electron-transport layer
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Chouk, Rihab, Aguir, Chadlia, Tala-Ighil, Razika, Al-Hada, Naif Mohammed, Al-Asbahi, Bandar Ali, and Khalfaoui, Mohamed
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- 2024
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12. Maximizing QRS duration reduction in contemporary cardiac resynchronization therapy is feasible and shorter QRS duration is associated with better clinical outcome.
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Borgquist, Rasmus, Marinko, Sofia, Platonov, Pyotr G, Wang, Lingwei, Chaudhry, Uzma, Brandt, Johan, and Mörtsell, David
- Abstract
Background: We aimed to evaluate if optimization by maximizing QRS duration (QRSd) reduction is feasible in an all-comer cardiac resynchronization therapy (CRT) population, and if reduced, QRSd is associated with a better clinical outcome. Methods: Patients with LBBB receiving CRT implants during the period 2015–2020 were retrospectively evaluated. Implants from 2015–2017 were designated as controls. Starting from 2018, an active 12-lead electrogram-based optimization of QRSd reduction was implemented (intervention group). QRSd reduction was evaluated in a structured way at various device AV and VV settings, aiming to maximize the reduction. The primary endpoint was a composite of heart failure hospitalization or death from any cause. Results: A total of 254 patients were followed for up to 6 years (median 2.9 [1.8–4.1]), during which 82 patients (32%) reached the primary endpoint; 53 deaths (21%) and 58 (23%) heart failure hospitalizations. Median QRS duration pre-implant was 162 ms [150–174] and post-implant 146ms [132–160]. Mean reduction in QRS duration was progressively larger for each year during the intervention period, ranging from − 9.5ms in the control group to − 24 in the year 2020 (p = 0.005). QRS reduction > 14 ms (median value) was associated with a lower risk of death or heart failure hospitalization (adjusted HR 0.54 [0.29–0.98] (p = 0.04). Conclusions: Implementing a general strategy of CRT device optimization by aiming for shorter QRS duration is feasible in a structured clinical setting and results in larger reductions in QRS duration post-implant. In patients with a larger QRS reduction, compared to those with a smaller QRS reduction, there is an association with a better clinical outcome. [ABSTRACT FROM AUTHOR]
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- 2023
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13. Design Strategies of 40 nm Split-Gate NOR Flash Memory Device for Low-Power Compute-in-Memory Applications.
- Author
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Yook, Chan-Gi, Kim, Jung Nam, Kim, Yoon, and Shim, Wonbo
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FLASH memory ,CONVOLUTIONAL neural networks ,ARTIFICIAL intelligence - Abstract
The existing von Neumann architecture for artificial intelligence (AI) computations suffers from excessive power consumption and memory bottlenecks. As an alternative, compute-in-memory (CIM) technology has been emerging. Among various CIM device candidates, split-gate NOR flash offers advantages such as a high density and low on-state current, enabling low-power operation, and benefiting from a high level of technological maturity. To achieve high energy efficiency and high accuracy in CIM inference chips, it is necessary to optimize device design by targeting low power consumption at the device level and surpassing baseline accuracy at the system level. In split-gate NOR flash, significant factors that can cause CIM inference accuracy drop are the device conductance variation, caused by floating gate charge variation, and a low on-off current ratio. Conductance variation generally has a trade-off relationship with the on-current, which greatly affects CIM dynamic power consumption. In this paper, we propose strategies for designing optimal devices by adjusting oxide thickness and other structural parameters. As a result of setting T
ox,FG to 13.4 nm, TIPO to 4.6 nm and setting other parameters to optimal points, the design achieves erase on-current below 2 μA, program on-current below 10 pA, and off-current below 1 pA, while maintaining an inference accuracy of over 92%. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
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14. Holistic Optimization of Trap Distribution for Performance/Reliability in 3-D NAND Flash Using Machine Learning
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Kihoon Nam, Chanyang Park, Hyeok Yun, Jun-Sik Yoon, Hyundong Jang, Kyeongrae Cho, Min Sang Park, Hyun-Chul Choi, and Rock-Hyun Baek
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3D NAND flash ,charge trap nitride ,device optimization ,machine learning ,performance ,reliability ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
A machine learning (ML) method was used to optimize the trap distribution of the charge trap nitride (CTN) to simultaneously improve its performance/reliability (P/R) characteristics, which are tradeoffs in 3-D NAND flash memories. Using an artificial neural network (ANN), we modeled the relationship between trap distributions and P/R characteristics. The ANN was trained using a large experimentally-calibrated technology computer-aided design (TCAD) simulation dataset. The gradient descent method was adapted to optimize the trap distribution, achieving the best P/R characteristics based on the well-trained ANN. Eventually, we found the best trap profile distributed in both space and energy. In particular, the energetic trap distribution had a larger impact on the P/R characteristics than that of the spatial trap distribution. Furthermore, in terms of the P/R characteristics, it was generally preferable to increase all inputs of the energetic trap distribution. However, the acceptor-like trap energy level ( $E_{TA}$ ) and its standard deviation ( $\sigma _{EA}$ ) caused a tradeoff between P/R characteristics; therefore, ML was used to determine their optimal points. The proposed ML method allows the optimization of trap distribution to obtain the best P/R characteristics rapidly and quantitatively. Our findings could be used as a guideline for determining the physical properties of CTN in 3-D NAND flash cells.
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- 2023
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15. Quasi-Gradient Nonlinear Simplex Optimization Method in Electromagnetics
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Arman Afsari, Amin Abbosh, and Yahya Rahmat-Samii
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Device optimization ,gradient-free optimization ,heuristic methods ,parameter estimation ,quasi-gradient optimization ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
Particle swarm optimization (PSO), genetic algorithm (GA), and nonlinear simplex optimization method (SOM) are some of the most prominent gradient-free optimization algorithms in engineering. When it comes to a common group of electromagnetic optimization problems wherein less than 10 optimization parameters are present in the problem domain, SOM features faster convergence rate vs PSO and GA. Nevertheless, PSO and GA still outperform SOM by having more accuracy in finding the global minimum. To improve the accuracy of SOM in problems with few optimization parameters, a quasi-gradient (Q-G) search direction is added to the conventional algorithm. An extra decision is made by the proposed algorithm to move alongside the reflection or quasi-gradient direction during the error-reduction operations. This modification will improve the accuracy of SOM, which otherwise fails in the examples presented in this article, to levels similar to PSO and GA, while retaining approximately 33% faster convergence speed with relatively small number of parameters, and 20% faster convergence speed with larger number of optimization parameters. Following a standard benchmark test verification, the proposed algorithm successfully solves a suite of electromagnetic optimization problems. Representative examples include the optimization of absorber dimensions in an anechoic chamber, and estimation of the properties of an unknown embedded object by scattered microwave signals.
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- 2023
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16. Investigation of quantum dot luminescent solar concentrator single, double and triple structures: A ray tracing simulation study.
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de Bruin, T.A. and van Sark, W.G.J.H.M.
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SOLAR concentrators , *RAY tracing , *QUANTUM efficiency , *QUANTUM dots , *SOLAR cells , *SEMICONDUCTOR quantum dots , *STOKES shift - Abstract
Quantum dot based luminescent solar concentrators (QDLSCs) are a special class of transparent photovoltaics (TPV), especially suited for building integrated photovoltaics (BIPV). Photons are absorbed by luminescent species in a waveguide and emitted at a red-shifted wavelength. Due to total internal reflection, these photons are absorbed by the solar cells attached to the sides. Successful deployment requires high conversion efficiency and high transparency, which are contradictory requirements. We have performed Monte-Carlo ray tracing simulations to investigate single, double, and triple QDLSCs and have assessed their optical and electrical performance. To this end, eight different semiconductor quantum dot materials have been used with various absorption and emission properties, and Stokes' shift. Device efficiency is analyzed for different average visible transmission (AVT) values, thus considering the human photopic response. The range of luminescent quantum efficiencies (30%–70%) leads to maximum efficiency of 2% for a single QDLSC, 2.4% for a double, and 2.7% for a triple structure, at high transparency and good color rendering index. Further improvements are possible towards > 5% at high transparency with near-unity quantum efficiencies. [Display omitted] • Optimization of conversion efficiency and visual aspects of luminescent solar concentrators. • Nanocrystals are used in single, double, and triple configurations. • Device efficiency and chromaticity aspects need to be optimized in a combined manner. [ABSTRACT FROM AUTHOR]
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- 2023
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17. Numerical analysis of high performance perovskite solar cells with stacked ETLs/C60 using SCAPS-1D device simulator.
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Mohandes, Aminreza, Moradi, Mahmood, and Kanani, Mansour
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SOLAR cells , *NUMERICAL analysis , *PEROVSKITE , *ELECTRON transport , *CONDUCTION bands - Abstract
The latest advances in perovskite solar cells (PSCs) are reported with efficiencies over 25%. PSCs are one of the best developing research-level photovoltaic technologies. To the best of our knowledge, for the first time, we optimize all parameters containing thicknesses, conduction and valence band offset of ETLs (electron transport layers) and hole transport layer, defect densities and doping concentration densities for Cs0.05(FA0.77 MA0.23)0.95Pb(I0.77Br0.23)3. As an absorber layer with numerous stacked ETLs including SnO2/C60, ZnO/C60, TiO2/C60, CdZnS/C60 and CdSe/C60 are used. To find the efficiency, the SCAPS (Solar Cell Capacitance Simulator)-1D program is performed to realize which of stacked ETLs is more appropriate for both cost-effectiveness and high efficiency. After all, the efficiency for stacked SnO2/C60 at 31.16%, stacked ZnO/C60 at 31.22%, stacked TiO2/C60 at 30.55%, stacked CdZnS/C60 at 30.46% and stacked CdSe/C60 at 31.24% are reached. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
18. Using human-in-the-loop optimization for guiding manual prosthesis adjustments: a proof-of-concept study
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Siena C. Senatore, Kota Z. Takahashi, and Philippe Malcolm
- Subjects
prosthesis fitting ,patient-centered design ,device optimization ,prosthesis simulator ,biomechanics ,Mechanical engineering and machinery ,TJ1-1570 ,Electronic computers. Computer science ,QA75.5-76.95 - Abstract
Introduction: Human-in-the-loop optimization algorithms have proven useful in optimizing complex interactive problems, such as the interaction between humans and robotic exoskeletons. Specifically, this methodology has been proven valid for reducing metabolic cost while wearing robotic exoskeletons. However, many prostheses and orthoses still consist of passive elements that require manual adjustments of settings.Methods: In the present study, we investigated if human-in-the-loop algorithms could guide faster manual adjustments in a procedure similar to fitting a prosthesis. Eight healthy participants wore a prosthesis simulator and walked on a treadmill at 0.8 ms−1 under 16 combinations of shoe heel height and pylon height. A human-in-the-loop optimization algorithm was used to find an optimal combination for reducing the loading rate on the limb contralateral to the prosthesis simulator. To evaluate the performance of the optimization algorithm, we used a convergence criterium. We evaluated the accuracy by comparing it against the optimum from a full sweep of all combinations.Results: In five out of the eight participants, the human-in-the-loop optimization reduced the time taken to find an optimal combination; however, in three participants, the human-in-the-loop optimization either converged by the last iteration or did not converge.Discussion: Findings from this study show that the human-in-the-loop methodology could be helpful in tasks that require manually adjusting an assistive device, such as optimizing an unpowered prosthesis. However, further research is needed to achieve robust performance and evaluate applicability in persons with amputation wearing an actual prosthesis.
- Published
- 2023
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19. 11.1: Invited Paper: High Performance Deep Red OLEDs Using Dual p‐dopants to Control Hole Injection.
- Author
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Xie, Menglan, Pang, Huiqing, Wang, Jing, Cui, Zhihao, Zheng, Renjie, Ding, Hualong, Zhang, Qi, Zhang, Cuifang, Kwong, Ray, and Xia, Sean
- Subjects
ORGANIC light emitting diodes ,FRONTIER orbitals ,QUANTUM efficiency ,ELECTROLUMINESCENCE - Abstract
We demonstrate improved charge balance in organic light emitting devices (OLEDs) by optimizing the hole injection layer (HIL) to control the hole density through the device. Two novel p‐dopants (PDs), PD02 with a shallow lowest unoccupied molecular orbital (LUMO) at ‐4.63 eV (reported in our previous work) and PD03 with a relatively deep LUMO of ‐4.91 eV were used. A two‐layer HIL consisting of HTM:PD02 and HTM:PD03 introduces new design flexibility to improve charge balance in the light emission layer. Using 16% by mass of PD02 and 3% by mass of PD03, we achieve, (1) a bottom emission deep red device with an external quantum efficiency (EQE) of over 30% at a CIE of (0.701, 0.299), an operating voltage of 3.2 V and LT95~13, 000 h at 10 mA/cm2. In particular, the efficiency roll‐off of this device is greatly reduced, which is highly desirable in the display industry. (2) a top emission deep red device with a current efficiency (CE) of 75 cd/A at a CIE of (0.707, 0.293), an operating voltage of 3.6 V and LT95 over 15, 000 h at 10 mA/cm2. An additional benefit from this novel dual p‐doped HIL approach is its much lower lateral conductivity compared to the standard single HIL device structure, resulting in reduced lateral crosstalk between RGB pixels. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
20. Optimization of non-spherical particle flow in vertical waste heat recovery devices: Analyzing structural configurations.
- Author
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Liu, Xiangyu, Ai, Qing, Wang, Lianyong, Liu, Meng, Shuai, Yong, and Pan, Qinghui
- Subjects
- *
GRANULAR flow , *POROSITY , *STRUCTURAL optimization , *SPHERES , *CONES - Abstract
Vertical waste heat recovery devices are emerging but are immature. The vertical waste heat recovery devices of circular, square, and optimized designs were analyzed for a full capacity of 8 tons of sintered ore. Using DEM theory, the effects of particle size distribution, velocity, and wall forces on void fraction distribution and particle flow were examined. The circular device demonstrated superior mixed particle flow compared to the square device, achieving integrated flow for 50 % of particles in the cone, in contrast to 26 % for the square device. An optimized circular device achieved integral flow for 90 % of particles, significantly enhancing overall flow and reducing wall adhesion, attributed to its improved internal design. Through insert and distributor design, the overall particle flow within the device improved, with almost no particles remaining on the walls. These findings underscore the potential for enhanced heat recovery efficiency through optimized internal structures in waste heat recovery devices. [Display omitted] • The circular device achieved 50 % overall flow; the square device reached only 26 %. • The optimized design increased overall flow to 90 %, enhancing particle distribution. • Particle impact on the bottom was minimized at a critical stacking height. • Modeling irregular spheres with spherical particles captured realistic flow behavior. • Internal structural optimization enhanced particle flow and reduced wall effects. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
21. Towards the CdS/SnSe solar cell optimization: Understanding the transport mechanisms.
- Author
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Carrillo-Osuna, A., Sánchez-Rodríguez, F.J., Rodriguez-Osorio, K.G., Montoya De Los Santos, I., Morán-Lázaro, J.P., Ojeda-Martínez, M., Pérez, Laura M., Laroze, David, and Courel, Maykel
- Abstract
• Numerical calculations on SnSe solar cells are presented. • Study of loss mechanisms limiting SnSe solar cells for the first time. • Experimental data reported on SnSe solar cells are reproduced with good agreement. • Defects in SnSe bulk and series resistances have a detrimental role rather than SnSe/CdS interface. • The path for further SnSe solar cell optimization is presented. In this work, numerical simulation results on SnSe solar cells are presented. The influence of loss mechanisms such as radiative recombination, SnSe bulk recombination, and CdS/SnSe interface recombination on the device is studied in detail under and without the influence of resistances for the first time. In the first step, our model is validated by accurately reproducing the experimental available data. We found that non-radiative recombination originated by SnSe bulk defects in combination with high series resistances are dominant loss mechanisms, resulting in efficiency values lower than 2 %. In addition, the important role of the CdS/SnSe interface is also evidenced, since SnSe solar cells without bulk defects and resistances would not be able to overcome the efficiency barrier of 10 % because of the cliff-like band alignment. The role of each loss mechanism on SnSe solar cell performance was studied as a function of material thicknesses, carrier concentrations, bulk and interface defects, and resistances for device optimization. We demonstrated that conversion efficiency of 21.8 % with an open-circuit voltage, short-circuit current density, and fill factor values of 0.82 V, 31.6 mA/cm
2 , 84.6 %, respectively can be achieved in the optimized device under the standard conditions of AM 1.5G illumination and 300 K. [ABSTRACT FROM AUTHOR]- Published
- 2024
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- View/download PDF
22. Modeling and Investigation of Rear-Passivated Ultrathin CIGS Solar Cell.
- Author
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Boukortt, Nour El I., Patanè, Salvatore, and Adouane, Mabrouk
- Subjects
SOLAR cells ,COPPER ,PHOTOVOLTAIC power systems ,COMPUTER simulation - Abstract
In this paper, we use numerical simulations to investigate ultrathin Cu (In
1−x Gax ) Se2 solar cells. In the first part, we focus on the cell configuration in which the PV parameters fit and match the fabricated cell characteristics. Our goal is to investigate the impact of different loss mechanisms, such as interface trap density (Dit ) and absorber trap density (Nt ), in different cell pitch sizes on cell performances. Dit defines the number of carrier traps at CIGS/Al2 O3 interfaces to recombine with photogenerated carriers. Nt defines the number of carrier traps in the absorber layer. Recombination through traps has been found to be the primary loss process in the investigated cell. Additional numerical simulations reveal appreciable gains in cell performance for various cell pitch sizes, absorber doping densities, Ga content, and graded bandgap under AM1.5 illumination. Research during the recent decade has clarified that the most promising strategy to achieve maximum efficiency consists of the so-called tandem configuration. Therefore, we here propose a u-CIGS/PERT silicon device employing, as a top cell, a u-CIGS cell optimized to take into account the above procedure. The results of these simulations provide insights into the optimization of ultrathin-film CIGS solar cells. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
23. Light-Emitting Diodes Based on Metal Halide Perovskite and Perovskite Related Nanocrystals.
- Author
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Liu Y, Ma Z, Zhang J, He Y, Dai J, Li X, Shi Z, and Manna L
- Abstract
Light-emitting diodes (LEDs) based on halide perovskite nanocrystals have attracted extensive attention due to their considerable luminescence efficiency, wide color gamut, high color purity, and facile material synthesis. Since the first demonstration of LEDs based on MAPbBr
3 nanocrystals was reported in 2014, the community has witnessed a rapid development in their performances. In this review, a historical perspective of the development of LEDs based on halide perovskite nanocrystals is provided and then a comprehensive survey of current strategies for high-efficiency lead-based perovskite nanocrystals LEDs, including synthesis optimization, ion doping/alloying, and shell coating is presented. Then the basic characteristics and emission mechanisms of lead-free perovskite and perovskite-related nanocrystals emitters in environmentally friendly LEDs, from the standpoint of different emission colors are reviewed. Finally, the progress in LED applications is covered and an outlook of the opportunities and challenges for future developments in this field is provided., (© 2025 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)- Published
- 2025
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- View/download PDF
24. Comprehensive Design and Numerical Study of GaN Vertical MPS Diodes Towards Alleviated Electric Field Crowding and Efficient Carrier Injection
- Author
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Heng Wang, Sihao Chen, Hang Chen, and Chao Liu
- Subjects
Breakdown voltage ,device optimization ,gallium nitride (GaN) ,specific ON-resistance ,vertical merged pn-Schottky (MPS) diode ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
In recent years, gallium nitride (GaN) has exhibited tremendous potential for power electronic devices owing to its wider energy band gap, higher breakdown electric field, and higher carrier mobility [1]–[4]. Thanks to the availability of low-dislocation-density bulk GaN substrates and the intrinsic advantages of the vertical device topology, GaN-based vertical SBDs have been developed extensively towards high voltage and high current applications [5]–[7]. However, similar to the lateral GaN SBDs based on the AlGaN/GaN heterostructures, GaN vertical SBDs also suffer from reverse leakage issues due to the energy barrier lowering effect at high reverse bias condition. To achieve a decent device performance, several device architectures have been developed, such as junction barrier Schottky (JBS) diode [8], MPS diode [9]–[12], and trench metal-insulator-semiconductor barrier Schottky (TMBS) diode [13], [14], which are designed to move the peak electric field from the interface of the Schottky junction to the inside of the device at high reverse bias, leading to a higher breakdown voltage and a lower reverse leakage current.
- Published
- 2022
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- View/download PDF
25. Design Strategies of 40 nm Split-Gate NOR Flash Memory Device for Low-Power Compute-in-Memory Applications
- Author
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Chan-Gi Yook, Jung Nam Kim, Yoon Kim, and Wonbo Shim
- Subjects
compute-in-memory (CIM) ,NOR flash ,split-gate NOR flash ,device optimization ,artificial intelligence ,convolutional neural network ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
The existing von Neumann architecture for artificial intelligence (AI) computations suffers from excessive power consumption and memory bottlenecks. As an alternative, compute-in-memory (CIM) technology has been emerging. Among various CIM device candidates, split-gate NOR flash offers advantages such as a high density and low on-state current, enabling low-power operation, and benefiting from a high level of technological maturity. To achieve high energy efficiency and high accuracy in CIM inference chips, it is necessary to optimize device design by targeting low power consumption at the device level and surpassing baseline accuracy at the system level. In split-gate NOR flash, significant factors that can cause CIM inference accuracy drop are the device conductance variation, caused by floating gate charge variation, and a low on-off current ratio. Conductance variation generally has a trade-off relationship with the on-current, which greatly affects CIM dynamic power consumption. In this paper, we propose strategies for designing optimal devices by adjusting oxide thickness and other structural parameters. As a result of setting Tox,FG to 13.4 nm, TIPO to 4.6 nm and setting other parameters to optimal points, the design achieves erase on-current below 2 μA, program on-current below 10 pA, and off-current below 1 pA, while maintaining an inference accuracy of over 92%.
- Published
- 2023
- Full Text
- View/download PDF
26. Treatment of cardiac resynchronization therapy non-responders: current approaches and new frontiers.
- Author
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Lehmann, H. Immo, Tsao, Lana, and Singh, Jagmeet P.
- Subjects
CARDIAC pacing ,ARRHYTHMIA ,PATIENT selection ,HEART failure ,TEAMS in the workplace - Abstract
Cardiac resynchronization therapy (CRT) has developed into a very effective technology for patients with decreased systolic function and has substantially improved patients' clinical course. However, non-responsiveness to CRT, described as lack of reverse cardiac chamber remodeling, leading to lack to improve symptoms, heart failure hospitalizations or mortality, is common, rather unpredictable, and not fully understood. This article aims to discuss key factors that are impacting CRT response, from patient selection to LV lead position, to structured follow-up in CRT clinics. Secondly, common causes and interventions for CRT non-responsiveness are discussed. Next, insight is given into technologies representing new and feasible interventions as well as pacing strategies in this group of patients that remain challenging to treat. Finally, an outlook is given into future scientific development. Despite the progress that has been made, CRT non-response remains a significant and complex problem. Patient management in interdisciplinary teams including heart failure, imaging, and cardiac arrhythmia experts appears critical as complexity is increasing and CRT non-response often is a multifactorial problem. This will allow optimization of medical therapy, and the use of new integrated sensor technologies and telemedicine to ultimately optimize outcomes for all patients in need of CRT. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
27. Design Space of GaN Vertical Trench Junction Barrier Schottky Diodes: Comprehensive Study and Analytical Modeling.
- Author
-
Yin, Jian, Chen, Sihao, Chen, Hang, Li, Shuti, Fu, Houqiang, and Liu, Chao
- Subjects
SCHOTTKY barrier diodes ,GALLIUM nitride ,BREAKDOWN voltage ,TRENCHES ,SCHOTTKY barrier ,ELECTRIC fields - Abstract
We report gallium nitride (GaN) vertical trench junction barrier Schottky (TJBS) diodes and systematically analyzed the effects of the key design parameters on the reverse and forward characteristics of the devices. By taking advantage of the shielding effects from both the trenches and pn junctions in the TJBS structure, the high electric field at the Schottky contact region can be effectively suppressed. We found that the doping concentration, thickness, and spacing of p-GaN, as well as the depth and angle of the trench sidewalls are closely associated with the electric field distribution and the reverse characteristics of the TJBS diodes. With an optimal set of design parameters, the local electric field crowding at either the corner of the trench or the edge of the p-GaN can also be alleviated, resulting in a boosted breakdown voltage of up to 1250 V in the TJBS diodes. In addition, an analytical model was developed to explore the physical mechanism behind the forward conduction behaviors. We believe that the results can provide a systematical design strategy for the development of low-loss, high-voltage, and high-power GaN power diodes towards an efficient power system. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
28. Pacing Optimized by Left Ventricular dP/dtmax.
- Author
-
Elliott, Mark K., Mehta, Vishal S., and Rinaldi, Christopher A.
- Abstract
Left ventricular (LV) dP/dt max provides a sensitive measure of the acute hemodynamic response to cardiac resynchronization therapy (CRT) and can predict reverse remodeling on echocardiography. Its use to guide LV lead placement has been shown to improve outcomes in a multicenter randomized trial. Given the invasive protocol required for measurement, it is unlikely to be universally beneficial for patients undergoing CRT but may be useful for patients who do not respond to conventional CRT, or in those who have borderline indications or risk factors for non-response. In such cases, LV dP/dt max may help guide LV lead placement, optimize device programming, and select the best alternative method of delivering CRT, such endocardial LV pacing or conduction system pacing. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
29. 45‐1: Invited Paper: Charge Balance in OLEDs: Optimization of Hole‐Injection Layer.
- Author
-
Xie, Menglan, Pang, Huiqing, Wang, Jing, Cui, Zhihao, Kwong, Ray, and Xia, Sean
- Subjects
DELAYED fluorescence ,QUANTUM efficiency ,ORGANIC light emitting diodes ,DOPING agents (Chemistry) - Abstract
In this work, we provide a novel strategy to improve the charge balance in organic light emitting devices (OLEDs) by optimizing the hole injection layer (HIL) and thereby controlling the overall hole supply in the device. The lowest unoccupied molecular orbit (LUMO) of the p‐dopant proposed in this work, PD02, is ‐4.63 eV, much shallower than that of the commercial material (PD01). Nevertheless, this enables use of the doping concentration to modulate the supply of holes to the emissive layer to control the charge balance. We demonstrate that device performances are significantly improved by employing such a scheme. With 23% molar doping of PD02, a bottom emission red OLED achieves external quantum efficiency (EQE) over 30%, operating voltage of 3.4 V and LT95 ~ 15,000 h at 10 mA/cm2. Moreover, the efficiency roll‐off is also suppressed up till ~ 3,500 cd/m2, a desirable feature in display applications. A study of exciton distribution within the emissive layer suggests that improved charge balance is indeed achieved in the optimized structure. An additional benefit from the modified HIL is its lower lateral conductivity relative to the standard formula, which reduces crosstalk between RGB pixels. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
30. Hierarchical Piezoresponse in Collagen.
- Author
-
Cartwright, Victoria F. and Brown, Cameron P.
- Subjects
- *
PIEZOELECTRICITY , *MUSCOVITE , *ENERGY harvesting - Abstract
The piezoelectric nature of collagen has been known for decades, yet its manifestation across, and interactions between, hierarchies remains elusive. Here, piezoelectricity at the tropocollagen‐, microfibril‐, and fibril‐level hierarchies is examined experimentally, using collagen assembled from solution onto muscovite mica substrates. An amplification of the d15 response of 35–50% is observed between the tropocollagen and fibril levels, with no difference observed between the microfibril and fibril levels. Comparison of experimental results with simulation indicates the potential to optimize collagen piezoresponse via tropocollagen packing to exceed the piezoelectric properties of native collagen fibrils. By improving electromechanical performance through adjustments to winding angle and packing, it may therefore be possible to utilize collagen in low‐cost, biodegradable, and biocompatible sensing or harvesting devices. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
31. Optimization of Feedback FET with Asymmetric Source Drain Doping Profile.
- Author
-
Lee, Inyoung, Park, Hyojin, Nguyen, Quan The, Kim, Garam, Cho, Seongjae, and Cho, Ilhwan
- Subjects
FIELD-effect transistors ,PSYCHOLOGICAL feedback ,DOPING agents (Chemistry) - Abstract
A feedback field-effect transistor (FBFET) is a novel device that uses a positive feedback mechanism. FBFET has a high on-/off ratio and is expected to realize ideal switching characteristics through steep changes from off-state to on-state. In this paper, we propose and optimize FBFET devices with asymmetric source/drain doping concentrations. Additionally, we discuss the changes in electrical characteristics across various channel length and channel thickness conditions and compare them with those of FBFET with a symmetric source/drain. This shows that FBFET with an asymmetric source/drain has a higher on-/off ratio than FBFET with a symmetric source/drain. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
32. 玉米秸秆捡拾制粒机的成型装置设计与试验.
- Author
-
邱硕, 孙喜月, 白雪卫, and 宫元娟
- Abstract
Copyright of Journal of Shenyang Agricultural University is the property of Journal of Shenyang Agricultural University Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
33. Device design and optimization of CNTFETs for high-frequency applications.
- Author
-
Peng, Boli, Annamalai, Manojkumar, Mothes, Sven, and Schröter, Michael
- Abstract
Carbon nanotube (CNT) field-effect transistors (FETs) have recently reached high-frequency (HF) performance similar to that of silicon RF-CMOS at the same gate length despite a tube density and current per tube that are far from the physical limits and suboptimal device architecture. This work reports on an investigation of the optimal device design for practical HF applications in terms of cut-off frequencies, power gain, and linearity. Different fundamental designs in the gate contact arrangement are considered based on a 3D device simulation of both CNTs and contacts. First, unit cells with a single CNT and minimal contact sizes are compared. The resulting simulation data are then extended toward a structure with two gate fingers and realistic contact sizes. Corresponding parasitic capacitances, as well as series and contact resistances, have been included for obtaining realistic characteristics and figures of merit that can be used for comparison with corresponding silicon RF MOSFETs. Finally, a sensitivity analysis of the device architecture with the highest performance is performed in order to find the optimal device design space. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
34. Modeling of Gate Tunable Synaptic Device for Neuromorphic Applications
- Author
-
Yang Shen, He Tian, Yanming Liu, Fan Wu, Zhaoyi Yan, Thomas Hirtz, Xuefeng Wang, and Tian-Ling Ren
- Subjects
resistive random-access memory ,neuromorphic synaptic device ,neural network ,online learning ,device optimization ,Physics ,QC1-999 - Abstract
The emerging memories are great candidates to establish neuromorphic computing challenging non-Von Neumann architecture. Emerging non-volatile resistive random-access memory (RRAM) attracted abundant attention recently for its low power consumption and high storage density. Up to now, research regarding the tunability of the On/Off ratio and the switching window of RRAM devices remains scarce. In this work, the underlying mechanisms related to gate tunable RRAMs are investigated. The principle of such a device consists of controlling the filament evolution in the resistive layer using graphene and an electric field. A physics-based stochastic simulation was employed to reveal the mechanisms that link the filament size and the growth speed to the back-gate bias. The simulations demonstrate the influence of the negative gate voltage on the device current which in turn leads to better characteristics for neuromorphic computing applications. Moreover, a high accuracy (94.7%) neural network for handwritten character digit classification has been realized using the 1-transistor 1-memristor (1T1R) crossbar cell structure and our stochastic simulation method, which demonstrate the optimization of gate tunable synaptic device.
- Published
- 2021
- Full Text
- View/download PDF
35. Design and Optimization of an Assistive Cane With Visual Odometry for Blind People to Detect Obstacles With Hollow Section.
- Author
-
Tang, Jingyu, Sun, Mingze, Zhu, Lingjun, Hu, Menghan, Zhou, Mei, Zhang, Jian, Li, Qingli, and Zhai, Guangtao
- Abstract
Existing obstacle avoidance systems do not consider the situation of hollowed-out obstacles. Therefore, in this paper, we design an assistive cane with visual odometry based on these requirements of the blind to aid them in attaining safe indoor navigation. The proposed device is portable, compact and adaptable. The assistive cane with visual odometry can be used not only to directly detect obstacles, but also to draw the attention of people around, providing multiple protection for the blind. In order to optimize the device parameters, we select the height of the camera and the speed of the voice broadcast as factors to design a complete factorial design, aiming to explore the parameter level that can make the passing time shortest and the success rate of obstacle avoidance highest. We invited two visually impaired people and two blindfolded students with normal vision as the experimental subjects. Each subject was required to conduct the experiments under nine combinations of device parameters. The subjects tried to avoid obstacles according to the voice prompts. The passing time and the success rate of obstacle avoidance were recorded. The experimental results show that the broadcast speed causes the significant effect to the success rate and both the two factors affect the passing time. In addition, we discuss the results of different subjects’ response surfaces and perceptual patterns and get the conclusion that different visual perceptual patterns, namely route representation and two different survey representations, have a certain impact on the setting of the optimal parameter level and the optimal passing time. The congenitally blind subject with route representation has the shortest optimal passing time in an unfamiliar environment, and the camera height should be set at the center of the hollowed-out obstacle, while the results are somewhat different for the acquired visual impairment subjects and the blindfolded normal vision subjects with survey representation. The camera height should be set between the center and the upper position of the obstacle. In summary, the camera height should be set at the center of the hollowed-out barrier and the broadcast speed should be set at the highest level. At the same time, the device parameters should be adjusted appropriately according to the visual perception pattern of users. Further researches are needed to analyze the perceptual patterns in depth. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
36. Reducing Passive Drug Diffusion from Electrophoretic Drug Delivery Devices through Co‐Ion Engineering
- Author
-
Shao‐Tuan Chen, Megan N. Renny, Liliana C. Tomé, Jorge L. Olmedo‐Martínez, Esther Udabe, Elise P. W. Jenkins, David Mecerreyes, George G. Malliaras, Robert R. McLeod, and Christopher M. Proctor
- Subjects
bioelectronics ,device optimization ,electrophoretic transport ,targeted drug delivery ,Science - Abstract
Abstract Implantable electrophoretic drug delivery devices have shown promise for applications ranging from treating pathologies such as epilepsy and cancer to regulating plant physiology. Upon applying a voltage, the devices electrophoretically transport charged drug molecules across an ion‐conducting membrane out to the local implanted area. This solvent‐flow‐free “dry” delivery enables controlled drug release with minimal pressure increase at the outlet. However, a major challenge these devices face is limiting drug leakage in their idle state. Here, a method of reducing passive drug leakage through the choice of the drug co‐ion is presented. By switching acetylcholine's associated co‐ion from chloride to carboxylate co‐ions as well as sulfopropyl acrylate‐based polyanions, steady‐state drug leakage rate is reduced up to sevenfold with minimal effect on the active drug delivery rate. Numerical simulations further illustrate the potential of this method and offer guidance for new material systems to suppress passive drug leakage in electrophoretic drug delivery devices.
- Published
- 2021
- Full Text
- View/download PDF
37. Reducing Passive Drug Diffusion from Electrophoretic Drug Delivery Devices through Co‐Ion Engineering.
- Author
-
Chen, Shao‐Tuan, Renny, Megan N., C. Tomé, Liliana, Olmedo‐Martínez, Jorge L., Udabe, Esther, Jenkins, Elise P. W., Mecerreyes, David, Malliaras, George G., McLeod, Robert R., and Proctor, Christopher M.
- Subjects
DRUG delivery devices ,CONTROLLED release drugs ,PLANT physiology - Abstract
Implantable electrophoretic drug delivery devices have shown promise for applications ranging from treating pathologies such as epilepsy and cancer to regulating plant physiology. Upon applying a voltage, the devices electrophoretically transport charged drug molecules across an ion‐conducting membrane out to the local implanted area. This solvent‐flow‐free "dry" delivery enables controlled drug release with minimal pressure increase at the outlet. However, a major challenge these devices face is limiting drug leakage in their idle state. Here, a method of reducing passive drug leakage through the choice of the drug co‐ion is presented. By switching acetylcholine's associated co‐ion from chloride to carboxylate co‐ions as well as sulfopropyl acrylate‐based polyanions, steady‐state drug leakage rate is reduced up to sevenfold with minimal effect on the active drug delivery rate. Numerical simulations further illustrate the potential of this method and offer guidance for new material systems to suppress passive drug leakage in electrophoretic drug delivery devices. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
38. Automated optimization of double heater convective polymerase chain reaction devices based on CFD simulation database and artificial neural network model.
- Author
-
Hong, Seong Hyeon, Shu, Jung-Il, Wang, Yi, and Baysal, Oktay
- Subjects
ARTIFICIAL neural networks ,POLYMERASE chain reaction ,COMPUTATIONAL fluid dynamics ,HEATING ,CAPILLARY tubes - Abstract
This paper presents a framework for automated optimization of double-heater convective PCR (DH-cPCR) devices by developing a computational fluid dynamics (CFD) simulation database and artificial neural network (ANN) model. The optimization parameter space that includes the capillary tube geometries and the heater sizes of DH-cPCR is established, and a database consisting of nearly 10,000 CFD simulations is constructed. The database is then used to train a two-stage ANN models that select practically relevant data for modeling and predict PCR device performance. The trained ANN model is then combined with the gradient-based and the heuristics optimization approaches to search for optimal device configuration that possesses the shortest DNA doubling time. The entire design process including model meshing and configuration, parallel CFD computation, database organization, and ANN training and utilization is fully automated. Case studies confirm that the proposed framework can successfully find the optimal device configuration with an error of less than 0.3 s, and hence, representing a cost-effective and rapid solution of DH-cPCR device design. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
39. Design and optimization of seagull airfoil wind energy conversion device.
- Author
-
Song, Li, Tian, Kangqi, Jiao, Xiaofeng, Feng, Rui, Wang, Long, and Tian, Rui
- Subjects
WIND power ,AEROFOILS ,ENERGY conversion ,GULLS ,STRAINS & stresses (Mechanics) ,AERODYNAMIC load - Abstract
Remote areas in Northwest China are blind regions without large-scale power grid coverage. To satisfy the residential electricity demand, it is essential to utilize small-scale distributed wind power systems and increase wind energy utilization. The seagull airfoil wind energy conversion device is adopted to improve the aerodynamic performance and increase the use of wind energy. Based on the wind tunnel experiment and numerical simulation, the bending shape of the seagull airfoil is optimized. Further, the cascade structure is constructed using the central bending seagull airfoil to explore the flow mechanisms. The front and rear cascades are the main and secondary regions, accounting for 84% and 16% of the force generated, respectively. The deformation of the blade is significantly larger at the trailing edge than at the leading edge, thereby exhibiting unique deformation characteristics of seagull airfoils. When the impeller is rotated, the average force of each seagull airfoil was 15.1% more than that of the flat airfoil, thereby enabling the absorption of more wind energy and device optimization. Owing to the stress and deformation distribution, the seagull airfoil blade can adapt to different aerodynamic loads by changing the cambers and angles of attack to ensure smooth operation of the device. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
40. A Dual NIR-Band Lock-In Pixel CMOS Image Sensor With Device Optimizations for Remote Physiological Monitoring.
- Author
-
Cao, Chen, Dutta, Jaydeep Kumar, Hakamata, Masashi, Yasutomi, Keita, Kagawa, Keiichiro, Aoyama, Satoshi, Tsumura, Norimichi, and Kawahito, Shoji
- Subjects
- *
CMOS image sensors , *PATIENT monitoring , *HEART beat , *PIXELS , *ELECTRIC fields , *IMAGE enhancement (Imaging systems) - Abstract
A 7.1-μm-pitch lock-in pixel (LIP) CMOS image sensor (CIS) that is capable of simultaneously phasing with two different near-infrared-band (NIR-band) light pulses is developed for remote physiological measurement, particularly a heart rate variability (HRV) signal monitor. The proposed dual NIR-band lock-in operation is realized by a four-tap-wise charge modulation with adjacent two-tap LIPs by means of a column-interdigital pixel driving scheme combining with in-LIP lateral electric field modulators (LEFMs). For attaining the weak HRV signal, the implemented CIS achieves a subelectron temporal noise of 0.67 e−rms at 64 times correlated multiple sampling (CMS) and a high charge modulation contrast (MC) up to 96% at maximum. These remarkable properties primarily result from the in-LIP dark current and LEFM controlling optimizations proposed in device domain. The experimental results show that the developed CIS exhibits not only a 98.5% accuracy in HRV signal capture with −39.1-dB signal-to-background ratio (SBR) against a fluctuant brightness ambient light but also a moderate artificial motion robustness benefited from the proposed dual NIR-band lock-in technique. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
41. Optimization of Feedback FET with Asymmetric Source Drain Doping Profile
- Author
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Inyoung Lee, Hyojin Park, Quan The Nguyen, Garam Kim, Seongjae Cho, and Ilhwan Cho
- Subjects
feedback field-effect transistor (FBFET) ,device optimization ,on–off current ratio ,subthreshold swing ,TCAD ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
A feedback field-effect transistor (FBFET) is a novel device that uses a positive feedback mechanism. FBFET has a high on-/off ratio and is expected to realize ideal switching characteristics through steep changes from off-state to on-state. In this paper, we propose and optimize FBFET devices with asymmetric source/drain doping concentrations. Additionally, we discuss the changes in electrical characteristics across various channel length and channel thickness conditions and compare them with those of FBFET with a symmetric source/drain. This shows that FBFET with an asymmetric source/drain has a higher on-/off ratio than FBFET with a symmetric source/drain.
- Published
- 2022
- Full Text
- View/download PDF
42. Design Strategies for Mesa-Type GaN-Based Schottky Barrier Diodes for Obtaining High Breakdown Voltage and Low Leakage Current.
- Author
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Jia, Xingyu, Chen, Sung-Wen Huang, Liu, Yajin, Hou, Xu, Zhang, Yonghui, Zhang, Zi-Hui, and Kuo, Hao-Chung
- Subjects
- *
BREAKDOWN voltage , *SCHOTTKY barrier diodes , *HIGH voltages , *ELECTRIC potential , *LOW voltage systems , *ELECTRIC fields - Abstract
In this article, we have systematically investigated the impact of different structural parameters on the breakdown voltage for GaN-based trench MIS barrier-controlled Schottky (TMBS) rectifier. Compared with the planar Schottky rectifier, the TMBS rectifier has field plates on the mesa sidewalls so that the drift region can be depleted in a 2-D manner, which helps to decrease the electric field at the metal/mesa interface. However, the adoption of mesas can make the electric potential lines at the mesa corner dense and has large curvatures. Therefore, the premature breakdown can occur when the electric field therein reaches the critical condition. We find that the electric field profiles can be affected by insulation layer thickness, mesa width, trench depth, and different types of insulation layers. Then, we increase the breakdown voltage by homogenizing the electric field distribution in the mesa region, e.g., the electric field at mesa corners can be decreased by adopting properly thick sidewall insulator and small trench depth. Meanwhile, TMBS rectifier using sidewall insulating material with a large dielectric constant more favors a large breakdown voltage. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
43. A data-driven approach to optimize the design configuration of multi-sleeve cone penetrometer probe attachments.
- Author
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Zhang, Danrong, Roy, Nimisha, and Frost, J. David
- Subjects
- *
MACHINE learning , *CONE penetration tests , *ELECTRONIC equipment , *SOIL classification , *PENETROMETERS - Abstract
This study uses a data-driven approach to address the complexities associated with research focused multi-sleeve Cone Penetration Test (CPT) devices, particularly focusing on the multi-friction attachment (MFA) and multi-piezo-friction attachment (MPFA) CPT devices. Hindered by time-consuming assembly and susceptibility to sensor stream losses due to extensive electronic components, these advanced devices demand optimization to transform from research devices to practice-suitable devices. This study aims at optimizing the design of the multi-sleeve CPT devices using machine learning, with soil type classification performance as the primary metric for device configuration effectiveness. The research scope centers not on using machine learning for soil classification but on refining the design of multi-sleeve CPT devices. A two-phase data-driven approach is adopted, testing various feature combinations across eight machine learning models. The first phase involves identifying the most suitable model for the dataset, followed by a refinement of features to balance sensor number minimization and soil classification accuracy. The result is a proposed configuration for a multi-sleeve CPT device, simplifying the original design while maintaining robustness, thereby enhancing cost-efficiency and operational effectiveness in geotechnical practice. This work sheds light on how the integration of machine learning can guide the design optimization of geotechnical instruments. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
44. 三氧化硫磺化装置的优化.
- Author
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郭志强, 李全红, 耿卫东, 娄君明, and 沈 宏
- Abstract
Copyright of China Cleaning Industry / Zhongguo Xidi Yongpin Gongye is the property of China Cleaning Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
45. Investigation of quantum dot luminescent solar concentrator single, double and triple structures: A ray tracing simulation study
- Author
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Bruin, T.A. de, Sark, W.G.J.H.M. van, Bruin, T.A. de, and Sark, W.G.J.H.M. van
- Abstract
Quantum dot based luminescent solar concentrators (QDLSCs) are a special class of transparent photovoltaics (TPV), especially suited for building integrated photovoltaics (BIPV). Photons are absorbed by luminescent species in a waveguide and emitted at a red-shifted wavelength. Due to total internal reflection, these photons are absorbed by the solar cells attached to the sides. Successful deployment requires high conversion efficiency and high transparency, which are contradictory requirements. We have performed Monte-Carlo ray tracing simulations to investigate single, double, and triple QDLSCs and have assessed their optical and electrical performance. To this end, eight different semiconductor quantum dot materials have been used with various absorption and emission properties, and Stokes’ shift. Device efficiency is analyzed for different average visible transmission (AVT) values, thus considering the human photopic response. The range of luminescent quantum efficiencies (30%–70%) leads to maximum efficiency of 2% for a single QDLSC, 2.4% for a double, and 2.7% for a triple structure, at high transparency and good color rendering index. Further improvements are possible towards 5% at high transparency with near-unity quantum efficiencies.
- Published
- 2023
46. Strategies for Restoring Cardiac Synchrony by Cardiac Pacing
- Author
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Cristian, Gabriel, Bontas, Ecaterina, Chiriac, Liviu, Dumitrescu, Silviu Ionel, T¸intoiu, Ion C., Kibos, Ambrose S., editor, Knight, Bradley P., editor, Essebag, Vidal, editor, Fishberger, Steven B., editor, Slevin, Mark, editor, and Țintoiu, Ion C., editor
- Published
- 2014
- Full Text
- View/download PDF
47. Modeling and Investigation of Rear-Passivated Ultrathin CIGS Solar Cell
- Author
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Nour El I. Boukortt, Salvatore Patanè, and Mabrouk Adouane
- Subjects
Computer Networks and Communications ,Hardware and Architecture ,Control and Systems Engineering ,thin film ,ultrathin CIGS ,Signal Processing ,PERT silicon ,Electrical and Electronic Engineering ,traps ,device optimization - Abstract
In this paper, we use numerical simulations to investigate ultrathin Cu (In1-xGax) Se2 solar cells. In the first part, we focus on the cell configuration in which the PV parameters fit and match the fabricated cell characteristics. Our goal is to investigate the impact of different loss mechanisms such as interface trap density (Dit) and absorber trap density (Nt) in different cell pitch sizes on cell performance. Dit defines the amount of carrier’s traps at CIGS/Al2O3 interface to recombine with photogenerated carriers. Nt defines the amount of carrier traps in the absorber layer. It has been found that the recombination via traps is the major loss mechanism in the investigated cell. Further numerical investigations quantify significant improvements in cell performance for different cell pitch sizes, absorber doping densities, Ga content, and graded bandgap at a fixed opening width in the Al2O3 layer. Consequently, for tandem configuration, the optimized single u-CIGS cell has been used as a top cell with a PERT silicon cell which aroused this recent decade as a promising strategy to achieve maximum efficiencies. The results from these simulations provide insights for ultrathin film CIGS solar cell optimization.
- Published
- 2022
- Full Text
- View/download PDF
48. Effect of the introduction of an alcohol-soluble conjugated polyelectrolyte as cathode interlayer in solution-processed organic light-emitting diodes and photovoltaic devices.
- Author
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Carulli, Francesco, Mróz, Wojciech, Lassi, Elisa, Sandionigi, Cristina, Squeo, Benedetta, Meazza, Lorenzo, Scavia, Guido, Luzzati, Silvia, Pasini, Mariacecila, Giovanella, Umberto, and Galeotti, Francesco
- Abstract
Interfacial engineering provides an important tool for optimizing the performances of optoelectronic devices. We show that poly[(2,7-(9,9′-dioctyl)fluorene)-alt-(2,7-(9,9′-bis(5″-trimethylammonium bromide)pentyl)fluorene)])], an alcohol-soluble π-conjugated polymer based on polyfluorene backbone and ammonium groups on the alkyl side chains, is capable of modifying the interface between the organic layer and the metal cathode in both organic solar cells and light-emitting diodes based on commercial materials and conventional architectures, improving their performances. The introduction of the cathode interlayer enhances the efficiency of a red-emitting phosphorescent OLED by 15% and decreases its turn-on voltage. The same polymer improves the power conversion efficiency of a PTB7/PC
71 BM solar cell by 55% and shows a beneficial effect in terms of device stability. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
49. Gate length scaling optimization of FinFETs.
- Author
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Chen, Shoumian, Shang, Enming, and Hu, Shaojian
- Subjects
- *
FIELD-effect transistors , *METAL oxide semiconductors , *STRAY currents , *FIELD-effect devices , *TRANSISTORS - Abstract
This paper introduces a device performance optimization approach for the FinFET through optimization of the gate length. As a result of reducing the gate length, the leakage current (Ioff) increases, and consequently, the stress along the channel enhances which leads to an increase in the drive current (Isat) of the PMOS. In order to sustain Ioff, work function is adjusted to offset the effect of the increased stress. Changing the gate length of the transistor yields different drive currents when the leakage current is fixed by adjusting the work function. For a given device, an optimal gate length is found to provide the highest drive current. As an example, for a standard performance device with Ioff = 1 nA/um, the best performance Isat = 856 uA/um is at L = 34 nm for 14 nm FinFET and Isat = 1130 uA/um at L = 21 nm for 7 nm FinFET. A 7 nm FinFET will exhibit performance boost of 32% comparing with 14 nm FinFET. However, applying the same method to a 5 nm FinFET, the performance boosting is out of expectance comparing to the 7 nm FinFET, which is due to the severe short-channel-effect and the exhausted channel stress in the FinFET. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
50. Towards an integrated evolutionary strategy and artificial neural network computational tool for designing photonic coupler devices.
- Author
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da Silva Ferreira, Adriano, Hernández Figueroa, Hugo Enrique, da Silva Santos, Carlos Henrique, and Gonçalves, Marcos Sergio
- Subjects
ARTIFICIAL neural networks ,FINITE element method ,MULTILAYER perceptrons ,PHOTONICS ,COMPUTER systems - Abstract
Photonics has been widely explored in computing and communications, mainly to rationalize the relationship between device size minimization and data processing/transmission maximization. Generally driven by optimization and modeling techniques, the design of photonic devices is often performed by bio-inspired algorithms integrated to electromagnetic solvers, which have achieved advances but is still time-consuming. As an alternative to a costly finite element method (FEM) solver, a multilayer perceptron (MLP) neural network is proposed for computing power coupling efficiency of photonic couplers, originally designed through an integrated evolutionary strategy (ES) and FEM routine. We address the ES-FEM design of two efficient couplers, present the MLP implementation and the MLP training and testing over the routine generated datasets, and measure MLP and FEM runtime. MLP suitably predicted the power coupling efficiency of a variety of unknown couplers on tests. The measured runtime showed MLP is ∼10 5 faster than FEM. In conclusion, MLP is a potential tool to be integrated to ES on the design of such photonic couplers. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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