Improvement Of Uniformity Research Articles

Paper] Spatial Uniformity Improvement at Low Luminance Levels for Organic Light-Emitting Diode Displays

This paper proposes two methods for improving uniformity in the low luminance region of an organic light-emitting diode (OLED) display. To supply a stable current to subpixels in the low luminance region, the time-division method produces long-term and short-term subframes for the frame period. On the other hand, the area-division method produces non-emitting and amplified emitting regions of grouped pixels. These methods assume that the effective use of a high current improves spatial uniformity, as it becomes worse in low luminance regions. In experiments involving an actual display, the spatial distribution of luminance was measured while applying each of the proposed methods and evaluated based on the root mean square (RMS) value of the luminous deviation. When the results of the experiments with or without application of the proposed methods were compared, the proposed methods were shown to produce a decrease in the RMS value.

Improvement of spin polarization spatial uniformity in optically pumped atomic magnetometers based on counter-propagating pump beams and atomic diffusion

In an optically pumped alkali vapor cell with a high density of atoms, the attenuation of the pump light generates a spatially non-uniform distribution of the electronic spin polarization of alkali atoms, which is detrimental to biomagnetism applications of magnetometers as well as the hyperpolarization of noble gas atoms. Therefore, in this study, we propose a new scheme to generate a nearly uniform, unsaturated spin polarization region based on counter-propagating pump beams and atomic diffusion. A finite element method-based simulation is used to demonstrate the three-dimensional distribution of the spin polarization in a spherical cell. The effects of cell temperature and pump light power on the homogeneity of the spin polarization are studied. The distribution of spin polarization near the center of the cell is experimentally measured and a 1 cm uniform spin polarization region is achieved in the center of the cell. The uniformity of spin polarization in the center region of the cell increased by 50% compared with single beam pumping. The advantage of our proposed scheme is that it can generate an unsaturated uniform region of spin polarization in the center of a cell using a single species of alkali atoms.

Uniformity Improvement with Time-division Driving for Low-level Luminescence of AMOLED Displays

Uniformity Improvement with Time-division Driving for Low-level Luminescence of AMOLED Displays

Efficiency improvement of a flow-through water disinfection reactor using UV-C light emitting diodes

In this study, the effects of irradiance distribution, outer radius (Ro), radiative power, and flow rate were investigated in a flow-through reactor using a 280 nm ultraviolet-C (UV-C) light emitting diodes (LEDs) to improve Escherichia coli (E. coli) inactivation efficiency. The length (L) and inner radius (Ri) of the reactor were 10 cm and 17 mm, respectively. The results demonstrated that the use of 24 LEDs offered the highest inactivation efficiency due to a significant improvement in irradiance uniformity under the same input power. An optimal log inactivation was obtained when Ro = 23 mm for the three UV-C LED arrays. An increase in Ro increases the exposure time but also significantly reduces average irradiance. Furthermore, the log inactivation decreased sharply as the flow rate was increased from 40 to 60 mL/min due to the significant decrement of exposure time. The reactor can achieve 4.0 log at a flow rate of 47 mL/min with an exposure time of 15.6 s at a radiative power of 10 mW. The inactivation rate constant K was obtained at 0.18 cm2/mJ for the two radiative powers in the fluence-response curve. The present results provide key implications for portable application of flow-through UV LED water disinfection reactor.

Effect of repetitive upsetting-extrusion on deformation uniformity and mechanical properties of Mg–Gd–Y–Zr alloy

Mg-8.3Gd-3.2Y-0.4Zr alloy underwent severe plastic deformation at 420 °C using 4-pass isothermal repetitive upsetting-extrusion (RUE) process. The deformation uniformity in different regions of the same sample after 4 passes of RUE was studied. The results showed that though there was slightly uneven deformation, the isothermal RUE process can improve uniformity. The strain in the central area is relatively small, and there are more deformed large grains. The dynamic recrystallization fraction at different positions is above 0.5, forming a more uniform microstructure, with the minimum average grain size being 10.66 μm. Discontinuous dynamic recrystallization and continuous dynamic recrystallization occur at the same time, which promotes grain refinement and improvement of microstructure uniformity. Dynamic recrystallization weakens the texture, resulting the similar texture intensity of different positions of the sample. The bottom edge position with the most uniform microstructure obtained the best tensile properties, UTS reached 323 MPa.

Prostate Bed Delineation Guidelines for Postoperative Radiation Therapy: On Behalf Of The Francophone Group of Urological Radiation Therapy

Prostate bed (PB) irradiation is considered the standard postoperative treatment after radical prostatectomy (RP) for tumors with high-risk features or persistent prostate-specific antigen, or for salvage treatment in case of biological relapse. Four consensus guidelines have been published to standardize practices and reduce the interobserver variability in PB delineation but with discordant recommendations. To improve the reproducibility in the PB delineation, the Francophone Group of Urological Radiotherapy (Groupe Francophone de Radiothérapie Urologique [GFRU]) worked to propose a new and more reproducible consensus guideline for PB clinical target volume (CTV) definition. A 4-step procedure was used. First, a group of 10 GFRU prostate experts evaluated the 4 existing delineation guidelines for postoperative radiation therapy (European Organization for Research and Treatment of Cancer; the Faculty of Radiation Oncology Genito-Urinary Group; the Radiation Therapy Oncology Group; and the Princess Margaret Hospital) to identify divergent issues. Second, data sets of 50 magnetic resonance imaging studies (25 after RP and 25 with an intact prostate gland) were analyzed to identify the relevant anatomic boundaries of the PB. Third, a literature review of surgical, anatomic, histologic, and imaging data was performed to identify the relevant PB boundaries. Fourth, a final consensus on PB CTV definition was reached among experts. Definitive limits of the PB CTV delineation were defined using easily visible landmarks on computed tomography scans (CT). The purpose was to ensure a better reproducibility of PB definition for any radiation oncologist even without experience in postoperative radiation therapy. New recommendations for PB delineation based on simple anatomic boundaries and available as a CT image atlas are proposed by the GFRU. Improvement in uniformity in PB CTV definition and treatment homogeneity in the context of clinical trials are expected.

Visual Luminescent Probes Constructed by Eu3+ Complex-Functionalized Silica Nanocomposites and Their Langmuir-Blodgett Films at Interfaces.

The trivalent europium ion (Eu3+) has garnered a great deal of interest for the design of luminescent materials possessing compound-independent emission bands, strong luminescent intensity, and long emission lifetimes. We herein introduce a synthetic methodology capable of constructing visual luminescent probes from Eu3+ complex-functionalized silica nanocomposites and their Langmuir-Blodgett (LB) films at interfaces. In order to facilitate the coordinative stabilization of Eu3+ over carrier surfaces, silica nanoparticles (nanoSiO2) were pregrafted with terpyridyl (TPy) to make nanoSiO2TPy linkers. Then, a well-designed coordination reaction of nanoSiO2TPy with EuCl3 and 2,6-pyridinedicarboxylic acid (DPA) was carried out at solid-liquid and air-water interfaces, where our desired material (denoted as nanoSiO2TPy@EuDPA) and its corresponding LB film are obtained. The presence of TPy and DPA interacting with Eu3+ plays a key role in regulating the chemical nature of the particle surface, hence giving rise to closely packed nanocomposite arrays in the film. As a result, the improvement in uniformity and stability is achieved alongside the enhancement in emission intensity and lifetime. With such advantageous optical properties, we find them workable as facile, green, and affordable luminescent sensors, by which a range of common toxic anions (Cr2O72-, MnO4-, and PO43-) can be visually and quantitatively recognized. Notably, the LB film-based material could afford a higher Ksv value (1.53 × 105 M-1), a lower detection limit (0.157 μM), and better recyclability than its original powder analogue, showcasing its utility as a more promising candidate for practical use.

Study of temperature uniformity and thermal storage performances of a shell-and-tube type phase change plate

In this paper, a phase change plate composed of shell-and-tube latent heat storage units was investigated for air conditioning application. A mathematic model of one shell-and-tube unit was built in COMSOL software, which was then validated with experimental results. Numerical and theoretical analysis results show that the improvement of temperature uniformity and better heat transfer performances are highly related, which can be improved with larger void fraction and smaller fluid channel diameter. Optimal void fraction and fluid channel diameter were proposed for the longest effective cooling time of heat transfer fluid, which is influenced by the critical temperature of outlet air. Design parameters of phase change plate were suggested to have the fluid channel diameter less than 0.5 cm and void fraction between 0.5 and 0.7. Then, optimal phase change temperature was suggested to secure relatively long effective cooling time in a large range of air inlet temperature.

A CFD-Based Shape Design Optimization Process of Fixed Flow Passages in a Francis Hydro Turbine

In recent times, optimization began to be popular in the turbomachinery field. The development of computational fluid dynamics (CFD) analysis and optimization technology provides the opportunity to maximize the performance of hydro turbines. The optimization techniques are focused mainly on the rotating components (runner and guide vane) of the hydro turbines. Meanwhile, fixed flow passages (stay vane, casing, and draft tube) are essential parts for the proper flow uniformity in the hydro turbines. The suppression of flow instabilities in the fixed flow passages is an inevitable process to ensure the power plant safety by the reduction of vortex-induced vibration and pressure pulsation in the hydro turbines. In this study, a CFD-based shape design optimization process is proposed with response surface methodology (RSM) to improve the flow uniformity in the fixed flow passages of a Francis hydro turbine model. The internal flow behaviors were compared between the initial and optimal shapes of the stay vane, casing, and the draft tube with J-Groove. The optimal shape design process for the fixed flow passages proved its remarkable effects on the improvement of flow uniformity in the Francis hydro turbine.

Thermal Performance of a Micro Heat Pipe Array for Battery Thermal Management Under Special Vehicle-Operating Conditions

The thermal management of battery systems is critical for maintaining the energy storage capacity, life span, and thermal safety of batteries used in electric vehicles, because the operating temperature is a key factor affecting battery performance. Excessive temperature rises and large temperature differences accelerate the degradation rate of such batteries. Currently, the increasing demand for fast charging and special on-vehicle scenarios has increased the heat dissipation requirements of battery thermal management systems. To address this demand, this work proposes a novel micro heat pipe array (MHPA) for thermal management under a broadened research scope, including high heat generation rates, large tilt angles, mild vibration, and distributed heat generation conditions. The experimental results indicate that the temperature difference is maintained 3.44 °C at a large heat generation of 50 W for a limited range of tilt angles. Furthermore, a mild vehicle vibration condition was found to improve temperature uniformity by 3.3 °C at a heat generation of 10 W. However, the use of distributed heat sources results in a temperature variation of 3.88 °C, suggesting that the heat generation distribution needs to be considered in thermal analyses. Understanding the effects of these special battery-operating conditions on the MHPA could significantly contribute to the enhancement of heat transfer capability and temperature uniformity improvement of battery thermal management systems based on heat pipe technologies. This would facilitate the realization of meeting the higher requirements of future battery systems.

A strategy for improving the uniformity of radio frequency tempering for frozen beef with cuboid and step shapes

Radio frequency (RF) tempering is considered as a fast and volumetric heating technology and has been proved to be effective in meat tempering. However, the thermal runaway heating problem usually causes uneven heating at the sample edges. In this study, a newstrategy whereby the frozen meat was surrounded by selected medium was developed and evaluated in order to improve the tempering uniformity. The RF tempering uniformity improvement effects of crushed ice, ethanol solution and glycerol solution were tested with frozen minced beef with two shapes: a cuboid and a step-shape, which were reported to experience the worst tempering uniformity in RF field. The temperature/time history, temperature distribution, cook loss, total volatile basic nitrogen (TVBN) and color indexes were determined and compared after RF tempering, RF tempering with glycerol solution surrounding, and refrigeration tempering treatments. Glycerol solution (70%) was verified to be the most effective surrounding medium, which improved the tempering uniformity significantly, and also was non-toxic, non-flammable and free from odor. The temperature variation within the volume of a step-shaped beef sample was −3.7∼-5.3 °C. The beef quality attributes of RF tempering with glycerol solution surrounding the sample were the highest, and were found to be similar to those after refrigeration tempering. The RF tempering rate with immersion in glycerol solution was 40 times higher than the traditional refrigeration tempering method. Results in this study indicate that 70% glycerol solution could be an effective surrounding medium for frozen meat products in RF tempering uniformity improvement.

Surface Evaluation of a Multi-Pass Flexible Magnetic Burnishing Brush for Rough and Soft Ground 60/40 Brass.

Burnishing is an advanced finishing process that produces higher-quality surfaces with better hardness and roughness than conventional finishing processes. Herein, a flexible magnetic burnishing brush comprising stainless steel pins under permanent magnet poles was used to investigate the influence of multiple passes and directions on the produced surface of soft and rough ground prepared brass. In total, five different samples were burnished on each of the two brass samples prepared. Four samples were processed in the same direction for up to four passes and the fifth sample was processed with two passes in the opposite direction. Results indicate that there was approximately a 30% increase in hardness and an 83% increase in microroughness for rougher-surface brass samples. For smoothly prepared surfaces, there was approximately a 14% increase in hardness and a 35% increase in microroughness. In the same direction of multi-pass burnishing, increasing the number of passes negatively affected surface roughness; for rougher surfaces, the surface hardness reduced and process uniformity increased owing to surface over-hardening and flaking mechanisms, and for smoother surfaces, the hardness, roughness, and process non-uniformity increased with the number of passes owing to repeated surface deformation at some locations and high flaking at other locations. Compared to single-pass burnishing, wherein the surface roughness and microhardness showed almost no change with high process uniformity, in burnishing with two opposite-direction passes, the produced surface exhibited better surface roughness, process uniformity, and microhardness improvements owing to a reverse strain mechanism. Hence, opposite burnishing passes are recommended.

High Performance SiGe HBT Performance Variability Learning by Utilizing Neural Networks and Technology Computer Aided Design

Process sensitivity and variation, such as layer thicknesses, etch dimensions and doping levels are all process parameters that should be well understood when assessing their impact on end of process wafer quality and device performance. Improvements in uniformity of electrical device performance is often not taken into major consideration until a certain maturity level of a technology is reached. In this work, use of technology computer aided design (TCAD) and process compact models (PCM) developed from neural networks demonstrate their utility in process- parameter variation understanding in earlier stages of technology development. A TCAD simulation was built and calibrated to match key electrical performance metrics of an experimental high performance SiGe HBT in 130nm BiCMOS technology, which was the device of focus in this study. Figure 1 includes a TCAD cross section of the device1. Neural net techniques, a machine-learning methodology, the development and deployment of which has grown significantly over the last three decades, is used to expand the scope of TCAD to process variability2-3.The aforementioned calibrated TCAD deck was used to generate training data for the neural network process compact model in place of hardware data. Key process features, as listed in table 1 were a few of the process conditions that were varied from nominal values to characterize the variation in resulting electrical performance. Figure 2 includes a 1D schematic view of the epitaxial layers of the HBT, highlighting some of the process features varied in simulation. The neural network was trained using a data analysis suite using three hidden layers with 16 neurons each to get a best fit to the training data input and output values.The foundation of this approach was a TCAD simulation calibrated to match performance of the nominal HBT device of focus. Key AC and Gummel performance parameters had good agreement with hardware data as illustrated in Figure 3a and b. Thousands of individual TCAD simulations with combinations of varied process feature values were then executed to generate neural network training data in lieu of hardware data- utilizing reported standard deviations of each process parameter. The trends and sensitivity of this data was then reflected in the process compact model, which would provide results for large-scale calculation and analysis. Beta was the electrical parameter of focus in this study, where its changes in process variation (mean and standard deviation) were predicted by the trained PCM. The agreement with hardware electrical parameter Beta with respect to Boron dose in Figure 4 demonstrates how use of calibrated TCAD as a basis can empower prediction of large-scale hardware results without the extent of hardware expense. Use of this tool can be extended to simulate and analyze larger populations than what would be feasible for hardware (in several thousands) to predict the effect of process input changes on uniformity of electrical parameters. Figure 5 demonstrates how the changes in standard deviation of Beta can be predicted as a function of Boron dose variation-through generation of large simulated populations by the PCM.The resulting work on a state-of-the-art SiGe BiCMOS technology demonstrates how specific simulation tools, like TCAD-trained process compact models can be leveraged for enhanced process understanding and improvement. The data generated from these tools can supplement or replace hardware and corresponding data, saving in development costs and associated hours in manpower. They can also enable earlier and more agile decision-making about key production metrics throughout the technology development process. Calibrated TCAD infrastructure, coupled with neural-net technology have potential to fulfill pivotal roles through the timelines of technology development, rather than just being utilized when a technology is mature.

Improvement of velocity uniformity at outlets of vehicle shelter air duct

ABSTRACT The flow field in the original duct was simulated using Reynolds-average Navier–Stokes methods. Grid independence test was carried out and the air velocity at four outlets was consistent with experimental data, so the accuracy of the numerical model can be guaranteed. Vortex at the inner wall of the curved duct was identified from the simulation result, and two 75° guide plates with the thickness of 1 mm were used to reduce it. The vortex was well improved and the flow path of air became more regular than the original scheme. Guide plates with gradual increasing height along the airflow direction at the straight duct were proposed to improve the uniformity. The height of the last guide plate was set to 50 mm, the same as original scheme; then, the smallest standard deviation of velocity at four outlets is achieved with the increasing ratio of 1.4.

High Performance SiGe HBT Performance Variability Learning by Utilizing Neural Networks and Technology Computer Aided Design

Improvements in uniformity of electrical device performance is often not taken into major consideration until a certain maturity level of a technology is reached. In this work, use of technology computer aided design (TCAD) and process compact models (PCM) developed from neural networks demonstrate their utility in process-parameter variation understanding in earlier stages of technology development. A third generation High Performance Silicon Germanium Heterojunction Bipolar Transistor (SiGe HBT) was modelled and simulated as the device of focus in this study.

Effect of guide strips on the distribution of threshed outputs and cleaning losses for a tangential-longitudinal flow rice combine harvester

The transverse distribution of the threshed material in a typical tangential-longitudinal flow combine harvester is uneven and this is likely to cause local accumulation of materials on the cleaning screen. Cleaning performance and efficiency reducing problems are easily caused. In this study, discrete element simulation was applied. The distribution position of the guide strips on the threshed outputs distribution was analysed. The threshing outputs under threshing cylinder were divided into seven sections, with the total making up the threshing ration. Using the standard deviation of threshing ratio as an evaluation criterion, the optimal structural parameters of the distribution devices were obtained. In order to verify parameter accuracy, field tests were carried out to monitor the threshed outputs distribution along the transverse direction on the cleaning screen. The cleaning loss rate was analysed statistically. It was concluded that the cleaning performance of tangential-longitudinal-flow combine harvester was increased by the automatic distributing system; including threshed outputs, lateral distribution evenness along cleaning shoe was improved and local accumulation was reduced. The adaptive system decreased the criterion used for evaluation by 42%. Under a 1 m s −1 working condition, cleaning loss decreased by 71.67%, and under a 1.5 m s −1 working condition, the cleaning loss decreased by 50%. • An even-distribution flow guiding device developed with self-adaptive adjustment. • Design scheme and optimisation process using DEM simulation of guide strips. • Improvement of uniformity of the threshed outputs achieved. • Reduction of cleaning loss was realised.

Improvement in uniformity of alloy steel by pulsed magnetic field treatment

This article reports that the uniformity of the alloy steel 20Cr2Ni4A is improved by using pulsed magnetic treatment. The pulsed magnetic field with 1, 4 and 9T was applied on the tempered samples. Meanwhile the microstructures were characterized using transmission electron microscopy and magnetic force microscopy, and mechanical properties tested to verify the effect of the proposed process. It shows the contact fatigue life of alloy steel increases by 42.11% after magnetic treatment. Range of residual stresses narrows down along with rise of magnetic induction strength. The microstructures of dislocations, precipitates, and magnetic domains become more uniform under pulsed magnetic field. Besides, dislocations and precipitates were observed to transit from intergranular agglomeration to intracrystalline distribution. The energy of the external magnetic field promotes the dislocation slip and reduces high dislocation density on grain boundaries, which results in a decrease of residual stress.

Abstract 2109: Amplicon design algorithm for single cell targeted DNA sequencing using machine learning

Abstract Background: To realize the promise of precision medicine for cancer, assessing genetic variation present in rare cells and understanding the role that these cells play in the evolution of tumor progression is essential. High throughput single cell DNA targeted sequencing enables detection of rare mutations in cells and identification of subclones defined by co-occurrence of mutations. The big challenge with multiplex sequencing at single cell level is the non-uniform amplification of the targeted regions during PCR. This results in inadequate coverage of mutations of interest in the panel and hence makes genotyping challenging. To address this challenge, we developed a machine learning engine to optimize amplicon design for uniform amplification by making reliable performance prediction. Methods: Multiple panels with various sizes were designed with amplicons spanning a wide range of design properties such as amplicon GC, length, secondary structure prediction, primer specificity. These panels were synthesized and processed through Tapestri single cell DNA platform. The tested amplicons are classified into low-performer, OK-performer and high flyer based on their normalized reads-per-cell value. Design properties and property distribution of the amplicons and the panel are the features. We used random forest classifier to calculate feature importance and analyzed the range of the top features for each class and their significance of variance between classes. These ranges were then used as parameters in the assay design pipeline. Next, we train machine learning models with performance data to develop a performance prediction engine. Results: To test the performance of the design pipeline with new parameters, we designed a small (31), medium (128) and large (287) amplicon panel. Multiple runs were conducted for each panel with different cell types. We were able to achieve high panel performance of 97%, 92% and 88% across the three panels. The new parameters resulted in ~10-20% improvement in panel uniformity. We are working on further optimizing the performance prediction engine by using different ML classification models with K-fold cross validation, training using larger group of amplicons and optimizing features using combinations of properties. Citation Format: Shu Wang, Saurabh Gulati, Dong Kim, Sombeet Sahu, Saurabh Parikh, Nianzhen Li, Manimozhi Manivannan, Nigel Beard. Amplicon design algorithm for single cell targeted DNA sequencing using machine learning [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2109.

The exploration of discharge efficiency and uniformity improvement with pre-ionized bipolar pulse method in DBD device

An exploration of discharge efficiency and uniformity improvement by using pre-ionized bipolar pulse method in dielectric barrier discharge (DBD) device under atmospheric pressure is conducted. Through utilizing the pre-ionized charged particles on the dielectric surface, the amplitude of the applied pulses for sustaining discharge can be significantly decreased. By analyzing the influence of “built-in” electric field from surface charges on discharge efficiency and uniformity, a scheme of pre-ionized bipolar pulse method is proposed. Since the property of “built-in” field is closely dependent with pre-ionized pulse parameters, such as amplitude, pulse number, and polarity, the discharge uniformity and efficiency under different combinations of pre-ionized pulse parameters are investigated. According to experimental results, the discharge efficiency of the proposed method is increased by 11.8% and 17.4%, and the production efficiency of active species of N2(C3Πu→ B3Πg) is increased by 10.4% and 89.5% compared with a conventional bipolar pulse and positive pulse method, respectively, in ambient air. Moreover, the uniformity of DBD discharge is improved, and the maximum intensity difference between discharge regions is decreased from ∼20% to ∼5% compared with the one driven by the conventional positive pulse.

38‐4: A 2T1C AMOLED Display with External Compensation Reducing On‐Panel Current Variations to 0.079%

This paper presents a new compensation principle using a 2T1C pixel circuit. The implementation shows significant improvement in uniformity for all grey‐levels, due to compensation for both VT and β‐factor variations. The resulting current variation after compensation in the characterized display area reaches values down to 0.079%.