Improvement Of Uniformity Research Articles

Microwave Hyperpolarization Effect─An Orthogonal Incoherent Microwave Field Heating Study.

In our previous study, the incoherent combined microwave sources possess a higher water heating rate than a single microwave source. This novel discovery may blaze a new trail in the pursuit of energy conservation. In this paper, a particular orthogonal microwave field device was designed to quantitatively study the effect of incoherent combined microwave heating on 17 solvents. Experimental results indicate that the solvents irradiated with incoherent combined microwaves absorb more microwave energy and experience a faster temperature rise. The multiphysics simulations of water with different microwaves show that the higher heating rate is not caused by the improvement of heating uniformity. In this regard, molecular dynamics simulations of ethanol under the irradiation of incoherent microwave electric fields with perpendicular polarization directions were carried out. The molecular dynamics simulations demonstrate that the main reason for this effect is the higher collision frequency of molecules with incoherent microwave electric fields. This study demonstrates a novel effect of incoherent combined microwave heating and contributes to the development of efficient microwave heating for industrial applications.

The integrated multi-performance fast optimization strategy for battery thermal management system

Increased battery energy density is required to boost electric vehicle endurance; however, this also raises the possibility of thermal runaway and power battery explosion. Improving the cooling system performance requires optimization and enhancement of classical systems. Traditional design approaches struggle to simultaneously enhance multiple aspects of performance, while an optimization based on Computational Fluid Dynamics (CFD) methods is often inefficient. Therefore, by integrating a flow resistance network model (FRNM) with a weighted average optimization algorithm (INFO), an efficient optimization for the comprehensive performance of the system can be achieved. Five optimized systems under different airflow rates were obtained through optimization. A comparison with two existing systems validated the effectiveness of the optimized system. The results demonstrate that, compared to the two reference systems, the optimized system decreases the maximum temperature difference by 65.51 % and 39.07 %, respectively. Furthermore, the improvement in temperature uniformity is more significant, increasing by 63.76 % and 34.40 %, respectively.

Threshold voltage uniformity improvement by introducing charge injection tuning for low-temperature poly-Si thin film transistors with metal/oxide/nitride/oxide/silicon structure

Low-temperature poly-Si thin film transistors (TFTs) with a metal/oxide/nitride/oxide/silicon structure were fabricated to investigate the feasibility of suppressing threshold voltage variations between TFTs. By applying relatively high positive and negative gate bias voltages, threshold voltage could be tuned positively and negatively, respectively, by injecting charges into the charge trap layer. Stability of threshold voltage against positive gate bias at a level close to the actual circuit operation was not degraded compared with the case of an as-fabricated TFT. A uniform threshold voltage distribution could be achieved in a preliminary test using 16 TFTs by converging threshold voltages with a target value by tuning the threshold voltage for each TFT.

Improvement of the resistivity uniformity of 8-inch 4H–SiC wafers by optimizing the thermal field

8-inch N-type 4H–SiC single crystals were grown on 4° off-axis seeds by the physical vapor transport (PVT) method. The electrical properties of 8-inch 4H–SiC wafers were assessed by contactless resistivity mapping. The resistivity of the whole wafer is inhomogeneous with an inhomogeneity of 4.8 %, much higher than that of standard 6-inch wafers with a resistivity inhomogeneity of 1.2 %. This nonuniformity phenomenon is attributed to facet formation caused by discontinuities in the thermal field as the crystal diameter increases. Due to the facet effect, the nitrogen doping concentration in the facet region is higher than that in other regions. By optimizing the thermal field through adjustment of the growth conditions, a nearly flat and slightly convex 8-inch SiC crystal growth interface was obtained. The uniformity of the resistivity of 8-inch SiC wafers is significantly improved, with an inhomogeneity of 1.6 %.

Study on the Influence of Fan and Fan Cowl on Intake Air Parameters of Cooling Module

Abstract Due to the increase in heat load, the demand for heat dissipation of the cabin cooling module has increased. The fan arrangement and the design of the fan cowl can significantly affect the intake air parameters, thereby affecting the performance of the heat exchangers. In this paper, the whole vehicle model was set up and the effect of the fan installation distance, the fan cowl coverage ratio, and the radial extension of the fan cowl outlet was researched by numerical simulation. The results show that due to the relative position of the layout of the cooling module, the effect of the fan arrangement and the fan cowl design on the intake parameters of the radiator is greater than that of the intercooler. The improvement of the air velocity uniformity can reduce the intake air average temperature for better heat dissipation, a 2% improvement in air intake velocity uniformity can lead to a 6% reduction in air intake average temperature event at a low air mass flow. The greater installation distance of the fan or the higher closing degree of the fan cowl, the more favorable intake parameters to ensure the better cooling performance of the heat exchangers. Moreover, when the fan cowl coverage ratio reaches 0.9, the air intake average temperature increases by 5.6%, which means that the fan cowl coverage should not be too high. This study will provide useful reference information for the design of cooling modules in the cabin.

生物刺激素“秋实皆”和“思甜”对阳光玫瑰果重和果实均匀度的改善

生物刺激素“秋实皆”和“思甜”对阳光玫瑰果重和果实均匀度的改善

Efficiency uniformity improvement of gratings for head-up display waveguide using multilayer perceptron network

Efficiency uniformity improvement of gratings for head-up display waveguide using multilayer perceptron network

High-precision and high-speed etching of diamond surfaces using Fe–Ni alloy catalyzed H–O plasma etching

Power devices with low losses are essential for achieving high-efficiency, low-cost, and miniaturized inverters and advance electronic technologies. Recently, diamond-based p-type groove semiconductor field-effect transistors have emerged as a hot research topic. Conventional method of fabricating surface grooves using inductively coupled plasma etching is costly and relatively slow. Here, we realized a novel diamond machining method using Fe–Ni alloy catalyzed H–O microwave plasma etching that can achieve high-rate and high-precision etching of diamond surfaces. Two major factors affecting the etching rate and pattern accuracy, wettability of diamond and carbon solubility with liquid metal, were identified. Oxygen added in H2 plasma allows the wetting increase, resulting in an improvement in uniformity of the etch area, while keeping the etch rate as high as 3 μm/min. The developed approached is promising for low-cost diamond patterning in electronic devices fabrication processes.

Heat transfer and flow analyses of microchannel heat sink with twisted blade-like fins

To enhance heat transfer coefficient, decrease pressure penalty, and improve wall temperature uniformity, a twisted blade-like fin with low-drag airfoil section is proposed in this study. The flow and heat transfer performances of microchannels with the fins are numerically investigated at Re = 50–700. Results show that the novel fins improve the heat transfer (Nu/Nu 0) significantly with a small pressure penalty (f/f 0), and thus show an excellent comprehensive thermal performance (TP). The ranges of Nu/Nu 0, f/f 0 and TP are 1.16–4.76, 1.51–2.36, and 1.01–3.58, respectively. The TP of TAMCHS reaches 3.58, exhibiting an increase of 46.7, 37.7, 22.6, and 16.6% compared to four models in previous study. The reduced pressure penalty is attributed to the streamlined configuration, and the improved heat transfer coefficient is attributed to the normalwise secondary flow stimulated by the twisted fins, which enhances heat transfer in the upper portion of the channel. Compared to a smooth microchannel heat sink (SMCHS), the major advantages lie in the significant reduction of sidewall temperatures and notable improvement in temperature uniformity on the top and bottom walls. The average and maximum wall temperature are reduced by 48.1 and 49.0 °C at most, respectively, and the greatest decline of wall temperature gradient is 55.0 °C.

Thermal Performance Analysis of Liquid Cooling System in Lithium-ion Battery

Electric vehicles (EV) have been rapidly developing and are becoming increasingly popular due to its zero emission, low operating cost and noise free. However, there are some factors that limit the development of electric vehicles, such as the thermal performance, cost, lifetime and safety of the battery. To address this difficulty integration of liquid cooling system is the promising solution. The battery cooling technologies like air cooling system, liquid cooling system, direct refrigerant cooling system, phase change material (PCM) cooling system are used in e-vehicle. In this research, the main goal is to better understand how to improve the consistent temperature distribution in battery packs. The study provides general strategies to reduce thermal unevenness or achieve almost no differences in temperature within lithium-ion battery modules. These modules are cooled using channelled liquid flow, where a liquid circulates through channels designed for thermal management. To demonstrate the effectiveness of the proposed strategies, the research numerically analyzes two cases: one with multiple short channels and another with orderly magnified contact areas. Two of the methods demonstrate significant improvement in the overall thermal uniformity of the battery pack.(a) Shortening flow paths with multiple serpentine channels, and (b) enhancing contact areas between batteries and serpentine channels along the flow path in the stream wise direction, both show considerable promise in improving pack thermal uniformity.The study investigates the thermal effects of varying liquid flow rates in a computational fluid dynamics model for an 71 18,650 battery pack discharged at 5C. A three-dimensional model is built in ANSYS and the mesh is generated using Fluent Meshing. The maximum temperature differences observed across the battery module during a 5C discharge are 2.2 K for one strategy and 0.7 K for the other. This information highlights the effectiveness of the second strategy in achieving lower temperature variations, indicating better thermal uniformity during the discharge process compared to the first strategy.

Effects of nanocarbon and nano‐calcium carbonate on soil enzyme activities and soil microbial community in wheat (Triticum aestivum L.) rhizosphere soil

AbstractBackgroundNanofertilisers can enhance the efficiency of nutrient utilization in crop production. Nevertheless, it is unclear how soil microbial and enzyme activities are affected by the application of nanofertilisers to wheat inter‐root soil.AimsThe study aims to investigate the influences of nanocarbon (NC) and nano‐calcium carbonate (NCC) on soil enzyme activities and microbial community in the open field setting.MethodsThe effects of nanofertilisers on soil wheat rhizosphere soil were studied through the evaluation of soil microbial quantity, enzyme activity, and microbial diversity.ResultsThe findings revealed that the combined utilization of nanofertilizers and compound fertilizers (CF) led to an augmentation in the diversity of the soil microbial community. When comparing the effects of 100% composite nanofertilizers (100% CF + 50% NC + 50% NCC) with the control (CK) (100% CF), it was observed that the activities of urease (EC 3.5.1.5), catalase (EC 1.11.1.6), alkaline phosphatase (EC 3.1.3.1), sucrase (EC.3.2.1.26), as well as the number of fungi, actinomycetes, and bacteria, increased by 22.4%, 7.7%, 17.8%, 9.3%, 35.9%, 27.7%, and 26.0%, respectively. Similarly, the employment of 70% composite nanofertilizers (70% CF + 35% NC + 35% NCC) also resulted in an enhancement of these aforementioned indicators. The magnitude of increase over the 100% CF was 19.0%, 6.6%, 13.6%, 6.2%, 26.8%, 21.3%, and 23.5%, respectively. Notably, there was no significant difference observed between 100% CF + 50% NC + 50 % NCC and 70% CF + 35% NC + 35% NCC within the 0–35 d after anthesis. Furthermore, both 100% CF + 50% NC + 50% NCC and 70% CF + 35% NC + 35% NCC contributed to an improvement in the species uniformity and operational taxonomic unit abundance of wheat rhizosphere microorganisms, while also increasing the abundance of Proteobacteria and Actinobacteria compared to the CK. The relative abundance of Bacteroidetes and Actinobacteria was found to be elevated in the nanomaterials‐treated groups, both at 0–7 d and 14–21 d after anthesis, and positively correlated with soil enzyme activities and soil microbial populations.ConclusionsThese results indicate that the application of composite nanofertilizers can enhance the soil microenvironment in wheat fields, particularly under reduced fertilization conditions.

New design for PVT system with elliptic cooling duct involving nanofluid in existence of MHD and utilizing TEG

This research investigates the integration of a thermoelectric-enhanced cooling elliptic duct into a photovoltaic solar system. Employing the finite volume method, the simulation aims to analyze the system's performance. Furthermore, the introduction of a magnetic field is explored as a strategy to boost electricity generation and overall system efficiency. The study is driven by the pursuit of enhanced energy conversion and a thorough comprehension of the complex dynamics within solar energy configurations. The nanofluid laminar flow within elliptic duct has been affected by magnetic force and better cooling has been achieved. Impacts of Wdust (amount of dust), Vi (inlet velocity into elliptic tube), Ha (Hartmann) and φ (fraction of additives) on thermal (ηth) and electrical (ηe) performance have been discussed in output section. With deposit of dust, ηth and ηe decrease about 9.07 % and 23.5 %. With rise of Ha, the uniformity of temperature over silicon layer improves and amounts of ηe and ηth increase about 1.18 % and 6.85 %.With mixing water with nanoparticles, the performance of panel enhances and positive effect enhances about 65.73 % and 7.35 % with elevate of Vi, in view of ηe and ηth, respectively. The enhancement of ηe and ηth with rise of Ha improves about 80.81 % and 15.1 % for greater Vi. As Vi intensifies, the better cooling occurs and amounts of ηe and ηth enhances about 4.03 % and 30.26 %. Achieving a uniform temperature distribution across the panel is crucial for assessing its performance. Increasing Vi and Ha leads to a substantial improvement in uniformity, with enhancements of approximately 47.35 % and 4.66 %, respectively. This indicates a more balanced heat distribution, which is a positive indicator of the system's efficiency.

Improvement of spin polarization and spatial uniformity in atomic magnetometers with reflection optimization

Improvement of spin polarization and spatial uniformity in atomic magnetometers with reflection optimization

Optimization of the structure and cathode operating parameters of a serpentine PEMFC with longitudinal vortex generators by response surface method

An improved method based on a concept for enhancing heat and mass transfer based on longitudinal vortex system is proposed for optimizing the performance and water-thermal management of proton exchange membrane fuel cells (PEMFCs). A certain number of rectangular plates are added to the cathode channel of the serpentine plate to create the longitudinal vortex to enhance the diffusion of fuel gas, the discharge of water, and temperature distribution uniformity of the fuel cell. A series of numerical studies are conducted employing the response surface method to evaluate the effect of cathode operating parameters on the efficiency and power density of the fuel cell system. The results obviously suggest that the installation of twenty groups of Longitudinal vortex generators(LVGs) in the first four straight flow channels can enhance the mean current density by 5.02 % compared with the condition without LVGs. Meanwhile, LVGs in the cathode flow channel close to the inlet can also enhance the distribution uniformity of membrane temperature by 11.38 %, which can contribute to the diffusion enhancement of oxygen by 36.94 % at the cathode and the improvement of water distribution uniformity by 10.87 %. The main reason for this phenomenon is that the rectangular-plate longitudinal vortex generator can increase the local turbulence intensity of the fuel gas in the cathode channel; therefore, more fuel gas can be transported from the channel to the diffusion layer, leading to a greater current density, in addition to the fact that the generated longitudinal vortex system can assist the exiting of the generated water from the channel. In addition to these, increasing pressure or reducing temperature or relative humidity can enhance power density, while reducing relative humidity is beneficial for improving system efficiency.

Spectroscopic Reflectometry for Optimizing 3D Through-Silicon-Vias Process

The main challenges in 3D metrology involve measuring TSVs etched with very high aspect ratios, where the via depth to diameter ratio approaches 10:1–20:1. In this paper, we introduce an innovative approach to enhance our in-house spectroscopic reflectometer module by integrating aperture technology, resulting in a substantial amplification of interference signals. Our system offers the flexibility to conduct measurements on an average number of TSVs, individual TSVs, or specific periodic arrays of TSVs. Additionally, we demonstrate the utility of the spectroscopic reflectometer as a non-destructive, high-speed metrology solution for in-line monitoring of TSV etch uniformity. Through a series of experimental trials in a reactive ion etch (RIE) process, we show that leveraging feedback data from the reflectometer leads to marked improvements in etch depth uniformity.

Heat transfer enhancement and temperature uniformity improvement of microchannel heat sinks with twisted blade-like fins

To enhance heat and fluid exchange between main flow and near-wall flow in microchannels, a twisted blade-like fin with an advantage in stimulating both spanwise and normalwise secondary flow is proposed. The cross sections of the fin are low-drag airfoils in different orientations. The flow and heat transfer performances of microchannels with fins are numerically investigated at Re = 50–700. The results show that the twisted blade-like fin improves heat transfer process significantly, especially wall temperature uniformity, and reduces the flow separation region behind the fin, resulting in an obvious small pressure penalty. At small inflow (Re = 50), the best heat transfer and lowest pressure penalty are obtained in the microchannel with a single fin. When Re > 150, better heat transfer is obtained in the microchannel with three fins, and the highest comprehensive thermal performance (TP) reaches 3.58. The twisted direction of fins has a significant effect on heat transfer but less on flow drag. Due to the twisted fins, left and right walls experience an overall decline in temperature, and the temperature uniformity of top and bottom walls is improved. Compared with a smooth microchannel, the average and maximum temperature of the investigated microchannels are reduced by 48.1 K and 49.0 K at most respectively.

Improvement of airflow uniformity and noise reduction with optimized V-shape configuration of perforated plate in the air distributor

The air distributor is the end component of the ventilation system, and its performance directly determines the comfortable and pleasant feeling of the residence. A perforated plate can be added to the air distributor to convert dynamic pressure into static pressure first and then distribute the air flow, which provides better self-adjustment compared with the embedded guide vane structure. However, the perforated plate can lead to a contradiction between head loss, noise and distribution uniformity. To reconcile this problem, a novel V-shape configuration of the perforated plate was put forward in this study. The internal flow and aeroacoustic properties of different types of perforated plates were systematically studied, and a full-scale test platform was built to verify the flow characteristics. The effects of hole size and installation position of the perforated plate on the uniform distribution of air flow were analyzed by the parametric analysis method. Then, the sound pressure level of the optimized perforated plate air distributor was further analyzed. The results show that, with the optimized perforated plate structure, the uniform flow performance was improved by about 30% and the overall sound pressure level was reduced by up to 12 dB.

Heat transfer enhancement by inserting a radiation-turbulence component in a wedge channel

This study proposed the concept of coupled convective and radiative heat transfer enhancement to improve the internal cooling near turbine blade's trailing edge. An original method, which employed a radiation-turbulence component inside a wedge-shaped channel was developed. Flow and heat transfer for four channel configurations were studied numerically. The results indicated that, in condition of Re=10,000 and q = 10,000 W·m−2, compared with the existing channel's configuration merely with pin-fins and without considering radiation (Model NN), the total Nusselt number ratio of the channel using the radiation-turbulence component (Model YY) increased by 48.10 %. The maximum temperature dropped by 354.73 K and the average temperature dropped by 38.59 K. This was attributed to extension of cold surfaces for enhancement of radiative heat transfer and change of flow disturbance distribution for improvement of convective heat transfer uniformity, both of which were induced by using the radiation-turbulence component. Furthermore, the influences of the Reynolds number as well as the wall heat flux were explored. This method was proved to have an excellent self-adaptive ability, which showed that the increase of the thermal load resulted in the growth of the total Nusselt number.

Effect of Hot Isostatic Pressing on Microstructure and Properties of GH4169 Superalloy Manufactured by SLM

During the additive manufacturing of the GH4169 superalloy, various defects including cracks and holes can occur in the alloy. In this study, the effects of distinct HIP temperatures and pressure on the microstructure and mechanical properties of GH4169 were studied utilizing the metallographic microscope(OM), scanning electron microscope(SEM), X-Ray diffraction(XRD), density, microhardness, and tensile experiment. SEM and XRD results indicate that HIP can alter the texture of the matrix phase and dramatically modify the microstructure of the test alloy manufactured by SLM. Following HIP, density increases due to the pore closure of GH4169, and the hardness decreases due to the decomposition of Laves phase. Tensile testing revealed that increasing HIP temperature and pressure led to a slight reduction in the tensile strength and yield strength of the test alloy, while elongation exhibited an opposite trend. Furthermore, the increase in elongation is attributed to the improvement of the microstructure uniformity of the test alloy by HIP. And the evidence suggested that 1165°C, 155MPa is an optimal HIP parameter. Besides, the resulting alloy has a high tensile strength (1046MPa), yield strength (654MPa), and elongation (42%). The Laves phase and carbide are evenly distributed. This optimal HIP parameter will facilitate subsequent heat treatment for obtaining higher mechanical properties of the alloy.

Uniformity improvement of a mini-LED backlight by a quantum-dot color conversion film with nonuniform thickness.

Mini-LED backlights energized by quantum-dot color conversion (QDCC) hold great potential for technological breakthroughs of liquid crystal displays. However, luminance uniformity issues should still be urgently solved owing to the large interval of direct-lit mini-LEDs, especially when covering with a QDCC film (QDCCF) with uniform thickness. Herein, we propose a uniformity improvement approach of mini-LED backlights by employing a QDCCF with nonuniform thickness based on the Lambertian distribution of mini-LEDs, which is demonstrated by screen-printing preparation and ray-tracing simulation. Experimental results show that the luminance uniformity of the nonuniform QDCCF can reach 89.91%, which is 24.92% higher than the uniform one. Ray-tracing simulation further elaborates the mechanism of this significant improvement. Finally, by employing this nonuniform QDCCF, a mini-LED backlight prototype is assembled and achieves high uniformity of 92.15%, good white balance with color coordinates of (0.3482, 0.3137), and high color gamut of 109% NTSC. This work should shed some new light on mini-LED-based display technology.