Thickness Of Dielectric Layer Research Articles

An investigation on the energy-saving potential of thermal insulating walls constructed with super thin vacuum insulated panels

Using EnergyPlus software to simulate the energy consumption of residential buildings in Harbin, Beijing, Nanjing, Haikou, and Kunming under various conditions, this study investigated the energy-saving potential of thermal insulating walls constructed with Super Thin Panel (STP). It also examined the benefits and drawbacks of the heat transfer performance of the panels, as well as the potential and viability of using STP as insulation materials. The findings demonstrated that in Harbin, Beijing, and Nanjing, the overall energy consumption for heating, cooling, and air conditioning dropped as the thickness of the insulation layer increased. Haikou had no need for any heating energy, and cooling energy use reduced as insulation thickness grew. In Kunming, the total energy consumption for cooling and air conditioning increased as insulation layer thickness grew while the energy consumption for heating reduced as insulation layer thickness increased. According to the findings, when STP panels is utilized as a thermal insulation material, its thermal insulation effect is remarkable. Under the same thermal insulation effect, the thickness was substantially thinner than that of conventional thermal insulation material. STP implementation had the biggest impact in Harbin, followed by Beijing, and had little influence in Haikou and Kunming, where there was essentially no heating demand. This implies that the use of STP vacuum insulation panels in cold areas of China has a promising future.

Integrated composite electrothermal de-icing system based on ultra-thin flexible heating film

Icing is a serious threat to the flight safety of aircraft. Lightweight and efficient electrothermal de-icing systems for carbon fiber reinforced polymer components are expected to contribute to the lightweighting and electrification of aircraft. This study presents the development and test of a novel, integrated, multifunctional composite electrothermal ice protection system. The system achieves this by incorporating a carbon-based ultra-thin flexible heating film into a carbon fiber-reinforced polymer composite laminate. T700 and M40 carbon fiber prepregs were used. The system composition and configuration were designed based on the anisotropic mechanical and thermal properties of the carbon fiber-reinforced polymer composite. The effects of ply stacking sequence, presence of insulation layer, ply angle, heating area, and prepreg type on thermal response and de-icing performance were investigated. Thermal response experiments were carried out in both room temperature and low temperature environments. A one-dimensional thermal response analysis model was developed for a representative heating structure. Comparative de-icing experiments were conducted on different samples in a low-temperature test chamber. A numerical model, based on the modified enthalpy-porosity method, was developed to simulate the de-icing process, and showed good agreement with the experimental results. Experiments and numerical calculations show that the arrangement of the heater close to the deicing surface improves the performance of the electrothermal deicing system while maintaining the overall mechanical properties of the multi-layer structure. While the insulation layer helps marginally with heat loss during de-icing, it significantly increases the system’s thermal inertia, which delays the de-icing’s start. It is recommended to minimize or eliminate insulation layer thickness. Rapid de-icing effects, combined with energy conservation, can be achieved through a short-term, high-power heating strategy.

Near-Infrared Perfect Absorption and Refractive Index Sensing Enabled by Split Ring Nanostructures.

Plasmonic nanostructures as narrowband perfect absorbers have garnered significant attention due to their potential applications in biosensing and environment detection. This study emphasizes the investigation of arrayed split ring nanostructures within the configuration of metal-insulator-metal (MIM) multilayers, resulting in a maximum light absorption of 99.94% in the near-infrared (NIR) spectral range. The exceptional absorption efficiency of the device is attributed to the strong resonance of electric and magnetic fields arising from the Fabry-Pérot cavity resonance. The resonant peak can be flexibly tuned by engineering the dielectric layer thickness, the period, and the geometric parameter of split rings. Remarkably, the device exhibits promising capabilities in sensing, demonstrating a sensitivity of 326 nm/RIU in visible wavelengths and 504 nm/RIU in NIR wavelengths when exposed to bio-analytes with varying refractive indices. This designed nanostructure can serve as a promising candidate for biosensors or environmental detection.

Detection of surface cracks on slanted surfaces and through thick irregular insulation layers using polarimetric microwave imaging

Reliable detection of cracks on slanted metal surfaces and through irregular insulation/coating is critical in many inspection applications. Microwave non-destructive testing (NDT) techniques have proven to be effective for crack detection and characterization. However, the utility of conventional microwave NDT techniques for challenging inspection scenarios which involve cracks on slanted surfaces, or cracks under relatively thick, and possibly, irregular insulation has been limited. In this paper, a polarimetric microwave imaging approach is employed for the detection of cracks in such inspection cases. The detection concept using interrogation with dual polarized wave to suppress the background is presented. It is established herein that the cross-polarization measurement is independent to irregular surfaces, and therefore, it constitutes an effective mean for reliable crack detection even if the background is not uniform or if the metal surface is slanted. This fact is further corroborated by numerical electromagnetic simulations and measurements. The efficacy of the proposed method is demonstrated using imaging results of various samples spanning the abovementioned scenarios.

Non‐Faraday Electrolyte Additives for Capacitance Boosting by Compression of Dielectric Layer Thickness: Organic Ferroelectric Salts

AbstractCarbon‐based supercapacitors are one of the most widely used commercial products. Organic electrolyte systems, such as tetraethylammonium tetrafluoroborate/acetonitrile (TEABF4/ACN), remain dominant after decades of development due to cost and performance advantages. However, improving the capacitance of existing carbon‐electrolyte systems not by altering the pore structure and surface properties of activated carbon is full of challenges. Herein, a non‐Faraday organic ferroelectric salt additive (diisopropylamine perchlorate, DIPAP) that can significantly increase capacitance from the standpoint of electrolyte dielectric modulation is proposed for the first time. Compared to counter ions, DIPA+ plays a vital role in capacity enhancement, in which electron‐rich N‐doped mesoporous carbon can greatly boost capacity by promoting local ion mobility. In situ Raman and theoretical studies show that small‐size DIPA+ can enter the pore and be enriched closer to electrode surfaces than TEA+ and ACN, allowing it to regulate the distribution of electric double‐layer species and dielectric properties (i.e., effective thickness of dielectric and/or relative dielectric constant), increasing capacity by up to 21.6–45.8% with only 1 wt% DIPAP while maintaining desired rate performances. The understanding of the mechanism of capacitance increase by such additives opens up new avenues for further extension of the commercialized carbon electrode‐organic electrolyte system's potential.

Numerical investigation on thermal runaway propagation and prevention in cell-to-chassis lithium-ion battery system

The recently emerged cell-to-chassis (CTC) technology tremendously raises the energy density of the battery pack by directly integrating lithium-ion batteries into the chassis fame, while it also brings more safety concerns involving thermal runaway propagation (TRP). However, the TRP behavior and the relevant prevention measures for the CTC battery system have not been comprehensively studied yet. In this work, a three-dimensional model was developed within the framework of OpenFOAM to investigate the TRP behavior in CTC battery packs. The heat generation was described by the electrochemistry reaction kinetics fitted in stages and the heat balance was used to address the propagation of TR. This model captures the evolution process of TRP in CTC system and five typical heat transfer modes between the TR and normal cells are identified according to simulation results. The subsequent numerical study indicates that enhancing heat dissipation can reduce the demand on critical thickness of the thermal insulation layers to inhibit TRP. However, local failure of thermal insulation can initially lead to small-scale TR and further contribute to a larger heat accumulation, putting forward higher standards for critical parameters to cease TRP. As the thickness of insulting layers increases to 2 mm, TRP can be completely ceased even when local failure of insulation occurs. This work enhances the understanding of TRP mechanism and its prevention, which can serve as new guidelines for the safety protection of rapidly developing non-module battery pack technologies.

On the super-junction formed by using field plate for lateral AlGaN/GaN-based Schottky barrier diodes

In this work, by using numerical TCAD simulations, we have systematically studied the impact of different field plates (FPs) on the electrical characteristics for lateral AlGaN/GaN-based Schottky barrier diodes (SBDs) with recessed anode. The FP enables the formation of a super-junction. When compared with the reference device without a FP, the proposed SBDs can generate charge-coupling effect between the FP and the recessed anode region, which can effectively reduce the electric field magnitude at the metal/sidewall interface. We also find that the electric field profiles can be affected by the FP length, insulation layer thickness and different insulation materials with various dielectric constants. By doing so, we can enhance the breakdown voltage by homogenizing the electric field distribution in the GaN drift layer. Then, the electric field at the recessed anode region can be decreased and the GaN drift layer can be extensively depleted.

A flexible P(VDF-TrFE)/MXene-based pressure sensor for breath and posture monitoring in football motion

Flexible capacitive pressure sensors are becoming increasingly significant in wearable electronic devices. The conventional form of pressure sensors, however, focuses primarily on microstructure design. While this approach can enhance sensitivity, it can also compromise the reliability of the sensor device. Here, we present a flexible pressure sensor according to the capacitance effect using the high dielectric P(VDF-TrFE)/MXene polymer as the capacitive pressure sensor dielectric layer. The P(VDF-TrFE)/MXene film has a high dielectric constant, making it an ideal choice for the dielectric layer of the flexible capacitive pressure sensor, resulting in rapid response and high sensing sensitivity. We also examine the impact of dielectric layer thickness on the sensor’s performance and find that increasing the thickness from 0.5 to 1.5 mm leads to a continuous improvement in sensitivity, reaching a maximum sensitivity of 0.42 kPa−1 and a wide sensing amplitude (3 Pa–25 kPa). Moreover, the response time of the capacitive pressure sensor can reach 47 ms. In addition, the sensor can be utilized to monitor human physiological information such as respiration and heartbeat. Its flexibility makes it ideal for application in sports, particularly for monitoring the movement posture of football players. Our findings can drive the wider adoption of pressure sensors in football motion monitoring.

Investigation of the Impact Properties of the Material of the Isolation on the Parameters of the Loaded Cable Lines

The thermodynamic model of work of the loaded cable line is presented. The received mathematical ratio allows to define the maximum allowed current loadings of the cable line in the form of a single-core cable product with the single-layer isolation depending on material and thickness of layer of isolation. It is constructed dependences of the maximum allowed current for a single-core wire of a certain section with one layer rubber (or polyvinilchloride) isolation from insulation layer thickness at various temperatures of the environment and the coefficients of the heat conductivity.

Disordered plasmonic nanocavity enhanced quantum dot emission

In this paper, a large-scale compatible plasmonic nanocavity design platform is utilized to achieve a nearly order of magnitude photoluminescence (PL) enhancement. The proposed design is made of multi-sized/multi-spacing gold (Au) nanounits that are uniformly wrapped with a thin aluminum oxide (Al2O3) layer, as a foreign host to form a metal–insulator–semiconductor cavity, as they are coated with semiconductor quantum dots (QDs). Our numerical and experimental data demonstrate that, in an optimal insulator layer thickness, the simultaneous formation of broadband Fabry–Perot resonances and plasmonic hot spots leads to enhanced light absorption within the QD unit. This improvement in absorption response leads to the PL enhancement of QDs. This work demonstrates the potential and effectiveness of a random plasmonic nanocavities host in the realization of lithography-free efficient emitters.

Boil-off gas precooling process for subsea low temperature LNG pipelines

Moving liquefied natural gas (LNG) ports offshore and transporting LNG to the coast through submarine pipelines can address the required water depth for LNG tankers and prevent potential safety hazards at ports in crowded waterways. At ultra-low LNG temperatures (−160 °C), pipelines should be precooled by LNG boil-off gas (−120 °C) before normal operation to avoid instantaneous LNG gasification and sharp pipe contraction. In the present study, a transient mathematical model was developed for the precooling process in a subsea multilayered LNG pipeline. Heat conductivity varied with temperature, and the governing equations were solved using the finite difference method. Additionally, the effects of pipe size, insulation layer thickness, and insulation material were investigated. The precooling time decreased significantly with increasing pipe size, and a pipe diameter in the range of 30” to 40” was suitable. In terms of economy and practical applications, the thickness of the insulation layer was suggested to be 30–60 mm. Moreover, compared with glass foam insulating material, rigid polyurethane foam exhibited better thermal performance during the precooling process. These results can assist in determining a safe precooling process for subsea LNG pipelines, providing a suitable green alternative to fossil fuels.

Interplay between Anodizing Parameters and Corrosion Resistance of Aluminum-Silicon Alloys

Aluminum alloys are widely used in the automotive, aerospace and construction fields due to their excellent physico-mechanical properties. Nevertheless, the corrosion resistance of bare Al alloys is often insufficient to meet the requirements of several industrial applications and protection strategies are needed. Among these, anodizing is particularly effective since it can lead to the formation of a compact and thick dielectric oxide layer with barrier and corrosion protection capabilities.However, anodizing of highly alloyed Aluminum alloys (e.g. those with an alloy element concentration higher than 5%wt) can be particularly challenging due to the presence of intermetallic precipitates within the Al matrix which generates micro-galvanic coupling events with an associated thickness inhomogeneity of the obtained anodic layer [1].In this context, the work investigates ten new current waveforms for anodizing of Aluminum Silicon alloys (AlSix). Particular attention is devoted to the interplay among waveform parameters (e.g. duty cycle, peak and rest step intensities), oxide layer morphology and corrosion resistance. In particular, metallography, voltammetry and contact angle methods are used in order to correlate different figures of merit with the anodic layer morphological features.It is concluded that a careful optimization of the current waveform parameters can modulate the: a) corrosion current; b) corrosion potential; c) breakdown potential; and d) polarization resistance; of coated specimens. In conclusion, the most effective waveforms are identified and coated Aluminum alloy specimens with a remarkable corrosion resistance are obtained.[1] M Bandiera, A Bonfanti, M Bestetti, F Bertasi, SAE International Journal of Advances and Current Practices in Mobility 3 (2), 973-979.

Heat Transfer Model and Thermal Insulation Characteristics of Surrounding Rock of Thermal Insulation Roadway in a High-Temperature Mine

The thermal insulation method is one of the effective methods for controlling the thermal environment of a high-temperature mine. In order to explore the thermal insulation mechanism and characteristics of thermal insulation roadways in high-temperature mines, a heat transfer model for the surrounding rock of the thermal insulation roadway was established based on the steady heat transfer theory. The temperature field of the surrounding rock of the thermal insulation roadway was studied, and the effects and sensitivities of thermal insulation layer thickness and thermal conductivity, convective heat transfer coefficient between roadway wall and airflow, and roadway radius on the thermal insulation performance of thermal insulation roadway were discussed. The results suggest the following: (1) The temperature gradient inside the thermal insulation layer is greater than that inside the surrounding rock. The thermal insulation roadway reduces the temperature difference between the original rock and the outside surface of the thermal insulation layer, thereby reducing the heat dissipation of the surrounding rock. (2) As the thermal insulation layer thickness increases, the thermal insulation capacity gradually increases, but its enhancement rate gradually weakens; as the thermal conductivity of the thermal insulation layer or the roadway radius increases, the thermal insulation capacity gradually decreases and its decline rate gradually weakens; and the convective heat transfer coefficient between the roadway wall and airflow has almost no effect on the thermal insulation capacity. (3) The thermal insulation performance of the thermal insulation roadway is highly sensitive or above the thickness and thermal conductivity of the thermal insulation layer, as well as the roadway radius. The sensitivity of thickness and thermal conductivity of the thermal insulation layer is greater than that of roadway radius. Therefore, the research results have guiding significance for the application of thermal insulation methods in the prevention and control of thermal hazards in mines.

Investigating on sensing mechanism of MoS2-FET biosensors in response to proteins

Field-effect transistor (FET) biosensors based on two-dimensional materials have gained extensive attention due to their high sensitivity, label-free detection capability, and fast response. Molybdenum disulfide (MoS2), with tunable bandgap, high surface-to-volume ratio, and smooth surface without dangling bonds, is a promising material for FET biosensors. Previous reports have demonstrated the fabrication of MoS2-FET biosensors and their high sensitivity detection of proteins. However, most prior research has focused on the realization of MoS2-FETs for detecting different kinds of proteins or molecules, while comprehensive analysis of the sensing mechanism and dominant device factors of MoS2-FETs in response to proteins is yet to investigate. In this study, we first fabricated MoS2-FET biosensor and detected different types of proteins (immunoglobulin G (IgG), β-actin, and prostate-specific antigen (PSA)). Secondly, we built the model of the device and analyzed the sensing mechanism of MoS2-FETs in response to proteins. Experimental and modeling results showed that the induced doping effect and gating effect caused by the target protein binding to the device surface were the major influential factors. Specifically, the channel doping concentration and gate voltage (V g) offset exhibited monotonic change as the concentration of the protein solution increases. For example, the channel doping concentration increased up to ∼37.9% and the V g offset was ∼−1.3 V with 10−7 μg μl−1 IgG. The change was less affected by the device size. We also investigated the effects of proteins with opposite acid–base properties (β-actin and PSA) to IgG on the device sensing mechanism. β-actin and PSA exhibited behavior opposite to that of IgG. Additionally, we studied the response behavior of MoS2-FETs with different dimensions and dielectric materials (channel length, MoS2 thickness, dielectric layer thickness, dielectric layer material) to proteins. The underlying mechanisms were discussed in details. This study provides valuable guidelines for the design and application of MoS2-FET biosensors.

Energy performance based optimization of building envelope containing PCM combined with insulation considering various configurations

Phase change material (PCM) is considered as a promising solution for reducing heating and cooling energy consumption by integrating them into the building envelope, which in turn reduces CO2 emissions. In this paper numerical simulations were carried out to evaluate the energy performance based optimization of envelope building integrated PCM. The effect of several parameters (PCM melting temperature, PCM layer combined with insulation, PCM layer and insulation layer thickness, double PCM layer system in the double external wall, and air layer interaction with PCM in roof) on energy savings in two typical models of residential buildings in Tunisia are investigated. Results show that energy demand reduction of 73.81% and 76.46% can be achieved under the optimal conditions of application of the PCM integrated in simple wall and double wall buildings respectively. This is associated with significant reduction of CO2 emission. Moreover, PCM layer performance is improved by increasing its thickness with an optimal value of 6 cm. Two PCM layers located in the middle of the double wall involve higher energy saving than a simple PCM layer.

Thermal insulation characteristics of high-temperature heat seals for hypersonic aero-engines

The high-temperature baseline sealing thermal protection technology is of great significance to realizing hypersonic aero-engines and aircraft. Based on the fact that there are few studies on the high-temperature baseline heat sealing in the ultra-high temperature environment (above 1000 °C), the paper establishes a simulation model to analyze the influence of different characteristic parameters on the thermal protection performance of the heat seal at ultra-high temperature and carried out experiments. Verification, simulation, and experiment error are less than 6%. The research results show that the aluminum silicate fiber has the best thermal insulation effect in the material of the inner thermal insulation layer, and the temperature can be lowered by more than 900 °C under an environment of 1200 °C. It is used to prepare heat seals. In addition, the filling density and thickness of the inner thermal insulation layer have little influence on the thermal insulation effect, and the influence coefficient does not exceed 5%. In the test of the degree of degradation of the thermal insulation performance of the heat seal, it is found that it does not exceed 5%, which meets the requirements for use. This paper further promotes the development of high-temperature thermal protection technology. It can also provide a corresponding technical basis for developing supersonic aero-engines.

The Ultra-Large-Bandwidth Cascade Full-Stokes-Imaging Metasurface Based on the Dual-Major-Axis Circular Dichroism Grating.

A dual-major-axis grating composed of two metal-insulator-metal (MIM) waveguides with different dielectric layer thicknesses is numerically proposed to achieve the function of the quarter-wave plate with an extremely large bandwidth (1.0-2.2 μm), whose optical properties can be controlled by the Fabry-Pérot (FP) resonance. For the TE incident mode wave, MIM waveguides with large (small) dielectric layer thicknesses control the guided-mode resonant channels of long (short) waves, respectively, in this miniaturized optical element. Meanwhile, for the TM incident mode wave, the propagation wave vector of this structure is controlled by the hybrid mode of two gap-SPPs (gap-surface plasmon polaritons) with different gap thicknesses. We combine this structure with a thick silver grating to propose a circularly polarizing dichroism device, whose effective bandwidth can reach an astonishing 1.65 μm with a circular polarization extinction ratio greater than 10 dB. The full Stokes pixel based on the six-image element technique can almost accurately measure arbitrary polarization states at 1.2-2.8 μm (including elliptically polarized light), which is the largest bandwidth (1600 nm) of the full Stokes large-image element to date in the near-infrared band. In addition, the average errors of the degree of linear polarizations (Dolp) and degree of circular polarizations (Docp) are less than -25 dB and -10 dB, respectively.

Long-range surface plasmon resonance-based hollow fiber temperature sensor with ultrahigh sensitivity and tunable detection range.

A dielectric/Ag-coated hollow fiber (HF) temperature sensor based on long-range surface plasmon resonance (LRSPR) is proposed and experimentally demonstrated. The structural parameters, including the dielectric material and layer thicknesses, are optimized through comprehensive theoretical analysis to achieve the best performance. By filling it with a high refractive index (RI) thermosensitive liquid, the GK570/Ag-coated HF temperature sensor with optimal structural parameters is fabricated. Due to the high sensitivity of the LRSPR sensor and the optimized design, the fabricated sensor achieves a temperature sensitivity of 3.6∼20.5 nm/°C, which is almost the highest among the optical fiber temperature sensors based on surface plasmon resonance reported experimentally. Moreover, the detection range of the proposed sensor can be easily tuned up to 170°C by varying the RI of the filled thermosensitive liquid, and the sensor performance remains stable. Considering that most temperature sensors using polydimethylsiloxane have a fixed detection range, this is an outstanding advantage that could expand the application field of the optical fiber temperature sensor.

The multi-factor influence of frost resistance and prevention effect of tunnel thermal insulation layer in cold areas

To figure out the thermal insulation effect of tunnel thermal insulation layer under the action of different factors in cold areas, the heat transfer analysis module in ABAQUS software was used for the Jiangluling Tunnel to numerically simulate the temperature change of the lining. The said thermal insulation effect under different insulation layer laying methods, insulation material heat conductivity coefficients, insulation layer thickness values, and air temperature conditions was analyzed based on the range of Heat Regulation Circle (HRC), and the empirical equation proposed by Japanese Scholar Kurokawa Yoshinori was employed to calculate the laying length of thermal insulation layer, which was then verified by the safety coefficient of tunnel lining structure. The research results showed that, after the thermal insulation layer had been set, the radial depth of annulus of HRC decreased significantly, indicating that the convective heat transfer of cold air had been suppressed; from high to low, the thermal insulation performance of thermal insulation layer installed by different laying methods was: double-layer style, wall-attaching style, composite filler style, and wall-detaching style. When installing thermal insulation layer for the Jiangluling Tunnel, the wall-attaching style thermal insulation layer is suggested; the thickness of thermal insulation layer should not be less than 5.5 cm; the thermal insulation material should take a thermal conductivity coefficient between 0.025 and 0.04 (W/m.k) and be laid throughout the entire tunnel; when the temperature drops below −17 °C, extra thermal insulation measures should be taken to ensure the frost resistance and prevention ability of the tunnel structure.

Phase field study on the flexoelectric response of dielectric–ferroelectric multilayers

We report a theoretical modeling of the flexoelectric response of dielectric–ferroelectric (DE–FE) multilayers based on phase field simulations in the framework of the Landau–Ginzburg–Devonshire (LGD) theory. The correlation between negative capacitance and flexoelectric response is revealed, and the single-domain and multi-domain models are compared. It shows that the dielectric layers drive the ferroelectric layer into a negative capacitance regime, and the flexoelectric response of the multilayer is maximal when the negative capacitance of the ferroelectric layer has a minimal absolute value. Moreover, the flexoelectric response peak will be shifted to a lower temperature by increasing the thickness of dielectric layer, indicating a possibility of achieving a stronger flexoelectric response at room temperature compared with that of pure ferroelectric. However, while the single-domain model shows that the flexoelectric response peak is simply shifted to a lower temperature with near constant peak value and width, the multi-domain model reveals a significant suppressing of the flexoelectric peak by the dielectric layer. This is attributed to the formation of the vortex domain state, which eases the depolarization effect and leads to large absolute value of negative capacitance of the ferroelectric layer. Our work provides new insights into flexoelectricity in ferroelectric heterostructures.