Effect Of Lateral Diffusion Research Articles

Ballistic performance of aluminum alloy plates with polyurea coatings for high-speed train structures

Polyurea coatings have been widely promoted in explosion and ballistic impact protection applications due to their excellent hyper-elasticity performance. In rail transportation, high-speed trains face potential impact threats from track ballast, which can affect the strength performance of the base material. To address these challenges, we examined the ballistic performances of aluminum alloy plates with polyurea coatings under large-scale impact (>30 mm). Four different configurations of target plates were investigated: A, P-A, A-P, and P-A-P. We fabricated samples and performed dynamic impact tests using an air cannon system to demonstrate the feasibility. Results show that ballistic performance is significantly improved by applying polyurea coatings on aluminum alloy plates. In particular, the growth rate of limit velocity of configuration A-P, P-A, and P-A-P to that of configuration A are 5.5 %, 19.4 %, and 22.8 %, respectively. The enhancement mechanism was further uncovered through stress wave propagation analysis and lateral energy diffusion effect. Explicit formulas for predicting the limit velocity and residual velocity were derived and demonstrated with reasonable accuracy over a wide range of parameter spaces. The observed enhancement in ballistic performance through polyurea coatings on aluminum alloy plates offers promising ways to design and implement more resilient and impact-resistant high-speed train structures.

P‐10.11: Pixelation of Nano‐LED arrays with high effective light‐emitting area ratio by ion injection: A Simulation study

The etch damage caused by the conventional bench-top etching process makes it difficult to produce Nano-LED devices. Recently, some scholars have studied the use of ion injection to achieve electrical isolation between pixels for the purpose of pixelation. In this paper, we focus on the distribution characteristics of ions in GaN targets to improve the effective light-emitting area ratio of devices by reducing the lateral diffusion effect of ions.

Analysis of Rainfall Erosion and Protective Measures for the Aeolian Sand Subgrade Slope of the Wuma Expressway

It is difficult to build roads in the desert areas with wind-blown sands because the prevailing harsh environment and the characteristics of the aeolian sands inhibit strategies and measures for road damage prevention and control that are typically effective in other settings. Typically, the rainfall period in aeolian sand areas worldwide is concentrated and the rainfall volume is relatively large, which combined with small and unstable nature and the aeolian sand particles means roads built in these areas can be easily washed away and are vulnerable to water damage. Given geological conditions, topographic features and hydrometeorological conditions differ depending on the region, basic research into water damage in highway roadbed slopes in aeolian sand areas is necessary to formulate treatment measures that are versatile and applicable in different regions. Towards that end, this study strengthens the evaluation of roadbed and pavement drainage and protective measures given aeolian sand erosion caused by rainwater infiltration in certain longitudinal length sections of the Expressway K165 + 250 mileage pile section, and includes verification of the design scheme. The effects of rainwater drainage, storage, and subgrade reinforcement on the seepage and stability of drainage in a long longitudinal slope in the desert hinterland were quantitatively analyzed using numerical analysis. Additionally taking into account the regional climate environment characteristics that locally prevail, the necessity and applicability of geotechnical reinforcement in practical engineering applications is demonstrated. The research found the stability of the subgrade slope given potential for rainfall erosion due to concentrated-rainfall periods in an aeolian sand region is promoted through measures including slope drainage on the highway combined with side ditch drainage, strengthening of the box culvert under embankment ditches, and local protection by laying geogrid in the embankment to produce a significant lateral diffusion effect.

Effect of ionic conduction under dielectric barriers on PEDOT:PSS electrochemical interfaces

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been widely used for electrochemical interfaces. When the surface is covered by an inhomogeneous dielectric layer, ions are injected to the uncovered part of PEDOT:PSS and then laterally diffuse to the covered part. However, this effect has not been incorporated into the device model. Here we show the effect of lateral ionic diffusion on the transient response of electrochemical interfaces. When PEDOT:PSS is partially covered by a dielectric layer, the covered part contributes to the electrochemical admittance unlike metal electrodes. This effect also makes the transient performance of organic electrochemical transistors deviate from conventional models.

Multi-scale gapped smoothing algorithm for robust baseline-free damage detection in optical infrared thermography

Flash thermography is a promising technique to perform rapid non-destructive testing of composite materials. However, it is well known that several difficulties are inherently paired with this approach, such as non-uniform heating, measurement noise and lateral heat diffusion effects. Hence, advanced signal-processing techniques are indispensable in order to analyze the recorded dataset. One such processing technique is Gapped Smoothing Algorithm, which predicts a gapped pixel's value in its sound state from a measurement in the defected state by evaluating only its neighboring pixels. However, the standard Gapped Smoothing Algorithm uses a fixed spatial gap size, which induces issues to detect variable defect sizes in a noisy dataset.In this paper, a Multi-Scale Gapped Smoothing Algorithm (MSGSA) is introduced as a baseline-free image processing technique and an extension to the standard Gapped Smoothing Algorithm. The MSGSA makes use of the evaluation of a wide range of spatial gap sizes so that defects of highly different dimensions are identified. Moreover, it is shown that a weighted combination of all assessed spatial gap sizes significantly improves the detectability of defects and results in an (almost) zero-reference background. The technique thus effectively suppresses the measurement noise and excitation non-uniformity. The efficiency of the MSGSA technique is evaluated and confirmed through numerical simulation and an experimental procedure of flash thermography on carbon fiber reinforced polymers with various defect sizes.

Influence of the accumulation chamber insertion depth to measure surface radon exhalation rates

A common method to measure radon exhalation rates relies on the accumulation chamber technique. Usually, this approach only considers one-dimensional gas transport within the soil that neglects lateral diffusion. However, this lateral transport could reduce the reliability of the method. In this work, several cylindrical-shaped accumulation chambers were built with different heights to test if the insertion depth of the chamber into the soil improves the reliability of the method and, in that case, if it could limit the radon lateral diffusion effects. To check this hypothesis in laboratory, two reference exhalation boxes were manufactured using phosphogypsum from a repository located nearby the city of Huelva, in the southwest of Spain. Laboratory experiments showed that insertion depth had a deep impact in reducing the effective decay constant of the system, extending the interval where the linear fitting can be applied, and consistently obtaining reliable exhalation measurements once a minimum insertion depth is employed. Field experiments carried out in the phosphogypsum repository showed that increasing the insertion depth could reduce the influence of external effects, increasing the repeatability of the method. These experiments provided a method to obtain consistent radon exhalation measurements over the phosphogypsum repository.

Size estimation of coating disbonds using the first derivative images in pulsed thermography

It has been a challenging task to estimate the size of thermal barrier coating disbonds by pulsed thermography, because thermal images are naturally blurred by lateral heat diffusion around the edge of defect. In the present work the first derivative images were employed to weaken the effect of lateral thermal diffusion, in a similar way as for Full Width at Half Maximum (FWHM) based on thermal images. Theoretical analysis introduced the correspondence of thermal profile and the first derivative profile along diameter of an in-plane defect, it’s found that half maximum points of two side dips in the first derivative profile is much closer to the real defect edge than the half maximum points of positive peak in temperature profile. Experimental results suggested that FWHM-1st based on the first derivative images generated more precise estimated values of coating disbonds than FWHM did. In addition, Evolution of FWHM and FWHM-1st in cooling process also revealed that it’s the early images in regular regime of transient heat conduction give more precise estimation of disbonding size instead of traditionally considered early images just at the final instant of optical pulse.

NDT inspection of aeronautical components by projected thermal diffusivity analysis

ABSTRACT This paper analyzes the application of an innovative method for thermographic NDT data processing to inspections on real aeronautical components. The results provided by this method are related to thermal diffusivity values obtained by projecting the characteristics of a 3D thermal diffusion model onto one of the coordinate planes. In previous studies, laboratory experiments demonstrated that this method produces a higher increase in the signal-to-noise ratio (SNR) compared to conventional processing algorithms and it also provides a novel way of representing detected defects identifying the area affected by the lateral thermal diffusion effect.

DNA Oligonucleotide-Functionalized Liposomes: Bioconjugate Chemistry, Biointerfaces, and Applications.

Interfacing DNA with liposomes has produced a diverse range of programmable soft materials, devices, and drug delivery vehicles. By simply controlling liposomal composition, bilayer fluidity, lipid domain formation, and surface charge can be systematically varied. Recent development in DNA research has produced not only sophisticated nanostructures but also new functions including ligand binding and catalysis. For noncationic liposomes, a DNA is typically covalently linked to a hydrophobic or lipid moiety that can be inserted into lipid membranes. In this article, we discuss fundamental biointerfaces formed between DNA and noncationic liposomes. The methods to prepare such conjugates and the interactions at the membrane interfaces are also discussed. The effect of DNA lateral diffusion on fluid bilayer membranes and the effect of membrane on DNA assembly are emphasized. DNA hybridization can be programmed to promote fusion of lipid membranes. Representative applications of this conjugate for drug delivery, biosensor development, and directed assembly of materials are briefly described toward the end. Some future research directions are also proposed to further understand this biointerface.

Effect of Lateral Diffusion on Hydrogen Permeation Measurement in Thick Steel Specimens

Effect of Lateral Diffusion on Hydrogen Permeation Measurement in Thick Steel Specimens

Recovery of acetylcholine-induced currents after paired-pulse stimulation in snail neurons: Analysis using a mathematical model

The experimental relationship between the paired-pulse ratio of acetylcholine-induced inward currents in the command neurons of Helix lucorum and the interval between application of a neurotransmitter was analyzed using the method of paired-pulse stimulation. A mathematical model that takes the membrane and intracellular localization of receptors, their lateral diffusion, and endocytosis and exocytosis depending on the intracellular processes into account was used to study this dependence. Our results have shown that membrane receptor endocytosis is the main process that determines the type of this relationship. The effects of exocytosis and lateral diffusion of membrane receptors on this relationship were studied. The parameters of an existing mathematical model were further clarified.

Numerical evaluation of lateral diffusion inside diffusive gradients in thin films samplers.

Using numerical simulation of diffusion inside diffusive gradients in thin films (DGT) samplers, we show that the effect of lateral diffusion inside the sampler on the solute flux into the sampler is a nonlinear function of the diffusion layer thickness and the physical sampling window size. In contrast, earlier work concluded that this effect was constant irrespective of parameters of the sampler geometry. The flux increase caused by lateral diffusion inside the sampler was determined to be ∼8.8% for standard samplers, which is considerably lower than the previous estimate of ∼20%. Lateral diffusion is also propagated to the diffusive boundary layer (DBL), where it leads to a slightly stronger decrease in the mass uptake than suggested by the common 1D diffusion model that is applied for evaluating DGT results. We introduce a simple correction procedure for lateral diffusion and demonstrate how the effect of lateral diffusion on diffusion in the DBL can be accounted for. These corrections often result in better estimates of the DBL thickness (δ) and the DGT-measured concentration than earlier approaches and will contribute to more accurate concentration measurements in solute monitoring in waters.

Integrated CMOS Optical Sensor for Light Spectral Analysis

In this paper, a fully integrated photo sensor in standard CMOS technology is reported, which enables light spectral analysis in the visible light range without additional optical components like color filters or gratings. The proposed sensor structure provides a continuously tunable spectral responsivity based on lateral carrier diffusion effects in combination with tunable field electrodes for defined carrier redirection. The tunable responsivity characteristics in combination with digital signal processing can be deployed for light spectral analysis like color measurements or full light spectral reconstruction. The realization of an accurate photometric color measurement based on the CIE X, Y, Z or R, G, B standard will be presented as an example for a basic light spectral analysis. Furthermore, the sensor application in a basic spectrophotometer is presented, providing a unique opportunity to realize a highly integrated low-cost spectrophotometer for basic spectral light measurements using a low-cost standard CMOS technology without process modification.

Lateral drug diffusion in human nails.

The main objective of the current work is to demonstrate the process of passive lateral diffusion in the human nail plate and its effect on the passive transungual permeation of antifungal drug ciclopirox olamine (CPO). A water soluble dye, methyl red sodium salt (MR) was used to visualize the process of lateral diffusion using a novel suspended nail experiment. The decline in concentration of CPO correlates with that of concentration of MR from the proximal to the distal end of the nail in suspended nail study. Three toenails each were trimmed to 5 mm × 5 mm (25 mm(2)), 7 mm × 7 mm (49 mm(2)), and 9 mm × 9 mm (81 mm(2)) to study the extent and effect of lateral diffusion of the CPO on its in vitro transungual permeation. The permeation flux of CPO decreased as the surface area of the toenail increased. There was a positive correlation between the concentrations of CPO and MR in the area of application and in the peripheral area of the toenails of the three surface areas, confirming the findings in the suspended nail experiment. Profound lateral diffusion of CPO was demonstrated and shown to reduce the in vitro passive transungual drug permeation and prolong the lag-time in human toenails. The study data implies that during passive in vitro transungual permeation experiments, the peripheral nail around the area of drug application has to be kept to a minimum, in order to get reliable data which mimics the in vivo situation.

Improved Magnetic Sensitivity of CMOS Vertical Hall Device by Using Partial Implantation Technique

With the continuous scaling of CMOS technology, the doping level of N-well is constantly increasing, which leads to a big decrease in magnetic sensitivity for vertical Hall devices (VHDs). Moreover, the Gaussian profile of doping concentration gives an additional decrease in N-well effective depth, which further reduces the magnetic sensitivity. In this paper, we apply partial N-well and top p+ layer implantation techniques to lower the doping level of N-well and improve the doping profile by means of impurity lateral diffusion and compensation effects. TCAD process and device simulations have been carried out for a typical five-contact VHD in 0.13 μm CMOS technology. Simulation results show that the current-related magnetic sensitivity is greatly improved from 40 V/AT to 110 V/AT by using the partial implantation techniques. Meanwhile, the voltage-related magnetic sensitivity is also increased and not significantly decreased.

A Compact Behavioral Simulation Model for CMOS Vertical Hall-Effect Devices

A compact behavioral simulation model for CMOS five-contact vertical Hall devices is presented. In term of the internal current flow geometry, the vertical Hall device is modeled based on an asymmetric Wheatstone bridge structure, including four current-controlled Hall voltage sources and four asymmetric lumped resistors. The lumped resistors on the Wheatstone bridge are calculated preliminarily by conformal mapping method. More importantly, the model takes into account the lateral diffusion effect and junction field effect which further improves the simulation accuracy. The behavioral model has been written in Verilog-A language with ten more physical and process parameters. The behavioral model simulation has been successfully performed in the Cadence Spectre environment with 0.8 μm high voltage CMOS technology parameters. The model’s simulation results are in good agreement with the reported experimental results.

Lateral carrier diffusion and current gain in terahertz InGaAs/InP double-heterojunction bipolar transistors

The DC current gain in In0.53Ga0.47As/InP double-heterojunction bipolar transistors is computed based on a drift-diffusion model, and is compared with experimental data. Even in the absence of other scaling effects, lateral diffusion of electrons to the base Ohmic contacts causes a rapid reduction in DC current gain as the emitter junction width and emitter-base contact spacing are reduced. The simulation and experimental data are compared in order to examine the effect of carrier lateral diffusion on current gain. The impact on current gain due to device scaling and approaches to increase current gain are discussed.

Modulating the field-effect passivation at the SiO2/c-Si interface: Analysis and verification of the photoluminescence imaging under applied bias method

In this paper, we study the surface passivation properties of thermally oxidized silicon wafers with controlled surface band bending, using a recently developed characterization technique combining calibrated photoluminescence imaging with the application of an external voltage over the rear side passivation layer. Various aspects of the technique and possible errors in the determination of the effective surface recombination velocity are discussed, including lateral carrier diffusion, leakage currents, and optical effects related to the presence of metal electrodes on the investigated samples. In order to quantitatively describe the recombination activity at the SiO2/c-Si interface and the effect of fixed charges in the oxide layer, the measured effective carrier lifetime vs. voltage curves have been analyzed in the framework of an extended Shockley-Read Hall recombination model. Furthermore, the results have been compared with corresponding results from microwave detected photoconductance decay measurements after depositing corona charges. We find an excellent agreement between the two techniques and between complementary measurements of the oxide charge density. Photoluminescence imaging under applied bias gives fast and repeatable measurements and allows for simultaneous data collection from multiple areas on the sample, and has thus been proven to be powerful tool for quantitative characterization of surface passivation layers.

Physics-based simulation of the modulation transfer function in HgCdTe infrared detector arrays

We have developed a numerical technique for performing physics-based simulations of the modulation transfer function (MTF) of infrared detector focal plane arrays. The finite-difference time-domain and finite element methods are employed to determine the electromagnetic and electrical response, respectively. We show how the total MTF can be decomposed to analyze the effect of lateral diffusion of charge carriers and present several methods for mitigation of such effects. We employ our numerical technique to analyze the MTF of a HgCdTe two-color bias-selectable infrared detector array.

Two dimensional mass transfer in flat layers and lateral diffusion effect in permeability determination

For investigation of diffusion, such experimental setup geometry arrangement is preferred, where as soon as possible homogeneous concentration field takes place in flat material samples. However, lateral mass transfer may play significant role. Here, this effect was solved for twodimensional diffusion through a layer of finite thickness to a circular target with an insulating ring. Simple formula has been suggested fitting the numerical results in a wide range of variables including asymptotic cases as well. The formula is suitable for determination of permeability using data received by electrodiffusion measurement under the conditions of limiting diffusion current to a circular electrode with a guard ring.