Multiplication Layer Thickness Research Articles

Deep-learning measurement of intracerebral haemorrhage with mixed precision training: a coarse-to-fine study

To develop a unified deep-learning-based method for automated intracerebral haemorrhage (ICH) segmentation on computed tomography (CT) images with different layer thickness parameters. A total of 134 patients from an internal database (67 patients) and an external database (called CQ500, 67 patients) were employed. The CT examinations included multiple layer thicknesses such as 0.625, 1.25 and 5 mm. ICH segmentation was performed by a coarse-to-fine strategy, including three stages of three-dimensional (3D) skull-stripping segmentation, 3D ICH localisation segmentation, and two-dimensional (2D) ICH fine segmentation. The three stages shared the same sICHNet for segmentation and employed mixed precision training to speed up the training process. In addition, the 3D contextual information from CT was maintained by formatting the consecutive slices into a three-channel image in the 2D ICH fine segmentation. Experimental results demonstrated that the coarse-to-fine segmentation strategy achieved the best performance with a mean Dice coefficient of 0.887. ICH volume consistency was observed (p<0.05) between manual and automatic segmentations, and between segmentations of same individual but with different layer thicknesses in internal dataset and external database. Automated segmentation achieved a relatively consistent segmentation time of 20.01±2.03 seconds no matter the layer thickness of the CT images and the extent of ICH. Longitudinal studies with conservative management and surgical treatment were also visualised. The coarse-to-fine deep learning strategy achieved the best ICH segmentation performance on CT images. The automated segmentation was 5-42 times faster than manual segmentation given ICH of different extents and using different layer thickness parameters.

Antibacterial intraosseous implant surface coating that responds to changes in the bacterial microenvironment.

Bone implant-associated infection is one of the most challenging problems encountered by orthopedic surgeons. There is considerable interest in the development of drug-loaded antibacterial coatings for the surfaces of metal implants. However, it is difficult to achieve the stable local release of an effective drug dose for many antibacterial coatings. In the present study, analyses of the thickness and water contact angle of multiple layers confirmed the successful assembly of multilamellar membrane structures. Measurement of the zone of bacterial inhibition indicated gradual degradation of the (montmorillonite [MMT]/hyaluronic acid [HA])10 multilamellar film structure with concentration-dependent degradation during incubation with hyaluronidase solution and Staphylococcus aureus. In vivo results resembled the in vitro results. Overall, the findings confirm that the (MMT/HA-rifampicin)10 multilamellar film structure exhibits good antibacterial properties and excellent biocompatibility. Further studies of the clinical potential of the antibacterial coating prepared in this experiment are warranted.

Numerical Model of an Enzymatic Glucose Sensor with a Blocking Layer on the Electrode

Glucose oxidase-based biosensors are a primary method for continuous glucose monitoring. b-glucose reacts with immobilized glucose oxidase to form gluconic acid and hydrogen peroxide. Hydrogen peroxide is oxidized on an adjacent electrode. The resulting anodic current is proportional to the concentration of glucose. The measured current may be influenced by oxidation of secondary species, such as ascorbic acid and acetaminophen, or fouling of the sensor via foreign body response.[1-3] A blocking layer, placed between the electrode and the immobilized enzyme layer, may act to prevent diffusion of secondary species to the electrode, and reduce the influence of the foreign body response.[3]The influence of a blocking layer on the steady and transient operation of the sensor was evaluated numerically. A blocking layer was added to the steady and transient glucose sensor model outlined in previous work [4] to address the potential influence of acetaminophen. Sensor performance was evaluated for multiple blocking layer thicknesses, reacting species diffusion coefficients, and oxygen concentration. The polarization behavior of the sensor was modeled. Selectivity to glucose was improved by addition of a blocking layer, but sensitivity to oxygen was increased with increasing blocking layer thickness.Numerical simulations of the transient response to a step change in glucose for a sensor with the blocking layer had a response time comparable to the response without the blocking layer, except when the hydrogen peroxide diffusion was greatly reduced in the blocking layer. A step change in acetaminophen yielded time constants comparable to that of the glucose step change in the absence of a blocking layer. The results are sensitive to the thickness of the blocking layer and to the diffusivity of the interfering species in the blocking layer.References Basu, A., & Veettil, S. (2016). Direct Evidence of Acetaminophen Interference with Subcutaneous Glucose Sensing in Humans: A Pilot Study. Diabetes Technology & Therapeutics, 18(S2), 43-47.Surani, S., & Sharma, M. (2021). Interaction between vitamin C and point of care glucose monitoring. Are we overly wary of it or is it a valid concern? Current Medical Research and Opinion, 37(7), 1111-1113.Yang, Y., Zhang, S., & Kingston, M. (2000). Glucose sensor with improved haemocompatibility. Biosensors and Bioelectronics, 15, 221-227.Jacobs and M. E. Orazem, ``Transient Response of a Continuous Glucose Monitor," presented at the 240th Meeting of the Electrochemical Society, Orlando, Florida, October 10-14, 2021. AcknowledgementThe support of Medtronic Diabetes (Northridge, CA) is gratefully acknowledged.

On the use of multiple layer thicknesses within laser powder bed fusion and the effect on mechanical properties

Laser Powder Bed fusion is capable of rapid production of parts, from conception, compared with traditional manufacturing methods. This said, the time taken to fabricate a single part can still be significant – typically many hours. Processing thicker layers, and hence fewer total layers, in the Laser Powder Bed Fusion process, is an effective way to reduce build times. However, mechanical performance can suffer as a result of this strategy. This study proposes and demonstrates a method to enable the interlacing of multiple layer thicknesses within one part, allowing for finer layers within regions where they are specifically required, whilst maintaining overall component integrity for specific load cases. Thicker layers are used within regions with lower property requirements in order to optimise an overall part for improved production rate. The design of interfaces between two disparate layer thickness regions could also be tailored for control of material properties and such will be investigated in an independent study. Ti6Al4V LPBF samples are fabricated, characterised by way of tensile testing, porosity analysis and microstructural analysis. The study demonstrate parts can be additively built using multiple layer thickness regions with consistent ultimate tensile strength (1110–1135 MPa) and varying penalties to ductility, depending on layer thickness and interface design (elongation to failure reductions up to 40% in the most extreme case).

A Micro-Computed Tomography Comparison of the Porosity in Additively Fabricated CuCr1 Alloy Parts Using Virgin and Surface-Modified Powders.

Recently, the use of novel CuCr1 surface-modified powder for reliable laser powder-bed fusion (LPBF) manufacturing has been proposed, enabling a broader LPBF processing window and longer powder storage life. Nevertheless, virgin CuCr1 powder is also LPBF processable, on the condition that a high-energy density is employed. In this work, we compare two dense specimens produced from virgin and surface-modified CuCr1 powder. Furthermore, a third sample fabricated from surface-modified powder is characterized to understand an abnormal porosity content initially detected through Archimedes testing. Utilizing high-resolution micro-CT scans, the nature of the defects present in the different samples is revealed. Pores are analyzed in terms of size, morphology and spatial distribution. The micro-CT data reveal that the virgin CuCr1 dense specimen displays keyhole pores plus pit cavities spanning multiple layer thicknesses. On the other hand, the sample fabricated with the surface-modified CuCr1 powder mainly contains small and spherical equi-distributed metallurgical defects. Finally, the CT analysis of the third specimen reveals the presence of a W contamination, favoring lack-of-fusion pores between subsequent LPBF layers. The LPBF melting mode (keyhole or conductive), the properties of the material, and the potential presence of contaminants are connected to the different porosity types and discussed.

Influence of optical parameters on a solar sail motion

Detailed dynamic modeling of a solar sail requires recording of solar radiation pressure influence. A photon-solar sail is determined by the thrust value and the direction. We define the solar sail’s reflectivity depending on the film materials, the sail design and temperature, the thickness of multiple layers, and degradation factor, with a reasonable degree of accuracy. Thus, this work is devoted to the identification of optical characteristics of thin multilayer films in space flight conditions, i.e. to finding its reflectance, absorbance, and transmittance. In particular, the paper asks whether the solar sail simulates by a mathematical model of the optical characteristics of a multilayer epitaxial thin film. The temperature change effect and optical properties of solar sail degradation are considered as well. Solar sail flight from Earth to Mercury is designed as a simulation of the flight change in optical parameters.

Performance Modulation for Back-Illuminated AlGaN Ultraviolet Avalanche Photodiodes Based on Multiplication Scaling

Back-illuminated Al0.1Ga0.9N ultraviolet avalanche photodiodes (APDs) of various multiplication widths were fabricated on AlN templates with a separate absorption and multiplication structure. The impacts of an increased multiplication scale on a device performance were investigated. The avalanche breakdown voltage was found to increase as the multiplication layer thickness (MLT) increases. The APD with 230-nm-MLT achieved a superior maximum multiplication gain of 5.4 × 10 4 , higher than that obtained in devices with 150-nm- and 300-nm-MLT. Theoretical simulations demonstrated that the critical electric field intensity in an avalanche region would decrease as the rising of MLT, indicating the modulating ability of multiplication scaling on the AlGaN APD performance. In addition, APDs fabricated on different AlN templates were employed to study the effects of crystalline quality on device properties.

Highly chromatic retardation via multi-twist liquid crystal films

Here we study birefringent films with highly customizable chromatic retardation spectra, using multi-twist liquid crystal (LC) films. These are made of two or more layers of chiral nematic LC polymer network materials, also known as reactive mesogens, which form a monolithic thin-film wherein the in-plane orientation of subsequent layers is automatically determined by the single alignment layer on the substrate. The multiple layer thicknesses and twists present many degrees of freedom to tailor the retardation. While prior work examined achromatic spectra, here we show how to use Mueller matrix analysis to create highly chromatic spectra. We experimentally demonstrate both a uniformly aligned retarder as a green/magenta color filter and a “hot” polarization grating (PG) that diffracts infrared while passing visible light. The three-twist color filter shows a contrast ratio in transmittance between polarizers as high as 10:1 between the half- and zero-wave retardation bands. The “hot” PG shows an average first-order efficiency of about 90% for 1000–2700 nm and an average zero-order efficiency of about 90% for 500–900 nm. The principles here can be extended to nearly any chromatic retardation spectra, including high/low/bandpass, and to nearly any LC orientation pattern, in general known as geometric-phase holograms.

A method to improve the stability of the optical interference system

The measurement system based on optical interference has obvious advantages of high precision and high sensitivity. However, the signal is easy to be disturbed by vibration from environment, so the system needs to stay away from the vibration source. To use the optical interference method for real-time measurement, it has to im-prove the system’s stability. In this paper, we proposed an integrated Michelson interference device to measure the thicknesses of multiple layers of optical plate, which could improve the stability of the optical interference system in a new way. Through smart design and high precision processing technique, the light path of the structure was integrated into a whole, which could avoid disturbing successfully. Compared with fiber based interferometer, this device could bring obviously more stable signal. The thicknesses of the multiple layers of optical plate were measured to confirm its feasibility to do the real-time precision measurement.

Experimental Evaluation of the Average Energy for Impact Ionization by Holes in Al0.4Ga 0.6N Alloy

An experimental approach to evaluate the average energy required by holes for impact ionization in Al0.4 Ga0.6N alloys is presented. A series of back-illuminated separate absorption and multiplication structures with different thickness of multiplication layer are employed. With the measured quantum efficiency of devices and a consideration of energy conservation in ionization process, the average energy for electron-hole pair production by energetic holes is obtained and it qualitatively agrees with the bond energy of Al0.4Ga0.6N, which is estimated from the Vegard's law.

Producing parts with multiple layer thicknesses by projection stereolithography

Producing parts with multiple layer thicknesses by projection stereolithography

Producing parts with multiple layer thicknesses by projection stereolithography

We present a novel method to increase the manufacturing speed and versatility in lithography-based additive manufacturing processes. Usually, a part made with additive manufacturing consists of equally thick layers that are fabricated upon one another. We use a projection stereolithography (PSL) system to manufacture parts containing several layer thicknesses, which reduces the manufacturing time and adds controllability to the system. The method is based on the possibility to control the cure depth by adjusting the operation wavelength. To demonstrate the applicability of the PSL system for this purpose, we used two different operation wavelengths to produce parts that include 50- and 300-µm layers. The method presented in this paper can be used in several PSL techniques to increase their performance by offering a new tool to control the layer thickness without affecting the manufacturing resolution.

Design considerations of high-performance InGaAs/InP single-photon avalanche diodes for quantum key distribution.

InGaAs/InP single-photon avalanche diodes (SPADs) are widely used in practical applications requiring near-infrared photon counting such as quantum key distribution (QKD). Photon detection efficiency and dark count rate are the intrinsic parameters of InGaAs/InP SPADs, due to the fact that their performances cannot be improved using different quenching electronics given the same operation conditions. After modeling these parameters and developing a simulation platform for InGaAs/InP SPADs, we investigate the semiconductor structure design and optimization. The parameters of photon detection efficiency and dark count rate highly depend on the variables of absorption layer thickness, multiplication layer thickness, excess bias voltage, and temperature. By evaluating the decoy-state QKD performance, the variables for SPAD design and operation can be globally optimized. Such optimization from the perspective of specific applications can provide an effective approach to design high-performance InGaAs/InP SPADs.

Finite Element Analysis of Cricket Ball Impact on Polycarbonate-EVA Sandwich

In cricket, balls are delivered at speeds ranging from 25 to 45 m/s. The force generated upon impact at such high speeds can be detrimental to batsmen's safety. There are several existing equipment that protect batsmen from injury and it is vital to evaluate their effectiveness for use in this sport. Finite Element Methods have come to be an exceptionally reliable tool in the design process of such protective gear as they provide deep insight into the impact phenomenon. With rigorous experimental testing, mathematical models for both the impacting projectile and the protective equipment can be developed and used to simulate the impact scenario under varied circumstances. This paper investigates the strength of a Polycarbonate-foam sandwich against impact by a cricket ball using Finite Element Analysis. The foam sandwiched is Ethylene-Vinyl Acetate, which possesses good impact absorbing characteristics and generally finds application in mouth-guards for sports and recreational activities. The Polycarbonate plate provides tear resistance. The cricket ball was modelled as a viscoelastic material, validated with experimental data available in literature. Additionally, the skin, connective adipose tissue and muscle layers of the human body are also modelled. Simulations with multiple velocities of impact, multiple angles of impact and multiple layer thicknesses of protective system were carried out. Impact force transmitted to the skin and the specific energy absorption of the foam sandwich was determined. The consecutive layers of the protective equipment and the human tissues were modelled together as square plates. The best combination of material thicknesses of the protective material was determined based on the least contact force transmitted to the human skin upon impact.

Instrumentation to Measure Soil Subsidence and Water Content in a Single Borehole

Errors associated with current methods for measuring in situ vertical soil shrinkage related to water loss are associated with measurements being spatially disconnected, which introduces unknown spatial variability and excessive soil disturbance during installation. To minimize these errors, a method was developed to measure changes in thicknesses of multiple soil layers in a single borehole. Soil layer thickness was measured by tracking the location of magnets in the sidewall of the borehole using a probe with a magnetic field sensor. The sensor was capable of submillimeter repeatability for measurements of soil layer thickness. Soil water content was measured with a neutron moisture meter in the same borehole. Measurements made on two soils showed that, compared with spatially separated measures, the single borehole method improved the observed relationship between soil shrink-swell and water content change, increasing r2 from 0.73 to 0.90.

Modified Waveguide Flange for Evaluation of Stratified Composites

Nondestructive evaluation of stratified (layered) composite structures at microwave and millimeter-wave frequencies is of great interest in many applications where simultaneous determination of the complex dielectric properties and thicknesses of multiple layers is desired. Open-ended rectangular waveguide probes, radiating into such structures, are effective tools for this purpose. The technique utilizes a full-wave electromagnetic model that accurately models the complex reflection coefficient as a function of frequency and material properties. While the electromagnetic model assumes an infinite waveguide flange (or ground plane), the measurements are conducted using a finite-sized flange. Consequently, the results of the electromagnetic model and those from measurements may not be sufficiently alike for accurate dielectric property and thickness evaluation. This paper investigates the effect of using an open-ended waveguide with a standard finite-sized flange on the error in evaluating the complex dielectric properties of a composite structure. Additionally, we present the design of a novel flange that markedly reduces this undesired effect by producing very similar electric field properties, at the flange aperture, to those created by an infinite flange. Finally, the efficacy of the design for evaluating the dielectric properties of a layered composite structure is demonstrated as well.

Comparison of waveguide avalanche photodiodes with InP and InAlAs multiplication layer for 25 Gb/s operation

2.5 and 10 Gb/s InP/InGaAs avalanche photodiodes (APDs) have been widely used in optical communication systems. However, the study on InP/InGaAs APDs above 10 Gb/s is insufficient. Recently, high-speed and high-sensitivity APDs for 100 Gb/s or even 400 Gb/s optical communication systems have drawn a lot of attention. On basis of the physical model for frequency response of APD including the dead space effect, a waveguide separate absorption, grading, charge, and multiplication (WG-SAGCM) InP/InGaAs APD has been designed for 25 Gb/s operation. Also, the frequency response of WG InAlAs/InGaAs APD was also simulated, which is perfectly in accordance with the experimental data. The comparison between InP/InGaAs APD and InAlAs/InGaAs APD with the same thickness of multiplication layer shows that the speeds of carriers in the nonionization layers are also important for the gain-bandwidth characteristics of SAGCM WG-APD. The higher drift velocity of carriers returned from multiplication layer and the lower drift velocity of carriers injected into multiplication layer result in a higher gain-bandwidth product and a higher dc gain. This work is helpful for the design of high-speed APDs.

Note: Accurate determination of thickness of multiple layers of thin film deposited on a piezoelectric quartz crystal

Modern day piezoelectric quartz crystal microbalances for thin film deposition control are based on Z-match equation, which is mathematically valid for deposition of a single material on a given quartz crystal. When multiple layers are deposited, thickness and deposition rate errors accumulate due to mismatch of acoustic impedance of different materials. Here we present a novel method, based on the acoustic transfer matrix formalism, for accurate determination of thickness of an arbitrary number of layers of dissimilar materials deposited on a quartz crystal. Laboratory data show excellent accuracy of the method compared to conventional Z-match equation.

Electrical modeling of InSb PiN photodiode for avalanche operation

Current density-voltage (J-V) characteristics at 77 K of InSb pin photodiodes, in dark condition and under illumination, were simulated in view to design an avalanche photodiode (APD). Theoretical J-V results were compared with experimental results, performed on InSb diode fabricated by molecular beam epitaxy, in order to validate the parameter values used for the modeling. Then, with the assumption of multiplication induced by the electrons, an optimized separate absorption and multiplication APD structure was defined by theoretically studying the absorber doping level and the multiplication layer thickness. Calculated gain value higher than 10 was achieved at V = −4.5 V. This result shows the potentiality of InSb material as APD device.

InGaAs–InP avalanche photodiodes with dark current limited by generation-recombination

Separate absorption grading charge multiplication avalanche photodiodes (SAGCM APDs) are widely accepted in photon starved optical communication systems due to the presence of large photocurrent gain. In this work, we present a detailed analysis of dark currents of planar-type SAGCM InGaAs-InP APDs with different thicknesses of multiplication layer. The effect of the diffusion process, the generation-recombination process, the tunneling process and the multiplication process on the total leakage current is discussed. A new empirical formula has been established to predict the optimal multiplication layer thickness of SAGCM APDs with dark current limited by generation-recombination at multiplication gain of 8.