Bottom Width Research Articles

Analysis of transient signal broadening of silicon-based photodiodes irradiated by nanosecond laser

To investigate the saturation characteristics of silicon-based optoelectronic devices caused by short-pulse laser irradiation, an Nd:YAG laser with a wavelength of 1064 nm and two typical silicon-based photodiodes, PN and PIN, were employed to build an experimental system to measure the transient response signal of the device. The change. The experimental results demonstrate that with the increase of laser energy density, the nonlinear saturation of the two devices occurs, and the response time is significantly increased. This is a response degradation phenomenon for the response of the device and the signal after the saturation of the two devices. By analyzing the rising edge, half-height width, and bottom width of the characteristic quantity, it can be found that the broadening of the two devices is mainly due to the broadening of the falling edge of the response signal. However, the broadening of the PIN-type photodiode after laser irradiation is compared with that of PN. Type photodiodes remain more remarkable. Through the analysis of carrier dynamics, when the signal is restored, the movement of carriers is affected by a large number of photogenerated carriers after the laser irradiation ends, affecting the drift movement and space charge region during the bipolar transport of carriers. The width of the two devices attenuates the speed when the signals of the two devices are restored, leading to the saturation caused by the laser irradiation of the two devices

Hazard Prediction Method of Landslide Damming and Analysis of a Typical Application

Landslide damming occurs frequently, affects a wide range of areas, and is difficult to predict, thus threatening the safety of human life, properties, and engineering structures. However, the studies on early identification remain at an early stage. This paper proposes a hazard prediction method for landslide damming, which includes prediction models of river blockage, landslide dam geometry, landslide dam stability, and dam breach time. On this basis, the landslide damming hazard can be predicted via ten parameters: the repose angle of the landslide mass, the landslide volume, the landslide discharge, the river discharge, the reservoir capacity of the barrier lake, the bottom width of the valley, two slope angles on both sides of the valley, the valley bed inclination, and the sliding surface dip-angle. The proposed method was examined in relation to a typical case, namely, the Baige landslide damming that occurred in 2018 in China, with the application process presented integrally. The results indicated that the river blockage model predicted that the Baige landslide could form a huge landslide dam, which was fully in line with the actual situation. The landslide dam geometry model provided the predicted value of the height, width, and length, as well as the downstream and upstream angles, of the Baige landslide dam, with the maximum relative error between the predicted values and the true values less than 20%. The prediction results of the landslide dam stability model indicated that when the reservoir capacity of the barrier lake is 280 million m3, the dam could breach. In fact, the dam breach time model predicted that the dam could breach within 38 h after the landslide dam formation, which was 11% less than the actual breach time of the Baige landslide dam. The current study provides a useful theoretical reference and technical support for the early identification, prediction, and warning of the disaster chain of landslide-induced river blocking.

PERENCANAAN ULANG SISTEM DRAINASE DAN IPAL DI JALAN SIMPANG BANDULAN BARAT - JALAN BRIGJEND KATAMSO KOTA MALANG

On West Bandulan Junction Street - Brigjend Katamso Street, Malang City often experiences inundation during the rainy season. The occurrence of flooding is caused by the capacity of the drainage channel which is not sufficient to accommodate the discharge of runoff, improper drainage planning garbage in the drainage channel, the amount of waste from households and industry and the large number of closed drainage channels because it is made for parking and community home yards . From this condition, the drainage re-design is carried out. This plan is made to re-design the dimensions of the drainage channels and calculate the WWTP (Wastewater Treatment Plant) requirements, as well as calculate the RAB. The results of the calculation of the planned channel dimensions are trapezoidal and square with the largest dimensions of the trapezoid having a width of 1.19 m, a bottom width of 0.8 m and a height of 1.09 m. while the largest dimension of a square has a width of 1.4 m and a height of 1.4 m. The results of the calculation of the need for WWTP require 4 WWTP with different capacities, namely IPAL 1 with a capacity of 4 m3, IPAL 2 with a capacity of 12 m3, IPAL 3 with a capacity of 3 m3, IPAL 2 with a capacity of 2 m3. Based on the results of the calculation of drainage redesign, it can be concluded that the cost of redesign the drainage and WWTP is Rp. 6,473,335,422.

Designing the hydrocyclone with flat bottom structure for weakening bypass effect

As a principal reason for the deterioration of separation accuracy, the bypass effect in hydrocyclones has received widely concerned. This paper presents a numerical study about the effect of flat bottom structure width on the bypass effect with the respect of flow field characteristics, separation efficiency, and particle spatial distribution with a verified TFM model. Numerical results demonstrate that wide flat bottom structure increases the cut size and reduces the fine particles misplaced in the underflow. However, the excessive flat bottom structure width increases coarse particles misplaced in the overflow causing by the superior turbulence intensity and the entrapment of the internal swirling flow. A wide flat bottom structure width reduces the turbulence dissipation rate, while the split ratio first decreases and then increases, indicating that the bypass effect is controlled by the turbulence dissipation and does not comply with the trend of the split ratio.

Visualization and simulation of 1700MS sheet laser welding based on three-dimensional geometries of weld pool and keyhole

Laser butt welding experiments assisted with high speed imaging were conducted to isochronously observe the keyhole and weld pool in this study. The time-averaged characteristics of the keyhole and weld pool geometries were extracted by image processing. The characteristics contained the upper width, bottom width and upper length of the weld pool, and the diameter and inclining angle of the keyhole. The effect of welding speed on the characteristics was investigated and the results showed the increased welding speed gave rise to a decrease in the keyhole diameter and the weld pool widths, while the weld pool upper length firstly decreased from 5.795 mm to 4.308 mm until the speed was 4.2 m/min, and then increased to 4.941 mm when the speed was 6.9 m/min. Based on the measured time-averaged characteristics, a double cylindrical heat source model considering the keyhole angle and diameter was derived to predict the weld size. Thermal analysis based on the heat source model was performed and the prediction results were validated using the time-averaged characteristics and the single weld cross section sizes respectively. The results showed the model had good simulation accuracy (7.20%–12.48%) for sub-millimeter weld cross section and had good adaptability of multi-process parameters. The max difference in the errors of the two validations was 3.92%, indicating the thermal analysis validating with the time-averaged results had higher accuracy.

Pulsed Discharge Characteristics of a Semicombustible Plasma Generator for ETC Launchers

A semicombustible plasma generator (SCPG), including a special tubular semicombustible medium, is introduced to improve the discharge property of the plasma generator and enhance the electrothermal–chemical (ETC) launch efficiency. The new structure of SCPG is mixed with both capillary plasma generator (CPG) and discharge rod plasma generator (DRPG). After the design and simulation, the electrical characteristics of this SCPG are discussed with both static test and dynamic tests. Results show that the SCPG is a resistive load with low inductance, which has stable and consistent electrical parameters. With the increase of discharge voltage, the peak current of SCPG is increased and the equivalent resistance of SCPG is decreased. The peak voltage is nearly 1.3 kV and the pulse current bottom width is more than 3.5 ms. Compared with the DRPG, the load characteristics of SCPG are in a stable and consistent trend during the pulsed discharge process as the same as DRPG. Also, the SCPG has longer stable working times and better stable working parameters and performance. This SCPG will promote the interaction between the plasma and propellants in the chamber.

Improving performance of light-emitting diodes using InGaN/GaN MQWs with varying trapezoidal bottom well width

We report the optical performance of four InGaN/GaN multiple quantum well (MQW) blue LEDs with different bottom base widths- LED A. InGaN/GaN rectangular shaped quantum wells (QWs) with well width of 2 nm, LED B. InGaN graded QWs with trapezoidal bottom base width of 0.8 nm, LED C. trapezoidal QWs with bottom base width of 0.6-nm, and LED D. trapezoidal QWs with bottom base width of 0.5 nm- in terms of optical output power and efficiency droop. The introduction of trapezoidal QW facilitates to decrease the piezoelectric polarization field in the well of InGaN/GaN based LED structure. Such structures not only increase overlapping between electron and hole wave functions, but cause uniform carrier distribution among all quantum wells thereby increasing the radiative recombination rate. The proposed LED C shows the best performance in terms of lowest efficiency droop of 4.7% and highest optical power output of 226 mW as compared to the efficiency droop of 48.8% and output power of 70 mW at input current of 120 mA obtained from the conventional LED structure, LED A.

Optimization design of cylindrical rivet in flat bottom riveting

Light weight material is used more and more extensively in automotive industry due to its high mechanical properties and low density. The joining of light weight material, such as mechanical clinching, is attracting much attention. The application of mechanical clinching is greatly restricted because of the protrusion produced on lower side of sheet. A new joining method, flat bottom riveting, is presented in this paper. Lower surface of riveted joint is flat and smooth, with no protrusion formed. Simulation was conducted to optimize geometrical parameters of rivet. Proper rivet length and rivet diameter were obtained. There is a circular groove on lower edge of rivet. Geometrical parameters of groove, such as groove inner diameter, groove length, groove height, groove bottom width and fillet radius have great influence on tensile load of joint. Finite element simulation and orthogonal test were carried out, and groove inner diameter was found to be the most important factor that affects joint tensile load. The results of simulation and experimental tests had high consistency, indicating that conclusion drawn was convincible.

Diffusion-controlled growth of Cu thin films electrodeposited directly on atomic-layer-deposited WC diffusion barrier for Cu interconnect

Direct copper (Cu) electrodeposition on a 10-nm atomic-layer-deposited (ALD) tungsten carbide (WC) diffusion barrier layer was investigated for building Cu interconnect in silicon (Si)-based microelectronic devices. The diffusion of Cu reducing species under potentiostatic Cu deposition was characterized according to applied cathodic potential in a neutral electrolyte with a concentration ratio of 1:10 for Cu to iminodiacetic acid (IDA) as a complexing agent. The diffusion-controlled nucleation and growth of Cu thin film on the ALD WC was figured out in relation to diffusion coefficients of Cu reducing species that were calculated from both modified current transient curves and more appropriately electrochemical impedance spectroscopy (EIS) analysis. At the end, the diffusion-controlled Cu fill of trenches with an aspect ratio of 6.3 and 15-nm bottom width was conducted by applying −1.4 V vs Ag/AgCl to an ALD-WC-covered, patterned Si wafer specimen.

Modeling and optimization of weld bead profile with varied welding stages for weathering steel A606

The profile of the welding bead changes with the welding process parameters during the gas metal arc welding (GMAW) process, the top reinforcement disappears, and the penetration becomes sunken when the excessive welding heat input is applied. However, little research work is specially planned to cope with the studying of welding bead under these circumstances. A systematic study of the relationships among the welding process variables and welding bead geometric features as well as optimization of the welding quality is presented. The influences of the welding technological parameters (voltage, welding speed, and wire feed speed) on the welding geometry were revealed, and the models correlating them were established. The features of the weld bead geometry were composed of top reinforcement width, top reinforcement height, penetration depth, bottom reinforcement width, and bottom reinforcement height. By the desirability function approach, the recommendation of suitable welding parameters to meet the contradicting demands of multiple bead geometric features is fulfilled. The microstructure in different welding regions and mechanical performances of the welding joints produced by the verification test were also studied.

EXPERIMENTAL AND STATISTICAL INVESTIGATION OF THE EFFECTS OF CUTTING PARAMETERS ON KERF QUALITY AND SURFACE ROUGHNESS IN LASER CUTTING OF Al 5083 ALLOY

In this study, the effect of cutting parameters on kerf quality and surface roughness in laser cutting of Al 5083 alloyed material was investigated both experimentally and statistically (Taguchi & Gray Taguchi). Experimental design was determined using the Taguchi L[Formula: see text] (21x 3[Formula: see text] orthogonal array. Experiments were carried out by using two different gas pressures (GP) (8 and 10 bar), three different cutting speeds (CS) (3500, 4000 and 4500[Formula: see text]mm[Formula: see text][Formula: see text][Formula: see text]min[Formula: see text] and laser power (P) (2600, 3100 and 3600[Formula: see text]W) in the cutting of Al 5083 alloyed material. As a result of the study, top kerf width (TKW), bottom kerf width (BKW) and average surface roughness (Ra) were measured as output parameter values. Using the measured top and BKW results, kerf taper (KT) was calculated. The lowest values of TKW, BKW, KT and Ra were 2.219[Formula: see text]mm, 2.010[Formula: see text]mm, 0.984∘ and 2.394[Formula: see text][Formula: see text]m, respectively. To determine the optimum values of laser cutting parameters for minimum output parameters, signal-noise (S/N) ratio, variance and regression analysis, validity experiments and GRA methods were used. When S/N ratios were examined, the most ideal cutting parameters were determined as A1B3C1 for TKW and BKW, A2B1C3 for KT and A2B3C3 for Ra. When the variance results were examined, it was determined that the most effective processing parameter for TKW, BKW and KT was at 46.04%, 50.58% and 56.45% CS, respectively, and the most effective processing parameter for Ra was laser power with 46.57%. According to gray relationship analysis, optimum laser cutting parameters for the smallest values of all output parameters were determined as A1B3C1. According to gray relationship analysis, optimum laser cutting parameters for the smallest values of all output parameters were determined as A1B3C1.

FEM modeling and simulation of kerf formation in the nanosecond pulsed laser engraving process

In the present study, a finite element method (FEM) simulation model is developed for nanosecond pulsed laser engraving process. The model’s novelty lies in the fact that it predicts the actual dimensions of the engraved geometry emphasizing the dimensional deviation due to the defects from kerf formation such as the sloped side walls instead of the intended vertical ones. Simulations were performed and the values of kerf taper angle, top kerf width and bottom kerf width were compared with the corresponding ones from experimental tests made using a LASERTEC 40 laser engraving machine and also were used for process optimization.

DETERMINING THE EFFECT OF CHANGING CHANNEL GEOMETRY OF IRRIGATION CANALS ON DISSOLVED OXYGEN CONCENTRATION

Dissolved oxygen (DO) is an important water quality parameter. It is considered the most important parameter. DO concentration in water is affected by different parameters such as volume flow rate, water velocity, and re-aeration rate. Those parameters are directly affected by the geometry of the waterway. Thus, studying the impact of changing channel geometry on DO is very important. Many researchers studied the effect of influential parameters on water quality variables but the influence of channel geometric parameters on DO was not studied thoroughly before. This research aims to study the effect of changing channel geometry on DO concentration. The DO is modeled along the channel using Streeter-Phelps equation. Studied geometric parameters are water depth, bottom width, side-slopes, and channel length. The case study is taken as Sheikh Zayed canal in Egypt. Sheikh Zayed canal is responsible for irrigating Toshka land in the Western Desert of Egypt. It is also responsible for increasing the cultivated area of Egypt by about 550,000 feddans. It was found that the DO concentration is greatly affected by changing the geometry of the canal, as the canal geometry directly influences the flow velocity as well as reaeration rate. The percentage change of DO concentration with every geometry parameter is for length 6.8%, bed width 1.8%, water depth 4%, and side slopes 1.4%.

Heat and water flux modeling in an earth dam.

This study aims to identify the water flux in an earth dam using heat flux due to convection. Sixteen earth dam models were constructed in a hydraulic flume by varying geometrical and flow input parameters to identify heat and water flux. Homogeneous as well as earth dams with clay cores were built in a hydraulic flume. Temperature measurements were done to calculate heat flux in the experimental model. A finite element model of the earth dam using Seep/w was developed to obtain water flux, while temp/w was used to obtain heat flux. These results were used as input in Temp/w and Seep/w in Geostudio 2020. Significant reduction of the heat and water flux was seen while comparing the homogeneous models with central impervious core models. An increase in the heat and water flux was observed on increasing the downstream filter's length, longitudinal slope, and vice versa with the upstream slope and the thickness of the clay core. Comparing fluxes in a homogeneous dam model (model 1) with the clay core model (model 9) with top width 2.4 m and bottom width 18 m in model 9, both water flux and heat flux were reduced by 78.46%. While comparing it with model 10, with bottom core width of 18 m and top core width of 1.9 m, both water flux and heat flux reduced by 77.72%. Heat flux measurements were found to be a valuable alternative to detecting water flux and seepage in an earth dam at a reduced cost.

A Comparative Study on the Wettability of Unstructured and Structured LiFePO4 with Nanosecond Pulsed Fiber Laser.

The wettability of electrodes increases the power and energy densities of the cells of lithium-ion batteries, which is vital to improving their electrochemical performance. Numerous studies in the past have attempted to explain the effect of electrolyte and calendering on wettability. In this work, the wettability behavior of structured and unstructured LiFePO4 electrodes was studied. Firstly, the wettability morphology of the structured electrode was analyzed, and the electrode geometry was quantified in terms of ablation top and bottom width, ablation depth, and aspect ratio. From the result of the geometry analysis, the minimum measured values of aspect ratio and ablation depth were used as structured electrodes. Laser structuring with pitch distances of 112 μm, 224 μm, and 448 μm was applied. Secondly, the wettability of the electrodes was measured mainly by total wetting time and electrolyte spreading area. This study demonstrates that the laser-based structuring of the electrode increases the electrochemically active surface area of the electrode. The electrode structured with 112 μm pitch distance exhibited the fastest wetting at a time of 13.5 s. However, the unstructured electrode exhibited full wetting at a time of 84 s.

Influence of process parameters for sheet lamination based on laser micro-spot welding of austenitic stainless steel sheets for bone tissue applications

The laser micro-spot welding process was studied to implement a sheet lamination process-based methodology for the fabrication of austenitic stainless steel scaffolds. AISI 302 sheets with a thickness of 254 μm were laser cut and laser welded. Experimental tests were carried out with different values of average laser power (i.e., 180, 200, and 220 W) and different exposure times (25, 50, 75, 100, 125 ms). The micro-spot welds were visually inspected according to the ISO 13919-1 Class B requirements. Spot welds were qualitatively characterized, and weld dimensions were measured (i.e., penetration depth, top, middle, and bottom width and the heat-affected zone (HAZ)) to identify the cross-sectional shape. Furthermore, process efficiencies (i.e., coupling, melting, and process) were studied. A seam welding model was adapted to calculate the required exposure time and was used to obtain a micro-spot weld to accomplish the quality requirements of the scaffold. A scaffold prototype was designed and manufactured using the selected parameters by experimental trials and using the mathematical model (i.e., a laser power of 220 W and an exposure time of 45 ms).

Effects of Chronic Secondhand Smoke (SHS) Exposure on Cognitive Performance and Metabolic Pathways in the Hippocampus of Wild-Type and Human Tau Mice.

Background:Exposure to secondhand smoke (SHS) is a risk factor for developing sporadic forms of sporadic dementia. A human tau (htau) mouse model is available that exhibits age-dependent tau dysregulation, neurofibrillary tangles, neuronal loss, neuroinflammation, and oxidative stress starting at an early age (3–4 months) and in which tau dysregulation and neuronal loss correlate with synaptic dysfunction and cognitive decline.Objective:The goal of this study was to assess the effects of chronic SHS exposure (10 months’ exposure to ) on behavioral and cognitive function, metabolism, and neuropathology in mice.Methods:Wild-type (WT) and htau female and male mice were exposed to SHS (90% side stream, 10% main stream) using the SCIREQ® inExpose™ system or air control for 168 min per day, for 312 d, 7 d per week. The exposures continued during the days of behavioral and cognitive testing. In addition to behavioral and cognitive performance and neuropathology, the lungs of mice were examined for pathology and alterations in gene expression.Results:Mice exposed to chronic SHS exposure showed the following genotype-dependent responses: a) lower body weights in WT, but not htau, mice; b) less spontaneous alternation in WT, but not htau, mice in the Y maze; c) faster swim speeds of WT, but not htau, mice in the water maze; d) lower activity levels of WT and htau mice in the open field; e) lower expression of brain PHF1, TTCM1, , and HSP90 protein levels in WT male, but not female, mice; and f) more profound effects on hippocampal metabolic pathways in WT male than female mice and more profound effects in WT than htau mice.Discussion:The brain of WT mice, in particular WT male mice, might be especially susceptible to the effects of chronic SHS exposure. In WT males, independent pathways involving ascorbate, flavin adenine dinucleotide, or palmitoleic acid might contribute to the hippocampal injury following chronic SHS exposure. https://doi.org/10.1289/EHP8428

Rotary Plow Modification of Four-Wheel Tractor Type Iseki 504 for Making Beds

This research aimed to modify the rotary plow into a bed-making tool. The performance test of the bed-making tool was carried out on sandy and loamy land by experimental method. The dimensions of the bed including the length, width, and height of the bed as well as the time are also measured in the tool performance test. The bed-making tool has a total length of 182 cm, the length of the right and left sides of each was 51 cm, the width was 25 cm and the height was 30 cm. The test of the bed-making tool by a four-wheel tractor was carried out on sandy land at a distance of 10 m and a loamy land at a distance of 25 m, bed making was performed 5 times. Experimental results on sandy land showed that the average bed height was 23.6 cm; the bottom width was 80 cm, and the top width bed was 56.4 cm with a processing time of 2.12 minutes. Loamy land testing showed that the average bed height was 21.2 cm; the bottom width was 80 cm, the top width was 58.8 cm with a processing time of 4.27 minutes. Based on the test results on two different types of land, it can be seen that the tool works more effectively and efficiently on sandy land than loamy land.

Strong and Short Bragg Waveguide Gratings With Trapezoidal-Shaped Grooves

In this study, we evaluate strong Bragg waveguide gratings formed of trapezoidal-shaped grooves, as typically produced in surface-etched structures, and we propose optimal groove shapes. We begin by validating our modelling approach, which is based on the finite-difference time-domain method, through comparisons with coupled mode theory applied to rectangular gratings. We then compute the reflectance, transmittance and loss of trapezoidal gratings as a function of Bragg order, and of the top and bottom widths of the grooves. Simulations reveal that the highest reflectance peaks are achieved for widths that are about λ/8, regardless of the Bragg order. We find that the characteristics of trapezoidal-grooved gratings are strongly dependent on the bottom width of the grooves, and that a very high reflectance can be achieved by carefully tailoring this width. We also calculate the coupling coefficients of infinitely long optimized structures, finding that they decrease with increasing Bragg order. Our results are of interest in the design of strong short gratings etched in the surface of semiconductor waveguides.

A study of kerf quality of Inconel 718 using abrasive water jet cutting

This study shows the experimental investigation on Inconel 718 to find the parametric response of abrasive water jet cutting on top Kerf width (Wt), bottom Kerf width (Wb) and Kerf wall inclination. The machining are planned with Box Behnken Design (BBD) based on four factors at three levels each. Four important process parameters e.g P, AFR, SOD and TS, were selected in cutting. The quadratic regression models were established to forcast the Kerf quality by using response surface methodology. ANOVA has been employed to find the influence of operating factors. Result reports that traverse speed is the most influenced parameter in affecting the Kerf taper.