scholarly journals The impact of surface roughness and permeability in hydroxyapatite bone regeneration membranes

2015 ◽  
Vol 27 (8) ◽  
pp. 1047-1054 ◽  
Author(s):  
Jonas Anderud ◽  
Ryo Jimbo ◽  
Peter Abrahamsson ◽  
Erik Adolfsson ◽  
Johan Malmström ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Bone Regeneration ◽  
The Impact

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

Nature instigated Grey wolf algorithm for parametric optimization during machining (Milling) of polymer nanocomposites

2021 ◽  
pp. 089270572199320
Author(s):  
Prakhar Kumar Kharwar ◽  
Rajesh Kumar Verma
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Polymer Nanocomposites ◽  
Feed Rate ◽  
Fitness Function ◽  
Depth Of Cut ◽  
Multiwall Carbon Nanotube ◽  
Grey Wolf ◽  
Milling Characteristics ◽  
The Impact

The new era of engineering society focuses on the utilization of the potential advantage of carbon nanomaterials. The machinability facets of nanocarbon materials are passing through an initial stage. This article emphasizes the machinability evaluation and optimization of Milling performances, namely Surface roughness (Ra), Cutting force (Fc), and Material removal rate (MRR) using a recently developed Grey wolf optimization algorithm (GWOA). The Taguchi theory-based L27 orthogonal array (OA) was employed for the Machining (Milling) of polymer nanocomposites reinforced by Multiwall carbon nanotube (MWCNT). The second-order polynomial equation was intended for the analysis of the model. These mathematical models were used as a fitness function in the GWOA to predict machining performances. The ANOVA outcomes efficiently explore the impact of machine parameters on Milling characteristics. The optimal combination for lower surface roughness value is 1.5 MWCNT wt.%, 1500 rpm of spindle speed, 50 mm/min of feed rate, and 3 mm depth of cut. For lower cutting force, 1.0 wt.%, 1500 rpm, 90 mm/min feed rate and 1 mm depth of cut and the maximize MRR was acquired at 0.5 wt.%, 500 rpm, 150 mm/min feed rate and 3 mm depth of cut. The deviation of the predicted value from the experimental value of Ra, Fc, and MRR are found as 2.5, 6.5 and 5.9%, respectively. The convergence plot of all Milling characteristics suggests the application potential of the GWO algorithm for quality improvement in a manufacturing environment.

scholarly journals A Novel Sea Surface Roughness Parameterization Based on Wave State and Sea Foam

2021 ◽  
Vol 9 (3) ◽  
pp. 246
Author(s):  
Difu Sun ◽  
Junqiang Song ◽  
Xiaoyong Li ◽  
Kaijun Ren ◽  
Hongze Leng
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Drag Coefficient ◽  
Sea Surface ◽  
High Wind Speed ◽  
Wave State ◽  
Wind Speeds ◽  
Sea Surface Roughness ◽  
Extreme Wind ◽  
The Impact

A wave state related sea surface roughness parameterization scheme that takes into account the impact of sea foam is proposed in this study. Using eight observational datasets, the performances of two most widely used wave state related parameterizations are examined under various wave conditions. Based on the different performances of two wave state related parameterizations under different wave state, and by introducing the effect of sea foam, a new sea surface roughness parameterization suitable for low to extreme wind conditions is proposed. The behaviors of drag coefficient predicted by the proposed parameterization match the field and laboratory measurements well. It is shown that the drag coefficient increases with the increasing wind speed under low and moderate wind speed conditions, and then decreases with increasing wind speed, due to the effect of sea foam under high wind speed conditions. The maximum values of the drag coefficient are reached when the 10 m wind speeds are in the range of 30–35 m/s.

High-Frequency and Passive Radar Designs for Homeland Security Applications

2011 ◽  
Vol 45 (3) ◽  
pp. 111-119 ◽  
Author(s):  
Magdy F. Iskander ◽  
Zhengqing Yun ◽  
Nuri Celik ◽  
Hyoungsun Youn ◽  
Nobutaka Omaki ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Homeland Security ◽  
High Frequency ◽  
Beam Steering ◽  
Antenna System ◽  
Hf Radar ◽  
Passive Radar ◽  
High Definition ◽  
Security Applications ◽  
The Impact

AbstractEmerging homeland security applications require low-cost and fast, deployable, high-frequency (HF) radar systems and the ability to operate in challenging terrain environments. With the need to cover as many border and coastal areas as possible, taking advantages of available transmitter resources to track targets using passive radar technologies is yet another area of research of considerable interest. In this paper, we describe the development of an HF radar system that meets these operational challenges, and we also highlight some recent implementation of the passive radar technology for homeland security applications. Specifically, we describe the design of a novel, electrically small HF antenna system consisting of three helical elements, one connected to the feed port while the other two are folded arms terminated with switchable loads. The antenna is 0.90-m (<3 feet) high with a small ground disk of 0.60 m (∼2 feet) diameter. The antenna is self-resonant at multiple frequencies (5.7, 16, 20.5, and 27.7 MHz) and with input impedance values that can be easily matched to a 50-Ω coaxial feed. Values of the electrical size ka range from 0.44 at 30 MHz down to 0.08 at 5.7 MHz. The achieved bandwidths range from 1.4% up to 12% and associated efficiencies range from 66.2% to 76% within the HF band (3‐30 MHz). As for the operational requirement in challenging terrain environments, a setup in a hilltop-type environment with a slope terrain and surface roughness was considered. A propagation modeling and ray-tracing approach was used to evaluate the impact of such terrain conditions on the effective interelement spacing of an HF radar antenna array and the subsequent impact on its beamforming and beam steering performance. It is shown that while the effect of the slope on the effective interelement spacing of the array could be very significant, diffraction effects from surface roughness resulted in a much smaller, but significant, error of about 18°. Results from some initial work on the implementation of passive radar technology, with focus on addressing the bandwidth requirement to ensure practical resolution values, are also described. It is shown that signals from wide-band transmitters (e.g., High Definition Television [HDTV] signals) rather than those from radio stations are required to provide acceptable range resolution. These as well as simulation and experimental results of the antenna design, and results from beamforming simulations illustrating the effect of a rough hilltop terrain on the HF radar performance are described.

Surface Roughness Impact on Secondary Flow and Losses in a Turbine Exhaust Casing

2018 ◽  
Author(s):  
Isak Jonsson ◽  
Valery Chernoray ◽  
Borja Rojo
Keyword(s):  
Surface Roughness ◽  
Secondary Flow ◽  
Suction Side ◽  
Pressure Probe ◽  
Time Resolved ◽  
Pressure Distributions ◽  
Turbulence Decay ◽  
Inlet Swirl ◽  
High Level ◽  
The Impact

This paper experimentally addresses the impact of surface roughness on losses and secondary flow in a Turbine Rear Structure (TRS). Experiments were performed in the Chalmers LPT-OGV facility, at an engine representative Reynolds number with a realistic shrouded rotating low-pressure turbine (LPT). Outlet Guide Vanes (OGV) were manufactured to achieve three different surface roughnesses tested at two Reynolds numbers, Re = 235000 and Re = 465000. The experiments were performed at on-design inlet swirl conditions. The inlet and outlet flow of the TRS were measured in 2D planes with a 5-hole probe and 7-hole probe accordingly. The static pressure distributions on the OGVs were measured and boundary layer studies were performed at the OGV midspan on the suction side with a time-resolved total pressure probe. Turbulence decay was measured within the TRS with a single hot-wire. The results showed a surprisingly significant increase in the losses for the high level of surface roughness (25–30 Ra) of the OGVs and Re = 465000. The increased losses were primary revealed as a result of the flow separation on the OGV suction side near the hub. The loss increase was seen but was less substantial for the intermediate roughness case (4–8 Ra). Experimental results presented in this work provide support for the further development of more advanced TRS and data for the validation of new CFD prediction methods for TRS.

scholarly journals Rated definition of degree of cutter coating influence upon parameters of surface layer quality of parts worked

2017 ◽  
Vol 2 (7) ◽  
pp. 20-24
Author(s):  
Вячеслав Безъязычный ◽  
Vyacheslav Bezyazychnyy ◽  
Максим Басков ◽  
Maksim Baskov
Keyword(s):  
Surface Roughness ◽  
Surface Layer ◽  
Residual Stresses ◽  
Layer Surface ◽  
Wear Resistant Coatings ◽  
Cutter Wear ◽  
Definition Of ◽  
Surface Layer Quality ◽  
The Impact

The impact of cutter wear-resistant coatings upon cutting process parameters and characteristics of surface layer quality in the parts worked: residual stresses, a degree and a depth of work hardening of a surface layer, surface roughness is investigated.

scholarly journals The Impact of Slicing Softwares on the Mechanical Properties of 3D Printed Parts

2020 ◽  
Vol 9 (2) ◽  
pp. 487-494
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
3D Printer ◽  
Stl File ◽  
3D Printed ◽  
Intersection Curves ◽  
The Impact

“Slicing tool” or “Slicing Software” computes the intersection curves of models and slicing planes. They improve the quality of the model being printed when given in the form of STL file. Upon analyzing a specimen that has been printed using two different slicing tools, there was a drastic variation on account of the mechanical properties of the specimen. The ultimate tensile strength and the surface roughness of the material vary from one tool to another. This paper reports an investigation and analysis of the variation in the ultimate tensile strength and the surface roughness of the specimen, given that the 3D printer and the model being printed is the same, with a variation of usage of slicing software. This analysis includes ReplicatorG, Flashprint as the two different slicing tools that are used for slicing of the model. The variation in the ultimate tensile strength and the surface roughness are measured and represented statistically through graphs. An appropriate decisive conclusion was drawn on the basis of the observations and analysis of the experiment on relevance to the behavior and mechanical properties of the specimen.

Impact of CF4 Plasma Treatment on the Surface Roughness of Ion Implanted SiC Induced by High Temperature Annealing

2010 ◽  
Vol 645-648 ◽  
pp. 783-786
Author(s):  
Tatsunori Sugimoto ◽  
Masataka Satoh ◽  
Tohru Nakamura ◽  
K. Mashimo ◽  
Hiroshi Doi ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Temperature ◽  
Energy Range ◽  
Plasma Treatment ◽  
Surface Roughening ◽  
High Temperature Annealing ◽  
Small Surface ◽  
Step Structure ◽  
The Impact ◽  
Ion Implanted

The impact of CF4 plasma treatment on the surface roughening of SiC has been investigated for N ion implanted SiC(0001) which is implanted with the energy range from 15 to 120 keV at a dose of 9.2 x 1014/cm2. The N ion implanted sample, which is processed by CF4 plasma, shows small surface roughness of 1.6 nm after annealing at 1700 oC for 10 min, while the sample without CF4 plasma treatment shows the large surface roughness (6.6nm) and micro step structure. XPS measurements reveals that CF4 plasma treatment is effective to dissolved the residual oxide on the surface of SiC which is not removed by BHF acid of SiO2 layer on SiC. It is strongly suggested that the formation of micro step structure with the increase of the surface roughness is promoted by the residual oxide such as SiCOx, on SiC.

The impact of immobilization of BMP-2 on PDO membrane for bone regeneration

2012 ◽  
Vol 100A (6) ◽  
pp. 1488-1493 ◽  
Author(s):  
Ji-Eun Kim ◽  
Eun-Jung Lee ◽  
Hyoun-Ee Kim ◽  
Young-Hag Koh ◽  
Jun-Hyeog Jang
Keyword(s):  
Bone Regeneration ◽  
The Impact
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