Determination of the optimum ball radius for researching materials using ball indenting

The article discusses the study of the effect of a change in the radius of the ball in the injecting of the sample on the curve in the coordinates «load – indentation depth», the deviation of the indentation depth during elastoplastic indentation from the indentation depth with the elastic indentation and the amount of the axial deformation of the ball. The study was conducted using the Ansys Mechanical APDL program implementing the fenite element method. In the process of the study, it was found that with a change in the radius of the ball, there is no obvious change in the behavior of the sample material, and the deviation of the indentation depth during the elastoplastic indulgence from the indentation depth during the elastic indentation is not dependent on the size of the ball radius. There was also an effect of changing the radius of the ball on the size of the axial deformation of the ball and proposed a formula for determining the size of the axial deformation of the ball for the ball of any diameter, which will determine the actual depth of the ball into the ball when using the balls of different radius.

Evaluation of Surface Landmarks and C-length as Predictors of the Depth of Right Internal Jugular Venous Catheter Insertion: A Transesophageal Echocardiography-Guided Study

Background Central venous catheterization is a standard clinical practice for infusion of fluids, blood products, or vasoactive drugs to the central circulation and to monitor central venous pressure during perioperative periods. However, this procedure can lead to significant complications, including cardiac arrhythmia, vascular injury, hydrothorax, hemothorax, hydromediastinum, and cardiac tamponade. Such complications can occur when the catheter tip is inserted within the heart chamber or when it abuts the vascular wall at a steep angle. Objectives The primary aim of the current study is to examine the accuracy of the C-distance or surface landmarks in determining the length of CVC that is required to place the catheter tip at the mid-SCV as confirmed by transesophageal echocardiography (TEE). A secondary aim is to derive an equation or formula to calculate the depth of the CVC that is required in order to have the catheter tip placed at the mid-SVC. Patients and Methods After obtaining the approval from research ethical committee of Ain Shams University and obtaining informed consent from patients the study was conducted in The Academic Institute for Cardiothoracic and Vascular Surgery, Ain Shams University hospitals. 30 adult patients scheduled for elective cardiac surgeries were enrolled in the study after being selected by random simple method. Results We used the TEE to visualize the CVC tip 3 cm above SVC-RA junction and use this actual depth to compare between the accuracy of the expected depth by C-length method and expected measured depth by surface landmarks method; we found out that the two methods were nearly the same to the actual depth guided by TEE. The mean ± SD surface landmarks distance was 142 ± 12 mm (range, 120 - 162 mm) and the mean ± SD by C-length was 128 ± 18 mm (range, 95 - 174 mm). The mean ± SD TEE-guided CVC length needed to place CVC tip at mid-SVC was140 ± 13 mm (range, 110 - 162 mm). Also in none of the patients was the CVC tip placed below the carinal level on postoperative plain AP chest x-ray. The CVC tip was placed at a mean ± SD height of 12 ± 2 mm (range, 5 to 16 mm) above the carinal line, which concludes that the mid SVC region lies above the carina level by 0.5-1.5 cm and it’s a reliable landmark for postoperative confirmation of optimum placement of CVC tip. Conclusion TEE can be used to effectively determine the proper fixed catheter insertion depth for a patient through the right internal jugular vein. This study showed that both C-length and surface landmarks methods are accurate to determine the depth of the central venous catheter in the mid SVC region (3-3.5 cm) above SVC-RA junction above pericardial reflection. Another conclusion is that the mid SVC region is above carinal level in all cases by 5 mm -15 mm. From this study we formulated two regression equations depending on the expected surface landmarks and C-length with an accuracy of ± 11.662 mm and ± 10.643 mm respectively.

Focusing Technique for Holographic Subsurface Radar Based on Image Entropy

An image focusing method for holographic subsurface radar (HSR) is proposed herein. HSR is increasingly being utilized to survey objects buried at shallow depths and the acquired signals are converted into an image by a reconstruction algorithm. However, that algorithm requires actual depth and material information or depends on human decisions. In this paper, an entropy-based image focusing technique is proposed and validated by numerical simulation software package based on finite-difference time-domain method and experiment. The resulting images show good agreement with the actual positions and shapes of the targets.

BathyNet: A Deep Neural Network for Water Depth Mapping from Multispectral Aerial Images

Besides airborne laser bathymetry and multimedia photogrammetry, spectrally derived bathymetry provides a third optical method for deriving water depths. In this paper, we introduce BathyNet, an U-net like convolutional neural network, based on high-resolution, multispectral RGBC (red, green, blue, coastal blue) aerial images. The approach combines photogrammetric and radiometric methods: Preprocessing of the raw aerial images relies on strict ray tracing of the potentially oblique image rays, considering the intrinsic and extrinsic camera parameters. The actual depth estimation exploits the radiometric image content in a deep learning framework. 3D water surface and water bottom models derived from simultaneously captured laser bathymetry point clouds serve as reference and training data for both image preprocessing and actual depth estimation. As such, the approach highlights the benefits of jointly processing data from hybrid active and passive imaging sensors. The RGBC images and laser data of four groundwater supplied lakes around Augsburg, Germany, captured in April 2018 served as the basis for testing and validating the approach. With systematic depth biases less than 15 cm and a standard deviation of around 40 cm, the results satisfy the vertical accuracy limit Bc7 defined by the International Hydrographic Organization. Further improvements are anticipated by extending BathyNet to include a simultaneous semantic segmentation branch.

A Deliberation on the Stages of Artificial Intelligence

Artificial Intelligence (AI) is a technology that can be programmed to mimic humans' natural intelligence, which helps the machines perform the tasks that a human being can do. After a long research period from 1955, the researchers have achieved remarkable achievements like machine learning and deep learning in this field. Other areas like education, agriculture, medical, etc., to name a few, also utilizing these technologies for its improvements. All the achievements made in this field are not even comparable to the actual depth of this technology, where the depth of AI is yet to measure; that is, a long way to go to develop a fully functional AI. To identify the extent of its depth, firstly, the path to the AI's core should be visibly defined, and secondly, the milestones are to be placed in between. There are some general stages and types of AI introduced by other researchers, but it cannot be used for further research due to the inconsistency in the information. So, to bring standardized information in the Stages of AI is as important as setting up a good base in this field. The paper proposes and defines new stages of AI that could help set the milestones. The work also places a general standard, brings more clarity, and eliminates the inconsistencies in the Stages of AI.

COMPOSITION AND QUALITY OF FRESHWATER LAKE SEDIMENTS (BALVU AND PĒRKONU LAKES)

Water quality, watershed basin and urbanization are key factors from the perspective of freshwater management; however, actual depth of waterbodies is often an overlooked element. Actual depth represents the overall depth of lake bed and depth of sediments. Some cases have been reported, where with increase of average depth of lake, it is possible to expect improvements of water quality when sediments are removed. If lakes are eutrophic, shallow, overgrown with macrophytes and contain high concentrations of biogenic elements water and lake ecosystem quality can be endangered. Removal of sediments can be an expensive procedure and also depends on the composition, structure, local conditions and total amount of sediments, also the disposal or possible use of sediments must be considered. Therefore, it is crucial to understand not only the genesis of sediments, but also possible pollutants, especially in urban territories. Two lakes in Latvia, where the coastal areas of lakes are urbanized at different levels, were studied. Lake Pērkonu was less affected from urbanization than Lake Balvu, cumulative effects of sedimentation and eutrophication were shown as these two lakes are interconnected. Characterization of lake sediments was done, including measurements of pH, ash content, analysis of C/N ratio, biological composition, metals, polyaromatic hydrocarbons (PAH), content of organic matter and concentration of humic acids. Results show that structure and composition of sediments in studied lakes differ with increasing depth, giving opportunity to track environmental changes in the past and differentiate possible applications of sediments. In deeper layers sediments were mostly formed from algae, but in more recent stages of lake development macrophytes were more dominant. Sediments formed after Ice-Age and located close to the bottom of the lake differ from conditions on paste (relief of lake bed, streams etc.), because areas with accumulated clay material and areas with sandy material were present.

Pulsed Laser Surface Treatment for Improvement of Machinability

The surface of worn dies are often machined to remove the worn layer and then to re-form its shape. But, in machining operations for hardened materials, the high cutting force sometimes yields bending deflection of low stiffness tools, and results the decrease in productivity and accuracy.In this study, surface treatment by pulsed laser is applied for the high hardness materials to improve the machinability in the machining operation. Die steels are used as work material machined with ball endmills of carbide in the experiments where the cutting force and the actual depth of cut are measured to obtain the specific cutting energy and to evaluate the machinability. In endmilling operations of the nitrided die steels, the actual depth of cut is decreased by the bending deflection of endmill. However, the surface treatment with laser moderates the decreasing of the actual depth of cut. It is confirmed that the surface of workpiece pre-treated with laser has larger roughness than un-treated ones, and the specific cutting energy is decreased by laser surface pre-treatment.

Computer-Aided Simulation of Dressing Using Diamond Rotary Dresser and Visualization of Dressing Process

The surface of a grinding wheel dressed by a diamond rotary dresser was generated by computer-aided simulation for the case of multipass dressing on the assumption that the grinding wheel is a homogeneous solid body and the dressing trajectories of the diamond grits are perfectly copied on the grinding wheel surface. The dressing process was visualized as a contour map of the dressed surface profile and the effects of the dressing strategy, i.e., down-cut dressing or up-cut dressing, on the grinding wheel removal process were investigated. It was found that the diamond grits remain the residual depth of cut on the surface of the grinding wheel, resulting in an actual depth of cut larger than that given by the rotary dresser.

Precision Micromachining Channels in Highly Elastic Polymers for Applications in Tissue Engineering

The aim of this research is to investigate the effect of elastic recovery on the ability to precisely control depth of cut when micromachining channels in poly(methyl methacrylate) (PMMA). Both a standard and impact resistant PMMA were machined using an orthogonal micro-slitting arrangement. While holding speed and cutting edge radius constant, the intended depth of cut was varied from 10 μm to 85 μm in order to determine the actual depth of cut due to chip formation and the fraction of material that was ploughed and then elastically recovered. Elastic recovery was determined by using a profilometer to measure step height after machining a partial groove. Results show that intended depth of cut and actual depth of cut are a function of material properties, with greater ploughing occurring in the PMMA material with lower tensile strength and higher strain to yield. When cutting resulted in a permanent trench being formed, actual depth of cut was related in a linear manner to the intended depth of cut. At lower intended depths of cut, the majority of material was ploughed beneath the cutting edge with little evidence of chip formation. In addition, at lower depths of cut a size effect was observed, where thrust force exceeded cutting force. Greater cutting and thrust forces were evident from the PMMA material with higher tensile strength. Resultant forces for both samples were related in a linear manner to the final trench depth. In general, the results indicate that orthogonal micro-slitting experiments may be used to generate process maps to accurately predict the depth of cut achieved when micromachining channels in highly elastic polymers.