Height Of Irregularities Research Articles

Structure and properties of additive products manufactured from electroerosion powders

The paper considers the possibility of using electroerosion metal powders based on the Co-Cr alloy with different properties in additive technologies. Use of these powders opens up great opportunities for improving the technical and economic characteristics of products, and will contribute to a significant increase in their reliability, durability, weight reduction, reduction of manufacture and operation costs. The economic efficiency of the use of electroerosion cobaltchromium powders is due to the use of waste and low energy-intensive technology for their production. The aim of this work is studying the technology of powder fusion obtained by electroerosion dispersion of cobaltchromium alloy waste in alcohol, on porosity, microhardness and roughness of additive products. The process of electrodispersion, i.e. grinding of the KKhMS "Cellite" alloy (63 % Co, 27 % Cr, 5 % Mo, 2 % Ni, 2 % Fe) was carried out on an original patented installation. After dispersion of cobalt-chromium alloy waste, its destruction occurred as a result of local exposure to short-term electrical discharges between the electrodes located in the working fluid, with formation of powder particles. Butyl alcohol was used as the working fluid. The fusion of electroerosion cobalt-chromium powders was carried out by plasma on the original installation for layer-by-layer deposition, which allows varying the technological parameters of the process: the nozzle transition speed (mm/min), the distance between the nozzle and the construction zone (mm), and the fusion temperature (°C). Based on a set of experimental studies, it was found that the melting temperature of particles of electroerosion cobaltchromium powder practically does not effect on varying in the elemental and phase composition of samples; at the same time, with an increase of the melting temperature, the pores size and their number decrease, as well as an increase of microhardness with decrease of the height of irregularities and roughness in general are observed. The research was conducted under financial support of the Russian scientific fund. The project number 17-79-20336P.

Determinants of cerebral aneurysm occlusion after embolization with the WEB device: a single-institution series of 215 cases with angiographic follow-up

BackgroundWoven EndoBridge (WEB) devices are becoming a reliable option for the treatment of wide-neck bifurcation aneurysms, but clear predictive factors are still missing to understand the one in five aneurysm...

Automatic relative humidity optimization in underground heritage sites through ventilation system based on digital twins

Underground heritage sites generally experience significant humidity, which results in the destruction of the surfaces and structures. This study establishes an underground heritage site preservation mechanism through a dynamic ventilation system based on digital twin technology. The aim is to control the relative humidity (RH) gradually on the air region near the walls of sites within the standard range and reduce adverse physical equipment effects and energy consumption of the system. Underground heritage site projects have more complex shapes with irregular and nonlinear arcs and height difference distributions. It is challenging to regenerate them. To achieve this objective, a model simplification rule for irregular heritage building information modeling (HBIM) technology was first established via computational fluid dynamics (CFD) simulation. Second, a methodology was developed to design a reliable and effective ventilation equipment and its layout based on CFD for irregular heritage sites. Compared with the scheme based on the optimal geometric rule arrangement, the number of pipes can be reduced by up to 25%. Third, a web-based digital twin platform combined with Internet of Things (IoTs) technology was established for achieving real-time control of the overall RH level of underground heritage sites within the standard range. The results present new solutions to control the RH of underground heritage sites for preservation. The proposed methodology can be used in typical underground heritage sites and illustrated by a real case. The validation encompassed development of digital environment for the real case and development of the ventilation system for its RH optimization.

ИССЛЕДОВАНИЕ ОПТИЧЕСКИХ СПЕКТРОВ ПРОПУСКАНИЯ И ПАРАМЕТРОВ ОБРАБОТКИ ПОВЕРХНОСТИ ИНТРАОКУЛЯРНЫХ ЛИНЗ

Manufacturers of intraocular lenses are constantly improving the parameters of artificial lenses,functionally bringing them closer to their natural counterpart. In this work, an experimental study of anumber of important physical and technical parameters of intraocular lenses of the world's leadingmanufacturers, affecting the quality of vision of operated patients, was carried out. The transmissionspectra of optical radiation of intraocular lenses in the range of 200–800 nm were investigated. In theshort-wavelength part, the measurement results showed a high efficiency of the protective properties ofintraocular lenses from ultraviolet radiation. It is shown that radiation with a wavelength of up to350 nm is completely absorbed by the lens material, and the transmission of waves with a wavelength of400 nm is 20 %. Further, up to a wavelength of 550 nm, an increase in the transmittance of the studiedintraocular lens to 100 % is observed, after which it gradually decreases to the end of the visible rangeto 85%. The work also investigated the influence of the quality of the surface treatment of intraocularlenses on the likelihood of secondary cataract development in the long-term period. Accordingto postoperative statistics, the likelihood of secondary cataract is 20–35 %. The appearance ofareas of optical opacity is due to various factors, one of which is the quality of the surface treatmentof intraocular lenses. The smoothness of the surface profile of the lens depends on the model,manufacturing technology and material of the artificial lens. The study of the quality of surfacetreatment of soft and hard intraocular lenses was carried out by atomic force microscopy. Ananalysis of the results of scanning the surface of intraocular lenses and a statistical analysis of630 clinical cases of secondary cataract in the long-term postoperative period (6 months or more)showed their relationship. If the height of irregularities (protrusions) on the lens surface increasesto 70 nm or more, the likelihood of secondary cataract in the postoperative period increases from6 to 15 %.

Results of an experimental study to determine the possible values of trauming software parameters

The parameters of the comprehensive small-leveler levelers developed in the article, that is their installation angle with respect to the direction of movement, length, vertical distance from the lower edge of the levelers to the rod and the speed of the aggregate are determined by the heights of irregularities in the treated area. The results of multivariate experimental studies to determine the optimal values that provide the average quadratic deviation and soil density at the level of agro-technical requirements with low energy consumption are presented. The multivariate experiments were performed according to the Hartley-3 plan. The data obtained from the experiments were processed by the PLANEXP program developed in the experimental department of QXMITI and regression equations adequately representing the evaluation criteria were obtained. The Cochrane criterion was used to assess the homogeneity of the variance, the Student's criterion was used to assess the value of the regression coefficients, and the Fisher criterion was used to assess the adequacy of the regression models. The obtained regression equations show that the average square deviation of the heights of the irregularities in the zone treated by the straighteners is not more than ± 2 cm, the density of the soil in the zone treated by the straighteners is in the range of 1.1–1.2 g/cm3. the optimum values of the parameters of the solution are determined together with the condition that the gravitational resistance of the device is minimal.

ON RANDOM EXPECTED VALUES VARIATIONS OF TRIBOLOGY PARAMETERS IN HUMAN HIP JOINT SURFACES

This paper presents recent progress in the knowledge concerning the stochastic theory of bio- hydrodynamic lubrication with a phospholipids bilayer. On the basis of experimental measurements and analytical solutions, the research concerns the determination of the random expectancy values of load carrying capacity, the friction coefficient, and synovial fluid dynamic variations. After numerous measurements, it directly follows that the random density function of the gap height in the human joint usually indicates a disorderly increases and decreases in the height. Such irregular gap height variations have an important influence on the random synovial bio-fluid dynamic viscosity. This finally leads to the friction coefficient and cartilage wear changes of cooperating bio- surfaces. The main topic of this paper relates to the expectancy values of the tribology parameters localized inside the variable stochastic standard deviation intervals of the human joint gap height. The results obtained finally indicate the influence of the random roughness and growth of living biological cartilage surfaces on the expectancy values of the synovial fluid dynamic viscosity, load carrying capacity and friction forces in human hip joints.

Mathematical modeling of the movement of a tracked vehicle using the RecurDyn application package

Mathematical modeling of motion allows at the design stage to assess the impact of the design and operational parameters of tracked vehicles on their performance, determine the qualitative and quantitative performance indicators, and consider controllability issues. The use of the RecurDyn application with a library of specialized extension packages allows to obtain a mathematical model of the vehicle, taking into account its design with a specified degree of detail. A model of a tracked vehicle with a torsion bar suspension was developed using the Professional extension packs and the Track (HM) library of the Toolkit extension package. It allows simulating standard maneuvers on various supporting surfaces. The CoLink extension package implements a control model that ensures the movement of the tracked vehicle along a given trajectory. The basis for the development of the motion control model is a technique based on predicting the position of the vehicle after a given forecast time. As a control, the speed difference between the leading and lagging tracks was adopted. It ensures movement along a given trajectory. The difference in speeds ∆V is determined using PID regulation by the values of the lateral deviation of the vehicle from the given trajectory and the angular deviation of the longitudinal axis of the vehicle from the tangent to the trajectory in the predicted position. The control model allows to simulate the movement of a vehicle with a differential and a planetary rotation mechanism. The simulation of movement along a circular trajectory and the snake maneuver was carried out. The movement of a tracked vehicle with a planetary steering mechanism on a solid support surface with a friction 0.7 coefficient was simulated.
 Based on the simulation results, a conclusion about the adequacy of the mathematical model of the tracked vehicle and the performance of the presented motion control model was made. The developed model allows simulating various maneuvers of a tracked vehicle to assess the stability of movement and controllability, to determine the rational parameters of the tracked mover based on the results of simulation of movement at various heights of irregularities and speeds of movement.

Mine surveying technique and steel storage tank base deformation removal

Introduction. Vertical steel tanks are extensively used in oil fields to hold crude oil and other liquids. Their construction requires continuous surveying control. However, measurement procedures, data processing, and deviations and documentation correction are not universal and cannot be applied for tanks with a capacity of less than 3000 m3. Moreover, the process of correcting the detected bottom irregularities is poorly substantiated and intuitive. Research objective is to improve the as-built survey accuracy and reliability of the low-capacity steel tank bottom, substantiate the minimum height of its irregularities, increase the objectivity and productivity of measurement processing, develop an unambiguous method for time-predictable correction of bottom irregularities, and substantiate the optimal contents of its relief’s as-built scheme. Methods of research. Geometric leveling for the bottom profile survey failed to provide adequate accuracy and was therefore replaced by the method of trigonometric leveling. A method has been developed for determining the deviations of the existent tank bottom profile from the design position by means of algebraic actions with surfaces of a topographic order. The accuracy of determining the smallest height of bottom irregularities has been estimated under the tacheometric survey. A method has been proposed for controlling the correction of tank bottom irregularities based on evaluation calculations of bottom deformations by the finite element method. Research results. All the development results are exemplified by a specific production example. It was found that for a full completion of work, two iterations of tank bottom irregularities correction are enough. Methods of optimal design for the facility’s as-built schemes are presented. Conclusions. A simple, accurate, low-cost, productive, and time-predictable method of mine surveying, mathematical processing and correction of deviations in the tank bottom profile has been developed. This technique reduces the construction period and increases the operating time of the facility.

Regularities in the formation of wear-resistant coatings on steel samples when machining them with electrical discharge

This paper considers the technology of electrical discharge machining of steel friction pairs and reports the results of experimental studies. Analysis of the experimental studies has shown that increasing the "anode-cathode" voltage leads to a sharp decrease in the micro-hardness of the surface layer. The study has also made it possible to determine the characteristic dimensions of the structural elements, the height parameters of surface roughness. The elemental composition of the resulting surface of a steel 15KHGN2TA sample differs from the composition of coatings and the surface layers of samples modified by electrical discharge machining involving various electrodes. Under the "anode-cathode" system operation mode, a thin layer of coating with a stable modified structure forms on the surface of the cathode due to dissipative processes. It is shown that the height of surface irregularities on sections after friction is higher than on the surface sections outside the friction flow, which is associated with the formation of a friction transfer film on the samples' surface. It was established that the interaction of friction of steel samples treated by electrical discharge machining forms a thin film on the surface of friction of steel samples, which leads to a change in the relief of surfaces with an increase in the height of the micro-protrusions, as well as the structuring of the transfer film in the direction of sliding. The effect of machining steel surfaces by electrical discharge on the wear resistance of metal-polymer tribosystem was established. The implementation of the devised technology could provide a significant increase in the wear resistance of metal-polymer tribojunctions

Prediction of Road Traffic Noise by CRTN Model in a Sub-Urban Town of India

Present study was undertaken for assessment of spatial characteristics of road traffic noise at varying intervals viz early morning (8-9 am), late morning (11-12 pm), afternoon (2-3 pm) and evening (6-7 pm) time at ten important locations (near school building) of G. T. Road which is passing through the Burdwan town. Digital noise meter was used for recording the traffic noise and noise contour map was constructed by using Geographical Information System (GIS). The recorded data revealed that the highest and lowest average noise 67.1 dB (A) and 86.9 dB (A), respectively. The results revealed that the performance of the CRTN model in both afternoon and evening time for predicting noise level near school building with a coefficient of determination (R2) are 0.536 and 0.544 and a mean difference of - 1.19 dB (A) and - 0.48 dB (A) between the measured and predicted values respectively. Similarly, Pearson statistics also revealed the strong correlation between measured and predicted noise level at afternoon (r = 0.732, p < 0.016) and evening time (r = 0.744, p < 0.014). However, the predicted traffic noise during early morning and late morning hour are less than 0.5. These low values are due to irregular traffic speed, traffic density and irregular building height are the appropriate reasons for low accuracy in predicting model. Finally, it may be suggested that CRTN model can be a decision tool for predicting equivalent noise level in the city like Burdwan.

Results of computer modeling of a modular independent tubular suspension of a logging truck

The necessity of increasing the efficiency of timber trucks by improving the designs of their suspensions has been substantiated. The main disadvantages of traditional suspension structures used in modern logging trucks have been described. A promising design of a modular independent tubular torsion bar suspension for a logging truck has been proposed. The aim of the research consisted of two stages. At the first stage, a mathematical model for the functioning of the proposed torsion bar suspension has been developed. At the second stage, a computer program for a preliminary assessment of the effectiveness of the functioning of this suspension (when driving on an insufficiently equipped forest road) has been made. Time dependences of the angular positions of suspension arm fork and ends of the tubular torsion bars were obtained. The regularities of the influence of the movement speed, average height of irregularities, coefficient of dry friction on the relative spread of vertical loads and suspension indicators of vibration dispersions were revealed.

Design of a defined grain distribution brazed diamond grinding wheel for ultrasonic assisted grinding and experimental verification

Ultrasonic assisted grinding (UAG) is a promising manufacturing technology in processing hard and brittle materials, mostly due to its excellent machining performance. In UAG, improvements in grain trajectory interactions and overlapping stemming from kinematic characteristics were identified as the main reasons for reduced grinding forces and improved processing quality. However, in existing studies, the grinding wheels with disordered abrasive grain distributions and irregular grain protrusion heights were generally used. Consequently, it is difficult to control both the interactions between grain trajectories and overlapping. Aiming to solve this problem, a brazed diamond grinding wheel with defined grain distribution was proposed in this study. The grinding wheel matrix was designed using finite element analysis, while abrasive grain distribution was obtained by kinematic analysis of UAG. Finally, the grinding wheel was prepared using brazing technology and to verify its grinding performance, an electroplated grinding wheel with the identic matrix and abrasive grain size was prepared. Morphology analysis of both grinding wheels has shown that compared to the electroplated grinding wheel, the brazed one has both higher and more uniform grain protrusion height. In the next step, UAG and CG experiments were carried out using the brazed and electroplated grinding wheel. The effects of grain distribution and grinding parameters on the grinding force, force ratio, surface profile wave, and surface roughness were studied. The results have shown that in similar operating conditions the brazed grinding wheel produced smaller grinding force, force ratio, smoother ground surface, and lower surface roughness compared to the electroplated grinding wheel. Additionally, for both grinding wheels, the UAG reduced grinding force, force ratio, surface roughness, and profile wave height. However, it also caused a more extensive ultrasonic vibration effect on grinding compared to the electroplated grinding wheel; its reduction percentage in grinding force was larger, while surface roughness and average height difference for UAG were higher compared to CG.

RSOB Shorting Defect Resolution through Looping Optimization and Ball Placement at Wirebond Process

Wirebonding process is one of the most challenging assembly manufacturing process in semiconductor packaging industry. This paper discussed the wirebonding challenge and the solution to resolve the wire to die shorting on reverse stitch on ball (RSOB) and prevent irregular looping height for the substrate land grid array (LGA) device. Comprehensive parameter optimization was done particularly on the wirebond looping to ensure that no wire depression and no capillary hitting would occur wirebonding setup. Ultimately, the optimized wirebonding parameter prevented the occurrence of looping issues during the lot process. For future works, the configuration and technique could be applied on packages with similar situation.

Investigation of the influence of the process of gear honing by diamond worm honing tools on the roughness factor of gear wheels

In the presented article, a new method of finishing is considered in more detail - gear honing of cylindrical gears. Analysis of literature sources shows that the most problematic technological operation is the finishing of gear wheels and gear honing in particular. The difference between the traditional honing of cylindrical gears with disc abrasive honing and the new method of processing with diamond worm honing is shown. The main advantage of this method is that it can be implemented on milling machines. New tools are proposed - diamond worm gears and the technology of their manufacture is described. The modes of processing cylindrical gears with various diamond worm gears are given and the processing method itself is described. The gear wheels that were processed are used in hydraulic pumps and in hydraulic motors. Roughness parameters Rmax (total height of profile), Rz (irregularity height at 10 points), Rq (root mean square deviation of the assessed profile), which correspond to the Ukrainian and European DSTU ISO 4287 standard, were used as a criterion for assessing the quality of gear processing: 2012. As you know, the strength, wear resistance, durability and other parameters depend on the roughness of the working surfaces of the teeth of the gear wheels. Roughness affects the wear of contact surfaces and noise during operation when running in gears, as well as at the time of their starting. The surfaces were compared before and after treatment. Distribution curves were plotted to visualize the experimental data. When using the new processing method, the correction of defects of the previous processing methods is shown. Based on the results of the studies carried out, it can be concluded that the roughness parameters Rmax, Rz, Rq improve on average by 1.5-2 times. This method can be recommended for the finishing of cylindrical gears, as effective and not requiring new equipment, replacing the traditional methods of honing gears, which can be implemented without significant costs at most Ukrainian enterprises.

Stabilization of power output and platform motion of a floating offshore wind turbine-generator system using model predictive control based on previewed disturbances

Model predictive control of a floating offshore wind turbine-generator system, in which wave height as well as inflow wind speed is regarded as the previewed disturbances, is developed to stabilize power output and platform motion and reduce dynamic loads at mechanical and supporting components at high wind speeds. First, the internal model to predict dynamic control behaviors to previewed disturbances is identified from an aero-elastic-hydro-control coupled simulation result, in which pseudorandom binary sequence signals are added to the manipulated variables calculated in a gain-scheduling feedback controller of the generator speed to satisfy a persistently exciting condition. Second, an aero-elastic-hydro-control coupled simulation using the developed model predictive control is performed for a 5-MW floating offshore wind turbine-generator system. The identified internal model has a high prediction accuracy of the system outputs by regarding the spatial mean wind speed in the swept area of the wind turbine as a rotor effective wind speed. The simulation results under turbulent wind fields and irregular wave height variations reveal that the stabilization of the power output and platform motion and the dynamic load reduction are achieved by employing the developed model predictive control with a perfect preview of the wind speed and wave height.

Tribological researches of electroerosive processing of steel details of cars

The article considers the technology of electroerosive treatment of steel friction pairs and presents the results of experimental studies. Analysis of experimental studies has shown that an increase in the anode-cathode voltage leads to a sharp decrease in the microhardness of the surface layer. The study also allowed to determine the characteristic size of the structural elements, the height parameters of the surface roughness. The elemental composition of the initial surface of the sample made of steel 15HGN2TA differs from the composition of the coatings and surface layers of the samples modified by electroerosive treatment with different electrodes. In the mode of operation of the "anode - cathode" system on the cathode surface due to dissipative processes, a thin layer of coating of a stable modified structure is formed. It is shown that the height of surface irregularities in the areas after friction is higher than in the areas of the surface outside the friction track, which is associated with the formation on the surface of the samples of the friction transfer film. It was found that the frictional interaction of steel samples treated by electroerosion method forms a thin film on the friction surface of steel samples, which leads to a change in the topography of surfaces with increasing height of microroughnesses and structuring of the transfer film in the sliding direction. The influence of electroerosive treatment of steel surfaces on the wear resistance of the metal-polymer tribosystem was established and the optimal treatment modes were obtained: voltage U = 145-150 V, capacitor capacity C = 225-230 μF, treatment duration t = 3-4 min / cm2, providing the greatest reduction in speed wear of the polymer counterbody and recommended in the development of technological processes of electroerosive treatment.

A New Solution Based on UTD-PO Method for Multiple-Diffraction by a Series of Buildings with Irregular Height and Spacing

A new solution based on the uniform theory of diffraction-physical optics (UTD-PO) method is presented for the prediction of multiple diffractions caused by a series of buildings with irregular height and interspacing. The prediction results, obtained using the proposed solution, are compared with the available measurement data and results based on UTD slope-diffraction method to validate the accuracy. Further, the computational complexity of the proposed algorithm is compared with that of the available UTD slope-diffraction method to demonstrate its computational efficiency.

Rapid Visual Screening method for vertically irregular buildings based on Seismic Vulnerability Indicator

Seismic vulnerability assessment of a large group of buildings can prove to be extremely difficult as it requires huge amount of time and resources. Rapid Visual Screening (RVS) alleviates this problem by classifying buildings into different classes of vulnerability thereby limiting the need for detailed analysis only to a few selected vulnerability classes. RVS survey of five G+1 houses were conducted using Arya et al. method, Sinha et al. method, Jain et al. method, FEMA Level 1 and FEMA Level 2 method. The lack of details regarding irregularities resulted in the same RVS score for buildings with significantly different configurations. This renders the RVS procedure difficult to be used for comparison. This paper provides a qualitative comparison of seismic vulnerability among vertically irregular buildings in terms of mass, geometric and stiffness irregularity through Rapid Visual Screening. 3D Response spectrum analysis of reinforced concrete buildings have been done using STAAD Pro software and Seismic Vulnerability Indicator (SVI) values are calculated for comparison of seismic vulnerabilities with respect to vertical irregularities. Mass irregularity near the mid height of building or stiffness irregularity below the mid height of building is found to be more critical among the possible locations of irregularity. Elevation asymmetry above mid height is found to decrease the seismic vulnerability of a building. Presence of stiffness irregularity is found to be significantly more critical than mass or geometric irregularity.

Processing of teeth of saw blades of cotton processing machines with a stream of compressed air with abrasive particles

In the article, it is presented materials on abrasive blasting of teeth of saw blades of cotton processing machines with particles of black silicon carbide. The micro-profile of the surface, characterized by the height and pitch of irregularities, after microcutting with abrasive particles is able to intensify the process of fiber separation by activating the tank surfaces of the teeth. This machining process is also accompanied by deformation hardening of the surface layer of the teeth, leading to an increase in the wear resistance and durability of the saws.

Integrated Probabilistic Surface Roughness Assessment for Various Processing Methods

The surface texture characteristics are specified by international standards, which include dozens of parameters, basically geometrical. The probability of filling the rough surface layer with a material from the reference line and through the layer thickness is proposed as a quantitative roughness assessment. It takes account of geometrical parameters, shape, height and frequency of surface irregularities. An example is given of studying a surface with processing defects, and a comparative analysis of surface treatment methods is presented. The calculation results are summarized in a table of probabilistic characteristics of surfaces for various processing methods.