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1
Toh, C. K. "Tool life and tool wear during high-speed rough milling using alternative cutter path strategies." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 217, no. 9 (September 1, 2003): 1295–304. http://dx.doi.org/10.1243/095440503322420223.
Повний текст джерелаАнотація:
The paper is concerned with a feasibility study of tool life and tool wear when employing high depths of cut (between 10 and 20 mm) and different cutter path strategies in the high-speed milling (HSM) of hardened die/mould steel. Following a review of previous work, experimental data are presented on the peripheral milling of hardened AISI H13 steel (HRC 52) using raster, single-direction raster and offset machining strategies. Coated carbide corner-radius end mills with a diameter of 10mm were employed with a fixed cutting speed of 314m/min and a feed per tooth of 0.067mm. From the experimental results it was realized that a raster cutter path strategy (combination of up and down milling) combined with high-depth roughing achieved the lowest tool wear. The offset strategy achieved the lowest tool life at all axial depths of cut within the range investigated. The experimental results clearly show that cutter path strategies and axial depths of cut have a significant effect on the tool life and tool wear for the cutters employed.
2
Srichok, Thanatkij, Rapeepan Pitakaso, Kanchana Sethanan, Worapot Sirirak, and Parama Kwangmuang. "Combined Response Surface Method and Modified Differential Evolution for Parameter Optimization of Friction Stir Welding." Processes 8, no. 9 (September 1, 2020): 1080. http://dx.doi.org/10.3390/pr8091080.
Повний текст джерелаАнотація:
In this study, we constructed a new algorithm to determine the optimal parameters for friction stir welding including rotational speed, welding speed, axial force, tool pin profile, and tool material. The objective of welding is to maximize the ultimate tensile strength of the welded aluminum. The proposed method combines the response surface method and the modified differential evolution algorithm (RSM-MDE). RSM-MDE is a method that involves both experimental and simulation procedures. It is composed of four steps: (1) finding the number of parameters and their levels that affect the efficiency of the friction stir welding, (2) using RSM to formulate the regression model, (3) using the MDE algorithm to find the optimal parameter of the regression model obtained from (2), and (4) verifying the results obtained from step (3). The optimal parameters generated by the RSM-MDE method were a rotation speed of 1417.68 rpm, a welding speed of 60.21 mm/min, an axial force of 8.44 kN, a hexagon-tapered tool pin profile, and the SKD 11 tool material. The ultimate tensile strength obtained from this set of parameters was 294.84 MPa, which was better than that of the RSM by 1.48%.
3
Wang, Wei, and Jian Guo Yang. "A Combined Error Model for Thermal Error Compensation of Machine Tools." Advanced Materials Research 820 (September 2013): 147–50. http://dx.doi.org/10.4028/www.scientific.net/amr.820.147.
Повний текст джерелаАнотація:
In this paper, a combined error model for thermal error compensation of machine tools is presented. Through the analysis of thermal error data of machine spindle at different temperatures, the error variation law is obtained. Experiments on the axial directional spindle deformation on a CNC machine center are conducted to build and validate the proposed models. The experimental validations show that the thermal errors of the machine tool are reduced effectively after applying the error compensation approach. The combined error model performs better than the traditional time series and neural network model in terms of prediction accuracy and robustness, which means that the new model is more suitable for complex working conditions in industrial applications.
4
Tsagkir Dereli, Tountzer, Nils Schmidt, Tim Furlan, Raphael Holtermann, Dirk Biermann, and Andreas Menzel. "Simulation Based Prediction of Compliance Induced Shape Deviations in Internal Traverse Grinding." Journal of Manufacturing and Materials Processing 5, no. 2 (June 8, 2021): 60. http://dx.doi.org/10.3390/jmmp5020060.
Повний текст джерелаАнотація:
Internal traverse grinding (ITG) using electroplated cBN tools in high-speed grinding conditions is a highly efficient manufacturing process for bore machining in a single axial stroke. However, process control is difficult. Due to the axial direction of feed, changes in process normal force and thus radial deflection of the tool and workpiece spindle system, lead to deviations in the workpiece contour along the length of the bore, especially at tool exit. Simulations including this effect could provide a tool to design processes which enhance shape accuracy of components. A geometrical physically-based simulation is herein developed to model the influence of system compliance on the resulting workpiece contour. Realistic tool topographies, obtained from measurements, are combined with an FE-calibrated surrogate model for process forces and with an empirical compliance model. In quasistatic experimental investigations, the spindle deflection is determined in relation to the acting normal forces by using piezoelectric force measuring elements and eddy current sensors. In grinding tests with in-process force measurement technology and followed by measurement of the resulting workpiece contours, the simulation system is validated. The process forces and the resulting characteristic shape deviations are predicted in good qualitative accordance with the experimental results.
5
Pa, Pai Shan. "Grinding Finishing Merging Electropolishing on Hole-Wall Surfaces." Advanced Materials Research 97-101 (March 2010): 4071–74. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.4071.
Повний текст джерелаАнотація:
The current study presents a method for finishing hole-wall surfaces, superior to that obtainable by traditional boring, using a simultaneous grinding and electropolishing process. A specially designed finishing tool, that includes a nonconductive grinding wheel and an electrode is employed in the process. The form of the tool and the machining process are different from those used in electrochemical grinding (ECG). A high power electrical supply is not required with this design of finishing tool because the axial feed allows for the use of a smaller interactive area between the electrode and the hole wall surface. The experimental results show that a high current flow combined with a fast axial feed rate for the tool is an important advantage to the finishing process. The finishing effect is better with high rotational tool speeds because discharge of the electropolishing dregs and grinding cuttings becomes more efficient and this is also advantageous to the grinding finishing process. Pulsed direct current can slightly improve the electrochemical finishing effect, but machining takes longer and this raises costs. A small edge radius on the electrode also provides more than sufficient discharge and gives a better finish. We intend to make a complete evaluation of the processing parameter data so that the use of this method for hole-wall surface finishing may be extended in the future. The combined application of grinding and electropolishing is crucial to this method and the specially designed tool and the new finishing process are highly efficient and inexpensive.
6
Степанов, Михаил Сергеевич, and Марина Сергеевна Иванова. "Development of the mathematical model for the choice of the optimal cutting condition with combined axial tool." Technology audit and production reserves 4, no. 1(24) (July 23, 2015): 69. http://dx.doi.org/10.15587/2312-8372.2015.47795.
Повний текст джерела
7
Ganapathy, T., K. Lenin, and K. Pannerselvam. "Process Parameters Optimization of Friction Stir Welding in Aluminium Alloy 6063-T6 by Taguchi Method." Applied Mechanics and Materials 867 (July 2017): 97–104. http://dx.doi.org/10.4028/www.scientific.net/amm.867.97.
Повний текст джерелаАнотація:
This paper deals with the effective application of friction stir welding similar to butt joining technique.AL6063 T-6 alloys prepared in 125x 100 x 7mm thickness plate and FSW tool setup were H13 of diameter 25mm rotary tool with straight cylindrical pin profile. The maximum strength was considered for selection of combined process parameter. The process parameters were optimized using Taguchi method. The Rotational speed, welding speed, and axial speed are the main process parameter which taken into our consideration. The optimum process parameters are determined with reference to tensile strength of the joint. From the experiments, it was found the effects of welding parameter are the axial force is highest substantial parameter to determining the tensile strength of the joint. The paper which revealed the optimal values of process parameter are to acquire a maximum tensile strength of friction stir welded AL6063-T6 plates is 101.6Mpa with the combination level of rotational speed, welding speed and axial force are found to be 1100 RPM, 60 mm/min and 12.5 KN. validation test was carried out and results were nearer to the optimized results confirmed by the optimum results.
8
Zhu, Lin, and De Ming Xiao. "The Monitoring and Analysis on the State of Deep Hole Drilling Based on Multi-Sensor Combined Detection Technology." Key Engineering Materials 392-394 (October 2008): 645–49. http://dx.doi.org/10.4028/www.scientific.net/kem.392-394.645.
Повний текст джерелаАнотація:
A kind of multi-sensor detection device was designed by using multi-sensor combined detection technology. The signal of axial force, torque and vibration in vertical and horizontal direction in deep hole drilling were collected respectively, and delivered to computer for processing by using data collection device. And then the feature parameters that can reflect the cutting tool wear were abstracted by means of the method of time-domain analysis and frequency-domain analysis. Finally, the state was classified by mode identification method and the judgment samples are also obtained.
9
Variola, Angela, Maria Elisabetta Zanolin, Giovanni Cipriano, Pierluigi Macchioni, Federica Martinis, Annalisa Pasetti, Mario Grassi, et al. "The IBIS-Q [IBd Identification of Spondyloarthritis Questionnaire]: A Novel Tool to Detect Both Axial and Peripheral Arthritis in Inflammatory Bowel Disease Patients." Journal of Crohn's and Colitis 14, no. 12 (May 15, 2020): 1680–86. http://dx.doi.org/10.1093/ecco-jcc/jjaa096.
Повний текст джерелаАнотація:
Abstract Background and Aims Both peripheral and axial spondyloarthritis [SpA] occur in inflammatory bowel disease [IBD] and represent the commonest extra-intestinal manifestation. We aimed to develop an easy and quick questionnaire through psychometric analysis, to identify peripheral and axial SpA in IBD patients within an integrated combined multidisciplinary rheumatological-gastroenterology clinic. Methods Initially, SpA-IBD experts generated a 42-item list covering SpA manifestations including spinal, articular, and entheseal involvement. The new questionnaire was administered before routine clinical IBD assessment. On the same day, rheumatological assessment, blinded to both history and questionnaire results, was performed to explore the presence of the Assessment of SpondyloArthritis International Society [ASAS] criteria for SpA, diagnostic criteria for fibromyalgia [FM], and non-specific low back pain [NSLB]. Factorial analysis of questionnaire items to identify the main factors—receiver operating characteristic [ROC] curves for sensitivity/specificity and Youden index for cut-off—were performed. Results Of the 181 consecutive patients, 56 met the ASAS SpA criteria [prevalence of 30%] with 10 new cases detected [5.5%: seven peripheral and three axial]. Through the psychometric and factorial analysis, we selected 14 items for the final questionnaire [named IBIS-Q]. The IBIS-Q was quick and performed well for detection of axial SpA and peripheral SpA (area under the curve [AUC] 0.88 with 95% confidence interval [CI] 0.830.93). A cut-off of three positive questions had a sensitivity 93% and specificity 77% for SpA patient identification. Conclusions The IBIS-Q is a useful and simple tool to use in IBD clinics for SpA detection, with a good statistical performance. Further studies are needed to validate it.
10
Benuzzi, E., and F. Soavi. "A Theoretical Investigation for High-Speed Cold Forging of Short Metal Cylinders Between Two Large Elastic Tools." Journal of Engineering for Industry 107, no. 3 (August 1, 1985): 266–74. http://dx.doi.org/10.1115/1.3185997.
Повний текст джерелаАнотація:
A theoretical solution is obtained for the pressure distribution at the die-material interface during a high-speed cold forging operation of a short metal cylinder workpiece, taking into account the elastic deformation of the tool considered as a half-space. The influence of the combined effects of axial and radial inertia forces, impact velocity, frictional conditions, plastic resistance of material, and radius to height ratio on pressure distribution and die surface deflection, are numerically evaluated. An illustrative example of dynamic compression with a gravity drop hammer is presented.
11
O’Neill, Macdarragh, and Ted J. Vaughan. "High-Speed Cutting of Synthetic Trabecular Bone—A Combined Experimental–Computational Investigation." Applied Mechanics 2, no. 3 (September 20, 2021): 650–65. http://dx.doi.org/10.3390/applmech2030037.
Повний текст джерелаАнотація:
Orthopaedic surgical cutting instruments are required to generate sufficient forces to penetrate bone tissue while minimising the risk of thermal and mechanical damage to the surrounding environment. This study presents a combined experimental–computational approach to determine relationships between key cutting parameters and overall cutting performance of a polyurethane-based synthetic trabecular bone analogue under orthogonal cutting conditions. An experimental model of orthogonal cutting was developed, whereby an adaptable cutting tool fixture driven by a servo-hydraulic uniaxial test machine was used to carry out cutting tests on Sawbone® trabecular bone analogues. A computational model of the orthogonal cutting process was developed using Abaqus/Explicit, whereby an Isotropic Hardening Crushable Foam elastic-plastic model was used to capture the complex post-yield behaviour of the synthetic trabecular bone. It was found that lower tool rake angles resulted in the formation of larger discontinuous chips and higher cutting forces, while higher rake angles tended to lead to more continuous chip formation and lower cutting forces. The computational modelling framework provided captured features of both chip formation and axial cutting forces over a wide range of cutting parameters when compared with experimental observations. This experimentally based computational modelling framework for orthogonal cutting of trabecular bone analogues has the potential to be applied to more complex three-dimensional cutting processes in the future.
12
Jiang, Liu, Guo Zhiping, Miao Shujing, He Xiangxin, and Zhu Xinyu. "Research on aerodynamic characteristics of two-stage axial micro air turbine spindle for small parts machining." Advances in Mechanical Engineering 12, no. 12 (December 2020): 168781402098437. http://dx.doi.org/10.1177/1687814020984373.
Повний текст джерелаАнотація:
In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.
13
Deng, Congying, Wei Zhou, Kai Yang, Zhiyu Huang, and Qian Tang. "Robust Chatter Stability Prediction of the Milling Process considering Uncertain Machining Positions." Mathematical Problems in Engineering 2020 (October 12, 2020): 1–15. http://dx.doi.org/10.1155/2020/1398957.
Повний текст джерелаАнотація:
Milling stability is a function of the tool point frequency response functions (FRFs), which vary with the movements of the moving parts within the whole machine tool work volume. The position-dependent tool point FRFs result in uncertain prediction of the stability lobe diagram (SLD) for chatter-free machining parameter selection. Taking the variations of modal parameters to represent the variations of tool point FRFs, this paper introduces the edge theorem to predict the robust milling chatter stability. The application of the edge theorem requires the minimum and maximum modal parameters within the machining space defined by the machining position and machining allowance information. Then, radial basis function artificial neural networks (RBFANNs) are used to predict the position-dependent modal parameters in X and Y directions based on the sample information of machining positions and related modal parameters at the tool point. Moreover, sample machining spaces are determined based on the aforementioned sample positions, and the trained RBFANNs are used to obtain corresponding sample extreme modal parameters. On this basis, RBFANNs for predicting the position and machining allowance-dependent extreme modal parameters can also be trained, and they are combined with the edge theorem and zero exclusion condition to calculate robust pairs of the spindle speed (n) and limiting axial cutting depth (aplim) and then plot the robust SLD (RSLD). A case study was performed on a real three-axial vertical machining center, and the plotted RSLD considering position variations was compared with the traditional SLD. Results of the chatter tests show that the RSLD can provide more reliable (ap, n) pairs to guarantee the milling stability, validating the feasibility of the proposed robust milling chatter stability prediction method.
14
Campa, Francisco Javier, Luis Norberto López de Lacalle, S. Herranz, Aitzol Lamikiz, and A. Rivero. "Avoiding Instability on the Milling of Parts with Thin Features." Materials Science Forum 526 (October 2006): 37–42. http://dx.doi.org/10.4028/www.scientific.net/msf.526.37.
Повний текст джерелаАнотація:
In this paper, a 3D dynamic model for the prediction of the stability lobes of high speed milling is presented, considering the combined flexibility of both tool and workpiece. The main aim is to avoid chatter vibrations on the finish milling of aeronautical parts, which include thin walls and thin floors. In this way the use of complex fixtures is eliminated. Hence, an accurate selection of both axial depth of cut and spindle speed can be accomplished. The model has been validated by means of a test device that simulates the behaviour of a thin floor.
15
Majic, Ivan, and Elek Pafka. "AwaP-IC—An Open-Source GIS Tool for Measuring Walkable Access." Urban Science 3, no. 2 (April 29, 2019): 48. http://dx.doi.org/10.3390/urbansci3020048.
Повний текст джерелаАнотація:
Within the broad field of walkability research, a key area of focus has been the relationship between urban form and capacities for walking. Measures of walkable access can be grouped into two key types: permeability measures that quantify the ease of movement through an urban fabric, and catchment measures, quantifying the potential to reach destinations within walking distance. Of numerous street network measures in use, it has been shown that many are poor proxies of permeability and catchment. Instead, two new measures have been proposed: the area-weighted average perimeter (AwaP) and interface catchment (IC), that, combined, better capture the capacities of urban morphologies to enable and attract pedestrian movement. In this paper, we present the QGIS tool AwaP-IC, developed to overcome the difficulty of computing these measures. Unlike GIS tools based on models that abstract streets to axial lines, by employing new algorithms and spatial computation techniques, AwaP-IC analyses actual urban morphologies, based on cadastral maps delineating public and private land. This can empower a new stream of urban morphological studies with the computational power of GIS. As an open-source tool, it can be further developed for use in urban mapping and to streamline the analysis of large datasets.
16
Jing, Lu Lu, Qing Long An, and Ming Chen. "Study on Burr Formation in Face Milling of Stainless Steel with Chamfered Cutting Tool." Advanced Materials Research 53-54 (July 2008): 83–88. http://dx.doi.org/10.4028/www.scientific.net/amr.53-54.83.
Повний текст джерелаАнотація:
Due to the properties such as high strength and high toughness, burr was commonly produced in the machining of stainless steel 1Cr18Ni9Ti, especially when a chamfered cutting tool was used. This study investigated the effects of chamfering geometry of cutting edge and machining parameters on burr formation and presented active control methods to minimize burr size on the exit end based on the experimental research in milling of 1Cr18Ni9Ti. Experiments of face milling with various cutting edge geometric features were conducted. Maximum height and thickness of exit burr and exit side burr were measured. As a result, a proper chamfering geometry that combined the advantages of enhancing the cutting edge strength and obtaining favorable burr types was presented. The experimental results also showed that a relatively high cutting speed was helpful in reducing burr formation; proper medium feed rate and axial depth were favorable for the minimization of burr size. This research is beneficial for precise machining of stainless steel.
17
Wiggert, D. C., F. J. Hatfield, and S. Stuckenbruck. "Analysis of Liquid and Structural Transients in Piping by the Method of Characteristics." Journal of Fluids Engineering 109, no. 2 (June 1, 1987): 161–65. http://dx.doi.org/10.1115/1.3242638.
Повний текст джерелаАнотація:
Since liquid-filled piping systems are composed of slender elements, their transient behavior can be described as one-dimensional wave phenomena. Seven wave components are identified: coupled axial compression of liquid and pipe material; coupled transverse shear and bending of the pipe elements in two principal directions; and torsion of the pipe wall. Utilizing the method of characteristics, the combined system of difference equations for pipe elements and the pipe junction boundary conditions comprise a general mathematical tool for predicting the liquid pressure and pipe stress responses to transient excitation of either liquid or piping. The complexity of fluid-structure interaction that can take place is demonstrated.
18
Quaranta, Erika, and Malcolm Smith. "Design of axial flow fans for reduced noise and improved efficiency." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 3 (August 1, 2021): 3649–62. http://dx.doi.org/10.3397/in-2021-2481.
Повний текст джерелаАнотація:
Axial flow fans are used in a wide variety of applications, from cooling systems for electronics to ventilation in buildings. Whatever the application, there will be competing design constraints which make it difficult to achieve the required pressure-flow performance characteristic, within a specified space envelope, whilst meeting a target aerodynamic efficiency and noise level. This paper describes a design methodology for optimizing aerodynamic performance and noise. It is based on use of a semi-analytic 2-D design tool for preliminary predictions and design, combined with a 3-D numerical CFD analysis to visualize the flow. Both models can be extended to the design of multi-stage systems. The 2-D model predicts the flow velocity at the trailing edge of the blades for each point on the fan performance curve, which is then used to estimate self-noise characteristics of the rotor using a classical model of airfoil trailing edge noise. The CFD analysis provides detailed validation of assumed airfoil characteristics, including the effect of 3D design features such as blade sweep, and confirms the flow and aerodynamic efficiency predictions; it can also used to estimate parameters such as turbulence intensity that is a key driver for the noise level.
19
Martirossyan, Armen, and Yan Xiao. "Flexural-Shear Behavior of High-Strength Concrete Short Columns." Earthquake Spectra 17, no. 4 (November 2001): 679–95. http://dx.doi.org/10.1193/1.1423656.
Повний текст джерелаАнотація:
This paper discusses the seismic performance of high-strength concrete columns. The research is a part of an ongoing comprehensive experimental program to investigate seismic design methods of high-strength concrete structures. The first stage of the program involved testing of fifteen high-strength concrete stub columns under concentric axial compression. The concrete compressive strength was about 69 MPa (10,000 psi). In addition, a large database including eighty-six similar tests conducted by other researchers was constructed, and stress-strain behavior of high-strength concrete was investigated. Based on the analysis, a stress-strain relationship for high-strength concrete columns was proposed. Secondly, six 1/3-1/2 scale high-strength concrete short columns were tested under combined axial load and cyclic shear, with double curvature condition. The primary experimental parameters included axial load ratio, longitudinal reinforcement ratio, and volumetric ratio of transverse reinforcement. The proposed stress-strain relationship was used in the analysis of the lateral force–displacement relationship for high-strength concrete columns. Moment-curvature analysis, based on proposed equivalent stress block approach, as well as plastic hinge mechanism, has been incorporated in this analytical tool. The analytical results agreed well with the primary load-deflection envelopes obtained from the tests.
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Cassese, Paolino, Costantino Menna, Antonio Occhiuzzi, and Domenico Asprone. "Experimental Behavior of Existing RC Columns Strengthened with HPFRC Jacket under Concentric and Eccentric Compressive Load." Buildings 11, no. 11 (November 6, 2021): 521. http://dx.doi.org/10.3390/buildings11110521.
Повний текст джерелаАнотація:
Reinforced concrete (RC) structures built before the 1970 represent a large portion of the existing European buildings stock. Their obsolescence in terms of design criteria, materials, and functionality is becoming a critical issue for guaranteeing adequate compliance with current structural codes. Recently, a new jacketing system based on the use of high-performance fiber-reinforced concrete (HPFRC) has been introduced for strengthening existing RC building members. Despite the promising aspects of the HPFRC jacketing technique, currently, a comprehensive and systematic technical framework for its implementation is still missing. In this paper, the experimental performance of RC columns strengthened with the HPFRC jacket subjected to pure axial load and combined axial load-bending moment uncoupled from shear is investigated. The test outcomes confirmed a significant improvement of the structural performance for the strengthened columns, especially for higher values of eccentricity. Finally, a standard-based practice-oriented analytical tool for designing retrofit interventions using the HPFRC jacket is proposed. The comparison between the calculated and experimental results revealed a satisfactory prediction capability.
21
Masud, M. A., Md Rabiul Islam, Md Rasel Sheikh, and Mahmud Md Alam. "Stable solution zone for fluid flow through curved pipe with circular cross-section." Journal of Naval Architecture and Marine Engineering 7, no. 1 (February 10, 2011): 19–26. http://dx.doi.org/10.3329/jname.v7i1.3630.
Повний текст джерелаАнотація:
Numerical study is performed to examine numerically the stable solution for the incompressible viscous steady flow through a curved pipe with circular cross-section. Also the combined effects of high Dean Number Dn and curvature δ on the flow are investigated. Spectral method is applied as a main tool for the numerical technique; where, Fourier series, Chebyshev polynomials, Collocation methods, and Iteration method are used as secondary tools. The flow patterns have been shown graphically for large Dean Numbers and a wide range of curvature, 0.01≤δ≤0.9.Two vortex solutions have been found for secondary flow. Axial velocity has been found to increase with the increase of Dean number and decrease with the increase of curvature. For high Dean number and low curvature almost all the fluid particles leave the inner half of the cross-section. The stable solution zone increases with the increase of curvature up to a certain limit, then decrease.DOI: 10.3329/jname.v7i1.3630
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Portillo, Karina, and Josep Morera. "Combined Pulmonary Fibrosis and Emphysema Syndrome: A New Phenotype within the Spectrum of Smoking-Related Interstitial Lung Disease." Pulmonary Medicine 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/867870.
Повний текст джерелаАнотація:
Combined pulmonary fibrosis and emphysema (CPFE) is a recently defined syndrome, in which centrilobular and/or paraseptal emphysemas in upper lung zones coexist with pulmonary fibrosis in lower lobes in individuals. These patients have a characteristic lung function profile, with unexpected subnormal dynamic and static lung volumes, contrasting with a significant reduction of carbon monoxide transfer (DLco) and exercise hypoxemia. Pulmonary hypertension is highly prevalent in CPFE and is the leading determinant of death. Tobacco smoking has been proposed as the main factor in its etiology, though the pathophysiology and its natural history remain to be determined. High-resolution computed axial tomography is the mandatory tool to confirm the diagnosis. Currently, there is no consensus about its treatment since those published to date on this issue are limited to well-characterised series of cases; hence, a better understanding of this entity may help in the development of future therapeutic approaches.
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Trzepieciński, Tomasz, Marcin Szpunar, and Robert Ostrowski. "Split-Plot I-Optimal Design Optimisation of Combined Oil-Based and Friction Stir Rotation-Assisted Heating in SPIF of Ti-6Al-4V Titanium Alloy Sheet under Variable Oil Pressure." Metals 12, no. 1 (January 7, 2022): 113. http://dx.doi.org/10.3390/met12010113.
Повний текст джерелаАнотація:
The aim of this paper is to determine the optimal input parameters for the process in order to ensure the maximum formable wall angle is obtained in a conical frustum with a varying wall angle fabricated using Single Point Incremental Forming (SPIF). The test material was 0.8-mm-thick Ti-6Al-4V titanium alloy sheets, and the test used a tungsten carbide tool with a rounded tip with a radius of 4 mm. Complete workpieces were heated using hot oil with a temperature of about 200 °C, and in addition, the high rotation speed of the forming tool generated an amount of friction heat. The input parameters were tool rotational speed, feed rate, step size, and tool rotation direction. Various oil pressures were used to improve both the accuracy of the components formed and the friction heating process. On the basis of calculations performed by means of the response surface methodology, split-plot I-optimal design responses were obtained by means of polynomial regression models. Models were fitted using REstricted Maximum Likelihood (REML), and p-values are derived using the Kenward–Roger approximation. Observation of the fracture surface of Ti-6Al-4V drawpieces showed that the destruction is as a result of ductile fracture mode. Tool rotational speed and step size are the most significant factors that affect the axial force, followed by feed rate. It was also found that step size is the most significant factor that affects the in-plane SPIF force.
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Li, Junli, Weiwei Yu, Qinglong An, and Ming Chen. "A modeling and prediction method for plunge cutting force considering the small displacement of cutting layer." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 234, no. 11 (June 9, 2020): 1369–78. http://dx.doi.org/10.1177/0954405420921739.
Повний текст джерелаАнотація:
In the process of plunge milling, the main cutting force is along the axial direction, and usually, the machining system has good axial rigidity, so it can withstand large cutting loads. This characteristic makes plunge milling particularly suitable for high-efficiency rough machining and semi-finishing of difficult-to-cut materials. The cutting force in the plunge milling process is usually large, and when the process parameters are not selected properly, the plunge milling is prone to the back-off phenomenon. In view of the characteristics of large cutting force and high cutting temperature in Inconel 718 plunge milling process, considering the small displacement of the actual tool tip caused by cutting force and cutting vibration, this article establishes a plunge milling force model based on the combination of analytical method and three-dimensional finite element method. The micro-displacement caused by vibration is obtained through dynamic modeling and modal test methods. Combined with the macro-displacement of cuter back-off under the action of the cutting force during the single-tooth run-in and run-out process, the modified cutting layer parameters are obtained, and optimized cutting force of plunge milling is obtained.
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Sohail, Muhammad Umer, Hossein Raza Hamdani, Asad Islam, Khalid Parvez, Abdul Munem Khan, Usman Allauddin, Muhammad Khurram, and Hassan Elahi. "Prediction of Non-Uniform Distorted Flows, Effects on Transonic Compressor Using CFD, Regression Analysis and Artificial Neural Networks." Applied Sciences 11, no. 8 (April 20, 2021): 3706. http://dx.doi.org/10.3390/app11083706.
Повний текст джерелаАнотація:
Non-uniform inlet flows frequently occur in aircrafts and result in chronological distortions of total temperature and total pressure at the engine inlet. Distorted inlet flow operation of the axial compressor deteriorates aerodynamic performance, which reduces the stall margin and increases blade stress levels, which in turn causes compressor failure. Deep learning is an efficient approach to predict catastrophic compressor failure, and its stability for better performance at minimum computational cost and time. The current research focuses on the development of a transonic compressor instability prediction tool for the comprehensive modeling of axial compressor dynamics. A novel predictive approach founded by an extensive CFD-based dataset for supervised learning has been implemented to predict compressor performance and behavior at different ambient temperatures and flow conditions. Artificial Neural Network-based results accurately predict compressor performance parameters by minimizing the Root Mean Square Error (RMSE) loss function. Computational results show that, as compared to the tip radial pressure distortion, hub radial pressure distortion has improved the stability range of the compressor. Furthermore, the combined effect of pressure distortion with the bulk flow has a qualitative and deteriorator effect on the compressor.
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Wang, Feifei, Zhuoran Ma, Yeteng Zhong, Felix Salazar, Chun Xu, Fuqiang Ren, Liangqiong Qu, Anna M. Wu, and Hongjie Dai. "In vivo NIR-II structured-illumination light-sheet microscopy." Proceedings of the National Academy of Sciences 118, no. 6 (February 1, 2021): e2023888118. http://dx.doi.org/10.1073/pnas.2023888118.
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Noninvasive optical imaging with deep tissue penetration depth and high spatiotemporal resolution is important to longitudinally studying the biology at the single-cell level in live mammals, but has been challenging due to light scattering. Here, we developed near-infrared II (NIR-II) (1,000 to 1,700 nm) structured-illumination light-sheet microscopy (NIR-II SIM) with ultralong excitation and emission wavelengths up to ∼1,540 and ∼1,700 nm, respectively, suppressing light scattering to afford large volumetric three-dimensional (3D) imaging of tissues with deep-axial penetration depths. Integrating structured illumination into NIR-II light-sheet microscopy further diminished background and improved spatial resolution by approximately twofold. In vivo oblique NIR-II SIM was performed noninvasively for 3D volumetric multiplexed molecular imaging of the CT26 tumor microenvironment in mice, longitudinally mapping out CD4, CD8, and OX40 at the single-cell level in response to immunotherapy by cytosine-phosphate-guanine (CpG), a Toll-like receptor 9 (TLR-9) agonist combined with OX40 antibody treatment. NIR-II SIM affords an additional tool for noninvasive volumetric molecular imaging of immune cells in live mammals.
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Del Guerra, Alberto, Salleh Ahmad, Mihai Avram, Nicola Belcari, Arne Berneking, Laura Biagi, Maria Giuseppina Bisogni, et al. "TRIMAGE: A dedicated trimodality (PET/MR/EEG) imaging tool for schizophrenia." European Psychiatry 50 (April 2018): 7–20. http://dx.doi.org/10.1016/j.eurpsy.2017.11.007.
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AbstractSimultaneous PET/MR/EEG (Positron Emission Tomography – Magnetic Resonance – Electroencephalography), a new tool for the investigation of neuronal networks in the human brain, is presented here within the framework of the European Union Project TRIMAGE. The trimodal, cost-effective PET/MR/EEG imaging tool makes use of cutting edge technology both in PET and in MR fields. A novel type of magnet (1.5T, non-cryogenic) has been built together with a PET scanner that makes use of the most advanced photodetectors (i.e., SiPM matrices), scintillators matrices (LYSO) and digital electronics. The combined PET/MR/EEG system is dedicated to brain imaging and has an inner diameter of 260 mm and an axial Field-of-View of 160 mm.It enables the acquisition and assessment of molecular metabolic information with high spatial and temporal resolution in a given brain simultaneously. The dopaminergic system and the glutamatergic system in schizophrenic patients are investigated via PET, the same physiological/pathophysiological conditions with regard to functional connectivity, via fMRI, and its electrophysiological signature via EEG. In addition to basic neuroscience questions addressing neurovascular-metabolic coupling, this new methodology lays the foundation for individual physiological and pathological fingerprints for a wide research field addressing healthy aging, gender effects, plasticity and different psychiatric and neurological diseases.The preliminary performances of two components of the imaging tool (PET and MR) are discussed. Initial results of the search of possible candidates for suitable schizophrenia biomarkers are also presented as obtained with PET/MR systems available to the collaboration.
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Zhao, Xue You, Zhi Chao Lang, Chun Feng Mao, and Wei Na Zhang. "Analysis on Crack Propagation of Roll by the Finite-Element." Advanced Materials Research 591-593 (November 2012): 553–56. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.553.
Повний текст джерелаАнотація:
Roller is a main tool and consumption parts for steel rolling. With analysis test on the fatigue property of roller, the development incentives of crack propagation were realized, the service life of roller was improved and the cost of Production was reduced in a large extent. Roller is a circular column, which do fixed-axis rotation under combined action of roll pressure, bearing reaction, Support roller reaction force and torsion. The failure types of roll such as flaking, fracture and crack. Simulate and analysis on damage of the roller crack by the fracture mechanics of knowledge and ANSYS, which shown that compressive was large with the ring and axial and compressive was small with the radial direction, so the compressive of radial direction the analysis had little effect on roll surface.
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Macin, Gulay, Burak Tasci, Irem Tasci, Oliver Faust, Prabal Datta Barua, Sengul Dogan, Turker Tuncer, Ru-San Tan, and U. Rajendra Acharya. "An Accurate Multiple Sclerosis Detection Model Based on Exemplar Multiple Parameters Local Phase Quantization: ExMPLPQ." Applied Sciences 12, no. 10 (May 12, 2022): 4920. http://dx.doi.org/10.3390/app12104920.
Повний текст джерелаАнотація:
Multiple sclerosis (MS) is a chronic demyelinating condition characterized by plaques in the white matter of the central nervous system that can be detected using magnetic resonance imaging (MRI). Many deep learning models for automated MS detection based on MRI have been presented in the literature. We developed a computationally lightweight machine learning model for MS diagnosis using a novel handcrafted feature engineering approach. The study dataset comprised axial and sagittal brain MRI images that were prospectively acquired from 72 MS and 59 healthy subjects who attended the Ozal University Medical Faculty in 2021. The dataset was divided into three study subsets: axial images only (n = 1652), sagittal images only (n = 1775), and combined axial and sagittal images (n = 3427) of both MS and healthy classes. All images were resized to 224 × 224. Subsequently, the features were generated with a fixed-size patch-based (exemplar) feature extraction model based on local phase quantization (LPQ) with three-parameter settings. The resulting exemplar multiple parameters LPQ (ExMPLPQ) features were concatenated to form a large final feature vector. The top discriminative features were selected using iterative neighborhood component analysis (INCA). Finally, a k-nearest neighbor (kNN) algorithm, Fine kNN, was deployed to perform binary classification of the brain images into MS vs. healthy classes. The ExMPLPQ-based model attained 98.37%, 97.75%, and 98.22% binary classification accuracy rates for axial, sagittal, and hybrid datasets, respectively, using Fine kNN with 10-fold cross-validation. Furthermore, our model outperformed 19 established pre-trained deep learning models that were trained and tested with the same data. Unlike deep models, the ExMPLPQ-based model is computationally lightweight yet highly accurate. It has the potential to be implemented as an automated diagnostic tool to screen brain MRIs for white matter lesions in suspected MS patients.
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McCrory, Bernadette, Alex Cuevas, Jacob Alborano, Bethany R. Lowndes, and M. Susan Hallbeck. "Optimizing Surgical Tools for Single-Site Surgery: A Cadaver-Based Design Study." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 63, no. 1 (November 2019): 1249–53. http://dx.doi.org/10.1177/1071181319631063.
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Background: Laparoendoscopic single site surgery (LESS) is feasible for more complex procedure types, but the technical challenges and learning curve posed by LESS makes traditional multi-incision laparoscopy still the preferred technique. The aims of this study were to understand the restricted mobility and positional requirements of these more complex procedures and to generate innovative instrument designs to overcome these restrictions. Methods: A two-phase study was conducted where three lightly-embalmed (fresh tissue) cadavers were utilized to estimate in vivo mobility restriction and positional requirements. These data were combined to quantifying instrument force and positional requirements to develop a novel design for a LESS-specific grasper. Results: The LESS-specific has an ergonomic curved axial handle and locking mechanism that enables surgeons to relax their grip without the grasper releasing. Conclusion: Further design adaptations are needed to optimize the size, angles, and curvature of the tool, as well as to add two points of articulation for rapid intracorporeal adjustment.
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Buonocore, Giuseppe, Antonio Gesualdo, Antonino Iannuzzo, Mariano Modano, Michela Monaco, and Maria Teresa Savino. "M-N Interaction Effect on the Frames Failure Mechanisms." Applied Mechanics and Materials 847 (July 2016): 248–56. http://dx.doi.org/10.4028/www.scientific.net/amm.847.248.
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The collapse factor is a significant parameter in the framework of the safety assessment and economical design of ductile structures. This fact draws attention to the necessity of a careful assessment of the limit analysis approaches. The kinematics in these structures arises in fact from the actual rotation of the plastic hinges under axial force and bending moment. It can be shown that it is possible to obtain a reliable tool capable of competing with computationally expensive methodologies. The application of the methods of limit analysis involves a simplified and idealised model of the structure and, notwithstanding the fact that hundreds of papers have been devoted to the topic, some consequences of apparently unimportant simplifications still seem to have not been properly and firmly highlighted. This paper investigates the ultimate load and collapse modes of steel frames under combined vertical and horizontal forces through limit analysis.
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Xu, Xu Song, and Zhi Ying Sun. "Study on Small-Diameter Deep–Hole Vibratory Drilling of Difficult-to-Cut Materials." Advanced Materials Research 328-330 (September 2011): 595–99. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.595.
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To solve the problem of drilling small-diameter deep-hole on difficult-to-cut materials, a kind of DF system combined with low frequency axial vibratory drilling was used. Its vibratory frequency was controlled by a frequency converter and could be adjusted continuously on-line. An inner chip removal deep-hole bit with dimension Φ8.95×500mm was developed and the material of the cutting tip was carbide alloy. Then, the drilling experiment of small-diameter deep-hole on the difficult-to-cut materials 1Cr11Ni4NMo was done. It can be found in the experiment that the chip remove was smooth, the cutting force was little, the cutting tool wear was light, the process of drilling was stable, and many factors of interfering roughness could be canceled or lightened effectively. The results show that DF vibratory drilling system can improve the machining precision and increase efficiency.
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Chen, C. M., H. L. Chang, and C. Y. Lee. "The Influence of Corrosion on the Anti-Loosening Performance of a Precision Locknut Subjected to Rotation and Periodic Impact." Journal of Mechanics 36, no. 3 (December 10, 2019): 295–303. http://dx.doi.org/10.1017/jmech.2019.49.
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ABSTRACTThe influence of combined corrosion and vibration to the anti-loosening performance of a precision locknut used in a machine tool is investigated. Firstly, the locknut was submerged in 5% NaCl solution according to ASTM B895 standard for corrosion testing. The locknuts, after submerged in 1-hr, 2-hr and 4-hr periods, respectively, were then installed on the rotating spindle in a vertical dynamic impact tester for performing anti-loosening test. The initial installed pretension was 9800 N and the spindle was rotating in a constant speed of 1000 rpm. Turmogrease Li 802 EP lubricant was used on the contact surface between spindle thread and locknut. The set screws on the locknut were tightened sequentially and evenly in three-stage of torque: 1.96 N-m, 3.92 N-m and 5.88 N-m. Its real-time pretension variation with the periodic transverse impact and its final loosening torque were measured. Accordingly, the axial force ratio and anti-loosening torque ratio were calculated and discussed. It was found that corrosion treatment had similar influence on both the axial force ratio and the anti-loosening torque ratio. More corrosion on the locknut with longer submersion in NaCl solution deteriorated its anti-loosening characteristics. The result could serve as the reference for evaluating the fastening performance of precision locknut and guide the design and manufacturing for the application improvement.
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Mesquita, E., P. Antunes, A. A. Henriques, A. Arêde, P. S. André, and H. Varum. "Structural reliability assessment based on optical monitoring system: case study." Revista IBRACON de Estruturas e Materiais 9, no. 2 (April 2016): 297–305. http://dx.doi.org/10.1590/s1983-41952016000200009.
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ABSTRACT Optical systems are recognized to be an important tool for structural health monitoring, especially for real time safety assessment, due to simplified system configuration and low cost when compared to regular systems, namely electrical systems. This work aims to present a case study on structural health monitoring focused on reliability assessment and applying data collected by a simplified optical sensing system. This way, an elevated reinforced concrete water reservoir was instrumented with a bi-axial optical accelerometer and monitored since January 2014. Taking into account acceleration data, the natural frequencies and relative displacements were estimated. The reliability analysis was performed based on generalized extreme values distribution (GEV) and the results were employed to build a forecast of the reliability of the water elevated reservoir for the next 100 years. The results showed that the optical system combined with GEV analysis, implemented in this experimental work, can provide adequate data for structural reliability assessment.
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Knapp, Helmut F., Frank A. Schabert, and Andreas Engel. "Scanning farfield and scanning nearfield probe microscopy of catalase platelets." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 628–29. http://dx.doi.org/10.1017/s0424820100148976.
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High resolution (sub nm) and direct height information obtained through scanning probe microscopy (SPM) (such as from the STM and AFM) establishes SPM as a valuable tool for the investigation of biological samples. Unfortunately SPM allows only regions of a few μm to be scanned at high speed. For biological applications this is a disadvantage, because most samples will be only of the μm size and scattered across the much larger substrate. To make SPM investigation of biological samples less tedious, we combined a STM (or alternatively an AFM) with an inverted confocal scanning laser microscope (CSLM), with a lateral and axial resolution of 200 nm and 400 nm, respectively. This enables to locate areas of interest on the substrate and position the tip of the STM. STM tips used are electro-chemically etched from Au to routinely attain tip radii in the 5 nm range. Catalase platelets were chosen as a sample, because of their established two different lattice repeats (17.5 nm and 6.8 nm).
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Maximov, JT, GV Duncheva, IM Amudjev, AP Anchev, and N. Ganev. "A new approach for pre-stressing of rail-end-bolt holes." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 12 (February 4, 2016): 2275–83. http://dx.doi.org/10.1177/0954406216630003.
Повний текст джерелаАнотація:
Bolted joint railroad is the subject matter of this paper. Rail joint elements are subjected to cyclic and impact loads as a result of the passage of trains, which causes the origination and growth of fatigue cracks occurring, in most cases, around the bolt holes. Fatigue failure around rail-end-bolt holes is particularly dangerous because it leads to derailment of trains and, consequently, to inevitable accidents. Moreover, the cracking at rail-ends, which starts from bolt hole surface, causes premature rails replacement. The presence of residual compressive hoop stresses around the bolted holes, which is achieved by prestressing of these holes, extends the fatigue life of bolted joint railroads. This article presents an innovative technology for pre-stressing of rail-end-bolt holes, implemented on a vertical machining centre of Revolver vertical (RV) type. Two consecutive operations are involved in the manufacturing technology process: formation of the hole by drilling, reaming and making of a chamfer through a new combined cutting tool; cold hole working by spherical motion cold working through a new tool equipment, which minimizes the axial force on the reverse stroke. The new technology introduces beneficial residual compressive stresses around the bolted holes thereby preventing the fatigue cracks growth and increasing the fatigue life of these openings.
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Harati, Hadi, Fatemeh Nooshinfard, Alireza Isfandyari-Moghaddam, Fahimeh Babalhavaeji, and Nadjla Hariri. "Factors affecting the unplanned use behavior of academic libraries users." Aslib Journal of Information Management 71, no. 2 (March 18, 2019): 138–54. http://dx.doi.org/10.1108/ajim-04-2018-0092.
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Purpose The purpose of this paper is to identify and design the axial coding pattern of the factors affecting the unplanned use behavior of users of the academic libraries and information centers. Design/methodology/approach The study as an applied research with a qualitative approach employed the grounded theory. The data collection tool was a deep and semi-structured interview. The interviews data were analyzed and coded during three stages of open, axial and selective coding using the MAXQDA 10 qualitative analysis software. The research population consisted of faculty members and experts in three areas of library and information science, management and psychology. Using the combined targeted sampling method (targeted and then the snowball), 12 subjects were selected as the sample size. Findings According to the research findings, the factors affecting the unplanned behavior of users in the use of academic libraries resources and services were identified as factors related to technology, environmental factors, information resources, information services, human resources, individual features, time position factor, cultural factors and social factors. Accordingly, the axial coding pattern of this type of behaviors was designed. Research limitations/implications The research limitations include the lack of theoretical basis related to the unplanned behavior issue in the field of library and information science and the lack of full familiarity of most of the experts in the field of library and information science with this topic. These factors lead to the necessity of explaining the subject under discussion. Originality/value The unplanned behavior of clients can be utilized to persuade users to use the information resources and library services so that the costs spent on their preparation and collection will be justifiable. The current research addressed this aspect of the unplanned information-seeking behavior.
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Morgalla, Matthias. "High-Resolution Three-Dimensional Computed Tomography for Assessing Complications Related to Intrathecal Drug Delivery." July 2016 5;19, no. 5;19 (July 14, 2016): E775—E780. http://dx.doi.org/10.36076/ppj/2016.19.e775.
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Background: The assessment of the functionality of intrathecal drug delivery (IDD) systems remains difficult and time-consuming. Catheter-related problems are still very common, and sometimes difficult to diagnose. Objectives: The aim of the present study is to investigate the accuracy of high-resolution three-dimensional computed tomography (CT) in order to detect catheter-related pump dysfunction. Study Design: An observational, retrospective investigation. Setting: Academic medical center in Germany. Methods: We used high-resolution three dimensional (3D) computed tomography with volume rendering technique (VRT) or fluoroscopy and conventional axial-CT to assess IDDrelated complications in 51 patients from our institution who had IDD systems implanted for the treatment of chronic pain or spasticity. Results: Twelve patients (23.5%) presented a total of 22 complications. The main type of complication in our series was catheter-related (50%), followed by pump failure, infection, and inappropriate refilling. Fluoroscopy and conventional CT were used in 12 cases. High-resolution 3D CT VRT scan was used in 35 instances with suspected yet unclear complications. Using 3D-CT (VRT) the sensitivity was 58.93% – 100% (CI 95%) and the specificity 87.54% – 100% (CI 95%).The positive predictive value was 58.93% – 100% (CI 95%) and the negative predictive value: 87.54% – 100% (CI 95%). Fluoroscopy and axial CT as a combined diagnostic tool had a sensitivity of 8.3% – 91.7% (CI 95%) and a specificity of 62.9% – 100% (CI 95%). The positive predictive value was 19.29% – 100% (CI 95%) and the negative predictive value: 44.43% – 96.89% (CI 95%). Limitations: This study is limited by its observational design and the small number of cases. Conclusion: High-resolution 3D CT VRT is a non- invasive method that can identify IDDrelated complications with more precision than axial CT and fluoroscopy. Key words: Volume rendering technique (VRT), intrathecal drug delivery systems, highresolution 3D computed tomography, complications, spasticity, chronic pain, cost effectiveness, fluoroscopy
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Ivanov, Alexey, Valery Rubtsov, Andrey Chumaevskii, Kseniya Osipovich, Evgeny Kolubaev, Vladimir Bakshaev, and Ivan Ivashkin. "Features of structure formation processes in AA2024 alloy joints formed by the friction stir welding with bobbin tool." Metal Working and Material Science 23, no. 2 (June 10, 2021): 98–115. http://dx.doi.org/10.17212/1994-6309-2021-23.2-98-115.
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Introduction. One of friction stir welding types is the bobbin friction stir welding (BFSW) process, which allows to obtain welded joints in various configurations without using a substrate and axial embedding force, as well as to reduce heat loss and temperature gradient across the welded material thickness. This makes the BFSW process effective for welding aluminum alloys, which properties are determined by their structural-phase state. According to research data, the temperature and strain rate of the welded material have some value intervals in which strong defect-free joints are formed. At the same time, much less attention has been paid to the mechanisms of structure formation in the BFSW process. Therefore, to solve the problem of obtaining defect-free and strong welded joints by BFSW, an extended understanding of the basic mechanisms of structure formation in the welding process is required. The aim of this work is to research the mechanisms of structure formation in welded joint of AA2024 alloy obtained by bobbin tool friction stir welding with variation of the welding speed. Results and discussion. Weld formation conditions during BFSW process are determined by heat input into a welded material, its fragmentation and plastic flow around the welding tool, which depend on the ratio of tool rotation speed and tool travel speed. Mechanisms of joint formation are based on a combination of equally important processes of adhesive interaction in “tool-material” system and extrusion of metal into the region behind the welding tool. Combined with heat dissipation conditions and the configuration of the “tool-material” system, this leads to material extrusion from a welded joint and its decompaction. This results in formation of extended defects. Increasing in tool travel speed reduce the specific heat input, but in case of extended joints welding an amount of heat released in joint increases because of specific heat removal conditions. As a result, the conditions of adhesion interaction and extrusion processes change, which leads either to the growth of existing defects or to the formation of new ones. Taking into account the complexity of mechanisms of structure formation in joint obtained by BFSW, an obtaining of defect-free joints implies a necessary usage of various nondestructive testing methods in combination with an adaptive control of technological parameters directly in course of a welding process.
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Kao, Yung-Chou, Nhu-Tung Nguyen, Mau-Sheng Chen, and Shyh-Chour Huang. "A combination method of the theory and experiment in determination of cutting force coefficients in ball-end mill processes." Journal of Computational Design and Engineering 2, no. 4 (June 23, 2015): 233–47. http://dx.doi.org/10.1016/j.jcde.2015.06.005.
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Abstract In this paper, the cutting force calculation of ball-end mill processing was modeled mathematically. All derivations of cutting forces were directly based on the tangential, radial, and axial cutting force components. In the developed mathematical model of cutting forces, the relationship of average cutting force and the feed per flute was characterized as a linear function. The cutting force coefficient model was formulated by a function of average cutting force and other parameters such as cutter geometry, cutting conditions, and so on. An experimental method was proposed based on the stable milling condition to estimate the cutting force coefficients for ball-end mill. This method could be applied for each pair of tool and workpiece. The developed cutting force model has been successfully verified experimentally with very promising results. Highlights By investigation of the stable cutting conditions in milling process, the linear function of average cutting force and feed per flute was successfully verified. A combined theoretical-experimental method was proposed with an effective model for the determination of cutting force coefficients in ball-end mill process.
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Zhang, Lufeng, Fujian Zhou, Jianye Mou, Wei Feng, Zhun Li, and Shicheng Zhang. "An Integrated Experimental Method to Investigate Tool-Less Temporary-Plugging Multistage Acid Fracturing of Horizontal Well by Using Self-Degradable Diverters." SPE Journal 25, no. 03 (January 31, 2020): 1204–19. http://dx.doi.org/10.2118/199884-pa.
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Summary Tool-less temporary-plugging multistage acid fracturing of horizontal well is a necessary technology to unlock the production potential and enable commercial productivity for tight carbonate reservoirs. However, this technique has not been investigated experimentally yet, and the plugging behavior of diverters within acid-etched fracture is still unclear. In this paper, we propose an integrated method to experimentally study tool-less multistage fracturing with diverters. First, we introduce an innovative 3D printing method to reproduce the roughness of acid-etched fracture surface and design an acid-etched fracture temporary plugging evaluation system to satisfy the requirements of temporary plugging experiments. Then, we conduct a series of plugging experiments to optimize the diverter's formula for creating a tight plugging zone within an acid-etched fracture under different fracture widths. On the basis of the description of the fracture surface, we further analyze the formation process and mechanism of temporary plugging. Finally, we further verify through laboratory experiments using a modified true tri-axial fracturing system the feasibility of using a single type of diverter and combined diverters to achieve tool-less temporary plugging staged fracturing of horizontal well. The experimental results show the following findings: (1) Pure fibers can realize temporary plugging at lower fracture width (≤2 mm). (2) To achieve temporary plugging, the diameter of particulates should not be less than half of the fracture width under the condition of larger fracture width (≥4 mm). (3) The fracture surface morphology affects the formation time of temporary plugging, but does not affect whether temporary plugging is formed or not. (4) Using a steel plate with a smooth fracture surface to conduct optimization experiments will increase the dosage of diverters, thus increasing the operation cost. (5) Pure particulates cannot achieve favorable plugging effect. This study provides an insight into multistage acid fracturing.
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Li, Yong, and Shaoping Zhou. "Sensorless balance method for the spindle system of computer numerical control gear grinding machine." Measurement and Control 51, no. 9-10 (October 8, 2018): 460–69. http://dx.doi.org/10.1177/0020294018802715.
Повний текст джерелаАнотація:
Background: Spindle imbalance vibration of the computer numerical control grinding machine may result in dramatic effects on tool wear, surface finish, and form-holding of the products, which makes the balancing procedure very essential during their manufacturing process. Although the spindle residual vibration in a single direction can be suppressed effectively by the commonly used commercial balance systems, some real-world application results show that most of these balance systems cannot reduce the spindle residual vibration in horizontal, vertical, and axial direction simultaneously. Methods: To overcome this issue, the limitation of commonly used influence coefficient method–based spindle balance method is discussed first. After that, a novel balance method is experimentally proposed for the spindle vibration control using the position fluctuation information between the carriage and guideway of the servo-axis. In this method, the position fluctuation information between the carriage and guideway and the key phase information are practically measured using the built-in linear scale and spindle servomotor encoder, respectively, in which the position fluctuation information between the carriage and guideway can be considered as an integrated representation of the spindle imbalance vibration. Combined with the influence coefficient method, the imbalance vibration presenting in the horizontal, vertical, and axial direction of the spindle can be suppressed simultaneously and effectively. Results and Conclusions: A field balancing experiment is carried out on a high-precision computer numerical control gear grinding machine. Experiment results demonstrate that, compared with the commonly used commercial balancing system, the proposed method can not only reduce the residual vibration amplitude at the objective balancing speed effectively but also reduce the residual vibration amplitude more than 50% simultaneously in each direction during the whole run-down process.
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di Virgilio, Agustina, Juan M. Morales, Sergio A. Lambertucci, Emily L. C. Shepard, and Rory P. Wilson. "Multi-dimensional Precision Livestock Farming: a potential toolbox for sustainable rangeland management." PeerJ 6 (May 30, 2018): e4867. http://dx.doi.org/10.7717/peerj.4867.
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Background Precision Livestock Farming (PLF) is a promising approach to minimize the conflicts between socio-economic activities and landscape conservation. However, its application on extensive systems of livestock production can be challenging. The main difficulties arise because animals graze on large natural pastures where they are exposed to competition with wild herbivores for heterogeneous and scarce resources, predation risk, adverse weather, and complex topography. Considering that the 91% of the world’s surface devoted to livestock production is composed of extensive systems (i.e., rangelands), our general aim was to develop a PLF methodology that quantifies: (i) detailed behavioural patterns, (ii) feeding rate, and (iii) costs associated with different behaviours and landscape traits. Methods For this, we used Merino sheep in Patagonian rangelands as a case study. We combined data from an animal-attached multi-sensor tag (tri-axial acceleration, tri-axial magnetometry, temperature sensor and Global Positioning System) with landscape layers from a Geographical Information System to acquire data. Then, we used high accuracy decision trees, dead reckoning methods and spatial data processing techniques to show how this combination of tools could be used to assess energy balance, predation risk and competition experienced by livestock through time and space. Results The combination of methods proposed here are a useful tool to assess livestock behaviour and the different factors that influence extensive livestock production, such as topography, environmental temperature, predation risk and competition for heterogeneous resources. We were able to quantify feeding rate continuously through time and space with high accuracy and show how it could be used to estimate animal production and the intensity of grazing on the landscape. We also assessed the effects of resource heterogeneity (inferred through search times), and the potential costs associated with predation risk, competition, thermoregulation and movement on complex topography. Discussion The quantification of feeding rate and behavioural costs provided by our approach could be used to estimate energy balance and to predict individual growth, survival and reproduction. Finally, we discussed how the information provided by this combination of methods can be used to develop wildlife-friendly strategies that also maximize animal welfare, quality and environmental sustainability.
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Marschik, Christian, Wolfgang Roland, Marius Dörner, Sarah Schaufler, Volker Schöppner, and Georg Steinbichler. "Application of Network Analysis to Flow Systems with Alternating Wave Channels: Part B. (Superimposed Drag-Pressure Flows in Extrusion)." Polymers 12, no. 9 (August 24, 2020): 1900. http://dx.doi.org/10.3390/polym12091900.
Повний текст джерелаАнотація:
Due to progress in the development of screw designs over recent decades, numerous high-performance screws have become commercially available in single-screw extrusion. While some of these advanced designs have been studied intensively, others have received comparatively less attention. We developed and validated a semi-numerical network-theory-based modeling approach to predicting flows of shear-thinning polymer melts in wave-dispersion screws. In the first part (Part A), we systematically reduced the complexity of the flow analysis by omitting the influence of the screw rotation on the conveying behavior of the wave zone. In this part (Part B), we extended the original theory by considering the drag flow imposed by the screw. Two- and three-dimensional melt-conveying models were combined to predict locally the conveying characteristics of the wave channels in a discretized flow network. Extensive experiments were performed on a laboratory single-screw extruder, using various barrel designs and wave-dispersion screws. The predictions of our semi-numerical modeling approach for the axial pressure profile along the wave-dispersion zone accurately reproduce the experimental data. Removing the need for time-consuming numerical simulations, this modeling approach enables fast analyses of the conveying behavior of wave-dispersion zones, thereby offering a useful tool for design and optimization studies and process troubleshooting.
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Chaur González, Julian, Jorge Nieto Andrade, and Manuel Esteban Barba Delgado. "Uso de modelos de cálculo didácticos en la estructura axilsimétrica del cenotafio de Newton = Use of didactic calculation models in the axilsimetric structure of Newton's cenotaph." Advances in Building Education 1, no. 3 (December 31, 2017): 67. http://dx.doi.org/10.20868/abe.2017.3.3670.
Повний текст джерелаАнотація:
ResumenEl trabajo desarrollado consiste en la formalización y comprobación ante hipótesis de carga de una bóveda axilsimétrica no construida. Esta bóveda es un proyecto utópico del arquitecto Louis Etienne Boullée, arquitecto francés con un volumen de obra muy significativo de carácter casi "surrealista". La obra de este autor alcanza normalmente unas proporciones titánicas y carentes de ornamento, basando sus formas principalmente en volúmenes geométricos sencillos. El proyecto que nos atañe será el cenotafio de Isaac Newton, una gigantesca bóveda axil simétrica con un espesor muy reducido en algunos puntos. Con el uso del programa de cálculo Maple, un programa de ánalisis matemático combinado con la tecnología CAD/CAM basada en los dibujos existentes de este proyecto comprobaremos la estabilidad geométrica y estructural de esta bóveda de proporciones titánicas. Con esto mostraremos las posibilidades de aplicación de los programas de cálculo geométrico a los modelos estructurales históricos y teóricos, como una herramienta mucho más visible y didáctica que los cálculos numéricos al uso. La visualización de los esfuerzos que resultan en las diferentes dovelas de la bóveda, conjuntamente con la comprensión y constatación del funcionamiento axil simétrico del modelo será determinante a la hora de comprender el funcionamiento de este sistema estructural y resolverá la duda que nos atañe. ¿Se podría construir el cenotafio de Newton? ¿Es una construcción estable geométrica y materialmente?AbstractThe work developed in this paper consists in the formalization and verification of the load hypothesis of a non-constructed axilsymmetric vault. This vault is a utopian project by the architect Louis Etienne Boullée, French architect with a very significant volume of work of "surrealist" character. The works topic of this author usually resembles itself in buildings of titanic proportions and devoid of ornament, that base their forms mainly on simple geometric volumes. The project that concerns us will be the Isaac Newton cenotaph, a giant axial symmetric vault with a very small thickness in some points. With the use of the Maple calculation program, a mathematical analysis program combined with CAD / CAM technology based on the existing drawings of this project, we will check the geometric and structural stability of this vault. With this we will show the possibilities of application of the geometric calculation programs to historical and theoretical structural models, as a much more visible and didactic tool than the usual numerical calculations. The visualization of the efforts that result in the different keystones of the vault, together with the understanding and verification of the axial symmetrical functioning of the model, will be decisive when understanding the functioning of this structural system and will resolve the main doubt that concerns us. Could Newton's cenotaph be built? Is it geometrically and materially speaking a stable construction?
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Hatano, Koji, Junichiro Tanaka, Yasutomo Nakai, Masashi Nakayama, Ken-ichi Kakimoto, Katsuyuki Nakanishi, and Kazuo Nishimura. "Utility of index lesion volume assessed by multiparametric MRI combined with Gleason grade for assessment of lymph node involvement in patients with high-risk prostate cancer." Japanese Journal of Clinical Oncology 50, no. 3 (December 12, 2019): 333–37. http://dx.doi.org/10.1093/jjco/hyz170.
Повний текст джерелаАнотація:
Abstract Purpose We examined the potential predictors of lymph node involvement and evaluated whether index lesion volume assessed using multiparametric magnetic resonance imaging is associated with lymph node involvement among patients with high-risk prostate cancer. Methods Extended pelvic lymph node dissection was used to evaluate patients with lymph node involvement. We retrospectively analyzed consecutive 102 patients with high-risk prostate cancer who underwent extended pelvic lymph node dissection at our institution between 2011 and 2017. To evaluate the index lesion volume at multiparametric magnetic resonance imaging (mrV), lesions were manually contoured on each T2-weighted axial slice in combination with diffusion-weighted and dynamic contrast-enhanced magnetic resonance imaging and integrated using image analysis software. Logistic regression analysis was performed to identify predictors of lymph node involvement. Results The median mrV was 1.4 ml (range 0–30.1 ml), and the median number of resected lymph nodes was 14 (range 7–38). Among 102 patients, 28 (28%) had lymph node involvement. Multivariate analysis identified significant predictors of lymph node involvement as follows: biopsy Gleason-grade group 5 (odds ratio = 17.2; 95% confidence interval, 2.1–299.0; P = 0.005), preoperative mrV (odds ratio = 1.14; 95% confidence interval, 1.02–1.30; P = 0.025) and percentage of positive cores with highest Gleason-grade group (odds ratio = 1.05; 95% confidence interval, 1.01–1.10; P = 0.005). Lymph node involvement was prevalent (69%) among tumors with Gleason-grade group 5 and mrV ≥3.4 ml, but was infrequently (10%) present among tumors with Gleason-grade group ≤4 and mrV <3.4 ml. Conclusions The combination of biopsy Gleason-grade and mrV may serve as a useful tool to stratify patients according to their risk of nodal metastases.
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Chida, K., H. Otani, H. Saito, T. Nagasaka, Y. Kagaya, M. Kohzuki, M. Zuguchi, and K. Shirato. "Feasibility of rapid‐sequence 31p magnetic resonance spectroscopy in cardiac patients." Acta Radiologica 46, no. 4 (July 2005): 386–90. http://dx.doi.org/10.1080/02841850510021283.
Повний текст джерелаАнотація:
Purpose: To determine the clinical feasibility of rapid‐sequence phosphorus‐31 magnetic resonance spectroscopy (31P ‐MRS) of the heart with cardiac patients using a 1.5T clinical MR system. Material and Methods: Twenty cardiac patients, i.e. dilated cardiomyopathy (DCM) 13 cases, hypertrophic cardiomyopathy (HCM) 3 cases, hypertensive heart diseases (HHD) 3 cases, and aortic regurgitation (AR) 1 case were examined using rapid cardiac 31P‐MRS. Complete three‐dimensional localization was performed using a two‐dimensional phosphorus chemical‐shift imaging sequence in combination with 30‐mm axial slice‐selective excitation. The rapid‐sequence 31P‐MRS procedure was phase encoded in arrays of 8×8 steps with an average of 4 acquisitions. The total examination time, including proton imaging and shimming, for the rapid cardiac 31P‐MRS procedure, ranged from 10 to 15 min, depending on the heart rate. Student's t test was used to compare creatine phosphate (PCr)/adenosine triphosphate (ATP) ratios from the cardiac patients with those of the control subjects ( n = 13). Results: The myocardial PCr/ATP ratio obtained by rapid 31P‐MRS was significantly lower ( P<0.001) in DCM patients (1.82±0.33, mean±SD), and in patients with global myocardial dysfunction (combined data for 20 patients: 1.89±0.32) than in normal volunteers (2.96±0.59). These results are similar to previous studies. Conclusion: Rapid‐sequence 31P‐MRS may be a valid diagnostic tool for patients with cardiac disease.
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Kim, K. J., S. T. Won, Y. H. Lee, D. S. Bae, C. W. Sung, and Y. N. Paik. "Development of an automotive rear subframe by the tube hydroforming process." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 11 (November 1, 2008): 1977–84. http://dx.doi.org/10.1243/09544070jauto890.
Повний текст джерелаАнотація:
The automotive industry has shown a growing interest in tube hydroforming during recent years. The advantages of hydroforming (less thinning, a more efficient manufacturing process, etc.) can, for instance, be combined with the high strength of extra-high-strength steels, which are usually less formable, to produce structural automotive components which exhibit lower weight and improved service performance. Design and production of tubular components require knowledge about tube material and forming behaviour during hydroforming and how the hydroforming operation itself should be controlled. These issues are studied analytically in the present paper. In this study, the whole process of rear subframe parts development by tube hydroforming using steel material having a tensile strength of 440MPa is presented. At the part design stage, it requires a feasibility study and process design assisted by computer aided engineering to confirm hydroformability in detail. The effects of parameters such as internal pressure, axial feeding, and geometry shape in the automotive rear subframe by the hydroforming process were carefully investigated. The overall possibility of hydroformable rear subframe parts could be examined by cross-sectional analyses. Moreover, it is essential to ensure the formability of tube material on every forming step such as pre-bending and hydroforming. In addition, all the components of a prototyping tool are designed and interference with a press is examined from the point of geometry and thinning.
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Han, Xiaoshuang, Weiliang Qiao, and Bo Zhou. "Frequency Domain Response of Jacket Platforms under Random Wave Loads." Journal of Marine Science and Engineering 7, no. 10 (September 21, 2019): 328. http://dx.doi.org/10.3390/jmse7100328.
Повний текст джерелаАнотація:
This article presents a procedure that simplifies an offshore jacket platform as a non-uniform cantilever beam subjected to an axial force. A Ritz method combined with a pseudo-excitation method is then used to analyze the responses of the jacket platform under random wave loads with the associated power spectral densities, variances and higher spectral moments. The theoretical basis and pertinent governing equations are derived. The proposed procedure not only eases the process of determining the pseudo wave loads, but also requires only the rudimentary structural details that are typically available at the preliminary design stage. Additionally, the merit of the proposed procedure is that the process does not require one to compute the normal modes, which saves time and is particularly convenient for the dynamic-response analysis of a complex structure (such as an offshore platform). An illustrative example based on a three-deck jacket platform is presented to demonstrate the procedure used to obtain the power spectral densities, variances and second spectral moments of jacket-top displacement and the bending moment of the jacket at the mud line. The results obtained are compared with those obtained using a Finite Element Mothed (FEM) model. Based on the findings of the study and good agreement shown in the comparison of results, it is concluded that the proposed method is effective, simple and convenient, and can be a useful tool for the preliminary design analysis of offshore platforms.
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SARVAN SHIRVAN, EZIZ. "KINEMATIC FEATURES OF THE LAPPING PROCESS AND DETERMINATION OF ITS BASIC PARAMETERS." Computational nanotechnology 7, no. 3 (September 30, 2020): 23–28. http://dx.doi.org/10.33693/2313-223x-2020-7-3-23-28.
Повний текст джерелаАнотація:
This paper discusses the kinematic characteristics of lapping process and the main parameters of the process. It was determined that the influencing degree of technological parameters to the forming surface and processes. It was projected the construction of the lapping head for processing of internal cylindrical surfaces, scheme of the lapping operation and graphic description of the forces influencing. The relationships between the axial, radial and tangential cutting forces and the effect of the combined force thereof are determined in order to ensure the necessary surface pressure. During the analysis geometric and mathematical relationships were obtained. The extracted analytical expressions can be realized by further experimental researches and can be used in engineering calculations of technological parameters of processing by lapping. Angular velocity, friction force, linear velocity, also the length of the tactile curve and the radius of the part can be considered the main kinematic and dynamic parameters of the process that the formation of the surface, also the course of the process depends on these parameters. Depending on the kinematic parameters, the wear nature of the tool changes and this changes the linear and angular velocities, which have a significant impact on the accuracy, quality and productivity of processing. When examining the technological capabilities of the process, the nature of the movement between the part and the grinding tool, also changes in cutting speed are often considered as a main factor. Analytical expressions were obtained to determine the main parameters of the process, taking into account the kinematic characteristics of the friction process. These expressions can be used in engineering calculations and allow to determine the optimal values of the processing mode. In order to obtain the required micrometric surface cleanliness and measurement accuracy, correlation relationships were established between the main parameters of the process, equations of the equilibrium system of shear forces were compiled and analytical expressions were obtained based on the analysis of kinematic and dynamic properties of the system.