Path Inclination Research Articles

Evaluation of joint kinematics in patients with condylar reconstruction using mandibular motion simulation based on intraoral scanning registration.

To summarize the features of condylar kinematics in patients with condylar reconstruction using a mandibular motion simulation method based on intraoral scanning registration. Patients undergoing unilateral segmental mandibulectomy and autogenous bone reconstruction as well as healthy volunteers were enrolled in the study. Patients were grouped based on whether the condyles were reconstructed. Mandibular movements were recorded using a jaw tracking system, and kinematic models were simulated after registration. The path inclination of the condyle point, margin of border movement, deviation, and chewing cycle were analyzed. A t test and one-way analysis of variance (ANOVA) were carried out. A total of 20 patients, including 6 with condylar reconstruction and 14 with condylar preservation as well as 10 healthy volunteers were included. The patients with condylar reconstruction showed flatter movement paths of the condyle points. The mean inclination angle of the condylar movement paths of the patients with condylar reconstruction (0.57 ± 12.54 degrees) was significantly smaller than that of those with condylar preservation (24.70 ± 3.90 degrees, P = 0.014) during both maximum opening and protrusion (7.04 ± 12.21 degrees and 31.12 ± 6.79 degrees, respectively, P = 0.022). The inclination angle of the condylar movement paths of the healthy volunteers was 16.81 ± 3.97 degrees during maximum opening and 21.54 ± 2.80 degrees during protrusion; no significant difference compared with the patients. The condyles of the affected side tended to deviate laterally in all patients during mouth opening and protrusion. Patients with condylar reconstruction showed more severe symptoms of mouth opening limitation and mandibular movement deviation as well as shorter chewing cycles than patients with condylar preservation. Patients with condylar reconstruction showed flatter movement paths of the condyle points, greater lateral motion range, and shorter chewing cycles than those with condylar preservation. The method of mandibular motion simulation based on intraoral scanning registration was feasible to simulate condylar movement.

Control of corner arc radius in wire electrochemical micromachining

Wire electrochemical micromachining (WECMM) technology is commonly used to process micro parts. Some thick parts contain many sharp structures, and have high machining accuracy requirements for the arc radius at the corner, such as jet sheet, micro gear, etc. However, when machining thick workpiece, it is easy to form a large arc radius at the corner due to stray corrosion and difficult discharge of electrolytic products. In order to solve this problem, this paper proposes a corner path optimization method, which reduces the arc radius of the sharp structure by adjusting the processing path of the wire electrode, thereby improving the machining accuracy of the sharp structures. The model of the relationship between the inclination of the machining path and the angle of the sharp structure is established. The inclination and offset distance of the processing path are obtained through theoretical calculation, and further optimized through experiments to avoid overcut or undercut at the corner. In the experiment, tungsten wires with different diameters were used as wire electrodes to process acute angle, right angle and obtuse angle structures on 510 μm thick 9Cr18Mo stainless steel. The influence of wire electrode processing path on the corner arc radius of different angle sharp structures was explored. The experimental results show that compared with the original path, the arc radius of the sharp structure could be reduced from tens of microns to <5 μm by using the optimized processing path.

Command Filter AILC for Finite Time Accurate Tracking of Aircraft Track Angle System Based on Fuzzy Logic

In this paper, the longitudinal model of an uncertain aircraft is taken as the research object, and the aircraft path inclination is controlled by controlling the input rudder deflection angle. An adaptive iterative learning control (AILC) scheme is proposed to solve the accurate tracking control problem of the flight path inclination on a finite time interval. The aircraft track angle system is abstractly modeled to obtain a triangular model in the form of strict feedback. For the abstracted strict feedback model, the fuzzy logic is used to approximate the uncertain part of the model. A command filter and an error compensation mechanism are introduced to prevent the computational bloat problem caused by excessive system order, and a convergent series sequence is used to deal with the truncation error caused by the approximation of the fuzzy logic. Based on the Lyapunov stability theorem, all signals of the closed-loop system are bounded on the finite time interval 0 , T , and the output of the system can track the desired trajectory accurately. Finally, the feasibility and effectiveness of the method are verified by MATLAB simulation results.

Intraoperative use of CT-navigation during percutaneous nephrolitholapaxy with the SIEMENS Healthineers’ ARTIS pheno robotic system

Introduction. Percutaneous nephrolitholapaxy (PNL) is the optimal method in the treatment of large or complex renal stones. Surgical equipment and endoscopic equipment, and specialised tools have been constantly developing since the advent of PNL in 1976, increasing success rates with a decrease in the number of complications and morbidity. Owing to the specificity and complexity of the technique, only 11% of urologists in the USA perform PNL, while in Russian Federation no more than 5% of specialists realise it.Objective. To evaluate the possibilities of using a robot-angiograph to create a puncture access.Materials &amp; methods. In the Krasnoyarsk Regional Clinical Hospital in 2021, the first PNL was performed in a patient with a left-sided lower calyx stone using the SIEMENS Healthineers’ ARTIS pheno robotic angiograph in a hybrid operating room. This robotic installation allows the performing of an intraoperative computed tomography examination followed by the construction of a navigation map with a clearly displayed trajectory, length, and angle of inclination of the needle path with automatic positioning of the C-arm.Results. We performed 30 pyelocaliceal punctures using a robotic angiographic installation for PNL. The average age of patients was 56.6 ± 19.0 years. According to MSCT, the lower calyx stone was detected in seven patients, the middle calyx — 13 cases, the upper calyx — seven patients, pelvic stones were recorded in three patients. The density of stones varied from 877 HU to 1356 HU. The use of the ARTIS pheno robotic system allows performing intraoperative 3D modelling to determine the safest pyelocaliceal puncture, followed by PNL, regardless of the stone localisation, the complexity of the anatomy. In addition, a CT-like scans allows you to assess the presence of residual stones during the operation and perform a "second look" not in a delayed manner. This system, unlike all existing types of navigation, allows intraoperative evaluation of the effectiveness (stone-free rate) of surgical treatment.Conclusion. The introduction of this navigation system in PNL will minimise the risks of complications from puncture access, reduce the number of repeated interventions, and minimise undesirable consequences in the postoperative period.

Probabilistic Failure Estimation of an Oblique Loaded Footing Settlement on Cohesive Geomaterials with a Modified Cam Clay Material Yield Function

In this work, a quantitative uncertainty estimation of the random distribution of the soil material properties to the probability density functions of the failure load and failure displacements of a shallow foundation loaded with an oblique load is portrayed. A modified Cam Clay yield constitutive model is adopted with a stochastic finite element model. The random distribution of the reload path inclination κ, the critical state line inclination c of the soil and the permeability k of the Darcian water flow relation, has been assessed with Monte Carlo simulations accelerated by using Latin hypercube sampling. It is proven that both failure load and failure displacements follow Gaussian normal distribution despite the excessive non-linear behaviour of the soil. In addition, as the obliquity increases the mean value of failure load and the failure displacement always increases. The uncertainty of the output failure stress with the increase of the obliquity of the load remains the same. The failure spline of clays can be calculated within an acceptable accuracy with the proposed numerical scheme in every possible geometry and load conditions, considering the obliquity of the load in conjunction with non-linear constitutive relations.

Empiricalα–βrunout modelling of snow avalanches in the Catalan Pyrenees

AbstractA variation in theα−βmodel which is a regression model that allows a deterministic prediction of the extreme runout to be expected in a given path, was applied for calculating avalanche runout in the Catalan Pyrenees. Present knowledge of major avalanche activity in this region and current mapping tools were used. The model was derived using a dataset of 97 ‘extreme’ avalanches that occurred from the end of 19th century to the beginning of 21st century. A multiple linear regression model was obtained using three independent variables: inclination of the avalanche path, horizontal length and area of the starting zone, with a good fit of the function (R2= 0.81). A larger starting zone increases the runout and a larger length of the path reduces the runout. The new updated equation predicts avalanche runout for a return period of ~100 years. To study which terrain variables explain the extreme values of the avalanche dataset, a comparative analysis of variables that influence a longer or shorter runout was performed. The most extreme avalanches were treated. The size of the avalanche path and the aspect of the starting zone showed certain association between avalanches with longer or shorter runouts.

Measurement and Prediction of Short-Range Path Loss between 27 and 40 GHz in University Campus Scenarios

In this paper, we present the results of short-range path loss measurement in the microwave and millimetre wave bands, at frequencies between 27 and 40 GHz, obtained in a campaign inside a university campus in Rio de Janeiro, Brazil. Existing empirical path loss prediction models, including the alpha-beta-gamma (ABG) model and the close-in free space reference distance with frequency-dependent path loss exponent (CIF) model, are tested against the measured data, and an improved prediction method that includes the path loss dependence on the height difference between transmitter and receiver is proposed. The main contribution of this paper is the use of the Fuzzy technique to perform path loss predictions for short links in the millimetre wave range, from 27 to 40 GHz, providing lower errors when compared to the traditional ABG and CIF models. However, it should be noted that the Fuzzy technique uses a set of equations to perform the prediction and the attenuation coefficient is not explicit as in the classical models. Also, a non-negligible correlation between the difference in height between transmitter and receiver positions and the path loss in such short links (i.e., the path inclination) has been observed and requires further investigation. If confirmed, it could provide an additional parameter to improve the accuracy of the traditional ABG model.

Reproducibility of Sagittal Condylar Path Inclination Assessed by Protrusive Interocclusal Record with Two Different Techniques of Facebow Registration

Purpose: The purpose is to validate whether the data obtained for sagittal condylar inclination are correctly reproduced on the semi-adjustable articulator using protrusive interocclusal records for conventional facebow registration method (orbitale (OR) as an anterior point of reference) and facebow registration using bubble leveler (BL) as an anterior point of reference and compared these values with the values obtained by lateral cephalogram (gold standard). Materials and Methods: In total, 30 individuals (20 males and 10 females) with proper teeth alignment, facebow registrations were recorded using OR as an anterior point of reference (Group A, conventional technique) and WBL as an anterior point of reference (Group B). The sagittal condylar path inclination was measured and compared using protrusive interocclusal records for both the groups. These values compared with the values for sagittal condylar path inclination obtained using lateral cephalogram (Group C) using one-way analysis of variance (P &lt; 0.05). Results: There was no statistically significant differences observed in the values of sagittal condylar inclination for all three groups with P = 0.583. Conclusion: This study suggests that BL technique can be used for the orientation of maxillary cast on the semi-adjustable articulator as accurately as the conventional approach, for those practitioners who find difficulty in locating the OR for those patients with deformity in facial region. Lateral cephalogram provides almost the same measurements of sagittal condylar path inclination as obtained using protrusive interocclusal record on facebow registrations using OR and BL as an anterior point of references.

Optimal command control of flight paths of aerospace system hypersonic first stage in conditions of atmospheric disturbances

The paper deals with disturbed motion of the hypersonic first stage of an aerospace system in accelerated climb. Disturbances are deviations of atmospheric density from the values of a standard model. A multistep control process is accepted. The command angle-of-attack schedule is specified at each step of control using the method of Pontryagins maximum principle. The nominal control program is applied at the first step. We present the results of modeling disturbed motion with command control of the angle of attack for maximum rarified and maximum dense atmosphere. The angle-of-attack constraint is violated for rarified and dense atmosphere at the end of the accelerated flight segment when a boundary value problem is solved. If command control obtained as a result of solving the boundary value problem is maintained the target terminal speed and altitude conditions are fulfilled. The finite value of the flight path inclination angle for rarefied atmosphere is 10% lower than the target one, while for dense atmosphere it is 12% higher.

Optimal command control of hypersonic aircraft flight path in conditions of atmospheric disturbances

Disturbed flight of a hypersonic vehicle in accelerated climb is analyzed. Disturbances are deviations of atmospheric density from the values of a standard model. The following concepts and definitions are used in the paper. The nominal optimal angle-of-attack control program is the angle-of-attack control program obtained in solving the task of minimizing fuel consumption for a model of standard atmosphere (hereafter nominal program). The disturbed nominal optimal program is the angle-of-attack control program obtained in solving the task of minimizing fuel consumption for a model of disturbed atmosphere on the condition that the disturbances are known (hereafter disturbed program. The command optimal program is the angle-of-attack control program obtained in solving the task of minimizing fuel consumption for a model of disturbed atmosphere on the condition that the disturbances are unknown (hereafter command program, command control). A multi-step control process is accepted. At each step of control the angle-of-attack control program is defined using the method of Pontryagins maximum principle. The nominal control program is used at the first step. The results of modeling disturbed motion with angle-of-attack command control are presented for maximum rarefied and maximum dense atmosphere. In the case of rarefied atmosphere the angle-of-attack restriction is violated at the end of the flight segment under consideration in solving the boundary value problem, while the prescribed terminal velocity, altitude and flight path inclination conditions are satisfied. In the case of dense atmosphere the terminal altitude and flight path inclination conditions are satisfied, but the terminal velocity condition is not. Since there is no violation of the above-mentioned control and phase coordinate restrictions in the case of the disturbed program, further line of research in the area of optimal command control is related to the improvement of the algorithm of solving the boundary value problem.

Hydrodynamic optimization of the geometry of a sloped-motion wave energy converter

This paper presents the hydrodynamic optimization study of CECO, a point absorber wave energy converter (WEC) with sloped motion. To maintain the overall costs, the characteristic dimensions of the optimized solution were not allowed to change significantly. Instead, different geometrical shapes have been generated and numerically investigated based on the exhaustive search method with a heuristic approach. The assessment of the different geometries was based on a new index - the hydrodynamic capacity for wave energy conversion - which considers that the theoretical maximum WEC's absorbed power from irregular waves is obtained assuming that for each individual wave component of the sea spectrum, the PTO system can operate with its optimum damping coefficient. The optimum geometry obtained is able to harvest twice as much wave energy than the original design of CECO. The numerical outcomes have been validated with the results of experimental tests with the new geometry. Unlike “pure” heaving WECs, a sloped-motion WEC can achieve natural oscillation periods within a broad range by controlling the inclination of the motion path, the submergence level or the shape of its floaters. Therefore, CECO can be tuned to any given sea state and avoid the need for active complex control strategies.

Disturbed motion of the hypersonic first stage of an aerospace system in climb

Disturbed motion of the hypersonic first stage of an aerospace system in climb is analyzed. Deviations of atmospheric density from standard values and deviations of aerodynamic force coefficients from reference values are taken as disturbances. Disturbance motion of the hypersonic first stage of a hypersonic vehicle with the optimal angle-of-attack schedule obtained for reference atmosphere and nominal aerodynamic characteristics is modeled. Deviations of terminal conditions of disturbed motion from the target values of velocity, altitude and flight path inclination are determined. The problem of minimum propellant mass consumed in the climb with acceleration to hypersonic velocity is solved for disturbed motion by the method of Pontryagins maximum principle. Optimal angle-of-attack schedules, optimal flight paths and finite values of the mass of the hypersonic first stage are determined. Comparative analysis of optimal control programs and flight paths for disturbed and undisturbed motion is made.

Disturbed motion of a hypersonic vehicle in climb

Disturbed motion of a hypersonic vehicle in climb is analyzed. Deviations of atmospheric density from standard values and deviations of aerodynamic force coefficients from nominal values are taken as disturbances. Disturbed motion of a hypersonic vehicle with the optimum angle-of-attack schedule and nominal flight characteristics is modeled. Deviations of terminal conditions of disturbed motion from the target values of velocity, altitude and path inclination are determined. Using the method of Pontryagins maximum principle the problem of fuel mass minimum consumed in hypersonic acceleration climb is solved for disturbed motion. Optimal angle-of-attack schedules, optimal flight paths and finite values of the hypersonic vehicles mass are determined. Comparative analysis of optimal control programs and flight paths obtained for disturbed and undisturbed motion is carried out.

Backstepping Control of Aircraft Take-Off in Windshear

In this paper, we deal with the problem of aircraft take-off control in the presence of a windshear. A simplified point mass nonlinear model of aircraft dynamics assuming the flight in a vertical plane is used. A reference trajectory is constructed to satisfy the altitude, relative path inclination and relative velocity state constraints. An integrator backstepping based control design procedure using barrier Lyapunov functions is suggested to track the constructed reference trajectory under state constraints and windshear disturbances.

A Collaborative System for Suitable Wheelchair Route Planning

Route planning is a challenging problem for urban computing that usually involves the processing of a huge amount of data and collaborative user feedback. Traditionally, route planning services are street-based, that is, even paths for a pedestrian are suggested in terms of streets. However, such models are not suitable for users with certain disabilities. To address this problem, we have performed a requirement analysis with a group of wheelchair-users and their companions to understand their urban mobility experience. Given that perspective, we describe in this article a sidewalk-based model to accommodate the needs for a wheelchair route planning service. The model is mathematically defined as a graph, where the vertices are the city block corners and the edges are the sidewalks or crosswalks. The edge costs are derived from important accessibility features, such as distance, path inclination, and existence and maintenance conditions of curb ramps, crosswalks, and sidewalks. The model has been designed so that user feedback is considered to help updating the model when accessibility issues are detected, by wheelchair-users and companions, or solved, by the department of city planning. We also present a route planning algorithm that provides a set of alternative routes based on accessibility conditions, and a shortcut recommender algorithm to support accessibility-related decision making by the department of city planning. Experiments, by using PgRouting and PostGIS with open data, are reported for a Brazilian city neighborhood to validate the model and the route planning service.

(L + S)-RT-CCD for Terrain Paths Monitoring

In past research, the problem of maritime targets detection and motion parameter estimation has been tackled. This letter aims to contribute to preventing illegal immigration, solving the problem of obtaining reliable paths detection of targets in terms of temporal decorrelation observed on coherent change detection (CCD) maps occurring between two or more complex-valued synthetic aperture radar (SAR) images. Most detection problems are related to terrain clutter and platform motion instabilities which make the paths structure detection and reconnaissance difficult. This letter presents a complete procedure called low-rank plus sparse decomposition radon transform (RT) CCD for automatic estimation and tracking of target paths by evaluating the generated temporal decorrelation CCD-SAR images, observed at the desert environments. The algorithm consists of evaluating a dual-stage low-rank plus sparse decomposition (LRSD) assisted by RT for clutter reduction, sparse object detection, and precise path inclination estimation. The algorithm is based on the robust principal component analysis (RPCA) implemented by convex programming. The LRSD algorithm permits the extrapolation of sparse objects of interest consisting of the incoherent patterns generated by targets from the unchanging low-rank and more coherent background. This dual-stage RPCA and RT applied to SAR-CCD surveillance permits fast detection and enhanced parameter estimation of terrain target paths.

Effect of Variable Confining Pressure on Cyclic Triaxial Behavior of K0-consolidated Soft Marine Clay

The effect of variable confining pressure (VCP) on the cyclic deformation and cyclic pore water pressure in K0-consolidated saturated soft marine clay were investigated with the help of the cyclic stress-controlled advanced dynamic triaxial test in undrained condition. The testing program encompassed three cyclic deviator stress ratios, CSR=0.189, 0.284 and 0.379 and three stress path inclinations ηampl=3,1 and 0.64. All tests with constant confining pressure (CCP) and variable confining pressure (VCP) have identical initial stress and average stress. The results were analyzed in terms of the accumulative normalized excess pore water pressure rqu recorded at the end of each stress cycle and permanent axial strain, as well as resilient modulus. Limited data suggest that these behavior are significantly affected by both of the VCP and CSR. For a given value of VCP, both of the pore water pressure rqu and permanent axial strains are consistently increase with the increasing values of CSR. However, for a given value of CSR, the extent of the influence of VCP and the trend is substantially depend on the CSR.

Optimizing a vehicle trans-atmospheric motion using Pontryagin’s maximum principle

The task of optimizing trans-atmospheric motion of a flight vehicle in order to maximize its final velocity with prescribed finite values of the height and flight path angle is considered. The angle of attack acts as control in passive motion of a vehicle. Previously, the sequential linearization method was used to solve this optimization task. It is shown that at great altitudes the control programs are slightly different depending on the chosen initial approximation. Therefore, the aim of this work is to determine the optimum control program on the basis of a strict solution of the optimization task using the Pontryagins maximum principle. Solving the problem of optimizing trans-atmospheric motion of a flight vehicle is illustrated by passive climb of the sub-hypersonic vehicle MPV (the first stage of the aerospace system RASCAL designed in the USA). The coefficient of lift (angle of attack) increases in the greater part of the trajectory to provide the prescribed finite values of height and path inclination and then decreases to provide maximum final velocity. The correctness of the obtained solutions of the optimization task using the maximum principle is confirmed by the zero Hamiltonian value in the optimum trajectory. The results of vehicle motion simulation with optimal control and various initial conditions of motion and the vehicle mass are discussed. The results obtained show that the solutions of the optimization task under consideration using the maximum principle and the sequential linearization principle are in close agreement.

Numerical tilting compensation in microscopy based on wavefront sensing using transport of intensity equation method

Wide-field microscopy is commonly used for sample observations in biological research and medical diagnosis. However, the tilting error induced by the oblique location of the image recorder or the sample, as well as the inclination of the optical path often deteriorates the imaging quality. In order to eliminate the tilting in microscopy, a numerical tilting compensation technique based on wavefront sensing using transport of intensity equation method is proposed in this paper. Both the provided numerical simulations and practical experiments prove that the proposed technique not only accurately determines the tilting angle with simple setup and procedures, but also compensates the tilting error for imaging quality improvement even in the large tilting cases. Considering its simple systems and operations, as well as image quality improvement capability, it is believed the proposed method can be applied for tilting compensation in the optical microscopy.

Monotonic and cyclic tests on kaolin: a database for the development, calibration and verification of constitutive models for cohesive soils with focus to cyclic loading

A database with about 60 undrained monotonic and cyclic triaxial tests on kaolin is presented. In the monotonic tests, the influences of consolidation pressure, overconsolidation ratio, displacement rate and sample cutting direction have been studied. In the cyclic tests, the stress amplitude, the initial stress ratio and the control (stress vs. strain cycles) have been additionally varied. Isotropic consolidation leads to a failure due to large strain amplitudes with eight-shaped effective stress paths in the final phase of the cyclic tests, while a failure due to an excessive accumulation of axial strain and lens-shaped effective stress paths was observed in the case of anisotropic consolidation with $$q^{\text{ ampl }}< |q^{\text{ av }}|$$ . The rate of pore pressure accumulation grew with increasing amplitude and void ratio (i.e. decreasing consolidation pressure and overconsolidation ratio). The “cyclic flow rule” well known for sand has been confirmed also for kaolin: With increasing value of the average stress ratio $$|\eta ^{\text{ av }}| = |q^{\text{ av }}|/p^{\text{ av }}, $$ the accumulation of deviatoric strain becomes predominant over the accumulation of pore water pressure. The tests on the samples cut out either horizontally or vertically revealed a significant effect of anisotropy. In the cyclic tests, the two kinds of samples exhibited an opposite inclination of the effective stress path. Furthermore, the horizontal samples showed a higher stiffness and could sustain a much larger number of cycles to failure. All data of the present study are available from the homepage of the first author. They may serve for the examination, calibration or improvement in constitutive models dedicated to cohesive soils under cyclic loading, or for the development of new models.