Vertical Translation Research Articles

ACCURATE SCALING AND LEVELLING IN UNDERWATER PHOTOGRAMMETRY WITH A PRESSURE SENSOR

Abstract. Photogrammetry needs known geometric elements to provide metric traceable measurements. These known elements can be a distance between two three-dimensional object points or two camera stations, or a combination of known coordinates and/or angles to solve the seven degrees of freedom that lead to rank deficiency of the normal-equation matrix. In this paper we present a novel approach for scaling and levelling to the local vertical direction an underwater photogrammetric survey. The developed methodology is based on a portable low-cost device designed and realized by the authors that uses depth measurements from a high resolution pressure sensor. The prototype consists of a data logger featuring a pressure sensor synchronized with a digital camera in its underwater pressure housing. The modular design, with optical communication and synchronization, provides great flexibility not requiring the camera housing to undergo any hardware modifications. The proposed methodology allows for a full 3D levelling transformation comprising two angles, a vertical translation and a scale factor and can work for surveying scenes extending horizontally, vertically or both. The paper presents the theoretical principles, an overview of the developed system together with preliminary calibration results. Tests in a lake and at sea are reported. An accuracy better than 1:5000 on the length measurement was achieved in calm water conditions.

Sea level rise outpaced by vertical dune toe translation on prograding coasts

Sea level is rising due to climate change and is expected to influence the development and dynamics of coastal dunes. However, the anticipated changes to coastal dunes have not yet been demonstrated using field data. Here, we provide evidence of dune translation that is characterized by a linear increase of the dune toe elevation on the order of 13–15 mm/year during recent decades along the Dutch coast. This rate of increase is a remarkable 7–8 times greater than the measured sea level rise. The observed vertical dune toe translation coincides with seaward movement of the dune toe (i.e., progradation), which shows similarities to prograding coasts in the Holocene both along the Dutch coast and elsewhere. Thus, we suspect that other locations besides the Dutch coast might also show such large ratios between sea level rise and dune toe elevation increase. This phenomenon might significantly influence the expected impact of sea level rise and climate change adaptation measures.

Design and validation of a self-powered device for wireless electronically controlled pneumatic brake and onboard monitoring in freight wagons

Electronically controlled pneumatic (ECP) brake system achieves better brake consistency because of fast braking command transmission, but the practical application is limited by the lack of power transmission in standard railway freight wagons. This paper presents the excitations analysis, design, modelling and experimental validation of a novel self-powered device (SPD) utilizing vertical mechanical energy of freight car for onboard power supply. The device with ball crew, mechanical motion rectifier, gearbox and generator converts the bi-directional vertical translation between the car body and bogie into the unidirectional rotation of generator. The electromechanical coupled model of SPD is established to predict the performance versus different load conditions and train speeds. A peak voltage of 29.3 V and an average power of 50.26 W with 16 Ω external resistance are obtained when the full-loaded vehicle speed is 100 km/h, which indicates the potential of single device to power the wireless ECP brake system and sensor nodes simultaneously. The experiments are carried out and the results are in good agreement with the simulations. Moreover, the SPD adapts well to the broadband characteristics of railcars vertical vibration. The experimental results show that an average power of 4.6 W is achieved even in unfavorable condition. This onboard SPD as distributed power supply in unpowered freight car will realize the popularization of more smart devices and improve the overall performance of heavy-haul trains with long group.

Zero duality gap conditions via abstract convexity

Using tools provided by the theory of abstract convexity, we extend conditions for zero duality gap to the context of non-convex and nonsmooth optimization. Mimicking the classical setting, an abstract convex function is the upper envelope of a family of abstract affine functions (being conventional vertical translations of the abstract linear functions). We establish new conditions for zero duality gap under no topological assumptions on the space of abstract linear functions. In particular, we prove that the zero duality gap property can be fully characterized in terms of an inclusion involving (abstract) -subdifferentials. This result is new even for the classical convex setting. Endowing the space of abstract linear functions with the topology of pointwise convergence, we extend several fundamental facts of functional/convex analysis. This includes (i) the classical Banach–Alaoglu–Bourbaki theorem (ii) the subdifferential sum rule, and (iii) a constraint qualification for zero duality gap which extends a fact established by Borwein, Burachik and Yao (2014) for the conventional convex case. As an application, we show with a specific example how our results can be exploited to show zero duality for a family of non-convex, non-differentiable problems.

Study on the Generalized Displacement Boundary and Its Analytical Prediction for Ground Movements Induced by Shield Tunneling

The process of shield tunnel excavation would inevitably cause surrounding ground movement, and excessive displacement in the soil could lead to large deformation and even collapse of the tunnel. The methods estimating convergence deformation around tunnel opening is summarized. Then, a universal pattern of displacement boundary condition around the tunnel cavity is originally introduced, which is solved as the combination of three fundamental deformation modes, namely, uniform convergence, vertical translation, and ovalization. The expression for the above-mentioned displacement boundary condition is derived, by imposing which the analytical solution for ground movements, based on the stress function method, is proposed. The reliability and applicability of this proposed solution are verified by comparing the observed data in terms of surface settlement, underground settlement, and horizontal displacement. Further parametric analyses indicate the following: (1) the maximum settlement increases linearly with the gap parameter and the tunnel radius, while it is negatively related to the tunnel depth; (2) the trough width parameter is independent of the gap parameter and the radius, while it is proportional to the tunnel depth. This study provides a new simple and reliable method for predicting ground movements induced by shield tunneling.

A comparison between two different immobilization devices for radiation therapy treatment of pelvic cancer using VMAT

ObjectivesTo assess setup reproducibility of low kneefix with feetfix (LKF-FF) system and its operator-reported convenience by reference to low dual leg positioner (LDLP), among patients treated with pelvic radiotherapy. MethodsA retrospective controlled trial was carried out at the radiotherapy unit. It included patients who underwent radical radiotherapy to the pelvis using VMAT, and who benefitted from LDLP (N = 30) or LKF-FF (N = 30) immobilization system. Average absolute shifts (AAS) and total vector errors (TVE) were computed and compared between the two systems, using translational (lateral, longitudinal and vertical) and rotational (X, Y and Z planes) directions. Accuracy rates were computed on pooled data including 1529 VMAT images, 819 in LDLP and 710 in LKF-FF groups, using different cutoffs. Radiotherapists' subjective assessment of the device's ease of setup, handling, cleaning, and storage, and patient comfort was carried out comparatively between the two devices. ResultsNo statistically significant difference was observed between the two systems in systematic settings, while LKF-FF outperformed LDLP in random settings; notably in vertical translation and X and Z rotational shifts. Analysis of TVEs showed significant decrease in rotational TVE in LKF-FF group (mean=1.38° versus 2.38, p = 0.003) by reference to LDLP, respectively; however, both systems had comparable translational TVE (p = 0.590). In pooled analysis, LKF-FF enabled an overall increase in setup accuracy rates in rotational directions by up to 15% and 19% at ±1° and ±2° accuracy levels, respectively (p<0.05). Subjective assessments showed that the two immobilization systems were comparable regarding all investigated dimensions; however, the overall radiotherapists’ preference leaned toward LDLP. ConclusionThe newly implemented LKF-FF system outperformed LDLP in terms of setup reproducibility, notably in rotational directions, where it enhanced setup accuracy rates by up to 19%. Long-term use of LKF-FF may improve the users’ satisfaction.

A Common Space Approach to Comparative Neuroscience.

Comparative neuroscience is entering the era of big data. New high-throughput methods and data-sharing initiatives have resulted in the availability of large, digital data sets containing many types of data from ever more species. Here, we present a framework for exploiting the new possibilities offered. The multimodality of the data allows vertical translations, which are comparisons of different aspects of brain organization within a single species and across scales. Horizontal translations compare particular aspects of brain organization across species, often by building abstract feature spaces. Combining vertical and horizontal translations allows for more sophisticated comparisons, including relating principles of brain organization across species by contrasting horizontal translations, and for making formal predictions of unobtainable data based on observed results in a model species.

The role of vestibular cues in postural sway.

Controlling posture requires continuous sensory feedback about body motion and orientation, including from the vestibular organs. Little is known about the role of tilt vs. translation vs. rotation vestibular cues. We examined whether intersubject differences in vestibular function were correlated with intersubject differences in postural control. Vestibular function was assayed using vestibular direction-recognition perceptual thresholds, which determine the smallest motion that can be reliably perceived by a subject seated on a motorized platform in the dark. In study A, we measured thresholds for lateral translation, vertical translation, yaw rotation, and head-centered roll tilts. In study B, we measured thresholds for roll, pitch, and left anterior-right posterior and right anterior-left posterior tilts. Center-of-pressure (CoP) sway was measured in sensory organization tests (study A) and Romberg tests (study B). We found a strong positive relationship between CoP sway and lateral translation thresholds but not CoP sway and other thresholds. This finding suggests that the vestibular encoding of lateral translation may contribute substantially to balance control. Since thresholds assay sensory noise, our results support the hypothesis that vestibular noise contributes to spontaneous postural sway. Specifically, we found that lateral translation thresholds explained more of the variation in postural sway in postural test conditions with altered proprioceptive cues (vs. a solid surface), consistent with postural sway being more dependent on vestibular noise when the vestibular contribution to balance is higher. These results have potential implications for vestibular implants, balance prostheses, and physical therapy exercises.NEW & NOTEWORTHY Vestibular feedback is important for postural control, but little is known about the role of tilt cues vs. translation cues vs. rotation cues. We studied healthy human subjects with no known vestibular pathology or symptoms. Our findings showed that vestibular encoding of lateral translation correlated with medial-lateral postural sway, consistent with lateral translation cues contributing to balance control. This adds support to the hypothesis that vestibular noise contributes to spontaneous postural sway.

The ligamentous injury pattern in acute acromioclavicular dislocations and its impact on clinical and radiographic parameters

Acromioclavicular (AC) joint dislocations are classified according to the Rockwood (RW) classification, which is based on radiographic findings. Several authors have suggested magnetic resonance imaging (MRI) for visualization of the capsuloligamentous structures stabilizing the AC joint. The aim of this study was to describe the ligamentous injury pattern in acute AC joint dislocations by MRI and investigate associations with clinical and radiographic parameters. This prospective study included 45 consecutive patients (5 women and 40 men; mean age, 33.6 years [range, 19-65 years]) with an acute AC joint separation (RW type I in 5, RW type II in 8, RW type III in 18, and RW type V in 14). All patients underwent physical examination of both shoulders, and clinical scores (Subjective Shoulder Value, Constant score, Taft score, and Acromioclavicular Joint Instability Score) were used to evaluate the AC joint clinically as well as radiographically. Post-traumatic radiography included bilateral anteroposterior stress views and bilateral Alexander views to evaluate vertical instability and dynamic posterior translation. MRI was performed for assessment of the AC and coracoclavicular (CC) ligaments and the delto-trapezoidal fascia. Radiographic and MRI classifications were concordant in 23 of 45 patients (51%), whereas 22 injuries (49%) were misjudged; of these, 6 (13%) were reclassified to a more severe type and 16 (36%), to a less severe type. The integrity of the CC ligaments was found to have a clinical impact on vertical as well as horizontal translation determined by radiographs and on clinical parameters. Among patients with an MRI-confirmed complete disruption of the CC ligaments, 68% showed a radiographic CC difference > 30% and 75% showed complete dynamic posterior translation. Inferior clinical parameters were noted in these patients as compared with patients with intact CC ligaments or partial disruption of the CC ligaments (Constant score of 67 points vs. 49 points [P < .05] and Acromioclavicular Joint Instability Score of 51 points vs. 23 points [P < .05]). The inter-rater and intra-rater reliability for assessment of the ligamentous injury pattern by MRI was fair to substantial (r = 0.37-0.66). The integrity of the CC and AC ligaments found on MRI has an impact on clinical and radiographic parameters.

Dosimetric impact of intrafraction prostate rotation and accuracy of gating, multi-leaf collimator tracking and couch tracking to manage rotation: An end-to-end validation using volumetric film measurements

Background and purposeBoth gating and tracking can mitigate the deteriorating dosimetric impact of intrafraction translation during prostate stereotactic body radiotherapy (SBRT). However, their ability to manage intrafraction rotation has not yet been thoroughly investigated. The dosimetric accuracy of gating, MLC tracking and couch tracking to manage intrafraction prostate rotation was investigated. Materials and methodsTreatment plans for end-to-end tests of prostate SBRT with focal boosting were generated for a dynamic anthropomorphic pelvis phantom. The phantom applied internal lateral rotation (up to 25°) and coupled vertical and longitudinal translation of a radiochromic film stack that was used for dose measurements. Dose was delivered for each plan while the phantom applied motion according to three typical prostate motion traces without compensation (i), with gating (ii), with MLC tracking (iii) or with couch tracking (iv). Measured doses for the four motion compensation strategies were compared with the planned dose in terms of γ-index analysis, target coverage and organs at risk (OAR) sparing. ResultsIntrafraction rotation reduced the 3%(global)/2mm γ-index passing rate (γPR) for the prostate target volume by median (range) –33.2% (−68.6%, −4.1%) when no motion compensation was applied. The use of motion compensation improved the γPR by 13.2% (−0.4%, 32.9%) for gating, by 6.0% (−0.8%, 27.7%) for MLC tracking and by 11.1% (1.2%, 22.9%) for couch tracking. The three compensation techniques improved the target coverage in most cases. Gating showed better OAR sparing than MLC tracking or couch tracking. ConclusionsCompensation of intrafraction prostate rotation with gating, MLC tracking and couch tracking was investigated experimentally for the first time. All three techniques improved the dosimetric accuracy, but residual motion-related dose errors remained due to the lack of rotation correction.

In vivo intervertebral kinematics and disc deformations of the human cervical spine during walking

The kinematics of the cervical spine during various functional neck motions has been widely reported. However, no data has been reported on the cervical intervertebral kinematics during walking, the most frequently performed daily functional activity. In this study, we evaluated cervical kinematics and disc deformation of asymptomatic subjects during a gait cycle using a dual fluoroscopic imaging system. Our measurements showed that the vertical translation of the cervical spine (1.6 ± 0.1 Hz) occurred at twice the frequency of the gait cycle (0.8 ± 0.1 Hz). The overall ranges of motion (ROMs) of the entire (C2-T1) cervical spine were 5.0 ± 3.1° in the flexion-extension rotation, 3.4 ± 1.0° in the lateral-bending rotation, and 5.8 ± 2.1° in the axial-twisting rotation during walking. Each intervertebral disc (measured at the disc centre location) dynamically deformed in its axial direction in a range of 16.2 ± 5.7% ~ 23.7 ± 8.7% (without significant differences among different segment levels, p > 0.05), similar to the ranges of shear deformations of the same disc (p > 0.05, except for the C7-T1 disc, where p = 0.010). These data could be useful for improvements of diagnosis and treatment methods of cervical pathologies.

Kinematic effects of the circle with and without rider in walking horses.

BackgroundBiomechanical studies of walk, especially walk on the circle, are scarce, while circles or curved tracks are frequently used during equestrian activities. To study horse–rider–circle interactions on the circle, the first steps would be to investigate how the unridden, freely walking horse is influenced by circular movement, and then add a rider. The aim was to study horse vertical trunk movements, and sagittal cannon angles (protraction–retraction) during walk in straight-line and on the circle without rider, and on the circle with a rider using minimal influence.MethodsTen horses were ridden by five riders, summing to 14 trials. Each trial included straight walk unridden (on concrete), and walk on 10 m diameter circles (left and right on soft surface) first lunged (unridden) and then ridden with minimal rider influence. Inertial measurement units (100 Hz) were positioned on the withers, third sacral vertebra (S3) and laterally on metacarpal and metatarsal bones (using self-adhesive bandage). Selected data were split in steps (withers and S3 vertical translations) or strides (cannon protraction–retraction) at maximum hind limb protraction, and range of motion (ROM), minima and maxima, and their timing, were extracted. Data were analyzed using mixed models with inner/outer/straight nested within unridden/ridden as fixed effect, and controlling for stride duration. Differences between: inner vs outer steps/limbs; the same step/limb unridden vs ridden; and the same step/limb straight vs inner/outer unridden; were examined for statistical significance at p < 0.05.ResultsInner limbs had smaller cannon ROM than outer limbs, for example, forelimbs when ridden (inner vs outer 62° vs 63°) and hind limbs when unridden (53° vs 56°). Forelimb cannon ROM was the largest for straight (65°). Hind limb ROM for straight walk (55°) was in-between inner (52–53°) and outer hind limbs (56–57°). Vertical ROM of S3 was larger during the inner (unridden/ridden 0.050/0.052 m) vs the outer step (unridden/ridden 0.049/0.051 m). Inner (0.050 m) and outer steps (0.049 m) unridden had smaller S3 ROM compared to straight steps (unridden, 0.054 m). Compared to when unridden, withers ROM was smaller when ridden: inner hind steps unridden/ridden 0.020 vs 0.015 m and outer hind steps 0.020 vs 0.013 m. When ridden, withers ROM was larger during the inner hind step vs the outer.ConclusionThe outer hind limb had greater cannon pro-retraction ROM, compared to the inner limb. Larger croup ROM during the inner step appears to be coupled to increased retraction of the outer hind limb. Knowledge of magnitudes and timing of the horse’s movements on the circle in unridden and ridden walk may stimulate riders to educate eye and feel in analyzing the execution of circles, and stimulate further studies of the walk, for example, on interactions with rider influence, natural horse asymmetries, or lameness.

Experiments on fall of open tori

Fall of open tori horizontally dropped in quiescent water is experimentally investigated. The fall is controlled by the Galileo number, the torus aspect ratio and the solid to fluid density ratio. The dependence of the descent velocity and of the drag coefficient on the control parameters is first analyzed. As the control parameters are varied, vertical translation, zigzagging and spiraling descent are observed. These different descent modes are characterized and a phase diagram of the falling tori are presented as function of the three control parameters.

Multibody System with Elastic Connections for Dynamic Modeling of Compactor Vibratory Rollers

The dynamic model of the system of bodies with elastic connections substantiates the conceptual basis for evaluating the technological vibrations of the compactor roller as well as of the parameters of the vibrations transmitted from the vibration source to the remainder of the equipment components. In essence, the multi-body model with linear elastic connections consists of a body in vertical translational motion for vibrating roller with mass m1, a body with composed motion of vertical translation and rotation around the transverse axis passing through its weight center for the chassis of the car with mass m and the moment of mass inertia J and a body of mass m’ representing the traction tire-wheel system located on the opposite side of the vibrating roller. The study analyzes the stationary motion of the system of bodies that are in vibrational regime as a result of the harmonic excitation of the m mass body, with the force F(t)= m0rω2sinωt, generated by the inertial vibrator located inside the vibrating roller. The vibrator is characterized by the total unbalanced m0 mass in rotational motion at distance r from the axis of rotation and the angular velocity or circular frequency ω.

Bristle Motion, Forces, and Related Vertical Translation for a Novel Electric Toothbrush Design

This paper presents a combination of theoretical and experimental techniques applied to characterize the bristle motion, forces, and related vertical translation for a novel electric toothbrush design with a linear drive system. Results of the theoretical description, based on a single filament, were successfully compared with laboratory-based investigations: force measurements and high-speed video analysis, and tracking the toothbrush motion. This work describes the vertical translation induced in the toothbrush head, of up to 250 μm, when the toothbrush bristles are applied against a contact surface at brushing loads of approximately 1 N to 2.5 N. Using these techniques, including Fast-Fourier transform analysis, it is shown that the vertical motion of the head is composed of the driving frequency and its harmonics.

Impedance functions of a strip foundation in presence of a trench

The influence of a trench in the behaviour of a rigid, strip foundation is numerically investigated under the prism of impedance functions. Both the soil and the foundation are simulated by 2-D plane strain elements. The soil half-space finite element model is truncated using absorbing boundaries. The foundation has three degrees of freedom: vertical and horizontal translation and rotation. Therefore, the foundation is excited by: vertical and horizontal force and moment loading for various frequencies. The corresponding displacements are generated by the finite element code. Finally, a 3 × 3 impedance matrix is calculated in the frequency domain applying FFT (Fast Fourier Transform). The vertical translation is uncoupled, whilst the horizontal translation and rotation are coupled. Various cases of are examined, where is distance between the mid-point of the strip foundation and the mid-point of the trench and is the foundation’s half-width. The finite element model is validated for: screening of waves; impedance functions. Parametric analyses are conducted for a three-degree of freedom system. The existence of an open trench significantly affects the behaviour of the foundation. The foundation’s response depends on: the superstructure; the foundation’s inertia; the distance and type of the trench.

Validation of a patient-specific system for mandible-first bimaxillary surgery: ramus and implant positioning precision assessment and guide design comparison

In orthognathic surgery, the use of patient-specific osteosynthesis devices is a novel approach used to transfer the virtual surgical plan to the patient. The aim of this study is to analyse the quality of mandibular anatomy reproduction using a mandible-first mandibular-PSI guided procedure on 22 patients. Three different positioning guide designs were compared in terms of osteosynthesis plate positioning and mandibular anatomical outcome. PSIs and positioning guides were designed according to virtual surgical plan and 3D printed using biocompatible materials. A CBCT scan was performed 1 month after surgery and postoperative mandibular models were segmented for comparison against the surgical plan. A precision comparison was carried out among the three groups. Correlations between obtained rami and plates discrepancies and between planned rami displacements and obtained rami discrepancies were calculated. Intraoperatively, all PSIs were successfully applied. The procedure was found to be accurate in planned mandibular anatomy reproduction. Different guide designs did not differ in mandibular outcome precision. Plate positional discrepancies influenced the corresponding ramus position, mainly in roll angle and vertical translation. Ramus planned displacement was found to be a further potential source of inaccuracy, possibly due to osteosynthesis surface interference.

Long Range Six Degree-of-Freedom Magnetic Levitation Using Low Cost Sensing and Control

We have developed a magnetic levitation system which uses an array of cylindrical actuation coils and a set of three position sensing photodiode assemblies for controlled levitation of a moving platform of permanent magnets. The novelty of this system is that low cost, standard off-the-shelf commodity hardware and software components are used for position sensing and feedback control, rather than costly motion tracking sensing systems and controllers. The design and function of the system are described and controlled motion in all directions is demonstrated through motion ranges of 30 mm horizontal and 20 mm vertical translation, and 26° of roll and 43° of yaw rotation.

Quick image stitching algorithm based on template matching for Mask defect detection

With the computer technology and image processing technology gradually applied to the mask detection system, computer vision detection method has become the mainstream way of automatic mask inspection. Masking is usually a large area, and in order to ensure detection accuracy, the camera’s field of view is small, and the panorama stitching of mask images has become an essential image processing link in defect detection. In the mask image acquisition system, the precision workbench is in the working mode of horizontal vertical translation, and the adjacent two images have horizontal and vertical offsets. In view of the characteristics of big data volume of mask image, cell repetition, small variation of rotation scale, this paper proposes a fast multi-mask image stitching algorithm based on template matching. The template matching algorithm is optimized, compared with the traditional image stitching algorithm, which greatly improves the stitching speed, avoids the problem of feature matching repeated graphics mismatch, and the stitching effect is good.

Temporal comparison of construction sites using photogrammetric point cloud sequences and robust phase correlation

Registration of multi-temporal data is an important task when conducting construction monitoring and analysis using 3D point clouds acquired at different time points. However, due to the complexity of scenes in construction sites and the intrinsic attributes of the datasets (e.g., noise, outliers, and uneven densities), the registration of multi-temporal datasets is a challenging task. To this end, in this paper, we propose a fast and marker-free method for coarse registration of multi-temporal point clouds by integrating a projection-based strategy with Fourier-based signal matching methods, consisting of three major steps: decoupling of 3D transformation with projection-based dimensionality reduction, estimation of horizontal transformation by matching 2D horizontally projected images, and estimation of vertical translation by matching 1D vertical signals. In the decoupling step, the principal projection plane is firstly identified through a robust plane fitting method. Then, each point cloud is decomposed into two independent parts according to the estimated projection plane, namely a 2D image and a 1D signal. The 2D image is obtained by mapping 3D points to the principal projection plane along the vertical direction. Correspondingly, the 1D signals are attained through projecting 3D points to the principal axis in the horizontal direction. In the following step, the rotation, scaling, and translation parameters between 2D images of different point clouds are decoupled with Fourier-Mellin transform. These transformation parameters are then solved with a robust 2D phase correlation algorithm. Simultaneously, 1D signals of non-registered point clouds are matched with a robust 1D phase correlation approach. Finally, combining estimated transformation parameters from both 2D images and 1D signals, the multi-temporal point clouds can be efficiently registered. Our registration method is tested using one TLS benchmark dataset and two multi-temporal point cloud sequences from different construction sites to validate the versatility and effectiveness of the proposed workflow. In terms of the registration accuracy, our proposed method can achieve satisfying performance, with accurate registration for both rotation and translation estimation.