Tip Movement Research Articles

Deep imitator: Handwriting calligraphy imitation via deep attention networks

Calligraphy imitation (CI) from a handful of target handwriting samples is such a challenging task that most of the existing writing style analysis or handwriting generation methods do not exhibit satisfactory performance. In this paper, we propose a novel multi-module framework to address the problem of CI. Firstly, we utilized a deep convolution neural network (CNN) to extract personalized calligraphical features. Then we built a calligraphy-clustering attention module and a mata-style matrix (msM) to compute an embedding of calligraphy. The structure of conditional gated recurrent unit (cGRU) is then improved to predict the probabilistic density of pen tip movement displacement by dual condition inputs. Finally, we generated personalized handwriting stroke sequences through iterative sampling with Gaussian mixture model (GMM). Experiments on public online handwriting databases verify that the proposed method could achieve satisfactory performance; the generated samples achieved high similarities with original handwriting examples.

Electric wheelchair with forward-reverse control using electromyography (EMG) control of arm muscle

Muscle dystrophy can occur in the body’s organs of human movements such as the legs, thighs, upper arms, palms and fingers of humans so that the sufferer cannot use limbs. Electric wheelchair is not effective for people with muscle dystrophy disabilities, because users have limitations such as defect of the hands. Given these circumstances, this research proposes an electric wheelchair with controlled by electromyography (EMG) which is placed on the arm muscles. This Electric wheelchair use 2-channel electrodes for sampling muscle signal. This research was conducted in Balai Besar Rehabilitasi Sosial Penyandang Disabilitas Fisik (BBRSPDF) Surakarta, Indonesia. The results of the first grip strength testing are less than 35.8 kgf that indicates weakness of the hand grip. The same thing in the second treatment is a weakness in the handle because of n less than 35.8 kgf. The result of robustness test, spherical movement is not robust with a value 0.756 and. 0.000. The result of cylindrical movement is fully robust with a value 0.001 and 0.000. The result of lateral movement is fully robust with a value 0.000 and 0.000. The result of tip movement is fully robust with a value 0.000 and 0.029. The result of hook movement is not robust with a value 0.109 and 0.000.

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ИСПЫТАНИЯ ПАДАЮЩИМ ГРУЗОМ ВЯЗКОЙ ТРУБНОЙ СТАЛИ ПРИ ТРЕХТОЧЕЧНОМ ИЗГИБЕ

The processes in the metal sample of a supply pipeline realized under drop-weight tests (DWT, or DWTT according to ASTM) are studied. DWT is a proof test of the pipeline metal that should ensure high resistance of the pipeline against extensive destruction. Numerical simulation of DWT with the steel sample of full thickness was performed; the steel had К65 strength grade. Parallel finite-element computer code DANCO developed in RFNC-VNIIEF was used for simulations. A detailed description of the rupture formation process required a fine-enough mesh and a supercomputer. To carry out the numerical simulation of the process, the constants of the deformation diagram were used, obtained on the basis of static and dynamic tensile tests of samples at room temperature. A modified Gurson–Tvergaard–Niedelman (GTNm) model for macro-viscous steel destruction (ductile failure) was used to describe the strain and the destruction of the metal. The modification makes it possible to describe direct and oblique cuts and their combinations in case of ductile failure of small-size objects (rods, plates, shells). The calculated dependences of the movement of the crack tip on the movement of the load and the resistance force of the sample on the movement of the crack tip are presented. We have got a good agreement between the computations and experimental data with regard to the “force–displacement” strength parameter, the deformed profiles and macro-geometry of the ruptured sample after the tests. The computation results reveal the mechanics of the crack origination, start and propagation in the sample, describe the plastic-flow energy distribution in the process of dynamic destruction. The results of the work can be used in the development of the requirements and of the implementation conditions of the “tooled” DWT, and for numerical simulation of the extensive destruction at the main pipeline.

Pen tip force and movement based estimation of physical workload in handwriting tasks

Pen tip force and movement based estimation of physical workload in handwriting tasks

Decoding fluid droplet generation during phacoemulsification and pars plana procedures in the COVID-19 era—An experimental study

Purpose:The purpose of this study is to evaluate fluid droplet spray generation during phacoemulsification (PE), pars plana vitrectomy (PPV), and fragmatome lensectomy (FL) and assess factors affecting these.Methods:This is an experimental study. PE through 2.2 and 2.8 mm incisions was performed in six goat eyes and four simulator eyes using both continuous and interrupted ultrasound (U/S). PPV and FL were performed in three goat eyes. Generation of visible fluid droplet spray was analyzed from video recordings through the microscope camera and an external digital camera. Hydroxypropylmethylcellulose (HPMC) was applied over the incision site during PE and FL.Results:When PE was performed through both incision sizes, there was no visible fluid droplet spray if the phaco tip was centered in the incision, without sleeve compression. When there was phaco tip movement with the phaco sleeve sandwiched between the tip and the incision wall, there was visible fluid droplet spray generation. It was more difficult to induce fluid droplet spray with 2.8 mm incision, and spray was lesser with interrupted U/S. During PPV, there was no droplet spray. During FL, fluid droplet spray was only seen when U/S was delivered with the fragmatome tip close to the sclerotomy. HPMC impeded droplet spray.Conclusion:Fluid droplet generation during PE can be minimized to a large extent by keeping the phaco tip centered within the incision, avoiding sleeve compression. Smaller incision and continuous U/S were more prone to droplet generation. FL should be performed away from sclerotomy. HPMC over incision is recommended.

Modelling fungal growth with fractional transport models

Due to the network-shaped colony formed by the filamentous fungi, fractional operators are likely to capture the time-evolution of their biomass distribution. In this paper, a generalised fractional transport model is developed to simulate the colony growth of a wood-rot fungus, Postia placenta. The colony is described by two variables, active and inactive biomass. The active biomass corresponds to the tips and the “active points”, responsible for biomass formation, while the inactive component represents the remaining biomass, which is assumed immobile. The fractional in time and space derivatives are applied to the active biomass to represent the spatial colonisation (i.e., tip movement). The proliferation of biomass (local densification of the network due to branching) is driven by a source term, while a portion of active biomass becomes inactive over time. The model is solved using an extended finite volume discretisation scheme and the accuracy is confirmed by comparison to an analytic solution obtained for the case where the source term is assumed linear. Next, the model parameters are identified for an optimized solution of the model that matches experimental observations well, indicating the suitability of the fractional operators for modelling biomass diffusion in a fungal colony. An interesting finding is that the best results are obtained when only anomalous diffusion in space (not time) is considered, which is probably related to the fractal dimension of mycelia. The spatial fractional–order derivative provides a unique ability to capture the non-local biomass diffusion of the fungal colony. We postulate that the fractional indices may provide a form of biological marker for the growth characteristics of different fungal species.

A Compression Valve for Sanitary Control of Fluid-Driven Actuators.

With significant research focused on integrating robotics into medical devices, sanitary control of pressurizing fluids in a precise, accurate and customizable way is highly desirable. Current sanitary flow control methods include pinch valves which clamp the pressure line locally to restrict fluid flow; resulting in damage and variable flow characteristics over time. This paper presents a sanitary compression valve based on an eccentric clamping mechanism. The proposed valve distributes clamping forces over a larger area, thereby reducing the plastic deformation and associated influence on flow characteristic. Using the proposed valve, significant reductions in plastic deformation (up to 96%) and flow-rate error (up to 98%) were found, when compared with a standard pinch valve. Additionally, an optimization strategy presents a method for improving linearity and resolution over the working range to suit specific control applications. The valve efficacy has been evaluated through controlled testing of a water jet propelled low-cost endoscopic device. In this case, use of the optimized valve shows a reduction in the average orientation error and its variation, resulting in smoother movement of the endoscopic tip when compared to alternative wet and dry valve solutions. The presented valve offers a customizable solution for sanitary control of fluid driven actuators.

Colorectal cancer prevention by a CLEAR principles–based colonoscopy protocol: an observational study

Colorectal cancer (CRC) prevention by colonoscopy has been lower than expected. We studied CRC prevention outcomes of a colonoscopy protocol based on Clean the colon, Look Everywhere, and complete Abnormality Removal (CLEAR) principles. This observational follow-up study studied patients provided screening colonoscopy at a free-standing private ambulatory surgery center in South Carolina by 80 endoscopists from October 2001 to December 2014, followed through December 2015. The colonoscopy protocol, optimized for polyp clearance, featured in-person bowel preparation instructions reinforced by phone, polyp search and removal throughout insertion and gradual withdrawal with circumferential tip movements, and a team approach using all personnel present to maximize polyp detection, patient safety, and clear-margin polypectomy including requesting repeat inspection or additional tissue removal. Outcome measures were postscreening lifetime CRC risk relative to Surveillance Epidemiology and End Results (SEER)-18 and interval cancer rate (postcolonoscopy CRCs among cancer-free patients at screening). Of 25,862 patients (mean age, 58.1 years; 52% black; 205,522 person-years of observation), 159 had CRC at screening and 67 patients developed interval CRC. The interval CRC rate was 3.34 per 10,000 person-years of observation, 5.79 and 2.24 among patients with and without adenomas, respectively. The rate was similar among older patients (mean age 68.5 years at screening) and with prolonged follow-up. Postscreening lifetime CRC risk was 1.6% (bootstrap 95% confidence interval, 1.3%-1.8%) versus 4.7% in SEER-18, 67% lower. Subgroups with mean screening ages of 50 and 68.5 years showed risk reductions of 80% and 72%, respectively. The adverse event rate was less than usually reported rates: perforation 2.6 per 10,000, bleeding with hospitalization 2.4 per 10,000, and no deaths. A colonoscopy protocol optimized for polyp clearance prevented 67% of CRC compared with a SEER-18 population given ongoing population screening.

Force modeling to develop a novel method for fabrication of hollow channels inside a gel structure.

Fabrication of hollow channels with user-defined dimensions and patterns inside viscoelastic, gel-type materials is required for several applications, especially in biomedical engineering domain. These include objectives of obtaining vascularized tissues and enclosed or subsurface microfluidic devices. However, presently there is no suitable manufacturing technology that can create such channels and networks in a gel structure. The advent of three-dimensional bioprinting has opened new possibilities for fabricating structures with complex geometries. However, application of this technique to fabricate internal hollow channels in viscoelastic material has not been yet explored to a great extent. In this article, we present the theoretical modeling/background of a proposed manufacturing paradigm through which hollow channels can be conveniently fabricated inside a gel structure. We propose that a tip connected to a robotic arm can be moved in X-, Y-, and Z-axis as per the desired design. The tip can be moved by a magnet or mechanical force. If the tip is further trailed with porous tube and moved inside the viscoelastic material, corresponding internal channels can be fabricated. To achieve this, however, force modeling to understand the forces that will be required to move the tip inside viscoelastic material should be known and understood. Therefore, in our first attempt, we developed the computational force modeling of the tip movement inside gels with different viscoelastic properties to create the channels.

Toward a Better Understanding of Crack Growth in Nickel-Cast Alloys Under Creep-Fatigue and Thermo-Mechanical Fatigue Conditions

Abstract To ensure the feasibility of gas turbines, despite rising commodity prices and emission restrictions, an enhancement of both their efficiency and flexibility is necessary. The consequential higher loading of components at high temperature conditions calls for an increased use of damage tolerant design approaches. To still guarantee a safe operation, a sound understanding and reliable estimations for crack growth under service conditions are indispensable. In this paper, the results from several projects in this field conducted at the TU Darmstadt and involved partners are summarized to identify and describe the various influences on crack growth under creep-fatigue and thermo-mechanical fatigue (TMF) loading. The activation of damage mechanisms under TMF loading and interactions between them is dependent on the temperature cycle and the respective load phasing. Depending on the type of loading (force versus strain control), contrary influences of the phase shift on the TMF crack growth rates are found. This can partially be attributed to the differences in mean stress evolution. Crack initiation and propagation under creep-fatigue and TMF conditions are also often connected with significant scattering of initiation sites and crack growth rates. One reason for this nonuniform behavior is the interaction of geometric discontinuities with the microstructure. To investigate the role of the local grain structure for crack initiation and propagation, in situ observation techniques for crack tip movement and local strain fields were applied. Harsh gradients in the local deformation behavior were identified as origins of secondary crack initiation. To describe crack growth under creep-fatigue and TMF conditions, the linear accumulation model “O.C.F.” was developed. It is based on the contributions of fatigue, creep, and oxidation to crack growth per load cycle. This model is capable of reproducing the effects of time-dependent damage, different load ratios, TMF phase shifts, as well as component geometry. Substantial advantages of this method are its independence from empiric correction factors to assess changing load cycle forms and the possibility to give analytic estimations without the need of extensive data processing. The model is currently validated for three nickel cast alloys, also including single-crystalline and directionally solidified cast variants, different creep-fatigue and TMF loading scenarios, and crack geometries. The model's linear formulation allows assessing the dominant driver of crack growth at each stage of an experiment. These predictions are compared with fractographic investigations and in situ observations of crack paths to identify the mechanisms of crack growth under different TMF load cycle forms.

Velocity-dependent friction enhances tribomechanical differences between monolayer and multilayer graphene

The influence of sliding speed in the nanoscale friction forces between a silicon tip and monolayer and multilayer graphene were investigated with the use of an atomic force microscope. We found that the friction forces increase linearly with the logarithm of the sliding speed in a highly layer-dependent way. The increase in friction forces with velocity is amplified at the monolayer. The amplification of the friction forces with velocity results from the introduction of additional corrugation in the interaction potential driven by the tip movement. This effect can be interpreted as a manifestation of local thermally induced surface corrugations in nanoscale influencing the hopping dynamics of the atoms at the contact. These experimental observations were explained by modeling the friction forces with the thermally activated Prandtl-Tomlinson model. The model allowed determination of the interaction potential between tip and graphene, critical forces, and attempt frequencies of slip events. The latter was observed to be dominated by the effective contact stiffness and independent of the number of layers.

Thermo-mechanically coupled modelling of a single-asperity scratch on an isotropic isotactic polypropylene surface

Abstract Isotactic polypropylene (iPP) is a low cost semi-crystalline polymer that is easy to process, has a wide variety in properties and is, therefore, used in many applications. Many of these applications require enhanced wear-resistance to prolong the lifetime of the product. Essential is to first investigate the intrinsic response of the material in order to describe its friction and wear response. In this respect, a hybrid experimental-numerical approach is used to couple the intrinsic response to the single-asperity scratch response. The numerical model used is a 3D elasto-viscoplastic model based on the Eindhoven Glassy Polymer (EGP) model. For the first time a coupled thermo-mechanical EGP model is implemented in a Finite Element Method (FEM)-framework. The model is capable of accurately describing the intrinsic response of the material, which opens the door to qualitatively and quantitatively describe its frictional response and understand the damage formation mechanism (i.e. the initiation of wear). In this study, α- and β-phase iPP are studied. We show that the difference in the intrinsic response between the two phases has a significant influence on the friction and wear response. Moreover, a stick-slip phenomenon is proven to be the main responsible for the damage mechanism observed. The observed periodic “fish-scale” damage pattern results from periodic changes in resistance during the tip movement. A relation between the polymer intrinsic response and the damage formation mechanism is established. The influence of the applied load and scratch speed on damage formation is investigated as well.

Expert Surgeons Can Smoothly Control Robotic Tools With a Discrete Control Interface

Objective assessment of surgical skill is gaining traction in a number of specialty fields. In robot-assisted surgery in particular, the availability of data from the operating console and patient-side robot offers the potential to derive objective metrics of performance based on tool movement kinematics. While these techniques are becoming established in the laparoscopic domain, current assessment techniques for robotic endovascular surgery are based primarily on observation, checklists, and grading scales. This work presents an objective and quantitative means of measuring technical competence based on analysis of the kinematics of endovascular tool tip motions controlled with a robotic interface. We designed an experiment that recorded catheter tip movement from 21 subjects performing fundamental endovascular robotic navigation tasks on a physical model. Motion-based measures of smoothness (spectral arc length and number of submovements) were computed and tested for correlation with subjective scores from a global rating scale assessment tool that has been validated for use when performing manual catheterization. Results show that the smoothness metrics that produced significant correlations with the global rating scale for manual catheterization show similar correlations for robotic catheterization. This finding is notable, since with the robotic interface, tool tip motion is commanded discretely via a control button interface, while in manual procedures the tools are controlled through continuous movements of the surgeon's hands. Logistic regression analysis using a single motion metric was capable of classifying subjects by expertise with better than 90% accuracy. These objective and quantitative metrics that capture movement quality could be incorporated into future training protocols to provide detailed feedback on trainee performance.

High-Definition Zoom Mode: A High Resolution X-ray Microscope for Neurointerventional Treatment Procedures.

Visualization of structural details of treatment devices during neurointerventional procedures can be challenging. A new true two-resolution imaging X-ray detector system features a 194µm pixel conventional flat-panel detector (FPD) mode and a 76µm pixel high-resolution high-definition (Hi-Def) zoom mode in one detector panel. The Hi-Def zoom mode was developed for use in interventional procedures requiring superior image quality over a small field of view (FOV). We report successful use of this imaging system during intracranial aneurysm treatment in 1 patient with a Pipeline-embolization device and 1 patient with a low-profile visualized intramural support (LVIS Blue) device plus adjunctive coiling. A guide catheter was advanced from the femoral artery insertion site to the proximity of each lesion using standard FPD mode. Under magnified small FOV Hi-Def imaging mode, an intermediate catheter and microcatheters were guided to the treatment site, and the PED and LVIS Blue plus coils were deployed. Radiation doses were tracked intraprocedurally. Critical details, including structural changes in the PED and LVIS Blue and position and movement of the microcatheter tip within the coil mass, were more readily apparent in Hi-Def mode. Skin-dose mapping indicated that Hi-Def mode limited radiation exposure to the smaller FOV of the treatment area. Visualization of device structures was much improved in the high-resolution Hi-Def mode, leading to easier, more controlled deployment of stents and coils than conventional FPD mode.

Learning needle tip localization from digital subtraction in 2D ultrasound.

This paper addresses localization of needles inserted both in-plane and out-of-plane in challenging ultrasound-guided interventions where the shaft and tip have low intensity. Our approach combines a novel digital subtraction scheme for enhancement of low-level intensity changes caused by tip movement in the ultrasound image and a state-of-the-art deep learning scheme for tip detection. As the needle tip moves through tissue, it causes subtle spatiotemporal variations in intensity. Relying on these intensity changes, we formulate a foreground detection scheme for enhancing the tip from consecutive ultrasound frames. The tip is augmented by solving a spatial total variation regularization problem using the split Bregman method. Lastly, we filter irrelevant motion events with a deep learning-based end-to-end data-driven method that models the appearance of the needle tip in ultrasound images, resulting in needle tip detection. The detection model is trained and evaluated on an extensive ex vivo dataset collected with 17G and 22G needles inserted in-plane and out-of-plane in bovine, porcine and chicken phantoms. We use 5000 images extracted from 20 video sequences for training and 1000 images from 10 sequences for validation. The overall framework is evaluated on 700 images from 20 sequences not used in training and validation, and achieves a tip localization error of 0.72 ± 0.04mm and an overall processing time of 0.094s per frame (~ 10 frames per second). The proposed method is faster and more accurate than state of the art and is resilient to spatiotemporal redundancies. The promising results demonstrate its potential for accurate needle localization in challenging ultrasound-guided interventions.

Abstract No. 589 Characterizing the extent and impact of catheter tip movement on chest port dysfunction

Abstract No. 589 Characterizing the extent and impact of catheter tip movement on chest port dysfunction

Quantifying the Effect of Repeated Impacts and Lateral Tip Movements on Brain Responses during Controlled Cortical Impact.

Controlled cortical impact (CCI) is a widely used laboratory neurotrauma model to study traumatic brain injury. During CCI, the brain is damaged by an impactor tip, which travels along its axial direction to a pre-defined depth at a pre-set speed. A recent study, however, using high-speed imaging analysis demonstrated that the impactor tip of an electromagnetically driven CCI device experienced repeated impacts and lateral movements, rather than a single axial impact. How these repeated impacts and lateral movements affect internal brain stresses/strains-which are the direct cause of neuronal damage and affect the accuracy and reproducibility of CCI-remains unknown. We use a previously validated, highly detailed three-dimensional finite element (FE) mouse brain model to investigate the effect of repeated impacts and lateral movements on brain responses during CCI. We also measured tip movements of an in-house pneumatically driven CCI and conducted FE simulations. We found that the repeated impacts had minimal effect on peak strains. The lateral movements of the tip, however, greatly increased brain strains and affected large brain regions. Hence, it is necessary to monitor and control lateral movements to ensure the accuracy and reproducibility of CCI.

Is the Human Brain Capable of Controlling Seven Degrees of Freedom?

BackgroundConventional rigid laparoscopic instruments offer five degrees of freedom (DOF). Robotic instruments add two independent DOFs allowing unconstrained directional steering. Several nonrobotic instruments have been developed with the additional DOFs, but with these devices, surgeon's wrist movements are not intuitively transmitted into tip movements. In this study, a new articulated instrument has been evaluated. The aim of the study was to compare learning curves and performances of conventional laparoscopic instruments, the da Vinci system and Steerable devices in a crossover study. Materials and methodsA total of 16 medical students without any laparoscopic experience were trained for 27 h to operate all of a rigid, a robotic, and a new Steerable instrument in a random order. Learning curves and ultimate experience scores were determined for each instrument. Strain in wrist and shoulders was assessed with a visual analog score. ResultsPerforming the suturing task with rigid and robot instruments required 4 h of training, compared with 6 h to master the Steerable instrument. After 9 h of training with each instrument, completing the complex suturing pattern required 662 ± 308 s with rigid instruments, 279 ± 90 s with the da Vinci system, and 279 ± 53 s with the Steerable instrument. Pain scores were significantly higher after using the rigid instruments compared with the Steerable instruments. ConclusionsTransmission of torque and the presence of additional two DOFs in combination with reduced crosstalk significantly improved the instrument dexterity where the Steerable platform is concerned. Although the learning curve is longer, once mastered, it provides enhanced surgical freedom.

Unique interfacial reaction and so-induced change in mechanical performance of Sn–3.0Ag–0.5Cu/Cu solder joints formed during undercooled and eutectic liquid soldering processes

A novel technique is proposed to prepare Sn–3.0Ag–0.5Cu/Cu joints at three different processing temperatures, which are called undercooled liquid (UL, 213.0 °C), eutectic liquid (EL, 217.0 °C) and normal liquid (NL, 231.0 °C) soldering temperatures correspondingly, and each of them is lower than, equal to and higher than Sn–3.0Ag–0.5Cu solder’s melting point (217.0 °C), respectively. The interfacial reaction, intermetallic compound growth and mechanical performance of Sn–3.0Ag–0.5Cu/Cu joints formed during UL, EL and NL soldering processes were investigated systematically. Results show that for Sn–3.0Ag–0.5Cu solder as the undercooled liquid melt or eutectic liquid melt or normal liquid melt in the formation of joints, the thickness of interfacial intermetallic compound (IMC) layer in the joints increases with prolonging dwelling time. For three different liquid soldering processes, the change tendency of the interfacial IMC layer thickness is distinct. For joints formed at UL and EL temperatures, the excessive growth of primary Cu6Sn5 and interfacial IMC (mainly Cu6Sn5) can be suppressed during isothermally dwelling in the liquid state for more than 5 min. Ball shear test results show that solder joints formed at UL and EL temperatures have lower value of the maximum shear force (MSF) than those formed during the NL soldering process. For UL and EL types of joints, the fracture occurs either by shear slide fracture totally along the shear tool tip movement plane (i.e., in-plane shear slide fracture) or by shear slide fracture initially along the shear tool tip movement plane and afterwards shear deformation fracture in the solder matrix under the plane (i.e., out-of-plane shear slide and deformation mixed-mode fracture), while the fracture takes place in NL joints only by in-plane shear slide fracture mode.

Development of a computational model of a lightweight vertical lathe with the use of superelements

Abstract This article presents a process of developing a computational model of a light construction vertical lathe. The model is made using the finite elements method. Due to the complexity of the machine tool and the optimization of the computation time superelements have been used in the model. The application of this method has reduced the computation time allowing the analysis of many variants of the mutual position of the machine components. The results of the analyzes led to the indication of weak links of the machine tool. After the improvement of the machine tool construction the movement of the tool tip and the workpiece was much smaller.