Relative Movement Research Articles

Influence of Process Parameters in LMD for Geometrical Accuracy and Thin Geometry with AISI316L

Laser metal deposition (LMD) industrial use demands research about the influence of the parameters in the built parts density, accuracy and mechanical properties. Especially for the thin-wall parts, knowledge about the correlations between processing parameters and the final result is indispensable. This study explores the relationship between process parameters and the quality of AISI316L stainless steel thin-walled parts produced by LMD. A six-axis robot equipped with a deposition head allowed relative spatial movement between the powder nozzle and laser beam and substrate with high accuracy. Controlled energy input provided by continuous wave Ytterbium fibre laser allows using less material flow rate and the production of thin layers in test samples. Three processing parameters were selected to investigate the effects on part characteristics using a Box-Behnken experimental design. Through this method, each parameter was evaluated between 600 W to 800 W laser power, 6 mm/s to 14 mm/s feedrate and 0.2 mm to 0.4 mm layer thickness. All remaining parameters were fixed using argon to provide an inert atmosphere, 8.8 g/min powder feeding rate and 1.5 mm spot diameter. The method was used to test the manufacture of thin-wall cylindrical specimens with 10 mm in height and 75 mm in diameter. Fabricated AISI316L samples were evaluated regarding the dimensional and geometrical characteristics. It was observed that higher energy input density during the laser additive manufacturing implies lower geometric precision. Feedrate and layer thickness has the highest impact on both the wall thickness and vertical accuracy. Given the inability to produce parts with an acceptable final surface, the process finds great applicability when complemented with additional finishing technologies.

Tectonic implications of the February 2023 Earthquakes (Mw7.7, 7.6 and 6.3) in south-eastern Türkiye

The series of earthquakes that took place on February 6, 2023 caused one of the saddest major calamities in Türkiye. The first major earthquake of magnitude Mw7.7 broke the Pazarcık and Erkenek segments moving north on the East Anatolian Fault Zone (EAFZ) between Türkoğlu and Çelikhan. According to the Coulomb failure criterion, the Pazarcık earthquake (Mw7.7) increased stress on the Sürgü-Çardak Fault, a segment on the north splay of the EAFZ, and nine hours later the Elbistan earthquake (Mw7.6) occurred. This great event ruptured the Çardak Fault, the western part of the E-W trending Sürgü-Çardak Fault between Nurhak and Göksun. The Amanos Fault, which extends from Türkoğlu south to Antakya, broke almost simultaneously to the first Pazarcık earthquake. Similarly, the earthquake that broke the Amanos Fault transferred increased stress to its south-western neighbour, the Cyprus-Antakya Transform Fault, triggering the 6.3 magnitude Samandağ earthquake 14 days later. The February 2023 earthquakes, which caused the collapse of >100,000 buildings and the death of >50,000 people, created surface ruptures hundreds of kilometres in length and caused different displacements on different faults, the two largest of which were 4.6 and 6.7 m. On all the faults where the deadly earthquakes occurred in February 2023, inversion of the focal mechanisms of the earthquakes (main shocks and their aftershocks) indicates a transtensional stress regime, or a change from strike-slip to normal slip. For all strike-slip inversions, the R values are <0.45 indicating transtension. The stress tensors obtained indicate left-lateral movement with normal component on all faults where the earthquakes occurred. The transtensional regime, which is thought to reflect regional tectonics, is the result of forces caused by relative movements of Arabia, eastern Mediterranean and Eurasia.

Photobiomodulation therapy assisted orthodontic tooth movement: potential implications, challenges, and new perspectives.

Over the past decade, dramatic progress has been made in dental research areas involving laser therapy. The photobiomodulatory effect of laser light regulates the behavior of periodontal tissues and promotes damaged tissues to heal faster. Additionally, photobiomodulation therapy (PBMT), a non-invasive treatment, when applied in orthodontics, contributes to alleviating pain and reducing inflammation induced by orthodontic forces, along with improving tissue healing processes. Moreover, PBMT is attracting more attention as a possible approach to prevent the incidence of orthodontically induced inflammatory root resorption (OIIRR) during orthodontic treatment (OT) due to its capacity to modulate inflammatory, apoptotic, and anti-antioxidant responses. However, a systematic review revealed that PBMT has only a moderate grade of evidence-based effectiveness during orthodontic tooth movement (OTM) in relation to OIIRR, casting doubt on its beneficial effects. In PBMT-assisted orthodontics, delivering sufficient energy to the tooth root to achieve optimal stimulation is challenging due to the exponential attenuation of light penetration in periodontal tissues. The penetration of light to the root surface is another crucial unknown factor. Both the penetration depth and distribution of light in periodontal tissues are unknown. Thus, advanced approaches specific to orthodontic application of PBMT need to be established to overcome these limitations. This review explores possibilities for improving the application and effectiveness of PBMT during OTM. The aim was to investigate the current evidence related to the underlying mechanisms of action of PBMT on various periodontal tissues and cells, with a special focus on immunomodulatory effects during OTM.

Pre-clinical characterization of a novel flexible surface stem design for total knee replacements.

Primary stability is crucial for implant osseointegration and the long-term stability of cementless total joint replacements. Biomechanical studies have shown the potential of femoral stems for total knee replacements to reduce micromotions at the bone-implant interface. However, approaches such as focusing on the structural elasticity of the femoral stems are rarely described. Three groups with different femoral stem designs were investigated: group 1: flexible surface stem, group 2: flexible surface stem with open-porous structured lamellas, and group 3: solid stem (reference). The stems were implanted into bone substitute material and dynamically loaded for 1000 cycles. Relative movement and subsidence were measured optically, and axial pull-out forces were determined after dynamic testing. Relative movements increased to 0.10 mm (groups 1 and 2) compared to 0.03 mm (group 3). Subsidence increased to 0.08 mm (group 1) and 0.11 mm (group 2) compared to 0.06 mm (group 3). For each group, subsidence mainly occurred during the first 500 cycles. A similar convergence was observed in the further course. Pull-out forces increased to 1815.0 N (group 1) and 1347.1 N (group 2) compared to 1306.4 N (group 3). The flexible surface stem design resulted in higher relative movements and subsidence, but also exhibited increased pull-out forces. The relative movements were below the critical limit of 0.15 mm and represent a superposition of the elastic deformations of the interacting implant components as well as the micromotion at the bone-implant interface. Therefore, the novel flexible surface stem design appears to offer promising primary implant fixation.

Sleep related rhythmic movement disorder: phenotypic characteristics and treatment response in a paediatric cohort

ObjectiveTo describe phenotypic, polysomnographic characteristics, impact, and treatment response in children with sleep related rhythmic movement disorder (SR-RMD). BackgroundThere is limited research on SR-RMD. We have developed a systematic clinical evaluation of children with SR-RMD to improve understanding and treatment. MethodsA retrospective chart review of 66 children at a UK tertiary hospital. Baseline assessment included validated screening questionnaires to study autism spectrum characteristics, general behaviour and sensory profile. A standardised questionnaire assessed impact on sleep quality and daytime wellbeing of child and family. Polysomnography data were collated. ResultsChildren were aged 0.9–16.3 years (78.8% male). 51.5% had a neurodevelopmental disorder, most commonly autism spectrum disorder. High rates of behavioural disturbance and sensory processing differences were reported, not confined to children with neurodevelopmental disorders. Parents reported concerns about risk of injury, loss of sleep and persistence into adulthood. Daytime wellbeing was affected in 72% of children and 75% of other family members. Only 31/48 children demonstrated rhythmic movements during video-polysomnography, occupying on average 6.1% of time in bed. Most clusters occurred in the settling period but also arose from N1, N2 and REM sleep and wake after sleep onset. Melatonin was prescribed to 52 children, all but one were extended-release preparations. 24/27 children with available data were reported to improve with melatonin. ConclusionsSR-RMD places a significant burden on child and family wellbeing. Our novel findings of sensory processing differences in this population and parent reported therapeutic response to extended-release melatonin offer potential avenues for future research.

Left Upper Limb Deep Venous Thrombosis: A Rare Condition Becoming Common Nowadays

Deep venous thrombosis of the upper limb is a less common phenomenon than lower limb deep vein thrombosis. The commonest reasons are trauma secondary to sport or job related arm movements and arm positions, predisposing for upper limb deep venous thrombosis. In this case report, we will discuss the diagnosis and management of upper limbs deep vein thrombosis, along with review of literature.

Multiorbital DNA walker nanoprobe for portable photothermal detection based on H2S etching of cubic Prussian blue.

In the developedassay, multiorbital 3D DNA walker (MO DNA walker) was applied as signal amplified protocol for enhancing the detection signal of the photothermal biosensor, which was designed for sensitive detection of miRNA based on the H2S triggered conversation of photothermal reagent. When the target molecule is present, the DNA walking strand was released and then hybridize with track strands. The landing of walking particles (WPT) on the tracking particles (TPT) promotes the relative movement of the WPT around TPT, thus releasing large amount of horseradish peroxidase (HRP) with the aid of DNAzyme. After reacting with Na2S2O3 and H2O2, multiple H2S can be generated in situ based on the catalytic ability of HRP. Meanwhile, cubic Prussian blue (CPB) was synthesized and exhibited superior photothermal response, which can be served as efficient photothermal reagent and H2S responsive acceptor. Significantly, the photothermal signal of CPB could be obviously reduced after challenged with H2S ascribed to synchronous reaction between the ferric ion (Fe3+) and H2S. The improved walking area and freedom enable significant signal amplification, enhancing the biosensor's performance. Under ideal circumstances, the proposed photothermal assay demonstrated excellent performance for determination of miRNA-21.

Reducing skid marks on steel slabs by developing an improved design scheme of water beam

Due to the existence of cooling water pipes and thermoduric skids in the walking beam type reheating furnace, skid marks always occur on the bottom of the steel slab and the quality of the steel slab is seriously affected. In this paper, the coupled heat transfer model among steel slab, water beam, furnace gas and furnace walls is established to accurately simulate the reheating process of the steel slab. The discrete ordinates method (DOM) is adopted to solve radiative heat transfer problem in reheating furnace. To get closer to the real situation, the relative movement between steel slab and thermoduric skid is taken into account strictly. The formation process of skid mark is clarified based on the calculated results of coupled heat transfer, and an improved design scheme for water beam is proposed to make the new skid marks produced after water beam dislocation not overlap each other, which effectively reduces the skid marks. Our study can provide helpful advising for the improvement of steel slab quality and the design of water beam structure in reheating furnace.

Non‐Contact Triboelectric Nanogenerator

AbstractWith the rapid development of science and technology, there is an increasing demand for sustainable energy sources. Although triboelectric nanogenerators (TENGs) can realize self‐powered supply by using various weak mechanical energy, the device's robustness and reliability are seriously affected by frequent, direct, and long‐term mechanical shocks, as well as negative environmental factors during equipment operation. Therefore, researchers have developed non‐contact triboelectric nanogenerators (NC‐TENGs) based on the principle of electrostatic induction. This technology enables electricity generation via relative movement of friction layers even when they are not in direct contact, which consequently leads to enhance device robustness, prolonged service life, and broadened operation scenarios. In this review, the recent progress of NC‐TENG from fundamental theory to practical applications is systematically summarized. The basic structure and working principle of NC‐TENG are first introduced, followed by a discussion of the devices’ structural construction and performance optimization methods. Furthermore, applications of NC‐TENG in automatic force position detection system, non‐contact human‐machine interface, and electrical energy harvesting are reviewed. Finally, a brief prospectus for the future development of NC‐TENG is provided.

Image segmentation for automatic detection and detectability evaluation of thinning defects using LSM-based induction thermography

The infrared thermography (IRT) technique is a highly reliable and attractive technique that can evaluate a large area in real-time without destroying the inspection object. This study used the line scanning method (LSM)-based induction thermography (IT) technique among active IRT to detect thinning defects in S275 steel specimens. Unlike the dynamic mode, LSM was applied to perform sequence processing so that the copper coil shape was removed in the 2D thermal images processed. After image segmentation, a binary image was acquired using the Otsu algorithm. By utilizing image segmentation, the applied threshold for each defect is different when performing the Otsu algorithm. This makes it possible to compare defect detection according to the presence or absence of image Segmentation. Automatic defect detection was performed using a Boundary Tracking algorithm, and 12 defect detections were confirmed. Accuracy was evaluated through pixel calculation, and defects in A, B, and D columns showed high detection accuracy. This study presented the principle of LSM in which includes the relative movement between the IR camera and the specimen. In addition, a mechanism to increase the number of defects detected through image segmentation was presented.

(Non)violent protest in Africa: Echoes and lessons from Fela Anikulapo Kuti

This study examines the intersection of popular music/culture, social movement and protest by analysing the numerous protest music produced and performed by Fela Anikulapo Kuti, Africa’s most iconic resistant artist of the twentieth century. It engages the core questions of right, injustice and inequality that have manifested in Africa/Nigeria’s underdevelopment since the Union Jack was lowered in 1960. It argues that Fela’s music did have obvious impact on Nigerian youth and the working class who attempted to revise or renegotiate their relationship with the Nigerian state. Yet, it posed hitherto unanswered questions of the changing meaning of social movement in relation to artistic production -- an aspect of peace studies that scholars have completely overlooked. It concludes that as people reconfigure social relations from one stage to another in their life, their engagement with the State and the social meaning attributed to social justice, which Fela’s music emphasised, also change. Thus, popular consciousness shaped by resistant music is not immutable to nonviolent social protest. Rather, it continued to change as individuals and groups reconstitute their relationship with the society, and as their social status transformed in accordance with the acquisition of better education, wealth/resources, among other significant elements that shape human’s consciousness.

A large‐scale decision‐making model for the expediency of funding the development of tourism infrastructure in regions

AbstractThe main goal of this study was to develop a hybrid decision‐making support model regarding the feasibility of financing the development of tourism infrastructure of regions for V4 countries, based on the predicted assessment of the level of tourist movement in relation to the infrastructure and accessibility of the studied regions, expert opinions regarding the level of quality of tourist services and tourism development, as well as opinions of experts regarding the prospects of rapid growth of tourist movement in the region. For the first time, a hybrid fuzzy model for assessing the level of tourism quality in the region was developed, using the opinions of experts regarding the level of quality of tourist services and tourism development. For the first time, a five‐layer neuro‐fuzzy model was developed to derive a quantitative and linguistic assessment of the level of feasibility of financing the development of tourist infrastructure based on the experience, knowledge, and competences of experts regarding the prospects of rapid growth of tourist movement in the studied region. The research results were tested, and the developed model was verified on real data for 43 regions of the V4 countries.

Model Development for Binder Migration within Lithium-Ion Battery Electrodes during the Drying Process

In the drying process of electrodes for lithium-ion batteries, the layer structure is defined and can only be influenced slightly in the subsequent process steps. An essential point in the drying process is the fixation of the binder, ensuring both the adhesive and cohesive strength of the electrode. It is known that high drying rates lead to the segregation of the binder in the direction of the coating surface, which results in reduced mechanical stability of the electrode. In a previous publication, an experimental approach was used to investigate the underlying processes that influence binder migration. These results are now used in a model-based approach to describe the binder migration using the convection–diffusion equation. The convective term originates from the shrinkage behavior of the layer during drying due to the relative movement between the active material particles and the solvent in which the binder is dissolved or dispersed; it is expected to be the cause of the binder migration. The diffusive term, representing the binder movement in the solvent, counteracts segregation. The interaction of these forces is simulated at different drying temperatures and the associated drying rates.

Yarn level finite element method simulation for bending over sheaves of braided ropes

The complex problem of ropes (cyclic) bending over sheaves (CBOS) is considered in this article. Ropes that are used to manoeuvre and regulate sails undergo a variety of dynamic stresses which are crucial yet difficult to determine, due to the complexity of the multi-scaled braiding structure of ropes. A full dynamic Finite Element Method (FEM) simulation of a braided rope bending over a sheave is conducted with the commercial software Abaqus/Explicit, as it can capture the complex processes occurring inside the rope to high accuracy. A theoretical deduction is performed to determine the yarn paths in a 3D braided structure. Relative movement between braided yarns (including the interlacing point) are better assessed at yarn level through 3D element types instead of the traditional beam elements, as they allow to obtain an estimation of yarn-yarn displacement. Parametric studies are conducted to better understand the factors that affect the yarn sliding. The ratio between the diameter of the sheave and the rope, and the braiding angle, are found to be crucial for the relative movement, while the number of yarns and their diameters have little influence. The successful simulation process demonstrates the feasibility of modelling and analysing the complex interaction occurring in braided structures under specific boundary conditions. The calculated estimated displacement can contribute to further investigations such as the friction and heat generation problem in braided ropes. Simulation with this method can provide alternatives in predicting lifespan of braided products that cannot be easily inspected.

Performance assessment of buried steel pipelines reinforced with carbon fibre-reinforced polymer under reverse fault movement

Buried oil and gas pipelines are often affected by the active zones across faults, and the failure of pipeline functions owing to relative fault movements has attracted widespread attention. Carbon fibre-reinforced polymer (CFRP) was proposed as a reinforcement measure for buried continuous pipelines crossing faults to mitigate the structural damage to pipelines subjected to large permanent ground deformations. In this study, the lamina model and Hashin failure criterion were used to simulate the CFRP material in a three-dimensional nonlinear finite element model of the pipeline-soil interaction. The peak strain and cross-sectional ovalization of the pipeline were used to quantify the nonlinear response of the steel pipeline subjected to reverse fault movement. Parametric studies in terms of the CFRP wrapping angle, thickness, length, as well as internal pressure were conducted to comprehensively assess overall performance of CFRP-wrapped steel pipelines. Results indicated that the CFRP wrapping in direction of 0°/90° with respect to the axial direction of the pipeline exhibit the optimum effects in improving the performance of pipelines. For steel pipelines subjected to reverse fault, increase of the CFRP wrapping thickness effectively reduces the development of compressive strain on the pipeline wall, thereby delay the local buckling failure of the pipeline. Besides, CFRP is effective in increasing the bending curvature radius and preventing the local buckling of the pipeline, but insufficient wrapping length of CFRP can lead to local buckling of steel pipelines under same fault displacement. For pipelines with internal pressures internal pressure can enhance the overall performance of CFRP wrapped pipelines against reverse fault movement.

Semantic Proximity Update of GNSS/INS/VINS for Seamless Vehicular Navigation Using Smartphone Sensors

The advancement of microelectromechanical systems (MEMS) and the Internet of Things (IoT) have enabled a wide range of applications based on smartphones. However, the existing navigation methods using these low-cost MEMS sensors cannot provide acceptable information for location-based applications in various environments. Their technical limitations, such as severe signal attenuation, reflections, blockages, error accumulation, and low quality of images degrade the performance of GNSS, INS, and camera. To mitigate these limitations, especially in indoor vehicle navigation, we first analyze the performance of the existing fusion algorithm, then we propose Semantic Proximity Update (SPU) based on a pre-trained model of real-time object detection to enhance the integration of Global Navigation Satellite System (GNSS), Inertial Navigation System (INS) and Visual Inertial Navigation System (VINS). SPU consists of the detection of geo-referenced objects and the relative movement to infer the absolute position. The proposed INS/GNSS/VINS/SPU can maintain long-term acceptable accuracy regardless of the indoor/outdoor environment. It only requires the use of smartphone sensors; thus, this scheme has no additional cost for users. Experimental results indicated that the errors of this scheme in horizontal positioning and three-dimensional positioning were 51.6% and 86.8% lower, respectively than those of a conventional integration.

INCLUSION OF CONTACT FRICTION FOR PARTICLE-BASED SIMULATION OF SEDIMENT TRANSPORT OVER MOBILE BED

The particle based approach, including the particle resolving method, such as CFD-DEM, e.g. Drake and Calantoni (2001), Schmeeckle (2014), and the Particle-In-Cell (PIC) method, e.g. Patankar and Joseph (2001); Finn, M. Li, and Apte (2016); Y. Li et al. (2014), has become important tool for simulation of sediment transport in recent years. The latter is advantageous in the required computing resources when large amount of particles are involved and hence is more suitable for simulation of sediment transport over mobile bed. However, unlike that in CFD-DEM, special treatment is needed in the PIC method in order to prevent overlap and over-packing of sediment particles in a computational cell. Most models so far ignore the contact friction force between particles that hinders relative movement but often is essential to maintain particles in static position, especially in the seabed where the contact forces between particles are the largest. An new friction force is proposed to simulate the particle interactions, similar to the collision used in previous studies, so that the kinetic energy driving particles motion can be effectively dissipated and over-packing can be minimised under either static or dynamic stages of the particle motion.

The sensory effects of light on the electric organ discharge rate of Gymnotus omarorum.

Gymnotiformes are nocturnal fishes inhabiting the root mats of floating plants. They use their electric organ discharge (EOD) to explore the environment and to communicate. Here, we show and describe tonic and phasic sensory-electromotor responses to light distinct from indirect effects depending on the light-induced endogenous circadian rhythm. In the dark, principally during the night, inter-EOD interval histograms are bimodal: the main peak corresponds to the basal rate and a secondary peak corresponds to high-frequency bouts. Light causes a twofold tonic but opposing effect on the EOD histogram: (i) decreasing the main mode and (ii) blocking the high-frequency bouts and consequently increasing the main peak at the expense of removal of the secondary one. Additionally, light evokes phasic responses whose amplitude increases with intensity but whose slow time course and poor adaptation differentiate from the so-called novelty responses evoked by abrupt changes in sensory stimuli of other modalities. We confirmed that Gymnotus omarorum tends to escape from light, suggesting that these phasic responses are probably part of a global 'light-avoidance response'. We interpret the data within an ecological context. Fish rest under the shade of aquatic plants during the day and light spots due to the sun's relative movement alert the fish to hide in shady zones to avoid macroptic predators and facilitate tracking the movement of floating plant islands by wind and/or water currents.

Focused classifications and refinements in high-resolution single particle cryo-EM analysis

Recent advances in cryo electron microscopy (cryo-EM) and image processing provide new opportunities to analyse drug targets at high resolution. However, structural heterogeneity limits resolution in many practical cases, hence restricting the level at which structural details can be analysed and drug design be performed. As structural disorder is not spread throughout the entire structure of a given macromolecular complex but instead is found in certain regions that move with respect to others and covering molecular scales from domain conformational changes up to the level of side chain conformations in ligand binding pockets, it is possible to focus the attention on those regions and the associated relative movements. Here we show how the usage of focused classifications and refinements provide insights into global conformational arrangements, exemplified on the human ribosome and on the cannabinoid G protein coupled receptor (GPCR), and how they can improve the local map resolution from an essentially disordered region to the 3–4 Å and finally to the 2 Å resolution range. A systematic analysis with variable spherical masks during focused refinement is presented showing that the choice of an optimal mask size helps refining to high resolution. This study covers several practical approaches on 4 examples illustrating how important mask size & shape and including neighbouring structural elements are for a focused analysis of a macromolecular complex. Such methods will be crucial for cryo-EM structure-based drug design of various medical targets and are applicable to single particle cryo-EM and electron tomography data.

A Spatial Delay Domain-Based Prony Channel Prediction Method for Massive MIMO LEO Communications

Massive multiple-input–multiple-output (massive MIMO)-based low Earth orbit (LEO) intersatellite link communications is a promising research topic for the fifth generation (5G) and forthcoming sixth generation (6G) wireless networks. However, due to the fast relative movement between the transmitter and receiver in LEO satellites, intersatellite link communication is facing serious Doppler shifts and delays, which makes it difficult to obtain the accurate channel state information (CSI). Therefore, this article proposes an improved channel prediction method, that is, spatial-delay domain-based Prony (SDD-Prony) prediction, which not only realizes the accurate CSI acquisition for massive MIMO-based LEO intersatellite link systems but also substantially reduces the computational complexity. In particular, it is shown that the prediction error of the proposed method can converge to zero with the increase in antenna number and bandwidth. In addition, we combine the SDD-Prony prediction method with the total least squares method to reduce the influence of the noise and error components on the prediction accuracy, which further improves the prediction performance. The effectiveness of the proposed method is demonstrated by a theoretical proof and simulation results.