Reciprocal Motion Research Articles

An In-Vitro Comparative Analysis on Root Canal Transportation, Centering Ability, Angle of Curvature Using XP-Endo Shaper and WaveOne Gold Rotary Systems-A CBCT Study

Background: In this study we highlight the difference between two recent single file endodontic systems XP-endo Shaper by FKG and WaveOne Gold by Dentsply by measuring their efficiency through assessing the centering ability, canal transportations, preparation time and changes in canal curvature on resin endodontic blocks using Cone Beam Computed Tomography. Material and Methods: Fourteen resin endodontic blocks are used for each system. The assessment was done by comparing and measuring the data collected of pre-instrumentation and post-instrumentation CBCT axial and sagittal images to assess the centering ability, canal transportation, preparation time and changes in canal curvature. These measurements were taken in 3mm ,5mm and 7 mm from the apical exit of the endodontic block used. Results: The mean Canal Transportation of XP System (Group A) in 3mm, 5mm and 7mm sections measured with values (-.5214, -.2714 and -.02140) respectively. The mean transportation of WaveOne Gold system (Group B) in 3mm, 5mm and 7mm in sections with values (-.3214, -.2571 and -.1143.) respectively, whereas the mean centering ability of XP System (Group A) in 3mm, 5mm and 7mm sections measured with values (.0714, -.6131 and -.9881) respectively. The mean transportation of WaveOne Gold system (Group B) in 3mm, 5mm and 7mm sections is given as (-.3255, -.6310 and -.6429) and there was no significant difference noted in centering ability and canal transportation between the two systems. The mean root canal preparation time showed no statistical difference between the two systems employed. There was statistical difference noted in the changes in pre- and post-curvatures of the canal between two systems studied. Conclusion: With our limitation in sample size, it was concluded that reciprocation motion in WaveOne Gold system gave better results in canal transportation and centering ability in the simulated apical part in endo-blocks than continues motion rotary preparation in XP endo shaper system. WaveOne Gold produced lesser canal transportation in the apical 3rd while XP endo shaper produced less canal transportation and centering ability in the middle 3rd simulated endo-blocks.

Comparison of cyclic fatigue resistance of heat-treated nickel-titanium reciprocating instruments at the intracanal temperature

Background/Aim: The aim of the present study was to compare the cyclic fatigue resistance of NiTi files running with reciprocal motion and having different characteristics (RPC Blue, WOG, EndoArt Wise Reciproc Gold, EndoArt Wise Reciproc Blue) at the intracanal temperature (35°C) by using NaOCl irrigation solution. Material and Methods: Totally 60 WaveOne GOLD (Dentsply-Sirona, Ballaigues, Switzerland), Reciproc Blue (VDW, Munich, Germany), EndoArt Wise Reciproc Gold, and EndoArt Wise Blue (Inci Dental Productions Co, Istanbul, Turkey) (n= 15) files were used. Each of the rotary files were tested at the intracanal temperature (35°C) using a dynamic model in a stainless-steel artificial canal with an inner diameter of 1.5 mm, 60° angle of curvature, and 2mm radius of curvature until fracture occurred. The device automatically stopped at the moment of fracture and the number of cycles to the fracture was calculated as per second. The lengths of fractured parts were measured using a digital microcaliper. The One-Way Analysis of Variance (ANOVA) and Tukey's posthoc tests were used for intergroup comparisons. Results: In 2 mm Radius of curvature, the EndoArt Wise Reciproc Blue group had a significantly higher time to fracture followed by the EndoArt Wise Reciproc Gold, Resiproc Blue, WaveOne Gold. No significant difference was found between EndoArt Wise Reciproc Gold and Resiproc Blue groups (P>0.05). Among the groups, there was no statistically significant difference in the lengths of fractured parts of the instruments (P> 0.05). Conclusions: EndoArt Wise Reciproc Blue files exhibited significantly higher cyclic fatigue resistance compared with other files tested in a 2-mm radius of curvature and a 600 angle in an artificial canal at the intracanal temperature.

Root Dentine Strain Generation during Root Canal Instrumentation with Rotation and Reciprocation Motions

The aim of the study is to measure and compare strain generated on root dentine surface by two different instrumentation motions. Thirty extracted single canal premolars were used in this study which randomly was divided into two groups, one group was prepared with ProTaper NEXT X2 file in rotation motion, and the second group was prepared by WaveOne GOLD primary file in reciprocation motion, the canals were irrigated during canal preparation by 2 ml of sodium hypochlorite and 17% EDTA gel was used. Strain measurement was performed by strain gauges and a digital strain output reader, data were recorded every 5 s for 50 s. The results of this study have shown that WaveOne GOLD had higher mean 0.7308±0.41106 than ProTaper next 0.5385±0.39904 which means WaveOne GOLD generates greater strain than ProTaper NEXT. However, according to Student’s t-test between two groups there is no statistical difference between them. Based on the results of this study, there was no difference between the two motions; both motions generated strain on root dentine surface.

Processing plants for food: Experimental grinding within the ERC-project PLANTCULT

PlantCult Project aims to explore the role of culinary traditions and innovations through their impact on shaping the social landscape in ancient Europe over long time periods (from the Neolithic period to the Iron Age) and large territories. The experimental program is part of an integrated study of food products and associated equipment focusing on whether the introduction of new species or changes in social and economic organisation brought about changes in the food grinding technologies of the area.
 The experiments include tools operated by back and forth reciprocal motion and circular motion, and manufactured from different raw materials, with different morphologies and sizes. The tools design and the list of plant ingredients (cereals, legumes, acorns and oil-seeds) ground in the experiments are all based on the archaeological record of the studied area. In this paper we present the experimental protocol, the multi-scale methodology applied to the use-wear analysis of grinding stone tools, and the results of the experimental processing of the main plant ingredients detected in prehistoric European cuisine.

A Tubular Single‐Phase Linear Generator with an Axially Magnetized PM Mover for Free‐Piston Engines

A novel tubular single‐phase linear generator with an axially magnetized permanent magnets (PM) mover is proposed in this paper for the application of free‐piston engine, which is an alternative power generation system of next‐generation electric vehicle. The transient 3D with motion electromagnetic field finite element model is created to analyze the EMF and thrust force characteristics of the linear generator. A 1.4 kW prototype with the max stroke of 40 mm and the max thrust force of 1670 N is developed, and main performances of the prototype are tested and validated with the finite element simulation. The prototype generating efficiency of 84 and 91% can be obtained respectively when driving by the 35 and 50 Hz sinusoidal reciprocation motion. Compared with the existed moving coil linear generator with similar generating efficiency, the mass power density and the volumetric power density of the new linear generator increase by about 37 and 80%, respectively. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Exo-shoe triboelectric nanogenerator: Toward high-performance wearable biomechanical energy harvester

Abstract Among various daily human motions, walking is considered the most natural and strongest one. In this study, the exo-shoe TENG (ES-TENG) with the rationally designed bi-directional gearbox is developed to generate extended and enhanced output performance during daily walking. This bi-directional gearbox effectively converts the whole stroke of a reciprocating and low frequency (1 Hz) natural stepping motion into uni-directional high-speed rotation (700 rpm). The proposed ES-TENG exhibits more than ten times enhancement of the output performance with effective motion transformation. Although the normal stepping motion is not interrupted by the ES-TENG, the specific power of the ES-TENG could reach up to 13 µW/g through a single daily stepping motion. Real-time self-powered environmental monitoring and charging wearable electronics are demonstrated as proof-of-concept applications. Furthermore, the voltage multiplier circuit is used to generate a boosted open-circuit voltage of more than 3 kV, which shows the potential electric treatment applications of the ES-TENG. The ES-TENG provides the potential of biomechanical energy harvesting with a broad range of applications through the generation of highly enhanced output performance under natural daily stepping motions.

Friction, wear and deformed structure of Ag and Ni under early stages of scratching

We report here the investigation of the effect of stacking fault energy (SFE) on the friction, wear, and deformed microstructure of Ag and Ni following one and ten cycles of scratching. For this purpose, low and high SFE face centered cubic (fcc) metals, were evaluated. Scratching of the samples was conducted in the reciprocal motion using a diamond indenter. To provide similar contact conditions we applied the parameter of virgin contact area, P/Hi ~0.055, where P is the load and Hi - the initial hardness. The tests were performed during 1 and 10 scratching cycles using sliding velocity of 30 μm/s. The microhardness before and after scratching was measured. Friction surfaces were carefully examined with a field emission scanning electron microscope (SEM) and an atomic force microscope (AFM). The cross-sectional transmission electron microscopic (TEM) lamellae were prepared using a focused ion beam (FIB). It was found that the deformation hardening of Ag is significantly greater than that of Ni. The size of scratch tracks of Ag was smaller than for Ni. This phenomenon can be explained by a high rate of deformation hardening and formation of the refined structure at upper surface layers of Ag due to the limitation of the cross slip during plastic deformation.

Torsional Resistance of WaveOne Gold and Reciproc Blue according to the Loading Methods

IntroductionThis study aimed to compare the torsional resistances and fracture modes of WaveOne Gold (Dentsply Sirona, Ballaigues, Switzerland) and Reciproc Blue (VDW, Munich, Germany) using the repetitive torsional loading (RTL) method and the conventional single-rotation (STL) method. MethodsA 3-mm file tip was fixed with a brass plate, and a torsional load was applied using a custom device. In the RTL method, the file was driven counterclockwise at 50 rpm until it achieved the preset torque of 0.5 Ncm; thereafter, it was returned to its original position. This recovery of the file to its original position was defined as 1 torsional loading cycle; the number of repetitive load cycles until fracture was counted. In the STL method, the files were rotated at a constant rate of 2 rpm in a counterclockwise direction until file fracture. The fragments fractured by the 2 methods were compared under a scanning electron microscope to examine the topographic features of the fractured surfaces and longitudinal aspects. ResultsWith the RTL method, Reciproc Blue showed a higher number of repetitive load cycles until fracture than WaveOne Gold (P < .05). With the STL method, Reciproc Blue also had a higher ultimate strength than WaveOne Gold (P < .05). Scanning electron microscopic findings of the fractured specimens from the 2 test methods showed different features of torsional failure. ConclusionsWithin the study limitations, both the RTL and STL methods conferred similar torsional resistance. Therefore, the clinically relevant RTL method with repetitive and reciprocation motion can be used for testing torsional resistance.

Assessment of cyclic fatigue resistance of Protaper Next and WaveOne Gold in different kinematics

BackgroundThe purpose of the current study was to inspect and compare the influence of applying continuous rotation and reciprocation motions on the cyclic fatigue resistance of Protaper Next (PTN) file (X2) and WaveOne Gold (WOG) Primary file in simulated canals. Twenty Protaper Next files(X2) and 20 WaveOne Gold Primary files were included in this study. A cyclic fatigue testing device was employed to test the cyclic resistance of each file in different motions. The testing device has an artificial custom-made stainless-steel canal with a 60° angle of curvature and a 2-mm radius of curvature. The files were randomly divided into 4 groups; group 1: PTN in continuous rotation, group 2: PTN in reciprocation, group 3: WOG in continuous rotation and group 4: WOG in reciprocation. All the instruments were rotated until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The number of cycles to fracture (NCF) was calculated. The data were analyzed statistically (p < .05).ResultsResults represented that when using either continuous rotation motion or reciprocating motion, WOG files showed a significantly longer time until failure than PTN files (p < 0.001). The time till fracture increased significantly, when using both types of files with a reciprocating filing motion.ConclusionWithin the confinement of this study, WOG file in reciprocation showed higher cyclic fatigue resistance than PTN in both continuous rotation and reciprocating motion. The reciprocating motion enhances both files behavior in terms of cyclic fatigue resistance.

The effect of dynamics of the swash plate–slippers–piston assembly on friction torques in bearings in compressor of cooling aggregate

Abstract The swash plate type compressor utilized in car air conditioning devices and cooling system was analyzed in this study. Proper dynamic behavior of the components in such a compressor affected the correct functioning of the whole system. The aim of the study was to identify the characteristics of the main motion components in the swash plate–slippers–piston assembly of the compressor and to estimate the friction torques in its bearings. Some models of this assembly are elaborated and presented in the paper. The main components of slipper complex motion were identified, such as reciprocal motion along the axis of piston, rotation around piston axis, and short-time rotation around its own axis. Friction torque in axial bearing was higher than in journal bearing and varied with the rotational angle. Friction torques in journal bearings varied with the rotational angle and had different courses for two bearings of the compressor.

Reciprocal microswimmers in a viscoelastic fluid

We suggest several reciprocal swimming mechanisms that lead to locomotion only in viscoelastic fluids. In the first situation, we consider a three-sphere microswimmer with a difference in oscillation amplitudes for the two arms. In the second situation, we consider a three-sphere microswimmer in which one of the frequencies of the arm motion is twice as large as the other one. In the third situation, we consider a two-sphere microswimmer with a difference in size for the two spheres. In all these three cases, the average velocity is proportional to the imaginary part of the complex shear viscosity of a surrounding viscoelastic medium. We show that it is essential for a micromachine to break its structural symmetry in order to swim in a viscoelastic fluid by performing reciprocal body motions.

ОСОБЕННОСТИ ПОСТРОЕНИЯ И ПРИМЕНЕНИЯ ЛОГИЧЕСКИХ МЕТОДОВ ПОИСКА ПРИЧИН ОТКАЗОВ ПОРШНЕВЫХ ДВИГАТЕЛЕЙ ВНУТРЕННЕГО СГОРАНИЯ В ЭКСПЛУАТАЦИИ

Despite the successes in research and development of designs of modern internal combustion engines for various purpose vehicles, including aircraft, to date, no reliable methods have been created to determine the causes of their failures. The application of well-known methods in practice, including the diagnosis of engine technical condition, not only requires a lot of labor and highly qualified personnel but in many cases, it is practically ineffective. This is especially true for severe operational damage arising from the destruction of the parts and accompanied by disturbing the synchronization of their reciprocating and rotational motion. On the other hand, the performed research shows that the causes of ICE failures can also be determined by logical-probabilistic methods, including based on the fault tree analysis, drawing on the available experience of studying various engine faults. However, it is not possible to use the well-known models and methods built based on the failure tree analysis in problems of finding the causes of engine failure. The reason is since such methods have been developed for the tasks of calculating the reliability characteristics of developed engines, rather than finding the causes of their failure in operation. The solution to this problem was found in several stages. Initially, by structuring the symptoms, a fault tree was compiled that logically describes the cause-effect relationships between the failure event and the initial damage that caused it. This is done separately for each of the types of failures selected for analysis and associated with severe damage to the studying engine type. Further, for a finite number of selected types of failures, a modified (inverted) fault tree was developed. It allows you to perform a simple logical analysis in the opposite direction to the generally accepted direction - from the system failure event to the basic events initiating the failure. After that, a modified engine fault tree common to the considered types of failures was compiled. As a result of using the proposed methodology in practice, it became possible to determine the causes of engine failure with sufficient reliability with minimal time.

Effect of different kinematics and operational temperature on cyclic fatigue resistance of rotary NiTi systems

BackgroundThe aim of this study was to compare the effect of different kinematics and operational temperature on cyclic fatigue resistance of Protaper Next, WaveOne Gold, and Twisted File Adaptive files in a static model.MethodologyAn artificial canal, made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature, and a curvature radius of 2 mm, was used for the cyclic fatigue test immersed in a water bath for temperature adjustment (37 °C and 20 °C). A total of 120 files were divided into three groups according to the type of motion continuous rotation motion (CRM), adaptive motion (AM), and reciprocation motion (RM). Each group was further subdivided into two subgroups according to the operational temperature (37 °C and 20 °C), All instruments were operated until fracture occurred, and the time to fracture was recorded in seconds. Mean number of cycles to failure and standard deviations were calculated for each group, and data were analyzed statistically using two-way ANOVA followed by Tukey’s post hoc test (P ≤ 0.05).ResultsThe continuous rotation motion exhibited significantly lower cyclic fatigue resistance than reciprocating or adaptive motion (p ≤ 0.001) at 37 °C and 20 °C.ConclusionsCyclic fatigue resistance of NiTi files was affected by the motion used during root canal preparation. Reciprocation motion and adaptive motion resulted in extended fatigue. The operational temperature affects the cyclic fatigue resistance of the twisted file.

Vibration reduction of a flexible robot link using a frictional damper

One of the most important factors reducing flexible manipulator efficiency is the residual vibration occurrence. In this research, vibration reduction of flexible manipulators is investigated using an internal frictional damper. At first, the vibration equation of a manipulator is obtained using the finite element method with the Euler–Bernoulli beam element to study its vibrations in a reciprocal motion. In addition, an analytical model is developed to investigate the effect of the frictional damper on robot link vibrations. Using particle swam optimization, ICA, NSGA-II, and GWO methods, the optimal structure for the damper is obtained to maximize its effect. The optimally damped link is fabricated, and its dynamic characteristics are extracted from a modal test experiment. The modal test results show a considerable improvement in the damping ratio of the damped link in comparison with a simple link. The fabricated link samples are then tested in a realistic situation. The experimental results are in coincidence with the simulation results, certifying the performance of the proposed plan in vibration reduction of a robot link.

공압 피로 시험기 구성을 위한 공압실린더의 고속/고정밀 제어기술

A hydraulic cylinder is typically used in fatigue testing machines for generating reciprocal motion. Hydraulic cylinders adversely affect the environment because they consume high amounts of oil for maintenance. Pneumatic cylinders can serve as potential alternatives to overcome this drawback. However, it is difficult to control a pneumatic cylinder with high accuracy due to the compressibility of air. This study presents a new control method for high-speed and high-precision control of a pneumatic cylinder for a servo-pneumatic fatigue testing machine. Displacement and load controllers with proportional-proportional-integral feedback and feedforward algorithms are proposed. Furthermore, an auto-tuning algorithm of a feedforward controller gain is proposed to improve control performance. A servo-pneumatic fatigue testing machine is constructed, and the control performance is evaluated via displacement and load control experiments at the various conditions.

Global-scale brittle plastic rheology at the cometesimals merging of comet 67P/Churyumov–Gerasimenko

Observations of comet nuclei indicate that the main constituent is a mix of ice and refractory materials characterized by high porosity (70-75%) and low bulk strength (10-4-10-6 MPa); however, the nature and physical properties of these materials remain largely unknown. By combining surface inspection of comet 67P/Churyumov-Gerasimenko and three-dimensional (3D) modeling of the independent concentric sets of layers that make up the structure of its two lobes, we provide clues about the large-scale rheological behavior of the nucleus and the kinematics of the impact that originated it. Large folds in the layered structure indicate that the merging of the two cometesimals involved reciprocal motion with dextral strike-slip kinematics that bent the layers in the contact area without obliterating them. Widespread long cracks and the evidence of relevant mass loss in absence of large density variations within the comet's body testify that large-scale deformation occurred in a brittle-plastic regime and was accommodated through folding and fracturing. Comparison of refined 3D geologic models of the lobes with triaxial ellipsoids that suitably represent the overall layers arrangement reveals characteristics that are consistent with an impact between two roughly ellipsoidal cometesimals that produced large-scale axial compression and transversal elongation. The observed features imply global transfer of impact-related shortening into transversal strain. These elements delineate a model for the global rheology of cometesimals that could be possible evoking a prominent bonding action of ice and, to a minor extent, organics.

Dynamic Analysis and Design Optimization of a Drag-Based Vibratory Swimmer

Many organisms achieve locomotion via reciprocal motions. This paper presents the dynamic analysis and design optimization of a vibratory swimmer with asymmetric drag forces and fluid added mass. The swimmer consists of a floating body with an oscillatory mass inside. One-dimensional oscillations of the mass cause the body to oscillate with the same frequency as the mass. An asymmetric rigid fin attached to the bottom of the body generates asymmetric hydrodynamic forces, which drive the swimmer either backward or forward on average, depending on the orientation of the fin. The equation of motion of the system is a time-periodic, piecewise-smooth differential equation. We use simulations to determine the hydrodynamic forces acting on the fin and averaging techniques to determine the dynamic response of the swimmer. The analytical results are found to be in good agreement with vibratory swimmer prototype experiments. We found that the average unidirectional speed of the swimmer is optimized if the ratio of the forward and backward drag coefficients is minimized. The analysis presented here can aid in the design and optimization of bio-inspired and biomimetic robotic swimmers. A magnetically controlled microscale vibratory swimmer like the one described here could have applications in targeted drug delivery.

Offset components and fault-block motion during the 2016 central Italy earthquake (Mw 6.6, Monte Vettore fault system)

We performed structural analyses on exhumed fault planes in carbonate rock of the Monte Vettore fault system (Central Italian Apennines). Slip on these faults was responsible in 2016 for a Mw 6.6 earthquake, accompanied by 30-km-long surface rupture. We focused on scratches, a peculiar coseismic abrasion feature that is rarely described and analysed in structural geology, mainly because of its ephemeral nature (most of scratches disappear after just a few months). We surveyed coseismic scratches and slip vectors of coseismic surface ruptures that, coupled with conventional striae analysis, provide interesting clues to the kinematic behavior of the hanging-wall during the 2016 mainshock. First, we investigated whether or not scratches could be considered as kinematic indicators and if they could really add information to results of striae analysis. To this end, we compared the statistical analysis of scratches with those obtained from conventional fault-surface structural elements or inferred from other geological, seismological and geodetical data. Results show that the movement of the hanging-wall of the Monte Vettore fault system during the October 30, 2016, mainshock can be traced back to two components. The first, major component is kinematically linked to deep tectonic deformation. The second, minor component, is related to passive-slip deformation induced by the complexity of reciprocal motion between hanging-wall and footwall.

A study on the effects of piston secondary motion in conjunction with clearance joints

Piston secondary motion caused by the changes in side forces and a clearance between piston skirt and cylinder liner, is inevitable in crank train. Studies reporting the combined effect of the associated joint clearances on piston secondary motion are rare, due to the complexity of analysis involved. This paper presents a dynamic model to analyze piston secondary motion considering all associated joint clearances. In this model, both the reciprocating and secondary motion of piston are considered as well as the planar motion of connecting rod. By adjusting the clearances, and simulating with/without the piston secondary motion, their effects on the dynamics of crank train system are evaluated. The simulated results indicate that the effects of joint clearances are closely connected with the impact responses caused by piston secondary motion. The dynamic model in the paper can be used to find the limit of joint clearance for analysis and design purpose of piston group.

Active Reversible Swimming of Magnetically Assembled "Microscallops" in Non-Newtonian Fluids.

Miniaturized devices capable of active swimming at low Reynolds numbers are of fundamental importance and possess potential biomedical utility. The design of colloidal microswimmers requires not only miniaturizing reconfigurable structures but also understanding their interactions with media at low Reynolds numbers. We investigate the dynamics of "microscallops" made of asymmetric magnetic cubes, which are assembled and actuated using magnetic fields. One approach to achieving directional propulsion is to break the symmetry of the viscous forces by coupling the reciprocal motions of such microswimmers with the nonlinear rheology inherent in non-Newtonian fluids. When placed in shear-thinning fluids, the local viscosity gradient resulting from nonuniform shear stresses exerted by time-asymmetric strokes of the microscallops generates propulsive thrust through an effect we term "self-viscophoresis". Surprisingly, we found that the direction of propulsion changes with the size and structure of these assemblies. We analyze the origins of their directional propulsion and explain the variable propulsion direction in terms of multiple counterbalancing domains of shear dissipation around the microscale structures. The principles governing the locomotion of these microswimmers may be extended to other reconfigurable microbots assembled from colloidal-scale units.