Instrument Rotation Research Articles

Characterization of Hydraulic Fractures With Triaxial Electromagnetic Induction and Sector Coil Rotation Measurement

The characterization of hydraulic fractures is crucial for fracturing evaluation and strategy optimization. Low-frequency electromagnetic triaxial induction measurement is a promising candidate in hydraulic fracture characterization. However, it is difficult to accurately monitor fracture shape, orientation, and the multistage fracture network distribution. A novel method that combines triaxial induction measurement with sector-shaped coils axial rotation measurement (TIM-SCARM) is proposed to characterize hydraulic fractures. It is implemented by using the finite element method with transition boundary conditions (FEM-TBCs), which approximates the thin fracture as a surface to enhance the computational efficiency. The study focuses on quantitative analysis of conductivity, cross-sectional shape, half-length, and orientation of hydraulic fractures to assess their effects on specific configurations of the TIM-SCARM. Furthermore, the correlations between multicomponent signals and fracture characteristics are investigated. Numerical results indicate that the coaxial component signal in SCARM can distinguish the cross-sectional shape and orientation. The cross-polarized component signals provide important features of tilted fractures, and the 3-D signal obtained by instrument rotation could determine the spatial distribution of fracture networks. Therefore, measurements that integrate the multicomponent signals and axial information improve fracture geometry evaluation.

Cyclic fatigue resistance of four different nickel-titanium instruments in an artificial canal

Introduction: The objective of this study was to measure the number of cycles to fracture of four continuous or reciprocating rotary nickel-titanium instruments in different materials. Methods: A total of 40 nickel-titanium instruments were used for the present study. Instruments were divided into four groups (n=10): group 1, Revo-S SU; group 2, ProTaper Next X2; group 3, Reciproc R25; group 4, WaveOne Gold Primary. An artificial stainless-steel was used to test the cyclic fatigue of the instruments. The instruments were introduced into the stainless-steel canal, one at a time, until they reached the other end, then they were rotated inside the canal without in-out motion. The time from the beginning of instrument rotation until the occurrence of breakage was recorded. The number of rotated cycles to fracture of the instrument were calculated based on the revolutions per minute (rpm) of each instrument and the recorded rotated time. The mean number of cycles to fracture and standard deviations were calculated and statistically analysed. Results: The number of cycles to fracture of the Revo-S SU was the lowest, and that of the WaveOne Gold Primary was highest. Scanning electronic microscope images of fracture surfaces revealed the characteristics of fatigue. Conclusions: The number of cycles to fracture of the reciprocating WaveOne Gold Primary system was the highest amongst the tested instruments.

Evaluation of Pressure Distribution against Root Canal Walls of NiTi Rotary Instruments by Finite Element Analysis

The aim of this study was to evaluate the contact pressure distribution of two different nickel-titanium (NiTi) endodontic rotary instruments against the root canal walls and to virtually predict their centering ability during shaping with finite element analysis (FEA). Resin blocks simulating root canals were used. One was shaped with ProGlider and ProTaper Next (PTN) X1-X2 and one with ScoutRace and BioRace (BR) 1, 2 and 3. Both resin blocks were virtually replicated with computer-aided design (CAD) software. The endodontic instruments ProTaper Next (PTN) X2 and BioRace BR3 were also replicated with CAD. The NiTi instruments and the shaped blocks geometries were discretized and exported for FEA. The instrument rotation in the root canals was simulated. The finite element simulation was performed by applying an insertion and extraction force of 2.5 N with a constant rotational speed (300 rpm). To highlight possible differences between pressure distributions against the root canal portions outside and inside the canal curvature, the parameter Var was originally defined. Var values were systematically lower for PTN X2, revealing a better centering ability. FEA proved effective for the virtual prediction of the centering ability of NiTi instruments during an early design phase without the use of prototypes.

Minimally Invasive Bilateral Anterior Cingulotomy via Open Minicraniotomy Using a Novel Multiport Cisternoscope: A Cadaveric Demonstration.

Bilateral anterior cingulotomy has been used to treat chronic pain, obsessive compulsive disorder, and addictions. Lesioning of the target area is typically performed using bilateral stereotactic electrode placement and target ablation, which involves transparenchymal access through both hemispheres. To evaluate an endoscopic direct-vision lesioning using a unilateral parasagittal minicraniotomy for minimally invasive bilateral anterior cingulotomy using a novel multiport endoscope through the anterior interhemispheric fissure. A novel multiport magnetic resonance imaging (MRI)-compatible neuroendoscope prototype is used to demonstrate cadaveric cingulate lesioning through a lateral imaging port while simultaneously viewing the pericallosal arteries as landmarks through a tip imaging port. The lateral port enables extended lesioning of the gyrus while rotation of the endoscope about its axis provides access to homologous areas of both hemispheres. Cadaver testing confirmed the capability to navigate the multiport neuroendoscope between the hemispheres using concurrent imaging from the tip and lateral ports. The lateral port enabled exploration of the gyrus, visualization of lesioning, and subsequent inspection of lesions. Tip-port imaging provided navigational cues and allowed the operator to ensure that the endoscope tip did not contact tissue. The multiport design required instrument rotation in the coronal plane of only 20° to lesion both gyri, while a standard endoscope necessitated a rotation of 54°. Multiport MRI-compatible endoscopy can be effectively used in cisternal endoscopy, whereby a unilateral parasagittal minicraniotomy can be used for endoscopic interhemispheric bilateral anterior cingulotomy.

Mathematical modeling of friction stir welding considering dry and viscous friction

• Friction in friction stir welding process produces heat energy. • Force, torque and power of surface friction analytically calculated for dry and viscous friction. • Surface friction alone cannot explain workpiece heating that is sufficient for instrument immersion. In this paper, the investigation of a pre-immersion period of Friction Stir Welding process (FSW) from the mechanical point of view using analytical considerations is presented. This initial period is a part of the real technological process, when a FSW instrument reaches the touchdown point with the workpiece, preheats the contact zone, but does not penetrate the material. This approach enables an insight into FSW process on a level, where the system parameters are known and an experimental evaluation of theoretical results is possible. Beside these considerations an analytical estimation of the power input of dry and viscous friction during instrument rotation and translation in parallel is shown. These phenomena are investigated including friction between a FSW instrument and a workpiece. The influences of both dry and viscous friction are studied. Experiments have been done to validate the calculated results.

Improvement of star identification based on star trace in star images

Abstract Digital zenith camera system is a highly accurate positioning instrument in geodetic astronomy. It can capture 16 star images in one experiment unit in different azimuthal camera orientations and the stars in each star image should be identified using star catalogue. But the amount of calculation is very large, the efficiency of star identification is low. Now, the improvement of star identification is mainly through updating algorithm. Considering that there exist identical stars in these star images, this paper provides a new method to improve star identification. The star trace is deduced taking the earth rotation and instrument rotation into consideration. The errors of star trace are also analyzed. Then select the same stars that appear in the star images taken in the initial position and after rotating one angle. Using the identical stars instead of star catalogue and the star trace to identify the rest stars, the efficiency will get improved. The analysis of experimental data shows that there are many identical stars in these star images. The appearance of one star can be predicted according to the star trace. The star identification get improved by using the same stars in these star images. And it costs less time to identify the stars in star images, but the precision is approximately equal.

Influence of eye rotation on peripheral eye length measurement obtained with a partial coherence interferometry instrument

The eye rotation approach for measuring peripheral eye length leads to concern about whether the rotation influences results, such as through pressure exerted by eyelids or extra-ocular muscles. This study investigated whether this approach is valid. Peripheral eye lengths were measured with a Lenstar LS 900 biometer for eye rotation and no-eye rotation conditions (head rotation for horizontal meridian and instrument rotation for vertical meridian). Measurements were made for 23 healthy young adults along the horizontal visual field (± 30°) and, for a subset of eight participants along the vertical visual field (± 25°). To investigate the influence of the duration of eye rotation, for six participants measurements were made at 0, 60, 120, 180 and 210 s after eye rotation to ± 30° along horizontal and vertical visual fields. Peripheral eye lengths were not significantly different for the conditions along the vertical meridian (F1,7 = 0.16, p = 0.71). The peripheral eye lengths for the conditions were significantly different along the horizontal meridian (F1,22 = 4.85, p = 0.04), although not at individual positions (p ≥ 0.10) and were not important. There were no apparent differences between the emmetropic and myopic groups. There was no significant change in eye length at any position after maintaining position for 210 s. Eye rotation and no-eye rotation conditions were similar for measuring peripheral eye lengths along horizontal and vertical visual field meridians at ± 30° and ± 25°, respectively. Either condition can be used to estimate retinal shape from peripheral eye lengths.

Alternating versus Continuous Rotation: A Comparative Study of the Effect on Instrument Life

Introduction Rotary nickel-titanium instruments have multiple advantages but with the risk of more fractures because of flexure or torsion. Alternating rotation appears to be an alternative to continuous rotary movement. The objective of this study was to determine the influence of the type of instrument rotation on the frequency of fractures or deformation. Methods Instrumentation was performed on 120 molar root canals with an angle of curvature greater than 30° using alternating rotation (group A: 60° clockwise, 45° counterclockwise) and continuous rotation (group B). Results The results indicate that instruments used with alternating rotation have a higher mean number of uses (13.0) compared with the continuous rotation group (10.05); this difference was statistically significant ( p < 0.05). Conclusions The ProTaper shaping instruments (S1 and S2) are those that achieved the greatest difference in use with alternating rotation, with S2 being the most resistant to fracture or deformation with the two types of movement used.

Analysis of charge transport during lightning using balloon‐borne electric field sensors and Lightning Mapping Array

Recently, wide band measurements of the electric field near a lightning flash have been obtained by a balloon‐borne electric field sonde or Esonde. This paper develops new techniques for analyzing lightning‐associated charge transport in a thundercloud by using both the Esonde data and simultaneous Lightning Mapping Array (LMA) measurements of VHF pulses emitted during lightning breakdown processes. Innovations in this paper include the following: (1) A filtering procedure is developed to separate the background field associated with instrument rotation and cloud charging processes from the lightning‐induced electric field change. Because of the abrupt change in the signal caused by lightning, standard filtering techniques do not apply. A new mathematical procedure is developed to estimate the background electric field that would have existed if the lightning had not occurred. The estimated background field is subtracted from the measured field to obtain the lightning‐induced field change. (2) Techniques are developed to estimate the charge transport due to lightning. At any instant of time during a cloud‐to‐ground (CG) flash, we estimate the charge transport by a monopole. During an intracloud (IC) flash, we estimate the charge transport by a dipole. Since the location of the monopole and dipole changes with time, they are referred to as a dynamic monopole and a dynamic dipole. The following physical constraints are used to achieve a unique fit: charge conservation during an IC flash, separation (distance between the CG monopole charge center and the ground and separation between IC dipole charge centers both exceed a minimum threshold), location (charge is placed on lightning channel), and likelihood (after a statistical analysis based on instrument uncertainty, highly unlikely charge locations are excluded). To implement the constraint that the charge is located on the lightning channel, we develop a mathematical object called the “pulse graph.” Vertices in the graph are pulse locations obtained from the Lightning Mapping Array. Edges in the graph (that is, the pairs of vertices which are connected by line segments) are obtained by joining, in a systematic way, neighboring vertices. One CG and two IC flashes observed on 18 August 2004 near Langmuir Laboratory are analyzed. In the CG flash, initial strokes drained 12 C charge from an altitude of 5 km, while an intermediate stroke discharged 12 C from a higher charge center at 8 km. For the IC flashes, the current flow lagged behind the channel formation by time intervals on the order of 0.1 s, roughly the same time delay observed for lightning optical signals detected by NASA's Lightning Imaging Sensor.

Quantification of process measures in laparoscopic suturing

Process measures describing the generation of movement are useful for evaluation and performance feedback purposes. This study aimed to identify process measures that differ between novice and advanced laparoscopists while completing a suturing skill. A group of junior and a group of senior residents and fellows in surgery (n = 6) placed 10 laparoscopic sutures in a synthetic model. Process measures were quantified using an opto-electric motion/force sensor assembly that recorded: instrument rotation, applied forces, time, and time delays between force application and instrument rotation. Advanced trainees showed increased instrument rotation, higher peak applied force, and faster performance compared to novices (alll p < .01). However, over trials, only novices showed adaptations for instrument rotation and total time (interactions at p < .01) with no adaptation for the force application. The difference between the moments of force application and instrument rotation was not sensitive to participant training. Movement process measures can enhance our understanding of early adaptation processes and how such factors might be used as feedback to facilitate skill acquisition.

TRIDENT: An Infrared Differential Imaging Camera Optimized for the Detection of Methanated Substellar Companions11Based on observations obtained at the Canada‐France‐Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

ABSTRACTWe describe a near‐infrared camera in use at the Canada‐France‐Hawaii Telescope (CFHT) and at the 1.6 m telescope of the Observatoire du mont Mégantic (OMM). The camera is based on a Hawaii‐1 1024 × 1024 HgCdTe array detector. Its main feature is the acquisition of three simultaneous images at three wavelengths across the methane absorption bandhead at 1.6 μm, enabling, in theory, an accurate subtraction of the stellar point‐spread function (PSF) and the detection of faint close, methanated companions. The instrument has no coronagraph and features fast data acquisition, yielding high observing efficiency on bright stars. The performance of the instrument is described, and it is illustrated by laboratory tests and CFHT observations of the nearby stars GL 526, υ And, and χ And. TRIDENT can detect (6 σ) a methanated companion with ΔH = 9.5 at 0.″5 separation from the star in 1 hr of observing time. Non–common‐path aberrations and amplitude modulation differences between the three optical paths are likely to be the limiting factors preventing further PSF attenuation. Instrument rotation and reference‐star subtraction improve the detection limit by a factor of 2 and 4, respectively. A PSF noise attenuation model is presented to estimate the non–common‐path wave‐front difference effect on PSF subtraction performance.

Effect of instrument rotation on handheld keratometry

To study the effect of instrument rotation on handheld automated keratometry. Department of Optometry and Radiography, The Hong Kong Polytechnic University, Hong Kong SAR, China. In 33 recruited subjects, corneal curvature in 1 eye (randomly selected) was measured using a Medmont topographic keratometer and a Nidek handheld keratometer. In handheld keratometry, measurements were obtained holding the instrument in the upright position and rotating it anticlockwise 5 degrees, 10 degrees, and 15 degrees and then clockwise 5 degrees, 10 degrees, and 15 degrees. The sequence of measurements was randomly assigned. The steepest and flattest corneal curvatures as well as the axis along the flattest meridian were compared in different conditions. The corneal power was converted to vector representation (M, J0, J45) for a second comparison. There was a significant difference in the steepest and flattest curvatures in different conditions (repeated-measures analysis of variation, P<.05). However, the mean difference between handheld and topographic keratometry was approximately 0.25 diopter (D) for the steepest curvature and 0.05 D for the flattest curvature regardless of the direction and amount of rotation. The intraclass correlation coefficients were nearly 1, which indicated good clinical reliability. The mean difference in axis determination followed the direction and amount of rotation. With vector representation, the difference between the devices increased with the amount of rotation, especially J0 and J45. Handheld keratometry was in agreement with topographic keratometry. However, practitioners should adjust the axis manually according to the direction and amount of rotation. The difference between handheld and topographic keratometry increased with the rotational effect, which was seen with vector representation. Practitioners are advised to use the handheld keratometer in the upright position.

Effects of Quasi-Static Aberrations in Faint Companion Searches

We present the first results obtained at CFHT with the TRIDENT infrared camera, dedicated to the detection of faint companions close to bright nearby stars. The camera's main feature is the acquisition of three simultaneous images in three wavelengths (simultaneous differential imaging) across the methane absorption bandhead at 1.6 micron, that enables a precise subtraction of the primary star PSF while keeping the companion signal. The main limitation is non-common path aberrations between the three optical paths that slightly decorrelate the PSFs. Two types of PSF calibrations are combined with the differential simultaneous imaging technique to further attenuate the PSF: reference star subtraction and instrument rotation to smooth aberrations. It is shown that a faint companion with a DeltaH of 10 magnitudes would be detected at 0.5 arcsec from the primary.

Effects of rotary instrumentation and different etchants on removal of smear layer on human dentin

Statement of problem. Various methods of rotary preparation and conditioning of teeth affect surface topography and may affect the retention of dental restorations.Purpose. This study microscopically evaluated dentin surfaces prepared by different rotary instruments and etched using several types of acid etchants that have been deemed suitable dentin conditioners.Material and methods. Occlusal surfaces of 35 extracted human molars were ground wet with 320-grit silicon carbide paper to the depth of the central groove and then prepared with diamond (n = 5) and finishing burs (n = 30). Five specimens from each group were used for SEM evaluation of mechanical preparation effects. Dentin specimens (n = 5) prepared with finishing burs were then etched with 1 of 5 etchants (25% polyacrylic acid, 10% phosphoric acid, 10% citric acid, 20% lactic acid, or 32% phosphoric acid) for 10 seconds. Specimens were critical-point dried and freeze fractured for SEM analysis.Results. Diamond rotary instruments created more undulating surfaces than finishing burs. Fine grooves were observed running perpendicular to undulations and parallel to the direction of instrument rotation. Specimens prepared with finishing burs exhibited a smooth surface interrupted by only a slight granularity. The amorphous smear layer was partially removed after the application of 25% polyacrylic acid (pH 1.53), but all dentinal tubules contained plugs. The number of dentin tubules containing plug material and the amount of material in the tubules decreased noticeably with 10% phosphoric acid (pH 0.86), and the dentin surface had an appearance similar to the specimen etched with 10% citric acid (pH 1.70). The surfaces treated with 20% lactic acid (pH 1.40) produced a clearly etched surface with minimal demineralization. Etching of dentin with 32% phosphoric acid (pH 0.16) revealed significant changes in dentin with the evidence of increased tubule diameter.Conclusion. Differences related to the method of instrumentation were found in the surface characteristics of dentin. The degree of smear layer removal was related to the pH of the acid etchant. (J Prosthet Dent 2001;85:67-72.)

A new direction in laparoscopic suturing and knot tying

An intracorporeal knot can be tied using instruments, employing a method that mimics the actions of the hooked index finger as used in the one‐handed, hand tie, of open surgery. The short end of the suture, when held in the instrument jaws, can be looped around the bite section of the suture. This rotation is facilitated by a spiral spur member, which is affixed to the instrument jaw, and which captures the bite. For maximum efficiency one uses paired left and right instruments, where the spiral spurs are directed clockwise and anticlockwise, respectively. Instrument rotation and minimal instrument transfers are required for this technique. The surgical half‐hitch can be created by two entirely different actions, the instrument‐ or the hand‐tied method. Each of these methods could be considered to be the converse of the other. Ergonomically designed instruments are essential for laparoscopic surgery. A role for instrument axial rotation is recognized and extended in this new method of laparoscopic knot tying. This novel technique contrasts with all known knotting methods.

Endoscopic knot tying made easier.

A new laparoscopic instrument has been developed to facilitate intracorporeal suturing and knot tying. The instrument combines both needle-holding jaws and a loop-forming member. The handle is ergonomically designed and contains a locking mechanism. This simple technique of knot tying extends the role of instrument rotation and contrasts out all other known methods of knot tying.

Preliminary results of a balloon flight of the solar disk sextant

Preliminary results of a balloon flight on October 11, 1991, of the solar disk sextant (SDS) experiment are reported. The SDS is an instrument which measures the solar diameter at different orientations with respect to the solar polar axis. Fitting straight lines through two fixed-angle data sets with time as the independent variable yields slopes of (7.1 +/ - 1.5) x 10 exp -3 and (6.7 +/- 1.6) x 10 exp -3/mas s, consistent with the value of 6.47 x 10 exp -3/mas s expected from the earth's approach to the sun due to the orbital motion toward perihelion. Upon the instrument's rotation on its axis a sinusoidal component of the diameter measurement was observed in each rotation cycle, with a variable amplitude of about 150 mas. The present result is epsilon of (5.6 +/- 6.3) x 10 exp -6, about 30 deg offset from the polar-equator position. The absolute diameter obtained by means of the FFT definition is found to be 1919.269 +/- 0.240 arcsec or 1919.131 +/- 0.240 arcsec, depending on the orientation mode of the measurement.

Thermomechanical compaction of gutta-percha: effect of speed and duration.

Summary. The McSpadden technique of obturating root canals with thermoplasticozed gutta‐percha has been used for several years, however the technique has been criticized, among the disadvantages is temperature elevation at the root surface. The objective of this study was to test the hypothesis that the McSpadden technique when used at higher speeds or for longer time than recommended by the manufacturer would result in a temperature rise at the root surface and would also have a determental effect upon linear apical leakage.Niney maxillary incisors were divided ino six groups of 15 teeth whose root canals were prepared and subjected to different filling techniques: 5000 rev/minute for 5 seconds, 10,000 rev/minutee for 5 second, 10,000 rv/minute for 15 minute for 15 seconds, and laterally condensed gutta‐percha. Temperatures were measured by suing two J‐type thermocouples which were at the surface of each root.A strobe was used to controsl the speed of instrument rotation and a stop‐wathch was employed to time each compaction. After obturation the teeth were placed into 1 per cent methylene blue dye for 2 weeks, then the linear extent of dye penetration was measured. Statistical analysis of the data showed that the influence of speed duration of compaction were significant in causing a temperature rise and apical leakage. The results of this study support the hypothesis that the use of the McSpadden technique at a higher speed or for longer duration than recommedned can cause an adverse temperature rise at the root surface and a detrimental effect upon the quality of the apical seal.

Evaluation of dental handpieces for high speed operations

During the past 70 or 75 years there has been little significant change in the basic design of the dental handpiece for rotat­ ing instruments, because the original de­ sign of this instrument was generally satisfactory. During this same period, however, numerous refinements have been made in the basic instrument which have permitted greater flexibility and better functioning of the instrument dur­ ing the cutting of tooth tissue. Most of these developments were associated with the contemporary advances that have oc­ curred in the field of machine tool manu­ facture and the general production of precision instruments. One of the most recent refinements in dental handpieces is the development of instruments which are capable of being operated at increased speeds of rotation. The speed of rotation, of course, is rela­ tive. Speeds which were previously con­ sidered slow, medium and high now are considered to be in the slower ranges of rotation. The present optimum and maxi­ mum speeds of rotation likewise may change within a few years because of further refinements and changes in in­ strument design. At the present time there is little agree­ ment among either the manufacturers of dental engines and handpieces or dentists who use the handpiece, regarding the possible optimum and maximum speeds of rotation. It is agreed, however, that faster speeds of instrument rotation are now practical and possible when com­ pared to instruments available ten years ago. For example, until recently, manu­ facturers of engines and handpieces made available instruments that operated within the accepted range of 4,000 to 6,000 rpm. Standard equipment is now obtainable which operates at speeds from 10,000 to 20,000 rpm, and experi­ mental studies are being conducted with instruments operating at speeds of 30,000 to 75,000 rpm. The clinical or laboratory justification for speeds over 15,000 to 20,000 rpm has not been fully established. Many prob­ lems of production and manufacture of a well balanced instrument with a po­ tential long life when operated at exces­ sive speeds have not been solved. The care and maintenance of both the hand­ pieces and motor units when operated at speeds of more than 15,000 rpm con­ tinue to be a problem of importance.

Rapid Plastometry

Abstract The uses of plasticity tests, especially rapid simple tests, are discussed, with particular reference to the limitations imposed by the complex plastic behavior of unvulcanized rubbers and stocks, leading to the conclusion that simple tests are likely to be of use only for routine control of repeat, nominally identical batches. A summary is given of information collected from the industry to show under what conditions a plasticity test is required to be used in factory control. The efficiency of a plasticity test is defined, and a discussion given on how the type of instrument (rotation, extrusion or compression) and the conditions of a compression test affect both efficiency and rapidity, thus showing what conditions furnish the best form of test. It is concluded that the parallel-plate compression test is the most suitable, provided the test-piece is precompressed to a small thickness so that it can be quickly heated to the test temperature before applying the load; other factors considered are the size of compression plates and of test-piece, use of release medium (e.g., thin paper), degree of precompression, preheat period, load, compression period, and temperature. Existing rapid plastometers are described, including full details of the new Wallace modification of the Hoekstra instrument, which embodies the recommended conditions of test.