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Sample records for simulated curved canals

  1. Comparison of canal transportation in simulated curved canals prepared with ProTaper Universal and ProTaper Gold systems

    PubMed Central

    Muniz, Brenda Leite; Pires, Frederico; Belladonna, Felipe Gonçalves; Neves, Aline Almeida; Souza, Erick Miranda; De-Deus, Gustavo

    2016-01-01

    Objectives The purpose of this study was to assess the ability of ProTaper Gold (PTG, Dentsply Maillefer) in maintaining the original profile of root canal anatomy. For that, ProTaper Universal (PTU, Dentsply Maillefer) was used as reference techniques for comparison. Materials and Methods Twenty simulated curved canals manufactured in clear resin blocks were randomly assigned to 2 groups (n = 10) according to the system used for canal instrumentation: PTU and PTG groups, upto F2 files (25/0.08). Color stereomicroscopic images from each block were taken exactly at the same position before and after instrumentation. All image processing and data analysis were performed with an open source program (FIJI). Evaluation of canal transportation was obtained for two independent canal regions: straight and curved levels. Student's t test was used with a cut-off for significance set at α = 5%. Results Instrumentation systems significantly influenced canal transportation (p < 0.0001). A significant interaction between instrumentation system and root canal level (p < 0.0001) was found. PTU and PTG systems produced similar canal transportation at the straight part, while PTG system resulted in lower canal transportation than PTU system at the curved part. Canal transportation was higher at the curved canal portion (p < 0.0001). Conclusions PTG system produced overall less canal transportation in the curved portion when compared to PTU system. PMID:26877984

  2. A comparison of the shaping ability of reciprocating NiTi instruments in simulated curved canals

    PubMed Central

    Yoo, Young-Sil

    2012-01-01

    Objectives The study was to compare the shaping ability of Reciproc (VDW) and WaveOne (Dentsply Maillefer) instruments compared with ProTaper, Profile and hand instrument during the preparation of simulated root canals. Materials and Methods Five groups (n = 5) were established. Reciproc, WaveOne, ProTaper, Profile and K file (K-flexo file) were used to prepare the resin simulated canals. A series of preoperative and postoperative images were taken by a microscope and superimposed in 2 different layers. The amount of resin removed from both the inner and the outer sides of the canal was measured to the level of 10 mm from the apical tip, with a 1 mm increment. Results The mean of resin removal from the inner canal wall was not different from the outer canal wall for Reciproc and WaveOne groups at apical third (1 - 3 mm level). There was no difference in the change of working length and maintenance of canal curvature. NiTi instruments are superior to stainless-steel K file in their shaping ability. Conclusions Within the limitation of this present study, Reciproc and WaveOne instruments maintained the original canal curvature in curved canals better than ProTaper and Profile, which tend to transport towards the outer canal wall of the curve in the apical part of the canal. PMID:23430033

  3. Method for Constructing Standardized Simulated Root Canals.

    ERIC Educational Resources Information Center

    Schulz-Bongert, Udo; Weine, Franklin S.

    1990-01-01

    The construction of visual and manipulative aids, clear resin blocks with root-canal-like spaces, for simulation of root canals is explained. Time, materials, and techniques are discussed. The method allows for comparison of canals, creation of any configuration of canals, and easy presentation during instruction. (MSE)

  4. Cyclic Fatigue Resistance and Force Generated by OneShape Instruments during Curved Canal Preparation

    PubMed Central

    Zhang, Xiaolei

    2016-01-01

    Objectives To evaluate the cyclic fatigue resistance and the force generated by OneShape files during preparation of simulated curved canals. Methods Six OneShape files (the test) and six ProTaper F2 files (the control) were subject to the bending ability test. Another thirty files of each type were used to prepare artificial canals (n = 60), which were divided into 3 groups according to respective curvatures of the canals (30°, 60°, and 90°). The numbers of cycles to fatigue (NCF) as well as the positive and negative forces that were generated by files during canal preparation were recorded. The scanning electron microscopy was applied to detect the fracture surfaces. Results Compared with ProTaper F2 files, the bending loads of OneShape files were significantly lower at deflections of 45°(P < .05), 60° (P < .05) and 75° (P < .01). No significant difference was found at 30°. OneShape files presented a higher NCF in both 60° and 90° canals than the control (P < .01). No significant difference of NCF was found between OneShape and ProTaper files in 30° canals. During the preparation of 30° canals by both files, the negative forces were dominant. With the increase of the curvature, more positive forces were observed. When the OneShape Files were compared with the control, significant different forces were found at D3 and D2 (P < .05) in 30° canals, at D2 (P < .05), D1 (P < .01) and D0 (P < .01) in 60° canals, and at D4 and D3 (P < .01) in 90° canals. Conclusions OneShape files possessed a reliable flexibility and cyclic fatigue resistance. According to the assessments of the forces generated by files, OneShape instruments performed in a more fatigue-resistant way during curved canal preparation, compared with the ProTaper F2 files. PMID:27513666

  5. Comparison of two sonic handpieces during the preparation of simulated root canals.

    PubMed

    Dummer, P M; Hutchings, R; Hartles, F R

    1993-05-01

    The objective of this study was to assess and compare two sonic handpieces during the preparation of simulated root canals. A total of 60 simulated canals in clear resin blocks of various angles and positions of curvature were prepared using Shaper files activated either by an MM1500 Sonic Air or an MM1400 Mecasonic handpiece. Each handpiece was used to prepare 30 canals using an identical preparation procedure which involved a linear filing motion and an anticurvature technique in curved canals. The efficacy of the handpieces was determined for straight and curved canals separately and included an assessment of loss of canal length, weight loss from the blocks, smoothness of canal walls, transportation and overall shape of the prepared canals. Canals were prepared rapidly and effectively by both handpieces. Overall, the MM1500 handpiece was associated with significantly less distance loss (P < 0.05) and significantly more loss of weight (P < 0.01). Only four prepared canals (8%) had hour-glass shapes displaying zips and elbows, each handpiece created two. Only two canals (4%) had danger zones, both were created by the MM1400 handpiece. There was little difference between the handpieces in terms of the smoothness of canal walls, the direction and amount of transportation or the overall shape of canals. Under the conditions of this study, the new MM1400 Mecasonic handpiece performed as well as the established MM1500 Sonic Air. PMID:8406963

  6. Shaping ability of Lightspeed rotary nickel-titanium instruments in simulated root canals. Part 2.

    PubMed

    Thompson, S A; Dummer, P M

    1997-12-01

    The aim of this laboratory based study was to determine the shaping ability of Lightspeed nickel-titanium rotary instruments in simulated root canals. A total of 40 canals with four different shapes in terms of angle and position of curve were prepared with Lightspeed instruments using the stepback technique recommended by the manufacturer. This report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation, and overall postoperative shape. Preoperative and postoperative images of the canals were taken using a video camera attached to a computer with image analysis software. The preoperative and postoperative views were superimposed to highlight the amount and position of material removed during preparation. Only one (2.5%) zip and one elbow were created, with no ledges, perforations, danger zones, or blockages being produced. At specific points along the canal length there were highly significant differences (p < 0.001) between the canal shapes in total canal width and in the amount of resin removed from the inner and outer aspects of the curve. The direction of canal transportation at the end point of preparation was most frequently toward the outer aspect of the curve; although in half of the canals, transportation was either directed toward the inner aspect or not observed. At the apex of the curve, the beginning of the curve, and halfway to the orifice, transportation was reversed with the majority of canals being transported toward the inner aspect of the curve. Mean absolute transportation was small and was below 0.06 mm at every position except the orifice. Overall, Lightspeed rotary instruments prepared canals well and would appear to be a valuable addition to the endodontic armamentarium. PMID:9487850

  7. Shaping ability of the M4 handpiece and Safety Hedstrom files in simulated root canals.

    PubMed

    Lloyd, A; Jaunberzins, A; Dhopatkar, A; Bryant, S; Dummer, P M

    1997-01-01

    The aim of this study was to assess the shaping ability of the M4 reciprocating handpiece and Safety Hedstrom files in simulated canals. A total of 40 simulated canals of various angles and positions of curvature were prepared with an M4 handpiece using Safety Hedstrom files oriented with the ground, flattened surface towards the inner aspect of the curve. A standard regimen was adopted throughout. Pre- and post-operative longitudinal images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount and location of resin material removed as a result of preparation were determined from composite images of superimposed pre- and post-operative views. Preparation time varied significantly (P < 0.001) between the canal types; overall, 20 degrees canals were prepared more quickly than 40 degrees canals. Zips and elbows were observed in 16 out of the 40 canals with most (11) being created in 40 degrees specimens. Ledges were found in 19 canals and perforations in only 1. There were no significant differences between canal shapes for these aberrations. Excessive removal of material from the inner aspect of the canal at the curve to create a danger zone was found in 20 canals, but only in those with 40 degrees curves. Significant differences in total canal width between the canal types were seen at the zips (P < 0.05), elbows (P < 0.05) and danger zones (P < 0.001). Transportation at the danger zones varied significantly (P < 0.001) between canal types. Under the conditions of this study, the M4 handpiece and Safety Hedstrom files created hour-glass preparations in a substantial proportion of canals. In reality, the Safety Hedstrom file with its one flattened surface was ineffective at reducing removal of material along the inner aspect of canal curves in severely curved specimens and clearly has the potential to create strip perforations in teeth. PMID:9477790

  8. Simulation of acid water movement in canals

    NASA Astrophysics Data System (ADS)

    Van Truong, To; Tat Dac, Nguyen; Ngoc Phienc, Huynh

    1996-05-01

    An attempt to tackle the problem of the propagation of acid water in canals is described, and a mathematical model to simulate the acid water movement is developed, in which the jurbanite equilibrium is found to prevail. The processes of settling owing to sedimentation, precipitation and redissolution have been considered in the modelling. Data available from Tan Thanh, in the Plain of Reeds of the Mekong Delta in Viet Nam, are used as a case study.

  9. DELightcurveSimulation: Light curve simulation code

    NASA Astrophysics Data System (ADS)

    Connolly, Samuel D.

    2016-02-01

    DELightcurveSimulation simulates light curves with any given power spectral density and any probability density function, following the algorithm described in Emmanoulopoulos et al. (2013). The simulated products have exactly the same variability and statistical properties as the observed light curves. The code is a Python implementation of the Mathematica code provided by Emmanoulopoulos et al.

  10. WEAR PROMOTED IN THE APICAL THIRD OF SIMULATED CANALS AFTER INSTRUMENTATION WITH PROTAPER UNIVERSAL SYSTEM

    PubMed Central

    da Silva, Kathrein Tapia; Grazziotin-Soares, Renata; Limongi, Orlando; Irala, Luis Eduardo Duarte; Salles, Alexandre Azevedo

    2009-01-01

    Objective: This study evaluated the wear in the apical third of simulate canals after preparation with ProTaper Universal Rotary System. Material and Methods: 24 sets of instruments were used in 24 simulated canals in transparent epoxy resin blocks with degree of curvature of either 20°or 40°. The canals were photographed preoperatively and after preparation of the apical stop with ProTaper F3, F4 and F5 instruments. The initial and final images were exported to Adobe Photoshop® software and superimposed to detect the root canal wall differences (in mm) between them, in two points located 1 (A) and 5 (B) mm from the point where the working length was established. Data were subjected to analysis of variance to verify the existence of interaction among the factors: canal curvature, instrument size and curve location. Significant level was set at 5%. Results: Regardless of the location and the canal curvature, F4 and F5 instruments produced the greatest wear (p<0.05). Conclusions: There was a deviation from the original pathway towards the outside of the root curvature in both analyzed points. All instruments produced canal transportation, but the F4 and F5 instruments produced more than the other instruments, and should thus be used with care in curved canals. PMID:19936533

  11. A comparison of the ability of K-files and Hedstrom files to shape simulated root canals in resin blocks.

    PubMed

    Alodeh, M H; Dummer, P M

    1989-09-01

    A total of 50 simulated root canals in clear resin blocks with various degrees and positions of curvature were prepared by either K-files or Hedstrom files. Each file type was used to prepare 25 canals employing an in/out circumferential filing motion. The efficacy of the files was assessed by instrumentation time, deformation and fracture of instruments, and loss of working distance. The shape of the prepared canals was assessed by direct observation and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. Overall, canal shaping with Hedstrom files was quicker and more effective. Both file types prepared straight canals in an appropriate manner but the majority of prepared curved canals were hourglass in shape. In general, K-files created zips which were wider and thus more pronounced than those produced by Hedstrom files. Wide 'danger zones' were also regularly created. The location of the aberrations depended largely on the original shape of the canal and in particular on the position of the beginning of the canal curve. Under the conditions of this study, the manipulation of K-files and Hedstrom files in a simple in/out circumferential filing motion proved an unsatisfactory method of shaping simulated curved root canals in resin blocks. PMID:2637229

  12. Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 2.

    PubMed

    Thompson, S A; Dummer, P M

    1997-07-01

    The aim of this laboratory-based study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. A total of 40 canals with four different shapes in terms of angle and position of curve were prepared with NT Engine and McXim instruments, using the technique recommended by the manufacturer. Part 2 of this report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall postoperative shape. Pre- and postoperative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and postoperative views were superimposed to highlight the amount and position of material removed during preparation. No zips, elbows, perforations or danger zones were created during preparation. Forty-two per cent of canals had ledges on the outer aspect of the curve, the majority of which (16 out of 17) occurred in canals with short acute curves. There were significant differences (P < 0.001) between canal shapes in terms of the incidence of ledges. There were highly significant differences (P < 0.001) between the canal shapes in total canal width at specific points along the canal length and in the amount or resin removed from the inner and outer aspects of the curve. The direction of canal transportation at the end-point of preparation was most frequently towards the outer aspect of the curve, especially in canals with 40 degrees curves. At the beginning of the curve, transportation in the majority of canals was towards the inner aspect of the curve. Mean absolute transportation was less than 0.03 mm throughout the curve and towards the end-point, with significant differences between canal shapes occurring at the apex (P < 0.05) and at the beginning of the curve (P < 0.001). Under the conditions of this study, NT Engine and McXim rotary nickel-titanium instruments created no aberrations

  13. Shaping ability of Quantec Series 2000 rotary nickel-titanium instruments in simulated root canals: Part 2.

    PubMed

    Thompson, S A; Dummer, P M

    1998-07-01

    The aim of this laboratory based study was to determine the shaping ability of Quantec Series 2000 nickel-titanium rotary instruments in simulated root canals. A total of 40 canals with four different shapes in terms of angle and position of curve were prepared with Quantec Series 2000 instruments using the technique recommended by the manufacturer. Part 2 of this report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall post-operative shape. Pre- and post-operative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and post-operative views were superimposed to highlight the amount and position of material removed during preparation. Twenty-one zips and elbows were created during preparation with a significant difference (P < 0.005) between canal shapes in terms of the incidence of aberrations. Four perforations were created, with significant differences (P < 0.005) between the canal shapes; three ledges were also created but no danger zones. Highly significant differences (P < 0.001) were apparent between the canal shapes in total canal width at specific points along the canal length and in the amount of resin removed from the inner and outer aspects of the curve. Canal transportation at the end-point of preparation was most frequently directed towards the outer aspect of the curve, and without exception in canals with 40 degrees curves. At the beginning of the curve, transportation became more evenly balanced between the inner and outer aspect of the curve, although predominated towards the outer. Transportation was generally directed towards the outer at the orifice, especially in canals with 40 degrees curves. Mean absolute transportation at the various measurement points was less than 0.11 mm; significant differences occurred between canal shapes at the end-point of preparation (P < 0.0001), at the

  14. Centering ability and dentin removal of rotary systems in curved root canals

    PubMed Central

    Moradi, Saeed; Talati, Ali; Monajem Zadeh, Ali

    2009-01-01

    INTRODUCTION: The aim of this study was to compare centering ability and dentin removal of three rotary systems in curved root canals of extracted teeth. MATERIALS AND METHODS: Sixty root canals of mandibular first molars with curvatures ranging between 25-35o were divided into three groups of 20 teeth each. Based on pre-instrumentation radiographs that assessed the angle and the radius of canal curvatures, teeth with curvatures were equally spread between the three groups. The root canals were sectioned horizontally at two levels before preparation and then remounted onto the muffle. All root canals were prepared using a low-torque control motor with Mtwo or Medin or Race instruments. Cross sectional images were obtained before and after instrumentation. Cross-sectional area and centering ability were evaluated. The data were analyzed using the one-way ANOVA and Tukey tests. RESULTS: Neither instrument fracture nor permanent deformation occurred during preparations. The best centering ability was obtained by Mtwo instruments compare to Race and Medin instruments. In the coronal and middle sections, Mtwo removed less dentin than Race and Medin; while the difference in the apical section was not significant. CONCLUSION: Under the conditions of this study, the debridement of root canals was more conservative with Mtwo. The canals prepared with these instruments were better centered in all three regions of the root. PMID:24003328

  15. Shaping ability of Mity Roto 360 degrees and Naviflex rotary nickel-titanium instruments in simulated root canals. Part 2.

    PubMed

    Thompson, S A; Dummer, P M

    1998-02-01

    The aim of this study was to determine the shaping ability of Mity Roto 360 degrees and Naviflex rotary nickel-titanium instruments in simulated canals. Forty simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by both sets of instruments using a stepdown approach. This study describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation, and thus the overall postoperative shape. Pre- and postoperative images of the canals were taken using a videocamera attached to a computer with image analysis software. The pre- and postoperative views were superimposed to highlight the amount and position of material removed during preparation. Neither Mity Roto 360 degrees nor Naviflex instruments created any zips or elbows. Ledges were produced in 20 (50%) canals prepared with Mity instruments and in 29 (72%) canals prepared with Naviflex instruments. Statistically significant differences (p < 0.001) between canal shapes occurred in relation to the incidence of ledges with 40 degrees canals (35) associated with more aberrations than 20 degrees canals (14); the position of the beginning of the curve had no effect. The distance of ledges from the end point of preparation was also affected significantly (p < 0.01) by canal shape. Neither instrument created any perforations or danger zones. At specific positions along the canal length, canal shape had a significant influence on total width and the amount of material removed from the inner and outer aspects of the canal curve. The direction of canal transportation at the end point of preparation was most frequently toward the outer aspect of the curve in canals prepared with Naviflex instruments, whereas the Mity instruments produced a more balanced preparation. At the apex and beginning of the curve, transportation with both instruments was generally toward the outer aspect of the curve. Overall

  16. A comparison of stainless steel and nickel-titanium K-files in curved root canals.

    PubMed

    Chan, A W; Cheung, G S

    1996-11-01

    The purpose of this study was to determine the effects of hand instrumentation using traditional stainless steel K-files and nickel-titanium K-files on the final shape of curved root canals. A total of 24 moderately curved canals in the mesial roots in extracted human mandibular first molars were randomly divided into two groups. These were instrumented manually using either stainless steel or nickel-titanium, K-files with the stepdown technique. The cross-sectional shape of each canal at three different horizontal levels were captured, before and after instrumentation, into a computer for comparison using image analyser software. Three parameters at each level were evaluated: (i) amount of dentine removed; (ii) least remaining dentine thicknesses on mesial and furcal aspects; and (iii) the amount and direction of canal transportation. The results showed that the two file types removed similar amounts of dentine at all three levels examined. The nickel-titanium files left a thicker layer of dentine on both the mesial and furcal aspects than stainless steel files. However, the difference was not significant (pooled T-test, P > 0.05). Both types of files transported the centre of the canals but the nickel-titanium instrument seemed to be safer because of the reduced amount of transportation towards the danger areas. PMID:10332236

  17. Comparison of two stainless steel files to shape simulated root canals.

    PubMed

    al-Omari, M A; Bryant, S; Dummer, P M

    1997-01-01

    The aim of this study was to compare the shaping ability of two stainless steel files using simulated canals. A total of 80 simulated canals of various angles and positions of curvature were prepared by hand using either Mani K-Files or Micro Mega K-Files. Following orifice enlargement each file type was used to prepare 40 canals employing a linear filing motion and an anticurvature stepback technique. Pre- and post-operative longitudinal images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount of material removed as a result of preparation were determined from composite images of superimposed pre- and post-operative views. Overall, canal preparation with Mani K-Files was significantly quicker (P < 0.005) and was associated with fewer instrument failures. Zips and elbows were observed in 70% of specimens with significantly more (P < 0.05) occurring following preparation with Micro Mega K-Files. Mani K-Files created significantly more (P < 0.01) danger zones. Micro Mega K-Files created significantly wider (P < 0.001) zips with significantly more (P < 0.01) resin removed from the outer aspect of the curves and, thus, significantly more (P < 0.01) transportation. Canal shape had a significant influence on preparation time (P < 0.001), the incidence of zips (P < 0.05) and danger zones (P < 0.005), the width of zips (P < 0.001) and transportation at the zips (P < 0.001). Under the conditions of this study, Mani K-Files were more effective than Micro Mega K-Files and produced canals with better shapes. Original canal shape had a substantial influence on the outcome of shaping procedures. PMID:9477792

  18. Shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals. Part 2.

    PubMed

    Thompson, S A; Dummer, P M

    1997-01-01

    The aim of this study was to determine the shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using a step-down approach. Part 2 of this two-part report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and the overall postoperative shape. No zips, perforations or danger zones were created although 24 specimens (60%) had ledges on the outer wall of the canal. The incidence of ledges differed significantly (P < 0.001) between the canal shapes. At specific points along the canal length there were highly significant differences (P < 0.001) in total canal width and in the amount of material removed from the inner and outer aspects of the curve between the various canal shapes. Overall, 40 degrees canals were wider than 20 degrees canals and canals with curves which began 8 mm from the orifice were wider than 12 mm canals. The direction of canal transportation at the end-point of preparation was balanced between inner and outer in the 8 mm canals, but more often towards the outer in the 12 mm canals. At the apex of the curve, transportation was invariably towards the outer aspect of the curvature. At the beginning of the curve, transportation was more balanced between inner and outer. Mean absolute transportation, ignoring direction, was generally greater in 40 degrees canals and in those with the curve beginning 8 mm from the orifice. Of particular importance was the finding that excessive resin was removed from the outer aspect of the canal at the apex of the curve which was often associated with irregular widened areas or ledges. This is in contrast to the pattern of tissue removal found with stainless steel hand instruments where more resin is removed from the inner aspect of the

  19. Canals

    ERIC Educational Resources Information Center

    Winkleman, Michael

    1974-01-01

    In the mid-1800's, the canal system in the U.S. was thriving. But, by the end of that century, roads and railways had replaced these commercial thoroughfares. Renewed interest in the abandoned canals is now resulting in renovation and ecological site development in Pennsylvania and New Jersey. (MA)

  20. Cone-beam computed tomography analysis of curved root canals after mechanical preparation with three nickel-titanium rotary instruments

    PubMed Central

    Elsherief, Samia M.; Zayet, Mohamed K.; Hamouda, Ibrahim M.

    2013-01-01

    Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes (surface area, changes in curvature and transportation) during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files (P = 0.226). During preparation there was failure of only one file (the protaper group). In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems. PMID:23885273

  1. Shaping ability of ProFile rotary nickel-titanium instruments with ISO sized tips in simulated root canals: Part 2.

    PubMed

    Bryant, S T; Thompson, S A; al-Omari, M A; Dummer, P M

    1998-07-01

    The aim of this study was to determine the shaping ability of ProFile 0.04 taper rotary nickel-titanium instruments with ISO sized tips in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using the 'crown down' approach recommended by the manufacturer. Part 2 of this two-part report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and the overall post-operative shape. Out of 37 completed specimens 9 zips (24%) and one ledge (3%) were created, but no perforations or danger zones were found. There were significant differences (P < 0.01) between canal shapes for the incidence of zips and elbows but not for their distance from the end-point of preparation. At specific positions along the canal length there were significant differences between the canal types in terms of their mean total width; overall, at the end-point of preparation and along the curved portion of the canals those specimens with 40 degrees curves were widest. This trend continued for the width of material removed from the outer aspect of the canal curves, whereas along the inner aspect of curves more material was removed in the 20 degrees canals. Overall, transportation was towards the outer aspect of the curve at the end-point of preparation and along the curved portion of canals but more balanced along the straight coronal section. Absolute transportation was small and below 0.1 mm at every position including the zips. Under the conditions of this study, ProFile nickel-titanium rotary instruments with ISO sized tips produced a larger number of zips than expected; however, the degree of zipping was limited and relatively minor. PMID:9823118

  2. Effect of Patency File on Transportation and Curve Straightening in Canal Preparation with ProTaper System

    PubMed Central

    Hasheminia, Seyed Mohsen

    2013-01-01

    The aim of this ex vivo study was to evaluate the effect of using a patency file on apical transportation and curve straightening during canal instrumentation with the ProTaper rotary system. Seventy permanent mandibular first molars with mesiobuccal canals, measuring 18–23 mm in length and with a 25–40° curvature (according to the Schneider method), were selected. The working lengths were determined and the teeth were mounted and divided into two experimental groups: (A) prepared by the ProTaper system without using a patency file (n = 35) and (B) prepared by the ProTaper system using a patency file (n = 35). Radiographs taken before and after the preparation were imported into Photoshop software and the apical transportation, and curve straightening were measured. Data were analyzed using independent t-test. Partial correlation analysis was performed to evaluate the relationship between the initial curvature, transportation, and curve straightening (α = 0.05). Using a patency file during canal preparation significantly decreased both apical transportation and curve straightening (P < 0.001). There were significant relationships between the angle of curvature, transportation and curve straightening in pairs (P < 0.001). Apical patency is recommended during root canal preparation with the ProTaper rotary system. PMID:24159390

  3. Real-time evaluation of two light delivery systems for photodynamic disinfection of Candida albicans biofilm in curved root canals.

    PubMed

    Sabino, C P; Garcez, A S; Núñez, S C; Ribeiro, M S; Hamblin, M R

    2015-08-01

    Antimicrobial photodynamic therapy (APDT) combined with endodontic treatment has been recognized as an alternative approach to complement conventional root canal disinfection methods on bacterial biofilms. We developed an in  vitro model of bioluminescent Candida albicans biofilm inside curved dental root canals and investigated the microbial reduction produced when different light delivery methods are employed. Each light delivery method was evaluated in respect to the light distribution provided inside curved root canals. After conventional endodontic preparation, teeth were sterilized before canals were contaminated by a bioluminescent strain of C. albicans (CEC789). Methylene blue (90 μM) was introduced into the canals and then irradiated (λ = 660 nm, P = 100 mW, beam diameter = 2 mm) with laser tip either in contact with pulp chamber or within the canal using an optical diffuser fiber. Light distribution was evaluated by CCD camera, and microbial reduction was monitored through bioluminescence imaging. Our findings demonstrated that the bioluminescent C. albicans biofilm model had good reproducibility and uniformity. Light distribution in dental tissue was markedly dependent on the light delivery system, and this strategy was directly related to microbial destruction. Both light delivery systems performed significant fungal inactivation. However, when irradiation was performed with optical diffuser fiber, microbial burden reduction was nearly 100 times more effective. Bioluminescence is an interesting real-time analysis to endodontic C. albicans biofilm inactivation. APDT showed to be an effective way to inactivate C. albicans biofilms. Diffuser fibers provided optimized light distribution inside curved root canals and significantly increased APDT efficiency. PMID:25060900

  4. Shaping Ability of Reciproc, UnicOne, and Protaper Universal in Simulated Root Canals.

    PubMed

    Maia Filho, Etevaldo Matos; Rizzi, Cláudia de Castro; Coelho, Matheus Bandeca; Santos, Sara Freitas; Costa, Luzia Mayanne Oliveira; Carvalho, Ceci Nunes; Tavarez, Rudys Rodolfo de Jesus; Soares, Janir Alves

    2015-01-01

    The study aimed to compare the shaping effects, preservation of the original curvature, and transportation of the apical foramen of Reciproc (VDW, Munich, Germany), UnicOne (Medin, Nové Město na Moravě, Czech Republic), and Protaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) in simulated root canals. Thirty resin blocks with simulated curved root canals were distributed into three groups (n = 10), and prepared using Reciproc (RCp), UnicOne (UnO) and the Protaper Universal (PTu). Standardized photographs were taken before and after the instrumentation, after which they were superimposed. Measurements were taken of the quantity of resin removed from the inner and outer walls of the curvature at 6 levels, the curvature angles before and after instrumentation, and the transportation of the apical foramen. RCp obtained the highest values for amount of resin removed from the inner wall while UnO demonstrated similar shaping on both the inner and outer walls. PTu produced the greatest transportation of foramen when compared to the reciprocating instruments. There was no significant difference between the groups in terms of the change in angle (P > 0.05). All the instruments were capable of maintaining the original curvature of the root canal; however, the UnO, which used reciprocating movement, produced more conservative shapes with lower foramen transportation. PMID:25950022

  5. Shaping Ability of Reciproc, UnicOne, and Protaper Universal in Simulated Root Canals

    PubMed Central

    Matos Maia Filho, Etevaldo; de Castro Rizzi, Cláudia; Bandeca Coelho, Matheus; Freitas Santos, Sara; Mayanne Oliveira Costa, Luzia; Nunes Carvalho, Ceci; Rodolfo de Jesus Tavarez, Rudys; Alves Soares, Janir

    2015-01-01

    The study aimed to compare the shaping effects, preservation of the original curvature, and transportation of the apical foramen of Reciproc (VDW, Munich, Germany), UnicOne (Medin, Nové Město na Moravě, Czech Republic), and Protaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) in simulated root canals. Thirty resin blocks with simulated curved root canals were distributed into three groups (n = 10), and prepared using Reciproc (RCp), UnicOne (UnO) and the Protaper Universal (PTu). Standardized photographs were taken before and after the instrumentation, after which they were superimposed. Measurements were taken of the quantity of resin removed from the inner and outer walls of the curvature at 6 levels, the curvature angles before and after instrumentation, and the transportation of the apical foramen. RCp obtained the highest values for amount of resin removed from the inner wall while UnO demonstrated similar shaping on both the inner and outer walls. PTu produced the greatest transportation of foramen when compared to the reciprocating instruments. There was no significant difference between the groups in terms of the change in angle (P > 0.05). All the instruments were capable of maintaining the original curvature of the root canal; however, the UnO, which used reciprocating movement, produced more conservative shapes with lower foramen transportation. PMID:25950022

  6. Dynamic Curving Simulation of Tilting Train

    NASA Astrophysics Data System (ADS)

    Zeng, Jing; Luo, Ren

    The application of carbody tilting technology is the most efficient way to raise train speed during curve negotiations. This paper mainly deals with the dynamic performance simulation of the tilting train. Through the establishment of the nonlinear mathematical model for the titling train electromechanical coupled system, the carbody tilting control law, bogie radial steering mechanism, and titling train curving performance are investigated. The effect of time delay caused by the sensing and control system on the tilting performance of the train is analyzed, and the compensation methods for the time delay effect are studied.

  7. Experimental simulation of closed timelike curves.

    PubMed

    Ringbauer, Martin; Broome, Matthew A; Myers, Casey R; White, Andrew G; Ralph, Timothy C

    2014-01-01

    Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved, leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into nonlinearities and the emergence of causal structures in quantum mechanics--essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the nonlinear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction and the influence of decoherence. PMID:24942489

  8. Matters of simulation of the semicircular canal system

    NASA Technical Reports Server (NTRS)

    Gurfinkel, V. S.; Petukhov, S. V.

    1977-01-01

    A scale model of the human semicircular canal system was developed based on the theory of dynamic similitude. This enlarged model makes it convenient to conduct tests on the vestibular processes and dynamics in the semicircular canals. Tests revealed hydromechanical interaction between canals, with asymmetry of the conditions of movement of the endolymph in the canals in opposite directions. A type of vestibular reactions, occurring with angular oscillations of the head, was predicted and demonstrated using this model and human test subjects.

  9. A Comparison of Apical Transportation in Severely Curved Canals Induced by Reciproc and BioRaCe Systems

    PubMed Central

    Nabavizadeh, Mohammadreza; Abbaszadegan, Abbas; Khojastepour, Leila; Amirhosseini, Mohsen; Kiani, Ebrahim

    2014-01-01

    Introduction: Preserving the apical root structure during cleaning and shaping of the canal has always been a challenge in endodontics particularly when the root canals are curved. The purpose of this in vitro study was to compare the apical transportation induced by the Reciproc and BioRaCe rotary systems in preparing the mesiobuccal root canal of the human maxillary molars. Materials and Methods: The mesiobuccal canals of sixty extracted maxillary molars with curvature angle of 25˚-35˚ were selected and randomly assigned into two groups. Each canal was prepared by either Reciproc or BioRaCe rotary systems. A double-digital radiographic technique and AutoCAD software were used to compare the apical transportation at 0.5, 1, 2, 3, 4 and 5 mm distances from the working length (WL). The distance between the master apical rotary file and the initial K-file in the superimposed radiographs determined the amount of apical transportation. An independent t-test was used to compare the groups. The statistical significant level was set at 0.05. Results: Apical transportation of the Reciproc group was significantly greater than the BioRaCe group in all distances (P<0.001). The maximum apical transportation occurred in the Reciproc group at 0.5 mm from the WL (0.048±0.0028 mm) and the minimum occurred for BioRaCe at 5 mm from the WL (0.010±0.0005 mm). Conclusions: The Reciproc system produced significantly more apical transportation than the BioRaCe, but this fact does not seem to negatively alter the clinical success or quality of root canal treatment. PMID:24688580

  10. Efficacy of Reciproc® and Profile® Instruments in the Removal of Gutta-Percha from Straight and Curved Root Canals ex Vivo

    PubMed Central

    Marfisi, Karem; Plotino, Gianluca; Clavel, Tatiana; Duran-Sindreu, Fernando; Roig, Miguel

    2015-01-01

    ABSTRACT Objectives To compare the efficacy of Reciproc® (VDW GmbH) and ProFile® (Dentsply Maillefer) instruments at removing gutta-percha from straight and curved root canals ex vivo filled using the cold lateral condensation and GuttaMaster® (VDW GmbH) techniques. Material and Methods Forty mesial roots of mandibular molars with two curved canals and 80 single-rooted teeth with straight root canals, a total of 160 root canals, were randomly assigned to eight groups (canals per group = 20) according to filling technique, retreatment instrument and root canal curvature as follows: Group I, cold lateral condensation/ProFile®/straight; Group II, cold lateral condensation/ProFile®/curved; Group III, cold lateral condensation/Reciproc®/straight; Group IV, cold lateral condensation/Reciproc®/curved; Group V, GuttaMaster®/ProFile®/straight; Group VI, GuttaMaster®/ProFile®/curved; Group VII, GuttaMaster®/Reciproc®/straight; and Group VIII, GuttaMaster®/Reciproc®/curved. The following data were recorded: procedural errors, retreatment duration and canal wall cleanliness. Means and standard deviations were calculated and analysed using the Kruskal-Wallis test, one-way analysis of variance and Tukey’s test (P < 0.05). Results Reciproc® instruments were significantly faster than ProFile® instruments at removing GuttaMaster® from both straight (P = 0.0001) and curved (P = 0.0003) root canals. Reciproc® were statistically more effective than ProFile® instruments in removing GuttaMaster® from straight root canals (P = 0.021). Regardless of filling technique or retreatment instrument, gutta-percha was removed more rapidly from curved than from straight root canals (P = 0.0001). Conclusions Neither system completely removed filling material from the root canals. Compared with ProFile® instruments, Reciproc® instruments removed GuttaMaster® filling material from straight and curved root canals more rapidly. PMID:26539283

  11. Computer simulation and capacity evaluation of Panama Canal alternatives

    SciTech Connect

    Rosselli, A.T.; Bronzini, M.S.; Weekly, D.A.

    1994-12-31

    The Operating Characteristics and Capacity Evaluation (OCCE) Study was one of the components of a group of studies of future alternatives to the Panama Canal, sponsored by a study commission formed by the governments of Panama, the US and Japan. The basic tool in the conduct of the study was the Waterway Analysis Model (WAM), developed originally by the US Army Corps of Engineers for use on the US inland waterway system and adapted under OCCE for study of Panama Canal alternatives. The study synthesized the many alternative plans for the Canal proposed historically into four basic groups: High-Rise Lock Canal, Low-Rise Lock Canal, Sea-Level Canal and Status Quo Canal. For economy, the sea-level cases were based on, essentially, a single-lane canal, in conjunction with the status quo canal. Hydraulic and navigation studies indicted that to achieve safe navigation, tide gates or locks would be required to control currents that would otherwise be generated by the differences in tides between the two oceans. The alternatives studied in detail are illustrated in the body of the paper.

  12. Shaping ability of rotatory or reciprocating instruments in curved canals: a micro-computed tomographic study.

    PubMed

    Jardine, Alexander Pompermayer; Rosa, Ricardo Abreu da; Santini, Manuela Favarin; Zaccara, Ivana Maria; Só, Marcus Vinicius Reis; Kopper, Patrícia Maria Poli

    2016-06-14

    This study aimed to compare apical transportation, centering ratio, and working time during root canal preparation with Wizard Navigator (WN), WaveOne (WO), or ProTaper Universal (PT) and to describe deformation and fracture of these instruments. Thirty-six mesiobuccal roots from maxillary molars were micro-computed tomography (micro-CT) scanned and then sorted into three groups (n = 12): Wizard Navigator (WN), WaveOne (WO), and ProTaper Universal (PT). The root canals were prepared using WN, WO, or PT; the time of each canal preparation was timed; and the specimens were micro-CT re-scanned. The instruments were submitted to scanning electron microscopy (SEM) before and after their use. The data on canal transportation at 1, 2, 3, 4 and 5 mm and preparation time were analyzed by the Kruskal-Wallis test, followed by the Mann-Whitney U test. The centering ratio was analyzed by ANOVA, followed by Tukey's test. Both instrument deformation and fracture were described. Apical transportation was similar among groups at 1, 2, 3 and 4 mm. The WO group showed higher canal transportation at 5mm than the other groups (p = 0.03). There was no significant difference in centering ratio among the groups. Preparation time in the WO group was significantly lower than in the other groups (p = 0.004). Small differences were observed in the surface area of all instruments. The WN, WO, and PT groups had a similar centering ratio without procedural errors or significant structural changes. At 5 mm from the apex, the WO group showed the largest canal transportation toward the furcation and root canal preparation was faster than in the WN and PT groups. PMID:27305517

  13. Optimizing Indicator Choosing for Canal Control System and Simulation Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One Key problem for canal system control is how to select appropriate performance indicators and how to tune the controller with these indicators. A canal system is a multi-input and multi-output (MIMO) system. The judging of control performance can be extremely complicated. In this paper, frequentl...

  14. Comparison of two endodontic handpieces during the preparation of simulated root canals.

    PubMed

    Smith, R B; Edmunds, D H

    1997-11-01

    The objective of this in vitro study was to compare and assess two endodontic handpieces during the preparation of simulated root canals. One hundred and sixty simulated root canals in clear resin blocks, of two angles and positions of curvature, were prepared using either Shaper files activated by the MM1500 Sonic Air handpiece (Micro-Mega, Besançon, France) or Excalibur files activated by the W & H Excalibur 969 handpiece (W & H, Bürmoos, Austria). Files of 21-mm or 25-mm length were used. When preparing the canals, the files were used either in line with or perpendicular to the canal curvature. Preparation of the canals was carried out using a technique described in the manufacturers' literature. A variety of parameters were used to compare the handpieces, including an assessment of the canal preparation time, the deformation or fracture of instruments, loss of canal length, weight loss from the resin blocks and the overall postpreparation canal shape. Both handpieces provided an efficient and easy method of preparing and shaping the root canal with little operator fatigue. The MM1500 Sonic Air handpiece took significantly more time (P < 0.001) to prepare the canals and was associated with both more loss of working length (P < 0.05) and more loss of weight (P < 0.001). Both handpieces created a high percentage of aberrations in the shapes of prepared canals. The MM1500 Sonic Air handpiece created significantly more aberrations than the Excalibur handpiece (P < 0.05 for zip and elbow, P < 0.05 for danger zone and coronal narrow). The effects of the variables, canal curvature, file length and the plane of use of the file, on the performance of the handpieces, were also assessed. PMID:9588976

  15. A comparison of stainless steel Flexofiles and nickel-titanium NiTiFlex files during the shaping of simulated canals.

    PubMed

    Bishop, K; Dummer, P M

    1997-01-01

    The aim of this study was to compare the shaping ability of stainless steel Flexofiles and nickel-titanium NiTiFlex files during the preparation of simulated canals in resin blocks. A total of 80 canals with various angles and position of curvature were prepared by one operator using either Flexofiles or NiTiFlex files in a modified double-flared technique with balanced force method of instrument manipulation. Canal shape was assessed at two stages during the procedure, after apical enlargement to size 30 and subsequently at size 45. Pre- and post-operative images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount of material removed as a result of preparation were determined from composite images of superimposed pre- and post-operative views. Canal preparation using NiTiFlex files was significantly quicker (P < 0.0001) up to size 30. More instrument failures occurred with Flexofiles (12) compared to NiTiFlex files (7) but there were no statistically significant differences between file type, instrument size or canal shape. Flexofiles created significantly more zips, perforations and ledges; there were no differences in terms of danger zones. Overall, canals prepared with Flexofiles were significantly wider because more material was removed from the outer aspect of the curve at the end-point of preparation and from the inner aspect of the curve at the apex. Under the conditions of this study, preparation with NiTiFlex files was more effective and produced more appropriate canal shapes than Flexofiles. PMID:9477791

  16. Efficacy of laser-based irrigant activation methods in removing debris from simulated root canal irregularities.

    PubMed

    Deleu, Ellen; Meire, Maarten A; De Moor, Roeland J G

    2015-02-01

    In root canal therapy, irrigating solutions are essential to assist in debridement and disinfection, but their spread and action is often restricted by canal anatomy. Hence, activation of irrigants is suggested to improve their distribution in the canal system, increasing irrigation effectiveness. Activation can be done with lasers, termed laser-activated irrigation (LAI). The purpose of this in vitro study was to compare the efficacy of different irrigant activation methods in removing debris from simulated root canal irregularities. Twenty-five straight human canine roots were embedded in resin, split, and their canals prepared to a standardized shape. A groove was cut in the wall of each canal and filled with dentin debris. Canals were filled with sodium hypochlorite and six irrigant activation procedures were tested: conventional needle irrigation (CI), manual-dynamic irrigation with a tapered gutta percha cone (manual-dynamic irrigation (MDI)), passive ultrasonic irrigation, LAI with 2,940-nm erbium-doped yttrium aluminum garnet (Er:YAG) laser with a plain fiber tip inside the canal (Er-flat), LAI with Er:YAG laser with a conical tip held at the canal entrance (Er-PIPS), and LAI with a 980-nm diode laser moving the fiber inside the canal (diode). The amount of remaining debris in the groove was scored and compared among the groups using non-parametric tests. Conventional irrigation removed significantly less debris than all other groups. The Er:YAG with plain fiber tip was more efficient than MDI, CI, diode, and Er:YAG laser with PIPS tip in removing debris from simulated root canal irregularities. PMID:24091791

  17. Simulating Radiation Transport in Curved Spacetimes

    NASA Astrophysics Data System (ADS)

    Endeve, Eirik; Hauck, Cory; Xing, Yulong; Cardall, Christian; Mezzacappa, Anthony

    2014-03-01

    We are developing methods for simulation of radiation transport in systems governed by strong gravity (e.g., neutrino transport in core-collapse supernovae). By employing conservative formulations of the general relativistic Boltzmann equation, we aim to develop methods that are (i) high-order accurate for computational efficiency; (ii) robust in the sense that the phase space density f preserves the maximum principle of the physical model (f ∈ [ 0 , 1 ] for fermions); and (iii) applicable to curvilinear coordinate systems to accommodate curved spacetimes, which result in gravity-induced frequency shift and angular aberration. Our approach is based on the Runge-Kutta discontinuous Galerkin method, which has many attractive properties, including high-order accuracy on a compact stencil. We present the physical model, describe our numerical methods, and show results from implementations in spherical and axial symmetry. Our tests show that the method is high-order accurate and strictly preserves the maximum principle on f. We also demonstrate the ability of our method to accurately include effects of a strong gravitational field.

  18. A novel image processing and measurement system applied to quantitative analysis of simulated tooth root canal shape

    NASA Astrophysics Data System (ADS)

    Yong, Tao; Yong, Wei; Jin, Guofan; Gao, Xuejun

    2005-02-01

    Dental pulp is located in root canal of tooth. To modern root canal therapy, "Root canal preparation" is the main means to debride dental pulp infection. The shape of root canal will be changed after preparation, so, when assessing the preparation instruments and techniques, the root canal shaping ability especially the apical offset is very important factor. In this paper, a novel digital image processing and measurement system is designed and applied to quantitative analysis of simulated canal shape. By image pretreatment, feature extraction, registration and fusion, the variation of the root canals' characteristics (before and after preparation) can be accurately compared and measured, so as to assess the shaping ability of instruments. When the scanning resolution is 1200dpi or higher, the registration and measurement precision of the system can achieve 0.021mm or higher. The performance of the system is tested by a series of simulated root canals and stainless steel K-files.

  19. Accuracy of acoustic ear canal impedances: finite element simulation of measurement methods using a coupling tube.

    PubMed

    Schmidt, Sebastian; Hudde, Herbert

    2009-06-01

    Acoustic impedances measured at the entrance of the ear canal provide information on both the ear canal geometry and the terminating impedance at the eardrum, in principle. However, practical experience reveals that measured results in the audio frequency range up to 20 kHz are frequently not very accurate. Measurement methods successfully tested in artificial tubes with varying area functions often fail when applied to real ear canals. The origin of these errors is investigated in this paper. To avoid mixing of systematical and other errors, no real measurements are performed. Instead finite element simulations focusing on the coupling between a connecting tube and the ear canal are regarded without simulating a particular measuring method in detail. It turns out that realistic coupling between the connecting tube and the ear canal causes characteristic shifts of the frequencies of measured pressure minima and maxima. The errors in minima mainly depend on the extent of the area discontinuity arising at the interface; the errors in maxima are determined by the alignment of the tube with respect to the ear canal. In summary, impedance measurements using coupling tubes appear questionable beyond 3 kHz. PMID:19507964

  20. In Vitro Evaluation of Apical Sealing Ability of HEROfill® Obturator Versus Cold Lateral Condensation in Curved Root Canals

    PubMed Central

    Zarei, Mina; Javidi, Maryam; Kazemi, Zeinab

    2015-01-01

    Objectives: This study aimed to assess and compare the apical sealing ability of HEROfill® Soft-Core system and lateral condensation technique in fine curved canals using the fluid filtration method. Materials and Methods: Forty human mesiobuccal root canals of mandibular first molars with 25° to 40° curvatures were instrumented to an apical size 30/0.04. Roots were randomly assigned to two experimental groups of 15, designated as groups A and B. Two control groups, each containing five teeth, served as positive and negative controls. Group A was obturated using lateral condensation technique and group B with the HEROfill® Soft-Core system. The groups were tested for microleakage using an in vitro fluid filtration apparatus with 0.5 atm pressure at zero, two, four, six, eight and 10 minutes. Independent t-test was used to analyze the microleakage data. Results: The mean and standard deviation (SD) values for fluid microleakage in the lateral condensation group were 0.58±0.49 μL/min, 0.68±0.35 μL/min, 0.74±0.22 μL/min, 0.71±0.29 μL/min and 0.60± 0.29 μL/min at two, four, six, eight and 10 minutes, respectively. The mean and SD values for fluid microleakage in the HEROfill® group were 0.53±0.42 μL/min, 0.67±0.34 μL/min, 0.69±0.26 μL/min, 0.73±0.33 μL/min and 0.63±0.26 μL/min at two, four, six, eight and 10 minutes, respectively. The difference between the lateral condensation and HEROfill® groups was not statistically significant at two (P=0.776), four (P=0.909), six (P=0.562), eight (P=0.861) or 10 (P=0.765) minutes. Conclusion: The HEROfill® system and cold lateral condensation technique were equally effective for apical sealing of curved canals. PMID:27123020

  1. 3D Analysis of D-RaCe and Self-Adjusting File in Removing Filling Materials from Curved Root Canals Instrumented and Filled with Different Techniques

    PubMed Central

    Simsek, Neslihan; Ahmetoglu, Fuat; Bulut, Elcin Tekin; Er, Kursat

    2014-01-01

    The aim of this study was to compare the efficacy of D-RaCe files and a self-adjusting file (SAF) system in removing filling material from curved root canals instrumented and filled with different techniques by using microcomputed tomography (micro-CT). The mesial roots of 20 extracted mandibular first molars were used. Root canals (mesiobuccal and mesiolingual) were instrumented with SAF or Revo-S. The canals were then filled with gutta-percha and AH Plus sealer using cold lateral compaction or thermoplasticized injectable techniques. The root fillings were first removed with D-RaCe (Step 1), followed by Step 2, in which a SAF system was used to remove the residual fillings in all groups. Micro-CT scans were used to measure the volume of residual filling after root canal filling, reinstrumentation with D-RaCe (Step 1), and reinstrumentation with SAF (Step 2). Data were analyzed using Wilcoxon and Kruskal-Wallis tests. There were no statistically significant differences between filling techniques in the canals instrumented with SAF (P = 0.292) and Revo-S (P = 0.306). The amount of remaining filling material was similar in all groups (P = 0.363); all of the instrumentation techniques left filling residue inside the canals. However, the additional use of SAF was more effective than using D-RaCe alone. PMID:25114976

  2. Simulated Equating Using Several Item Response Curves.

    ERIC Educational Resources Information Center

    Boldt, R. F.

    The comparison of item response theory models for the Test of English as a Foreign Language (TOEFL) was extended to an equating context as simulation trials were used to "equate the test to itself." Equating sample data were generated from administration of identical item sets. Equatings that used procedures based on each model (simple item…

  3. Simulation and video animation of canal flushing created by a tide gate

    USGS Publications Warehouse

    Schoellhamer, David H.

    1988-01-01

    A tide-gate algorithm was added to a one-dimensional unsteady flow model that was calibrated, verified, and used to determine the locations of as many as five tide gates that would maximize flushing in two canal systems. Results from the flow model were used to run a branched Lagrangian transport model to simulate the flushing of a conservative constituent from the canal systems both with and without tide gates. A tide gate produces a part-time riverine flow through the canal system that improves flushing along the flow path created by the tide gate. Flushing with no tide gates and with a single optimally located tide gate are shown with a video animation.

  4. Filling of simulated lateral canals with gutta-percha or thermoplastic polymer by warm vertical compaction.

    PubMed

    Sant'Anna-Junior, Arnaldo; Guerreiro-Tanomaru, Juliane Maria; Martelo, Roberta Bosso; Silva, Guilherme Ferreira da; Tanomaru Filho, Mário

    2015-01-01

    The aim of this study was to evaluate the ability of gutta-percha and a thermoplastic synthetic polymer (Resilon) to fill simulated lateral canals, using warm vertical compaction. Forty-five single-rooted human teeth were prepared using the rotary crown-down technique. Artificial lateral canals were made at 2, 5, and 8 mm from the working length (WL) in each root. The specimens were divided into three groups (n = 15), according to the filling material: Dentsply gutta-percha (GD), Odous gutta-percha (GO), and Resilon cones (RE). The root canals were obturated using warm vertical compaction, without endodontic sealer. The specimens were subjected to a tooth decalcification and clearing procedure. Filling of the lateral canals was analyzed by digital radiography and digital photographs, using the Image Tool software. The data were subjected to the Kruskal-Wallis and Dunn tests at 5% significance. RE had the best filling ability in all root thirds (p < 0.05), with similar results for GO in the coronal third. In the middle and apical thirds, GD and GO had similar results (p > 0.05). Resilon may be used as an alternative to gutta-percha as a solid core filling material for use with the warm vertical compaction technique. The study findings point to the potential benefit of the warm vertical compaction technique for filling lateral canals, and the study provides further information about using Resilon and gutta-percha as materials for the warm vertical compaction technique. PMID:25885024

  5. A comparison of curved canal instrumentation using nickel-titanium or stainless steel files with the balanced-force technique.

    PubMed

    Harlan, A L; Nicholls, J I; Steiner, J C

    1996-08-01

    The Flex-R file was compared with the Onyx nickel-titanium file in respect to canal center movement and final canal area after balanced-force instrumentation. Forty-two root canals in extracted human molars were divided into two equal groups of 21, in all of which the angle of curvature ranged from 20 to 40 degrees. After mounting in a mold, each root was sectioned at two locations, providing an apical and a coronal section. Pre- and postinstrumentational 35-mm photographic slides of each section were superimposed, projected, traced, and then scanned into a computer. From these computerized pre- and postinstrumentation images, the movement of the canal center and the area of each canal were computed at both the apical and coronal sections. Results showed no significant difference in canal center movement or postinstrumentation area when Flex-R or Onyx files were used at the apical section. Coronally, the Flex-R files demonstrated more movement of the canal center. No significant correlation was found between the angle of root curvature and canal movement or the angle of root curvature and postinstrumentation canal area. PMID:8941749

  6. A comparison of Flex-R files and K-type files for enlargement of severely curved molar root canals.

    PubMed

    Sepic, A O; Pantera, E A; Neaverth, E J; Anderson, R W

    1989-06-01

    A double exposure radiographic technique is introduced and used to evaluate the magnitude of apical canal transportation that occurs during preparation procedures. The balanced force technique and a step-back method for cleaning and shaping root canals were evaluated in mesiobuccal root canals from 80 extracted human molar teeth with curvatures ranging from 30 to 73 degrees. Pre- and posttreatment file positions were examined from clinical and proximal radiographic views by computer digitization. Statistical analysis indicated significantly less apical transportation with the use of the balanced force technique when compared with a step-back technique in canals exhibiting both more and less than 45 degrees of curvature. PMID:2592877

  7. Apical Extrusion of Debris after Canal Preparation with Hand-Files Used Manually or Installed on Reciprocating Air-Driven Handpiece in Straight and Curved Canals

    PubMed Central

    Labbaf, Hossein; Shakeri, Leila; Orduie, Reza; Bastami, Farshid

    2015-01-01

    Introduction: Apical debris extrusion (DE) subsequent to root canal instrumentation, is one of the most important causes of endodontic flare-ups. The aim of this study was to compare the amount of DE after root canal instrumentation using nickel-titanium (NiTi) hand files with step-back manual technique or installed on reciprocating handpiece. Methods and Materials: This study was conducted on mesiobuccal (MB) roots of extracted maxillary first molars (n=20) and roots of mandibular premolars (n=20) that were randomly divided into two groups (n=20) according to the armamentarium used for canal preparation (air-driven reciprocating handpiece or hand instrumentation). In each group, the MB and premolar roots were prepared with the main apical sizes of 35 and 40, respectively. The extruded debris were collected and weighed. Finally, the mean dry weights were compared using ANOVA and t-test, and Tukey’s Multiple Comparisons Procedures were used to determine the significant differences in amounts of DE. The level of significance was set at 0.05. Results: Regardless of the type of teeth, the mean values of DE, were significantly lower in the handpiece group (P<0.0001). In addition, significantly lower amounts of DE was observed in premolars in similar group (P<0.001). However, this difference was not significant in MB roots of molars (P=0.20). Conclusion: Root canal preparation with reciprocating handpiece can lead to significantly lower debris extrusion than the manual step-back technique. In handpiece-prepared canals, the amount of extruded debris was significantly lower in premolar teeth. PMID:26213538

  8. Simulations of curved turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Orlandi, Paolo

    1991-01-01

    The objective of this work is to develop a space-time accurate numerical method for the solution of incompressible Navier-Stokes equations in generalized coordinates. The resulting code is to be used for direct and large-eddy simulation of turbulence in complex geometries. In a previous paper, the system of Navier-Stokes equations in general curvilinear coordinates was solved by a second-order accurate finite-difference scheme. Satisfactory results were obtained for several flows in two and three dimensions. The system of Navier-Stokes for the fluxes are given in Orlandi (1989). The main deficiency of the numerical scheme was the large CPU time required for the solution of the Poisson equation for the 'pressure' field. The point SOR relaxation, in conjunction with a multigrid scheme, was used for the Poisson equation. In some cases, particularly with very fine grids, it was impossible to obtain a divergent-free flow. A preliminary attempt is made to compute the spatially evolving flow of Swearingen & Blackwelder. To reduce the streamwise distance, the inflow was at a distance x = 60 cm from the leading edge.

  9. [Deformations occurring in the apical third of curved root canals during biomechanical preparation using manual impulsion-traction techniques].

    PubMed

    Roig Cayón, M; Basilio Monné, J; Canalda Sahli, C

    1990-01-01

    Apical deformations, specially zips and elbows, during instrumentation of the root canals, are studied. The authors study why do they appear, their effect on endodontic therapy, and the way of avoiding them. PMID:1964069

  10. Visualization of removal of trapped air from the apical region in simulated root canals by laser-activated irrigation using an Er,Cr:YSGG laser.

    PubMed

    Peeters, Harry Huiz; De Moor, Roeland J G; Suharto, Djoko

    2015-08-01

    The aim of this visualization study was to obtain a better understanding of the mechanism by which trapped air is removed from the apical region of simulated root canals by activation of an irrigant using an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser during endodontic procedures. A high-speed imaging system with high temporal and spatial resolution was used to visualize laser-induced shock waves in a resin block model with a curved root canal (inner diameter at the apex 0.08 mm, taper 4 %, crown height 10 mm, overall length 40 mm) and a glass cylinder model with a straight root canal (inner diameter 1 mm, crown height 10 mm, overall length 40 mm). The study utilized MZ3 and RFT3 tips in each model, without water or air spray, and with an average power of 1 W at 35 Hz. Laser-activated irrigation overcame the airlock effect by releasing air trapped in the air column. The mechanism underlying the removal of trapped air from the apical region using an Er,Cr:YSGG laser in a dry root canal is via the disruption of the surface tension at the solution-air interface. This disruption, caused by bubble implosion (cavitation), displaces air in the form of bubbles from the apical region toward the solution, which allows the solution to travel apically. PMID:25159897

  11. Simulating the value of El Niño forecasts for the Panama Canal

    NASA Astrophysics Data System (ADS)

    Graham, Nicholas E.; Georgakakos, Konstantine P.; Vargas, Carlos; Echevers, Modesto

    2006-11-01

    The Panama Canal relies on rain-fed streamflow into Gatun Lake, the canal's primary storage facility, for operations—principally ship passage and hydropower generation. Precipitation in much of Panama has a strong negative relationship with eastern tropical Pacific sea surface temperature (SST) and this relationship is reflected in Gatun Lake inflows. For example, the correlation coefficient between wet season (July-December) inflow and NINO3 SST is -0.53 over the period 1914-1997. Operational capabilities to predict tropical Pacific SSTs have been demonstrated by several forecast systems during the past decade, and (as we show) such SST forecasts can be used to reduce the uncertainty of estimates of future inflows (compared with climatological expectations). Because substantial reductions in lake inflow negatively impact canal operations, we wondered whether these forecasts of future inflows, coupled with a method for translating that information into effective operational policy, might result in more efficient canal management. A combined simulation/optimization/assessment "virtual" canal system was implemented and exercised using operational El Niño forecasts over the period 1981-1998. The results show the following main points: At current demand levels, the canal system is relatively robust (insensitive to flow forecasts) unless flows are substantially reduced (i.e., during El Niño episodes) or forecasts are extremely accurate. The inclusion of accurately specified levels of forecast uncertainty is critical in developing economically beneficial policies. The situations in which imperfect forecast information can be useful lie between those where storage and future inflows are relatively high, and those where storage and inflows are relatively low. In the former case, demands can be met without the benefit of forecast information, and in the latter case even perfect forecast information cannot prevent operational curtailments. For a nominally configured

  12. Simulation of the effects of proposed tide gates on circulation, flushing, and water quality in residential canals, Cape Coral Florida

    USGS Publications Warehouse

    Goodwin, Carl R.

    1991-01-01

    Decades of dredging and filling of Florida's low-lying coastal wetlands have produced thousands of miles of residential tidal canals and adjacent waterfront property. Typically, these canals are poorly flushed, and over time, accumulated organic-rich bottom materials, contribute to an increasingly severe degraded water quality. One-dimensional hydrodynamic and constituent-transport models were applied to two dead-end canal systems to determine the effects of canal system interconnection using tide gates on water circulation and constituent flushing. The model simulates existing and possible future circulation and flushing conditions in about 29 miles of the approximately 130 miles of tidally influenced canals in Cape Coral, located on the central west coast of peninsular Florida. Model results indicate that tidal water-level differences between the two canal systems can be converted to kinetic energy, in the form of increased water circulation, but the use of one-way tide gate interconnections. Computations show that construction of from one to four tide gates will cause replacement of a volume of water equivalent to the total volume of canals in both systems in 15 to 9 days, respectively. Because some canals flush faster than others, 47 and 21 percent of the original canal water will remain in both systems 50 days after start of operation of one and four tide gates, respectively. Some of the effects that such increased flushing are expected to have include reduced density stratification and associated dissolved-oxygen depletion in canal bottom waters, increased localized reaeration, and more efficient discharge of stormwater runoff entering the canals.

  13. Bacterial penetration of the root canal of intact incisor teeth after a simulated traumatic injury.

    PubMed

    Love, R M

    1996-12-01

    One of the aims in treating traumatised teeth is to maintain the vitality of the pulp or allow conditions favourable for pulp revascularisation. However, infection of the pulp and root canal system may prevent this. A number of pathways have been proposed that allow bacteria to invade the root canal system, however most of these pathways cannot account for pulp infection in teeth that did not sustain injury to the periodontal attachment. Enamel/dentine cracks have been proposed as a portal for bacterial invasion of seemingly intact teeth and the aim of this study was to determine if bacteria could invade the root canal system after a simulated traumatic episode. Twenty intact and sound upper central incisors were chosen and prepared. One tooth was selected as a sterility control and the external crown surface of the remaining 19 teeth was subjected to infection with Streptococcus gordonii in a bacterial microleakage model. Over 7 days samples of growth media from the root canal system were taken and tested for bacteria. Sixteen of the teeth did not demonstrate bacterial invasion over the time frame. These teeth were then prepared for testing in a pendulum impact device and were subjected to a blow which did not fracture the crowns or dislodge the tooth from its simulated alveolus. The teeth were then prepared and tested in the bacterial microleakage model. After impact seven of the teeth demonstrated bacterial invasion of the root canal system (P = 0.002). These teeth were then reprepared for testing in the bacterial microleakage model. The crowns of five teeth, selected at random, were coated with two layers of light cured unfilled resin, the remaining two were used as positive controls. All the teeth coated with resin did not demonstrate bacterial invasion (P = 0.00), while the positive controls demonstrated invasion. The results suggested that enamel/dentine infractions were pathways for bacterial invasion of the root canal system of traumatised teeth. The

  14. The application of new method and system to analyze of simulated tooth root canal shaping ability in stomatology

    NASA Astrophysics Data System (ADS)

    Yong, Tao; Yong, Wei; Jin, Guofan; Gao, Xuejun

    2005-01-01

    The study of shaping ability is very important in assessment of instruments and preparation techniques. Using simulated canals in these studies have many advantages such as good standardization, good comparability, transparent et al. A new computer assistant measure system particularly designed for quantitative analysis of the shape of simulated canals is set up and described in this paper. This system can be used in automatic assessment of shaping ability of instruments, by image pretreatment, feature extraction, registration, fusion, and measurement. Comparing the simulated root canal shape before and after instrument in the fused image is good to reduce the errors from vision and enhance the repetition of results. The registration and measurement precision of the system can achieve 0.021mm or higher, when the resolution of original root canal image is 1200 DPI or higher. The shaping ability of stainless steel K-files is evaluated by the system.

  15. Effectiveness of Four Different Final Irrigation Activation Techniques on Smear Layer Removal in Curved Root Canals : A Scanning Electron Microscopy Study

    PubMed Central

    Ahuja, Puneet; Nandini, Suresh; Ballal, Suma; Velmurugan, Natanasabapathy

    2014-01-01

    Objective: The aim of this study was to assess the efficacy of apical negative pressure (ANP), manual dynamic agitation (MDA), passive ultrasonic irrigation (PUI) and needle irrigation (NI) as final irrigation activation techniques for smear layer removal in curved root canals. Materials and Methods: Mesiobuccal root canals of 80 freshly extracted maxillary first molars with curvatures ranging between 25° and 35° were used. A glide path with #08–15 K files was established before cleaning and shaping with Mtwo rotary instruments (VDW, Munich, Germany) up to size 35/0.04 taper. During instrumentation, 1 ml of 2.5% NaOCl was used at each change of file. Samples were divided into 4 equal groups (n=20) according to the final irrigation activation technique: group 1, apical negative pressure (ANP) (EndoVac); group 2, manual dynamic agitation (MDA); group 3, passive ultrasonic irrigation (PUI); and group 4, needle irrigation (NI). Root canals were split longitudinally and subjected to scanning electron microscopy. The presence of smear layer at coronal, middle and apical levels was evaluated by superimposing 300-μm square grid over the obtained photomicrographs using a four-score scale with X1,000 magnification. Results: Amongst all the groups tested, ANP showed the overall best smear layer removal efficacy (p < 0.05). Removal of smear layer was least effective with the NI technique. Conclusion: ANP (EndoVac system) can be used as the final irrigation activation technique for effective smear layer removal in curved root canals. PMID:24910670

  16. Histological evaluation of the cleaning effectiveness of two reciprocating single-file systems in severely curved root canals: Reciproc versus WaveOne

    PubMed Central

    Carvalho, Maira de Souza; Junior, Emílio Carlos Sponchiado; Bitencourt Garrido, Angela Delfina; Roberti Garcia, Lucas da Fonseca; Franco Marques, André Augusto

    2015-01-01

    Objective: The aim of this study was to evaluate the cleaning effectiveness achieved with two reciprocating single-file systems in severely curved root canals: Reciproc and WaveOne. Materials and Methods: Twenty-five mesial roots of mandibular molars were randomly separated into two groups, according to the instrumentation system used. The negative control group consisted of five specimens that were not instrumented. The mesial canals (buccal and lingual) in Reciproc Group were instrumented with file R25 and the WaveOne group with the Primary file. The samples were submitted to histological processing and analyzed under a digital microscope. Results: The WaveOne group presented a larger amount of debris than the Reciproc Group, however, without statistically significant difference (P > 0.05). A larger amount of debris in the control group was observed, with statistically significant difference to Reciproc and WaveOne groups (P < 0.05). Conclusions: The two reciprocating single-file instrumentation systems presented similar effectiveness for root canal cleaning. PMID:25713489

  17. Curve squealing of trains: Measurement, modelling and simulation

    NASA Astrophysics Data System (ADS)

    Glocker, Ch.; Cataldi-Spinola, E.; Leine, R. I.

    2009-07-01

    Curve squealing of railway wheels occurs erratically in narrow curves with a frequency of about 4 kHz. Squealing is caused by a self-excited stick-slip oscillation in the wheel-rail contact. The mechanism which activates squeal is still unexplained and will be analyzed in the paper at hand. The squeal model consists of the first modal forms of an elastic wheel and is equipped with a three-dimensional hard Coulomb contact. Based on this model, a linear stability analysis of the stationary run through a curve is performed for the four wheels of the investigated bogie. The results show that in particular the front inner wheel tends to squeal. A numerical simulation of the system's differential inclusions performed on the unstable states shows the existence of a self-excited stick-slip oscillation. The computed frequency of the limit cycle agrees well with the measurements. The design of the squeal model, the steps necessary to perform the stability analysis on systems with non-ideal constraints, as well as the non-smooth dynamics code used to perform the simulations are explained in detail.

  18. Scanning Electron Microscopic Evaluation of Residual Smear Layer Following Preparation of Curved Root Canals Using Hand Instrumentation or Two Engine-Driven Systems

    PubMed Central

    Khademi, Abbasali; Saatchi, Masoud; Shokouhi, Mohammad Mehdi; Baghaei, Badri

    2015-01-01

    Introduction: In this experimental study, the amount of smear layer (SL) remnants in curved root canals after chemomechanical instrumentation with two engine-driven systems or hand instrumentation was evaluated. Methods and Materials: Forty-eight mesiobuccal roots of mandibular first molars with curvatures ranging between 25 and 35 degrees (according to Schneider’s method) were divided into three groups (n=16) which were prepared by either the ProTaper Universal file series, Reciproc single file system or hand instrumentation. The canals were intermittently irrigated with 5.25% NaOCl and 17% (ethylenediaminetetraacetic acid) EDTA, followed by distilled water as the final rinse. The roots were split longitudinally and the apical third of the specimens were evaluated under 2500× magnification with a scanning electron microscope (SEM). The mean scores of the SL were calculated and analyzed using the non-parametric Kruskal-Wallis and Mann-Whitney U tests. Results: The mean scores of the SL were 2.00±0.73, 1.94±0.68 and 1.44±0.63 µm for the ProTaper Universal, Reciproc and hand instrumentation, respectively. Mean score of SL was significantly less in the hand instrumentation group than the ProTaper (P=0.027) and Reciproc (P=0.035) groups. The difference between the two engine-driven systems, however, was not significant (P=0.803). Conclusion: The amount of smear layer in the apical third of curved root canals prepared with both engine-driven systems was similar and greater than the hand instrumentation technique. Complete cleanliness was not attained. PMID:26523137

  19. SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES

    SciTech Connect

    Findeisen, Krzysztof; Hillenbrand, Lynne; Cody, Ann Marie

    2015-01-10

    Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs.

  20. Simulations of elastic, stretchable, shearable curves interacting with a liquid

    NASA Astrophysics Data System (ADS)

    Gazzola, Mattia; McCormick, Andrew; Mahadevan, L.

    2015-11-01

    We present a general numerical approach for the simulations of soft filaments deforming in three-dimensional space. Unlike the vast literature on inextensible and unshearable rods, we enable all possible deformation modes at every cross-section consistent with the full Euclidean group SE(3), namely, bending, twisting, shear and stretch. Additionally, we also allow elastic curves to interact with the environment via muscular activity, self-contact, surface friction and hydrodynamics. We demonstrate the capabilities of our approach on a range of biophysical problems, with an emphasis on limbless locomotion on dry surfaces, thin liquid films and in bulk liquids.

  1. Positional glow curve simulation for thermoluminescent detector (TLD) system design

    NASA Astrophysics Data System (ADS)

    Branch, C. J.; Kearfott, K. J.

    1999-02-01

    Multi- and thin element dosimeters, variable heating rate schemes, and glow-curve analysis have been employed to improve environmental and personnel dosimetry using thermoluminescent detectors (TLDs). Detailed analysis of the effects of errors and optimization of techniques would be highly desirable. However, an understanding of the relationship between TL light production, light attenuation, and precise heating schemes is made difficult because of experimental challenges involved in measuring positional TL light production and temperature variations as a function of time. This work reports the development of a general-purpose computer code, thermoluminescent detector simulator, TLD-SIM, to simulate the heating of any TLD type using a variety of conventional and experimental heating methods including pulsed focused or unfocused lasers with Gaussian or uniform cross sections, planchet, hot gas, hot finger, optical, infrared, or electrical heating. TLD-SIM has been used to study the impact on the TL light production of varying the input parameters which include: detector composition, heat capacity, heat conductivity, physical size, and density; trapped electron density, the frequency factor of oscillation of electrons in the traps, and trap-conduction band potential energy difference; heating scheme source terms and heat transfer boundary conditions; and TL light scatter and attenuation coefficients. Temperature profiles and glow curves as a function of position time, as well as the corresponding temporally and/or spatially integrated glow values, may be plotted while varying any of the input parameters. Examples illustrating TLD system functions, including glow curve variability, will be presented. The flexible capabilities of TLD-SIM promises to enable improved TLD system design.

  2. The Reamer/Irrigator/Aspirator Reduces Femoral Canal Pressure in Simulated TKA

    PubMed Central

    Van Gorp, Cornel C.; Falk, James V.; Kmiec, Stanley J.

    2008-01-01

    Inserting the femoral intramedullary alignment rod during total knee arthroplasty (TKA) can generate high intramedullary pressure, which increases the risk of intraoperative complications caused by fat embolism. Despite modifications to the surgical procedure, the best method to prevent this increase in pressure remains unknown. The reamer/irrigator/aspirator is a surgical instrument designed for use during femoral canal entry to increase the canal size and remove intramedullary fat and may prevent this pressure increase. We posed two hypotheses: (1) using the reamer/irrigator/aspirator system will result in lower maximum femoral intramedullary pressure than using only conventional instrumentation during the initial steps of a TKA; and (2) using the reamer/irrigator/aspirator system in the initial steps of TKA will result in a mean maximum intramedullary pressure less than 200 mm Hg. We simulated a TKA on 14 cadaveric femurs to compare the femoral intramedullary pressure using both methods. Considerable decreases in femoral intramedullary pressure of 86% proximally and 87% distally were obtained by using the reamer/irrigator/aspirator system. The mean maximum pressure using the reamer/irrigator/aspirator system was less than 200 mm Hg. Additional clinical studies are needed to confirm any reduction in complications using the reamer/irrigator/aspirator system. PMID:18425558

  3. Irrigation Management, Evolving Canal Systems and Social Simulation in Hohokam Society, Central Arizona

    NASA Astrophysics Data System (ADS)

    Ertsen, Maurits; Murphy, John; Purdue, Louise

    2015-04-01

    As may societies that rely on irrigation, the Hohokam civilization in South West Arizona faced challenges arising from the variability and unpredictability of water supply and the physics underlying the flow of water through open channels. Such challenges can be overcome through cooperation and other forms of structured social interactions and institutions ranging from simple to complex. These interactions are influenced by and are influenced themselves by environmental conditions, including hydrology, soils and vegetation. At the same time, the environmental record provides clues to these interactions. To better understand these past interactions we combine geoarchaeological studies with flow simulations and Agent Based Modeling. Fieldwork conducted on Hohokam irrigation revealed new details about canal morphology, including shape, size, elevation, slope, and cleaning events. Micromorphological study of the sediments in these structures allow finer resolution in discerning the performance (velocity, discharge, etc.) of the canal channels and their evolution through time. We couple this with basic agent-based modeling to explore how these constraints might have required alternative strategies for cooperation. The combination of both approaches is key to discerning both broad differences between periods and fine variation within major chronological periods. We show that the coupling of social and physical models on very fine time scales can offer insight into the social arrangements and day-to-day life of people in the prehistoric past and inform our understanding of those societies' long-term changes.

  4. Shaping ability of Reciproc and TF Adaptive systems in severely curved canals of rapid microCT-based prototyping molar replicas

    PubMed Central

    ORDINOLA-ZAPATA, Ronald; BRAMANTE, Clovis Monteiro; DUARTE, Marco Antonio Húngaro; CAVENAGO, Bruno Cavalini; JARAMILLO, David; VERSIANI, Marco Aurélio

    2014-01-01

    Objective: To evaluate the shaping ability of Reciproc and Twisted-File Adaptive systems in rapid prototyping replicas. Material and Methods: Two mandibular molars showing S-shaped and 62-degree curvatures in the mesial root were scanned by using a microcomputed tomography (μCT) system. The data were exported in the stereolitograhic format and 20 samples of each molar were printed at 16 µm resolution. The mesial canals of 10 replicas of each specimen were prepared with each system. Transportation was measured by overlapping radiographs taken before and after preparation and resin thickness after instrumentation was measured by μCT. Results: Both systems maintained the original shape of the apical third in both anatomies (P>0.05). Overall, considering the resin thickness in the 62-degree replicas, no statistical difference was found between the systems (P>0.05). In the S-shaped curvature replica, Reciproc significantly decreased the thickness of the resin walls in comparison with TF Adaptive. Conclusions: The evaluated systems were able to maintain the original shape at the apical third of severely curved mesial canals of molar replicas. PMID:24918662

  5. Influence of motion pattern on apical transportation and centering ability of WaveOne single-file technique in curved root canals

    PubMed Central

    Naseri, Mandana; Paymanpour, Payam; Kangarloo, Ali; Haddadpur, Sahar; Dianat, Omid; Ketabi, Mohammad Ali

    2016-01-01

    Background: The aim of this study was to evaluate apical transportation and centering ability of single-file instruments, WaveOne primary, with full rotation versus reciprocation movement using cone-beam computed tomography (CBCT) analysis in curved mesiobuccal (MB) root canal of human mandibular molars. Materials and Methods: Thirty MB canals of mandibular molars were randomly divided into two groups according to the instrument motion (n = 15): Group 1, reciprocation/WaveOne primary; Group 2, continuous rotation/WaveOne primary. After preparation, the amount of apical transportation and centering ability were assessed by evaluating pre- and post-instrumentation CBCT scans in three section (1, 3, and 5 mm from apical foramen). Statistical analysis of the data was performed using Mann-Whitney U-test and Friedman test (α = 0.05). Results: There was no statistically significant difference between two experimental groups in terms of apical transportation and centering ratio at 1, 3, and 5 mm from apical foramen (P > 0.05). Conclusion: Apical transportation and centering ability of WaveOne primary reciprocating instrument did not significantly differ between two motion patterns. PMID:26962310

  6. Alterations of the Danger Zone after Preparation of Curved Root Canals Using WaveOne with Reverse Rotation or Reciprocation Movements

    PubMed Central

    Shantiaee, Yazdan; Dianat, Omid; Paymanpour, Payam; Nahvi, Golnaz; Ketabi, Mohammad Ali; Kolahi Ahari, Golbarg

    2015-01-01

    Introduction: The aim of this study was to compare the changes that occur in the danger zone (DZ) after preparation of curved mesiobuccal (MB) canals of mandibular first molars with WaveOne instruments in two different movements [reciprocation (RCP) and counter-clockwise rotation (CCWR)] by means of cone-beam computed tomography (CBCT). Methods and Materials: MB canals of 30 mandibular molars were randomly divided into 2 groups (n=15); WaveOne/RCP and WaveOne/CCWR. Pre- and post-instrumentation CBCT images were assessed for changes in the dentin thickness in DZ (2 and 4 mm below the highest point of the root furcation) in both groups. Data was analyzed using the repeated measures ANOVA test. Results: There was no statistically significant difference between two experimental groups in terms of remaining dentin thickness at 2 and 4 mm levels below the highest point of the furcation (P>0.05). Conclusion: The efficacy of WaveOne instrument on changes of the dentin thickness in the DZ was not affected by different file movements. PMID:26213536

  7. Simulating cartilage conduction sound to estimate the sound pressure level in the external auditory canal

    NASA Astrophysics Data System (ADS)

    Shimokura, Ryota; Hosoi, Hiroshi; Nishimura, Tadashi; Iwakura, Takashi; Yamanaka, Toshiaki

    2015-01-01

    When the aural cartilage is made to vibrate it generates sound directly into the external auditory canal which can be clearly heard. Although the concept of cartilage conduction can be applied to various speech communication and music industrial devices (e.g. smartphones, music players and hearing aids), the conductive performance of such devices has not yet been defined because the calibration methods are different from those currently used for air and bone conduction. Thus, the aim of this study was to simulate the cartilage conduction sound (CCS) using a head and torso simulator (HATS) and a model of aural cartilage (polyurethane resin pipe) and compare the results with experimental ones. Using the HATS, we found the simulated CCS at frequencies above 2 kHz corresponded to the average measured CCS from seven subjects. Using a model of skull bone and aural cartilage, we found that the simulated CCS at frequencies lower than 1.5 kHz agreed with the measured CCS. Therefore, a combination of these two methods can be used to estimate the CCS with high accuracy.

  8. Mechanical Behavior of a NiTi Endodontic File During Insertion in an Anatomic Root Canal Using Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Legrand, V.; Moyne, S.; Pino, L.; Arbab Chirani, S.; Calloch, S.; Chevalier, V.; Arbab Chirani, R.

    2015-12-01

    Superelastic NiTi shape memory alloys (SMA) have biomedical applications including rotary endodontic files. These alloys are used thanks to their flexibility, which is due to solid-solid martensitic transformation. Unfortunately, the intracanal file separation can occur during canal preparation. To avoid this problem and to have a good idea of the mechanical behavior of these instruments, finite elements simulations taking into account the real shape of root canals are proposed in this study. This is possible by using a well-adapted model describing all the particularities of SMA and representative limit conditions. The behavior model has been validated in previous studies under complex loadings. It is implemented in ABAQUS® finite elements software. The anatomic shapes of root canals are extracted by microtomography using a real tooth. They are applied as limit conditions in realized simulations to be as near as possible to clinical conditions. The mechanical behavior of an endodontic file is then simulated during insertion in a root canal without and with rotation. This permits to obtain different information like the loading applied to the instrument during its use, the stress, and the phase transformation fields through the file. This is useful not only for clinical use but also for new NiTi endodontic instruments design.

  9. Direct numerical simulation of curved turbulent channel flow

    NASA Technical Reports Server (NTRS)

    Moser, R. D.; Moin, P.

    1984-01-01

    Low Reynolds number, mildly curved, turbulent channel flow has been simulated numerically without subgrid scale models. A new spectral numerical method developed for this problem was used, and the computations were performed with 2 million degrees of freedom. A variety of statistical and structural information has been extracted from the computed flow fields. These include mean velocity, turbulence stresses, velocity skewness, and flatness factors, space time correlations and spectra, all the terms in the Reynolds stress balance equations, and contour and vector plots of instantaneous velocity fields. The effects of curvature on this flow were determined by comparing the concave and convex sides of the channel. The observed effects are consistent with experimental observations for mild curvature. The most significant difference in the turbulence statistics between the concave and convex sides was in the Reynolds shear stress. This was accompanied by significant differences in the terms of the Reynolds shear stress balance equations. In addition, it was found that stationary Taylor-Gortler vortices were present and that they had a significant effect on the flow by contributing to the mean Reynolds shear stress, and by affecting the underlying turbulence.

  10. Numerical simulation of laminar flow in a curved duct

    SciTech Connect

    Lopez, A.R.; Oberkampf, W.L.

    1995-01-01

    This paper describes numerical simulations that were performed to study laminar flow through a square duct with a 900 bend. The purpose of this work was two fold. First, an improved understanding was desired of the flow physics involved in the generation of secondary vortical flows in three-dimensions. Second, adaptive gridding techniques for structured grids in three- dimensions were investigated for the purpose of determining their utility in low Reynolds number, incompressible flows. It was also of interest to validate the commercial computer code CFD-ACE. Velocity predictions for both non-adaptive and adaptive grids are compared with experimental data. Flow visualization was used to examine the characteristics of the flow though the curved duct in order to better understand the viscous flow physics of this problem. Generally, moderate agreement with the experimental data was found but shortcomings in the experiment were demonstrated. The adaptive grids did not produce the same level of accuracy as the non-adaptive grid with a factor of four more grid points.

  11. Simulator evaluation of manually flown curved instrument approaches. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Sager, D.

    1973-01-01

    Pilot performance in flying horizontally curved instrument approaches was analyzed by having nine test subjects fly curved approaches in a fixed-base simulator. Approaches were flown without an autopilot and without a flight director. Evaluations were based on deviation measurements made at a number of points along the curved approach path and on subject questionnaires. Results indicate that pilots can fly curved approaches, though less accurately than straight-in approaches; that a moderate wind does not effect curve flying performance; and that there is no performance difference between 60 deg. and 90 deg. turns. A tradeoff of curve path parameters and a paper analysis of wind compensation were also made.

  12. Photodynamic Inactivation of Root Canal Bacteria by Light Activation through Human Dental Hard and Simulated Surrounding Tissue

    PubMed Central

    Cieplik, Fabian; Pummer, Andreas; Leibl, Christoph; Regensburger, Johannes; Schmalz, Gottfried; Buchalla, Wolfgang; Hiller, Karl-Anton; Maisch, Tim

    2016-01-01

    Introduction: Photodynamic inactivation of bacteria (PIB) may be a supportive antimicrobial approach for use in endodontics, but sufficient activation of photosensitizers (PS) in root canals is a critical point. Therefore, aim of this study was to evaluate the ability of PS absorbing blue (TMPyP) or red light (Methylene Blue; MB) for light activation through human dental hard and simulated surrounding tissue to inactivate root canal bacteria. Methods: A tooth model was fabricated with a human premolar and two molars in an acrylic resin bloc simulating the optical properties of a porcine jaw. The distal root canal of the first molar was enlarged to insert a glass tube (external diameter 2 mm) containing PS and stationary-phase Enterococcus faecalis. Both PS (10 μM) were irradiated for 120 s with BlueV (20 mW/cm2; λem = 400–460 nm) or PDT 1200L (37.8 mW/cm2; λem = 570–680 nm; both: Waldmann Medizintechnik), respectively. Irradiation parameters ensured identical numbers of photons absorbed by each PS. Three setups were chosen: irradiating the glass pipette only (G), the glass pipette inside the single tooth without (GT) and with (GTM) simulated surrounding tissues. Colony forming units (CFU) were evaluated. Transmission measurements of the buccal halves of hemisected mandibular first molars were performed by means of a photospectrometer. Results: PIB with both PS led to reduction by ≥ 5 log10 of E. faecalis CFU for each setup. From transmission measurements, a threshold wavelength λth for allowing an amount of light transmission for sufficient activation of PS was determined to be 430 nm. Conclusion: This study can be seen as proof of principle that light activation of given intra-canal PS from outside a tooth may be possible at wavelengths ≥ 430 nm, facilitating clinical application of PIB in endodontics. PMID:27379059

  13. A Comparative SEM Investigation of Smear Layer Remaining on Dentinal Walls by Three Rotary NiTi Files with Different Cross Sectional Designs in Moderately Curved Canals

    PubMed Central

    Kakkar, Pooja; Vats, Asit

    2015-01-01

    Objective: The objective of this study was to compare the smear layer formed on root canal walls during canal preparation of extracted human teeth by Twisted, Mtwo, and ProTaper rotary nickel titanium instruments. Materials and Methods: Sixty single rooted human premolar teeth with root curvature <250 were selected and randomly divided into three Groups (n= 20 teeth per Group). Three types of rotary nickel titanium instruments were used, Twisted (SybronEndo, Orange, CA, USA), Mtwo (VDW, Munich, Germany) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) according to manufacturer’s instructions to instrument the root canals. Irrigation for all groups was performed after each instrument change with 3ml of 3% sodium hypochlorite followed by Glyde (File Prep, Dentsply, Maillefer, Ballaigues, Switzerland) as chelator paste and lubricant. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using scanning electron microscopy (SEM). The canal wall of each sample was assessed and compared using a predefined scale for the presence or absence of smear layer. Data were analysed statistically using ANOVA and Tukey HSD test Results: All three groups showed statistically significant more smear layer in the apical thirds of the canal as compared to the coronal and middle thirds (p<0.001). Mtwo rotary file system produced significantly less smear layer (p<0.001) compared to Twisted and ProTaper rotary instruments in the apical portion. Twisted Files resulted in less smear layer formation in the apical thirds of the canal compared to ProTaper rotary instruments but were statistically insignificant. Conclusion: Completely clean root canals were not found after instrumentation with any of the three instruments. Under the confines of this study Mtwo instruments produced significantly cleaner dentin wall surfaces throughout the canal length in comparison to Twisted and ProTaper rotary files. Twisted Files proved to be comparable to Pro

  14. Reconstruction of quadratic curves in 3D using two or more perspective views: simulation studies

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Sukavanam, N.; Balasubramanian, R.

    2006-01-01

    The shapes of many natural and man-made objects have planar and curvilinear surfaces. The images of such curves usually do not have sufficient distinctive features to apply conventional feature-based reconstruction algorithms. In this paper, we describe a method of reconstruction of a quadratic curve in 3-D space as an intersection of two cones containing the respective projected curve images. The correspondence between this pair of projections of the curve is assumed to be established in this work. Using least-square curve fitting, the parameters of a curve in 2-D space are found. From this we are reconstructing the 3-D quadratic curve. Relevant mathematical formulations and analytical solutions for obtaining the equation of reconstructed curve are given. The result of the described reconstruction methodology are studied by simulation studies. This reconstruction methodology is applicable to LBW decision in cricket, path of the missile, Robotic Vision, path lanning etc.

  15. Panama Canal capacity analysis

    SciTech Connect

    Bronzini, M.S.

    1995-04-27

    Predicting the transit capacities of the various Panama Canal alternatives required analyzing data on present Canal operations, adapting and extending an existing computer simulation model, performing simulation runs for each of the alternatives, and using the simulation model outputs to develop capacity estimates. These activities are summarized in this paper. A more complete account may be found in the project final report (TAMS 1993). Some of the material in this paper also appeared in a previously published paper (Rosselli, Bronzini, and Weekly 1994).

  16. Particle sedimentation in curved tubes: A 3D simulation and optimization for treatment of vestibular vertigo

    NASA Astrophysics Data System (ADS)

    White, Brian; Squires, Todd M.; Hain, Timothy C.; Stone, Howard A.

    2003-11-01

    Benign paroxysmal positional vertigo (BPPV) is a mechanical disorder of the vestibular system where micron-size crystals abnormally drift into the semicircular canals of the inner ear that sense angular motion of the head. Sedimentation of these crystals causes sensation of motion after true head motion has stopped: vertigo results. The usual clinical treatment is through a series of head maneuvers designed to move the particles into a less sensitive region of the canal system. We present a three-dimensional model to simulate treatment of BPPV by determining the complete hydrodynamic motion of the particles through the course of a therapeutic maneuver while using a realistic representation of the actual geometry. Analyses of clinical maneuvers show the parameter range for which they are effective, and indicate inefficiencies in current practice. In addition, an optimization process determines the most effective head maneuver, which significantly differs from those currently in practice.

  17. The Simulation of an Oxidation-Reduction Titration Curve with Computer Algebra

    ERIC Educational Resources Information Center

    Whiteley, Richard V., Jr.

    2015-01-01

    Although the simulation of an oxidation/reduction titration curve is an important exercise in an undergraduate course in quantitative analysis, that exercise is frequently simplified to accommodate computational limitations. With the use of readily available computer algebra systems, however, such curves for complicated systems can be generated…

  18. Water pollution risk simulation and prediction in the main canal of the South-to-North Water Transfer Project

    NASA Astrophysics Data System (ADS)

    Tang, Caihong; Yi, Yujun; Yang, Zhifeng; Cheng, Xi

    2014-11-01

    The middle route of the South-to-North Water Transfer Project (MRP) will divert water to Beijing Tuancheng Lake from Taocha in the Danjiangkou reservoir located in the Hubei province of China. The MRP is composed of a long canal and complex hydraulic structures and will transfer water in open channel areas to provide drinking water for Beijing, Shijiazhuang and other cities under extremely strict water quality requirements. A large number of vehicular accidents, occurred on the many highway bridges across the main canal would cause significant water pollution in the main canal. To ensure that water quality is maintained during the diversion process, the effects of pollutants on water quality due to sudden pollution accidents were simulated and analyzed in this paper. The MIKE11 HD module was used to calculate the hydraulic characteristics of the 42-km Xishi-to-Beijuma River channel of the MRP. Six types of hydraulic structures, including inverted siphons, gates, highway bridges, culverts and tunnels, were included in this model. Based on the hydrodynamic model, the MIKE11 AD module, which is one-dimensional advection dispersion model, was built for TP, NH3-N, CODMn and F. The validated results showed that the computed values agreed well with the measured values. In accordance with transportation data across the Dianbei Highway Bridge, the effects of traffic accidents on the bridge on water quality were analyzed. Based on simulated scenarios with three discharge rates (ranged from 12 m3/s to 17 m3/s, 40 m3/s, and 60 m3/s) and three pollution loading concentration levels (5 t, 10 t and 20 t) when trucks spill their contents (i.e., phosphate fertilizer, cyanide, oil and chromium solution) into the channel, emergency measures were proposed. Reasonable solutions to ensure the water quality with regard to the various types of pollutants were proposed, including treating polluted water, maintaining materials, and personnel reserves.

  19. Shaping ability of ProTaper NEXT, ProTaper Universal and iRace files in simulated S-shaped canals.

    PubMed

    Hiran-Us, Sirawut; Pimkhaokham, Somsinee; Sawasdichai, Jirapat; Ebihara, Arata; Suda, Hideaki

    2016-04-01

    The aim of this study was to determine the shaping ability of three nickel-titanium endodontic file systems by comparing three parameters: canal deviation, apical foramen position and instrumentation time. A glide path was established in 30 simulated S-shaped canal blocks that were randomly assigned into three groups (n = 10): ProTaper Universal, ProTaper NEXT and iRace. Each group was instrumented per its manufacturer's directions. Pre- and postoperative images were superimposed to determine any canal deviation or change in apical foramen position. The instrumentation times were recorded. The iRace system resulted in the least mean canal deviation. The apical foramen position was least shifted by the iRace system. The iRace system also required the least instrumentation time. The iRace system demonstrated the most favourable shaping ability in all three parameters. PMID:26420685

  20. The effect of electropolishing on torque and force during simulated root canal preparation with ProTaper shaping files.

    PubMed

    Boessler, Claudia; Paque, Frank; Peters, Ove A

    2009-01-01

    Surface modifications of nickel-titanium instruments such as electropolishing may reduce fracture incidence but could potentially alter the instruments' mechanical properties. We studied the impact of two surface types, machined and electropolished, of ProTaper shaping files on torque and force during simulated root canal preparation. Pilot holes of 0.5-mm diameter were drilled perpendicularly through 3-mm thick human dentin discs and served as standardized simulated root canals (SSRCs). A total of 300 SSRCs were prepared with ProTaper Sx, S1, and S2 instruments using an automated testing platform. Maximum torque (in Ncm) and maximum force values (in N) were measured. In three experimental groups (Sx, S1, and S2) preparation of SSRCs was performed using electropolished versus machined instruments in the same dentin disc. For all three tested instruments, peak torque was higher for electropolished files; apically exerted forces were similar, except for Sx, in which machined instruments developed higher forces. We conclude that surface treatment by electropolishing alters the cutting ability of nickel-titanium rotary instruments. PMID:19084135

  1. Methods for simulating solute breakthrough curves in pumping groundwater wells

    USGS Publications Warehouse

    Starn, J. Jeffrey; Bagtzoglou, Amvrossios C.; Robbins, Gary A.

    2012-01-01

    In modeling there is always a trade-off between execution time and accuracy. For gradient-based parameter estimation methods, where a simulation model is run repeatedly to populate a Jacobian (sensitivity) matrix, there exists a need for rapid simulation methods of known accuracy that can decrease execution time, and thus make the model more useful without sacrificing accuracy. Convolution-based methods can be executed rapidly for any desired input function once the residence-time distribution is known. The residence-time distribution can be calculated efficiently using particle tracking, but particle tracking can be ambiguous near a pumping well if the grid is too coarse. We present several embedded analytical expressions for improving particle tracking near a pumping well and compare them with a finely gridded finite-difference solution in terms of accuracy and CPU usage. Even though the embedded analytical approach can improve particle tracking near a well, particle methods reduce, but do not eliminate, reliance on a grid because velocity fields typically are calculated on a grid, and additional error is incurred using linear interpolation of velocity. A dilution rate can be calculated for a given grid and pumping well to determine if the grid is sufficiently refined. Embedded analytical expressions increase accuracy but add significantly to CPU usage. Structural error introduced by the numerical solution method may affect parameter estimates.

  2. Methods for simulating solute breakthrough curves in pumping groundwater wells

    NASA Astrophysics Data System (ADS)

    Jeffrey Starn, J.; Bagtzoglou, Amvrossios C.; Robbins, Gary A.

    2012-11-01

    In modeling there is always a trade-off between execution time and accuracy. For gradient-based parameter estimation methods, where a simulation model is run repeatedly to populate a Jacobian (sensitivity) matrix, there exists a need for rapid simulation methods of known accuracy that can decrease execution time, and thus make the model more useful without sacrificing accuracy. Convolution-based methods can be executed rapidly for any desired input function once the residence-time distribution is known. The residence-time distribution can be calculated efficiently using particle tracking, but particle tracking can be ambiguous near a pumping well if the grid is too coarse. We present several embedded analytical expressions for improving particle tracking near a pumping well and compare them with a finely gridded finite-difference solution in terms of accuracy and CPU usage. Even though the embedded analytical approach can improve particle tracking near a well, particle methods reduce, but do not eliminate, reliance on a grid because velocity fields typically are calculated on a grid, and additional error is incurred using linear interpolation of velocity. A dilution rate can be calculated for a given grid and pumping well to determine if the grid is sufficiently refined. Embedded analytical expressions increase accuracy but add significantly to CPU usage. Structural error introduced by the numerical solution method may affect parameter estimates.

  3. Comparative evaluation of a novel smart-seal obturating system and its homogeneity of using cone beam computed tomography: In vitro simulated lateral canal study

    PubMed Central

    Arora, Shashank; Hegde, Vibha

    2014-01-01

    Aim: The aim was to evaluate and compare a novel polyamide polymer based obturating system and Gutta-percha and sealer in filling simulated lateral canals and their homogeneity when used for obturating the root canals. Materials and Methods: A total of 60 freshly extracted human single rooted teeth with fully formed apices were selected for this study. Teeth were de-coronated, and roots were standardized to a working length of 15 mm. Root canal preparation was carried out with rotary Protaper file system in all groups. The specimens were then randomly divided into three groups A, B, and C (n = 20). Ten samples from each group were decalcified and simulated lateral canals were made at 2, 4, and 6 mm from the root apex. Remaining ten samples from each group were maintained calcified. Group A was obturated with SmartSeal system (Prosmart-DRFP Ltd., Stamford, UK). Group B was obturated with sectional backfill method. Group C was obutrated with cold lateral compaction method (control). Decalcified samples from the respective groups were analyzed with digital radiography and photography and the measurement of the linear extension and area of lateral canal filling was done using UTHSCSA (UTHSCSA Image Tool for Windows version 3.0, San Antonio, TX, USA) software. Calcified samples were subjected to cone beam computed tomography image analysis sectioned axially. Results: Group A 92.46 ± 19.45 showed greatest extent of filling in lateral canals and denser homogeneity of oburation, followed by Group B 78.43 ± 26.45 and Group C 52.12 ± 36.67. Conclusions: Polyamide polymer obturation proved to have greater efficiency when compared with Gutta-percha system, when used for obturation with regards to adaptation of the sealer and penetration into the simulated lateral canals. PMID:25125851

  4. Simulation of a G-tolerance curve using the pulsatile cardiovascular model

    NASA Technical Reports Server (NTRS)

    Solomon, M.; Srinivasan, R.

    1985-01-01

    A computer simulation study, performed to assess the ability of the cardiovascular model to reproduce the G tolerance curve (G level versus tolerance time) is reported. A composite strength duration curve derived from experimental data obtained in human centrifugation studies was used for comparison. The effects of abolishing automomic control and of blood volume loss on G tolerance were also simulated. The results provide additional validation of the model. The need for the presence of autonomic reflexes even at low levels of G is pointed out. The low margin of safety with a loss of blood volume indicated by the simulation results underscores the necessity for protective measures during Shuttle reentry.

  5. On a framework for generating PoD curves assisted by numerical simulations

    NASA Astrophysics Data System (ADS)

    Subair, S. Mohamed; Agrawal, Shweta; Balasubramaniam, Krishnan; Rajagopal, Prabhu; Kumar, Anish; Rao, Purnachandra B.; Tamanna, Jayakumar

    2015-03-01

    The Probability of Detection (PoD) curve method has emerged as an important tool for the assessment of the performance of NDE techniques, a topic of particular interest to the nuclear industry where inspection qualification is very important. The conventional experimental means of generating PoD curves though, can be expensive, requiring large data sets (covering defects and test conditions), and equipment and operator time. Several methods of achieving faster estimates for PoD curves using physics-based modelling have been developed to address this problem. Numerical modelling techniques are also attractive, especially given the ever-increasing computational power available to scientists today. Here we develop procedures for obtaining PoD curves, assisted by numerical simulation and based on Bayesian statistics. Numerical simulations are performed using Finite Element analysis for factors that are assumed to be independent, random and normally distributed. PoD curves so generated are compared with experiments on austenitic stainless steel (SS) plates with artificially created notches. We examine issues affecting the PoD curve generation process including codes, standards, distribution of defect parameters and the choice of the noise threshold. We also study the assumption of normal distribution for signal response parameters and consider strategies for dealing with data that may be more complex or sparse to justify this. These topics are addressed and illustrated through the example case of generation of PoD curves for pulse-echo ultrasonic inspection of vertical surface-breaking cracks in SS plates.

  6. On a framework for generating PoD curves assisted by numerical simulations

    SciTech Connect

    Subair, S. Mohamed Agrawal, Shweta Balasubramaniam, Krishnan Rajagopal, Prabhu; Kumar, Anish; Rao, Purnachandra B.; Tamanna, Jayakumar

    2015-03-31

    The Probability of Detection (PoD) curve method has emerged as an important tool for the assessment of the performance of NDE techniques, a topic of particular interest to the nuclear industry where inspection qualification is very important. The conventional experimental means of generating PoD curves though, can be expensive, requiring large data sets (covering defects and test conditions), and equipment and operator time. Several methods of achieving faster estimates for PoD curves using physics-based modelling have been developed to address this problem. Numerical modelling techniques are also attractive, especially given the ever-increasing computational power available to scientists today. Here we develop procedures for obtaining PoD curves, assisted by numerical simulation and based on Bayesian statistics. Numerical simulations are performed using Finite Element analysis for factors that are assumed to be independent, random and normally distributed. PoD curves so generated are compared with experiments on austenitic stainless steel (SS) plates with artificially created notches. We examine issues affecting the PoD curve generation process including codes, standards, distribution of defect parameters and the choice of the noise threshold. We also study the assumption of normal distribution for signal response parameters and consider strategies for dealing with data that may be more complex or sparse to justify this. These topics are addressed and illustrated through the example case of generation of PoD curves for pulse-echo ultrasonic inspection of vertical surface-breaking cracks in SS plates.

  7. Comparison of the shaping ability of RaCe and FlexMaster rotary nickel-titanium systems in simulated canals.

    PubMed

    Merrett, Sarah J; Bryant, Susan T; Dummer, Paul M H

    2006-10-01

    The aim of this study was to compare the shaping ability of RaCe and FlexMaster rotary nickel-titanium instruments in simulated canals. A total of 80 canals with four different shapes were prepared with either RaCe or FlexMaster instruments. Pre- and postoperative images of each canal were recorded and combined using image analysis software. The development of canal aberrations and transportation was assessed. There was a significant difference (p < 0.001) between the systems for time of preparation to apical size 30, .06 taper; FlexMaster instruments took on average 1.86 min and RaCe 1.66 min. One RaCe and two FlexMaster instruments fractured. No zips, elbows, or danger zones were created. One perforation and eight outer widenings were created using FlexMaster instruments; RaCe instruments created two outer widenings. No differences were found between the instruments for direction of transportation. RaCe and FlexMaster nickel-titanium instruments prepared canals rapidly with few aberrations. PMID:16982273

  8. Light Curve Simulation Using Spacecraft CAD Models and Empirical Material Spectral BRDFS

    NASA Astrophysics Data System (ADS)

    Willison, A.; Bedard, D.

    This paper presents a Matlab-based light curve simulation software package that uses computer-aided design (CAD) models of spacecraft and the spectral bidirectional reflectance distribution function (sBRDF) of their homogenous surface materials. It represents the overall optical reflectance of objects as a sBRDF, a spectrometric quantity, obtainable during an optical ground truth experiment. The broadband bidirectional reflectance distribution function (BRDF), the basis of a broadband light curve, is produced by integrating the sBRDF over the optical wavelength range. Colour-filtered BRDFs, the basis of colour-filtered light curves, are produced by first multiplying the sBRDF by colour filters, and integrating the products. The software package's validity is established through comparison of simulated reflectance spectra and broadband light curves with those measured of the CanX-1 Engineering Model (EM) nanosatellite, collected during an optical ground truth experiment. It is currently being extended to simulate light curves of spacecraft in Earth orbit, using spacecraft Two-Line-Element (TLE) sets, yaw/pitch/roll angles, and observer coordinates. Measured light curves of the NEOSSat spacecraft will be used to validate simulated quantities. The sBRDF was chosen to represent material reflectance as it is spectrometric and a function of illumination and observation geometry. Homogeneous material sBRDFs were obtained using a goniospectrometer for a range of illumination and observation geometries, collected in a controlled environment. The materials analyzed include aluminum alloy, two types of triple-junction photovoltaic (TJPV) cell, white paint, and multi-layer insulation (MLI). Interpolation and extrapolation methods were used to determine the sBRDF for all possible illumination and observation geometries not measured in the laboratory, resulting in empirical look-up tables. These look-up tables are referenced when calculating the overall sBRDF of objects, where

  9. Digital simulation error curves for a spring-mass-damper system

    NASA Technical Reports Server (NTRS)

    Knox, L. A.

    1971-01-01

    Plotting digital simulation errors for a spring-mass-damper system and using these error curves to select type of integration, feedback update method, and number of samples per cycle at resonance reduces excessive number of samples per cycle and unnecessary iterations.

  10. 3D Numerical Simulation of Turbulent Buoyant Flow and Heat Transport in a Curved Open Channel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A three-dimensional buoyancy-extended version of kappa-epsilon turbulence model was developed for simulating the turbulent flow and heat transport in a curved open channel. The density- induced buoyant force was included in the model, and the influence of temperature stratification on flow field was...

  11. Monte Carlo Simulations for the Purpose of Efficiency Curve Calibration for the Fastscan Whole Body Counter

    NASA Astrophysics Data System (ADS)

    Graham, Hannah Robyn

    In order to be able to qualify and quantify radiation exposure in terms of dose, a Fastscan whole body counter must be calibrated correctly. Current calibration methods do not take the full range of body types into consideration when creating efficiency curve calibrations. The goal of this work is the creation of a Monte Carlo (MCNP) model, that allows the simulation of efficiency curves for a diverse population of subjects. Models were created for both the Darlington and the Pickering Fastscan WBCs, and the simulations were benchmarked against experimental results with good agreement. The Pickering Fastscan was found to have agreement to within +/-9%, and the Darlington Fastscan had agreement to within +/-11%. Further simulations were conducted to investigate the effects of increased body fat on the detected activity, as well as locating the position of external contamination using front/back ratios of activity. Simulations were also conducted to create efficiency calibrations that had good agreement with the manufacturer's efficiency curves. The work completed in this thesis can be used to create efficiency calibration curves for unique body compositions in the future.

  12. Comparison of the shaping ability of GT® Series X, Twisted Files and AlphaKite rotary nickel-titanium systems in simulated canals

    PubMed Central

    2013-01-01

    Background Efforts to improve the performance of rotary NiTi instruments by enhancing the properties of NiTi alloy, or their manufacturing processes rather than changes in instrument geometries have been reported. The aim of this study was to compare in-vitro the shaping ability of three different rotary nickel-titanium instruments produced by different manufacturing methods. Methods Thirty simulated root canals with a curvature of 35˚ in resin blocks were prepared with three different rotary NiTi systems: AK- AlphaKite (Gebr. Brasseler, Germany), GTX- GT® Series X (Dentsply, Germany) and TF- Twisted Files (SybronEndo, USA). The canals were prepared according to the manufacturers’ instructions. Pre- and post-instrumentation images were recorded and assessment of canal curvature modifications was carried out with an image analysis program (GSA, Germany). The preparation time and incidence of procedural errors were recorded. Instruments were evaluated under a microscope with 15 × magnifications (Carl Zeiss OPMI Pro Ergo, Germany) for signs of deformation. The Data were statistically analyzed using SPSS (Wilcoxon and Mann–Whitney U-tests, at a confidence interval of 95%). Results Less canal transportation was produced by TF apically, although the difference among the groups was not statistically significant. GTX removed the greatest amount of resin from the middle and coronal parts of the canal and the difference among the groups was statistically significant (p < 0.05). The shortest preparation time was registered with TF (444 s) and the longest with GTX (714 s), the difference among the groups was statistically significant (p < 0.05). During the preparation of the canals no instrument fractured. Eleven instruments of TF and one of AK were deformed. Conclusion Under the conditions of this study, all rotary NiTi instruments maintained the working length and prepared a well-shaped root canal. The least canal transportation was produced by AK. GTX

  13. Projectile shape influence on ballistic limit curves as determined by computational simulation

    SciTech Connect

    Hertel, E.S. Jr.; Chhabildas, L.C.

    1995-09-01

    A requirement for an effective debris shield is that it must protect a spacecraft from impacts by irregularly shaped particles. A series of numerical simulations has been performed using the multi-dimensional shock physics code CTH to numerically determine the ballistic limit curve for a Whipple bumper shield. Two different projectile shapes are considered for the numerical simulations, flat plates of varying diameters with a constant thickness and spheres of varying diameters. The critical diameter of ballistic limit was determined over a velocity range from 4 km/s to 15 km/s. We have found both experimentally and numerically that the particle shape has a significant effect on the debris cloud distribution, ballistic limit curve, and penetration capability.

  14. Dispersion curves from short-time molecular dynamics simulation. 1. Diatomic chain results

    SciTech Connect

    Noid, D.W.; Broocks, B.T.; Gray, S.K.; Marple, S.L.

    1988-06-16

    The multiple signal classification method (MUSIC) for frequency estimation is used to compute the frequency dispersion curves of a diatomic chain from the time-dependent structure factor. In this paper, the authors demonstrate that MUSIC can accurately determine the frequencies from very short time trajectories. MUSIC is also used to show how the frequencies can vary in time, i.e., along a trajectory. The method is ideally suited for analyzing molecular dynamics simulations of large systems.

  15. Comparative Study on Two Melting Simulation Methods: Melting Curve of Gold

    NASA Astrophysics Data System (ADS)

    Liu, Zhong-Li; Sun, Jun-Sheng; Li, Rui; Zhang, Xiu-Lu; Cai, Ling-Cang

    2016-05-01

    Melting simulation methods are of crucial importance to determining melting temperature of materials efficiently. A high-efficiency melting simulation method saves much simulation time and computational resources. To compare the efficiency of our newly developed shock melting (SM) method with that of the well-established two-phase (TP) method, we calculate the high-pressure melting curve of Au using the two methods based on the optimally selected interatomic potentials. Although we only use 640 atoms to determine the melting temperature of Au in the SM method, the resulting melting curve accords very well with the results from the TP method using much more atoms. Thus, this shows that a much smaller system size in SM method can still achieve a fully converged melting curve compared with the TP method, implying the robustness and efficiency of the SM method. Supported by the National Natural Science Foundation of China under Grant No. 41574076 and the NSAF of China under Grant No. U1230201/A06, and the Young Core Teacher Scheme of Henan Province under Grant No. 2014GGJS-108

  16. Simulation of Stress-Strain Curves of Polyester and Viscose Filaments

    NASA Astrophysics Data System (ADS)

    Ghosh, Anindya; Das, Subhasis; Saha, Bapi

    2015-10-01

    Eyring's non-linear visco-elastic model has been used to simulate stress-strain behaviours of polyester and viscose filaments. The complex mathematical equations of Eyring's model for curve fitting are handled by non-traditional optimization methods such as genetic algorithm. The findings show that Eyring's model can be used to simulate the stress-strain behaviours of the polyester and viscose filaments with reasonable degree of accuracy. It can also decipher the underlying molecular mechanism of the stress-strain behaviours.

  17. Forculator: A Micromagnetic Tool for Simulating First-Order Reversal Curve Diagrams

    NASA Astrophysics Data System (ADS)

    Harrison, R. J.; Lascu, I.

    2014-12-01

    We describe a method for simulating first-order reversal curve (FORC) diagrams of interacting single-domain particles. Magnetostatic interactions are calculated in real space, allowing simulations to be performed for particle ensembles with arbitrary geometry. For weakly interacting uniaxial particles, the equilibrium magnetization at each field step is obtained by direct solution of the Stoner-Wohlfarth model, assuming a quasi-static distribution of interaction fields. For all other cases, the equilibrium magnetization is calculated using an approximate iterated solution to the Landau-Lifshitz-Gilbert equation. Multithreading is employed to allow multiple curves to be computed simultaneously, enabling FORC diagrams to be simulated in reasonable time using a standard desktop computer. Statistical averaging and post processing lead to simulated FORC diagrams that are comparable to their experimental counterparts. The method is applied to several geometries of relevance to rock and environmental magnetism, including densely packed random clusters and partially collapsed chains. The method forms the basis of FORCulator, a freely available software tool with graphical user interface that will enable FORC simulations to become a routine part of rock magnetic studies.

  18. [Frequency and most common localisation of root canal curvature].

    PubMed

    Blasković-Subat, V

    1991-01-01

    The root canal therapy of the curved canals is a complex operative procedure. Therefore 260 root canals were analysed radiologically to determine the frequency and the most common localisation of the root canal curvature. The frequency of the curved canals averaged at 59%, being greater in the sample of posterior than in the anterior teeth (p less than 0.05). The root canal curvature was most frequently localised at the apical third part (53.9%), followed by the cervical (33.3%) and the middle (12.8%) third part. The apical curvature was predominant in the sample of the anterior, while the cervical predominant (45.2%) in the sample of the posterior teeth. This study pointed out that the frequency of the curved canals is rather high. Consequently, the necessity for practising the modern root canal preparation techniques, bearing in mind their potential danger, is emphasized. PMID:1819932

  19. Simulation technique for extrapolation curves in 4πβ-γ coincidence counting method using EGS5 code.

    PubMed

    Unno, Y; Sanami, T; Sasaki, S; Hagiwara, M; Yunoki, A

    2016-03-01

    A simulation technique was developed for the extrapolation technique in 4πβ-γ coincidence counting method. Simultaneous emissions of β and γ rays were calculated using EGS5 code to obtain coincidence counting between both β and γ channels. The simulated extrapolation curves were compared with experimental data obtained with (134)Cs measurements using a plastic scintillator in the β channel. The variation of the extrapolation curves with γ-gate configuration was investigated by the simulation technique. PMID:26688354

  20. Cell-centred model for the simulation of curved cellular monolayers

    NASA Astrophysics Data System (ADS)

    Mosaffa, Payman; Asadipour, Nina; Millán, Daniel; Rodríguez-Ferran, Antonio; J Muñoz, Jose

    2015-12-01

    This paper presents a cell-centred model for the simulation of planar and curved multicellular soft tissues. We propose a computational model that includes stress relaxation due to cell reorganisation (intercellular connectivity changes) and cytoskeleton remodelling (intracellular changes). Cells are represented by their cell centres, and their mechanical interaction is modelled through active non-linear elastic laws with a dynamically changing resting length. Special attention is paid to the handling of connectivity changes between cells, and the relaxation that the tissues exhibit under these topological changes. Cell-cell connectivity is computed by resorting to a Delaunay triangulation, which is combined with a mapping technique in order to obtain triangulations on curved manifolds. Our numerical results show that even a linear elastic cell-cell interaction model may induce a global non-linear response due to the reorganisation of the cell connectivity. This plastic-like behaviour is combined with a non-linear rheological law where the resting length depends on the elastic strain, mimicking the global visco-elastic response of tissues. The model is applied to simulate the elongation of planar and curved monolayers.

  1. Simulation of curving behaviour under high traction in lubricated wheel-rail contacts

    NASA Astrophysics Data System (ADS)

    Arias-Cuevas, Oscar; Li, Zili; Popovici, Radu I.; Schipper, Dik J.

    2010-12-01

    Migration of the flange lubricant to the top of the high rail may compromise the traction of a rail vehicle and affect its curving behaviour. In order to simulate this possible situation, a lubrication model has been coupled to commercial multi-body dynamics software to describe the tangential formulation of the lubricated high-rail contact. Different friction levels have been adopted for the low rail to study their influence on the curving behaviour and traction. Since the creep force in the wheel-rail contact approaches saturation of the friction, the traction control unit of the rail vehicle under study has also been modelled to account for the reduction of the wheel axle torque in the presence of wheel macro-slip.

  2. Simulation of flows with moving contact lines on curved substrates by immersed boundary methods

    NASA Astrophysics Data System (ADS)

    Ding, Hang; Liu, Hao-Ran

    2014-11-01

    We propose an approach to simulate flows with moving contact lines (MCLs) on curved substrates. The approach combines an immersed boundary method with a three-component diffuse-interface model and a characteristic MCL model. The immersed boundary method circumvents the penetration of the gas and the liquid into the solid by convection while the three-component diffuse-interface model can prevent the diffusive fluxes of the gas and liquid from infiltrating into the solid substrate. The characteristic MCL model not only allows for the motion of contact lines, but makes the gas-liquid interface to intersect the solid object at an angle in consistence with the prescribed contact angle, even with tangent variation at the solid surface. We examine the performance of the approach through a variety of numerical experiments: mass conservation and interface shapes at equilibrium were tested through the simulation of drop spreading on a circular cylinder, while the dynamic behavior of MCLs on the curved boundaries was investigated by simulating water entry of and drop impact on a sphere, respectively. At last, we studied the penetration process of a drop into a cluster of circular cylinders. This article was supported by 100 Talents Program of The Chinese Academy of Sciences and the National Natural Science Foundation of China (Grant No. 11172294).

  3. Molecular dynamics simulations of the melting curve of NiAl alloy under pressure

    SciTech Connect

    Zhang, Wenjin; Peng, Yufeng; Liu, Zhongli

    2014-05-15

    The melting curve of B2-NiAl alloy under pressure has been investigated using molecular dynamics technique and the embedded atom method (EAM) potential. The melting temperatures were determined with two approaches, the one-phase and the two-phase methods. The first one simulates a homogeneous melting, while the second one involves a heterogeneous melting of materials. Both approaches reduce the superheating effectively and their results are close to each other at the applied pressures. By fitting the well-known Simon equation to our melting data, we yielded the melting curves for NiAl: 1783(1 + P/9.801){sup 0.298} (one-phase approach), 1850(1 + P/12.806){sup 0.357} (two-phase approach). The good agreement of the resulting equation of states and the zero-pressure melting point (calc., 1850 ± 25 K, exp., 1911 K) with experiment proved the correctness of these results. These melting data complemented the absence of experimental high-pressure melting of NiAl. To check the transferability of this EAM potential, we have also predicted the melting curves of pure nickel and pure aluminum. Results show the calculated melting point of Nickel agrees well with experiment at zero pressure, while the melting point of aluminum is slightly higher than experiment.

  4. Comparison of two warning concepts of an intelligent Curve Warning system for motorcyclists in a simulator study.

    PubMed

    Huth, Véronique; Biral, Francesco; Martín, Oscar; Lot, Roberto

    2012-01-01

    Curve crashes are a particular matter of concern regarding motorcycle riding safety. For this reason, an intelligent Curve Warning system has been designed that gives the riders support when negotiating a curve. The system has been tested in a simulator study carried out with 20 test riders. The subjects performed three rides: one without the system (baseline) and two experimental rides using a version of the Curve Warning system, one providing the warnings by a force feedback throttle and one by a haptic glove. The effects of the two system versions were evaluated both in terms of the simulated riding performance and the subjective assessment by the riders. A descriptive analysis of the riders' reactions to the warnings shows that the warnings provided by both system versions provoke an earlier and stronger adaptation of the motorcycle dynamics to the curve than when the riders do not use the system. Riding with the Curve Warning system with the haptic glove furthermore leads to a reduction of critical curve events. The riders' subjective workload level was not affected by the system use, whereas the Curve Warning system with the force feedback throttle required an increased attention. The comparison of the riders' opinions about the system reveals a preference of the Curve Warning system with the haptic glove. The better acceptance of this system version suggests a higher potential in the enhancement of riding safety. PMID:22062345

  5. 20. 1934 aerial of Tempe Canal, Sections 9, 16, and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. 1934 aerial of Tempe Canal, Sections 9, 16, and 17 (T1N R5E) (top of page is north). The Tempe Crosscut is seen as the dark line entering from top right, which turns north, then curves around the Chandler Falls powerhouse. The canal then curves slowly around to the southwest. The old Trunk Ditch is visible at the top of the curve, coming in from the northeast. A wasteway (top left) runs west from the canal to the Salt River. Photographer: Unknown, 1934. Source: SRP Cartographic Drafting - Tempe Canal, South Side Salt River in Tempe, Mesa & Phoenix, Tempe, Maricopa County, AZ

  6. Transfer function approach based on simulation results for the determination of pod curves

    NASA Astrophysics Data System (ADS)

    Demeyer, S.; Jenson, F.; Dominguez, N.; Iakovleva, E.

    2012-05-01

    POD curves estimations are based on statistical studies of empirical data which are obtained thru costly and time consuming experimental campaigns. Currently, cost reduction of POD trials is a major issue. A proposed solution is to replace some of the experimental data required to determine the POD with model based results. Following this idea, the concept of Model Assisted POD (MAPOD) has been introduced first in the US in 2004 through the constitution of the MAPOD working group. One approach to Model Assisted POD is based on a transfer function which uses empirical data and models to transfer POD measured for one specific application to another related application. The objective of this paper is to show how numerical simulations could help to determine such transfer functions. A practical implementation of the approach to a high frequency eddy current inspection for fatigue cracks is presented. Empirical data is available for the titanium alloy plates. A model based transfer function is used to assess a POD curve for the inspection of aluminum components.

  7. Toward computer simulation of high-LET in vitro survival curves

    NASA Astrophysics Data System (ADS)

    Heuskin, A.-C.; Michiels, C.; Lucas, S.

    2013-09-01

    We developed a Monte Carlo based computer program called MCSC (Monte Carlo Survival Curve) able to predict the survival fraction of cells irradiated in vitro with a broad beam of high linear energy transfer particles. Three types of cell responses are studied: the usual high dose response, the bystander effect and the low-dose hypersensitivity (HRS). The program models the broad beam irradiation and double strand break distribution following Poisson statistics. The progression of cells through the cell cycle is taken into account while the repair takes place. Input parameters are experimentally determined for A549 lung carcinoma cells irradiated with 10 and 20 keV µm-1 protons, 115 keV µm-1 alpha particles and for EAhy926 endothelial cells exposed to 115 keV µm-1 alpha particles. Results of simulations are presented and compared with experimental survival curves obtained for A549 and EAhy296 cells. Results are in good agreement with experimental data for both cell lines and all irradiation protocols. The benefits of MCSC are several: the gain of time that would have been spent performing time-consuming clonogenic assays, the capacity to estimate survival fraction of cell lines not forming colonies and possibly the evaluation of radiosensitivity parameters of given individuals.

  8. A fixed-base simulation study of two STOL aircraft flying curved, descending instrument approach paths

    NASA Technical Reports Server (NTRS)

    Benner, M. S.; Sawyer, R. H.; Mclaughlin, M. D.

    1973-01-01

    A real-time, fixed-base simulation study has been conducted to determine the curved, descending approach paths (within passenger-comfort limits) that would be acceptable to pilots, the flight-director-system logic requirements for curved-flight-path guidance, and the paths which can be flown within proposed microwave landing system (MLS) coverage angles. Two STOL aircraft configurations were used in the study. Generally, no differences in the results between the two STOL configurations were found. The investigation showed that paths with a 1828.8 meter turn radius and a 1828.8 meter final-approach distance were acceptable without winds and with winds up to at least 15 knots for airspeeds from 75 to 100 knots. The altitude at roll-out from the final turn determined which final-approach distances were acceptable. Pilots preferred to have an initial straight leg of about 1 n. mi. after MLS guidance acquisition before turn intercept. The size of the azimuth coverage angle necessary to meet passenger and pilot criteria depends on the size of the turn angle: plus or minus 60 deg was adequate to cover all paths execpt ones with a 180 deg turn.

  9. Numerical simulation of flow and aquaculture organic waste dispersion in a curved channel

    NASA Astrophysics Data System (ADS)

    Ali, Alfatih; Thiem, Øyvind; Berntsen, Jarle

    2013-10-01

    The dispersion and deposition of particulate organic matter from a fish cage located in an idealized curved channel with a 90° bend are studied for different horizontal grid resolutions. The model system consists of a three-dimensional, random-walk particle tracking model coupled to a terrain-following ocean model. The particle tracking model is a Lagrangian particle tracking simulator which uses the local flow field, simulated by the ocean model, for advection of the particles and random walk to simulate the turbulent diffusion. The sinking of particles is modeled by imposing an individual particle settling velocity. As the homogeneous water flows through the bend in the channel, the results show that a cross-channel secondary circulation is developed. The motion of this flow is similar to a helical motion where the water in the upper layers moves towards the outer bank and towards the inner bank in the lower layers. The intensity of the secondary circulation will depend on the viscosity scheme and increases as the horizontal grid resolution decreases which significantly affects the distribution of the particles on the seabed. The presence of the secondary circulation leads to that most of the particles that settle, settle close to the inner bank of the channel.

  10. Effects of the Offset Term in Experimental Simulation on Afterglow Decay Curve

    PubMed Central

    Tsai, Chi-Yang; Lin, Jeng-Wen; Huang, Yung-Chieh

    2014-01-01

    This study examines the effect of the offset term in a multiple single exponential equation that fits into experimental afterglow decay curve data for material applications. For afterglow materials applied and attached to structures, the inclusion of this offset term may reduce the values of the calculated decay times, τi, and enlarge the time invariant constants, Ai, in the associated equation compared to theoretically perfect test conditions. Using a set of experimental data obtained from a lab under dim light, adjustments can be made to calculate the required parameters for an equation without the offset term. This study uses mathematical simulations and lab tests to support our thesis and crosslink test results generated from different ambient light conditions. This paper defines the offset ratio as the ratio of the offset value, I0, versus the initial light intensity in an equation. This ratio can be used to evaluate possible effects on the calculated parameters of an equation in an associated numerical simulation. The most reliable parameters will have consistent results from the use of multiple single exponential equations, with and without the offset term, in simulations to obtain them in an equation to model a set of data. PMID:25089289

  11. Effects of the offset term in experimental simulation on afterglow decay curve.

    PubMed

    Tsai, Chi-Yang; Lin, Jeng-Wen; Huang, Yih-Ping; Huang, Yung-Chieh

    2014-01-01

    This study examines the effect of the offset term in a multiple single exponential equation that fits into experimental afterglow decay curve data for material applications. For afterglow materials applied and attached to structures, the inclusion of this offset term may reduce the values of the calculated decay times, τ i , and enlarge the time invariant constants, A i , in the associated equation compared to theoretically perfect test conditions. Using a set of experimental data obtained from a lab under dim light, adjustments can be made to calculate the required parameters for an equation without the offset term. This study uses mathematical simulations and lab tests to support our thesis and crosslink test results generated from different ambient light conditions. This paper defines the offset ratio as the ratio of the offset value, I 0, versus the initial light intensity in an equation. This ratio can be used to evaluate possible effects on the calculated parameters of an equation in an associated numerical simulation. The most reliable parameters will have consistent results from the use of multiple single exponential equations, with and without the offset term, in simulations to obtain them in an equation to model a set of data. PMID:25089289

  12. Reducing spurious gravitational radiation in binary-black-hole simulations by using conformally curved initial data

    NASA Astrophysics Data System (ADS)

    Lovelace, Geoffrey

    2009-06-01

    At early times in numerical evolutions of binary black holes, current simulations contain an initial burst of spurious gravitational radiation (also called 'junk radiation') which is not astrophysically realistic. The spurious radiation is a consequence of how the binary-black-hole initial data are constructed: the initial data are typically assumed to be conformally flat. In this paper, I adopt a curved conformal metric that is a superposition of two boosted, non-spinning black holes that are approximately 15 orbits from merger. I compare junk radiation of the superposed-boosted-Schwarzschild (SBS) initial data with the junk of corresponding conformally flat, maximally sliced (CFMS) initial data. The SBS junk is smaller in amplitude than the CFMS junk, with the junk's leading-order spectral modes typically being reduced by a factor of order 2 or more.

  13. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    NASA Astrophysics Data System (ADS)

    Dai, Qi; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-02-01

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330-390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  14. Ultrasonic cleaning of root canals

    NASA Astrophysics Data System (ADS)

    Verhaagen, Bram; Boutsioukis, Christos; Jiang, Lei-Meng; Macedo, Ricardo; van der Sluis, Luc; Versluis, Michel

    2011-11-01

    A crucial step during a dental root canal treatment is irrigation, where an antimicrobial fluid is injected into the root canal system to eradicate all bacteria. Agitation of the fluid using an ultrasonically vibrating miniature file has shown significant improvement in cleaning efficacy over conventional syringe irrigation. However, the physical mechanisms underlying the cleaning process, being acoustic streaming, cavitation or chemical activity, and combinations thereof, are not fully understood. High-speed imaging allows us to visualize the flow pattern and cavitation in a root canal model at microscopic scales, at timescales relevant to the cleaning processes (microseconds). MicroPIV measurements of the induced acoustic streaming are coupled to the oscillation characteristics of the file as simulated numerically and measured with a laser vibrometer. The results give new insight into the role of acoustic streaming and the importance of the confinement for the cleaning of root canals.

  15. Analog-model simulations for secondary canal controls and forward pumping water-management schemes in southeast Florida

    USGS Publications Warehouse

    Cordes, E.H.; Gardner, Richard Alfred

    1976-01-01

    The analog model of the Biscayne aquifer of southeast Florida was used to approximate the effects of two proposed water-management schemes. One involved adding a secondary control structure in a major canal which is controlled near the coast. In the model the controls were operated in accordance with canal water level both above and below the secondary control. Although the model could not differentiate between control openings of 1 foot or 5 feet, it showed that the secondary control is a viable method of conserving ground water. The second scheme involved pumping ground water ('forward pumping') from the Biscayne aquifer in inland areas during the dry season to: (1) augment canal flows toward the coast to sustain ground-water levels there, and (2) generate additional ground-water storage space for recharge in the wet season. Several sites on the model were programmed for forward pumping wells and the storage change was noted as a percentage of the ground-water withdrawal. (Woodard-USGS)

  16. Tsunami Simulation using CIP Method with Characteristic Curve Equations and TVD-MacCormack Method

    NASA Astrophysics Data System (ADS)

    Fukazawa, Souki; Tosaka, Hiroyuki

    2015-04-01

    After entering 21st century, we already had two big tsunami disasters associated with Mw9 earthquakes in Sumatra and Japan. To mitigate the damages of tsunami, the numerical simulation technology combined with information technologies could provide reliable predictions in planning countermeasures to prevent the damage to the social system, making safety maps, and submitting early evacuation information to the residents. Shallow water equations are still solved not only for global scale simulation of the ocean tsunami propagation but also for local scale simulation of overland inundation in many tsunami simulators though three-dimensional model starts to be used due to improvement of CPU. One-dimensional shallow water equations are below: partial bm{Q}/partial t+partial bm{E}/partial x=bm{S} in which bm{Q}=( D M )), bm{E}=( M M^2/D+gD^2/2 )), bm{S}=( 0 -gDpartial z/partial x-gn2 M|M| /D7/3 )). where D[m] is total water depth; M[m^2/s] is water flux; z[m] is topography; g[m/s^2] is the gravitational acceleration; n[s/m1/3] is Manning's roughness coefficient. To solve these, the staggered leapfrog scheme is used in a lot of wide-scale tsunami simulator. But this scheme has a problem that lagging phase error occurs when courant number is small. In some practical simulation, a kind of diffusion term is added. In this study, we developed two wide-scale tsunami simulators with different schemes and compared usual scheme and other schemes in practicability and validity. One is a total variation diminishing modification of the MacCormack method (TVD-MacCormack method) which is famous for the simulation of compressible fluids. The other is the Cubic Interpolated Profile (CIP) method with characteristic curve equations transformed from shallow water equations. Characteristic curve equations derived from shallow water equations are below: partial R_x±/partial t+C_x±partial R_x±/partial x=∓ g/2partial z/partial x in which R_x±=√{gD}± u/2, C_x±=u± √{gD}. where u

  17. 3. ELEVATION. FROM SOUTH WITH CANAL PRISM. Canal Road ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. ELEVATION. FROM SOUTH WITH CANAL PRISM. - Canal Road Bridge, Canal Road spanning Delaware Canal Diversion, Locks 22 & 23 in Delaware Canal State Park in Williams Township, Raubsville, Northampton County, PA

  18. ProTaper and WaveOne systems three-dimensional comparison of device parameters after the shaping technique. A micro-CT study on simulated root canals

    PubMed Central

    Dioguardi, Mario; Troiano, Giuseppe; Laino, Luigi; Russo, Lucio Lo; Giannatempo, Giovanni; Lauritano, Floriana; Cicciù, Marco; Muzio, Lorenzo Lo

    2015-01-01

    Aim: The aim of this study is to highlights possible differences in the volume of shaping and canal surface area after the using of common endodontic devices ProTaper Universal and WaveOne systems. Methods: Forty ISO 15, 0.02 taper, S-shaped endo-training Blocks (Dentsply, Maillefer) were assigned in two groups (n = 20 for each group). For each block the initial working length (WL) was evaluated with a 10 K-files (Dentsply Maillefer), so the glide path was created with PathFile 1, 2 and 3 (Dentsply Maillefer) at the WL. After that, simulated canals in the group 1 were shaped with S1, S2, F1 and F2 at WL; while in group 2 it was used single-file WaveOne primary in reciprocating motion. After shaping, the resin blocks were analysed with Skyscan 1172 scanner (Skyscan, Kontich, Belgium) and then volumetrically at a source voltage of 65 kV and a source current of 153 uA. Results: No statistically differences (P > 0.05) have been found in terms of volume and surface area after the use of ProTaper Universal and WaveOne systems. Conclusions: Although, results from micro-CT analysis revealed that Wave One result in a decrease of volume and surface area of shaping than ProTaper Universal, differences are not statistically significant. PMID:26770376

  19. Diagnosing Hydrologic Flow Paths in Forest and Pasture Land Uses within the Panama Canal Watershed Using Simulated Rainfall and Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Ogden, F. L.; Mojica, A.; Kempema, E. W.; Briceno, J. C.; Regina, J. A.

    2014-12-01

    Hydrological processes in the humid tropics are poorly understood and an important topic when it comes to water management in the seasonal tropics. The Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project, seeks to understand these processes and quantify the long-term effects of different land cover and use across the Panama Canal Watershed. In this study we used an ARS-type rainfall simulator to apply rainfall rates up to 200 mm per hour over a 2m by 6m area on deep saprolitic soils in forest and pasture land covers. A salinity contrast added to the applied rainwater allowed observation of bulk flow paths and velocities in the subsurface. The observed effects of land cover and land use on hydrological response were striking. In the forest site, we were unable to produce surface runoff even after the application of 600 mm of rainfall in three hours, and observed flow in soils down to approximately 2 m depth, and no downslope macropore flow. In the pasture site, surface runoff was produced, and we measured the permeability of the area with applied rainfall. Observed flow paths were much shallower, less than 1 m depth, with significant macropore flow observed at downslope positions. We hypothesize that land use and land cover have significant impacts on flow paths as they affect creation, connectivity, and function of biologically created macropores in the soil.

  20. 21. 1934 aerial of Tempe Canal, Sections 19 and 30 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. 1934 aerial of Tempe Canal, Sections 19 and 30 (T1N R5E) and Sections 24 and 25 (T1N R4E) (top of page is north). The main canal enters the picture at upper right and curves out of picture at lower right. The Hayden Branch (thin dark line) runs from top of picture to the southwest, then curves to the west. The Western Branch enters picture running parallel to main canal, then angles off to southwest. Photographer: Unknown, 1934. Source: SRP Cartographic Drafting - Tempe Canal, South Side Salt River in Tempe, Mesa & Phoenix, Tempe, Maricopa County, AZ

  1. Alternative curved-boundary treatment for the lattice Boltzmann method and its application in simulation of flow and potential fields.

    PubMed

    Mohammadipoor, O R; Niazmand, H; Mirbozorgi, S A

    2014-01-01

    Since the lattice Boltzmann method originally carries out the simulations on the regular Cartesian lattices, curved boundaries are often approximated as a series of stair steps. The most commonly employed technique for resolving curved-boundary problems is extrapolating or interpolating macroscopic properties of boundary nodes. Previous investigations have indicated that using more than one equation for extrapolation or interpolation in boundary conditions potentially causes abrupt changes in particle distributions. Therefore, a curved-boundary treatment is introduced to improve computational accuracy of the conventional stair-shaped approximation used in lattice Boltzmann simulations by using a unified equation for extrapolation of macroscopic variables. This boundary condition is not limited to fluid flow and can be extended to potential fields. The proposed treatment is tested against several well-established problems and the solutions order of accuracy is evaluated. Numerical results show that the present treatment is of second-order accuracy and has reliable stability characteristics. PMID:24580362

  2. Evaluation of Forces Generated on Three Different Rotary File Systems in Apical Third of Root Canal using Finite Element Analysis

    PubMed Central

    Medha, Ashish; Patil, Suvarna; Hoshing, Upendra; Bandekar, Siddhesh

    2014-01-01

    Aim: Aim of the study is to evaluate the distribution of forces on the instrument in the apical 3rd of curved canal with three Nickel Titanium rotary systems. Methodology: Three brands of instruments (ProTaper Universal; DENTSPLY Maillefer, RevoS; MicroMega and Hyflex; Coltene-Whaledent, Allstetten, Switzerland) were scanned with the Laser assisted computerized scanner to produce a real-size, 3-dimensional (3-D) model for each. The stresses on the instrument during simulated shaping of a root canal were analyzed numerically by using a 3-D finite element package, taking into account the nonlinear mechanical behavior of the nickel-titanium material. Results: RevoS shows lowest values for force generation in the apical 3rd of canal as compared to Protaper which shows highest values, while Hyflex shows intermediate values for forces. Conclusion: With FE simulation of root canal shaping by 3 files, it was observed that different instrument designs would experience unequal degree of force generation in canal, as well as reaction torque from the root canal wall. PMID:24596786

  3. Accretion disc time lag distributions: applying CREAM to simulated AGN light curves

    NASA Astrophysics Data System (ADS)

    Starkey, D. A.; Horne, Keith; Villforth, C.

    2016-02-01

    Active galactic nuclei (AGN) vary in their brightness across all wavelengths. Moreover, longer wavelength ultraviolet-optical continuum light curves appear to be delayed with respect to shorter wavelength light curves. A simple way to model these delays is by assuming thermal reprocessing of a variable point source (a lamp post) by a blackbody accretion disc. We introduce a new method, CREAM (Continuum REprocessed AGN Markov Chain Monte Carlo), that models continuum variations using this lamp post model. The disc light curves lag the lamp post emission with a time delay distribution sensitive to the disc temperature-radius profile and inclination. We test CREAM's ability to recover both inclination and product of black hole mass and accretion rate {Mdot{M}}, and show that the code is also able to infer the shape of the driving light curve. CREAM is applied to synthetic light curves expected from 1000 s exposures of a 17th magnitude AGN with a 2-m telescope in Sloan g and i bands with Signal-to-Noise Ratio (SNR) of 500-900 depending on the filter and lunar phase. We also test CREAM on poorer quality g and i light curves with SNR = 100. We find in the high-SNR case that CREAM can recover the accretion disc inclination to within an uncertainty of 5° and an {Mdot{M}} to within 0.04 dex.

  4. Numerical simulation of the role of the utriculo-endolymphatic valve in the rotation-sensing capabilities of semicircular canals.

    PubMed

    Shen, Shuang; Sun, Xiuzhen; Yu, Shen; Liu, Yingxi; Su, Yingfeng; Zhao, Wei; Liu, Wenlong

    2016-06-14

    The utriculo-endolymphatic valve (UEV) has an uncertain function, but its opening and closure have been predicted to maintain a constant endolymphatic pressure within the semicircular canals (SCCs) and the utricle of the inner ear. Here, the study׳s aim was to examine the role of the UEV in regulating the capabilities of the 3 SCCs in sensing angular acceleration by using the finite element method. The results of the developed model showed endolymphatic flow and cupula displacement patterns in good agreement with previous experiments. Moreover, the open valve was predicted to permit endolymph exchange between the 2 parts of the membranous labyrinth during head rotation and, in comparison to the closed valve, to result in a reinforced endolymph flow in the utricle and an enhanced or weakened cupula deflection. Further, the model predicted an increase in the size of the orifice would result in greater endolymph exchange and thereby to a greater impact on cupula deflection. The model findings suggest the UEV plays a crucial role in the preservation of inner ear sensory function. PMID:27059257

  5. Simulation of ultrasonic inspection of curved composites using a hybrid semi-analytical/numerical code

    NASA Astrophysics Data System (ADS)

    Reverdy, Frédéric; Mahaut, Steve; Dominguez, Nicolas; Dubois, Philippe

    2015-03-01

    Carbon Fiber reinforced composites are increasingly used in structural parts in the aeronautics industry, as they allow to reduce the weight of aircrafts while maintaining high mechanical performances. However, such structures can be complicated to inspect due to their complex geometries and complex composite properties, leading to highly heterogeneous and anisotropic materials. Different potential damages and manufacturing flaws related to these parts are to be detected: porosities, ply waviness, delaminations after impact. Ultrasonic inspection, which is commonly used to test the full volume of composite panels, thus has to cope with both complex wave propagation (within anisotropic parts whose crystallographic orientation varies according to the layers structure) and flaw interaction (local distortion of plies such as ply waviness, small pores, structural noise due to periodicity patterns…). Developing NDT procedures for those parts therefore requires simulation tools to help for understanding those phenomena, and to optimize probes and techniques. Within the CIVA multi-techniques platform, CEA-LIST has developed semi-analytical tools for ultrasonic techniques, which have the advantages of high computational efficiency (fast calculations), but with limited range of application due to some hypothesis (for instance, homogenization approaches which don't allow to take account of structural noise). On the other hand, numerical methods such as finite element (FEM) or finite difference in time domain (FDTD) are more suitable to compute ultrasonic wave propagation and defect scattering in complex materials such as composite but require more computational efforts. Hybrid methods couple semi-analytical solutions and numerical computations in limited spatial domains to handle complex cases with high computation performances. In CIVA we have integrated a hybrid model that combines the semi-analytical methods developed at CEA to FDTD codes developed at Airbus Group

  6. Application of software for automated canal management (SacMan) to the WM lateral canal

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Simulation studies have demonstrated that automatic control of canals is more effective when feedforward scheduling, or routing of know demand changes, is combined with centralized, automatic, distant, downstream-water-level control. In practice, few canals use this approach. To help further develop...

  7. 25. Photocopy of photograph (original print at Gage Canal Company ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. Photocopy of photograph (original print at Gage Canal Company Office), photographer unknown, March 1954. VIEW OF THE GAGE IRRIGATION CANAL, CONCRETE 'COVERING COMPLETED & BACKFILLED TO WATERMAN AVENUE...CURVING TOWARD NO. 1 TUNNEL' - California Citrus Heritage Recording Project, Riverside, Riverside County, CA

  8. Molecular simulation of water along the liquid--vapor coexistence curve from 25 degree C to the critical point

    SciTech Connect

    de Pablo, J.J.; Prausnitz, J.M. Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA ); Strauch, H.J.; Cummings, P.T. )

    1990-11-15

    Previous work has shown that the simple point-charge (SPC) model can represent the experimental dielectric constant of water. In this work, we present results of Monte Carlo simulations of SPC water in the isothermal--isobaric (NPT) ensemble and in the Gibbs ensemble. Long-range intermolecular interactions are included in these simulations by use of the Ewald summation method. When Ewald sums are used, simulated, uniphase liquid potential energies are slightly lower (in absolute value) than those obtained for a simple spherical cutoff of the intermolecular potential. The coexistence curve of SPC water is obtained from 25 to 300{degree}C. The critical constants of SPC water are estimated by adjusting the coefficients of a Wegner expansion to fit the difference between simulated liquid and vapor orthobaric densities; the estimated critical temperature is 314 {degree}C and the estimated critical density is 0.27 g/cm{sup 3}.

  9. Evolution of the SCS curve number method and its applications to continuous runoff simulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Natural Resources Conservation Service (NRCS) [previously Soil Conservation Service (SCS)] developed the SCS runoff curve-number (CN) method for estimating direct runoff from storm rainfall. The NRCS uses the CN method for designing structures and for evaluating their effectiveness. Structural...

  10. Large-scale computational simulation for optimal design of curved piezoelectric actuator using composite material

    NASA Astrophysics Data System (ADS)

    Chung, Soon Wan; Hwang, In Seong; Kim, Seung Jo

    2004-07-01

    In this paper, the electromechanical displacements of curved piezoelectric actuators with laminated composite material are calculated using high performance computing technology, and the optimal configuration of composite curved actuator is proposed. To predict the pre-stress in the device due to the mismatch in coefficients of thermal expansion, carbon-epoxy and glass-epoxy as well as PZT ceramic are numerically modeled by using hexahedral solid elements. Because the modeling of these thin layers causes the numbers of degree of freedom to increase, large-scale structural analyses are performed through the PEGASUS supercomputer which is composed of 400 Intel Xeon CPUs. In the first stage, the curved shape of the actuator and the internal stress in each layer are obtained by the cured curvature analysis. Subsequently, the displacement due to the piezoelectric force by an applied voltage is also calculated and the performance of composite curved actuator is investigated by comparing the displacements according to the configuration of the actuator. To consider the finite deformation in the first stage and include the pre-stress in each layer in the second analysis stage, nonlinear finite element analyses will be carried out. The thickness and the elastic constants of laminated composite are chosen as design factors.

  11. Comparing the Light Curves of Simulated Type Ia Supernovae with Observations Using Data-driven Models

    NASA Astrophysics Data System (ADS)

    Diemer, Benedikt; Kessler, Richard; Graziani, Carlo; Jordan, George C., IV; Lamb, Donald Q.; Long, Min; van Rossum, Daniel R.

    2013-08-01

    We propose a robust, quantitative method to compare the synthetic light curves of a Type Ia supernova (SN Ia) explosion model with a large set of observed SNe Ia, and derive a figure of merit for the explosion model's agreement with observations. The synthetic light curves are fit with the data-driven model SALT2 which returns values for stretch, color, and magnitude at peak brightness, as well as a goodness-of-fit parameter. Each fit is performed multiple times with different choices of filter bands and epoch range in order to quantify the systematic uncertainty on the fitted parameters. We use a parametric population model for the distribution of observed SN Ia parameters from large surveys, and extend it to represent red, dim, and bright outliers found in a low-redshift SN Ia data set. We discuss the potential uncertainties of this population model and find it to be reliable given the current uncertainties on cosmological parameters. Using our population model, we assign each set of fitted parameters a likelihood of being observed in nature, and a figure of merit based on this likelihood. We define a second figure of merit based on the quality of the light curve fit, and combine the two measures into an overall figure of merit for each explosion model. We compute figures of merit for a variety of one-, two-, and three-dimensional explosion models and show that our evaluation method allows meaningful inferences across a wide range of light curve quality and fitted parameters.

  12. A Laboratory Simulation of Urban Runoff and the Potential for Hydrograph Prediction with Curve Numbers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urban drainages are mosaics of pervious and impervious surfaces, and prediction of runoff hydrology with a lumped modeling approach using the NRCS curve number may be appropriate. However, the prognostic capability of such a lumped approach is complicated by routing and connectivity amongst infiltra...

  13. An evidence-based laparoscopic simulation curriculum shortens the clinical learning curve and reduces surgical adverse events

    PubMed Central

    De Win, Gunter; Van Bruwaene, Siska; Kulkarni, Jyotsna; Van Calster, Ben; Aggarwal, Rajesh; Allen, Christopher; Lissens, Ann; De Ridder, Dirk; Miserez, Marc

    2016-01-01

    Background Surgical simulation is becoming increasingly important in surgical education. However, the method of simulation to be incorporated into a surgical curriculum is unclear. We compared the effectiveness of a proficiency-based preclinical simulation training in laparoscopy with conventional surgical training and conventional surgical training interspersed with standard simulation sessions. Materials and methods In this prospective single-blinded trial, 30 final-year medical students were randomized into three groups, which differed in the way they were exposed to laparoscopic simulation training. The control group received only clinical training during residency, whereas the interval group received clinical training in combination with simulation training. The Center for Surgical Technologies Preclinical Training Program (CST PTP) group received a proficiency-based preclinical simulation course during the final year of medical school but was not exposed to any extra simulation training during surgical residency. After 6 months of surgical residency, the influence on the learning curve while performing five consecutive human laparoscopic cholecystectomies was evaluated with motion tracking, time, Global Operative Assessment of Laparoscopic Skills, and number of adverse events (perforation of gall bladder, bleeding, and damage to liver tissue). Results The odds of adverse events were 4.5 (95% confidence interval 1.3–15.3) and 3.9 (95% confidence interval 1.5–9.7) times lower for the CST PTP group compared with the control and interval groups. For raw time, corrected time, movements, path length, and Global Operative Assessment of Laparoscopic Skills, the CST PTP trainees nearly always started at a better level and were never outperformed by the other trainees. Conclusion Proficiency-based preclinical training has a positive impact on the learning curve of a laparoscopic cholecystectomy and diminishes adverse events. PMID:27512343

  14. Flow Curve Determination at Large Plastic Strain Levels to Accurately Constitutive Equations of AHSS in Forming Simulation

    NASA Astrophysics Data System (ADS)

    Lemoine, X.; Sriram, S.; Kergen, R.

    2011-05-01

    ArcelorMittal continuously develops new steel grades (AHSS) with high performance for the automotive industry to improve the weight reduction and the passive safety. The wide market introduction of AHSS raises a new challenge for manufacturers in terms of material models in the prediction of forming—especially formability and springback. The relatively low uniform elongation, the high UTS and the low forming limit curve of these AHSS may cause difficulties in forming simulations. One of these difficulties is the consequence of the relatively low uniform elongation on the parameters identification of isotropic hardening model. Different experimental tests allow to reach large plastic strain levels (hydraulic bulge test, stack compression test, shear test…). After a description on how to determine the flow curve in these experimental tests, a comparison of the different flow curves is made for different steel grades. The ArcelorMittal identification protocol for hardening models is only based on stress-strain curves determined in uniaxial tension. Experimental tests where large plastic strain levels are reached are used to validate our identification protocol and to recommend some hardening models. Finally, the influence of isotropic hardening models and yield loci in forming prediction for AHSS steels will be presented.

  15. Micromagnetic simulations of demagnetization curves for single-phase nanocrystalline PrFeB magnet

    NASA Astrophysics Data System (ADS)

    Wang, X. P.; Zhao, S. F.; Han, X. F.

    2006-06-01

    The Gauss-Seidel projection method developed in [E. Weinan, X.P. Wang, SIAM J. Numer. Anal. 38 (2000) 1647-1665 and X.P. Wang, C.J. Garcia-Cervera, E. Weinan, J. Comp. Phys. 171 (2001) 357] is used to calculate the demagnetization curves for the single-phase nanocrystalline PrFeB magnet. It is observed that magnetic reversal for PrFeB magnet starts near the grain boundary where the angle between the external magnetic field and easy direction of the magnet can be as large as 90[ring operator]. We also calculated the demagnetization curves, coercivity [mu]0Hc and remanence Jr for different temperatures. The numerical results are consistent with the experimental observations.

  16. A model to simulate synthetic light curves of solar-like stars

    NASA Astrophysics Data System (ADS)

    Lanza, A. F.; Messina, S.; Pagano, I.; Rodonò, M.

    2006-01-01

    A model to synthesize stellar variability induced by solar-like magnetic activity is presented. It is based on the model introduced by Lanza et al. (2003) and Lanza, Rodonò& Pagano (2004) to fit the time variations of the solar bolometric and spectral irradiances. The model parameters are scaled in the case of solar-like stars in order to provide light curve amplitudes comparable with those observed for active stars with rotation periods ≤ 10 days. Simultaneous light curves in different optical passbands can be synthesized with the model in order to test, e.g., the methods that were recently proposed to detect planetary transit signatures in multiband photometric observations by space-borne telescopes.

  17. New approaches to the simulation of heat-capacity curves and phase diagrams of pseudobinary phospholipid mixtures.

    PubMed Central

    Johann, C; Garidel, P; Mennicke, L; Blume, A

    1996-01-01

    A simulation program using least-squares minimization was developed to calculate and fit heat capacity (cp) curves to experimental thermograms of dilute aqueous dispersions of phospholipid mixtures determined by high-sensitivity differential scanning calorimetry. We analyzed cp curves and phase diagrams of the pseudobinary aqueous lipid systems 1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol/ 1,2-dipalmitoyl-sn-glycero-3phosphatidylcholine (DMPG/DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphatidic acid/1, 2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DMPA/DPPC) at pH 7. The simulation of the cp curves is based on regular solution theory using two nonideality parameters rho g and rho l for symmetric nonideal mixing in the gel and the liquid-crystalline phases. The broadening of the cp curves owing to limited cooperativity is incorporated into the simulation by convolution of the cp curves calculated for infinite cooperativity with a broadening function derived from a simple two-state transition model with the cooperative unit size n = delta HVH/delta Hcal as an adjustable parameter. The nonideality parameters and the cooperative unit size turn out to be functions of composition. In a second step, phase diagrams were calculated and fitted to the experimental data by use of regular solution theory with four different model assumptions. The best fits were obtained with a four-parameter model based on nonsymmetric, nonideal mixing in both phases. The simulations of the phase diagrams show that the absolute values of the nonideality parameters can be changed in a certain range without large effects on the shape of the phase diagram as long as the difference of the nonideality parameters for rho g for the gel and rho l for the liquid-crystalline phase remains constant. The miscibility in DMPG/DPPC and DMPA/DPPC mixtures differs remarkably because, for DMPG/DPPC, delta rho = rho l -rho g is negative, whereas for DMPA/DPPC this difference is positive. For DMPA/DPPC, this

  18. Thermoluminescence curves simulation using genetic algorithm with factorial design

    NASA Astrophysics Data System (ADS)

    Popko, E. A.; Weinstein, I. A.

    2016-05-01

    The evolutionary approach is an effective optimization tool for numeric analysis of thermoluminescence (TL) processes to assess the microparameters of kinetic models and to determine its effects on the shape of TL peaks. In this paper, the procedure for tuning of genetic algorithm (GA) is presented. This approach is based on multifactorial experiment and allows choosing intrinsic mechanisms of evolutionary operators which provide the most efficient algorithm performance. The proposed method is tested by considering the “one trap-one recombination center” (OTOR) model as an example and advantages for approximation of experimental TL curves are shown.

  19. Root canal irrigants

    PubMed Central

    Kandaswamy, Deivanayagam; Venkateshbabu, Nagendrababu

    2010-01-01

    Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are discussed. We performed a Medline search for English-language papers published untill July 2010. The keywords used were ‘root canal irrigants’ and ‘endodontic irrigants.’ The reference lists of each article were manually checked for additional articles of relevance. PMID:21217955

  20. Simulation of tissue activity curves of 64Cu-ATSM for sub-target volume delineation in radiotherapy

    NASA Astrophysics Data System (ADS)

    Dalah, E.; Bradley, D.; Nisbet, A.

    2010-02-01

    There is much interest in positron emission tomography (PET) for measurements of regional tracer concentration in hypoxic tumour-bearing tissue, focusing on the need for accurate radiotherapy treatment planning. Generally, relevant data are taken over multiple time frames in the form of tissue activity curves (TACs), thus providing an indication of vasculature structure and geometry. This is a potential key in providing information on cellular perfusion and limited diffusion. A number of theoretical studies have attempted to describe tracer uptake in tissue cells in an effort to understand such complicated behaviour of cellular uptake and the mechanism of washout. More recently, a novel computerized reaction diffusion equation method was developed by Kelly and Brady (2006 A model to simulate tumour oxygenation and dynamic [18F]-FMISO PET data Phys. Med. Biol. 51 5859-73), where they managed to simulate the realistic dynamic TACs of 18F-FMISO. The model was developed over a multi-step process. Here we present a refinement to the work of Kelly and Brady, such that the model allows simulation of a realistic tissue activity curve (TAC) of any hypoxia selective PET tracer, in a single step process. In this work we show particular interest in simulating the TAC of perhaps the most promising hypoxia selective tracer, 64Cu-ATSM. In addition, we demonstrate its potential role in tumour sub-volume delineation for radiotherapy treatment planning. Simulation results have demonstrated the significant high contrast of imaging using ATSM, with a tumour to blood ratio ranging from 2.24 to 4.1.

  1. 56. CROSS SECTIONS OF CANAL AND TUNNELS. POWER CANAL, SALT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. CROSS SECTIONS OF CANAL AND TUNNELS. POWER CANAL, SALT RIVER RESERVOIR Courtesy of U.S.G.S., Reclamation Service - Roosevelt Power Canal & Diversion Dam, Parallels Salt River, Roosevelt, Gila County, AZ

  2. Bitter Root Irrigation district canal, looking east, typical section (canal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Bitter Root Irrigation district canal, looking east, typical section (canal full) - Bitter Root Irrigation Project, Bitter Root Irrigation Canal, Heading at Rock Creek Diversion Dam, West of U.S. Highway 93, Darby, Ravalli County, MT

  3. 9. BLACK RIVER CANAL CANAL (RIGHT), DISCHARGE GATE (BACKGROUND), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. BLACK RIVER CANAL - CANAL (RIGHT), DISCHARGE GATE (BACKGROUND), FARMER'S TURNOUT (LEFT), AND LATERAL NO. 14 (FOREGROUND). VIEW TO SOUTHEAST - Carlsbad Irrigation District, Black River Canal, 15 miles Southeast of Carlsbad near Malaga, Carlsbad, Eddy County, NM

  4. 8. BLACK RIVER CANAL LOOKING DOWN CANAL WITH LATERAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. BLACK RIVER CANAL - LOOKING DOWN CANAL WITH LATERAL TURNOUT NO. 1 ON THE RIGHT. VIEW TO THE SOUTHEAST - Carlsbad Irrigation District, Black River Canal, 15 miles Southeast of Carlsbad near Malaga, Carlsbad, Eddy County, NM

  5. 14. MAIN CANAL CANAL CHECKGATES, JUST BELOW DARK CANYON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. MAIN CANAL - CANAL CHECKGATES, JUST BELOW DARK CANYON SIPHON, VIEW TO NORTHEAST - Carlsbad Irrigation District, Main Canal, 4 miles North to 12 miles Southeast of Carlsbad, Carlsbad, Eddy County, NM

  6. Numerical simulations of magnetoacoustic-gravity waves in the solar coronal curved magnetic field lines structure

    NASA Astrophysics Data System (ADS)

    Jelínek, P.; Murawski, K.

    2013-09-01

    We present a two-dimensional (2D) magnetohydrodynamic (MHD) model of magneto-acoustic-gravity waves in the gravitationally stratified solar corona that is shaped by a realistic (VAL-C, Vernazza Avrett Loeser model C) temperature profile and curved magnetic field lines. These waves are triggered by an initial Gaussian pulse in the horizontal component of velocity, that is, launched either just below or above the transition region. The time-dependent ideal MHD equations are solved numerically with the use of the FLASH code. The numerical results reveal conversion of a horizontal flow into its vertical counterpart, oscillations of the transition region and vertical jets of cold plasma penetrating the solar corona. The wavelet analysis of the mass-density variations at a fixed detection point leads to the oscillation period of about 180 s, which corresponds to 3-min oscillations observed in solar active regions.

  7. Simulations of peristaltic slip-flow of hydromagnetic bio-fluid in a curved channel

    NASA Astrophysics Data System (ADS)

    Ali, N.; Javid, K.; Sajid, M.

    2016-02-01

    The influence of slip and magnetic field on transport characteristics of a bio-fluid are analyzed in a curved channel. The problem is modeled in curvilinear coordinate system under the assumption that the wavelength of the peristaltic wave is larger in magnitude compared to the width of the channel. The resulting nonlinear boundary value problem (BVP) is solved using an implicit finite difference technique (FDT). The flow velocity, pressure rise per wavelength and stream function are illustrated through graphs for various values of rheological and geometrical parameters of the problem. The study reveals that a thin boundary layer exists at the channel wall for strong magnetic field. Moreover, small values of Weissenberg number counteract the curvature and make the velocity profile symmetric. It is also observed that pressure rise per wavelength in pumping region increases (decreases) by increasing magnetic field, Weissenberg number and curvature of the channel (slip parameter).

  8. 6. O'BRIAN CANAL/DENVERHUDSON CANAL BIFURCATION POINT The O'Brian Canal is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. O'BRIAN CANAL/DENVER-HUDSON CANAL BIFURCATION POINT The O'Brian Canal is flowing to the left; the Denver-Hudson Canal is flowing to the right - O'Brian Canal, South Platte River Drainage Area Northest of Denver, Brighton, Adams County, CO

  9. Parameter Estimation and Confidence Regions in the Method of Light Curve Simulations for the Analysis of Power Density Spectra

    SciTech Connect

    Mueller, M.; Madejski, G.

    2009-05-20

    The Method of Light Curve Simulations is a tool that has been applied to X-ray monitoring observations of Active Galactic Nuclei (AGN) for the characterization of the Power Density Spectrum (PDS) of temporal variability and measurement of associated break frequencies (which appear to be an important diagnostic for the mass of the black hole in these systems as well as their accretion state). It relies on a model for the PDS that is fit to the observed data. The determination of confidence regions on the fitted model parameters is of particular importance, and we show how the Neyman construction based on distributions of estimates may be implemented in the context of light curve simulations. We believe that this procedure offers advantages over the method used in earlier reports on PDS model fits, not least with respect to the correspondence between the size of the confidence region and the precision with which the data constrain the values of the model parameters. We plan to apply the new procedure to existing RXTE and XMM observations of Seyfert I galaxies as well as RXTE observations of the Seyfert II galaxy NGC 4945.

  10. Simulations of incompressible Navier Stokes equations on curved surfaces using discrete exterior calculus

    NASA Astrophysics Data System (ADS)

    Samtaney, Ravi; Mohamed, Mamdouh; Hirani, Anil

    2015-11-01

    We present examples of numerical solutions of incompressible flow on 2D curved domains. The Navier-Stokes equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. A conservative discretization of Navier-Stokes equations on simplicial meshes is developed based on discrete exterior calculus (DEC). The discretization is then carried out by substituting the corresponding discrete operators based on the DEC framework. By construction, the method is conservative in that both the discrete divergence and circulation are conserved up to machine precision. The relative error in kinetic energy for inviscid flow test cases converges in a second order fashion with both the mesh size and the time step. Numerical examples include Taylor vortices on a sphere, Stuart vortices on a sphere, and flow past a cylinder on domains with varying curvature. Supported by the KAUST Office of Competitive Research Funds under Award No. URF/1/1401-01.

  11. Effect of motion cues during complex curved approach and landing tasks: A piloted simulation study

    NASA Technical Reports Server (NTRS)

    Scanlon, Charles H.

    1987-01-01

    A piloted simulation study was conducted to examine the effect of motion cues using a high fidelity simulation of commercial aircraft during the performance of complex approach and landing tasks in the Microwave Landing System (MLS) signal environment. The data from these tests indicate that in a high complexity MLS approach task with moderate turbulence and wind, the pilot uses motion cues to improve path tracking performance. No significant differences in tracking accuracy were noted for the low and medium complexity tasks, regardless of the presence of motion cues. Higher control input rates were measured for all tasks when motion was used. Pilot eye scan, as measured by instrument dwell time, was faster when motion cues were used regardless of the complexity of the approach tasks. Pilot comments indicated a preference for motion. With motion cues, pilots appeared to work harder in all levels of task complexity and to improve tracking performance in the most complex approach task.

  12. The Comparative Efficacy of Different Files in The Removal of Different Sealers in Simulated Root Canal Retreatment- An In-vitro Study

    PubMed Central

    Kanaparthy, Aruna

    2016-01-01

    Introduction Root canal treatment enjoys a high success rate all over the world and has saved billions of teeth from extraction. However, there are instances of failure, the main causes being insufficient cleaning and inadequate obturation. In such cases the most conservative treatment option would be non-surgical retreatment. It requires regaining access to the entire root canal system through removal of the original root canal filling thus permitting further cleaning and re- obturation. Removal of gutta-percha and sealer becomes a critical step to gain access to the root canal system, remove necrotic tissue debris, bacteria and infected dentin. Aim To compare and evaluate the efficacy of manual hand Hedstrom files and two rotary retreatment file systems ProTaper Universal retreatment files and MtwoR (retreatment) files in the removal of root canal filling material during root canal retreatment and the influence of the type of sealers zinc oxide eugenol and AH plus on the presence of remaining debris in the reinstrumented canals in the apical, middle and coronal third. Materials and Methods Sixty single rooted human premolar teeth were divided into 3 Groups of 20 teeth each Group I (20 Teeth): prepared using hand K Files, Group II (20 Teeth): prepared using ProTaper rotary system and Group III (20 Teeth): prepared using Mtwo rotary system. In Groups- IA, IIA, IIIA: (10 teeth each) Obturation was done using Zinc Oxide Eugenol sealer and gutta percha. In Groups- IB, IIB, IIIB: (10 teeth each) obturation was done with AH Plus sealer and gutta percha. All the teeth were subjected to retreatment. Groups IA and IB with Hedstrom files, Groups IIA and IIB with ProTaper retreatment files and for Groups IIIA and IIIB with Mtwo retreatment Files. The roots were longitudinally split and were observed under a stereomicroscope for remaining amount of filling material on the canal walls. Statistical analysis was done using One–way ANOVA (Analysis of variance) test and Tukey

  13. An In Vitro Comparative Study of Intracanal Fluid Motion and Wall Shear Stress Induced by Ultrasonic and Polymer Rotary Finishing Files in a Simulated Root Canal Model

    PubMed Central

    Koch, Jon; Borg, John; Mattson, Abby; Olsen, Kris; Bahcall, James

    2012-01-01

    Objective. This in vitro study compared the flow pattern and shear stress of an irrigant induced by ultrasonic and polymer rotary finishing file activation in an acrylic root canal model. Flow visualization analysis was performed using an acrylic canal filled with a mixture of distilled water and rheoscopic fluid. The ultrasonic and polymer rotary finishing file were separately tested in the canal and activated in a static position and in a cyclical axial motion (up and down). Particle movement in the fluid was captured using a high-speed digital camera and DaVis 7.1 software. The fluid shear stress analysis was performed using hot film anemometry. A hot-wire was placed in an acrylic root canal and the canal was filled with distilled water. The ultrasonic and polymer rotary finishing files were separately tested in a static position and in a cyclical axial motion. Positive needle irrigation was also tested separately for fluid shear stress. The induced wall shear stress was measured using LabVIEW 8.0 software. PMID:22461994

  14. Impact of sample geometry on the measurement of pressure-saturation curves: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Moura, M.; Fiorentino, E.-A.; Mâløy, K. J.; Schäfer, G.; Toussaint, R.

    2015-11-01

    In this paper, we study the influence of sample geometry on the measurement of pressure-saturation relationships, by analyzing the drainage of a two-phase flow from a quasi-2-D random porous medium. The medium is transparent, which allows for the direct visualization of the invasion pattern during flow, and is initially saturated with a viscous liquid (a dyed glycerol-water mix). As the pressure in the liquid is gradually reduced, air penetrates from an open inlet, displacing the liquid which leaves the system from an outlet on the opposite side. Pressure measurements and images of the flow are recorded and the pressure-saturation relationship is computed. We show that this relationship depends on the system size and aspect ratio. The effects of the system's boundaries on this relationship are measured experimentally and compared with simulations produced using an invasion percolation algorithm. The pressure build up at the beginning and end of the invasion process are particularly affected by the boundaries of the system whereas at the central part of the model (when the air front progresses far from these boundaries), the invasion happens at a statistically constant capillary pressure. These observations have led us to propose a much simplified pressure-saturation relationship, valid for systems that are large enough such that the invasion is not influenced by boundary effects. The properties of this relationship depend on the capillary pressure thresholds distribution, sample dimensions, and average pore connectivity and its applications may be of particular interest for simulations of two-phase flow in large porous media.

  15. Modelling the RXTE light curve of η Carinae from a 3D SPH simulation of its binary wind collision

    NASA Astrophysics Data System (ADS)

    Okazaki, A. T.; Owocki, S. P.; Russell, C. M. P.; Corcoran, M. F.

    2008-07-01

    The very massive star system η Carinae exhibits regular 5.54 yr (2024 d) period disruptive events in wavebands ranging from the radio to X-ray. There is a growing consensus that these events likely stem from periastron passage of an (as yet) unseen companion in a highly eccentric (e ~ 0.9) orbit. This Letter presents 3D smoothed particle hydrodynamics (SPH) simulations of the orbital variation of the binary wind-wind collision, and applies these to modelling the X-ray light curve observed by the Rossi X-ray Timing Explorer (RXTE). By providing a global 3D model of the phase variation of the density of the interacting winds, the simulations allow computation of the associated variation in X-ray absorption, presumed here to originate from near the apex of the wind-wind interaction cone. We find that the observed RXTE light curve can be readily fitted if the observer's line of sight is within this cone along the general direction of apastron. Specifically, the data are well fitted by an assumed inclination i = 45° for the orbit's polar axis, which is thus consistent with orbital angular momentum being along the inferred polar axis of the Homunculus nebula. The fits also constrain the position angle φ that an orbital-plane projection makes with the apastron side of the semimajor axis, strongly excluding positions φ < 9° along or to the retrograde side of the axis, with the best-fitting position given by φ = 27°. Overall the results demonstrate the utility of a fully 3D dynamical model for constraining the geometric and physical properties of this complex colliding wind binary system.

  16. CALCLENS: Curved-sky grAvitational Lensing for Cosmological Light conE simulatioNS

    NASA Astrophysics Data System (ADS)

    Becker, Matthew R.

    2012-10-01

    CALCLENS, written in C and employing widely available software libraries, efficiently computes weak gravitational lensing shear signals from large N-body light cone simulations over a curved sky. The algorithm properly accounts for the sky curvature and boundary conditions, is able to produce redshift-dependent shear signals including corrections to the Born approximation by using multiple-plane ray tracing, and properly computes the lensed images of source galaxies in the light cone. The key feature of this algorithm is a new, computationally efficient Poisson solver for the sphere that combines spherical harmonic transform and multgrid methods. As a result, large areas of sky (~10,000 square degrees) can be ray traced efficiently at high-resolution using only a few hundred cores on widely available machines. Coupled with realistic galaxy populations placed in large N-body light cone simulations, CALCLENS is ideally suited for the construction of synthetic weak lensing shear catalogs to be used to test for systematic effects in data analysis procedures for upcoming large-area sky surveys.

  17. Analysis of the terrestrial ion foreshock: 2D Full-Particle simulation of a curved supercritical shock

    NASA Astrophysics Data System (ADS)

    Lembege, B.; Savoini, P.; Stienlet, J.

    2013-05-01

    Two distinct ion populations backstreaming into the solar wind have been clearly evidenced by various space missions within the quasi-perpendicular region of the ion foreshock located upstream of the Earth's Bow shock (i.e. for 45° ≤ Theta_Bn ≤ 90°, where Theta_Bn is the angle between the shock normal and the upstream magnetostatic field): (i) field-aligned ion beams (« FAB ») characterized by a gyrotropic distribution, and (ii) gyro-phase bunched ions («GPB »), characterized by a NON gyrotropic distribution. The origin of these backstreaming ions has not been clearly identified and is presently analyzed with the help of 2D PIC simulation of a curved shock, where full curvature effects, time of flight effects and both electrons and ions dynamics are fully described within a self consistent approach. Present simulations evidence that these two populations can be effectively created directly by the shock front without invoking microinstabilities. The analysis of both individual and statistical ion trajectories evidences that: (i) two new parameters, namely the interaction time DT_inter and distance of penetration L_depth into the shock wave, play a key role and allow to discriminate these two populations. "GPB" population is characterized by a very short interaction time (DT_inter = 1 to 2 Tci) in comparison to the "FAB" population (DT_inter = 2 Tci to 10 Tci) which moves back and forth between the upstream edge of the shock front and the overshoot, where tci is the upstream ion gyroperiod. (ii) the importance of the injection angle (i.e. the angle between the normal of the shock front and the gyration velocity when ions reach the shock) to understand how the reflection process takes place. (iii) "FAB" population drifts along the curved shock front scanning a large Theta_Bn range from 90°. (iv) "GPB" population is embedded within the "FAB" population near the shock front which explains the difficulty to identify such a population in the experimental

  18. Simulation of dissolved oxygen and biochemical oxygen demand, Plantation Canal, Broward County, Florida with an evaluation of the QUAL-I model for use in south Florida

    USGS Publications Warehouse

    Russo, Thomas N.; McQuivey, Raul S.

    1975-01-01

    A mathematical model; QUAL-I, developed by the Texas Water Development Board, was evaluated as a management tool in predicting the spatial and temporal distribution of dissolved oxygen and biochemical oxygen demand in Plantation Canal. Predictions based on the QUAL-I model, which was verified only against midday summer-flow conditions, showed that improvement of quality of inflows from sewage treatment plants and use of at least 130 cubic feet per second of dilution water would improve water quality in the canal significantly. The model was not fully amenable to use on Plantation Canal because: (1) it did not consider photosynthetic production, nitrification, and benthic oxygen demand as sources and sinks of oxygen; (2) the model assumptions of complete mixing, transport, and steady state were not met; and (3) the data base was inadequate because it consisted of only one set of data for each case. However, it was felt that meaningful results could be obtained for some sets of conditions. (Woodard-USGS)

  19. In-vitro evaluation of the effect of canal curvature on adaptation of gutta-percha in canals obturated with HEROfill system by CBCT.

    PubMed

    Zarei, Mina; Talati, Ali; Mortazavi, Mohammad; Zarch, Hosein Hoseini; Javidi, Maryam; Bidokhty, Hamid Abbaszadeh

    2011-03-01

    A hermetic seal of the root canal space following canal preparation is important in endodontics. This study evaluated the effect of canal curve on adaptation of gutta-percha to dentinal walls of canals obturated using the Herofill system. For this in vitro study, 80 mesial roots of mature human first molars with length of 16 mm, curve between 5° and 45°, and no caries or resorption of the root surface were selected. A cone beam computed tomography system was used to evaluate the presence or absence of a gap in the samples. Photographs were taken in three sections: 2 mm above the curve, at the curve and 2 mm below the curve. The gap area was identified using Photoshop and AutoCAD software. Kruskal Wallis and Mann-Whitney tests were used to analyze the data mounted in a castcurve. There were significant differences between the two lateral condensation groups with various curves; roots with more curve had more gaps. When the Herofill and lateral condensation groups were compared without considering the sections and curve, there was a significant difference between these groups and the Herofill group had less gaps. The Herofill system is an alternative to the lateral condensation technique in severely curved canals. PMID:21467814

  20. Numerical simulation of peristaltic flow of a biorheological fluid with shear-dependent viscosity in a curved channel.

    PubMed

    Ali, N; Javid, K; Sajid, M; Anwar Bég, O

    2016-01-01

    Peristaltic motion of a non-Newtonian Carreau fluid is analyzed in a curved channel under the long wavelength and low Reynolds number assumptions, as a simulation of digestive transport. The flow regime is shown to be governed by a dimensionless fourth-order, nonlinear, ordinary differential equation subject to no-slip wall boundary conditions. A well-tested finite difference method based on an iterative scheme is employed for the solution of the boundary value problem. The important phenomena of pumping and trapping associated with the peristaltic motion are investigated for various values of rheological parameters of Carreau fluid and curvature of the channel. An increase in Weissenberg number is found to generate a small eddy in the vicinity of the lower wall of the channel, which is enhanced with further increase in Weissenberg number. For shear-thinning bio-fluids (power-law rheological index, n < 1) greater Weissenberg number displaces the maximum velocity toward the upper wall. For shear-thickening bio-fluids, the velocity amplitude is enhanced markedly with increasing Weissenberg number. PMID:26158210

  1. The Semicircular Canal Microphonic

    NASA Technical Reports Server (NTRS)

    Rabbitt, R. D.; Boyle, R.; Highstein, S. M.; Dalton, Bonnie P. (Technical Monitor)

    2002-01-01

    Present experiments were designed to quantify the alternating current (AC) component of the semicircular canal microphonic for angular motion stimulation as a function of stimulus frequency and amplitude. The oyster toadfish, Opsanus tau, was used as the experimental model. Calibrated mechanical indentation of the horizontal canal duct was used as a stimulus to generate hair-cell and afferent responses reproducing those present during head rotation. Sensitivity to polarization of the endolymph DC voltage re: perilymph was also investigated. Modulation of endolymph voltage was recorded using conventional glass electrodes and lock-in amplification over the frequency range 0.2-80 Hz. Access to the endolymph for inserting voltage recording and current passing electrodes was obtained by sectioning the anterior canal at its apex and isolating the cut ends in air. For sinusoidal stimulation below approx.10 Hz, the horizontal semicircular canal AC microphonic was nearly independent of stimulus frequency and equal to approximately 4 microV per micron indent (equivalent to approx. 1 microV per deg/s). A saturating nonlinearity decreasing the microphonic gain was present for stimuli exceeding approx.3 micron indent (approx. 12 deg/s angular velocity). The phase was not sensitive to the saturating nonlinearity. The microphonic exhibited a resonance near 30Hz consistent with basolateral current hair cell resonance observed previously in voltage-clamp records from semicircular canal hair cells. The magnitude and phase of the microphonic exhibited sensitivity to endolymphatic polarization consistent with electro-chemical reversal of hair cell transduction currents.

  2. Radiographic evaluation of the course and visibility of the mandibular canal

    PubMed Central

    Jung, Yun-Hoa

    2014-01-01

    Purpose This study was performed to investigate the course of the mandibular canal on panoramic radiography and the visibility of this canal on both panoramic radiography and cone-beam computed tomography (CBCT). Materials and Methods The study consisted of panoramic radiographs and CBCT images from 262 patients. The course of the mandibular canal, as seen in panoramic radiographs, was classified into four types: linear, elliptical, spoon-shaped, and turning curves. The visibility of this canal from the first to the third molar region was evaluated by visually determining whether the mandibular canal was clearly visible, probably visible, or invisible. The visibihlity of the canal on panoramic radiographs was compared with that on CBCT images. Results Elliptical curves were most frequently observed along the course of the mandibular canal. The percentage of clearly visible mandibular canals was the highest among the spoon-shaped curves and the lowest among the linear curves. On panoramic radiographs, invisible mandibular canals were found in 22.7% of the examined sites in the first molar region, 11.8% in the second molar region, and 1.3% in the third molar region. On CBCT cross-sectional images, the mandibular canal was invisible in 8.2% of the examined sites in the first molar region, 5.7% in the second molar region, and 0.2% in the third molar region. Conclusion The visibility of this canal was lower in the first molar region than in the third molar region. The mandibular canal presented better visibility on CBCT images than on panoramic radiographs. PMID:25473634

  3. 54. View of junction of unlined canal and lined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  4. 55. View of junction of unlined canal and lined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    55. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  5. Use of DNA melting simulation software for in silico diagnostic assay design: targeting regions with complex melting curves and confirmation by real-time PCR using intercalating dyes

    PubMed Central

    Rasmussen, John P; Saint, Christopher P; Monis, Paul T

    2007-01-01

    Background DNA melting curve analysis using double-stranded DNA-specific dyes such as SYTO9 produce complex and reproducible melting profiles, resulting in the detection of multiple melting peaks from a single amplicon and allowing the discrimination of different species. We compare the melting curves of several Naegleria and Cryptosporidium amplicons generated in vitro with in silico DNA melting simulations using the programs POLAND and MELTSIM., then test the utility of these programs for assay design using a genetic marker for toxin production in cyanobacteria. Results The SYTO9 melting curve profiles of three species of Naegleria and two species of Cryptosporidium were similar to POLAND and MELTSIM melting simulations, excepting some differences in the relative peak heights and the absolute melting temperatures of these peaks. MELTSIM and POLAND were used to screen sequences from a putative toxin gene in two different species of cyanobacteria and identify regions exhibiting diagnostic melting profiles. For one of these diagnostic regions the POLAND and MELTSIM melting simulations were observed to be different, with POLAND more accurately predicting the melting curve generated in vitro. Upon further investigation of this region with MELTSIM, inconsistencies between the melting simulation for forward and reverse complement sequences were observed. The assay was used to accurately type twenty seven cyanobacterial DNA extracts in vitro. Conclusion Whilst neither POLAND nor MELTSIM simulation programs were capable of exactly predicting DNA dissociation in the presence of an intercalating dye, the programs were successfully used as tools to identify regions where melting curve differences could be exploited for diagnostic melting curve assay design. Refinements in the simulation parameters would be required to account for the effect of the intercalating dye and salt concentrations used in real-time PCR. The agreement between the melting curve simulations for

  6. A novel approach in assessment of root canal curvature

    PubMed Central

    Sadeghi, Shiva; Poryousef, Vahideh

    2009-01-01

    Introduction: The purpose of this in vitro study was to introduce a new method to describe root canal curvatures and to assess the degree of curvature of human permanent mandibular teeth with curved root canals. Materials and Methods: One hundred and thirty five mesial root canals of mandibular first and second molar teeth were selected. Access cavities were prepared. After inserting a K-file size #10 into each canal, radiographs were taken. Canal curvature was determined by measuring the Schneider angle, canal access angle, as well as the canal radius, length, height and curvature starting distance on scanned radiographs using a computerized image processing system. Data was evaluated statistically using Pearson correlation. Results: The mean canal access angle (CAA) and Schneider angle (S) were 8.04◦ (3.46) and 19◦ (6.99), respectively. The Pearson correlation analysis found significant positive correlation between S and CAA (r=0.826, P<0.0001). Negative correlations were found between radius and length (r= –0.4, P<0.0001), radius and Schneider angle (r= –0.4, P<0.0001), radius and CAA (r= –0.24, P=0.004) and CAA and curvature starting distance (r= 0.4, P<0.0001). There was no correlation between height and distance (r=0.013, P=0.789), as well as CAA and height (r=0.654, P=0.001). Conclusion: Under the limitations of this study, the results indicated that the shape of root canal curvature can be more accurately described using two angles, Schneider in combination with Canal access angle. The related parameters included radius, length, distance and height of curvature. [Iranian Endodontic Journal 2009;4(4):131-4] PMID:24019833

  7. Ear canal cholesteatoma.

    PubMed

    Holt, J J

    1992-06-01

    Although cholesteatomas are more commonly found in the middle ear and the mastoid, the disease can occur in the external ear canal. All cases of ear canal cholesteatoma treated by the author were reviewed. There were nine ears in seven patients, who had an average age of 62 years. The lesions ranged in size from a few millimeters to extensive mastoid destruction. Smaller lesions can be managed by frequent cleaning as an office procedure. Larger lesions require surgery, either canaloplasty or mastoidectomy. The otolaryngologist should suspect this disease in the elderly. Microscopic examination of the ear with meticulous cleaning of all wax, especially in elderly patients, is most useful in detecting early disease. Frequent applications of mineral oil to the canal should be used in the management of the disease and to prevent recurrence. PMID:1376388

  8. 23. VIEW OF GRAND CANAL, SHOWING NEW ALIGNMENT CANAL ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. VIEW OF GRAND CANAL, SHOWING NEW ALIGNMENT CANAL ON RIGHT. THIS PHOTO WAS TAKEN FROM APPROXIMATELY THE SAME SPOT AS THE PREVIOUS PHOTOGRAPH (AZ-17-22). Photographer: Kevin Kreisel-Coons, May 1990 - Grand Canal, North side of Salt River, Tempe, Maricopa County, AZ

  9. 56. View of lined canal looking east toward unlined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. View of lined canal looking east toward unlined canal, from road bridge crossing lined canal. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  10. Frequency curves

    USGS Publications Warehouse

    Riggs, H.C.

    1968-01-01

    This manual describes graphical and mathematical procedures for preparing frequency curves from samples of hydrologic data. It also discusses the theory of frequency curves, compares advantages of graphical and mathematical fitting, suggests methods of describing graphically defined frequency curves analytically, and emphasizes the correct interpretations of a frequency curve.

  11. Love canal questions

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    The Environmental Protection Agency (EPA) conducted a 3-month monitoring study of the Love Canal area near Niagara Falls, N.Y., after the federal government pronounced that a potential health risk existed due to chemical waste dumps. In 1982 the Department of Health and Human Services (HHS) decided that the area was habitable, subject to implementation of effective safeguards against leakage from the canal and to cleaning up of the contaminants. Now, the Congressional Office of Technology Assessment (OTA) has announced that, with the information available, it is not possible to demonstrate with certainty that unsafe levels do not exist within the so-called “emergency declaration area” (EDA).

  12. The evolutionary genetics of canalization.

    PubMed

    Flatt, Thomas

    2005-09-01

    Evolutionary genetics has recently made enormous progress in understanding how genetic variation maps into phenotypic variation. However why some traits are phenotypically invariant despite apparent genetic and environmental changes has remained a major puzzle. In the 1940s, Conrad Hal Waddington coined the concept and term "canalization" to describe the robustness of phenotypes to perturbation; a similar concept was proposed by Waddington's contemporary Ivan Ivanovich Schmalhausen. This paper reviews what has been learned about canalization since Waddington. Canalization implies that a genotype's phenotype remains relatively invariant when individuals of a particular genotype are exposed to different environments (environmental canalization) or when individuals of the same single- or multilocus genotype differ in their genetic background (genetic canalization). Consequently, genetic canalization can be viewed as a particular kind of epistasis, and environmental canalization and phenotypic plasticity are two aspects of the same phenomenon. Canalization results in the accumulation of phenotypically cryptic genetic variation, which can be released after a "decanalizing" event. Thus, canalized genotypes maintain a cryptic potential for expressing particular phenotypes, which are only uncovered under particular decanalizing environmental or genetic conditions. Selection may then act on this newly released genetic variation. The accumulation of cryptic genetic variation by canalization may therefore increase evolvability at the population level by leading to phenotypic diversification under decanalizing conditions. On the other hand, under canalizing conditions, a major part of the segregating genetic variation may remain phenotypically cryptic; canalization may therefore, at least temporarily, constrain phenotypic evolution. Mechanistically, canalization can be understood in terms of transmission patterns, such as epistasis, pleiotropy, and genotype by environment

  13. Effectiveness of conventional syringe irrigation, vibringe, and passive ultrasonic irrigation performed with different irrigation regimes in removing triple antibiotic paste from simulated root canal irregularities

    PubMed Central

    Topçuoğlu, Hüseyin Sinan; Aktı, Ahmet; Topçuoğlu, Gamze; Düzgün, Salih; Ulusan, Özge; Akpek, Firdevs

    2016-01-01

    Background: This study evaluated the efficacy of a sonic device (Vibringe), passive ultrasonic irrigation (PUI), and conventional syringe irrigation (CSI) in the removal of triple antibiotic paste (TAP) from artificial standardized grooves in the apical and coronal thirds of a root canal. Materials and Methods: One-hundred eighteen root canals were prepared using the ProTaper system. The roots were split longitudinally, and a standardized groove was prepared in the apical and coronal parts of one segment. The grooves were filled with TAP, and the roots were reassembled. The roots were randomly divided into nine experimental groups and two control groups, according to the following irrigation methods: (1) CSI with sodium hypochlorite (NaOCl) + ethylenediaminetetraacetic acid (EDTA), (2) CSI/EDTA, (3) CSI/NaOCl, (4) PUI/NaOCl + EDTA, (5) PUI/EDTA, (6) PUI/NaOCl, (7) Vibringe/NaOCl + EDTA, (8) Vibringe/EDTA, and (9) Vibringe/NaOCl. The amount of remaining medicament was evaluated under a stereomicroscope. Results: In the apical third, Vibringe/NaOCl + EDTA and PUI/NaOCl + EDTA were superior to the other groups (P < 0.05); there was no significant difference between the other experimental groups (P > 0.05). In the coronal third, there was no significant difference between the experimental groups (P > 0.05). Conclusions: The use of the NaOCl/EDTA combination together with sonic or ultrasonic agitation improved the removal of TAP from the apical third. PMID:27563179

  14. Experimental depth dose curves of a 67.5 MeV proton beam for benchmarking and validation of Monte Carlo simulation

    PubMed Central

    Faddegon, Bruce A.; Shin, Jungwook; Castenada, Carlos M.; Ramos-Méndez, José; Daftari, Inder K.

    2015-01-01

    Purpose: To measure depth dose curves for a 67.5 ± 0.1 MeV proton beam for benchmarking and validation of Monte Carlo simulation. Methods: Depth dose curves were measured in 2 beam lines. Protons in the raw beam line traversed a Ta scattering foil, 0.1016 or 0.381 mm thick, a secondary emission monitor comprised of thin Al foils, and a thin Kapton exit window. The beam energy and peak width and the composition and density of material traversed by the beam were known with sufficient accuracy to permit benchmark quality measurements. Diodes for charged particle dosimetry from two different manufacturers were used to scan the depth dose curves with 0.003 mm depth reproducibility in a water tank placed 300 mm from the exit window. Depth in water was determined with an uncertainty of 0.15 mm, including the uncertainty in the water equivalent depth of the sensitive volume of the detector. Parallel-plate chambers were used to verify the accuracy of the shape of the Bragg peak and the peak-to-plateau ratio measured with the diodes. The uncertainty in the measured peak-to-plateau ratio was 4%. Depth dose curves were also measured with a diode for a Bragg curve and treatment beam spread out Bragg peak (SOBP) on the beam line used for eye treatment. The measurements were compared to Monte Carlo simulation done with geant4 using topas. Results: The 80% dose at the distal side of the Bragg peak for the thinner foil was at 37.47 ± 0.11 mm (average of measurement with diodes from two different manufacturers), compared to the simulated value of 37.20 mm. The 80% dose for the thicker foil was at 35.08 ± 0.15 mm, compared to the simulated value of 34.90 mm. The measured peak-to-plateau ratio was within one standard deviation experimental uncertainty of the simulated result for the thinnest foil and two standard deviations for the thickest foil. It was necessary to include the collimation in the simulation, which had a more pronounced effect on the peak-to-plateau ratio for the

  15. A Molecular Dynamics simulation of Hugoniot curves of HMX using ReaxFF and its application in SPH modeling of macroscale terminal effects

    NASA Astrophysics Data System (ADS)

    Liu, Gui-Rong; Wang, Gangyu; Peng, Qing; de, Suvranu

    2015-06-01

    HMX is a widely used high explosive. Hugoniot curve is a valuable tool for analyzing the equations of state, and is of importance for all energetic materials including HMX. The Hugoniot curves serve as one of the key character in continuum modeling of high explosives. It can be obtained from experimental measurements, and recently also from computational studies. In this study, the Hugoniot curve of HMX is calculated using a multi-scale shock technique via Molecular Dynamics (MD) simulations, where the reactive force field ReaxFF is obtained from Quantum Mechanics calculations and tailored for HMX. It is found that our MD Hugoniot curve of HMX from the optimized ReaxFF potential agree well with experiments. The MD Hugoniot curve of HMX is also incorporated in our in-house Smoothed Particle Hydrodynamics (SPH) code for the modeling of the macro-scale explosive behaviors of HMX explosives and HMX cased in a 3D cylinder. The authors would like to acknowledge the generous financial support from the Defense Threat Reduction Agency (DTRA) Grant HDTRA1-13-1-0025.

  16. Curved Beam Computed Tomography based Structural Rigidity Analysis of Bones with Simulated Lytic Defect: A Comparative Study with Finite Element Analysis.

    PubMed

    Oftadeh, R; Karimi, Z; Villa-Camacho, J; Tanck, E; Verdonschot, N; Goebel, R; Snyder, B D; Hashemi, H N; Vaziri, A; Nazarian, A

    2016-01-01

    In this paper, a CT based structural rigidity analysis (CTRA) method that incorporates bone intrinsic local curvature is introduced to assess the compressive failure load of human femur with simulated lytic defects. The proposed CTRA is based on a three dimensional curved beam theory to obtain critical stresses within the human femur model. To test the proposed method, ten human cadaveric femurs with and without simulated defects were mechanically tested under axial compression to failure. Quantitative computed tomography images were acquired from the samples, and CTRA and finite element analysis were performed to obtain the failure load as well as rigidities in both straight and curved cross sections. Experimental results were compared to the results obtained from FEA and CTRA. The failure loads predicated by curved beam CTRA and FEA are in agreement with experimental results. The results also show that the proposed method is an efficient and reliable method to find both the location and magnitude of failure load. Moreover, the results show that the proposed curved CTRA outperforms the regular straight beam CTRA, which ignores the bone intrinsic curvature and can be used as a useful tool in clinical practices. PMID:27585495

  17. Curved Beam Computed Tomography based Structural Rigidity Analysis of Bones with Simulated Lytic Defect: A Comparative Study with Finite Element Analysis

    PubMed Central

    Oftadeh, R.; Karimi, Z.; Villa-Camacho, J.; Tanck, E.; Verdonschot, N.; Goebel, R.; Snyder, B. D.; Hashemi, H. N.; Vaziri, A.; Nazarian, A.

    2016-01-01

    In this paper, a CT based structural rigidity analysis (CTRA) method that incorporates bone intrinsic local curvature is introduced to assess the compressive failure load of human femur with simulated lytic defects. The proposed CTRA is based on a three dimensional curved beam theory to obtain critical stresses within the human femur model. To test the proposed method, ten human cadaveric femurs with and without simulated defects were mechanically tested under axial compression to failure. Quantitative computed tomography images were acquired from the samples, and CTRA and finite element analysis were performed to obtain the failure load as well as rigidities in both straight and curved cross sections. Experimental results were compared to the results obtained from FEA and CTRA. The failure loads predicated by curved beam CTRA and FEA are in agreement with experimental results. The results also show that the proposed method is an efficient and reliable method to find both the location and magnitude of failure load. Moreover, the results show that the proposed curved CTRA outperforms the regular straight beam CTRA, which ignores the bone intrinsic curvature and can be used as a useful tool in clinical practices. PMID:27585495

  18. Numerical simulations of rubber networks at moderate to high tensile strains using a purely enthalpic force extension curve for individual chains

    NASA Astrophysics Data System (ADS)

    Hanson, David E.

    2009-12-01

    We report the results of numerical simulations of random, three-dimensional, periodic, tetrafunctional networks in response to a volume-preserving tensile strain. For the intranode force, we use a polynomial fit to a purely enthalpic ab initio force extension curve for extended polyisoprene. The simulation includes a relaxation procedure to minimize the node forces and enforces chain rupture when the extension of a network chain reaches the ab initio rupture strain. For the reasonable assumption that the distribution of network chain lengths is Gaussian, we find that the calculated snap-back velocity, temperature increase due to chain ruptures and predicted tensile stress versus strain curve are consistent with experimental data in the moderate to high extension regime. Our results show that a perfect tetrafunctional polyisoprene network is extremely robust, capable of supporting tensile stresses at least a factor of 10 greater than what is observed experimentally.

  19. Numerical simulations of rubber networks at moderate to high tensile strains using a purely enthalpic force extension curve for individual chains

    SciTech Connect

    Hanson, David Edward

    2009-01-01

    We report the results of numerical simulations of random, three-dimensional, periodic, tetrafunctional networks in response to a volume-preserving tensile strain. For the intranode force, we use a polynomial fit to a purely enthalpic ab initio force extension curve for extended polyisoprene. The simulation includes a relaxation procedure to minimize the node forces and enforces chain rupture when the extension of a network chain reaches the ab initio rupture strain. For the reasonable assumption that the distribution of network chain lengths is Gaussian, we find that the calculated snap-back velocity, temperature increase due to chain ruptures and predicted tensile stress versus strain curve are consistent with experimental data in the moderate to high extension regime. Our results show that a perfect tetrafunctional polyisoprene network is extremely robust, capable of supporting tensile stresses at least a factor of 10 greater than what is observed experimentally.

  20. MODELING HIGH-ENERGY LIGHT CURVES OF THE PSR B1259-63/LS 2883 BINARY BASED ON 3D SPH SIMULATIONS

    SciTech Connect

    Takata, J.; Okazaki, A. T.; Nagataki, S.; Lee, S.-H.; Naito, T.; Kawachi, A.; Mori, M.; Hayasaki, K.; Yamaguchi, M. S.; Owocki, S. P.

    2012-05-01

    Temporal changes of X-ray to very high energy gamma-ray emissions from the pulsar-Be-star binary PSR B1259-63/LS 2883 are studied based on three-dimensional smoothed particle hydrodynamic simulations of pulsar wind interaction with Be-disk and wind. We focus on the periastron passage of the binary and calculate the variation of the synchrotron and inverse-Compton emissions using the simulated shock geometry and pressure distribution of the pulsar wind. The characteristic double-peaked X-ray light curve from observations is reproduced by our simulation under a dense Be-disk condition (base density {approx}10{sup -9} g cm{sup -3}). We interpret the pre- and post-periastron peaks as being due to a significant increase in the conversion efficiency from pulsar spin-down power to the shock-accelerated particle energy at orbital phases when the pulsar crosses the disk before periastron passage, and when the pulsar wind creates a cavity in the disk gas after periastron passage, respectively. On the contrary, in the model TeV light curve, which also shows a double-peak feature, the first peak appears around the periastron phase. The possible effects of cooling processes on the TeV light curve are briefly discussed.

  1. Multicolor Light Curve Simulations of Population III Core-Collapse Supernovae: From Shock Breakout to 56Co Decay

    NASA Astrophysics Data System (ADS)

    Tolstov, Alexey; Nomoto, Ken’ichi; Tominaga, Nozomu; Ishigaki, Miho N.; Blinnikov, Sergey; Suzuki, Tomoharu

    2016-04-01

    The properties of the first generation of stars and their supernova (SN) explosions remain unknown due to the lack of actual observations. Recently, many transient surveys have been conducted and the feasibility of detecting supernovae (SNe) of Pop III stars is growing. In this paper, we study the multicolor light curves for a number of metal-free core-collapse SN models (25–100 {M}ȯ ) to determine the indicators for the detection and identification of first generation SNe. We use mixing-fallback supernova explosion models that explain the observed abundance patterns of metal-poor stars. Numerical calculations of the multicolor light curves are performed using the multigroup radiation hydrodynamic code stella. The calculated light curves of metal-free SNe are compared with non-zero-metallicity models and several observed SNe. We have found that the shock breakout characteristics, the evolution of the photosphere’s velocity, the luminosity, and the duration and color evolution of the plateau, that is, all of the SN phases from shock breakout to 56Co decay, are helpful for estimating the parameters of the SN progenitor: the mass, the radius, the explosion energy, and the metallicity. We conclude that the multicolor light curves could potentially be used to identify first-generation SNe in current (Subaru/HSC) and future transient surveys (LSST, James Webb Space Telescope). They are also suitable for identifying low-metallicity SNe in the nearby universe (PTF, Pan-STARRS, Gaia).

  2. Leiomyoma of External Auditory Canal.

    PubMed

    George, M V; Puthiyapurayil, Jamsheeda

    2016-09-01

    This article reports a case of piloleiomyoma of external auditory canal, which is the 7th case of leiomyoma of the external auditory canal being reported and the 2nd case of leiomyoma arising from arrectores pilorum muscles, all the other five cases were angioleiomyomas, arising from blood vessels. A 52 years old male presented with a mass in the right external auditory canal and decreased hearing of 6 months duration. Tumor excision done by end aural approach. Histopathological examination report was leiomyoma. It is extremely rare for leiomyoma to occur in the external auditory canal because of the non-availability of smooth muscles in the external canal. So it should be considered as a very rare differential diagnosis for any tumor or polyp in the ear canal. PMID:27508144

  3. Modeling and measurement of root canal using stereo digital radiography

    NASA Astrophysics Data System (ADS)

    Analoui, Mostafa; Krisnamurthy, Satthya; Brown, Cecil

    2000-04-01

    Determining root canal length is a crucial step in success of root canal treatment. Root canal length is commonly estimated based on pre-operation intraoral radiography. 2D depiction of a 3D object is the primary source of error in this approach. Techniques based on impedance measurement are more accurate than radiographic approaches, but do not offer a method for depicting the shape of canal. In this study, we investigated a stererotactic approach for modeling and measurement of root canal of human dentition. A weakly perspective model approximated the projectional geometry. A series of computer-simulated objects was used to test accuracy of this model as the first step. The, to assess the clinical viability of such an approach, endodontic files inserted in the root canal phantoms were fixed on an adjustable platform between a radiographic cone and an image receptor. Parameters of projection matrix were computed based on the relative positions of image receptors, focal spot, and test objects. Rotating the specimen platform from 0 to 980 degrees at 5-degree intervals set relative angulations for stereo images. Root canal is defined as the intersection of two surfaces defined by each projection. Computation of error for length measurement indicates that for angulations greater than 40 degrees the error is within clinically acceptable ranges.

  4. Distributed control at Love canal

    SciTech Connect

    McPherson, G.; Rider, G.J.; Sadowski, B.; Moore, M.

    1994-09-01

    Love Canal is known worldwide as the site of one of the worst non-nuclear environmental disasters in modern history. For 12 years, a Niagara Falls, New York chemical company used the canal bed as a chemical dump. This article discusses the computerized control of equipment used to remove the toxic materials from the ground under Love Canal, and how the minimization of maintenance is reducing maintenance costs and increasing operator safety.

  5. Nasopalatine canal cyst: often missed

    PubMed Central

    Srivastava, Saurabh; Misra, Neeta; Agarwal, Rashmi; Pandey, Praveen

    2013-01-01

    Nasopalatine canal cyst may occur within the nasopalatine canal or in the soft tissues of the palate, at the opening of the canal, where it is called the ‘cyst of the palatine papilla’. These are normally asymptomatic, constituting casual radiological findings. We present a case report of a male patient with infected nasopalatine canal cyst seen clinically as swelling over palate. Radiographic interpretation should be thoroughly performed for maxillary anterior region and any occlusal radiograph in routine radiography to screen this entity and must be distinguished from other maxillary anterior radiolucencies by the clinician. PMID:23536642

  6. ASTER Suez Canal

    NASA Technical Reports Server (NTRS)

    2000-01-01

    One of the most important waterways in the world, the Suez Canal runs north to south across the Isthmus of Suez in northeastern Egypt. This image of the canal covers an area 36 kilometers (22 miles) wide and 60 kilometers (47 miles) long in three bands of the reflected visible and infrared wavelength region. It shows the northern part of the canal, with the Mediterranean Sea just visible in the upper right corner. The Suez Canal connects the Mediterranean Sea with the Gulf of Suez, an arm of the Red Sea. The artificial canal provides an important shortcut for ships operating between both European and American ports and ports located in southern Asia, eastern Africa, and Oceania. With a length of about 195 kilometers (121 miles) and a minimum channel width of 60 meters (197 feet), the Suez Canal is able to accommodate ships as large as 150,000 tons fully loaded. Because no locks interrupt traffic on this sea level waterway, the transit time only averages about 15 hours. ASTER acquired this scene on May 19, 2000.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high-resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five

  7. 15. ROUTE OF CANAL NORTHWEST OF THE DILLON CEMETERY. CANAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. ROUTE OF CANAL NORTHWEST OF THE DILLON CEMETERY. CANAL PASSES BELOW HILLSIDE IN FOREGROUND, THROUGH THE LOWER EDGE OF THE TREES ON LEFT, ON FAR SIDE OF SMALL VALLEY JUST RIGHT OF CENTER, AND AROUND THE PROMINENT POINT ON THE RIGHT. VIEW IS TO THE EAST-SOUTHEAST. - Snake River Ditch, Headgate on north bank of Snake River, Dillon, Summit County, CO

  8. REACTOR CANAL AFTER IT HAS BEEN TILED. WATER FILLS CANAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REACTOR CANAL AFTER IT HAS BEEN TILED. WATER FILLS CANAL PART WAY TO TOP. CAMERA FACES WEST. INL NEGATIVE NO. 3993-A. Unknown Photographer, 12/28/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  9. A diffuse-interface immersed-boundary method for two-dimensional simulation of flows with moving contact lines on curved substrates

    NASA Astrophysics Data System (ADS)

    Liu, Hao-Ran; Ding, Hang

    2015-08-01

    We propose an approach to simulate flows with moving contact lines (MCLs) on curved substrates on a Cartesian mesh. The approach combines an immersed boundary method with a three-component diffuse-interface model and a characteristic MCL model. The immersed boundary method is able to accurately enforce the no-slip boundary condition at the solid surface, thereby circumventing the penetration of the gas and the liquid into the solid by convection. On the other hand, using the three-component diffuse-interface model can prevent the gas and liquid from infiltrating into the solid substrate through the diffusive fluxes during the interface evolution. A combination of these two methods appears to effectively conserve the mass of the phases in the computation. The characteristic MCL model not only allows the contact lines to move on the curved boundaries, but makes the gas-liquid interface to intersect the solid object at an angle in consistence with the prescribed contact angle, even with the variation of surface tangent at the solid substrate. We examine the performance of the approach through a variety of numerical experiments. The mass conservation and interface shapes at equilibrium were tested through the simulation of drop spreading on a circular cylinder. The dynamic behaviors of moving contact lines were validated by simulating the droplet spreading on a flat substrate, and we compared the numerical results against theoretical predictions and previous experimental observations. The method was also applied to the simulations of flows with curved boundaries and moving contact lines, such as drop impact on a sphere and water entry of a sphere. Finally, we studied the penetration process of a two-dimensional drop into a porous substrate that consists of a cluster of circular cylinders.

  10. Controversy at Love Canal.

    PubMed

    Paigen, B

    1982-06-01

    A cancer researcher reviews the events surrounding the toxic waste contamination at Love Canal with emphasis on the political nature of the controversy about its health impact. Antagonism between the community and the New York State Department of Health was fueled by several factors: the state's awareness that it gained from delay in investigation, disagreement on health problems to be studied, control over the information gathering process, silencing of opposition opinion, and the violation of norms of scientific behavior. The author calls for the establishment of standards of ethical behavior for scientists in such situations, standards for conflict resolution, and means of appeal for those injured. PMID:7107238

  11. Combined Monte Carlo and path-integral method for simulated library of time-resolved reflectance curves from layered tissue models

    NASA Astrophysics Data System (ADS)

    Wilson, Robert H.; Vishwanath, Karthik; Mycek, Mary-Ann

    2009-02-01

    Monte Carlo (MC) simulations are considered the "gold standard" for mathematical description of photon transport in tissue, but they can require large computation times. Therefore, it is important to develop simple and efficient methods for accelerating MC simulations, especially when a large "library" of related simulations is needed. A semi-analytical method involving MC simulations and a path-integral (PI) based scaling technique generated time-resolved reflectance curves from layered tissue models. First, a zero-absorption MC simulation was run for a tissue model with fixed scattering properties in each layer. Then, a closed-form expression for the average classical path of a photon in tissue was used to determine the percentage of time that the photon spent in each layer, to create a weighted Beer-Lambert factor to scale the time-resolved reflectance of the simulated zero-absorption tissue model. This method is a unique alternative to other scaling techniques in that it does not require the path length or number of collisions of each photon to be stored during the initial simulation. Effects of various layer thicknesses and absorption and scattering coefficients on the accuracy of the method will be discussed.

  12. Can carbon surface oxidation shift the pore size distribution curve calculated from Ar, N2 and CO2 adsorption isotherms? Simulation results for a realistic carbon model

    NASA Astrophysics Data System (ADS)

    Furmaniak, Sylwester; Terzyk, Artur P.; Gauden, Piotr A.; Harris, Peter J. F.; Kowalczyk, Piotr

    2009-08-01

    Using the virtual porous carbon model proposed by Harris et al, we study the effect of carbon surface oxidation on the pore size distribution (PSD) curve determined from simulated Ar, N2 and CO2 isotherms. It is assumed that surface oxidation is not destructive for the carbon skeleton, and that all pores are accessible for studied molecules (i.e., only the effect of the change of surface chemical composition is studied). The results obtained show two important things, i.e., oxidation of the carbon surface very slightly changes the absolute porosity (calculated from the geometric method of Bhattacharya and Gubbins (BG)); however, PSD curves calculated from simulated isotherms are to a greater or lesser extent affected by the presence of surface oxides. The most reliable results are obtained from Ar adsorption data. Not only is adsorption of this adsorbate practically independent from the presence of surface oxides, but, more importantly, for this molecule one can apply the slit-like model of pores as the first approach to recover the average pore diameter of a real carbon structure. For nitrogen, the effect of carbon surface chemical composition is observed due to the quadrupole moment of this molecule, and this effect shifts the PSD curves compared to Ar. The largest differences are seen for CO2, and it is clearly demonstrated that the PSD curves obtained from adsorption isotherms of this molecule contain artificial peaks and the average pore diameter is strongly influenced by the presence of electrostatic adsorbate-adsorbate as well as adsorbate-adsorbent interactions.

  13. Can carbon surface oxidation shift the pore size distribution curve calculated from Ar, N(2) and CO(2) adsorption isotherms? Simulation results for a realistic carbon model.

    PubMed

    Furmaniak, Sylwester; Terzyk, Artur P; Gauden, Piotr A; Harris, Peter J F; Kowalczyk, Piotr

    2009-08-01

    Using the virtual porous carbon model proposed by Harris et al, we study the effect of carbon surface oxidation on the pore size distribution (PSD) curve determined from simulated Ar, N(2) and CO(2) isotherms. It is assumed that surface oxidation is not destructive for the carbon skeleton, and that all pores are accessible for studied molecules (i.e., only the effect of the change of surface chemical composition is studied). The results obtained show two important things, i.e., oxidation of the carbon surface very slightly changes the absolute porosity (calculated from the geometric method of Bhattacharya and Gubbins (BG)); however, PSD curves calculated from simulated isotherms are to a greater or lesser extent affected by the presence of surface oxides. The most reliable results are obtained from Ar adsorption data. Not only is adsorption of this adsorbate practically independent from the presence of surface oxides, but, more importantly, for this molecule one can apply the slit-like model of pores as the first approach to recover the average pore diameter of a real carbon structure. For nitrogen, the effect of carbon surface chemical composition is observed due to the quadrupole moment of this molecule, and this effect shifts the PSD curves compared to Ar. The largest differences are seen for CO(2), and it is clearly demonstrated that the PSD curves obtained from adsorption isotherms of this molecule contain artificial peaks and the average pore diameter is strongly influenced by the presence of electrostatic adsorbate-adsorbate as well as adsorbate-adsorbent interactions. PMID:21828590

  14. Derivation of a Provisional, Age-dependent, AIS2+ Thoracic Risk Curve for the THOR50 Test Dummy via Integration of NASS Cases, PMHS Tests, and Simulation Data.

    PubMed

    Laituri, Tony R; Henry, Scott; El-Jawahri, Raed; Muralidharan, Nirmal; Li, Guosong; Nutt, Marvin

    2015-11-01

    A provisional, age-dependent thoracic risk equation (or, "risk curve") was derived to estimate moderate-to-fatal injury potential (AIS2+), pertaining to men with responses gaged by the advanced mid-sized male test dummy (THOR50). The derivation involved two distinct data sources: cases from real-world crashes (e.g., the National Automotive Sampling System, NASS) and cases involving post-mortem human subjects (PMHS). The derivation was therefore more comprehensive, as NASS datasets generally skew towards younger occupants, and PMHS datasets generally skew towards older occupants. However, known deficiencies had to be addressed (e.g., the NASS cases had unknown stimuli, and the PMHS tests required transformation of known stimuli into THOR50 stimuli). For the NASS portion of the analysis, chest-injury outcomes for adult male drivers about the size of the THOR50 were collected from real-world, 11-1 o'clock, full-engagement frontal crashes (NASS, 1995-2012 calendar years, 1985-2012 model-year light passenger vehicles). The screening for THOR50-sized men involved application of a set of newly-derived "correction" equations for self-reported height and weight data in NASS. Finally, THOR50 stimuli were estimated via field simulations involving attendant representative restraint systems, and those stimuli were then assigned to corresponding NASS cases (n=508). For the PMHS portion of the analysis, simulation-based closure equations were developed to convert PMHS stimuli into THOR50 stimuli. Specifically, closure equations were derived for the four measurement locations on the THOR50 chest by cross-correlating the results of matched-loading simulations between the test dummy and the age-dependent, Ford Human Body Model. The resulting closure equations demonstrated acceptable fidelity (n=75 matched simulations, R2≥0.99). These equations were applied to the THOR50-sized men in the PMHS dataset (n=20). The NASS and PMHS datasets were combined and subjected to survival

  15. Laboratory Simulation of Urban Runoff and Estimation of Runoff Hydrographs with Experimental Curve Numbers Implemented in USEPA SWMM

    EPA Science Inventory

    The prognostic capabilities of a lumped hydrologic modeling approach may be complicated by routing and connectivity among infiltrative and impervious surfaces. We used artificial rainfall to generate runoff from impervious and bare soil boxes arranged in series to simulate differ...

  16. Root Canal Therapy of a Mandibular First Molar with Five Root Canals: A Case Report

    PubMed Central

    Reyhani, Mohammad Frough; Rahimi, Saeed; Shahi, Shahriar

    2007-01-01

    A mandibular first molar requiring root canal therapy was found with five canals, three mesial canals, and two distal canals. Initially, four canals (mesiobuccal, mesiolingual, distobuccal, and distolingual) were identified. The mesiobuccal and mesiolingual canals were found in their normal locations, and a fifth canal was noted between these two. This case demonstrates a rare anatomical configuration and supplements previous reports of the existence of such configurations in mandibular first molars. PMID:24298291

  17. 173. CANAL TENDER OPERATING LOCK MACHINERY ON THE MORRIS CANAL. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    173. CANAL TENDER OPERATING LOCK MACHINERY ON THE MORRIS CANAL. AS THE LOCK TENDER TURNS THE CRANK, A SMALL COGGED WHEEL (PINION) ON THE CRANK TURNS A LARGER COGGED WHEEL, (MAIN GEAR). MAIN GEAR ENGAGES A COGGED BAR CALLED A TRAVELLER WHICH MOVES FORWARD OR BACK DEPENDING ON WHICH WAY THE CRANK IS TURNED. CONNECTED TO THE TRAVELLER ARE TO LONG RODS (GATE ARMS) WHICH IN TURN ARE CONNECTED TO THE GATE'S TOP BEAM (ONE FOR EACH GATE). AS THE TRAVELLER MOVES FORWARD THE GATE ARMS EXTEND PUSHING THE GATES OPEN. - Morris Canal, Phillipsburg, Warren County, NJ

  18. Simulation of the shape of chaperonins using the small-angle x-ray scattering curves and torus form factor

    SciTech Connect

    Amarantov, S. V.; Naletova, I. N.; Kurochkina, L. P.

    2011-08-15

    The inverse scattering problem has been solved for protein complexes whose surfaces can be described by a set of the simplest doubly connected surfaces in the uniform approximation (a scattering potential inside the molecule is a constant). Solutions of two proteins-well-known GroEL bacterial chaperonin and poor-studied bacteriophage chaperonin, which is a product of 146 gene (gp146)-were taken for the experiment. The shapes of protein complexes have been efficiently reconstructed from the experimental scattering curves. The shell method, the method of the rotation of amino acid sequences with the use of the form factor of an amino acid, and the method of seeking the model parameters of a protein complex with the preliminarily obtained form factor of the model have been used to reconstruct the shape of these particles.

  19. BINSYN: A Publicly Available Program for Simulating Spectra and Light Curves of Binary Systems with or without Accretion Disks

    NASA Astrophysics Data System (ADS)

    Linnell, Albert P.; DeStefano, Paul; Hubeny, Ivan

    2012-08-01

    The BINSYN program suite, a collection of programs for analysis of binary star systems with or without an optically thick accretion disk, is available for download from a wiki. This article describes the package, including download instructions. BINSYN produces synthetic spectra of individual binary star components plus a synthetic spectrum of the system. If the system includes an accretion disk, BINSYN also produces a separate synthetic spectrum of the disk face and rim. A system routine convolves the synthetic spectra with filter profiles of several photometric standards to produce absolute synthetic photometry output. The package generates synthetic light curves and determines an optimized solution for system parameters. This article includes illustrative literature references that have used the suite, including mass transfer rates in several cataclysmic binary systems.

  20. A curve number simulation of gully cut-and-fill cycles: impact of agro-management on gully activity in the Tigray Highlands

    NASA Astrophysics Data System (ADS)

    Lanckriet, Sil; Monsieurs, Elise; Frankl, Amaury; Mesfin, Gebrekidan; Descheemaeker, Katrien; Nyssen, Jan

    2015-04-01

    Gully cut-and-fill dynamics are often thought to be driven by climate and/or deforestation related to population pressure. However, in this case-study of nine representative catchments in the North Ethiopian Highlands, we find that neither climate changes nor deforestation can explain gully morphology changes over the 20th century. Firstly, by using a Monte Carlo simulation to estimate historical catchment-wide curve numbers, we show that the landscape was already heavily degraded in the 19th and early 20th century - a period with low population density. The mean catchment-wide curve number (>80) one century ago was, under the regional climatic conditions, already resulting in considerable simulated historical runoff responses. Secondly, 20th century land cover and runoff coefficient changes were confronted with 20th century changing gully morphologies. As the results show, large-scale land cover changes and deforestation cannot explain the observed processes. The study therefore invokes interactions between authigenic factors, small-scale plot boundary changes, cropland management and sociopolitical forces to explain the gully cut processes. Finally, semi-structured interviews and sedistratigraphic analysis of three filled gullies confirm the dominant impact of (crop)land management (tillage, check dams in gullies and channel diversions) on gully cut-and-fill processes. Since agricultural land management - including land tenure and land distribution - has been commonly neglected in earlier related research, we argue therefore that it can be a very strong driver of 20th century gully morphodynamics.

  1. Using a High-Fidelity Patient Simulator with First-Year Medical Students to Facilitate Learning of Cardiovascular Function Curves

    ERIC Educational Resources Information Center

    Harris, David M.; Ryan, Kathleen; Rabuck, Cynthia

    2012-01-01

    Students are relying on technology for learning more than ever, and educators need to adapt to facilitate student learning. High-fidelity patient simulators (HFPS) are usually reserved for the clinical years of medical education and are geared to improve clinical decision skills, teamwork, and patient safety. Finding ways to incorporate HFPS into…

  2. S-Shaped Canals: A Series of Cases Performed by Four Specialists around the World

    PubMed Central

    Machado, Ricardo; Chaniottis, Antonis; Vera, Jorge; Saucedo, Carlos; Vansan, Luiz Pascoal; Silva, Emmanuel João Nogueira Leal

    2014-01-01

    Recognition of anatomical variations is a real challenge for clinicians undertaking therapy regardless of the teeth that are to be treated. The extent of the curvature is one of the most important variables that could lead to instrument fracture. In clinical conditions, two curves can be present in the same root canal trajectory. This type of geometry is denoted as the “S” shape, and it is a challenging condition. This report describes a different clinical and educational scenario where four specialists around the world present different approaches for the treatment of root canals with double curvatures or S-shaped canals. Endodontic therapy is a very nuanced and challenging science and art. The clinical and teaching experience of the authors show different approaches that can be successfully employed to treat challenging teeth having roots with multiple curves. The necessity of precise knowledge of the root canal morphology and its variation is also underlined. PMID:25143838

  3. Black Anal Canal: Acute Necrosis

    PubMed Central

    Martins, Catarina; Gonçalves, Cláudia; Alves, Paulo; Gil, Inês; Canhoto, Manuela; Silva, Filipe; Cotrim, Isabel; Amado, Cristina; Eliseu, Liliana; Vasconcelos, Helena

    2016-01-01

    Acute ischemia of the rectum or anal canal resulting in necrosis is extremely uncommon because both the rectum and the anal canal have excellent blood supplies. We present a case with spontaneous necrosis of the anal canal without rectal involvement. Surgical debridement was accomplished, and the recovery was uneventful. The patient was elderly, with probable atherosclerotic arterial disease, and presented with hypotension. Due to the lack of other precipitating factors, the hypoperfusion hypothesis seems to be the most suitable in this case. To the best of our knowledge, no similar cases have been reported in the literature on this subject.

  4. Simulations of Gamma-Ray Burst Jets in a Stratified External Medium: Dynamics, Afterglow Light Curves, Jet Breaks, and Radio Calorimetry

    NASA Astrophysics Data System (ADS)

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

    2012-05-01

    The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρextvpropr -k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ-1 0. For larger k values, however, the lateral expansion is faster at early times (when Γ > θ-1 0) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θobs <= θ0) than by the slope of the external density profile (for 0 <= k <= 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more

  5. An In Vitro Comparison of Root Canal Transportation by Reciproc File With and Without Glide Path

    PubMed Central

    Nazarimoghadam, Kiumars; Daryaeian, Mohammad; Ramazani, Nahid

    2014-01-01

    Objective: The aim of ideal canal preparation is to prevent iatrogenic aberrations such as transportation. The aim of this study was to evaluate the root canal transportation by Reciproc file with and without glide path. Materials and Methods: Thirty acrylic-resin blocks with a curvature of 60° and size#10 (2% taper) were assigned into two groups (n= 15). In group 1, the glide path was performed using stainless steel k-files size#10 and 15 at working length In group 2, canals were prepared with Reciproc file system at working length. By using digital imaging software (AutoCAD 2008), the pre-instrumentation and post-instrumentation digital images were superimposed over, taking the landmarks as reference points. Then the radius of the internal and external curve of the specimens was calculated at three α, β and γ points (1mm to apex as α, 3mm to apex as β, and 5mm to apex as γ). The data were statically analyzed using the independent T-test and Mann-Whitney U test by SPSS version 16. Results: Glide path was found significant for only external curve in the apical third of the canal; that is, 5mm to apex (P=0.005). But in the other third, canal modification was not significant (P> 0.008). Conclusion: Canal transportation in the apical third of the canal seems to be significantly reduced when glide path is performed using reciprocating files. PMID:25628682

  6. Bradford Curves.

    ERIC Educational Resources Information Center

    Rousseau, Ronald

    1994-01-01

    Discussion of informetric distributions shows that generalized Leimkuhler functions give proper fits to a large variety of Bradford curves, including those exhibiting a Groos droop or a rising tail. The Kolmogorov-Smirnov test is used to test goodness of fit, and least-square fits are compared with Egghe's method. (Contains 53 references.) (LRW)

  7. The Love Canal: Beyond science?

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    When in 1978, the New York State Department of Health issued the report, ‘Love Canal—Public Health Time Bomb,’ the serious effects of chemical waste contamination in the Love Canal area became an issue of national concern. A few ‘studies’ since then have produced results in concert with those of initial reports that described ‘conditions of acute health effects’ as being linked to hazardous wastes incorporated in landfill in the Love Canal site near Niagara Falls, New York. Now that a ‘blue ribbon’ panel of experts from the medical sciences has reviewed the problems of Love Canal, however, a different view has emerged. The ‘Report of the Governors' Panel to Review Scientific Studies and the Development of Public Policy on Problems Resulting from Hazardous Wastes,’ transmitted in October of this year, identifies the following factors about the health effects at Love Canal:

  8. Looking back at Love Canal

    SciTech Connect

    Deegan, J. Jr.

    1987-05-01

    In the first part of this series (ES and T, April 1987, pp. 328-31) it was pointed out that the methods and conclusions of EPA's Love Canal Study were the subject of some controversy in the environmental community. Others defended the agency's approaches and methods. Part 2 makes no attempt to resolve the controversy; its purpose is to present the results and conclusions of the Love Canal.

  9. Study of Morphometry of Carotid Canal in Skulls of South Indian origin

    PubMed Central

    N M, Shamasundar

    2015-01-01

    Background: The internal carotid artery supplies the anterior part of the brain, the eye and its appendages and sends branches to the forehead and nose.Carotid canal is a curved channel in the petrous temporal bone through which internal carotid artery enters the skull. Aim: In the present study 20 skulls of unknown sex were considered. The morphometric study of carotid canal was studied by direct bone method and by silicone cast method. The present study aimed to show the differences of measurements by two methods and the silicon cast method is of its kind to measure the length of the carotid canal. Materials and Methods: Carotid canal were measured at three different levels by both methods. Length of carotid canal to bend, diameter at the bend, length from the bend to foramen lacerum. The data was analysed for all the measurements of two methods and comparison of mean and SD at three different levels was done.Significant difference between two methods at three different levels was observed. Independent sample t-test was applied for total length of carotid canal. Results: By observation there is a mean significant difference between two methods in the measurements of carotid canal from lower opening till the angulation on left side of the skull.The study showed that there is a bilateral significant difference in measurements of diameter between two methods. There was no significant difference observed in total length of the canal in both left and right sides. Conclusion: Morphometrical details of the canal are of great significance to neurosurgeons and otologists. Silicon cast method was cost effective and much easier method to study the length and measurements of carotid canal as it exactly depicts the curvature of carotid canal. PMID:25859440

  10. Gamma-Ray Burst Afterglow Light Curves from a Lorentz-boosted Simulation Frame and the Shape of the Jet Break

    NASA Astrophysics Data System (ADS)

    van Eerten, Hendrik; MacFadyen, Andrew

    2013-04-01

    The early stages of decelerating gamma-ray burst (GRB) afterglow jets have been notoriously difficult to resolve numerically using two-dimensional hydrodynamical simulations even at very high resolution, due to the extreme thinness of the blast wave and high outflow Lorentz factors. However, these resolution issues can be avoided by performing the simulations in a boosted frame, which makes it possible to calculate afterglow light curves from numerically computed flows in sufficient detail to accurately quantify the shape of the jet break and the post-break steepening of the light curve. Here, we study afterglow jet breaks for jets with opening angles of 0.05, 0.1, and 0.2 radians decelerating in a surrounding medium of constant density, observed at various angles ranging from on-axis to the edge of the jet. A single set of scale-invariant functions describing the time evolution of afterglow synchrotron spectral break frequencies and peak flux, depending only on jet opening angle and observer angle, are all that is needed to reconstruct light curves for arbitrary explosion energy, circumburst density and synchrotron particle distribution power law slope p. These functions are presented in the paper. Their time evolutions change directly following the jet break, although an earlier reported temporary post-break steepening of the cooling break is found to have been resolution-induced. We compare synthetic light curves to fit functions using sharp power law breaks as well as smooth power law transitions. We confirm our earlier finding that the measured jet break time is very sensitive to the angle of the observer and can be postponed significantly. We find that the difference in temporal indices across the jet break is larger than theoretically anticipated and is about -(0.5 + 0.5p) below the cooling break and about -(0.25 + 0.5p) above the cooling break, both leading to post-break slopes of roughly about 0.25 - 1.3p, although different observer angles, jet opening

  11. GAMMA-RAY BURST AFTERGLOW LIGHT CURVES FROM A LORENTZ-BOOSTED SIMULATION FRAME AND THE SHAPE OF THE JET BREAK

    SciTech Connect

    Van Eerten, Hendrik; MacFadyen, Andrew

    2013-04-20

    The early stages of decelerating gamma-ray burst (GRB) afterglow jets have been notoriously difficult to resolve numerically using two-dimensional hydrodynamical simulations even at very high resolution, due to the extreme thinness of the blast wave and high outflow Lorentz factors. However, these resolution issues can be avoided by performing the simulations in a boosted frame, which makes it possible to calculate afterglow light curves from numerically computed flows in sufficient detail to accurately quantify the shape of the jet break and the post-break steepening of the light curve. Here, we study afterglow jet breaks for jets with opening angles of 0.05, 0.1, and 0.2 radians decelerating in a surrounding medium of constant density, observed at various angles ranging from on-axis to the edge of the jet. A single set of scale-invariant functions describing the time evolution of afterglow synchrotron spectral break frequencies and peak flux, depending only on jet opening angle and observer angle, are all that is needed to reconstruct light curves for arbitrary explosion energy, circumburst density and synchrotron particle distribution power law slope p. These functions are presented in the paper. Their time evolutions change directly following the jet break, although an earlier reported temporary post-break steepening of the cooling break is found to have been resolution-induced. We compare synthetic light curves to fit functions using sharp power law breaks as well as smooth power law transitions. We confirm our earlier finding that the measured jet break time is very sensitive to the angle of the observer and can be postponed significantly. We find that the difference in temporal indices across the jet break is larger than theoretically anticipated and is about -(0.5 + 0.5p) below the cooling break and about -(0.25 + 0.5p) above the cooling break, both leading to post-break slopes of roughly about 0.25 - 1.3p, although different observer angles, jet opening

  12. A Review and Comparison of Methods for Recreating Individual Patient Data from Published Kaplan-Meier Survival Curves for Economic Evaluations: A Simulation Study

    PubMed Central

    Wan, Xiaomin; Peng, Liubao; Li, Yuanjian

    2015-01-01

    Background In general, the individual patient-level data (IPD) collected in clinical trials are not available to independent researchers to conduct economic evaluations; researchers only have access to published survival curves and summary statistics. Thus, methods that use published survival curves and summary statistics to reproduce statistics for economic evaluations are essential. Four methods have been identified: two traditional methods 1) least squares method, 2) graphical method; and two recently proposed methods by 3) Hoyle and Henley, 4) Guyot et al. The four methods were first individually reviewed and subsequently assessed regarding their abilities to estimate mean survival through a simulation study. Methods A number of different scenarios were developed that comprised combinations of various sample sizes, censoring rates and parametric survival distributions. One thousand simulated survival datasets were generated for each scenario, and all methods were applied to actual IPD. The uncertainty in the estimate of mean survival time was also captured. Results All methods provided accurate estimates of the mean survival time when the sample size was 500 and a Weibull distribution was used. When the sample size was 100 and the Weibull distribution was used, the Guyot et al. method was almost as accurate as the Hoyle and Henley method; however, more biases were identified in the traditional methods. When a lognormal distribution was used, the Guyot et al. method generated noticeably less bias and a more accurate uncertainty compared with the Hoyle and Henley method. Conclusions The traditional methods should not be preferred because of their remarkable overestimation. When the Weibull distribution was used for a fitted model, the Guyot et al. method was almost as accurate as the Hoyle and Henley method. However, if the lognormal distribution was used, the Guyot et al. method was less biased compared with the Hoyle and Henley method. PMID:25803659

  13. Mimamata and Love Canal: A Pollution Tale of Two Cities.

    ERIC Educational Resources Information Center

    Williams, Mary Louise

    1993-01-01

    Presents a lesson plan about case studies of the environmental disasters of Minamata, Japan and Love Canal, New York. Compares how the legal cases were handled in two constitutional democracies. Provides six handouts that include maps, role descriptions for simulations, and student readings. (CFR)

  14. Limitations of navigation through Nubaria canal, Egypt

    PubMed Central

    Samuel, Magdy G.

    2013-01-01

    Alexandria port is the main Egyptian port at the Mediterranean Sea. It is connected to the Nile River through Nubaria canal, which is a main irrigation canal. The canal was designed to irrigate eight hundred thousand acres of agricultural lands, along its course which extends 100 km. The canal has three barrages and four locks to control the flow and allow light navigation by some small barges. Recently, it was decided to improve the locks located on the canal. More than 40 million US$ was invested in these projects. This decision was taken to allow larger barges and increase the transported capacity through the canal. On the other hand, navigation through canals and restricted shallow waterways is affected by several parameters related to both the channel and the vessel. Navigation lane width as well as vessel speed and maneuverability are affected by both the channel and vessel dimensions. Moreover, vessel dimensions and speed will affect the canal stability. In Egypt, there are no guide rules for navigation through narrow and shallow canals such Nubaria. This situation threatens the canal stability and safety of navigation through it. This paper discussed the characteristics of Nubaria canal and the guide rules for navigation in shallow restricted water ways. Dimensions limitation for barges navigating through Nubaria canal is presented. New safe operation rules for navigation in Nubaria canal are also presented. Moreover, the implication of navigation through locks on canal discharge is estimated. PMID:25685482

  15. Root Canal Shaping by Single-File Systems and Rotary Instruments: a Laboratory Study

    PubMed Central

    Bane, Khaly; Faye, Babacar; Sarr, Mouhamed; Niang, Seydina O; Ndiaye, Diouma; Machtou, Pierre

    2015-01-01

    Introduction: The aim of this study was to compare the shaping ability of two single-file systems and conventional rotary instruments in severely curved root canals of extracted human molars. Methods and Materials: Mesiobuccal canals of 120 mandibular molars with angles of curvature ranging between 25° and 35° and radii of curvature from 5 to 9 mm, were divided into three groups (n=40). In each group the canals were instrumented with either WaveOne (W), Reciproc (R) or ProTaper (P). The time required for canal shaping and the frequency of broken instruments were recorded. The standardized pre and post-instrumentation radiographs were taken to determine changes in working length (WL) and straightening of canal curvature. The presence of blockage or perforation was also evaluated. Data were analyzed using the one-way analysis of variance (ANOVA) and post-hoc Tukey’s test. The level of significance was set at 0.05. Results: Both single-instrument systems reduced the canal preparation time by approximately 50% (P<0.05). No incidence of broken instruments from single-file systems was reported; however, two F2 instruments in the P group were broken (P<0.05). Reduction in WL and straightening of canal curvature was observed in all three systems with the highest scores belonging to P system (P<0.05). No case of blockage or perforation was found during shaping in any group. Conclusion: Single-file systems shaped curved canals with substantial saving in time and a significant decrease in incidence of instrument separation, change in WL, and straightening of canal curvature. PMID:25834600

  16. Optodynamic Phenomena During Laser-Activated Irrigation Within Root Canals

    NASA Astrophysics Data System (ADS)

    Lukač, Nejc; Gregorčič, Peter; Jezeršek, Matija

    2016-07-01

    Laser-activated irrigation is a powerful endodontic treatment for smear layer, bacteria, and debris removal from the root canal. In this study, we use shadow photography and the laser-beam-transmission probe to examine the dynamics of laser-induced vapor bubbles inside a root canal model and compare ultrasonic needle irrigation to the laser method. Results confirm important phenomenological differences in the two endodontic methods with the laser method resulting in much deeper irrigation. Observations of simulated debris particles show liquid vorticity effects which in our opinion represents the major cleaning mechanism.

  17. IGMtransmission: Transmission curve computation

    NASA Astrophysics Data System (ADS)

    Harrison, Christopher M.; Meiksin, Avery; Stock, David

    2015-04-01

    IGMtransmission is a Java graphical user interface that implements Monte Carlo simulations to compute the corrections to colors of high-redshift galaxies due to intergalactic attenuation based on current models of the Intergalactic Medium. The effects of absorption due to neutral hydrogen are considered, with particular attention to the stochastic effects of Lyman Limit Systems. Attenuation curves are produced, as well as colors for a wide range of filter responses and model galaxy spectra. Photometric filters are included for the Hubble Space Telescope, the Keck telescope, the Mt. Palomar 200-inch, the SUBARU telescope and UKIRT; alternative filter response curves and spectra may be readily uploaded.

  18. Corinth Canal, Greece

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Isthmus of Corinth has played a very important role in the history of Greece. It is the only land bridge between the country's north (Attica) and south (Peloponnese). It is a 6 km wide tongue of land separating the Gulf of Corinth from the Saronic Sea. Populations, armies and commodities have got to move through it. In the 6th century BCE, the Greeks built the Diolkos, a 10 meter-wide stone roadway to pull ships across the Isthmus on wooden cylinders and wheeled vehicles. In 1882, a canal was started and completed 11 years later. It is 6343 meters long, 25 meters wide, and 8 meters deep.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 25.3 by 37.7 kilometers (15.7 by 23.4 miles) Location: 37.9 degrees North latitude, 23 degrees East longitude

  19. Fluidmechanics of semicircular canals revisited

    NASA Astrophysics Data System (ADS)

    Obrist, Dominik

    2008-05-01

    In this work we find the exact solution for the flow field in a semicircular canal which is the main sensor for angular motion in the human body. When the head is rotated the inertia of the fluid in the semicircular canal leads to a deflection of sensory hair cells which are part of a gelatinous structure called cupula. A modal expansion of the governing equation shows that the semicircular organ can be understood as a dynamic system governed by duct modes and a single cupular mode. We use this result to derive an explicit expression for the displacement of the cupula as a function of the angular motion of the head. This result shows in a mathematically and physically clean way that the semicircular canal is a transducer for angular velocity.

  20. The X-ray Power Density Spectrum of the Seyfert 2 Galaxy NGC 4945: Analysis and Application of the Method of Light Curve Simulations

    SciTech Connect

    Mueller, Martin; /SLAC

    2010-12-16

    The study of the power density spectrum (PDS) of fluctuations in the X-ray flux from active galactic nuclei (AGN) complements spectral studies in giving us a view into the processes operating in accreting compact objects. An important line of investigation is the comparison of the PDS from AGN with those from galactic black hole binaries; a related area of focus is the scaling relation between time scales for the variability and the black hole mass. The PDS of AGN is traditionally modeled using segments of power laws joined together at so-called break frequencies; associations of the break time scales, i.e., the inverses of the break frequencies, with time scales of physical processes thought to operate in these sources are then sought. I analyze the Method of Light Curve Simulations that is commonly used to characterize the PDS in AGN with a view to making the method as sensitive as possible to the shape of the PDS. I identify several weaknesses in the current implementation of the method and propose alternatives that can substitute for some of the key steps in the method. I focus on the complications introduced by uneven sampling in the light curve, the development of a fit statistic that is better matched to the distributions of power in the PDS, and the statistical evaluation of the fit between the observed data and the model for the PDS. Using archival data on one AGN, NGC 3516, I validate my changes against previously reported results. I also report new results on the PDS in NGC 4945, a Seyfert 2 galaxy with a well-determined black hole mass. This source provides an opportunity to investigate whether the PDS of Seyfert 1 and Seyfert 2 galaxies differ. It is also an attractive object for placement on the black hole mass-break time scale relation. Unfortunately, with the available data on NGC 4945, significant uncertainties on the break frequency in its PDS remain.

  1. Wavelength dependence of photon-induced photoacoustic streaming technique for root canal irrigation

    NASA Astrophysics Data System (ADS)

    Lukač, Nejc; Zadravec, Jure; Gregorčič, Peter; Lukač, Matjaž; Jezeršek, Matija

    2016-07-01

    Laser-enhanced irrigation of complex root canals appears to be a very promising technique to improve the outcome of root canal treatment. This applies, in particular, if the technique can be effective at very low laser energies in irrigating not only the main canal but also the small lateral canals. This is important in order to avoid potential undesirable effects at higher laser energies such as temperature increase, dentin ablation, or extrusion of irrigating solution beyond the apical foramen. An improved understanding of the role of laser parameters, such as laser wavelength and pulse duration, in irrigation of lateral canals is therefore desired in order to optimize treatment efficacy. The influence of laser wavelength and pulse duration on cavitation phenomena was studied using shadow photography and a method of measuring fluid flow in lateral canals based on tracking of movements of small air bubbles naturally forming in liquid as a result of laser agitation. A simulated model of a root canal including a narrow lateral canal designed to represent typical root canal morphology was used for the water flow measurements. The following three laser wavelengths with relatively high absorption in water were studied: Er:YAG (2.94 μm), Er,Cr:YSGG (2.73 μm), and Nd:YAP (1.34 μm). Among the three wavelengths studied, the Er:YAG laser wavelength was found to be the most effective in formation of cavitation bubbles and in generating fluid motions within narrow lateral canals. A comparison between the shadow photography and fluid motion data indicates that it is the bubble's radius and not the bubble's volume that predominantly influences the fluid motion within lateral canals. Based on the results of our study, it appears that effective minimally invasive laser-assisted irrigation can be performed with low Er:YAG laser pulse energies below 10 mJ.

  2. Erie Canal Technology: Stump Pullers

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2013-01-01

    Many years ago I saw a picture of a huge set of wheels that was used to remove tree stumps during the construction of the Erie Canal (1817-1825) and was intrigued by its use of leverage, mechanical advantage, and torque. Figure 1 is a scale model of the device based on my memory of the (lost) picture and published accounts.

  3. Erie Canal Technology: Stump Pullers

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2013-10-01

    Many years ago I saw a picture of a huge set of wheels that was used to remove tree stumps during the construction of the Erie Canal (1817-1825) and was intrigued by its use of leverage, mechanical advantage, and torque. Figure 1 is a scale model of the device based on my memory of the (lost) picture and published accounts.

  4. A continuity equation for the simulation of the current-voltage curve and the time-dependent properties of dye-sensitized solar cells.

    PubMed

    Anta, Juan A; Idígoras, Jesús; Guillén, Elena; Villanueva-Cab, Julio; Mandujano-Ramírez, Humberto J; Oskam, Gerko; Pellejà, Laila; Palomares, Emilio

    2012-08-01

    A numerical model that simulates the steady-state current-voltage curve and the time-dependent response of a dye-sensitized solar cell with a single continuity equation is derived. It is shown that the inclusion of the multiple-trapping model, the quasi-static approximation and non-linear recombination kinetics leads to a continuity equation for the total electron density in the photoanode with an electron density-dependent diffusion coefficient and a density-dependent pseudo-first order recombination constant. All parameters in the model can be related to quantities accessible experimentally. The required power exponents are taken from impedance spectroscopy measurements at different voltages. The model provides new insights into the physical interpretation of the power exponents. Modeling examples involving a high-efficiency TiO(2)-based dye solar cell and a ZnO-based dye solar cell are presented. It is demonstrated that the model reproduces the transient behavior of the cell under small perturbations. The spatial dependence of the recombination rate and the influence of film thickness and of voltage dependent injection efficiency on cell performance are studied. The implications of the model are discussed in terms of efficiencies potentially attainable in dye-sensitized solar cells and other kinds of solar cells with a diffusional mechanism of charge transport. PMID:22735099

  5. Dynamic intratubular biomineralization following root canal obturation with pozzolan-based mineral trioxide aggregate sealer cement.

    PubMed

    Yoo, Yeon-Jee; Baek, Seung-Ho; Kum, Kee-Yeon; Shon, Won-Jun; Woo, Kyung-Mi; Lee, WooCheol

    2016-01-01

    The application of mineral trioxide aggregates (MTA) cement during the root canal obturation is gaining concern due to its bioactive characteristic to form an apatite in dentinal tubules. In this regard, this study was to assess the biomineralization of dentinal tubules following root canal obturation by using pozzolan-based (Pz-) MTA sealer cement (EndoSeal MTA, Maruchi). Sixty curved roots (mesiobuccal, distobuccal) from human maxillary molars were instrumented and prepared for root canal obturation. The canals were obturated with gutta-percha (GP) and Pz-MTA sealer by using continuous wave of condensation technique. Canals obturated solely with ProRoot MTA (Dentsply Tulsa Dental) or Pz-MTA sealer were used for comparison. In order to evaluate the biomineralization ability under different conditions, the PBS pretreatment before the root canal obturation was performed in each additional samples. At dentin-material interfaces, the extension of intratubular biomineralization was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy. When the root canal was obturated with GP and Pz-MTA sealer, enhanced biomineralization of the dentinal tubules beyond the penetrated sealer tag was confirmed under the SEM observation (p < 0.05). Mineralized apatite structures (calcium/phosphorous ratio, 1.45-1.89) connecting its way through the dentinal tubules were detected at 350-400 μm from the tubule orifice, and the pre-crystallization seeds were also observed along the intra- and/or inter-tubular collagen fiber. Intratubular biomineralization depth was significantly enhanced in all PBS pretreated canals (p < 0.05). Pz-MTA cement can be used as a promising bioactive root canal sealer to enhance biomineralization of dentinal tubules under controlled environment. SCANNING 38:50-56, 2016. © 2015 The Authors. Scanning Published by Wiley Periodicals, Inc. PMID:26179659

  6. A Low-Cost Teaching Model of Inguinal Canal: A Useful Method to Teach Surgical Concepts in Hernia Repair

    ERIC Educational Resources Information Center

    Ansaloni, Luca; Catena, Fausto; Coccolini, Frederico; Ceresoli, Marco; Pinna, Antonio Daniele

    2014-01-01

    Objectives: Inguinal canal anatomy and hernia repair is difficult for medical students and surgical residents to comprehend. Methods: Using low-cost material, a 3-dimensional inexpensive model of the inguinal canal was created to allow students to learn anatomical details and landmarks and to perform their own simulated hernia repair. In order to…

  7. ETR BUILDING, TRA642, INTERIOR. FIRST FLOOR. WORKING CANAL AND REACTOR. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ETR BUILDING, TRA-642, INTERIOR. FIRST FLOOR. WORKING CANAL AND REACTOR. CAMERA FACING NORTHEASTERLY. CONTROL ROOM WALL ALONG LEFT HALF OF VIEW. NOTE CURVED DUCT EMERGING FROM FLOOR AT LEFT EDGE OF VIEW. INL NEGATIVE NO. HD46-16-1. Mike Crane, Photographer, 2/2005 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  8. Characterization of mandibular molar root and canal morphology using cone beam computed tomography and its variability in Belgian and Chilean population samples

    PubMed Central

    Jacobs, Reinhilde; Lambrechts, Paul; Brizuela, Claudia; Cabrera, Carolina; Concha, Guillermo; Pedemonte, María Eugenia

    2015-01-01

    Purpose This study used cone-beam computed tomography (CBCT) to characterize mandibular molar root and canal morphology and its variability in Belgian and Chilean population samples. Materials and Methods We analyzed the CBCT images of 515 mandibular molars (257 from Belgium and 258 from Chile). Molars meeting the inclusion criteria were analyzed to determine (1) the number of roots; (2) the root canal configuration; (3) the presence of a curved canal in the cross-sectional image of the distal root in the mandibular first molar and (4) the presence of a C-shaped canal in the second mandibular molar. A descriptive analysis was performed. The association between national origin and the presence of a curved or C-shaped canal was evaluated using the chi-squared test. Results The most common configurations in the mesial root of both molars were type V and type III. In the distal root, type I canal configuration was the most common. Curvature in the cross-sectional image was found in 25% of the distal canals of the mandibular first molars in the Belgian population, compared to 11% in the Chilean population. The prevalence of C-shaped canals was 10% or less in both populations. Conclusion In cases of unclear or complex root and canal morphology in the mandibular molars, CBCT imaging might assist endodontic specialists in making an accurate diagnosis and in treatment planning. PMID:26125004

  9. Curves and Their Properties.

    ERIC Educational Resources Information Center

    Yates, Robert C.

    This volume, a reprinting of a classic first published in 1952, presents detailed discussions of 26 curves or families of curves, and 17 analytic systems of curves. For each curve the author provides a historical note, a sketch or sketches, a description of the curve, a discussion of pertinent facts, and a bibliography. Depending upon the curve,…

  10. Stem length and canal filling in uncemented custom-made total hip arthroplasty.

    PubMed

    Sakai, T; Sugano, N; Nishii, T; Haraguchi, K; Ochi, T; Ohzono, K

    1999-01-01

    We reviewed 60 custom-made femoral components of two different lengths : 125 mm (group A) and 100 mm (group B), in order to investigate the relationship between stem length and canal filling in uncemented custom-made total hip arthroplasty. There were no statistical differences between the two groups in age, gender, height, body weight, canal flare index, or bowing angle of the femur. Postoperatively there was no statistical difference between the two groups in the proximal canal filling, but significant difference in the distal canal filling (75.5% vs 85.8% on the anteroposterior view and 76.0% vs 82.5% in the lateral view, P<0.001). The distal canal filling inversely correlated with the ratio of the proximal portion and the distal portion of the stem curvature on the lateral view (lateral curve ratio of the stem, P=0.002). We conclude that superior filling at both the proximal and the distal levels can be obtained by using 100-mm custom made components with a small lateral curve ratio. PMID:10591939

  11. The effect of chloroform, orange oil and eucalyptol on root canal transportation in endodontic retreatment.

    PubMed

    Karataş, Ertuğrul; Kol, Elif; Bayrakdar, İbrahim Şevki; Arslan, Hakan

    2016-04-01

    The purpose of the present study was to assess the effect of solvents on root canal transportation in endodontic retreatment. Sixty extracted human permanent mandibular first molars with curved root canals were selected. All of the root canals were prepared using Twisted File Adaptive instruments (SybronEndo, Orange, CA, USA) and filled with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) using the cold lateral compaction technique. The teeth were assigned to four retreatment groups as follows (n = 15): eucalyptol, chloroform, orange oil and control. The canals were scanned using cone-beam computed tomography scanning before and after instrumentation. The chloroform group showed a significantly higher mean transportation value than the orange oil and control groups at the 3 and 5 mm levels (P = 0.011 and P = 0.003, respectively). There was no significant difference among the orange oil, eucalyptol and control groups in terms of canal transportation (P > 0.61). The chloroform led to more canal transportation than the eucalyptol and orange oil during endodontic retreatment. PMID:26420757

  12. 160. Photocopy of drawing (taken from Twin Falls Canal Company ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    160. Photocopy of drawing (taken from Twin Falls Canal Company Field Book #361 #86, page 1). SCALE DRAWING, CANAL HEADGATES AND CANAL SURVEY, 'A' LINE. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

  13. Management of Six Root Canals in Mandibular First Molar

    PubMed Central

    Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

    2015-01-01

    Success in root canal treatment is achieved after thorough cleaning, shaping, and obturation of the root canal system. This clinical case describes conventional root canal treatment of an unusual mandibular first molar with six root canals. The prognosis for endodontic treatment in teeth with abnormal morphology is unfavorable if the clinician fails to recognize extra root canals. PMID:25685156

  14. Developmental spinal canal stenosis and somatotype.

    PubMed Central

    Nightingale, S

    1989-01-01

    The hypothesis that somatotype and cervical spine developmental canal stenosis may be associated has been investigated by anthropometry and measurement of lateral projection cervical spine radiographs. A significant association of canal size with somatotype has been found such that those with developmentally narrow canals are more likely to have relatively shorter long-bones, particularly in the upper arm, and longer trunks. Images PMID:2769282

  15. Complicated canal morphology of mandibular first premolar

    PubMed Central

    Pallavi, Vyapaka; Kumar, Janga Ravi; Mandava, Ramesh Babu; Rao, Subramanian Hari

    2015-01-01

    The aim of this article was to report an unusual anatomic variation of mandibular first premolar, with one root and three distinct canals, which leave pulp chamber and merge short of apex to exit as two separate apical foramina. The incidence of three canals existing as two apical foramina has only been documented in the literature by a few case reports. To achieve successful endodontic treatment, the clinician has to identify the different canal configurations and treat them properly. PMID:26538977

  16. Chlorhexidine as a canal irrigant: a review.

    PubMed

    Ryan, Steven

    2010-06-01

    The use of an irrigant during root canal therapy is an important factor in the cleaning and disinfecting of the root canal system. While sodium hypochlorite has been used for decades as a primary irrigant, other irrigants have been investigated as alternatives. This article reviews chlorhexidine as a canal irrigant, explores its different properties, and provides the dental practitioner with information to help make a more informed decision when choosing an irrigant. PMID:20583503

  17. Hypoglossal canal size and hominid speech

    PubMed Central

    DeGusta, David; Gilbert, W. Henry; Turner, Scott P.

    1999-01-01

    The mammalian hypoglossal canal transmits the nerve that supplies the motor innervation to the tongue. Hypoglossal canal size has previously been used to date the origin of human-like speech capabilities to at least 400,000 years ago and to assign modern human vocal abilities to Neandertals. These conclusions are based on the hypothesis that the size of the hypoglossal canal is indicative of speech capabilities. This hypothesis is falsified here by the finding of numerous nonhuman primate taxa that have hypoglossal canals in the modern human size range, both absolutely and relative to oral cavity volume. Specimens of Australopithecus afarensis, Australopithecus africanus, and Australopithecus boisei also have hypoglossal canals that, both absolutely and relative to oral cavity volume, are equal in size to those of modern humans. The basis for the hypothesis that hypoglossal canal size is indicative of speech was the assumption that hypoglossal canal size is correlated with hypoglossal nerve size, which in turn is related to tongue function. This assumption is probably incorrect, as we found no apparent correlation between the size of the hypoglossal nerve, or the number of axons it contains, and the size of the hypoglossal canal in a sample of cadavers. Our data demonstrate that the size of the hypoglossal canal does not reflect vocal capabilities or language usage. Thus the date of origin for human language and the speech capabilities of Neandertals remain open questions. PMID:9990105

  18. Love Canal: environmental and toxicological studies

    SciTech Connect

    Kim, C.S.

    1981-01-01

    The New York State Department of Health has been involved at the Love Canal since 1978. The State has carried out numerous environmental and toxicological studies. The major purposes for these studies were to define how Love Canal contaminants might be escaping into the environment at large, what paths contaminant migration might take, and what toxicological effects Love Canal chemicals might have individually and together. Although underground contaminant migration was hypothesized along swales and underground utility bedding, these mechanisms have been proven not to be operative except for some migration along the utility bedding under Frontier Avenue. In general no underground migration has occurred outside the confines of the three city blocks that contain the Love Canal referred to as the ''first ring''. Studies have been confused by apparent burial of waste materials in areas proximate but not directly connected to the Love Canal. Migration of Love Canal leachate has occurred through storm sewers. Love Canal contaminants have reached creeks to the north and the Niagara River to the south through storm sewer transport. In spite of finding 2, 3, 7, 8 tetrachlorodibenzoparadioxin (TCDD), toxicological studies in situ and through exposure to volatile components in Love Canal soils do not indicate unusual toxicity. Animal studies continue in an attempt to determine the teratogenic and fetotoxic potential of Love Canal chemicals under different routes of exposure.

  19. The primate semicircular canal system and locomotion

    PubMed Central

    Spoor, Fred; Garland, Theodore; Krovitz, Gail; Ryan, Timothy M.; Silcox, Mary T.; Walker, Alan

    2007-01-01

    The semicircular canal system of vertebrates helps coordinate body movements, including stabilization of gaze during locomotion. Quantitative phylogenetically informed analysis of the radius of curvature of the three semicircular canals in 91 extant and recently extinct primate species and 119 other mammalian taxa provide support for the hypothesis that canal size varies in relation to the jerkiness of head motion during locomotion. Primate and other mammalian species studied here that are agile and have fast, jerky locomotion have significantly larger canals relative to body mass than those that move more cautiously. PMID:17576932

  20. 12. CONCRETE LINING ON A CURVING SEGMENT OF THE LATERAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. CONCRETE LINING ON A CURVING SEGMENT OF THE LATERAL NEAR THE NORTHEAST END OF LAKE LADORA (SECTION 2). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  1. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  2. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  3. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  4. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  5. SECTION OF CANAL AT PROPOSED McLELLAN DRIVE INTERCHANGE, SHOWING CANAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SECTION OF CANAL AT PROPOSED McLELLAN DRIVE INTERCHANGE, SHOWING CANAL (RIGHT), BRIDAL TRAIL (CENTER) AND PEDESTRIAN/BICYCLE TRAIL (RIGHT). VIEW TO NORTH - High Line Canal, Mouth of South Platte River to confluence with Second Creek, Denver, Denver County, CO

  6. Standard Mastery Curves and Skew Curves.

    ERIC Educational Resources Information Center

    Warries, Egbert

    The objective of the study is to convince educational researchers of the necessity for "standard mastery curves" for the graphical representation of scores on summative tests for a group of students. Attention is drawn to the study of theoretical and empirical skew curves in education and biology. Use of standard mastery curves and study of skew…

  7. 63. PLANS FOR PROPOSED HISTORICAL CANAL SECTION AND PUBLIC BOAT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. PLANS FOR PROPOSED HISTORICAL CANAL SECTION AND PUBLIC BOAT LAUNCH RAMP Plan Sheet D-29976, Venice Canals Rehabilitation, Sheet 25 of 26 (delineated by Manuel Bartolome, November 1991) - Venice Canals, Community of Venice, Los Angeles, Los Angeles County, CA

  8. 10. DETAIL, SOUTHEAST SPAN THROUGH CANAL, VIEW BLOCKED BY STEEL, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. DETAIL, SOUTHEAST SPAN THROUGH CANAL, VIEW BLOCKED BY STEEL, CLAD COUNTER WEIGHT, WATER SPAN RAISED OUT OF VIEW - Cape Cod Canal Lift Bridge, Spanning Cape Cod Canal, Buzzards Bay, Barnstable County, MA

  9. 3. August, 1971. VIEW ALONG CANAL SHOWING BORDER PATH AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. August, 1971. VIEW ALONG CANAL SHOWING BORDER PATH AND BRIDGE FOR INSPECTION - ABOUT ONE MILE FROM CANAL HEAD. - Hurricane Irrigation Canal, State Route 15 Vicinity, Hurricane, Washington County, UT

  10. OBLIQUE VIEW OF NORTHWEST SIDE OF 2195 SOUTHWEST CANAL STREET, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OBLIQUE VIEW OF NORTHWEST SIDE OF 2195 SOUTHWEST CANAL STREET, VIEW TOWARDS SOUTHEAST - St. Lucie Canal, Lock No. 1, Attendant's Quarters, St. Lucie, Cross State Canal, Okeechobee Intracoastal Waterway, Stuart, Martin County, FL