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Sample records for polished tapered stem

  1. Initial Evaluation on Subsidence of Cemented Collarless Polished Tapered Stem Applied to the Patients with Narrow Femoral Medullar Canal

    PubMed Central

    Dairaku, Katsuyuki; Ishii, Masaji; Kobayashi, Shinji; Kawaji, Hiroyuki; Sasaki, Kan; Takakubo, Yuya; Takagi, Michiaki

    2010-01-01

    Purpose: The geometry of the proximal femur is one of the important factors for choosing the suitable stem. We have been applied cemented collarless polished tapered (CPT) stem to the patients with small femur. Radiographic evaluation was performed to access the clinical feature of the stem in early stage of the follow-up. Methods: One hundred total hip arthroplasties with CPT system were performed between October 2004 to February 2006. This study focused on the 53 cases to whom size 1 or smaller sized stem were implanted, and its post-operative period was 41 months (30-46 months). Morphologic classification of preoperative proximal femur, stem alignment, thickness of the cement mantle, cementing technique, subsidence of the stem, improvement in the bone-cement interface, and stress shielding were assessed. Results: The size of the inserted stem was X-SMALL in one case, SMALL in two cases, SIZE 0 in 12 cases, and SIZE 1 in 38 cases. Canal shape of proximal femur was stovepipe type in five cases, normal type in 43 cases, and champagne-flute type in five cases. There was no subsidence in eight cases. 44 stems subsided within 1 mm, one stem subsided 1 to 2 mm, and no stem subsided over 2 mm. In 39 of 45 cases, subsidence was appeared within six months after operation. Marked progressive and excessive subsidence was not seen after the two years of follow-up. Conclusions: Short term radiographic results of THA with CPT stem to small femur were satisfactory with less unfavorable radiographic findings, which imply contribution to longer survivorship of the stem. PMID:20448819

  2. Substantially higher prevalence of postoperative peri­prosthetic fractures in octogenarians with hip fractures operated with a cemented, polished tapered stem rather than an anatomic stem

    PubMed Central

    Mukka, Sebastian; Mellner, Carl; Knutsson, Björn; Sayed-Noor, Arkan; Sköldenberg, Olof

    2016-01-01

    Background and purpose Recent studies have demonstrated a high incidence of postoperative periprosthetic femoral fracture (PPF) in elderly patients treated with 2 commonly used cemented, polished tapered stems. We compared the prevalence and incidence rate of PPF in a consecutive cohort of octagenerians with femoral neck fractures (FNFs) treated with either a collarless, polished tapered (CPT) stem or an anatomic matte stem (Lubinus SP2). Patients and methods In a multicenter, prospective cohort study, we included 979 hips in patients aged 80 years and above (72% females, median age 86 (80–102) years) with a femoral neck fracture as indication for surgery. 69% of the patients were classified as ASA class 3 or 4. Hip-related complications and repeat surgery were assessed at a median follow-up of 20 (0–24) months postoperatively. Results 22 hips (2.2%) sustained a PPF at a median of 7 (0–22) months postoperatively; 14 (64%) were Vancouver B2 fractures. 7 of the 22 surgically treated fractures required revision surgery, mainly due to deep infection. The cumulative incidence of PPFs was 3.8% in the CPT group, as compared with 0.2% in the SP2 group (p < 0.001). The risk ratio (RR) was 16 (95% CI: 2–120) using the SP2 group as denominator. Interpretation The CPT stem was associated with a higher risk of PPF than the SP2 stem. We suggest that the tapered CPT stem should not be used for the treatment of femoral neck fractures in patients over 80 years. PMID:27045318

  3. Femoral impaction bone allografting with an Exeter cemented collarless, polished, tapered stem in revision hip replacement: a mean follow-up of 10.5 years.

    PubMed

    Wraighte, P J; Howard, P W

    2008-08-01

    Femoral impaction bone allografting has been developed as a means of restoring bone stock in revision total hip replacement. We report the results of 75 consecutive patients (75 hips) with a mean age of 68 years (35 to 87) who underwent impaction grafting using the Exeter collarless, polished, tapered femoral stem between 1992 and 1998. The mean follow-up period was 10.5 years (6.3 to 14.1). The median pre-operative bone defect score was 3 (interquartile range (IQR) 2 to 3) using the Endo-Klinik classification. The median subsidence at one year post-operatively was 2 mm (IQR 1 to 3). At the final review the median Harris hip score was 80.6 (IQR 67.6 to 88.9) and the median subsidence 2 mm (IQR 1 to 4). Incorporation of the allograft into trabecular bone and secondary remodelling were noted radiologically at the final follow-up in 87% (393 of 452 zones) and 40% (181 of 452 zones), respectively. Subsidence of the Exeter stem correlated with the pre-operative Endo-Klinik bone loss score (p = 0.037). The degree of subsidence at one year had a strong association with long-term subsidence (p < 0.001). There was a significant correlation between previous revision surgery and a poor Harris Hip score (p = 0.028), and those who had undergone previous revision surgery for infection had a higher risk of complications (p = 0.048). Survivorship at 10.5 years with any further femoral operation as the end-point was 92% (95% confidence interval 82 to 97).

  4. The influence of proximal stem geometry and surface finish on the fixation of a double-tapered cemented femoral stem.

    PubMed

    Sangiorgio, Sophia N; Longjohn, Donald B; Dorr, Lawrence D; Ebramzadeh, Edward

    2011-01-04

    In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varying only in surface finish (polished or matte) and proximal stem geometry (with or without flanges) were compared under two conditions. First, four specimens of each stem type were tested with initially bonded stem-cement interfaces, representing early post-operative conditions. Then, simulating conditions a few weeks to months later, stems were implanted in unused synthetic femurs, with a thin layer coating the stem to prevent stem-cement adhesion. Per-cycle motions were measured at both cement interfaces throughout loading. Overall, surface finish had the smallest relative effect on fixation compared to flanges. Flanges increased axial fixation by 22 μm per-cycle, regardless of surface finish (P=0.01). Further, all stems moved under dynamic load at the stem-cement interface during the first few cycles of loading, even without a thin film. The results indicate that flanges have a greater effect on fixation than surface finish, and therefore adverse findings about matte surfaces should not necessarily apply to all double-tapered stems. Specifically, dorsal flanges enhance the stability of a tapered cemented femoral stem, regardless of surface finish.

  5. The Effect of Taper Angle and Spline Geometry on the Initial Stability of Tapered, Splined Modular Titanium Stems.

    PubMed

    Pierson, Jeffery L; Small, Scott R; Rodriguez, Jose A; Kang, Michael N; Glassman, Andrew H

    2015-07-01

    Design parameters affecting initial mechanical stability of tapered, splined modular titanium stems (TSMTSs) are not well understood. Furthermore, there is considerable variability in contemporary designs. We asked if spline geometry and stem taper angle could be optimized in TSMTS to improve mechanical stability to resist axial subsidence and increase torsional stability. Initial stability was quantified with stems of varied taper angle and spline geometry implanted in a foam model replicating 2cm diaphyseal engagement. Increased taper angle and a broad spline geometry exhibited significantly greater axial stability (+21%-269%) than other design combinations. Neither taper angle nor spline geometry significantly altered initial torsional stability.

  6. Development and verification of a cementless novel tapered wedge stem for total hip arthroplasty.

    PubMed

    Faizan, Ahmad; Wuestemann, Thies; Nevelos, Jim; Bastian, Adam C; Collopy, Dermot

    2015-02-01

    Most current tapered wedge hip stems were designed based upon the original Mueller straight stem design introduced in 1977. These stems were designed to have a single medial curvature and grew laterally to accommodate different sizes. In this preclinical study, the design and verification of a tapered wedge stem using computed tomography scans of 556 patients are presented. The computer simulation demonstrated that the novel stem, designed for proximal engagement, allowed for reduced distal fixation, particularly in the 40-60 year male population. Moreover, the physical micromotion testing and finite element analysis demonstrated that the novel stem allowed for reduced micromotion. In summary, preclinical data suggest that the computed tomography based stem design described here may offer enhanced implant fit and reduced micromotion.

  7. Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses.

    PubMed

    Witt, Florian; Gührs, Julian; Morlock, Michael M; Bishop, Nicholas E

    2015-01-01

    Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface.

  8. Feasibility of early tapering of cyclosporine following reduced-intensity stem cell transplantation for advanced hematologic or solid malignancies.

    PubMed

    Hori, Akiko; Kami, Masahiro; Ohnishi, Mutsuko; Murashige, Naoko; Kojima, Rie; Takaue, Yoichi

    2005-07-01

    Although some researchers have reported that early tapering of cyclosporine is feasible and beneficial to augment graft-versus-leukemia effects after conventional stem-cell transplantation, there is little information on the feasibility of this strategy following reduced-intensity stem cell transplantation (RIST). We summarized outcomes of 17 patients who underwent early tapering of cyclosporine following RIST from HLA-identical siblings.

  9. Effects of Prosthesis Stem Tapers on Stress Distribution of Cemented Hip Arthroplasty

    SciTech Connect

    Abdullah, Abdul Halim; Nor, Mohd Asri Mohd; Saman, Alias Mohd; Tamin, Mohd Nasir; Kadir, Mohammed Rafiq Abdul

    2010-10-15

    Aseptic loosening effects are critical issues in encouraging long term stability of cemented hip arthroplasty. Stress shielding is believed to be an important factor that contributes to the aseptic loosening problems. The numerous changes in the prosthesis stem design are intended to minimize the stress shielding and aseptic loosening problems and to improve the long term performance of the implants. In this study, the stress distribution in cemented hip arthroplasty is established using finite element method. The taper of the prosthesis is designed to be 3 deg. at anterior/posterior, 3 deg. at medial/lateral and 10 deg. from wide lateral to narrow medial. Major muscle loads and contact forces are simulated for walking (toe-off phase) and stair climbing load cases. Effects of prosthesis stem tapers on the resulting stress distribution are investigated. Results show that compressive stress dominates in the medial plane while tensile stress in the lateral plane of the femur. The corresponding stress levels of intact femur for walking and stair-climbing load cases are 22 and 29 MPa, respectively. The magnitude of Tresca stress for the THA femur in stair-climbing load case remains higher in the region of 85 MPa while the walking load case induces around 40 MPa. The stress range in the straight and single taper stem prosthesis is lower than 260 MPa, while localized Tresca stress is in the order of the yield strength of Ti-6Al-4V alloy for double and triple taper stem design.

  10. Effects of Prosthesis Stem Tapers on Stress Distribution of Cemented Hip Arthroplasty

    NASA Astrophysics Data System (ADS)

    Abdullah, Abdul Halim; Nor, Mohd Asri Mohd; Saman, Alias Mohd; Tamin, Mohd Nasir; Kadir, Mohammed Rafiq Abdul

    2010-10-01

    Aseptic loosening effects are critical issues in encouraging long term stability of cemented hip arthroplasty. Stress shielding is believed to be an important factor that contributes to the aseptic loosening problems. The numerous changes in the prosthesis stem design are intended to minimize the stress shielding and aseptic loosening problems and to improve the long term performance of the implants. In this study, the stress distribution in cemented hip arthroplasty is established using finite element method. The taper of the prosthesis is designed to be 3° at anterior/posterior, 3° at medial/lateral and 10° from wide lateral to narrow medial. Major muscle loads and contact forces are simulated for walking (toe-off phase) and stair climbing load cases. Effects of prosthesis stem tapers on the resulting stress distribution are investigated. Results show that compressive stress dominates in the medial plane while tensile stress in the lateral plane of the femur. The corresponding stress levels of intact femur for walking and stair-climbing load cases are 22 and 29 MPa, respectively. The magnitude of Tresca stress for the THA femur in stair-climbing load case remains higher in the region of 85 MPa while the walking load case induces around 40 MPa. The stress range in the straight and single taper stem prosthesis is lower than 260 MPa, while localized Tresca stress is in the order of the yield strength of Ti-6Al-4V alloy for double and triple taper stem design.

  11. Risk Factors for Subsidence of a Modular Tapered Femoral Stem Used for Revision Total Hip Arthroplasty.

    PubMed

    Tangsataporn, Suksan; Safir, Oleg A; Vincent, Alexander D; Abdelbary, Hesham; Gross, Allan E; Kuzyk, Paul R T

    2015-06-01

    The purpose of this study was to determine the incidence, and the clinical and radiographic risk factors for significant subsidence of a cementless, modular tapered revision femoral stem. Femoral stem subsidence of at least 10 mm or subsidence requiring revision was considered significant subsidence. Ninety-seven patients (99 hips) were included with minimum radiographic follow-up of one year (mean 34 months; range, 12-91 months). The mean stem subsidence was 4.5 mm (range, 0-44 mm). Fourteen out of 99 (14.1%) stems had significant subsidence and 6 (6.1%) stems required revision due to subsidence. Patient weight greater than 80 kg (P=0.04) and femoral stem press-fit distance of less than 2 cm (P<0.01) were both independent risk factors for significant stem subsidence.

  12. Modeling of stem taper models for Chamaecyparis obtusa in Jeju Island, Korea

    NASA Astrophysics Data System (ADS)

    SungCheol, Jung; YeonOk, Seo; Roscinto ian, Lumbres; SeongYoun, Lee; ChanSoo, Kim

    2016-04-01

    This study was conducted to fit the different commonly used stem taper models in predicting the diameter over bark at any given height (d) and total volume of Chamaecyparis obtusa in Jeju Island, Korea. The performance of the stem taper models were evaluated using four fit statistics and these were standard error of estimate (SEE), mean bias ( PIC ), absolute mean difference (AMD), and coefficient of determination (R2). Lack-of-fit statistics were also determine and in this study, SEE, AMD and PIC of the different models in predicting d in the different relative height classes and in predicting the total volume in the different diameter at breast height (DBH) classes were calculated. Results showed that the Kozak model 02 stem taper had the best performance in all fit statistics with SEE of 1.3327, PIC of 0.0020 cm, AMD of 0.9970 cm and R2of 0.9958. Based on the lack of fit statistics, this model also showed a good performance in predicting d in most of the relative height classes and in estimating the total volume in the different DBH classes. The result of this study could help forest managers to determine the d, merchantable stem volumes and total stem volumes of Chamaecyparis obtusa in Jeju Island, Korea.

  13. Femoral revision with taper stems: results at ten years follow-up.

    PubMed

    Cherubino, Paolo; Fagetti, Alessandro; D'Angelo, Fabio; Surace, Michele Francesco

    2010-10-01

    In the case of extensively damaged meta-diaphyseal femoral bone with cortices thinning and widened femoral canal, tapered stems allow a good primary fixation and early weight-bearing. A retrospective review was conducted to evaluate long-term results of modular revision taper stems implanted from March 1999 to December 2002. Sixty-five consecutive hip revision surgeries were performed, mostly for aseptic loosening (75% of the cases). Femoral bone stock defects were classified according to AAOS's criteria and consisted mainly in type II (cavitary defects, 44.6%) and type III (combined defects, 33.9%). A trochanteric osteotomy was performed in 25 cases (38%) to remove primary implants that were cemented in 35 cases (54%). The mean postoperative follow-up was 109 months (range, 76 to 131 months). Clinical assessment at follow-up showed a significantly improved mean Harris Hip Score from 42 points preoperatively to 81 points postoperatively, while the x-ray examination did show a satisfactory distal integration of the stem in all cases and satisfactory reconstitution of the femoral bone stock in 47% of cases. The average subsidence of the stem at follow-up was less than one millimeter. According to data analysis, a leg-length discrepancy exceeding 15 millimeters caused significantly worse functional outcome and pain.

  14. Development of a stem taper equation and modelling the effect of stand density on taper for Chinese fir plantations in Southern China

    PubMed Central

    Zhang, Sensen; Zhang, Xiongqing

    2016-01-01

    Chinese fir (Cunninghamia lanceolata) is the most important commercial tree species in southern China. The objective of this study was to develop a variable taper equation for Chinese fir, and to quantify the effects of stand planting density on stem taper in Chinese fir. Five equations were fitted or evaluated using the diameter-height data from 293 Chinese fir trees sampled from stands with four different densities in Fenyi County, Jiangxi Province, in southern China. A total of 183 trees were randomly selected for the model development, with the remaining 110 trees used for model evaluation. The results show that the Kozak’s, Sharma/Oderwald, Sharma/Zhang and modified Brink’s equations are superior to the Pain/Boyer equation in terms of the fitting and validation statistics, and the modified Brink’s and Sharma/Zhang equations should be recommended for use as taper equations for Chinese fir because of their high accuracy and variable exponent. The relationships between some parameters of the three selected equations and stand planting densities can be built by adopting some simple mathematical functions to examine the effects of stand planting density on tree taper. The modelling and prediction precision of the three taper equations were compared with or without incorporation of the stand density variable. The predictive accuracy of the model was improved by including the stand density variable and the mean absolute bias of the modified Brink’s and Sharma/Zhang equations with a stand density variable were all below 1.0 cm in the study area. The modelling results showed that the trees have larger butt diameters and more taper when stand density was lower than at higher stand density. PMID:27168964

  15. Fitting and Calibrating a Multilevel Mixed-Effects Stem Taper Model for Maritime Pine in NW Spain.

    PubMed

    Arias-Rodil, Manuel; Castedo-Dorado, Fernando; Cámara-Obregón, Asunción; Diéguez-Aranda, Ulises

    2015-01-01

    Stem taper data are usually hierarchical (several measurements per tree, and several trees per plot), making application of a multilevel mixed-effects modelling approach essential. However, correlation between trees in the same plot/stand has often been ignored in previous studies. Fitting and calibration of a variable-exponent stem taper function were conducted using data from 420 trees felled in even-aged maritime pine (Pinus pinaster Ait.) stands in NW Spain. In the fitting step, the tree level explained much more variability than the plot level, and therefore calibration at plot level was omitted. Several stem heights were evaluated for measurement of the additional diameter needed for calibration at tree level. Calibration with an additional diameter measured at between 40 and 60% of total tree height showed the greatest improvement in volume and diameter predictions. If additional diameter measurement is not available, the fixed-effects model fitted by the ordinary least squares technique should be used. Finally, we also evaluated how the expansion of parameters with random effects affects the stem taper prediction, as we consider this a key question when applying the mixed-effects modelling approach to taper equations. The results showed that correlation between random effects should be taken into account when assessing the influence of random effects in stem taper prediction.

  16. Fitting and Calibrating a Multilevel Mixed-Effects Stem Taper Model for Maritime Pine in NW Spain

    PubMed Central

    Arias-Rodil, Manuel; Castedo-Dorado, Fernando; Cámara-Obregón, Asunción; Diéguez-Aranda, Ulises

    2015-01-01

    Stem taper data are usually hierarchical (several measurements per tree, and several trees per plot), making application of a multilevel mixed-effects modelling approach essential. However, correlation between trees in the same plot/stand has often been ignored in previous studies. Fitting and calibration of a variable-exponent stem taper function were conducted using data from 420 trees felled in even-aged maritime pine (Pinus pinaster Ait.) stands in NW Spain. In the fitting step, the tree level explained much more variability than the plot level, and therefore calibration at plot level was omitted. Several stem heights were evaluated for measurement of the additional diameter needed for calibration at tree level. Calibration with an additional diameter measured at between 40 and 60% of total tree height showed the greatest improvement in volume and diameter predictions. If additional diameter measurement is not available, the fixed-effects model fitted by the ordinary least squares technique should be used. Finally, we also evaluated how the expansion of parameters with random effects affects the stem taper prediction, as we consider this a key question when applying the mixed-effects modelling approach to taper equations. The results showed that correlation between random effects should be taken into account when assessing the influence of random effects in stem taper prediction. PMID:26630156

  17. Elevated Serum Titanium Level as a Marker for Failure in a Titanium Modular Fluted Tapered Stem.

    PubMed

    McAlister, Ian P; Abdel, Matthew P

    2016-07-01

    Serum ion concentrations of cobalt and chromium are commonly used to monitor for the development of local metal reactions in metal-on-metal total hip arthroplasties, as well as dual-modular constructs. Although rarely used in clinical practice, elevated serum titanium levels have the ability to indicate a failure with contemporary revision constructs, such as with titanium modular fluted tapered (TMFT) stems. The authors report the case of a 64-year-old man with a TMFT stem after revision total hip arthroplasty for a dual-modular neck construct who had set screw disengagement with subsequent proximal body loosening. The patient's serum cobalt and chromium levels were normal, but he had a markedly elevated serum titanium level, indicating failure of the titanium modular junction. Implant failures at modular junctions in femoral components are well described. Although several different failure mechanisms have been defined, to the authors' knowledge this is the first reported failure of this particular TMFT stem. In addition, this is the first report describing the use of serum titanium levels in identifying a novel failure mechanism. With the popularity of this stem, surgeons should be aware that an elevated serum titanium level may aid in the diagnosis of this unique complication. [Orthopedics. 2016; 39(4):e768-e770.].

  18. Effect of femoral canal shape on mechanical stress distribution and adaptive bone remodelling around a cementless tapered-wedge stem

    PubMed Central

    Oba, M.; Kobayashi, N.; Ike, H.; Tezuka, T.; Saito, T.

    2016-01-01

    Objectives In total hip arthroplasty (THA), the cementless, tapered-wedge stem design contributes to achieving initial stability and providing optimal load transfer in the proximal femur. However, loading conditions on the femur following THA are also influenced by femoral structure. Therefore, we determined the effects of tapered-wedge stems on the load distribution of the femur using subject-specific finite element models of femurs with various canal shapes. Patients and Methods We studied 20 femurs, including seven champagne flute-type femurs, five stovepipe-type femurs, and eight intermediate-type femurs, in patients who had undergone cementless THA using the Accolade TMZF stem at our institution. Subject–specific finite element (FE) models of pre- and post-operative femurs with stems were constructed and used to perform FE analyses (FEAs) to simulate single-leg stance. FEA predictions were compared with changes in bone mineral density (BMD) measured for each patient during the first post-operative year. Results Stovepipe models implanted with large-size stems had significantly lower equivalent stress on the proximal-medial area of the femur compared with champagne-flute and intermediate models, with a significant loss of BMD in the corresponding area at one year post-operatively. Conclusions The stovepipe femurs required a large-size stem to obtain an optimal fit of the stem. The FEA result and post-operative BMD change of the femur suggest that the combination of a large-size Accolade TMZF stem and stovepipe femur may be associated with proximal stress shielding. Cite this article: M. Oba, Y. Inaba, N. Kobayashi, H. Ike, T. Tezuka, T. Saito. Effect of femoral canal shape on mechanical stress distribution and adaptive bone remodelling around a cementless tapered-wedge stem. Bone Joint Res 2016;5:362–369. DOI: 10.1302/2046-3758.59.2000525. PMID:27601435

  19. Assembly force and taper angle difference influence the relative motion at the stem-neck interface of bi-modular hip prostheses.

    PubMed

    Haschke, Henning; Jauch-Matt, Sabrina Y; Sellenschloh, Kay; Huber, Gerd; Morlock, Michael M

    2016-07-01

    Bi-modular hip arthroplasty prostheses allow adaptation to the individual patient anatomy and the combination of different materials but introduce an additional interface, which was related lately to current clinical issues. Relative motion at the additional taper interface might increase the overall risk of fretting, corrosion, metallic debris and early failure. The aim of this study was to investigate whether the assembly force influences the relative motion and seating behaviour at the stem-neck interface of a bi-modular hip prosthesis (Metha(®); Aesculap AG, Tuttlingen, Germany) and whether this relation is influenced by the taper angle difference between male and female taper angles. Neck adapters made of titanium (Ti6Al4V) and CoCr (CoCr29Mo) were assembled with a titanium stem using varying assembly forces and mechanically loaded. A contactless eddy current measurement system was used to record the relative motion between prosthesis stem and neck adapter. Higher relative motion was observed for Ti neck adapters compared to the CoCr ones (p < 0.001). Higher assembly forces caused increased seating distances (p < 0.001) and led to significantly reduced relative motion (p = 0.019). Independent of neck material type, prostheses with larger taper angle difference between male and female taper angles exhibited decreased relative motion (p < 0.001). Surgeons should carefully use assembly forces above 4 kN to decrease the amount of relative motion within the taper interface. Maximum assembly forces, however, should be limited to prevent periprosthetic fractures. Manufacturers should optimize taper angle differences to increase the resistance against relative motion.

  20. In vivo oxide-induced stress corrosion cracking of Ti-6Al-4V in a neck-stem modular taper: Emergent behavior in a new mechanism of in vivo corrosion.

    PubMed

    Gilbert, Jeremy L; Mali, Sachin; Urban, Robert M; Silverton, Craig D; Jacobs, Joshua J

    2012-02-01

    In vivo modular taper corrosion in orthopedic total joint replacements has been documented to occur for head-neck tapers, modular-body tapers, and neck-stem tapers. While the fretting corrosion mechanism by which this corrosion occurs has been described in the literature, this report shows new and as yet unreported mechanisms at play. A retrieved Ti-6Al-4V/Ti-6Al-4V neck-stem taper interface, implanted for 6 years is subjected to failure analysis to document taper corrosion processes that lead to oxide driven crack formation on the medial side of the taper. Metallurgical sectioning techniques and scanning electron microscopy analysis are used to document the taper corrosion processes. The results show large penetrating pitting attack of both sides of the taper interface where corrosion selectively attacks the beta phase of the microstructure and eventually consumes the alpha phase. The pitting attack evolves into plunging pits that ultimately develop into cracks where the crack propagation process is one of corrosion resulting in oxide formation and subsequent reorganization. This process drives open the crack and advances the front by a combination of oxide-driven crack opening stresses and corrosion attack at the tip. The oxide that forms has a complex evolving structure including a network of transport channels that provide access of fluid to the crack tip. This emergent behavior does not appear to require continued fretting corrosion to propagate the pitting and cracking. This new mechanism is similar to stress corrosion cracking where the crack tip stresses arise from the oxide formation in the crack and not externally applied tensile stresses.

  1. Tapered triumph

    NASA Astrophysics Data System (ADS)

    2009-01-01

    German company M2K Laser was the first in the world to successfully commercialize tapered diode lasers, and is currently the only one making gallium antimonide devices. The company's managing director speaks to Nadya Anscombe about its strategy and future.

  2. A comparison of subsidence of Exeter standard and long stems.

    PubMed

    Davis, Edward T; Heaver, Catriona E; Pynsent, Paul B; Pearson, Andrew M; Treacy, Ronan B C

    2010-01-01

    The survivorship of the polished, double taper Exeter stem is related to subsidence within the cement mantle. Long Exeter stems have altered geometry which may influence subsidence characteristics. Using digitised x-rays and appropriate computer software we measured the subsidence of 35 standard and 40 long stem Exeter implants. Measurements were taken from initial postoperative radiographs and repeated at intervals up to 5 years. Long stem implants were used in cemented revisions without the use of impaction bone grafting. Subsidence rates of the standard length stems in our study were comparable to that in published literature. Long stems did not replicate this subsidence pattern and had subsided less at 6, 12 and 24 months. However, the 205mm long stem, which has a fully tapered design, did follow the subsidence characteristics of the standard stem. Subsidence of long stem Exeter implants does not mirror that of the standard length stem. Loss of the fully tapered geometry of the longer stem implants may account for this finding. We suggest that whenever possible, the 205mm long stem should be used if the biomechanical principles of the standard Exeter stem are to be utilised.

  3. Experimental Measurement of the Static Coefficient of Friction at the Ti-Ti Taper Connection in Total Hip Arthroplasty.

    PubMed

    Bitter, T; Khan, I; Marriott, T; Schreurs, B W; Verdonschot, N; Janssen, D

    2016-03-01

    The modular taper junction in total hip replacements has been implicated as a possible source of wear. The finite-element (FE) method can be used to study the wear potential at the taper junction. For such simulations it is important to implement representative contact parameters, in order to achieve accurate results. One of the main parameters in FE simulations is the coefficient of friction. However, in current literature, there is quite a wide spread in coefficient of friction values (0.15 - 0.8), which has a significant effect on the outcome of the FE simulations. Therefore, to obtain more accurate results, one should use a coefficient of friction that is determined for the specific material couple being analyzed. In this study, the static coefficient of friction was determined for two types of titanium-on-titanium stem-adaptor couples, using actual cut-outs of the final implants, to ensure that the coefficient of friction was determined consistently for the actual implant material and surface finish characteristics. Two types of tapers were examined, Biomet type-1 and 12/14, where type-1 has a polished surface finish and the 12/14 is a microgrooved system. We found static coefficients of friction of 0.19 and 0.29 for the 12/14 and type-1 stem-adaptor couples, respectively.

  4. Tapered structure construction

    SciTech Connect

    Smith, Eric D.; Takata, Rosalind K.; Slocum, Alexander H.; Nayfeh, Samir A.

    2016-04-05

    Feeding stock used to form a tapered structure into a curving device such that each point on the stock undergoes rotational motion about a peak location of the tapered structure; and the stock meets a predecessor portion of stock along one or more adjacent edges.

  5. Bone creep and short and long term subsidence after cemented stem total hip arthroplasty (THA).

    PubMed

    Norman, T L; Shultz, T; Noble, G; Gruen, T A; Blaha, J D

    2013-03-15

    Stem-cement and cement-bone interfacial failures as well as cement fractures have been noted in cemented total hip arthroplasty (THA) as the cause of aseptic loosening. Attempts to reduce the risk of femoral component loosening include improving the stem-cement interface by various coatings, using a textured or porous coated stem surfaces or by using a tapered stem having a highly-polished surface. The latter approach, often referred to as "force-closed" femoral stem design, would theoretically result in stem stabilization subsequent to debonding and 'taper-lock'. Previous work using three-dimensional finite element analysis has shown a state of stress at the stem-cement interface indicative of 'taper-lock' for the debonded stem and indicated that stem-cement interface friction and bone cement creep played a significant role in the magnitudes of stresses and subsidence of the stem. However, the previous analysis did not include the viscoelastic properties of bone, which has been hypothesized to permit additional expansion of the bone canal and allow additional stem subsidence (Lu and McKellop, 1997). The goal of this study was to investigate the effect of bone viscoelastic behavior on stem subsidence using a 3D finite element analysis. It was hypothesized that the viscoelastic behavior of bone in the hoop direction would allow expansion of the bone reducing the constraint on bone over time and permit additional stem subsidence, which may account for the discrepancies between predicted and clinical subsidence measurements. Analyses were conducted using physiological loads, 'average peak loads' and 'high peak loads' for 'normal patient' and 'active patient' (Bergmann et al., 2010) from which short and long term subsidence was predicted. Results indicated that bone creep does contribute to higher stem subsidence initially and after 10 years of simulated loading. However, it was concluded that the "constraint" upon the cement mantle is not mitigated enough to result in

  6. Long-term results using the straight tapered femoral cementless hip stem in total hip arthroplasty: a minimum of twenty-year follow-up.

    PubMed

    Ateschrang, Atesch; Weise, Kuno; Weller, Siegfried; Stöckle, Ulrich; de Zwart, Peter; Ochs, Björn Gunnar

    2014-08-01

    We report the first long-term results of a prospective cohort study after total hip arthroplasty using the cementless Bicontact hip stem. Between 1987 and 1990, 250 total hip arthroplasties in 236 patients were performed using the cementless Bicontact hip stem. The average follow-up was 22.8 years (20.4-24.8) and average age at index surgery was 58.1 years. Eighty-one patients died and 9 were lost to follow-up. We noted 11 stem revisions revealing an overall Kaplan Meier survival rate of 95.0% (CI 95%: 91.1-97.2%). The average Harris Hip Score revealed 81 points (range 24-93). The Bicontact hip stem demonstrated high survival rates despite high ages and osteopenic changes, which are equivalent to other long-term reports of cementless stem fixation.

  7. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    Lapointe, Donat J. E. (Inventor); Wright, Lawrence T. (Inventor); Vincent, Laurence J. (Inventor)

    1987-01-01

    A tapered tubular polyester sleeve is described to serve as the flexible foundation for a spacesuit limb covering. The tube has a large end and a small end with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end. A requisite number of warp yarns extend the full length of the sleeve. Other warp yarns extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel, heated in an oven, and then attached to the arm or other limb of the spacesuit.

  8. Tapered, tubular polyester fabric

    NASA Technical Reports Server (NTRS)

    LaPointe, Donat J. E. (Inventor); Vincent, Laurence J. (Inventor); Wright, Lawrence T. (Inventor)

    1988-01-01

    A tapered tubular polyester sleeve as set forth. It has a large end 12 and a small end 14 with a length to be determined. The ratio of taper is also determined by scale factors. All the warp yarns extend to the large end 12. A requisite number of warp yarns 16 extend the full length of the sleeve. Other warp yarns exemplified at 18, 22, 26, 28, 30 and 32 extend from the large end but are terminated along the length of the sleeve. It is then woven with a filling yarn 40 which extends in a full circle along the full length of the sleeve to thereby define the tapered sleeve. The sleeve after fabrication is then placed on a mandrel 42, heated in an oven 44 and is thereafter placed on the arm or other limb of a space suit exemplified at 50.

  9. Ultrasonic Polishing

    NASA Technical Reports Server (NTRS)

    Gilmore, Randy

    1993-01-01

    The ultrasonic polishing process makes use of the high-frequency (ultrasonic) vibrations of an abradable tool which automatically conforms to the work piece and an abrasive slurry to finish surfaces and edges on complex, highly detailed, close tolerance cavities in materials from beryllium copper to carbide. Applications range from critical deburring of guidance system components to removing EDM recast layers from aircraft engine components to polishing molds for forming carbide cutting tool inserts or injection molding plastics. A variety of materials including tool steels, carbides, and even ceramics can be successfully processed. Since the abradable tool automatically conforms to the work piece geometry, the ultrasonic finishing method described offers a number of important benefits in finishing components with complex geometries.

  10. Compound taper milling machine

    NASA Technical Reports Server (NTRS)

    Campbell, N. R.

    1969-01-01

    Simple, inexpensive milling machine tapers panels from a common apex to a uniform height at panel edge regardless of the panel perimeter configuration. The machine consists of an adjustable angled beam upon which the milling tool moves back and forth above a rotatable table upon which the workpiece is held.

  11. Tapered capillary optics

    DOEpatents

    Hirsch, Gregory

    1998-01-01

    A metal or glass wire is etched with great precision into a very narrowly tapering cone which has the shape of the desired final capillary-optics bore. By controlling the rate of removal of the wire from an etchant bath, a carefully controlled taper is produced. A sensor measures the diameter of the wire as it leaves the surface of the etchant. This signal is used for feedback control of the withdrawal speed. The etched wire undergoes a treatment to produce an extremely low surface-roughness. The etched and smoothed wire is coated with the material of choice for optimizing the reflectivity of the radiation being focused. This could be a vacuum evaporation, sputtering, CVD or aqueous chemical process. The coated wire is either electroplated, built up with electroless plating, or encapsulated in a polymer cylinder such as epoxy to increase the diameter of the wire for easier handling and greater robustness. During this process, the wire is vertically oriented and tensioned to assure that the wire is absolutely straight. The coated and electroformed wire is bonded to a flat, rigid substrate and is then periodically segmented by cutting or etching a series of narrow slits or grooves into the wire. The wire is vertically oriented and tensioned during the bonding process to assure that it is straight. The original wire material is then chemically etched away through the slits or otherwise withdrawn to leave the hollow internal bore of the final tapered-capillary optical element.

  12. Endfire tapered slot antenna characteristics

    NASA Technical Reports Server (NTRS)

    Schaubert, D. H.

    1989-01-01

    Typical configurations and operating characteristics for endfire tapered slot antennas are described. The feed transition modeling and moment method modeling techniques are utilized to predict antenna performance. The radiation pattern and cross polarization properties for the linearly tapered slot antennas are examined. Endfire tapered slot antennas are applicable for wide-band scanning arrays and focal plane arrays for imaging and multiple beam reflector systems.

  13. Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil.

    PubMed

    Nunes, Matheus Henrique; Görgens, Eric Bastos

    2016-01-01

    Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects.

  14. Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil

    PubMed Central

    Nunes, Matheus Henrique

    2016-01-01

    Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects. PMID:27187074

  15. Tapered undulator for SASE FELs

    SciTech Connect

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2001-09-14

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).

  16. Head-Neck Taper Corrosion in Hip Arthroplasty

    PubMed Central

    Hussenbocus, S.; Kosuge, D.; Solomon, L. B.; Howie, D. W.; Oskouei, R. H.

    2015-01-01

    Modularity at the head-neck junction of the femoral component in THA became popular as a design feature with advantages of decreasing implant inventory and allowing adjustment of leg length, offset, and soft tissue balancing through different head options. The introduction of a new modular interface to femoral stems that were previously monoblock, or nonmodular, comes with the potential for corrosion at the taper junction through mechanically assisted crevice corrosion. The incidence of revision hip arthroplasty is on the rise and along with improved wear properties of polyethylene and ceramic, use of larger femoral head sizes is becoming increasingly popular. Taper corrosion appears to be related to all of its geometric parameters, material combinations, and femoral head size. This review article discusses the pathogenesis, risk factors, clinical assessment, and management of taper corrosion at the head-neck junction. PMID:25954757

  17. Tapered undulators for SASE FELs

    NASA Astrophysics Data System (ADS)

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2002-05-01

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission, where the radiation tends to have a relatively broad bandwidth and limited temporal coherence. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of tapered undulators for parameters corresponding to the Argonne low-energy undulator test line FEL and the proposed linac coherent light source.

  18. Effect of trunnion roughness and length on the modular taper junction strength under typical intraoperative assembly forces.

    PubMed

    Jauch-Matt, S Y; Miles, A W; Gill, H S

    2017-01-01

    Modular hip implants are at risk of fretting-induced postoperative complications most likely initiated by micromotion between adjacent implant components. A stable fixation between ball head and stem-neck taper is critical to avoid excessive interface motions. Therefore, the aim of this study was to identify the effect of trunnion roughness and length on the modular taper strength under typical intraoperative assembly forces. Custom-made Titanium trunnions (standard/mini taper, smooth/grooved surface finish) were assembled with modular Cobalt-chromium heads by impaction with peak forces ranging from 2kN to 6kN. After each assembly process these were disassembled with a materials testing machine to detect the pull-off force as a measure for the taper strength. As expected, the pull-off forces increased with rising peak assembly force (p < 0.001). For low and moderate assembly forces, smooth standard tapers offered higher pull-off forces compared to grooved tapers (p < 0.038). In the case of an assembly force of 2kN, mini tapers showed a higher taper strength than standard ones (p=0.037). The results of this study showed that smooth tapers provided a higher strength for taper junctions. This higher taper strength may reduce the risk of fretting-related complications especially in the most common range of intraoperative assembly forces.

  19. EPRI condensate polisher guidelines

    SciTech Connect

    Larkin, B.A.; Webb, L.C.; Sawochka, S.G.; Crits, G.J.; Pocock, F.J.; Wirth, L.

    1995-01-01

    Cycle chemistry is one of the most important contributors to the loss of availability of generating units. Condensate polishing can significantly improve cycle chemistry by improving cycle water quality and minimizing the transport of contaminants in the power cycle. The EPRI-funded project described in this paper developed comprehensive guidelines for condensate polishing based upon information gathered from utility surveys, equipment vendors, and resin suppliers. Existing literature was also surveyed for pertinent input. Comprehensive guidelines which outline guidance for design, operation, maintenance, surveillance, management, and retrofitting of condensate polishing systems were developed. Economics of condensate polishing were evaluated and a roadmap for economic evaluation for utilities to follow was produced.

  20. Communicating in Polish.

    ERIC Educational Resources Information Center

    Penny, Bernard; Malinowska, Krystyna T.

    This Polish textbook consists of a series of narrations and dialogs based on photographs depicting typical activities in the daily lives of Polish citizens. Two sets of questions follow each selection; the first set is intended to stimulate communication on what has been seen and heard, while the second set asks the students to compare what they…

  1. Polish Literature in Exile.

    ERIC Educational Resources Information Center

    Zielinska, Marie F.

    1994-01-01

    Presents a brief historical overview of the development of Polish literature in exile with emphasis on publishing. The upheaval of World War II left many Poles outside their native land. They have created a flourishing press and literature, with 21 Polish houses outside of Poland and other active presses. (SLD)

  2. Tapered optical fibres for sensing

    NASA Astrophysics Data System (ADS)

    Martan, Tomas; Kanka, Jiri; Kasik, Ivan; Matejec, Vlastimil

    2008-11-01

    Recently, optical fibre tapers have intensively been investigated for many applications e.g. in telecommunications, medicine and (bio-) chemical sensing. The paper deals with enhancement of evanescent-field sensitivity of the solid-core microstructured fibre with steering-wheel air-cladding. Enhancement of a performance of the microstructured fibre is based on reduction of fibre core diameter down to narrow filament by tapering thereby defined part of light power is guided by an evanescent wave traveling in axial cladding air holes. The original fibre structure with outer diameter of 125 µm was reduced 2×, 2.5×, 3.33×, and 4× for increasing relatively small intensity overlap of guided core mode at wavelength of 1.55 μm with axial air holes. The inner structures of tapered microstructured fibre with steering-wheel aircladding were numerically analyzed and mode intensity distributions were calculated using the FDTD technique. Analyzed fiber tapers were prepared by constructed fibre puller employing 'flame brush technique'.

  3. Tapered laser rods as a means of minimizing the path length of trapped barrel mode rays

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Payne, Stephen A.; Mercer, Ian; Perry, Michael D.

    2005-08-30

    By tapering the diameter of a flanged barrel laser rod over its length, the maximum trapped path length of a barrel mode can be dramatically reduced, thereby reducing the ability of the trapped spontaneous emission to negatively impact laser performance through amplified spontaneous emission (ASE). Laser rods with polished barrels and flanged end caps have found increasing application in diode array end-pumped laser systems. The polished barrel of the rod serves to confine diode array pump light within the rod. In systems utilizing an end-pumping geometry and such polished barrel laser rods, the pump light that is introduced into one or both ends of the laser rod, is ducted down the length of the rod via the total internal reflections (TIRs) that occur when the light strikes the rod's barrel. A disadvantage of using polished barrel laser rods is that such rods are very susceptible to barrel mode paths that can trap spontaneous emission over long path lengths. This trapped spontaneous emission can then be amplified through stimulated emission resulting in a situation where the stored energy available to the desired lasing mode is effectively depleted, which then negatively impacts the laser's performance, a result that is effectively reduced by introducing a taper onto the laser rod.

  4. Rediscovery of Polish meteorites

    NASA Astrophysics Data System (ADS)

    Tymiński, Z.; Stolarz, M.; Żołądek, P.; Wiśniewski, M.; Olech, A.

    2016-01-01

    The total number of Polish registered meteorites (by July 2016) including the meteoritical artifacts as Czestochowa Raków I and II is 22. Most of them are described by the pioneer of Polish Meteoritics Jerzy Pokrzywnicki who also identified the meteorite fall locations. In recent years prospectors found impressive specimens of known Polish meteorites such as Morasko: 34 kg, 50 kg, 164 kg, 174 kg and 261 kg or Pultusk: 1578 g, 1576 g, 1510 g, 610 g and 580 g expanding and determining precisely the known meteorite strewn fields.

  5. Thread gauge for tapered threads

    DOEpatents

    Brewster, Albert L.

    1994-01-11

    The thread gauge permits the user to determine the pitch diameter of tapered threads at the intersection of the pitch cone and the end face of the object being measured. A pair of opposed anvils having lines of threads which match the configuration and taper of the threads on the part being measured are brought into meshing engagement with the threads on opposite sides of the part. The anvils are located linearly into their proper positions by stop fingers on the anvils that are brought into abutting engagement with the end face of the part. This places predetermined reference points of the pitch cone of the thread anvils in registration with corresponding points on the end face of the part being measured, resulting in an accurate determination of the pitch diameter at that location. The thread anvils can be arranged for measuring either internal or external threads.

  6. Thread gauge for tapered threads

    DOEpatents

    Brewster, A.L.

    1994-01-11

    The thread gauge permits the user to determine the pitch diameter of tapered threads at the intersection of the pitch cone and the end face of the object being measured. A pair of opposed anvils having lines of threads which match the configuration and taper of the threads on the part being measured are brought into meshing engagement with the threads on opposite sides of the part. The anvils are located linearly into their proper positions by stop fingers on the anvils that are brought into abutting engagement with the end face of the part. This places predetermined reference points of the pitch cone of the thread anvils in registration with corresponding points on the end face of the part being measured, resulting in an accurate determination of the pitch diameter at that location. The thread anvils can be arranged for measuring either internal or external threads. 13 figures.

  7. Fracture of the C-Stem cemented femoral component in revision hip surgery using bone impaction grafting technique: report of 9 cases.

    PubMed

    Buttaro, Martin; Comba, Fernando; Zanotti, Gerardo; Piccaluga, Francisco

    2015-01-01

    We present a series of 9 fractures of a C-Stem femoral component (6 long stems and 3 conventional stems) that had been implanted with the use of impaction bone grafting (IBG). The length of the long fractured stems was 240 mm in 4 cases and 200 mm in 2. The patients presented had an average BMI of 26.5 and an average of 2.7 previous hip surgeries (range 2-5 surgeries) before the stem fracture. A total of 5 cases presented with a metal mesh fracture in addition to the fractured stem. Bending of the stems or stem defects was not observed in any case. Typical fracture waves consistent with fatigue failure were clearly visible on all the cut surfaces, starting anterolaterally and propagating to the medial side. Although fatigue fracture of a modern cemented tapered polished femoral stem is a rare event, stress due to the absence of proximal femoral bone support could be sufficient to put this stem at a higher risk for fatigue fracture in non-obese patients.

  8. Polished polymide substrate

    DOEpatents

    Farah, John; Sudarshanam, Venkatapuram S.

    2003-05-13

    Polymer substrates, in particular polyimide substrates, and polymer laminates for optical applications are described. Polyimide substrates are polished on one or both sides depending on their thickness, and single-layer or multi-layer waveguide structures are deposited on the polished polyimide substrates. Optical waveguide devices are machined by laser ablation using a combination of IR and UV lasers. A waveguide-fiber coupler with a laser-machined groove for retaining the fiber is also disclosed.

  9. Theory and Simulations of Tapered Diblock Polymers

    NASA Astrophysics Data System (ADS)

    Hall, Lisa M.; Seo, Youngmi; Brown, Jonathan R.

    We study tapered block polymers, AB diblock polymers with a gradient region inserted between the pure A and B blocks such that composition smoothly transitions from A to B (or B to A in the case of inverse tapers). Phase diagrams were created using self consistent field theory (SCFT), and coarse-grained molecular dynamics (MD) simulations were used to study polymer conformations and diffusion, including diffusion of monomer-sized penetrants preferentially dissolved in one of the phases. As has been observed experimentally, we find that tapering makes the A and B blocks more miscible, decreasing domain spacing and shifting the order to disorder transition to lower temperatures. We predict a widening of the bicontinuous double gyroid region of the phase diagram for moderate length normal tapers versus diblocks, suggesting taper length can be used as a control parameter to obtain network phases even at high molecular weight, as may be desirable in transport applications. Additionally, in some inverse tapered systems, SCFT predicts phases not present in the standard AB diblock phase diagram, and MD simulations show how the chains fold back and forth across the interface. In these inverse tapered polymers, as segregation strength is increased, the competing effects of folding and stretching produces lamellae that have domain spacing nearly independent of temperature. We also find that diffusion of penetrants in normal tapers is significantly faster than that in inverse tapers, which is likely related to their unusual conformations. This material is based upon work supported by DOE Grant SC0014209.

  10. Identification of the class characteristics in the handwriting of Polish people writing in English.

    PubMed

    Turnbull, Susan J; Jones, Allison E; Allen, Mike

    2010-09-01

    An investigation was carried out to identify the class characteristics of Polish people writing in English and to specifically identify those characteristics that separate Polish handwriting from English handwriting. In the first stage, 40 Polish and 40 English handwriting samples were collected and systematically examined. In total, 31 features were identified that occurred in ≥25% of the Polish handwriting samples and therefore considered class characteristics. Of these, chi-square analyses identified 21 class characteristics that occurred significantly more in Polish compared to English handwriting. Twenty-one of the class characteristics in the Polish handwriting had similar constructions to the copybook pattern thus supporting the theory that class characteristics frequently stem from the taught writing system. In the second stage, an algorithm was developed using seventeen of the class characteristics that successfully discriminated between a further 13 Polish and 12 English handwriting samples.

  11. Analysis of the polishing slurry flow of chemical mechanical polishing by polishing pad with phyllotactic pattern

    NASA Astrophysics Data System (ADS)

    Lv, Yushan; Zhang, Tian; Wang, Jun; Li, Nan; Duan, Min; Xing, Xue-Ling

    2010-12-01

    In order to make the polishing slurry distribution more uniform over the polishing region, a new kind of polishing pad, which has sunflower seed pattern, has been designed based on the phyllotaxis theory of biology, and the boundary conditions of polishing slurry flow have been established. By the help of computational fluid dynamics software (FLUENT), the flow state of the polishing slurry is simulated and the effects of the phyllotactic parameters of polishing pad on the flow field of polishing slurry are analyzed. The results show that when the polishing slurry is imported from the center of phyllotaxis polishing pad, the slurry flows along the counterclockwise and clockwise spiral grooves of phyllotatic pattern, which make fluid flow divergence around, and the flow field becomes more uniform.

  12. [Polish nomenclature of lumbar disc disease].

    PubMed

    Radło, Paweł; Smetkowski, Andrzej; Tesiorowski, Maciej

    2014-01-01

    Lumbar disc herniation is one of the most common damage of musculoskeletal system. The incidence of pain of lumbosacral spine is estimated approximately on 60-90% in general population, whereas the incidence of disc herniation in patients experiencing low back pain is about 91%. Despite the high incidence and uncomplicated pathogenesis of disc disease there is a problem with the nomenclature. In the vast majority of cases, the naming confusion stems from ignorance of the etiology of low back pain. Different terminologies: morphological, topographical, Radiological and Clinical are used interchangeably. In addition, diagnosis is presented in a variety of languages: Polish, English and Latin. Moreover, the medical and traditional language are used alternately. The authors found in Polish literature more, than 20 terms to describe lumbar disc herniation. All of these terms in the meaning of the authors are used to determine one pathology--mechanical damage to the intervertebral disc and moving the disc material beyond the anatomical area.

  13. Know Your Laws. Polish.

    ERIC Educational Resources Information Center

    Watson, Joan Q.; Kopania, Margaret

    This Polish language version of "Know Your Laws" consists of 24 self-contained modules designed to acquaint the Florida adult student with laws she/he will meet in everyday life; fundamentals of local, state, and federal governments; and the criminal and juvenile justice systems. (The 130 objectives are categorized in the first three…

  14. Frequency coded sensors incorporating tapers

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor); Solie, Leland P. (Inventor)

    2010-01-01

    A surface acoustic wave device includes a piezoelectric substrate on which is formed a transducer that generates acoustic waves on the surface of the substrate from electrical waves received by the transducer. The waves are carried along an acoustic track to either a second transducer or a reflector. The transducers or transducer and reflector are formed of subsections that are constructed to operate at mutually different frequencies. The subsections of at least one of the transducers or transducer and reflector are out of alignment with respect to one another relative to the transverse of the propagation direction. The out of aligned subsections provide not only a frequency component but also a time to the signal output signal. Frequency response characteristics are improved. An alternative embodiment provides that the transducers and/or reflectors are continuously tapered instead of having discrete frequency subsections.

  15. STEM?!?!

    ERIC Educational Resources Information Center

    Merrill, Jen

    2012-01-01

    The author's son has been an engineer since birth. He never asked "why" as a toddler, it was always "how's it work?" So that he wanted a STEM-based home education was no big surprise. In this article, the author considers what kind of curricula would work best for her complex kid.

  16. Endfire tapered slot antennas on dielectric substrates

    NASA Technical Reports Server (NTRS)

    Yngvesson, K. S.; Schaubert, D. H.; Korzeniowski, T. L.; Kollberg, E. L.; Thungren, T.

    1985-01-01

    Endfire-tapered slot antennas are suitable for many integrated circuit applications, imaging and phased arrays. An investigation of single elements of such antennas, including slots which are exponentially tapered (Vivaldi), linearly tapered, and constant width. For antennas of all types, a good general agreement is obtained for curves of beamwidth-versus-length, normalized to wavelength, when one compares the data with that for traveling-wave antennas published by Zucker (1961). An important condition for this agreement is that the effective dielectric thickness, defined in the text, is in a certain optimum range. This condition is qualitatively explained in terms of the theory for traveling-wave antennas.

  17. Tapered plug foam spray apparatus

    NASA Technical Reports Server (NTRS)

    Allen, Peter B. (Inventor)

    1996-01-01

    A two-component foam spray gun is readily disassembled for cleaning. It includes a body (1) with reactant (12, 14) and purge gas (16) inlet ports. A moldable valve packing (32) inside the body has a tapered conical interior surface (142), and apertures which match the reactant ports. A valve/tip (40) has a conical outer surface (48) which mates with the valve packing (32). The valve/tip (40) is held in place by a moldable packing washer (34), held at non-constant pressure by a screw (36, 38). The interior of the valve/tip (40) houses a removable mixing chamber (50). The mixing chamber (50) has direct flow orifices (60) and an auxiliary flow path (58, 60) which ameliorate pressure surges. The spray gun can be disassembled for cleaning without disturbing the seal, by removing the valve/tip (40) to the rear, thereby breaking it free of the conical packing. Rotation of the valve/tip (40) relative to the body (1) shuts off the reactant flow, and starts the purge gas flow.

  18. Pseudotumour formation due to tribocorrosion at the taper interface of large diameter metal on polymer modular total hip replacements.

    PubMed

    Cook, Richard B; Bolland, Benjamin J R F; Wharton, Julian A; Tilley, Simon; Latham, Jeremy M; Wood, Robert J K

    2013-09-01

    We present an in-depth failure analysis of two large diameter bearing metal-on-polymer (MoP) modular total hip replacements, which have required revision surgery due to pseudotumour formation. The failure analysis showed a discrete pattern of material loss from the distal end of the head taper/stem trunnion interface. We postulate that the use of a proximal contacting taper design had provided insufficient mechanical locking between the head and the stem, enabling the head to toggle on the trunnion. In addition, the difference in angle between the taper and the trunnion formed a crevice between the two components. Through a combination of crevice environment, mechanically assisted corrosion, mechanical wear and erosion; debris and metal-ions have been released resulting in the adverse local tissue reactions (ALTR).

  19. Notions Catalog. Polish Functional Grammar.

    ERIC Educational Resources Information Center

    Woytak, Lidia

    The Polish notions catalog systematizes a variety of informational codes used in Polish, resulting in lists of notions, each presented from a structural perspective. Where applicable, they are accompanied by a morphological component, structural chart, semantic description, frequentative expressions, and related vocabulary items. The notions…

  20. Reading Authentic Polish, Volume II.

    ERIC Educational Resources Information Center

    Walczynski, Waldemar

    The second volume on reading authentic Polish is the continuation of a supplementary textbook to be used either in the classroom or in independent study. The materials included in it are unaltered authentic texts from Polish newspapers, magazines, and other mass media that provide exposure to the context and format of everyday reading matter. The…

  1. Polishing technique for beryllium mirror

    NASA Technical Reports Server (NTRS)

    Froechtenigt, J. F.

    1976-01-01

    Performance tests, accomplished by inserting entire X ray telescope and polished mirror into vacuum line 67 m long and taking photographs of an X ray resolution source, indicate that polishing increases mirror efficiency from 0.06 percent for X rays at 0.8 nm and increases resolution from 15 to 3.75 arc-seconds.

  2. Polish Americans. Second, Revised Edition.

    ERIC Educational Resources Information Center

    Lopata, Helen Znaniecka

    This book examines Polonia, the Polish ethnic community in America created by three giant waves of immigration between 1880 and 1990. The complicated history of this ethnic group is reflected in the lives of increasing numbers of Polish Americans, including recent immigrants brought by political and economic changes, as they achieve middle class…

  3. [Lysenkoism in Polish botany].

    PubMed

    Köhler, Piotr

    2008-01-01

    Lysenkoism in Poland was never an autonomous phenomenon. The whole array of reasons for which it appeared in Polish science would require a separate study--here it only needs to be pointed out that the major reasons included terror on the part of the security service, lawlessness, the ubiquitous atmosphere of intimidation and terror, censorship, the diminishing sphere of civil liberties, political show trials, propaganda and denunciations. An important role in facilitating the introduction of Lysenkoism was played also by the reorganization of science after World War Two, the isolation of Polish science from science in the West, as well as the damage it had suffered during the war. At first, Lysenkoism was promoted in Poland by a small group of enthusiastic and uncritical proponents. A overview of the events connected with the ten years of Lysenkoism in Poland (end of 1948--beginning of 1958) shows a two-tier picture of how the 'idea' was propagated. The first tier consisted in the activities of the Association of Marxist Naturalists [Koło Przyrodników-Marksistów], which it engaged in since the end of 1948. The Association was later transformed into a Union of Marxist Naturalists, and this in turn merged, in 1952, with the Copernican Society of Polish Naturalists [Polskie Towarzystwo Przyrodników im. Kopernika]. It was that society which promoted Lysenkoism longest, until the end of 1956. The propaganda and training activities of the circle and the society prepared ground for analogous activities of the newly formed Polish Academy of Science (PAN), which--since its very establishment in 1952--engaged in promoting Lysenkoism through its Second Division. These activities were aimed at naturalists, initially at those who were prominent scientists (eg. the conference at Kuźnice, 1950/1951), and then at those who were only starting their academic career (including national courses in new biology at Dziwnów, 1952, or Kortowo, 1953 and 1955). The end to promoting

  4. Training theory and taper: validation in triathlon athletes.

    PubMed

    Banister, E W; Carter, J B; Zarkadas, P C

    1999-01-01

    This paper defines a training theory with which to predict the effectiveness of various formats of taper in optimizing physical performance from a standardized period of training and taper. Four different taper profiles: step reduction vs exponential (exp) decay and fast vs slow exp decay tapers, were simulated in a systems model to predict performance p(t) resulting from a standard square-wave quantity of training for 28 days. The relative effectiveness of each of the profiles in producing optimal physical improvement above pre-taper criterion physical test standards (running and cycle ergometry) was determined. Simulation showed that an exp taper was better than a step-reduction taper, and a fast exp decay taper was superior to a slow exp decay taper. The results of the simulation were tested experimentally in field trials to assess the correspondence between simulation and real-training criterion physical tests in triathlon athletes. The results showed that the exp taper (tau = 5 days) group made a significantly greater improvement above a pre-taper standard (P < or = 0.05) than the step-reduction taper group in cycle ergometry, and was better, but not significantly so, in a 5-km run. A fast exp taper group B (tau = 4 days) performed significantly better (P < or = 0.05) in maximal, cycle ergometry above a pre-taper training standard than a slow exp taper group A (tau = 8 days) and was improved more, but not significantly so, than group A in a 5-km criterion run. The mean improvement on both physical tests by exp decay taper groups all increased significantly (P < or = 0.05) above their pre-taper training standard. Maximum oxygen uptake increased significantly in a group of eight remaining athletes during 2 weeks of final taper after three athletes left early for final preparations at the race site.

  5. Turbine airfoil fabricated from tapered extrusions

    DOEpatents

    Marra, John J

    2013-07-16

    An airfoil (30) and fabrication process for turbine blades with cooling channels (26). Tapered tubes (32A-32D) are bonded together in a parallel sequence, forming a leading edge (21), a trailing edge (22), and pressure and suction side walls (23, 24) connected by internal ribs (25). The tapered tubes may be extruded without camber to simplify the extrusion process, then bonded along matching surfaces (34), forming a non-cambered airfoil (28), which may be cambered in a hot forming process and cut (48) to length. The tubes may have tapered walls that are thinner at the blade tip (T1) than at the base (T2), reducing mass. A cap (50) may be attached to the blade tip. A mounting lug (58) may be forged (60) on the airfoil base and then machined, completing the blade for mounting in a turbine rotor disk.

  6. Two critical tapers in a single wedge

    NASA Astrophysics Data System (ADS)

    Smit, J.; Burg, J.-P.; Brun, J.-P.

    2009-04-01

    Thrust involving a ductile décollement (e.g. salt, over-pressured shales) like Zagros, Jura, Pakistan Salt Ranges, Cascades and Makran have in common a small cross-sectional taper, attributed to large thrust spacing and fast frontward propagation above the ductile décollement. Such a low cross-sectional taper has been analytically explained by approximating the ductile layer as a horizon with negligible shear strength. We tested the development of thrust wedges involving a ductile basal décollement of uniform shear strength by means of laboratory experiments. The model consists of a sand layer with initial wedge geometry and a basal ductile décollement of constant thickness and shear strength made of silicone putty. 30% of bulk shortening is applied to the wedge at constant velocity. Thrusting starts in the middle of the wedge, followed by in-sequence frontward propagation. The back part of the wedge, between backstop and the closest thrust, remains undeformed; it passively advances over the base without internal deformation. It appears that both domains have different critical tapers. The inner domain is in a critical state from the onset of shortening (i.e. the initial wedge is already critical), while the frontal domain steadily acquires a state of critical taper by thrusting. This result is at variance with the classical assumption that shortening of a wedge made of homogeneous layers creates a single critical taper. The experimental thrust wedges do show other features characteristic for weak décollement wedges like narrow cross-sectional taper, large thrust spacing and variety in thrust geometries. Application of the results to natural thrust wedges like the Jura Mountains could shed new light on their development and geometry at depth.

  7. Stress intensity factor in a tapered specimen

    NASA Technical Reports Server (NTRS)

    Xue-Hui, L.; Erdogan, F.

    1985-01-01

    The general problem of a tapered specimen containing an edge crack is formulated in terms of a system of singular integral equations. The equations are solved and the stress intensity factor is calculated for a compact and for a slender tapered specimen, the latter simulating the double cantilever beam. The results are obtained primarily for a pair of concentrated forces and for crack surface wedge forces. The stress intensity factors are also obtained for a long strip under uniform tension which contains inclined edge cracks.

  8. Lightwave coupler utilizing a tapered buffer layer.

    PubMed

    Kishioka, K

    1988-06-01

    We discuss the performance of a lightwave coupler utilizing a tapered buffer layer. The coupler with a ridge waveguide is fabricated on a glass substrate and high coupling efficiencies of 75% and 50% are measured for the operations of coupling from the waveguide to a light beam and from the laser beam into the waveguide, respectively. Further, experimental results of the rigid connection between the optical fiber and the waveguide are demonstrated. We also describe how the coupler differs from the conventional tapered guiding-layer coupler.

  9. Polishing of denture base acrylic resin with chairside polishing kits: an SEM and surface roughness study.

    PubMed

    Chatzivasileiou, Konstantinos; Emmanouil, Ioannis; Kotsiomiti, Eleni; Pissiotis, Argirios

    2013-01-01

    Heat-cured acrylic resin specimens were polished using either conventional laboratory polishing, sandpaper, or three commercial chairside kits. The surface roughness of the polished specimens was measured with a contact profilometer. Scanning electron microscopy was used to obtain microphotographs of the polished surfaces. Laboratory polishing produced the smoothest surfaces in all cases, while sandpaper application produced the roughest. Use of the chairside polishing kits resulted in significantly rougher surfaces compared to those produced by laboratory polishing. Nonetheless, polishing of trimmed denture bases using chairside polishing kits is an effective alternative procedure for cases in which the laboratory procedure is not applicable.

  10. Recent Changes in the Spoken Polish Language.

    ERIC Educational Resources Information Center

    Birkenmayer, Sigmund S.

    Both spoken and written Polish have undergone profound changes during the past twenty-eight years. The increasing urbanization of Polish culture and the forced change in Polish society are the main factors influencing the change in the language. Indirect evidence of changes which have occurred in the vocabulary and idioms of spoken Polish in the…

  11. 77 FR 50716 - Tapered Roller Bearings From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... COMMISSION Tapered Roller Bearings From China Determination On the basis of the record \\1\\ developed in the... antidumping duty order on tapered roller bearings from China would be likely to lead to continuation or... Publication 4343 (August 2012), entitled Tapered Roller Bearings from China: Investigation No....

  12. Microstrip transmission line tapers on ferrites

    SciTech Connect

    Albuquerque, M.R.; dAssuncao, A.G.; Lima, F.

    1997-04-01

    The spectral domain approach is employed to perform a theoretical investigation of tapered microstrip lines on magnetized ferrite substrates. A linear variation of the conducting strip width along the direction of propagation is considered. The analysis takes into account the effects of the applied dc magnetic bias field in the transmission characteristics of these structures. The properties of the taper are determined by a model based on a segmentation of the considered line into uniform microstrip line subsections. Normalized phase constants and characteristic impedances are obtained by using the Hertz vector potentials method and Galerkin numerical technique. Numerical results are presented to show the taper input parameters as a function of the load impedance, geometrical dimensions, operating frequency, and ferrite parameters, considering the orientation and magnitude changes of the biasing magnetic-field {bold H}{sub 0}. The results agree fairly well with those available in the literature for tapered microstrip lines on isotropic dielectric substrates. {copyright} {ital 1997 American Institute of Physics.}

  13. 60 GHz Tapered Transmission Line Resonators

    DTIC Science & Technology

    2008-09-15

    DARPA TEAM program (contract no. DAAB07-02-1- L428 ), Motorola, and the UC-Micro program. 60 GHz Tapered Transmission Line Resonators by...0403427, wafer fabrication donation by STMicroelectronics, DARPA TEAM program (con- tract no. DAAB07-02-1- L428 ), Motorola, and the UC-Micro program. 1

  14. Tapered LSO arrays for small animal PET

    NASA Astrophysics Data System (ADS)

    Yang, Yongfeng; St. James, Sara; Wu, Yibao; Du, Huini; Qi, Jinyi; Farrell, Richard; Dokhale, Purushottam A.; Shah, Kanai S.; Vaigneur, Keith; Cherry, Simon R.

    2011-01-01

    By using detectors with good depth encoding accuracy (~2 mm), an animal PET scanner can be built with a small ring diameter and thick crystals to simultaneously obtain high spatial resolution and high sensitivity. However, there will be large wedge-shaped gaps between detector modules in such a scanner if traditional cuboid crystal arrays are used in a polygonal arrangement. The gaps can be minimized by using tapered scintillator arrays enabling the sensitivity of the scanner to be further improved. In this work, tapered lutetium oxyorthosilicate (LSO) arrays with different crystal dimensions and different combinations of inter-crystal reflector and crystal surface treatments were manufactured and their performance was evaluated. Arrays were read out from both ends by position-sensitive avalanche photodiodes (PSAPDs). In the optimal configuration, arrays consisting of 0.5 mm LSO elements could be clearly resolved and a depth of interaction resolution of 2.6 mm was obtained for a 20 mm thick array. For this tapered array, the intrinsic spatial is degraded from 0.67 to 0.75 mm compared to a standard cuboidal array with similar dimensions, while the increase in efficiency is 41%. Tapered scintillator arrays offer the prospect of improvements in sensitivity and sampling for small-bore scanners, without large increases in manufacturing complexity.

  15. Tooth polishing: The current status

    PubMed Central

    Sawai, Madhuri Alankar; Bhardwaj, Ashu; Jafri, Zeba; Sultan, Nishat; Daing, Anika

    2015-01-01

    Healthy teeth and gums make a person feel confident and fit. As people go about their daily routines and with different eating and drinking habits, the tooth enamel turns yellowish or gets stained. Polishing traditionally has been associated with the prophylaxis procedure in most dental practices, which patients know and expect. However, with overzealous use of polishing procedure, there is wearing of the superficial tooth structure. This would lead to more accumulation of local deposits. Also, it takes a long time for the formation of the fluoride-rich layer of the tooth again. Hence, now-a-days, polishing is not advised as a part of routine oral prophylaxis procedure but is done selectively based on the patients’ need. The article here, gives an insight on the different aspects of the polishing process along with the different methods and agents used for the same. PMID:26392683

  16. Lysenko affair and Polish botany.

    PubMed

    Köhler, Piotr

    2011-01-01

    This article describes the slight impact of Lysenkoism upon Polish botany. I begin with an account of the development of plant genetics in Poland, as well as the attitude of scientists and the Polish intelligentsia toward Marxist philosophy prior to the World War II. Next I provide a short history of the introduction and demise of Lysenkoism in Polish science, with a focus on events in botany, in context with key events in Polish science from 1939 to 1958. The article outlines the little effects of Lysenkoism upon botanists and their research, as well as how botanists for the most part rejected what was often termed the "new biology." My paper shows that though Lysenko's theories received political support, and were actively promoted by a small circle of scientists and Communist party activists, they were never accepted by most botanists. Once the political climate in Poland altered after the events of 1956, Lysenko's theories were immediately abandoned.

  17. XXXVI Polish Astronomical Society Meeting

    NASA Astrophysics Data System (ADS)

    Różańska, Agata; Bejger, Michał

    2014-12-01

    XXXVI meeting of Polish Astronomical Society was held in Warsaw on Sept. 11-14, 2013. The conference brought together 150 astronomers working in different institutes in Poland and abroad. The highlight of the Congress was the first awarding of the Paczynski's Medal. The first laureate of the Medal is Professor Martin Rees from University of Cambridge. Medal was given by the President of the Polish Astronomical Society prof. Bozena Czerny.

  18. Astronarium - Filmography of Polish Astronomy

    NASA Astrophysics Data System (ADS)

    Radajewski, Bogumił; Mikołajewski, Maciej; Czart, Krzysztof; Guz, Iwona; Rubaszewski, Adam; Stelmach, Tomasz

    2016-06-01

    ``Astronarium'' is a series of TV programs about astronomy and space research co-produced by the Polish Astronomical Society and Polish Television. It has been planned for three seasons and 34 episodes in total (8, 13 and 13 per season). The first season was presented in March and April 2015 and the second started in September 2015. The third one is planned for 2016. ``Astronarium'' has been broadcast on the nationwide channel TVP Regionalna, which later changed its name to TVP 3.

  19. Electrochemical polishing of notches

    DOEpatents

    Kephart, Alan R.; Alberts, Alfred H.

    1989-01-01

    An apparatus and method are disclosed for the selective electrochemical polishing of a lateral tip of a deep longitudinal notch in a work piece used to test crack initiation properties of materials. A DC power source is connected to the work piece and to an electrode disposed laterally along the distal end of an insulated body which is inserted in the longitudinal notch. The electrode and distal end of the body are disposed along the tip of the notch, but are spaced from the notch so as to provide a lateral passage for an electrolyte. The electrolyte is circulated through the passage so that the electrolyte only contacts the work piece adjacent the passage. Conveniently, the electrolyte is circulated by use of an inlet tube and an outlet tube provided at opposite ends of the passage. These tubes are preferably detachably located adjacent the ends of the passage and suitable seals are provided. A holding device including arms to which the tubes are attached is conveniently used to rapidly and easily locate the test specimen with the passage aligned with the tubes. The electrode is preferably a wire which is located in grooves along the distal end of the insulated body and up one side of the body or a plastic sheath insulated thin metal strip.

  20. Electrochemical polishing of notches

    DOEpatents

    Kephart, A.R.; Alberts, A.H.

    1989-02-21

    An apparatus and method are disclosed for the selective electrochemical polishing of a lateral tip of a deep longitudinal notch in a work piece used to test crack initiation properties of materials. A DC power source is connected to the work piece and to an electrode disposed laterally along the distal end of an insulated body which is inserted in the longitudinal notch. The electrode and distal end of the body are disposed along the tip of the notch, but are spaced from the notch so as to provide a lateral passage for an electrolyte. The electrolyte is circulated through the passage so that the electrolyte only contacts the work piece adjacent the passage. Conveniently, the electrolyte is circulated by use of an inlet tube and an outlet tube provided at opposite ends of the passage. These tubes are preferably detachably located adjacent the ends of the passage and suitable seals are provided. A holding device including arms to which the tubes are attached is conveniently used to rapidly and easily locate the test specimen with the passage aligned with the tubes. The electrode is preferably a wire which is located in grooves along the distal end of the insulated body and up one side of the body or a plastic sheath insulated thin metal strip. 4 figs.

  1. Elastic emission polishing

    SciTech Connect

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  2. Transverse Emittance Reduction with Tapered Foil

    SciTech Connect

    Jiao, Yi; Chao, Alex; Cai, Yunhai; /SLAC

    2011-12-09

    The idea of reducing transverse emittance with tapered energy-loss foil is proposed by J.M. Peterson in 1980s and recently by B. Carlsten. In this paper, we present the physical model of tapered energy-loss foil and analyze the emittance reduction using the concept of eigen emittance. The study shows that, to reduce transverse emittance, one should collimate at least 4% of particles which has either much low energy or large transverse divergence. The multiple coulomb scattering is not trivial, leading to a limited emittance reduction ratio. Small transverse emittances are of essential importance for the accelerator facilities generating free electron lasers, especially in hard X-ray region. The idea of reducing transverse emittance with tapered energy-loss foil is recently proposed by B. Carlsten [1], and can be traced back to J.M. Peterson's work in 1980s [2]. Peterson illustrated that a transverse energy gradient can be produced with a tapered energy-loss foil which in turn leads to transverse emittance reduction, and also analyzed the emittance growth from the associated multiple coulomb scattering. However, what Peterson proposed was rather a conceptual than a practical design. In this paper, we build a more complete physical model of the tapered foil based on Ref. [2], including the analysis of the transverse emittance reduction using the concept of eigen emittance and confirming the results by various numerical simulations. The eigen emittance equals to the projected emittance when there is no cross correlation in beam's second order moments matrix [3]. To calculate the eigen emittances, it requires only to know the beam distribution at the foil exit. Thus, the analysis of emittance reduction and the optics design of the subsequent beam line section can be separated. In addition, we can combine the effects of multiple coulomb scattering and transverse energy gradient together in the beam matrix and analyze their net effect. We find that,when applied to an

  3. Sidestream condensate polishing for PWRs

    SciTech Connect

    Shor, S.W.W.; Yim, S.L.; Rios, J.; Liu, J.

    1986-06-01

    Condensate polishers are used in power plant condensate system to remove both particulate matter and ionized corrodents. Their conventional location is just downstream of the hotwell pumps (condensate pumps). Most polisher installations have enough flow capacity to polish 100% of the condensate. This inline configuration has some disadvantage, including a flow that varies with unit load and tends to disturb the polisher beds and reduce their effectiveness, and a potential for interrupting flow to the feedwater pumps. An alternate arrangement where water is extracted from either the condenser or the condensate system, polished and returned to the system, has been used in a few plants. Three different ways of doing this have been used: divide the condenser hotwell into two parts, one of which receives condensate from the tube bundles and the other of which is sheltered. Take unpolished condensate from the first part, purify it and return it to the other part from which the condensate pumps take suction; take unpolished condensate from one end of a divided header on the suction side of the hotwell pumps and after polishing it return it to the other end; and take unpolished condensate from a header on the discharge side of the condensate pumps, purify it and return it to the condensate system a short distance downstream. The three variants are analyzed in this report. It is concluded that the variant where the connections are on the discharge side of the condensate pumps is the most desirable for retrofitting, in all cases being far easier to retrofit than an inline polisher. In many cases it will be most desirable for new construction.

  4. Orthogonal feeding techniques for tapered slot antennas

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Simons, Rainee N.

    1998-01-01

    For array of "brick" configuration there are electrical and mechanical advantages to feed the antenna with a feed on a substrate perpendicular to the antenna substrate. Different techniques have been proposed for exciting patch antennas using such a feed structure.Rncently, an aperture-coupled dielectric resonator antenna using a perpendicular feed substrate has been demonstrated to have very good power coupling efficiency. For a two-dimensional rectangular array with tapered slot antenna elements, a power combining network on perpendicular substrate is generally required to couple power to or from the array. In this paper, we will describe two aperture-coupled techniques for coupling microwave power from a linearly tapered slot antenna (LTSA) to a microstrip feed on a perpendicular substrate. In addition, we will present measured results for return losses and radiation patterns.

  5. Performance of an elliptically tapered neutron guide

    NASA Astrophysics Data System (ADS)

    Mühlbauer, Sebastian; Stadlbauer, Martin; Böni, Peter; Schanzer, Christan; Stahn, Jochen; Filges, Uwe

    2006-11-01

    Supermirror coated neutron guides are used at all modern neutron sources for transporting neutrons over large distances. In order to reduce the transmission losses due to multiple internal reflection of neutrons, ballistic neutron guides with linear tapering have been proposed and realized. However, these systems suffer from an inhomogeneous illumination of the sample. Moreover, the flux decreases significantly with increasing distance from the exit of the neutron guide. We propose using elliptically tapered guides that provide a more homogeneous phase space at the sample position as well as a focusing at the sample. Moreover, the design of the guide system is simplified because ellipses are simply defined by their long and short axes. In order to prove the concept we have manufactured a doubly focusing guide and investigated its properties with neutrons. The experiments show that the predicted gains using the program package McStas are realized. We discuss several applications of elliptic guides in various fields of neutron physics.

  6. Cooling arrangement for a tapered turbine blade

    DOEpatents

    Liang, George

    2010-07-27

    A cooling arrangement (11) for a highly tapered gas turbine blade (10). The cooling arrangement (11) includes a pair of parallel triple-pass serpentine cooling circuits (80,82) formed in an inner radial portion (50) of the blade, and a respective pair of single radial channel cooling circuits (84,86) formed in an outer radial portion (52) of the blade (10), with each single radial channel receiving the cooling fluid discharged from a respective one of the triple-pass serpentine cooling circuit. The cooling arrangement advantageously provides a higher degree of cooling to the most highly stressed radially inner portion of the blade, while providing a lower degree of cooling to the less highly stressed radially outer portion of the blade. The cooling arrangement can be implemented with known casting techniques, thereby facilitating its use on highly tapered, highly twisted Row 4 industrial gas turbine blades that could not be cooled with prior art cooling arrangements.

  7. Spatially resolved spectroscopy using tapered stripline NMR

    NASA Astrophysics Data System (ADS)

    Tijssen, Koen C. H.; Bart, Jacob; Tiggelaar, Roald M.; Janssen, J. W. G. (Hans); Kentgens, Arno P. M.; van Bentum, P. Jan M.

    2016-02-01

    Magnetic field B0 gradients are essential in modern Nuclear Magnetic Resonance spectroscopy and imaging. Although RF/B1 gradients can be used to fulfill a similar role, this is not used in common practice because of practical limitations in the design of B1 gradient coils. Here we present a new method to create B1 gradients using stripline RF coils. The conductor-width of a stripline NMR chip and the strength of its radiofrequency field are correlated, so a stripline chip can be tapered to produce any arbitrary shaped B1 field gradient. Here we show the characterization of this tapered stripline configuration and demonstrate three applications: magnetic resonance imaging on samples with nL-μL volumes, reaction monitoring of fast chemical reactions (10-2-101 s) and the compensation of B0 field gradients to obtain high-resolution spectra in inhomogeneous magnetic fields.

  8. Performance of a tapered pulse tube

    SciTech Connect

    Swift, G.; Allen, M.; Woolan, J.J.

    1998-02-01

    In a well instrumented pulse tube refrigerator having 1,500 W of cooling power at 125 K, the authors have measured the figure of merit of a tapered pulse tube at several operating points. At operating points near the operating point for which the taper was designed, the figure of merit is 0.96. This is close to the theoretical optimum figure of merit 0.97 calculated for this pulse tube considering only two loss mechanisms: heat conduction in the metal pulse tube wall and ordinary thermoacoustic heat transport in the gas within a few thermal penetration depths of the wall. At operating points farther from the design operating point, the measured figure of merit is much lower, as streaming driven convection adds a third loss mechanism.

  9. Efficient polishing of aspheric optics

    SciTech Connect

    Taylor, J.S.; Piscotty, M.A.; Nguyen, N.Q.; Landram, C.S.; Ng, L.C.

    1997-04-15

    The objectives of this project are to develop, evaluate, and optimize novel designs for a polishing tool intended for ultra-precise figure corrections on aspheric optics with tolerances typical of those required for use in extreme ultraviolet (EUV) projection lithography. This work may lead to an enhanced US industrial capability for producing optics for EUV, x-ray and, other high precision applications. LLNL benefits from developments in computer-controlled polishing and the insertion of fluid mechanics modeling into the precision manufacturing area. Our accomplishments include the numerical estimation of the hydrodynamic shear stress distribution for a new polishing tool that directs and controls the interaction of an abrasive slurry with an optical surface. A key milestone is in establishing a correlation between the shear stress predicted using our fluid mechanics model and the observed removal footprint created by a prototype tool. In addition, we demonstrate the ability to remove 25 nm layers of optical glass in a manner qualitatively similar to macroscopic milling operations using a numerically- controlled machine tool. Other accomplishments include the development of computer control software for directing the polishing tool and the construction of a polishing testbed.

  10. Sensing roughness and polish direction

    NASA Astrophysics Data System (ADS)

    Jakobsen, M. L.; Olesen, A. S.; Larsen, H. E.; Stubager, J.; Hanson, S. G.; Pedersen, T. F.; Pedersen, H. C.

    2016-04-01

    As a part of the work carried out on a project supported by the Danish council for technology and innovation, we have investigated the option of smoothing standard CNC machined surfaces. In the process of constructing optical prototypes, involving custom-designed optics, the development cost and time consumption can become relatively large numbers in a research budget. Machining the optical surfaces directly is expensive and time consuming. Alternatively, a more standardized and cheaper machining method can be used, but then the object needs to be manually polished. During the polishing process the operator needs information about the RMS-value of the surface roughness and the current direction of the scratches introduces by the polishing process. The RMS-value indicates to the operator how far he is from the final finish, and the scratch orientation is often specified by the customer in order to avoid complications during the casting process. In this work we present a method for measuring the RMS-values of the surface roughness while simultaneously determining the polishing direction. We are mainly interested in the RMS-values in the range from 0 - 100 nm, which corresponds to the finish categories of A1, A2 and A3. Based on simple intensity measurements we estimates the RMS-value of the surface roughness, and by using a sectioned annual photo-detector to collect the scattered light we can determine the direction of polishing and distinguish light scattered from random structures and light scattered from scratches.

  11. Pump and Signal Taper for Airclad Fibers

    DTIC Science & Technology

    2006-01-05

    as follows: Crystal Fibre A/S will develop a taper/coupler solution to interface between a new polarization maintaining/polarizing amplifier fiber ...MM) pump combiner with a high NA air-clad output. The input side of the combiner is 7 individual MM pump delivery solid all- glass fibers . The NA of...pump combiner. MOTIVATION FINAL REPORT ITEM 0002 In a typical standard fused fiber coupler a number of all- glass 0.22 NA pump

  12. Waveguide taper engineering using coordinate transformation technology

    NASA Astrophysics Data System (ADS)

    Tichit, Paul-Henri; Burokur, Shah Nawaz; de Lustrac, André

    2010-01-01

    Spatial coordinate transformation is a suitable tool for the design of complex electromagnetic structures. In this paper, we define three spatial coordinate transformations which show the possibility of designing a taper between two different waveguides. A parametric study is presented for the three transformations and we propose achievable values of permittivity and permeability that can be obtained with existing metamaterials. The performances of such defined structures are demonstrated by finite element numerical simulations.

  13. Waveguide taper engineering using coordinate transformation technology.

    PubMed

    Tichit, Paul-Henri; Burokur, Shah Nawaz; de Lustrac, André

    2010-01-18

    Spatial coordinate transformation is a suitable tool for the design of complex electromagnetic structures. In this paper, we define three spatial coordinate transformations which show the possibility of designing a taper between two different waveguides. A parametric study is presented for the three transformations and we propose achievable values of permittivity and permeability that can be obtained with existing metamaterials. The performances of such defined structures are demonstrated by finite element numerical simulations.

  14. Design of Structurally Efficient Tapered Struts

    NASA Technical Reports Server (NTRS)

    Messinger, Ross

    2010-01-01

    This report describes the analytical study of two full-scale tapered composite struts. The analytical study resulted in the design of two structurally efficient carbon/epoxy struts in accordance with NASA-specified geometries and loading conditions. Detailed stress analysis was performed of the insert, end fitting, and strut body to obtain an optimized weight with positive margins. Two demonstration struts were fabricated based on a well-established design from a previous Space Shuttle strut development program.

  15. Tapered Bottlebrush Polymers: A New Polymer Architecture

    DTIC Science & Technology

    2015-07-30

    length of the backbone polymer . This type of covalent, cone- shaped polymer may have applications in supersoft elastomeric materials and as...rate of polymerization must be as high as possible for the synthesis of precise tapered bottlebrush polymers . An example of the kinetics data obtained... polymers with anchor group 1 allow for faster polymerization . MM Name k p (10 -3 L * mol -1 * s -1 ) t1/2 (s) krel 1S 3k 11 ± 2 68 ± 20

  16. Experimental stiffness of tapered bore seals

    NASA Technical Reports Server (NTRS)

    Fleming, D. P.

    1985-01-01

    The stiffness of tapered-bore ring seals was measured with air as the sealed fluid. Static stiffness agreed fairly well with results of a previous analysis. Cross-coupled stiffness due to shaft rotation was much less than predicted. It is suggested that part of the disparity may be due to simplifying assumptions in the analysis; however, these do not appear to account for the entire difference observed.

  17. Tapered pulse tube for pulse tube refrigerators

    DOEpatents

    Swift, Gregory W.; Olson, Jeffrey R.

    1999-01-01

    Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

  18. Surgical Outcomes of Forearm Loop Arteriovenous Fistula Formation Using Tapered versus Non-Tapered Polytetrafluoroethylene Grafts

    PubMed Central

    Han, Sun; Seo, Pil Won; Ryu, Jae-Wook

    2017-01-01

    Background Tapered grafts, which have a smaller diameter on the arterial side, have been increasingly used for arteriovenous fistula (AVF) formation. We compared the outcomes of 4–6-mm tapered and 6-mm straight forearm loop arteriovenous grafts. Methods A total of 103 patients receiving forearm loop arteriovenous grafts between March 2005 and March 2015 were retrospectively analyzed and separated into 2 groups (group A, 4- to 6-mm tapered grafts, n=78; group B, 6-mm straight grafts, n=25). In each group, complications and patency rates after surgery were assessed. Results Clinical characteristics and laboratory results, except for cerebrovascular disease history (group A, 7.7%; group B, 28.0%; p=0.014), were similar between the groups. No significant differences were found for individual complications. Kaplan-Meier survival analysis revealed no significant differences in 1-year, 3-year, and 5-year patency rates between groups (61.8%, 44.9%, and 38.5% vs. 62.7%, 41.1%, and 35.3%, respectively). Conclusion We found no significant differences in complication and patency rates between the tapered and straight graft groups. If there are no differences in complication and patency between the two graft types, tapered grafts may be a valuable option for AVF formation in light of their other advantages. PMID:28180100

  19. Polishing of dental porcelain by polycrystalline diamond.

    PubMed

    Nakamura, Yoshiharu; Sato, Hideaki; Ohtsuka, Masaki; Hojo, Satoru

    2010-01-01

    Polycrystalline diamond (PCD) exhibits excellent abrasive characteristics and is commonly used as loose grains for precision machining of hard ceramics and other materials that are difficult to grind and polish. In the present study, we investigated using bonded PCD for polishing dental porcelain, for which a lustrous surface is difficult to obtain by polishing. We compared the surface texture and characteristics of dental porcelain after polishing with bonded PCD with that obtained using bonded monocrystalline diamond (MCD), which is commonly used for this purpose. Polishing was performed at various pressures and rotational speeds on a custom-built polishing apparatus using bonded PCD or MCD with grain sizes of 3.92 μm on specimens consisting of VITA Omega 900 dentin porcelain after firing and then glazing to a specified surface roughness. The surface roughness of the polished porcelain and the abrasion quantity in terms of its polishing depth were measured, and its surface texture and characteristics were investigated. At low polishing pressures, PCD yielded a finer polished surface than MCD. The polishing depth after polishing for 20-30 min was approximately 2-3 μm with PCD and 1-2 μm with MCD. The polished surface was more uniform and smooth with PCD than with MCD.

  20. Graphite Composite Panel Polishing Fixture

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Strojny, Carl; Budinoff, Jason

    2011-01-01

    The use of high-strength, lightweight composites for the fixture is the novel feature of this innovation. The main advantage is the light weight and high stiffness-to-mass ratio relative to aluminum. Meter-class optics require support during the grinding/polishing process with large tools. The use of aluminum as a polishing fixture is standard, with pitch providing a compliant layer to allow support without deformation. Unfortunately, with meter-scale optics, a meter-scale fixture weighs over 120 lb (.55 kg) and may distort the optics being fabricated by loading the mirror and/or tool used in fabrication. The use of composite structures that are lightweight yet stiff allows standard techniques to be used while providing for a decrease in fixture weight by almost 70 percent. Mounts classically used to support large mirrors during fabrication are especially heavy and difficult to handle. The mount must be especially stiff to avoid deformation during the optical fabrication process, where a very large and heavy lap often can distort the mount and optic being fabricated. If the optic is placed on top of the lapping tool, the weight of the optic and the fixture can distort the lap. Fixtures to support the mirror during fabrication are often very large plates of aluminum, often 2 in. (.5 cm) or more in thickness and weight upwards of 150 lb (68 kg). With the addition of a backing material such as pitch and the mirror itself, the assembly can often weigh over 250 lb (.113 kg) for a meter-class optic. This innovation is the use of a lightweight graphite panel with an aluminum honeycomb core for use as the polishing fixture. These materials have been used in the aerospace industry as structural members due to their light weight and high stiffness. The grinding polishing fixture consists of the graphite composite panel, fittings, and fixtures to allow interface to the polishing machine, and introduction of pitch buttons to support the optic under fabrication. In its

  1. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1995-08-22

    A polishing compound for plastic surfaces is disclosed. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains fine particles silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS{trademark}, LEXAN{trademark}, LUCITE{trademark}, polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired. 5 figs.

  2. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1993-01-01

    A polishing compound for plastic surfaces is disclosed. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains colloidal silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS{sup TM}, LEXAN{sup TM}, LUCITE{sup TM}, polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  3. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, Michael S.

    1995-01-01

    A polishing compound for plastic surfaces. The compound contains by weight approximately 4 to 17 parts at least one petroleum distillate lubricant, 1 to 6 parts mineral spirits, 2.5 to 15 parts abrasive particles, and 2.5 to 10 parts water. The abrasive is tripoli or a similar material that contains fine particles silica. Preferably, most of the abrasive particles are less than approximately 10 microns, more preferably less than approximately 5 microns in size. The compound is used on PLEXIGLAS.TM., LEXAN.TM., LUCITE.TM., polyvinyl chloride (PVC) and similar plastic materials whenever a smooth, clear polished surface is desired.

  4. Effects of taper on swim performance. Practical implications.

    PubMed

    Houmard, J A; Johns, R A

    1994-04-01

    Competitive swimmers commonly focus upon optimising performance at a single competition. A period where training volume is incrementally reduced or "tapered" often precedes such a competition. The use of taper is justified as increases in muscular power, and the restoration of plasma haematocrit, haemoglobin and creatine kinase are evident with this training reduction. A consistent performance improvement of approximately 3% has also been reported with taper in competitive swimmers. However, there are limitations in terms of what comprises a successful taper schedule. It appears that a taper which improves performance involves a substantial (60 to 90%) graded reduction in training volume, and daily high intensity interval work over a 7- to 21-day period. Training frequency should be reduced by no more than 50%; a more conservative estimate would be to reduce frequency by approximately 20%. Optimal performance is likely when the reduction in training frequency is combined with the qualitative knowledge of the coach and/or athlete during taper.

  5. Migration and strains induced by different designs of force-closed stems for THA☆

    PubMed Central

    Griza, Sandro; Gomes, Luiz Sérgio Marcelino; Cervieri, André; Strohaecker, Telmo Roberto

    2015-01-01

    Objectives Subtle differences in stem design can result in different mechanical responses of the total hip arthroplasty. Tests measuring migration of the stem relative to the femur, as well as the strains in the cement mantle and on the femur can detect different mechanical behavior between stems. Methods In this article, conical, double and triple tapered stems were implanted in composite femurs and subjected to static and cyclic loads. Stems differed mainly on taper angle, calcar radius and proximal stiffness. Stem migration and strains on the femur and in the cement mantle were achieved. Results Significant differences (p < 0.05) were noted in the permanent rotation between double and triple tapers, in the strains on the proximal medial femur between triple and both conical and double tapers, and in the strains on the lateral proximal femur between double tapers and both conical and triple tapers. Conclusion The proposed mechanical tests were able to detect significant differences in the behavior of these resembling stems. Stem proximal stiffness and the calcar radius of the stem influence its rotational stability and the strain transmission to the femur. PMID:27218081

  6. Proceedings: 2002 Workshop on Condensate Polishing

    SciTech Connect

    2002-06-01

    Condensate polishing aims to control impurities in a nuclear power plant, thus allowing the unit to operate more reliably. This report contains the work presented at EPRI's 2002 Workshop on Condensate Polishing, where 36 papers were presented on current issues, research, and utility experiences involving polishing issues at both pressurized water reactor (PWR) and boiling water reactor (BWR) units.

  7. Proceedings: 2000 Workshop on Condensate Polishing

    SciTech Connect

    2001-06-01

    Condensate polishing maintains control of impurities in the nuclear power plant and allows the unit to operate more reliably. This report presents proceedings of EPRI's 2000 Workshop on Condensate Polishing, where 30 papers were presented on current issues and utility experience involving condensate polishing at both pressurized water reactor (PWR) and boiling water reactor (BWR) plants.

  8. The Polish People: The Challenge of Sponsorship.

    ERIC Educational Resources Information Center

    Li, Gertraude Roth; Johnson, Winston

    This report provides background information on Polish refugees that may be of use to sponsors involved in Polish refugee resettlement in the United States. The report discusses economic and social conditions in Poland; the social values and political attitudes of modern Polish refugees as opposed to those of Poles who settled in the United States…

  9. Tapering practices of Croatian open-class powerlifting champions.

    PubMed

    Grgic, Jozo; Mikulic, Pavle

    2016-10-27

    The aim of this study was to explore tapering practices among 10 Croatian open-class powerlifting champions (mean ± SD: age 29.2 ± 3.2 years; Wilks coefficient 355.1 ± 54.8). The athletes were interviewed about their tapering practices using a semi-structured interview, after which the audio content was transcribed. The athletes reported decreasing training volume during the taper by 50.5 ± 11.7% using a step type or an exponential type of taper with a fast decay. Training intensity was maintained or increased during the taper, and it reached its highest values 8 ± 3 days before the competition. Training frequency was reduced or maintained during the taper. The final week included a reduction in training frequency by 47.9 ± 17.5% with the last training session performed 3 ± 1 days before the competition. The participants typically stated that the main reasons for conducting the taper were maintaining strength and reducing the amount of fatigue. They also stated that (a) the taper was structured identically for the squat, bench press, and the deadlift; (b) the training during the taper was highly specific, the assistance exercises were removed, and the same equipment was used as during competition; (c) the source of information for tapering was their coach, and training fluctuated based on the coach's feedback; and (d) nutrition, foam rolling, static stretching, and massage were all given extra attention during the taper. These results may aid athletes and coaches in strength sports in terms of the optimization of tapering variables.

  10. Phase Centers of Subapertures in a Tapered Aperture Array.

    SciTech Connect

    Doerry, Armin W.; Bickel, Douglas L.

    2015-11-01

    Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

  11. Reading Authentic Polish, Volume I.

    ERIC Educational Resources Information Center

    Walczynski, Waldemar

    This book of instructional materials for reading in Polish are intended for college-level students, and are designed to bring native English-speakers from an 0+ (Novice High) to a 1+ (Intermediate High) language proficiency level on the American Council on the Teaching of Foreign Languages/Interagency Language Roundtable proficiency scale. The…

  12. Dilemmas of Polish Military Strategy

    DTIC Science & Technology

    2008-03-05

    and the tendency to “polarization and symbolization” of the alliance76 that breeds enormous strategic risks. Zbigniew Brzezinski and some Polish...n.p., 2002),64. 21 Ibid., 22 Piotr Wandycz, Polska w polityce miedzynarodowej” in Z dziejopw dyplomacji, (n.p.: Wroclaw, 1989), 9. 23 Janusz

  13. Low-crosstalk Si arrayed waveguide grating with parabolic tapers.

    PubMed

    Ye, Tong; Fu, Yunfei; Qiao, Lei; Chu, Tao

    2014-12-29

    A silicon arrayed waveguide grating (AWG) with low channel crosstalk was demonstrated by using ultra-short parabolic tapers to connect the AWG's free propagation regions and single-mode waveguides. The tapers satisfied the requirements of low-loss mode conversion and lower channel crosstalk from the coupling of neighboring waveguides in the AWGs. In this work, three different tapers, including parabolic tapers, linear tapers, and exponential tapers, were theoretically analyzed and experimentally investigated for a comparison of their effects when implemented in AWGs. The experimental results showed that the AWG with parabolic tapers had a crosstalk improvement up to 7.1 dB compared with the others. Based on the advantages of parabolic tapers, a 400-GHz 8 × 8 cyclic AWG with 2.4 dB on-chip loss and -17.6~-25.1 dB crosstalk was fabricated using a simple one-step etching process. Its performance was comparable with that of existing AWGs with bi-level tapers, which require complicated two-step etching fabrication processes.

  14. Radiation pattern analysis of the tapered slot antenna, appendix 1

    NASA Technical Reports Server (NTRS)

    Janaswamy, Ramakrishna

    1986-01-01

    A theoretical model for the tapered slot antenna is presented. The model is valid for any smooth taper of the slot. The problem is solved by modeling the slot electric field and using the half plane Green's function to compute the far fields. The aperture field is obtained by affecting a stepped approximation to the continuous taper and utilizing the uniform wide slot line data. The uniform wide slot line is solved by the spectral Galerkin's technique and closed form experssions are developed for the slot wave length and the slot characteristic impedance. Numerous comparisons with measurement are made to demonstrate the versatility of the model in treating an arbitrary slot taper.

  15. Cross-linguistic parallels in processing derivational morphology: evidence from Polish.

    PubMed

    Bozic, Mirjana; Szlachta, Zanna; Marslen-Wilson, William D

    2013-12-01

    Neuroimaging evidence in English suggests that the neurocognitive processing of derivationally complex words primarily reflects their properties as whole forms. The current experiment provides a cross-linguistic examination of these proposals by investigating the processing of derivationally complex words in the rich morphological system of Polish. Within the framework of a dual language system approach, we asked whether there is evidence for decompositional processing of derivationally complex Polish stems - reflected in the activation of a linguistically specific decompositional system in the left hemisphere - or for increased competition between the derived stem and its embedded base stem in the bilateral system. The results showed activation in the bilateral system and no evidence for selective engagement of the left hemisphere decompositional system. This provides a cross-linguistic validation for the hypothesis that the neurocognitive processing of derived stems primarily reflects their properties as stored forms.

  16. A tapered box model of the cochlea

    NASA Astrophysics Data System (ADS)

    Sun, Luyang; Ni, Guangjian; Elliott, Stephen

    2015-12-01

    The complicated, three dimensional geometry of the fluid chambers in the cochlea is often represented in models of its mechanics by a box with a uniform area along its length. In this paper we use previous measurements of the variation in area of the two fluid chambers along the length of the cochlea in various mammals, to calculate the variation in the "effective area" that determines the 1D fluid coupling, which is given by the harmonic mean of the two chamber areas. The square root of this effective area is found to vary surprisingly linearly along the cochlea length in several mammalian species. This suggests a variation of the box model in which the width and height of the two fluid chambers are still equal, but now decrease linearly along its length. The width of the basilar membrane, BM, is assumed to increase linearly along the length of the model. The analytic form of the 1D fluid pressure distribution due to elemental BM motion is derived for this tapered box model. The added mass due to the near field acoustic coupling can also be computed, which surprisingly turns out to be almost constant along the length of the BM. The coupled response of the box model with a passive BM can then be readily calculated. Although the pressure distributions due to elemental fluid coupling are very different in the uniform and tapered box models, the distribution of the passive BM response in the coupled models are very similar in the two cases, although the overall level of the response in the tapered model is about 10 dB greater than that in the uniform model.

  17. Resonant plasmon nanofocusing by closed tapered gaps.

    PubMed

    Søndergaard, Thomas; Bozhevolnyi, Sergey I; Beermann, Jonas; Novikov, Sergey M; Devaux, Eloïse; Ebbesen, Thomas W

    2010-01-01

    We study radiation nanofocusing by closed tapered gaps, i.e. metal V-grooves, under normal illumination, and discover that the local field inside a groove can be resonantly enhanced due to interference of counter-propagating gap plasmons. Considering V-grooves milled in gold, we analyze this phenomenon theoretically, deriving an analytic expression for the resonance condition and predicting more than 550-fold intensity enhancements at resonance, and observe it experimentally with two-photon photoluminescence microscopy, demonstrating more than 100-fold intensity enhancements.

  18. Characterization of angled tapered superluminescent LEDs.

    PubMed

    Causa, Federica; Sarma, Jayanta; Yunus, Sharina

    2002-08-20

    We present a detailed analysis of the output beam of high-power edge-emitting angled tapered superluminescent LEDs (A-TSLEDs). A device model, including spontaneous and stimulated emission processes as well as the typical nonuniform carrier-density distribution due to current spreading and carrier diffusion, has been developed and used to interpret the experimentally obtained characteristics of inhouse-fabricated A-TSLEDs. The good match between measured and theoretical results indicates that the model reproduces the A-TSLED operation very satisfactorily and clearly explains the role of the collecting lens on the pronounced asymmetry of some of the measured optical intensity profiles.

  19. Window taper functions for subaperture processing.

    SciTech Connect

    Doerry, Armin Walter

    2013-12-01

    It is well known that the spectrum of a signal can be calculated with a Discrete Fourier Transform (DFT), where best resolution is achieved by processing the entire data set. However, in some situations it is advantageous to use a staged approach, where data is first processed within subapertures, and the results are then combined and further processed to a final result. An artifact of this approach is the creation of grating lobes in the final response. The nature of the grating lobes, including their amplitude and spacing, is an artifact of window taper functions, subaperture offsets, and subaperture processing parameters. We assess these factors and exemplify their effects.

  20. Fiber taper coupling to chalcogenide microsphere modes

    SciTech Connect

    Grillet, Christian; Bian Shuning; Magi, Eric C.; Eggleton, Benjamin J.

    2008-04-28

    We report the fabrication and optical characterization of microsphere in chalcogenide (As{sub 2}Se{sub 3}). We show that high Q modes of a 9.2 {mu}m diameter chalcogenide glass can be efficiently excited via evanescent coupling using a silica tapered fiber. Loaded Q factors of more than 20 000 have been measured. Fine analysis of the coupling spectrum around 1619 nm led to an estimation of the microsphere eccentricity of less than 1%. Owing to the unique combination properties of chalcogenide glass and the microspheres geometry, we expect this architecture to offer an ideal environment for versatile applications on both the telecommunication and midinfrared wavelength windows.

  1. Variations in the trunnion surface topography between different commercially available hip replacement stems.

    PubMed

    Munir, Selin; Walter, William L; Walsh, William Robert

    2015-01-01

    Modular hip implants allows for the adjustment of leg length, offset, and the ability to remove the head for acetabular exposure during primary and revision surgery. The design of the Morse taper facilitates the intimate contact of the conical trunnion of the femoral stem (male component), with the conical bore of the femoral head (female component). Orthopaedic trunnion tapers are not standardized and vary in length, taper angle, and base dimension. Variations in the design and surface characteristics of the trunnion, will directly reflect on the interface at the taper junction and can influence the likelihood of subsequent wear, corrosion and longevity of the implant. The effect of surface topography of trunnions on commercially available hip stems has not yet been considered as a possible contributing factor in the corrosion observed at taper junctions. In this study we analyzed the surface topography and surface roughness of randomly selected commercially available femoral hip stem trunnions to obtain a greater insight into their surface characteristics.

  2. The violin bow: taper, camber and flexibility.

    PubMed

    Gough, Colin

    2011-12-01

    An analytic, small-deflection, simplified model of the modern violin bow is introduced to describe the bending profiles and related strengths of an initially straight, uniform cross-section, stick as a function of bow hair tension. A number of illustrative bending profiles (cambers) of the bow are considered, which demonstrate the strong dependence of the flexibility of the bow on longitudinal forces across the ends of the bent stick. Such forces are shown to be comparable in strength to critical buckling loads causing excessive sideways buckling unless the stick is very straight. Non-linear, large deformation, finite element computations extend the analysis to bow hair tensions comparable with and above the critical buckling strength of the straight stick. The geometric model assumes an expression for the taper of Tourte bows introduced by Vuillaume, which is re-examined and generalized to describe violin, viola and cello bows. A comparison is made with recently published measurements of the taper and bending profiles of a particularly fine bow by Kittel.

  3. Energy savings in Polish buildings

    SciTech Connect

    Markel, L.C.; Gula, A.; Reeves, G.

    1995-12-31

    A demonstration of low-cost insulation and weatherization techniques was a part of phase 1 of the Krakow Clean Fossil Fuels and Energy Efficient Project. The objectives were to identify a cost-effective set of measures to reduce energy used for space heating, determine how much energy could be saved, and foster widespread implementation of those measures. The demonstration project focused on 4 11-story buildings in a Krakow housing cooperative. Energy savings of over 20% were obtained. Most important, the procedures and materials implemented in the demonstration project have been adapted to Polish conditions and applied to other housing cooperatives, schools, and hospitals. Additional projects are being planned, in Krakow and other cities, under the direction of FEWE-Krakow, the Polish Energie Cities Network, and Biuro Rozwoju Krakowa.

  4. Polishing compound for plastic surfaces

    DOEpatents

    Stowell, M.S.

    1991-01-01

    This invention is comprised of a polishing compound for plastic materials. The compound includes approximately by approximately by weight 25 to 80 parts at least one petroleum distillate lubricant, 1 to 12 parts mineral spirits, 50 to 155 parts abrasive paste, and 15 to 60 parts water. Preferably, the compound includes approximately 37 to 42 parts at least one petroleum distillate lubricant, up to 8 parts mineral spirits, 95 to 110 parts abrasive paste, and 50 to 55 parts water. The proportions of the ingredients are varied in accordance with the particular application. The compound is used on PLEXIGLAS{trademark}, LEXAN{trademark}, LUCITE{trademark}, polyvinyl chloride (PVC), and similar plastic materials whenever a smooth, clear polished surface is desired.

  5. Research of combination polishing technology

    NASA Astrophysics Data System (ADS)

    Hang, Liangxia; Zhu, Xueliang; Liu, Weiguo; Guo, Zhongda; Chen, Zhili; Wang, Hongjun

    2010-10-01

    Optical nano-surface is mainly processed by single method, which's high efficiency and high definition are in opposition to each other. The fused silica surface is manufactured with the combination of the Magnetorhelogical manufacturing technology and the Ballonet polishing technology. Finally the high-quality optical nano-surface is achieved which RMS of roughness value is 0.8nm and the sub-surface damage is less.

  6. Electromagnetic field tapering using all-dielectric gradient index materials

    PubMed Central

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-01-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes. PMID:27464989

  7. Electromagnetic field tapering using all-dielectric gradient index materials

    NASA Astrophysics Data System (ADS)

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-07-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

  8. Electromagnetic field tapering using all-dielectric gradient index materials.

    PubMed

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-07-28

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

  9. Functional significance of the taper of vertebrate cone photoreceptors

    PubMed Central

    Hárosi, Ferenc I.

    2012-01-01

    Vertebrate photoreceptors are commonly distinguished based on the shape of their outer segments: those of cones taper, whereas the ones from rods do not. The functional advantages of cone taper, a common occurrence in vertebrate retinas, remain elusive. In this study, we investigate this topic using theoretical analyses aimed at revealing structure–function relationships in photoreceptors. Geometrical optics combined with spectrophotometric and morphological data are used to support the analyses and to test predictions. Three functions are considered for correlations between taper and functionality. The first function proposes that outer segment taper serves to compensate for self-screening of the visual pigment contained within. The second function links outer segment taper to compensation for a signal-to-noise ratio decline along the longitudinal dimension. Both functions are supported by the data: real cones taper more than required for these compensatory roles. The third function relates outer segment taper to the optical properties of the inner compartment whereby the primary determinant is the inner segment’s ability to concentrate light via its ellipsoid. In support of this idea, the rod/cone ratios of primarily diurnal animals are predicted based on a principle of equal light flux gathering between photoreceptors. In addition, ellipsoid concentration factor, a measure of ellipsoid ability to concentrate light onto the outer segment, correlates positively with outer segment taper expressed as a ratio of characteristic lengths, where critical taper is the yardstick. Depending on a light-funneling property and the presence of focusing organelles such as oil droplets, cone outer segments can be reduced in size to various degrees. We conclude that outer segment taper is but one component of a miniaturization process that reduces metabolic costs while improving signal detection. Compromise solutions in the various retinas and retinal regions occur between

  10. Comparative study of the variability of 0.06 tapered rotary endodontic files to current taper standards.

    PubMed

    Hatch, Garth W; Roberts, Steven; Joyce, Anthony P; Runner, Royce; McPherson, James C

    2008-04-01

    This study compared the taper variation among Profile, Guidance, and EndoSequence 0.06 tapered rotary files to current standards. Fifteen files of sizes 35, 40, and 45 from each manufacturer were evaluated for a total of 135 files. A digital image of the first 4 mm of each file was captured with light microscope at 22x, calibrated for 0.001-mm accuracy, and analyzed. The diameter of each file was measured at 1 and 4 mm, and the taper was calculated. Of the 3 file systems, 100% of the Profile files, 97.8% of the Guidance files, and 86.7% of the EndoSequence files fell within +/-0.02 taper. All file systems demonstrated variability within their groups. A series of chi(2) analyses indicated that manufacturers tend to produce Guidance and Profile tapers slightly under the ideal 0.06 taper (P < .05). The tapers of EndoSequence files were just as likely to be over or under the advertised 0.06 taper (P > .05).

  11. Mach-Zehnder interferometer based on tapered PCF with an up-tapered joint for curvature, strain and temperature interrogation

    NASA Astrophysics Data System (ADS)

    Narayan Dash, Jitendra; Jha, Rajan

    2016-10-01

    We propose a Mach-Zehnder interferometric sensor based on tapered Photonic Crystal Fiber (PCF) with up-tapered collapsed region for measurement of parameters such as curvature, strain and temperature. The up-tapered collapsed region helps in excitation of the cladding modes in PCF and these modes interfere with each other at the tapered region of PCF which is completely collapsed. Three tapered PCFs with varying geometry are fabricated and their effect on curvature sensitivity is analyzed. Experimental results show that the proposed sensor has a curvature sensitivity of 7.56 nm m-1 with negligible hysteresis effect. Moreover, the proposed sensor shows a strain sensitivity of 1.6 pm/μɛ along with a maximum temperature sensitivity of 51.6 pm °C-1. In addition to this, the response of the interference pattern to all these parameters is found to be linear.

  12. Increased efficacy of intermediate-dose cytarabine + G-CSF compared to DHAP + G-CSF for stem cell mobilization in patients with lymphoma: an analysis by the polish lymphoma research group.

    PubMed

    Giebel, Sebastian; Sadus-Wojciechowska, Maria; Halaburda, Kazimierz; Drozd-Sokolowska, Joanna; Wierzbowska, Agnieszka; Najda, Jacek; Mendrek, Wlodzimierz; Sobczyk-Kruszelnicka, Malgorzata; Nowicki, Mateusz; Holowiecki, Jerzy; Czerw, Tomasz

    2016-01-01

    Salvage regimens, like DHAP (dexamethasone, cytarabine, and cisplatin) are frequently used for stem cell mobilization in lymphoma. The aim of this study was to compare the efficacy of DHAP + G-CSF with intermediate-dose cytarabine (ID-AraC) + G-CSF, recently proposed as an alternative schedule. Consecutive patients with Hodgkin's or non-Hodgkin lymphoma who had received at least 2 lines of chemotherapy, mobilized with either DHAP (n = 51) or ID-AraC (n = 50) + G-CSF were included in the analysis. AraC was administered at the dose of 400 mg/m [1] bid intravenously for 2 days followed by filgrastim starting from day 5. In the AraC group, 96 % of patients collected at least 2 × 10 [2] CD34(+) cells/kg compared to 71 % in the DHAP group (p = 0.0006). The CD34(+) cell yield was 9.3 (0-30.3) × 10 [2]/kg vs. 5.6 (0-24.8) × 10 [2]/kg, respectively (p = 0.006). A single apheresis was sufficient to achieve the threshold number of CD34(+) cells in 82 % of the cases after AraC compared to 45 % after DHAP (p = 0.001). We conclude that stem cell mobilization using ID-AraC is associated with a significantly higher efficacy than DHAP, allowing for collection of the transplant material in almost all patients with lymphoma. Our observation suggests that ID-AraC + G-CSF may be a preferable mobilization regimen in this setting.

  13. Design of Structurally Efficient Tapered Struts (SETS)

    NASA Technical Reports Server (NTRS)

    Deo, Ravi; Benner, Harry; Vincent, Dawson; Olason, Eric; Harrison, Richard

    2010-01-01

    A study was conducted to develop mass efficient composite struts. A closed-form design methodology for composite struts was developed using well established analyses to predict Euler buckling, local wall buckling; compression strength, damage tolerance, and interlaminar shear at geometric gradients. The methodology was coded in a spreadsheet suitable for convenient and rapid sizing of tapered composite struts. This spreadsheet analysis was used to determine the influence of several variables such as material stiffness, strut diameter, and material allowables on strut weight for given loading conditions. The comparison showed that, while the Park Aerospace design method was well suited to preliminary sizing for a conservative design, the closed-form-analyses-based spreadsheet accounts for all possible failure modes and is a good optimum strut design tool. The report concludes with a set of recommendations for future work in analytical design and analysis methodology enhancements.

  14. Hierarchical tapered bar elements undergoing axial deformation

    NASA Technical Reports Server (NTRS)

    Ganesan, N.; Thampi, S. K.

    1992-01-01

    A method is described to model the dynamics of tapered axial bars of various cross sections based on the well-known Craig/Bampton component mode synthesis technique. This element is formed in terms of the static constraint modes and interface restrained normal modes. This is in contrast with the finite elements as implemented in NASTRAN where the interface restrained normal modes are neglected. These normal modes are in terms of Bessel functions. Restoration of a few of these modes leads to higher accuracy with fewer generalized coordinates. The proposed models are hierarchical so that all lower order element matrices are embedded in higher order element matrices. The advantages of this formulation compared to standard NASTRAN truss element formulation are demonstrated through simple numerical examples.

  15. Pulse propagation in the tapered wiggler

    NASA Astrophysics Data System (ADS)

    Al-Abawi, H.; McIver, J. K.; Moore, G. T.; Scully, M. O.

    Theory and preliminary numerical calculations are presented for coherent optical and electron pulse propagation in a free-electron laser with a tapered wiggler. Since only trapped electrons contribute significantly to the laser radiation, it is possible to define generalized 'slow' space-time coordinates in terms of which the electron pulse envelope may be considered constant. The theory is outlined first for the helical wiggler and then is developed for an arbitrary quasiperiodic wiggler, using a more rigorous 'multiple-scaling' approach. In the latter case a modified definition of the electron phase angle is required, and optical harmonic generation is predicted. The numerical calculations show that substantial energy extraction is achievable, but that the optical pulse rapidly breaks up into a series of spikes in the time domain. Surprisingly, the optical spectrum remains quite smooth in appearance.

  16. Enclosed Cutting-And-Polishing Apparatus

    NASA Technical Reports Server (NTRS)

    Rossier, R. N.; Bicknell, B.

    1989-01-01

    Proposed apparatus cuts and polishes specimens while preventing contamination of outside environment or of subsequent specimens processed in it. Designed for use in zero gravity but also includes features useful in cutting and polishing of toxic or otherwise hazardous materials on Earth. Includes remote manipulator for handling specimens, cutting and polishing wire, inlets for gas and liquid, and outlets for waste liquid and gas. Replaceable plastic liner surrounds working space.

  17. Laser polishing of niobium for SRF applications

    SciTech Connect

    Zhao, Liang; Klopf, J. Michael; Reece, Charles E.; Kelley, Michael

    2013-09-01

    Smooth interior surfaces are desired for niobium SRF cavities, now obtained by buffered chemical polish (BCP) and/or electropolish (EP). Laser polishing is a potential alternative, having advantages of speed, freedom from chemistry and in-process inspection. Here we show that laser polishing can produce smooth topography with Power Spectral Density (PSD) measurements similar to that obtained by EP. We studied the influence of the laser power density and laser beam raster rate on the surface topography. These two factors need to be combined carefully to smooth the surface without damaging it. Computational modeling was used to simulate the surface temperature and explain the mechanism of laser polishing.

  18. Perceptions of and Attitudes towards Regional Varieties of Polish: Views from Two Polish Provinces

    ERIC Educational Resources Information Center

    Milobog, Magdalena; Garrett, Peter

    2011-01-01

    This paper reports a study of perceptions and attitudes relating to regional varieties of Polish. The methodology followed folk linguistic approaches to attitudes research. Respondents in two Polish provinces were asked to draw on a map of Poland where they thought the main regional varieties of Polish were spoken, and then to name and…

  19. Development of small bore, high speed tapered roller bearing

    NASA Technical Reports Server (NTRS)

    Morrison, F. R.; Gassel, S. S.; Bovenkerk, R. L.

    1981-01-01

    The performance of four rolling bearing configurations for use on the input pinion shaft of a proposed commercial helicopter transmission was evaluated. The performance characteristics of a high speed tapered roller bearing operating under conditions comparable to those existing at this input pinion shaft were defined. The tapered roller bearing shaft support configuration was developed for the gearbox using commercially available bearing designings. The configuration was optimized and interactive thermomechanically system analyzed. Automotive pinion quality tapered roller bearings were found to be reliable under load and speed conditions in excess of those anticipated in the helicopter transmission. However, it is indicated that the elastohydrodynamic lubricant films are inadequate.

  20. Nonlinear transmission through a tapered fiber in rubidium vapor

    SciTech Connect

    Hendrickson, S. M.; Pittman, T. B.; Franson, J. D.

    2009-02-15

    Subwavelength-diameter tapered optical fibers surrounded by rubidium vapor can undergo a substantial decrease in transmission at high atomic densities due to the accumulation of rubidium atoms on the surface of the fiber. Here we demonstrate the ability to control these changes in transmission using light guided within the taper. We observe transmission through a tapered fiber that is a nonlinear function of the incident power. This effect can also allow a strong control beam to change the transmission of a weak probe beam.

  1. Free torsional vibrations of tapered cantilever I-beams

    NASA Astrophysics Data System (ADS)

    Rao, C. Kameswara; Mirza, S.

    1988-08-01

    Torsional vibration characteristics of linearly tapered cantilever I-beams have been studied by using the Galerkin finite element method. A third degree polynomial is assumed for the angle of twist. The analysis presented is valid for long beams and includes the effect of warping. The individual as well as combined effects of linear tapers in the width of the flanges and the depth of the web on the torsional vibration of cantilever I-beams are investigated. Numerical results generated for various values of taper ratios are presented in graphical form.

  2. Some novel features of an FEL oscillator with tapered undulator

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Yurkov, M.V.

    1995-12-31

    A one-dimensional analysis of an FEL oscillator with a linear undulator tapering is presented. Some principally novel results have been obtained. The origin of these results is in principal difference between the FEL oscillator and an FEL amplifier. In the case of the FEL amplifier the frequency of the amplified wave and all the other parameters are defined by an experimenter. Contrary to this, the case of the FEL oscillator with tapered undulator is more complicated. The lasing frequency is defined by the maximum of the small-signal gain and depends on the tapering depth in some complex way.

  3. Polish Foundation for Energy Efficiency

    SciTech Connect

    1995-12-31

    The Polish Foundation for Energy Efficiency (FEWE) was established in Poland at the end of 1990. FEWE, as an independent and non-profit organization, has the following objectives: to strive towards an energy efficient national economy, and to show the way and methods by use of which energy efficiency can be increased. The activity of the Foundation covers the entire territory of Poland through three regional centers: in Warsaw, Katowice and Cracow. FEWE employs well-known and experienced specialists within thermal and power engineering, civil engineering, economy and applied sciences. The organizer of the Foundation has been Battelle Memorial Institute - Pacific Northwest Laboratories from the USA.

  4. Tripol condensate polishing - operational experience

    SciTech Connect

    Swainsbury, D.

    1995-01-01

    This paper gives a brief outline of the Mission Energy Management Australia Company who operate and maintain the Loy Yang B Power Station in the Latrobe Valley, Victoria, Australia. Details of the plant configuration, the water/steam circuit and cycle chemistry are discussed. The arrangement of the TRIPOL Condensate Polishing Plant and it`s operational modes are examined. Results of the first twelve months operation of the TRIPOL plant are detailed. Levels of crud removal during early commissioning phases employing the pre-filter are presented. Typical parameters achieved during a simulated condenser leak and an operational run beyond the ammonia break point are also documented.

  5. Drug consumption among Polish centenarians.

    PubMed

    Rajska-Neumann, A; Mossakowska, M; Klich-Rączka, A; Życzkowska, J; Grześkowiak, E; Shieh, S; Wieczorowska-Tobis, K

    2011-01-01

    The aim of the study was to describe the quantitative and qualitative aspects of pharmacotherapy of Polish centenarians. The studied group consisted of 92 centenarians (mean age: 101.7±1.2 years, 77 females, mean age: 101.5±1.2; 15 males mean age: 102.2±1.2). Among the studied subjects, 18 individuals (19.6% of all subjects) did not use any drugs in his or her daily regimen. The mean number of drugs per person was 2.5±2.5 drugs (prescription drugs: 1.9±2.2 and non-prescription drugs: 0.5±0.8). Fifty-six centenarians (60.9% of all studied subjects) took concomitantly 0-3 drugs daily while 36 (39.1%) took more than 3 drugs daily. Within this group, 30 centenarians (32.6%) took 5 or more drugs concomitantly every day. The most commonly used groups of drugs were: gastrointestinal drugs (55 centenarians, 74.3% of all drug consumed), cardiovascular drugs (51 centenarians, 68.9%) and central nervous system drugs (N) (38 centenarians, 51.4%). In the studied group, 6 persons (8.1% of all drug consumers) were taking one potentially inappropriate drug based on the Beers criteria. To conclude, the mean number of drugs, the prevalence of polypharmacy, and the tendency for potential inappropriateness of treatment are lower among Polish centenarians comparing to the common elderly.

  6. Buffered Electrochemical Polishing of Niobium

    SciTech Connect

    Gianluigi Ciovati; Tian, Hui; Corcoran, Sean

    2011-03-01

    The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.

  7. The first Polish total laryngectomies

    PubMed Central

    Paprocka-Borowicz, Małgorzata; Pozowski, Andrzej; Kuciel-Lewandowska, Jadwiga

    2013-01-01

    The total removal of the larynx (total laryngectomy), performed in 1872 by the well-known Viennese surgeon Christian A. Theodor Billroth (1829–1894), was an epoch-making event in the history of surgery and laryngology. This paper presents the first surgeons who performed this operation. The first Pole who performed a total laryngectomy (1877) was Julian Kosiński (1833–1914), head of the Surgical Clinic of Imperial University Warsaw. It was the 14th operation of this kind in the world. Several laryngectomies were carried out by Franciszek Ksawery Jawdyński (1851–1896), called the father of Polish head and neck surgery, who was the first Pole to excise a malignant neck cancer together with the lymph nodes. The next total laryngectomies were performed by the following Polish surgeons: Jan Mikulicz-Radecki (1850–1905), Władysław H.S. Krajewski (1855–1907), Alfred Obaliński (1843–1898). According to Jan Sędziak, by 1897 Poland with 16 laryngectomies (per 188 carried out) had occupied the fourth position in the world. The failures of the first laryngectomies were due to such factors as the ignorance of shock pathophysiology, the inability to ensure the patency of the airways during and after the operation, which would result in lung and mediastinum infections, massive haemorrhages and so on. But the primary cause was the lack of constructive collaboration between the laryngologists and the surgeons. PMID:24592132

  8. Method of polishing nickel-base alloys and stainless steels

    DOEpatents

    Steeves, Arthur F.; Buono, Donald P.

    1981-01-01

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  9. Attack polish for nickel-base alloys and stainless steels

    DOEpatents

    Steeves, Arthur F.; Buono, Donald P.

    1983-01-01

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  10. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    PubMed

    Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-02-01

    Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region.

  11. Radiation Effects on Fused Biconical Taper Wavelength Division Multiplexers

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C.; Swift, Gary M.; Dubovitsky, Serge; Bartman, Randall K.; Barnes, Charles E.; Dorsky, Leonard

    1994-01-01

    The effects of radiation on fused biconical taper wavelength division multiplexers are presented. A theoretical model indicates that index changes in the fiber are primarily responsible for the degradation of these devices.

  12. Optical coupling and splitting with two parallel waveguide tapers.

    PubMed

    Tao, S H

    2011-01-17

    A coupling and splitting device comprising a width taper and a spatial-modulated subwavelength grating waveguide (SSGW) is proposed. The width taper is a waveguide with increasing width and the SSGW is a waveguide grating whose width and thickness are constant but the filling factor increases along the light propagation. Thus, the effective index of the subwavelength grating increases according to the effective medium theory. Light of orthogonal polarizations from a single-mode fiber can be coupled efficiently with the two parallel tapers. Furthermore, the coupled lights of orthogonal polarizations in the two tapers can be further split with connecting bent waveguides. Fabrication of the device is fully compatible with current complementary metal oxide semiconductor technology.

  13. Perfluorinated plastic optical fiber tapers for evanescent wave sensing.

    PubMed

    Gravina, Roberto; Testa, Genni; Bernini, Romeo

    2009-01-01

    In this work we describe the fabrication and the characterization of perfluorinated plastic-cladded optical fiber tapers. The heat-and-pull procedure has been used to fabricate symmetric tapers. Devices with different taper ratio have been produced and the repeatability of the process has been verified. The very low refractive indexes of the core-cladding perfluorinated polymers (n = 1.35-1.34) permit a strong enhancement of the evanescent wave power fraction in aqueous environments (n = 1.33), making them very attractive for evanescent wave sensing. The tapers have been characterized carrying out evanescent field absorbance measurements with different concentrations of methylene blue in water and fluorescence collection measurements in an aqueous solution containing Cy5 dye. A good sensitivity, tightly related to the low refractive index of the core-cladding materials and the geometrical profile, has been shown.

  14. Holding fixture for metallographic mount polishing

    DOEpatents

    Barth, C.H.; Cramer, C.E.

    1997-12-30

    A fixture is described for holding mounted specimens for polishing, having an arm; a body attached to one end of the arm, the body having at least one flange having an opening to accommodate a mounted specimen; and a means applying pressure against the outer surface of the mounted specimen to hold the specimen in contact with the polishing surface. 3 figs.

  15. Holding fixture for metallographic mount polishing

    DOEpatents

    Barth, Clyde H.; Cramer, Charles E.

    1997-01-01

    A fixture for holding mounted specimens for polishing, having an arm; a body attached to one end of the arm, the body having at least one flange having an opening to accommodate a mounted specimen; and a means applying pressure against the outer surface of the mounted specimen to hold the specimen in contact with the polishing surface.

  16. BEGINNING POLISH, VOLUME ONE. YALE LINGUISTIC SERIES.

    ERIC Educational Resources Information Center

    SCHENKER, ALEXANDER M.

    BASED ON A MODERN LINGUISTIC ANALYSIS OF THE POLISH LANGUAGE, THIS TWO-VOLUME TEXT IS APPROPRIATE FOR A ONE-YEAR INTENSIVE COURSE. VOLUME I INCLUDES 25 LESSONS, EACH DIVIDED INTO--SENTENCES (DIALOGS), GRAMMAR, EXERCISES, AND VOCABULARY LISTS. THE INTRODUCTION PRESENTS A BRIEF CONTRASTIVE ANALYSIS OF POLISH AND RUSSIAN, AND THERE IS INCLUDED A…

  17. Optimization of tapered busses for solar cell contacts

    NASA Technical Reports Server (NTRS)

    Landis, G. A.

    1979-01-01

    Some fraction of the power produced by a solar cell is necessarily lost by series resistance associated with the metallized contact grid and by shadowing of cell active area by the grid. There are several approaches to reducing these losses, such as choosing a more efficient pattern, optimizing line spacing, and using tapered buses. The present paper analyzes tapered lines and derives from this analysis a theoretical lower bound to metallization power loss, independent of pattern chosen.

  18. Fabrication and Testing of Tapered Electro-spray Nozzles

    DTIC Science & Technology

    2012-09-01

    oxidized nozzle with broken top cap. 15 The ultrasonic breaking of the etch mask was found to be a low-yield methodology, with some caps breaking...Fabrication and Testing of Tapered Electro-spray Nozzles by Brendan M. Hanrahan and C. Mike Waits ARL-TR-6226 September 2012...September 2012 Fabrication and Testing of Tapered Electro-spray Nozzles Brendan M. Hanrahan and C. Mike Waits Sensors and Electron Devices

  19. Optical inclinometer based on fibre-taper-modal Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Amaral, L. M. N.; Frazão, O.; Santos, J. L.; Lobo Ribeiro, A. B.

    2010-09-01

    An inclinometer sensor based on optical fibre-taper-modal Michelson interferometer is demonstrated. The magnitude of the tilt (bending angle of the fibre taper interferometer) is obtained by passive interferometric interrogation based on the generation of two quadrature phase-shifted signals from two fibre Bragg gratings. Optical phase-to-rotation sensitivity of 1.13 rad/degree with a 14 mrad/√Hz resolution is achieved.

  20. Multimode tapered optical light pipe for illumination systems

    NASA Astrophysics Data System (ADS)

    Romańczuk, Patryk; Pietrzycki, Marcin; Źmojda, Jacek; Kochanowicz, Marcin; Dorosz, Dominik

    2015-09-01

    In the article the multimode tapered optical light pipe for illumination systems was investigated. Based on tree light emitting diodes at the wavelength of 460 nm (blue), 528 nm (green) and 631 nm (red) possibility of white light emission on the output surface of the tapered light pipe was submitted. Influence of optical power of LEDs on the colour coordinates (CIE-1931) has been investigated.

  1. Mean Scatterer Spacing Estimation Using Multi-Taper Coherence

    PubMed Central

    Rubert, Nicholas; Varghese, Tomy

    2013-01-01

    It has been hypothesized that estimates of mean scatterer spacing are useful indicators for pathological changes to the liver. A commonly employed estimator of the mean scatterer spacing is the location of the maximum of the collapsed average of coherence of the ultrasound radio-frequency signal. To date, in ultrasound, estimators for this quantity have been calculated with a single taper. Using frequency-domain Monte Carlo simulations, we demonstrate that multi-taper estimates of coherence are superior to single-taper estimates for predicting mean scatterer spacing. Scattering distributions were modeled with Gamma-distributed scatterers for fractional standard deviations in scatterer spacings of 5, 10, and 15% at a mean scatterer spacing of 1 mm. Additionally, we demonstrate that we can distinguish between ablated liver tissue and unablated liver tissue based on signal coherence. We find that, on the average, signal coherence is elevated in the liver relative to signal coherence of received echoes from thermally ablated tissue. Additionally, our analysis indicates that a tissue classifier utilizing the multi-taper estimate of coherence has the potential to distinguish between ablated and unablated tissue types better than a single-taper estimate of coherence. For a gate length of 5 mm, we achieved an error rate of only 8.7% when sorting 23 ablated and 23 unablated regions of interest (ROIs) into classes based on multi-taper calculations of coherence. PMID:25004470

  2. Molecular Dynamics Simulations of Penetrants in Microphase Separated Tapered Diblock Copolymers

    NASA Astrophysics Data System (ADS)

    Seo, Youngmi; Brown, Jonathan R.; Hall, Lisa M.

    Tapered AB diblock copolymers contain pure A and B monomer blocks on the ends with a tapered midblock of intermediate composition, providing taper length as an additional tuning parameter to control microphase separation and interfacial behavior. We model the midblock as a statistical linear gradient from pure A to pure B. Recent experiments with salt dissolved in one of microphases show that a certain length of taper increases ion conductivity while the same length of inverse taper lowers conductivity. We perform coarse-grained molecular dynamics simulations of tapered copolymers with monomer sized penetrants, which have preferential interactions with one microphase, to better understand this observation and the general effects of tapering on dynamics. We calculate penetrant diffusion, polymer relaxation times, and other quantities over the range from 0% (diblock) to 100% (full gradient) taper length, with the taper direction either normal or inverse (with the A side of the taper connected to the pure B block). Normal taper results typically lie between those of diblocks and full gradients, while inverse tapers show strong nonmonotonic behavior as a function of taper length. For intermediate length inverse tapers, penetrant and monomer dynamics are significantly slower than those of diblocks or normal tapers, and this relates to the folding of the inverse chains back and forth across the interface. To provide further insight, we also compare to the dynamics of random copolymers of various compositions. Based upon work supported by NSF Grant 1454343.

  3. Experiences with polishing electroless nickel

    SciTech Connect

    Brown, N.J.; Taylor, J.S.; Fuchs, B.A.

    1991-04-01

    During recent years the bureaucracy has become increasingly rigid in demanding a mechanical observance of the minimum bid specified on the simplest terms. Qualifications of the vendor and specifications of the product are increasingly viewed as attempts to thwart the progress of the process toward minimum quality, Any such qualification or specification must be justified as to not only reasonableness but necessity. This provides the purpose of this paper, to record forever the existence of the wild dingleberry and to disclose its habits with respect to laps and the marvelous effects it has on the emotional state of the lappers. Among metal polishers, the term dingleberry refers to a type of nodule or wartlike structure sometimes seen in isolation and occasionally in considerable profusion particularly in chemically plated surfaces. 2 refs.

  4. Psychological profile of Polish skydivers.

    PubMed

    Próchniak, Piotr

    2011-02-01

    To identify personality factors, personal values, time perspective, and attitude toward death of 53 Polish skydivers (M age = 28.4 yr., SD = 9.8) and 59 low-risk sport athletes (controls, M age = 27.3 yr., SD = 5.3), several scales were used. These were the Zuckerman-Kuhlman Personality Questionnaire, Schwartz's Value Survey, the Present and Future Time Perspective Questionnaire, and Death Attitude Questionnaire. It was found that skydivers scored higher on Impulsive Sensation Seeking, Hedonism, Stimulation, and Self-direction values, concentration on the present, preferring a fast death, and belief about controlling death in comparison to the control group. Skydivers also scored lower on Tradition, Universalism, and Benevolence values in comparison to the control group.

  5. Careers of young Polish chemists.

    PubMed

    Kosmulski, Marek

    Typical young Polish scientist is an alumnus of doctoral studies at the same university and department where he/she completed his/her Master degree. The career is continued by receiving a habilitation at the same university and department. Then a holder of habilitation is promoted to a tenured position at the same university and department. Detailed analysis of scientific careers of 154 recent Ph.D. recipients and of 16 habilitation candidates in chemistry from University of Warsaw is presented. More than 96 % of the Ph.D. theses were results of doctoral studies. A typical doctor is Polish citizen (>98 %), alumnus/alumna of the University of Warsaw (>85 %), holder of Master degree in chemistry (88 %) who joined the Ph.D. program at the same university directly after having completed his/her Master degree, and completed the Ph.D. program 5.5 years after completion of Master degree. A fraction of recent female Ph.D. recipients in chemistry (61 %) is very high as compared with the corresponding fractions in other countries (e.g., USA), but it is still substantially lower than the fraction of female Master degree recipients. In recent habilitation candidates, the female ratio is 50 %, thus relative male dominance is observed at higher levels. At least one-third of the recent Ph.D. recipients were employed by the same university, where they received their Ph.D., while the fraction of the recent Ph.D. recipients employed by other universities in Poland was below 5 %. High degree of academic inbreeding is due to the legal system in Poland, which (nominally) is designed to prevent academic inbreeding, but the regulations can be easily circumvented. Over 10 % of the recent Ph.D. recipients found post-doctoral positions abroad, chiefly in EU countries and in the USA.

  6. Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres

    PubMed Central

    Suratwala, Tayyab; Steele, Rusty; Feit, Michael; Dylla-Spears, Rebecca; Desjardin, Richard; Mason, Dan; Wong, Lana; Geraghty, Paul; Miller, Phil; Shen, Nan

    2014-01-01

    Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial shape (i.e., surface figure), will converge to final surface figure with excellent surface quality under a fixed, unchanging set of polishing parameters in a single polishing iteration. In contrast, conventional full aperture polishing methods require multiple, often long, iterative cycles involving polishing, metrology and process changes to achieve the desired surface figure. The Convergent Polishing process is based on the concept of workpiece-lap height mismatch resulting in pressure differential that decreases with removal and results in the workpiece converging to the shape of the lap. The successful implementation of the Convergent Polishing process is a result of the combination of a number of technologies to remove all sources of non-uniform spatial material removal (except for workpiece-lap mismatch) for surface figure convergence and to reduce the number of rogue particles in the system for low scratch densities and low roughness. The Convergent Polishing process has been demonstrated for the fabrication of both flats and spheres of various shapes, sizes, and aspect ratios on various glass materials. The practical impact is that high quality optical components can be fabricated more rapidly, more repeatedly, with less metrology, and with less labor, resulting in lower unit costs. In this study, the Convergent Polishing protocol is specifically described for fabricating 26.5 cm square fused silica flats from a fine ground surface to a polished ~λ/2 surface figure after polishing 4 hr per surface on a 81 cm diameter polisher. PMID:25489745

  7. Zeeko precession for free-form polishing

    NASA Astrophysics Data System (ADS)

    Procháska, F.; Poláková, I.; Polák, J.; Matoušek, O.; Tomka, D.

    2016-11-01

    The aim of this work is an exploration of the options for optical surface polishing using the Zeeko IRP 100 machine and raster kinematics suitable for free-form polishing. For this purpose, aspheric surfaces were polished in raster prepolishing mode and then in Precession raster 3D shape correction, which is based on the Dwell time tool movement control. It was found that shape accuracy can achieve the value of approximately 35 nm RMS. The main inaccuracy was caused by the mid-spatial frequencies generated by the kinematics of the applied tools, which also limited the achievable values of microroughness.

  8. Macromodel for changes in polishing pad surface condition caused by dressing and polishing

    NASA Astrophysics Data System (ADS)

    Isobe, Akira; Ogata, Kenjiro; Kurokawa, Shuhei

    2014-01-01

    A macromodel for changes in a pad surface by dressing and polishing is proposed. A polishing pad is divided into small areas and it is assumed that each area takes an “H” (= high) or “L” (= low) condition. The condition is changed by dressing or polishing, and the total chemical mechanical planarization (CMP) performance is determined by the average pad condition. The results from equations are compared with experimental data, and good correspondence is confirmed. Various CMP behaviors are well explained by the equations, such as polishing rate stabilization by dummy running, the differences in the stability time and polishing rate between in situ dressing and ex situ dressing, and polishing rate behaviors for patterned wafers. This new model can be used to predict process performances, to optimize process conditions, or to indicate the direction of consumable development.

  9. Chemical mechanical polishing of freestanding GaN substrates

    NASA Astrophysics Data System (ADS)

    Huaiyue, Yan; Xiangqian, Xiu; Zhanhui, Liu; Rong, Zhang; Xuemei, Hua; Zili, Xie; Ping, Han; Yi, Shi; Youdou, Zheng

    2009-02-01

    Chemical mechanical polishing (CMP) has been used to produce smooth and scratch-free surfaces for GaN. In the aqueous solution of KOH, GaN is subjected to etching. At the same time, all surface irregularities, including etch pyramids, roughness after mechanical polishing and so on will be removed by a polishing pad. The experiments had been performed under the condition of different abrasive particle sizes of the polishing pad. Also the polishing results for different polishing times are analyzed, and chemical mechanical polishing resulted in an average root mean square (RMS) surface roughness of 0.565 nm, as measured by atomic force microscopy.

  10. Tapered Implants in Dentistry: Revitalizing Concepts with Technology: A Review.

    PubMed

    Wilson, T G; Miller, R J; Trushkowsky, R; Dard, M

    2016-03-01

    The most common approach to lessen treatment times is by decreasing the healing period during which osseointegration is established. Implant design parameters such as implant surface, primary stability, thread configuration, body shape, and the type of bone have to be considered to obtain this objective. The relationship that exists between these components will define the initial stability of the implant. It is believed implant sites using a tapered design and surface modification can increase the primary stability in low-density bone. Furthermore, recent experimental preclinical work has shown the possibility of attaining primary stability of immediately loaded, tapered dental implants without compromising healing and rapid bone formation while minimizing the implant stability loss at compression sites. This may be of singular importance with immediate/early functional loading of single implants placed in poor-quality bone. The selection of an implant that will provide adequate stability in bone of poor quality is important. A tapered-screw implant design will provide adequate stability because it creates pressure on cortical bone in areas of reduced bone quality. Building on the success of traditional tapered implant therapy, newer tapered implant designs should aim to maximize the clinical outcome by implementing new technologies with adapted clinical workflows.

  11. In vitro corrosion testing of modular hip tapers.

    PubMed

    Goldberg, Jay R; Gilbert, Jeremy L

    2003-02-15

    The in vivo fretting behavior of modular hip prostheses was simulated to determine the effects of material combination and a unique TiN/AlN coating on fretting and corrosion at the taper interface. Fretting current, open-circuit potential (OCP), and quantities of soluble debris were measured to determine the role of mechanically assisted crevice corrosion on fretting and corrosion of modular hip tapers. Test groups consisting of similar-alloy (Co-Cr-Mo head/Co-Cr-Mo neck), mixed-alloy (Co-Cr-Mo head/Ti-6Al-4V neck), and TiN/AlN-coated mixed-alloy modular hip taper couples were used. Loads required to initiate fretting were similar for all test groups and were well below loads produced by walking and other physical activities. Decreases in OCP and increases in fretting current observed during long-term cyclic loading were indicative of fretting and corrosion. Current measured after cessation of cyclic loading suggests that once the conditions for crevice corrosion are established, corrosion can continue in the absence of loading. The chemical, mechanical, and electrochemical measurements, along with microscopic inspections of the taper surfaces indicate that the fretting and corrosion behavior of similar- and mixed-alloy taper couples are similar and that the coated samples are more resistant to fretting and corrosion. The results of this study clearly indicate the role of mechanical loading in the corrosion process, and support the hypothesis of mechanically assisted crevice corrosion.

  12. Modeling and multidimensional optimization of a tapered free electron laser

    NASA Astrophysics Data System (ADS)

    Jiao, Y.; Wu, J.; Cai, Y.; Chao, A. W.; Fawley, W. M.; Frisch, J.; Huang, Z.; Nuhn, H.-D.; Pellegrini, C.; Reiche, S.

    2012-05-01

    Energy extraction efficiency of a free electron laser (FEL) can be greatly increased using a tapered undulator and self-seeding. However, the extraction rate is limited by various effects that eventually lead to saturation of the peak intensity and power. To better understand these effects, we develop a model extending the Kroll-Morton-Rosenbluth, one-dimensional theory to include the physics of diffraction, optical guiding, and radially resolved particle trapping. The predictions of the model agree well with that of the GENESIS single-frequency numerical simulations. In particular, we discuss the evolution of the electron-radiation interaction along the tapered undulator and show that the decreasing of refractive guiding is the major cause of the efficiency reduction, particle detrapping, and then saturation of the radiation power. With this understanding, we develop a multidimensional optimization scheme based on GENESIS simulations to increase the energy extraction efficiency via an improved taper profile and variation in electron beam radius. We present optimization results for hard x-ray tapered FELs, and the dependence of the maximum extractable radiation power on various parameters of the initial electron beam, radiation field, and the undulator system. We also study the effect of the sideband growth in a tapered FEL. Such growth induces increased particle detrapping and thus decreased refractive guiding that together strongly limit the overall energy extraction efficiency.

  13. Temperature distribution and scuffing of tapered roller bearing

    NASA Astrophysics Data System (ADS)

    Wang, Ailin; Wang, Jiugen

    2014-11-01

    In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.

  14. Deterministic polishing from theory to practice

    NASA Astrophysics Data System (ADS)

    Hooper, Abigail R.; Hoffmann, Nathan N.; Sarkas, Harry W.; Escolas, John; Hobbs, Zachary

    2015-10-01

    Improving predictability in optical fabrication can go a long way towards increasing profit margins and maintaining a competitive edge in an economic environment where pressure is mounting for optical manufacturers to cut costs. A major source of hidden cost is rework - the share of production that does not meet specification in the first pass through the polishing equipment. Rework substantially adds to the part's processing and labor costs as well as bottlenecks in production lines and frustration for managers, operators and customers. The polishing process consists of several interacting variables including: glass type, polishing pads, machine type, RPM, downforce, slurry type, baume level and even the operators themselves. Adjusting the process to get every variable under control while operating in a robust space can not only provide a deterministic polishing process which improves profitability but also produces a higher quality optic.

  15. Polishing X-ray Mirror Mandrel

    NASA Technical Reports Server (NTRS)

    1999-01-01

    NASA's Space Optics Manufacturing Center has been working to expand our view of the universe via sophisticated new telescopes. The Optics Center's goal is to develop low-cost, advanced space optics technologies for the NASA program in the 21st century - including the long-term goal of imaging Earth-like planets in distant solar systems. To reduce the cost of mirror fabrication, Marshall Space Flight Center (MSFC) has developed replication techniques, the machinery, and materials to replicate electro-formed nickel mirrors. The process allows fabricating precisely shaped mandrels to be used and reused as masters for replicating high-quality mirrors. MSFC's Space Optics Manufacturing Technology Center (SOMTC) has grinding and polishing equipment ranging from conventional spindles to custom-designed polishers. These capabilities allow us to grind precisely and polish a variety of optical devices, including x-ray mirror mandrels. This image shows Charlie Griffith polishing the half-meter mandrel at SOMTC.

  16. The Crisis of Polish Higher Education.

    ERIC Educational Resources Information Center

    Piasek, Ryszard; Vaughan, Michalina

    1987-01-01

    A discussion of recent declining enrollment in Polish higher education looks at the underlying demographic, economic, social, and policy factors causing changes in higher education in general, in specific institutions and faculties, and in women's participation. (MSE)

  17. Polish women's experiences of breastfeeding in Ireland.

    PubMed

    Szafranska, Marcelina; Gallagher, Louise

    2016-01-01

    Exclusive breastfeeding among Polish mothers at three-four months (38.6 per cent) is in keeping with the low rates of breastfeeding in Ireland overall (Begley et al 2008), and suggests that Polish women have begun to adopt the infant feeding practices of Irish women. Therefore, the aim of this study was to explore the factors that influence Polish women's decisions to initiate and continue breastfeeding in Ireland. A descriptive qualitative approach was utilised to explore participants' perspectives of breastfeeding. Results showed that professional and family support are key to a successful breastfeeding experience for these mothers. Recommendations include further individualised support in order to meet the needs of Polish women breastfeeding in Ireland.

  18. The influence of contact conditions and micromotions on the fretting behavior of modular titanium alloy taper connections.

    PubMed

    Baxmann, M; Jauch, S Y; Schilling, C; Blömer, W; Grupp, T M; Morlock, M M

    2013-05-01

    Modularity of femoral stems and neck components has become a more frequently used tool for an optimized restoration of the hip joint center and improvement of patient biomechanics. The additional taper interface increases the risk of mechanical failure due to fretting and crevice corrosion. Several failures of titanium alloy neck adapters have been documented in case-reports. An experimental fretting device was developed in this study to systematically investigate the effect of micromotion and contact pressure on fretting damage in contact situations similar to taper interfaces of modular hip prostheses under cyclic loading representative of in vivo load conditions. As a first application, the fretting behavior of Ti-6Al-4V titanium alloy components was investigated. Micromotions were varied between 10μm and 50μm, maximum contact pressures between 400 and 860N/mm(2). All modes of fretting damage were observed: Fretting wear was found for high micromotions in combination with low contact pressures. Fretting fatigue occurred with reduced movement or increased contact pressures. With small micromotions or high normal pressures, low fretting damage was observed. The developed device can be used to evaluate taper design (and especially contact geometry) as well as different materials prior to clinical use.

  19. Attack polish for nickel-base alloys and stainless steels

    DOEpatents

    Not Available

    1980-05-28

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels is described. The chemical attack polich comprises FeNO/sub 3/, concentrated CH/sub 3/COOH, concentrated H/sub 2/SO/sub 4/ and H/sub 2/O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  20. Tapered rib fiber coupler for semiconductor optical devices

    DOEpatents

    Vawter, Gregory A.; Smith, Robert Edward

    2001-01-01

    A monolithic tapered rib waveguide for transformation of the spot size of light between a semiconductor optical device and an optical fiber or from the fiber into the optical device. The tapered rib waveguide is integrated into the guiding rib atop a cutoff mesa type semiconductor device such as an expanded mode optical modulator or and expanded mode laser. The tapered rib acts to force the guided light down into the mesa structure of the semiconductor optical device instead of being bound to the interface between the bottom of the guiding rib and the top of the cutoff mesa. The single mode light leaving or entering the output face of the mesa structure then can couple to the optical fiber at coupling losses of 1.0 dB or less.

  1. Confinement loss in adiabatic photonic crystal fiber tapers

    NASA Astrophysics Data System (ADS)

    Kuhlmey, Boris T.; Nguyen, Hong C.; Steel, M. J.; Eggleton, Benjamin J.

    2006-09-01

    We numerically study confinement loss in photonic crystal fiber (PCF) tapers and compare our results with previously published experimental data. Agreement between theory and experiment requires taking into account hole shrinkage during the tapering process, which we measure by using a noninvasive technique. We show that losses are fully explained within the adiabatic approximation and that they are closely linked to the existence of a fundamental core-mode cutoff. This cutoff is equivalent to the core-mode cutoff in depressed-cladding fibers, so that losses in PCF tapers can be obtained semiquantitatively from an equivalent depressed-cladding fiber model. Finally, we discuss the definition of adiabaticity in this open boundary problem.

  2. Wind-tunnel research comparing lateral control devices, particularly at high angles of attack IX : tapered wings with ordinary ailerons

    NASA Technical Reports Server (NTRS)

    Weick, Fred E; Wenzinger, Carl J

    1933-01-01

    Tests were made with ordinary flap-type ailerons on two wings with different amounts of taper, one medium and the other extreme. On each wing both medium sized tapered ailerons and short wide tapered ailerons were tested.

  3. Single muscle fiber gene expression with run taper.

    PubMed

    Murach, Kevin; Raue, Ulrika; Wilkerson, Brittany; Minchev, Kiril; Jemiolo, Bozena; Bagley, James; Luden, Nicholas; Trappe, Scott

    2014-01-01

    This study evaluated gene expression changes in gastrocnemius slow-twitch myosin heavy chain I (MHC I) and fast-twitch (MHC IIa) muscle fibers of collegiate cross-country runners (n = 6, 20±1 y, VO₂max = 70±1 ml•kg-1•min-1) during two distinct training phases. In a controlled environment, runners performed identical 8 kilometer runs (30:18±0:30 min:s, 89±1% HRmax) while in heavy training (∼72 km/wk) and following a 3 wk taper. Training volume during the taper leading into peak competition was reduced ∼50% which resulted in improved race times and greater cross-section and improved function of MHC IIa fibers. Single muscle fibers were isolated from pre and 4 hour post run biopsies in heavily trained and tapered states to examine the dynamic acute exercise response of the growth-related genes Fibroblast growth factor-inducible 14 (FN14), Myostatin (MSTN), Heat shock protein 72 (HSP72), Muscle ring-finger protein-1 (MURF1), Myogenic factor 6 (MRF4), and Insulin-like growth factor 1 (IGF1) via qPCR. FN14 increased 4.3-fold in MHC IIa fibers with exercise in the tapered state (P<0.05). MSTN was suppressed with exercise in both fiber types and training states (P<0.05) while MURF1 and HSP72 responded to running in MHC IIa and I fibers, respectively, regardless of training state (P<0.05). Robust induction of FN14 (previously shown to strongly correlate with hypertrophy) and greater overall transcriptional flexibility with exercise in the tapered state provides an initial molecular basis for fast-twitch muscle fiber performance gains previously observed after taper in competitive endurance athletes.

  4. Technology Development for Tapered-Wiggler Free-Electron Lasers

    DTIC Science & Technology

    1984-04-01

    canting can produce equal e-beam focusing in each of the two - transverse directions. Thus the e-beam focusing characteristics of a helical wiggler can...Both taper prescriptions require a modest frequency chirp of less than 1.5 percent during start-up. 3.2 VARIALE -TAPER WIGGLER EMAWQEM DEVEPHE T This...with Nonuniform Wigglers," IEEE J. Quantum Electron. QE-16, 335 (1980). 4-8. J.P. Blewett and R. Chasman, "Orbits and Fields in the Helical Wiggler," J

  5. Bent optical fiber tapers for refractometery and biosensing

    NASA Astrophysics Data System (ADS)

    Penchev, Emil; Eftimov, Tinko; Bock, Wojtek

    2015-01-01

    We report the results of our study of the spectral shifts caused by surrounding refractive index changes (SRI) in bent fibre tapers. Fused and etched fibre tapers were fabricated using a gas burner and HF acid. Spectral shifts as high as 200 nm have been observed for SRI variations from 1.33 to 1.44 and sensitivity as high as 830 nm/r.i.u. around water RI values. We present results for refractometric measurements of cow milk of varying fat content and compare results with those obtained with conventional Abbe refractometers and high sensitivity double resonance LPGs.

  6. Impedance Scaling for Small-angle Tapers and Collimators

    SciTech Connect

    Stupakov, G.; /SLAC

    2010-02-11

    In this note I will prove that the impedance calculated for a small-angle collimator or taper, of arbitrary 3D profile, has a scaling property that can greatly simplify numerical calculations. This proof is based on the parabolic equation approach to solving Maxwell's equation developed in Refs. [1, 2]. We start from the parabolic equation formulated in [3]. As discussed in [1], in general case this equation is valid for frequencies {omega} >> c/a where a is a characteristic dimension of the obstacle. However, for small-angle tapers and collimators, the region of validity of this equation extends toward smaller frequencies and includes {omega} {approx} c/a.

  7. Opioid abstinence reinforcement delays heroin lapse during buprenorphine dose tapering.

    PubMed

    Greenwald, Mark K

    2008-01-01

    A positive reinforcement contingency increased opioid abstinence during outpatient dose tapering (4, 2, then 0 mg/day during Weeks 1 through 3) in non-treatment-seeking heroin-dependent volunteers who had been maintained on buprenorphine (8 mg/day) during an inpatient research protocol. The control group (n=12) received $4.00 for completing assessments at each thrice-weekly visit during dose tapering; 10 of 12 lapsed to heroin use 1 day after discharge. The abstinence reinforcement group (n=10) received $30.00 for each consecutive opioid-free urine sample; this significantly delayed heroin lapse (median, 15 days).

  8. Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators

    SciTech Connect

    Rittershofer, W.; Schroeder, C.B.; Esarey, E.; Gruner, F.J.; Leemans, W.P.

    2010-05-17

    Tapered plasma channels are considered for controlling dephasing of a beam with respect to a plasma wave driven by a weakly-relativistic, short-pulse laser. Tapering allows for enhanced energy gain in a single laser plasma accelerator stage. Expressions are derived for the taper, or longitudinal plasma density variation, required to maintain a beam at a constant phase in the longitudinal and/or transverse fields of the plasma wave. In a plasma channel, the phase velocities of the longitudinal and transverse fields differ, and, hence, the required tapering differs. The length over which the tapered plasma density becomes singular is calculated. Linear plasma tapering as well as discontinuous plasma tapering, which moves beams to adjacent plasma wave buckets, are also considered. The energy gain of an accelerated electron in a tapered laser-plasma accelerator is calculated and the laser pulse length to optimize the energy gain is determined.

  9. Efficient sub-wavelength light confinement using surface plasmon polaritons in tapered fibers.

    PubMed

    Renna, Fabrizio; Cox, David; Brambilla, Gilberto

    2009-04-27

    Light confinement to sub-wavelength spot sizes is proposed and realized in tapered optical fibers. To achieve high transmission efficiencies, light propagating along the taper is combined with the excitation of surface plasmon polaritons (SPP) at its tip.

  10. Effects of taper on drilling and cutting with a pulsed laser

    NASA Astrophysics Data System (ADS)

    Angell, James; Ho, Wen; Schaeffer, Ronald D.

    1997-04-01

    An inherent characteristic of laser machined features is taper. For a particular laser the degree of taper is largely dependent on two things: the type of material being machined and the laser energy per unit area or fluence at the processing surface. The latter of these is dependent on different parameters for the three lasers mentioned above. In this paper we review the particular laser parameters that control taper and what degree of taper can be expected for certain materials. More often than not taper is a nondesirable characteristic and is, in many cases, the limiting factor regarding the maximum thickness of material that a laser is practically capable of drilling or cutting through. We therefore discuss methods of minimizing taper and its effects. Under some circumstances taper can be used to one's advantage to achieve a desired feature size if one has control over the taper angle.

  11. Effects of taper on drilling and cutting with a pulsed laser

    NASA Astrophysics Data System (ADS)

    Angell, James; Ho, Wen; Schaeffer, Ronald D.

    1997-03-01

    An inherent characteristic of laser machined features is taper. For a particular laser the degree of taper is largely dependent on two things: the type of material being machined and the laser energy per unit area or fluence at the processing surface. The latter of these is dependent on different parameters for the three lasers mentioned above. In this paper we review the particular laser parameters that control taper and what degree of taper can be expected for certain materials. More often than not taper is a nondesirable characteristic and is, in many cases, the limiting factor regarding the maximum thickness of material that a laser is practically capable of drilling or cutting through. We therefore discuss methods of minimizing taper and its effects. Under some circumstances taper can be used to one's advantage to achieve a desired feature size if one has control over the taper angle.

  12. Fabrication and characterization of bare Ge-Sb-Se chalcogenide glass fiber taper

    NASA Astrophysics Data System (ADS)

    Luo, Baohua; Wang, Yingying; Sun, Ya'nan; Dai, Shixun; Yang, Peilong; Zhang, Peiqing; Wang, Xunsi; Chen, Feifei; Wang, Rongping

    2017-01-01

    In this work, Ge15Sb20Se65 bare glass fiber with a diameter of 500 μm was fabricated, and then tapered with different tapering parameters. The analysis of Raman and energy dispersive X-ray spectra (EDS) indicated that, a slight change in the chemical composition of the glass, fiber and tapering fiber has negligible effect on the glass structure. It was found that, the waist diameter decreases exponentially with increasing tapering length and speed, and high quality taper fiber with the cone diameter of 2.65 μm can be achieved under the optimal tapering conditions. Finally, the simulated and experimental results of the output transmission under different waist length and taper ratio show that the transmission decreases with increasing waist length and taper ratio.

  13. Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier

    SciTech Connect

    Hidaka, Y.; She, Y.; Murphy, J.B.; Podobedov, B.; Seletskiy, S.; Yang, X.

    2011-03-28

    We report experimental studies of the effect of undulator tapering on superradiance in a single-pass high-gain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform and tapered undulator were experimentally characterized using frequency-resolved optical gating (FROG) images. Numerical studies predicted pulse broadening and spectral cleaning by undulator tapering Pulse broadening was experimentally verified. However, spectral cleanliness degraded with tapering. We have performed first experiments with a tapered undulator and a short seed laser pulse. Pulse broadening with tapering expected from simulations was experimentally confirmed. However, the experimentally obtained spectra degraded with tapering, whereas the simulations predicted improvement. A further numerical study is under way to resolve this issue.

  14. Internet Use of Polish by Polish Melburnians: Implications for Maintenance and Teaching

    ERIC Educational Resources Information Center

    Fitzgerald, Michael; Debski, Robert

    2006-01-01

    The Internet has become an important communication medium and it is having a significant impact on language use. The present study takes a "snapshot" of how the Polish language is currently used with modern communications technologies by Polish-Australians living in Melbourne. Through a questionnaire, it surveys which communications…

  15. Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian D.

    2009-01-01

    This paper establishes a relationship between the polishing process parameters and the generation of mid spatial-frequency error. The consideration of the polishing lap design to optimize the process in order to keep residual errors to a minimum and optimization of the process (speeds, stroke, etc.) and to keep the residual mid spatial-frequency error to a minimum, is also presented.

  16. Polish parliament liberalizes abortion law.

    PubMed

    1996-11-22

    On October 24, the Sejm (Poland's lower house of parliament) voted 228 to 195 (with 16 abstentions) to amend Poland's March 1993 ban on abortions. The amendment legalizes abortion until the 12th week of pregnancy for women who face financial hardship or difficult personal circumstances. Client counseling by a doctor who will not perform the abortion and a 3-day wait are required. Abortions will be permitted in licensed private clinics, as well as in public hospitals. Anyone performing an illegal abortion can receive 2 years' imprisonment. The government will subsidize contraceptive pills, and a sex education curriculum will be developed for schools. Abortion had been legal and widely available under communist rule; however, a Catholic-aligned government limited abortion to cases where a woman's life or health was endangered, where the pregnancy resulted from rape or incest, or where the fetus had a severe anomaly. The Catholic Church opposed the new measure, and the Senat (Poland's upper house), on October 3, had voted 40 to 52 (with 2 abstentions) against the amendment. Although the Sejm had previously voted 208 to 61 (with 15 abstentions) in favor of the amendment, 120 of those opposed to the measure, primarily members of the Polish Peasants Party (part of Poland's ruling coalition), had walked out in protest just before an August tally. The Democratic Left Alliance, the other coalition partner, supports the amendment. The most recent vote in the Sejm overturns the Senat veto; however, before the law can go into effect in 1997, it must be signed by President Aleksandr Kwasniewski (a supporter) after a review by Poland's conservative constitutional tribunal.

  17. New technology in condensate polishing

    SciTech Connect

    Kunin, R.; Salem, E.; Libutti, B. . Water Div.)

    1992-08-01

    Sulfonic acid ion exchange resins. when carried into a boiler or steam generator, thermally decompose releasing large amounts of corrosive, sulfates. Replacement of the sulfonic acid resin with a carboxylic acid resin would eliminate this source of contamination. The sulfonic acid resin is a strong acid: the carboxylic acid resin is a weak acid. The carboxylic acid resin alone is not capable of splitting salts which limits its use to mixed resin beds or to its use in single or individual beds with feeds of high alkalinity or high pH values. Laboratory, pilot plant and full scale plant tests compared the two resins in precoat filters. When the resins in mixed beds were in the acid form, the weakly acid resin was almost as effective in removing sodium ion as the strongly acid resin. In the ammonium form. the weakly acid resin was generally more effective in removing sodium than the strongly acid resin. Condensate polishing reduced the sodium ion to a few parts per billion (ppB). Complete resin separation before regeneration is more important for the weakly acid resin than for the strongly acid resin. Another development found that the hydrazine reaction with oxygen could be catalyzed by powdered activated carbon combined with microfibers on a Powdex substrate. The carbon should be thoroughly washed to reduce its residual sodium content. In plant tests, the carbon reduced the oxygen concentration in condensate about 50% during startup. In preliminary tests believed to be typical, carbon lowered the oxygen concentration below 10 ppB in about 6 hours compared to 18 hours without the carbon. Oxygen is also reduced during normal operation.

  18. Optimization of group delay response of (apodized) tapered fiber Bragg grating by shaping taper transition and apodization window

    NASA Astrophysics Data System (ADS)

    Markowski, Konrad; Jedrzejewski, Kazimierz; Osuch, Tomasz

    2016-09-01

    This article presents implementation of the Simulated Annealing (SA) algorithm for tapered fiber Bragg gratings (TFBGs) design. Particularly, together with well-known Coupled Mode Theory (CMT) and Transfer Matrix Method (TMM) the algorithm optimizes the group delay response of TFBG, by simultaneous shaping of both apodization function and tapered fiber transition profile. Prior to the optimization process, numerical model for TFBG design has been validated. Preliminary results reveal great potential of the SA-based approach and with proper definition of the design criteria may be even applied for optimization of the spectral properties of TFBGs.

  19. STEM, STEM Education, STEMmania

    ERIC Educational Resources Information Center

    Sanders, Mark

    2009-01-01

    In this article, the author introduces integrative STEM (science, technology, engineering, and/or mathematics) education and discusses the importance of the program. The notion of integrative STEM education includes approaches that explore teaching and learning between/among any two or more of the STEM subject areas, and/or between a STEM subject…

  20. Ultraviolet-extended flat supercontinuum generation in cascaded photonic crystal fiber tapers

    NASA Astrophysics Data System (ADS)

    Chen, H. H.; Chen, Z. L.; Zhou, X. F.; Hou, J.

    2013-08-01

    Cascaded photonic crystal fiber (PCF) tapers in a monolithic fiber obtained by post-processing techniques such as hole inflation and tapering have been manufactured. An ultraviolet-extended supercontinuum (SC) generation down to 352 nm wavelength pumped at 1064 nm in cascading PCF tapers has been obtained. High spectral flatness (5 dB) has been achieved in the entire visible window.

  1. Impedance Matching of Tapered Slot Antenna using a Dielectric Transformer

    NASA Technical Reports Server (NTRS)

    Simons, R. N.; Lee, R. Q.

    1998-01-01

    A new impedance matching technique for tapered slot antennas using a dielectric transformer is presented. The technique is demonstrated by measuring the input impedance, Voltage Standing Wave Ratio (VSWR) and the gain of a Vivaldi antenna (VA). Measured results at Ka-Band frequencies are presented and discussed.

  2. Linearly tapered slot antenna circular array for mobile communications

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Kelly, Eron; Lee, Richard Q.; Taub, Susan R.

    1993-01-01

    The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

  3. Tapered fiber bundles for combining high-power diode lasers.

    PubMed

    Kosterin, Andrey; Temyanko, Valery; Fallahi, Mahmoud; Mansuripur, Masud

    2004-07-01

    Tapered fiber bundles are often used to combine the output power of several semiconductor lasers into a multimode optical fiber for the purpose of pumping fiber lasers and amplifiers. It is generally recognized that the brightness of such combiners does not exceed the brightness of the individual input fibers. We report that the brightness of the tapered fibers (and fiber bundles) depends on both the taper ratio and the mode-filling properties of the beams launched into the individual fibers. Brightness, therefore, can be increased by selection of sources that fill a small fraction of the input fiber's modal capacity. As proof of concept, we present the results of measurements on tapered fiber-bundle combiners having a low-output étendue. Under low mode-filling conditions per input multimode fiber (i.e., fraction of filled modes < or =0.29), we report brightness enhancements of 8.0 dB for 19 x 1 bundles, 6.7 dB for 7 x 1 bundles, and 4.0 dB for 3 x 1 combiners. Our measured coupling efficiency variations of approximately 1%-2% among the various fibers in a given bundle confirm the uniformity and quality of the fabricated devices.

  4. FSW of Tapered Thickness Welds using an Adjustable Pin Tool

    NASA Technical Reports Server (NTRS)

    Adams, Glynn; Venable, Richard; Lawless, Kirby; Smelser, Jerry (Technical Monitor)

    2002-01-01

    This viewgraph presentation describes the advantages of tapered thickness welds in FSW (friction stir welding), the structure of FSW welds, the adjustable pin tool used in FSW. Other topics described include compliance and temperature measurement in a FSW system, loads and torque upon the pin tool and its ability to penetrate different metals, and the results and metallurgy of FSW welds.

  5. Tapered Roller Bearing Damage Detection Using Decision Fusion Analysis

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Kreider, Gary; Fichter, Thomas

    2006-01-01

    A diagnostic tool was developed for detecting fatigue damage of tapered roller bearings. Tapered roller bearings are used in helicopter transmissions and have potential for use in high bypass advanced gas turbine aircraft engines. A diagnostic tool was developed and evaluated experimentally by collecting oil debris data from failure progression tests conducted using health monitoring hardware. Failure progression tests were performed with tapered roller bearings under simulated engine load conditions. Tests were performed on one healthy bearing and three pre-damaged bearings. During each test, data from an on-line, in-line, inductance type oil debris sensor and three accelerometers were monitored and recorded for the occurrence of bearing failure. The bearing was removed and inspected periodically for damage progression throughout testing. Using data fusion techniques, two different monitoring technologies, oil debris analysis and vibration, were integrated into a health monitoring system for detecting bearing surface fatigue pitting damage. The data fusion diagnostic tool was evaluated during bearing failure progression tests under simulated engine load conditions. This integrated system showed improved detection of fatigue damage and health assessment of the tapered roller bearings as compared to using individual health monitoring technologies.

  6. Pulse Compression using a Tapered Microstructure Optical Fiber

    DTIC Science & Technology

    2006-04-01

    Pulse compression using a tapered microstructure optical fiber Jonathan Hu, Brian S. Marks, and Curtis R. Menyuk University of Maryland Baltimore...R. Menyuk , ”Optimization of the Split-Step Fourier Method in Modeling Optical-Fiber Communications Systems,” J. Lightwave Technol. 21, 61–68 (2003

  7. Vibration frequencies of tapered bars with nonclassical boundary conditions

    NASA Technical Reports Server (NTRS)

    Craver, W. Lionel, Jr.

    1988-01-01

    The goals for this research were revised and clarified. The goals are restated along with an evaluation of the accomplishment of the goal. All of the cases of the truncated-cone beams that were originally proposed to be solved were solved. A summary of these solutions is presented. Some cases of beams with unequal tapers were solved and are discussed.

  8. Efficiency optimization in a FEL with fields` nonadiabatic tapering

    SciTech Connect

    Goncharov, I.A.; Belyavskiy, E.D.; Silivra, A.A.

    1995-12-31

    Amplification of an electromagnetic wave in free electron lasers with a reversed guide field and right-hand polarized wiggler field is investigated both analytically and numerically. An effect of electron bunch trapping by the high frequency electromagnetic field is used for efficiency optimization. On the basis of motion stability criteria a possibility of bunches trapping by FEL parameters nonadiabatic (experimentally realizable) tapering is shown. The stability analysis of electron motion is based on Lyapunov theory for autonomy systems. A particle simulation is carried out for FEL parameters close to the experimental ones (relativistic factor {gamma}=4.75, wiggler field strength B{sub w}= 2.8 kG, guide field strength B{sub o}= -1.4 kG, operation wavelength {lambda}=6.2 mm) for the case of wiggler field tapering. Theoretically predicted rule of wiggler field tapering corresponding to FEL efficiency of 55% is approximated by stepped functions. For the experimentally realizable tapering it is found that FEL efficiency can be over 40%.

  9. Tapered optical fiber sensor for chemical pollutants detection in seawater

    NASA Astrophysics Data System (ADS)

    Irigoyen, Maite; Sánchez-Martin, Jose Antonio; Bernabeu, Eusebio; Zamora, Alba

    2017-04-01

    Three tapered silica optical fibers, uncoated and coated with metallic (Al or Cu) and dielectric layers (TiO2), are employed to determine the presence of oil and Hazardous and Noxious Substances (HNS from now on) in water, by means of the measurement of their spectral transmittance. With our experimental assembly, the presence of oil and HNS spills can be detected employing the three different kinds of tapers, since the complete range of refractive indices of the pollutants (1.329–1.501) is covered with these tapers. The most suitable spectral range to detect the presence of a chemical pollutant in seawater has been identified and a complete spectral characterization of the three types of optical fiber tapers has been carried out. The results obtained show that, in general terms, these devices working together can be employed for the early detection of oil and HNS spills in seawater in a marine industrial environment. These sensors have many advantages, such as its low cost, its simplicity and versatility (with interesting properties as quick response and repeatability), and especially that they can be self-cleaned with seawater in motion.

  10. Opioid Abstinence Reinforcement Delays Heroin Lapse during Buprenorphine Dose Tapering

    ERIC Educational Resources Information Center

    Greenwald, Mark K.

    2008-01-01

    A positive reinforcement contingency increased opioid abstinence during outpatient dose tapering (4, 2, then 0 mg/day during Weeks 1 through 3) in non-treatment-seeking heroin-dependent volunteers who had been maintained on buprenorphine (8 mg/day) during an inpatient research protocol. The control group (n = 12) received $4.00 for completing…

  11. Loss Factor of Tapered Structures for Short Bunches

    SciTech Connect

    Blednykh, A.

    2011-03-28

    Using the electromagnetic simulation code ECHO, we have found a simple phenomenological formula that accurately describes the loss factor for short bunches traversing an axisymmetric tapered collimator. In this paper, we consider tapered collimators with rectangular cross-section and use the GdfidL code to calculate the loss factor dependence on the geometric parameters for short bunches. The results for both axisymmetric and rectangular collimators are discussed. The behaviour of the impedance of tapered structures for very short bunches in the optical regime has been determined in refs. [10,11]. Here, for the loss factors for two particular geometries, we have studied the departure from the optical regime behaviour as bunch length is increased. In both cases, the ratio of the loss factor for the tapered collimator to the loss factor in the optical regime is a function only of the scaling parameter {sigma}L/d{sup 2}. The fact that the bunch length a and the taper length L appear as a product is consistent with the recent scaling derived by Stupakov in ref. [12], since there is only a weak dependence on g. One noteworthy fact that is not a priori expected is that only the larger radius or vertical half-aperture d appears. The reduction factor is independent of b. Moreover, it is striking that the specific form involving the arctan given in Eq. (5) holds for both geometries, with only the coefficient {mu} differing by a factor of {approx}2 for flat vs round. This suggests that there may be a useful phenomenological form for more general geometries which may follow from natural extensions of Eq. (5). This possibility is presently being investigated.

  12. [Use of the anatomical cemented femoral stem SAS I: mid-term results].

    PubMed

    Mikláš, M; Pink, M; Valoušek, T

    2015-01-01

    is an implant made to fit the proximal femur anatomy. Its highly polished surface allows for optimal fitting with the supporting bone and for even distribution of weight bearing. This results in a low rate of THA failure. In accordance with the relevant literature, the acetabular components is considered to be the weakest element in total hip replacement in terms of aseptic loosening and implant failure. At present, the SAS I stem has no Morse Eurocone taper and this is the chief obstacle hindering its more frequent use in endoprosthetics. CONCLUSIONS The results of our study are in agreement with those of other successfully implanted polished cemented femoral components. Key words: anatomical cemented femoral component, surface adjustment of the femoral stem, complications.

  13. Priorities in the Polish health care system.

    PubMed

    Nieszporska, Sylwia

    2017-01-01

    Since 1999, Polish health policy has changed, the quality of services has increased, and also the level of financing, mainly from public benefits. Despite constant growth of indexes reflecting the health status of Polish society, such as life expectancy, quality of life, or decreasing index of deaths at birth, just as in the majority of European countries, in Poland the society is growing older, which implies the necessity to reorganize the system. In this paper, the author has described the most important factors that determine the operation of the health system in Poland, as well as presents the ways it was restructured over the last few years, taking into consideration the structural, legislative, financial, organizational, and quantitative aspects. Also, the latest trends in Polish health policy, which take into account new goals of the system, have been presented within.

  14. Preliminary study of disc hydrodynamic polishing.

    PubMed

    Li, Yan; Lin, Bin; Zhang, XiaoFeng; Liu, PengFei

    2016-10-01

    In this paper, a developed polishing method based on elastic emission machining and Jules Verne-a variation on fluid jet polishing-is presented. This method is named disc hydrodynamic polishing (DHDP). A computational fluid dynamics (CFD)-based model that consists of a CFD model and an erosion model is introduced to predict the surface roughness obtained by DHDP. The performance of DHDP is studied by experiments. The slurry used in the experiments comprises 95% deionized water and 5% cerium oxide particles. Fused-silica glass is chosen as the workpiece. After the experiments, an ultrasmooth surface without cracks is obtained. The simulation results principally coincide with the experimental results. The experimental results show that the actual roughness is slightly less than the prediction and smaller particles are more favorable for obtaining a better surface roughness.

  15. [Convent nursing in Polish hospitals from 1939].

    PubMed

    Halat, M

    2000-01-01

    The author, Sister of Charity and Mother Superior of the Children's Home in Tarnów, describes the attitude of the authorities of the Polish People's Republic towards convent nursing in hospitals. The problem is exemplified by the situation of the Cracow Province of the Order of the Sisters of Charity. Apart from this main theme, Sister Mirosława Hałat says a little about the establishment of the Order and the role it played in Polish hospital care. Before presenting the fundamental problems related to the topic of the article, the author presents numerical data showing the Sisters of Charity's involvement in hospital care between World War I and World War II. This facilitates a comparison of the possibilities of providing hospital care by the Sisters of Charity at a later time. The author also describes the persecutions of the Sister of Charity by the German occupiers. Her main reflections are divided into several parts. The period from 1945 to 1949 covers the time when the Sisters of Charity tried to engage actively in the reconstruction of the ruined Polish hospital system. This involved leaving the former Polish eastern borderland and taking up duties in the so-called Regained Territories. The period from 1950 to 1989 describes the conscious, planned and ideologically directed policies of the authorities of the Polish People's Republic to nullify or at least diminish the role of the Sisters of Charity in Polish hospitals. Quoting numerous accounts and documents, the author tries to recreate the atmosphere of those times. She also writes about the Sisters of Charity's preparation for work in hospitals as well as the possibilities of their education after the war. The article presents the Sisters of Charity's activity under very difficult political conditions and is complemented by a great number of figures, graphs and source documents.

  16. Carbon dioxide laser fabrication of fused-fiber couplers and tapers.

    PubMed

    Dimmick, T E; Kakarantzas, G; Birks, T A; Russell, P S

    1999-11-20

    We report the development of a fiber taper and fused-fiber coupler fabrication rig that uses a scanning, focused, CO(2) laser beam as the heat source. As a result of the pointlike heat source and the versatility associated with scanning, tapers of any transition shape and uniform taper waist can be produced. Tapers with both a linear shape and an exponential transition shape were measured. The taper waist uniformity was measured and shown to be better than +/-1.2%. The rig was also used to make fused-fiber couplers. Couplers with excess loss below -0.1 dB were routinely produced.

  17. Octave spanning supercontinuum in an As₂S₃ taper using ultralow pump pulse energy.

    PubMed

    Hudson, Darren D; Dekker, Stephen A; Mägi, Eric C; Judge, Alexander C; Jackson, Stuart D; Li, Enbang; Sanghera, J S; Shaw, L B; Aggarwal, I D; Eggleton, Benjamin J

    2011-04-01

    An octave spanning spectrum is generated in an As₂S₃ taper via 77 pJ pulses from an ultrafast fiber laser. Using a previously developed tapering method, we construct a 1.3 μm taper that has a zero-dispersion wavelength around 1.4 μm. The low two-photon absorption of sulfide-based chalcogenide fiber allows for higher input powers than previous efforts in selenium-based chalcogenide tapered fibers. This higher power handling capability combined with input pulse chirp compensation allows an octave spanning spectrum to be generated directly from the taper using the unamplified laser output.

  18. Theoretical model of the modulation transfer function for fiber optic taper

    NASA Astrophysics Data System (ADS)

    Wang, Yaoxiang; Tian, Weijian; Bin, XiangLi

    2005-02-01

    Fiber optic taper has been used more and more widely as a relay optical component in the integrated taper assembly image intensified sensors for military and medical imaging application. In this paper, the transmission characteristic of energy in the taper is analyzed, and following the generalized definition of the modulation transfer function for sampled imaging system, a spatial averaged impulse response and a corresponding MTF component that are inherent in the sampling process of taper are deduced, and the mathematical model for evaluating the modulation transfer function of fiber optic taper is built. Finally, the dynamic and static modulation transfer function curves simulated by computer have been exhibited.

  19. Polishing procedure and surface characterization lead tungstate crystal scintillator Road No. 723 and No. 754

    SciTech Connect

    Kellam, M

    1996-05-01

    Step by step procedures are given for polishing the scintillator rods. A Strasbaugh spindle polishing machine was used along with visual inspection and hand polishing. Extensive data is given on pre-polish surface characterization, profilometry, microphotography, and interferometry.

  20. Use of chemical mechanical polishing in micromachining

    DOEpatents

    Nasby, Robert D.; Hetherington, Dale L.; Sniegowski, Jeffry J.; McWhorter, Paul J.; Apblett, Christopher A.

    1998-01-01

    A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface.

  1. Use of chemical mechanical polishing in micromachining

    DOEpatents

    Nasby, R.D.; Hetherington, D.L.; Sniegowski, J.J.; McWhorter, P.J.; Apblett, C.A.

    1998-09-08

    A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface. 4 figs.

  2. Stem Cells

    MedlinePlus

    Stem cells are cells with the potential to develop into many different types of cells in the body. ... the body. There are two main types of stem cells: embryonic stem cells and adult stem cells. Stem ...

  3. Comparison of 3 polishing techniques for 2 all-ceramic materials.

    PubMed

    Saraç, Duygu; Turk, Tamer; Elekdag-Turk, Selma; Saraç, Y Sinaç

    2007-01-01

    The aim of this study was to compare the surface roughness produced by polishing 2 all-ceramic materials after surface conditioning. Air particle abrasion (APA) with 25-microm aluminum oxide, 9.6% hydrofluoric acid (HFA,) and APA + HFA were applied for ceramic surface conditioning. Subsequently, the ceramics were subjected to 3 polishing techniques: polishing kit, polishing paste, and polishing kit + polishing paste. Surface roughness (Ra) was evaluated profilometrically. The highest deltaRa values were obtained with the polishing kit and polishing kit + paste for the APA + HFA groups. No significant differences were observed among the polishing paste groups. Combining a polishing kit and polishing paste produced the smoothest ceramic surfaces.

  4. Modeling and simulation of wheeled polishing method for aspheric surface

    NASA Astrophysics Data System (ADS)

    Zong, Liang; Xie, Bin; Wang, Ansu

    2016-10-01

    This paper describes a new polishing tool for the polishing process of the aspheric lens: the wheeled polishing tool, equipping with an elastic polishing wheel which can automatically adapt to the surface shape of the lens, has been used to get high-precision surface based on the grinding action between the polishing wheel and the workpiece. In this paper, 3D model of polishing wheel structure is established by using the finite element analysis software. Distribution of the contact pressure between the polishing wheel and optical element is analyzed, and the contact pressure distribution function is deduced by using the least square method based on Hertz contact theory. The removal functions are deduced under different loading conditions based on Preston hypothesis. Finally, dwell time function is calculated. The simulation results show that the removal function and dwell time function are suitable for the wheeled polishing system, and thus establish a theoretical foundation for future research.

  5. Refractive index sensors based on the fused tapered special multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Fu, Xing-hu; Xiu, Yan-li; Liu, Qin; Xie, Hai-yang; Yang, Chuan-qing; Zhang, Shun-yang; Fu, Guang-wei; Bi, Wei-hong

    2016-01-01

    In this paper, a novel refractive index (RI) sensor is proposed based on the fused tapered special multi-mode fiber (SMMF). Firstly, a section of SMMF is spliced between two single-mode fibers (SMFs). Then, the SMMF is processed by a fused tapering machine, and a tapered fiber structure is fabricated. Finally, a fused tapered SMMF sensor is obtained for measuring external RI. The RI sensing mechanism of tapered SMMF sensor is analyzed in detail. For different fused tapering lengths, the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0. The RI sensitivity is increased with the increase of fused tapering length. Moreover, it has many advantages, including high sensitivity, compact structure, fast response and wide application range. So it can be used to measure the solution concentration in the fields of biochemistry, health care and food processing.

  6. An in vitro analysis of separation of multi-use ProTaper Universal and ProTaper Next instruments in extracted mandibular molar teeth.

    PubMed

    Ertas, Huseyin; Capar, Ismail Davut

    2015-01-01

    This study investigated the separation incidence of reused ProTaper Universal and ProTaper Next rotary instruments and identified the location of separated fragments. The root canals of extracted human mandibular molars were prepared with 10 assorted sets of ProTaper Universal and ProTaper Next instruments. After each preparation, instrument sets were autoclaved. This arrangement was repeated until an instrument fractured. The number of prepared teeth until fracture occurred was recorded for each instrument set. Teeth in which the instruments fractured were analyzed to determine the separation grade, apical relation, and coronal position. Fracture surfaces of the instruments were examined with scanning electron microscope. ProTaper Universal instruments fractured after application to a mean of 7.3 teeth, and ProTaper Next instruments after application to a mean of 5.7 teeth (p > 0.05). In the ProTaper Universal and ProTaper Next groups, F2 and X1 were the most commonly fractured instruments, respectively. Torsional and cyclic failures were evenly distributed in both the groups. The mean lengths of the fractured fragments of the instruments showed no statistically significant difference. The distance between the tip of the fractured instruments and apical constriction was similar (p > 0.05). However, the mean distance between the root canal orifice and coronal part of the fractured instrument was shorter in the ProTaper Next group (p < 0.05). The life span of ProTaper Universal and ProTaper Next instruments was the same for preparation of mandibular molar teeth. None of the instruments were fractured in the first usage.

  7. Contact pressure distribution of chemical mechanical polishing based on bionic polishing pad

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Xing, Xue-Ling; Lu, Yu-Shan; Zhang, Liao-Yuan

    2010-12-01

    In order to improve the uniformity of the contact pressure distribution of chemical mechanical polishing, based on the Winkler foundation principle of mechanics and phyllotaxis theory of biology, a kind of stannum fixed abrasive pad with bionic surface texture has been designed, and the contact mechanism and ANSYS model have been established. By the calculating and analysis of contact pressure distribution on polishing wafer, the contact pressure distribution and the effects of the geometrical and physical parameters polishing pad on the contact pressure distributions have been obtained. The results show that the horizontal effect of the polishing pad is very small, the uniformity of contact pressure distribution can be improved, and there are the phyllotactic parameters which make the contact pressure distribution more uniformity.

  8. Neurocognitive Dimensions of Lexical Complexity in Polish

    ERIC Educational Resources Information Center

    Szlachta, Zanna; Bozic, Mirjana; Jelowicka, Aleksandra; Marslen-Wilson, William D.

    2012-01-01

    Neuroimaging studies of English suggest that speech comprehension engages two interdependent systems: a bilateral fronto-temporal network responsible for general perceptual and cognitive processing, and a specialised left-lateralised network supporting specifically linguistic processing. Using fMRI we test this hypothesis in Polish, a Slavic…

  9. Polish Complementary Schools in Iceland and England

    ERIC Educational Resources Information Center

    Zielinska, Malgorzata; Kowzan, Piotr; Ragnarsdóttir, Hanna

    2014-01-01

    Since 2004, the opening of labour markets has spurred a considerable number of Poles to emigrate e.g. to Iceland and England. Families with school age children have had the challenge of adapting to foreign environments and school systems. Polish complementary schools have played an important, albeit ambivalent, role in this process. Through focus…

  10. Professional Training of Economists at Polish Universities

    ERIC Educational Resources Information Center

    Ogienko, Olena

    2016-01-01

    Polish experience in professional training of economists at university has been generalized. Structural, content and procedural peculiarities of the training have been defined. It has been proved that key factors for reforming economic education in Poland are globalization, internationalization, integration, technologization and informatization.…

  11. BEGINNING POLISH, VOLUME TWO. YALE LINGUISTIC SERIES.

    ERIC Educational Resources Information Center

    SCHENKER, ALEXANDER M.

    THIS BOOK OF DRILLS IS DESIGNED SPECIFICALLY FOR CLASSROOM INSTRUCTION. ITS PURPOSE IS TO SUPPLEMENT, RATHER THAN CONTINUE, VOLUME I OF "BEGINNING POLISH." IT EXPANDS THE PATTERN DRILLS GIVEN IN THE "SENTENCES" OF VOLUME I AND ADDS TO THE ILLUSTRATIONS PROVIDED IN THE "GRAMMAR." PARALLELING THE STRUCTURE OF VOLUME I, IT HAS 25 LESSONS, DIVIDED IN…

  12. Polish Youth: A Dychotomic World of Values.

    ERIC Educational Resources Information Center

    Bodnar, Artur; Zelichowski, Ryszard

    Research results show a skepticism among Polish youth concerning the possibility of implementing the accepted socialist values in political practice and denote a steady erosion of socialism's image. Youth organizations are many and varied, but it appears that most join because of the opportunity to meet friends, not because of political…

  13. Femtosecond laser polishing of optical materials

    NASA Astrophysics Data System (ADS)

    Taylor, Lauren L.; Qiao, Jun; Qiao, Jie

    2015-10-01

    Technologies including magnetorheological finishing and CNC polishing are commonly used to finish optical elements, but these methods are often expensive, generate waste through the use of fluids or abrasives, and may not be suited for specific freeform substrates due to the size and shape of finishing tools. Pulsed laser polishing has been demonstrated as a technique capable of achieving nanoscale roughness while offering waste-free fabrication, material-specific processing through direct tuning of laser radiation, and access to freeform shapes using refined beam delivery and focusing techniques. Nanosecond and microsecond pulse duration radiation has been used to perform successful melting-based polishing of a variety of different materials, but this approach leads to extensive heat accumulation resulting in subsurface damage. We have experimentally investigated the ability of femtosecond laser radiation to ablate silicon carbide and silicon. By substituting ultrafast laser radiation, polishing can be performed by direct evaporation of unwanted surface asperities with minimal heating and melting, potentially offering damage-free finishing of materials. Under unoptimized laser processing conditions, thermal effects can occur leading to material oxidation. To investigate these thermal effects, simulation of the heat accumulation mechanism in ultrafast laser ablation was performed. Simulations have been extended to investigate the optimum scanning speed and pulse energy required for processing various substrates. Modeling methodologies and simulation results will be presented.

  14. Knowledge Mobilisation in the Polish Education System

    ERIC Educational Resources Information Center

    Fazlagic, Jan; Erkol, Arif

    2015-01-01

    Poland has made substantial progress in improving the quality of its education system in recent years. This paper aims to describe the situation of the Polish education system from a knowledge management perspective and, to some extent, through innovation policies in education. The many challenges, this paper argues, can be tackled only through…

  15. Outgassing Properties of Chemically Polished Titanium Materials

    NASA Astrophysics Data System (ADS)

    Kurisu, Hiroki; Kimoto, Gou; Fujii, Hiroaki; Tanaka, Kazuhiko; Yamamoto, Setsuo; Matsuura, Mitsuru; Ishizawa, Katsunobu; Nomura, Takeru; Murashige, Nobuyuki

    We developed a chemical polishing (CP) for titanium materials applicable to ultrahigh vacuum (UHV) and extremely high vacuum (XHV) systems. The surface roughness, Ra, of the chemically polished titanium is obtained to be 25 nm by the atomic force microscopy measurement. This value is smaller than those of the base metal (BM) and the buff-polished (BP) samples. The thickness of the surface oxide layer of CP sample is estimated to be 7 nm by the cross section of transmission electron micrograph. Amount of desorption gas of CP sample obtained by the thermal desorption measurement is smaller than those of BM and BP sample, and is the same as that of the mechanochemically polished (MCP) sample. The outgassing rate of CP sample after baking at 150°C×20 h is obtained to be 7×10-13 Pa•m•s-1. This value is lower than that of standard vacuum materials by two orders of magnitude after the ordinary baking.

  16. Freeform grinding and polishing with PROSurf

    NASA Astrophysics Data System (ADS)

    Wolfs, Franciscus; Fess, Edward; DeFisher, Scott; Torres, Josh; Ross, James

    2015-10-01

    Recently, the desire to use freeform optics has been increasing, including shapes such as torics and anamorphic aspheres. Freeform optics can be used to expand capabilities of optical systems. They can compensate for limitations in rotationally symmetric optics. These same traits that give freeform optics the ability to improve optical systems also makes them more challenging to manufacture. This holds true for grinding, polishing, and metrology. As freeform optics become more prevalent in the industry, tolerances will become more stringent, requiring deterministic manufacturing processes. To generate freeforms, it is crucial to have control over all aspects of the process. Controlling the surface definition is important for achieving a better surface finish during processing. Metrology will be required to adjust tool paths at various stages in manufacturing. During grinding, metrology will be used to adjust tool positions relative to the nominal tool path to compensate for repeatable machine and tooling error. For polishing, metrology will be used to deterministically adjust dwell relative to the amount of the error in different surface locations, allowing for convergence towards the desired surface at a uniform rate. OptiPro has developed PROSurf, a CAM software package for creating freeform tool paths and applying metrology-based corrections. The software can be used for both grinding and polishing freeform optics. The software has flexibility to allow for different methods of modelling the surface: mathematical equations, solid models, and point clouds. The software is designed to make it easier to manufacture and polish complex freeform optics.

  17. [The life of Polish students at the Polish School of Medicine at the University of Edinburgh].

    PubMed

    Gebertt, S

    1994-01-01

    The article has been written by a former student of the Polish School of Medicine at the University of Edinburgh, a member of the Polish Forces in Britain. The reminiscences concentrate on day to day life of others, like himself, seconded from the Forces to continue their medical studies. Statistical data concerning the activities of Polish School of Medicine are presented and analysed. Detailed mention is made of various routes by which Polish students reached Great Britain from the time of defeat and partition of Poland between Germany and Soviet Union. The various phases of relationship and attitudes between Polish Armed Forces and the body of students are described and illustrated by extracts from personal memoirs. The number of other topics is presented and discussed: The difficulties and problems encountered in living and studying amongst people, who although sympathetic, but whose language, culture and customs were completely foreign to the Poles. The ways in which individuals and groups of students tried and in many instances managed to overcome these obstacles, forging links with their Scottish colleagues and population at large. The participation in various joint activities like Settlement Day, work in agricultural camps, sports, Scottish students Unions and Representative Councils etc. are described. "Inner life" of Polish students concentrated in "Bursa" (an equivalent of University Residence) is presented in a light-hearted way. Large detachments of a foreign army, living, amongst albeit friendly population, are bound to cause, sometimes serious, friction. Very much in relation to this problem the role of Polish students as ambassadors of Poland and Polish Causes are presented and their value assessed.

  18. Design of multiple-ply laminated composite tapered beams

    NASA Technical Reports Server (NTRS)

    Rodriguez, P.

    1993-01-01

    A study of a special case of symmetric laminated composite cantilever beams is presented. The approach models beams that are tapered both in depth and width and investigates the effect of the ply layup angle and the ply taper on bending and interlaminar shearing stresses. For the determination of stresses and deflections, the beam stiffness matrices are expressed as linear functions of the beam length. Using classical lamination theory (CLT) the stiffness matrices are determined and assembled at strategic locations along the length of the beam. They are then inverted and necessary stiffness parameters are obtained numerically and extracted for determination of design information at each location chosen. Several ply layup configurations are investigated, and design considerations are presented based on the findings. Finally, recommendations for the design of these beams are presented, and a means for anticipating the location of highest stresses is offered.

  19. Piezoelectric energy harvester having planform-tapered interdigitated beams

    DOEpatents

    Kellogg, Rick A.; Sumali, Hartono

    2011-05-24

    Embodiments of energy harvesters have a plurality of piezoelectric planform-tapered, interdigitated cantilevered beams anchored to a common frame. The plurality of beams can be arranged as two or more sets of beams with each set sharing a common sense mass affixed to their free ends. Each set thus defined being capable of motion independent of any other set of beams. Each beam can comprise a unimorph or bimorph piezoelectric configuration bonded to a conductive or non-conductive supporting layer and provided with electrical contacts to the active piezoelectric elements for collecting strain induced charge (i.e. energy). The beams are planform tapered along the entirety or a portion of their length thereby increasing the effective stress level and power output of each piezoelectric element, and are interdigitated by sets to increase the power output per unit volume of a harvester thus produced.

  20. Refractive index sensor based on tapered multicore fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Chuanbiao; Ning, Tigang; Li, Jing; Pei, Li; Li, Chao; Lin, Heng

    2017-01-01

    A novel refractive index (RI) sensor based on middle-tapered multicore fiber (TMCF) is proposed and experimentally demonstrated. The sensing structure consists of two singlemode fibers (SMF) and simply spliced a section tapered four-core fiber between them. The light injected from the SMF into the multicore fiber (MCF) will excite multiple cladding mode, and interference between these modes can be affected by the surrounding refractive index (SRI), which also dictates the wavelength shift of the transmission spectrum. Our experimental investigations achieved a sensitivity around 171.2 nm/RIU for a refractive index range from 1.3448 to 1.3774. All sensors fabricated in this paper show good linearity in terms of the spectral wavelength shift versus changes in RI.

  1. Design of MR brake featuring tapered inner magnetic core

    NASA Astrophysics Data System (ADS)

    Sohn, Jung Woo; Oh, Jong-Soek; Choi, Seung-Bok

    2015-04-01

    In this work, a new type of MR brake featuring tapered inner magnetic core is proposed and its braking performance is numerically evaluated. In order to achieve high braking torque with restricted size and weight of MR brake system, tapered inner magnetic core is designed and expands the area that the magnetic flux is passing by MR fluid-filled gap. The mathematical braking torque model of the proposed MR brake is derived based on the field-dependent Bingham rheological model of MR fluid. Finite element analysis is carried out to identify electromagnetic characteristics of the conventional and the proposed MR brake configuration. To demonstrate the superiority of the proposed MR brake, the braking torque of the proposed MR brake is numerically evaluated and compared with that of conventional MR brake model.

  2. Free-electron lasers with very slow wiggler taper

    NASA Astrophysics Data System (ADS)

    Bosley, D. L.; Kevorkian, J.

    1990-09-01

    A highly accurate, explicit asymptotic solution of the electron energy and phase is found for a class of free-electron lasers with very long wavelength beams, very low electron energies, and very slow taper of the wiggler field relative to the wiggler period. Dimensionless variables are defined and normalized, and three small parameters which characterize the operation of the FEL are identified. Because of the explicit nature of the solution, our results may be directly used to calculate features such as the escape distance of the electron from the potential well and the effects of the various physical parameters. One important advantage of the very slow wiggler taper is the increased efficiency of the energy transfer from the electron beam to the signal field due to increased bucket width. Numerical calculations are performed to verify all results.

  3. Free-electron lasers with very slow wiggler taper

    NASA Astrophysics Data System (ADS)

    Bosley, D. L.; Kevorkian, J.

    1991-04-01

    A highly accurate, explicit asymptotic solution of the electron energy and phase is found for a class of free-electron lasers (FELs) with very long wavelength beams, very low electron energies, and very slow taper of the wiggler field relative to the wiggler period. Dimensionless variables are defined and normalized, and three small parameters which characterize the operation of the FEL are identified. Due to the explicit asymptotic nature of the solution, the results may be directly used to calculate features such as the escape distance of the electron from the potential well and the effects of the various physical parameters. One important advantage of the very slow wiggler taper is the increased efficiency of the energy transfer from the electron beam to the signal field due to increased bucket width. Numerical calculations are performed to verify all results.

  4. Magnetic field tunability of square tapered no-core fibers

    NASA Astrophysics Data System (ADS)

    Miao, Yinping; Wu, Jixuan; Lin, Wei; Zhang, Kailiang; Song, Binbin; Zhang, Hao; Liu, Bo

    2014-05-01

    A magnetic-field-tuned photonics device based on magnetic fluid (MF) and a square tapered no-core fiber (NCF) sandwiched between two single-mode fibers (SMFs) has been proposed. The enhanced evanescent field effect in the NCF is achieved by tapering the square NCF utilizing a fusion splicer. The spectral dependence of the proposed device on the applied magnetic-field intensity has been investigated. The results indicate that a maximal sensitivity of -18.7pm/Oe is obtained for a magnetic field strength ranging from 25Oe to 450Oe. The proposed tunable device has several advantages, including low cost, ease of fabrication, compact structure, and high sensitivity.

  5. A microsphere-taper cascading structured microfiber for temperature sensing

    NASA Astrophysics Data System (ADS)

    Xian, Pei; Feng, Guoying; Zhou, Shouhuan

    2016-04-01

    We propose and demonstrate a technique for cascading a microsphere and an abrupt taper together in a standard singlemode fiber. The proposed microsphere-taper cascading structured microfiber (MTCSM) was fabricated by fusion splicing and electric-arc discharge. Exposing the MTCSM segment to increasing temperatures results in a significant shift of the transmission notches towards longer wavelengths with a slope of approximately 17.24 pm/°C∇ from 35°C to 170°C, and the linearity is 99.8%. Due to its compact size and all-fiber configuration, the proposed sensor has advantages of good mechanical strength, simplicity and low-cost fabrication, such new device would find potential applications in communication and sensing fields.

  6. Development of high-power gyrotrons with gradually tapered cavity

    SciTech Connect

    Lei Chaojun; Yu Sheng; Niu Xinjian; Liu Yinghui; Li Hongfu; Li Xiang

    2012-12-15

    In high power gyrotrons, the parasitic modes coupled with the operating mode cannot be avoided in the beam-wave interaction. These parasitic modes will decrease the efficiency of the gyrotrons. The purity of the operating mode affected by different tapers should be carefully studied. The steady-state self-consistent nonlinear theory for gyrotron with gradually tapered cavity is developed in this paper. A steady-state calculation code including 'cold cavity' and 'hot cavity' is designed. By comparison, a time-domain model analysis of gyrotron operation is also studied by particle-in-cell (PIC). It is found that the tapers of gyrotron have different influences on the modes coupling between the operating mode and the parasitic modes. During the study, an example of 94 GHz gyrotron with pure operating mode TE{sub 03} has been designed. The purity of the operating mode in the optimized cavity is up to -77 dB, and in output waveguide of the cavity is up to -76 dB. At the same time, the beam-wave interaction in the designed cavity has been simulated, too. An output power of 120 kW, corresponding to 41.6% efficiency and an oscillation frequency of 94.099 GHz have been achieved with a 50 kV, 6 A helical electron beam at a guiding magnetic field of 3.5485 T. The results show that the power in spurious modes of the optimized cavity may be kept far below than that of the traditional tapered cavity.

  7. Gas insulated transmission line having tapered particle trapping ring

    DOEpatents

    Cookson, Alan H.

    1982-01-01

    A gas-insulated transmission line includes an outer sheath, an inner conductor, insulating supports and an insulating gas. A particle-trapping ring is secured to each insulating support, and it is comprised of a central portion and two tapered end portions. The ends of the particle trapping ring have a smaller diameter than the central portion of the ring, so as to enable the use of the particle trapping ring in a curved transmission line.

  8. Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    The future X-ray observatory missions, such as International X-ray Observatory, require grazing incidence replicated optics of extremely large collecting area (3 m2) in combination with angular resolution of less than 5 arcsec half-power diameter. The resolution of a mirror shell depends ultimately on the quality of the cylindrical mandrels from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation studies have been performed to optimize the operational parameters as well as the polishing lap configuration. Furthermore, depending upon the surface error profile, a model for localized polishing based on dwell time approach is developed. Using the inputs from the mathematical model, a mandrel, having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. We report our first experimental results and discuss plans for further improvements in the polishing process.

  9. Between Polish Positivism and American Capitalism: The Educational Agents' Experiment in the Polish-American Community, 1889-1914

    ERIC Educational Resources Information Center

    Jaroszynska-Kirchmann, Anna D.

    2008-01-01

    "Ameryka-Echo" was one of the most popular Polish-language weeklies, published in the United States between 1889 and 1972. Its founder and owner, Antoni A. Paryski, consciously sought to transplant ideas of Polish Positivism to the Polish-American immigrant communities in the United States. Reading was a central concept of…

  10. Evaluation of the polished surface characteristic of cobalt-chrome castings subsequent to various finishing and polishing techniques.

    PubMed

    Ponnanna, A A; Joshi, S M; Bhat, S; Shetty, P

    2001-01-01

    Finishing and Polishing constitutes an essential requisite after the fabrication of removable partial dentures. Improper finishing and polishing of cast framework will adversely affect the quality of functional units of partial dentures due to reduced dimensions. In this study the polished surface characteristic and loss of weight of the casting were evaluated and compared following different finishing and polishing techniques. A total number of thirty test specimens were cast and each surface finishing and polishing technique was carried out with a high speed polishing motor and an electropolishing unit under standardised conditions. Surface roughness was evaluated by means of a surface roughness analyzing instrument, Perthometer. The loss of weight due to the metal lost was observed on a sensitive electronic balance. The results of polishing technique employed with G3 group revealed better surface characteristic. It may be understood that sandblasting causes initial roughness and the sequence of coarse cylindrical abrasive, Black hard rubber polisher (coarse grit-Dentauram), Grey hard rubber polisher (Med-grit-Dentauram), Green hard rubber polisher (Fine-grit-Dentauram), Grey flexible rubber polisher (Fine grit-Renfert), felt buff with pumice slurry and felt buff with green polishing compound (Degussa) produced improved surface in this case. The loss of weight due to metal lost show concern with technique groups G4, G5, G6. It can be avoided by judicious sandblasting and application of proper grit of abrasive agents.

  11. Schottky photodetector with tapered thin metal strip on silicon waveguide

    NASA Astrophysics Data System (ADS)

    Guo, Jingshu; Wu, Zhiwei; Li, Yuan; Zhao, Yanli

    2016-01-01

    We propose a Schottky photodetector with tapered thin metal strip on SOI platform. Schottky photodetector can detect photons below the semiconductor bandgap energy by exploiting the internal photoemission. In the internal photoemission process, the hot carriers generate in the tapered thin metal strip where light absorption occurs, and part of these carriers can be emitted over the Schottky barrier and collected as photocurrent. The small thickness of the tapered metal strip contributes to a high internal quantum efficiency of 11.25%. This metal-semiconductor structure acts as a photonics-plasmonics mode convertor. According to 3D-FDTD simulation, about 95.8% of the incident optical power can be absorbed in the absorption area within 4.5μm at wavelength of 1550 nm. The responsivity is estimated to be 0.135A/W at 1550 nm. This compact design with a low dark current has a minimum detectable power of -23.15 dβm. We argue that this design can promote the progress of all-Si photo-detection in near-infrared communication band.

  12. Magnetic field tunability of optical microfiber taper integrated with ferrofluid.

    PubMed

    Miao, Yinping; Wu, Jixuan; Lin, Wei; Zhang, Kailiang; Yuan, Yujie; Song, Binbin; Zhang, Hao; Liu, Bo; Yao, Jianquan

    2013-12-02

    Optical microfiber taper has unique propagation properties, which provides versatile waveguide structure to design the tunable photonic devices. In this paper, the S-tapered microfiber is fabricated by using simple fusion spicing. The spectral characteristics of microfiber taper integrated with ferrofluid under different magnetic-field intensities have been theoretically analyzed and experimentally demonstrated. The spectrum are both found to become highly magnetic-field-dependent. The results indicate the transmission and wavelength of the dips are adjustable by changing magnetic field intensity. The response of this device to the magnetic field intensity exhibits a Langvin function. Moreover, there is a linear relationship between the transmission loss and magnetic field intensity for a magnetic field intensity range of 25 to 200Oe, and the sensitivities as high as 0.13056dB/Oe and 0.056nm/Oe have been achieved, respectively. This suggests a potential application of this device as a tunable all-in-fiber photonic device, such as magneto-optic modulator, filter, and sensing element.

  13. A woman's experience of tapering from buprenorphine during pregnancy

    PubMed Central

    Welle-Strand, Gabrielle Katrine; Kvamme, Odd; Andreassen, Andreas; Ravndal, Edle

    2014-01-01

    Although opioid maintenance treatment (OMT) is the treatment of choice for pregnant opioid-dependent patients, some professionals argue that tapering the medication dose will reduce the severity of neonatal abstinence syndrome (NAS). This case description is based on the patient's detailed blog, and medical records from her general practitioner and the hospital. The patient is an employed, 32-year-old drug-abstinent woman in OMT. Her taper from 24 mg of buprenorphine started at 14 weeks’ gestation and is slow, with withdrawal symptoms increasing gradually. In pregnancy week 31, she is off buprenorphine but she has severe withdrawal symptoms. She chose to go back on 4 mg of buprenorphine. The patient's son was born in pregnancy week 38+3, weighs 2950 g and does not require pharmacological treatment for NAS. The fetus most probably did experience fetal stress during the patient's tapering. It was the right decision by the patient to go back on buprenorphine. PMID:25540212

  14. Model-based optimization of tapered free-electron lasers

    NASA Astrophysics Data System (ADS)

    Mak, Alan; Curbis, Francesca; Werin, Sverker

    2015-04-01

    The energy extraction efficiency is a figure of merit for a free-electron laser (FEL). It can be enhanced by the technique of undulator tapering, which enables the sustained growth of radiation power beyond the initial saturation point. In the development of a single-pass x-ray FEL, it is important to exploit the full potential of this technique and optimize the taper profile aw(z ). Our approach to the optimization is based on the theoretical model by Kroll, Morton, and Rosenbluth, whereby the taper profile aw(z ) is not a predetermined function (such as linear or exponential) but is determined by the physics of a resonant particle. For further enhancement of the energy extraction efficiency, we propose a modification to the model, which involves manipulations of the resonant particle's phase. Using the numerical simulation code GENESIS, we apply our model-based optimization methods to a case of the future FEL at the MAX IV Laboratory (Lund, Sweden), as well as a case of the LCLS-II facility (Stanford, USA).

  15. Reconfigurable tapered coaxial slot antenna for hepatic microwave ablation.

    PubMed

    Malhotra, Neeru; Marwaha, Anupma; Kumar, Ajay

    2016-01-01

    Microwave ablation is rapidly being rediscovered and developed for treating many cancers of liver, lung, kidney and bone, as well as arrhythmias and other medical conditions. The microwaves ablate tissue by heating it to cytotoxic temperatures. The microwave antenna design suffers the challenges of effective coupling and penetration into body tissues, uncontrolled power deposition due to applicator construction limitations affecting uniform heating of target region, and narrowband operation leading to mismatch for many patients and detrimental heating. To meet out the requirements of wideband operation and localized lesion reconfigurable linearly tapered slot interstitial wideband antenna has been proposed for working in the 1.38 GHz to 4.31 GHz frequency band. The performance of the antenna is evaluated by using FEM-based HFSS software. The slot height and taper height are reconfigured for parametric analysis achieving maximum impedance matching and spherical ablation zone without requiring any additional adjustable structures. The tapering of the slot in coaxial antenna generates current distribution at the edges of the slot for maximizing specific absorption rate.

  16. Comparative evaluation of apically extruded debris with V-Taper, ProTaper Next, and the Self-adjusting File systems

    PubMed Central

    Vyavahare, Nishant K.; Raghavendra, Srinidhi Surya; Desai, Niranjan N.

    2016-01-01

    Background: Complete cleaning of the root canal is the goal for ensuring success in endodontics. Removal of debris plays an important role in achieving this goal. In spite of advancements in instrument design, apical extrusion of debris remains a source of inflammation in the periradicular region. Aim: To comparatively evaluate the amount of apically extruded debris with V-Taper, ProTaper Next, and the self-adjusting File (SAF) system. Materials and Methods: Sixty-four extracted human mandibular teeth with straight root canals were taken. Access openings were done and working length determined. The samples were randomly divided into three groups: Group I - V-Taper files (n = 20), Group II - ProTaper Next (n = 20), Group III - SAF (n = 20). Biomechanical preparation was completed and the debris collected in vials to be quantitatively determined. The data obtained was statistically analyzed using ANOVA and post hoc Tukey's test. Results: All the specimens showed apical debris extrusion. SAF showed significantly less debris extrusion compared to V-Taper and ProTaper Next (P < 0.001). Among Groups I and II, ProTaper Next showed lesser debris extrusion as compared to V-Taper, but it was not significant (P = 0.124). Conclusion: The SAF showed least amount of apical debris extrusion when compared to newer rotary endodontic instruments. This indicates that the incidence of inter-treatment flare-ups due to debris extrusion would be less with the SAF. PMID:27217636

  17. Tooth polishing: Relevance in present day periodontal practice

    PubMed Central

    Madan, Charu; Bains, Rhythm; Bains, Vivek K.

    2009-01-01

    Time has seen the emergence of more efficient and effective devices like jet abrasives. However, the role of rubber cups with prophy angles cannot be overlooked as they are still being widely used and provide an economical alternative. Owing to several shortcomings associated with the air polishing device using sodium bicarbonate (NaHCO3), trends are shifting towards the usage of low abrasive powders. Recent demonstration of Glycine Powder Air Polishing (GPAP) in removing subgingival biofilm results in less gingival erosion than hand instrumentation or NaHCO3 air-polishing. Despite the emergence of latest advances in polishing, data suggesting selective polishing of teeth is compelling. PMID:20376245

  18. Silica based polishing of {100} and {111} single crystal diamond

    PubMed Central

    Thomas, Evan L H; Mandal, Soumen; Brousseau, Emmanuel B; Williams, Oliver A

    2014-01-01

    Diamond is one of the hardest and most difficult to polish materials. In this paper, the polishing of {111} and {100} single crystal diamond surfaces by standard chemical mechanical polishing, as used in the silicon industry, is demonstrated. A Logitech Tribo Chemical Mechanical Polishing system with Logitech SF1 Syton and a polyurethane/polyester polishing pad was used. A reduction in roughness from 0.92 to 0.23 nm root mean square and 0.31 to 0.09 nm rms for {100} and {111} samples respectively was observed. PMID:27877689

  19. Polishing Material Removal Correlation on PMMA - FEM Simulation

    NASA Astrophysics Data System (ADS)

    Almeida, R.; Börret, R.; Rimkus, W.; Harrison, D. K.; DeSilva, A. K. M.

    2016-02-01

    The complexity of polishing is very high and experience in this field is required to achieve reproducible deterministic results concerning shape accuracy. The goal of this work is to predict the material removal of the polishing process on PMMA (Polymethylmethacrylate) using an industrial robot polisher. In order to predict the material removal, a FEM Model was created representing the polishing process. This model will help to predict the material removal when polishing parameters are changed. Experiments were carried out and compared to the results obtained from the different parameters tested in the simulation.

  20. In-situ Tapering of Chalcogenide Fiber for Mid-infrared Supercontinuum Generation

    PubMed Central

    Rudy, Charles W.; Marandi, Alireza; Vodopyanov, Konstantin L.; Byer, Robert L.

    2013-01-01

    Supercontinuum generation (SCG) in a tapered chalcogenide fiber is desirable for broadening mid-infrared (or mid-IR, roughly the 2-20 μm wavelength range) frequency combs1, 2 for applications such as molecular fingerprinting, 3 trace gas detection, 4 laser-driven particle acceleration, 5 and x-ray production via high harmonic generation. 6 Achieving efficient SCG in a tapered optical fiber requires precise control of the group velocity dispersion (GVD) and the temporal properties of the optical pulses at the beginning of the fiber, 7 which depend strongly on the geometry of the taper. 8 Due to variations in the tapering setup and procedure for successive SCG experiments-such as fiber length, tapering environment temperature, or power coupled into the fiber, in-situ spectral monitoring of the SCG is necessary to optimize the output spectrum for a single experiment. In-situ fiber tapering for SCG consists of coupling the pump source through the fiber to be tapered to a spectral measurement device. The fiber is then tapered while the spectral measurement signal is observed in real-time. When the signal reaches its peak, the tapering is stopped. The in-situ tapering procedure allows for generation of a stable, octave-spanning, mid-IR frequency comb from the sub harmonic of a commercially available near-IR frequency comb. 9 This method lowers cost due to the reduction in time and materials required to fabricate an optimal taper with a waist length of only 2 mm. The in-situ tapering technique can be extended to optimizing microstructured optical fiber (MOF) for SCG10 or tuning of the passband of MOFs, 11 optimizing tapered fiber pairs for fused fiber couplers12 and wavelength division multiplexers (WDMs), 13 or modifying dispersion compensation for compression or stretching of optical pulses.14-16 PMID:23748947

  1. Finishing of advanced ceramic balls for bearing applications by magnetic float polishing (MFP) involving fine polishing followed by chemo-mechanical polishing (CMP)

    NASA Astrophysics Data System (ADS)

    Jiang, Ming

    Scope and method of study. This investigation deals with the development of science and technology of finishing advanced ceramics, such as Sisb3Nsb4 balls for bearing applications by magnetic float polishing (MFP) technology. Experimental design and analysis based on Taguchi method are applied to determine the optimum processing conditions for improving the surface quality in fine mechanical polishing by MFP technology. Polishing with various abrasives, different operating conditions, and polishing environments for Sisb3Nsb4 bearing balls have been investigated. Fundamental mechanisms of chemo-mechanical polishing (CMP) have been studied based on thermodynamic and kinetic analysis. Findings and conclusions. The methodology, involved mechanical polishing followed by CMP for finishing of Sisb3Nsb4 balls from the as-received condition to a sphericity of 0.15 mum and surface finish of Ra 4 nm by MFP technology has been developed. It takes about 20 hours to finish a batch of balls compared to a range of several weeks to several months by conventional grinding and polishing technology. High material removal rates (1 mum/min) with minimal subsurface damage are possible by mechanical polishing with harder abrasives such as Bsb4C or SiC in MFP. CeOsb2 and ZrOsb2 are found to be most effective abrasives followed by Fesb2Osb3 and Crsb2Osb3 for CMP of Sisb3Nsb4. CMP is found to be particularly effective in a water-based environment. There are similarities between polishing glass and polishing Sisb3Nsb4 workmaterial including the role of water, polishing environment, and chemical effectiveness and mechanical hardness of abrasive for effective polishing.

  2. Vibration transfer in the ball-stem contact interface of artificial hips.

    PubMed

    Hothan, Arne; Lewerenz, Kathrin; Weiss, Cornelius; Hoffmann, Norbert; Morlock, Michael; Huber, Gerd

    2013-10-01

    Audible squeaking has put the reputation of ceramic bearings for total hip replacements into question. Inter-articular friction induces vibrations in the ceramic head which are transferred through the head-taper interface to the femoral stem. If excited to sufficient amplitudes, squeaking can be emitted by the stem. Hence, the damping and amplification properties of this interface have a crucial influence on stem vibrations. The aim of this study was to determine the vibration transfer behavior between the head and the taper of a femoral stem and its dependence on the assembly force, in order to assess its influence on the development of audible squeaking. A ceramic head was assembled on a titanium femoral stem taper with high and low forces. Frequency response functions characterizing the head-stem interface were determined experimentally. The interface demonstrated negligible influence on vibration transfer in the squeaking frequency range (1-5 kHz). However its damping effect in lower and higher frequency ranges was significant and some areas of amplification were also found. Although squeaking vibration was not influenced by the particular interface studied, the method established can be utilized to trace taper designs with dynamic properties that decrease the susceptibility to squeaking.

  3. Computationally generated velocity taper for efficiency enhancement in a coupled-cavity traveling-wave tube

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey D.

    1989-01-01

    A computational routine has been created to generate velocity tapers for efficiency enhancement in coupled-cavity TWTs. Programmed into the NASA multidimensional large-signal coupled-cavity TWT computer code, the routine generates the gradually decreasing cavity periods required to maintain a prescribed relationship between the circuit phase velocity and the electron-bunch velocity. Computational results for several computer-generated tapers are compared to those for an existing coupled-cavity TWT with a three-step taper. Guidelines are developed for prescribing the bunch-phase profile to produce a taper for efficiency. The resulting taper provides a calculated RF efficiency 45 percent higher than the step taper at center frequency and at least 37 percent higher over the bandwidth.

  4. Key findings from studies of methotrexate tapering and withdrawal in rheumatoid arthritis.

    PubMed

    Subesinghe, Sujith; Scott, Ian C

    2015-01-01

    Methotrexate is the dominant initial drug in the management of rheumatoid arthritis (RA). Despite its widespread use, methotrexate is associated with a number of adverse effects. Tapering its dose to the minimal amount required to maintain RA remission is, therefore, an important clinical goal. While the complete withdrawal of disease-modifying anti-rheumatic drugs is associated with a definite risk of a disease flare, it is unclear as to what the risk is specific to methotrexate withdrawal and whether this can be minimized by gradual dose reduction (termed 'tapering'). This review examines studies of methotrexate tapering and withdrawal on RA outcomes. It covers three scenarios: tapering/withdrawing methotrexate monotherapy; tapering/withdrawing methotrexate as part of a 'step-down' combination disease-modifying anti-rheumatic drug regimen; and tapering/withdrawing methotrexate when it is being co-prescribed with biologic agents.

  5. Compact and efficient large cross-section SOI rib waveguide taper optimized by a genetic algorithm

    NASA Astrophysics Data System (ADS)

    Liu, Yujin; Wang, Xi; Dong, Ying; Wang, Xiaohao

    2016-01-01

    A genetic algorithm is applied to optimize a taper between a large cross-section silicon-on-insulator (SOI) rib waveguide and a single-mode fiber to achieve an ultra-compact and highly efficient coupling structure. The coupling efficiency is taken as the objective function of the genetic algorithm in the taper optimization process. To apply the optimization algorithm, the taper is segmented into several sections. Three encoding forms and a two-step optimization strategy are adopted in the optimization process, resulting in a 10μm long taper with a coupling efficiency of 93.30% in quasi-TE mode at 1550nm. The characteristics of the optimized taper including the field profile, spectrum and fabrication tolerances in both horizontal and vertical directions are investigated via a three dimensional eigenmode expansion (EME) method, indicating that the optimized taper is compatible with the prevailing integrated circuit (IC) processing technology.

  6. Condensate polishers add operating reliability and flexibility

    SciTech Connect

    Layman, C.M.; Bennett, L.L.

    2008-08-15

    Many of today's advanced steam generators favour either an all-volatile treatment or oxygenated treatment chemistry programme, both of which require strict maintenance of an ultra-pure boiler fedwater ro condensate system. Those requirements are many times at odds with the lower-quality water sources, such as greywater, available for plant makeup and cooling water. Adding a condensate polisher can be a simple, cost-effective solution. 4 figs.

  7. ROUGHNESS ANALYSIS OF VARIOUSLY POLISHED NIOBIUM SURFACES

    SciTech Connect

    Ribeill, G.; Reece, C.

    2008-01-01

    Niobium superconducting radio frequency (SRF) cavities have gained widespread use in accelerator systems. It has been shown that surface roughness is a determining factor in the cavities’ effi ciency and maximum accelerating potential achievable through this technology. Irregularities in the surface can lead to spot heating, undesirable local electrical fi eld enhancement and electron multipacting. Surface quality is typically ensured through the use of acid etching in a Buffered Chemical Polish (BCP) bath and electropolishing (EP). In this study, the effects of these techniques on surface morphology have been investigated in depth. The surface of niobium samples polished using different combinations of these techniques has been characterized through atomic force microscopy (AFM) and stylus profi lometry across a range of length scales. The surface morphology was analyzed using spectral techniques to determine roughness and characteristic dimensions. Experimentation has shown that this method is a valuable tool that provides quantitative information about surface roughness at different length scales. It has demonstrated that light BCP pretreatment and lower electrolyte temperature favors a smoother electropolish. These results will allow for the design of a superior polishing process for niobium SRF cavities and therefore increased accelerator operating effi ciency and power.

  8. Duplication of holograms by using fingernail polish

    NASA Astrophysics Data System (ADS)

    Toxqui-López, S.; Olivares-Pérez, A.; Fuentes-Tapia, I.; Quintero-Romo, A.

    2007-08-01

    In this manuscript, we report the results of a research effort in finding an innovative recorder material which utilized fingernail polish (Super Oro One Coat®) information by means of the control of temperature as a parameter induced by hand rubbing. Analogical and computer holograms were replicated, resulting in a high quality behavior of fingernail polish through coating the polish with an average thickness of 10-15 μm, which contains some components of polyester resin with nitrocellulose. Through this material we obtained a high absolute diffraction efficiency, which was approximately equal to 90%, with gratings of 100 lines/mm. For a copy of conventional holograms at high frequencies (holographic ranges) the diffraction efficiency parameter is in the neighborhood of 22% at first order or more, depending on diffraction efficiency of the pattern of the hologram. The hologram is elaborated in the absence of any development of any process and does not need to have carefully controlled environmental conditions. Following this process, the hologram is obtained at standard atmospheric conditions of pressure and temperature. Another advantage is that it is possible to obtain a hologram at a lower cost; furthermore, the property of applicability to any substrate that it has is remarkable.

  9. Multiwavelength digital holography for polishing tool shape measurement

    NASA Astrophysics Data System (ADS)

    Lédl, Vít.; Psota, Pavel; Václavík, Jan; Doleček, Roman; Vojtíšek, Petr

    2013-09-01

    Classical mechano-chemical polishing is still a valuable technique, which gives unbeatable results for some types of optical surfaces. For example, optics for high power lasers requires minimized subsurface damage, very high cosmetic quality, and low mid spatial frequency error. One can hardly achieve this with use of subaperture polishing. The shape of the polishing tool plays a crucial role in achieving the required form of the optical surface. Often the shape of the polishing tool or pad is not known precisely enough during the manufacturing process. The tool shape is usually premachined and later is changed during the polishing procedure. An experienced worker could estimate the shape of the tool indirectly from the shape of the polished element, and that is why he can achieve the required shape in few reasonably long iterative steps. Therefore the lack of the exact tool shape knowledge is tolerated. Sometimes, this indirect method is not feasible even if small parts are considered. Moreover, if processes on machines like planetary (continuous) polishers are considered, the incorrect shape of the polishing pad could extend the polishing times extremely. Every iteration step takes hours. Even worse, polished piece could be wasted if the pad has a poor shape. The ability of the tool shape determination would be very valuable in those types of lengthy processes. It was our primary motivation to develop a contactless measurement method for large diffusive surfaces and demonstrate its usability. The proposed method is based on application of multiwavelength digital holographic interferometry with phase shift.

  10. Efficiency and Spectrum Enhancement in a Tapered Free-Electron Laser Amplifier

    SciTech Connect

    Wang, X. J.; Harder, D.; Murphy, J. B.; Qian, H.; Shen, Y.; Yang, X.; Freund, H. P.; Miner, W. H. Jr.

    2009-10-09

    We report the first experimental characterization of efficiency and spectrum enhancement in a laser-seeded free-electron laser using a tapered undulator. Output and spectra in the fundamental and third harmonic were measured versus distance for uniform and tapered undulators. With a 4% field taper over 3 m, a 300% (50%) increase in the fundamental (third harmonic) output was observed. A significant improvement in the spectra with the elimination of sidebands was observed using a tapered undulator. The experiment is in good agreement with predictions using the MEDUSA simulation code.

  11. Coupled-Cavity Traveling-Wave Tube Has Phase-Adjusted Taper

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey D.

    1992-01-01

    In structure of improved coupled-cavity traveling-wave tube amplifier, lengths of cavities chosen according to computer-generated, nonlinear taper to increase efficiency of conversion of power from electron beam to microwave. Design calls for "phase-adjusted taper," calculated so phase of electron bunches with respect to phase of microwave changes gradually from value conducive to formation of strong bunches to value conducive to strong transfer of power to microwave at output of taper. Phase-adjusted taper significantly increases power capability of microwave transmission, enabling satellite-communication systems to have higher data-transmission rates.

  12. Efficiency enhancement of coupled-cavity TWT's through cavity resonance tapering

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.

    1979-01-01

    The paper examines efficiency enhancement of coupled-cavity traveling-wave tube (TWT) through cavity resonance tapering. Beam-wave resynchronization through circuit velocity reduction is used for TWT efficiency enhancement, with circuit velocity reduction in coupled cavity TWT's accomplished through period tapering. However, the amount of the latter is limited by the stability considerations, so that beyond a critical value of velocity reduction, the tube may be subject to zero drive oscillations originating in the velocity taper region. The coupled-cavity resonance tapering allows the velocity reduction to continue beyond the limit of stable period tapering, and it is accomplished by a gradual reduction in the cavity resonance frequency, with the period and the circuit bandwidth unchanged. The advantages of cavity resonance tapering vs period tapering are discussed, and test data are presented with the results of large-signal computer calculations. It is shown that cavity resonance tapering can produce efficiencies as period tapering without incurring the same risk of lower band-edge oscillations.

  13. Multicolor upconversion emissions in Tm 3+/Er3+ codoped tellurite photonic microwire between silica fiber tapers.

    PubMed

    Chen, Nan-Kuang; Kuan, Pei-Wen; Zhang, Junjie; Zhang, Liyan; Hu, Lili; Lin, Chinlon; Tong, Limin

    2010-12-06

    We report multicolor upconversion emissions including the blue-violet, green, and red lights in a Tm 3+/Er3+codoped tellurite glass photonic microwire between two silica fiber tapers. A silica fiber is tapered until its evanescent field is exposed and then angled-cleaved at the tapered center to divide the tapered fibers into two parts. A tellurite glass is melted by a gas flame to cluster into a sphere at the tip of one tapered fiber. The other angled-cleaved tapered fiber is blended into the melted tellurite glass. When the tellurite glass is melted, the two silica fiber tapers are simultaneously moving outwards to draw the tellurite glass into a microwire in between. The advantage of angled-cleaving on fiber tapers is to avoid cavity resonances in high index photonic microwire. Thus, the broadband white light can be transmitted between silica fibers and a special optical property like high intensity upconversion emission can be achieved. A cw 1064 nm Nd:YAG laser light is launched into the Tm 3+/Er3+ codoped tellurite microwire through a silica fiber taper to generate the multicolor upconversion emissions, including the blue-violet, green, and red lights, simultaneously.

  14. Characterization of arbitrary fiber taper profiles with optical microscopy and image processing algorithms

    NASA Astrophysics Data System (ADS)

    Farias, Heric D.; Sebem, Renan; Paterno, Aleksander S.

    2014-08-01

    This work reports results from the development of a software to process the parameters involved in the characterization of fiber taper profiles, while using optical microscopy, a high-definition camera and a high- precision translation stage as the moveable base on which the taper is positioned. In addition to this procedure, image processing algorithms were customized to process the acquired images. With edge detection algorithms in the stitched image, one would be able to characterize the given taper radius curve that represents the taper profile when the camera has a sufficient resolution. As a consequence, the proposed fiber taper characterization procedure is a first step towards a high-resolution characterization of fiber taper diameters with arbitrary profiles, specially this case, in which tapers are fabricated with the stepwise technique that allows the production of non- biconical profiles. The parameters of the stitched images depends on the used microscope objective and the length of the characterized tapers. A non-biconical arbitrary taper is measured as an example for the illustration of the developed software and procedure.

  15. Flexibility of K3 and ProTaper universal instruments.

    PubMed

    Grazziotin-Soares, Renata; Barato Filho, Flares; Vanni, José Roberto; Almeida, Susimara; Oliveira, Elias Pandonor Motcy de; Barletta, Fernando Branco; Limongi, Orlando

    2011-01-01

    This study used a mechanical test to evaluate the flexibility of instruments from the K3 (conicity 0.04) and the ProTaper Universal systems when they were new and after 5 uses in simulated canals. Five sets of instruments of each system were tested: K3 (15, 20, 25, 30, 35, 40 and 45) and ProTaper Universal (S1, S2, F1, F2, F3, F4 and F5). Each set of instruments was used to prepare a simulated canal and the same set of instruments was used 5 times (50 canals). The number of each subgroup represented the number of uses: 0 (control), 1, 3 and 5 uses. Before and after each use, the instruments were submitted to a mechanical flexibility test performed in a Versat 502 universal testing machine. Interactions between the instrument and the number of uses were analyzed by ANOVA and Tukey's test at a 5% level of significance. Instruments from both systems presented lower flexibility after the third use compared to the flexibility obtained after uses 0 and 1 (p<0.05), and maintained the same flexibility after the fifth use. The flexibility of instruments from the K3 system decreased with the increase of diameter, irrespective of the number of uses. Among the instruments from the ProTaper Universal system, the shaping files presented greater flexibility than the finishing files. F2 and F3 were the least flexible instruments, and F4 and F5 presented flexibility values similar to those of F1.

  16. Compound-taper feed horn for NASA 70-m antennas

    NASA Astrophysics Data System (ADS)

    Manshadi, Farzin; Hartop, Rob

    1988-09-01

    A novel X-band feedhorn was designed for the Deep Space Network (DSN) 70-meter antennas. The feedhorn is a compound-taper structure consisting of a corrugated flared section and a corrugated straight section. This feedhorn is designed to closely imitate the characteristics of the standard feedhorn, while providing the proper phase center location, without adding any significant loss to the system. The use of the existing feedhorn and the ease of manufacturing the corrugated straight section have resulted in major overall cost savings.

  17. Compound-taper feedhorn for the DSN 70-meter antennas

    NASA Astrophysics Data System (ADS)

    Manshadi, F.; Hartop, R.

    1987-08-01

    A novel X-band feedhorn was designed for the Deep Space Network (DSN) 70-meter antennas. The feedhorn is a compound-taper structure consisting of a corrugated flared section and a corrugated straight section. This feedhorn is designed to closely initiate the characteristics of the standard feedhorn, while providing the proper phase center location, without adding any significant loss to the system. The use of the existing feedhorn and the ease of manufacturing the corrugated straight section have resulted in major overall cost savings.

  18. Compound-taper feedhorn for the DSN 70-meter antennas

    NASA Technical Reports Server (NTRS)

    Manshadi, F.; Hartop, R.

    1987-01-01

    A novel X-band feedhorn was designed for the Deep Space Network (DSN) 70-meter antennas. The feedhorn is a compound-taper structure consisting of a corrugated flared section and a corrugated straight section. This feedhorn is designed to closely initiate the characteristics of the standard feedhorn, while providing the proper phase center location, without adding any significant loss to the system. The use of the existing feedhorn and the ease of manufacturing the corrugated straight section have resulted in major overall cost savings.

  19. Compound-taper feed horn for NASA 70-m antennas

    NASA Technical Reports Server (NTRS)

    Manshadi, Farzin; Hartop, Rob

    1988-01-01

    A novel X-band feedhorn was designed for the Deep Space Network (DSN) 70-meter antennas. The feedhorn is a compound-taper structure consisting of a corrugated flared section and a corrugated straight section. This feedhorn is designed to closely imitate the characteristics of the standard feedhorn, while providing the proper phase center location, without adding any significant loss to the system. The use of the existing feedhorn and the ease of manufacturing the corrugated straight section have resulted in major overall cost savings.

  20. Gaussian Filtering with Tapered Oil-Filled Photonic Bandgap Fibers

    NASA Astrophysics Data System (ADS)

    Brunetti, A. C.; Scolari, L.; Weirich, J.; Eskildsen, L.; Bellanca, G.; Bassi, P.; Bjarklev, A.

    2008-10-01

    A tunable Gaussian filter based on a tapered oil-filled photonic crystal fiber is demonstrated. The filter is centered at λ = 1364 nm with a bandwidth (FWHM) of 237nm. Tunability is achieved by changing the temperature of the filter. A shift of 210nm of the central wavelength has been observed by increasing the temperature from 25 °C to 100 °C. The measurements are compared to a simulated spectrum obtained by means of a vectorial Beam Propagation Method model.

  1. Space Power Amplification with Active Linearly Tapered Slot Antenna Array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1993-01-01

    A space power amplifier composed of active linearly tapered slot antennas (LTSA's) has been demonstrated and shown to have a gain of 30 dB at 20 GHz. In each of the antenna elements, a GaAs monolithic microwave integrated circuit (MMIC) three-stage power amplifier is integrated with two LTSA's. The LTSA and the MMIC power amplifier has a gain of 11 dB and power added efficiency of 14 percent respectively. The design is suitable for constructing a large array using monolithic integration techniques.

  2. Spatial frequency multiplier with active linearly tapered slot antenna array

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1994-01-01

    A frequency multiplier with active linearly tapered slot antennas (LTSA's) has been demonstrated at the second harmonic frequency. In each antenna element, a GaAs monolithic microwave integrated circuit (MMIC) distributed amplifier is integrated with two LTSA's. The multiplier has a very wide bandwidth and large dynamic range. The fundamental-to-second harmonic conversion efficiency is 8.1 percent. The spatially combined second harmonic signal is 50 dB above the noise level. The design is suitable for constructing a large array using monolithic integration techniques.

  3. Characterization of tapered slot antenna feeds and feed arrays

    NASA Technical Reports Server (NTRS)

    Kim, Young-Sik; Yngvesson, K. Sigfrid

    1990-01-01

    A class of feed antennas and feed antenna arrays used in the focal plane of paraboloid reflectors and exhibiting higher than normal levels of cross-polarized radiation in the diagonal planes is addressed. A model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented. The predictions are in good agreement with experimental results. Tapered slot antenna (TSA) elements are used an example of an element of this type. It is shown that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other, more standard types of arrays incorporating waveguide type elements.

  4. Modeling taper charge with a non-linear equation

    NASA Technical Reports Server (NTRS)

    Mcdermott, P. P.

    1985-01-01

    Work aimed at modeling the charge voltage and current characteristics of nickel-cadmium cells subject to taper charge is presented. Work reported at previous NASA Battery Workshops has shown that the voltage of cells subject to constant current charge and discharge can be modeled very accurately with the equation: voltage = A + (B/(C-X)) + De to the -Ex where A, B, D, and E are fit parameters and x is amp-hr of charge removed during discharge or returned during charge. In a constant current regime, x is also equivalent to time on charge or discharge.

  5. Design and Manufacture of Structurally Efficient Tapered Struts

    NASA Technical Reports Server (NTRS)

    Brewster, Jebediah W.

    2009-01-01

    Composite materials offer the potential of weight savings for numerous spacecraft and aircraft applications. A composite strut is just one integral part of the node-to-node system and the optimization of the shut and node assembly is needed to take full advantage of the benefit of composites materials. Lockheed Martin designed and manufactured a very light weight one piece composite tapered strut that is fully representative of a full scale flight article. In addition, the team designed and built a prototype of the node and end fitting system that will effectively integrate and work with the full scale flight articles.

  6. FEL Gain Length and Taper Measurements at LCLS

    SciTech Connect

    Ratner, Daniel; Brachmann, A.; Decker, F.J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, P.; Huang, Z.; Iverson, R.; Loos, H.; Miahnahri, A.; Nuhn, H.D.; Turner, J.; Welch, J.; White, W.; Wu, J.; Xiang, D.; Yocky, G.; /SLAC /LBL, Berkeley

    2010-07-30

    We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 {angstrom} at the Linac Coherent Light Source (LCLS). By disrupting the FEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.

  7. Continuously tunable delay line based on SOI tapered Bragg gratings.

    PubMed

    Giuntoni, Ivano; Stolarek, David; Kroushkov, Dimitar I; Bruns, Jürgen; Zimmermann, Lars; Tillack, Bernd; Petermann, Klaus

    2012-05-07

    The realization of an integrated delay line using tapered Bragg gratings in a drop-filter configuration is presented. The device is fabricated on silicon-on-insulator (SOI) rib waveguides using a Deep-UV 248 nm lithography. The continuous delay tunability is achieved using the thermo-optical effect, showing experimentally that a tuning range of 450 ps can be obtained with a tuning coefficient of -51 ps/°C. Furthermore the system performance is considered, showing that an operation at a bit rate of 25 Gbit/s can be achieved, and could be extended to 80 Gbit/s with the addition of a proper dispersion compensation.

  8. Multimaterial preform coextrusion for robust chalcogenide optical fibers and tapers.

    PubMed

    Tao, Guangming; Shabahang, Soroush; Banaei, Esmaeil-Hooman; Kaufman, Joshua J; Abouraddy, Ayman F

    2012-07-01

    The development of robust infrared fibers is crucial for harnessing the capabilities of new mid-infrared lasers. We present a novel approach to the fabrication of chalcogenide glass fiber preforms: one-step multimaterial extrusion. The preform consists of a glass core and cladding surrounded by a built-in, thermally compatible, polymer jacket for mechanical support. Using this approach we extrude several preform structures and draw them into robust composite fibers. Furthermore, the polymer cladding allows us to produce robust tapers with submicrometer core diameter.

  9. Abrupt fiber taper based Michelson interferometric deflection sensor

    NASA Astrophysics Data System (ADS)

    Tian, Zhaobing; Yam, Scott S.-H.

    2008-06-01

    A new compact standard single mode fiber Michelson interferometer deflection sensor was proposed, tested and simulated. The new interferometer consists of a symmetrical abrupt 3 dB taper region with a 40 μm waist diameter, a 700 μm length and a 500nm thick gold layer coating. Compared with similar interferometric devices based on long period gratings that need microfabrication technology and photosensitive fibers, the proposed sensor uses a much simplified fabrication process and normal single mode fiber, and has a linear response of 1.1nm/mm.

  10. On-chip optical mode exchange using tapered directional coupler

    PubMed Central

    Zhang, Zhonglai; Hu, Xiao; Wang, Jian

    2015-01-01

    We present an on-chip optical mode exchange between two multiplexed modes by using tapered directional couplers on silicon-on-insulator platform. The device consisting of mode multiplexing and mode exchange is compact with relatively large fabrication error tolerance. The simulation results show efficient higher order mode excitation and mode exchange. A low excess loss less than 0.5 dB and high extinction ratio larger than 15 dB over 10 nm wavelength range from 1535 to 1545 nm are achieved. PMID:26530728

  11. Method of making tapered capillary tips with constant inner diameters

    SciTech Connect

    Kelly, Ryan T.; Page, Jason S.; Tang, Keqi; Smith, Richard D.

    2009-02-17

    Methods of forming electrospray ionization emitter tips are disclosed herein. In one embodiment, an end portion of a capillary tube can be immersed into an etchant, wherein the etchant forms a concave meniscus on the outer surface of the capillary. Variable etching rates in the meniscus can cause an external taper to form. While etching the outer surface of the capillary wall, a fluid can be flowed through the interior of the capillary tube. Etching continues until the immersed portion of the capillary tube is completely etched away.

  12. X-Ray Propagation in Tapered Planar Waveguide

    NASA Astrophysics Data System (ADS)

    Dolocan, Andrei; van der Veen, J. Friso

    The present paper focuses on the tapered planar waveguide solution for an initial given wave form. The algorithm is constructed in distributions space such that the calculations can be actually computed by taking some hypothesis regarding the mode series which appear. The whole argument leads to the conclusion that the wave is compressed towards the waveguide in the direction of tilting, leading thereafter to a focusing phenomena. We present two alternative constructions in order to compute the convolution which gives the wave inside the waveguide. The hypothesis are providing results in good approximation with the real evolution of the field within the definition domain.

  13. Frequency characteristics of tapered backfire helical antenna with loaded termination

    NASA Astrophysics Data System (ADS)

    Nakano, H.; Iio, S.; Yamauchi, J.

    1984-06-01

    Effects of loaded termination on a tapered backfire bifilar helical antenna are numerically and experimentally investigated over a wide frequency range of ratio 1:1.7. With the help of the scalar potential for a lumped resistance at the arm end, the current distribution along the helical wire is determined. It is found that nearly constant input impedance, high front-to-back ratio and low axial ratio are realised. The inherent absolute gain is not significantly deteriorated in spite of the use of a terminal resistor. The existence of the phase centre is also demonstrated, and the phase centre location is presented as a function of frequency.

  14. Polishing performances of different optics with different size powder and different pH value slurries during CMP polishing

    NASA Astrophysics Data System (ADS)

    Cao, Jun; Wei, Chaoyang; Liu, Shijie; Dun, Aihuan; Yang, Minghong; Xu, Xueke; Shao, Jianda

    2015-10-01

    Different size polishing powder and different pH value ceria slurries were used to polish fused silica glass K9 glass and Nd-doped glass on pitch plate. Material removal rates (MRR) of glass polished with different size powder and various pH value slurries, and textures of each sample were characterized. The results show that powder size has an effect on glass polishing performance: scratch densities increase with the increase of polishing powder size; surface textures become rougher with the increase of the size of polishing powder. The slurry pH value also affects glass polishing performance: MRR of fused silica glass are lowest under any pH value slurry while Nd-doped glass has the largest MRR; removal rates of all three kinds of glass will rise under both acidic and alkaline condition. Near neutral polishing environment and smaller size powder are useful for the surface polishing process. The results further reveal polishing mechanism and provide the guidance for glass surface process.

  15. Embryonic body formation using the tapered soft stencil for cluster culture device.

    PubMed

    Yukawa, Hiroshi; Ikeuchi, Masashi; Noguchi, Hirofumi; Miyamoto, Yoshitaka; Ikuta, Koji; Hayashi, Shuji

    2011-05-01

    Induced pluripotent stem (iPS) cells are expected to provide a source of tissue, a renewable cell source for tissue engineering, and a method for in vitro drug screening for patient-specific or disease-specific treatment. A simple technology by which iPS cells can be differentiated effectively and in large quantities is strongly desired. In this paper, a new device (Tapered Soft Stencil for Cluster Culture: TASCL) is proposed for the easy and efficient formation of EBs which can be used in regenerative medicine. This device was compared with the two major methods currently being evaluated, namely the HD method and the Terasaki® plate (MWC substitution), in terms of the efficiency, morphology and acquired number of EB formation. Using the TASCL device, the shape of the EBs formed was almost a perfect sphere, and the formation was also faster than for the two other methods. There was little variability in the number of cells. Moreover, EBs formed using the TASCL device had the ability to differentiate into all three germ layers, and differentiation of EBs from the TASCL culture into hepatic cells was confirmed. In conclusion, it appears that the TASCL device can be utilized for EB formation to generate cells for regenerative medicine applications.

  16. The advancement of the high precision stress polishing

    NASA Astrophysics Data System (ADS)

    Li, Chaoqiang; Lei, Baiping; Han, Yu

    2016-10-01

    The stress polishing is a kind of large-diameter aspheric machining technology with high efficiency. This paper focuses on the principle, application in the processing of large aspheric mirror, and the domestic and foreign research status of stress polishing, aimed at the problem of insufficient precision of mirror surface deformation calculated by some traditional theories and the problem that the output precision and stability of the support device in stress polishing cannot meet the requirements. The improvement methods from these three aspects are put forward, the characterization method of mirror's elastic deformation in stress polishing, the deformation theory of influence function and the calculation of correction force, the design of actuator's mechanical structure. These improve the precision of stress polishing and provide theoretical basis for the further application of stress polishing in large-diameter aspheric machining.

  17. Corrosion and Fretting of a Modular Hip System: A Retrieval Analysis of 60 Rejuvenate Stems.

    PubMed

    De Martino, Ivan; Assini, Joseph B; Elpers, Marcella E; Wright, Timothy M; Westrich, Geoffrey H

    2015-08-01

    Femoral stems with dual-taper modularity were introduced to allow independent control of length, offset, and version. Corrosion and fretting related to micromotion at the neck-stem junction are thought to stimulate an adverse local tissue reaction (ALTR). Analysis of 60 consecutively retrieved modular-neck stem implants (Rejuvenate, Stryker) revised primarily for ALTR was done to determine the variables influencing corrosion and fretting patterns at the neck-stem interface. Taper damage evaluation was performed with stereomicrocopic analysis with two observers. Evidence of fretting and corrosion was seen at the neck-stem taper in all implants, including three implants revised for periprosthetic fractures within four weeks of the index surgery indicating that this process starts early. Femoral stems paired with the long overall neck lengths had significantly higher corrosion scores. Correlation of the corrosion severity at particular locations with the length of implantation suggests that the neck-stem junction experiences cyclic cantilever bending in vivo. The positive correlation between the length of implantation and fretting/corrosion scores bodes poorly for patients who still have this implant. Scanning electron microscopy on a subset of specimens was also performed to evaluate the black corrosion material. We strongly urge frequent follow-up exams for every patient with this particular modular hip stem.

  18. Constellation-X Cylinder Figuring and Polishing Studies

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Arsenovic, Petar; Content, David; Saha, Timo; Strojny, Carl; Wright, Geraldine; Fleetwood, Charles

    2001-01-01

    In support of Goddard's Constellation-X mandrel manufacturing effort a series of fabrication experiments are being performed to determine a best approach. Currently, polishing immediately after diamond turning, produces a RMS surface roughness of 0.31 nm, on a nickel plated aluminum mandrel. Studies currently under way will incorporate an abrasive figuring step followed by a polishing operation. The current diamond turning, figuring and polishing procedures will be described and the results presented.

  19. Spiralling tapered slip-on drill string stabilizer

    SciTech Connect

    Beasley, T.R.; Teng, C.C.

    1986-12-23

    A stabilizer is described for use in a drilling string comprising: a substantially cylindrical body member having a central passageway to accommodate the drill sting, the inside surface of the body member defining a right-hand spiralling thread with a tapered trailing edge which spirals from a starting point on the body member. The thread terminates internally of the body member in an arcuate recess extending around the interior of the body member; a key member is secured to the inner wall surface of the recess of the body member, the key member having a lug extending longitudinally of the body member within the recess; a slip member adapted to thread within the body member between the body member and the drill string. The slip defines a right-hand thread with a matching tapered trailing edge configured to make up with the right-hand thread on the body member and to wedge between the body member and the drill string. One end of the slip terminates in a longitudinally disposed shoulder capable of abutting the lug upon threading of the clip within the body member.

  20. Moment method analysis of linearly tapered slot antennas

    NASA Technical Reports Server (NTRS)

    Koeksal, Adnan

    1993-01-01

    A method of moments (MOM) model for the analysis of the Linearly Tapered Slot Antenna (LTSA) is developed and implemented. The model employs an unequal size rectangular sectioning for conducting parts of the antenna. Piecewise sinusoidal basis functions are used for the expansion of conductor current. The effect of the dielectric is incorporated in the model by using equivalent volume polarization current density and solving the equivalent problem in free-space. The feed section of the antenna including the microstripline is handled rigorously in the MOM model by including slotline short circuit and microstripline currents among the unknowns. Comparison with measurements is made to demonstrate the validity of the model for both the air case and the dielectric case. Validity of the model is also verified by extending the model to handle the analysis of the skew-plate antenna and comparing the results to those of a skew-segmentation modeling results of the same structure and to available data in the literature. Variation of the radiation pattern for the air LTSA with length, height, and taper angle is investigated, and the results are tabulated. Numerical results for the effect of the dielectric thickness and permittivity are presented.

  1. Fatigue Life Methodology for Tapered Hybrid Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    urri, Gretchen B.; Schaff, Jeffery R.

    2006-01-01

    Nonlinear-tapered flexbeam specimens from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. Two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) associated with simulated delamination growth in the flexbeams are presented from both codes. These results compare well with each other and suggest that the initial delamination growth from the tip of the ply-drop toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves for comparison with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared well with the test results.

  2. Analysis of guided wave propagation in a tapered composite panel

    NASA Astrophysics Data System (ADS)

    Wandowski, Tomasz; Malinowski, Pawel; Moll, Jochen; Radzienski, Maciej; Ostachowicz, Wieslaw

    2015-03-01

    Many studies have been published in recent years on Lamb wave propagation in isotropic and (multi-layered) anisotropic structures. In this paper, adiabatic wave propagation phenomenon in a tapered composite panel made out of glass fiber reinforced polymers (GFRP) will be considered. Such structural elements are often used e.g. in wind turbine blades and aerospace structures. Here, the wave velocity of each wave mode does not only change with frequency and the direction of wave propagation. It further changes locally due to the varying cross-section of the GFRP panel. Elastic waves were excited using a piezoelectric transducer. Full wave-field measurements using scanning Laser Doppler vibrometry have been performed. This approach allows the detailed analysis of elastic wave propagation in composite specimen with linearly changing thickness. It will be demonstrated here experimentally, that the wave velocity changes significantly due to the tapered geometry of the structure. Hence, this work motivates the theoretical and experimental analysis of adiabatic mode propagation for the purpose of Non-Destructive Testing and Structural Health Monitoring.

  3. Improved oil-off survivability of tapered roller bearings

    NASA Technical Reports Server (NTRS)

    Kreider, Gary E.; Lee, Peter W.

    1987-01-01

    The aim of this program is to improve the oil-off survivability of a tapered roller bearing when applied to a helicopter transmission, since the tapered bearing has shown a performance advantage in this application. However, the critical roller end-rib conjunction is vulnerable to damage in an oil-off condition. Three powdered metal materials were selected to use as the rib material for oil-off evaluation. These were: M2 steel to a 65% density, CBS 1000M 65% density, and CBS 1000M 75% density. The bearing styles tested were ribbed cone (inner race) and ribbed cup (outer race). Carburized solid CBS 600 was also used as a ribbed material for comparison of oil-off results. The tests were conducted at six speeds from 4000 rpm (0.26 million DN) through 37000 rpm (2.4 million DN).The ribbed cup style bearing achieved longer lives than the ribbed cone style. A standard bearing lasted only 10 minutes at 4000 rpm; however, the 30-min oil-off goal was achieved through 11000 rpm using the survivable ribbed cup bearing. The oil-off lives at 37000 rpm were less than 10 seconds. The grinding of the powder metal materials and surface preparation to achieve an open porosity is extremely critical to the oil-off performance of the powder metal component.

  4. Fatigue Life Analysis of Tapered Hybrid Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; Schaff, Jeffery R.; Dobyns, Alan L.

    2002-01-01

    Nonlinear-tapered flexbeam laminates from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. The two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) obtained from the above codes using the virtual crack closure technique (VCCT) at a resin crack location in the flexbeams are presented for both hybrid material types. These results compare well with each other and suggest that the initial delamination growth from the resin crack toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves and compared with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared reasonably well with the test results.

  5. Defect centers in chemical-mechanical polished MOS oxides

    SciTech Connect

    Shaneyfelt, M.R.; Warren, W.L.; Hetherington, D.L.; Timon, R.P.; Resnick, P.J.; Winokur, P.S.

    1994-12-31

    Defect centers generated in vacuum-ultraviolet irradiated chemical-mechanical polished oxides have been characterized using electron paramagnetic resonance and C-V analysis. Both oxide trap E{sub {gamma}} and interface trap P{sub b0} centers were detected in unpolished and polished oxides. In addition, another interface defect center known as the P{sub b1} center was only identified in the polished oxides, suggesting that the polishing process altered the SiO{sub 2}/Si interface.

  6. Slurry Supplying Method for Large Quartz Glass Substrate Polishing

    NASA Astrophysics Data System (ADS)

    Khajornrungruang, Panart; Kimura, Keiichi; Yui, Ryuji; Wada, Nagisa; Suzuki, Keisuke

    2011-05-01

    Chemical mechanical polishing (CMP) has been used in polishing a photomask substrate in flat-panel display (FPD) manufacture. Moreover, the quadrilateral geometry of quartz glass used as the photomask substrate has been enlarged. However, the slurry cannot flow throughout the glass surface evenly owing to the enlarged substrate covering the center of the platen in the polishing process. In this work, we verified the beneficial of spreading slurry into a non-inflow region by the reinforced suction of the slurry supplied to the polishing pad through a hole at center of the platen. A fluorescent agent was used instead of the slurry for flow visualization.

  7. Performance analysis of CO2 laser polished angled ribbon fiber

    NASA Astrophysics Data System (ADS)

    Sohn, Ik-Bu; Choi, Hun-Kook; Noh, Young-Chul; Lee, Man-Seop; Oh, Jin-Kyoung; Kim, Seong-min; Ahsan, Md. Shamim

    2017-01-01

    This paper demonstrates CO2 laser assisted simultaneous polishing of angled ribbon fibers consisting eight set of optical fibers. The ribbon fibers were rotated vertically at an angle of 12° and polished by repetitive irradiation of CO2 laser beam at the end faces of the fibers. Compared to mechanically polished sharp edged angled fibers, CO2 laser polishing forms curve edged angled fibers. Increase in the curvature of the end faces of the ribbon fibers causes the increase of the fibers' strength, which in turn represents great robustness against fiber connections with other devices. The CO2 laser polished angled fibers have great smoothness throughout the polished area. The smoothness of the fiber end faces have been controlled by varying the number of laser irradiation. After CO2 laser polishing, the average value of the fiber angle of the ribbon fibers is ∼8.28°. The laser polished ribbon fibers show low insertion and return losses when connecting with commercial optical communication devices. The proposed technique of polishing the angled ribbon fibers is highly replicable and reliable and thus suitable for commercial applications.

  8. Condensate polishers for brackish water-cooled PWRs

    SciTech Connect

    Sadler, M.A.; Darvill, M.R.; Bickerstaffe, J.A.; Chakravorti, R.; Siegwarth, D.P.

    1986-07-01

    The objectives of project RP 1571-5 ''Optimization of Pressurized Water Reactor Secondary Water Treatment: Task 4 Conceptual Design Options - Condensate Polishing'' were to provide detailed guidelines for the design of a condensate polishing system for retrofitting to a seawater cooled PWR. For this purpose a national 1100MW PWR with recirculating steam generators was defined. The polished water to be produced by this plant must be of such a quality so as to permit the advisory SGOG guidelines on impurity levels in Steam Generator water to be achieved. Target maximum impurity levels in the final polished water were proposed by the RP 1571 Project review Team and adopted for this study.

  9. Using “Sub-cement” to simulate the long-term fatigue response of cemented femoral stems in a cadaver model: could a novel pre-clinical screening test have caught the Exeter matte problem?

    PubMed Central

    Race, Amos; Miller, Mark A.; Mann, Kenneth A.

    2010-01-01

    Previously, we formulated cement with degraded fatigue properties (sub-cement) to simulate long-term fatigue in short-term cadaver tests. The present study determined the efficacy of sub-cement in a `pre-clinical' test of a design change with known clinical consequences: the “polished” to “matte” transition of the Exeter stem (revision rates were twice as high for matte stems). Contemporary stems were bead-blasted to give Ra=1micron (matte finish). Matte and polished stems were compared in cadaver pairs under stair-climbing loads (3 pairs size-1, 3 pairs size-3). Stem micromotion was monitored during loading. Post-test, transverse sections were examined for cement damage. Cyclic retroversion decreased for polished stems but increased for matte stems (p<0.0001). Implant size had a substantial effect: retroversion of (larger) size-3 stems was half that of size-1 stems and polished size-3 stems subsided 2½ times more than the others. Cement damage measures were similar and open through-cracks occurred around both stems of two pairs. Stem retroversion within the mantle resulted in stem-cement gaps of 50–150microns. Combining information on cyclic motion, cracks, and gaps, we concluded that this test `predicted' higher revision rates for matte stems (it also implied that polished size-3 stems might be superior to size-1). PMID:20476506

  10. Robotic Automation in Computer Controlled Polishing

    NASA Astrophysics Data System (ADS)

    Walker, D. D.; Yu, G.; Bibby, M.; Dunn, C.; Li, H.; Wu, Y.; Zheng, X.; Zhang, P.

    2016-02-01

    We first present a Case Study - the manufacture of 1.4 m prototype mirror-segments for the European Extremely Large Telescope, undertaken by the National Facility for Ultra Precision Surfaces, at the OpTIC facility operated by Glyndwr University. Scale-up to serial-manufacture demands delivery of a 1.4 m off-axis aspheric hexagonal segment with surface precision < 10 nm RMS every four days, compared with a typical year or more for an one-off part. This requires a radically-new approach to large optics fabrication, which will inevitably propagate into wider industrial optics. We report on how these ambitious requirements have stimulated an investigation into the synergy between robots and computer numerically controlled ('CNC') polishing machines for optical fabrication. The objective was not to assess which is superior. Rather, it was to understand for the first time their complementary properties, leading us to operate them together as a unit, integrated in hardware and software. Three key areas are reported. First is the novel use of robots to automate currently-manual operations on CNC polishing machines, to improve work-throughput, mitigate risk of damage to parts, and reduce dependence on highly-skilled staff. Second is the use of robots to pre-process surfaces prior to CNC polishing, to reduce total process time. The third draws the threads together, describing our vision of the automated manufacturing cell, where the operator interacts at cell rather than machine level. This promises to deliver a step-change in end-to-end manufacturing times and costs, compared with either platform used on its own or, indeed, the state-of-the-art used elsewhere.

  11. Polarization-independent all-fiber isolator based on asymmetric fiber tapers.

    PubMed

    Fang, X

    1996-11-01

    Nonreciprocal intensity transmission in optical fibers can be realized by use of an asymmetric fiber taper. A few-mode fiber taper-based nonreciprocal component is designed, and its nonreciprocal transmission characteristics are demonstrated. This structure can be employed to build polarization-independent all-fiber isolators or fiber-optic sensors.

  12. 77 FR 12326 - Tapered Roller Bearings From China; Scheduling of a Full Five-Year Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-29

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Tapered Roller Bearings From China; Scheduling of a Full Five- Year Review AGENCY: United States... Act) to determine whether revocation of the antidumping duty order on tapered roller bearings...

  13. 77 FR 16859 - Tapered Roller Bearings From China; Scheduling of a Full Five-Year Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-22

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Tapered Roller Bearings From China; Scheduling of a Full Five- Year Review AGENCY: United States...)) (the Act) to determine whether revocation of the antidumping duty order on tapered roller bearings...

  14. Novel methods for measuring modulation transfer function for fiber optic taper

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wang, Yaoxiang; Tian, Weijian; Ma, Weihong; Zhang, Hongjian; Sun, Aijuan

    2006-01-01

    As a relay optical component, fiber optic taper has become more important and more widely used in the integrated taper assembly image intensified sensors for military and medical imaging application. However, the method for evaluating the quality of output images from the fiber optic taper is few. In this article, the Modulation Transfer Function (MTF) is introduced and measured to evaluate the image quality of fiber optic taper. Because fiber optic taper is of a mosaic array architecture, there are some new problems need to be resolved in defining MTF of it. And there also should be some special requirements in MTF measurement. Two methods including edge scanning and point imaging analyzing are introduced in measuring MTF of fiber optic taper, in which the incident light, scanning step and scanning range are specially limited. Experiments show that the results of the measurements consist with the theoretical analysis simulated by computer. And the spatial averaged MTF of fiber optic taper has been gotten by two means. It is concluded that the MTF value measured by point imaging is always some higher than measured by edge scanning, because the point imaging is more weakly effected by the fiber arrangement in taper.

  15. The mean aerodynamic chord and the aerodynamic center of a tapered wing

    NASA Technical Reports Server (NTRS)

    Diehl, Walter S

    1942-01-01

    A preliminary study of pitching-moment data on tapered wings indicated that excellent agreement with test data was obtained by locating the quarter-chord point of the average chord on the average quarter-chord point of the semispan. The study was therefore extended to include most of the available data on tapered-wing models tested by the NACA.

  16. Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

    DOE PAGES

    Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.

    2015-08-16

    In this paper, simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a11a2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE 11 mode in an optimized taper is 0.0293(a2-a1)4/amore » $$2\\atop{1}$$1a$$2\\atop{2}$$. These formulae are accurate when a2≲2a1. Slightly more complex formulae, accurate for a2≤4a1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a2≤2.12a1 and less than 0.1 % when a2≤1.53a1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Finally, parabolic tapers may provide lower loss, but linear tapers with moderate values of a2/a1 may be attractive because of their simplicity of fabrication.« less

  17. Competence of Irish and Polish Teachers in the Opinions of Young Polish Immigrants in Ireland

    ERIC Educational Resources Information Center

    Augustyniak, Joanna

    2016-01-01

    Since 2004, Ireland has experienced the arrival of immigrants from various countries from all over the world including Poland. The Polish came to Ireland with their families including children of school age obliged to attend compulsory education. These children have attended schools dissimilar from the ones they are accustomed to in their home…

  18. Precision non-contact polishing tool

    DOEpatents

    Taylor, John S.

    1997-01-01

    A non-contact polishing tool that combines two orthogonal slurry flow geometries to provide flexibility in altering the shape of the removal footprint. By varying the relative contributions of the two flow geometries, the footprint shape can be varied between the characteristic shapes corresponding to the two independent flow regimes. In addition, the tool can include a pressure activated means by which the shape of the brim of the tool can be varied. The tool can be utilized in various applications, such as x-ray optical surfaces, x-ray lithography, lenses, etc., where stringent shape and finish tolerances are required.

  19. Precision non-contact polishing tool

    DOEpatents

    Taylor, J.S.

    1997-01-07

    A non-contact polishing tool is disclosed that combines two orthogonal slurry flow geometries to provide flexibility in altering the shape of the removal footprint. By varying the relative contributions of the two flow geometries, the footprint shape can be varied between the characteristic shapes corresponding to the two independent flow regimes. In addition, the tool can include a pressure activated means by which the shape of the brim of the tool can be varied. The tool can be utilized in various applications, such as x-ray optical surfaces, x-ray lithography, lenses, etc., where stringent shape and finish tolerances are required. 5 figs.

  20. Innovations in high rate condensate polishing systems

    SciTech Connect

    O`Brien, M.

    1995-01-01

    Test work is being conducted at two major east coast utilities to evaluate flow distribution in high flow rate condensate polishing service vessels. The work includes core sample data used to map the flow distribution in vessels as originally manufactured. Underdrain modifications for improved flow distribution are discussed with data that indicates performance increases of the service vessel following the modifications. The test work is on going, with preliminary data indicating that significant improvements in cycle run length are possible with underdrain modifications. The economic benefits of the above modifications are discussed.

  1. A Report of Successful Procedural, Clinical, and Angiographic Outcomes with a Tapered Stent of a Patient in Naturally Tapered Coronary Vessel

    PubMed Central

    Kumar, Yerra Shiv

    2017-01-01

    In cases involving stenosis or occlusions in major parts of a long vessel, natural tapering of coronary vessels may create dilemma in deciding the optimal stent size during percutaneous coronary intervention. In this regard, tapered stents have been developed recently. Herein, we present a case of 67-year-old male patient with triple vessel disease including two tandem lesions in naturally tapered Left Anterior Descending (LAD) artery. The patient received a 3.0–2.5x60 mm Sirolimus-eluting BioMime Morph stent (Meril life Sciences, Gujarat, India) in the mid-distal LAD lesion along with conventional stent implantations in other two lesions. The procedure was successful and good coronary flow was obtained after revascularization. The patient remained asymptomatic thereafter. At one year, angiographic follow-up revealed good flow and no restenosis in the LAD vessel. We are of opinion that using tapered stents with decremented diameter may offer the advantages of excellent adaptation to vessel size, vessel tapering, and good apposition in patients with long coronary lesions in tapered vessels. PMID:28273994

  2. Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

    PubMed Central

    UEZU, Mary Kinue Nakamune; BRITTO, Maria Leticia Borges; NABESHIMA, Cleber K.; PALLOTTA, Raul Capp

    2010-01-01

    Objective The aim of this study was to evaluate the in vitro action of ProTaper retreatment files and ProTaper Universal in the retreatment of mandibular premolars. Material and methods The amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. Thirty teeth had their canals prepared using ProTaper Universal files and were obturated by the single cone technique. The teeth were then stored at 37ºC in a humid environment for 7 days. During the use of the rotary instruments for root canal filling removal, the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris. Results ProTaper Universal files were significantly faster (p=0.0011) than the ProTaper retreatment files to perform gutta-percha removal, but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion. Conclusions ProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris. PMID:21308282

  3. 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

  4. Miniature tapered photonic crystal fiber interferometer with enhanced sensitivity by acid microdroplets etching.

    PubMed

    Qiu, Sun-jie; Chen, Ye; Kou, Jun-long; Xu, Fei; Lu, Yan-qing

    2011-08-01

    We fabricate a miniature tapered photonic crystal fiber (PCF) interferometer with enhanced sensitivity by acid microdroplets etching. This method is very simple and cost effective, avoiding elongating the PCF, moving and refixing the device during etching, and measuring. The refractive index sensing properties with different PCF diameters are investigated both theoretically and experimentally. The tapering velocity can be controlled by the microdroplet size and position. The sensitivity greatly increases (five times, 750 nm/RIU) and the size decreases after slightly tapering the PCF. The device keeps low temperature dependence before and after tapering. More uniformly and thinly tapered PCFs can be realized with higher sensitivity (∼100 times) by optimizing the etching process.

  5. Intensity modulated SMF cascaded tapers with a hollow core PCF based microcavity for curvature sensing

    NASA Astrophysics Data System (ADS)

    Dass, Sumit; Narayan Dash, Jitendra; Jha, Rajan

    2016-03-01

    We propose a highly sensitive curvature sensor based on cascaded single mode fiber (SMF) tapers with a microcavity. The microcavity is created by splicing a small piece of hollow core photonic crystal fiber (HCPCF) at the end of an SMF to obtain a sharp interference pattern. Experimental results show that two SMF tapers enhance the curvature sensitivity of the system and by changing the tapering parameters of the second taper, the curvature sensitivity of the system can be tailored, together with the fringe contrast of the interference pattern. A maximum curvature sensitivity of 10.4 dB/m-1 is observed in the curvature range 0 to 1 m-1 for a second taper diameter of 18 μm. The sensing setup is highly stable and shows very low temperature sensitivity. As the interrogation is intensity based, a low cost optical power meter can be utilized to determine the curvature.

  6. Supercontinuum generation from 437 to 2850 nm in a tapered fluorotellurite microstructured fiber

    NASA Astrophysics Data System (ADS)

    Wang, F.; Jia, Z. X.; Yao, C. F.; Wang, S. B.; Hu, M. L.; Wu, C. F.; Ohishi, Y.; Qin, W. P.; Qin, G. S.

    2016-12-01

    We demonstrated supercontinuum (SC) generation in a tapered fluorotellurite microstructured fiber (MF) with a sub-micrometer core diameter. Fluorotellurite MFs based on TeO2-BaF2-Y2O3 glasses were fabricated by using a rod-in-tube method and a tapered fluorotellurite MF with a minimum core diameter of ~0.65 µm was prepared by employing a tapering system. A 1560 nm femtosecond fiber laser was used as the pumping source. With increasing the peak power of the launched pump laser to ~11 kW, SC light expanding from 437 to 2850 nm was generated in the tapered fluorotellurite MF. In addition, relatively strong blue-shifted dispersive wave at ~489 nm was also observed from the tapered fluorotellurite MF.

  7. Spectral tuning of a locally bent microfiber taper interferometer with a nanosized liquid crystal overlay.

    PubMed

    Luo, Haimei; Wang, Changjing; Ji, Yinghua; Yuan, Wen; Zhang, Guoping; Wang, Yifan; Hong, Zehua; Wang, Xianping

    2016-09-10

    In this paper, the tuning characteristics of locally bent microfiber taper covered with a nanosized high-refractive-index liquid crystal (LC) layer under different temperatures and electric field intensities have been theoretically analyzed and experimentally investigated. A locally bent microfiber taper interferometer with a waist diameter of ∼3.72  μm is fabricated by using the flame brushing technique, followed by bending the transition region of the taper to form a modal interferometer and later by placing a ∼200  nm LC layer over the uniform taper waist region. Experimental results indicate that a high-efficiency thermal or electric tuning of an LC-coated locally bent microfiber taper interferometer could be achieved. This suggests a potential application of this device as tunable all-fiber photonic devices, such as filters, modulators, and sensing elements.

  8. Deterministic Computer-Controlled Polishing Process for High-Energy X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    A deterministic computer-controlled polishing process for large X-ray mirror mandrels is presented. Using tool s influence function and material removal rate extracted from polishing experiments, design considerations of polishing laps and optimized operating parameters are discussed

  9. High Efficiency Electron-Laser Interactions in Tapered Helical Undulators

    NASA Astrophysics Data System (ADS)

    Duris, Joseph Patrick

    Efficient coupling of relativistic electron beams with high power radiation lies at the heart of advanced accelerator and light source research and development. The inverse free electron laser is a stable accelerator capable of harnessing very high intensity laser electric fields to efficiently transfer large powers from lasers to electron beams. In this dissertation, we first present the theoretical framework to describe the interaction, and then apply our improved understanding of the IFEL to the design and numerical study of meter-long, GeV IFELs for compact light sources. The central experimental work of the dissertation is the UCLA BNL helical inverse free electron laser experiment at the Accelerator Test Facility in Brookhaven National Laboratory which used a strongly tapered 54cm long, helical, permanent magnet undulator and a several hundred GW CO2 laser to accelerate electrons from 52 to 106MeV, setting new records for inverse free electron laser energy gain (54MeV) and average accelerating gradient (100MeV/m). The undulator design and fabrication as well as experimental diagnostics are presented. In order to improve the stability and quality of the accelerated electron beam, we redesigned the undulator for a slightly reduced output energy by modifying the magnet gap throughout the undulator, and we used this modified undulator to demonstrated capture of >25% of the injected beam without prebunching. In the study of heavily loaded GeV inverse free electron lasers, we show that a majority of the power may be transferred from a laser to the accelerated electron beam. Reversing the process to decelerate high power electron beams, a mechanism we refer to as tapering enhanced stimulated superradiant amplification, offers a clear path to high power light sources. We present studies of radiation production for a wide range of wavelengths (10mum, 13nm, and 0.3nm) using this method and discuss the design for a deceleration experiment using the same undulator used

  10. Polishing techniques for MEGARA pupil elements optics

    NASA Astrophysics Data System (ADS)

    Izazaga, R.; Carrasco, E.; Aguirre, D.; Salas, A.; Gil de Paz, A.; Gallego, J.; Iglesias, J.; Arroyo, J. M.; Hernández, M.; López, N.; López, V.; Quechol, J. T.; Salazar, M. F.; Carballo, C.; Cruz, E.; Arriaga, J.; De la Luz, J. A.; Huepa, A.; Jaimes, G. L.; Reyes, J.

    2016-07-01

    MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is the new integral-field and multi-object optical spectrograph for the 10.4m Gran Telescopio Canarias.. It will offer RFWHM 6,000, 12,000 and 18,700 for the low- , mid- and high-resolution, respectively in the wavelength range 3650-9700Å. .The dispersive elements are volume phase holographic (VPH) gratings, sandwiched between two flat Fused Silica windows of high optical precision in large apertures. The design, based in VPHs in combination with Ohara PBM2Y prisms allows to keep the collimator and camera angle fixed. Seventy three optical elements are being built in Mexico at INAOE and CIO. For the low resolution modes, the VPHs windows specifications in irregularity is 1 fringe in 210mm x 170mm and 0.5 fringe in 190mm x 160mm. for a window thickness of 25 mm. For the medium and high resolution modes the irregularity specification is 2 fringes in 220mm x 180mm and 1 fringe in 205mm x 160mm, for a window thickness of 20mm. In this work we present a description of the polishing techniques developed at INAOE optical workshop to fabricate the 36 Fused Silica windows and 24 PBM2Y prisms that allows us to achieve such demanding specifications. We include the processes of mounting, cutting, blocking, polishing and testing.

  11. Lapping: Polishing and shear mode grinding

    SciTech Connect

    Brown, N.J.

    1990-02-01

    It is the thesis of this paper that shear mode grinding (SMG), (ductile grinding, nanogrinding, fractureless grinding) is just a particular form of polishing. It may be unique in that it can involve a hard wheel of very precise dimensions compared to the soft laps usually used in polishing. Such a wheel would permit the fabrication of a precision surface on a brittle material such as glass at a precisely located and oriented position on a part. The technological and economic consequences of such a process seem important but the technical obstacles to implementing the technique are for the moment formidable. It is in production in Japan. This paper provides a bit of understanding of that process obtained by making an end run around the obstacles to view the process from the vantage point of lapping. The paper will lay out some of the concepts and terminology necessary to understand the papers that have supplied the real labor to get us to this point. It will refer to parts of this work briefly in passing so the reader who needs the details knows where to look, and for what, in the bibliography appended. 32 refs., 5 figs.

  12. 76 FR 6397 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-04

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the... shipper review (``NSR'') of the antidumping duty order on tapered roller bearings (``TRBs'') from the... Order; Tapered Roller Bearings and Parts Thereof, Finished or Unfinished, From the People's Republic...

  13. 76 FR 45777 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-01

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the... review (``NSR'') of the antidumping duty order on tapered roller bearings (``TRBs'') from the People's... Order; Tapered Roller Bearings and Parts Thereof, Finished or Unfinished, From the People's Republic...

  14. 76 FR 3086 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-19

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the... administrative review of tapered roller bearings (``TRBs'') from the People's Republic of China (``PRC''). See Tapered Roller Bearings and Parts Thereof, Finished or Unfinished, From the People's Republic of...

  15. 77 FR 52682 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-30

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the... the antidumping duty order on tapered roller bearings and parts thereof, finished and unfinished... should the order be revoked.\\2\\ \\2\\ See Tapered Roller Bearings and Parts Thereof, Finished...

  16. 77 FR 2031 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-13

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the... shipper review of the antidumping duty order on tapered roller bearings and parts thereof, finished and unfinished from the People's Republic of China. See Tapered Roller Bearings and Parts Thereof, Finished...

  17. Mechanized Polishing of Optical Rod and Fiber Ends

    NASA Technical Reports Server (NTRS)

    Gum, J. S.

    1987-01-01

    Workpiece holder for standard grinding and polishing machine makes it easier to produce optical finish and shape on end of metal or glass rod or bundle of optical fibers. Previously, glass parts lapped and polished manually, time-consuming procedure calling for considerable skill.

  18. POLISHING EFFLUENT FROM A PERCHLORATE-REDUCING ANAEROBIC BIOLOGICAL CONTACTOR

    EPA Science Inventory

    The U.S. Environmental Protection Agency undertook at 3 ½ year pilot-scale biological perchlorate treatment study that included two long (311 and 340 days) examinations of anaerobic effluent polishing. The polishing system consisted of hydrogen peroxide addition and aeration, fo...

  19. Correction on the edge collapse during the synchrospeed polishing process

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Liu, Yang; Zhang, Bingqin; Shen, Yi; Zhang, Hao; Hui, Changshun

    2016-10-01

    In the last few years, synchrospeed polishing has been widely employed in the mass spherical optical surface manufacturing process with the development of the optical polishing technology and equipment. However, the edge collapse appears easily in the synchrospeed polishing process because of the high edge pressure. The principle of the spherical surface synchrospeed polishing process is introduced, and the motion mathematical model is developed. A new multi-mode polishing method which utilizes a big polishing tool combined with a small one to correction on the edge collapse is proposed. A sphere that aperture is 110mm and radiuses is 238mm is polished via the mew method. The collapse radio is decease from 20% to 10%, and the D-value of collapse is deceased from 459.29nm to 68.74nm before and after the correct polishing process. The surface figure accuracy RMS is improved from 90.97nm to 15.97nm accordingly. The experiment proved that the correction method is very useful to correct the edge collapse.

  20. Spatial Fourier Transform Analysis of Polishing Pad Surface Topography

    NASA Astrophysics Data System (ADS)

    Khajornrungruang, Panart; Kimura, Keiichi; Okuzono, Takahisa; Suzuki, Keisuke; Kushida, Takashi

    2012-05-01

    The spatial Fourier transform analysis is proposed to quantitatively evaluate the irregular topography of the conditioned chemical mechanical polishing (CMP) pad surface. We discuss the power spectrum in the spatial wavelengths of the surface topographies corresponding to polishing time. We conclude that the spatial wavelength of less than 5 µm in the topography yielded high material removal rates.

  1. The Immigrant Experience: A Polish-American Model. Student Materials.

    ERIC Educational Resources Information Center

    Social Studies Development Center, Bloomington, IN.

    Designed to supplement eleventh grade U.S. history textbooks, the self-contained activities in this student guide will help students learn about Polish immigration to America. Intended for use with an accompanying teacher's guide, the activities are organized around five themes: (1) the colonial period: early Polish-American influence; (2) the…

  2. Global Citizenship Education in School Curricula. A Polish Perspective

    ERIC Educational Resources Information Center

    Leek, Joanna

    2016-01-01

    The purpose of this study is to present global citizenship education from a Polish perspective. Analyzing the issue, the first part of this paper presents the development of citizenship education, followed by the current status of global citizenship education in Polish schools. In the second part of the study I draw attention to national curricula…

  3. Analysis and modeling of tribology effects in conventional glass polishing

    NASA Astrophysics Data System (ADS)

    Waechter, Daniel; Dambon, Olaf; Klocke, Fritz

    2013-09-01

    Conventional or chemo-mechanical polishing represents the polishing technology most often applied for manufacturing precision glass optics. It is applied on various machine types and for all kinds of geometries. But it still represents the manufacturing step with the lowest process stability. This work deals with the analysis and descriptive modeling of contact conditions occurring in the process area. The polishing process is assumed as a hydrodynamic system. The model aims for a qualitative description of the formation of a fluid film between pad and surface. The models enable the theoretical discussion of the effects of major process parameters on the fluid film thickness. Secondly, the theoretical considerations are validated by experiments on a tribometer. With this test bench the effects of the polishing parameters as well pad properties on the contact conditions are investigated. Additional experiments are conducted on a polishing machine for validation the results. It is found, that the hydrodynamic theory describes the formation of fluid film in polishing. Under typical polishing conditions, the friction regime is in the range of mixed friction. That means pad asperities and polishing grains are not completely separated from the surface by a fluid film. The transition into erosive wear and pure liquid friction was not reached. But an analysis of the surface quality in dependence on the relative speed showed, that the quality starts decreasing after a minimum, far before reaching the transition point. Based on the derived qualitative description, the effects of process parameters and pad properties on the fluid film can be discussed.

  4. Growth strategies to control tapering in Ge nanowires

    SciTech Connect

    Periwal, P.; Baron, T. Salem, B.; Bassani, F.; Gentile, P.

    2014-04-01

    We report the effect of PH{sub 3} on the morphology of Au catalyzed Ge nanowires (NWs). Ge NWs were grown on Si (111) substrate at 400 °C in the presence of PH{sub 3}, using vapor-liquid-solid method by chemical vapor deposition. We show that high PH{sub 3}/GeH{sub 4} ratio causes passivation at NW surface. At high PH{sub 3} concentration phosphorous atoms attach itself on NW surface and form a self-protection coating that prevents conformal growth and leads to taper free nanostructures. However, in case of low PH{sub 3} flux the combination of axial and radial growth mechanism occurs resulting in conical structure. We have also investigated axial PH{sub 3}-intrinsic junctions in Ge NWs. The unusual NW shape is attributed to a combination of catalyzed, uncatalyzed and diffusion induced growth.

  5. Lithographically defined tapered waveguides for transformation optics device applications

    NASA Astrophysics Data System (ADS)

    Adams, Todd; Ermer, Kurt; Piazza, Alex; Schaefer, Dave; Smolyaninova, Vera; Smolyaninov, Igor

    2013-03-01

    Recent progress in metamaterials and transformation optics (TO) give rise to such fascinating devices as perfect lenses, invisibility cloaks, etc., which are typically achieved with metamaterials. Realization of these devices using electromagnetic metamaterials would require sophisticated nanofabrication techniques. Recently we have demonstrated that the same effect may be achieved by much simpler means. By tapering a waveguide, one can literally ``bend'' optical space and achieve the same result. Our approach leads to much simpler designs, which require conventional lithographic techniques and readily available dielectric materials. Here we report fabrication of low cost TO devices, such as analogues of metamaterial lenses and invisibility cloaks. Their broadband properties will be demonstrated and performance for light of different polarization will be discussed. This work is supported by NSF grants DMR-0348939 and DMR-110476.

  6. Development of SiC Large Tapered Crystal Growth

    NASA Technical Reports Server (NTRS)

    Neudeck, Phil

    2011-01-01

    Research Focus Area: Power Electronics, Temperature Tolerant Devices. Demonstrate initial feasibility of totally new "Large Tapered Crystal" (LTC) process for growing vastly improved large-diameter wide-band gap wafers. Addresses Targets: The goal of this research is to experimentally investigate and demonstrate feasibility of the key unproven LTC growth processes in SiC. Laser-assisted growth of long SiC fiber seeds. Radial epitaxial growth enlargement of seeds into large SiC boules. Uniqueness and Impacts open a new technology path to large-diameter SiC and GaN wafers with 1000-fold defect density improvement at 2-4 fold lower cost. Leapfrog improvement in wide band gap power device capability and cost.

  7. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

    PubMed

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-12-16

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

  8. Thin-ribbon tapered coupler for dielectric waveguides

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Otoshi, T. Y.; Shimabukuro, F. I.

    1994-01-01

    A recent discovery shows that a high-dielectric constant, low-loss, solid material can be made into a ribbon-like waveguide structure to yield an attenuation constant of less than 0.02 dB/m for single-mode guidance of millimeter/submillimeter waves. One of the crucial components that must be invented in order to guarantee the low-loss utilization of this dielectric-waveguide guiding system is the excitation coupler. The traditional tapered-to-a-point coupler for a dielectric rod waveguide fails when the dielectric constant of the dielectric waveguide is large. This article presents a new way to design a low-loss coupler for a high- or low-dielectric constant dielectric waveguide for millimeter or submillimeter waves.

  9. Tapered whiskers are required for active tactile sensation

    PubMed Central

    Hires, Samuel Andrew; Pammer, Lorenz; Svoboda, Karel; Golomb, David

    2013-01-01

    Many mammals forage and burrow in dark constrained spaces. Touch through facial whiskers is important during these activities, but the close quarters makes whisker deployment challenging. The diverse shapes of facial whiskers reflect distinct ecological niches. Rodent whiskers are conical, often with a remarkably linear taper. Here we use theoretical and experimental methods to analyze interactions of mouse whiskers with objects. When pushed into objects, conical whiskers suddenly slip at a critical angle. In contrast, cylindrical whiskers do not slip for biologically plausible movements. Conical whiskers sweep across objects and textures in characteristic sequences of brief sticks and slips, which provide information about the tactile world. In contrast, cylindrical whiskers stick and remain stuck, even when sweeping across fine textures. Thus the conical whisker structure is adaptive for sensor mobility in constrained environments and in feature extraction during active haptic exploration of objects and surfaces. DOI: http://dx.doi.org/10.7554/eLife.01350.001 PMID:24252879

  10. Polarization independent broadband metamaterial absorber based on tapered helical structure

    NASA Astrophysics Data System (ADS)

    Agarwal, Sajal; Prajapati, Y. K.; Singh, V.; Saini, J. P.

    2015-12-01

    This communication presents a tapered helical structure as absorber, made of unconventional material i.e. metamaterial. Modeling, analytical study and the optimization of the absorber have been done. Quad helical optimized structure gives almost unity absorption at 499 nm wavelength and gives the absorption more than 75% from 300 nm to 1650 nm which is a very wide operating region with, average absorbance of 91.32%. Whereas, triple helical structure gives 85% average absorbance with the operating range from 300 nm to 1350 nm. Also, it is analyzed that the presented structures are polarization independent and broadband. Comparison of the proposed quad helical absorber with the existing metamaterial absorbers is done and found it is most eligible.

  11. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

    PubMed Central

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-01-01

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering. PMID:27999245

  12. Fabrication of internally tapered capillaries for capillary electrochromatography electrospray ionization mass spectrometry.

    PubMed

    Zheng, Jack; Norton, Dean; Shamsi, Shahab A

    2006-02-15

    In this study, we report a novel procedure for fabricating internally tapered capillary columns suitable for the coupling of capillary electrochromatography (CEC) to electrospray mass spectrometry (ESI-MS). The internal tapers were prepared by slowly heating the capillary end in a methane/O2 flame. Due to continuous self-shrinking of the inner channel of the capillary, the inside diameter of the opening was reduced to 7-10 microm. The procedure is easy to handle, with no requirement for expensive equipment as well as elimination of problematic grinding of the tip. Several advantages of these new internal tapers, as compared to using externally tapered columns, are described. First, the problems of poor durability and tip breakage associated with external tapering were successfully overcome with the internal taper. A comparison of the online CEC/ESI-MS between external versus internal tapers showed that the latter provides enhanced electrospray stability, resulting in significantly lower short-term noise and very short-term noise values. In turn, the more rugged design of internal tapers allows performing CEC/MS utilizing a harsh polar organic mobile phase, which was not previously successful using an external taper due to higher operating current and electrospray arcing. Next, data on the reproducibility of the internally tapered CEC/MS column using warfarin and beta-blockers as model analytes are presented. For example, when comparing the reproducibility for separation of warfarin under reversed-phase conditions, the internal taper demonstrated superior intraday % RSD (1.6-3.4) as compared to the external taper intraday % RSD (5-6). Last, the applicability of performing quantitative CEC/MS with internally tapered capillaries is demonstrated for simultaneous enantioseparation of beta-blockers. Impressive quantitative results include good linearity of calibration curves (e.g., R2 = 0.9940-0.9988) and limit of detection as low as 30 nM. The sensitive detection of a

  13. Model-based polishing of meter size optics

    NASA Astrophysics Data System (ADS)

    Kupfer, Jan-Claas; Achtsnick, Marcel; Becker, Elisabeth

    2013-09-01

    In display or semiconductor manufacturing it is a constant drive towards the use of scale effects to reduce costs per unit. For equipment suppliers this leads to ever bigger optical components. To answer this need new cost-efficient technologies are required. In the process chain, the polishing step is one of the most important as it defines the optical surface. In this work the polishing step of a planar surface of a cylindrical component is investigated. A simulation for long scanning optics starting from Preston equation has been derived. By separating the optical surface into several zones, velocity variable polishing paths have been computed. Including pressure differences at the edges so called removal maps have been plotted. At the end, it has been verified that the model approach is able to influence polishing results of meter size optics by velocity controlled polishing.

  14. The invisible community: undocumented Polish workers in Athens.

    PubMed

    Romaniszyn, K

    1996-04-01

    "This article describes the development of an economic migration from Poland to Greece and the creation of a migrant community in Athens. It presents the development of a new migration route by political immigrants. It then describes how the Polish political emigrants heading for Greece in the mid-1980s established the pillar institutions which were inherited by the Polish undocumented workers who have followed, and which have served the latter well. The article proceeds to highlight the work milieu of the Polish undocumented workers in Athens, and discusses the role played by the ¿Polish church', i.e., the Roman Catholic church to which Poles were given access. It concludes by considering the future prospects of this migration and of the Polish migrant community in Greece."

  15. Pad polishing for rapid production of large flats

    SciTech Connect

    Berggren, R.R.; Schmell, R.A.

    1997-11-01

    Pad polishing is an efficient technique for polishing-out a ground surface and reaching a figure better than one wave, ready for completion with less than an hour on a planetary polisher. For the 350 mm square piece of BK-7, removal was one micrometer every 10 minutes. Polishing-out from a 5 micrometer grind took less than 3 hours, to a surface smoothness of one nm rms. Other tests verified that the pad leaves no unusual subsurface damage. Following completion on a pitch planetary polisher, surface finish is the same as obtained for conventional processing. Unlike pitch, the pad retains its surface figure, producing a uniform result when used on a production basis. Coupled with the speed of production and low capital cost of overarm machines, it provides a cost-effective approach.

  16. Graphene-based side-polished optical fiber amplifier.

    PubMed

    Karimi, Mohammad; Ahmadi, Vahid; Ghezelsefloo, Masoud

    2016-12-20

    We demonstrate a novel design for optical fiber amplifiers, utilizing side-polished fibers with a single-layer graphene overlay as the active medium and carrier injection in the graphene layer to provide the required inversion. We study the effects of an electrically induced graphene p-i-n heterojunction in the forward bias regime on optical modes of side-polished fibers and show that gain values of 0.51, 1.81, and 1.79 dB/cm for wavelengths 1064, 1330, and 1550 nm can be obtained for single-mode side-polished fibers. Our results show that in multi-mode side-polished fibers, higher order modes experience higher values of gain, and gain can be increased by increasing polished depth. The proposed system is a tunable wideband optical amplifier that can operate for wavelengths larger than 1000 nm.

  17. Polish device for FOCCoS/PFS slit system

    NASA Astrophysics Data System (ADS)

    de Oliveira, Antonio Cesar; de Oliveira, Ligia Souza; de Arruda, Marcio V.; Souza Marrara, Lucas; dos Santos, Leandro Henrique; Ferreira, Décio; dos Santos, Jesulino Bispo; de Paiva Vilaça, Rodrigo; Rosa, Josimar Aparecido; Sodré Junior, Laerte; de Oliveira, Claudia Mendes

    2014-07-01

    The Fiber Optical Cable and Connector System, "FOCCoS", for the Prime Focus Spectrograph, "PFS", is responsible for transporting light from the Subaru Telescope focal plane to a set of four spectrographs. Each spectrograph will be fed by a convex curved slit with 616 optical fibers organized in a linear arrangement. The slit frontal surface is covered with a special dark composite, made with refractory oxide, which is able to sustain its properties with minimum quantities of abrasives during the polishing process; this stability is obtained This stability is obtained by the detachment of the refractory oxide nanoparticles, which then gently reinforce gently the polishing process and increase its the efficiency. The surface roughness measured in several samples after high performance polishing was about 0.01 microns. Furthermore, the time for obtaining a polished surface with this quality is about 10 times less than the time required for polishing a brass, glass or ceramic surface of the same size. In this paper, we describe the procedure developed for high quality polishing of this type of slit. The cylindrical polishing described here, uses cylindrical concave metal bases on which glass paper is based. The polishing process consists to use grid sequences of 30μm, 12μm, 9μm, 5μm, 3μm, 1μm and, finally, a colloidal silica on a chemical cloth. To obtain the maximum throughput, the surface of the fibers should be polished in such a way that they are optically flat and free from scratches. The optical fibers are inspected with a microscope at all stages of the polishing process to ensure high quality. The efficiency of the process may be improved by using a cylindrical concave composite base as a substrate suitable for diamond liquid solutions. Despite this process being completely by hand, the final result shows a very high quality.

  18. Implication of femoral stem on performance of articular surface replacement (ASR) XL total hip arthroplasty.

    PubMed

    Cip, Johannes; von Strempel, Archibald; Bach, Christian; Luegmair, Matthias; Benesch, Thomas; Martin, Arno

    2014-11-01

    Taper junctions of large diameter metal-on-metal femoral heads and femoral stems were described as metal ion generator due to accelerated wear and corrosion. However, literature about the Articular Surface Replacement (ASR) total hip arthroplasty (THA) invariably deals with stems manufactured by DePuy Orthopedics (Warsaw, IN, USA). Nothing is known whether different stems with common 12/14 mm tapers affect failure rate or ion release. 99 ASR THA (88 patients) implanted with CoxaFit or ARGE Geradschaft stems (K-Implant, Hannover, Germany) were retrospectively analyzed. After a mean follow-up of 3.5 years revision rate was 24.5%, mostly due to adverse reaction to metal debris (ARMD). CT scan revealed component loosening in 10.3% and pseudotumoral lesions in 12.6%. Elevated ion concentrations (>7 μg/l) were found in 38.6%.

  19. Simple method for manufacturing and optical characterization of tapered optical fibres

    NASA Astrophysics Data System (ADS)

    Zakrzewski, A.; Pięta, A.; Patela, S.

    2016-12-01

    Photonic devices often use light delivered by a single-mode telecommunication fibre. However, as the diameter of the core of the optical fibre is of 10 microns, and the transverse dimensions of the photonic waveguides are usually micrometer or less, there is an issue of incompatibility. The problem may be solved by application of tapered optical fibres. For efficient light coupling, the taper should be prepared so as to create a beam of long focal length and small spot diameter in the focus. The article describes the design, fabrication and characterization of tapered optical fibres prepared with a fibre-optic fusion splicer. We modelled the tapers with FDTD method, for estimation of the influence of the tapered length and angle on the spot diameter and the focal length of an outgoing beam. We fabricated tapers from a standard single mode fibre by the Ericsson 995 PMfi- bre-optic fusion splicer. We planned the splicing technology so as to get the needed features of the beam. We planned a multistep fusion process, with optimized fusion current and fusion time. The experimental measurements of best tapered optical fibres were carried out by the knife-edge method.

  20. Inferring the spatial variation of the wedge strength based on a modified critical taper model

    NASA Astrophysics Data System (ADS)

    Yang, C.; Liu, H.; Hsieh, Y.; Dong, J.

    2013-12-01

    Critical taper wedge theory has been widely applied to evaluate the strength of the detachment fault and the wedge by measuring taper angle. Traditional taper model, which incorporated constant cohesion and friction angle, fails to explain the lateral variation of the taper angle. A modified critical taper model adopting nonlinear Hoek-Brown failure criterion is proposed accordingly. The fold-and-thrust belt of central Taiwan was studied. Based on the field works and laboratory tests, the geological strength index (GSI) and the uniaxial compressive strength were obtained and the wedge strength can be estimated accordingly. The GSI values from investigation are decreased from the west to the east along the cross section due to the wedge strength heterogeneity. The uniaxial compressive strength of intact rock varies from the age of formation and lithology. The estimated wedge strength exhibits a strong spatial variation. The strength of the detachment fault was derived from rotary shear tests using fault gouge materials under different velocities and normal stresses. General speaking, the steady-state friction coefficient are about 0.29-0.46 when the shear velocity less than 0.1 m/s. The friction coefficient is not sensitive to the normal stress. Consequently, the lateral variation of the taper angle, which calculated by modified critical taper model, is mainly dominated by the wedge strength heterogeneity and the thickening of the wedge from the west to the east.

  1. Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

    SciTech Connect

    Schaub, S. C.; Shapiro, M. A.; Temkin, R. J.

    2015-08-16

    In this paper, simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a1taper is 3.198a1a2/λ. Here, λ is the wavelength of radiation. The fractional loss of the HE 11 mode in an optimized taper is 0.0293(a2-a1)4/a$2\\atop{1}$1a$2\\atop{2}$. These formulae are accurate when a2≲2a1. Slightly more complex formulae, accurate for a2≤4a1, are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a2≤2.12a1 and less than 0.1 % when a2≤1.53a1. The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Finally, parabolic tapers may provide lower loss, but linear tapers with moderate values of a2/a1 may be attractive because of their simplicity of fabrication.

  2. Polished Downhole Transducer Having Improved Signal Coupling

    DOEpatents

    Hall, David R.; Fox, Joe

    2006-03-28

    Apparatus and methods to improve signal coupling in downhole inductive transmission elements to reduce the dispersion of magnetic energy at the tool joints and to provide consistent impedance and contact between transmission elements located along the drill string. A transmission element for transmitting information between downhole tools is disclosed in one embodiment of the invention as including an annular core constructed of a magnetically conductive material. The annular core forms an open channel around its circumference and is configured to form a closed channel by mating with a corresponding annular core along an annular mating surface. The mating surface is polished to provide improved magnetic coupling with the corresponding annular core. An annular conductor is disposed within the open channel.

  3. Edge effect in fluid jet polishing.

    PubMed

    Guo, Peiji; Fang, Hui; Yu, Jingchi

    2006-09-10

    The edge effect is one of the most important subjects in optical manufacturing. The removal function at different positions of the sample in the process of fluid jet polishing (FJP) is investigated in the experiments. Furthermore, by using finite-element analysis (FEA), the distributions for velocity and pressure of slurry jets are simulated. Experimental results demonstrate that the removal function has a ring-shaped profile, except for a little change in the size at the operated area even if the nozzle extends beyond the edge of the sample. FEA simulations reveal a similar distribution of velocity with a cavity resulting in the ring-shaped profile of material removal at different impact positions. To a certain extent, therefore, the removal function at the edge of the surface of the sample appears similar to that inside of it, so that the classical edge effect can be neglected in FJP.

  4. astronomia.pl: Polish Astronomy Portal

    NASA Astrophysics Data System (ADS)

    Czart, K.

    2005-12-01

    Astronomia.pl is an educational internet service for students, teachers and all astronomy amateurs. It is the biggest and the most popular astronomical portal in Poland. Our main address is www.astronomia.pl, but we created additional services: Copernicus - biographies of famous astronomers (www.kopernik.pl), AstroWWW - a collection of interesting webpages created by amateur astronomers (www.astrowww. pl), AstroSHOP - an on-line shop (www.astronomia.com.pl), Planetarium - website about Polish planetaria (www.planetarium.pl). An English version of the portal is available at www.astronomia.pl/english. In this article we give a short introduction to many of the portal's projects.

  5. Fluid jet polishing: removal process analysis

    NASA Astrophysics Data System (ADS)

    Faehnle, Oliver W.; van Brug, Hedser H.

    1999-09-01

    This paper reports on a new finishing process, Fluid Jet Polishing (FJP), that resembles the kinetic process employed in ASJ systems in that it is guiding a pre-mixed slurry to the surface, but within FJP low pressures are applied. Since FJP employs a fluid for machining, no tool wear occurs and the tool is cooling and removing debris in process. Using slurry that contained water with grinding abrasives, the FJP finishing process has been demonstrated. On flat glass samples, the surface roughness of a previously ground surface has been reduced from 475 nm rms to 5 nm rms and a prepolished surface has been shaped without increasing its roughness of 1.6 nm rms. Experiments are described showing that the final surface roughness depends on slurry characteristics and that the material removal spot can be adjusted by varying process parameters, e.g. the angle of the incident ray.

  6. Characterization of polished surfaces by ``Makyoh''

    NASA Astrophysics Data System (ADS)

    Kugimiya, K.

    1990-06-01

    Characterization by "Makyoh", the magic mirror metho, has been proven to be very effective in detecting various flaws on mirror surfaces and also in controling mirror fabrication processes: state-of-the-art processes. Makyoh, a many-centuries-old simple concept, offers a very simple and non-destructive surface analyzing method which transforms latent damages, scratches, waviness and other flaws on mirror-like surfaces into visual images. It has a sensitivity of picking up undulations of an order of a few nm over a half mm span and is the most suitable method to characterize highly finished mirror-like surfaces with the extreme perfection of large areas, i.e. mirror-polished Si wafers for ULSI, hard discs, liquid crystal display glasses and other substrates. The Makyoh method has replaced the laborious and unstable naked-eye wafer inspection lines. It has also been proved to be effective in monitoring wafer processes like thermal and epitaxial processes.

  7. Latest developments in Polish Fireball Network

    NASA Astrophysics Data System (ADS)

    Wiśniewski, M.; Żołądek, P.

    2015-01-01

    The Polish Fireball Network started in March 2004. Most of its observers are amateurs, members of the Comets and Meteors Workshop. The network consists of 40 continuously working stations, where nearly 70 sensitive CCTV video and digital cameras operate. The new cameras for digital meteor spectroscopy were tested. We use technology of crossed grids to have better chances to register a meteor spectrum. A resolution of 8 A/pixel + 5.5 A/pixel was achieved. For the meteor patrol we have chosen the DMK 23GX236 with a chip resolution of 1920x1200 pixels. Two new cameras will be able to cover almost the whole sky with a resolution 4'/pixel.

  8. Simulation on friction taper plug welding of AA6063-20Gr metal matrix composite

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Nithin, Abeyram M.

    2016-05-01

    Friction taper plug welding a variant of friction welding is useful in welding of similar and dissimilar materials. It could be used for joining of composites to metals in sophisticated aerospace applications. In the present work numerical simulation of friction taper plug welding process is carried out using finite element based software. Graphite reinforced AA6063 is modelled using the software ANSYS 15.0 and temperature distribution is predicted. Effect of friction time on temperature distribution is numerically investigated. When the friction time is increased to 30 seconds, the tapered part of plug gets detached and fills the hole in the AA6063 plate perfectly.

  9. Efficiency enhancement of anomalous-Doppler electron cyclotron masers with tapered magnetic field

    SciTech Connect

    Xie, Chao-Ran; Hou, Zhi-Ling; Kong, Ling-Bao E-mail: pkliu@pku.edu.cn; Liu, Pu-Kun E-mail: pkliu@pku.edu.cn; Du, Chao-Hai; Jin, Hai-Bo

    2014-02-15

    The efficiency of slow-wave electron cyclotron masers (ECM) is usually low, thus limiting the practical applications. Here, a method of tapered magnetic field is introduced for the efficiency enhancement of the slow-wave ECM. The numerical calculations show that the tapered magnetic-field method can enhance the efficiency of slow-wave ECM significantly. The effect of beam electron velocity spread on the efficiency has also been studied. Although the velocity spread reduces the efficiency, a great enhancement of efficiency can still be obtained by the tapered magnetic field method.

  10. Analytical Solution of a Tapering Cable Equation for Dendrites and Conformal Symmetry

    NASA Astrophysics Data System (ADS)

    Romero, Juan M.; Trenado, Carlos

    2015-09-01

    Progress towards detailed characterization of structural and biophysical properties of dendrites emphasizes the importance of finding analytical solutions for more realistic dendrite models with circular cross-section and varying diameter. In this regard, we employ symmetry methods and the passive cable theory to deduce a generalized analytical solution for electric propagation in a family of tapering dendrites. In particular, we study the effect of such tapering geometries on the obtained electric voltage. Simulations using the deduced analytical solution indicate that for a subfamily of tapering profiles neural integration is better than in the stereotypical profile given by a cylinder.

  11. Calculation of the aerodynamic characteristics of tapered wings with partial-span flaps

    NASA Technical Reports Server (NTRS)

    Person, Henry A; Anderson, Raymond F

    1939-01-01

    Factors derived from wing theory are presented. By means of these factors, the angle of zero lift, the lift-curve slope, the pitching moment, the aerodynamic-center position, and the induced drag of tapered wings with partial-span flaps may be calculated. The factors are given for wings of aspect ratios 6 and 10 , of taper ratios from 0.25 to 1.00, and with flaps of various length. An example is presented of the method of application of the factors. Fair agreement with experimental results is shown for two wings of different taper ratio having plain flaps of various spacing.

  12. Fusion splice between tapered inhibited coupling hypocycloid-core Kagome fiber and SMF.

    PubMed

    Zheng, Ximeng; Debord, Benoît; Vincetti, Luca; Beaudou, Benoît; Gérôme, Frédéric; Benabid, Fetah

    2016-06-27

    We report for the first time on tapering inhibited coupling (IC) hypocycloid-core shape Kagome hollow-core photonic crystal fibers whilst maintaining their delicate core-contour negative curvature with a down-ratio as large as 2.4. The transmission loss of down-tapered sections reaches a figure as low as 0.07 dB at 1550 nm. The tapered IC fibers are also spliced to standard SMF with a total insertion loss of 0.48 dB. These results show that all-fiber photonic microcells with the ultra-low loss hypocycloid core-contour Kagome fibers is now possible.

  13. [POLISH EXPEDITION TO SPITSBERGEN IN 1934].

    PubMed

    Köhler, Piotr

    2015-01-01

    Polish expedition to Spitsbergen in 1934 was already the second Polish polar expedition to the Arctic. It was scientific-mountaineering in character. 7 persons took part in it: Witold Biernawski (1898-1957)--film-maker and radiotelegraph operator, Stefan Bernadzikiewicz (1907-1939)--expedition leader, Henryk Mogilnicki (1906-1999)--photographer and radiotelegraph operator, Stefan Zbigniew Różycki (1906-1988)--geologist, Stanisław Siedlecki (1912-2002)--meteorological observer, Sylweriusz Bohdan Zagrajski (1892-1940)--triangulator, Antoni Rogal-Zawadzki (1896-1974)--topographer and photogrammetrist. The purpose of this expedition was to collect data in geology and cartography, and to a lesser degree--in glaciology, botany, zoology and meteorology. It lasted from May 20 to September 16, 1934. The time between June 20 - August 28 the group spent on Spitsbergen's Torell Land. The outcome: an area of app. 300 square kilometres of previously undiscovered land was marked by triangular system, covered by photogrammetric photos and surveyed. Geological research covered the land of app. 500 square kilometres and the group collected geological specimens of app. 800 kg in weight. On the basis of their research, two maps (at a scale of 1:50 000 and 1:200 000) were published. The participants collected also botanical and zoological material. Meteorological observations were carried out at the base over Van Keulen fjord throughout the whole expedition. Different objects on Torell Land were named by the expedition, their names referring largely to Poland (Annex I). Approximately 200 photographs and a film were shot by the expedition. Apart from scientific research, the participants published also diaries of the expedition.

  14. Patient's autonomy of will in Polish law.

    PubMed

    Swiderska, Małgorzata

    2012-09-01

    A principle of Polish legislation is that the evidence of legality for any medical intervention is the patient's consent. The issue is directly referred to by both the Patient's Rights Act from 2008 and the Medical Profession Act from 1996. The patient's consent may be given after obtaining reliable, accessible and thorough information about all stages of medical intervention: diagnosis, therapy prospects or rehabilitation. The extent of information about the potential risk of medical treatment should include the typically foreseeable results, which usually brings the matter down to typical risk. However, there are interventions, which bear greater risk, and even though it can't be considered typical, it should also be mentioned, despite the fact that the postulate of tactfulness should be respected here. The burden of proof that appropriate information has been given lies upon the doctor. Thus default consent, especially one given on being admitted to hospital, to all medical actions isn't valid in legal terms. The role of forms including standard information for giving consent is limited. Polish law doesn't regulate this issue, and other forms of indirect communication are used as auxiliary and cannot replace direct contact between a patient and a doctor. According to the Patient's Rights Act, in case of deliberate breach of those rights, the court can grant the aggrieved party with an appropriate sum as financial compensation for the harm sustained or an appropriate sum of money for the charity chosen by the aggrieved party. It is a legal basis for claiming compensation for non-material harm in case of a breach of the patient's right to give consent. It is possible both in case of liability in tort, as well as contractual claims.

  15. Droughts in historical times in Polish territory

    NASA Astrophysics Data System (ADS)

    Limanowka, Danuta; Cebulak, Elzbieta; Pyrc, Robert; Doktor, Radoslaw

    2015-04-01

    Climate change is one of the key environmental, social and economical issues, and it is also followed by political consequences. Impact of climate conditions on countries' economy is increasingly recognized, and a lot of attention is given, both in the global scale and by the individual national governments. In years 2008-2010, at the Poland -Institute of Meteorology and Water Management-National Research Institute was realized the KLIMAT Project on Impact of climate change on environment, economy and society (changes, effects and methods of reducing them, conclusions for science, engineering practice and economic planning) No. POIG01-03-01-14-011/08. The project was financed by the European Union and Polish state budget in frame of Innovative Economy Operational Programme. A very wide range of research was carried out in the different thematic areas. One of them was "Natural disasters and internal safety of the country (civil and economical)." The problem of drought in Poland was developed in terms of meteorology and hydrology. "Proxy" Data Descriptions very often inform about dry years and seasons, hot periods without precipitation. Analysis of historical material allowed to extract the years that have experienced prolonged periods of high temperatures and rainfall shortages. Weather phenomenon defined as drought belongs to extreme events. This information was very helpful in the process of indexing and thus to restore the course and intensity of climatic elements in the past. The analysis covered the period from year 1000 to modern times. Due to the limited information from the period of 1000-1500 the authors focused primarily on the period from 1500 to 2010. Analysis of the collected material has allowed the development of a highly precise temporal structure of the possible occurrence of dry periods to Polish territory.

  16. Excessive distal migration of fiber-mesh coated femoral stems

    PubMed Central

    2011-01-01

    Background The surface texture, localization, and magnitude of the surface material applied to the femoral stem can facilitate bone ingrowth and influence the survival of total hip arthroplasties. Clinical and radiographic studies have shown superior bone ingrowth in proximally porous-coated stems with a diaphyseal grit-blasted surface in comparison to a smooth diaphyseal surface. Surface textures—especially porous surface material—have been suggested to have a sealing effect against migration of polyethylene debris along the implant-bone interface and to reduce the inflammatory response, leading to a prolonged implant survival. Patients and methods Between 2004 and 2006, we conducted a randomized, controlled trial (RCT) involving 50 patients with non-inflammatory arthritis. They received either a distally tapered, extended coated stem or a straight, proximally coated stem. During surgery, tantalum markers were inserted into the greater and lesser trochanter. Implant migration was evaluated at 3, 12, and 24 months postoperatively by radiostereometric analysis. The primary endpoint was stem migration 2 years after surgery. Results All femoral components in both groups showed pronounced distal translation, with the highest rate of translation occurring between 0 and 3 months. After 2 years, the mean distal translation was 2.67 (95% CI: –3.93 to –1.42) mm for the tapered, extended coated stem and 1.80 (–2.45 to –1.15) mm for the straight, proximally coated stem. Half of the tapered, extended coated stems and two-thirds of the straight, proximally coated stems had migrated more than 1 mm. No difference between the 2 stems could be seen with regard to translation or rotation at any time point. After 2 years, 2 hips have been reoperated due to mechanical loosening of the stem. Interpretation An excessive amount of migration of both stem types was seen 2 years postoperatively. It is of vital importance to follow this patient cohort since radiostereometric

  17. [Fifty years of cooperation--FEBS and Polish Biochemical Society].

    PubMed

    Barańska, Jolanta

    2014-01-01

    This year, the Federation of European Biochemical Societies (FEBS) celebrates its 50th anniversary. The Polish Biochemical Society, represented by the Society's President, Kazimierz Zakrzewski, was a founding member of the organization. The text presents a history of collaboration between FEBS and Polish Biochemical Society, the participation of Polish Biochemical Society members in different FEBS activities, as well as the role they played in running the Federation. Author describes FEBS Congresses which taken place in Warsaw, the first 3rd FEBS Meeting in 1966 and then 29th Congress in 2004. The profiles of Jakub Karol Parnas, the founding father of the Polish biochemistry and some crucial Presidents of the Society, are also presented. The text describes Parnas Conferences, organized jointly by Polish and Ukrainian Biochemical Societies from 1996, and growing from 2011 into three-nation event with participation of Ukrainian, Israeli and Polish scientists, largely due to significant help from FEBS. Summarizing the last few years, author judge the cooperation between the Federation and the Polish Biochemical Society as optimal.

  18. Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing

    SciTech Connect

    Suratwala, T I; Steele, R; Feit, M D; Wong, L; Miller, P E; Menapace, J A; Davis, P J

    2007-05-02

    The distribution and characteristics of surface cracks (i.e., sub-surface damage or scratching) on fused silica formed during grinding/polishing resulting from the addition of rogue particles in the base slurry has been investigated. Fused silica samples (10 cm diameter x 1 cm thick) were: (1) ground by loose abrasive grinding (alumina particles 9-30 {micro}m) on a glass lap with the addition of larger alumina particles at various concentrations with mean sizes ranging from 15-30 {micro}m, or (2) polished (using 0.5 {micro}m cerium oxide slurry) on various laps (polyurethanes pads or pitch) with the addition of larger rogue particles (diamond (4-45 {micro}m), pitch, dust, or dried Ceria slurry agglomerates) at various concentrations. For the resulting ground samples, the crack distributions of the as-prepared surfaces were determined using a polished taper technique. The crack depth was observed to: (1) increase at small concentrations (>10{sup -4} fraction) of rogue particles; and (2) increase with rogue particle concentration to crack depths consistent with that observed when grinding with particles the size of the rogue particles alone. For the polished samples, which were subsequently etched in HF:NH{sub 4}F to expose the surface damage, the resulting scratch properties (type, number density, width, and length) were characterized. The number density of scratches increased exponentially with the size of the rogue diamond at a fixed rogue diamond concentration suggesting that larger particles are more likely to lead to scratching. The length of the scratch was found to increase with rogue particle size, increase with lap viscosity, and decrease with applied load. At high diamond concentrations, the type of scratch transitioned from brittle to ductile and the length of the scratches dramatically increased and extended to the edge of the optic. The observed trends can explained semi-quantitatively in terms of the time needed for a rogue particle to penetrate into a

  19. Electro-Chemically Enhanced Mechanical Polishing of Nickel Mandrels

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian; Engelhaupt, Darell

    2006-01-01

    Grinding and mechanical polishing techniques used for x-ray optics mandrel figuring lead to mid-frequency surface ripple. These small figure variations have to be addressed in order to improve the performance of the resulting x-ray mirrors. If the electrochemical etching is combined with mechanical polishing, the figuring and the surface finishing cm be done simultaneously and be used to correct the mid-frequency surface ripple. It is shown that the electrochemical mechanical polishing method allows selective removal of nickel alloy without mandrel surface microroughness degradation.

  20. Temporal stability and performance of MR polishing fluid

    NASA Astrophysics Data System (ADS)

    Schinhaerl, Markus; Pitschke, Elmar G.; Rascher, Rolf; Sperber, Peter; Stamp, Richard; Smith, Lyndon N.; Smith, Gordon

    2004-10-01

    The lifetime of standard magnetorheological (MR) polishing fluids, used for example in polishing machines for optical applications, is limited. Scanning electron microscope examinations as well as chemical analyses of the fluid had been undertaken in order to investigate reasons for limited lifetime. We found out that the removal rate decreases during the course of time. However, the usable fluid life is most limited by the point of time when the critical minimum amount of fluid, necessary to ensure circulation, is reached. The results in association with a new fluid conditioner show, that a standard MR polishing fluid may be used for longer periods than common periods of about 2 weeks.

  1. Reel-to-reel substrate tape polishing system

    DOEpatents

    Selvamanickam, Venkat; Gardner, Michael T.; Judd, Raymond D.; Weloth, Martin; Qiao, Yunfei

    2005-06-21

    Disclosed is a reel-to-reel single-pass mechanical polishing system (100) suitable for polishing long lengths of metal substrate tape (124) used in the manufacture of high-temperature superconductor (HTS) coated tape, including multiple instantiations of a polishing station (114) in combination with a subsequent rinsing station (116) arranged along the axis of the metal substrate tape (124) that is translating between a payout spool (110a) and a take-up spool (110b). The metal substrate tape obtains a surface smoothness that is suitable for the subsequent deposition of a buffer layer.

  2. Hydraulic supports for polishing TMT M3MP

    NASA Astrophysics Data System (ADS)

    Hu, Haifei; Qi, Erhui; Cole, Glen; Hu, Haixiang; Luo, Xiao; Ford, Virginia; Zhang, Xuejun

    2016-10-01

    For polishing the ultra-thin TMT M3MP, a polishing support system with 18 hydraulic supports (HS) is introduced. This work focuses on the designing and testing of these HSs. Firstly the design concept of HS system is discussed; then mechanical implementation of the HS structure is carried out, with special consideration of fluid cycling, work pressurization and the weight component. Afterward the piping installation and the de-gas process for the working fluid are implemented. Pressurization and stiffness are well checked before system integration for the single HS unit. Finally the support system is integrated for the polishing process.

  3. Types of Stem Cells

    MedlinePlus

    ... Stem Cell Glossary Search Toggle Nav Types of Stem Cells Stem cells are the foundation from which all ... Learn About Stem Cells > Types of Stem Cells Stem cells Stem cells are the foundation for every organ ...

  4. Vertically-tapered optical waveguide and optical spot transformer formed therefrom

    DOEpatents

    Bakke, Thor; Sullivan, Charles T.

    2004-07-27

    An optical waveguide is disclosed in which a section of the waveguide core is vertically tapered during formation by spin coating by controlling the width of an underlying mesa structure. The optical waveguide can be formed from spin-coatable materials such as polymers, sol-gels and spin-on glasses. The vertically-tapered waveguide section can be used to provide a vertical expansion of an optical mode of light within the optical waveguide. A laterally-tapered section can be added adjacent to the vertically-tapered section to provide for a lateral expansion of the optical mode, thereby forming an optical spot-size transformer for efficient coupling of light between the optical waveguide and a single-mode optical fiber. Such a spot-size transformer can also be added to a III-V semiconductor device by post processing.

  5. Physiological changes associated with the pre-event taper in athletes.

    PubMed

    Mujika, Iñigo; Padilla, Sabino; Pyne, David; Busso, Thierry

    2004-01-01

    Some of the physiological changes associated with the taper and their relationship with athletic performance are now known. Since the 1980s a number of studies have examined various physiological responses associated with the cardiorespiratory, metabolic, hormonal, neuromuscular and immunological systems during the pre-event taper across a number of sports. Changes in the cardiorespiratory system may include an increase in maximal oxygen uptake, but this is not a necessary prerequisite for taper-induced gains in performance. Oxygen uptake at a given submaximal exercise intensity can decrease during the taper, but this response is more likely to occur in less-skilled athletes. Resting, maximal and submaximal heart rates do not change, unless athletes show clear signs of overreaching before the taper. Blood pressure, cardiac dimensions and ventilatory function are generally stable, but submaximal ventilation may decrease. Possible haematological changes include increased blood and red cell volume, haemoglobin, haematocrit, reticulocytes and haptoglobin, and decreased red cell distribution width. These changes in the taper suggest a positive balance between haemolysis and erythropoiesis, likely to contribute to performance gains. Metabolic changes during the taper include: a reduced daily energy expenditure; slightly reduced or stable respiratory exchange ratio; increased peak blood lactate concentration; and decreased or unchanged blood lactate at submaximal intensities. Blood ammonia concentrations show inconsistent trends, muscle glycogen concentration increases progressively and calcium retention mechanisms seem to be triggered during the taper. Reduced blood creatine kinase concentrations suggest recovery from training stress and muscle damage, but other biochemical markers of training stress and performance capacity are largely unaffected by the taper. Hormonal markers such as testosterone, cortisol, testosterone : cortisol ratio, 24-hour urinary cortisol

  6. High-sensitivity refractive index sensors based on fused tapered photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Fu, Xing-hu; Xie, Hai-yang; Yang, Chuan-qing; Qu, Yu-wei; Zhang, Shun-yang; Fu, Guang-wei; Guo, Xuan; Bi, Wei-hong

    2016-05-01

    In this paper, a novel liquid refractive index (RI) sensor based on fused tapered photonic crystal fiber (PCF) is proposed. It is fabricated by fusing and tapering a section of PCF which is spliced with two single-mode fibers (SMFs). Due to the fused biconical taper method, the sensor becomes longer and thinner, to make the change of the outside RI has more direct effects on the internal optical field of the PCF, which finally enhances the sensitivity of this sensor. Experimental results show that the transmission spectra of the sensor are red-shifted obviously with the increase of RI. The longer the tapered region of the sensor, the higher the sensitivity is. This sensor has the advantages of simple structure, easy fabrication, high performance and so on, so it has potential applications in RI measurement.

  7. Effect of preparation taper and height on strength and retention of zirconia crowns.

    PubMed

    Ersu, Bahadir; Narin, Duygu; Aktas, Guliz; Yuzugullu, Bulem; Canay, Senay

    2012-01-01

    This study aimed to determine the effect of the taper and height of tooth preparations on the fracture strength and retention of zirconia crowns. Sixty-four dies were designed to simulate a crown preparation. Dies were machined with a height of either 4 mm (n = 16) or 7 mm (n = 16) and a taper of either 6 degrees (n = 16) or 20 degrees (n = 16). Copings were created from Lava zirconia blanks. Retention tests were performed using a universal testing machine. Copings were recemented on the dies, thermocycled, and tested for fracture strength. Data were analyzed using factorial analysis of variance. Retention was greater in the taller and less-tapered preparation designs. Taller preparations showed superior fracture strength. Preparing posterior teeth with higher axial walls and less taper is recommended to achieve increased retention and strength for zirconia crowns.

  8. Corrosion on the acetabular liner taper from retrieved modular metal-on-metal total hip replacements.

    PubMed

    Gascoyne, Trevor C; Dyrkacz, Richard M; Turgeon, Thomas R; Burnell, Colin D; Wyss, Urs P; Brandt, Jan-M

    2014-10-01

    Eight retrieved metal-on-metal total hip replacements displayed corrosion damage along the cobalt-chromium alloy liner taper junction with the Ti alloy acetabular shell. Scanning electron microscopy indicated the primary mechanism of corrosion to be grain boundary and associated crevice corrosion, which was likely accelerated through mechanical micromotion and galvanic corrosion resulting from dissimilar alloys. Coordinate measurements revealed up to 4.3mm(3) of the cobalt-chromium alloy taper surface was removed due to corrosion, which is comparable to previous reports of corrosion damage on head-neck tapers. The acetabular liner-shell taper appears to be an additional source of metal corrosion products in modular total hip replacements. Patients with these prostheses should be closely monitored for signs of adverse reaction towards corrosion by-products.

  9. Implementation of rectangular slit-inserted ultra-wideband tapered slot antenna.

    PubMed

    Kim, Sun-Woong; Choi, Dong-You

    2016-01-01

    In this paper, a tapered slot antenna capable of ultra-wideband communication was designed. In the proposed antenna, rectangular slits were inserted to enhance the bandwidth and reduce the area of the antenna. The rectangular slit-inserted tapered slot antenna operated at a bandwidth of 8.45 GHz, and the bandwidth improved upon the basic tapered slot antenna by 4.72 GHz. The radiation pattern of the antenna was suitable for location recognition in a certain direction owing to an appropriate 3 dB beam width. The antenna gain was analyzed within the proposed bandwidth, and the highest gain characteristic at 7.55 dBi was exhibited at a 5-GHz band. The simulation and measurement results of the proposed tapered slot antenna were similar.

  10. Power coupling in multicore optical fiber tapers utilizing out-cladding ferrofluids

    NASA Astrophysics Data System (ADS)

    Tagoudi, Eirini; Milenko, Karolina; Pissadakis, Stavros

    2016-04-01

    Herein we present the experimental implementation of a power coupling device that combines the technology of tapered, multicore microstructured optical fibres (MOFs) with ferrofluidic overlayers. Power coupling between different cores of a tapered, multicore MOF is demonstrated, utilizing magneto-refraction effects induced by magnetic field stimulus into a ferrofluidic outcladding surrounding of the multicore optical fibre taper. By tapering the multicore all-solid MOF to a specific diameter, the excitation of all the adjacent cores through the central one is achieved. Transmission spectra measurements of the individual cores proved that light coupling between fiber cores can be manipulated by magnetic field stimulus. We anticipate that such a type of magneto-tunable power-coupling photonic device can find applications in optical magnetometry, imaging and optical communications.

  11. Comparison of the fracture resistance of dental implants with different abutment taper angles.

    PubMed

    Wang, Kun; Geng, Jianping; Jones, David; Xu, Wei

    2016-06-01

    To investigate the effects of abutment taper angles on the fracture strength of dental implants with TIS (taper integrated screwed-in) connection. Thirty prototype cylindrical titanium alloy 5.0mm-diameter dental implants with different TIS-connection designs were divided into six groups and tested for their fracture strength, using a universal testing machine. These groups consisted of combinations of 3.5 and 4.0 mm abutment diameter, each with taper angles of 6°, 8° or 10°. 3-Dimensional finite element analysis (FEA) was also used to analyze stress states at implant-abutment connection areas. In general, the mechanical tests found an increasing trend of implant fracture forces as the taper angle enlarged. When the abutment diameter was 3.5 mm, the mean fracture forces for 8° and 10° taper groups were 1638.9 N ± 20.3 and 1577.1 N ± 103.2, respectively, both larger than that for the 6° taper group of 1475.0 N ± 24.4, with the largest increasing rate of 11.1%. Furthermore, the difference between 8° and 6° taper groups was significant, based on Tamhane's multiple comparison test (P<0.05). In 4.0 mm-diameter abutment groups, as the taper angle was enlarged from 6° to 8° and 10°, the mean fracture value was increased from 1066.7 N ± 56.1 to 1241.4 N ± 6.4 and 1419.3 N ± 20.0, with the largest increasing rate of 33.1%, and the differences among the three groups were significant (P<0.05). The FEA results showed that stress values varied in implants with different abutment taper angles and supported the findings of the static tests. In conclusion, increases of the abutment taper angle could significantly increase implant fracture resistance in most cases established in the study, which is due to the increased implant wall thickness in the connection part resulting from the taper angle enlargement. The increasing effects were notable when a thin implant wall was present to accommodate wide abutments.

  12. Hormonal responses to training and its tapering off in competitive swimmers: relationships with performance.

    PubMed

    Mujika, I; Chatard, J C; Padilla, S; Guezennec, C Y; Geyssant, A

    1996-01-01

    During a winter training season, the effects of 12 weeks of intense training and 4 weeks of tapering off (taper) on plasma hormone concentrations and competition performance were investigated in a group of highly trained swimmers (n = 8). Blood samples were collected and the swimmers performed their speciality in competition at weeks 10 (mid-season), 22 (pre-taper) and 26 (post-taper). No statistically significant changes were observed in the concentrations of total testosterone (TT), non-sex hormone binding globulin-bound-testosterone (NSBT), cortisol (C), luteinising hormone, thyroid stimulating hormone, triiodothyronine, thyroxine plasma catecholamines, creatine kinase and ammonia during training and taper. Mid-season NSBT: C ratio and the amount of training were statistically related (r = 0.82, P < 0.05). Competition performance slightly declined during intense training [0.52 (SD 2.51)%, NS] and improved during taper [2.32 (SD 1.69)%, P < 0.01]. Changes in performance during training and taper correlated with changes in ratios TT: C (r = 0.86, P < 0.01 and r = 0.81, P < 0.05, respectively) and NSBT: C (r = 0.77, P < 0.05 and r = 0.76, P < 0.05, respectively). In summary, these results showed that the monitored plasma hormones and metabolic indices were unaltered by 12 weeks of intense training and 4 weeks of taper. The TT: C and NSBT: C ratios, however, appeared to be effective markers of the swimmers' performance capacities throughout the training season.

  13. WGM-Resonator/Tapered-Waveguide White-Light Sensor Optics

    NASA Technical Reports Server (NTRS)

    Stekalov, Dmitry; Maleki, Lute; Matsko, Andrey; Savchenkov, Anatoliy; Iltchenko, Vladimir

    2007-01-01

    Theoretical and experimental investigations have demonstrated the feasibility of compact white-light sensor optics consisting of unitary combinations of (1) low-profile whispering-gallery-mode (WGM) resonators and (2) tapered rod optical waveguides. These sensors are highly wavelength-dispersive and are expected to be especially useful in biochemical applications for measuring absorption spectra of liquids. These sensor optics exploit the properties of a special class of non-diffracting light beams that are denoted Bessel beams because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have large values of angular momentum. In a sensor optic of this type, a low-profile WGM resonator that supports modes having large angular momenta is used to generate high-order Bessel beams. As used here, "low-profile" signifies that the WGM resonator is an integral part of the rod optical waveguide but has a radius slightly different from that of the adjacent part(s).

  14. Compact fiber optic immunosensor using tapered fibers and acoustic enhancement

    NASA Astrophysics Data System (ADS)

    Zhou, Chonghua; Pivarnik, Philip E.; Auger, Steven; Rand, Arthur G.; Letcher, Stephen V.

    1997-06-01

    A compact fiber-optic sensing system that features all-fiber optical design and semiconductor-laser excitation has been developed and tested. A 2X2 fiber coupler directs the input light to the SMA connected sensing fiber tip and the fluorescent signal back to a CCD fiber spectrophotometer. In this system, the fluorescent signal is confined in the fiber system so the signal-to-noise ratio is greatly improved and the system can be operate in ambient light conditions. The utilization of a red laser diode has reduced the background signal of non-essential biomolecules. The fluorescent dye used is Cy5, which has an excitation wavelength of 650 nm and a fluorescent center wavelength of 680 nm. To illustrate the biosensor's diagnostic capabilities, a sandwich immunoassay to detect Salmonella is presented. Tapered fiber tips with different shapes and treatments were studied and optimized. An enhancement system employing ultrasonic concentration of target particles has also been developed and applied to the detection of Salmonella. The immunoassay was conducted in a test chamber that also serves as an ultrasonic standing-wave cell and allows microspheres to be concentrated in a column along the fiber probe. The system demonstrates broad promise in future biomedical application.

  15. Experimental study on the wake behind tapered circular cylinders

    NASA Astrophysics Data System (ADS)

    Visscher, Jan; Pettersen, Bjørnar; Andersson, Helge I.

    2011-11-01

    The flow around tapered cylinders can act as basic models for numerous bluff body flows with a spanwise variation of either the body shape or the inflow conditions. The well-known vortex street is influenced by strong three-dimensional effects from the spanwise variation of the shedding frequency, namely oblique vortex shedding and vortex dislocations. Stereo-PIV was chosen to study these phenomena, since it allows analyzing planes with the full three-component, instantaneous velocity fields and local, time-dependent variations in the same setting. Hence, detailed aspects of the vortex dislocation phenomenon are presented. Single vortex dislocation events are presented through the local variation of the three measured velocity components u, v and w. Longer time-series reveal both period and location of these dislocation events, as well as quantity and sizes of the cells of constant shedding velocity in between them. The influence of the Reynolds number and the cylinder aspect ratio on the vortex cells could be shown. The analysis of the vortex shedding behavior shows good agreement with previously published results. At the same time, the applied PIV technique provides more spatial information than point-based measurements and offers insight into a Reynolds number range that is currently out of reach of Direct Numerical Simulations.

  16. Morse taper dental implants and platform switching: The new paradigm in oral implantology

    PubMed Central

    Macedo, José Paulo; Pereira, Jorge; Vahey, Brendan R.; Henriques, Bruno; Benfatti, Cesar A. M.; Magini, Ricardo S.; López-López, José; Souza, Júlio C. M.

    2016-01-01

    The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: “Bone loss and platform switching,” “bone loss and implant-abutment joint,” “bone resorption and platform switching,” “bone resorption and implant-abutment joint,” “Morse taper and platform switching.” “Morse taper and implant-abutment joint,” Morse taper and bone resorption,” “crestal bone remodeling and implant-abutment joint,” “crestal bone remodeling and platform switching.” The selection criteria used for the article were: meta-analysis; randomized controlled trials; prospective cohort studies; as well as reviews written in English, Portuguese, or Spanish languages. Within the 287 studies identified, 81 relevant and recent studies were selected. Results indicated a reduced occurrence of peri-implantitis and bone loss at the abutment/implant level associated with Morse taper implants and a reduced-diameter platform switching abutment. Extrapolation of data from previous studies indicates that Morse taper connections associated with platform switching have shown less inflammation and possible bone loss with the peri-implant soft tissues. However, more long-term studies are needed to confirm these trends. PMID:27011755

  17. Modified reverse tapering method to prevent frequency shift of the radiation in the planar undulator

    NASA Astrophysics Data System (ADS)

    Shim, Chi Hyun; Ko, In Soo; Parc, Yong Woon

    2017-03-01

    This paper presents a modified reverse tapering method to generate a polarized soft x ray in x-ray free-electron lasers (XFELs) with a higher photon power and a shorter undulator length than the simple linear reverse tapering method. In the proposed method, a few untapered planar undulators are added before the simple linear reverse tapering section of the undulator line. This simple modification prevents the frequency shift of the radiation that occurs when the simple linear reverse tapering method is applied to planar undulators. In the proposed method, the total length of planar undulators decreased in spite of the additional untapered undulators. When the modified reverse tapering method is used with four untapered planar undulators, the total length of the planar undulators is 64.6 m. On the other hand, the required length of the planar undulators is 94.6 m when the simple linear reverse tapering method is used. The proposed method gives us a way to generate a soft x-ray pulse (1.24 keV) with a high degree of polarization (>0.99 ) and radiation power (>30 GW ) at the new undulator line with a 10-GeV electron beam in the Pohang Accelerator Laboratory X-ray Free-Electron Laser. This method can be applied in the existing XFELs in the world without any change in the undulator lines.

  18. Robust plasmonic tips fabricated by the tapering of composite hybrid silicate microfibers with metallic core

    NASA Astrophysics Data System (ADS)

    Petropoulou, Afroditi; Antonopoulos, Grigoris; Bastock, Paul; Craig, Christopher; Kakarantzas, Georgios; Hewak, Dan W.; Zervas, Michalis N.; Riziotis, Christos

    2016-11-01

    The development of plasmonic devices for sensing applications can offer high sensitivity and a dramatic improvement to the detection limits due to the high field enhancement at the metal surfaces. The platform proposed here is a tapered hybrid microfiber comprising a metal core and a glass cladding. The existence of a glass cladding not only serves as a mechanical host for the metal core, but also provides ease of handling regarding the tapering process. The advantages of this composite material system over pure metal tips are the absence of impurities and the multiple excitation of the plasmon modes due to the total internal reflection at the glass/air interface. The improved field enhancement at the apex of these tapered microwires was calculated through Finite Element Method (FEM) simulations. Enhancement factors up to 104 were theoretically observed for this type of tapered microwires. The use of different metals having different melting points and thermal expansion coefficients as well as different glass thicknesses can lead to an optimization of the tapering process conditions in order to achieve tapered microwires with the desirable geometrical characteristics.

  19. Genetic structure and phylogenetic relationships of the Polish Heavy horse.

    PubMed

    Iwańczyk, Ewa; Juras, Rytis; Cholewiński, Grzegorz; Cothran, E Gus

    2006-01-01

    In this study a wide range of genetic markers (12 microsatellites, 7 blood-group loci, 10 blood-protein loci) and mitochondrial DNA (mtDNA) were used to assess genetic diversity in Polish Heavy horses. Three random samples were sequenced for 421 bp of the mitochondrial D-loop region, but no clear phylogenetic patterns were seen in mtDNA variation. Both heterozygosity and diversity levels are fairly high in Polish Heavy horses. In phylogenetic analysis the draught horses form a distinct cluster that pairs with the true pony breeds. Within this 'cold-blooded' group, the Polish Heavy Horse clusters most closely with the Posavina breed from Croatia and the Breton breed from France. From the standpoint of genetic conservation, the Polish Heavy Horse does not appear to be in jeopardy.

  20. Method for polishing the end of an optical fiber

    NASA Technical Reports Server (NTRS)

    Dholakia, Anil R. (Inventor)

    1988-01-01

    A method of polishing a roof-shaped, or bevelled, tip having a predetermined angle on the end of an optical fiber is disclosed. The method comprises placing an optical fiber in contact with an abrasive tape at an angle corresponding to the desired predetermined angle. The fiber is moved towards the tape beyond the point of contact so as to cause a bend in the fiber. Upon moving the abrasive tape, the compliance of the fiber, by virtue of the bend, provides a pressure of the fiber against the tape to enable polishing to occur. As polishing continues the pressure decreases until enough material is removed so as to eliminate the bend and impart the predetermined angle to the fiber tip. The fiber may be rotated to polish the other side in a similar manner, if so desired.

  1. High quality optically polished aluminum mirror and process for producing

    NASA Technical Reports Server (NTRS)

    Lyons, III, James J. (Inventor); Zaniewski, John J. (Inventor)

    2005-01-01

    A new technical advancement in the field of precision aluminum optics permits high quality optical polishing of aluminum monolith, which, in the field of optics, offers numerous benefits because of its machinability, lightweight, and low cost. This invention combines diamond turning and conventional polishing along with india ink, a newly adopted material, for the polishing to accomplish a significant improvement in surface precision of aluminum monolith for optical purposes. This invention guarantees the precise optical polishing of typical bare aluminum monolith to surface roughness of less than about 30 angstroms rms and preferably about 5 angstroms rms while maintaining a surface figure accuracy in terms of surface figure error of not more than one-fifteenth of wave peak-to-valley.

  2. High quality optically polished aluminum mirror and process for producing

    NASA Technical Reports Server (NTRS)

    Lyons, III, James J. (Inventor); Zaniewski, John J. (Inventor)

    2002-01-01

    A new technical advancement in the field of precision aluminum optics permits high quality optical polishing of aluminum monolith, which, in the field of optics, offers numerous benefits because of its machinability, lightweight, and low cost. This invention combines diamond turning and conventional polishing along with india ink, a newly adopted material, for the polishing to accomplish a significant improvement in surface precision of aluminum monolith for optical purposes. This invention guarantees the precise optical polishing of typical bare aluminum monolith to surface roughness of less than about 30 angstroms rms and preferably about 5 angstroms rms while maintaining a surface figure accuracy in terms of surface figure error of not more than one-fifteenth of wave peak-to-valley.

  3. Application of Nail Polish During Topical Management of Onychomycosis

    PubMed Central

    Del Rosso, James Q.

    2016-01-01

    Topical antifungal management of toenail onychomycosis has been fraught with several therapeutic challenges including difficulty gaining access to the site of infection and the need for prolonged durations of therapy. In addition, there has been a marked lack of information on the impact of toenail polish application on drug penetration after application. This article reviews available data from studies evaluating the effect of nail polish on antifungal drag penetration using ex vivo laboratory models with cadaver fingernail plates with both tavaborole 5% solution and efinaconazole 10% solution. In addition, changes in nail polish appearance and color transfer to applicators are also discussed, with changes noted with topical efinaconazole. Importantly, there are no data on whether or not nail polish application alters the efficacy of these topical agents. PMID:27672416

  4. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing... that contains an abrasive material, such as silica pumice, intended to remove debris from the...

  5. DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.

    EPA Science Inventory

    The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...

  6. Research of annular polishing asymmetric ZnS plane window

    NASA Astrophysics Data System (ADS)

    Guo, Weijin; Tong, Yi; Jin, Yuzhu; Lin, Nana

    2016-10-01

    Due the annular polishing technology for planar optical components do not have the sharp selectivity, annular polishing technology is a very import process to fabricate irregular planar elements which with high precision surface shape and low surface roughness. According to the characteristics of annular polishing, the zns asymmetric plane window annular polishing process and key technical parameters control was researched. In this paper, one pair of asymmetric planar ZnS window parts were machined which diagonal length is 147mm, through technology experiments, obtained process test samples. The surface figures of the plane zns window are measured by a Zygo interferometer and the reflect wavefront P-V value is better than 1.5λ, the reflect wavefront local error rms value is better than 0.05λ (λ=632.8nm). Experiments results demonstrate the effectiveness of annular processing technology was used to manufacture zinc sulfide asymmetric shape plane window.

  7. Electrochemical and mechanical polishing and shaping method and system

    NASA Technical Reports Server (NTRS)

    Engelhaupt, Darell E. (Inventor); Gubarev, Mikhail V. (Inventor); Jones, William David (Inventor); Ramsey, Brian D. (Inventor); Benson, Carl M. (Inventor)

    2011-01-01

    A method and system are provided for the shaping and polishing of the surface of a material selected from the group consisting of electrically semi-conductive materials and conductive materials. An electrically non-conductive polishing lap incorporates a conductive electrode such that, when the polishing lap is placed on the material's surface, the electrode is placed in spaced-apart juxtaposition with respect to the material's surface. A liquid electrolyte is disposed between the material's surface and the electrode. The electrolyte has an electrochemical stability constant such that cathodic material deposition on the electrode is not supported when a current flows through the electrode, the electrolyte and the material. As the polishing lap and the material surface experience relative movement, current flows through the electrode based on (i) adherence to Faraday's Law, and (ii) a pre-processing profile of the surface and a desired post-processing profile of the surface.

  8. Effect of chemical polishing in titanium materials for low outgassing

    NASA Astrophysics Data System (ADS)

    Ishizawa, K.; Kurisu, H.; Yamamoto, S.; Nomura, T.; Murashige, N.

    2008-03-01

    A chemical polishing using a nitric acid solution was found to be the most suitable for the titanium materials. 1.8 nm of small surface roughness was observed in a microscopic range in 1 μm square, and 7 nm of a thin oxide layer was shown to exist for the chemically polished titanium. The surface processing for the titanium was developed combining the chemical polishing and the precision cleaning. The chemically polished pure titanium of JIS grade 2 showed extremely low outgassing rate below 10-12 Pams-1 after baking process, which is two orders of magnitude smaller than that for standard vacuum materials under the same baking condition. Outgassing rates of the titanium is about 1/5 of that for a stainless steel without baking process.

  9. Fundamental studies on silicon dioxide chemical mechanical polishing

    NASA Astrophysics Data System (ADS)

    Mahajan, Uday

    Chemical Mechanical Polishing (CMP) has lately been adopted on a large scale by the semiconductor industry for planarizing and patterning metal and dielectric films. Additionally, CMP has been used for hundreds of years for optical polishing. Still, several aspects of this process remain poorly understood. In this study, some results on CMP of SiO2 are presented with a view to characterizing the effects of abrasive properties and slurry chemistry on the polishing process. Additionally, some results from a novel in-situ friction force measuring instrument are also presented. The friction force results showed the effect of several parameters such as surface roughness, solution pH and ionic strength on wafer-pad interactions. Additionally, monitoring the friction as a function of velocity showed that the transition from boundary lubrication to full fluid-film lubrication depends on the roughness (conditioning) of the polishing pad. The parameters investigated in the polishing experiments include abrasive size and concentration. From the experimental results, it was found that an optimum concentration exists for each abrasive size, which shifts to lower values and becomes narrower as particle size increases. From calculations, this was attributed to a decreased ability of the large particles to chemically modify the surface of the SiO2 films. The smaller particles, having a much larger surface area, are able to better adsorb dissolution and abrasion products at high concentrations, thus leading to high removal rates under those conditions. Studies on the effect of slurry ionic strength showed that the ability of a metal ion to shield the surface charge on the surfaces interacting during polishing is what determined removal rate. This was due to the reduced electrostatic repulsion between the surfaces, which resulted in better contact and thus higher polishing rates. These results were corroborated by the earlier friction force measurements. Finally, the influence of

  10. Automation of Die and Mold Polishing: A Preliminary Investigation

    DTIC Science & Technology

    1990-02-02

    molecules. 2 The dominant theories appear to be the molecular removal theory supported by Rabinowicz and the abrasive wear theory supported by Samuels...53 Rabinowicz states, "practical experience suggests that in polishing copper, an abrasive size of 3 pm represents approximately the demarcation...Reading, Massachusetts: Addison- Wesley, 1984), pp. 563. 51. Ibid., pp. 562. 52. E. Rabinowicz , "The Nature of Polished and Burnished Surfaces, Proceedings

  11. A jet polishing technique for thinning two phase materials

    SciTech Connect

    Witcomb, M.J. ); Dahmen, U. )

    1990-11-01

    A common problem in the preparation of thin foils for transmission electron microscopy is the different thinning rate in two-phase materials. Often this leads to foils in which the majority, or matrix, phase is evenly polished while the minority, or precipitate, phase is either etched out or stands proud of the surrounding material. In the present report we describe a two-stage jet polishing technique that has been used successfully on different relatively coarse two-phase structures. 3 figs.

  12. Joining of SiC parts by polishing and hipping

    DOEpatents

    Rossi, Guilio A.; Pelletier, Paul J.

    1990-05-15

    A method of joining two pre-sintered pieces of silicon carbide is disclosed. It entails polishing the surfaces to be joined to a mirror-finish, fitting the polished surfaces together to form a composite structure, and then subjecting the composite structure to hot isostatic pressing under conditions which are sufficient to form a joint which is essentially indistinguishable from the original silicon carbide pieces.

  13. Stereomicroscope Inspection of Polished Aluminum Collector 50684.0

    NASA Technical Reports Server (NTRS)

    Rodriquez, M. C.; Calaway, M. J.; Allton, J. H.

    2008-01-01

    The Genesis polished aluminum "kidney" collector was damaged during the hard landing of the capsule on September 8, 2004 in the Utah desert. The kidney was introduced into the Genesis (ISO class 4) cleanroom laboratory on November 4, 2004 and stored under nitrogen cover gas. The collector is currently fastened to a highly polished stainless steel plate for secure handling. Curatorial work at JSC has made successful subdivision and subsequent allocation of samples from the kidney.

  14. Automated visual inspection for polished stone manufacture

    NASA Astrophysics Data System (ADS)

    Smith, Melvyn L.; Smith, Lyndon N.

    2003-05-01

    Increased globalisation of the ornamental stone market has lead to increased competition and more rigorous product quality requirements. As such, there are strong motivators to introduce new, more effective, inspection technologies that will help enable stone processors to reduce costs, improve quality and improve productivity. Natural stone surfaces may contain a mixture of complex two-dimensional (2D) patterns and three-dimensional (3D) features. The challenge in terms of automated inspection is to develop systems able to reliably identify 3D topographic defects, either naturally occurring or resulting from polishing, in the presence of concomitant complex 2D stochastic colour patterns. The resulting real-time analysis of the defects may be used in adaptive process control, in order to avoid the wasteful production of defective product. An innovative approach, using structured light and based upon an adaptation of the photometric stereo method, has been pioneered and developed at UWE to isolate and characterize mixed 2D and 3D surface features. The method is able to undertake tasks considered beyond the capabilities of existing surface inspection techniques. The approach has been successfully applied to real stone samples, and a selection of experimental results is presented.

  15. Couvade Syndrome among Polish expectant fathers

    PubMed Central

    Kazmierczak, Maria; Kielbratowska, Bogumiła; Pastwa-Wojciechowska, Beata; Preis, Krzysztof

    2013-01-01

    Background The aim of the conducted study was to analyze the phenomenon of Couvade Syndrome amongst fathers expecting their children in Poland. The authors examined the frequency of couvade symptoms in male subjects as well as their associations with male empathy. Material/Methods The research involved 143 expectant fathers. All subjects attended antenatal classes, and their female partners were in their third trimester. Before the start of classes, participants were asked to fill in the following questionnaires: a survey for measurement of Couvade Syndrome (which includes a set of 16 symptoms identified by Lipkin and Lamb (19) and translated into Polish), and the Empathic Sensitiveness Scale (SWE). Although participants, on average, did not experience Couvade Syndrome, they did experience symptoms that are commonly linked with the syndrome, namely those related to weight (weight gain, changes in appetite and flatulence). Results The results indicate that expectant fathers experience couvade symptoms related to weight (weight gain, changes in appetite and flatulence). The only empathic component that positively correlates with Couvade Syndrome is personal distress, i.e. the tendency to take on the negative emotions of others. Demographic characteristics are not associated with Couvade Syndrome. Conclusions The frequency of couvade symptoms in male subjects is associated with male empathy. In other words, men who are emotionally sensitive or prone to distress may physiologically experience the pregnancy of their female partners, which can be interpreted as compathy. PMID:23425940

  16. Tissue banking training courses: Polish experience.

    PubMed

    Kaminski, Artur; Gut, Grzegorz; Uhrynowska-Tyszkiewicz, Izabela; Olender, Ewa

    2013-03-01

    Personnel directly involved in the donation, procurement, testing, processing, preservation, storage and distribution of human tissues and cells should be appropriately qualified and provided with timely and relevant training according to EU directives. In the time of new tissue and cells regulations implementation such a training system existed in Poland only at a local level. The first training programme outlines for various groups of health professionals engaged in tissue banking practice was created in co-operation with the Institute for LifeLong Learning at University of Barcelona in 2006. This initial training courses were financially supported by EU Transition Facility Programme 2004. Then, starting from 2006, based on previous experience, system of advanced training courses was created. This training programme was financially supported by the National Programme for the Development of Transplantation Medicine 2006-2009-POLGRAFT financed by Polish Ministry of Health. During 2006 and 2007 first set of tissue banking initial training courses were provided according to TF 2004 project. Over 200 pathologists, forensic medicine specialists and other medical doctors responsible for donor screening and classification, medical directors of tissue establishments, technical staff; tissue graft users: orthopaedic surgeons, neurosurgeons, cardiosurgeons and ophthalmologists were trained. Between 2006 and 2009 there were organized 8 advanced tissue banking training courses according to POLGRAFT programme. There were organized both theoretical and practical courses on various aspects of tissue for over 350 persons. We present our experience in organisation of international and national tissue banking training courses.

  17. Stem cells.

    PubMed

    Behr, Björn; Ko, Sae Hee; Wong, Victor W; Gurtner, Geoffrey C; Longaker, Michael T

    2010-10-01

    Stem cells are self-renewing cells capable of differentiating into multiple cell lines and are classified according to their origin and their ability to differentiate. Enormous potential exists in use of stem cells for regenerative medicine. To produce effective stem cell-based treatments for a range of diseases, an improved understanding of stem cell biology and better control over stem cell fate are necessary. In addition, the barriers to clinical translation, such as potential oncologic properties of stem cells, need to be addressed. With renewed government support and continued refinement of current stem cell methodologies, the future of stem cell research is exciting and promises to provide novel reconstructive options for patients and surgeons limited by traditional paradigms.

  18. STEM Sell

    ERIC Educational Resources Information Center

    Pantic, Zorica

    2007-01-01

    Between 1994 and 2003, employment in science, technology, engineering and math (STEM) fields grew by a remarkable 23 percent, compared with 17 percent in non-STEM fields, according to federal data. The Bureau of Labor Statistics predicts continued strong growth in STEM job openings through 2014, with emphasis on life sciences, environmental…

  19. Effects of tapering structures on the characteristics of a coaxial-waveguide gyrotron backward-wave oscillator

    SciTech Connect

    Hung, C. L.; Chang, T. H.; Yeh, Y. S.

    2011-10-15

    This study analyzes the characteristics of a gyrotron backward-wave oscillator (gyro-BWO) with a longitudinally tapered coaxial-waveguide by using a single-mode, self-consistent nonlinear code. Simulation results indicate that although tapering the inner wall or the outer wall can significantly raise the start-oscillation current, the former is more suitable for mode selection than the latter because an increase of the start-oscillation current by a tapered inner wall heavily depends on the chosen C value (i.e., the average ratio of the outer radius to the inner radius over the axial waveguide length). Selective suppression of the competing mode by tapering the inner wall is numerically demonstrated. Moreover, efficiency of the coaxial gyro-BWO is increased by tapering the outer wall. Properly down-tapering the outer wall ensures that the coaxial gyro-BWO can reach a maximum efficiency over twice that with a uniform one.

  20. Coupled fiber taper extraction of 1.53 microm photoluminescence from erbium doped silicon nitride photonic crystal cavities.

    PubMed

    Shambat, Gary; Gong, Yiyang; Lu, Jesse; Yerci, Selçuk; Li, Rui; Dal Negro, Luca; Vucković, Jelena

    2010-03-15

    Optical fiber tapers are used to collect photoluminescence emission at approximately 1.5 microm from photonic crystal cavities fabricated in erbium doped silicon nitride on silicon. In the experiment, photoluminescence collection via one arm of the fiber taper is enhanced 2.5 times relative to free space collection, corresponding to a net collection efficiency of 4%. Theoretically, the collection efficiency into one arm of the fiber-taper with this material system and cavity design can be as high as 12.5%, but the degradation of the experimental coupling efficiency relative to this value mainly comes from scattering loss within the short taper transition regions. By varying the fiber taper offset from the cavity, a broad tuning range of coupling strength and collection efficiency is obtained. This material system combined with fiber taper collection is promising for building on-chip optical amplifiers.

  1. Fatigue Life Methodology for Tapered Composite Flexbeam Laminates

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; OBrien, T. Kevin; Rousseau, Carl Q.

    1997-01-01

    The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delamination fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to non-linear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axial-tension and transverse cyclic bending. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen. Continued cycling resulted in multiple delaminations. A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed. The global responses of the model and test specimens agreed very well in terms of the transverse displacement. The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode 2, whereas delamination growth toward the thin region was almost completely mode 1. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

  2. Fatigue Life Methodology for Tapered Composite Flexbeam Laminates

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.; O''Brien, T. Kevin; Rousseau, Carl Q.

    1997-01-01

    The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delamination fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to nonlinear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axial-tension and transverse cyclic bending loads. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen. Continued cycling resulted in multiple delaminations. A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed. The global responses of the model and test specimens agreed very well in terms of the transverse flexbeam tip-displacement and flapping angle. The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode 2, whereas delamination growth toward the thin region was almost completely mode 1. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

  3. Vortex shedding behind tapered obstacles in neutral & stratified flow

    NASA Astrophysics Data System (ADS)

    Castro, Ian; Vosper, Simon; Paisley, Martin; Hayden, Paul

    2001-10-01

    Results of laboratory and numerical experiments on both homogeneous and density-stratified flow over single, bluff obstacles of various shapes are presented. The obstacle height is in most cases of the same order as the base diameter and the major controlling (flow) parameter is the Froude number, defined here as Fh= U/ Nh, where U is the (uniform) upstream velocity, h the obstacle height and N is the buoyancy frequency. Attention is concentrated, firstly, on the case of homogeneous flows over rather weakly tapered obstacles and, secondly, for bodies whose height is similar to their base width, on the case Fh=0.1, representing stratification sufficiently strong that lee-wave motions do not play a significant role in the flow dynamics. For right-circular cones it is shown that the sectional contributions to the total fluctuating side force (lift) show significant phase variations up the height of the obstacle, which are not always reflected in the developed vortex street further downstream. For some obstacle shapes, the vortex lines linking the von Karman eddies at different heights can be significantly tilted, particularly in the upper part of the wake. Vortex convection speeds do not appear generally to vary greatly with height and, as found in previous work, the shedding frequency remains constant with height, despite the strong variation of cross-stream obstacle width. By comparison with the homogeneous results, it is suggested that the stratification enhances the shedding instability, which would otherwise be very weak for squat obstacles, but does not annihilate the ability of the flow at one level to influence that at another.

  4. Density-tapered spiral arrays for ultrasound 3-D imaging.

    PubMed

    Ramalli, Alessandro; Boni, Enrico; Savoia, Alessandro Stuart; Tortoli, Piero

    2015-08-01

    The current high interest in 3-D ultrasound imaging is pushing the development of 2-D probes with a challenging number of active elements. The most popular approach to limit this number is the sparse array technique, which designs the array layout by means of complex optimization algorithms. These algorithms are typically constrained by a few steering conditions, and, as such, cannot guarantee uniform side-lobe performance at all angles. The performance may be improved by the ungridded extensions of the sparse array technique, but this result is achieved at the expense of a further complication of the optimization process. In this paper, a method to design the layout of large circular arrays with a limited number of elements according to Fermat's spiral seeds and spatial density modulation is proposed and shown to be suitable for application to 3-D ultrasound imaging. This deterministic, aperiodic, and balanced positioning procedure attempts to guarantee uniform performance over a wide range of steering angles. The capabilities of the method are demonstrated by simulating and comparing the performance of spiral and dense arrays. A good trade-off for small vessel imaging is found, e.g., in the 60λ spiral array with 1.0λ elements and Blackman density tapering window. Here, the grating lobe level is -16 dB, the lateral resolution is lower than 6λ the depth of field is 120λ and, the average contrast is 10.3 dB, while the sensitivity remains in a 5 dB range for a wide selection of steering angles. The simulation results may represent a reference guide to the design of spiral sparse array probes for different application fields.

  5. Effect of implant design on initial stability of tapered implants.

    PubMed

    Chong, Linus; Khocht, Ahmed; Suzuki, Jon B; Gaughan, John

    2009-01-01

    Implant design is one of the parameters for achieving successful primary stability. This study aims to examine the effect of a self-tapping blades implant design on initial stability in tapered implants. Polyurethane blocks of different densities were used to simulate different bone densities. The two different implant designs included one with self-tapping blades and one without self-tapping blades. Implants were placed at 3 different depths: apical third, middle third, and fully inserted at 3 different densities of polyurethane blocks. A resonance frequency (RF) analyzer was then used to measure stability of the implants. Repeated-measures analysis of variance was used to examine the effect of implant design, insertion depth, and block density on RF. Analysis of covariance was used to examine the strength of association between RF and the aforementioned factors. In both medium-density (P = .017) and high-density (P = .002) blocks, fully inserted non-self-tapping implants showed higher initial stability than self-tapping implants. No differences were noted between the 2 implant designs that were not fully inserted. The highest strength of association was with insertion depth (standardized beta [std beta] = -0.60, P = .0001), followed by block density (std beta = -0.15, P = .0002). Implant design showed a weak association (std beta = -0.07, P = .09). In conclusion, fully inserted implants without self-tapping blades have higher initial stability than implants with self-tapping blades. However, the association strength between implant design and initial stability is less relevant than other factors, such as insertion depth and block density. Thus, if bone quality and quantity are optimal, they may compensate for design inadequacy.

  6. Salivary hormones, IgA, and performance during intense training and tapering in judo athletes.

    PubMed

    Papacosta, Elena; Gleeson, Michael; Nassis, George P

    2013-09-01

    The aims of this study were to identify the time course of change of salivary testosterone (sT), cortisol (sC), and IgA (SIgA); mood state; and performance capacity during a 2-week taper in judo athletes and to examine the diurnal variation in these salivary markers. Eleven male judo athletes completed 5 weeks of training: 1 week of normal training (NORM), 2 weeks of intensified training (INT), and 2 weeks of exponential tapering (TAPER). Once per week subjects completed vertical and horizontal countermovement jump tests, a grip strength test, a Special Judo Fitness Test, a multistage aerobic fitness test, a 3 × 300-m run test, and anthropometric measurement. Subjects also completed questionnaires to assess mood state and muscle soreness. Two daily saliva samples (at 0700 and 1900) were collected at the end of each week during NORM and INT and every day during TAPER. Increased morning sT, decreased evening sC, lower muscle soreness, and enhanced mood state (p < 0.05) were evident by the early phases of TAPER. A significant 7.0% improvement in 3 × 300-m performance time, a 6.9% improvement in the vertical jump (p < 0.05), and increased morning and evening SIgA secretion rate (p < 0.01) were observed during the middle-late phases of TAPER. The higher values of salivary variables were observed in the morning. This study indicates that salivary hormones display diurnal variation. Furthermore, changes in hormonal responses, mood state, and muscle soreness precede enhancements in performance and mucosal immunity, suggesting that judo athletes taper for at least a week before competition.

  7. Computer-Controlled Cylindrical Polishing Process for Development of Grazing Incidence Optics for Hard X-Ray Region

    NASA Technical Reports Server (NTRS)

    Khan, Gufran Sayeed; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    The presentation includes grazing incidence X-ray optics, motivation and challenges, mid spatial frequency generation in cylindrical polishing, design considerations for polishing lap, simulation studies and experimental results, future scope, and summary. Topics include current status of replication optics technology, cylindrical polishing process using large size polishing lap, non-conformance of polishin lap to the optics, development of software and polishing machine, deterministic prediction of polishing, polishing experiment under optimum conditions, and polishing experiment based on known error profile. Future plans include determination of non-uniformity in the polishing lap compliance, development of a polishing sequence based on a known error profile of the specimen, software for generating a mandrel polishing sequence, design an development of a flexible polishing lap, and computer controlled localized polishing process.

  8. Initiatory concept of localized CO2 laser-based tapering rig for realization of in-fiber devices

    NASA Astrophysics Data System (ADS)

    Aharoni, Ran; Bidani, Liron; Sinvani, Moshe; Zalevsky, Zeev

    2012-07-01

    We present the development procedure as well as preliminary fabrication results for a CO2 laser-based tapering rig allowing one stage tapering of optical fibers. Our aim is to develop in-fiber devices constructed from fibers filled with various materials, which can be drawn from thick preforms using the presented procedure. The constructed tapering rig consists of a CO2 laser as the heating source, ellipsoid-based mirror optics, and computer-controlled high-precision motors.

  9. New technology in condensate polishing. Final report

    SciTech Connect

    Kunin, R.; Salem, E.; Libutti, B.

    1992-08-01

    Sulfonic acid ion exchange resins. when carried into a boiler or steam generator, thermally decompose releasing large amounts of corrosive, sulfates. Replacement of the sulfonic acid resin with a carboxylic acid resin would eliminate this source of contamination. The sulfonic acid resin is a strong acid: the carboxylic acid resin is a weak acid. The carboxylic acid resin alone is not capable of splitting salts which limits its use to mixed resin beds or to its use in single or individual beds with feeds of high alkalinity or high pH values. Laboratory, pilot plant and full scale plant tests compared the two resins in precoat filters. When the resins in mixed beds were in the acid form, the weakly acid resin was almost as effective in removing sodium ion as the strongly acid resin. In the ammonium form. the weakly acid resin was generally more effective in removing sodium than the strongly acid resin. Condensate polishing reduced the sodium ion to a few parts per billion (ppB). Complete resin separation before regeneration is more important for the weakly acid resin than for the strongly acid resin. Another development found that the hydrazine reaction with oxygen could be catalyzed by powdered activated carbon combined with microfibers on a Powdex substrate. The carbon should be thoroughly washed to reduce its residual sodium content. In plant tests, the carbon reduced the oxygen concentration in condensate about 50% during startup. In preliminary tests believed to be typical, carbon lowered the oxygen concentration below 10 ppB in about 6 hours compared to 18 hours without the carbon. Oxygen is also reduced during normal operation.

  10. Studies on polishing of Ti and Ag-Pd-Cu-Au alloy with five dental abrasives.

    PubMed

    Hirata, T; Nakamura, T; Takashima, F; Maruyama, T; Taira, M; Takahashi, J

    2001-08-01

    Titanium (Ti) and Ag-Pd-Cu-Au alloy were examined for their polishing behaviour by conducting manually controlled polishing tests using five dental abrasives [carborundum point (CR) and silicone points (R1 and R2)] driven by a high torque micromotor with rotational speeds ranging from 2000 to 15 000 r.p.m. Polishing of Ti resulted in less volume of removal upon polishing, a rougher surface and larger loss of abrasives, compared with polishing of Ag-Pd-Cu-Au alloy. Polishing of Ti with a rotational speed of 15 000 r.p.m. led to the largest volume of removal upon polishing, whilst that of 10 000 r.p.m. produced the optimal volume for Ag-Pd-Cu-Au alloy. It was concluded that Ti was much more difficult to polish, requiring special care (e.g. frequent exchange of abrasives). Development of new abrasives for polishing Ti is required.

  11. Effect of several processing parameters on material removal ratio in the deliquescent polishing of KDP crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Feihu; Guo, Shaolong; Zhang, Yong; Luan, Dianrong

    2009-05-01

    A new ultraprecision machining technology for potassium dihydrogen phosphate (KDP) crystals, deliquescent polishing technology for KDP crystals, which utilizes deliquescent effect for ultraprecision machining KDP crystals, is proposed. The principle and the advantages of technology are introduced. The deliquescent polishing procedure of KDP crystals is given. The deliquescent polishing experiments of KDP crystals are conducted, and the material removal ratios are calculated. Through the experiments, the effect of four processing parameters (velocity of polishing plate, velocity of drip, volume percentage of water in the deliquescent polishing fluid, polishing pressure) on material removal ratio in the deliquescent polishing of KDP crystals is researched. The plot of material removal ratio versus every processing parameter in the deliquescent polishing of KDP crystals is obtained, and the rules of material removal ratio in the deliquescent polishing of KDP crystals are reached.

  12. Trapping and propelling microparticles at long range by using an entirely stripped and slightly tapered no-core optical fiber.

    PubMed

    Sheu, Fang-Wen; Huang, Yen-Si

    2013-02-28

    A stripped no-core optical fiber with a 125 µm diameter was transformed into a symmetric and unbroken optical fiber that tapers slightly to a 45-µm-diameter waist. The laser light can be easily launched into the no-core optical fiber. The enhanced evanescent wave of the slightly tapered no-core optical fiber can attract nearby 5-µm-diameter polystyrene microparticles onto the surface of the tapered multimode optical fiber within fast flowing fluid and propel the trapped particles in the direction of the light propagation to longer delivery range than is possible using a slightly tapered telecom single-mode optical fiber.

  13. Linear permittivity tapering in a Cerenkov microwave source with a pre-bunched beam

    NASA Astrophysics Data System (ADS)

    Poole, B. R.; Harris, J. R.

    2013-04-01

    Cerenkov microwave sources use a dielectric-lined waveguide to reduce the velocity of the electromagnetic wave and provide efficient energy transfer between the wave and the driving electron beam. Tapering the permittivity of the dielectric to maintain synchronism between the beam and the wave as the beam loses energy can increase the efficiency of these devices. Here, we consider such a structure driven by an electron beam with a harmonic density perturbation. Particle-In-Cell (PIC) simulations and a macro-particle model based on the slowly varying envelope approximation are first used to examine an un-tapered baseline case. PIC simulations of the source with linear tapers over the entire amplifier length as well as over only a section of the amplifier where the beam executes synchrotron oscillations are examined. The efficiency for the baseline un-tapered source is 18%, while efficiencies up to approximately 48% are found using a taper in dielectric permittivity. Results of the best performing cases are presented. Detailed examination of longitudinal phase space, particle energy distributions, evolution of longitudinal wavenumber, and phase dynamics are presented from the PIC simulations.

  14. Flexural-torsional vibration of a tapered C-section beam

    NASA Astrophysics Data System (ADS)

    Dennis, Scott T.; Jones, Keith W.

    2017-04-01

    Previous studies have shown that numerical models of tapered thin-walled C-section beams based on a stepped or piecewise prismatic beam approximation are inaccurate regardless of the number of elements assumed in the discretization. Andrade recently addressed this problem by extending Vlasov beam theory to a tapered geometry resulting in new terms that vanish for the uniform beam. (See One-Dimensional Models for the Spatial Behaviour of Tapered Thin-Walled Bars with Open Cross-Sections: Static, Dynamic and Buckling Analyses, PhD Thesis, University of Coimbra, Portugal, 2012, https://estudogeral.sib.uc.pt) In this paper, we model the coupled bending-twisting vibration of a cantilevered tapered thin-walled C-section using a Galerkin approximation of Andrade's beam equations resulting in an 8-degree-of-freedom beam element. Experimental natural frequencies and mode shapes for 3 prismatic and 2 tapered channel beams are compared to model predictions. In addition, comparisons are made to detailed shell finite element models and exact solutions for the uniform beams to confirm the validity of the approach. Comparisons to the incorrect stepped model are also presented.

  15. Increasing the Strength of Adhesively Bonded Joints by Tapering the Adherends

    SciTech Connect

    GUESS,TOMMY R.; METZINGER,KURT E.

    1999-09-09

    Wind turbine blades are often fabricated with composite materials. These composite blades are frequently attached to a metallic structure with an adhesive bond. For the baseline composite-to-steel joint considered in this study, failure typically occurs when the adhesive debonds from the steel adherend. Previous efforts established that the adhesive peel stresses strongly influence the strength of these joints for both single-cycle and fatigue loading. This study focused on reducing the adhesive peel stresses present in these joints by tapering the steel adherends. Several different tapers were evaluated using finite element analysis before arriving at a final design. To confirm that the selected taper was an improvement to the existing design, the baseline joint and the modified joint were tested in both compression and tension. In these axial tests, the compressive strengths of the joints with tapered adherends were greater than those of the baseline joints for both single-cycle and low-cycle fatigue. In addition, only a minor reduction in tensile strength was observed for the joints with tapered adherends when compared to the baseline joints. Thus, the modification would be expected to enhance the overall performance of this joint.

  16. Morphology and Dynamics of Tapered Diblock Copolymers from fDFT-initialized MD Simulations

    NASA Astrophysics Data System (ADS)

    Hall, Lisa M.; Seo, Youngmi; Brown, Jonathan R.

    2015-03-01

    Tapered block copolymers are similar to AB diblock copolymers, but with a statistical A-to-B (normal) or B-to-A (inverse) gradient ``taper'' between the A and B blocks. Depending on the sequence of monomers along the chain and the segregation strength, the A and B monomers are known to microphase separate into various ordered morphologies. Tapering introduces an additional parameter, independent of molecular weight or polymer choice, to tune morphology, and has been shown previously to widen the gyroid region of the phase diagram.In this study, we use classical, fluids density functional theory (fDFT) and molecular dynamics (MD) simulations to study the morphology and dynamics of tapered systems. Using fDFT allows us to accurately compare free energies between different potential microphases as a function of interaction parameter and fraction of A. Because of the similarity of the fDFT and MD models, the fDFT results map very closely with the corresponding MD model. We use the fDFT density profiles to generate the initial state of the chains for the simulations. Lamellae, cylinders, and other phases can be generated in this way with approximately correct spacing and density. We apply the streamlined simulation setup to analyze the effect of tapering on conformations and dynamics.

  17. Effect of sequence dispersity on morphology of tapered diblock copolymers from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Levine, William G.; Seo, Youngmi; Brown, Jonathan R.; Hall, Lisa M.

    2016-12-01

    Tapered diblock copolymers are similar to typical AB diblock copolymers but have an added transition region between the two blocks which changes gradually in composition from pure A to pure B. This tapered region can be varied from 0% (true diblock) to 100% (gradient copolymer) of the polymer length, and this allows some control over the microphase separated domain spacing and other material properties. We perform molecular dynamics simulations of linearly tapered block copolymers with tapers of various lengths, initialized from fluids density functional theory predictions. To investigate the effect of sequence dispersity, we compare systems composed of identical polymers, whose taper has a fixed sequence that most closely approximates a linear gradient, with sequentially disperse polymers, whose sequences are created statistically to yield the appropriate ensemble average linear gradient. Especially at high segregation strength, we find clear differences in polymer conformations and microstructures between these systems. Importantly, the statistical polymers are able to find more favorable conformations given their sequence, for instance, a statistical polymer with a larger fraction of A than the median will tend towards the A lamellae. The conformations of the statistically different polymers can thus be less stretched, and these systems have higher overall density. Consequently, the lamellae formed by statistical polymers have smaller domain spacing with sharper interfaces.

  18. Linear permittivity tapering in a Cerenkov microwave source with a pre-bunched beam

    SciTech Connect

    Poole, B. R.; Harris, J. R.

    2013-04-15

    Cerenkov microwave sources use a dielectric-lined waveguide to reduce the velocity of the electromagnetic wave and provide efficient energy transfer between the wave and the driving electron beam. Tapering the permittivity of the dielectric to maintain synchronism between the beam and the wave as the beam loses energy can increase the efficiency of these devices. Here, we consider such a structure driven by an electron beam with a harmonic density perturbation. Particle-In-Cell (PIC) simulations and a macro-particle model based on the slowly varying envelope approximation are first used to examine an un-tapered baseline case. PIC simulations of the source with linear tapers over the entire amplifier length as well as over only a section of the amplifier where the beam executes synchrotron oscillations are examined. The efficiency for the baseline un-tapered source is 18%, while efficiencies up to approximately 48% are found using a taper in dielectric permittivity. Results of the best performing cases are presented. Detailed examination of longitudinal phase space, particle energy distributions, evolution of longitudinal wavenumber, and phase dynamics are presented from the PIC simulations.

  19. Tapered optical fiber tip probes based on focused ion beam-milled Fabry-Perot microcavities

    NASA Astrophysics Data System (ADS)

    André, Ricardo M.; Warren-Smith, Stephen C.; Becker, Martin; Dellith, Jan; Rothhardt, Manfred; Zibaii, M. I.; Latifi, H.; Marques, Manuel B.; Bartelt, Hartmut; Frazão, Orlando

    2016-09-01

    Focused ion beam technology is combined with dynamic chemical etching to create microcavities in tapered optical fiber tips, resulting in fiber probes for temperature and refractive index sensing. Dynamic chemical etching uses hydrofluoric acid and a syringe pump to etch standard optical fibers into cone structures called tapered fiber tips where the length, shape, and cone angle can be precisely controlled. On these tips, focused ion beam is used to mill several different types of Fabry-Perot microcavities. Two main cavity types are initially compared and then combined to form a third, complex cavity structure. In the first case, a gap is milled on the tapered fiber tip which allows the external medium to penetrate the light guiding region and thus presents sensitivity to external refractive index changes. In the second, two slots that function as mirrors are milled on the tip creating a silica cavity that is only sensitive to temperature changes. Finally, both cavities are combined on a single tapered fiber tip, resulting in a multi-cavity structure capable of discriminating between temperature and refractive index variations. This dual characterization is performed with the aid of a fast Fourier transform method to separate the contributions of each cavity and thus of temperature and refractive index. Ultimately, a tapered optical fiber tip probe with sub-standard dimensions containing a multi-cavity structure is projected, fabricated, characterized and applied as a sensing element for simultaneous temperature and refractive index discrimination.

  20. Paul Lazarsfeld and Polish sociology: a historical record of contact, perception, and impact.

    PubMed

    Sułek, A

    1998-01-01

    This paper records the Polish aspects of P. F. Lazarsfeld's sociointellectual biography and examines his impact on Polish sociology. The analysis is divided into three chronological parts. In the 1930s, Lazarsfeld's empirical work inspired Polish sociologists in their studies on unemployment. In the late 1950s and 1960s, his model of empirical social research shaped the style of sociological practice in Poland. In the 1990s, some of Lazarsfeld's substantive contributions, mainly in the area of election studies, were taken up in Polish sociology. Lazarsfeld's influence on Polish sociology was conditioned by changes in Polish society and sociology, which is emphasized in this analysis.

  1. The role of food in the Polish migrant adjustment journey.

    PubMed

    Brown, Lorraine; Paszkiewicz, Irena

    2017-02-01

    In 2015, there were 916,000 Poles living in the UK, making them the largest group of non-UK nationals at 16.5 percent of the population. Though increasingly research has focused on the consequences of this migration for both migrants themselves and the receiving country, little research has looked at food habits. This paper will explore the role of food in the Polish migrant adjustment journey. A qualitative approach was adopted, involving semi-structured interviews with nine Polish migrants. In this study, Polish migrants described the move to a new culture as a time of stress and loneliness. Due to a lack of money, they were forced to eat local food, which exacerbated their unease, as they found it to be tasteless and unhealthy. As soon as their financial situation improved, they reverted to a Polish diet, relying on ingredients brought from home, from London, or more recently, purchased from local Polish shops. This gave them comfort, and all participants acknowledged the vital role of food in their adjustment to life in a new culture.

  2. Nail polish as a source of exposure to triphenyl phosphate.

    PubMed

    Mendelsohn, Emma; Hagopian, Audrey; Hoffman, Kate; Butt, Craig M; Lorenzo, Amelia; Congleton, Johanna; Webster, Thomas F; Stapleton, Heather M

    2016-01-01

    Triphenyl phosphate (TPHP) is primarily used as either a flame retardant or plasticizer, and is listed as an ingredient in nail polishes. However, the concentration of TPHP in nail polish and the extent of human exposure following applications have not been previously studied. We measured TPHP in ten different nail polish samples purchased from department stores and pharmacies in 2013-2014. Concentrations up to 1.68% TPHP by weight were detected in eight samples, including two that did not list TPHP as an ingredient. Two cohorts (n=26 participants) were recruited to assess fingernail painting as a pathway of TPHP exposure. Participants provided urine samples before and after applying one brand of polish containing 0.97% TPHP by weight. Diphenyl phosphate (DPHP), a TPHP metabolite, was then measured in urine samples (n=411) and found to increase nearly seven-fold 10-14h after fingernail painting (p<0.001). To determine relative contributions of inhalation and dermal exposure, ten participants also painted their nails and painted synthetic nails adhered to gloves on two separate occasions, and collected urine for 24h following applications. Urinary DPHP was significantly diminished when wearing gloves, suggesting that the primary exposure route is dermal. Our results indicate that nail polish may be a significant source of short-term TPHP exposure and a source of chronic exposure for frequent users or those occupationally exposed.

  3. Consensus Conference Findings on Supragingival and Subgingival Air Polishing.

    PubMed

    Cobb, Charles M; Daubert, Diane M; Davis, Karen; Deming, Jodi; Flemmig, Thomas F; Pattison, Anna; Roulet, Jean-François; Stambaugh, Roger V

    2017-02-01

    A consensus conference was convened to evaluate and address issues of safety and efficacy when using glycine powder in an air-powder jet device for supra- and subgingival applications during dental prophylaxis and periodontal maintenance. The conference reported the following conclusions: 1) Supra- and subgingival air polishing using glycine powder is safe and effective for removal of biofilms from natural tooth structure and restorative materials; 2) there is no evidence of soft-tissue abrasion when using glycine powder in an air-polishing device; 3) in periodontal probing depths of 1 mm to 4 mm, glycine-powder air polishing, using a standard air-polishing nozzle, is more effective at removing subgingival biofilm than manual or ultrasonic instruments; and 4) at probing depths of 5 mm to 9 mm, using a subgingival nozzle, glycine powder air polishing is more effective at removing subgingival biofilm than manual or ultrasonic instrumentation. This conference statement, supported by an industry grant, was drafted by a panel of distinguished dental professionals.

  4. Nail Polish as a Source of Exposure to Triphenyl Phosphate

    PubMed Central

    Mendelsohn, Emma; Hagopian, Audrey; Hoffman, Kate; Butt, Craig M.; Lorenzo, Amelia; Congleton, Johanna; Webster, Thomas F.; Stapleton, Heather M.

    2015-01-01

    Triphenyl phosphate (TPHP) is primarily used as either a flame retardant or plasticizer, and is listed as an ingredient in nail polishes. However, the concentration of TPHP in nail polish and the extent of human exposure following applications have not been previously studied. We measured TPHP in ten different nail polish samples purchased from department stores and pharmacies in 2013–2014. Concentrations up to 1.68% TPHP by weight were detected in eight samples, including two that did not list TPHP as an ingredient. Two cohorts (n=26 participants) were recruited to assess fingernail painting as a pathway of TPHP exposure. Participants provided urine samples before and after applying one brand of polish containing 0.97% TPHP by weight. Diphenyl phosphate (DPHP), a TPHP metabolite, was then measured in urine samples (n=411) and found to increase nearly seven-fold 10–14 hours after fingernail painting (p<0.001). To determine relative contributions of inhalation and dermal exposure, ten participants also painted their nails and painted synthetic nails adhered to gloves on two separate occasions, and collected urine for 24 hours following applications. Urinary DPHP was significantly diminished when wearing gloves, suggesting that the primary exposure route is dermal. Our results indicate that nail polish may be a significant source of short-term TPHP exposure and a source of chronic exposure for frequent users or those occupationally exposed. PMID:26485058

  5. BRITE-PL: the first Polish scientific satellite

    NASA Astrophysics Data System (ADS)

    Orleanski, Piotr; Graczyk, Rafal; Rataj, Miroslaw; Schwarzenberg-Czerny, Aleksander; Zawistowski, Tomasz; Zee, Robert E.

    2010-09-01

    The participation in BRITE Consortium gives Poland the possibility to launch into space the first Polish scientific satellite. This paper presents the Polish technical contribution to the BRITE Program to be realized in two institutes of the Polish Academy of Sciences: Nicolaus Copernicus Astronomical Center and Space Research Center.. BRITE Constellation, short for "BRIght Target Explorer Constellation," is a group of up to six nano-satellites whose purpose is to photometrically measure low-level oscillations and temperature variations in the sky's 286 stars brighter than visual magnitude 3.5, with unprecedented precision and time sampling not achievable through terrestrial-based methods. The three-axis pointing performance (1 arc minute rms stability) of each BRITE satellite is a significant advancement over anything that has ever flown before on a nano-satellite and is an important factor that enables the high precision photometry mission. The paper summarizes the technical details of the BRITE satellite based on Generic Nanosatellite Bus from SFL/UTIAS. The first Polish satellite, BRITE -PL 1, will be a modified version of the original SFL design. The second Polish satellite, BRITE-PL 2, will include the significant changes to be implemented by SRC PAS.

  6. Trench-embedding fiber taper sensor fabricated by a femtosecond laser for gas refractive index sensing.

    PubMed

    Cao, Zhitao; Jiang, Lan; Wang, Sumei; Wang, Peng; Zhang, Fei; Lu, Yongfeng

    2014-02-20

    A fiber in-line, multimode coupling interferometer with a trench-embedding, fiber taper probe is proposed and fabricated by femtosecond-laser-induced water breakdown. The reflection-type taper probe is used for gas refractive index (RI) detection from 1.0001143 to 1.0002187 and temperature sensing from 50°C to 500°C. The largest RI sensitivity of the taper probe embedded with a trench at a width of 18.4 μm is 669.502  nm/RIU for hybrid nitrogen and helium. Temperature sensitivity is 9.97  pm/°C and it shows good linearity through the whole testing range. The new-type multimode interferometer is appropriate for high-accuracy gas RI detection of micrometer-scale spaces and wide-range temperature compensation can be realized.

  7. Optical similaritons in a tapered graded-index nonlinear-fiber amplifier with an external source

    SciTech Connect

    Raju, Thokala Soloman; Panigrahi, Prasanta K.

    2011-09-15

    We analytically explore a wide class of optical similariton solutions to the nonlinear Schroedinger equation appropriately modified to model beam propagation in a tapered, graded-index nonlinear-fiber amplifier with an external source. Under certain physical conditions, we reduce the coupled nonlinear Schroedinger equations to a single-wave equation that aptly describes similariton propagation through asymmetric twin-core fiber amplifiers. The asymmetric twin-core fiber is composed of two adjoining, closely spaced, single-mode fibers in which the active one is a tapered, graded-index nonlinear-fiber and the passive one is a step-index fiber. We obtain these self-similar waves for different choices of tapered index profile, using a Moebius transformation. Our procedure is applicable for both self-focusing and self-defocusing nonlinearities.

  8. A high sensitivity refractometer based on a tapered SCSMF structure and its application to biosensing

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Ma, Youqiao; Semenova, Yuliya; Yuan, Jinhui; Bo, Lin; Wang, Pengfei; Sang, Xinzhu; Teng, Mianzhen; Yu, Chongxiu; O'Mahony, Christy Charlton; Farrell, Gerald

    2014-05-01

    A high sensitivity refractive index (RI) sensor based on a tapered small core singlemode fibre (SCSMF) structure is proposed and developed. By tapering the SCSMF section, this sensor has very high sensitivity around the RI of water. Experimentally we have demonstrated a sensitivity of 1988.5 nm/RIU (RI unit) in the RI range from 1.3325 to 1.3407 by tapering a SCSMF section from a diameter of 125 μm to a diameter of 16 μm. The feasibility of using this type of sensor for biosensing application has also been verified by experiments. This was undertaken using a suitable Fibrinogen antigen surface functionalisation, which successfully showed that the sensor can in principle detect differences in the concentration of a Fibrinogen antibody.

  9. Tailored dispersion profile in controlling optical solitons in a tapered parabolic index fiber

    NASA Astrophysics Data System (ADS)

    Prakash, S. Arun; Malathi, V.; Mani Rajan, M. S.

    2016-03-01

    We investigate the soliton dynamics in tapered parabolic index fibers via symbolic computation for a variety of dispersion profiles to inspect how a specific dispersion profile controls the optical soliton. By means of AKNS procedure, Lax pair is constructed for nonlinear Schrödinger equation with variable coefficients. Using obtained Lax pair, multi-soliton solutions are generated via Darboux transformation technique. Using multi-soliton solutions, soliton dynamics in tapered parabolic index fiber with the hyperbolic, Gaussian, exponential, and linear profiles are discussed. Results obtained in this study will be of certain potential application on construction of the nonlinear optical devices by soliton control. Results obtained in this study will be of certain value to the studies on the propagation and application of the soliton in the tapered parabolic index fiber and dispersion-managed fiber system.

  10. Efficient formalism for treating tapered structures using the Fourier modal method

    NASA Astrophysics Data System (ADS)

    Osterkryger, Andreas D.; Gregersen, Niels

    2016-04-01

    We investigate the development of the mode occupations in tapered structures using the Fourier modal method. In order to use the Fourier modal method, tapered structures are divided into layers of uniform refractive index in the propagation direction and the optical modes are found within each layer. This is not very efficient and in this proceeding we take the first steps towards a more efficient formalism for treating tapered structures using the Fourier modal method. We show that the coupling coefficients through the structure are slowly varying and that only the first few modes are occupied. We exploit both of these properties in the developing of a more efficient formalism.

  11. High-power 1550 nm tapered DBR lasers fabricated using soft UV-nano-imprint lithography

    NASA Astrophysics Data System (ADS)

    Viheriälä, Jukka; Aho, Antti T.; Mäkelä, Jaakko; Salmi, Joel; Virtanen, Heikki; Leinonen, Tomi; Dumitrescu, Mihail; Guina, Mircea

    2016-03-01

    Paper reports the DBR-RWG surface grating design, the fabrication process, and the output characteristics of tapered DBR laser diodes for the applications, like for example LIDAR and range finding, that require eye-safe high-power single-mode coherent light sources. The fabricated regrowth-free DBR AlGaInAs/InP lasers exhibited a CW output power as high as 560 mW in single-mode operation at room temperature. At maximum output power the SMSR was 38 dB, proving the excellent behavior of the surface gratings. The tapered section enabled scaling the maximum CW power at room temperature from 125 mW to 560 mW, by increasing its length from 0.5 mm to 4.0 mm. The paper discusses the limitations and performance variation associated to the power scaling by using the tapered section length as a scaling parameter.

  12. Characteristics of a Linearly Tapered Slot Antenna (LTSA) Conformed Longitudinally Around a Cylinder

    NASA Technical Reports Server (NTRS)

    Jordan, Jennifer L.; Ponchak, George E.; Tavassolian, Negar; Tentzeris, Manos M.

    2007-01-01

    The family of tapered slot antennas (TSA s) is suitable for numerous applications. Their ease of fabrication, wide bandwidth, and high gain make them desirable for military and commercial systems. Fabrication on thin, flexible substrates allows the TSA to be conformed over a given body, such as an aircraft wing or a piece of clothing for wearable networks. Previously, a Double Exponentially Tapered Slot Antenna (DETSA) was conformed around an exponential curvature, which showed that the main beam skewed towards the direction of curvature. This paper presents a Linearly Tapered Slot Antenna (LTSA) conformed longitudinally around a cylinder. Measured and simulated radiation patterns and the direction of maximum H co-polarization (Hco) as a function of the cylinder radius are presented.

  13. Ultrathin fiber-taper coupling with nitrogen vacancy centers in nanodiamonds at cryogenic temperatures.

    PubMed

    Fujiwara, Masazumi; Zhao, Hong-Quan; Noda, Tetsuya; Ikeda, Kazuhiro; Sumiya, Hitoshi; Takeuchi, Shigeki

    2015-12-15

    We demonstrate cooling of ultrathin fiber tapers coupled with nitrogen vacancy (NV) centers in nanodiamonds to cryogenic temperatures. Nanodiamonds containing multiple NV centers are deposited on the subwavelength 480-nm-diameter nanofiber region of fiber tapers. The fiber tapers are successfully cooled to 9 K using our home-built mounting holder and an optimized cooling speed. The fluorescence from the nanodiamond NV centers is efficiently channeled into a single guided mode and shows characteristic sharp zero-phonon lines (ZPLs) of both neutral and negatively charged NV centers. The present nanofiber/nanodiamond hybrid systems at cryogenic temperatures can be used as NV-based quantum information devices and for highly sensitive nanoscale magnetometry in a cryogenic environment.

  14. Self-efficacy and compliance with benzodiazepine taper in older adults with chronic insomnia.

    PubMed

    Bélanger, Lynda; Morin, Charles M; Bastien, Céyne; Ladouceur, Robert

    2005-05-01

    Better understanding of compliance with BZD taper is warranted. Compliance with a taper program and perceived self-efficacy (SE) in being able to comply with hypnotic reduction goals was monitored weekly in 52 older adults (mean age: 63.0 years) with chronic insomnia (average duration: 21.9 years) who underwent a 10-week physician-supervised medication tapering. One group received cognitive- behavior therapy for insomnia during discontinuation, whereas the other did not. Compliant patients showed higher SE ratings at Weeks 6, 8, 9, and 10. Medication-free patients at the end of the treatment also reported higher mean SE ratings at those 4 weeks. Differences remained significant when withdrawal symptoms and sleep efficiency were controlled for. These results have important clinical implications because SE may indicate key time points when patients are experiencing more difficulty during discontinuation.

  15. Temperature sensor based on a tapered optical fiber with ALD nanofilm

    NASA Astrophysics Data System (ADS)

    Zhu, Shan; Pang, Fufei; Wen, Jianxiang; Zhao, Ziwen; Wang, Tingyun

    2015-09-01

    A temperature sensor with high sensitivity based on a tapered optical fiber with Al2O3 nanofilm by atomic layer deposition (ALD) technology is presented. Attributed to the high refractive index Al2O3 nanofilm overlay, an asymmetry Fabry-Perot interferometer is formed along the tapered fiber. Based on the ray-optic analysis, the resonant dip in the interference transmission spectrum depends on the phase delay variation induced by the Goos-Hänchen shift at the nanofilm-coating interface. As a result, the interference transmission spectrum shows good sensitivity to the change of surrounding refractive index. In this work, a temperature-sensitive silicone gel is coated around the fiber taper with Al2O3 nanofilm to realize a high sensitivity temperature sensor. The high sensitivity of 2.44 nm/°C is obtained.

  16. Dual wavelength erbium-doped fiber laser using a tapered fiber

    NASA Astrophysics Data System (ADS)

    Harun, S. W.; Lim, K. S.; Jasim, A. A.; Ahmad, H.

    2010-12-01

    A tapered fiber is fabricated by heating and stretching a piece of optical fiber after the polymer protective cladding has been removed. An equidistant comb-like transmission spectrum, with a spacing of 1.6 nm and an extinction ratio of more than 5 dB, was obtained by the tapered fiber due to the multibeam interferences of the cladding modes. The tapered fiber was applied in a ring erbium-doped fiber laser (EDFL) to generate dual-wavelength lasing oscillations. The EDFL operates at wavelengths of 1557.0 nm and 1558.6 nm with a stable peak power and a signal-to-noise ratio of more than 40 dB.

  17. Enhanced Kerr nonlinearity in As IISe 3 chalcogenide fibre tapers with sub-wavelength diameter

    NASA Astrophysics Data System (ADS)

    Nguyen, Hong C.; Mägi, Eric C.; Yeom, Dong-Il; Fu, Libin; Eggleton, Benjamin J.

    2007-05-01

    The nonlinearity in optical fibres can be enhanced significantly by reducing the effective mode area or by using materials with higher nonlinear-index coefficient (n II). In this paper we combine these two concepts and experimentally demonstrate enhanced Kerr nonlinear effects in tapered highly nonlinear As IISe 3 chalcogenide fibre. We taper the fibre to sub-wavelength waist diameter of 1.2 μm and observe enhanced nonlinearity of 63,600 W -1km -1. This is 40,000 times larger than in silica single-mode fibre, owing to the 400 times larger n II and almost 100 times smaller effective mode area. We also discuss the role of group velocity dispersion in these highly nonlinear fibre tapers.

  18. [Polish legal terms of animal-based research - selected aspects].

    PubMed

    Poznański, Paweł; Niedźwiecki, Sławomir

    2014-01-01

    Animal-based models used in biomedical sciences allow to perform research that, conducted on humans, would be highly problematic because of bioethical and technical issues. Contemporary researchers race can lead to abuse, hence the need for special law regulations regarding this subject. This necessity reflected both in the EU and Polish legislation, and is rooted in the philosophical and moral achievements of Europe. EU legislation in this case takes the form of directives implemented in the legal systems of the member states. Polish tradition of legislative approach to animal-based research is long. In 1959 the wide attempt to regulate this matter was undertaken. Until 2005, the nature of the matter had been regulated by the Polish animal protection law. Currently, details concerning animal-based-research are regulated by the animal experiments law (2005). The elapsed time since enactment allowed doctrine and judicature to reveal capabilities and vulnerabilities of the law.

  19. Computer numeric control subaperture aspheric surface polishing-microroughness evaluation

    NASA Astrophysics Data System (ADS)

    Prochaska, Frantisek; Polak, Jaroslav; Matousek, Ondrej; Tomka, David

    2014-09-01

    The aim of this work was an investigation of surface microroughness and shape accuracy achieved on an aspheric lens by subaperture computer numeric control (CNC) polishing. Different optical substrates were polished (OHARA S-LAH 58, SF4, ZERODUR) using a POLITEX™ polishing pad, synthetic pitch, and the natural optical pitch. Surface roughness was measured by light interferometer. The best results were achieved on the S-LAH58 glass and the ZERODUR™ using the natural optical pitch. In the case of SF4 glass, the natural optical pitch showed a tendency to scratch the surface. Experiments also indicated a problem in surface form deterioration when using the natural optical pitch, regardless of the type of optical material.

  20. [Polish medical ethics in the period 1945-1980].

    PubMed

    Wichrowski, Marek

    2003-01-01

    The purpose of this article is o present that main currents of Polish medical ethics in the years 1945-1980, which the author treats as the 'prehistory' of Poland's contemporary bioethics. The author begins by ascertaining the post-war disappearance of two Polish traditions--that of the Warsaw school of philosopher-physicians (known in the West as the Polish School of Philosophy of Medicine) and the Lwów-Warsaw School of Philosophy. The political system that come into being after 1945 was not conducive to the development of medical ethics, but several clear orientations may be discerned in the utterances of physicians, lawyers, moral technologlans and academic philosophers. The analysis begins with Catholic ethics in its archaic 1950s-vintage form. The author then presents the thinking of ethicians Independent of both the Church and Marxism (the milieu of the journal 'Etyka') as well as the deontological writings of physicians.

  1. Particle adhesion studies relevant to chemical mechanical polishing.

    PubMed

    Lu, Zhenyu; Ryde, Niels P; Babu, S V; Matijević, Egon

    2005-10-25

    This study describes particle adhesion experiments carried out to elucidate interactions between particles in slurries used for polishing of wafers and disks. For this purpose the packed column technique was employed, which simulated chemical mechanical polishing of copper with silica and alumina, as well as of silicic oxide with ceria. The model systems consisted of uniform copper and glass beads as collectors, representing the wafers, and colloidal dispersions of silica, alumia, and silica coated with nanosize ceria, all of well-defined properties that are used as abrasives. It was shown that a strong correlation exists between deposition and detachment results of the adhesion studies and the polish rates measured using actual substrates with the same or similar slurries.

  2. SiO overcoating and polishing of CFRP telescope panels

    NASA Technical Reports Server (NTRS)

    Woida, Patrick; Hoffmann, William F.

    1988-01-01

    Development of carbon fiber reinforces plastic (CFRP) panel overcoating and polishing is structured in two parts. The first part utilized a short series of experiments to determine the feasibility of overcoating and polishing CFRP panels, and the second part employes a systematic approach to optimize techniques learned. Questions which required answers in the initial investigation are summarized. Tests were performedin the Steward Observatory's 2.2 Meter Vacuum Coating Chamber and began with 3 cm square pieces of CFRP facesheet material. Next, a 10 cm square and one-inch-thick CFPR-Aluminum core panel was tested. Tests were then conducted on a 0.5-meter-square Dornier panel (QUAD 4) with CFRP facesheets on two-inch aluminum Flexcore. To complete the initial study, a previously characterized 0.5 m Dornier panel (QUAD 23) was coated and hand polished. The mirror's optical performance was not affected by the SiO coating.

  3. Evaluation of the tapered PMMA fiber sensor response due to the ionic interaction within electrolytic solutions

    NASA Astrophysics Data System (ADS)

    Batumalay, M.; Rahman, H. A.; Kam, W.; Ong, Y. S.; Ahmad, F.; Zakaria, R.; Harun, S. W.; Ahmad, H.

    2014-01-01

    A tapered plastic multimode fiber (PMMA) optical sensor is proposed and demonstrated for continuous monitoring of solutions based on different concentration of sodium chloride and glucose in deionized water The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 mm and 10 mm, respectively, and was used to investigate the effect of straight, U-shape, and knot shape against concentration for both sodium chloride and glucose. The results show that there is a strong dependence of the electrolytic and non-electrolytic nature of the chemical solutions on the sensor output. It is found that the sensitivity of the sodium chloride concentration sensor with the straight tapered fiber probe was 0.0023 mV/%, which was better than the other probe arrangements of U-shape and knot. Meanwhile, the glucose sensor performs with the highest sensitivity of 0.0026 mV/wt % with the knot-shaped tapered fiber probe. In addition, a tapered PMMA probe which was coated by silver film was fabricated and demonstrated using calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observed increment in the transmission of the sensor that is immersed in solutions of higher concentration. As the concentration varies from 0 ppm to 6 ppm, the output voltage of the sensor increases linearly from 3.61 mV to 4.28 mV with a sensitivity of 0.1154 mV/ppm and a linearity of more than 99.47%. The silver film coating increases the sensitivity of the proposed sensor due to the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber.

  4. What causes a small increase in radiographic progression in rheumatoid arthritis patients tapering TNF inhibitors?

    PubMed Central

    Bouman, Chantal A M; den Broeder, Alfons A; van der Maas, Aatke; van den Hoogen, Frank H J; Landewé, Robert B M; van Herwaarden, Noortje

    2017-01-01

    Objective In a randomised controlled trial investigating tapering of TNF inhibitors (TNFi) compared with usual care (UC) in rheumatoid arthritis patients, minimal radiographic progression was more frequent in patients who attempted tapering. Possible explanations include higher incidence of flaring, higher mean disease activity or lower TNFi use. Methods 18 months data from the DRESS study were used. Change in Sharp-van der Heijde (ΔSvdH) score (linear regression) and proportion of patients with >0.5 ΔSvdH (logistic regression) were used as outcomes. The cumulative incidence and number of short-lived and major flares per patient, mean time-weighted disease activity (MTW-DAS28-CRP) and TNFi use were used as independent variables. Regression models were performed stratified per study group and corrected for possible confounders. Results 175 of 180 patients had 18-month data available. The mean ΔSvdH were 0.75 and 0.15 units with 37 of 116 (32%) and 9 of 59 (15%) patients exceeding 0.5 points in the tapering and UC group, respectively (both p<0.05). MTW-DAS28-CRP, but not incidence or number of short-lived or major flares, or TNFi use, was independently associated with the mean progression score, but only in the tapering group. Additional analyses on DAS28-CRP subcomponents showed that this was mainly caused by MTW swollen joint count. No confounders were identified. Conclusions Radiographic progression was associated with higher MTW-DAS28-CRP (and especially swollen joint count), but only in patients who tapered TNFi. This finding stresses the importance of maintaining disease activity as low as possible in patients in whom TNFi is tapered and to check for radiographic progression regularly. Trial registration number NTR 3216; Post-results.

  5. Waveguide tapering for beam-width control in a waveguide transducer.

    PubMed

    Kwon, Young Eui; Jeon, Hyun Joong; Kim, Hoe Woong; Kim, Yoon Young

    2014-03-01

    In a waveguide transducer that transmits an ultrasonic wave through a waveguide unit to a test structure, it is most preferred to send a non-dispersive ultrasonic wave of a narrow beam width. However, there is an unresolved conflict between the generation of the non- or less-dispersive wave and the transmission of a narrow-beam wave into a test structure. Among others, the thickness of the waveguide unit in a waveguide transducer is the key variable determining these two conflicting criteria, but the use of a uniformly-thick waveguide of any thickness cannot fulfill the two conflicting criteria simultaneously. In this study, we propose a specially-engineered tapered waveguide unit for the simultaneous satisfaction. An excitation unit is installed at the end of the thin region of the tapered waveguide and generates only the lowest non-dispersive shear-horizontal wave. Then the generated wave propagates through the tapered region of the waveguide unit and reaches the thick region of the waveguide with insignificant mode conversion to higher modes. If the tapered waveguide is used, the surviving lowest mode in the thick region of the waveguide is shown to carry most of the transmitted power and is finally propagated into a test structure. Because the beam size of the propagated wave and the thickness of the contacting waveguide region are inversely related, the thick contacting region of the tapered waveguide ensures narrow beam width. Numerical and experimental investigations were performed to check the effectiveness of the proposed waveguide-tapering approach.

  6. Development of hybrid fluid jet/float polishing process

    NASA Astrophysics Data System (ADS)

    Beaucamp, Anthony T. H.; Namba, Yoshiharu; Freeman, Richard R.

    2013-09-01

    On one hand, the "float polishing" process consists of a tin lap having many concentric grooves, cut from a flat by single point diamond turning. This lap is rotated above a hydrostatic bearing spindle of high rigidity, damping and rotational accuracy. The optical surface thus floats above a thin layer of abrasive particles. But whilst surface texture can be smoothed to ~0.1nm rms (as measured by atomic force microscopy), this process can only be used on flat surfaces. On the other hand, the CNC "fluid jet polishing" process consists of pumping a mixture of water and abrasive particles to a converging nozzle, thus generating a polishing spot that can be moved along a tool path with tight track spacing. But whilst tool path feed can be moderated to ultra-precisely correct form error on freeform optical surfaces, surface finish improvement is generally limited to ~1.5nm rms (with fine abrasives). This paper reports on the development of a novel finishing method, that combines the advantages of "fluid jet polishing" (i.e. freeform corrective capability) with "float polishing" (i.e. super-smooth surface finish of 0.1nm rms or less). To come up with this new "hybrid" method, computational fluid dynamic modeling of both processes in COMSOL is being used to characterize abrasion conditions and adapt the process parameters of experimental fluid jet polishing equipment, including: (1) geometrical shape of nozzle, (2) position relative to the surface, (3) control of inlet pressure. This new process is aimed at finishing of next generation X-Ray / Gamma Ray focusing optics.

  7. Profilometric analysis of root surfaces after using various polishing agents

    PubMed Central

    Jana, Anjan; Chakraborty, Abhijit; Pal, Tamal Kanti; Datta, Someswar

    2016-01-01

    Background: Polishing is an important step in oral prophylaxis procedure which retards further accumulation of plaque on the root surfaces. Though polishing was done with various abrasive particles with different sizes over a long period of time, it was never been highlighted to evaluate the ideal polishing material and the particle size that would produce the ideal surface smoothness (Ra <0.2 μm). Materials and Methods: The present study was carried out on 70 periodontally involved, caries-free extracted human teeth from 42 patients. All the teeth were collected from the region of incisors, canines, and premolars. In vitro scaling and root planing were performed by piezoelectric scaler and Gracey's area specific curettes, respectively. All the teeth were grouped at random into control and experimental. The collections of abrasive materials were done directly from the market, and the different particle sizes were prepared in the laboratory. Experimentation: The polishing was done at a constant speed of 200 rpm with cylindrical nylon bristle brush followed by rubber prophy cup. Each group belonging to control and experimental was subjected to profilometric study for evaluation of surface roughness. Results: Regular polishing abrasives are not able to produce the surface smoothness of our desire level (i.e., Ra <0.2 μm), which can be achieved only by submicron-sized particles. Conclusion: Regular size polishing particles available in the market (>5 μm) are not able to produce the surface smoothness <0.2 μm. Only, submicron sized particles are able to produce the desired smoothness. PMID:27041833

  8. Span load distribution for tapered wings with partial-span flaps

    NASA Technical Reports Server (NTRS)

    Pearson, H A

    1937-01-01

    Tables are given for determining the load distribution of tapered wings with partial-span flaps placed either at the center or at the wing tips. Seventy-two wing-flap combinations, including two aspect ratios, four taper ratios, and nine flap lengths, are included. The distributions for the flapped wing are divided into two parts, one a zero lift distribution due primarily to the flaps and the other an additional lift distribution due to an angle of attack of the wing as a whole. Comparison between theoretical and experimental results for wings indicate that the theory may be used to predict the load distribution with sufficient accuracy for structural purposes.

  9. Polarization insensitive all-fiber mode-lockers functioned by carbon nanotubes deposited onto tapered fibers

    NASA Astrophysics Data System (ADS)

    Song, Yong-Won; Morimune, Keiyo; Set, Sze Y.; Yamashita, Shinji

    2007-01-01

    The authors demonstrate a nonblocked all-fiber mode locker operated by the interaction of carbon nanotubes with the evanescent field of propagating light in a tapered fiber. Symmetric cross section of the device with the randomly oriented nanotubes guarantees the polarization insensitive operation of the pulse formation. In order to minimize the scattering, the carbon nanotubes are deposited within a designed area around the tapered waist. The demonstrated passively pulsed laser has the repetition rate of 7.3MHz and the pulse width of 829fs.

  10. Laser wakefield acceleration research by using a tapered capillary waveguide at GIST

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Jang, Donggyu; Nam, Inhyuk; Lee, Taehee; Suk, Hyyong

    2012-10-01

    The tapered plasma density in a gas-filled capillary waveguide can suppress the dephasing problem in laser wakefield acceleration (LWFA). As a result, the acceleration distance and the gained electron energy are expected to be increased significantly. For this purpose, we recently developed a tapered capillary waveguide, which can produce a plasma density of 10^18 cm-3. This capillary plasma waveguide will be used for high-energy electron generation experiment together with a 20 TW/35 fs Ti:sapphire laser system that will be completed by this summer. In this presentation, the ongoing experiments will be reported.

  11. Generation of high energy electron accelerated by using a tapered capillary discharge plasma

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Nam, Inhyuk; Lee, Taehee; Lee, Seungwoo; Suk, Hyyong

    2014-10-01

    The tapered plasma density in a gas-filled capillary waveguide can suppress the dephasing problem in laser wakefield acceleration (LWFA). As a result, the acceleration distance and the gained electron energy are expected to be increased. For this purpose, we developed a tapered capillary waveguide, which can produce a plasma density of ~ 1018 cm-3. Using this capillary discharge plasma, we performed the acceleration experiments with the high power laser system (20 TW/40 fs) constructed at GIST. In this presentation, the detailed electron acceleration experiments will be reported.

  12. Coupling of single NV center to adiabatically tapered optical single mode fiber

    NASA Astrophysics Data System (ADS)

    Vorobyov, Vadim V.; Soshenko, Vladimir V.; Bolshedvorskii, Stepan V.; Javadzade, Javid; Lebedev, Nikolay; Smolyaninov, Andrey N.; Sorokin, Vadim N.; Akimov, Alexey V.

    2016-12-01

    We demonstrated a simple and reliable technique of coupling diamond nanocrystal containing NV center to tapered optical fiber. The NV center emission was collected by the fiber via nearfield interaction between NV center and the tapered portion of the fiber. Single photon statistics was demonstrated at the fiber end as well as up to 3 times improvement in collection efficiency with respect to our confocal microscope. Also, we carefully studied fluorescence of the fiber itself and were able to suppress it to the level lower than single photon emission from the NV center.

  13. Wind-tunnel investigation of tapered wings with ordinary ailerons and partial-span split flaps

    NASA Technical Reports Server (NTRS)

    Wenzinger, Carl J

    1937-01-01

    Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel to determine the aerodynamic properties of tapered wings having partial-span flaps for high lift and ordinary ailerons for lateral control. Each of two Clark-y wings, tapered 5:1 and 5:3, was equipped with partial-span split flaps of two lengths and with ordinary ailerons extending from the outboard ends of the flap to the wing tips. Measurements of wing forces and moments and of aileron hinge moments were made for the two conditions of flaps neutral and deflected.

  14. An elastic strip with multiple cracks and applications to tapered specimens

    NASA Technical Reports Server (NTRS)

    Liu, X.-H.; Erdogan, F.

    1985-01-01

    In this paper an infinite elastic strip containing arbitrarily oriented cracks and subjected to uniform tension and a pair of concentrated forces is formulated in terms of a system of singular integral equations. Even though the technique is sufficiently general to solve new multiple crack problem, with the objective of applying the results to tapered specimens, only a certain symmetric crack geometry and loading conditions are considered. The stress intensity factors are calculated for edge cracks in the strip under uniform tension and for a 'compact' and a 'slender' tapered specimen (the latter simulating the double cantilever beam) under concentrated forces or crack surface wedge forces.

  15. Manipulating multiparticles simultaneously with tapered-tip single fiber optical tweezers

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Wu, Zhongfu; Liu, Zhihai; Yang, Jun; Yuan, Libo

    2008-12-01

    We present a single-core tapered-tip single fiber optical tweezers, which can trap multi-particle simultaneously. In order to test and verify its new function, finite difference time domain (FDTD) method is used to calculate and simulate. The relationship between the trapping force and the particle-parameters, such as the size, refractive index and others of particle are studied. By experimental validation, the tapered-tip single optic fiber tweezers can trap Particle 2nd after the Particle 1st trapped firmly, but can not trap Particle 3rd, which just verifies the theoretical simulation results to be right.

  16. Directional anemometer based on an anisotropic flat-clad tapered fiber Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Ling; Lee, Chung-Fen; Li, Chai-Ming; Chiang, Tsai-Ching; Hsiao, Ying-Li

    2012-07-01

    This work demonstrates a sensitive directional anemometer that is based on a pendulum-type of anisotropic flat-clad tapered fiber Michelson interferometer (AFCTFMI). The AFCTFMI is fabricated by tapering an anisotropic flat-cladding fiber to establish structural anisotropy, and enables the sensing of the direction and magnitude of flowing air (wind). Wavelength shifts and fringes visibility of the measured interference fringes are correlated with the magnitude and furthermore the direction of the wind. Experimental results agree closely with the theoretical analysis. The directional anemometer can simultaneously and effectively indicate the direction, and sensitively measure the magnitude of wind.

  17. Improving field enhancement of 2D hollow tapered waveguides via dielectric microcylinder coupling

    NASA Astrophysics Data System (ADS)

    Chen, Yongzhu; Xie, Xiangsheng; Li, Li; Chen, Gengyan; Guo, Lina; Lin, Xusheng

    2015-02-01

    We numerically study a novel scheme to improve the field enhancement of 2D hollow tapered waveguides (HTWs). A dielectric microcylinder is embedded into a metal-insulator-metal (MIM) HTW for resonant exciting gap surface plasmons (GSPs), which is different from the lowest propagating mode (TM0) excitation via the conventional fire-end coupling method. The physical mechanism of the field enhancement and the influence of critical parameters such as numerical aperture (NA) of the lens, permittivity of the microcylinder and the incident wavelength are discussed. The substantial improvement of the GSP excitation efficiency via dielectric microcylinder coupling shows potential in designing tapered MIM waveguides for nanofocusing and field enhancement.

  18. Multiplexing of PVA-coated multimode-fiber taper humidity sensors

    NASA Astrophysics Data System (ADS)

    Wang, Xueping; Zhao, Chun-Liu; Li, Jihui; Jin, Yongxing; Ye, Manping; Jin, Shangzhong

    2013-11-01

    A simple multiplexing method for relative humidity (RH) sensors based on multimode-fiber tapers (MFTs) is proposed and demonstrated. By cascading a polyvinyl alcohol (PVA) coated MFT with every channel of an Arrayed-Waveguide Grating (AWG), multipoint RH measurement is achieved. Experimental results show that the proposed multipoint RH sensor system works well. The output power for every sensor head is almost linearly increased with the RH, and the average sensitivity of the proposed sensor is about 0.23 nW/%RH within the measurement range of 35%RH-90%RH with the taper waist diameter of ˜22 μm.

  19. Tapered simplified modal method for analysis of non-rectangular gratings

    NASA Astrophysics Data System (ADS)

    Li, Shuai; Zhou, Changhe; Barbastathis, George

    2017-01-01

    The Simplified Modal Method (SMM) provides a quick and intuitive way to analyze the performance of gratings of rectangular shapes. For non-rectangular shapes, a version of SMM has been developed, but it applies only to the Littrow-mounting incidence case and it neglects reflection. Here, we use the theory of mode-coupling in a tapered waveguide to improve SMM so that it applies to non-rectangular gratings at arbitrary angles of incidence. Moreover, this new 'Tapered Simplified Modal Method' (TSMM) allows us to properly account for reflected light. We present here the analytical development of the theory and numerical simulations, demonstrating the validity of the method.

  20. Production of Ultrashort FEL XUV Pulses via a Reverse UndulatorTaper

    SciTech Connect

    Fawley, William M.

    2007-10-22

    We adapt the "reverse taper" scheme presented by Saldin etal. (Phys. Rev. ST Accel. Beams, 9, 050702 [2006]) for attosecond pulseproduction to the XUV/soft-xray regime. We find that that GW-level pulsesof a few femtosecond duration or shorter can be produced using electronbeams of quite moderate parameters and undulators of 20-m length orshorter. The output pulse is significantly shifted in wavelength relativeto the main background which permits a further increase in contrast ratiovia simple monochromatization. Moreover, the output pulse has a naturalwavelength chirp that allows further temporal compression, if wanted.Both positive and negative chirps can be produced depending uponthe signof the undulator taper.

  1. Enhanced terahertz transmission through a periodic array of tapered rectangular apertures

    NASA Astrophysics Data System (ADS)

    Devi, Koijam Monika; Sarma, Amarendra K.; Kumar, Gagan

    2016-10-01

    We numerically analyze extraordinary terahertz transmission properties of an array of rectangular shaped apertures perforated periodically on a thin metal film. The apertures are tapered at different angles to achieve higher field concentration at the tapered end. The periodic sub-wavelength scale apertures ensure plasmonic behavior giving rise to the enhanced transmission of a specific frequency mode decided by the periodicity. We compare results of transmission with the rectangular shaped apertures of same parameters and observe a significant increase in the transmission. We have compared results of our numerical simulations with theory and have found them consistent.

  2. A refractive index sensor based on taper Michelson interferometer in multimode fiber

    NASA Astrophysics Data System (ADS)

    Fu, Xinghu; Zhang, Jiangpeng; Wang, Siwen; Fu, Guangwei; Liu, Qiang; Jin, Wa; Bi, Weihong

    2016-11-01

    A refractive index sensor based on taper Michelson interferometer in multimode fiber is proposed. The Hydrofluoric acid corrosion processing is studied in the preparation of single cone multimode optical fiber sensor. The taper Michelson interferometer is fabricated by changing corrosion time. The relationship between fiber sensor feature and corrosion time is analyzed. The experimental results show that the interference spectrum shift in the direction of short wave with the increase of the refractive index. The refractive index sensitivity can reach 115.8008 nm/RIU. Thereby, it can be used in detecting the refractive index in different areas including the environmental protection, health care and food production.

  3. 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.

  4. Polish queer lesbianism: sexual identity without a lesbian community.

    PubMed

    Kowalska, Alicja

    2011-01-01

    The article investigates the state of Polish lesbianism. It presents the history of lesbian groups, lesbian culture, and community in Poland. It puts social and political activism of lesbians in the context of the growing feminist movement and strong nationalism in Poland. Showing the important role of the Internet communication and the way in which queer philosophy is understood in this country, it investigates sexual identity formation and the process through which lesbian communities develop in Poland. The analysis of Polish lesbianism confirms the constructionists' theory that sexual identity formation highly depends on cultural and political circumstances.

  5. Computer controlled precision optical polishing on the diamond turning machine

    SciTech Connect

    Hannah, P.R.; Day, R.D.; Hatch, D.

    1993-10-01

    This abstract reports the force and wear data required to predict the material removal, or wear, for the Numerical controlled (N/C) polishing program. The program`s aim is to provide the operator of a N/C diamond turning machine or N/C grinding machine with the wear characteristics necessary to achieve uniform material removal. The first phase of the program looks at a rotating polishing wheel, moving from near the center to edge of a rotating glass disc. future phases will look at more complex shapes.

  6. Chronology of the Polish Crisis, January 1-August 31, 1982,

    DTIC Science & Technology

    1982-09-28

    of Journalists of the Polish People’s Republic, made up of members supporting martial law. 21 The baptism of Walesa’s seventh child (born in January...Black Madonna of Czestochowa. 10 Glemp told approximately 100,000 worshippers at an outdoor mass in Warsaw that Poles would greet the Pope in *peace...At a gathering of some 300,000 Polish pilgrims cele- brating the 600th anniversary of the Black Madonna of Jasna Gora, Glemp called on the Jaruzelski

  7. Laser polishing for topography management of accelerator cavity surfaces

    SciTech Connect

    Zhao, Liang; Klopf, J. Mike; Reece, Charles E.; Kelley, Michael J.

    2015-07-20

    Improved energy efficiency and reduced cost are greatly desired for advanced particle accelerators. Progress toward both can be made by atomically-smoothing the interior surface of the niobium superconducting radiofrequency accelerator cavities at the machine's heart. Laser polishing offers a green alternative to the present aggressive chemical processes. We found parameters suitable for polishing niobium in all surface states expected for cavity production. As a result, careful measurement of the resulting surface chemistry revealed a modest thinning of the surface oxide layer, but no contamination.

  8. 77 FR 32522 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-01

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the... of the antidumping duty order on Tapered Roller Bearings and Parts Thereof, Finished and Unfinished... and exported by GGB Bearing Technology (Suzhou) Co., Ltd. (``GGB'') during the period of review...

  9. 77 FR 24179 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the...'') published the final results of the antidumping duty administrative review of tapered roller bearings and... ministerial error made in the calculation of the antidumping duty margin for Changshan Peer Bearing...

  10. 78 FR 45912 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-30

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the... (Department) has determined that Shanghai Tainai Bearing Co., Ltd.'s (Tainai's) request for a new shipper review (NSR) of the antidumping duty order on tapered roller bearings and parts thereof, finished...

  11. 78 FR 34985 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-11

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the... order on tapered roller bearings and parts thereof, finished and unfinished (TRBs) from the People's... Company, for the following companies: (1) Changshan Peer Bearing Company (CPZ/SKF); (2) Ningbo...

  12. 76 FR 72213 - Tapered Roller Bearings From China; Notice of Commission determination To Conduct a Full Five...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Tapered Roller Bearings From China; Notice of Commission determination To Conduct a Full Five-Year... tapered roller bearings from China would be likely to lead to continuation or recurrence of...

  13. 78 FR 38943 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-28

    ... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the... review of the antidumping duty order of tapered roller bearings and parts thereof, finished and unfinished (TRBs), from the People's Republic of China (PRC). Specifically, Shanghai General Bearing...

  14. Intergranular corrosion-fatigue failure of cobalt-alloy femoral stems. A failure analysis of two implants.

    PubMed

    Gilbert, J L; Buckley, C A; Jacobs, J J; Bertin, K C; Zernich, M R

    1994-01-01

    Two modular hip implants with a cobalt-alloy head and a cobalt-alloy stem were retrieved after a fracture had occurred in the neck region of the femoral component, eighty-five and seventy months after implantation. Both implants failed less than one millimeter distal to the taper junction between the head and the stem (outside of the taper). The fracture surfaces of the implant were investigated with the use of scanning electron microscopy, to determine the nature of the failure process. The fractures occurred at the grain boundaries of the microstructure and appeared to be the result of three factors: porosity at the grain boundaries; intergranular corrosive attack, initiated both at the head-neck taper and at the free surface; and cyclic fatigue-loading of the stem. The corrosive attack of the free surface was initiated, in part, by the egression of surface grains and by the ingression of fluid into the intergranular regions. Sectioned surfaces showed extensive intergranular corrosive attack in the prosthetic neck localized in the region of the head-neck taper junction and penetrating deeply into the microstructure.

  15. A comparative evaluation of plaque-removing efficacy of air polishing and rubber-cup, bristle brush with paste polishing on oral hygiene status: A clinical study

    PubMed Central

    Patil, Saurabh S.; Rakhewar, Purshottam S.; Limaye, Priyanka S.; Chaudhari, Niraj P.

    2015-01-01

    Objectives: Over the years, professional dental prophylaxis has involved the use of rubber-cup, bristle brush, and abrasive paste for coronal polishing. Although air polishing is an excellent alternative for removal of tooth stain and dental plaque, very few studies have compared their efficacy in vivo. The present study attempts to evaluate and compare the efficacy of air polishing (test) alone versus rubber-cup polishing (control). Materials and Methods: A total of 35 individuals having generalized mild to moderate gingivitis were enrolled as the study population after obtaining their informed consent. Before commencement of the study, all subjects underwent scaling to remove calculus deposits (if any), following which the ipsilateral quadrant of the patient's mouth was randomly assigned as the test side and the contralateral quadrant of the same arch was assigned as the control side for polishing procedures. Time employed for both methods of polishing was held constant at 5 min for each technique. Subjects were assessed before and immediately after polishing and again after 15 days following treatment, for plaque and gingival status along with gingival bleeding. Results: Overall, the results of the intra-group comparison of both the polishing procedure sites indicated similar but significant plaque and gingival status changes, whereas the inter-group comparison showed no significant difference between the efficacies of both the groups. Conclusions: Air polishing and the rubber-cup, bristle brush with paste polishing demonstrated equivalent efficacy regarding removal of supragingival plaque and in reducing gingival inflammation. PMID:26759798

  16. Tapered and linearly chirped fiber Bragg gratings with co-directional and counter-directional resultant chirps

    NASA Astrophysics Data System (ADS)

    Osuch, Tomasz

    2016-05-01

    A method of spectral width tailoring of tapered fiber Bragg gratings is theoretically analyzed and experimentally verified. This concept is based on inscription grating structures in which synthesis of chirps comes from both taper profile and a linearly chirped phase mask used for grating inscription. It is shown that under UV exposure and depending on the orientation of the optical fiber taper relative to the variable-pitch phase mask, tapered and linearly chirped fiber Bragg gratings (TCFBG) with resultant co-directional or counter-directional chirps are achieved. Thus, both effects, those of reduction and enhancement of the grating chirp, as well as their influence on the grating spectral response, are presented. In particular, using the above approach TCFBG with significantly narrowed spectral width are shown. Moreover, fused tapered chirped FBG with relatively large waist diameter are shown having broad spectrum, something that prior to now was not attainable using previously developed techniques.

  17. STEM Education

    PubMed Central

    Xie, Yu; Fang, Michael; Shauman, Kimberlee

    2015-01-01

    Improving science, technology, engineering, and mathematics (STEM) education, especially for traditionally disadvantaged groups, is widely recognized as pivotal to the U.S.’s long-term economic growth and security. In this article, we review and discuss current research on STEM education in the U.S., drawing on recent research in sociology and related fields. The reviewed literature shows that different social factors affect the two major components of STEM education attainment: (1) attainment of education in general, and (2) attainment of STEM education relative to non-STEM education conditional on educational attainment. Cognitive and social psychological characteristics matter for both major components, as do structural influences at the neighborhood, school, and broader cultural levels. However, while commonly used measures of socioeconomic status (SES) predict the attainment of general education, social psychological factors are more important influences on participation and achievement in STEM versus non-STEM education. Domestically, disparities by family SES, race, and gender persist in STEM education. Internationally, American students lag behind those in some countries with less economic resources. Explanations for group disparities within the U.S. and the mediocre international ranking of US student performance require more research, a task that is best accomplished through interdisciplinary approaches. PMID:26778893

  18. STEM Education.

    PubMed

    Xie, Yu; Fang, Michael; Shauman, Kimberlee

    2015-08-01

    Improving science, technology, engineering, and mathematics (STEM) education, especially for traditionally disadvantaged groups, is widely recognized as pivotal to the U.S.'s long-term economic growth and security. In this article, we review and discuss current research on STEM education in the U.S., drawing on recent research in sociology and related fields. The reviewed literature shows that different social factors affect the two major components of STEM education attainment: (1) attainment of education in general, and (2) attainment of STEM education relative to non-STEM education conditional on educational attainment. Cognitive and social psychological characteristics matter for both major components, as do structural influences at the neighborhood, school, and broader cultural levels. However, while commonly used measures of socioeconomic status (SES) predict the attainment of general education, social psychological factors are more important influences on participation and achievement in STEM versus non-STEM education. Domestically, disparities by family SES, race, and gender persist in STEM education. Internationally, American students lag behind those in some countries with less economic resources. Explanations for group disparities within the U.S. and the mediocre international ranking of US student performance require more research, a task that is best accomplished through interdisciplinary approaches.

  19. Application of Swales' Model in the Analysis of Research Papers by Polish Authors.

    ERIC Educational Resources Information Center

    Golebiowski, Zosia

    1999-01-01

    Reports the investigation of the organizational structure of introductory sections of research papers written by Polish authors in English and Polish. The aim of the study was to test whether in view of cultural differences, reflected in the Anglo-American and Polish intellectual styles, the rhetorical pattern of research papers would vary between…

  20. A grooved glass surface-plate for making a flat polished surface

    NASA Astrophysics Data System (ADS)

    Miyagi, Isoji

    2017-01-01

    To obtain a flat polished surface for microchemical analyses such as EPMA, SIMS, and ATR micro-FTIR, a glass plate with a grooved surface was developed for hand polishing with an abrasive film. It eases the polishing process by minimizing slipping or sticking, and results in negligible relief in the sample surface.