WorldWideScience

Sample records for bridge abutments

  1. Integral Abutment and Jointless Bridges

    OpenAIRE

    Cristian-Claudiu Comisu

    2005-01-01

    Integral bridges, or integral abutment and jointless bridges, as they are more commonly known in the USA, are constructed without any movement joints between spans or between spans and abutments. Typically these bridges have stub-type abutments supported on piles and continuous bridge deck from one embankment to the other. Foundations are usually designed to be small and flexible to facilitate horizontal movement or rocking of the support. Integrally bridges are simple or multiple span ones t...

  2. Transition Slabs of Integral Abutment Bridges

    OpenAIRE

    Dreier, Damien; Muttoni, Aurelio; BURDET, Olivier

    2011-01-01

    Over the past decades, an increasing number of bridges with integral abutment have been built in Switzerland. This type of bridge offers various advantages over standard bridges with abutments, equipped with expansion joints and bearings that require regular inspection and maintenance. One main concern of integral abutment bridges is related to the soil-structure interaction, in particular between the transition slab and the embankment. To avoid any expansion joints, transition slabs are dire...

  3. Dynamic Soil-Structure Interaction in Bridge Abutments

    OpenAIRE

    Martínez Cutillas, Antonio; Mateo Bermejo, J.; Alarcón Álvarez, Enrique

    1996-01-01

    Strong motion obtained in instrumental short-span bridges show the importance of the abutments in the dynamic response of the whole structure. Many models have been used in order to take into account the influence of pier foundations although no reliable ones have been used to analyse the abutment performance. In this work three-dimensional Boundary Element models in frequency domain have been proposed and dimensionless dynamic stiffness of standard bridge abutments have been obtained.

  4. Abutments influence in the dynamic response of bridges

    OpenAIRE

    Martínez Cutillas, Antonio; Gómez Lera, Sagrario; Alarcón Álvarez, Enrique

    1996-01-01

    A simplified analytical model of a short span bridge is proposed. The inertial interaction effects of pier foundations and abutments has been included in order to evaluate the response sensitivities to different soil-structure interaction variables. The modification of natural frequency and damping properties is shown for typical short span bridges of the integral deck-abutment type for longitudinal vibrations or general bridges for the transverse ones.

  5. Time-wise variation of scouring at bridge abutments

    Indian Academy of Sciences (India)

    A Melih Yanmaz; Omer Kose

    2007-06-01

    Accurate estimation of the maximum possible depth of scour at bridge abutments is important in decision-making for the safe depth of burial of footings. Besides, investigation of the geometric features of scour holes around abutments provides useful information for the degree of scour counter-measure to be implemented against excessive scouring. Experiments have been performed to investigate time-dependent characteristics of scour holes around vertical wall abutments under clear water conditions with uniform bed materials. Temporal variations of scour depth and scour contours were measured. Using this information, an empirical relation was developed for temporal variation of scour depth. Additional relations were also derived for time-dependent volume and surface area of the scour holes around abutments. The findings of this study may provide useful informatoin for preliminary design of abutment footings and placement details of armoring counter-measures, such as riprap.

  6. Experimental and Analytical Investigations of Piles and Abutments of Integral Bridges

    OpenAIRE

    Arsoy, Sami

    2000-01-01

    Bridges without expansion joints are called "integral bridges." Eliminating joints from bridges crates concerns for the piles and the abutments of integral bridges because the abutments and the piles are subjected to temperature-induced cyclic lateral loads. As temperatures change daily and seasonally, the lengths of integral bridges increase and decrease, pushing the abutment against the approach fill and pulling it away. As a result the bridge superstructure, the abutment, the approach f...

  7. Study of displacements of a bridge abutment using FEM

    Directory of Open Access Journals (Sweden)

    Wymysłowski Michał

    2016-06-01

    Full Text Available Steel sheet piles are often used to support excavations for bridge foundations. When they are left in place in the permanent works, they have the potential to increase foundation bearing capacity and reduce displacements; but their presence is not usually taken into account in foundation design. In this article, the results of finite element analysis of a typical abutment foundation, with and without cover of sheet piles, are presented to demonstrate these effects. The structure described is located over the Więceminka river in the town of Kołobrzeg, Poland. It is a single-span road bridge with reinforced concrete slab.

  8. On the Performance of Super-Long Integral Abutment Bridges: Parametric Analyses and Design Optimization

    OpenAIRE

    Lan, Cheng

    2012-01-01

    The concept of "integral abutment bridge" has recently become a topic of remarka-ble interest among bridge engineers, not only for newly built bridges but also during refurbishment processes. The system constituted by the substructure and the superstructure can achieve a composite action responding as a single structural unit; the elimination of expansion joint and bearings on the abutments, greatly reduce the construction and maintenance costs. To maximize the benefits from integral abutment...

  9. Effect of abutment modeling on the seismic response of bridge structures

    Institute of Scientific and Technical Information of China (English)

    Ady Aviram; Kevin R.Mackie; Bozidar Stojadinovic

    2008-01-01

    Abutment behavior significantly influences the seismic response of certain bridge structures.Specifically in the case of short bridges with relatively stiff superstructures typical of highway overpasses,embankment mobilization and inelastic behavior of the soil material under high shear deformation levels dominate the response of the bridge and its column bents.This paper investigates the sensitivity of bridge seismic response with respect to three different abutment modeling approaches.The abutment modeling approaches are based on three increasing levels of complexity that attempt to capture the critical components and modes of abutment response without the need to generate continuum models of the embankment,approach,and abutment foundations.Six existing reinforced concrete bridge structures,typical of Ordinary Bridges in California,are selected for the analysis.Nonlinear models of the bridges are developed in OpenSees.Three abutment model types of increasing complexity are developed for each bridge,denoted as roller,simplified,and spring abutments.The roller model contains only single-point constraints.The spring model contains discrete representations of backfill,bearing pad,shear key,and back wall behavior.The simplified model is a compromise between the efficient roller model and the comprehensive spring model.Modal,pushover,and nonlinear dynamic time history analyses are conducted for the six bridges using the three abutment models for each bridge.Comparisons of the analysis results show major differences in mode shapes and periods,ultimate base shear strength,as well as peak displacements of the column top obtained due to dynamic excitation.The adequacy of the three abutment models used in the study to realistically represent all major resistance mechanisms and components of the abutments,including an accurate estimation of their mass,stiffness,and nonlinear hysteretic behavior,is evaluated.Recommendations for abutment modeling are made.

  10. Simplified modelling of bridge abutments-soil interaction under seismic effects

    OpenAIRE

    Martínez Cutillas, Antonio; Alarcón Álvarez, Enrique

    1995-01-01

    A simplified model is proposed to show the importance that the dynamic soil-abutment interaction can have in the global behavior of bridges submitted to seismic loading. The modification of natural frequency and damping properties is shown in graphic form for typical short span bridges of the integral deck-abutment type for longitudinal vibrations or general ones for transverse vibrations.

  11. Reduction of Bridge Construction and Maintenance Costs through Coupled Geotechnical and Structural Design of Integral Abutment Bridges

    OpenAIRE

    Frosch, Robert J; Bobet, Antonio; Khasawneh, Yazen

    2014-01-01

    Elimination expansion joints in the superstructure of integral abutment bridges offers the advantage of reducing the initial and life cycle costs of the structure. However, such elimination may have an adverse effect on the displacement demand at the pile-abutment connection and on the earth pressures on the abutment wall due to the thermal expansion/contraction cycles of the bridge. These adverse effects have resulted in regulations that impose restrictions on the maximum length and skew ang...

  12. Soil Structure Interaction for Integral Abutment Bridge Using Spring Analogy Approach

    International Nuclear Information System (INIS)

    The reaction of the backfill behind the abutments and adjacent to the piles plays a significant role in the behavior of the Integral bridge. The handling of soil-structure interaction in the analysis and design of integral abutment bridges has always been problematic due to its complexity. This study describes the implementation of a 2-D finite element model of IAB system which explicitly incorporates the soil response. The superstructure members and the pile have been represented by means of three-node isoperimetric beam elements with three degree of freedom per node. The Eight node isoperimetric quadrilateral element has been used to model the abutment. The backfill was idealized by uncoupled 'Winkler' spring. The applic1ability of this model is demonstrated by analyzing a single span IA bridge. The results have shown that the shear forces at the tops of the supported piles were only 12% to 16% of the load which at the top of abutment.

  13. Soil Structure Interaction for Integral Abutment Bridge Using Spring Analogy Approach

    Energy Technology Data Exchange (ETDEWEB)

    Thanoon, W A [Faculty Engineering, Nizwa University (Oman); Abdulrazeg, A A; Jaafar, M S; Kohnehpooshi, O [Department of Civil Engineering, University Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Noorzaei, J, E-mail: jamal@eng.upm.edu.my [Institute of Advance Technology, University Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2011-02-15

    The reaction of the backfill behind the abutments and adjacent to the piles plays a significant role in the behavior of the Integral bridge. The handling of soil-structure interaction in the analysis and design of integral abutment bridges has always been problematic due to its complexity. This study describes the implementation of a 2-D finite element model of IAB system which explicitly incorporates the soil response. The superstructure members and the pile have been represented by means of three-node isoperimetric beam elements with three degree of freedom per node. The Eight node isoperimetric quadrilateral element has been used to model the abutment. The backfill was idealized by uncoupled 'Winkler' spring. The applic1ability of this model is demonstrated by analyzing a single span IA bridge. The results have shown that the shear forces at the tops of the supported piles were only 12% to 16% of the load which at the top of abutment.

  14. Local scour around bridge abutments under ice covered condition- an experimental study

    Institute of Scientific and Technical Information of China (English)

    Peng WU; Faye HIRSHFIELD; Jue-yi SUI

    2015-01-01

    The local scour around bridge abutments has been an active research topic for many decades. But very few studies have been conducted regarding the impacts of ice cover on the local scour phenomenon around bridge abutments. A series of ice covered flume experiments were conducted in this study. The shape factors of different abutment types in the local scour were compared. Under ice cover, the shape factor for semi-circular abutments ranges from 0.66~0.71. Three different non-uniform sediments were used withD50s of 0.58 mm, 0.50 mm, and 0.47 mm respectively. Two types of ice cover, namely smooth and rough cover, were created to simulate the impacts of ice cover around the abutments. Maximum scour depth was analyzed under different conditions. The contours of the scour holes were plotted to show the bed morphology and sediment deposition around bridge abutments. An empirical relationship between maximum scour depth, densimetric Froude number and sediment size was developed.

  15. Economical bridge solutions based on innovative composite dowels and integrated abutments ecobridge

    CERN Document Server

    Băncilă, Radu

    2015-01-01

    This book is an outcome of the research project “ECOBRIDGE – Demonstration of ECOnomical BRIDGE solutions based on innovative composite dowels and integrated abutments – RFCS – CT 2010-00024”, which has been co-funded by the Research Fund for Coal and Steel (R.F.C.S.) of the European Community. The main topics of the book are the following: design of integral bridges, innovative composite dowels for the shear transmission, construction of bridges, structural analysis of bridges and monitoring. The book joins the technical experience and the contributions of the involved research partners. The technical content of all the papers is present-day in the field of the design, construction and monitoring of innovative composite bridges. The efficient design and construction improve and consolidate the market position of steel construction and steel producing industry. In addition, the advanced forms of construction are contributing to savings in material and energy consumption for the structure during prod...

  16. Combination of natural teeth and osseointegrated implants as prosthesis abutments in a posterior cantilever bridge

    Directory of Open Access Journals (Sweden)

    Michael Josef Kridanto Kamadjaja

    2008-06-01

    Full Text Available Dental implants have been used for several decades. Patients of all ages have chosen dental implants to replace a single tooth or several teeth or to support partial or full dentures. This paper reports two cases of patients treated with dental implant as alternative to replace the missing teeth and connected with natural tooth as abutments in a fixed restoration with distal cantilever bridge. The underlining reasons that we decided to make such kind fixed prostheses are because of clinically imposible to put the implant on certain area and the patients asked for prostheses as optimum as possible, so the mastication function could return to the homeostasis condition. The benefit of these treatments are that prostheses could be made as optimum as possible with a more economic price, so the patients feel quite satisfied. The result shows that a few years after the treatments finished there is no any disadvantageous effect of connecting teeth to implants as abutments in fixed partial dentures and there is no sign of a harmful effect to the opposing teeth either.

  17. Effect of Abutment Taper on the Fracture Resistance of all-Ceramic Three-unit Bridges

    Directory of Open Access Journals (Sweden)

    F. Gerami-Panah

    2005-12-01

    Full Text Available Statement of Problem: The connector area is the weakest zone of an all-ceramic fixed partial denture (FPD, where most catastrophic failures of the prostheses tend to occur.Purpose: The aim of the present study was to assess the effect of the convergence angle of abutments on the fracture resistance of three-unit fixed partial dentures made of IPSEmpress2.Materials and Methods: Forty extracted human premolars and molars were used to reproduce twenty, 3-unit fixed partial dentures, for the replacement of second premolars. All teeth were prepared according to the guidelines outlined for all-ceramic crowns and bridges, except for the convergence angles of the abutments. The specimens were randomly divided into two groups of 10, with total occlusal convergence angles of 12° and 22°. Fixed partial dentures with a uniform thickness of 0.8 mm were fabricated using IPS-Empress2 and were bonded to the corresponding models. Connectordimensions were set to 4 mm height and 4mm width. The radius of curvature at the gingival embrasure was carved to 0.9 mm. All specimens were exposed to 10,000 preloading cycles and a load of 40 N at a frequency of 1.3 Hz in a standardized testing machine at a cross head speed of 1mm/min. Student t-test was performed to detect any difference in the mean fracture resistance between the two groups (α = 0.05.Results: Mean failure loads (and standard deviations of the 12° and 22° groups were 1009.12 N (208.05 and 1182.72 N (144.67, respectively. Statistical analysis revealed a significant difference (P <0.04 between the mean failure loads of the two groups. Mostfractures occurred through the connectors.Conclusion: The mean failure loads of the investigated fixed partial dentures were higher in the abutments with 22° taper as compared to those with a taper of 12°.

  18. "EFFECTS OF FLOW INTENSITY, OBSTACLE ALIGNMENT AND CROSS-SECTION GEOMETRY ON SCOUR AT BRIDGE ABUTMENTS" CARDOSO, A.H., SANTOS, J.S. and ROCA, M.

    Institute of Scientific and Technical Information of China (English)

    Bruce W. MELVILLE

    2002-01-01

    The authors present new measurements of maximum (equilibrium) local scour depth at bridge abutments, the new data being analysed in terms of the multiplying factors given in Melville (1992,1997) and Melville and Coleman (2000). The design method presented in these publications is referred to here as the University of Auckland (UoA) Method. The authors' data apply to the following factors:∏f (flow intensity), ∏θ (abutment alignment) and ∏g (approach channel geometry).

  19. Live-Load Testing Application Using a Wireless Sensor System and Finite-Element Model Analysis of an Integral Abutment Concrete Girder Bridge

    Directory of Open Access Journals (Sweden)

    Robert W. Fausett

    2014-01-01

    Full Text Available As part of an investigation on the performance of integral abutment bridges, a single-span, integral abutment, prestressed concrete girder bridge near Perry, Utah was instrumented for live-load testing. The live-load test included driving trucks at 2.24 m/s (5 mph along predetermined load paths and measuring the corresponding strain and deflection. The measured data was used to validate a finite-element model (FEM of the bridge. The model showed that the integral abutments were behaving as 94% of a fixed-fixed support. Live-load distribution factors were obtained using this validated model and compared to those calculated in accordance to recommended procedures provided in the AASHTO LRFD Bridge Design Specifications (2010. The results indicated that if the bridge was considered simply supported, the AASHTO LRFD Specification distribution factors were conservative (in comparison to the FEM results. These conservative distribution factors, along with the initial simply supported design assumption resulted in a very conservative bridge design. In addition, a parametric study was conducted by modifying various bridge properties of the validated bridge model, one at a time, in order to investigate the influence that individual changes in span length, deck thickness, edge distance, skew, and fixity had on live-load distribution. The results showed that the bridge properties with the largest influence on bridge live-load distribution were fixity, skew, and changes in edge distance.

  20. Effect of Abutment Taper on the Fracture Resistance of all-Ceramic Three-unit Bridges

    OpenAIRE

    F. Gerami-Panah; H. Jalali; L. Sedighpour

    2005-01-01

    Statement of Problem: The connector area is the weakest zone of an all-ceramic fixed partial denture (FPD), where most catastrophic failures of the prostheses tend to occur.Purpose: The aim of the present study was to assess the effect of the convergence angle of abutments on the fracture resistance of three-unit fixed partial dentures made of IPSEmpress2.Materials and Methods: Forty extracted human premolars and molars were used to reproduce twenty, 3-unit fixed partial dentures, for the rep...

  1. EFFECTS OF FLOW INTENSITY, OBSTACLE ALIGNMENT AND CROSS-SECTION GEOMETRY ON SCOUR AT BRIDGE ABUTMENTS

    Institute of Scientific and Technical Information of China (English)

    A. H. CARDOSO; J. S. SANTOS; M. ROCA

    2002-01-01

    Experiments are reported on the effects of flow intensity, obstacle alignment and cross-section geome try on the equilibrium scour depth around abutments. The effect of flow intensity was studied for clear water flow conditions, the obstacle alignment was studied for a wide range of angles of the obstacle with the flow direction, and tests on the cross-section geometry apply only to the case where the abut ment extends into the main channel of a compound cross-section (two-stage channel). The channel bank and flood plain were built up with sand. The hypothesis of zero scour for flow velocities smaller than approximately 50% of the threshold velocity for the beginning of motion in the approaching flow cannot be rejected; maximum scour occurs for obstacles protruding at right angle from the cross-section walls, the reduction being small when obstacles point upstream; compared with rigid banks, the scour depth seems to be significantly reduced when channel bank and flood plain are constituted of alluvial material.

  2. EPS材料在防治桥头跳车中的应用%Application of EPS Material in the Control of Vehicle Jumping at Bridge Abutment

    Institute of Scientific and Technical Information of China (English)

    焦莉

    2012-01-01

    EPS (Expanded Polystyrene)materials have the properties of super light, water resistance, antt-ageing and good mechanical property and convenience in construction. Because of its good properties.EPS has been widely used in decreasing the different settlement at the bridge abutment and preventing the jump at the bridge abutment. To ensure effective application of EPS, the embankment fill should be executed according to constructing quality standard.%EPS材料具有超轻、耐水,不易老化、力学性能良好和施工便捷等优点,在处理桥台和路基相接处差异沉降,防治桥头跳车中得到广泛应用.为保证EPS应用效果,路基应按照施工质量标准进行填筑.

  3. Local scour at abutments: A review

    Indian Academy of Sciences (India)

    Abdul Karim Barbhuiya; Subhasish Dey

    2004-10-01

    Failure of bridges due to local scour has motivated many investigators to explore the causes of scouring and to predict the maximum scour depth at abutments. In this paper, a detailed review of the up-to-date work on scour at abutments is presented including all possible aspects, such as flow field, scouring process, parameters affecting scour depth, time-variation of scour and scour depth estimation formulae.

  4. 高肋板式桥台静载试验与分析%The Static Load Test and Analysis of the High Rib-plate-shaped Bridge Abutment

    Institute of Scientific and Technical Information of China (English)

    王解军; 刘昕炜; 李旺

    2015-01-01

    In view of the high rib-plate-shaped bridge abutment of the simple supported beam bridge in an engineering example,taking the ribbed slab,the pile cap and the pile foundation into con-sideration,we use the finite element software,MIDAS /CIVIL,to build the solid element model,which we calculate the horizontal displacement and stress under the load.With the vehicle load making the stat-ic load test,we use the total station to measure the horizontal displacement of the abutment on the top, and using the resistance strain gauge to measure the stress of the ribbed slab.By comparing the experi-mental results with the theoretical value,we make the technical condition evaluation of bridge abutment.%针对某工程实例简支梁桥的高肋板式桥台,采用有限元软件 MIDAS /CIVIL,考虑肋板、承台及桩基础,建立桥台结构实体有限元模型,对荷载作用下肋板的水平位移和应力进行计算分析。对桥台进行静载试验,采用车辆加载,全站仪测试台顶水平位移,电阻应变计与应变仪测试肋板应力。通过实测结果与理论值的对比分析,对桥台的技术状况进行评定。

  5. The clinical study on abutment dentin hypersensitivity after preparation for crown and bridge%冠桥基牙制备后牙本质敏感的临床治疗研究

    Institute of Scientific and Technical Information of China (English)

    邓文正; 郭庆; 陆辉; 邱伟芳

    2013-01-01

    Objective To evaluate the effects of professional oral allergy desensitization paste for treating abutment dentin hypersensitivity after preparation for Crown and bridge.Methods 226 patients,repaired by porcelain Crown and bridge,were randomly divided into test group and control group,n =113.Test group:Professional oral allergy desensitization paste was used after tooth preparation and before bonding the ceramic Crown and bridge,for 113 cases.Control group:Gluma desensitizer was used after tooth preparation and before bonding the ceramic Crown and bridge,for 113 cases.Adopted cold air blowing,dentin sensitivity was evaluated by recording the value of visual analogue pain scores (VAS).Results The abutment sensitivity of the test group,by using desensitizing paste therapy after tooth preparation,significantly reduced.The abutment sensitivity after desensitizing paste therapy was statistically significant compared with that of before using desensitization paste and control group (P<0.001).The abutment sensitivity of test group was statistically significant compared with that of control group after the ceramic Crown and bridge was bonded (P<O.O01).Conclusion Professional oral allergy desensitization paste has good effect on treating abutment dentin hypersensitivity after preparation for Crown and bridge.%目的:评价抗敏口腔专业用脱敏膏对于烤瓷冠桥基牙制备后牙本质过敏的治疗疗效.方法:选取做烤瓷冠桥修复的226例患者,随机分为实验组和对照组,各113例.实验组:113例备牙后和烤瓷冠桥粘固前使用抗敏口腔专业用脱敏膏进行脱敏.对照组:113例备牙后、烤瓷冠桥粘固前使用Gluma脱敏剂脱敏.牙本质敏感度的评价采用冷空气喷吹法,记录视觉模拟疼痛评分(visual analogue scale,VAS)值.结果:实验组于备牙后使用脱敏膏治疗基牙敏感显著降低,与使用前对照组比较差异有统计学意义(P<0.001);与对照组相比,实验组粘固后基牙敏

  6. Evaluation on Impact Interaction between Abutment and Steel Girder Subjected to Nonuniform Seismic Excitation

    OpenAIRE

    Yue Zheng; Xiang Xiao; Lunhai Zhi; Guobo Wang

    2015-01-01

    This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abut...

  7. Glass fiber-reinforced abutments for dental implants. A pilot study.

    Science.gov (United States)

    Behr, M; Rosentritt, M; Lang, R; Handel, G

    2001-04-01

    Titanium abutments in dental implants shine through all-ceramic crowns and therefore limit excellent esthetic results. Prototypes of tooth-colored fiber-reinforced abutments were investigated to avoid the shining-through effect. In vitro, the fracture strength was determined after thermal cycling and mechanical loading of all-ceramic single crowns and four-unit bridges made of a fiber-reinforced composite. The suprastructures were adhesively fixed onto fiber-reinforced implant abutments and compared with those fixed on standard titanium abutments. The median of the fracture strength of the titanium-supported all-ceramic crowns was significantly higher than the median of crowns fixed onto the prototypes. But this value was still more than twice as high as the maximum loading force under oral conditions. No statistical difference was found between four-unit bridges made by fiber-reinforced composite inserted onto titanium abutments and those inserted onto fiber-reinforced abutments. Fiber-reinforced abutment prototypes for dental implants avoided the shining-through effect associated with metal abutments. Their load-bearing capacity after in vitro stress simulation was higher than the maximum oral loading force. With some improvements, the fiber-reinforced implant abutments are therefore a promising alternative to titanium abutments. PMID:11251668

  8. Velocity and turbulence at a wing-wall abutment

    Indian Academy of Sciences (India)

    Abdul Karim Barbhuiya; Subhasish Dey

    2004-02-01

    Experimental investigation of the 3D turbulent flow field around a 45° wing-wall abutment, resting on a rough rigid bed, is reported. The experiment was conducted in a laboratory flume using the Acoustic Doppler Velocimeter (ADV). Profiles of time-averaged velocity components, turbulent intensity components, turbulent kinetic energy and Reynolds stresses at different azimuthal planes are presented. Vector plots of flow fields at azimuthal and horizontal planes show the presence of a primary vortex associated with the downflow in the upstream side of the abutment and a wake vortex on the downstream side. The shear stresses acting on the bed around the abutment are estimated from the Reynolds stresses and velocity gradients. The data presented in this study would be useful to researchers for future development and comparison of theoretical models of flow fields around bridge abutments.

  9. 不同载荷下天然牙一种植牙联合桥基牙应力分布%Stress Distribution on Abutment of Tooth- Implant Fixed Bridge Under Different Loading

    Institute of Scientific and Technical Information of China (English)

    胡建军; 周延民; 王志彪; 张理生; 孟维艳; 周振平

    2001-01-01

    目的:揭示天然牙一种植体联合支持固定桥在不同载荷下基牙的应力反应规律,指导临床优化设计。方法:采用三维有限元方法建模型计算、分析。结果:斜向载荷下种植体的最大应力值是天然牙的2~2.5倍,集中斜向载荷与分散斜向载荷下种植体最大应力值无明显差异,是垂直载荷下种值体最大应力值2~2.5倍。集中垂直载荷下天然牙、种植体的最大应力值高于分散垂直载荷下的最大应力值。天然牙集中斜向载荷下最大应力值大于分散斜向载荷下的最大应力值。结论:天然牙一种植体联合桥承受侧向力的能力弱,种值体应具有高强度,天然牙根应粗大,减小侧向力;集中载荷比分散f荷破坏作用大,桥体与基牙的骆面咬合接触点应分布均匀,建立多点咬合接触。%To discovery the stress distribution on the abutments of tooth - implant fixed bridge under differ ent loading.Method: By 3- D finite element modeling computed and analyzed .Results: Under oblique loading, stress on the implant was 2 ~ 2.5 times as big as on tooth. There was no significant deviation of the biggest stress on the implant between concentrated oblique loading and oblique dispered loading. The biggest stress on implant under concentrated oblique loading was 2 ~ 2.5 times as big as vertical laoding. Both tooth and implant, the stress under concentrated vertical loading was bigger than under dispersed vertical loading. On the tooth, stress under concentrated oblique loading was bigger than under dispersed oblique loading. Conclusion:The ability of supporting oblique force for tooth- implant fixed bridge is weak. Implant should be of higher strength, tooth root should be stronger, oblique force should be less. Distruction of condentrated loading for abutment is more serious than dispersed loading. The bite points should be well distributed.

  10. VORTEX FLOW FIELD IN A SCOUR HOLE AROUND ABUTMENTS

    Institute of Scientific and Technical Information of China (English)

    Abdul Karim BARBHUIYA; Subhasish DEY

    2003-01-01

    The three-dimensional flow field in a scour hole around different abutments under a clear water regime was experimentally measured in a laboratory flume, using the Acoustic Doppler Velocimeter (ADV). Three types of abutments used in the experiments were vertical-wall (rectangular section), 45° wing-wall (45° polygonal section) and semicircular. The threedimensional time-averaged velocity components were detected at different vertical planes for vertical-wall abutment and azimuthal planes for wing-wall and semicircular abutments. The velocity components were also measured at different horizontal planes. In the upstream, presentations of flow field through vector plots at vertical / azimuthal and horizontal planes show the existence of a primary vortex associated with the downflow inside the scour hole. On the other hand, in the downstream, the flow field shows a reversed flow near the abutments having a subsequent recovery with a passage of flow as a part of the main flow. The data presented in this paper would be useful to the researchers for the development and verification of mathematical models of flow field in a scour hole at bridge abutments.

  11. 双端固定桥两基牙牙周膜厚度分别不同时的生物力学分析%Biomechanical Analysis of the Stress Distribution of Rigid Fixed Bridge During Different Thickness of Periodontal Membranes Around Abutments

    Institute of Scientific and Technical Information of China (English)

    刘建平; 冯晓刚; 王乐

    2011-01-01

    Objective: To study the effects of the different thickness of periodontal membranes around abutments to stress distribution of rigid fixed bridge. Methods: Two-dimensional images of mandible bones, teeth and periodontal supporting tissue of healthy people were scanned by spiral CT. Three-dimensional digital model was developed by imaging software. The three-dimensional finite element model of fixed denture on mandible posterior teeth was then developed. Stress distribution of fixed bridge loaded with the same vertical and horizontal forces was analyzed during different thickness of periodontal membranes around abutments. Results: There were no apparent differences in stress between the fixed bridge abutments and the surface of alveolar bones when the thickness of periodontal membrane around the abutments were less than 0.1 mm.When the thickness of periodontal membranes were between 0.1 mm and 0.4 mm, the stress of the alveolar bones surface reduced with the increase of the thickness of periodontal membranes, and there was a non-linear relationship between them. There was no change in the stress of the alveolar bones surface with the increase of the thickness of periodontal membranes when the thickness was more than 0.4 mm. Conclusions: Periodontal membranes around abutments exhibited cushioning effect when their thicknesses were in certain area. When it was too thicker or thinner, the cushioning effect will disappear.%目的:研究双端固定桥两基牙牙周膜厚度分别不同时对固定桥各部位应力分布的影响.方法:采用螺旋CT扫描获取健康人下颌骨、牙齿及牙周支持组织的二维图像,通过图像合成软件建立三维数字模型,并应用三维有限元分析软件生成下颌后牙固定桥的三维有限元分析模型.在相同垂直载荷和水平载荷情况下,分析两基牙牙周膜厚度分别不同时固定桥的应力分布.结果:当基牙牙周膜厚度小于0.1mm时固定桥基牙与牙槽骨表面应力大小

  12. An introduction to single implant abutments.

    LENUS (Irish Health Repository)

    Warreth, Abdulhadi

    2013-01-01

    This article is an introduction to single implant abutments and aims to provide basic information about abutments which are essential for all dental personnel who are involved in dental implantology. Clinical Relevance: This article provides a basic knowledge of implants and implant abutments which are of paramount importance, as replacement of missing teeth with oral implants has become a well-established clinical procedure.

  13. Comparison of Fracture Resistance and Failure Mode of Different Zirconia Abutments with Titanium Abutment

    Directory of Open Access Journals (Sweden)

    Ghasem Omati Shabestari

    2013-02-01

    Full Text Available Background and Aims: One of the decicive factors on the final esthetic results of implant treatment is theabutment material. Ceramic abutments are nowadays very popular in this regard. The purpose of this study was tocompare the fracture resistance of three zirconia abutments with titanium abutment.Materials and Methods: Four groups of abutments 4 recorded for each specimen. The data were analyzed using One-way ANOVA.Results: The mean values recorded for fracture resistance of different zirconia abutments varied between 426 to688 N; however, there was no significant differences among the groups

  14. Evaluation on Impact Interaction between Abutment and Steel Girder Subjected to Nonuniform Seismic Excitation

    Directory of Open Access Journals (Sweden)

    Yue Zheng

    2015-01-01

    Full Text Available This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abutment and the girder. The detailed nonlinear finite element (FE model is established and the steel girder and the reinforced concrete piers are modeled by nonlinear fiber elements. The pounding element of the abutment is simulated by using a trilinear compression gap element. The elastic-perfectly plastic element is used to model the nonlinear rubber bearings. The comparisons of the pounding forces, the shear forces of the nonlinear bearings, the moments of reinforced concrete piers, and the axial pounding stresses of the steel girder are studied. The made observations indicate that the nonuniform excitation for multisupport bridge is imperative in the analysis and evaluation of the pounding effects of the bridges.

  15. Jointless and Smoother Bridges: Behavior and Design of Piles

    OpenAIRE

    Frosch, Robert J; Chovichien, Voraniti; Durbin, Katrinna; Fedroff, David

    2006-01-01

    Integral abutment bridges have been used in the United States for decades. By eliminating expensive expansion joints, the piles supporting the end bent accommodate the total thermal movement of the bridge. Currently, integral bridges are designed based upon experience, and a rational design specification has not been developed. Furthermore, the interaction of the abutment, pile, and soil remains uncertain. A better understanding regarding the behavior of this system is needed. The objective o...

  16. A Stress Analysis on Abutment Teeth of Dowel Cemented Fixed Partial Dentures : On the effect of the resorption of alveoar bone

    OpenAIRE

    KATAOKA, SHIGERU; KOSAKA, SHIGERU; TSUCHIYA, SOHICHIRO; AMARI, MITSUHARU

    1995-01-01

    Stress in abutment teeth with cemented dowels and those with crown margins in fixed-fixed and cantilever bridges that resorp alveolar bone were analyzed by a two dimensional finite element method. Stress in all parts of the dentin in both bridges increased with the resorption of alveolar bone. Moreover, in th dentin and apex of the dowel in cantilever bridges, extreme stress when there were large amounts of resorption of alveolar bone, was seen. Therefore, in cantilevers bridges, cemented dow...

  17. Effect of vegetated-banks on local scour around a wing-wall abutment with cir-cular edges

    Institute of Scientific and Technical Information of China (English)

    AFZALIMEHR Hossein; BAKHSHI Somayeh; GALLICHAND Jacques; SUI Jueyi

    2014-01-01

    Failure of bridges due to local scour in the vicinity of bridge abutments is a common occurrence. In this study, experime-nts under two different channel conditions were conducted to assess the impacts of vegetation on channel banks on local scour around a wing-wall abutment with circular edges. Some experiments were conducted in channel with vegetation on channel banks, and other experiments in channel without vegetation on channel bank. The flow velocity and Reynolds stress distributions in scour holes around a wing-wall abutment with circular edges were compared under these 2 different channel conditions. Results reveal that the vegetated-banks can reduce the time for achieving the equilibrium condition from 17 h to 9 h. Also, vegetated-bank channels can result in a significant decrease in the maximum scour depth from 0.084 m (for bare channel bank) to 0.00032 m. Additionally, around the abutment, vegetated-banks play a significant role in diminishing the Reynolds stress (RS) near the bed and removing negative values in RS distribution by weakening unfavorable pressure gradient and down-flow in the upstream of abutment.

  18. Laboratory technique for coloring titanium abutments to improve esthetics.

    Science.gov (United States)

    Wadhwani, Chandur P K; O'Brien, Richard; Kattadiyil, Mathew T; Chung, Kwok-Hung

    2016-04-01

    Titanium alloys are used for implant abutments onto which prostheses are attached. One major disadvantage of titanium abutments is their esthetics; the metallic gray color may show through the restorative material or through surrounding tissues. A laboratory technique using readily available household items is described that can alter the abutment color by anodization. PMID:26723096

  19. 21 CFR 872.3630 - Endosseous dental implant abutment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Endosseous dental implant abutment. 872.3630... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3630 Endosseous dental implant abutment. (a) Identification. An endosseous dental implant abutment is a premanufactured prosthetic...

  20. Clinical Use of Laser-Microtextured Abutments: A Case Series.

    Science.gov (United States)

    Shapoff, Cary A; Babushkin, Jeffrey A; Wohl, David J

    2016-01-01

    This article discusses the clinical use of laser-microtextured abutments on dental implant restorations. Four cases are presented, each using one of the four commercially available laser-microtextured abutment styles. Numerous preclinical and clinical studies have shown the positive effects of laser microtexturing on the implant platform in limiting crestal bone loss and benefiting soft tissue stability. Other histologic studies of laser microtexturing on the implant abutment have demonstrated the ability of this specific feature to block epithelial downgrowth and provide a functional connective tissue attachment to the abutment surface. Other abutment designs, styles, and materials have only demonstrated a soft tissue seal with epithelial adhesion and a circular ring of connective tissue fibers around the abutment without direct contact. This article presents clinical and radiographic case examples from a private practice perspective on the longterm successful use of microtextured abutments with respect to crestal bone levels, exceptional soft tissue health, and stability with minimal sulcular depth. PMID:27560683

  1. Abrasion of abutment screw coated with TiN

    OpenAIRE

    Jung, Seok-Won; Son, Mee-Kyoung; Chung, Chae-Heon; Kim, Hee-Jung

    2009-01-01

    STATEMENT OF PROBLEM Screw loosening has been a common complication and still reported frequently. PURPOSE The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly m...

  2. Scour and Scour Countermeasures at Bridge Sites

    Institute of Scientific and Technical Information of China (English)

    CHIEW Yee-Meng

    2008-01-01

    This paper examines scour and scour countermeasures at bridge piers and abutments.Abutment scour is by far more complex than its counterpart associated with piers because of the possibility of the presence of a floodplain. Notwithstanding this, the mechanism of scour at both piers and abutments is very similar; moreover, the failure mechanisms associated with both armor-ing and flow-altering countermeasures are not very different. In rivers with a floodplain, abutment scour becomes much more complex. In cases where the abutment ends at or near to the flood-plain, it can initiate bank erosion, which clearly is an important erosion problem that is quite distinct from the customary scour at either an abutment in rivers without a floodplain or a pier. For this rea-son, abutment scour can be very site-specific while pier-scour is more generic in nature. To this end, the ability to identify the type of abutment scour that may form in a particular channel is closely related to an engineer's ability to propose devices for effective scour countermeasure.By summarizing research efforts on using riprap as a pier or abutment countermeasure over the past few decades, this paper highlights the deficiencies of riprap in arresting pier scour. To this end,different failure mechanisms are identified. They are shear failure, winnowing failure, edge failure,bedform-induced failure and bed-degradation induced failure. Each failure mechanism can singly or, more likely, combine to cause the eventual breakdown of the riprap layer. The study shows that a riprap layer is vulnerable to other failure mechanisms even though it is adequately designed against shear failure, rendering it ineffective in arresting scour.

  3. Implant adaptation of stock abutments versus CAD/CAM abutments: a radiographic and Scanning Electron Microscopy study

    Science.gov (United States)

    Apicella, Davide; Veltri, Mario; Chieffi, Nicoletta; Polimeni, Antonella; Giovannetti, Agostino; Ferrari, Marco

    2011-01-01

    Summary Introduction The study evaluated a null-hypothesis of no differences of fit between stock abutments and CAD/CAM titanium, gold sputtered and zirconia abutments when examined for radiographic adaptation and Scanning Electron Microcopy (SEM) at their inner aspect. The agreement between microscopic and radiographic fit was also assessed. Methods Implants (Osseospeed, Astra Tech, Mölndal, Sweden) were connected to titanium abutments (Ti-design, Astra Tech, Mölndal, Sweden) (control group n=12), to stock zirconia abutments (Zir-design, Astra Tech) (group 1 n=12) and to third party zirconia abutments (Aadva Zr abutment, GC, Tokyo, Japan) as observed under SEM (JEOL JSM-6060LV, Tokyo, Japan). Two independent operators blindly evaluated the images, according to a three-score scale: perfect adaptation, no complete adaptation, and clear evidence of no adaptation. A Kruskal-Wallis test was applied to assess significant differences in adaptation scores between the groups. Results All specimens showed precise SEM adaptation at all tested interfaces and no radiographically apparent gaps. No significant differences were found and therefore the null-hypothesis tested was accepted. Radiographic and SEM scores were in agreement. Discussion CAD/CAM titanium, gold sputtered and zirconia abutments and third-part CAD/CAM zirconia abutments show an adaptation to Astra Tech implants that is comparable to that of stock titanium and zirconia abutments. Clinicians might be able to verify such adaptation with an x-ray. In-vivo studies would be needed to evaluate the clinical outcome of CAD/CAM abutments. PMID:22238709

  4. Clinical evaluation of isolated abutment teeth in removable partial dentures

    Directory of Open Access Journals (Sweden)

    Zarrati S

    2011-02-01

    Full Text Available "nBackground and Aims: Nowadays, removable partial dentures are applied to patients who are not able to use dental implants or fixed prosthesis. Although based on the studies the users of removable partial dentures are in the risk of plaque accumulation and unacceptable changes such as gingivitis, periodontitis and mobility in abutment tooth. It is not clear whether the negative effects of removable partial dentures are more on the isolated teeth which are a kind of abutment adjacent to endentulous area in both sides. The purpose of this study was to investigate the clinical condition of isolated abutment teeth without splinting in comparison to control abutment from the aspects of B.O.P (bleeding on probing, mobility, pocket depth and gingivitis."nMaterials and Methods: In this cross-sectional study, the prepared questionnaires were filled out by 50 patients who received removable partial dentures in department of removable prosthodontics of dental school of Tehran University of Medical Sciences. The patients had isolated abutment tooth and did not have any systemic disease. The obtained data were analyzed. Using Wilcoxon, exact Fisher and Kruskal-Wallis test."nResults: B.O.P (P=0.004, pocket depth (P=0.035, and mobility (P<0.001 in isolated abutments were more than those in control abutments, but there were not significant differences in the degree of caries (P=0.083 and gingivitis (P=0.07."nConclusion: This study showed that clinical condition of isolated abutments is worse than that of control abutments. More attention should be paid to healthiness of isolated teeth without splinting and periodic follow ups should be done in these cases.

  5. Distribution of lateral floor abutment pressure in a stope

    Institute of Scientific and Technical Information of China (English)

    Zhang Hualei; Wang Lianguo; Sun Jian

    2011-01-01

    In order to study the distribution of lateral floor abutment pressure at a working face, we first used elasticity theory to establish a distribution model of lateral floor abutment pressure and then analysed its distribution. Second, we established a three-dimensional numerical simulation model of the Haizi Coal Mine No. 86 mining area by using FLAC3D (ITASCA Consulting Group) software. We investigated the distribution of lateral floor abutment pressure of a stope, which indicated that the position of abutment pressure peak varies at different floor depths. We then determined the rational reinforcement range of a floor roadway, based on the conclusion reached earlier. Finally, we used our conclusions in support of the No. 86 mining area crossing-roadway. The supported crossing-roadway remained stable when mining the upper workface, which validates the accuracy of our numerical simulation and provides a future reference for the support of span-roadways under similar conditions.

  6. Mechanical testing of thin-walled zirconia abutments

    Directory of Open Access Journals (Sweden)

    Luigi CANULLO

    2013-01-01

    Full Text Available Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bi-component aesthetic abutments has been suggested. Objective Mechanical testing of customized thin-walled titanium-zirconia abutments at the connection with the implant was performed in order to characterize the fatigue behavior and the failure modes for straight and angled abutments. Material and Methods Twenty custom-made bi-component abutments were tested according to ISO 14801:2007 either at a straight or a 25° angle inclination (n=10 each group. Fatigue was conducted at 15 Hz for 5 million cycles in dry conditions at 20°C±5°C. Mean values and standard deviations were calculated for each group. All comparisons were performed by t-tests assuming unequal variances. The level of statistical significance was set at p≤0.05. Failed samples were inspected in a polarized-light and then in a scanning electron microscope. Results Straight and angled abutments mean maximum load was 296.7 N and 1,145 N, the dynamic loading mean Fmax was 237.4 N and 240.7 N, respectively. No significant differences resulted between the straight and angled bi-component abutments in both static (p=0.253 and dynamic testing (p=0.135. A significant difference in the bending moment required for fracture was detected between the groups (p=0.01. Fractures in the angled group occurred mainly at the point of load application, whereas in the straight abutments, fractures were located coronally and close to the thinly designed areas at the cervical region. Conclusion Angled or straight thin-walled zirconia abutments presented similar Fmax under fatigue testing despite the different bending moments required for fracture. The main

  7. Clinical evaluation of isolated abutment teeth in removable partial dentures

    OpenAIRE

    Zarrati S; Baheri Mghadam T; Nematollahi F

    2011-01-01

    "nBackground and Aims: Nowadays, removable partial dentures are applied to patients who are not able to use dental implants or fixed prosthesis. Although based on the studies the users of removable partial dentures are in the risk of plaque accumulation and unacceptable changes such as gingivitis, periodontitis and mobility in abutment tooth. It is not clear whether the negative effects of removable partial dentures are more on the isolated teeth which are a kind of abutment adjacent to ...

  8. Periodontal and pulpal conditions of abutment teeth. Status after four to eight years following the incorporation of fixed reconstructions.

    Science.gov (United States)

    Reichen-Graden, S; Lang, N P

    1989-01-01

    In the present retrospective clinical study, 58 patients were examined 4 to 8 years (median 77 months) following the incorporation of a fixed reconstruction. No regular maintenance care had been provided during the interval period. The periodontal conditions represented by the Plaque Control Record (PCR), the Gingival Index (GI) and pocket probing depths were examined on 182 abutment teeth of 94 reconstructions. Pulpal vitality and periapical pathology were assessed clinically as well as radiographically. The periodontal parameters of the abutment teeth were compared with homologous contralateral uncrowned teeth. Significantly higher plaque prevalence, gingival indices, and pocket probing depths were found in the crowned teeth. Also, bleeding on probing was observed more frequently whenever the crown margins were located subgingivally. At the end of the interval period, 3.7% of the originally vital abutments had lost their vitality. A technical failure rate of 7.4% with no apparent differences between conventional and extension bridges was noted. This study indicates that even with precise marginal fit and in the absence of a regular maintenance program, the supragingival location of the crown margin is more favourable than the subgingival location for the maintenance of oral health. PMID:2701195

  9. Stress distribution among periodontally compromised abutments: A comparative study using three-dimensional finite element analysis

    Directory of Open Access Journals (Sweden)

    Rajkiran Chitumalla

    2012-01-01

    Full Text Available Aims: The aim of the study was to evaluate the stress distribution patterns in teeth and supporting structures of fixed prosthesis and design modifications in a fixed prosthesis with either normal or reduced bone support of an additional abutment. Study was also undertaken to disprove Ante′s law. Materials and Methods: Main models and variations of main models (modification 1, 2, 3, 4, 5, 6, 7, 8 were subjected to 200 N at angulations of 90° and 15° on functional cusps. Results for each loading were obtained as stress distribution color images and numerical values were recorded. A three-dimensional finite element analysis study of variations of normal models was performed using two finite element softwares, namely PRO-Engineer wildfire version 1.0 manufacturer: Parametric technology corporation, Needham, MA 02494 U.S.A. Results: When periodontal compromised abutment teeth was splinted with an additional abutment an increase of stress was observed in periodontally compromised abutments so an additional abutment is not required. Eventhough the pericemental area of compromised abutments with an additional abutment (canine was more than the combined pericemental area of pontics to be replaced, stress generated was more on abutments. This disproves Ante′s law. Hence, it may be a reference, but should not be the ultimate criterion in determining the number of multiple abutments. Conclusions: When periodontal compromised abutment teeth was splinted with an additional abutment an increase of stress was observed in periodontally compromised abutments so an additional abutment is not required. Even though the pericemental area of compromised abutments with an additional abutment (canine was more than combined pericemental area of pontics to be replaced, stress generated was more on abutments. This disproves Ante′s law. Hence, it may be a reference, but should not be the ultimate criterion in determining the number of multiple abutments.

  10. The applicability of PEEK-based abutment screws.

    Science.gov (United States)

    Schwitalla, Andreas Dominik; Abou-Emara, Mohamed; Zimmermann, Tycho; Spintig, Tobias; Beuer, Florian; Lackmann, Justus; Müller, Wolf-Dieter

    2016-10-01

    The high-performance polymer PEEK (poly-ether-ether-ketone) is more and more being used in the field of dentistry, mainly for removable and fixed prostheses. In cases of screw-retained implant-supported reconstructions of PEEK, an abutment screw made of PEEK might be advantageous over a conventional metal screw due to its similar elasticity. Also in case of abutment screw fracture, a screw of PEEK could be removed more easily. M1.6-abutment screws of four different PEEK compounds were subjected to tensile tests to set their maximum tensile strengths in relation to an equivalent stress of 186MPa, which is aused by a tightening torque of 15Ncm. Two screw types were manufactured via injection molding and contained 15% short carbon fibers (sCF-15) and 40% (sCF-40), respectively. Two screw types were manufactured via milling and contained 20% TiO2 powder (TiO2-20) and >50% parallel orientated, continuous carbon fibers (cCF-50). A conventional abutments screw of Ti6Al4V (Ti; CAMLOG(®) abutment screw, CAMLOG, Wimsheim, Germany) served as control. The maximum tensile strength was 76.08±5.50MPa for TiO2-20, 152.67±15.83MPa for sCF-15, 157.29±20.11MPa for sCF-40 and 191.69±36.33MPa for cCF-50. The maximum tensile strength of the Ti-screws amounted 1196.29±21.4MPa. The results of the TiO2-20 and the Ti screws were significantly different from the results of the other samples, respectively. For the manufacturing of PEEK abutment screws, PEEK reinforced by >50% continuous carbon fibers would be the material of choice. PMID:27434650

  11. [Interproximal tooth cleansing of abutment teeth and pontic design].

    Science.gov (United States)

    Kocher, T; Plagmann, H C; Engelsmann, U; Schlüter, R

    1990-03-01

    This clinical study was an attempt to find out if a patient's home care plaque control at his or her abutment tooth is more effectively enhanced by a modified ridge lap or a hygienic pontic design. Oral hygiene was performed either with a tooth brush alone or in combination with an interdental brush. We found that the effectivity of interproximal toothcleaning was not influenced by the pontic design and that only interdental brushes permit a good plaque control at the proximal area of the abutment tooth. This implies that "self cleansing" is non-existent in these tooth areas. PMID:2257819

  12. Replacing worn overdenture abutments of an unknown implant system by using laser welding: a clinical report.

    Science.gov (United States)

    Mohunta, Vrinda V; Stevenson, James A; Lee, Damian J

    2014-09-01

    This clinical report describes a procedure for replacing worn ball abutments with low-profile resilient abutments by using laser welding when the implant system for a mandibular implant-supported overdenture could not be identified. PMID:24836281

  13. Field test and numerical analysis on behaviors of low-cap pile foundation supporting bridged abutment subjected to embankment load%低承台桥台桩基侧向受力性状试验与数值分析

    Institute of Scientific and Technical Information of China (English)

    聂如松; 冷伍明; 杨奇; 岳健

    2012-01-01

    Based on field test results, a three-dimensional finite element method was set up to explore the settlement of the pile foundation, the bending moment of the piles, the horizontal movement of pile head, shear force and earth pressure on pile shafts with increasing embankment load behind the abutment wall. The results show that the calculated and measured results agree well; the lateral deformation of pile head and maximum bending moment of pile with the increase of embankment load increases linearly. In 20 m depth, the distribution of shear force along the pile depth is in "S" shaped pattern, the distribution of the earth pressure along the depth direction is of a parabola. The mechanical model of low-cap pile foundation is equivalent with the statically indeterminate beam of the pile head and pile embedded in a certain depth soil. The conclusions can be helpful and give references for pile design and construction.%基于现场测试结果,采用三维有限元技术分析低承台桥台桩基在台后路基填土过程中桩基沉降、桩身弯矩、桩顶水平变形、桩身剪力和桩侧附加水平挤压力随台后填土荷载增加的变化规律.研究结果表明:计算结果与实测结果吻合较好:桩顶水平变形和桩身最大弯矩随填土荷载的增加近似呈线性增加:深度方向20m范围内,桩身剪力图呈“S”型,桩侧附加水平挤压力图呈抛物线型.低承台桥台桩基力学模型等同于桩项和桩端嵌入一定深度、具有一定变位的超静定梁结构.本文所得结论可以为桥台桩基的设计和施工提供参考.

  14. Removal of failed crown and bridge.

    Science.gov (United States)

    Sharma, Ashu; Rahul, G R; Poduval, Soorya T; Shetty, Karunakar

    2012-07-01

    Crown and bridge have life span of many years but they fail for a number of reasons. Over the years, many devices have been designed to remove crowns and bridges from abutment teeth. While the removal of temporary crowns and bridges is usually very straightforward, the removal of a definitive cast crown with unknown cement is more challenging. Removal is often by destructive means. There are a number of circumstances, however, in which conservative disassembly would aid the practitioner in completing restorative/endodontic procedures. There are different mechanisms available to remove a failed crown or bridge. But there is no information published about the classification of available systems for crown and bridge removal. So it is logical to classify these systems into different groups which can help a clinician in choosing a particular type of system depending upon the clinical situation. The aim of this article is to provide a classification for various crown and bridge removal systems; describe how a number of systems work; and when and why they might be used. A PubMed search of English literature was conducted up to January 2010 using the terms: Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. Additionally, the bibliographies of 3 previous reviews, their cross references as well as articles published in various journals like International Endodontic Journal, Journal of Endodontics and were manually searched. Key words:Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. PMID:24558549

  15. Acrylic resin guide for locating the abutment screw access channel of cement-retained implant prostheses.

    Science.gov (United States)

    Ahmed, Ayman; Maroulakos, Georgios; Garaicoa, Jorge

    2016-05-01

    Abutment screw loosening represents a common and challenging technical complication of cement-retained implant prostheses. This article describes the fabrication of a simple and accurate poly(methyl methacrylate) guide for identifying the location and angulation of the abutment screw access channel of a cement-retained implant prosthesis with a loosened abutment screw. PMID:26794698

  16. AN INTEGRATED APPROACH FOR SIMULATING AND PREDICTING SCOUR AROUND ABUTMENTS

    Institute of Scientific and Technical Information of China (English)

    L.Q.ZHANG; D.H.ZHAO; H.W.SHEN

    2006-01-01

    A new experimental and numerical approach to predict scour around abutments located either in the floodplain of a compound channel or in a rectangular channel was investigated. A prediction equation for the scour around abutments was proposed on the basis of the experimental study. A special horizontal two-dimensional (2D) numerical model was combined with the experimental studies. The 2D model is based on the principles of the finite volume method with Riemann solvers. The corrections to account for the impacts of the hydrostatic pressure assumption, turbulence, and three-dimensional behavior were embedded in the 2D model. The proposed prediction equation is based on both experimental and numerical techniques for estimation of scour depths in cases with different channel geometries and abutment lengths under various flow conditions. A comparison was done of the measured scour depths from the experiments and the calculated scour depths from the prediction equation. It was proved that the scour depths predicted with the proposed equation matched better with the measured values than another similar prediction equation.

  17. Railroad Bridges

    Data.gov (United States)

    Department of Homeland Security — Bridges-Rail in the United States According to The National Bridge Inspection Standards published in the Code of Federal Regulations (23 CFR 650.3), a bridge isA...

  18. Distribution of Side Abutment Stress in Roadway Subjected to Dynamic Pressure and Its Engineering Application

    OpenAIRE

    Yao Qiangling; Zhou Jian; Li Yanan; Tan Yingming; Jiang Zhigang

    2015-01-01

    The borehole stress-meter was employed in this study to investigate the distribution of the side abutment stress in roadway subjected to dynamic pressure. The results demonstrate that the side abutment stress of the mining roadway reaches a peak value when the distance to the gob is 8 m and the distribution curve of the side abutment stress can be divided into three zones: stress rising zone, stress stabilizing zone, and stress decreasing zone. Further numerical investigation was carried out ...

  19. Effect of Abutment Modification and Cement Type on Retention of Cement-Retained Implant Supported Crowns

    OpenAIRE

    Mitra Farzin; Kianoosh Torabi; Ahmad Hasan Ahangari; Reza Derafshi

    2014-01-01

    Objective: Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations. Materials and Method: Two prefabricated abutments were attached to their corresponding analogs and embedded in an ac...

  20. Effect of abutment modification and cement type on retention of cement-retained implant supported crowns.

    Directory of Open Access Journals (Sweden)

    Mitra Farzin

    2014-06-01

    Full Text Available Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations.Two prefabricated abutments were attached to their corresponding analogs and embedded in an acrylic resin block. The first abutment (control group was left intact without any modifications. The screw access channel for the first abutment was completely filled with composite resin. In the second abutment, (test group the axial wall was partially removed to form an abutment with 3 walls. Wax models were made by CAD/CAM. Ten cast copings were fabricated for each abutment. The prepared copings were cemented on the abutments by Temp Bond luting agent under standardized conditions (n=20. The assemblies were stored in 100% humidity for one day at 37°C prior to testing. The cast crown was removed from the abutment using an Instron machine, and the peak removal force was recorded. Coping/abutment specimens were cleaned after testing, and the testing procedure was repeated for Dycal luting agent (n=20. Data were analyzed with two- way ANOVA (α=0.05.There was no significant difference in the mean transformed retention (Ln-R between intact abutments (4.90±0.37 and the abutments with 3 walls (4.83±0.25 using Dycal luting agent. However, in TempBond group, the mean transformed retention (Ln-R was significantly lower in the intact abutment (3.9±0.23 compared to the abutment with 3 walls (4.13±0.33, P=0.027.The retention of cement-retained implant restoration can be improved by the type of temporary cement used. The retention of cast crowns cemented to implant abutments with TempBond is influenced by the wall removal.

  1. [Arthroscopic distal ulna resection after post traumatic ulno carpal abutment].

    Science.gov (United States)

    Mathoulin, C; Pagnotta, A

    2006-11-01

    Ulno carpal abutments secondary to the sequels of a fracture of the radius are often due to the inversion of the distal radio ulnar index by shortening relative to the radius. This positive ulnar variance eventually leads to an abutment between the head of the ulnar and the proximal articular face of the lunate with alteration of the cartilaginous carpal surfaces. The wrist arthroscopy makes diagnosis and treatment possible in a less invasive way. The patients are operated on as outpatients under local regional anaesthetic using a pneumatic tourniquet. The arthroscope is positioned using the 3-4 radio carpal opening permitting exploration of the joint. The surgical treatment is performed by arthroscopy using a burr and going in through the 6R radio carpal opening. In this way we use the technique of partial resection of the distal ulna. We have a series of 62 patients who have benefited from the technique of partial resection of the ulnar head by arthroscopy. There were 30 men and 32 women. The average age was 66 years old (between 45 and 82). Our average follow-up is 32 months (between 12 and 60 months). Recovery of mobility was immediate in all cases with persistent pain in the radio ulnar joint in 8 cases. Arthroscopic treatment of ulno carpal abutment has proved itself effective and innocuous. It should nevertheless be reserved for operations on small sized inversions of the distal radio ulnar index (less than 5 mm). In the event of larger ulnar variances we prefer ulnar shortening osteotomy. The other techniques will be restricted to cases where the distal radio ulnar joint has been impaired. PMID:17361890

  2. Retrofit of existing railway bridges of short to medium spans for high-speed traffic using viscoelastic dampers

    OpenAIRE

    MOLINER CABEDO, EMMANUELA; Museros Romero, Pedro; MARTÍNEZ RODRIGO, MARÍA DE LOS DOLORES

    2012-01-01

    This paper presents a study on the energy-absorbing capacities of viscoelastic dampers (VEDs) for reducing the resonant vibrations of simply supported high-speed railway bridges of short to medium span. The proposed solution is based on retrofitting the bridge with a set of discrete VEDs connected to the slab and to an auxiliary structure, placed underneath the bridge deck and resting on the abutments. In this investigation attention is focused on mitigating flexural vibrations; therefore, bo...

  3. Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone

    Directory of Open Access Journals (Sweden)

    Eduardo Aloisio Fleck NEUMANN

    2014-08-01

    Full Text Available Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1, polyetheretherketone (PEEK screws (Group 2, and 30% carbon fiber-reinforced PEEK screws (Group 3. The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey’s range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p 0.05. Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

  4. Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

    Directory of Open Access Journals (Sweden)

    Marcos Michelon Naconecy

    2010-04-01

    Full Text Available OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1 parallel vertical implants, and 2 tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm. The deformation values were measured when the metallic frameworks were tested over three, four or five abutments, and transformed into force and bending moment values. Data were analyzed by ANOVA and Tukey's test for multiple comparisons at 5% level of significance. RESULTS: Abutment #1 (adjacent to the cantilever had the highest values of force and sagittal bending moment for all tests with three, four or five abutments. Independently from the number of abutments, axial force in abutment #1 was higher in the vertical model than in the tilted model. Total moment was higher with three abutments than with four or five abutments. Independently from the inclination of implants, the mean force with four or five abutments was lower than that with three abutments. CONCLUSION: The results suggest that in the set-ups with four or five abutments tilted distal implants reduced axial force and did not increase bending moments.

  5. Beam-edge modifier for abutting electron fields

    International Nuclear Information System (INIS)

    Abutment of unmodified electron fields to irradiate large areas can lead to significant dose inhomogeneities in the region of junction of the fields. In this paper we describe the design and dosimetric characteristics of a device developed to broaden the electron beam penumbra and thereby to improve the dose uniformity in the overlap region. The device is a high-density triangular-toothed comb capable of reducing the beam intensity without seriously degrading the beam energy. The effect of the comb is such that a single device will generate a beam penumbra which is broad and very nearly linear at all depths for all clinically used beam energies. Results are shown for various field configurations and energies. With a gap of 5.0 cm between the treatment cone and phantom surface the dose ''ripple'' in the region beneath the teeth was found not to exceed +- 5% at 0.5-cm depth

  6. Assessment of the NCHRP abutment scour prediction equations with laboratory and field data

    Science.gov (United States)

    Benedict, Stephen T.

    2014-01-01

    The U.S. Geological Survey, in coopeation with nthe National Cooperative Highway Research Program (NCHRP) is assessing the performance of several abutment-scour predcition equations developed in NCHRP Project 24-15(2) and NCHRP Project 24-20. To accomplish this assssment, 516 laboratory and 329 fiels measurements of abutment scor were complied from selected sources and applied tto the new equations. Results will be used to identify stregths, weaknesses, and limitations of the NCHRP abutment scour equations, providing practical insights for applying the equations. This paper presents some prelimiray findings from the investigation.

  7. A Simple Method for Making Diagnostic Casts for Dental Implants Using Acrylic Abutments

    Directory of Open Access Journals (Sweden)

    H. Siadat

    2007-06-01

    Full Text Available The use of multiple implants in the same jaw requires a detailed knowledge of abutment angulation. The position and angulation of the abutments play an important role in treatment planning and fabrication of the custom tray. Therefore diagnostic casts thatcontain cover screws may cause problems during implant therapy.The current article describes a technique for making a preliminary cast with acrylic custom abutments in order to help the clinician select an appropriate impression technique and evaluate the location and angulations of the implant bodies. This method can also aid the technician to provide adequate and proper space for the fabrication of an open custom tray.

  8. Non-rigid connector in fixed partial dentures with pier abutment: An enigma simplified

    Directory of Open Access Journals (Sweden)

    Prince Kumar

    2012-01-01

    Full Text Available In the fixed partial denture (FPD prosthesis with rigid connectors, forces of mastication are transmitted to the terminal retainers, which make the middle abutment act as a class I lever fulcrum. This techno-clinical cycle often causes failure of the fixed partial dentures. To overcome this dilemma, a non-rigid connector may be incorporated on the distal aspect of the middle (pier abutment. The non-rigid connector counterbalances the effects of these forces of leverage. This clinical report presents the use of a non-rigid connector in a long-span, five-unit FPD, replacing two missing teeth with an intermediate pier abutment.

  9. 氧化锆基台在种植体支持的全瓷修复中的应用%The application of zirconia abutment in implant supported all - ceramic restoration

    Institute of Scientific and Technical Information of China (English)

    王大山; 杨建军; 邓悦; 吴品林; 杨振; 杨凤丽; 张慧敏

    2011-01-01

    目的 探讨氧化锆基台的应用及种植体支持的全瓷修复体的临床效果.方法 选择安多键内连接种植系统φ4.0×10ram种植体植入缺牙区,上颌植入6个月、下颌植入3个月后安装自制的氧化锆基台;将基台予以磨改预留修复间隙,取印模,灌制石膏模型;应用CAD/CAM制作全瓷冠、桥;将全瓷修复体与基台粘接固位;应用MINRAY口内数字X线摄片系统和X线摄片定位仪,拍摄安装氧化锆基台时和全瓷修复体粘接后36个月时的X线片进行测量,对比分析.结果 自制的氧化锆基台能与种植体顺利装配,应用该基台和CAD/CAM制作的全瓷冠、桥修复体完成的15例患者18颗种植义齿全瓷修复的即刻效果满意,追踪30-36个月,所有患者的种植义齿使用良好,修复体和基台均无松动脱落与折裂、折断,牙周无炎症及牙槽骨吸收,部分患者的牙槽骨显示增高,患者满意度高.结论 应用氧化锆基台配合CAD/CAM氧化锆全瓷冠、桥修复体,不仅可获得满意的美学效果,还有益于种植义齿周围组织的健康.%Objective ThiS study is to discuss the application of zirconia abutment and Lhe clinical results of the implant supponed all - ceramic restoration.Methods Embed the Anthogyr inter - joins implant system ( φ 4.0 × 10mm)into the edentulous region, install the self - made zirconia abutment after 6 months maxilla implantation or 3 months mandible implantation; Then the abutment is ground to reserve restoration space and the impression is made to cast plaster mould; Make the all - ceramic crown/ bridge by CAD/CAM before adhere and fix the all - ceramic restoration with the abutment; Use MINRAY digital X - ray shooting system and X - ray holders system to shoot X - ray at the time of zirconia abutment installation and 36 months after the adhesion of the all - ceramic restoration then carry out measurement and comparative analysis.Results The self - made zirconia abutment can match well

  10. Torque Removal Evaluation of Screw in One-Piece and Two-Piece Abutments Tightened with a Handheld screwdriver

    Directory of Open Access Journals (Sweden)

    Jalil Ghanbarzadeh

    2013-12-01

    Full Text Available Introduction: Some clinicians use a handheld screw driver instead of a torque wrench to definitively tighten abutment screws. The aim of this study was to compare the removal torque of one-piece and two-piece abutments tightened with a handheld driver and a torque control ratchet. Methods: 40 ITI implants were placed in acrylic blocks and divided into 4 groups. In groups one and two, 10 ITI one-piece abutments (Solid® and in groups three and four, 10 ITI two-piece abutments (Synocta® were placed on the implants. In groups one and three abutments were tightened by 5 experienced males and 5 experienced females using a handheld driver. In groups two and four abutments were tightened using a torque wrench with torque values of 10, 20 and 35 N.cm. Insertion torque and removal torque values of the abutments were measured with a digital torque meter. Results: The insertion torque values (ITVs of males in both abutments were significantly higher than those of females. ITVs in both Solid® and Synocta® abutments tightened with a handheld screwdriver were similar to the torque of 20 N.cm in the torque wrench. Removal torque values (RTVs of solid® abutments were higher than those of synocta® abutments. Conclusion: The one- piece abutments (solid® showed higher RTVs than the two-piece abutments (synocta®. Hand driver does not produce sufficient preload force for the final tightening of the abutment

  11. Marginal Vertical Fit along the Implant-Abutment Interface: A Microscope Qualitative Analysis

    Directory of Open Access Journals (Sweden)

    Nicola Mobilio

    2016-09-01

    Full Text Available The aim of this study was to qualitatively evaluate the marginal vertical fit along two different implant-abutment interfaces: (1 a standard abutment on an implant and (2 a computer-aided-design/computer-aided-machine (CAD/CAM customized screw-retained crown on an implant. Four groups were compared: three customized screw-retained crowns with three different “tolerance” values (CAD-CAM 0, CAD-CAM +1, CAD-CAM −1 and a standard titanium abutment. Qualitative analysis was carried out using an optical microscope. Results showed a vertical gap significantly different from both CAD-CAM 0 and CAD-CAM −1, while no difference was found between standard abutment and CAD-CAM +1. The set tolerance in producing CAD/CAM screw-retained crowns plays a key role in the final fit.

  12. DEEP COLLIERY PRESSURE BUMPS AND ITS PREVENTIONS UNDER THE ACTION OF ABUTMENT PRESSURE

    Institute of Scientific and Technical Information of China (English)

    杜计平; 张先尘; 田昌栋; 闫培华

    1999-01-01

    Based on field measurement, the relations was introduced between mining depth and the peak value places of abutment pressures in long wall face of the deep colliery with caving method to handle goaf, and the reasons and kinds of pressure bumps are analysed under the action of the moving and constant abutment pressures formed by the method of long wall caving or room and pillar mining, and the relative precautions were put forward to prevent the pressure bumps in deep mining.

  13. The Influence of Post in Endodontically Treated Molar Abutment on Fixed Dentures Success Rate

    OpenAIRE

    Pralita Kusumawardhini; Alysia Henrietta; Saraventi Saraventi

    2013-01-01

    Many dentists believe that the tooth need reinforcement provided by post before the definite restoration is placed. However, others suggest not to use post when posterior teeth especially molars, still have significant amount of tooth structure. Therefore, when endodontically treated molar is considered to be used as fixed denture abut-ment, clinicians must have proper knowledge about the impact of post placement. This literature will describe considerations regarding post placement in endodo...

  14. Non-rigid connector in fixed partial dentures with pier abutment: An enigma simplified

    OpenAIRE

    Prince Kumar; Vishal Singh; Roshni Goel; Harkanwal P Singh

    2012-01-01

    In the fixed partial denture (FPD) prosthesis with rigid connectors, forces of mastication are transmitted to the terminal retainers, which make the middle abutment act as a class I lever fulcrum. This techno-clinical cycle often causes failure of the fixed partial dentures. To overcome this dilemma, a non-rigid connector may be incorporated on the distal aspect of the middle (pier) abutment. The non-rigid connector counterbalances the effects of these forces of leverage. This clinical report...

  15. A Retrospective Study of Implant–Abutment Connections on Crestal Bone Level

    OpenAIRE

    Lin, M.-I.; Shen, Y.-W.; Huang, H.-L.; Hsu, J.-T.; Fuh, L.-J.

    2013-01-01

    This study compared the effects of external hex, internal octagon, and internal Morse taper implant–abutment connections on the peri-implant bone level before and after the occlusal loading of dental implants. Periapical radiographs of 103 implants (63 patients) placed between 2002 and 2010 were collected, digitized, standardized, and classified into groups based on the type of implant–abutment connection. These radiographs were then analyzed with image-processing software to measure the peri...

  16. Myocardial Bridging

    Directory of Open Access Journals (Sweden)

    Shi-Min Yuan

    2016-02-01

    Full Text Available Abstract Myocardial bridging is rare. Myocardial bridges are most commonly localized in the middle segment of the left anterior descending coronary artery. The anatomic features of the bridges vary significantly. Alterations of the endothelial morphology and the vasoactive agents impact on the progression of atherosclerosis of myocardial bridging. Patients may present with chest pain, myocardial infarction, arrhythmia and even sudden death. Patients who respond poorly to the medical treatment with β-blockers warrant a surgical intervention. Myotomy is a preferred surgical procedure for the symptomatic patients. Coronary stent deployment has been in limited use due to the unsatisfactory long-term results.

  17. Mechanical properties of alumina-zirconia composites for ceramic abutments

    Directory of Open Access Journals (Sweden)

    Maria Cecilia Corrêa de Sá e Benevides de Moraes

    2004-12-01

    Full Text Available The need for new materials to substitute injured or damaged parts of the human body has led scientists of different areas to investigate bioceramics since the 70's, when other materials in use started to show rejection problems. Ceramics show some advantages like being the material that best mimics the bone tissue, although present low toughness when compared with the metallic materials. As patients have become more and more demanding regarding esthetic and biocompatibility aspects of their dental restorations, ceramic material has become a main object of scientific interest especially from the material point of view. The alumina-zirconia composites are one of the relatively good and promising candidate for biomaterials application, due to biocompatibility and their mechanical properties that combines high flexural strength with a high toughness. The aim of the present work is to analyze the mechanical properties of these composites, where Y-TZP zirconia content was varied from 5 to 80 wt.% These systems can achieve a flexural strength 93 % and fracture toughness 29 % superior when compared to the pure alumina ceramics. These results showed that ceramic abutments components can be prepared for prosthetic rehabilitations with dental implants.

  18. Determination of Abutment Pressure in Coal Mines with Extremely Thick Alluvium Stratum: A Typical Kind of Rockburst Mines in China

    Science.gov (United States)

    Zhu, Sitao; Feng, Yu; Jiang, Fuxing

    2016-05-01

    This paper investigates the abutment pressure distribution in coal mines with extremely thick alluvium stratum (ETAS), which is a typical kind of mines encountering frequent intense rockbursts in China. This occurs due to poor understanding to abutment pressure distribution pattern and the consequent inappropriate mine design. In this study, a theoretical computational model of abutment pressure for ETAS longwall panels is proposed based on the analysis of load transfer mechanisms of key stratum (KS) and ETAS. The model was applied to determine the abutment pressure distribution of LW2302S in Xinjulong Coal Mine; the results of stress and microseismic monitoring verified the rationality of this model. The calculated abutment pressure of LW2302S was also used in the terminal mining line design of LW2301N for rockburst prevention, successfully protecting the main roadway from the adverse influence of the abutment pressure.

  19. Fatal complications after stereotactic body radiation therapy for central lung tumors abutting the proximal bronchial tree

    Science.gov (United States)

    Haseltine, Justin M.; Rimner, Andreas; Gelblum, Daphna Y.; Modh, Ankit; Rosenzweig, Kenneth E.; Jackson, Andrew; Yorke, Ellen D.; Wu, Abraham J.

    2016-01-01

    Purpose Stereotactic body radiation therapy (SBRT) is associated with excess toxicity following treatment of central lung tumors. Risk-adapted fractionation appears to have mitigated this risk, but it remains unclear whether SBRT is safe for all tumors within the central lung zone, especially those abutting the proximal bronchial tree (PBT). We investigated the dependence of toxicity on tumor proximity to PBT and whether tumors abutting the PBT had greater toxicity than other central lung tumors after SBRT. Materials and methods A total of 108 patients receiving SBRT for central lung tumors were reviewed. Patients were classified based on closest distance from tumor to PBT. Primary endpoint was SBRT-related death. Secondary endpoints were overall survival, local control, and grade 3+ pulmonary adverse events. We compared tumors abutting the PBT to nonabutting and those ≤1 cm and >1 cm from PBT. Results Median follow-up was 22.7 months. Median distance from tumor to PBT was 1.78 cm. Eighty-eight tumors were primary lung and 20 were recurrent or metastatic; 23% of tumors were adenocarcinoma and 71% squamous cell. Median age was 77.5 years. Median dose was 4500 cGy in 5 fractions prescribed to the 100% isodose line. Eighteen patients had tumors abutting the PBT, 4 of whom experienced SBRT-related death. No other patients experienced death attributed to SBRT. Risk of SBRT-related death was significantly higher for tumors abutting the PBT compared with nonabutting tumors (P 1cm from PBT (P = .014). Conclusions Even with risk-adapted fractionation, tumors abutting PBT are associated with a significant and differential risk of SBRT-related toxicity and death. SBRT should be used with particular caution in central-abutting tumors, especially in the context of anti-vascular endothelial growth factor therapy. PMID:26577006

  20. The Influence of Post in Endodontically Treated Molar Abutment on Fixed Dentures Success Rate

    Directory of Open Access Journals (Sweden)

    Pralita Kusumawardhini

    2013-05-01

    Full Text Available Many dentists believe that the tooth need reinforcement provided by post before the definite restoration is placed. However, others suggest not to use post when posterior teeth especially molars, still have significant amount of tooth structure. Therefore, when endodontically treated molar is considered to be used as fixed denture abut-ment, clinicians must have proper knowledge about the impact of post placement. This literature will describe considerations regarding post placement in endodontically treated molar abutment in fixed partial dentures and their influence to the success rate. Previous studies implied the need of proper measurement of the amount of remaining tooth structure, the type of intracoronal reinforcement of the abutment, and the functional loads to ensure the success of fixed denture treatment. When planning definitive restorations for endodontically treated abutment teeth, some even suggest to use post and core to fulfill the need of reinforcement. On the contrary, others find that when a post is use in endodontically treated abutment teeth, the failure of custom made-tapered cast post and core is relatively high, whereas the use of amalgam or composite core in posterior teeth especially molars with adequate amount of tooth structure is sufficient due to post system’s limited influence on the suc-cess rate. Based on literature review, for cases with adequate tooth stucture, it can be concluded that the influ-ence of post placement in endodontically treated molar abutment to fixed partial dentures success rate is very limited.DOI: 10.14693/jdi.v18i2.64

  1. A digital approach to fabricating an abutment replica to control cement volume in a cement-retained implant prosthesis.

    Science.gov (United States)

    Lee, Ju-Hyoung; Park, In-Sook; Sohn, Dong-Seok

    2016-07-01

    If a cement-retained implant prosthesis is placed on an abutment, excess cement should be minimized or removed to prevent periimplant inflammation. Various methods for fabricating an abutment replica have been introduced to maintain tissue health and reduce clean-up time. The purpose of this article is to present an alternative technique for fabricating an abutment replica with computer-aided design/computer-aided manufacturing (CAD/CAM) technology. PMID:26946917

  2. Radiologic Evaluation of Bone Loss at Implants with Biocide Coated Titanium Abutments: A Study in the Dog

    OpenAIRE

    López-Píriz, R.; Bartolomé, J. F.; Cabal, B.; Esteban-Tejeda, L.; Torrecillas, Ramón; J. S. Moya

    2012-01-01

    The objective of the present study is to evaluate bone loss at implant abutments coated with a soda-lime glass containing silver nanoparticles subjected to experimental peri-implantitis. Five beagle dogs were used in the experiments, 3 implants were installed in each quadrant of the mandibles. Glass/n-Ag coted abutments were connected to implant platform. Cotton floss ligatures were placed in a submarginal position around the abutment necks and the animals were subject to a diet which allowed...

  3. The Effect of Abutment Surface Roughness on the Retention of Implant-Supported Crowns Cemented with Provisional

    Directory of Open Access Journals (Sweden)

    Seyyed Mohammad Abrisham

    2012-09-01

    Full Text Available Introduction: Surface roughness can increase the retention of castings by ridges and grooves that are microretentive. This study compared the retention of implant-supported crowns when used with 3 different surface roughness abutments and one temporary cement. Methods: Thirty solid abutments (ITI, 4 mm high, were divided into three groups randomly. In the first group, 10 abutments were roughened with sandblast (50-µm aluminum oxide and in the second group, 10 abutments were roughened with diamond bur. The third group had no surface treatment. Then, thirty implant fixture analogs (ITI were placed in the center of acrylic cylinders. After that a solid abutment was tightened on the each fixture analog with 35 N/cm force. Thirty base metal crowns were made on the 4 mm ITI abutment analogs using plastic coping. The prepared copings were cemented on the abutments by TempBond temporary cement and finally, crowns were pulled from the abutment in a universal test machine at a cross speed of 0.5cm/min. Results: The mean tensile strength in sandblasted, bur treated, and control group were 64.38±8, 91.37±7.19, and 58.61±1.93, respectively. Bur treated group showed higher tensile strength in comparison with two other groups. Conclusion: Surface modification of implant abutment by diamond bur may be an effective method to increase retention of crown when TempBond is used.

  4. Evaluation of the marginal fit at implant-abutment interface by optical coherence tomography

    Science.gov (United States)

    Kikuchi, Keisuke; Akiba, Norihisa; Sadr, Alireza; Sumi, Yasunori; Tagami, Junji; Minakuchi, Shunsuke

    2014-05-01

    Vertical misfit of implant-abutment interface can affect the success of implant treatment; however, currently available modalities have limitations to detect these gaps. This study aimed to evaluate implant-abutment gaps in vitro using optical coherence tomography (OCT). Vertical misfit gaps sized 50, 100, 150, or 200 μm were created between external hexagonal implants and titanium abutments (Nobel Biocare, Göteborg, Sweden). A porcine gingival tissue slice, 0.5, 1.0, 1.5, or 2.0 mm in thickness, was placed on each implant-abutment interface. The gaps were evaluated by swept-source OCT at a center wavelength of 1330 nm (Panasonic Healthcare, Ehime, Japan) with beam angles of 90, 75 and 60 deg to the implant long-axis. The results suggested that while the measurements were precise, gap size and gingival thickness affected the sensitivity of detection. Gaps sized 100 μm and above could be detected with good accuracy under 0.5- or 1.0-mm-thick gingiva (GN). Around 70% of gaps sized 150 μm and above could be detected under 1.5-mm-thick GN. On the other hand, 80% of gaps under 2.0-mm-thick GN were not detected due to attenuation of near-infrared light through the soft tissue. OCT appeared as an effective tool for evaluating the misfit of implant-abutment under thin layers of soft tissue.

  5. Non-linear 3D evaluation of different oral implant-abutment connections.

    Science.gov (United States)

    Streckbein, P; Streckbein, R G; Wilbrand, J F; Malik, C Y; Schaaf, H; Howaldt, H P; Flach, M

    2012-12-01

    Micro-gaps and osseous overload in the implant-abutment connection are the most common causes of peri-implant bone resorption and implant failure. These undesirable events can be visualized on standardized three-dimensional finite element models and by radiographic methods. The present study investigated the influence of 7 available implant systems (Ankylos, Astra, Bego, Brånemark, Camlog, Straumann, and Xive) with different implant-abutment connections on bone overload and the appearance of micro-gaps in vitro. The individual geometries of the implants were transferred to three-dimensional finite element models. In a non-linear analysis considering the pre-loading of the occlusion screw, friction between the implant and abutment, the influence of the cone angle on bone strain, and the appearance of micro-gaps were determined. Increased bone strains were correlated with small (< 15°) cone angles. Conical implant-abutment connections efficiently avoided micro-gaps but had a negative effect on peri-implant bone strain. Bone strain was reduced in implants with greater wall thickness (Ankylos) or a smaller cone angle (Bego). The results of our in silico study provide a solid basis for the reduction of peri-implant bone strain and micro-gaps in the implant-abutment connection to improve long-term stability.

  6. Bridge Management Systems

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper bridge management systems are discussed with special emphasis on management systems for reinforced concrete bridges. Management systems for prestressed concrete bridges, steel bridges, or composite bridges can be developed in a similar way.......In this paper bridge management systems are discussed with special emphasis on management systems for reinforced concrete bridges. Management systems for prestressed concrete bridges, steel bridges, or composite bridges can be developed in a similar way....

  7. Programmevaluierung Bridge

    OpenAIRE

    Warta, Katharina; Good, Barbara; Geyer, Anton

    2009-01-01

    BRIDGE is an initiative funded by the Ministry for Transport, Innovation and Technology (BMVIT) that aims to close the “funding gap” between basic and applied research in stand-alone projects with the primary objective of jointly developing the potential of basic and applied research. BRIDGE acts as an  umbrella structure under which the Austrian Science Fund (FWF) and the  Austrian Research Promotion Agency (FFG) coordinate two thematically open funding programmes: The ...

  8. D型便梁加固既有桥台施工技术%Type D beam strengthened with abutment construction technology

    Institute of Scientific and Technical Information of China (English)

    张留

    2014-01-01

    Bao Xi railway double track two Dao Gou Bridge Abutment with both type D beam reinforcement, through the relationship between old and new, on line analysis of existing line is busy and so on, elaborates the technical measures of temporary pier construction, beam transport and installation, safety protection to ensure the operation safety of the line.%包西铁路复线二道沟大桥既有桥台采用D型便梁加固,通过对新旧线路关系、既有线路繁忙情况等方面的分析,详细阐述了临时支墩施工、便梁的运输及安装、既有线安全防护等确保线路运营安全的技术措施。

  9. A comparative radiographic evaluation of the titanium and zirconium implant-abutment gap of three different implant connections

    Directory of Open Access Journals (Sweden)

    Majid Sahebi

    2016-07-01

    Full Text Available Background and Aims: In response to esthetic demand and use of zirconia abutments; detection of implant-abutment connection misfit is so important. The purpose of this study was to evaluate the sensitivity and specificity of radiographic images in the detection of abutment-implant connection misfit in zirconia and titanium abutments of three different implant connections. Materials and Methods: One regular implant fixture of Branemark, Noble active and Replace systems were mount in acrylic models. Two pieces titanium and zirconium abutments were attached to the implants, once with correct adaptation and once with 0.5 mm spacer. Digital radiographic images were taken of 12 created states with zero degree vertical and horizontal inclination and evaluated by 10 specialists in implant treatment in two different time penods. Data were analyzed using Kappa analysis. Results: Interclass Correlation Coefficients (ICC of the agreement of answers in the first and second times were 97.4 and 97.5, respectively (P<0/001. Sensitivity of detecting gap in all groups was acceptable (95-100% except titanium abutment in Noble active which was the lowest value (35%. Specificity of all groups were acceptable (80-95% except zirconia abutments in Noble active and Replace with 45% and 30% values, respectively, and titanium abutments in Branemark had the highest value (95%. Conclusion: The sensitivity of radiographic images in detection of abutment-implant connection misfit only in Noble active with titanium abutment was not acceptable. Specificity of radiographic images in the absence of gap in titanium abutments was more favorable.

  10. Elasto-Viscoplastic Block Element Method and its Application to Arch Dam Abutment Slopes

    Science.gov (United States)

    Chen, S.-H.; Shahrour, I.; Egger, P.; Wang, W.-M.

    2002-08-01

    This paper presents an elasto-viscoplastic block element method and its application to the deformation and stability study of arch dam abutment slopes. The paper is composed of two parts. The first part concerns the numerical methods used in the analysis, which includes the identification of the rock blocky system, the algorithm of unconfined seepage flow in discontinuity network taking the grout curtain and drainage curtain into account, and the elasto-viscoplastic block element method as well. In the second part a complicated arch dam abutment slope is studied, from which the seepage flow, the deformation, and the safety factor of the abutment slope are obtained. Based on the analysis suggestions about the seepage control and stabilization measures are made.

  11. National Bridge Inventory (NBI) Bridges

    Data.gov (United States)

    Department of Homeland Security — The NBI is a collection of information (database) describing the more than 600,000 of the Nation's bridges located on public roads, including Interstate Highways,...

  12. Mechanical behavior of single-layer ceramized zirconia abutments for dental implant prosthetic rehabilitation

    OpenAIRE

    Jiménez Melendo, Manuel; Llena Blasco, Oriol; Bruguera Alvarez, August; Llena Blasco, Jaime; Yáñez Vico, Rosa María; García Calderón, Manuel; Vaquero Aguilar, Cristina; Velázquez Cayón, Rocío; Gutiérrez Pérez, José Luis; Torres Lagares, Daniel

    2014-01-01

    Objectives: This study was undertaken to characterize the mechanical response of bare (as-received) and single-layer ceramized zirconia abutments with both internal and external connections that have been developed to enhanced aesthetic restorations. Material and Methods: Sixteen zirconia implant abutments (ZiReal Post®, Biomet 3i, USA) with internal and external connections have been analyzed. Half of the specimens were coated with a 0.5mm-thick layer of a low-fusing fluroapatite ceramic. Me...

  13. Sealing Capability and SEM Observation of the Implant-Abutment Interface

    Directory of Open Access Journals (Sweden)

    Fabio C. Lorenzoni

    2011-01-01

    water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (<.05 and Tukey's test. Marginal fit was determined using SEM. Leakage was observed for both groups at all times and was significantly higher at 144 hrs. SEM analysis depicted gaps in the implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period.

  14. Resin-bonded cast splints for loosened abutment teeth to anchor a removable partial denture: a case report.

    Science.gov (United States)

    Shimizu, Hiroshi; Tsue, Fumitake; Takahashi, Yutaka

    2009-03-01

    This case report describes a technique to stabilize loosened abutment teeth by seating resin-bonded cast splints with rest seats and surveyed guide planes to anchor a removable partial denture. This technique can achieve sufficient stability of the abutment teeth and proper support and bracing of the removable partial denture with minimal intervention.

  15. Building Bridges

    DEFF Research Database (Denmark)

    The report Building Bridges adresses the questions why, how and for whom academic audience research has public value, from the different points of view of the four working groups in the COST Action IS0906 Transforming Audiences, Transforming Societies – “New Media Genres, Media Literacy and Trust...... in the Media”, “Audience Interactivity and Participation”, “The Role of Media and ICT Use for Evolving Social Relationships” and “Audience Transformations and Social Integration”. Building Bridges is the result of an ongoing dialogue between the Action and non-academic stakeholders in the field of audience...

  16. Seismic response of skewed RC box-girder bridges

    Institute of Scientific and Technical Information of China (English)

    Ahmed Abdel-Mohti; Gokhan Pekcan

    2008-01-01

    It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities.Since the 1971 San Fernando earthquake,there has been a better understanding of the seismic performance of bridges.Nonetheless,there are no detailed guidelines addressing the performance of skewed highway bridges.Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex.Therefore,there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges.This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees,analytically.Finite element (FE) and simplified beam-stick (BS) models of the bridge were developed using SAP2000.Different types of analysis were considered on both models such as:nonlinear static pushover,and linear and nonlinear time history analyses.A comparison was conducted between FE and BS,different skew angles,abutment support conditions,and time history and pushover analysis.It is shown that the BS model has the capability to capture the coupling due to skew and the significant modes for moderate skew angles.Boundary conditions and pushover load profile are determined to have a major effect on pushover analysis.Pushover analysis may be used to predict the maximum deformation and hinge formation adequately.

  17. Analysis of load distribution in tooth-implant supported fixed partial dentures by the use of resilient abutment

    Directory of Open Access Journals (Sweden)

    Glišić Mirko

    2016-01-01

    Full Text Available Introduction. Differences between the tooth and implant response to load can lead to many biological and technical implications in the conditions of occlusal forces. Objective. The objective of this study was to analyze load distribution in tooth/implant-supported fixed partial dentures with the use of resilient TSA (Titan Shock Absorber, BoneCare GmbH, Augsburg, Germany abutment and conventional non-resilient abutment using finite element method. Methods. This study presents two basic 3D models. For one model a standard non-resilient abutment is used, and on the implant of the second model a resilient TSA abutment is applied. The virtual model contains drawn contours of tooth, mucous membranes, implant, cortical bones and spongiosa, abutment and suprastructure. The experiment used 500 N of vertical force, applied in three different cases of axial load. Calculations of von Mises equivalent stresses of the tooth root and periodontium, implants and peri-implant tissue were made. Results. For the model to which a non-resilient abutment is applied, maximum stress values in all three cases are observed in the cortical part of the bone (maximum stress value of 49.7 MPa. Measurements of stress and deformation in the bone tissue in the model with application of the resilient TSA abutment demonstrated similar distribution; however, these values are many times lower than in the model with non-resilient TSA abutment (maximum stress value of 28.9 MPa. Conclusion. Application of the resilient TSA abutment results in more equal distribution of stress and deformations in the bone tissue under vertical forces. These values are many times lower than in the model with the non-resilient abutment.

  18. Building Bridges

    DEFF Research Database (Denmark)

    The report Building Bridges adresses the questions why, how and for whom academic audience research has public value, from the different points of view of the four working groups in the COST Action IS0906 Transforming Audiences, Transforming Societies – “New Media Genres, Media Literacy and Trust...

  19. Long-term stability analysis of the left bank abutment slope at Jinping I hydropower station

    Directory of Open Access Journals (Sweden)

    Long Zhang

    2016-06-01

    Full Text Available The time-dependent behavior of the left bank abutment slope at Jinping I hydropower station has a major influence on the normal operation and long-term safety of the hydropower station. To solve this problem, a geomechanical model containing various faults and weak structural planes is established, and numerical simulation is conducted under normal water load condition using FLAC3D, incorporating creep model proposed based on thermodynamics with internal state variables theory. The creep deformations of the left bank abutment slope are obtained, and the changes of principal stresses and deformations of the dam body are analyzed. The long-term stability of the left bank abutment slope is evaluated according to the integral curves of energy dissipation rate in domain and its derivative with respect to time, and the non-equilibrium evolution rules and the characteristic time can also be determined using these curves. Numerical results show that the left bank abutment slope tends to be stable in a global sense, and the stress concentration is released. It is also indicated that more attention should be paid to some weak regions within the slope in the long-term deformation process.

  20. Long-term stability analysis of the left bank abutment slope at Jinping I hydropower station

    Institute of Scientific and Technical Information of China (English)

    Long Zhang; Qiang Yang; Yaoru Liu

    2016-01-01

    The time-dependent behavior of the left bank abutment slope at Jinping I hydropower station has a major influence on the normal operation and long-term safety of the hydropower station. To solve this problem, a geomechanical model containing various faults and weak structural planes is established, and numerical simulation is conducted under normal water load condition using FLAC3D, incorporating creep model proposed based on thermodynamics with internal state variables theory. The creep deformations of the left bank abutment slope are obtained, and the changes of principal stresses and deformations of the dam body are analyzed. The long-term stability of the left bank abutment slope is evaluated ac-cording to the integral curves of energy dissipation rate in domain and its derivative with respect to time, and the non-equilibrium evolution rules and the characteristic time can also be determined using these curves. Numerical results show that the left bank abutment slope tends to be stable in a global sense, and the stress concentration is released. It is also indicated that more attention should be paid to some weak regions within the slope in the long-term deformation process.

  1. Resisting momentum in the abutment to rotating of freight car bogie

    Directory of Open Access Journals (Sweden)

    Pavels GAVRILOVS

    2008-01-01

    Full Text Available On the Latvian railway, derailments of freight cars take place in the course of shunting work on marshalling yards. A number of factors during shunting work on marshalling yards may contribute to the derailments of rolling stock: longitudinal dynamics during braking of cars with the turned off brakes by locomotive, hauling down cars from a marshalling hill with braking position controlled by an operator, dry internal rails in curves, absence of greasing in the pivot unit of freight bogies. At present, measures allowing elimination of the car derailments during shunting work are developed.During the period between repairs, the abutment unit of freight car often works in conditions of dry friction. Our observations suggest that at the time of taking a car into repair, there is often an absence of greasing between trail bearing and center plate of the abutment, and a presence of sandy dust. It increases a friction and, together with high contact pressures and dynamic influence, hinders the turn of bogie at motion of car.In this paper, the results of studying the resisting moment in the abutment to turning of bogie is reported. The study was conducted on the basis of freight bogie of type 18-100; the body was leant on the center plate unit of the abutment, on the center plate unit, and on the sliders. Experiments were conducted, with the use of greasing and at the dry friction of center plate unit.

  2. Formation and evolution of gas flow channels in the abutment pressure area

    Institute of Scientific and Technical Information of China (English)

    Zhang Yong; Zhang Xibin; Xu Lifeng; Zhang Jiangli; Zhou Genli

    2012-01-01

    The permeability of coal ahead of the working face obviously changes dues to changes in abutment pressure.The formation and evolution of gas flow channels within the abutment pressure area was studied by analyzing the fracture extension mechanism and fracture development in different zones of the abutment pressure area.Fracture and damage mechanics theory is used to understand the observations.The following two techniques were used to understand the evolution of gas flow channels:field observation of the characteristic fractures at different positions relative to the working face and fluorescence micrographs of prepared coal samples.Bending tensile fractures develop along an approximately vertical direction that forms a microscopic network of channels in areas of stress concentration.The abutment pressure affects the local stress and,hence,the local gas conduction.The fractures induced by large deformation and plastic flow form macroscopically networked channels in the reduced stress area.Closer to the working face the gas flow channels evolve from microscopic to macroscopic and from isolated to network.Gas permeability continuously increases during this time.This is corroborated by field observations of the displacement of top coal and the gas flow from gas extraction drillings.

  3. Relevance between abutment pressure and fractal dimension of crack network induced by mining

    Institute of Scientific and Technical Information of China (English)

    Gao Mingzhong; Jin Wencheng; Dai Zhixu; Xie Jing

    2013-01-01

    Based on the geological conditions of coal mining face No. 15-14120 at No. 8 mine of Pingdingshan coal mining group, the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument. And according to the geology of this working face, a discrete element model was calculated by UDEC. Combining in situ experimental data with numerical results, the relationship between the fractal dimension of boreholes’ wall and the distri-bution of advanced abutment pressure was studied under the condition of mining advance. The results show that the variation tendency of fractal dimension and the abutment pressure has the same charac-teristic value. The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face. When the working face is set as the original point, the trend of fractal dimension from the far place to the origin can be divided into three phases:constant, steady increasing and constant. And the turning points of these phases are the max-influencing distance (50 m) and peak value (15 m) of abutment pressure.

  4. Distribution of Side Abutment Stress in Roadway Subjected to Dynamic Pressure and Its Engineering Application

    Directory of Open Access Journals (Sweden)

    Yao Qiangling

    2015-01-01

    Full Text Available The borehole stress-meter was employed in this study to investigate the distribution of the side abutment stress in roadway subjected to dynamic pressure. The results demonstrate that the side abutment stress of the mining roadway reaches a peak value when the distance to the gob is 8 m and the distribution curve of the side abutment stress can be divided into three zones: stress rising zone, stress stabilizing zone, and stress decreasing zone. Further numerical investigation was carried out to study the effect of the coal mass strength, coal seam depth, immediate roof strength, and thickness on the distribution of the side abutment stress. Based on the research results, we determined the reasonable position of the mining roadway and the optimal width of the barrier pillar. The engineering application demonstrates that the retention of the barrier pillar with a width of 5 m along the gob as the haulage roadway for the next panel is feasible, which delivers favorable technological and economic benefits.

  5. The effect of mucosal cuff shrinkage around dental implants during healing abutment replacement.

    Science.gov (United States)

    Nissan, J; Zenziper, E; Rosner, O; Kolerman, R; Chaushu, L; Chaushu, G

    2015-10-01

    Soft tissue shrinkage during the course of restoring dental implants may result in biological and prosthodontic difficulties. This study was conducted to measure the continuous shrinkage of the mucosal cuff around dental implants following the removal of the healing abutment up to 60 s. Individuals treated with implant-supported fixed partial dentures were included. Implant data--location, type, length, diameter and healing abutments' dimensions--were recorded. Mucosal cuff shrinkage, following removal of the healing abutments, was measured in bucco-lingual direction at four time points--immediately after 20, 40 and 60 s. anova was used to for statistical analysis. Eighty-seven patients (49 women and 38 men) with a total of 311 implants were evaluated (120 maxilla; 191 mandible; 291 posterior segments; 20 anterior segments). Two-hundred and five (66%) implants displayed thick and 106 (34%) thin gingival biotype. Time was the sole statistically significant parameter affecting mucosal cuff shrinkage around dental implants (P < 0.001). From time 0 to 20, 40 and 60 s, the mean diameter changed from 4.1 to 4.07, 3.4 and 2.81 mm, respectively. The shrinkage was 1%, 17% and 31%, respectively. The gingival biotype had no statistically significant influence on mucosal cuff shrinkage (P = 0.672). Time required replacing a healing abutment with a prosthetic element should be minimised (up to 20/40 s), to avoid pain, discomfort and misfit. PMID:26132112

  6. Cancer of Oral Cavity Abutting the Mandible; Predictors of Loco-regional Failure

    International Nuclear Information System (INIS)

    The purpose of this study is to analyze the causes of Loco-regional failure in 51 patients with tumors of the oral cavity abutting the mandible. Patients and Methods: This cross-sectional study (27 patients were operated upon in the retrospective section and 24 patients in the prospective section of the study) was done in the department of Surgical Oncology, National Cancer Institute, Cairo University, from January 2003 to January 2008. Fifty-one patients, with oral cavity cancerous lesions abutting the mandible, were operated upon by segmental mandibulectomy en-bloc with primary tumor resection in addition to modified radical or selective neck dissection according to the status of the cervical lymph nodes. Results: During a median follow-up of 2 years, 29 patients (56.8%) had local recurrences, the incidence of nodal recurrence after neck dissection was detected in 4 patients (7.8%). On multivariate analysis, tumor depth, tumor grade, oral mucosa, soft tissue and bone surgical margins in addition to metastatic lymphadenopathy were independent prognostic factors of loco-regional failure and disease-free survival. Conclusion: Oral cavity cancers abutting the mandible should be treated with great caution by a multidisciplinary oncology team (resection and reconstruction surgeons) as it has a very aggressive biologic behavior. Negative intraoperative pathological margins should be attempted since this is the critical point for patients with cancers abutting the mandible? Further research on the biologic margin and genetic study is required

  7. Live-bed scour experiments with 45° wing-wall abutments

    Indian Academy of Sciences (India)

    M H Mazumder; A K Barbhuiya

    2014-10-01

    Live bed scour experiments were conducted using four types of noncohesive bed sediments with median diameters d50 = 0.26 mm, 0.42 mm, 1.06 mm and 1.92 mm and five 45° wing-wall abutments of lengths l = 0.04 m, 0.06 m, 0.08 m, 0.10 m and 0.12 m. The tests were conducted in the range of flow velocity varies from 0.71 to 5 times of the critical velocity. The plotting of non-dimensional scour depths (scour depths/abutment lengths) vs non-dimensional flow intensity (flow intensity/critical velocity) show one peak value of scour depth close to the threshold velocity and thereafter, it reduces and again attain a live-bed maximum in the range of flow intensity 3 to 5 times of the critical velocity. It is also observed that the scour depth increases with the increase in sediment sizes up to threshold value of flow for all sediment sizes and abutment lengths. Further, the scour depth decreases with the increase of non-uniformity under all flow conditions. A design equation is proposed for estimating maximum scour depth at 45°wing-wall abutment under live-bed condition. The calculated values of scour depths using proposed equation, and also with three different live-bed local scour equations, are compared with the measured values of scour depths.

  8. Bridged graphite oxide materials

    Science.gov (United States)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  9. Percutaneous Radiofrequency Ablation for the Hepatocellular Carcinoma Abutting the Diaphragm: Assessment of Safety and Therapeutic Efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Tae Wook; Rhim, Hyun Chul; Kim, Eun Young; Kim, Young Sun; Choi, Dong Il; Lee, Won Jae; Lim, Hyo K. [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2009-02-15

    To assess the safety and therapeutic efficacy of a percutaneous radiofrequency (RF) ablation for the hepatocellular carcinoma (HCC) abutting the diaphragm. We retrospectively assessed 80 patients who underwent a percutaneous RF ablation for a single nodular (< 4 cm) HCC over the last four years. Each patient underwent an ultrasound-guided RF ablation using internally cooled electrodes for the first-line treatment. We divided patients into two subgroups based on whether the index tumor was abutting (less than 5 mm) the diaphragm or not: group A (abutting; n = 31) versus group B (non-abutting; n = 49). We compared the two subgroups for complications and therapeutic efficacy using image and the review of medical records. The statistical assessment included an independent t-test, Fisher's exact test, and chi-square test. The assessment of the diaphragmatic swelling at CT immediately following the procedure was more severe in group A than group B (mean thickness change:1.44 vs. 0.46 mm, p = 0.00). Further, right shoulder pain was more common in group A than B (p = 0.01). Although minor complications (hemothorax 1 case, pleural effusion 1 case) were noted only in group A, no major thoracic complication occurred in either group. The technical success rate was lower in group A than group B (84% vs. 98%, p = 0.03). As well, the primary and secondary technique effectiveness rates in group A and group B were 90% versus 98% (p = 0.29) and 79% versus 91% (p = 0.25), respectively. The local tumor progression rate was higher in group A than in group B (29% vs. 6%, p = 0.02). We found that the percutaneous RF ablation for the HCC abutting the diaphragm is a safe procedure without major complications. However, it is less effective with regard to technical success and local tumor control.

  10. Analytical solutions of hard roof’s bending moment, deflection and energy under the front abutment pressure before periodic weighting

    Institute of Scientific and Technical Information of China (English)

    Jiang Haijun; Cao Shenggen; Zhang Yun; Wang Chen

    2016-01-01

    The distribution of front abutment pressure is closely related to the force, deformation and energy distri-bution of hard roof before periodic weighting. So it is necessary to carry out research on the relationship between them. According to front abutment pressure distribution feature, using the location of peak front abutment pressure as the dividing point, coal seam is divided into two parts along the direction of min-ing:the yield zone that is the area between the faceline and the point where the maximum front abut-ment pressure occurs, and the elastic zone that is the part before the point of peak front abutment pressure. The proposed mechanical model of unit width hard roof at the panel center before periodic weighting consists of five parts including the yield zone. All parameters of the deflection equations for each of the five parts that satisfy the continuity conditions and natural boundary conditions are obtained by using the Matlab software. The continuous curves of front abutment pressure, deflection, bending moment and bending strain energy density distribution of hard roof are obtained by iterative approxima-tion method, and the relationship between the yield zone width and the above curves are analyzed in detailed.

  11. Hasarlı Çene Kemiklerinde Abutment Boyunun Dental İmplant Sistemi Üzerindeki Etkileri

    Directory of Open Access Journals (Sweden)

    Sinan KÖSE

    2015-01-01

    Full Text Available The purpose of this study is to investigate the stresses occurred onhard and soft bones after recovering the deficiency caused by totally edentulousand damaged mandible by using abutments with different lengths andprosthesis filling material. Two different damaged parts of 2.5 and 4.5 mm indepth were created with the aid of Solidworks program on the right hand sideof the mandible. Implants were then applied between the foremen channels.Later, the damaged models were recovered by abutment with different lengthsas for the first method. Two models using abutment were, therefore, obtainedfor the damaged parts of 2.5 and 4.5 mm in depth. In the second method, for thesame damaged cases, prosthesis filling material was used to recover deficiencykeeping the abutment length constant. Finally, there were totally obtained 4different damaged models of two fixed with abutment and two fixed with fillingmaterial and 1 undamaged model. At the second step of this study, the stressvalues were obtained on lower jaw bones by using finite element method underthe maximum chewing force and compared to each other. The results showedthat stress data obtained particularly on the soft and hard bones weredistributed more uniformly on the damaged models fixed with prosthesis fillingmaterial compared to the damaged models recovered by abutment. Moreover,the stress values obtained for models fixed with different abutment length wererather high in comparison to those of the filling material application

  12. The use of CAD/CAM technology to fabricate a custom ceramic implant abutment: a clinical report.

    Science.gov (United States)

    Bertolini, Martinna de Mendonça e; Kempen, Juan; Lourenço, Eduardo José Veras; Telles, Daniel de Moraes

    2014-05-01

    Well-placed dental implants are a prerequisite of functional and esthetically successful dental implant-supported crowns. The presence of soft tissue is essential for excellent esthetics because the dental implant or titanium abutment may become visible if the soft-tissue contour is not acceptable. This clinical report describes the use of a custom ceramic implant abutment designed with computer-aided design and computer-aided manufacturing (CAD/CAM) technology by milling a zirconia framework that was cemented extraorally to a prefabricated titanium abutment with a reduced diameter. This ceramic abutment has the strength and precise fit of a titanium interface and also the esthetic advantages of shaded custom-milled zirconia, with no visible metal. PMID:24433839

  13. Evaluation of fracture resistance of indirect composite resin crowns by cyclic impact test: influence of crown and abutment materials.

    Science.gov (United States)

    Sakoguchi, Kenji; Minami, Hiroyuki; Suzuki, Shiro; Tanaka, Takuo

    2013-01-01

    This study evaluated the effect of abutment materials on the fracture resistance of composite crowns for premolars. Composite crowns were fabricated using two different indirect composite resin materials (Meta Color Prime Art or Estenia C&B) and cemented onto either a metal (Castwell M.C. 12) or composite resin (Build-It FR and FibreKor) abutment with resin cement (Panavia F2.0). Twenty-four specimens were fabricated for four groups (n=6 each) and subjected to 280-N cyclic impact loading at 1.0 Hz. The number of cycles which caused the composite crown to fracture was defined as its fracture resistance. All data were statistically analyzed using ANOVA and the Bonferroni test (α=0.05). Composite crowns cemented onto resin abutments showed higher fracture resistance than those cemented onto metal abutments.

  14. Esthetic Considerations for Reconstructing Implant Emergence Profile Using Titanium and Zirconia Custom Implant Abutments: Fifty Case Series Report.

    Science.gov (United States)

    Kutkut, Ahmad; Abu-Hammad, Osama; Mitchell, Richard

    2015-10-01

    Titanium and zirconia custom implant abutments are now commonly used for esthetic implant dentistry. Custom implant abutments allow the clinician to improve an implant's emergence profile, to customize cervical margins in accordance with the anatomy of the natural root, and to compensate for poor implant angulation. All of these are essential for optimum esthetic outcomes. Computer-aided design/computer-aided machining (CAD/CAM) technology allows the clinician to design custom implant abutment configurations and create natural-looking superstructures that are in harmony with the adjacent dentition and soft tissue. The CAD/CAM technique provides precise fit, reduces the cost of the procedure, and eliminates dimensional inaccuracies inherent in the conventional waxing and casting technique. The aim of this report is to describe a simplified technique for reconstructing emergence profiles during implant restoration using milled titanium and zirconia custom implant abutments. The results of 50 consecutive cases are reported. PMID:24175922

  15. Abutment-Supported Papilla: A Combined Surgical and Prosthetic Approach to Papilla Reformation.

    Science.gov (United States)

    Urban, Istvan A; Klokkevold, Perry R; Takei, Henry H

    2016-01-01

    Restoration of lost interdental papilla remains one of the most challenging goals for clinicians. When a single tooth is replaced with an implant, the papilla between the tooth and the implant can often be maintained or predictably reconstructed as long as the periodontal attachment and bone of the adjacent tooth is preserved. However, if the periodontal support is compromised on the neighboring natural tooth, the papilla will often be deficient or missing. This article presents a multidisciplinary treatment approach to regenerate the interdental papilla between an implant and a periodontally compromised tooth using surgical procedures and a customized abutment. Specifically, an abutment with modified subgingival contours is used to enhance support of the surgically reformed papilla. PMID:27560670

  16. Fabricating abutment crowns for existing removable partial dentures using custom resin clasp analogs.

    Science.gov (United States)

    Livaditis, G J

    1998-11-01

    A universal approach for fabricating abutment crowns for existing removable partial dentures is described. A replica (analog) of the clasp assembly is generated and transferred to a traditional working cast, which includes the abutment die. The analog is incorporated into the working cast as a removable component to allow the formation of the crown contours. The article reviews in detail the procedures required to transfer accurately all the essential components and information from the mouth to the working cast while allowing the patient uninterrupted use of the removable partial denture. Prestabilizing the removable partial denture, creating the analog impression, avoiding errors due to soft tissue components, forming a precise analog base, selecting materials, generating a rigid resin analog, and prescribing a path of insertion and withdrawal to the analog are described. The method replicates all types of clasps and can generate all types of fixed prosthodontic retainers to function harmoniously with the existing partial denture.

  17. Fabricating abutment crowns for existing removable partial dentures using custom resin clasp analogs.

    Science.gov (United States)

    Livaditis, G J

    1998-11-01

    A universal approach for fabricating abutment crowns for existing removable partial dentures is described. A replica (analog) of the clasp assembly is generated and transferred to a traditional working cast, which includes the abutment die. The analog is incorporated into the working cast as a removable component to allow the formation of the crown contours. The article reviews in detail the procedures required to transfer accurately all the essential components and information from the mouth to the working cast while allowing the patient uninterrupted use of the removable partial denture. Prestabilizing the removable partial denture, creating the analog impression, avoiding errors due to soft tissue components, forming a precise analog base, selecting materials, generating a rigid resin analog, and prescribing a path of insertion and withdrawal to the analog are described. The method replicates all types of clasps and can generate all types of fixed prosthodontic retainers to function harmoniously with the existing partial denture. PMID:9813815

  18. Mechanism of Geogrid Reinforced Soil at Bridge Approach

    Institute of Scientific and Technical Information of China (English)

    FENG Guangle; LUO Rong; CHEN Congxin

    2007-01-01

    Using Geogrid-Reinforced Soil (GRS) we studied the working mechanism and design method of GRS at bridge approach with high backfill by field experiment. In a highway section where the height of backfill is 13.5 meters, geogrids were used at two bridge approaches to address the bumping problems. Some soil pressure cells were used to measure the normal and lateral soil pressure at different locations in the roadbed. The experimental results indicate that geogrids in geogrid-reinforced soil (GRS) could produce an uplift force, the closer the location to the abutment, the larger the uplift force, and the reduction of measured soil pressures compared with theoretical values was the largest at the bottom of roadbed, less at the top than at the bottom, and the least in the mid-height of roadbed than at the bottom. These findings are different from those of the traditional greogrid-reinforced subgrade design method.

  19. Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

    OpenAIRE

    Marcos Michelon Naconecy; Tomás Geremia; André Cervieri; Eduardo Rolim Teixeira; Rosemary Sadami Shinkai

    2010-01-01

    OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1) parallel vertical implants, and 2) tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm). The deformation values were mea...

  20. Transpulmonary computed tomography-guided radiofrequency ablation of liver neoplasms abutting the diaphragm with multiple bipolar electrodes

    OpenAIRE

    Q. Zhang; Li, X; Pan, J.; Z. Wang

    2015-01-01

    Background: Neoplasm abutting the diaphragm is one kind of the special sites of liver neoplasms treated with radiofrequency ablation (RFA), the purpose of this study is to evaluate the feasibility and safety of computed tomography (CT)-guided RFA of liver neoplasms abutting the diaphragm with multiple bipolar electrodes sequentially passing through the lung parenchyma. Materials and Methods: 37 patients were treated with transpulmonary CT-guided RFA. Technical success rate, perioperative comp...

  1. The effect of resin cements and primer on retentive force of zirconia copings bonded to zirconia abutments with insufficient retention

    OpenAIRE

    Kim, Seung-Mi; Yoon, Ji-Young; Lee, Myung-Hyun; Oh, Nam-Sik

    2013-01-01

    PURPOSE The purpose of this study was to investigate the effect of resin cements and primer on the retentive force of zirconia copings bonded to zirconia abutments with insufficient retention. MATERIALS AND METHODS Zirconia blocks (Lava, 3M ESPE, St. Paul, MN, USA) were obtained and forty sets of zirconia abutments and copings were fabricated using CAD/CAM technology. They were grouped into 4 categories as follows, depending on the types of resin cements used, and whether the primer is applie...

  2. LATE RESULTS OF PATIENTS’ ORTHOPEDIC TREATMENT USING FIXED PARTIAL DENTURES, DEPENDING ON THE FUNCTIONAL STATE OF THE ABUTMENT TEETH

    OpenAIRE

    Ozhogan, Z. R.; Klymyuk, Y. V.

    2015-01-01

    Treatment of partial adentia involves preparation of abutment teeth, followed by the production of fixed partial dentures. However, the abutment tooth vitality should be taken into account and the periodontal reserve power should be considered to prevent functional overload. The hygienic condition of the oral cavity is also necessary to be monitored during treatment and at different times after it.Using clinical indices data, the preservation of vital teeth was found to be a more reliable cri...

  3. Biomechanical Analysis of Tapered Integrated Screw and Sensitivity Analysis on Abutment Loosening in Dental Implants

    OpenAIRE

    Milad Farzadi; Mohammadreza Mallakzadeh

    2013-01-01

    Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS), which is a Tapered Interference Fit (TIF) with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.Materials and Methods: Relevant equations were developed to predict tig...

  4. Correction of Malpositioned Implants through Periodontal Surgery and Prosthetic Rehabilitation Using Angled Abutment

    Directory of Open Access Journals (Sweden)

    Érica Dorigatti de Avila

    2014-01-01

    Full Text Available When dental implants are malpositioned in relation to the adjacent teeth and alveolar bone or in an excessive buccal or lingual position, the final prosthesis rehabilitation impairs the peri-implant health of the gingival tissues and the aesthetics of the patient. Thus, the purpose of this case was to report and discuss a multidisciplinary protocol for the treatment of a compromised maxillary tooth in a patient with an abscess in his right central incisor due to an excessive buccal implant position. The patient presented with an implant-supported provisional restoration on his right maxillary central incisor and a traumatic injury in his left central incisor. The treatment protocol consisted in (i abutment substitution to compensate the incorrect angulation of the implant, (ii clinical crown lengthening, (iii atraumatic extraction of the left central incisor, and (iv immediate implant placement. Finally, (v a custom abutment was fabricated to obtain a harmonious gingival contour around the prosthetic crown. In conclusion, when implants are incorrectly positioned in relation to the adjacent teeth, associated with soft-tissue defects, the challenge to create a harmonious mucogingival contours may be achieved with an interdisciplinary approach and with the placement of an appropriate custom abutment.

  5. Accuracy of different abutment level impression techniques in All-On-4 dental implants

    Directory of Open Access Journals (Sweden)

    Marzieh Alikhasi

    2012-01-01

    Full Text Available Background and Aims: Passive fit of prosthetic frameworks is a major concern in implant dentistry. Impression technique is one of the several variables that may affect the outcome of dental implants. The purpose of this study was to compare the three dimensional accuracy of direct and indirect abutment level implant impressions ofALL-ON-4 treatment plan.Materials and Methods: A reference acrylic resin model with four Branemark fixtures was made according to All-On-4 treatment plan. Multiunit abutments were screwed into the fixtures and two special trays were made for direct and indirect impression techniques. Ten direct and ten indirect impression techniques with respective impression transfers were made. Impressions were poured with stone and the positional accuracy of the abutment analogues in each dimension of x, y, and z axes and also angular displacement (Δθ were evaluated using a Coordinate Measuring Machine (CMM. Data were analyzed using T- test.Results: The results showed that direct impression technique was significantly more accurate than indirect technique (P<0.001.Conclusion: The results showed that the accuracy of direct impression technique was significantly more than that of indirect technique in Δθ and Δr coordinate and also Δx, Δy, Δz.

  6. 重载铁路桥台设计%Abutment Design of Heavy Haul Railway

    Institute of Scientific and Technical Information of China (English)

    严章荣

    2012-01-01

    针对山西中南部铁路通道采用的30 t轴重荷载,分析目前国内外重栽铁路的发展特点,拟定桥台的设计标准、设计荷载以及荷载检算模式,通过对台身偏心及应力检算,确定了空心桥台的结构尺寸.设计的矩形空心桥台台长随填土高增加而增加,其结构整体刚度好、台身圬工量较省、方便施工,能够满足30t轴重列车的运营要求.%Focusing on the axle load of 30 tons which was applied to the Railway Passage in Central and Southern Shanxi, the development characteristics of heavy haul railway at home and abroad at present were analyzed. The design criteria, design load and the load calculation model were formulated. After the eccentricities and the stresses are checked out, the structure size of hollow abutment was defined. The design results show that the rectangular hollow abutment which the abutment length increases with the increase of earth filling's height, has a good rigidity with less amount of masonry, can be convenient for construction, and can meet the requirements of train's operation under 30t axle load.

  7. Preload and torque removal evaluation of three different abutment screws for single standing implant restorations

    Directory of Open Access Journals (Sweden)

    Rafael Augusto Stüker

    2008-02-01

    Full Text Available Several authors still consider the mechanical problems of fracture and component loosening as the main causes of failure of implant-supported restorations. The purpose of this in vitro study was to compare the preload of three types of screw for transmucosal abutment attachment used in single implant-supported prosthesis through strain gauge and removal torque measurements. Three external hex fixtures were used, and each received a transmucosal abutment (Cera One®, which was fixed to the implant with its respective screw: Group A- gold screw, Group B- titanium screw and Group C- surface-treated titanium screw (Ti-Tite®. Ten screws of each type were attached applying a 30.07±0.28 Ncm torque force and maintained in position for 5 minutes. After this, the preload values were measured using strain gauges and a measurement cell. Gold screws presented higher preload values (131.72±8.98 N, followed by surface-treated titanium screws (97.78±4.68 N and titanium screws (37.03±5.69 N. ANOVA (p<0.05 and Tukey's test (p<0.05 were applied. Statistically significant differences were found among the groups for both preload and removal torque values. In conclusion, gold screws may be indicated to achieve superior longevity of the abutment-implant connection and, consequently, prosthetic restoration due to greater preload values yielded.

  8. Repeatability and reproducibility of individual abutment impression, assessed with a blue light scanner

    Science.gov (United States)

    Kim, Dong-Yeon; Lee, Jae-Jun; Kim, Ji-Hwan

    2016-01-01

    PURPOSE We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by 10-20° on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (α=.05). RESULTS The differences with regard to repeatability were 4.5, 2.7, and 3.1 µm for the canine, premolar, and molar, indicating the poorest repeatability for the canine (P<.001). For reproducibility, the differences were 6.6, 5.8, and 11.0 µm indicating the poorest reproducibility for the molar (P=.007). CONCLUSION Our results indicated that impressions of individual abutment teeth, digitized with a blue light scanner, had good repeatability and reproducibility. PMID:27350856

  9. Soft Tissue Response to Titanium Abutments with Different Surface Treatment: Preliminary Histologic Report of a Randomized Controlled Trial

    Science.gov (United States)

    Canullo, Luigi; Dehner, Jan Friedrich; Penarrocha, David; Checchi, Vittorio; Mazzoni, Annalisa; Breschi, Lorenzo

    2016-01-01

    The aim of this preliminary prospective RCT was to histologically evaluate peri-implant soft tissues around titanium abutments treated using different cleaning methods. Sixteen patients were randomized into three groups: laboratory customized abutments underwent Plasma of Argon treatment (Plasma Group), laboratory customized abutments underwent cleaning by steam (Steam Group), and abutments were used as they came from industry (Control Group). Seven days after the second surgery, soft tissues around abutments were harvested. Samples were histologically analyzed. Soft tissues surrounding Plasma Group abutments predominantly showed diffuse chronic infiltrate, almost no acute infiltrate, with presence of few polymorphonuclear neutrophil granulocytes, and a diffuse presence of collagenization bands. Similarly, in Steam Group, the histological analysis showed a high variability of inflammatory expression factors. Tissues harvested from Control Group showed presence of few neutrophil granulocytes, moderate presence of lymphocytes, and diffuse collagenization bands in some sections, while they showed absence of acute infiltrate in 40% of sections. However, no statistical difference was found among the tested groups for each parameter (p > 0.05). Within the limit of the present study, results showed no statistically significant difference concerning inflammation and healing tendency between test and control groups. PMID:27366741

  10. Dynamic responses of bridge-approach embankment transition section of high-speed rail

    Institute of Scientific and Technical Information of China (English)

    杨长卫; 孙海玲; 张建经; 朱传彬; 颜利平

    2013-01-01

    Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.

  11. Seismic Response Analysis of Continuous Multispan Bridges with Partial Isolation

    Directory of Open Access Journals (Sweden)

    E. Tubaldi

    2015-01-01

    Full Text Available Partially isolated bridges are a particular class of bridges in which isolation bearings are placed only between the piers top and the deck whereas seismic stoppers restrain the transverse motion of the deck at the abutments. This paper proposes an analytical formulation for the seismic analysis of these bridges, modelled as beams with intermediate viscoelastic restraints whose properties describe the pier-isolator behaviour. Different techniques are developed for solving the seismic problem. The first technique employs the complex mode superposition method and provides an exact benchmark solution to the problem at hand. The two other simplified techniques are based on an approximation of the displacement field and are useful for preliminary assessment and design purposes. A realistic bridge is considered as case study and its seismic response under a set of ground motion records is analyzed. First, the complex mode superposition method is applied to study the characteristic features of the dynamic and seismic response of the system. A parametric analysis is carried out to evaluate the influence of support stiffness and damping on the seismic performance. Then, a comparison is made between the exact solution and the approximate solutions in order to evaluate the accuracy and suitability of the simplified analysis techniques for evaluating the seismic response of partially isolated bridges.

  12. Effects of Live Load on Seismic Response of Bridges: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Sanders D.H.

    2012-01-01

    Full Text Available Although live load is well known to have a dynamic effect on bridge response in addition to its self-weight, the significance of these effects on seismic response is unclear. In addition, most bridge design specifications have few requirements concerning the inclusion of live load in their seismic design provisions. The main objective of this study is therefore to investigate and obtain insight into the effect of vehicle-bridge interaction during earthquake shaking. The study consists of both experimental and analytical investigations. This paper focuses on the experimental work, which includes shake table testing of a 2/5-scale model of a horizontally curved steel girder bridge loaded with a series of representative vehicles. Preliminary experimental results show that the presence of the live load had a clear beneficial effect on performance for small amplitude motions, but that this improvement diminished with increasing amplitude of shaking. Parameters used to measure performance include column displacements, abutment shear forces, abutment uplift, and concrete spalling.

  13. The Effect of Laser-Etched Surface Design on Soft Tissue Healing of Two Different Implant Abutment Systems: An Experimental Study in Dogs.

    Science.gov (United States)

    Neiva, Rodrigo; Tovar, Nick; Jimbo, Ryo; Gil, Luiz F; Goldberg, Paula; Barbosa, Joao Pm; Lilin, Thomas; Coelho, Paulo G

    2016-01-01

    This study describes the early soft tissue morphology around two different implant systems that received either smooth or laser-etched abutments in a beagle dog model. Implants were placed in the healed mandibular molar region of eight beagle dogs and allowed to heal for 7 weeks. When the most apical aspect of the junctional epithelium (JE) was above or within the upper half of the laser-etched region, fibers were oriented perpendicular to the abutment surface. In contrast, JE positioned within the lower half of the laser-etched region or within or below the implant-abutment gap level presented fibers oriented parallel to the abutment surface. PMID:27560671

  14. Assessment of seismic performance of skew reinforced concrete box girder bridges

    Science.gov (United States)

    Abdel-Mohti, Ahmed; Pekcan, Gokhan

    2013-12-01

    The seismic vulnerability of highway bridges remains an important problem and has received increased attention as a consequence of unprecedented damage observed during several major earthquakes. A significant number of research studies have examined the performance of skew bridges under service and seismic loads. The results of these studies are particularly sensitive to modeling assumptions in view of the interacting parameters. In the present study, three-dimensional improved beam-stick models of two-span highway bridges with skew angles varying from 0° to 60° are developed to investigate the seismic response characteristics of skew box girder bridges. The relative accuracy of beam-stick models is verified against counterpart finite element models. The effect of various parameters and conditions on the overall seismic response was examined such as skew angle, ground motion intensity, soil condition, abutment support conditions, bridge aspect ratio, and foundation-base conditions. The study shows that the improved beam-stick models can be used to conduct accurate nonlinear time history analysis of skew bridges. Skew angle and interacting parameters were found to have significant effect on the behavior of skewed highway bridges. Furthermore, the performance of shear keys may have a predominant effect on the overall seismic response of the skew bridges.

  15. Radiologic evaluation of bone loss at implants with biocide coated titanium abutments: a study in the dog.

    Directory of Open Access Journals (Sweden)

    Roberto López-Píriz

    Full Text Available The objective of the present study is to evaluate bone loss at implant abutments coated with a soda-lime glass containing silver nanoparticles subjected to experimental peri-implantitis. Five beagle dogs were used in the experiments, 3 implants were installed in each quadrant of the mandibles. Glass/n-Ag coted abutments were connected to implant platform. Cotton floss ligatures were placed in a submarginal position around the abutment necks and the animals were subject to a diet which allowed plaque accumulation, and after 15 weeks the dogs were sacrificed. Radiographs of all implant sites were obtained at the beginning and at the end of the experimentally induced peri-implantitis. The radiographic examination indicated that significant amounts of additional bone loss occurred in implants without biocide coating, considering both absolute and relative values of bone loss. Percentages of additional bone loss observed in implants dressed with a biocide coated abutment were about 3 times lower (p<0.006 distal aspect; and p<0.031 at mesial aspect than the control ones. Within the limits of the present study it seems promising the use of soda-lime glass/nAg coatings on abutments to prevent peri-implant diseases.

  16. Implications of Surface and Bulk Properties of Abutment Implants and Their Degradation in the Health of Periodontal Tissue

    Directory of Open Access Journals (Sweden)

    Erica Dorigatti de Avila

    2013-12-01

    Full Text Available The aim of the current review was to investigate the implications of the surface and bulk properties of abutment implants and their degradation in relation to periodontal health. The success of dental implants is no longer a challenge for dentistry. The scientific literature presents several types of implants that are specific for each case. However, in cases of prosthetics components, such as abutments, further research is needed to improve the materials used to avoid bacterial adhesion and enhance contact with epithelial cells. The implanted surfaces of the abutments are composed of chemical elements that may degrade under different temperatures or be damaged by the forces applied onto them. This study showed that the resulting release of such chemical elements could cause inflammation in the periodontal tissue. At the same time, the surface characteristics can be altered, thus favoring biofilm development and further increasing the inflammation. Finally, if not treated, this inflammation can cause the loss of the implant.

  17. Damage analysis and seismic retrofitting of a continuous prestressed reinforced concrete bridge

    Directory of Open Access Journals (Sweden)

    Nicola Caterino

    2014-12-01

    Full Text Available The seismic analysis and retrofit of prestressed reinforced concrete bridge is discussed by considering a real case of a viaduct still in use. The unique features of this bridge make this type of bridge particularly interesting, either structurally or architecturally. The paper begins with the analysis of certain particular structural deficiencies that emerged during the viaduct operation. The results of the analysis indicate that the structural performance can be enhanced by only modifying the support devices. The primary structural components are not required to be involved in the retrofitting process. Using the modern seismic code, the upgrading of the viaduct performance is obtained by replacing the old bearing devices on the piers and existing viscous dampers connected abutments to the deck with new modernised ones.

  18. The effect of platform switching on the levels of metal ion release from different implant–abutment couples

    Science.gov (United States)

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant–abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt–chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (PTitanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant–abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant–abutment couples. PMID:27357323

  19. The effect of platform switching on the levels of metal ion release from different implant-abutment couples.

    Science.gov (United States)

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant-abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt-chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (P<0.05). Titanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant-abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant-abutment couples. PMID:27357323

  20. Assessment of the tensile strength of hexagonal abutments using different cementing agents

    Directory of Open Access Journals (Sweden)

    Carlos Wahl

    2008-12-01

    Full Text Available The aim of this study was to assess the uniaxial tensile strength after thermal cycling in replicas of CeraOne®abutments (abutment and coping sets, using four types of cements (n = 10. A zinc phosphate cement (Fosfato de Zinco®/ SSW, a resin-modified glass ionomer cement (RelyX®luting / 3M-ESPE, a zinc oxide-eugenol cement (ZOE®/ SSW and a zinc oxide cement without eugenol (TempBond NE®/ KERR were used. After cementation, the samples were submitted to thermal cycles (1,000 cycles, 5ºC ± 2º to 55ºC ± 2º for thirty seconds in each bath. Next, the samples were submitted to the tensile test in a universal test machine (0.5 mm/min. The data were submitted to ANOVA and the Tukey-Kramer test (p < 0.05, and statistically significant difference was found among the cements. The highest tensile strength mean value found was for zinc phosphate cement (33.6 kgf followed by the resin-modified glass ionomer cement (20.5 kgf, zinc oxide-eugenol cement (8.4 kgf and the temporary cement (3.1 kgf. Therefore, it was found that the permanent cements presented higher tensile strength, and the temporary cement could be used in situations requiring reversibility and the removal of cemented dental implant-supported prostheses.

  1. Histology of a dental implant with a platform switched implant-abutment connection

    Directory of Open Access Journals (Sweden)

    Vittoria Perrotti

    2011-10-01

    Full Text Available Background: Peri-implant crestal bone must be stable for aesthetic reasons. Aim of this study was a histologic analysis of an implant with a platform switched implant-abutment connection. Materials and methods: A 32-year-old male patient participated in this study. The patient needed a bilateral mandibular restoration. Four implants were used, and were immediately restored and loaded the same day of insertion. After a 6 weeks healing period, one implant with platform-switched abutment was retrieved with trephine. Before retrieval the implant was osseointegrated and not mobile. On one side of the implant, a 1 mm resorption of the crestal bone was present. On the contrary, on the other side no bone resorption had occurred and about 1 mm of bone was present over the implant shoulder. Results: The bone-implant contact percentage was 65.1 ± 6.3 %. Platform- switching could help in maintaining the height of the peri-implant crestal bone.

  2. Biomechanical Analysis of Tapered Integrated Screw and Sensitivity Analysis on Abutment Loosening in Dental Implants

    Directory of Open Access Journals (Sweden)

    Milad Farzadi

    2013-02-01

    Full Text Available Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS, which is a Tapered Interference Fit (TIF with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.Materials and Methods: Relevant equations were developed to predict tightening and loosening torques, contactpressure and preloads with and without bone tissue in this analysis. The efficiency is defined as the ratio of the loosening torque to the tightening torque. The effects of the change in elastic modulus and thickness of the bone on operation of this mechanism were investigated.Results: In this study, 14 independent parameters such as taper angle, friction coefficient, abutment and implantgeometry that are effective on performance of TIS mechanism were presented. The role of some factors was shown in the performance of ITI implant using sensitivity analysis.Conclusion: It was shown that friction coefficient, contact length, and implant radius play major roles on tightening and loosening torques and efficiency of the mechanism. Furthermore, the results revealed that the change in the elastic modulus and thickness of the bone influenced the efficiency of the mechanism less than 15%.

  3. Investigation of the Effects of Abutment and Implant Length on Stability of Short Dental Implants

    Directory of Open Access Journals (Sweden)

    Eda OZYILMAZ

    2015-01-01

    Full Text Available The use of dental implants to solve different problems in dentistry has been growing rapidly. The success rates of dental implants are also very important for patients. Depending on the bone level of patients, short dental implants are very popular and widely used by many dentists. Although many dentists are using short dental implants frequently, It can be guessed that there can be stability problems because of crown to implant ratios. In this study, it is aimed to find out the effects of dental implant and abutment lengths on stability of short dental implants. 3 different short dental implant design made with the use of Solidworks 2013. Abutment lengths were 3,5 mm, 4 mm, 4,5 mm, 5 mm and implant lengths were 5 mm, 6 mm, 7 mm for each model. Human mandible model is transferred from Computed Tomography. Then, each implant model is mounted to modeled mandible and Finite Element Analysis is performed for each model. In order to see the effects of implant number on stability, we performed same analysis by placing 4 implants to the mandible

  4. Repeatability and reproducibility of individual abutment impression, assessed with a blue light scanner

    Science.gov (United States)

    Kim, Dong-Yeon; Lee, Jae-Jun; Kim, Ji-Hwan

    2016-01-01

    PURPOSE We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by 10-20° on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (α=.05). RESULTS The differences with regard to repeatability were 4.5, 2.7, and 3.1 µm for the canine, premolar, and molar, indicating the poorest repeatability for the canine (Pteeth, digitized with a blue light scanner, had good repeatability and reproducibility. PMID:27350856

  5. Cable Supported Bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    Cable supported bridges in the form of suspension bridges and cable-stayed bridges are distinguished by their ability to overcome large spans.The book concentrates on the synthesis of cable supported bridges, covering both design and construction aspects. The analytical part covers simple methods...... to quantify the different structural configurations and allows a preliminary optimization of the main structure.Included are the most recent advances in structural design, corrosion protection of cables, aerodynamic safety, and erection procedures....

  6. Clinical follow-up of ceramic bridges with auro-galvanoforming primary coping and Ni-Cr pontic for restoration of dentition defects

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiang-hao; SUN Feng

    2009-01-01

    Background Alternatives to the conventional auro-galvanoforming ceramic bridge need to be evaluated in long-term longitudinal studies before being recommended for restoration of dentition defects. This study aimed to evaluate the clinical performance of a ceramic bridge with auro-galvanoforming primary coping and Ni-Cr pontic for restoration of dentition defects.Methods In total, 114 ceramic bridges with auro-galvanoforming (primary coping and Ni-Cr pontic) were placed in 112 patients with dentition defects. Among them, 83 bridges in 82 patients were available for follow-up after 7 years. We evaluated marginal integrity, color match, gingival inflammation, fracture of ceramic bridges, and recurrent caries. Results Marginal integrity of the ceramic bridges was perfect in all patients. Most ceramic bridges maintained their original color. Fracture was found in three bridges; the rest were free of fracture, breakage, and loosening. Recurrent abutment caries were not found. Ceramic bridges with auro-galvanoforming (primary coping and Ni-Cr pontic) produced satisfactory clinical outcomes-equivalent to the conventional porcelain-fused-to-metal restoration. This technique is especially useful for dentition defects of the molar area and is cheaper than restoration with noble metal bridges. Conclusions Ceramic bridges with auro-galvanoforming (primary coping and Ni-Cr pontic) performed well for the restoration of dentition defects during this follow-up period. More studies are warranted to further evaluate this technique as an alternative to the conventional porcelain-fused-to-metal restoration.

  7. Rehabilitation of the edentulous mandible with implant-supported overdenture using ball attachments and healing abutments: A case report

    OpenAIRE

    PARK, JUN-BEOM

    2009-01-01

    For many years, osseointegrated implant-supported overdentures have been used in the rehabilitation of the edentulous lower jaw with excellent results. In this report, additional implants with healing abutments were applied posterior to mental foramen on each side was used to achieve additional support to the overdenture.

  8. The Relationship between Biofilm and Physical-Chemical Properties of Implant Abutment Materials for Successful Dental Implants

    Directory of Open Access Journals (Sweden)

    Erica Dorigatti de Avila

    2014-05-01

    Full Text Available The aim of this review was to investigate the relationship between biofilm and peri-implant disease, with an emphasis on the types of implant abutment surfaces. Individuals with periodontal disease typically have a large amount of pathogenic microorganisms in the periodontal pocket. If the individuals lose their teeth, these microorganisms remain viable inside the mouth and can directly influence peri-implant microbiota. Metal implants offer a suitable solution, but similarly, these remaining bacteria can adhere on abutment implant surfaces, induce peri-implantitis causing potential destruction of the alveolar bone near to the implant threads and cause the subsequent loss of the implant. Studies have demonstrated differences in biofilm formation on dental materials and these variations can be associated with both physical and chemical characteristics of the surfaces. In the case of partially edentulous patients affected by periodontal disease, the ideal type of implant abutments utilized should be one that adheres the least or negligible amounts of periodontopathogenic bacteria. Therefore, it is of clinically relevance to know how the bacteria behave on different types of surfaces in order to develop new materials and/or new types of treatment surfaces, which will reduce or inhibit adhesion of pathogenic microorganisms, and, thus, restrict the use of the abutments with indication propensity for bacterial adhesion.

  9. Effect of abutment angulation in the retention and durability of three overdenture attachment systems: An in vitro study

    Science.gov (United States)

    Ustrell, Raul; Mendes, Jose Manuel; Braga, Ana Cristina; Berastegui, Esther

    2016-01-01

    PURPOSE This in vitro study investigated and compared the durability and retention of three types of attachments. MATERIALS AND METHODS Three commercially available attachments were investigated: Clix®, Dalbo-Plus® and Locator®. In total, 72 samples of these attachments were placed in the acrylic resin forms and subjected to mechanical testing (5400 cycles of insertion and removal) over the respective ball or Locator abutments immersed in artificial saliva at pH 7 and 37℃. The abutments were placed at angulations of 0°, 10° and 20°. The retention force was recorded at the beginning and after 540, 1080, 2160, 3240, 4320 and 5400 insertion-removal cycles. RESULTS The results revealed that there were significant differences in the average values of the insertion/removal force due to angulation (F (2.48) = 343619, P<.05) and the type of attachment (F (7.48) = 23.220, P<.05). CONCLUSION Greater angulation of the abutments was found to influence the retention capacity of the attachments, and the fatigue test simulating 5 years of denture insertion and removal did not produce wear in the metal abutments. PMID:26949484

  10. Microbial diversity of supra- and subgingival biofilms on freshly colonized titanium implant abutments in the human mouth.

    Science.gov (United States)

    Heuer, W; Stiesch, M; Abraham, W R

    2011-02-01

    Supra- and subgingival biofilm formation is considered to be mainly responsible for early implant failure caused by inflammations of periimplant tissues. Nevertheless, little is known about the complex microbial diversity and interindividual similarities around dental implants. An atraumatic assessment was made of the diversity of microbial communities around titanium implants by single strand conformation polymorphism (SSCP) analysis of the 16S rRNA gene amplicons as well as subsequent sequence analysis. Samples of adherent supra- and subgingival periimplant biofilms were collected from ten patients. Additionally, samples of sulcusfluid were taken at titanium implant abutments and remaining teeth. The bacteria in the samples were characterized by SSCP and sequence analysis. A high diversity of bacteria varying between patients and within one patient at different locations was found. Bacteria characteristic for sulcusfluid and supra- and subgingival biofilm communities were identified. Sulcusfluid of the abutments showed higher abundance of Streptococcus species than from residual teeth. Prevotella and Rothia species frequently reported from the oral cavity were not detected at the abutments suggesting a role as late colonizers. Different niches in the human mouth are characterized by specific groups of bacteria. Implant abutments are a very valuable approach to study dental biofilm development in vivo. PMID:20931254

  11. Microbial diversity of supra- and subgingival biofilms on freshly colonized titanium implant abutments in the human mouth.

    Science.gov (United States)

    Heuer, W; Stiesch, M; Abraham, W R

    2011-02-01

    Supra- and subgingival biofilm formation is considered to be mainly responsible for early implant failure caused by inflammations of periimplant tissues. Nevertheless, little is known about the complex microbial diversity and interindividual similarities around dental implants. An atraumatic assessment was made of the diversity of microbial communities around titanium implants by single strand conformation polymorphism (SSCP) analysis of the 16S rRNA gene amplicons as well as subsequent sequence analysis. Samples of adherent supra- and subgingival periimplant biofilms were collected from ten patients. Additionally, samples of sulcusfluid were taken at titanium implant abutments and remaining teeth. The bacteria in the samples were characterized by SSCP and sequence analysis. A high diversity of bacteria varying between patients and within one patient at different locations was found. Bacteria characteristic for sulcusfluid and supra- and subgingival biofilm communities were identified. Sulcusfluid of the abutments showed higher abundance of Streptococcus species than from residual teeth. Prevotella and Rothia species frequently reported from the oral cavity were not detected at the abutments suggesting a role as late colonizers. Different niches in the human mouth are characterized by specific groups of bacteria. Implant abutments are a very valuable approach to study dental biofilm development in vivo.

  12. Distribution laws of abutment pressure around fully mechanized top-coal caving face by in-situ measurement

    Institute of Scientific and Technical Information of China (English)

    CHANG Ju-cai

    2011-01-01

    In order to obtain the distribution rules of abutment pressure around the 1151 (3) fully mechanized top-coal caving (FMTC) face of Xieqiao Colliery, the KSE-Ⅱ-1 type bore-hole stress gauges were installed in the tailentry and headentry to measure the mining-induced stress. The distribution rules of the front and side abutment pressure were demonstrated. The results show that distribution rules of stress are obviously different in the vicinity of the face and entries. The peak value of abutment pressure in the protective coal pillar and face are located commonly in front of the working face along the strike, and they are located at the stress-decreased zone near the face. There is no stress peak value in the lateral coal mass beside the headentry in front of the face on the strike, and the peak value of abutment pressure appears at the rear area of the face. There are stress peak values both in the protective coal pillar and in the lateral coal mass beside the headentry to the dip.

  13. Estimation of potential scour at bridges on local government roads in South Dakota, 2009-12

    Science.gov (United States)

    Thompson, Ryan F.; Wattier, Chelsea M.; Liggett, Richard R.; Truax, Ryan A.

    2014-01-01

    In 2009, the U.S. Geological Survey and South Dakota Department of Transportation (SDDOT) began a study to estimate potential scour at selected bridges on local government (county, township, and municipal) roads in South Dakota. A rapid scour-estimation method (level-1.5) and a more detailed method (level-2) were used to develop estimates of contraction, abutment, and pier scour. Data from 41 level-2 analyses completed for this study were combined with data from level-2 analyses completed in previous studies to develop new South Dakota-specific regression equations: four regional equations for main-channel velocity at the bridge contraction to account for the widely varying stream conditions within South Dakota, and one equation for head change. Velocity data from streamgages also were used in the regression for average velocity through the bridge contraction. Using these new regression equations, scour analyses were completed using the level-1.5 method on 361 bridges on local government roads. Typically, level-1.5 analyses are completed at flows estimated to have annual exceedance probabilities of 1 percent (100-year flood) and 0.2 percent (500-year flood); however, at some sites the bridge would not pass these flows. A level-1.5 analysis was then completed at the flow expected to produce the maximum scour. Data presented for level-1.5 scour analyses at the 361 bridges include contraction, abutment, and pier scour. Estimates of potential contraction scour ranged from 0 to 32.5 feet for the various flows evaluated. Estimated potential abutment scour ranged from 0 to 40.9 feet for left abutments, and from 0 to 37.7 feet for right abutments. Pier scour values ranged from 2.7 to 31.6 feet. The scour depth estimates provided in this report can be used by the SDDOT to compare with foundation depths at each bridge to determine if abutments or piers are at risk of being undermined by scour at the flows evaluated. Replicate analyses were completed at 24 of the 361 bridges

  14. Zirconia- versus metal-based, implant-supported abutments and crowns

    DEFF Research Database (Denmark)

    Hosseini, Mandana

    was to test the reliability and validity of six aesthetic parameters used at the Copenhagen Dental School to assess the aesthetic outcome of implant-supported restorations. The aims of study III and IV were to compare the influence of different abutment and crown materials on biological, biomechanical......To restore oral functions in patients with missing teeth, single-tooth implants are a well-documented treatment option. Along with high survival rates, aesthetic factors have become an important clinical outcome variable for evaluating treatment success of implant-supported restorations. Thus...... studies have reported on aesthetic, biological, biomechanical and patient-reported outcomes of implant-supported single-tooth restorations of various biomaterials. The aim of the present thesis was to investigate the clinical performance of zirconia-based implant-supported single-tooth restorations...

  15. RADIOACTIVE OR NATURAL TRACER。TECHNIQUES FOR LEAK DETERMINING OF DAM ABUTMENT

    Institute of Scientific and Technical Information of China (English)

    陈建生; 杜国平; 等

    1995-01-01

    Infiltration and localization of preferential infiltration zones at the dam abutment are measured using radioactive tracer tests of flow in boreholes,meanwhile interconnection between boreholes and the energing water points is analysed.The theory and practice of radioactive tracer synthetic detective method are described to give methods and calculation formulae used under the condition of stable flow in single well to measure permeability coefficient and hydrostatic heads.Major single hole techniques including measurement for seepage line,velocity,rate of seepage flow and relationship of recharge of groundwater in aquifers are introduced briefly.The possibilities offered by natureal tracers are analysed,uincluding electric-conduct,pH-value and temperature of water as well as stable isotopes(D,18O) and tritium.Furthermore,the sensibilities of this theory and methods were confirmed by detecting seepage flow field of Xinanjiang Dam.

  16. Taizhou Yangtze River Bridge

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Taizhou Bridge lies between Taizhou, Zhenjiang and Changzhou City in Jiangsu Province. The total length of Taizhou Bridge is 62.088 kin. The whole line is designed by freeway codes with six lanes in two directions. The wholeinvestment is 9.37 billion RMB and the planned construction duration is 5.5 years. The main bridge crossing the Yangtze River is a continuous three-pylon two-span suspension bridge with the main span of 1 080 m. The bridge system is realized for the first time and ranks first in the world until now.

  17. Accuracy of 3D white light scanning of abutment teeth impressions: evaluation of trueness and precision

    Science.gov (United States)

    Jeon, Jin-Hun; Kim, Hae-Young; Kim, Ji-Hwan

    2014-01-01

    PURPOSE This study aimed to evaluate the accuracy of digitizing dental impressions of abutment teeth using a white light scanner and to compare the findings among teeth types. MATERIALS AND METHODS To assess precision, impressions of the canine, premolar, and molar prepared to receive all-ceramic crowns were repeatedly scanned to obtain five sets of 3-D data (STL files). Point clouds were compared and error sizes were measured (n=10 per type). Next, to evaluate trueness, impressions of teeth were rotated by 10°-20° and scanned. The obtained data were compared with the first set of data for precision assessment, and the error sizes were measured (n=5 per type). The Kruskal-Wallis test was performed to evaluate precision and trueness among three teeth types, and post-hoc comparisons were performed using the Mann-Whitney U test with Bonferroni correction (α=.05). RESULTS Precision discrepancies for the canine, premolar, and molar were 3.7 µm, 3.2 µm, and 7.3 µm, respectively, indicating the poorest precision for the molar (Pteeth types were 6.2 µm, 11.2 µm, and 21.8 µm, respectively, indicating the poorest trueness for the molar (P=.007). CONCLUSION In respect to accuracy the molar showed the largest discrepancies compared with the canine and premolar. Digitizing of dental impressions of abutment teeth using a white light scanner was assessed to be a highly accurate method and provided discrepancy values in a clinically acceptable range. Further study is needed to improve digitizing performance of white light scanning in axial wall. PMID:25551007

  18. Finite Element and Experimental Analysis and Evaluation of Static and Dynamic Responses of Oblique Pre-stressed Concrete Box Girder Bridge

    Directory of Open Access Journals (Sweden)

    Ali Fadhil Naser

    2013-10-01

    Full Text Available Hashuang bridge is type of prestressed concrete box girder oblique bridge and it is located in Harbin City within Heilongjiang province in the east north of China. The objectives of this study are to investigate the appearance of the bridge structure and identify all the damages in the bridge structural members and to evaluate the structural performance of the bridge structure under dead and live loads. Finite element analysis is used to analyze the static designed internal forces and dynamic responses by adopting SAP200 software Ver. 14.2.0. Static and dynamic load test are adopted to evaluate the structural performance of the bridge structure. The results of field investigation process of the bridge appearance show that the bridge suffers from serious damages. The web of box girder of the second span near pier No.2 (in the quarter of middle span at 39m on the bridge length suffers from serious shear cracks. The state of abutments, piers and sidewalks is good, but the bearing, drainage holes, steel rail and expansion joints are not good and they suffer from much damage. The steel rail is corroded and the expansion joint loses the material which fills the joint. There are many dusts and debris is collected on the bridge deck in the location near sidewalk. The analysis results of finite element and load tests show that there are high tensile stresses in the quarter of middle span at distance 39 m of the bridge length and the state of the bridge structure is not good and the main problem of the bridge structure in the original design of prestressed tendons. Therefore, this study recommends for repairing and strengthening the bridge structure to increase the stiffness and strength and to improve the bearing capacity of the bridge structural members to increase the service live of the bridge structure.

  19. Bone loss at implant with titanium abutments coated by soda lime glass containing silver nanoparticles: a histological study in the dog.

    Science.gov (United States)

    Martinez, Arturo; Guitián, Francisco; López-Píriz, Roberto; Bartolomé, José F; Cabal, Belén; Esteban-Tejeda, Leticia; Torrecillas, Ramón; Moya, José S

    2014-01-01

    The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression. PMID:24466292

  20. Bone loss at implant with titanium abutments coated by soda lime glass containing silver nanoparticles: a histological study in the dog.

    Directory of Open Access Journals (Sweden)

    Arturo Martinez

    Full Text Available The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression.

  1. Finite element model updating of a prestressed concrete box girder bridge using subproblem approximation

    Science.gov (United States)

    Chen, G. W.; Omenzetter, P.

    2016-04-01

    This paper presents the implementation of an updating procedure for the finite element model (FEM) of a prestressed concrete continuous box-girder highway off-ramp bridge. Ambient vibration testing was conducted to excite the bridge, assisted by linear chirp sweepings induced by two small electrodynamic shakes deployed to enhance the excitation levels, since the bridge was closed to traffic. The data-driven stochastic subspace identification method was executed to recover the modal properties from measurement data. An initial FEM was developed and correlation between the experimental modal results and their analytical counterparts was studied. Modelling of the pier and abutment bearings was carefully adjusted to reflect the real operational conditions of the bridge. The subproblem approximation method was subsequently utilized to automatically update the FEM. For this purpose, the influences of bearing stiffness, and mass density and Young's modulus of materials were examined as uncertain parameters using sensitivity analysis. The updating objective function was defined based on a summation of squared values of relative errors of natural frequencies between the FEM and experimentation. All the identified modes were used as the target responses with the purpose of putting more constrains for the optimization process and decreasing the number of potentially feasible combinations for parameter changes. The updated FEM of the bridge was able to produce sufficient improvements in natural frequencies in most modes of interest, and can serve for a more precise dynamic response prediction or future investigation of the bridge health.

  2. Effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations: in vitro study of color masking ability

    Science.gov (United States)

    Oh, Seon-Hee

    2015-01-01

    PURPOSE The aim of the study was to evaluate the effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations. MATERIALS AND METHODS Three different types of disk-shaped zirconia coping specimens (Lava, Cercon, Zirkonzahn: ø10 mm × 0.4 mm) were fabricated and veneered with IPS e.max Press Ceram (shade A2), for total thicknesses of 1 and 1.5 mm. A total of sixty zirconia restoration specimens were divided into six groups based on their coping types and thicknesses. The abutment specimens (ø10 mm × 7 mm) were prepared with gold alloy, base metal (nickel-chromium) alloy, and four different shades (A1, A2, A3, A4) of composite resins. The average L*, a*, b* values of the zirconia specimens on the six abutment specimens were measured with a dental colorimeter, and the statistical significance in the effects of three variables was analyzed by using repeated measures analysis of variance (α=.05).The average shade difference (ΔE) values of the zirconia specimens between the A2 composite resin abutment and other abutments were also evaluated. RESULTS The effects of zirconia specimen thickness (P<.001), abutment shade (P<.001), and type of zirconia copings (P<.003) on the final shade of the zirconia restorations were significant. The average ΔE value of Lava specimens (1 mm) between the A2 composite resin and gold alloy abutments was higher (close to the acceptability threshold of 5.5 ΔE) than th ose between the A2 composite resin and other abutments. CONCLUSION This in-vitro study demonstrated that abutment shade, ceramic thickness, and coping type affected the resulting shade of zirconia restorations. PMID:26576252

  3. 多年冻土区路桥过渡段的一种新结构%A New Structure of Roadbed-Abutment Transition Part on Permafrost

    Institute of Scientific and Technical Information of China (English)

    刘建坤; 鲍维猛; 黎明; 葛建军

    2004-01-01

    The design of roadbed-abutment transition part is always a challenging problem in transportation engineering, especially in permafrost distribution zone. A new type of roadbed-abutment transition part on permafrost was presented, and long-term observation was conducted for the deformation and the thermal regime of a roadbed-abutment transition part in the constructing Qinghai-Tibet Railway. In this paper, a new structure was presented and the observed settlements both in the subgrade and the base and its dependency with the thermal regime (permafrost table) were analyzed. In conclusion the roadbed-a-butment transition method for permafrost distribution zone was evaluated.

  4. Bone Loss at Implant with Titanium Abutments Coated by Soda Lime Glass Containing Silver Nanoparticles: A Histological Study in the Dog

    OpenAIRE

    Martinez, Arturo; Guitián, Francisco; López-Píriz, R.; Bartolomé, J. F.; Cabal, B.; Esteban-Tejeda, L.; Torrecillas, Ramón; J. S. Moya

    2014-01-01

    The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental...

  5. Fatigue cyclic loading test of an auro-galvanoforming ceramic bridge

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiang-hao; SUN Feng; WANG Huan; XU Man-qiong

    2008-01-01

    Background In dental clinics, dentition defects are commonly restored with conventional porcelain-fused-to-metal fixedbridges. However, Ni-Cr alloy ceramic fixed bridges are known to have several drawbacks such as marginal coloration of the neck, low casting precision and, most seriously, poor biocompatibility. These problems could be circumvented by using noble metal ceramic bridges; however, one negative issue related to the conventional noble metal ceramic bridges is its high price due to the use of a large amount of gold for pontic. Therefore, an auro-galvanoforming ceramic bridge would be ideal to retain the advantages of a conventional material, yet reduce the amount of noble metal used. This study aimed to investigate whether any destructive changes occur to the auro-galvanoforming ceramic bridge under a fatigue cyclic loading test.Methods On standard models which the left maxillary first premolar is lost and with the cuspid teeth and the second premolar as the fixed bridge abutment teeth, six maxillary auro-galvanoforming ceramic bridges and six corresponding nichrome ceramic jointed crowns were made as group A, six nichrome ceramic bridges and six corresponding nichromeceramic jointed crowns were made as group B (control group). And then all specimens were fixed and tested on a fatigue cyclic loading machine; the changes occurring to the surfaces of occlusal contact with large functional area and to the porcelain-metal interfaces of the nichrome primary copings margins were observed through a scanning electron microscope (SEM).Results In 120 hours' continual observation, none of the specimens had porcelain coating fractures or scraping occurrence and all of the porcelain coatings had been kept intact under sinusoidal cyclic loading with the load range of 120-200 N and frequency of 5 Hz.Conclusions Auro-galvanoforming ceramic bridges exhibited excellent fatigue strength in the fatigue cyclic loading test and may satisfy the clinical demand in theory, while

  6. Concrete bridge prioritization system

    OpenAIRE

    Kesselring, Debbie Anne

    1995-01-01

    An alternative method of prioritization for concrete bridge maintenance, repair, and rehabilitation activities is required due to the inability of the current system to manage the increasing nmnber of aging concrete bridges. The Concrete Bridge Prioritization System was proposed because of its ability to address the critical technical parameters of safety and cost benefit in prioritization of funding and work allocation. The analysis includes four parts, service life assessment, s...

  7. Bridging the Gap

    DEFF Research Database (Denmark)

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska;

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures.......Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures....

  8. Bridging the Gap

    OpenAIRE

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska; Murdock, Karen; Schmidt, Iben Julie

    2015-01-01

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures. Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ve...

  9. Semiconductor bridge (SCB) detonator

    Science.gov (United States)

    Bickes, Jr., Robert W.; Grubelich, Mark C.

    1999-01-01

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  10. Level II scour analysis for Bridge 29 (HUNTTH00290029) on Town Highway 29, crossing Cobb Brook, Huntington, Vermont

    Science.gov (United States)

    Flynn, Robert H.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00290029 on Town Highway 29 crossing Cobb Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in northwestern Vermont. The 4.16-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest upstream and downstream of the bridge. In the study area, Cobb Brook has an incised, straight channel with a slope of approximately 0.024 ft/ft, an average channel top width of 53 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to bedrock with a median grain size (D50) of 112.0 mm (0.367 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 25, 1996, indicated that the reach was stable. The Town Highway 29 crossing of Cobb Brook is a 36-ft-long, one-lane bridge consisting of one 30-foot steel-beam span (Vermont Agency of Transportation, written communication, December 11, 1995) and a wooden deck. The opening length of the structure parallel to the bridge face is 27 ft.The bridge is supported by vertical, concrete abutments. The channel is skewed approximately 25 degrees to the opening while the opening-skew-to-roadway was measured to be 20 degrees. VTAOT records indicate an opening-skew-to-roadway of zero degrees. A scour hole 1.5 ft deeper than

  11. Clinical analysis of the influence of temporary crowns on abutment and implant after tooth preparation%牙体制备后临时冠桥修复对基牙及修复体影响的临床分析

    Institute of Scientific and Technical Information of China (English)

    吴启建; 徐敏; 李桂苓

    2015-01-01

    Objective Analysis the effect of temporary crown and bridge repair on the abutment and dental restoration. Methods Randomly selected 80 patients between 2013-2014 a clinical investigation, using retrospective analysis method, the application of direct or indirect method, improve the function, cosmetic repair effect.Results All patients were back on time,within the given time line PFM, casting crown and bridge repair, clinical observation, try effect is good,smooth in place restoration,restoration margin closed closed, try occlusal height is normal, no displacement of abutment teeth, no missing area, elongation polices jaw teeth.Temporary crown bridge can protect the abutment teeth, protect fix clearance and occlusal relationship, avoid teeth mobile embedded plug caused by food, maintain a healthy oral and periodontal tissue. Play a good role.Conclusion The temporary crown and bridge of protect teeth, worth clinical promotion.%目的:分析牙体制备后临时冠桥修复对基牙及修复体的影响。方法选取2013~2014年我院收治的患者80例,采用回顾分析法,应用直接或间接制作方法,提高功能,美观的修复效果。结果本组患者均在规定时间内按时复诊,行烤瓷、铸造冠桥的修复,临床观察,试戴效果良好,顺利就位修复体,修复体边缘封闭密合,试戴咬合高度正常,无基牙移位,无缺失区,対颌牙伸长。临时冠桥的制作能保护基牙,保护修复间隙和咬合关系,避免牙齿移动引起食物嵌塞,维护口腔牙周组织健康。结论临时冠桥所起到的保护牙齿作用,值得临床推广使用。

  12. Bone response from a dynamic stimulus on a one-piece and multi-piece implant abutment and crown by finite element analysis.

    Science.gov (United States)

    Hajimiragha, Habib; Abolbashari, Mohammadreza; Nokar, Saeed; Abolbashari, AmirHossein; Abolbashari, Mehrdad

    2014-10-01

    The present study was done to evaluate the effects of different types of abutments on the rate and distribution of stress on the bone surrounding the implant by dynamic finite element analysis method. In this study two ITI abutment models-one-piece and multi-piece-along with fixture, bone, and superstructure have been simulated with the help of company-made models. The maximum Von Mises stress (MVMS) was observed in the distobuccal area of the cortical bone near the crest of implant in two implant models. In the multi-piece abutment, MVMS was higher than the one-piece model (27.9 MPa and 23.3 MPa, respectively). Based on the results of this study, it can be concluded that type of abutment influences the stress distribution in the area surrounding the implant during dynamic loading.

  13. Randomized Controlled Clinical Trial of All-Ceramic Single Tooth Implant Reconstructions Using Modified Zirconia Abutments: Radiographic and Prosthetic Results at 1 Year of Loading

    OpenAIRE

    Thoma, Daniel S.; Brandenberg, Francine; Fehmer, Vincent; Büchi, Dominik L.E.; Hämmerle, Christoph H.F.; Sailer, Irena

    2015-01-01

    This study aims to test whether or not veneering of the submucosal part of zirconia abutments with pink dental ceramic affects radiographic and technical outcomes of implant-supported single crowns (ISSC).

  14. 谈公路桥梁沉降段路基路面施工%Discussion on subgrade pavement construction of highway bridge subsidence section

    Institute of Scientific and Technical Information of China (English)

    路海清

    2015-01-01

    简述了公路桥梁沉降引发的危害性,通过分析台背地基、路堤、桥头搭板末端发生变形的基本原理,从地基处理、填料控制等方面探讨了公路桥梁沉降段路基路面施工的措施,以避免公路桥梁沉降现象的发生。%The thesis describes highway bridge subsidence hazards,analyzes basic principles of abutment foundation,subgrade,bridge head board deformation,and explores subgrade pavement construction measures of highway bridge subsidence section from aspects of foundation treat-ment,filling material control and so on,with a view to avoid highway bridge subsidence.

  15. Clinical Outcome of Inter-Proximal Papilla between a Tooth and a Single Implant Treated with CAD/CAM Abutments: a Cross-Sectional Study

    OpenAIRE

    Tiago Borges; Tiago Lima; Ágata Carvalho; Vasco Carvalho

    2012-01-01

    ABSTRACT Objectives The aim of this study was to assess the clinical outcomes achieved with Computer-Assisted Design/Computer-Assisted Manufacturing implant abutments in the anterior maxilla. Material and Methods Nineteen patients with a mean age of 41 (range form 26 to 63) years, treated with 21 single tooth implants and 21 Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM) abutments in the anterior maxillary region were included in this study. The patients followed 4 criteri...

  16. Environmentally Friendly Solution to Ground Hazards in Design of Bridges in Earthquake Prone Areas Using Timber Piles

    Science.gov (United States)

    Sadeghi, H.

    2015-12-01

    Bridges are major elements of infrastructure in all societies. Their safety and continued serviceability guaranties the transportation and emergency access in urban and rural areas. However, these important structures are subject to earthquake induced damages in structure and foundations. The basic approach to the proper support of foundations are a) distribution of imposed loads to foundation in a way they can resist those loads without excessive settlement and failure; b) modification of foundation ground with various available methods; and c) combination of "a" and "b". The engineers has to face the task of designing the foundations meeting all safely and serviceability criteria but sometimes when there are numerous environmental and financial constrains, the use of some traditional methods become inevitable. This paper explains the application of timber piles to improve ground resistance to liquefaction and to secure the abutments of short to medium length bridges in an earthquake/liquefaction prone area in Bohol Island, Philippines. The limitations of using the common ground improvement methods (i.e., injection, dynamic compaction) because of either environmental or financial concerns along with the abundance of timber in the area made the engineers to use a network of timber piles behind the backwalls of the bridge abutments. The suggested timber pile network is simulated by numerical methods and its safety is examined. The results show that the compaction caused by driving of the piles and bearing capacity provided by timbers reduce the settlement and lateral movements due to service and earthquake induced loads.

  17. Distribution pattern of front abutment pressure of fully-mechanized working face of soft coal isolated island

    Institute of Scientific and Technical Information of China (English)

    Xu Wenquan; Wang Enyuan; Shen Rongxi; Song Dazhao; Zhang Jingmin

    2012-01-01

    The front abutment pressure of a fully-mechanized workface of 11061 soft coal isolated island of Liangbei Coal Mine was measured and studied using a self-developed mining-induced stress monitoring system associated with electromagnetic radiation technology,and the effects of abutment pressure distribution on strata behavior we discussed.The results indicate that the mining-induced influencing distance advanced at the fully-mechanized working face of soft coal isolated island is larger than that at the general working face at the isolated island,besides the fracture zone in front of working face was widened to some extent,and the influencing range caused by relaxations on both roadways became bigger with the advancing working face.Moreover,it can be indicated that mining has significant effect on strata behavior of fully-mechanized working face of soft coal isolated island,which is mostly distributed in the area of stress concentration.The research results have an important reference value for revealing the distribution pattern of the front abutment pressure of a fully-mechanized working face of soft coal isolated island,and controlling the coal-rock dynamic disaster occurrence under similar mining conditions.

  18. Analysis of Stability of Gaixia Arch Dam Abutment%盖下拱坝坝肩稳定分析

    Institute of Scientific and Technical Information of China (English)

    房巍; 刘晓青

    2011-01-01

    Taking Gaixia arch dam as the object of the research and combining finite elements and rigid limit equilibrium method to study the stability of Gaixia arch dam abutment in static and dynamic conditions, the anti-slide safety factor of the abutment is obtained. The results satisfy the specification; it is shown that the Gaixia arch dam abutment is safe. The results can be taken as reference for practical projects.%以盖下拱坝为研究对象,结合有限元和刚体极限平衡法,分析了盖下拱坝坝肩岩体在静、动力条件下的稳定性,得到坝肩岩体的抗剪安全系数.所得结果满足规范要求,说明盖下拱坝坝肩是稳定的.研究成果为实际工程提供了参考依据.

  19. Principles of Bridge Reliability

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Nowak, Andrzej S.

    The paper gives a brief introduction to the basic principles of structural reliability theory and its application to bridge engineering. Fundamental concepts like failure probability and reliability index are introduced. Ultimate as well as serviceability limit states for bridges are formulated...

  20. The floating water bridge

    International Nuclear Information System (INIS)

    When high voltage is applied to distilled water filled in two glass beakers which are in contact, a stable water connection forms spontaneously, giving the impression of a floating water bridge. A detailed experimental analysis reveals static and dynamic structures as well as heat and mass transfer through this bridge

  1. USE THE REIMPLANTED TOOTH AS ABUTMENT FOR FIXED PAR TIAL DENTURE

    Directory of Open Access Journals (Sweden)

    Golmoradizadeh

    2013-04-01

    Full Text Available ABSTRACT: OBJECTIVE: Use of the fixed partial denture is more favorable t han the removable partial denture for my patient, she complained about e dentulism in upper right side and a little discomfort with second upper premolar. Clinical examin ation shows the tooth was crown less and radio graphically tooth had a big periapical lesi on with poor prognosis. METHOD: After root canal treatment and extraction the tooth, clea n and irrigate the socket, we are implanted it with hydroxyapatite again and follow the patient for six months. After six months, radio graph shows that the tooth was in ideal condition without mobility, then the tooth has used as an abutment for fixed partial denture with canine and 2 nd molar in order to have a better prognosis we used semi precision attachment, and foll ow her for three years. RESULT: Three years follow the patient shows the tooth is in an ac ceptable condition radio-graphically without mobility and patient was comfortable esthetically a nd functionally. CONCLUSION: In my opinion in this case use of the hydroxyapatite, crown lengthening during the re- implantation and use the semi precision attachment was the reaso n of increase the prognosis after treatment

  2. Effects of Dental Implant-abutment Interfaces on the Reliability of Implant Systems

    Directory of Open Access Journals (Sweden)

    Zhang Xiao

    2016-01-01

    Full Text Available In this paper, by analyzing the effects of two different kinds of implant-abutment connection interfaces under the same working condition on the mechanical and fatigue performances of the implant system as well as on the surrounding bones, we intend to study such effects on the reliability of the implants and provide a theoretical basis for the design and clinical application of dental implant systems. For the purpose, we adopt a 3-D modeling method to establish the model, and use FEA (finite element analysis to carry out static mechanic and fatigue analysis on the implant system and its surrounding bones; then we make the two implant systems, and carry out fatigue tests on a dynamic fatigue testing machine to verify the FEA results. After comparing the results from the two different systems, we find that the stress distribution and fatigue safety factor of the system which has deeper axial matching of the taper connection are better than those of the other system, that is to say, between the two major elements of a implant system, the axial length of the connecting taper and the size of the hexagon, the former has greater effects than the latter. When the axial matching is deeper, the stress distribution of the implant system will be better, the fatigue safety factor will be higher, and the implant system will be more reliable.

  3. Streambed scour evaluations and conditions at selected bridge sites in Alaska, 2012

    Science.gov (United States)

    Beebee, Robin A.; Schauer, Paul V.

    2015-11-19

    Streambed scour potential was evaluated at 18 river- and stream-spanning bridges in Alaska that have unknown foundation details or a lack of existing scour analysis. All sites were evaluated for stream stability and long-term scour potential. Contraction scour and abutment scour were calculated for 17 bridges, and pier scour was calculated for 7 bridges that had piers. Vertical contraction (pressure flow) scour was calculated for sites with overtopping floods (where the modeled water surface was higher than the superstructure of the bridge). In most cases, hydraulic models of the 1- and 0.2-percent annual exceedance probability floods (also known as the 100- and 500-year floods, respectively) were used to derive hydraulic variables for the scour calculations. Alternate flood values were used in scour calculations for sites where smaller floods overtopped a bridge or where standard flood-frequency estimation techniques did not apply. Scour was also calculated for large recorded floods at several sites. Equations for scour in cohesive soils were used for sites where streambed sediment was silt-sized or smaller.

  4. Indian practice on estimation of scour around bridge piers—A comment

    Indian Academy of Sciences (India)

    Umesh C Kothyari

    2007-06-01

    Well-laid foundation is mostly provided in road and railway bridges in India over large and medium-sized rivers. The age-old Lacey–Inglis method is used for estimation of the design scour depth around bridge elements such as pier, abutment, guide bank, spur and groyene. Codal provisions are seen to produce too large a scour depth around bridge elements resulting in bridge sub-structures that lead to increased construction costs. Limitations that exist in the codes of practice are illustrated in this paper using examples. The methods recently developed for estimation of the scour are described. New railway and road bridges are required to be built in large numbers in the near future across several rivers to strengthen such infrastructure in the country. It is strongly felt that provisions in the existing codes of practice for determination of design scour depth require immediate review. The present paper provides a critical note on the practices followed in India for estimating the design scour depth.

  5. Level II scour analysis for Bridge 12 (BRAITH00230012) on Town Highway 23, crossing Ayers Brook, Braintree, Vermont

    Science.gov (United States)

    Olson, Scott A.

    1996-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure BRAITH00230012 on town highway 23 crossing Ayers Brook, Braintree, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I study is included in Appendix E of this report. A Level I study provides a qualitative geomorphic characterization of the study site. Information on the bridge available from VTAOT files was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the Green Mountain physiographic province of central Vermont in the town of Braintree. The 18.8-mi2 drainage area is in a predominantly rural watershed. In the vicinity of the study site, the surface cover of the left and right banks is pasture. In the study area, Ayers Brook has a meandering channel with a slope of approximately 0.003 ft/ft, an average channel top width of 46 ft and an average channel depth of 5 ft. The predominant channel bed material is sand and gravel (D50 is 6.15 mm or 0.0202 ft). The geomorphic assessment at the time of the Level I and Level II site visit on November 16, 1994, indicated that the reach was laterally unstable. Also at the time of the site visit, there was considerable backwater at the bridge site due to a beaver dam downstream. The beaver dam was ignored in the analyses. The town highway 23 crossing of Ayers Brook is a 28-ft-long, one-lane bridge consisting of one 23-foot span (Vermont Agency of Transportation, written communication, August 24, 1994). The bridge is supported by vertical timber cribwork abutments with wingwalls on the upstream and downstream sides of the right abutment. The lower half of the right abutment and wingwalls are constructed of laid-up stone. The right abutment and wingwalls are also protected by stone fill. The channel is skewed approximately 45

  6. Bridge technology report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. As LANs have proliferated, new technologies and system concepts have come to the fore. One of the key issues is how to interconnect networks. One means of interconnection is to use a 'bridge'. Other competing technologies are repeaters, routers, and gateways. Bridges permit traffic isolation, connect network segments together and operate at the MAC layer. Further, because they operate at the MAC layer, they can handle a variety of protocols such as TCP/IP, SNA, and X.25. This report focuses on the specific technology of bridging two netw

  7. In vitro evaluation of fracture resistance of Fiber-Reinforced Composite inlay bridges in upper anterior and lower posterior teeth

    Directory of Open Access Journals (Sweden)

    Jalalian E.

    2007-07-01

    Full Text Available Background and Aim: Considering flexural strength of fiber-reinforced composites (FRC and also the role of conservative cavities in protecting sound tissue of abutments, the aim of this study was to evaluate the fracture resistance of these bridges by handmade samples in vitro.Materials and Methods: In this experimental in vitro study, 44 sound newly extracted teeth were used to make 22 fixed inlay bridges including 11 three unit anterior upper inlay bridges substituting clinical model of upper central and 11 three unit posterior lower inlay bridges substituting clinical model of lower first molar. Specimens were prepared with FRC and mounted with artificial PDL in acryl. Cases were exposed to final load by using Universal Testing Machine (Instron 1195 with the speed of 1 mm/min. Statistical analysis was performed by Kolmogorov- Smirnov, independent sample T and Kaplan-Meier tests with p<0.05 as the level of significance.Results: Based on the statistical tests, the 95% confidence interval of mean was 450-562 N in anterior and  1473- 1761 N in posterior area. Fracture strength was high in the studied groups. Fractures in both groups occurred on composite facing, and the framework remained intact. The highest percentage of fracture in posterior teeth was in the middle of pontic towards the distal connector and in the anterior teeth in the lateral connector, between central pontic and lateral abutment. Using the independent sample T  test a significant statistical difference was observed between two groups (P<0.001. The fracture resistance of anterior samples was lower than the posterior ones.Conclusion: Based on the results of this study regarding the high fracture resistance in both areas FRC inlay bridges could be recommended for upper anterior and lower posterior teeth in clinical dentistry certainly more studies are needed to ascertain this treatment option.

  8. Bridged Race Population Estimates

    Data.gov (United States)

    U.S. Department of Health & Human Services — Population estimates from "bridging" the 31 race categories used in Census 2000, as specified in the 1997 Office of Management and Budget (OMB) race and ethnicity...

  9. Long Span Bridges in Scandinavia

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1998-01-01

    The first Scandinavian bridge with a span of more than 500 m was the Lillebælt Suspension Bridge opened to traffic in 1970.Art the end of the 20th century the longest span of any European bridge is found in the Storebælt East Bridge with a main span of 1624 m. Also the third longest span in Europ...

  10. Level II scour analysis for Bridge 26 (ROYATH00540026) on Town Highway 54, crossing Broad Brook, Royalton, Vermont

    Science.gov (United States)

    Burns, Ronda L.; Weber, Matthew A.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure ROYATH00540026 on Town Highway 54 crossing Broad Brook, Royalton, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 11.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover on the left bank upstream and downstream is pasture with trees and brush on the immediate banks. The right bank, upstream and downstream of the bridge, is forested. In the study area, Broad Brook has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 37 ft and an average bank height of 4 ft. The channel bed material ranges from sand to boulders with a median grain size (D50) of 66.3 mm (0.218 ft). The geomorphic assessment at the time of the Level I site visit on April 13, 1995 and the Level II site visit on July 11, 1996, indicated that the reach was stable. The Town Highway 54 crossing of Broad Brook is a 29-ft-long, one-lane bridge consisting of one 24-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, March 23, 1995). The opening length of the structure parallel to the bridge face is 23.3 ft. The bridge is supported by a vertical, concrete face laid-up stone abutment with concrete wingwalls on the left and a laid-up stone

  11. An in vivo assessment of the effects of using different implant abutment occluding materials on implant microleakage and the peri-implant microbiome

    Science.gov (United States)

    Rubino, Caroline

    Microleakage may be a factor in the progression of peri-implant pathology. Microleakage in implant dentistry refers to the passage of bacteria, fluids, molecules or ions between the abutment-implant interface to and from the surrounding periodontal tissues. This creates a zone of inflammation and reservoir of bacteria at the implant-abutment interface. Bone loss typically occurs within the first year of abutment connection and then stabilizes. It has not yet been definitively proven that the occurrence of microleakage cannot contribute to future bone loss or impede the treatment of peri-implant disease. Therefore, strategies to reduce or eliminate microleakage are sought out. Recent evidence demonstrates that the type of implant abutment channel occluding material can affect the amount of microleakage in an in vitro study environment. Thus, we hypothesize that different abutment screw channel occluding materials will affect the amount of observed microleakage, vis-a-vis the correlation between the microflora found on the abutment screw channel occluding material those found in the peri-implant sulcus. Additional objectives include confirming the presence of microleakage in vivo and assessing any impact that different abutment screw channel occluding materials may have on the peri-implant microbiome. Finally, the present study provides an opportunity to further characterize the peri-implant microbiome. Eight fully edentulous patients restored with at dental implants supporting screw-retained fixed hybrid prostheses were included in the study. At the initial appointment (T1), the prostheses were removed and the implants and prostheses were cleaned. The prostheses were then inserted with polytetrafluoroethylene tape (PTFE, TeflonRTM), cotton, polyvinyl siloxane (PVS), or synthetic foam as the implant abutment channel occluding material and sealed over with composite resin. About six months later (T2), the prostheses were removed and the materials collected. Paper

  12. Transpulmonary computed tomography-guided radiofrequency ablation of liver neoplasms abutting the diaphragm with multiple bipolar electrodes

    Directory of Open Access Journals (Sweden)

    Q Zhang

    2015-01-01

    Full Text Available Background: Neoplasm abutting the diaphragm is one kind of the special sites of liver neoplasms treated with radiofrequency ablation (RFA, the purpose of this study is to evaluate the feasibility and safety of computed tomography (CT-guided RFA of liver neoplasms abutting the diaphragm with multiple bipolar electrodes sequentially passing through the lung parenchyma. Materials and Methods: 37 patients were treated with transpulmonary CT-guided RFA. Technical success rate, perioperative complications, and local tumor progression were investigated. Results: The number of electrode (s sequentially passing through the lung parenchyma (NPLP was 1 electrode in 20 patients, 2 electrodes in 14 cases, and 3 electrodes in 3 cases. Technical success rate was 100%. The most of the perioperative complications were self-limiting and mainly included pneumothorax (11 cases, 2 needed percutaneous drainage, hemorrhage of the electrode track in the lung parenchyma (6 cases, a small amount of hemoperitoneum in perihepatic space (8 cases and discomfort of the right shoulder (7 cases. Local tumor progression occurred in 6 cases during the follow-up (3–12 months. Multivariate logistic regression analysis showed that the incidence of pneumothorax was not related to NPLP (P = 0.50, length of the electrode (s in the lung parenchyma (P = 0.18, types of anesthesia (P = 0.10, and indwelling time of the electrode (s in the lung parenchyma (P = 0.28. Conclusion: CT-guided RFA of liver neoplasms abutting the diaphragm with multiple bipolar electrodes sequentially passing through the lung parenchyma is a feasible and safe therapeutic option.

  13. Level II scour analysis for Bridge 48 (FFIETH00300048) on Town Highway 30, crossing Wanzer Brook, Fairfield, Vermont

    Science.gov (United States)

    Flynn, Robert H.; Boehmler, Erick M.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure FFIETH00300048 on Town Highway 30 crossing Wanzer Brook, Fairfield, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in northwestern Vermont. The 6.78-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover upstream of the bridge and on the downstream right bank is primarily pasture. The downstream left bank is forested. In the study area, Wanzer Brook has an incised, straight channel with a slope of approximately 0.03 ft/ft, an average channel top width of 65 ft and an average bank height of 5 ft. The channel bed material is cobble with a median grain size (D50) of 111 mm (0.364 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 11, 1995, indicated that the reach was stable. The Town Highway 30 crossing of Wanzer Brook is a 31-ft-long, two-lane bridge consisting of one 28-foot steel-beam span (Vermont Agency of Transportation, written communication, March 8, 1995). The opening length of the structure parallel to the bridge face is 26 ft.The bridge is supported by vertical stone wall abutments with concrete caps and “kneewall” footings. The channel is skewed approximately 25 degrees to the opening while the measured opening-skew-to-roadway is 20 degrees. A scour hole 1.5 ft deeper than

  14. Carpal Tunnel Cross-Sectional Area Affected by Soft Tissues Abutting the Carpal Bones.

    Science.gov (United States)

    Gabra, Joseph N; Li, Zong-Ming

    2013-02-01

    The carpal tunnel accommodates free movement of its contents, and the tunnel's cross-sectional area is a useful morphological parameter for the evaluation of the space available for the carpal tunnel contents and of potential nerve compression in the tunnel. The osseous boundary of the carpal bones as the dorsal border of the carpal tunnel is commonly used to determine the tunnel area, but this boundary contains soft tissues such as numerous intercarpal ligaments and the flexor carpi radialis tendon. The aims of this study were to quantify the thickness of the soft tissues abutting the carpal bones and to investigate how this soft tissue influences the calculation of the carpal tunnel area. Magnetic resonance images were analyzed for eight cadaveric specimens. A medical balloon with a physiological pressure was inserted into an evacuated tunnel to identify the carpal tunnel boundary. The balloon-based (i.e. true carpal tunnel) and osseous-based carpal tunnel boundaries were extracted and divided into regions corresponding to the hamate, capitate, trapezoid, trapezium, and transverse carpal ligament (TCL). From the two boundaries, the overall and regional soft tissue thicknesses and areas were calculated. The soft tissue thickness was significantly greater for the trapezoid (3.1±1.2mm) and trapezium (3.4±1.0mm) regions than for the hamate (0.7±0.3mm) and capitate (1.2±0.5mm) regions. The carpal tunnel area using the osseous boundary (243.0±40.4mm(2)) was significantly larger than the balloon-based area (183.9±29.7mm(2)) with a ratio of 1.32. In other words, the carpal tunnel area can be estimated as 76% (= 1/1.32) of the osseous-based area. The abundance of soft tissue in the trapezoid and trapezium regions can be attributed mainly to the capitate-trapezium ligament and the flexor carpi radialis tendon. Inclusion of such soft tissue leads to overestimations of the carpal tunnel area. Correct quantification of the carpal tunnel area aids in examining carpal

  15. Carpal Tunnel Cross-Sectional Area Affected by Soft Tissues Abutting the Carpal Bones.

    Science.gov (United States)

    Gabra, Joseph N; Li, Zong-Ming

    2013-02-01

    The carpal tunnel accommodates free movement of its contents, and the tunnel's cross-sectional area is a useful morphological parameter for the evaluation of the space available for the carpal tunnel contents and of potential nerve compression in the tunnel. The osseous boundary of the carpal bones as the dorsal border of the carpal tunnel is commonly used to determine the tunnel area, but this boundary contains soft tissues such as numerous intercarpal ligaments and the flexor carpi radialis tendon. The aims of this study were to quantify the thickness of the soft tissues abutting the carpal bones and to investigate how this soft tissue influences the calculation of the carpal tunnel area. Magnetic resonance images were analyzed for eight cadaveric specimens. A medical balloon with a physiological pressure was inserted into an evacuated tunnel to identify the carpal tunnel boundary. The balloon-based (i.e. true carpal tunnel) and osseous-based carpal tunnel boundaries were extracted and divided into regions corresponding to the hamate, capitate, trapezoid, trapezium, and transverse carpal ligament (TCL). From the two boundaries, the overall and regional soft tissue thicknesses and areas were calculated. The soft tissue thickness was significantly greater for the trapezoid (3.1±1.2mm) and trapezium (3.4±1.0mm) regions than for the hamate (0.7±0.3mm) and capitate (1.2±0.5mm) regions. The carpal tunnel area using the osseous boundary (243.0±40.4mm(2)) was significantly larger than the balloon-based area (183.9±29.7mm(2)) with a ratio of 1.32. In other words, the carpal tunnel area can be estimated as 76% (= 1/1.32) of the osseous-based area. The abundance of soft tissue in the trapezoid and trapezium regions can be attributed mainly to the capitate-trapezium ligament and the flexor carpi radialis tendon. Inclusion of such soft tissue leads to overestimations of the carpal tunnel area. Correct quantification of the carpal tunnel area aids in examining carpal

  16. Istanbul Bridge Conference 2014

    CERN Document Server

    Gülkan, Polat; Mahmoud, Khaled

    2016-01-01

      The book includes peer-reviewed contributions selected from presentations given at the Istanbul Bridge Conference 2014, held from August 11 – 13 in Istanbul, Turkey. It reports on the current challenges in bridge engineering faced by professionals around the globe, giving a special emphasis to recently developed techniques, innovations and opportunities. The book covers key topics in the field, including modeling and analysis methods; construction and erection techniques; design for extreme events and condition assessment and structural health monitoring. There is a balanced presentation of theory, research and practice. This book, which provides the readers with a comprehensive and timely reference guide on current practices in bridge engineering, is intended for professionals, academic researchers and students alike.

  17. Active Control of Suspension Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

  18. Dental devices; reclassification of root-form endosseous dental implants and endosseous dental implant abutments. Final rule.

    Science.gov (United States)

    2004-05-12

    The Food and Drug Administration (FDA) is reclassifying root-form endosseous dental implants and endosseous dental implant abutments from class III to class II (special controls). Root-form endosseous dental implants are intended to be surgically placed in the bone of the upper or lower jaw arches to provide support for prosthetic devices, such as artificial teeth, in order to restore the patient's chewing function. Endosseous dental implant abutments are separate components that are attached to the dental implant and intended to aid in prosthetic rehabilitation. FDA is reclassifying these devices on its own initiative on the basis of new information. Elsewhere in this issue of the Federal Register, FDA is announcing the availability of the guidance document that will serve as the special control for these devices. FDA is taking this action under the Federal Food, Drug, and Cosmetic Act (the act), as amended by the Medical Device Amendments of 1976 (the 1976 amendments), the Safe Medical Devices Act of 1990, the Food and Drug Administration Modernization Act of 1997, and the Medical Device User Fee and Modernization Act of 2002. PMID:15141676

  19. In vitro infrared thermography assessment of temperature peaks during the intra-oral welding of titanium abutments

    Science.gov (United States)

    Degidi, Marco; Nardi, Diego; Sighinolfi, Gianluca; Merla, Arcangelo; Piattelli, Adriano

    2012-07-01

    Control of heat dissipation and transmission to the peri-implant area during intra-oral welding is very important to limit potential damage to the surrounding tissue. The aim of this in vitro study was to assess, by means of thermal infrared imaging, the tissue temperature peaks associated with the thermal propagation pathway through the implants, the abutments and the walls of the slot of the scaffold, generated during the welding process, in three different implant systems. An in vitro polyurethane mandible model was prepared with a 7.0 mm v-shape slot. Effects on the maximum temperature by a single welding procedure were studied using different power supplies and abutments. A total of 36 welding procedures were tested on three different implant systems. The lowest peak temperature along the walls of the 7.0 mm v-shaped groove (31.6 ± 2 °C) was assessed in the specimens irrigated with sterile saline solution. The highest peak temperature (42.8 ± 2 °C) was assessed in the samples with a contemporaneous power overflow and premature pincers removal. The results of our study suggest that the procedures used until now appear to be effective to avoid thermal bone injuries. The peak tissue temperature of the in vitro model did not surpass the threshold limits above which tissue injury could occur.

  20. Level II scour analysis for Bridge 32 (TUNBTH00600032) on Town Highway 60, crossing First Branch White River, Tunbridge, Vermont

    Science.gov (United States)

    Wild, Emily C.

    1998-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure TUNBTH00600032 on Town Highway 60 crossing the First Branch White River, Tunbridge, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 92.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge, while woody vegetation sparsely covers the immediate banks. In the study area, the First Branch White River has a sinuous channel with a slope of approximately 0.001 ft/ft, an average channel top width of 82 ft and an average bank height of 7 ft. The channel bed material ranges from sand to gravel with a median grain size (D50) of 24.4 mm (0.08 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 18, 1995, indicated that the reach was laterally unstable, as a result of block failure of moderately eroded banks. The Town Highway 60 crossing of the First Branch White River is a 74-ft-long, one-lane bridge consisting of a 71-foot timber thru-truss span (Vermont Agency of Transportation, written communication, August 24, 1994). The opening length of the structure parallel to the bridge face is 64 ft.The bridge is supported by vertical, laid-up stone abutments with upstream wingwalls. The channel is not skewed to the opening

  1. Level II scour analysis for Bridge 34 (HUNTTH00210034) on Town Highway 21, crossing Brush Brook, Huntington, Vermont

    Science.gov (United States)

    Burns, Ronda L.; Ivanoff, Michael A.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00210034 on Town Highway 21 crossing Brush Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 6.23-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest. In the study area, Brush Brook has an incised, straight channel with a slope of approximately 0.03 ft/ft, an average channel top width of 43 ft and an average bank height of 4 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 90.0 mm (0.295 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 26, 1996, indicated that the reach was stable. The Town Highway 21 crossing of Brush Brook is a 28-ft-long, one-lane bridge consisting of one 26-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication November 30, 1995). The opening length of the structure parallel to the bridge face is 25.4 ft. The bridge is supported by vertical, concrete abutments with a wingwall on the upstream right. The channel is skewed approximately 5 degrees to the opening and the computed opening-skew-to-roadway is 5 degrees. A tributary enters Brush Brook on the right bank immediately downstream of the bridge. At the confluence, the

  2. Level II scour analysis for Bridge 24 (MANCUS00070024) on U.S. Route 7, crossing Lye Brook, Manchester, Vermont

    Science.gov (United States)

    Olson, Scott A.

    1997-01-01

    28, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 45 degrees to the opening while the opening-skew-to-roadway is 55 degrees. At the time of construction, the downstream channel was relocated (written communication, Dan Landry, VTAOT, January 2, 1997). A levee on the downstream right bank was also constructed and is protected by type-4 stone-fill (less than 60 inches diameter) extending from the bridge to more than 300 feet downstream. Type-2 stone fill (less than 36 inches diameter) covers the downstream right bank from the bridge to more than 300 feet downstream. Type-2 stone-fill also extends from the bridge to 220 feet upstream on both upstream banks. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is analyzed since it has the potential of being the worst-case scour scenario. Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 1.0 to 1.6 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour computations for the left abutment ranged from 14.5 to 16.1 ft. with the worst-case occurring at the 100-year discharge. Abutment scour computations for the right abutment ranged from 6.9 to 10.4 ft. with

  3. Quantum Bidding in Bridge

    Science.gov (United States)

    Muhammad, Sadiq; Tavakoli, Armin; Kurant, Maciej; Pawłowski, Marcin; Żukowski, Marek; Bourennane, Mohamed

    2014-04-01

    Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain an advantage in a famous, immensely popular, card game—bridge. The essence of a winning strategy in bridge is efficient communication between the partners. The rules of the game allow only a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits). Surprisingly, our quantum technique does not violate the existing rules of the game (as there is no increase in information flow). We show that our quantum bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt game, which is equivalent to a 2→1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.

  4. Bridge of Light

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Lying gleaming white under a brooding sky,the Lhasa River Railway Bridge forms a gate to Lhasa City.Built as a part of Qinghai-Tibet Railway,on July 1,2011, the highest altitude railway in the world has been in service for five years. Lhasa,Tibet

  5. Bridge over troubled water?

    DEFF Research Database (Denmark)

    Svendsen, Gunnar Lind Haase; Nannestad, Peter; Svendsen, Gert Tinggaard

    2008-01-01

    The problem of integrating non-Western immigrants into Western welfare states is the focus of this paper. To address this issue, we suggest a social capital approach in which we apply the conceptual pair of bridging social capital (BR), which connects an individual to the broader social structure...

  6. Building Bridges to China.

    Science.gov (United States)

    Wasta, Stephanie; Scott, Margaret

    1998-01-01

    Describes a theme cycle called "Building Bridges to China" developed for third grade students that focuses on the similarities between the lives of children and families in China and the United States. Explains that the theme cycle addresses the National Geography Standards and three of the National Council for the Social Studies standards. (CMK)

  7. Revised Rules for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.;

    This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

  8. Dynamic Bridge Response for a Bridge-friendly Truck

    Directory of Open Access Journals (Sweden)

    V. Šmilauer

    2004-01-01

    Full Text Available A truck with controlled semi-active suspensions traversing a bridge is examined for benefits to the bridge structure. The original concept of a road-friendly truck was extended to a bridge-friendly vehicle, using the same optimization tools. A half-car model with two independently driven axles is coupled with simply supported bridges (beam, slab model with the span range from 5 m to 50 m. Surface profile of the bridge deck is either stochastic or in the shape of a bump or a pot in the mid-span. Numerical integration in the MATLAB/SIMULINK environment solves coupled dynamic equations of motion with optimized truck suspensions. The rear axle generates the prevailing load and to a great extent determines the bridge response. A significant decrease in contact road-tire forces is observed and the mid-span bridge deflections are on average smaller, when compared to commercial passive suspensions. 

  9. Level II scour analysis for Bridge 44 (LINCTH00330044) on Town Highway 33, crossing the New Haven River, Lincoln, Vermont

    Science.gov (United States)

    Burns, Ronda L.; Wild, Emily C.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure LINCTH00330044 on Town Highway 33 crossing the New Haven River, Lincoln, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D.The site is in the Green Mountain section of the New England physiographic province in west-central Vermont. The 6.3-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest.In the study area, the New Haven River has an incised, sinuous channel with a slope of approximately 0.02 ft/ft, an average channel top width of 56 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 101.9 mm (0.334 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 10, 1996, indicated that the reach was stable.The Town Highway 33 crossing of the New Haven River is a 33-ft-long, one-lane bridge consisting of one 31-foot timber-beam span (Vermont Agency of Transportation, written communication, December 14, 1995). The opening length of the structure parallel to the bridge face is 29.3 ft. The bridge is supported by vertical, wood-beam crib abutments with wingwalls. The channel is skewed approximately 25 degrees to the opening while the opening-skew-to-roadway is zero degrees.A scour hole 1.0 ft deeper than the mean thalweg depth was observed along the right abutment during the Level I assessment. The

  10. Level II scour analysis for Bridge 31 (HUNTTH00220031) on Town Highway 22, crossing Brush Brook, Huntington, Vermont

    Science.gov (United States)

    Flynn, Robert H.; Degnan, James R.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00220031 on Town Highway 22 crossing Brush Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, obtained from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in west-central Vermont. The 5.01-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover consists of trees and brush. In the study area, Brush Brook has an incised, straight channel with a slope of approximately 0.06 ft/ft, an average channel top width of 44 ft and an average bank height of 4 ft. The channel bed material ranges from boulder to gravel with a median grain size (D50) of 107.0 mm (0.352 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 25, 1996, indicated that the reach was stable. The Town Highway 22 crossing of Brush Brook is a 34-ft-long, one-lane bridge consisting of one 30-foot steel I-beam span (Vermont Agency of Transportation, written communication, November 30, 1995). The opening length of the structure parallel to the bridge face is 31.2 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 15 degrees to the opening while the computed opening-skew-to-roadway is 10 degrees. The VTAOT computed opening-skewto-roadway is 2 degrees. A scour hole 1.0 ft deeper than the mean thalweg depth was

  11. Stock Versus CAD/CAM Customized Zirconia Implant Abutments - Clinical and Patient-Based Outcomes in a Randomized Controlled Clinical Trial

    NARCIS (Netherlands)

    Schepke, Ulf; Meijer, Henny J A; Kerdijk, Wouter; Raghoebar, Gerry M; Cune, Marco

    2016-01-01

    BACKGROUND: Single-tooth replacement often requires a prefabricated dental implant and a customized crown. The benefits of individualization of the abutment remain unclear. PURPOSE: This randomized controlled clinical trial aims to study potential benefits of individualization of zirconia implant ab

  12. Performance-based seismic assessment of skewed bridges with and without considering soil-foundation interaction effects for various site classes

    Science.gov (United States)

    Ghotbi, Abdoul R.

    2014-09-01

    The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation, shear keys failure, abutment unseating and column-bent drift. This research, therefore, aims to study the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Due to several sources of uncertainty associated with the ground motions, soil and structure, a probabilistic approach is needed. Thus, a probabilistic methodology similar to the one developed by the Pacific Earthquake Engineering Research Center (PEER) has been utilized to assess the probability of damage due to various levels of shaking using appropriate intensity measures with minimum dispersions. The probabilistic analyses were performed for various bridge configurations and site conditions, including sand ranging from loose to dense and clay ranging from soft to stiff, in order to evaluate the effects. The results proved a considerable susceptibility of skewed bridges to deck rotation and shear keys displacement. It was also found that SSI had a decreasing effect on the damage probability for various demands compared to the fixed-base model without including SSI. However, deck rotation for all types of the soil and also abutment unseating for very loose sand and soft clay showed an increase in damage probability compared to the fixed-base model. The damage probability for various demands has also been found to decrease with an increase of soil strength for both sandy and clayey sites. With respect to the variations in the skew angle, an increase in skew angle has had an increasing effect on the amplitude of the seismic response for various demands. Deck rotation has been very sensitive to the increase in the skew angle; therefore, as the skew angle increased, the deck rotation responded accordingly

  13. History, observation and mathematical models in the seismic analysis of the Valadier abutment area in the Colosseum

    Directory of Open Access Journals (Sweden)

    D. D'Ayala

    1995-06-01

    Full Text Available The present work aimed to outline the need to investigate different fields of research to interpret the structural behaviour of a monument as complex as the Colosseum. It is shown how defining the numerical models first. then refining them, followed by interpretation of results. is strictly linked with the inforination gathered from historical records and observation of the ~nonumenta s it is today. The study is confined to the area of the Valadier abutment. analysing its state and its seismic behaviour before and after the XIX century restoration using different ilumerical tools, from the elastic modal analysis to the non linear step by step time history direct integration. The procedure comparatiely evaluates the reliability in the interpretation of the results and identifies future lines or research.

  14. [Retention of adhesive bridges].

    Science.gov (United States)

    Raes, F; De Boever, J

    1994-04-01

    Since the development of adhesive bridges in the early seventies, the retention and therefore the durability of these bridges has been tremendously improved. Conditioning of the non-precious metal by silanisation, careful acid etching of the enamel and the use of the appropriate composite resin are of prime importance. Furthermore, the meticulous preparation with enough interproximal embrace, occlusal rests, interocclusal clearance and cingulum stops is equally important. Including more teeth in the design does not necessarily lead to an improved retention. Besides the material and technical aspects, the whole clinical procedure needs much attention. The retention does not depend on one single factor, but on the precision of all the necessary clinical steps and on a well-defined selection of the material. In this way a five-year survival rate of close to 80% can be obtained. PMID:11830965

  15. Free-end saddle length influence on stress level in unilateral complex partial denture abutment teeth and retention elements

    Directory of Open Access Journals (Sweden)

    Patrnogić Vesna

    2013-01-01

    Full Text Available Background/Aim. Different types of dental restorations are used for the therapy of unilateral free-end saddle edentulism. Unilateral complex partial denture is one of the indications for the Kennedy class II partial edentulism. The abscence of major connector and denture plate is an advantage compared to the conventional restorations, because of better comfort and shorter period of adaptation. The aim of the study was to analyse the influence of free-end saddle length change on the behaviour of unilateral complex partial denture supporting structures. Methods. Stress levels of the canine and the first premolar as retentional teeth and the attachments were tested under the influence of physiological forces with the loading point shifting distally in relation to the saddle length change. A virtual real size 3D model of the fixed part of the restoration (the canine and the first premolar with milled crowns was created using the CATIA computer program. It was connected to the mobile part of partial denture with the SD snap in latch attachment. Mobile part of the restoration was designed in the region of 2, 3 and 4 lateral teeth (second premolar, first, second and third molar. By using the finite element method (FEM stress levels analysis was performed under the load of physiological forces of 150 N in the free-end saddle teeth zone. Results. The results of analysis show that physiological forces cause a different stress distribution on the abutment teeth and the attachment, depending on the saddle length. Conclusion. The stress level values obtained for the abutment teeth as well as the attachment are far lower than the marginal ones. The behaviour of the system changes under this defined stress, but no plastic deformation occurs.

  16. BRIDGING SERVICE QUALITY GAPS

    OpenAIRE

    BARKATH UNISSA

    2012-01-01

    Bridging the Service quality gaps is one of the foremost areas of concern for amarketer. Service marketing is inherently different from product or goods marketing.Services are distinctively characterized by their intangible, heterogeneous, inseparableand perishable nature. The importance of the service sector in today's world is a verywidely accepted and renowned idea. “We are already experiencing a service society“services do have some basic characteristics which make them fundamentally diff...

  17. Bridging as Coercive Accommodation

    CERN Document Server

    Bos, J W; Mineur, A M; Bos, Johan; Buitelaar, Paul; Mineur, Anne-Marie

    1995-01-01

    In this paper we discuss the notion of "bridging" in Discourse Representation Theory as a tool to account for discourse referents that have only been established implicitly, through the lexical semantics of other referents. In doing so, we use ideas from Generative Lexicon theory, to introduce antecedents for anaphoric expressions that cannot be "linked" to a proper antecedent, but that do not need to be "accommodated" because they have some connection to the network of discourse referents that is already established.

  18. Nematic liquid crystal bridges

    Science.gov (United States)

    Doss, Susannah; Ellis, Perry; Vallamkondu, Jayalakshmi; Danemiller, Edward; Vernon, Mark; Fernandez-Nieves, Alberto

    We study the effects of confining a nematic liquid crystal between two parallel glass plates with homeotropic boundary conditions for the director at all bounding surfaces. We find that the free surface of the nematic bridge is a surface of constant mean curvature. In addition, by changing the distance between the plates and the contact angle with the glass plates, we transition between loops and hedgehogs that can be either radial or hyperbolic.

  19. Clinical Outcome of Inter-Proximal Papilla between a Tooth and a Single Implant Treated with CAD/CAM Abutments: a Cross-Sectional Study

    Directory of Open Access Journals (Sweden)

    Tiago Borges

    2012-09-01

    Full Text Available Objectives: The aim of this study was to assess the clinical outcomes achieved with Computer-Assisted Design/Computer-Assisted Manufacturing implant abutments in the anterior maxilla.Material and Methods: Nineteen patients with a mean age of 41 (range form 26 to 63 years, treated with 21 single tooth implants and 21 Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM abutments in the anterior maxillary region were included in this study. The patients followed 4 criteria of inclusion: (1 had a single-tooth implant in the anterior maxilla, (2 had a CAD/CAM abutment, (3 had a contralateral natural tooth, (4 the implant was restored and in function for at least 6 months up to 2 years. Cases without contact point were excluded. Presence/absence of the interproximal papilla, inter tooth-implant distance (ITD and distance from the base of the contact point to dental crest bone of adjacent tooth (CPB were accessed. Results: Forty interproximal spaces were evaluated, with an average mesial CPB of 5.65 (SD 1.65 mm and distal CPB of 4.65 (SD 1.98 mm. An average mesial ITD of 2.49 (SD 0.69 mm and an average distal ITD of 1.89 (SD 0.63 mm were achieved. Papilla was present in all the interproximal spaces accessed. Conclusions: The restoration of dental implants using CAD/CAM abutments is a predictable treatment with improved aesthetic results. These type of abutments seem to help maintaining a regular papillary filling although the variations of the implant positioning or the restoration teeth relation.

  20. Clinical Outcome of Inter-Proximal Papilla between a Tooth and a Single Implant Treated with CAD/CAM Abutments: a Cross-Sectional Study

    Science.gov (United States)

    Lima, Tiago; Carvalho, Ágata; Carvalho, Vasco

    2012-01-01

    ABSTRACT Objectives The aim of this study was to assess the clinical outcomes achieved with Computer-Assisted Design/Computer-Assisted Manufacturing implant abutments in the anterior maxilla. Material and Methods Nineteen patients with a mean age of 41 (range form 26 to 63) years, treated with 21 single tooth implants and 21 Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM) abutments in the anterior maxillary region were included in this study. The patients followed 4 criteria of inclusion: (1) had a single-tooth implant in the anterior maxilla, (2) had a CAD/CAM abutment, (3) had a contralateral natural tooth, (4) the implant was restored and in function for at least 6 months up to 2 years. Cases without contact point were excluded. Presence/absence of the interproximal papilla, inter tooth-implant distance (ITD) and distance from the base of the contact point to dental crest bone of adjacent tooth (CPB) were accessed. Results Forty interproximal spaces were evaluated, with an average mesial CPB of 5.65 (SD 1.65) mm and distal CPB of 4.65 (SD 1.98) mm. An average mesial ITD of 2.49 (SD 0.69) mm and an average distal ITD of 1.89 (SD 0.63) mm were achieved. Papilla was present in all the interproximal spaces accessed. Conclusions The restoration of dental implants using CAD/CAM abutments is a predictable treatment with improved aesthetic results. These type of abutments seem to help maintaining a regular papillary filling although the variations of the implant positioning or the restoration teeth relation. PMID:24422016

  1. GFRP seismic strengthening and structural heath monitoring of Portage Creek Bridge concrete columns

    International Nuclear Information System (INIS)

    Located in Victoria British Columbia (BC), Canada, the Portage Creek Bridge is a 124m long, three-span structure with a reinforced concrete piers and abutments on H piles. The bridge was designed prior to the introduction of current bridge seismic design codes and construction practices. Therefore it was not designed to resist the earthquake forces as required by today's standards. The bridge is on a route classified as a Municipal Disaster Route scheduled to be retrofitted to prevent collapse during a design seismic event, with a return period of 475 years (i.e., an event with 105 probability of exceedance in 50 years). Conventional materials and methods were used to retrofit most of the bridge. The dynamic analysis of the bridge predicted the two tall columns of Pier No. 1 will form plastic hinges under an earthquake resulting an additional shear to the short columns of Pier No. 2. A non-liner static pushover analysis indicated the short columns will not be able to form plastic hinges prior to failure in shear. The innovative solution of Fiber Reinforced Polymer wraps (FRPs) was chosen to strengthen the short columns for shear without increasing the moment capacity. The FRP wraps and the bridge were instrumented as one of 36 demonstration projects across Canada sponsored by ISIS (Intelligent Sensing for Innovative Structure) Canada, federally funded Network of Centers of Excellence, to access the performance of FRP and the use of FOS (Fiber Optic Sensors) for Structural Health Monitoring (SHM). The two columns of the bridge pier were strengthened with GFRP (Glass Fiber Reinforced Polymer) wraps with eight bi-directional rosette type strain gauges and four long gauge fiber optic sensors attached to the outer layer of the wraps. In addition, two 3-D Crossbow accelerometers are installed on the pier cap above the columns and a traffic web-cam mounted above the deck at the pier location. The data is collected through high sped internet line to an interactive web page

  2. Assessing potential scour using the South Carolina bridge-scour envelope curves

    Science.gov (United States)

    Benedict, Stephen T.; Feaster, Toby D.; Caldwell, Andral

    2016-09-30

    SummaryBridge-scour equations presented in the Federal Highway Administration Hydraulic Engineering Circular No. 18 reflect the current state-of-the practice for predicting scour at bridges. Although these laboratory-derived equations provide an important resource for assessing scour potential, there is a measure of uncertainty when applying these equations to field conditions. The uncertainty and limitations have been acknowledged by laboratory researchers and confirmed in field investigations.Because of the uncertainty associated with bridge-scour equations, HEC-18 recommends that engineers evaluate the computed scour depths obtained from the equations and modify the resulting data if they appear unreasonable. Perhaps the best way to evaluate the reasonableness of predicted scour is to compare it to field measurements of historic scour. Historic field data show scour depths resulting from high flows and provide a reference for evaluating predicted scour. It is rare, however, that such data are available at or near a site of interest, making the evaluation of predicted scour as compared to field data difficult if not impossible. Realizing the value of historic scour measurements, the U.S. Geological Survey (USGS), in cooperation with the South Carolina Department of Transportation (SCDOT), conducted a series of three field investigations to collect historic scour data with the goal of understanding regional trends of scour at riverine bridges in South Carolina.Historic scour measurements, including measurements of clear-water abutment, contraction, and pier scour, as well as live-bed contraction and pier scour, were made at more than 200 bridges. These field investigations provided valuable insights into regional scour trends and yielded regional bridge-scour envelope curves that can be used as supplementary tools for assessing all components of scour at riverine bridges in South Carolina.The application and limitations of these envelope curves were documented in

  3. Environmental life cycle assessment comparison between two bridge types: reinforced concrete bridge and steel composite bridge

    DEFF Research Database (Denmark)

    Du, Guangli; Karoumi, Raid

    2013-01-01

    not been integrated into the decision-making process. This paper presents a systematic LCA method for quantifying the environmental impacts for bridges. The comparison study is performed between a reinforced concrete bridge and a steel bridge as an alternative design, with several key maintenance and EOL......The concept of sustainable construction has attracted an increased attention. Bridge infrastructures and their belonged construction activities consume considerable material and energy, which is responsible for large environmental burdens. However, the environmental assessment of bridges has...

  4. Level II scour analysis for Bridge 33 (TUNBTH00450033) on Town Highway 45, crossing the First Branch White River, Tunbridge, Vermont

    Science.gov (United States)

    Wild, E.C.; Severance, Timothy

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure TUNBTH00450033 on Town Highway 45 crossing the First Branch White River, Tunbridge, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 86.4-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge, while woody vegetation sparsely covers the immediate banks. In the study area, the First Branch White River has an incised, sinuous channel with a slope of approximately 0.003 ft/ft, an average channel top width of 68 ft and an average bank height of 7 ft. The channel bed material ranges from sand to gravel with a median grain size (D50) of 27.1 mm (0.089 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 18, 1995, indicated that the reach was laterally unstable due to a cut-bank present on the upstream right bank and a wide channel bar in the upstream reach. The Town Highway 45 crossing of the First Branch White River is a 67-ft-long, one-lane bridge consisting of one 54-foot timber thru-truss span (Vermont Agency of Transportation, written communication, March 23, 1995). The opening length of the structure parallel to the bridge face is 53.5 ft. The bridge is supported on the right by a vertical, concrete abutment

  5. Vulnerability of bridges to fire

    DEFF Research Database (Denmark)

    Giuliani, Luisa; Crosti, C.; Gentili, F.

    2012-01-01

    Even if recent effort in developing methodology and measures for design structures against fire and explosions has been mostly focused on buildings, bridges can also be very sensitive to those actions, as witnesses by some recent bridge accidents, which caused major economic losses and also...... endangered people safety in few cases. Purpose of this paper is making a focus on the state of the art of the research and current regulations concerning the response of bridges to fire. Several cases of bridge fires are reported and a focus is made on the occurrence and consequence of bridge fires......, considering both the costs deriving by structural damages and by limited serviceability and other indirect societal aspects. Few cases of recent bridge fire are reviewed in detail and structural consequences are highlighted, distinguishing between damages directly induced by fire and damages induced by local...

  6. Theory of bridge aerodynamics

    CERN Document Server

    Strømmen, Einar

    2006-01-01

    This text book is intended for studies in wind engineering, with focus on the stochastic theory of wind induced dynamic response calculations for slender bridges or other line ?like civil engineering type of structures. It contains the background assumptions and hypothesis as well as the development of the computational theory that is necessary for the prediction of wind induced fluctuating displacements and cross sectional forces. The simple cases of static and quasi-static structural response calculations are for the sake of completeness also included. The text is at an advanced level in the

  7. Modelling railway bridge asset management

    OpenAIRE

    Le, Bryant Linh Hai

    2014-01-01

    The UK has a long history in the railway industry with a large number of railway assets. Railway bridges form one of the major asset groups with more than 35,000 bridges. The majority of the bridge population are old being constructed over 100 years ago. Many of the bridges were not designed to meet the current network demand. With an expected increasing rate of deterioration due to the increasing traffic loads and intensities, the management authorities are faced with the difficult task of k...

  8. Level II scour analysis for Bridge 23 (GLOVTH00410023) on Town Highway 41, crossing Sherburne Brook, Glover, Vermont

    Science.gov (United States)

    Olson, Scott A.; Boehmler, Erick M.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure GLOVTH00410023 on Town Highway 41 crossing Sherburne Brook, Glover, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in northern Vermont. The 2.57-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is primarily forest with small areas of lawn and a home on the right overbank and a gravel roadway along the upstream left bank. In the study area, Sherburne Brook has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 33 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 57.3 mm (0.188 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 24, 1994, indicated that the reach was stable. The Town Highway 41 crossing of Sherburne Brook is a 24-ft-long, one-lane bridge consisting of one 21-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, August 4, 1994). The opening length of the structure parallel to the bridge face is 20.3 ft. The bridge is supported by vertical, granite block abutments. The channel is skewed approximately 55 degrees to the opening while the measured opening-skew-to-roadway is 30 degrees. One foot

  9. Level II scour analysis for Bridge 7H (HUNTTH0001007H) on Town Highway 1, crossing Cobb Brook, Huntington, Vermont

    Science.gov (United States)

    Wild, Emily C.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH001007H on Town Highway 1 crossing the Cobb Brook, Huntington, Vermont (figures 1–10). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D.In August 1976, Hurricane Belle caused flooding at this site which resulted in road and bridge damage (figures 7-8). This was approximately a 25-year flood event (U.S. Department of Housing and Urban Development, 1978). The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 4.20-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest upstream of the bridge. Downstream of the bridge is brushland and pasture.In the study area, the Cobb Brook has an incised, straight channel with a slope of approximately 0.03 ft/ft, an average channel top width of 43 ft and an average bank height of 6 ft. The channel bed material ranges from sand to boulders with a median grain size (D50) of 65.5 mm (0.215 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 24, 1996, indicated that the reach was stable. The Town Highway 1 crossing of the Cobb Brook is a 23-ft-long, two-lane bridge consisting of one 20-foot concrete slab span (Vermont Agency of Transportation, written communication, June 21, 1996). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 15 degrees

  10. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2005-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  11. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2004-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  12. Development of cooperative system bridges

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhe; WAN Qi-bai; SHI Lei

    2008-01-01

    Cooperative system bridges comprise several basic structures that act jointly to improve structural characteristics. We delved into the historical development of cooperative system bridges. Cooperative systems are classified as different-load cooperative systems and same-load cooperative systems by distinguishing the modes of load distribution. For different-load cooperation, individual basic structures are at different positions in the direction along bridge axis and carry the loads separately. While for same-load cooperation, all basic structures overlap in geometrical locations and support the entire loads conjointly. The choosing of span ratios between basic structures, the design of connections of different-load cooperative systems were discussed as well as optimizations of relative rigidity for same-load cooperative systems which greatly influence structural characteristics. The general situation and several structural measurements of several cooperative bridges were demonstrated. This information can assist engineers in developing their concepts in cooperative systems and can lead to more efficient and economical cooperative bridges.

  13. Safety evaluation of replacement reinforcement quality in abutment contact zones of ultra-high arch dam in first impoundment period based on prototype monitoring

    Directory of Open Access Journals (Sweden)

    Bo HU

    2012-06-01

    Full Text Available Reinforcement quality evaluation at the abutment is an important research direction. Prototype monitoring and theoretical derivation were integrated to study the replacement reinforcement quality in abutment contact zones of the Xiaowan ultra-high arch dam. The principles of monitoring layout and design are introduced in detail. Prototype monitoring shows that the increment of the interfacial compressive stress is much larger in the impoundment stage than in the regulating stage. The water pressure and time-effect are two main factors affecting the interfacial stress. The time-effect is the key factor in the initial impoundment stage, and the water pressure is the key factor after impoundment. The contact properties are significantly improved by grouting. This study shows that there are three typical stages in the joint opening hydrographs, namely the compression stage, opening stage, and stable stage. There is a nonlinear relationship between the joint opening and temperature, which can be well described by the S-function. In conclusion, the reinforcement effect is satisfying, and the abutment is safe.

  14. Improving the long-term stability of Ti6Al4V abutment screw by coating micro/nano-crystalline diamond films.

    Science.gov (United States)

    Xie, Youneng; Zhou, Jing; Wei, Qiuping; Yu, Z M; Luo, Hao; Zhou, Bo; Tang, Z G

    2016-10-01

    Abutment screw loosening is the most common complication of implanting teeth. Aimed at improving the long-term stability of them, well-adherent and homogeneous micro-crystalline diamond (MCD) and nano-crystalline diamond (NCD) were deposited on DIO(®) (Dong Seo, Korea) abutment screws using a hot filament chemical vapor deposition (HFCVD) system. Compared with bare DIO(®) screws, diamond coated ones showed higher post reverse toque values than the bare ones (pcoated disks showed lower friction coefficients of 0.15 and 0.18 in artificial saliva when countered with ZrO2 than that of bare Ti6Al4V disks of 0.40. Though higher cell apoptosis rate was observed on film coated disks, but no significant difference between MCD group and NCD group. And the cytotoxicity of diamond films was acceptable for the fact that the cell viability of them was still higher than 70% after cultured for 72h. It can be inferred that coating diamond films might be a promising modification method for Ti6Al4V abutment screws. PMID:27393893

  15. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region

    Directory of Open Access Journals (Sweden)

    Guerino Paolantoni

    2016-01-01

    Full Text Available The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces; in 45 cases the restoration was a screw-retained restoration (one piece. Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results.

  16. Cascaded resonant bridge converters

    Science.gov (United States)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  17. The behavior of implant-supported dentures and abutments using the cemented cylinder technique with different resinous cements

    Directory of Open Access Journals (Sweden)

    Ivete Aparecida de Mathias Sartori

    2008-01-01

    Full Text Available Objective: Evaluate the behavior of implant-supported dentures and their components, made by cemented cylinder technique, using threetypes of resin cements. Methods: Fifty three patients, of whom 26 were women and 27 men, aged between 25 and 82 years. Results: With partial (54.43% and total (45.57% implant-supported dentures, of the Cone Morse, external and internal hexagon types (Neodent®, Curitiba, Brazil, totaling 237 fixations, were analyzed. The resin cements used were Panavia® (21.94%, EnForce® (58.23% and Rely X® (19.83% and the components were used in accordance with the Laboratory Immediate Loading - Neodent® sequence. The period of time of denture use ranged between 1 and 5 years. The results reported that 5(2.1% cylinders were loosened from metal structure (both belonging to Rely X group, 2(0.48% implants were lost after the first year of use, 16(6.75% denture retention screws wereloosened and 31(13.08% abutment screws were unloosened.Conclusion: The reasons for these failures probably are: metal structure internal retention failure, occlusal pattern, cementation technique and loading conditions. The cemented cylinder technique was effective when used in partial and total implant-supported rehabilitations, keeping prosthetic components stable, despite the resin cement utilized. However, further clinical studies must be conducted.

  18. Level II scour analysis for Bridge 68 (NFIETH00960068) on Town Highway 96, crossing the Dog River, Northfield, Vermont

    Science.gov (United States)

    Burns, Ronda L.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure NFIETH00960068 on Town Highway 96 crossing the Dog River, Northfield, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 30.7-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover on the left bank upstream and downstream is pasture while the immediate banks have dense woody vegetation. The right bank upstream is forested and the downstream right bank is pasture. Vermont state route 12A runs parallel to the river on the right bank. In the study area, the Dog River has an incised, straight channel with a slope of approximately 0.004 ft/ft, an average channel top width of 70 ft and an average bank height of 7 ft. The channel bed material ranges from sand to cobble with a median grain size (D50) of 47.9 mm (0.157 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 25, 1996, indicated that the reach was stable. The Town Highway 96 crossing of the Dog River is a 45-ft-long, one-lane bridge consisting of one 43-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, October 13, 1995). The opening length of the structure parallel to the bridge face is 41.5 ft.The bridge is supported by vertical, concrete abutments with wingwalls. The

  19. Numerical Modeling of the Lake Mary Road Bridge for Foundation Reuse Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States); Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States); Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-04-01

    This project uses numerical techniques to assess the structural integrity and capacity of the bridge foundations and, as a result, reduces the risk associated with reusing the same foundation for a new superstructure. Nondestructive test methods of different types were used in combination with the numerical modeling and analysis. The onsite tests included visual inspection, tomography, ground penetrating radar, drilling boreholes and coreholes, and the laboratory tests on recovered samples. The results were utilized to identify the current geometry of the structure with foundation, including the hidden geometry of the abutments and piers, and soil and foundation material properties. This data was used to build the numerical models and run computational analyses on a high performance computer cluster to assess the structural integrity of the bridge and foundations including the suitability of the foundation for reuse with a new superstructure and traffic that will increase the load on the foundations. Computational analysis is more cost-effective and gives an advantage of getting more detailed knowledge about the structural response. It also enables to go beyond non-destructive testing and find the failure conditions without destroying the structure under consideration.

  20. Liquid-Bridge Breaking Limits

    Science.gov (United States)

    Macner, Ashley; Steen, Paul

    2011-11-01

    Wet adhesion by liquid bridges in large arrays shows promise for use in lightweight, controllable on-demand devices. Applications include grab/release of wafer substrates, transport of micron-sized tiles for use in 3D printing and micro-dosing of personalized pharmaceutical drugs. By wetting and spreading, a drop can form a bridge and thereby ``grab'' a nearby solid substrate. By volume decrease or extension, the bridge can break. The breaking limit corresponds to bridge instability which can be predicted, knowing the static mechanical response of the bridge. Mechanical behaviors include force-volume (FV), pressure-volume (pV) and force-length (FL) responses. Instability crucially depends on the mode of failure - failure under constant-force or constant length are typical cases. We study single bridge equilibria for their breaking limits. FV diagrams for the pin-pin equal and pin-pin unequal radii boundary conditions for different bridge heights are measured in the laboratory. The FL response in the case of pin-pin equal radii is also measured. Results are compared to predictions of static theory. Static results are then used to compare to dynamical sequences where volume is driven quasistatically by syringe or an electro-osmotic pump. As the breaking limit is approached, the shape deformation accelerates leading to non-equilibrium shapes not captured by the static analysis.

  1. Bridge Creek IMW database - Bridge Creek Restoration and Monitoring Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The incised and degraded habitat of Bridge Creek is thought to be limiting a population of ESA-listed steelhead (Oncorhynchus mykiss). A logical restoration...

  2. National Bridge Inventory - National Geospatial Data Asset (NGDA) Bridges

    Data.gov (United States)

    Department of Transportation — The NBI (NTAD 2015) is a collection of information (database) describing the more than 610,000 of the Nation's bridges located on public roads, including Interstate...

  3. Complex Testing of the Bridges

    Directory of Open Access Journals (Sweden)

    Savić Adrijana

    2016-01-01

    Full Text Available This article describes the process of examining bridges. AB road bridge, founded on the columns by the Karpoš system and damaged due to erosive action of the river, is given as an example. The first tests of the bridge are conducted on the impact load of V 300, because of the appearance of longitudinal cracks. The results of the columns testing are presented in this paper, as well as the rehabilitation measures thus increasing the load capacity of the column.

  4. General design of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Xigang; Yuan Hong; Pei Minshan; Dai Jie; Xu Lin

    2009-01-01

    The main span of Sutong Bridge is a double-pylon, double-plane cable-stayed bridge with steel box girder, which has the world's longest central span of 1 088 m within cable-stayed bridges. To overcome problems caused by severe meteorological conditions, perplexing hydrological conditions, deep buried bedrock and higher navigation level, many new technics and methods were created. Keys including structural system, steel box girder, stayed cable, tower, pier, tower foundation, collision avoidance system, wind-resistance, seismic-resistance, structural nonlinear response and structural static stability were presented individually in this paper.

  5. Thermal bridges of modern windows

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan de Place; Møller, Eva B.; Nielsen, Anker;

    2013-01-01

    With its focus on reduced energy consumption, contemporary housing construction requires a highly insulated and airtight building envelope with as few thermal bridges as possible.Windows must be carefully designed, as thermal bridges can lead to surface condensation or mold growth, even...... if the window has an U-factor of 1 W/(m2·K) or lower. This paper describes the development of modern, energy efficient Danish windows with reduced thermal bridges. It focuses on materials, geometry, and sealing of window panes based on a literature review. Examples of modern windows are presented. Experience...

  6. Reliability Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Middleton, C. R.

    This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the details of a methodology which can be used to generate Whole Life (WL) reliability...... profiles. These WL reliability profiles may be used to establish revised rules for concrete bridges. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

  7. 路桥过渡段路堤加筋现场试验和数值模拟分析%Experimental and numerical simulation analysis on geosynthetic reinforced embankment at bridge approaches

    Institute of Scientific and Technical Information of China (English)

    张军; 郑俊杰; 马强; 董友扣

    2011-01-01

    采用土工格栅加筋处理路堤填土可有效解决路堤填土压缩变形过大的问题,从而减小路桥过渡段桥台与路堤的差异沉降以及缓解桥头跳车的现象.通过现场试验对加筋路堤中格栅上、下表面土压力与格栅变形进行了监测分析.采用有限元方法对比分析路堤在加筋与未加筋2种工况下路桥过渡段路堤变形的差异.结果表明:路堤加筋技术在桥台附近减载作用明显,随着距桥台距离的增加,减载作用逐渐减弱;路堤加筋技术有效减小了桥台与路堤的差异沉降.最后,对桩体弹性模量、桩径、筋材抗拉刚度、路堤填土黏聚力和路堤填土内摩擦角进行了参数分析.%Geosynthetic can be used to reinforce the embankment fill so that it can solve problems of excessive compression effectively, thus reduce differential settlements between bridge abutment and embankment and alleviate bump at the approach of the bridge. The stress and deformation of the soil above and below the geosynthetic were measured through the field test. In addition, the differential settlements at the bridge approach under two conditions (embankment with and without geosynthetic reinforcement) were analyzed by finite element method. The results show that load-reduction of the reinforced embankment technique is significant at the vicinity of bridge abutment, while the effect moderates with the distance from the bridge abutment; and the reinforced embankment technique can relieve the differential settlement at the bridge approach effectively. Finally, parametric studies on elastic modulus and diameter of pile, tensile stiffness of geosynthetic, cohesion and friction angle of embankment fill were carried out.

  8. Level II scour analysis for Bridge 28 (ROCHTH00370028) on Town Highway 37, crossing Brandon Brook, Rochester, Vermont

    Science.gov (United States)

    Wild, Emily C.; Weber, Matthew A.

    1998-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure ROCHTH00370028 on Town Highway 37 crossing Brandon Brook, Rochester, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (FHWA, 1993). Results of a Level I scour investigation also are included in appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from VTAOT files, was compiled prior to conducting Level I and Level II analyses and is found in appendix D. The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 8.0-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture on the upstream left overbank although the immediate banks have dense woody vegetation. The upstream right overbank and downstream left and right overbanks are forested. In the study area, the Brandon Brook has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 44 ft and an average bank height of 7 ft. The channel bed material ranges from gravel to cobbles with a median grain size (D50) of 84.2 mm (0.276 ft). The geomorphic assessment at the time of the Level I site visit on April 12, 1995 and Level II site visit on July 8, 1996, indicated that the reach was stable. The Town Highway 37 crossing of the Brandon Brook is a 33-ft-long, one-lane bridge consisting of a 31-foot timber-stringer span (Vermont Agency of Transportation, written communication, March 22, 1995). The opening length of the structure parallel to the bridge face is 29.6 ft. The bridge is supported by vertical, timber log cribbing abutments with wingwalls. The channel is skewed approximately 5 degrees to the opening while the computed opening-skew-to-roadway is zero

  9. Level II scour analysis for Bridge 32 (HUNTTH00220032) on Town Highway 22, crossing Brush Brook, Huntington, Vermont

    Science.gov (United States)

    Burns, Ronda L.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00220032 on Town Highway 22 crossing Brush Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 5.7-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest except on the downstream right overbank which is pasture. In the study area, Brush Brook has an incised, straight channel with a slope of approximately 0.05 ft/ft, an average channel top width of 58 ft and an average bank height of 6 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 127 mm (0.416 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 25, 1996, indicated that the reach was stable. The Town Highway 22 crossing of Brush Brook is a 36-ft-long, one-lane bridge consisting of one 34-foot steel-beam span and a timber deck (Vermont Agency of Transportation, written communication, December 12, 1995). The opening length of the structure parallel to the bridge face is 35.7 ft. The bridge is supported by vertical, concrete abutments with wingwalls on the left. The channel is skewed approximately 50 degrees to the opening while the measured opening-skew-to-roadway is 15 degrees. A scour hole 1.0 ft deeper than the mean thalweg depth was

  10. The Higgs Bridge

    CERN Document Server

    Allen, Roland E

    2013-01-01

    The particle recently discovered at the Large Hadron Collider near Geneva is almost certainly a Higgs boson, the long-sought completion of the Standard Model of particle physics. But this discovery, an achievement by more than six thousand scientists (including students), is actually much more than a mere capstone of the Standard Model. It instead represents a bridge from the Standard Model to exciting discoveries of the future, at higher energies or in other experiments, and to the properties of matter at very low temperatures. The mere existence of a particle with zero spin implies a need for new physics, with the most likely candidate being supersymmetry, which requires that every known particle has a superpartner yet to be discovered. And phenomena similar to the Higgs are seen in superconducting metals and superfluid gases at low temperatures, which extend down to a millionth or even a billionth of a degree Kelvin. So the discovery of a Higgs boson has a central place in our attempts both to achieve a tr...

  11. Mineral bridges in nacre revisited

    CERN Document Server

    Checa, Antonio G; Willinger, Marc-Georg

    2012-01-01

    We confirm with high-resolution techniques the existence of mineral bridges between superposed nacre tablets. In the towered nacre of both gastropods and the cephalopod Nautilus there are large bridges aligned along the tower axes, corresponding to gaps (150-200 nm) in the interlamellar membranes. Gaps are produced by the interaction of the nascent tablets with a surface membrane that covers the nacre compartment. In the terraced nacre of bivalves bridges associated with elongated gaps in the interlamellar membrane (> 100 nm) have mainly been found at or close to the edges of superposed parental tablets. To explain this placement, we hypothesize that the interlamellar membrane breaks due to differences in osmotic pressure across it when the interlamellar space below becomes reduced at an advanced stage of calcification. In no cases are the minor connections between superimposed tablets (< 60 nm), earlier reported to be mineral bridges, found to be such.

  12. Simulation of multivariate diffusion bridges

    DEFF Research Database (Denmark)

    Bladt, Mogens; Finch, Samuel; Sørensen, Michael

    We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental role in simulation-based likelihood and Bayesian inference for stochastic differential equations. By a novel application of classical coupling methods, the new approach generalizes a previously...

  13. Applications of overburden conveyor bridges

    Energy Technology Data Exchange (ETDEWEB)

    Schachtschneider, H.

    1987-06-01

    In large scale surface mines of the capacities required today, a cross-pit operation with overburden conveyor bridges is the most economical method of overburden removal and disposal. In order to provide the production capacity required in surface mining equipment by the GDR brown coal industry, VEB Schwermaschinenbau Lauchhammerwerk undertook the design and manufacture of standard overburden conveyor bridges for cut heights of 34 m, 45 m and 60 m. All three base types may be equipped to match the site specific geological and geotechnical conditions, and to meet customer's demands. Specifications of the bridges are given as well as details of conveyor belt speeds, modifications to the standards, and number manufactured. Design problems faced with the 60 m bridge are discussed, together with details of the superstructure, method of operation, transportation rates, structural steel used, assembly and power supply. 5 refs.

  14. Bridge Culture of Langde Village

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Langde, a village in Leishan County ofsouthwestern Guizhou province, is known for itslarge number of unique bridges bearing the distinctdesign style of the Miao ethnic group. Animpressive variety of well-preserved ancient

  15. Glass fiber composite resin cores used in wedge-shaped defect dew pulp abutment teeth%玻璃纤维桩复合树脂核在楔状缺损露髓基牙中的应用

    Institute of Scientific and Technical Information of China (English)

    胡建江; 姚悦; 李远祥; 熊雷

    2015-01-01

    目的:观察玻璃纤维桩复合树脂核在楔缺露髓基牙修复中的临床疗效。方法:选取101颗经完善根管治疗的楔缺露髓牙(上颌45颗,下颌56颗),经纤维桩修复后患者经过3、6、12个月随访,观察其临床修复效果。结果:修复后3、6、12个月复查随访发现,上颌前牙11颗,前磨牙27颗,磨牙6颗,下颌前牙15颗,前磨牙33颗,磨牙8颗冠桥无脱落,桩核无脱落及折断,牙齿无折断,X线检查无根折;上颌前牙1颗,桩核脱落,牙齿无折断,X线检查根中1/3折断。修复3、6、12个月效果比较,差异无统计学意义(>0.05)。结论:玻璃纤维桩复合树脂核在楔缺露髓基牙修复中的3、6、12个月的临床疗效无显著性差异。玻璃纤维桩在牙体缺损修复中具有抗牙折性、美观效果好等优点。%Objective To observe the glass fiber composite resin cores in wedge of pulp abutment clinical curative effect of repair. Methods Select 101 after perfect root canal therapy of wedge dew pulp teeth (maxillary 44,mandible 56),the fiber pile repair patients after two years after 3,6 and 12 months follow- up,observe its clinical repair effect. Results Repair after 3,6 and 12 months follow- up findings:review of the maxillary anterior teeth 11,27,premolar teeth six, jaw teeth before 15,premolar 33, molar eight crown bridge without, pile nuclear free fall off and break, no broken teeth,X- ray rootless fold;Upper front teeth one pile nuclear fall off, no broken teeth,X- ray check a third break in the root.Repair effect of 3,6 and 12 months the differences of no statistical significance ( >0.05). Conclusion Glass fiber composite resin cores in wedge of pulp abutment repair clinical curative effect of 3,6 and 12 months there was no significant difference.Glass fiber post in tooth defect have fight tooth folding resistance, beautiful effect is good.

  16. ANGIOGRAPHIC ASPECTS OF MYOCARDIAL BRIDGES

    Directory of Open Access Journals (Sweden)

    Sujatha. M

    2015-12-01

    Full Text Available Introduction: The segment of epicardial coronary artery that traverses intramurally through the myocardium and bridged by a bunch of cardiac muscle fibers is called tunneled artery or intramural artery. The band of cardiac muscle fibers passing over the tunneled artery segment is named as myocardial bridge. During angiography milking effect is observed during systole due to the external pressure of muscle fibers on the tunneled artery that leads to narrowing of vessel lumen and further ischemia. Materials & Methods: It is a prospective study performed from 2012- 2015 in cardiac centers available around Tirupati, Andhra Pradesh, South India. A total number of 2015 adult patients who underwent diagnostic coronary angiography were evaluated to detect myocardial bridges. With the informed consent the relevant data was collected from the patients and analyzed. Results: The prevalence of myocardial bridges was 3.17%. Among the 2015 patients 70.7% are males and 29.2% are females. Among 64 myocardial bridge positive cases 62.5% were male and 37.5% were female patients. Regarding coronary dominance 84% were right dominant and 14.4% were left dominant and 1.6% are balanced. The percentage incidence of myocardial bridging according to dominance was 3.01% for right dominant patients, 4.12% for left dominant patients and 3.1% for balanced dominant patients. In all the myocardial bridge positive cases they were located on the left anterior descending artery (LAD. According to diagnosis the patients with normal coronaries were 22.6%, patients with MILD CAD were 17.9%, patients with single vessel disease were 23.4%, patients with two vessel disease were 14.7% and the patients with triple vessel disease were 21.3%. The 64 myocardial bridging cases were grouped in to three groups according to their age. Incidence of double bridges was observed in 3 cases of which 66.7% males & 33.3% in females. Conclusion: These results show that Andhra Pradesh population are

  17. The stories of two bridges in Ghana

    DEFF Research Database (Denmark)

    Andreasen, Jørgen

    2004-01-01

    Public participation in bridge building was promoted by un habitat in the village of Mankrong. The neighbouring village did not participate in the construction of their bridge. The first flooding washed the second bridge down while the "participative bridge" stood up....

  18. An Expert System for Concrete Bridge Management

    DEFF Research Database (Denmark)

    Brito, J. de; Branco, F. A.; Thoft-Christensen, Palle;

    1997-01-01

    The importance of bridge repair versus new bridge construction has risen in recent decades due to high deterioration rates that have been observed in these structures. Budgets both for building new bridges and keeping the existing ones are always limited. To help rational decision-making, bridge...

  19. Stability of liquid crystalline bridges

    Science.gov (United States)

    Mahajan, Milind P.; Tsige, Mesfin; Taylor, P. L.; Rosenblatt, Charles

    1999-02-01

    The stability of cylindrical bridges of the liquid crystal octylcyanobiphenyl in an immiscible liquid bath was investigated in the nematic and smectic A phases. In the nematic phase the bridge was found to destabilize at a length-to-diameter (slenderness) ratio R similar to that of ordinary Newtonian fluids. On the other hand, the Bingham behavior of the smectic A phase, i.e., an apparent yield stress, enabled the formation of stable columns with R well in excess of π.

  20. Comparison of strain generated in bone by "platform-switched" and "non-platform-switched" implants with straight and angulated abutments under vertical and angulated load: A finite element analysis study

    Directory of Open Access Journals (Sweden)

    Susan Paul

    2013-01-01

    Full Text Available Purpose: The aim of this study was to evaluate the microstrain exhibited by bone around immediately loaded, platform-switched, and non-platform-switched implants under vertical and angled loading using a finite element analysis (FEA and also to evaluate whether platform-switched implants evoke a better response than non-platform-switched implants on a mechanical basis. Materials and Methods: Three-dimensional finite element study was undertaken to model and analyze an immediate loaded situation. FEA was chosen for this study since it is useful in determining the stress and strain around the dental implant. Bone responses to vertical and angulated loads on straight and angulated abutments (platform-switched and non-platform-switched abutments were evaluated. Results: Non-platform-switched abutments tend to exhibit a lower tensile stress and compressive stress but higher microstrain value (conducive to higher chance of bone resorption than platform-switched abutments. Ideal bone remodeling values of microstrain (50-3000 μϵ were exhibited by platform-switched straight abutments under vertical load and angled load (with an abutment-implant diameter difference of 1 mm. Conclusion: In spite of the obvious advantages, the practice of immediate loading is limited due to apprehension associated with compromised bone response and a higher rate of bone loss around an immediately loaded implant. The mechanical basis for the concept of "platform switching" in immediately loaded situation is analyzed in this context. The results of this limited investigation indicated that the ideal values of microstrain (50-3000 microstrain can be exhibited by platform switching of dental implants (with an abutment-implant diameter difference of 1 mm and can be considered as a better alternative for prevention of crestal bone loss when compared to non-platform-switched implants.

  1. Displacements Prediction in Double-Arch Dam Rock Abutment Using SPSS Software Based on Extensometer Readings Case study: Karun 4 Concrete Dam, Iran

    Directory of Open Access Journals (Sweden)

    Hadi kamali Bandpey

    2012-11-01

    Full Text Available In this study we present a method for Displacements Prediction in Double-Arch Dam Rock Abutment Using SPSS Software Based on Extensometer Readings. Displacement in dams is the most tangible and important parameter which could be crucial in their safety. Different elevation displacements are yielded by various loadings and the thrust force imposed on foundation and abutment. Most concrete dams are constructed on stone foundations. Displacements in foundation and abutment are measured by extensometers. Karun 4 Concrete dam is designed with 11 galleries, from elevation 1016 to 802 m, in the order from top elevation (dam crest elevation 1032 to the bottom elevation (dam foundation elevation 806 within the dam body. As a whole, 19 extensometers in the left bank, 17 in the right, and one more in the middle are implemented in the dam. Karun 4 dam has already been impounded with water up to the elevation 1003. Displacements in Karun 4 are recorded by extensometers whence water was leveled in 7 elevations 943.68, 953.36, 973.55, 983.28, 993.17, 1003.13. In this study, using SPSS we have tried to predict the displacements for a situation in which water will be elevated to the elevations 1013, 1023, 1032 in the future for elevations which are equipped with anchor. The most predicted displacement pertaining to the left bank when water was leveled to the elevation 1013, was 3.65 mms by R2 = 0.9997 for the implemented anchor. Proceeding further, as water is leveled to the elevations 1023 and 1033, the most predicted displacement respectively would be 4.31 and 5.66 by R2 = 0.9941; and is related to the anchor implemented in the elevation 936.05. The most predicted displacement for the right bank is 5.9397, 7.2347 and 8.6877 mms by R2 = 0.9995 for the elevation 888.128 m.

  2. Level II scour analysis for Bridge 33 (HUNTTH00220033) on Town Highway 22, crossing Brush Brook, Huntington, Vermont

    Science.gov (United States)

    Burns, Ronda L.; Degnan, James R.

    1997-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HUNTTH00220033 on Town Highway 22 crossing Brush Brook, Huntington, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 8.65-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest except on the downstream right overbank which is pasture. In the study area, Brush Brook has an incised, straight channel with a slope of approximately 0.04 ft/ft, an average channel top width of 42 ft and an average bank height of 3 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 76.7 mm (0.252 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 26, 1996, indicated that the reach was stable. The Town Highway 22 crossing of Brush Brook is a 40-ft-long, two-lane bridge consisting of one 23.5-foot concrete slab span (Vermont Agency of Transportation, written communication, November 30, 1995). The opening length of the structure parallel to the bridge face is 36.9 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 35 degrees to the opening while the opening-skew-to-roadway is 30 degrees. The scour protection measure at the site was type-2 stone fill (less than 36 inches diameter

  3. Effects of Length and Inclination of Implants on Terminal Abutment Teeth and Implants in Mandibular CL1 Removable Partial Denture Assessed by Three-Dimensional Finite Element Analysis

    OpenAIRE

    Amir Fayaz; Alahyar Geramy; Yeganeh Memari; Zahra Rahmani Rahmani

    2016-01-01

    Objectives: This study sought to assess the effects of length and inclination of implants on stress distribution in an implant and terminal abutment teeth in an implant assisted-removable partial denture (RPD) using three-dimensional (3D) finite element analysis (FEA).  Materials and Methods: In this in vitro study, a 3D finite element model of a partially dentate mandible with a distal extension RPD (DERPD) and dental implants was designed to analyze stress distribution in bone around termin...

  4. The State of Prosthetic Bed Mucous Membrane and Periodontium of Abutment and Preserved Teeth in Conditions of Considerable and Total Loss of Teeth and Use of Removable Dentures

    OpenAIRE

    Vasylyshyn, U.

    2014-01-01

    The paper deals with the study of impact of considerable loss of teeth and long-term use of removable dentures on mucous membrane of prosthetic bed and periodontium of abutment and preserved teeth, and also impact on the appearance and course of inflammatory processes in these parts. Materials and research methods: the patients of Dentistry Centre of IFNMU clinic (105 people  from 45 to 70 years old) with considerable and total loss of teeth, treated by the removable dentures, were the object...

  5. Floating liquid bridge charge dynamics

    Science.gov (United States)

    Teschke, Omar; Soares, David Mendez; Gomes, Whyllerson Evaristo; Valente Filho, Juracyr Ferraz

    2016-01-01

    The interaction of liquid with electric fields is investigated in a configuration where up to 13 kV are applied between electrodes resulting in a 106 V/m electric field in the capillaries and where there is the formation of a free-standing fluid bridge in the interelectrode gap. The Mott-Gurney equation was fitted to the measured ionization current vs applied voltage curve which indicates that the ionization rate at the high-voltage anode electrode dimethylsulfoxide (DMSO) interface and space charging in the interelectrode gap determine the floating liquid bridge current for a given cathode-to-anode voltage. Space charge effects were measured in the cathode becker and also at the liquid bridge since the ionized charges at the anode migrate to the bridge outer surface and decrease the interfacial tension from 43 mJ/m2 to 29 mJ/m2. Two distinct structural regions then form the bridge, a charged plastic (bulk modulus ˜100 MPa) conducting outer layer with a surface conductivity of ˜10-9 Ω-1, which shapes and supports the floating fluid structure, and an inner liquid cylinder, where DMSO molecules flow.

  6. A strange bridge by Leonardo

    CERN Document Server

    Huylebrouck, Dirk

    2013-01-01

    On folio 855 recto of the Codex Atlanticus, Leonardo da Vinci drew three 'easily movable' bridges, but one of them is enigmatic: all 'replicas' in Leonardo museums and exhibitions come as a surprise, to say the least, to any engineer or architect whose attention is drawn to it. This is the case for models in Amboise (France), Chicago and Portland (USA), Florence (Italy) and for the one of the traveling exhibition by the Australian company 'Grande Exhibitions' that already visited 40 major cities in the world. All 'replicas' of the bridge model attributed to Leonardo have pillars standing on the deck of the bridge, while the deck is suspended by cables attached on these pillars. At first sight this problem does not catch the attention of the observer, as the bridge seems to be a mixed form of a beam and a suspension bridge, but it was not overlooked by my colleague architect-engineer Dr. Laurens Luyten (Gent, Belgium). Yet, after a TV-interview in Brussels so much pressure was exerted by some of the museum col...

  7. Multicolor fluorescent in situ hybridization to define abutting and overlapping gene expression in the embryonic zebrafish brain

    Directory of Open Access Journals (Sweden)

    Hauptmann Giselbert

    2011-04-01

    Full Text Available Abstract Background In recent years, mapping of overlapping and abutting regulatory gene expression domains by chromogenic two-color in situ hybridization has helped define molecular subdivisions of the developing vertebrate brain and shed light on its basic organization. Despite the benefits of this technique, visualization of overlapping transcript distributions by differently colored precipitates remains difficult because of masking of lighter signals by darker color precipitates and lack of three-dimensional visualization properties. Fluorescent detection of transcript distributions may be able to solve these issues. However, despite the use of signal amplification systems for increasing sensitivity, fluorescent detection in whole-mounts suffers from rapid quenching of peroxidase (POD activity compared to alkaline phosphatase chromogenic reactions. Thus, less strongly expressed genes cannot be efficiently detected. Results We developed an optimized procedure for fluorescent detection of transcript distribution in whole-mount zebrafish embryos using tyramide signal amplification (TSA. Conditions for hybridization and POD-TSA reaction were optimized by the application of the viscosity-increasing polymer dextran sulfate and the use of the substituted phenol compounds 4-iodophenol and vanillin as enhancers of POD activity. In combination with highly effective bench-made tyramide substrates, these improvements resulted in dramatically increased signal-to-noise ratios. The strongly enhanced signal intensities permitted fluorescent visualization of less abundant transcripts of tissue-specific regulatory genes. When performing multicolor fluorescent in situ hybridization (FISH experiments, the highly sensitive POD reaction conditions required effective POD inactivation after each detection cycle by glycine-hydrochloric acid treatment. This optimized FISH procedure permitted the simultaneous fluorescent visualization of up to three unique transcripts

  8. Bridging history and social psychology

    DEFF Research Database (Denmark)

    Glaveanu, Vlad Petre; Yamamoto, Koji

    2012-01-01

    This special issue aims to bridge history and social psychology by bringing together historians and social psychologists in an exercise of reading and learning from each other’s work. This interdisciplinary exercise is not only timely but of great importance for both disciplines. Social...... hand historians can enhance their analysis of historical sources by drawing upon the conceptual tools developed in social psychology. They can “test” these tools and contribute to their validation and enrichment from completely different perspectives. Most important, as contributions to this special......-traditionalized societies—a distinction that lies at the heart of many social psychology accounts of the world we live in. The present editorial will introduce and consider this act of bridging history and social psychology by focusing on three main questions: What is the bridge made of? How can the two disciplines...

  9. Analysis on distribution law of the abutment pressure of the integrated coal beside the road-in packing for gob-side entry retaining in fully-mechanized caving face

    Institute of Scientific and Technical Information of China (English)

    Zhu Chuanqu; Liu Ze; Wang Weijun; Zhang Daobing

    2009-01-01

    The three-dimensional damage constitutive relationship of coal is established and distribution law of the abut-ment pressure of the integrated coal beside the road-in packing for gob-side entry retaining in fully-mechanized caving face under the effect of given deformation of the main roof is analyzed by the damage mechanics theory. And the rela-tionship between distribution of the abutment pressure and thickness of coal seam is explored. The presented result is of great theoretical significance and practical value to the study on stability control of the surrounding rock of road-in pack-ing for gob-side entry retaining in fully-mechanized caving face.

  10. Excitation Methods for Bridge Structures

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

    1999-02-08

    This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

  11. Bridge Number and Conway Products

    OpenAIRE

    Blair, Ryan C.

    2007-01-01

    Schubert proved that, given a composite link $K$ with summands $K_{1}$ and $K_{2}$, the bridge number of $K$ satisfies the following equation: $$\\beta(K)=\\beta(K_{1})+\\beta(K_{2})-1.$$ In ``Conway Produts and Links with Multiple Bridge Surfaces", Scharlemann and Tomova proved that, given links $K_{1}$ and $K_{2}$, there is a Conway product $K_{1}\\times_{c}K_{2}$ such that $$\\beta(K_{1}\\times_{c} K_{2}) \\leq \\beta(K_{1}) + \\beta(K_{2}) - 1$$ In this paper, we define the generalized Conway prod...

  12. Optimum selection on bridge erection with floating crane in East China Sea Bridge and Hangzhou Bay Bridge

    Institute of Scientific and Technical Information of China (English)

    Shunquan Qin; Pu Zhou; Youheng Hua

    2004-01-01

    @@ Introduction With the rapid development of China′s economy, many bridges will be built over the Chinese coastal waters of Pacific Ocean. Among them, construction of East China Sea Bridge has been commenced in June 2001, and will be completed at the end of 2005, Hangzhou Bay Bridge was also started to construct in June 2003(Fig. 1). These two ultralong bridges are designed as twin expressway bridges standing side by side each carries a 3-lane one-way carriageway. The total width is 31.5m and 33.0m respectively. East China Sea Bridge starts from Nanhui District, Shanghai and extends to the Yangshan Deep Water Port Area, which is located at one of the Qiqu Islands. The total length of the bridge is about 31.0 km, in which 25 km are on the sea, and 22 km is in the unnavigable region. Hangzhou Bay Bridge across the mouth of Qiantang River.

  13. Is myocardial bridging a bridge connecting to cardiovascular events?

    Institute of Scientific and Technical Information of China (English)

    LI Jian-jun

    2010-01-01

    @@ Coronary arteries and their major branches usually course on the surface of the heart in the subepicardial tissue. However, a muscle hber overlying the intramyocardial segment of an epicardial coronary artery was defined as myocardial bridging (MB), and subsequently the artery coursing within the myocardium is called a tunneled artery.

  14. Level II scour analysis for Bridge 29 (CRAFTH00550029) on Town Highway 55, crossing the Black River, Craftsbury, Vermont

    Science.gov (United States)

    Boehmler, Erick M.; Degnan, James R.

    1996-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure CRAFTH00550029 on town highway 55 crossing the Black River, Craftsbury, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province of north-central Vermont in the town of Craftsbury. The 24.7-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the banks have woody vegetation coverage except for the upstream left bank and the downstream right bank, which have more brush cover than trees. In the study area, the Black River has an incised, sinuous channel with a slope of approximately 0.01 ft/ft, an average channel top width of 41 ft and an average channel depth of 5.5 ft. The predominant channel bed material is sand and gravel (D50 is 44.7 mm or 0.147 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 7, 1995, indicated that the reach was stable. The town highway 55 crossing of the Black Riveris a 32-ft-long, one-lane bridge consisting of one 28-foot span steel stringer superstructure with a timber deck (Vermont Agency of Transportation, written communication, August 4, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 40 degrees to the opening while the opening-skew-to-roadway is 10 degrees. A scour hole 2 ft deeper than the mean thalweg depth was

  15. In vitro synchrotron-based radiography of micro-gap formation at the implant–abutment interface of two-piece dental implants

    International Nuclear Information System (INIS)

    Micro-radiography using hard X-ray synchrotron radiation is the first potential tool to allow an evaluation of the mechanical behavior of the dental implant–abutment complex during force application, thus enabling the enhancement of the design of dental implants which has been based on theoretical analysis to date. Micro-gap formation at the implant–abutment interface of two-piece dental implants was investigated in vitro using high-resolution radiography in combination with hard X-ray synchrotron radiation. Images were taken with the specimen under different mechanical loads of up to 100 N. The aim of this investigation was to prove the existence of micro-gaps for implants with conical connections as well as to study the mechanical behavior of the mating zone of conical implants during loading. Synchrotron-based radiography in comparison with classical laboratory radiography yields high spatial resolution in combination with high contrast even when exploiting micro-sized features in highly attenuating objects. The first illustration of a micro-gap which was previously indistinguishable by laboratory methods underlines that the complex micro-mechanical behavior of implants requires further in vitro investigations where synchrotron-based micro-imaging is one of the prerequisites

  16. [Analysis of the effect of contact strength on three-dimensional displacement of an implant-supported fixed bridge under axial-concentrated load using digital laser speckle photography].

    Science.gov (United States)

    Wang, Jun; Peng, Zhenzhen; Li, Aijie; Xu, Zujie; Chen, Xinmin

    2013-12-01

    The purpose of this study was to investigate the effect of four kinds of different contact strength on the three-dimensional displacement of an implant-supported fixed bridge using digital laser speckle photography method. An in vitro model of beagle mandible with an implant-supported fixed bridge in its right premolar region was developed. The bridge was Au-Pt metal-ceramic. The contact was recovered to four different tightnesses, named 0, 1, 2, and 3. Different axial concentrated static load was applied to abutments and bridge respectively. The three-dimensional displacement of the implant-supported fixed bridge was measured using digital laser speckle photographic method. The results demonstrated that the influence of contact tightness was mainly on the mesio-distal and buccal lingual parts. When the contact tightness reached number 3, the regularity of displacement distribution was changed. The present study proved that digital laser speckle photography was an effective method of measuring the micro-displacement. One of the criterions of contact recovering decreased the implant displacement effectively without changing the regularity of displacement distribution.

  17. Architectural engineering of FRP bridges

    OpenAIRE

    Smits, J.E.P.

    2014-01-01

    This paper deals with the use of Fibre Reinforced Polymers (FRP's) in architectural and structural bridge design. The challenges and opportunities that come with this relatively new material are discussed. An inventory is made of recent engineers' solutions in FRP, followed by a discussion on architectural application of FRP's derived from the authors architectural practice.

  18. Instability of the capillary bridge

    Science.gov (United States)

    Pare, Gounseti; Hoepffner, Jerome

    2014-11-01

    Capillary adhesion is a physical mechanism that maintains two bodies in contact by capillarity through a liquid ligament. The capillary bridge is an idealization of this capillary adhesion. In this study we first focus on the classical case of the stability of the capillary bridge. Secondly we study a slightly more complex configuration, imagining a flow in the capillary bridge as in the case of the dynamics of the neck of a liquid ligament, in its withdrawal under the effect of capillarity. Inspired by the experiments on soap films of Plateau, the configuration analyzed consists of an initially axisymmetric, mass of fluid held by surface tension forces between two parallel, coaxial, solid pipes of the same diameter. The results presented are obtained by numerical simulations using the free software, Gerris Flow Solver. We first focus on the capillary Venturi. In the static configuration the stability diagram of the capillary bridge obtained is in perfect agreement with the results of Lev A. Slobozhanin. In the dynamic case we develop a matlab code based on the one dimensional equations of Eggers and Dupont. The comparison of the bifurcation diagram obtained and the numerical simulations shows a good agreement.

  19. Bridge Aesthetics and Structural Honesty

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1999-01-01

    In bridges the overall form must be chosen with due respect to the transmission of forces if efficient structures shall be created, The design must therefore be governed by experienced structural engineers - in some cases assisted by aesthetic advisers on specific issues. Some basic requirements...

  20. The Wien Bridge Oscillator Family

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2006-01-01

    A tutorial in which the Wien bridge family of oscillators is defined and investigated. Oscillators which do not fit into the Barkhausen criterion topology may be designed. A design procedure based on initial complex pole quality factor is reported. The dynamic transfer characteristic...

  1. Architectural engineering of FRP bridges

    NARCIS (Netherlands)

    Smits, J.E.P.

    2014-01-01

    This paper deals with the use of Fibre Reinforced Polymers (FRP's) in architectural and structural bridge design. The challenges and opportunities that come with this relatively new material are discussed. An inventory is made of recent engineers' solutions in FRP, followed by a discussion on archit

  2. Intercellular bridges in vertebrate gastrulation.

    Directory of Open Access Journals (Sweden)

    Luca Caneparo

    Full Text Available The developing zebrafish embryo has been the subject of many studies of regional patterning, stereotypical cell movements and changes in cell shape. To better study the morphological features of cells during gastrulation, we generated mosaic embryos expressing membrane attached Dendra2 to highlight cellular boundaries. We find that intercellular bridges join a significant fraction of epiblast cells in the zebrafish embryo, reaching several cell diameters in length and spanning across different regions of the developing embryos. These intercellular bridges are distinct from the cellular protrusions previously reported as extending from hypoblast cells (1-2 cellular diameters in length or epiblast cells (which were shorter. Most of the intercellular bridges were formed at pre-gastrula stages by the daughters of a dividing cell maintaining a membrane tether as they move apart after mitosis. These intercellular bridges persist during gastrulation and can mediate the transfer of proteins between distant cells. These findings reveal a surprising feature of the cellular landscape in zebrafish embryos and open new possibilities for cell-cell communication during gastrulation, with implications for modeling, cellular mechanics, and morphogenetic signaling.

  3. Dynamic identification of paradela historic railway bridge

    OpenAIRE

    Ramos, Luís F.; Valente, Isabel; Guimarães, Paulo; Vazquez, Kevin; Lourenço, Paulo B.

    2013-01-01

    Paradela Bridge is a metallic bridge located along the bank of the Tua River in northern Portugal. While the bridge is not currently in service, its structure is representative of many metallic truss structures built across the country between the 19th and the 20th century. The construction of the Paradela Bridge was completed in 1886 and served for about 120 years connecting northern Portugal. Tua Line belongs to the Douro area that UNESCO recently declared as world heritage. This work acqui...

  4. Path transformations of first passage bridges

    OpenAIRE

    Bertoin, Jean

    2003-01-01

    We define the first passage bridge from 0 to $\\lambda$ as the Brownian motion on the time interval $[0,1]$ conditioned to first hit $\\lambda$ at time 1. We show that this process may be related to the Brownian bridge, the Bessel bridge or the Brownian excursion via some path transformations, the main one being an extension of Vervaat's transformation. We also propose an extension of these results to certain bridges with cyclically exchangeable increments.

  5. 47 CFR 80.331 - Bridge-to-bridge communication procedure.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge communication procedure. 80..., Alarm, Urgency and Safety Procedures § 80.331 Bridge-to-bridge communication procedure. (a) Vessels... position). I plan to (give proposed course of action). Over. (3) (Coast station), this is (vessel's...

  6. Clear-water abutment and contraction scour in the Coastal Plain and Piedmont Provinces of South Carolina, 1996-99

    Science.gov (United States)

    Benedict, Stephen T.

    2016-01-01

    The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, collected observations of clear-water aburment and contraction scour at 146 bridges in the Coastal Plain and Piedmont of South Carolina. Scour depths ranged from 0 to 23.6 feet. Theoretical scour depths were computed at each bridge and compared with observed scour. This comparison showed that theoretical scour depths, in general, exceeded the observed scour depths and often were excessive. A comparison of field data with dimensionless relations for laboratory data showed that the range of dimensionless variables used in laboratory investigations was outside of the range for field data in South Carolina, suggesting laboratory relations may not be applicable to field conditions in South Carolina. Variables determined to be important in developing scour within laboratory studies were investigated to understand their influence within the South Carolina field data, and many of these variables appeared to be insignificant under field conditions found in South Carolina. The strongest explanatory variables were embankment length, geometric-contraction ratio, approach velocity, and soil cohesion. Envelope curves developed with the field data are useful tools for assessing reasonable ranges of scour depth in South Carolina. These tools are simple to apply and are an improvement over the current methods for predicting theoretical scour.

  7. Remediation: Higher Education's Bridge to Nowhere

    Science.gov (United States)

    Complete College America, 2012

    2012-01-01

    The intentions were noble. It was hoped that remediation programs would be an academic bridge from poor high school preparation to college readiness. Sadly, remediation has become instead higher education's "Bridge to Nowhere." This broken remedial bridge is travelled by some 1.7 million beginning students each year, most of whom will…

  8. Comparison between Modern Violin Bridge and Baroque Violin Bridge by Photoelastic Observation and Frequency Analysis

    Science.gov (United States)

    Matsutani, Akihiro

    2004-05-01

    A comparison between the modern bridge and the baroque bridge of the violin by photoelastic observation was carried out. The relationship between the stress part and the hole is symmetric in the modern and baroque bridges. The measured spectral envelopes of baroque bridges are similar to those of modern bridges in D- or G-strings, and have peaks at a frequency higher than those of modern bridges in E-string. The visualization method as used in this study may provide hints for the design of violin bridges.

  9. Comprehensive Real-Time Bridge Health Monitoring System of Tongtai Bridge

    OpenAIRE

    Lei Su-su; Gao Yong-tao; Pan Dan-guang

    2015-01-01

    Tongtai Bridge is the world’s largest suspension curve-girder-skew-arch bridge, which is located in Zhangjiakou, China. The understanding of mechanics characteristics is limited to such complex bridges, so it is necessary to establish reliable health monitoring system to investigate the static and dynamic responses and monitor the safety of the bridge. A comprehensive real-time bridge health monitoring system is establish, which includes four aspects: sensor system, data acquisition and trans...

  10. Level II scour analysis for Bridge 30 (BRIDTH00330030) on Town Highway 33, crossing Dailey Hollow Branch, Bridgewater, Vermont

    Science.gov (United States)

    Olson, Scott A.; Song, Donald L.

    1996-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure BRIDTH00330030 on town highway 33 crossing Dailey Hollow Branch, Bridgewater, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I study is included in Appendix E of this report. A Level I study provides a qualitative geomorphic characterization of the study site. Information on the bridge available from VTAOT files was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the Green Mountain physiographic province of central Vermont in the town of Bridgewater. The 7.51-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest. In the study area, Dailey Hollow Branch has an incised, sinuous channel with a slope of approximately 0.013 ft/ft, an average channel top width of 45 ft and an average channel depth of 5 ft. The channel bed material ranges from sand to boulder with a median grain size (D50) of 60.7 mm (0.199 ft). The geomorphic assessment at the time of the Level I and Level II site visit on November 1, 1994, indicated that the reach was stable. The town highway 33 crossing of Dailey Hollow Branch is a 31-ft-long, one-lane bridge consisting of one 25-foot steel-beam span with a timber deck (Vermont Agency of Transportation, written communication, August 25, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is 0 degrees. Type-2 stone-fill (less than 36 inches diameter) protection was found at all four wingwalls. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed

  11. New Concept for Durable Concrete Bridges

    OpenAIRE

    Damek, Marek

    2015-01-01

    This master’s thesis covers the design of a post-tensioned concrete bridge in Trondheim municipality in Norway, in collaboration with Statens vegvesen (SVV). The concept of the bridge is inspired by Egg-Graben-Brücke in Austria, which was designed and built without steel reinforcement in the bridge deck. The idea is to eliminate steel reinforcement which can corrode in the bridge deck. The total length of the bridge is 73 meters and it is divided into 3 spans. The crosssection ...

  12. Heavy Vehicles on Minor Highway Bridges

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Nielsen, Søren R. K.; Enevoldsen, I.

    Vibration of a bridge structure due to the passage of vehicles is an important consideration in the design of bridges. Further, a common problem in bridge engineering practice in these years is the upgrading of minor highway bridges (=5-20 m) to carry heavier loads partly due to a tendency...... of heavier trucks moving at larger speeds, and partly because the authorities want to permit transportation of special heavy goods at a larger part of the road net. These needs will in many cases cause the strengthening of the bridges becomes necessary. In order to keep the expenses of such strengthening...... the results obtained using the numerical models given in details in "Heavy Vehicles on Minor Highway Bridges : dynamic modelling of vehicles and bridges". The models are established using a ordinary vehicle which consists of a 48 t Scania with a 3 axle tractor and a 3 axle trailer, joined in a flexible hinge...

  13. Heavy Vehicles on Minor Highway Bridges

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Nielsen, Søren R. K.; Enevoldsen, I.

    Vibration of a bridge structure due to the passage of vehicles is an important consideration in the design of bridges. Further, a common problem in bridge engineering practice in these years is the upgrading of minor highway bridges (=5-20 m) to carry heavier loads partly due to a tendency...... of heavier trucks moving at larger speeds, and partly because the authorities want to permit transportation of special heavy goods at a larger part of the road net. These needs will in many cases cause the strengthening of the bridges becomes necessary. In order to keep the expenses of such strengthening...... the numerical models for the mathematical models of the vehicles and the bridge from which the load amplification factors can be estimated assuming that the dynamic parameters of the vehicles and the modal parameters of the bridge are known....

  14. Level II scour analysis for Bridge 33 (BRIDTH00050033) on Town Highway 5, crossing the North Branch Ottauquechee River, Bridgewater, Vermont

    Science.gov (United States)

    Olson, Scott A.; Song, Donald L.

    1996-01-01

    communication, August 25, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is 10 degrees. A scour hole 1.0 ft deeper than the mean thalweg depth was observed along the right abutment and upstream right wingwall during the Level I assessment. Scour protection measures at the site include type-2 stone fill (less than 36 inches diameter) at the ends of all the wingwalls except the upstream left which has type-3 stone fill (less than 48 inches diameter). Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1993). Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 0.0 to 0.7 ft. The worst-case contraction scour occurred at the incipient-overtopping discharge, which was less than the 100-year discharge. Abutment scour ranged from 5.3 to 7.2 ft. The worst-case abutment scour occurred at the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A crosssection of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle

  15. Full-bridge capacitive extensometer

    Science.gov (United States)

    Peters, Randall D.

    1993-08-01

    Capacitive transducers have proven to be very effective sensors of small displacements, because of inherent stability and noninvasive high resolution. The most versatile ones have been those of a differential type, in which two elements are altered in opposite directions in response to change of the system parameter being monitored. Oftentimes, this differential pair has been incorporated into a bridge circuit, which is a useful means for employing synchronous detection to improve signal to noise ratios. Unlike previous differential capacitive dilatometers which used only two active capacitors, the present sensor is a full-bridge type, which is well suited to measuring low-level thermal expansions. This analog sensor is capable of 0.1 μm resolution anywhere within a range of several centimeters, with a linearity of 0.1%. Its user friendly output can be put on a strip chart recorder or directed to a computer for sophisticated data analysis.

  16. Noise Considerations in Resistance Bridges

    DEFF Research Database (Denmark)

    Diamond, Joseph M.

    1963-01-01

    thermometry, where the noise in the unknown resistor will predominate strongly. An impedance step-up device (transformer or tuned circuit) is valuable in raising the bridge signal and noise level above the noise of the first amplifier tube. However, as the step-up ratio is increased, two counterfactors appear......, namely, noise in the loss resistance of the step-up device, and grid current noise. There is therefore an optimum step-up ratio, which has been found. The step-up device is permitted to have a different temperature from the unknown and standard resistors, to evaluate the advantage of cooling it....... With certain assumptions about the noise and grid current of the first tube it is found that the equivalent temperature of a unity ratio (Mueller) bridge used for liquid helium measurements may be 400°K....

  17. Stability of Axisymmetric Liquid Bridges

    CERN Document Server

    Rubinstein, Boris

    2016-01-01

    We study stability of axisymmetric liquid bridges between two axisymmetric solid bodies in the absence of gravity under arbitrary asymmetric perturbations which are expanded into a set of angular Fourier modes. We determine the stability region boundary for every angular mode in case of both fixed and free contact lines. Application of this approach allows us to demonstrate existence of stable convex nodoid menisci between two spheres.

  18. 2015 Bridge Inspection ERC Training

    OpenAIRE

    Dougherty, Merril

    2015-01-01

    This presentation will discuss recent changes to the County Bridge Inspection Program from the perspective of both the FHWA and INDOT. We will also discuss the responsibilities of the local public agency’s (LPA’s) employee in responsible charge (ERC) with respect to managing this program. As this course is a yearly requirement, all county ERCs are encouraged to attend. Pre-registering is strongly encouraged by e-mailing your contact information to .

  19. The Bridge Program - Participant Perspectives

    OpenAIRE

    Rönnqvist, Riitta; Hakonen, Anu; Vartiainen, Matti

    2015-01-01

    The Nokia Bridge Program was established in summer 2011 in order to "make the best of the restructuring: create meaningful opportunities for individuals and local economies impacted by workforce reductions" and to "assist individuals in re-employment". This document reports whether and how the program helped individuals avoid the known negative effects of job loss and find meaningful re-employment. The document also reports how affected employees formed perceptions about Nokia´s fairness and ...

  20. Inspection Strategies for Concrete Bridges

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1989-01-01

    In this paper an optimal inspection strategy for concrete bridges based on periodic routine and detailed inspections is presented. The failure mode considered is corrosion of the reinforcement due to chlorides. A simple modelling of the corrosion and of the inspection strategy is presented....... The optimal inspection strategy is determined from an optimization problem, where the design variables are time intervals between detailed inspections and the concrete cover. The strategy is illustrated on a simple structure, namely a reinforced concrete beam....

  1. Parabolic metamaterials and Dirac bridges

    Science.gov (United States)

    Colquitt, D. J.; Movchan, N. V.; Movchan, A. B.

    2016-10-01

    A new class of multi-scale structures, referred to as `parabolic metamaterials' is introduced and studied in this paper. For an elastic two-dimensional triangular lattice, we identify dynamic regimes, which corresponds to so-called `Dirac Bridges' on the dispersion surfaces. Such regimes lead to a highly localised and focussed unidirectional beam when the lattice is excited. We also show that the flexural rigidities of elastic ligaments are essential in establishing the `parabolic metamaterial' regimes.

  2. Severe ASR damaged concrete bridges

    DEFF Research Database (Denmark)

    Antonio Barbosa, Ricardo; Gustenhoff Hansen, Søren

    2015-01-01

    Technical University of Denmark (DTU) and University of Southern Denmark (SDU) have conducted several full-scale experiments with severe ASR deteriorated bridges. This paper presents few and preliminary results from both the shear tests and the measuring of the material properties. The shear test...... show that the shear capacity is almost unaffected of ASR despite significant reduction in compressive concrete strength. Furthermore, measurements show a significant tensile reinforcement strain developed due to ASR expansion....

  3. Halliburton Composite Bridge Plug Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Starbuck, J.M.; Luttrell, C.R.; Aramayo, G.

    2005-01-15

    The overall objectives of this CRADA were to assist Halliburton in analyzing a composite bridge plug and to determine why their original design was failing in the field. In Phase 1, finite element analyses were done on the original composite slip design and several alternative designs. The composite slip was the component in the bridge plug that was failing. The finite element code ABAQUS was used for these calculations and I-DEAS was used as the pre- and post-processor in the analyses. Several different designs and materials were analyzed and recommendations were made towards improving the design. In Phase 2, the objective was to develop finite element models that would accurately represent the deformations in the entire all-composite 4-1/2' diameter bridge plug assembly. The finite element code LS-DYNA was used and the results from this effort were intended to expand Halliburton's composite design and analysis capabilities with regard to developing future composite components for downhole tools. In addition to the finite element modeling, this effort involved the utilization of micromechanics to determine the necessary composite material properties that were needed as input for finite element codes.

  4. Nondestructive evaluation techniques for enhanced bridge inspection

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.; Benson, S.; Durbin, P.; Del Grande, N.; Haskins, J.; Brown, A.; Schneberk, D.

    1993-10-01

    Nondestructive evaluation of bridges is a critical aspect in the US aging infrastructure problem. For example in California there are 26,000 bridges, 3000 are made of steel, and of the steel bridges, 1000 are fracture critical. California Department of Transportation (Caltrans), Federal Highway Administration, and Lawrence Livermore National Laboratory (LLNL) are collaborating to develop and field NDE techniques to improve bridge inspections. We have demonstrated our NDE technologies on several bridge inspection applications. An early collaboration was to ultrasonically evaluate the steel pins in the E-9 pier on the San Francisco Bay Bridge. Following the Loma-Prieta earthquake in 1989 and the road way collapse at the E-9 pier, a complete nondestructive evaluation was conducted by Caltrans inspectors and several ultrasonic indications were noted. LLNL worked with Caltrans to help identify the source of these reflections. Another project was to digitally enhance high energy radiographs of bridge components such as cable end caps. We demonstrated our ability to improve the detection of corrosion and fiber breakage inside the end cap. An extension of this technology is limited view computer tomography (CT). We implemented our limited view CT software and produced cross-sectional views of bridge cables from digitized radiographic films. Most recently, we are developing dual band infrared imaging techniques to assess bridge decks for delaminations. We have demonstrated the potential of our NDE technology for enhancing the inspection of the country`s aging bridges.

  5. Study on structural system of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Xigang; Pei Minshan; Yuan Hong; Xu Liping; Zhu Bin

    2009-01-01

    Sutong Bridge, whose layout is [ (100 + 100 + 300) + 1 088 + ( 300 + 100 + 100) ] m, marks the largest span of cable-stayed bridges in the world. The complex natural condition at the bridge site and the strict requirements for resistance of wind and seismic action make it crucial to choose a favorable structural system to assure the function and safety of the bridge. The comparison among several optional structural systems for Sutong Bridge is illustrated. After detailed analysis is carried out for viscous damper and hydraulic buffer, super liquid viscous damper with additional displacement limitation is designed for the first application in bridge engineering. The parameters for the damper is analyzed and studied and the dampers are installed suecessfuUy after quality tests.

  6. Evaluation method research on prestressed concrete bridges

    Institute of Scientific and Technical Information of China (English)

    HUANG Qiao; LIN Yang-zi; REN Yuan

    2008-01-01

    Considering the construction features of prestressed concrete bridge, the comprehensive evaluation method about the bridge damage conditions are studied. Particular attentions are paid on establishing a multi-level evaluation model for damaged prestressed concrete bridge, and the evaluation indices of the model as well as the rating standards are defined in the model. A normal relative function about the evaluation indices of each element is developed to calculate the relative degree, and for each element which is no sub-level elements. When evaluating the elements in sub-item level or index level of the model, the weights of elements that are pertained to one element are adopted, taking account of their deterioration degree. At the same time, the dam-age conditions of bridge are characterized by relative degree, element evaluation scale and structural technology mark of bridge ,so it agrees with Code for Maintenance of Highway Bridges and Culvers.

  7. Seismic Evaluation of Highway Bridges - Phase 1

    OpenAIRE

    Ramirez, J.A.; Pan, Austin D.; Mwakasisi, Frank Thompson

    1996-01-01

    The primary objective of the study was to establish the guidelines for screening, assessing, and ranking Indiana bridges for seismic upgrade. The outcome of the study is a complete strategy for the detailed structural assessment of Indiana highway bridges subjected to seismic forces. The structural evaluation is conducted using a nonlinear time-history analysis of the bridge for simulated or actual records. The specific soil conditions at the site are accounted in terms of the ground motio...

  8. REPORT: BioMedBridges standards workshop

    OpenAIRE

    Conte, Nathalie; Hancocks, Tom; Suhr, Stephanie

    2014-01-01

    This workshop, co-organized by BioMedBridges WP3 and 12, was held on 24-25 June and hosted by BioMedBridges partners at VUMC in Amsterdam. Attendees included BioMedBridges personnel, members from the ESFRI BMS research infrastructures and invited external experts from existing standards organisations. The following aspects of data standardisation were explored: Defining entity identifiers and identifiers best practice Development of a Meta models and Mappings Registry for bio...

  9. Analysis of liquid bridge between spherical particles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A pair of central moving spherical particles connected by a pendular liquid bridge with interstitial Newtonian fluid is often encountered in pariculate coalescence process. In this paper, by assuming perfect-wet condition, the effects of liquid volume and separation distance on static liquid bridge are analyzed, and the relation between rupture energy and liquid bridge volume is also studied. These points would be of significance in industrial processes related to adhesive particles.

  10. Bridge engineering handbook construction and maintenance

    CERN Document Server

    Chen, Wai-Fah

    2014-01-01

    Over 140 experts, 14 countries, and 89 chapters are represented in the second edition of the Bridge Engineering Handbook. This extensive collection highlights bridge engineering specimens from around the world, contains detailed information on bridge engineering, and thoroughly explains the concepts and practical applications surrounding the subject.Published in five books: Fundamentals, Superstructure Design, Substructure Design, Seismic Design, and Construction and Maintenance, this new edition provides numerous worked-out examples that give readers step-by-step design procedures, includes c

  11. Markovian Bridges: Weak continuity and pathwise constructions

    OpenAIRE

    Chaumont, Loïc; Uribe Bravo, Gerónimo

    2009-01-01

    A Markovian bridge is a probability measure taken from a disintegration of the law of an initial part of the path of a Markov process given its terminal value. As such, Markovian bridges admit a natural parameterization in terms of the state space of the process. In the context of Feller processes with continuous transition densities, we construct by weak convergence considerations the only versions of Markovian bridges which are weakly continuous with respect to their parameter. We use this ...

  12. Life Cycle Assessment of a Norwegian Bridge

    OpenAIRE

    Dequidt, Thomas Charles Edouard

    2012-01-01

    Life cycle assessment (LCA) methodology aims at evaluating the environmental impacts of a product or system from a holistic approach. In this methodology, all life cycle phases of the product are identified and assessed, from the raw material acquisition to the end-of-life phase. This master thesis is dealing with the LCA of a Norwegian bridge. First, a literature review is realized by going through 14 bridge LCA references. Then, a detailed description of bridge LCA methodology ...

  13. Bridge Engineering-Oriented Parametric Model

    Institute of Scientific and Technical Information of China (English)

    周凌远; 李乔

    2004-01-01

    A new model is proposed to improve the efficiency of structural modeling. In this model, the bridge structural components are expressed with component description, parametric description and geometric description in a software system. This model provides both convenience and flexibility for users in structural modeling process. The object-oriented method is applied in the model implementation. A bridge analysis preprocessor is developed on the basis of this model. It provides an effective way for bridge modeling.

  14. Dynamics and Statics of Nonaxisymmetric Liquid Bridges

    Science.gov (United States)

    Alexander, J. Iwan D.; Resnick, Andrew H.; Slobozhanin, L. A.

    1996-01-01

    Theoretical and experimental investigation of the stability of nonaxisymmetric and nonaxisymmetric bridges contained between equal and unequal radii disks as a function of Bond and Weber number with emphasis on the transition from unstable axisymmetric to stable nonaxisymmetric shapes, are conducted. Numerical analysis of the stability of nonaxisymmetric bridges between unequal disks for various orientations of the gravity vector is performed. Experimental and theoretical investigation of large (nonaxisymmetric) oscillations and breaking of liquid bridges are also conducted.

  15. Maximal liquid bridges between horizontal cylinders

    OpenAIRE

    Cooray, Himantha; Huppert, Herbert E.; Neufeld, Jerome A

    2016-01-01

    We investigate two-dimensional liquid bridges trapped between pairs of identical horizontal cylinders. The cylinders support forces due to surface tension and hydrostatic pressure which balance the weight of the liquid. The shape of the liquid bridge is determined by analytically solving the nonlinear Laplace-Young equation. Parameters that maximize the trapping capacity (defined as the cross-sectional area of the liquid bridge) are then determined. The results show that these parameters can ...

  16. Axisymmetric long liquid bridges stability and resonances

    OpenAIRE

    Meseguer Ruiz, José; Sanz Andres, Angel Pedro; Perales Perales, José Manuel

    1990-01-01

    In this paper mathematical expressions for minimum-volume stability limits and resonance frequencies of axisymmetric long liquid bridges are presented. These expressions are valid for a wide range of liquid bridge configurations, accounting for ef-fects like unequal disks and axial microgravity in the case of minimum-volume stability limits,and unequal disks, axial microgravity,non-zero viscosity and liquid bridge volume different from the cylindrical one in the case of resonance frequenc...

  17. Clinical Research of Repairing Single Posterior Tooth Loss by Adhesion Fixed Bridge%粘结固定桥修复单个后牙缺失的临床研究

    Institute of Scientific and Technical Information of China (English)

    彭蓓; 储雯; 张婉丽; 杨杨; 张晓渝; 王祥云; 黄大海

    2013-01-01

    目的 观察改良C型粘结固定桥修复下颌单个后牙缺失伴桥基牙倾斜的患者的临床效果.方法 选择口腔门诊下颌单个后牙缺失并伴远端基牙向近中或舌侧倾斜的32例患者,采用改良C型粘结桥修复,修复体粘结后即刻、半年、la和2a观察,对修复体边缘适合性、基牙菌斑指数、X线片检查和患者主观感受等方面进行评价.结果 修复后半年内复查,未有一例失败,基牙菌斑指数与对照牙相比,差异无统计学意义(P>0.05);0.5~2a定期复查有4例舌侧属翼板松脱,但患者自觉咀嚼功能良好,X线片显示基牙牙周膜间隙无异常,基牙菌斑指数与对照牙相比,差异有统计学意义(P<0.05).结论 改良C型粘结固定桥修复下颌单个后牙缺失,短期临床修复效果较好,树脂粘接技术也能满足临床修复的要求,但修复后牙周的维护是很有必要的.%Objective To observe the clinical result of patients with single posterior tooth and abutment tooth bevel repaired by improved C-type retainer adhesion fixed bridge. Methods 32 patients with loss of mandibule single posterior tooth and abutment tooth bevel buccal or lingual direction were selected using C-type retainer adhesion fixed bridge to restore. We observed the bonder compatibility, abutment dental plaque index, radiography and subjective perception of patients after bond instantly, half a year,1year and 2 years after treatment. Results Patients were reviewed in half a year after treatment, and there was no failure. Compared with control teeth, abutment dental plaque index didn't show statistically significant difference (P > 0.05). 4 cases occurred lingual wing loosening after recheck in 0.5-2 years, but patients felt good masticatory function. Radiography displayed normal periodontal membrane space, abutment dental plaque achieved statistically significant difference (P<0.05). Conclusion Improved C-type retainer adhesion fixed bridge has better repair

  18. Crystal growth under bridge foundation

    OpenAIRE

    Ramon Tarragona, Anna; Alonso Pérez de Agreda, Eduardo

    2012-01-01

    W(H)YDOC PhD Prize 2012, durant el 4th International Workshop of Young Doctors in Geomechanics W(H)YDOC 2012. A high-speed railway viaduct experienced a sustained heave at high rates after its construction. The pillars of the bridge are founded on an Eocene hard anhydritic-gypsiferous claystone by means of massive foundations. Field investigations identified an active layer below the piles’ tips where expansions occur as a result of gypsum crystal growth in discontinuities from supersatura...

  19. Nanoclusters a bridge across disciplines

    CERN Document Server

    Jena, Purusottam

    2010-01-01

    This comprehensive book on Nanoclusters comprises sixteen authoritative chapters written by leading researchers in the field. It provides insight into topics that are currently at the cutting edge of cluster science, with the main focus on metal and metal compound systems that are of particular interest in materials science, and also on aspects related to biology and medicine. While there are numerous books on clusters, the focus on clusters as a bridge across disciplines sets this book apart from others. Delivers cutting edge coverage of cluster science Covers a broad range of topics in

  20. Family Medicine: Bridge to Life.

    Science.gov (United States)

    Luz, Clare

    2016-01-01

    Reflecting on the suicide of a close friend, this essay explores what comprises, and inspires a will to live, and how those in Family Medicine can address suicide risk even in the face of debilitating or terminal illness. Research indicates that the will to live is a measurable indicator of general well-being, distinct from depression, and an important predictor of a person's motivation to "hold on to life". As such, understanding what is at the heart of a desire to live should alter clinical practice. This essay offers ideas for ways in which to create bridges for patients that could help sustain life.

  1. A bridge to advanced mathematics

    CERN Document Server

    Sentilles, Dennis

    2011-01-01

    This helpful workbook-style ""bridge"" book introduces students to the foundations of advanced mathematics, spanning the gap between a practically oriented calculus sequence and subsequent courses in algebra and analysis with a more theoretical slant. Part 1 focuses on logic and number systems, providing the most basic tools, examples, and motivation for the manner, method, and concerns of higher mathematics. Part 2 covers sets, relations, functions, infinite sets, and mathematical proofs and reasoning. Author Dennis Sentilles also discusses the history and development of mathematics as well a

  2. Myocardial bridges: morphological and functional aspects.

    OpenAIRE

    A.G. Ferreira; Trotter, S E; König, B; Décourt, L V; Fox, K; Olsen, E G

    1991-01-01

    OBJECTIVE--To assess the arrangement of myocardial bridges. DESIGN--A necropsy study of 90 consecutive hearts (56 male, 34 female). RESULTS--Myocardial bridges, either single or multiple, were seen in 50 (55.6%) of the 90 hearts. The left anterior descending artery was the most commonly affected artery. Thirty five of the 50 hearts which contained in total 41 muscle bridges were dissected further with a magnifying glass. Two different types of muscle bridges could be identified. Thirty one of...

  3. A data management infrastructure for bridge monitoring

    Science.gov (United States)

    Jeong, Seongwoon; Byun, Jaewook; Kim, Daeyoung; Sohn, Hoon; Bae, In Hwan; Law, Kincho H.

    2015-04-01

    This paper discusses a data management infrastructure framework for bridge monitoring applications. As sensor technologies mature and become economically affordable, their deployment for bridge monitoring will continue to grow. Data management becomes a critical issue not only for storing the sensor data but also for integrating with the bridge model to support other functions, such as management, maintenance and inspection. The focus of this study is on the effective data management of bridge information and sensor data, which is crucial to structural health monitoring and life cycle management of bridge structures. We review the state-of-the-art of bridge information modeling and sensor data management, and propose a data management framework for bridge monitoring based on NoSQL database technologies that have been shown useful in handling high volume, time-series data and to flexibly deal with unstructured data schema. Specifically, Apache Cassandra and Mongo DB are deployed for the prototype implementation of the framework. This paper describes the database design for an XML-based Bridge Information Modeling (BrIM) schema, and the representation of sensor data using Sensor Model Language (SensorML). The proposed prototype data management framework is validated using data collected from the Yeongjong Bridge in Incheon, Korea.

  4. Review of Energy Harvesters Utilizing Bridge Vibrations

    Directory of Open Access Journals (Sweden)

    Farid Ullah Khan

    2016-01-01

    Full Text Available For health monitoring of bridges, wireless acceleration sensor nodes (WASNs are normally used. In bridge environment, several forms of energy are available for operating WASNs that include wind, solar, acoustic, and vibration energy. However, only bridge vibration has the tendency to be utilized for embedded WASNs application in bridge structures. This paper reports on the recent advancements in the area of vibration energy harvesters (VEHs utilizing bridge oscillations. The bridge vibration is narrowband (1 to 40 Hz with low acceleration levels (0.01 to 3.8 g. For utilization of bridge vibration, electromagnetic based vibration energy harvesters (EM-VEHs and piezoelectric based vibration energy harvesters (PE-VEHs have been developed. The power generation of the reported EM-VEHs is in the range from 0.7 to 1450000 μW. However, the power production by the developed PE-VEHs ranges from 0.6 to 7700 μW. The overall size of most of the bridge VEHs is quite comparable and is in mesoscale. The resonant frequencies of EM-VEHs are on the lower side (0.13 to 27 Hz in comparison to PE-VEHs (1 to 120 Hz. The power densities reported for these bridge VEHs range from 0.01 to 9539.5 μW/cm3 and are quite enough to operate most of the commercial WASNs.

  5. Gust loading on streamlined bridge decks

    DEFF Research Database (Denmark)

    Larose, Guy; Mann, Jakob

    1998-01-01

    The current analytical description of the buffeting action of wind on long-span bridges is based on the strip assumption. However, recent experiments on closed-box girder bridge decks have shown that this assumption is not valid and is the source of an important part of the error margin of the an......The current analytical description of the buffeting action of wind on long-span bridges is based on the strip assumption. However, recent experiments on closed-box girder bridge decks have shown that this assumption is not valid and is the source of an important part of the error margin...

  6. 柱式桥台前坡改造数值分析与现场检测%Study on buried abutment slope transformation based on numerical simulation and site detections

    Institute of Scientific and Technical Information of China (English)

    朱登元; 姚占勇; 葛守仁

    2015-01-01

    In order to get more traffic clearance under bridge during the road upgrading transformation,an internal and external reinforcement program was proposed to the underpass grade separation.The internal program was the soil rein-forcement by the Soletanche method to active pressure soil and passive pressure soil of the abutment,and the external program was the anchored retaining wall by tie rods.Based on Abaqus6. 10,the nonlinear FEM software,a 3D elastic-plastic numeric model was built to simulate the transformation process from buried abutment slope to anchored retaining wall.Two kinds of the construction processes were simulated,one was the slope soil excavation in layer vertically only and the other was in section horizontally and in layer vertically,and the soil reinforcement area was determined.Based on site detections to the top displacement and the bolt tension force of the retaining wall,stability analysis during the soil excavation and the wall construction were done,and the anchor pull test was carried out.The results indicated that the stability factor of the slope soil excavation program in layer vertically was 1. 61,while the program in layer vertically and in section horizontally was 1. 84,and the latter program was better.The top displacement of the wall increased mainly during the construction process,and the tension forces of the bolt did not change suddenly,and the wall and the soil behind the wall were stable.The soil reinforcement by the Soletanche method could enhance the soil shear strength and the resistance to deformation,and there was no collapse,fall,and slip during the construction process.%为了增加桥下被交道路的通行空间,采取袖阀管劈裂注浆加固柱式桥台台后主动压力区土体及台前被动压力区土体,并在分段分级挖除台前填土过程中增设锚杆钢筋混凝土挡墙的内外部双重加固措施;采用Abaqus6.10非线性分析软件,建立柱式桥台前坡加固改造的三维弹塑

  7. 49 CFR 237.101 - Scheduling of bridge inspections.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Scheduling of bridge inspections. 237.101 Section... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.101 Scheduling of bridge inspections. (a) Each bridge management program shall include a provision for scheduling...

  8. Finite element of multilayer surfacing systems on orthotropic steel bridges

    NARCIS (Netherlands)

    Li, J.; Liu, X.; Scarpas, A.; Tzimiris, G.

    2013-01-01

    Light weight orthotropic steel bridge decks have been widely utilized for bridges in seismic zones, movable bridges and long span bridges. In the last three decades, severe problems were reported in relation to asphaltic surfacing materials on orthotropic steel deck bridges. Earlier investigations h

  9. The Bridge of Mandolin County

    Science.gov (United States)

    Lantz, Juliette M.; Feindt, Jenny E.; Lewellyn, Eric P. B.; Walczak, Mary M.

    1999-12-01

    The Bridge of Mandolin County is a case designed to teach the general chemistry principles of molar mass, ions and aqueous reactions, solubility rules, and inorganic nomenclature. Through the instructor-facilitated class discussion, students consider the options before the Mandolin Town Council regarding deicing the newly constructed bridge connecting Mandolin with a large nearby city. The students must decipher contradictory claims made on behalf of sodium chloride, the traditional deicer, and calcium magnesium acetate, a new environmentally friendly deicer, to arrive at the most cost-effective and environmentally appropriate deicing product. As they work through the analysis they raise questions that can be addressed in a laboratory setting. Four optional role-playing experiments are included, which can be used by the students to gather information helpful to resolution of the case. The case is intended to be used over two class periods, with a laboratory period in between, though suggestions for other models are provided. Laboratory procedures include an EDTA titration for Ca2+ and Mg2+, a gravimetric analysis, a qualitative examination of ions and solubility, an introduction to freezing point depression and measurement, and an experimental design activity. This case can also successfully be used without alteration in non-majors chemistry or environmental chemistry courses, or upper-level analytical or environmental chemistry courses.

  10. Clinical research on abutment gingivitis and secondary caries after partial centure fixing%固定义齿修复后基牙牙龈炎、继发龋的临床观察

    Institute of Scientific and Technical Information of China (English)

    徐频频; 林燕; 麻广丽; 周国锋

    2014-01-01

    目的:观察固定义齿修复后基牙牙龈炎与继发龋的临床表现,对比两种疾病的牙周指标。方法选取本院口腔科接受固定义齿修复的患者共50例:25例患者接受治疗后发生基牙牙龈炎,设定为A组;25例患者接受治疗后发生继发龋,设定为B组,对比两组患者的菌斑指数、社区牙周治疗需要指数、探诊深度以及菌斑细菌分布。结果 A组与B组患者的菌斑指数、社区牙周治疗需要指数、探诊深度差异无统计学意义,A组与B组的菌斑细菌分布差异有统计学意义(P<0.05)。结论固定义齿修复后基牙牙龈炎与继发龋的发生率较高,基牙牙龈炎与继发龋患者的牙周指标无显著差异,因此医生应注重患者固定义齿修复后的健康宣教,以降低牙周疾病的发生率。%Objective To observe the clinical manifestation of abutment gingivitis and secondary caries after partial denture fixing,and to have a comparison of periodontal index between abutment gingivitis and secondary caries. Meth-ods Fifty patients who received partial denture fixing were divided randomly into two groups.Twenty-five patients had abutment gingivitis,and twenty-five patients had secondary caries. The PLI,CPITN,PD and the classification of bacte-rial of two groups were compared. Results The PLI,CPITN,PD of both groups had no difference,but the classification of bacterial in both groups were significantly different (P<0.05). Conclusion The incidence of abutment gingivitis and secondary caries after partial denture fixing is massive. Although the periodontal index between patients who had abut-ment gingivitis or secondary caries after partial denture fixing have no difference. Doctors should strengthen the health education after treatment to reduce the rate of periodontal disease.

  11. Level II scour analysis for Bridge 57 (BRIDTH00650057) on Town Highway 65, crossing Broad Brook, Bridgewater, Vermont

    Science.gov (United States)

    Ayotte, Joseph D.; Olson, Scott A.

    1996-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure BRIDTH00650057 on Town Highway 65 crossing Broad Brook, Bridgewater, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I study is included in Appendix E of this report. A Level I study provides a qualitative geomorphic characterization of the study site. Information on the bridge, available from VTAOT files, was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the Green Mountain physiographic province of central Vermont in the town of Bridgewater. The 26.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the US left bank is forested; DS left bank is shrub and brushland; US right bank is lawn and the DS right bank has very little vegetation and is largely coincident with the Ottauquechee River. In the study area, Broad Brook has an incised channel with a slope of approximately 0.0067 ft/ft, an average channel top width of 60 ft and an average channel depth of 3 ft. The predominant channel bed material is gravel (D50 is 46.2 mm or 0.151 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 25, 1994, indicated that the reach was stable. The Town Highway 65 crossing of Broad Brook is a 47-ft-long, one-lane bridge consisting of one 44-ft steel-beam span with a timber deck, supported by vertical concrete abutments with wingwalls on the upstream and downstream sides (Vermont Agency of Transportation, written commun., August, 1994). The US right wingwall and road approach is protected by stone fill. The US and DS right wingwalls and the right abutment are reported as having 1.0 to 1.5 ft of scour at the time of the Level one assessment on 10/25/94. Erosion from road wash affects all

  12. 33 CFR 165.1187 - Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay...

    Science.gov (United States)

    2010-07-01

    ... from the surface to the sea floor, within 25 yards of all piers, abutments, fenders and pilings of the...) Regulations. (1) In accordance with the general regulations in § 165.33 of this part, entry into...

  13. Bridge Lock-up Device System

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    The Colebrand Lock-up Device (LUD) provides additional substructure strength to resist seismic forces as a structural shock transmission unit for highway bridges. This system can provide a temporary rigid link between bridge structural members under seismic, braking, or other fast-acting type loads, while permitting slow thermal movements.

  14. Paul Dirac:. Building Bridges of the Mind

    Science.gov (United States)

    Brown, Laurie M.

    2003-12-01

    Paul Dirac was a brilliant and original thinker. He used his physical intuition and his ideal of mathematical beauty to construct bridges between major areas of physics. This article discusses several such important works, including the bridge between quantum mechanics and relativity that led to his prediction of the existence of antimatter.

  15. History of cable-stayed bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1999-01-01

    The principle of supporting a bridge deck by inclined tension members leading to towers on either side of the span has been known for centuries. However, the real development of cable-stayed bridges did not begin before the 1950s. Since then the free span has been increased from 183 m in the Strö...

  16. COUPLING VIBRATION OF VEHICLE-BRIDGE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    陈炎; 黄小清; 马友发

    2004-01-01

    By applying the sinusoidal wave mode to simulate the rugged surface of bridge deck,accounting for vehicle-bridge interaction and using Euler-Bernoulli beam theory, a coupling vibration model of vehicle-bridge system was developed. The model was solved by mode analyzing method and Runge-Kutta method, and the dynamic response and the resonance curve of the bridge were obtained. It is found that there are two resonance regions, one represents the main resonance while the other the minor resonance, in the resonance curve. The influence due to the rugged surface, the vibration mode of bridge, and the interaction between vehicle and bridge on vibration of the system were discussed. Numerical results show that the influence due to these parameters is so significant that the effect of roughness of the bridge deck and the mode shape of the bridge can't be ignored and the vehicle velocity should be kept away from the critical speed of the vehicle.

  17. A STUDY OF BARRIERS IN BRIDGING COMMUNICATION

    OpenAIRE

    Niteen V. Dandekar

    2014-01-01

    The main objective of this paper is to make a thought provoking discussion on the role barriers in bridging communication. It focuses on the concept of communication, process and the role of language related barriers in bridging communication. It studies the significance of communication in modern human life.

  18. General framework for bridge life cycle design

    Institute of Scientific and Technical Information of China (English)

    Junhai MA; Airong CHEN; Jun HE

    2009-01-01

    Based on a detailed illustration for bridge life cycle design which comprises the processes of service life design, aesthetics design, performance design, environ-mental and ecological design, inspection, maintenance and repair design as well as cost analysis, this paper presented a general framework for bridge life cycle design comprising three design phases and six design processes.

  19. Active aerodynamic stabilisation of long suspension bridges

    DEFF Research Database (Denmark)

    Nissen, Henrik Ditlev; Sørensen, Paul Haase; Jannerup, Ole Erik

    2004-01-01

    The paper describes the addition of actively controlled appendages (flaps) attached along the length of the bridge deck to dampen wind-induced oscillations in long suppension bridges. A novel approach using control systems methods for the analysis of dynamic stability is presented. In order to ma...

  20. Lifetime Reliability Assessment of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed...

  1. Re-Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper two aspects of re-assessment of the reliability of concrete bridges are discussed namely modelling of the corrosion of reinforcement and updating of uncertain variables. The main reason for deterioration of concrete bridges is corrosion of the reinforcement. Therefore, modelling...

  2. Optimum Maintenance Strategies for Highway Bridges

    DEFF Research Database (Denmark)

    Frangopol, Dan M.; Thoft-Christensen, Palle; Das, Parag C.;

    As bridges become older and maintenance costs become higher, transportation agencies are facing challenges related to implementation of optimal bridge management programs based on life cycle cost considerations. A reliability-based approach is necessary to find optimal solutions based on minimum ...... is described. The end result of this investigation will be a general reliability-based framework to be used by the UK Highways Agency in order to plan optimal strategies for the maintenance of its bridge network so as to optimize whole-life costs....... expected life-cycle costs or maximum life-cycle benefits. This is because many maintenance activities can be associated with significant costs, but their effects on bridge safety can be minor. In this paper, the program of an investigation on optimum maintenance strategies for different bridge types...

  3. The I-35W bridge Project Website

    DEFF Research Database (Denmark)

    Kampf, Constance

    How can websites be used to rebuild trust?  In August 2007, the Interstate Highway 35-W bridge in Minneapolis, MN collapsed during rush hour.  Although many people were rescued and casualties were as limited as could be expected due to quick and effective intervention, the image of a major bridge...... collapsing during rush hour damaged the Minnesota Department of Transportation's reputation and resulted in the loss of public trust for the organization.  The ensuing bridge reconstruction project included a project website intended to rebuild this trust through transparency, community involvement......, and the use of multimodal features.  This paper looks at the I35-W bridge reconstruction project in Minneapolis through web-based communication by the Minnesota Department of Transportation (MnDOT) about the project. The MnDOT bridge reconstruction website will be examined using a combination of 1). Weick...

  4. Modified Geometry of Transition Slabs for Integral Bridges

    OpenAIRE

    Dreier, Damien

    2010-01-01

    Over the past decades, an increasing number of integral bridges have been built. This type of bridge offers various advantages in comparison with standard bridges equipped with expansion joints and bearings. In particular, integral bridges require less maintenance since they require less mechanical elements. Transition slabs, which are used in integral bridges, are directly connected to the bridge deck and therefore they are subjected to large displacements caused by creep, shrinkage and temp...

  5. Building bridges … and accelerators

    CERN Multimedia

    2009-01-01

    Lyn Evans, the LHC project leader, was awarded an honorary doctorate from the University of Geneva (UNIGE) to celebrate his role not just in building accelerators, but also in building bridges between nations. He was one of four notables honoured at the event on Friday 5 June, coinciding with the University’s 450th Anniversary. Lyn Evans arriving at the ceremony with Archbishop Desmond Tutu. "It was a big surprise when I found out I’d been nominated," recounts Evans, "but it was an even bigger surprise to find out with whom I’d been nominated". At the ceremony Evans was awarded the honorary doctorate along with three others: Archbishop Desmond Tutu, who was acclaimed for his fight against apartheid in South Africa, Mary Robinson, first woman president of Ireland and former United Nations’ high commissioner of human rights, and Pascal Lamy, Director-General of the World Trade Organization. The award ceremony, known as the �...

  6. Root coverage with bridge flap

    Directory of Open Access Journals (Sweden)

    Pushpendra Kumar Verma

    2013-01-01

    Full Text Available Gingival recession in anterior teeth is a common concern due to esthetic reasons or root sensitivity. Gingival recession, especially in multiple anterior teeth, is of huge concern due to esthetic reasons. Various mucogingival surgeries are available for root coverage. This case report presents a new bridge flap technique, which allows the dentist not only to cover the previously denuded root surfaces but also to increase the zone of attached gingiva at a single step. In this case, a coronally advanced flap along with vestibular deepening technique was used as root coverage procedure for the treatment of multiple recession-type defect. Here, vestibular deepening technique is used to increase the width of the attached gingiva. The predictability of this procedure results in an esthetically healthy periodontium, along with gain in keratinized tissue and good patient′s acceptance.

  7. Factors associated with fixed partial denture abutment gingivitis and secondary caries%固定义齿基牙牙龈炎继发龋菌斑因素的研究

    Institute of Scientific and Technical Information of China (English)

    李文晋; 李瑛; 牛金亮; 金慧兰; 王涛; 刘艳

    2011-01-01

    Objective To investigate the factors associated with fixed partial denture abutment gingivitis and secondary caries.Methods Forty patients with gingivitis or secondary caries after fixed partial denture abutment were included in this study, comprising 57 abutment teeth in all (42 with gingivitis and 15 with secondary caries).The peridontal index of abutment tooth, the severity of secondmry caries and constituent ratio of dental plaques were investigated and compared between the two conditions.Results Peridontal index was comparable between patients with abutment gingivitis and those with secondary caries (P>0.05).The constituent ratio of Staphylococci in dental plaque was significantly higher in secondary caries than in abutment gingivitis, while the constituent ratios of Spirochaetes, Fusobocterium and Eubacterium was lower in secondary caries than in abutment gingivitis (P<0.05).Conclusion It is as equally important to protect abutment peridontal tissue after treatment.Patients should be educated to keep good oral cavity hygiene and regular clinic visit in order to reduce gingivitis and secondary caries.%目的 通过对固定义齿修复后基牙牙龈炎、继发龋的观察,分析基牙牙龈炎、继发龋与牙周组织及菌斑的关系.方法 收集固定义齿修复后出现牙龈炎、继发龋的病例40例,共57颗固定义齿修复体,其中基牙牙龈炎42颗,继发龋15颗.观察基牙的牙周指数、继发龋坏的情况以及菌斑细菌构成比.结果 基牙牙龈炎组与继发龋组的牙周指数差异无统计学意义(P>0.05).基牙继发龋组牙菌斑中球菌的构成比高于基牙牙龈炎组,螺旋体、梭形杆菌和真杆菌的构成比低于基牙牙龈炎组,差异有统计学意义(P<0.05).结论 固定义齿修复后牙周组织的保护同样很重要.固定义齿修复后要对患者进行口腔卫生宣教,指导患者注意保持口腔卫生,定期复诊,以减少牙龈炎、继发龋的发生.

  8. 桥梁工程速凝膏浆帷幕注浆的应用%Application of Quick Setting Slurry Curtain Grouting in Bridge Engineering

    Institute of Scientific and Technical Information of China (English)

    裴野

    2014-01-01

    The eastern main tower abutment of Egongyan tra- ck bridge of Chongqing rail link is located in the Yangtze River. The Yangtze River has great peak height is in low water period and high water period, and the distance between main tower caps and old Egongyan highway bridge pile cap is only 16.1m, so it cannot use blasting. In order to solve this problem, this paper established the construction scheme. The results showed the effect is good.%重庆市轨道环线鹅公岩轨道专用桥东岸主塔承台顶面常年位于长江江面以下,且长江枯水期和丰水期洪峰高差极大,主塔承台与老鹅公岩公路桥承台间距才16.1 m,不能使用爆破。为解决此问题,本文制定了施工方案。结果显示,实施效果良好。

  9. 采动剧烈垮冒煤巷的支承压力分布规律研究%Study on Abutment Pressure Distribution Law in Collapse Coal Roadway with Mining-induced Violently

    Institute of Scientific and Technical Information of China (English)

    李开晴; 何富连; 严红; 韩红强

    2011-01-01

    针对阳煤集团新元公司采动剧烈的垮冒煤巷普遍存在顶板严重下沉、巷帮严重臌帮和巷道底鼓等问题,对煤柱支承压力进行了现场实测和计算机三维数值模拟,分析研究采动剧烈影响下的煤巷支承压力分布规律,得出应力集中系数平均值达3.2及煤巷支承压力的分布范围,从而为采动剧烈垮冒煤巷的支护方案设计提供科学依据。%Aiming at the problems such as roof severe subsidence,the ribs of roadway ingression and floor heave in roadway of Yangguan coal industry Co.Ltd Xinyuan corporation,abutment pressure of coal pillars are analyzed by field measurements and 3D numerical simulation to research on the distribution law of abutment pressure in the mining-induced violently collapse coal roadway.The average value of stress concentration factor is 3.2,and the abutment distribution scale is obtained.These results can supply the scientific basis for the supporting scheme design.

  10. Oscillations in a sunspot with light bridges

    CERN Document Server

    Yuan, Ding; Huang, Zhenghua; Li, Bo; Su, Jiangtao; Yan, Yihua; Tan, Baolin

    2014-01-01

    Solar Optical Telescope onboard Hinode observed a sunspot (AR 11836) with two light bridges (LBs) on 31 Aug 2013. We analysed a 2-hour \\ion{Ca}{2} H emission intensity data set and detected strong 5-min oscillation power on both LBs and in the inner penumbra. The time-distance plot reveals that 5-min oscillation phase does not vary significantly along the thin bridge, indicating that the oscillations are likely to originate from the underneath. The slit taken along the central axis of the wide light bridge exhibits a standing wave feature. However, at the centre of the wide bridge, the 5-min oscillation power is found to be stronger than at its sides. Moreover, the time-distance plot across the wide bridge exhibits a herringbone pattern that indicates a counter-stream of two running waves originated at the bridge sides. Thus, the 5-min oscillations on the wide bridge also resemble the properties of running penumbral waves. The 5-min oscillations are suppressed in the umbra, while the 3-min oscillations occupy...

  11. Track-Bridge Longitudinal Interaction of Continuous Welded Rails on Arch Bridge

    Directory of Open Access Journals (Sweden)

    Rong Chen

    2013-01-01

    Full Text Available Taking arch bridges, including deck, half-through, and through arch bridges (short for DAB, HTAB, and TAB as examples, mechanics analysis models of longitudinal interaction between continuously welded rails (short for CWRs and arch bridges are established. Based on the finite element method (FEM, the longitudinal interaction calculation software of CWR on arch bridges has been developed. Focusing on an HTAB, the tension, compression, and deflection conditions are calculated and analyzed. The results show that the mechanics analysis models of three types of arch bridges can truly reflect the real state of the structure; the calculation software can be used for systematic research of the CWR on arch bridge; as for HTAB, temperature difference of arch rib has a small effect on rail tension/compression, and arch bridge can be simplified as a continuous beam for rail tension/compression additional force calculation; in calculation of deflection conditions of HTAB, it is suggested that train loads are arranged on half span and full span and take the direction of load entering bridge into account. Additionally, the deflection additional force variation of CFST basket handle arch bridge is different from that of ordinary bridge.

  12. Signal and noise in bridging PCR

    Directory of Open Access Journals (Sweden)

    Thaler David S

    2002-07-01

    Full Text Available Abstract Background In a variant of the standard PCR reaction termed bridging, or jumping, PCR the primer-bound sequences are originally on separate template molecules. Bridging can occur if, and only if, the templates contain a region of sequence similarity. A 3' end of synthesis in one round of synthesis that terminates in this region of similarity can prime on the other. In principle, Bridging PCR (BPCR can detect a subpopulation of one template that terminates synthesis in the region of sequence shared by the other template. This study considers the sensitivity and noise of BPCR as a quantitative assay for backbone interruptions. Bridging synthesis is also important to some methods for computing with DNA. Results In this study, BPCR was tested over a 328 base pair segment of the E. coli lac operon and a signal to noise ratio (S/N of approximately 10 was obtained under normal PCR conditions with Taq polymerase. With special precautions in the case of Taq or by using the Stoffel fragment the S/N was improved to 100, i.e. 1 part of cut input DNA yielded the same output as 100 parts of intact input DNA. Conclusions In the E. coli lac operator region studied here, depending on details of protocol, between 3 and 30% per kilobase of final PCR product resulted from bridging. Other systems are expected to differ in the proportion of product that is bridged consequent to PCR protocol and the sequence analyzed. In many cases physical bridging during PCR will have no informational consequence because the bridged templates are of identical sequence, but in a number of special cases bridging creates, or, destroys, information.

  13. Level II scour analysis for Bridge 25 (HARDTH00420025) on Town Highway 42, crossing Lamoille River, Hardwick, Vermont

    Science.gov (United States)

    Ayotte, Joseph D.

    1996-01-01

    This report provides the results of a detailed Level II analysis of scour potential at structure HARDTH00420025 on town highway 42 crossing the Lamoille River, Hardwick, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). A Level I study is included in Appendix E of this report. A Level I study provides a qualitative geomorphic characterization of the study site. Information on the bridge available from VTAOT files was compiled prior to conducting Level I and Level II analyses and can be found in Appendix D. The site is in the Green Mountain physiographic division of north-central Vermont in the town of Hardwick. The 119-mi2 drainage area is in a predominantly rural basin. In the vicinity of the study site, the left banks are covered by pasture and (or) fields. The right bank of Lamoille River is adjacent to Vermont Route 15 near the north edge of the Lamoille River valley. In the study area, the Lamoille River has a sinuous channel with a slope of approximately 0.0004 ft/ft, an average channel top width of 89.0 ft and an average channel depth of 8.0 ft. The predominant channel bed material is sand and gravel (D50 is 22.4 mm or 0.0733 ft). In general, the banks have sparse or no woody vegetative cover and the reach was noted to be laterally unstable at the time of the Level I site visit on July 25, 1995. The Level II work was completed on 07/27/95 and the site was revisited on August 16, 1995, just after the August 5-6, 1995 flood on the Lamoille River. Findings from this follow-up visit are presented in Appendix G. The town highway 42 crossing of the Lamoille Riveris a 62-ft-long, two-lane bridge consisting of one 60-foot steel- beam span with a concrete deck, supported by vertical abutments with wingwalls on upstream and downstream sides (Vermont Agency of Transportation, written commun., August 24, 1994). The bridge is

  14. Human Errors and Bridge Management Systems

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Nowak, A. S.

    Human errors are divided in two groups. The first group contains human errors, which effect the reliability directly. The second group contains human errors, which will not directly effect the reliability of the structure. The methodology used to estimate so-called reliability distributions...... on basis of reliability profiles for bridges without human errors are extended to include bridges with human errors. The first rehabilitation distributions for bridges without and with human errors are combined into a joint first rehabilitation distribution. The methodology presented is illustrated...

  15. Building the Clinical Bridge: An Australian Success

    Directory of Open Access Journals (Sweden)

    Marianne Wallis

    2012-01-01

    Full Text Available Nursing effectiveness science includes primary, secondary, and translational, clinically focused research activities which aim to improve patient or client outcomes. It is imperative, for the successful conduct of a program of nursing effectiveness science, that a clinical bridge is established between academic and healthcare service facilities. An Australian example of the development of a robust clinical bridge through the use of jointly funded positions at the professorial level is outlined. In addition, an analysis of the practical application of Lewin’s model of change management and the contribution of both servant and transformational leadership styles to the bridge building process is provided.

  16. Building the clinical bridge: an Australian success.

    Science.gov (United States)

    Wallis, Marianne; Chaboyer, Wendy

    2012-01-01

    Nursing effectiveness science includes primary, secondary, and translational, clinically focused research activities which aim to improve patient or client outcomes. It is imperative, for the successful conduct of a program of nursing effectiveness science, that a clinical bridge is established between academic and healthcare service facilities. An Australian example of the development of a robust clinical bridge through the use of jointly funded positions at the professorial level is outlined. In addition, an analysis of the practical application of Lewin's model of change management and the contribution of both servant and transformational leadership styles to the bridge building process is provided.

  17. Maxwell Tension Supports the Water Bridge

    OpenAIRE

    Widom, A.; Srivastava, Y. N.; Swain, J.; Sivasubramanian, S.

    2008-01-01

    A cylindrical flexible cable made up of pure fluid water can be experimentally spanned across a spatial gap with cable endpoints fixed to the top edges of two glass beakers. The cable has been called a water bridge in close analogy to iron cables employed to build ordinary span bridges. A necessary condition for the construction of a water bridge is that a large electric field exists parallel to and located within the water cable. Presently, there is no accepted detailed theory which quantita...

  18. Pilot testing of a hydraulic bridge exciter

    OpenAIRE

    Andersson Andreas; Ülker-Kaustell Mahir; Borg Richard; Dymén Olivier; Carolin Anders; Karoumi Raid

    2015-01-01

    This paper describes the development of a hydraulic bridge exciter and its first pilot testing on a full scale railway bridge in service. The exciter is based on a hydraulic load cylinder with a capacity of 50 kN and is intended for controlled dynamic loading up to at least 50 Hz. The load is applied from underneath the bridge, enabling testing while the railway line is in service. The system is shown to produce constant load amplitude even at resonance. The exciter is used to experimentally ...

  19. 西南某水电站坝肩抗力体长期稳定性分析%NUMERICAL LONG-TERM STABILITY OF DAM ABUTMENT RESISTANCE BODY FOR A HYDROPOWER STATION IN SOUTHWEST CHINA

    Institute of Scientific and Technical Information of China (English)

    杨根兰; 黄润秋

    2011-01-01

    Long-term stability of dam abutment resistance body is very important for a hydropower station. The a-butment resistance body stability of complex rock mass dam under the action of water thrust is particularly important. There are widely altered rocks in the dam abutment of a hydropower station in Southwest China. On the basis of altered rock rheological property and its viscous-elastic-plastic constitutive model, the stress and deformation fields characteristics in the resistance body slope have been simulated with 3D numerical method during the reservoir operation period. The study results show that te third stress field is formed after 6months of water storage. The dam abutment resistance body is in the most dangerous situation. Local destruction between altered rock and fault may appear. According to the simulated deformation value and plastic zones after 5 years of water storage,the abutment resistance body of the whole dam is in a long-term stable state.%水电工程对坝肩抗力体长期稳定性要求极高,因此,对于复杂岩土体坝肩抗力体在水推力作用下的稳定性评价显得尤为重要.西南某水电工程坝肩岩体普遍发育有蚀变岩,因此需对其抗力体长期稳定性进行评价.根据考虑蚀变岩体流变特性的黏-弹-塑性本构模型,对水库蓄水运行期抗力体边坡应力、形变场等特征进行了三维数值模拟研究.研究表明,坝肩抗力体在蓄水6个月后“三次应力场”基本形成,即此时抗力体处于最危险状态,可能会出现蚀变岩带与断层交叉部位的局部破坏;通过对蓄水5a后模拟得到的变形值及塑性区变化情况分析,得出坝肩抗力体整体上是长期稳定的.

  20. Research progress on cantilevered resin-boned bridge%单端粘接桥的研究进展

    Institute of Scientific and Technical Information of China (English)

    张倩

    2011-01-01

    As the development of the conservative treatment, the resin-bonded bridge is a well-accepted clinical treatment to replace missing teeth, because of less tooth preparation, fewer working hours and lower cost. Recent clinical studies showed 2-unit cantilevered resin-boned bridges (CRBB) can reduce the interabutment stress and retainer debonding. Abutment selection, retention form and retainer design, metal surface treatment and luting cement are the keys to avoid the failure of CRBB. Two databases, Pubmed and China National Knowledge Infras-trudure were used to search the literatures of CRBB and investigate the effection of above factors on the longevity of CRBB, which provide the information for the clinical application of CRBB.%随着牙体保守治疗的兴起,粘接桥修复因牙体预备少、椅旁操作时间短、成本低廉等优点而广受医患的欢迎.近来的研究表明:2单位单端粘接桥可减小基牙间的应力,降低固位体的脱落率,从而获得较高的临床成功率,因而发展前景更加广泛.病例的选择、基牙固位型与固位体的设计、金属表面处理方法与粘接剂等都是影响单端粘接桥成败的关键因素.本文检索了Pubmed与中国知网数据库中的相关文章,就上述影响因素的研究现状作一综述,以供临床参考.

  1. Discussion about the Shoulderless and Local microshoulder Abutment Tooth Preparation of Full Crown Restoration%牙体牙列缺损美容修复牙体预备方法的临床探讨

    Institute of Scientific and Technical Information of China (English)

    刘建东; 刘曼丽; 周嘉洪

    2011-01-01

    Objective:In order to adapt the demand that patients who don't want to destroy their natural tooth tissue by routine method at basic hospital.To discuss the method that shouldless and local microshoulder abutment tooth preparation of full crown for retaining tissue of tooth and shorting the time of tooth preparation.Methods: 995 abutment tooth which from 490 cases have been cured by the method of shouldless and local microshoulder abutment tooth preparation by writer in 10 years from 2001 to 2010.Among the cases ,Swaged metal full crown which formed the line concave the crown edge of dental cervix but not any shoulder preparation.PFM which formed the microshoulder on the labial or buccal surface and the line concave at the proximal or lingual surface in thc abutment tooth.Results: By revisiting and observing the above-mentioned 490 cases during one to seven years.The restorations of 483 cases are all in good condition and there are no abnormality in pulp、periodontal and periapical tissue besides four cases which the local edge of porcelain veneer crown appear metallochrome lightly and three cases which appear topical stenopaic at the edge of porcelain veneer crown.There are no dental canies and breaking, the restorations have not been destroyed and moved.Conclusion:Compare the method which mentioned with the routine method can retain more tissue of tooth, accentuate the restention and resisting force of abutment tooth, shorten the time of tooth preparation and reduce the possible nuisance to tooth, gingival and paradentium during the course of abutment tooth preparation which allay patients and relief their trepidation to abutment tooth preparation.%目的:为适应基层农村患者惧怕磨牙和不愿接受常规牙体预备的要求,探讨一种微小肩台的全冠牙体预备方法,以减少因预备肩台而磨去较多牙体组织和缩短口内操作时间,减轻患者痛苦.方法:从2001年至2010年的10年时间里,共对490例患者的995颗需做

  2. Unseating Damage to Simply Supported Bridges during Wenchuan Earthquake and Design Countermeasures%汶川大地震简支梁桥落梁震害与设计对策

    Institute of Scientific and Technical Information of China (English)

    王东升; 王吉英; 孙治国; 李晓莉

    2011-01-01

    The unseating damage to simply supported bridges and their main influencing factors during the Wenchuan earthquake are summarized. It is found that excepting the earthquake-induced landslide hazard, the earthquake surface rupture, near fault ground motion, punching shear failure of the abutment breast wall, the invalidity of the devices for preventing unseating damage to the bridges and the complex bridge types are main influencing factors leading to the unseating damage to the simply supported bridges. Basic seismic design idea and method to prevent unseating damage to simply supported bridges are presented in this paper, which include: (1) sliding between bridge girders and cap beams is allowed to reduce the seismic actions concentrated on the bridge piers; (2) cap beams with enough seating length are recommended for sliding between girder and pier to avoid unseating damage; (3) shear keys or cable restrainers should be used as added measures to prevent unseating damage. The design method for simply supported bridges with cable restrainers is illustrated in detail by using current seismic design code for bridges.%总结了5· 12汶川大地震中简支梁桥落梁震害及主要影响因素,发现除地震山体滑坡等地质灾害外,断层地表破裂、近断层地震动效应、桥台胸墙冲切破坏、防落梁构造措施单一及桥梁体型复杂等因素都是引起简支梁桥落粱震害的重要原因.提出了简支梁桥防落梁设计的基本理念及相关技术方案要点为允许墩梁间发生滑移,以降低桥墩承受的地震惯性力,以及盖梁提供允许的最大滑移长度及支座支承宽度,再辅助挡块或拉索限位器等共同防止落粱发生.最后结合现行规范,以拉索限位器为例给出了简支梁桥防落梁设计方法.

  3. Allegheny County-Owned Bridges Points

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset shows the location of bridges owned by Allegheny County as centroids. If viewing this description on the Western Pennsylvania Regional Data Center’s...

  4. Allegheny County-Owned Bridges Centerlines

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset shows the bridges owned by Allegheny County. If viewing this description on the Western Pennsylvania Regional Data Center’s open data portal...

  5. Influence of Icing on Bridge Cable Aerodynamics

    DEFF Research Database (Denmark)

    Koss, Holger; Frej Henningsen, Jesper; Olsen, Idar

    2013-01-01

    In recent years the relevance of ice accretion for wind-induced vibration of structural bridge cables has been recognised and became a subject of research in bridge engineering. Full-scale monitoring and observation indicate that light precipitation at moderate low temperatures between zero and -5......°C may lead to large amplitude vibrations of bridge cables under wind action. For the prediction of aerodynamic instability quasi-steady models have been developed estimating the cable response magnitude based on structural properties and aerodynamic force coefficients for drag, lift and torsion...... forces of different bridge cables types. The experiments were conducted in a wind tunnel facility capable amongst others to simulate incloud icing conditions....

  6. Assessment of the Reliability of Concrete Bridges

    DEFF Research Database (Denmark)

    Middleton, C. R.; Thoft-Christensen, Palle

    in the wake of ever increasing traffic loads and volumes, and an ageing population of bridges subject to various mechanisms of deterioration. The goal is to optimise the allocation of limited resources whilst maintaining their bridges in a safe and serviceable condition. Reliability analysis is one tool being......Although there has been a considerable amount of research into different aspects of concrete bridge reliability, it has still not been widely adopted in professional practice other than in the development and calibration of codes. This situation appears to be changing as there has been...... adopted to assist in achieving this goal. Rather than review the specific research on this subject this paper examines a number of key issues related to the practical application of reliability analysis to the assessment of concrete bridges....

  7. Pilot testing of a hydraulic bridge exciter

    Directory of Open Access Journals (Sweden)

    Andersson Andreas

    2015-01-01

    Full Text Available This paper describes the development of a hydraulic bridge exciter and its first pilot testing on a full scale railway bridge in service. The exciter is based on a hydraulic load cylinder with a capacity of 50 kN and is intended for controlled dynamic loading up to at least 50 Hz. The load is applied from underneath the bridge, enabling testing while the railway line is in service. The system is shown to produce constant load amplitude even at resonance. The exciter is used to experimentally determine frequency response functions at all sensor locations, which serve as valuable input for model updating and verification. An FE-model of the case study bridge has been developed that is in good agreement with the experimental results.

  8. Practical Approach to Fragility Analysis of Bridges

    Directory of Open Access Journals (Sweden)

    Yasamin Rafie Nazari

    2012-12-01

    Full Text Available Damages during past earthquakes reveal seismic vulnerability of bridge structures and the necessity of probabilistic approach toward seismic performance evaluation of bridges and its interpretation in terms of decision variables such as repair cost, downtime and life loss. This Procedure involves hazard analysis, structural analysis, damage analysis and loss analysis. The purpose of present study is reviewing different methods developed to derive fragility curves for damage analysis of bridges and demonstrating a simple procedure for fragility analysis using Microsoft Office Excel worksheet to reach probability of occurring predefined level of damage due to different levels of seismic demand parameters. The input of this procedure is the intensity of ground motion and the output is an appropriate estimate of the expected damage. Different observed damages of the bridges are discussed and compared the practical definition of damage states. Different methods of fragility analyses are discussed and a practical step by step example is illustrated.

  9. Identifying hidden sexual bridging communities in Chicago.

    Science.gov (United States)

    Youm, Yoosik; Mackesy-Amiti, Mary Ellen; Williams, Chyvette T; Ouellet, Lawrence J

    2009-07-01

    Bridge populations can play a central role in the spread of human immunodeficiency virus (HIV) by providing transmission links between higher and lower prevalence populations. While social network methods are well suited to the study of bridge populations, analyses tend to focus on dyads (i.e., risk between drug and/or sex partners) and ignore bridges between distinct subpopulations. This study takes initial steps toward moving the analysis of sexual network linkages beyond individual and risk group levels to a community level in which Chicago's 77 community areas are examined as subpopulations for the purpose of identifying potential bridging communities. Of particular interest are "hidden" bridging communities; that is, areas with above-average levels of sexual ties with other areas but whose below-average AIDS prevalence may hide their potential importance for HIV prevention. Data for this analysis came from the first wave of recruiting at the Chicago Sexual Acquisition and Transmission of HIV Cooperative Agreement Program site. Between August 2005 through October 2006, respondent-driven sampling was used to recruit users of heroin, cocaine, or methamphetamine, men who have sex with men regardless of drug use, the sex partners of these two groups, and sex partners of the sex partners. In this cross-sectional study of the sexual transmission of HIV, participants completed a network-focused computer-assisted self-administered interview, which included questions about the geographic locations of sexual contacts with up to six recent partners. Bridging scores for each area were determined using a matrix representing Chicago's 77 community areas and were assessed using two measures: non-redundant ties and flow betweenness. Bridging measures and acquired immunodeficiency syndrome (AIDS) case prevalence rates were plotted for each community area on charts representing four conditions: below-average bridging and AIDS prevalence, below-average bridging and above

  10. Inspection Based Evaluation of a Danish Road Bridge

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper it is shown how an inspection-based evaluation of a Danish road bridge may be performed using the BRIDGE1 and BRIDGE2 bridge management systems produced within the EC-supported research programme "Assessment of Performance and Optimal Strategies for Inspection and Maintenance...

  11. TMACS test procedure TP012: Panalarm software bridge

    International Nuclear Information System (INIS)

    This Test Procedure addresses the testing of the functionality of the Tank Monitor and Control System (TMACS) Panalarm bridge software. The features to be tested are: Bridge Initialization Options; Bridge Communication; Bridge Performance; Testing Checksum Errors; and Testing Command Reject Errors. Only the first three could be tested; the last two have been deferred to a later date

  12. Assessment of a Bridge WIM System on Integral Concrete Bridges and on Steel Orthotropic Decks

    OpenAIRE

    Ieng, Sio Song; SCHMIDT, Franziska; ROMBONI, Frédéric; Jacob, Bernard

    2011-01-01

    Bridge-Weigh-In-Motion uses bridges as a scale to weigh vehicles. Practically, this is done by measuring the strains in that bridge, and relating them to the weight and dimensions of a truck called “calibration trucks” whose shape and axle weights are well known. This article summarizes different B-WIM experiments the institute IFSTTAR (formerly called LCPC) realized and the lessons drawn from this experience. First, the system has been tested on frame-type bridges with integral s...

  13. Experimental study of single span railway bridges

    OpenAIRE

    Rigueiro, Constança; Rebelo, C.; Silva, L. Simões da

    2007-01-01

    The main purpose of this paper is to present some results concerning the investigation that has been done by the authors regarding the dynamic response of small to médium span railway bridges using response acceleration data colleted during the measurements carried out on single span bridges on the railway track Linz-Wels, in Austria. Using output-only methods in this experimental program, it was possible to have an estimation of the igenfrequencies, mode shapes and the corresponding viscous ...

  14. Active control of vibrations in pedestrian bridges

    OpenAIRE

    Álvaro Cunha; Carlos Moutinho

    1999-01-01

    This paper, apart from making a brief general reference to vibration problems in pedestrian bridges, as well as to the form of modelling of dynamic pedestrian loads, presents the use of a predictive control strategy for the numerical simulation of the dynamic response of actively controlled structures of this type. The consideration of this control strategy permitted the development of a computational model, which was applied to the study of a pedestrian cable-stayed bridge, in order to show ...

  15. Building Organic Bridges: Volume 1, Argentina - France

    OpenAIRE

    Rahmann, Gerold; Aksoy, Uygun

    2014-01-01

    [Foreword ...] The 18th IFOAM Organic World Congress held on 13-15 October, 2014 in Istanbul-Turkey targets to 'build organic bridges'. The Scientific track will contribute to bridging not only scientists but also institutions and disciplines, and to linking more developed and less developed, rural and urban, research to extension, plant to animal, farm practices to world-wide problems and producer and consumers. Organic is a management system that requires a diversity of inputs from differen...

  16. Building Organic Bridges: Volume 2, Germany - India

    OpenAIRE

    Rahmann, Gerold; Aksoy, Uygun

    2014-01-01

    [Foreword ...] The 18th IFOAM Organic World Congress held on 13-15 October, 2014 in Istanbul-Turkey targets to 'build organic bridges'. The Scientific track will contribute to bridging not only scientists but also institutions and disciplines, and to linking more developed and less developed, rural and urban, research to extension, plant to animal, farm practices to world-wide problems and producer and consumers. Organic is a management system that requires a diversity of inputs from differen...

  17. Thermal Bridge Effects in Walls Separating Rowhouses

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report the thermal bridge effects at internal wall/roof junctions in rowhouses are evaluated. The analysis is performed using a numerical calculation programme, and different solutions are evaluated with respect to extra heat loss and internal surface temperatures.......In this report the thermal bridge effects at internal wall/roof junctions in rowhouses are evaluated. The analysis is performed using a numerical calculation programme, and different solutions are evaluated with respect to extra heat loss and internal surface temperatures....

  18. External Prestressing Bridge Reinforcement Technology Review

    Directory of Open Access Journals (Sweden)

    Zhu Hanbing

    2015-01-01

    Full Text Available Externally prestressed bridge can not only limit and reduce the cracks and deformation of the structure, improve the rigidity and bearing capacity of structure, improve the stress state of structure, but also have less interference for bridge operation when it is operating and have the good economic efficiency. This paper introduces the advantages and disadvantages of external prestressed strengthening technique, its calculation theory and construction technology described in detail, and finally the paper discusses the deficiency of existing research.

  19. Subscapularis Tendon Repair Using Suture Bridge Technique

    OpenAIRE

    Park, Yong Bok; Park, Young Eun; Koh, Kyoung Hwan; Lim, Tae Kang; Shon, Min Soo; Yoo, Jae Chul

    2015-01-01

    The subscapularis tendon plays an essential role in shoulder function. Although subscapularis tendon tears are less common than other rotator cuff tears, tears of the subscapularis tendon have increasingly been recognized with the advent of magnetic resonance imaging and arthroscopy. A suture bridge technique for the treatment of posterosuperior rotator cuff tears has provided the opportunity to improve the pressurized contact area and mean footprint pressure. However, suture bridge fixation ...

  20. Framework for Bridges Maintenance in Egypt

    Directory of Open Access Journals (Sweden)

    Hesham Abd Elkhalek

    2016-01-01

    Full Text Available The traditional approaches for bridges maintenance is proven to be inefficient as they lead to random way of spending maintenance budget and deteriorating bridge conditions. In many cases, maintenance activities are performed due to user complaints. The objective of this paper is to develop a practical and reliable framework to manage the maintenance and repair activities of Bridges network in Egypt considering performance and budget limits. The model solves an optimization problem that maximizes the average condition of the network given the limited budget using Genetic Algorithm (GA. The main tasks of the system are bridge inventory, condition assessment, deterioration using markov model, and maintenance optimization. The developed model takes into account multiple parameters including serviceability requirements, budget allocation, element importance on structural safety and serviceability, bridge impact on network, and traffic. A questionnaire is conducted to complete the research scope. The proposed model is implemented in software, which provides a friendly user interface. The results of the framework are multi – year maintenance plan for the entire network for up to five years. A case study is presented for validating and testing the model with Data collected from “General Authority for Roads, Bridges and Land Transport” in Egypt.

  1. Precast Pearl-Chain concrete arch bridges

    DEFF Research Database (Denmark)

    Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

    2015-01-01

    A Pearl-Chain Bridge is a closed-spandrel arch bridge consisting of a number of straight pre-fabricated so called Super-Light Deck elements put together in an arch shape by post-tensioning cables. Several Pearl-Chain arches can be positioned adjacent to each other by a crane to achieve a bridge...... the technology was used. We also study other important components and details in the Pearl-Chain Bridge concept and review the effects of different types of loads. A theoretical case study of a circular 30 m span Pearl-Chain Bridge is presented showing the influence of a number of parameters: The number of post......-tensioning cables, the rise to span ratio, the height of the filling, and the height of the Super-Light Decks. We find that Pearl-Chain Bridges can be adjusted to resist specific moment loads by changing the normal force in the arch cross section by altering the above parameters. It is also found that the negative...

  2. Response Modification Factors for Concrete Bridges in Europe

    OpenAIRE

    Kappos, A. J.; Paraskeva, T. S.; Moschonas, I. F.

    2013-01-01

    The paper presents a methodology for evaluating the actual response modification factors (q or R) of bridges and applies it to seven concrete bridges typical of the stock found in southern Europe. The usual procedure for analytically estimating the q-factor is through pushover curves derived for the bridge in (at least) its longitudinal and transverse directions. The shape of such curves depends on the seismic energy dissipation mechanism of the bridge; hence, bridges are assigned to two cate...

  3. Prevention of bacterial leakage at implant-abutment connection level: an in vitro study of the efficacy of three different implant systems.

    Science.gov (United States)

    Carinci, F; Lauritano, D; Cura, F; Lopez, M A; Andreasi Bassi, M; Confalone, L; Pezzetti, F

    2016-01-01

    Peri-implantitis is the main cause of implant failures. Peri-implantitis is provoked by the presence of bacterial infiltration around Implant-Abutment Connection (IAC). Reduction of bacterial leakage may be achieved by improving the accuracy and precision of the two pieces of IAC. The aim of the present in vitro study was to evaluate bacterial microleakage from the inside to the outside of the IAC, testing the efficacy of three new designs of internal conical connection (FN - nano-fix -, NQ - uNiQo - and Elisir implant systems by FMD, Rome, Italy). To identify the efficacy of three new IAC, the passage of genetically modified Escherichia coli across IAC was evaluated. A total of 17 implants were used (5 FN, 6 NQ and 6 Elisir). All implants were immerged in a bacterial culture for 48 h and bacteria amount was then measured inside and outside IAC with Real-time PCR. Bacterial quantification was performed by Real-Time Polymerase Chain Reaction using the absolute quantification with the standard curve method. In all the tested implants, bacteria were found in the inner side, with a median percentage of 1.9% FN, 1.4% NQ and 2.6% Elisir. The analysis revealed that in both cases (internally and externally), bacteria grew in the first 48 hours but subsequently started to die, probably due to nutrient consumption. Of the three, the most efficacious connection was NQ. Within the limitations of this study, it was concluded that the best implant connection reducing bacterial leakage al IAC level was NQ (NQ implant system by FMD, Rome, Italy). PMID:27469551

  4. A Novel Scheme and Evaluations on a Long-Term and Continuous Biosensor Platform Integrated with a Dental Implant Fixture and Its Prosthetic Abutment.

    Science.gov (United States)

    Li, Yu-Jung; Lu, Chih-Cheng

    2015-01-01

    A miniature intra-oral dental implant system including a built-in biosensor device is proposed in this article. The dental implant system, or platform, is replaced over maxilla and allows relatively non-invasive procedures for a novel biosensing scheme for human blood analysis. Due to placement of the implant fixture, periodontal ligaments and the pulp structure, which are regarded as the main origin of pain, are thus removed, and long-term, continuous blood analysis and management through maxillary bone marrow becomes achievable through the dental implant platform. The new pathway of biological sensing is for the first time presented to realize an accurate and painless approach without injections. The dental implant system mainly consists of an implant fixture and a prosthetic abutment, a biosensor module, a bluetooth 4.0 wireless module and a dc button cell battery. The electrochemical biosensor possesses three electrodes, including working, reference and counter ones, which are arranged to pass through the titanium implant fixture below the biosensor module. The electrodes are exposed to the blood pool inside the maxillary bone marrow and perform oxidation/reduction reactions with the coating of biosensing enzyme. To prove the proposed platform, the immobilization process of glucose oxidase (GOD) enzyme and in vitro detections of glucose levels are successfully carried out, and proven sensitivity, linearity and repeatability of the glucose biosensor system are obtained. Moreover, a preliminary canine animal model adopting the new pathway shows significant consistency with the traditional method through dermal pricks for blood sugar detection. Despite the prospective results, further challenges in engineering implementation and clinical practices are addressed and discussed. In brief, the novel biosensing pathway and intra-oral biosensor platform may increasingly reveal their promising value and feasibilities in current bio-medical analysis, diagnosis, drug

  5. A Novel Scheme and Evaluations on a Long-Term and Continuous Biosensor Platform Integrated with a Dental Implant Fixture and Its Prosthetic Abutment

    Directory of Open Access Journals (Sweden)

    Yu-Jung Li

    2015-09-01

    Full Text Available A miniature intra-oral dental implant system including a built-in biosensor device is proposed in this article. The dental implant system, or platform, is replaced over maxilla and allows relatively non-invasive procedures for a novel biosensing scheme for human blood analysis. Due to placement of the implant fixture, periodontal ligaments and the pulp structure, which are regarded as the main origin of pain, are thus removed, and long-term, continuous blood analysis and management through maxillary bone marrow becomes achievable through the dental implant platform. The new pathway of biological sensing is for the first time presented to realize an accurate and painless approach without injections. The dental implant system mainly consists of an implant fixture and a prosthetic abutment, a biosensor module, a bluetooth 4.0 wireless module and a dc button cell battery. The electrochemical biosensor possesses three electrodes, including working, reference and counter ones, which are arranged to pass through the titanium implant fixture below the biosensor module. The electrodes are exposed to the blood pool inside the maxillary bone marrow and perform oxidation/reduction reactions with the coating of biosensing enzyme. To prove the proposed platform, the immobilization process of glucose oxidase (GOD enzyme and in vitro detections of glucose levels are successfully carried out, and proven sensitivity, linearity and repeatability of the glucose biosensor system are obtained. Moreover, a preliminary canine animal model adopting the new pathway shows significant consistency with the traditional method through dermal pricks for blood sugar detection. Despite the prospective results, further challenges in engineering implementation and clinical practices are addressed and discussed. In brief, the novel biosensing pathway and intra-oral biosensor platform may increasingly reveal their promising value and feasibilities in current bio-medical analysis

  6. Role of multiprotein bridging factor 1 in archaea: bridging the domains?

    NARCIS (Netherlands)

    Koning, de B.; Blombach, F.; Wu Hao,; Brouns, S.J.J.; Oost, van der J.

    2009-01-01

    MBF1 (multiprotein bridging factor 1) is a highly conserved protein in archaea and eukaryotes. It was originally identified as a mediator of the eukaryotic transcription regulator BmFTZ-F1 (Bombyx mori regulator of fushi tarazu). MBF1 was demonstrated to enhance transcription by forming a bridge bet

  7. Micromechanical model of cross-over fibre bridging - Prediction of mixed mode bridging laws

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Gamstedt, E.K.; Østergaard, Rasmus Christian;

    2008-01-01

    The fracture resistance of fibre composites can be greatly enhanced by crack bridging. In situ observations of mixed mode crack growth in a unidirectional carbon-fibre/epoxy composite reveal crack bridging by single fibres and by beam-like ligaments consisting of several fibres. Based on the obse...

  8. Comprehensive Real-Time Bridge Health Monitoring System of Tongtai Bridge

    Directory of Open Access Journals (Sweden)

    Lei Su-su

    2015-01-01

    Full Text Available Tongtai Bridge is the world’s largest suspension curve-girder-skew-arch bridge, which is located in Zhangjiakou, China. The understanding of mechanics characteristics is limited to such complex bridges, so it is necessary to establish reliable health monitoring system to investigate the static and dynamic responses and monitor the safety of the bridge. A comprehensive real-time bridge health monitoring system is establish, which includes four aspects: sensor system, data acquisition and transmission system, data processing and control system, structure early warning and security assessment system. The paper systematically describes the system design principles, sensor layout, and monitoring content, then expounds system integration and function of each subsystem.

  9. A probabilistic bridge safety evaluation against floods.

    Science.gov (United States)

    Liao, Kuo-Wei; Muto, Yasunori; Chen, Wei-Lun; Wu, Bang-Ho

    2016-01-01

    To further capture the influences of uncertain factors on river bridge safety evaluation, a probabilistic approach is adopted. Because this is a systematic and nonlinear problem, MPP-based reliability analyses are not suitable. A sampling approach such as a Monte Carlo simulation (MCS) or importance sampling is often adopted. To enhance the efficiency of the sampling approach, this study utilizes Bayesian least squares support vector machines to construct a response surface followed by an MCS, providing a more precise safety index. Although there are several factors impacting the flood-resistant reliability of a bridge, previous experiences and studies show that the reliability of the bridge itself plays a key role. Thus, the goal of this study is to analyze the system reliability of a selected bridge that includes five limit states. The random variables considered here include the water surface elevation, water velocity, local scour depth, soil property and wind load. Because the first three variables are deeply affected by river hydraulics, a probabilistic HEC-RAS-based simulation is performed to capture the uncertainties in those random variables. The accuracy and variation of our solutions are confirmed by a direct MCS to ensure the applicability of the proposed approach. The results of a numerical example indicate that the proposed approach can efficiently provide an accurate bridge safety evaluation and maintain satisfactory variation. PMID:27386269

  10. Natural vibration dynamics of Rainbow Bridge, Utah

    Science.gov (United States)

    Moore, J. R.; Thorne, M. S.; Wood, J. R.; Doyle, S.; Stanfield, E.; White, B.

    2015-12-01

    We measured resonant frequencies of Rainbow Bridge, Utah, one of the world's longest rock spans, during a field experiment recording ambient vibration data. Measurements were generated over 20 hours on March 23-24, 2015 using two broadband three-component seismometers placed on the bridge, and compared to concurrent data from nearby reference stations 20 and 220 m distant. We identified seven distinct modes of vibration for Rainbow Bridge between 1 and 6 Hz. Data for each resonant frequency was then analyzed to determine the frequency-dependent polarization vector in an attempt to clarify mode shapes; e.g. the fundamental mode represents out-of-plane horizontal flexure. We compared experimental data to results of 3D numerical modal analysis, using a new photogrammetric model of Rainbow Bridge generated in this study imported into COMSOL Multiphysics. Results compare well with measured data for seven of the first eight modeled modes, matching vibrational frequencies and polarization orientations generally within 10%. Only predicted mode 6 was not explicitly apparent in our experimental data. Large site-to-reference spectral ratios resolved from experimental data indicate high amplification on the bridge as compared to nearby bedrock.

  11. Bridges in the random-cluster model

    Directory of Open Access Journals (Sweden)

    Eren Metin Elçi

    2016-02-01

    Full Text Available The random-cluster model, a correlated bond percolation model, unifies a range of important models of statistical mechanics in one description, including independent bond percolation, the Potts model and uniform spanning trees. By introducing a classification of edges based on their relevance to the connectivity we study the stability of clusters in this model. We prove several exact relations for general graphs that allow us to derive unambiguously the finite-size scaling behavior of the density of bridges and non-bridges. For percolation, we are also able to characterize the point for which clusters become maximally fragile and show that it is connected to the concept of the bridge load. Combining our exact treatment with further results from conformal field theory, we uncover a surprising behavior of the (normalized variance of the number of (non-bridges, showing that it diverges in two dimensions below the value 4cos2⁡(π/3=0.2315891⋯ of the cluster coupling q. Finally, we show that a partial or complete pruning of bridges from clusters enables estimates of the backbone fractal dimension that are much less encumbered by finite-size corrections than more conventional approaches.

  12. 可摘局部义齿基牙健康状况的临床观察%Clinic observation on abutment teeth healthily status with the patients wearing removable partial denture

    Institute of Scientific and Technical Information of China (English)

    孙迎春; 高平; 张恩; 陶伟

    2001-01-01

    Objective: To compare the effect of different factors (1) oral hygiene habits (2)designs of dentures (3)material of dentures on abutment teeth of removable partial dentures (RPDs). Methods: Abutment teeth healthily of examined patients status after they had worn RPDs two years with index about the caries, periodontal and oral hygiene habits . Their results were analyzed with χ2 statistics. Results:The patients oral hygiene habits and different designs of dentures are close relation with abutment teeth healthily status but different material of dentures is not significantly. Conclusion: The abutment teeth healthily status are relativei with many factors, but oral hygiene is a most important factor.%目的:对比患者不同的口腔卫生习惯、不同的义齿设计、不同的义齿材料等,以分析可摘局部义齿(RPDs)[摘要]目的:对比患者不同的口腔卫生习惯、不同的义齿设计、不同的义齿材料等,以分析可摘局部义齿(RPDs)对口腔微生态的影响。方法:在病人戴入RPDs 2a后,用龋病、牙周病常用指数及口腔卫生指数,来检查基牙健康状况,用χ2检验分析它们之间的结果有无差异。结果:患者的口腔卫生习惯、义齿的不同设计、均与基牙健康密切相关。而两种不同材料的义齿对基牙的损坏无显著性差异。结论:RPDs基牙的健康与多因素有关,而口腔卫生状况是决定RPDs口腔微生态的重要因素。

  13. Fast Hough transform for automatic bridge extraction

    Science.gov (United States)

    Hao, Qiwei; Chen, Xiaomei; Ni, Guoqiang; Zhang, Huaili

    2008-03-01

    In this paper, a new method to recognize bridge in the complicated background is presented. The algorithm takes full advantages of the characteristics of the bridge image. Firstly, the image is preprocessed and the object edges are extracted. Then according to the limitations of traditional Hough transform (HT), the extraction method of the image line segment characteristic of HT is improved, which eliminates spurious peaks on the basis of global and local thresholds, discriminates the position relation between two straight line segments, and merges segments with near endpoints, etc. Experiments show that this algorithm is more precise and efficient than traditional HT, moreover it can provide a complete description of the bridge in a complicated background.

  14. MINERAL BRIDGES OF NACRE AND ITS EFFECTS

    Institute of Scientific and Technical Information of China (English)

    宋凡; 白以龙

    2001-01-01

    Nacre, or mother-of-pearl, is a kind of composites of aragonite platelets sandwiched between organic materials. Its excellent mechanical properties are thought to stem from the microarchitecture that is traditionally described as a "brick and mortar" arrangement. In this paper, a new microstructure, referred to as mineral bridge in the biomineralization, is directly observed in the organic matrix layers (mortar) of nacre. This is an indication that the organic matrix layer of nacre should be treated as a three-dimensional interface and the microarchitecture of nacre ought to be considered as a "brick-bridge-mortar" structure rather than the traditional one. Experiments and analyses show that the mineral bridges not only improve the mechanical properties of the organic matrix layers but also play an important role in the pattern of the crack extension in nacre.

  15. MULTIPHASE BLASTING OF THE BRIDGE ACROSS THE DRENICA RIVER

    OpenAIRE

    Branko Božić

    1989-01-01

    The construction of new bridges on the sites of the existing ones require demolition of the old bridge. Due to closeness of newly erected bridge elements the fundations of old bridges are demolished by multiphase blasting process. The blasting of the piers and anchorages of the bridge across 'the Drenica river carrying the Balačevac—Goleš industrial railway was done in four phases. The piers and anchorages of a new bridge and its construction elements have been erected before (the paper is pu...

  16. Bridging radiation policy and science

    International Nuclear Information System (INIS)

    Scientists, regulators, and policy makers from five continents and 20 countries reached consensus on a number of conclusions and recommendations regarding low-level ionizing radiation exposures at an international conference, 'Bridging Radiation Policy and Science,' at the Airlie Center in Warrenton, Virginia, 1-5 December 1999. The goal of the conference was to develop strategies for formulating national and international policy based on current scientific information in the context of economic, political, and social concerns. Specifically, attendees explored how to establish public policies with respect to radiation protection in view of the scientific uncertainties of the effects of low-level radiation [<100 millisievert (mSv)]. Conference participants agreed that science will not likely answer in the near future fundamental questions about the shape of the dose-response curve and mechanisms of effects of radiation at low doses. The conference endorsed the quest for a prudent and coherent radiation policy based on the International Atomic Energy Agency's (IAEA) 'evolving global framework'. The Conference participants agreed upon the following recommendations: Policy discussions on the regulation of radiation sources delivering low-level radiation should include references to natural background radiation. The conference supports the evolving global framework of the International Atomic Energy Agency (IAEA) for the safe use of radiation. The conference supports further development and evaluation of the ideas associated with the proposal on controllable dose. No radiation dose is below regulatory concern but certain levels should be below regulatory action, and appropriate dose levels should be established. Fundamental questions about the shape of the dose-response curve and mechanisms of effects of radiation at low doses are unlikely to be answered in the near future. Scientific research, including molecular and cellular radiobiology studies are critical in order

  17. Extracorporeal Life Support Bridge to Ventricular Assist Device: The Double Bridge Strategy.

    Science.gov (United States)

    Marasco, Silvana F; Lo, Casey; Murphy, Deirdre; Summerhayes, Robyn; Quayle, Margaret; Zimmet, Adam; Bailey, Michael

    2016-01-01

    In patients requiring left ventricular assist device (LVAD) support, it can be difficult to ascertain suitability for long-term mechanical support with LVAD and eventual transplantation. LVAD implantation in a shocked patient is associated with increased morbidity and mortality. Interest is growing in the utilization of extracorporeal life support (ECLS) as a bridge-to-bridge support for these critically unwell patients. Here, we reviewed our experience with ECLS double bridging. We hypothesized that ECLS double bridging would stabilize end-organ dysfunction and reduce ventricular assist device (VAD) implant perioperative mortality. We conducted a retrospective review of prospectively collected data for 58 consecutive patients implanted with a continuous-flow LVAD between January 2010 and December 2013 at The Alfred Hospital, Melbourne, Victoria, Australia. Twenty-three patients required ECLS support pre-LVAD while 35 patients underwent LVAD implantation without an ECLS bridge. Preoperative morbidity in the ECLS bridge group was reflected by increased postoperative intensive care duration, blood loss, blood product use, and postoperative renal failure, but without negative impact upon survival when compared with the no ECLS group. ECLS stabilization improved end-organ function pre-VAD implant with significant improvements in hepatic and renal dysfunction. This series demonstrates that the use of ECLS bridge to VAD stabilizes end-organ dysfunction and reduces VAD implant perioperative mortality from that traditionally reported in these "crash and burn" patients.

  18. The seismic response of concrete arch bridges (with focus on the Bixby Creek bridge Carmel, California)

    Energy Technology Data Exchange (ETDEWEB)

    Hoehler, M; McCallen, D; Noble, C

    1999-06-01

    The analysis, and subsequent retrofit, of concrete arch bridges during recent years has relied heavily on the use of computational simulation. For seismic analysis in particular, computer simulation, typically utilizing linear approximations of structural behavior, has become standard practice. This report presents the results of a comprehensive study of the significance of model sophistication (i.e. linear vs. nonlinear) and pertinent modeling assumptions on the dynamic response of concrete arch bridges. The study uses the Bixby Creek Bridge, located in California, as a case study. In addition to presenting general recommendations for analysis of this class of structures, this report provides an independent evaluation of the proposed seismic retrofit for the Bixby Creek Bridge. Results from the study clearly illustrate a reduction of displacement drifts and redistribution of member forces brought on by the inclusion of material nonlinearity. The analyses demonstrate that accurate modeling of expansion joints, for the Bixby Creek Bridge in particular, is critical to achieve representative modal and transient behavior. The inclusion of near-field displacement pulses in ground motion records was shown to significantly increase demand on the relatively softer, longer period Bixby Creek Bridge arch. Stiffer, shorter period arches, however, are more likely susceptible to variable support motions arising from the canyon topography typical for this class of bridges.

  19. V. Tormis: "Bridge of Song / Brian Hunt

    Index Scriptorium Estoniae

    Hunt, Brian

    1997-01-01

    Uuest heliplaadist "V. Tormis: "Bridge of Song" - Bridge of Song; Singing aboard ship; Brides Farewell; Kihnu Island Wedding Songs; 17 Estonian Wedding Songs; Three Estonian Game Songs; Four Estonian Lullabies. Estonian Radio Choir / Toomas Kapten. Finlandia 4509 96937-2; 56:52 DDD; "People of Kalevala" - God protect us from war; Vespian Winter; Eagle Flew From the North East; Plague Memory; Vainamoinen's Words of Wisdom; The Seventeenth Rune of Kalevala. National Male Choir of Estonia. Finlandia 0630 12245-2; 56:52 DDD

  20. Stability of a liquid bridge under vibration

    Science.gov (United States)

    Benilov, E. S.

    2016-06-01

    We examine the stability of a vertical liquid bridge between two vertically vibrating, coaxial disks. Assuming that the vibration amplitude and period are much smaller than the mean distance between the disks and the global timescale, respectively, we employ the method of multiple scales to derive a set of asymptotic equations. The set is then used to examine the stability of a bridge of an almost cylindrical shape. It is shown that, if acting alone, gravity is a destabilizing influence, whereas vibration can weaken it or even eliminate altogether. Thus, counter-intuitively, vibration can stabilize an otherwise unstable capillary structure.

  1. ParB spreading requires DNA bridging

    OpenAIRE

    Graham, Thomas G. W.; Wang, Xindan; Song, Dan; Etson, Candice M.; van Oijen, Antoine M.; Rudner, David Z.; Loparo, Joseph J.

    2014-01-01

    The bacterial parABS system is employed for plasmid partitioning and chromosome segregation. ParB binds to parS sites and associates with broad regions of adjacent DNA, a phenomenon known as spreading. However, the molecular basis for spreading is unknown. Using single-molecule approaches, Graham et al. demonstrate DNA bridging by B. subtilis ParB (Spo0J). Spo0J mutations that disrupt DNA bridging lead to defective spreading and SMC condensin complex recruitment. This study suggests a novel, ...

  2. Germanium-overcoated niobium Dayem bridges

    Science.gov (United States)

    Holdeman, L. B.; Peters, P. N.

    1976-01-01

    Overcoating constriction microbridges with semiconducting germanium provides additional thermal conductivity at liquid-helium temperatures to reduce the effects of self-heating in these Josephson junctions. Microwave-induced steps were observed in the I-V characteristics of an overcoated Dayem bridge fabricated in a 15-nm-thick niobium film; at least 20 steps could be counted at 4.2 K. No steps were observed in the I-V characteristics of the bridge prior to overcoating. In addition, the germanium overcoat can protect against electrical disturbances at room temperature.

  3. Ambient Vibration Test on Reinforced Concrete Bridges

    Directory of Open Access Journals (Sweden)

    Idris Nurul Shazwin

    2016-01-01

    Full Text Available An investigation was carried out to determine dynamic characteristic of reinforced concrete (RC bridges by using ambient vibration test (AVT. The ambient vibration sources on bridges may come from traffic, wind, wave motion and seismic events. AVT describes the dynamic characteristics of the bridge and ground by measuring the natural frequencies using highly sensitive seismometer sensor. This test is beneficial due to light weight equipment and smaller number of operator required, cheap and easy to be handled. It is able to give a true picture of the bridge dynamic behavior without any artificial force excitation when vibration data is recorded. A three-span reinforced concrete bridge located in Sri Medan, Batu Pahat, Johor was measured by using microtremor equipment consist of three units of 1 Hz eigenfrequency passive sensors used in this test was performed in normal operating condition without excitation required from any active sources or short period noise perturbations. Ten measurements were conducted on the bridge deck and ten measurements on the ground surface in order to identify the natural frequencies of the bridge. Several peak frequencies were identified from three components of Fourier Amplitude Spectra (FAS in transverse (North-South, longitudinal (East-West and vertical (Up-Down direction as well as squared average Horizontal to Vertical Spectral Ratio (HVSR of ground response, computed by using Geopsy software. From the result, it was expected the bridge have five vibration modes frequencies in the range of 1.0 Hz and 7.0 Hz with the first two modes in the transverse and longitudinal direction having a frequency 1.0 Hz, the third mode is 2.2 Hz in transverse direction, fourth and fifth mode is 5.8 Hz and 7.0 Hz. For ground natural frequencies are in range 1.0 Hz to 1.3 Hz for North-South direction and 1.0 Hz to 1.6 Hz for East-West direction. Finally the results are compared with several empirical formulas for simple

  4. A Bridge Deflection Monitoring with GPS

    Science.gov (United States)

    Figurski, M.; Gałuszkiewicz, M.; Wrona, M.

    2007-01-01

    This paper introduces results of investigation carried on by The Applied Geomatics Section in Military University of Technology. Research includes possibilities of monitoring dynamic behavior of a bridge using high rate GPS data. Whole event was executed with collaboration of The Road and Bridge Management and The Warsaw Geodesy Company. Interdisciplinary approach with this project allows authors to get reliable information about investigating constructions and their respond for true traffic loading detected by GPS receivers. Way of compute data and used software (TRACK) are also shown in this paper.

  5. Planar Hall effect bridge magnetic field sensors

    DEFF Research Database (Denmark)

    Henriksen, A.D.; Dalslet, Bjarke Thomas; Skieller, D.H.;

    2010-01-01

    Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can...... be significantly enhanced by a geometric factor. For the samples in the present study, we demonstrate an enhancement of the sensor output by a factor of about 100 compared to cross-shaped sensors. The presented construction opens a new design and application area of the planar Hall effect, which we term planar...... Hall effect bridge sensors....

  6. Planar Hall effect bridge magnetic field sensors

    Science.gov (United States)

    Henriksen, A. D.; Dalslet, B. T.; Skieller, D. H.; Lee, K. H.; Okkels, F.; Hansen, M. F.

    2010-07-01

    Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can be significantly enhanced by a geometric factor. For the samples in the present study, we demonstrate an enhancement of the sensor output by a factor of about 100 compared to cross-shaped sensors. The presented construction opens a new design and application area of the planar Hall effect, which we term planar Hall effect bridge sensors.

  7. “On a bridge in Berlin”

    DEFF Research Database (Denmark)

    Pihl, Ole Verner

    2013-01-01

    that jumps in time and place: it begins with Martin Heidegger´s quotation “The Bridge gathers to itself in its own way earth and sky, divinities and mortals”, and the bridge is a state of mind, a chronotope, a portal in time between past, present, and future. The methodological approach is based...... on Bachelard and Heidegger. This GN investigates how architecture changes our cities and cultural identity. It merges different narrative time layers as: childhood memories, dreams, hallucinations, fiction, past, present, and future. The findings of this paper explains why a cross disciplinary approach...

  8. Composite timber-concrete road bridge structure

    Directory of Open Access Journals (Sweden)

    Stojić Dragoslav

    2007-01-01

    Full Text Available This work presents preliminary design of the road bridge made of laminated timber. The supporting system of the main bearing elements is made of the laminated timber in the system of arch with three joints; the bridge slab is designed as continuous slab, made of nine equal fields; each pair is made as composite timber-concrete beam, where the road slab is made of concrete and the needle pieces are made of timber. Fundament is based on HW piles. All the elements are designed to Eurocode.

  9. Diode-quad bridge for reactive transducers and FM discriminators

    Science.gov (United States)

    Harrison, D. R.; Dimeff, J.

    1972-01-01

    Diode-quad bridge circuit was developed for use with pressure-sensitive capacitive transducers, liquid-level measuring devices, proximity deflection sensors, and inductive displacement sensors. It may also be used as FM discriminator and as universal impedance bridge.

  10. Foot force models of crowd dynamics on a wobbly bridge

    CERN Document Server

    Belykh, Igor; Belykh, Vladamir

    2016-01-01

    Modern pedestrian and suspension bridges are designed using industry-standard packages, yet disastrous resonant vibrations are observed, necessitating multi-million dollar repairs. Recent examples include pedestrian induced vibrations during the openings of the Solf\\'erino Bridge in Paris in 1999 and the increased bouncing of the Squibb Park Bridge in Brooklyn in 2014. The most prominent example of an unstable lively bridge is the London Millennium Bridge which started wobbling as a result of pedestrian-bridge interactions. Pedestrian phase-locking due to footstep phase adjustment, is suspected to be the main cause of its large lateral vibrations; however, its role in the initiation of wobbling was debated. In this paper, we develop foot force models of pedestrians' response to bridge motion and detailed, yet analytically tractable models of crowd phase-locking. We use bio-mechanically inspired models of crowd lateral movement to investigate to what degree pedestrian synchrony must be present for a bridge to ...

  11. Violin bridge mobility analysis under in-plane excitation.

    Science.gov (United States)

    Zhang, Cheng-Zhong; Zhang, Guang-Ming; Ye, Bang-Yan; Liang, Li-Dong

    2013-11-08

    The vibration of a violin bridge is a dynamic contact vibration with two interfaces: strings-bridge, and bridge feet-top plate. In this paper, the mobility of an isolated bridge under in-plane excitation is explored using finite element modeling based on the contact vibration model. Numerical results show that the dynamic contact stiffness in the two contact interfaces has a great impact on the bridge mobility. A main resonance peak is observed in the frequency range of 2-3 kHz in the frequency response of the isolated bridge when the contact stiffness is smaller than a critical threshold. The main resonance peak frequency is affected by the contact stiffness as well. In order to verify the numerical findings, a novel experimental system is then designed on the basis of a piezoelectric dynamometer for bridge mobility analysis. Experimental results confirm the impact of the dynamic contact stiffness on the bridge mobility.

  12. CDC WONDER: Population - Bridged-Race July 1st Estimates

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Population - Bridged-Race July 1st Estimates online databases report bridged-race population estimates of the July 1st resident population of the United States,...

  13. Violin Bridge Mobility Analysis under In-Plane Excitation

    Directory of Open Access Journals (Sweden)

    Cheng-Zhong Zhang

    2013-11-01

    Full Text Available The vibration of a violin bridge is a dynamic contact vibration with two interfaces: strings-bridge, and bridge feet-top plate. In this paper, the mobility of an isolated bridge under in-plane excitation is explored using finite element modeling based on the contact vibration model. Numerical results show that the dynamic contact stiffness in the two contact interfaces has a great impact on the bridge mobility. A main resonance peak is observed in the frequency range of 2–3 kHz in the frequency response of the isolated bridge when the contact stiffness is smaller than a critical threshold. The main resonance peak frequency is affected by the contact stiffness as well. In order to verify the numerical findings, a novel experimental system is then designed on the basis of a piezoelectric dynamometer for bridge mobility analysis. Experimental results confirm the impact of the dynamic contact stiffness on the bridge mobility.

  14. Hydraulic bridges in unsaturated coarse granular media: Influence of bridge size and conductivity on flow through clasts

    Science.gov (United States)

    Jayakody, Jeevan A.; Nicholl, Michael J.

    2016-10-01

    Unsaturated flow in coarse granular media must pass through hydraulic bridges (e.g., pendular water, porous connections) that form a physical connection between adjoining clasts. Previous studies suggest that volumetric flow through a porous clast (Q) will be linearly dependent on the cross-sectional area of the hydraulic bridges, and understate the importance of bridge conductivity. Numerical simulations were performed to explore steady-state flow through a spherical clast with identical bridges located at the top and bottom. The cross-sectional area of the bridges relative to that of the clast (Ar) was varied across six orders of magnitude. The ratio of hydraulic conductivity between bridges and clasts (Kb/Kc) was varied across 12 orders of magnitude to consider resistive, neutral, and conductive bridges. Results show that hydraulic bridges place a primary control on both Q and flux distribution within the clast. For neutral and conductive bridges (Kb/Kc ≥1), Ar is the dominant factor in determining Q, while Kb/Kc is the primary control for resistive bridges (Kb/Kc < 1). For all bridges, Q shows a non-linear dependency on both Ar and Kb/Kc. The intra-clast flow distribution shifts outwards as Ar increases. Conductive bridges promote this process and resistive bridges impede it.

  15. Bridging the digital divide with mobile services

    CERN Document Server

    Yelton, Andromeda

    2013-01-01

    In this issue of Library Technology Reports, Andromeda Yelton shows how libraries can build on the breadth of this population to help bridge the digital divide and provide even greater access to information. Yelton breaks down the demographics of mobile internet users, provides examples of how different libraries are reaching out to these populations, and suggests what the future may hold for this trend.

  16. Circuit bridging of components by smoke

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T.J.; Nowlen, S.P.; Anderson, D.J. [Sandia National Labs., Albuquerque, NM (United States)

    1996-10-01

    Smoke can adversely affect digital electronics; in the short term, it can lead to circuit bridging and in the long term to corrosion of metal parts. This report is a summary of the work to date and component-level tests by Sandia National Laboratories for the Nuclear Regulatory Commission to determine the impact of smoke on digital instrumentation and control equipment. The component tests focused on short-term effects such as circuit bridging in typical components and the factors that can influence how much the smoke will affect them. These factors include the component technology and packaging, physical board protection, and environmental conditions such as the amount of smoke, temperature of burn, and humidity level. The likelihood of circuit bridging was tested by measuring leakage currents and converting those currents to resistance in ohms. Hermetically sealed ceramic packages were more resistant to smoke than plastic packages. Coating the boards with an acrylic spray provided some protection against circuit bridging. The smoke generation factors that affect the resistance the most are humidity, fuel level, and burn temperature. The use of CO{sub 2} as a fire suppressant, the presence of galvanic metal, and the presence of PVC did not significantly affect the outcome of these results.

  17. Bridges in Mathematics. WWC Intervention Report

    Science.gov (United States)

    What Works Clearinghouse, 2009

    2009-01-01

    "Bridges in Mathematics," published by the Math Learning Center (MLC), is an elementary school math curriculum covering kindergarten through fifth grade that focuses on problem solving and skill building, and applies a combination of whole-group, small-group, and independent activities. Lessons incorporate visual models, including manipulatives,…

  18. The Memory Bridge Initiative on Service Learners

    Science.gov (United States)

    Wescott, Amy; Healy, Tara C.

    2011-01-01

    This study evaluated the Memory Bridge Initiative (MBI), an educational, experiential program pairing high school students with older adults who have dementia. A qualitative, single group design with baseline and follow-up measures examined whether or not students would have a positive learning experience while gaining newfound appreciation and…

  19. Bridging the Gap: Pracademics in Foreign Policy

    Science.gov (United States)

    Murphy, Ann Marie; Fulda, Andreas

    2011-01-01

    In his seminal work "Bridging the Gap: Theory and Practice in Foreign Policy", Alexander George (1993) lamented the great divide between academia and the foreign policymaking community, arguing that greater interaction between scholars and policymakers would produce better policy. We share George's belief that scholars and practitioners each have…

  20. Ergonomic aspects of automation in navigation bridges

    NARCIS (Netherlands)

    Lazet, A.; Walraven, P.L.

    1971-01-01

    New ergonomic questions arise from the tendency toward increasing automation in maritime operations. Direct control of engines and rudder from the bridge promises improved ship control, provided that the operator can really exploit the technical improvements. To make such direct control most efficie

  1. LPN/ADN Bridge Course. Instructor's Guide.

    Science.gov (United States)

    Barrett, Jan; And Others

    This curriculum guide has been constructed in order to bridge the skills gap between licensed practical nursing (LPN) programs and associate degree nursing (ADN) programs in Missouri. The curriculum was developed through a cooperative effort by persons from both sectors. The curriculum contains four major units, each consisting of several lessons,…

  2. Journaling: A Bridge between School and Home

    Science.gov (United States)

    McGough, Julie

    2013-01-01

    This article describes how first-grade students create meaningful communication with families and help build the student-teacher-parent relationship through journaling. Journals are a useful tool to bridge school and home. A journal can communicate learning goals, develop scientific vocabulary, and create dialogue through oral and written…

  3. 75 FR 41281 - Bridge Safety Standards

    Science.gov (United States)

    2010-07-15

    ... Federal Register at 60 FR 20654, the interim statement included a request for comments to be submitted to... of Agency Policy on the Safety of Railroad Bridges (``policy statement''). See 65 FR 52667. With the... amendment. See 74 FR 157. All aspects of the policy statement that are not incorporated into the...

  4. Heavy Vehicles on Minor Highway Bridges

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.; Kirkegaard, Poul Henning; Enevoldsen, I.

    The present paper worked out as a part of a research project on "Dynamic amplification factor of vehicle loadings on smaller bridges" establishes a two-dimensional spectral description of the road roughness surface based on measurements from a Danish road using so-called Profilograph used by Dani...

  5. Bridging gaps : ten crosscurrents in media studies

    OpenAIRE

    Fornäs, Johan

    2008-01-01

    The final, definitive version of this paper has been published in: Media, Culture and Society, (30), 6, 895-905, 2008.Johan Fornäs, Bridging Gaps: Ten Crosscurrents in Media Studies.http://dx.doi.org/10.1177/0163443708096811. by SAGE Publications Ltd, All rights reserved. http://www.sagepub.com/

  6. Steel plate reinforcement of orthotropic bridge decks

    NARCIS (Netherlands)

    Teixeira de Freitas, S.

    2012-01-01

    The PhD research is focused on the reinforcement of fatigue cracked orthotropic steel bridge decks (OBD) by adding a second steel plate to the existing deck. The main idea is to stiffen the existing deck plate, which will reduce the stresses at the fatigue sensitive details and extend the fatigue li

  7. Aeroelastic Stability of Suspension Bridges using CFD

    DEFF Research Database (Denmark)

    Stærdahl, Jesper Winther; Sørensen, Niels; Nielsen, Søren R.K.

    2007-01-01

    In recent years large span suspension bridges with very thin and slender profiles have been built without proportional increasing torsional and bending stiffness. As a consequence large deformations at the mid-span can occur with risk of aeroelastic instability and structural failure. Analysis...

  8. The mechanics of ship impacts against bridges

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    a glancing blow between the ship and the bridge structure. This model is based on rigid body mechanics and well suited for inclusion in a probabilistic analysis procedure. Finally, some empirical expressions are presented which relate the energy absorbed by crushing of ship structures to the maximum impact...

  9. Fiber reinforced polymer composites for bridge structures

    Directory of Open Access Journals (Sweden)

    Alexandra CANTORIU

    2013-12-01

    Full Text Available Rapid advances in construction materials technology have led to the emergence of new materials with special properties, aiming at safety, economy and functionality of bridges structures. A class of structural materials which was originally developed many years ago, but recently caught the attention of engineers involved in the construction of bridges is fiber reinforced polymer composites. This paper provides an overview of fiber reinforced polymer composites used in bridge structures including types, properties, applications and future trends. The results of this study have revealed that this class of materials presents outstanding properties such as high specific strength, high fatigue and environmental resistance, lightweight, stiffness, magnetic transparency, highly cost-effective, and quick assembly, but in the same time high initial costs, lack of data on long-term field performance, low fire resistance. Fiber reinforced polymer composites were widely used in construction of different bridge structures such as: deck and tower, I-beams, tendons, cable stands and proved to be materials for future in this field.

  10. Bridging the Gap Between Theory and Practice

    Directory of Open Access Journals (Sweden)

    Roy H.M. Sembel

    2015-05-01

    Full Text Available Some concerns in the field of Business Management regarding the gap between theory and practice have been raised by practitioners and academicians. This keynote speech describes some lessons learned from the academic literature regarding this gap (whether the gap really exists, and if it exists, whether it needs to be bridged or closed, and how to bridge or close this gap, and shares the author's personal and professional experiences of living as both an academician and a practitioner. The main findings of this article are: (1 Yes the gap exists, however, it has to be viewed in a wider perspective to really understand the situation; (2 The gap in a specific area is bad and should become our concern, but in other areas it should not; (3 There are some ways to bridge or close the negative gap; (4 There exists hybrid career opportunities to become professionals that work both as an academician and a practitioner; (5 This new breed of hybrid professionals has a huge potential to bridge the bad theory-practice gap.

  11. Thermal Bridge Effects in Window Grooves

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report thermal bridge effects in window grooves are analyzed. The analysis is performed using different thicknesses of the window groove insulation, to evaluate what the optimal solution is.All analysis in the report is performed using both 2- and 3-dimensional numerical analysis....

  12. Analysis on Stability Simulation of Right Abutment Slope, Delsi-Tanisagua Hydroelectric Project, Ecuador%厄瓜多尔德尔西水电站右坝肩边坡稳定性模拟分析

    Institute of Scientific and Technical Information of China (English)

    梁晓波; 张为法

    2014-01-01

    基于厄瓜多尔德尔西水电站前期地质勘查资料,用Gocad软件建立右坝肩边坡的三维地质模型,导入Flac3d做弹塑性分析和强度折减计算,根据计算所得位移场和应力场的分布规律,分析评价右坝肩边坡的天然稳定性,探讨边坡的可能破坏情况。%Based on data on geological exploration at the feasible study stage of Delsi-Tanisagua Hydroelectric Project in Ecuador, 3D geological model of slope in right abutment is built with Gocad.Then Flac3d is introduced to perform the elastic-plastic analysis and the strength reduction calculation.In accordance with the distribution law of displacement field and stress field from the calculation, the natural stability of the slope in the right abutment is analyzed and assessed, and the potential failure of the slope isstudied.

  13. Noise Reduction of Fractional Source in Cryogenic Current Comparator Bridge

    OpenAIRE

    C. Jassadajin; Kurupakorn, C.; N. Khumthukthit; A. Pruksanubal

    2013-01-01

    In this work, a resistance measurement is done at both high accuracy and precision using Cryogenic Current Comparator (CCC) bridge system [1]. A CCC bridge circuit consists of three parts: coil, current source and detector parts. There are electronic components in the current source of the system. They generate thermal noise in the measurement system. This paper shows the noise reduction in a fractional source of CCC Bridge which is a ramp generator. The bridge receives the voltage signal, wh...

  14. Performance of damage detection methods in bridges through vibration monitoring

    OpenAIRE

    Cruz, Paulo J. S.; Salgado, R.

    2009-01-01

    The important advances achieved in the modal identification, sensors and structural monitoring of bridges have motivated the bridge engineering community to develop damage detection methods based on vibration monitoring. Some of these methods have already been demonstrated under certain conditions in bridges with deliberate damage (Farrar et al., 1998). However, the performance of these methods for damage detection in bridges has not been fully proven so far and more research n...

  15. RISK LEVEL ANALYSIS ON THE PREVENTIVE EROSION CAPACITY OF BRIDGES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Deficiency of the Preventive Erosion Capacity (PEC) of a bridge pier is the main factor leading to bridge failures. In this paper, the PEC of bridge piers was analyzed using the stochastic analysis method. The definitions of the reliability and risk level of a bridge pier subjected to water erosion were proposed and a computational model for erosion depth and risk level in was suggested.

  16. The detection of an older population in the Magellanic Bridge

    OpenAIRE

    Bagheri, Gemma; Cioni, Maria-Rosa; Napiwotzki, Ralf

    2012-01-01

    The Magellanic system comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), and the less frequently observed Magellanic Bridge and Magellanic Stream. The Bridge is traced by neutral gas and has an observed stellar component, while the Stream consists of gas only, with no observed stellar counterpart to date. This study uses catalogues created in the direction of the Bridge from 2MASS and WISE to investigate the stellar content of the Magellanic Bridge. Catalogues were ...

  17. Rupture of an Evaporating Liquid Bridge between Two Grains

    OpenAIRE

    Mielniczuk, Boleslaw; El Youssoufi, Moulay Saïd; Sabatier, Laurent; Hueckel, Tomasz

    2014-01-01

    The study examines rupture of evaporating liquid bridges between two glass spheres. Evolution of the bridge profile has been recorded with the use of high-speed camera. Geometrical characteristics of the bridge were then used to calculate evolution of the variables during the process: Laplace pressure, capillary force, and surface tension force. For the purpose of reference, the bridge evolution is followed also during kinematic extension. During both processes the diameter of the neck decrea...

  18. TorBricks: Blocking-Resistant Tor Bridge Distribution

    OpenAIRE

    Zamani, Mahdi; Saia, Jared; Crandall, Jedidiah

    2016-01-01

    Tor is currently the most popular network for anonymous Internet access. It critically relies on volunteer nodes called bridges for relaying Internet traffic when a user's ISP blocks connections to Tor. Unfortunately, current methods for distributing bridges are vulnerable to malicious users who obtain and block bridge addresses. In this paper, we propose TorBricks, a protocol for distributing Tor bridges to n users, even when an unknown number t < n of these users are controlled by a malicio...

  19. Railroad Bridges in Louisiana, Geographic NAD83, FEMA (1997) [railroad_bridges_FEMA_1997

    Data.gov (United States)

    Louisiana Geographic Information Center — This is is a point dataset for the locations and attributes of 32 Louisiana railroad bridges. The attributes include city (nearest?), county (sic), routefrom...

  20. Nondestructive evaluation inspection of the Arlington Memorial Bridge using a robotic assisted bridge inspection tool (RABIT)

    Science.gov (United States)

    Gucunski, Nenad; Boone, Shane D.; Zobel, Rob; Ghasemi, Hamid; Parvardeh, Hooman; Kee, Seong-Hoon

    2014-04-01

    The information presented in this report provides a detailed assessment of the condition of the Arlington Memorial Bridge (AMB) deck. The field-data collection was obtained by both the RABIT™ Bridge Inspection Tool and a number of semi-automated non-destructive evaluation (NDE) tools. The deployment of the semi-automated NDE tools was performed to inspect the AMB deck condition and also to validate data obtained by the RABIT™ Bridge Inspection Tool. Data mining and analysis were accomplished through enhanced data interpretation and visualization capabilities using advanced data integration, fusion, and 2D rendering. One of the major challenges that the research team had to overcome in assessing the condition of the AMB deck was the presence of an asphalt overlay on the entire bridge deck.

  1. Performance Assessment of Bridges Using GPS: The Juarez Bridge in Culiacan, Mexico

    Science.gov (United States)

    Vazquez, G. E.; Gaxiola-Camacho, J. R.; Trejo, M.; Echagaray, J.; Guzman, G. M.

    2015-12-01

    Performance assessment of bridges has become very important during recent years. Bridges around the world are aging, leading to the incorporation of efficient, reliable, and economic evaluation procedures. These techniques must assess properly the performance of bridges under several loading conditions in a real manner, representing the physics of the problem. Among several approaches, Global Positioning System (GPS) can be intelligently used for the performance evaluation of bridges. We focused on GPS, since it naturally produces position estimates as compared to seismic instruments that record either velocity or acceleration, and thus require an integration. There are several reasons that make the Juarez Bridge a case of study for evaluation: it is approximately 45 years old, it is a reinforced concrete structure, it connects two significant zones of the city, and its spans is closely to 200 meters long. In addition, thousands of vehicles and pedestrians use the Juarez Bridge every day, which make feasible the GPS performance assessment. Hence, in order to produce optimal position estimates, GPS data were collected during two consecutive hours at three different periods of the day for a whole week (Monday through Sunday), to represent three critical limit states of the bridge (mid-span and end-spans). GPS data were processed using the GAMIT/GLOBK software, considering 1-second sampling rate, 15-degree cutoff angle, ionosphere-free double-differenced (DD) carrier phase method, and precise final orbits disseminated by IGS (International GNSS Service). The displacements obtained from the above discussed procedure are compared with allowable values documented in bridge construction manuals. Reliability theory was used to evaluate the probability of failure of the bridge for the three periods of the day. In addition, a conclusion was made about the most risky day of the week for the use of the Juarez Bridge. It is expected that the results from the proposed research

  2. Monitoring of levees, bridges, pipelines, and other critical infrastructure during the 2011 flooding in the Mississippi River Basin: Chapter J in 2011 floods of the central United States

    Science.gov (United States)

    Densmore, Brenda K.; Burton, Bethany L.; Dietsch, Benjamin J.; Cannia, James C.; Huizinga, Richard J.

    2014-01-01

    more prone to erosion or scour. Data collected from multibeam echosounder hydrographic surveys at selected bridges aided State agencies in evaluating the structural integrity of the bridges during the flood, by assessing the amount of scour present around piers and abutments. Hydrographic surveys of the riverbed detected scour depths ranging from zero (no scour) to approximately 5.8 meters in some areas adjacent to North Dakota bridge piers, zero to approximately 6 meters near bridge piers in Nebraska, and zero to approximately 10.4 meters near bridge piers in Missouri. Substructural support elements of some bridge piers in North Dakota, Nebraska, and Missouri that usually are buried were exposed to moving water and sediment. At five Missouri bridge piers the depth of scour left less than 1.8 meters of bed material between the bottom of the scour hole and bedrock. State agencies used this information along with bridge design and construction information to determine if reported scour depths would have a substantial effect on the stability of the structure. Multibeam echosounder hydrographic surveys of the riverbed near pipeline crossings did not detect exposed pipelines. However, analysis of the USGS survey data by pipeline companies aided in their evaluation of pipeline safety and led one company to further investigate the safety of their line and assisted another company in getting one offline pipeline back into operation. Multibeam echosounder hydrographic surveys of the banks, riverbed, and underwater infrastructure at Omaha Public Power District power plants documented the bed and scour conditions. These datasets were used by Omaha Public Power District to evaluate the effects that the flood had on operation, specifically to evaluate if scour during the peak of the flood or sediment deposition during the flood recession would affect the water intake structures. Hydrographic surveys at an Omaha Public Power District electrical transmission tower documented scour so

  3. 采动影响下三连铁路桥维修加固方案%Maintenance and Reinforcement Schemes of Sanlian Railway Bridge Under the Influence of Mining

    Institute of Scientific and Technical Information of China (English)

    田迎斌

    2015-01-01

    为了实现受采动影响铁路桥梁的安全运行,应用概率积分法预计了S2 S7工作面开采对三连铁路桥产生的最大移动与变形值。在此基础上分析了下沉、倾斜及水平变形对桥梁结构的影响。结果表明:桥梁下沉后铁路桥下过水断面净空高度满足规范要求;桥梁纵向倾斜不影响行车,可通过不断调整轨面来满足规范要求的桥梁横向倾斜且不影响墩台的稳定性;桥梁纵向压缩不会影响正常使用,但桥梁基础横向拉伸变形已达Ⅲ级。针对桥梁基础有可能遭受到较大损害的情况,提出了采用扁钢对桥墩及桥台进行加固的设计方案,并提出了保证线路正常运行的安全措施。实践表明,经过加固的铁路桥经受住了S2 S7工作面的采动影响,达到了铁路桥下安全采煤的目的。%In order to realize the safety service of the railway bridge influenced by mining,the probability integral method was used to predict the movement and deformation values of the Sanlian railway bridge at the S2 S7 working face during mining. Based on this,the effect of subsidence,inclination and horizontal deformation on structure of railway bridge was analyzed. The results showed that the wetted cross section height under the railway bridge is in accord with the requirement of criterion,the longitudinal inclination of the bridge beam did not influence the driving,and the horizontal inclination met the requirement of the criterion by adjusting the orbit plane,so it cannot influence the stability of the bridge pier. The longitudinal compression of the bridge did not affect the use, but the tensile deformation of the bridge lateral basis reached Class III, resulting that the bridge foundation may suffer the great damage. In view of this,the design which adopted the flat steel to strengthen the bridge pier and abutment was proposed,and the safety measures for the normal service of the bridge were put forward. The

  4. Building water bridges in air: Electrohydrodynamics of the Floating Water Bridge

    OpenAIRE

    Marin, Alvaro G.; Lohse, Detlef

    2010-01-01

    The interaction of electrical fields and liquids can lead to a phenomenon that defies intuition. Some famous examples can be found in electrohydrodynamics as Taylor cones, whipping jets, or noncoalescing drops. A less famous example is the floating water bridge: a slender thread of water held between two glass beakers in which a high voltage difference is applied. Surprisingly, the water bridge defies gravity even when the beakers are separated at distances up to 2 cm. In this paper, experime...

  5. Spectroscopic Studies of Bridge Contributions to Electronic Coupling in a Donor-Bridge-Acceptor Biradical System

    OpenAIRE

    Kirk, Martin L.; Shultz, David A.; Depperman, Ezra C.; Habel-Rodriguez, Diana; Schmidt, Robert D.

    2012-01-01

    Variable temperature electronic absorption and resonance Raman spectroscopies are used to probe the excited state electronic structure of TpCum,MeZn(SQ-Ph-NN) (1) – a donor-bridge-acceptor (D-B-A) biradical complex and a ground state analog of the charge-separated excited state formed in photoinduced electron transfer reactions. Strong ferromagnetic exchange coupling that is mediated by the para-phenylene bridge stabilizes the triplet ground state of this molecule. Detailed spectroscopic and ...

  6. 49 CFR 237.31 - Adoption of bridge management programs.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Adoption of bridge management programs. 237.31 Section 237.31 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... Adoption of bridge management programs. Each track owner shall adopt a bridge safety management program...

  7. Ambient Response Analysis of the Great Belt Bridge

    DEFF Research Database (Denmark)

    Brincker, Rune; Frandsen, J. B.; Andersen, P.

    2000-01-01

    In this paper an ambient response analysis of the Great Belt Bridge is presented. The Great Belt Bridge is one of the largest suspension bridges in the world, and the analysis was carried out in order to investigate the possibilities of estimating reliable damping values from the ambient response...

  8. 23 CFR 650.409 - Evaluation of bridge inventory.

    Science.gov (United States)

    2010-04-01

    ... BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409... establishing eligibility and priority for replacement or rehabilitation of bridges; in general the lower the... State program. After evaluation of the inventory and assignment of sufficiency ratings, the...

  9. Reduction of Impact Noise of Trams on a Major Bridge

    NARCIS (Netherlands)

    Dittrich, M.G.; Bosshaart, C.; Wessels, P.W.

    2015-01-01

    As part of a recent renovation of the Erasmus bridge in Rotterdam, improvements were made to reduce impact noise caused by trams passing a series of rai! joints. The bridge inciudes several different sections inciuding a bascule bridge and is in an inner city tocation with new adjacent apartment bui

  10. 21 CFR 872.3770 - Temporary crown and bridge resin.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Temporary crown and bridge resin. 872.3770 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3770 Temporary crown and bridge resin. (a) Identification. A temporary crown and bridge resin is a device composed of a material, such...

  11. Resin-Bonded Bridges in vitro and in vivo

    NARCIS (Netherlands)

    Veen, Johannes Hilbrandt van der

    1988-01-01

    In this thesis in vitro and in vivo studies on the clinical application of resin-bonded bridges are described and discussed. The development of different types of resin-bonded bridges is described in chapter 1. The bridges are often made by boding a cast metal retainer fitted with and artificial too

  12. Bridged Quaterphenyls as Flashlamp-Pumpable Laser Dyes

    OpenAIRE

    Kauffman, Joel M; Kelley, Charles J.; Ghiorghis, Alem; Neister, Edward; Armstrong, Lorne; Prause, Paul R.

    1987-01-01

    Partial bridging of the o,o′ positions of the aromatic rings in quaterphenyl gave superior flashlamp-pumpable laser dyes. Alkyl-substituted carbon bridges gave superior dyes to those containing oxygen or alkyl-substituted nitrogen or silicon bridges. Dyes lasing in the 365–390 nm region with improved energy output, lifetime and solubility were discovered.

  13. Improving the Dynamics of Suspension Bridges using Active Control Systems

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Improving the dynamics of suspension bridge using active control is discussed in this paper. The main dynamic problem with long suspension bridges is the aeroelastic phenomenon called flutter. Flutter oscillations of a bridge girder is a stability problem and the oscillations are perpendicular...

  14. Renovation techniques for fatigue cracked orthotropic steel bridge decks

    NARCIS (Netherlands)

    de Jong, F.B.P.

    2007-01-01

    This dissertation presents the research into renovation techniques for orthotropic steel bridge decks. These techniques are needed to solve fatigue problems in the decks of these bridges, as several fatigue cracks have been detected in the deck structure of these bridges the last decade. A well-know

  15. Road Bridges and Culverts, Bridges layers located in GIS and Transportation database., Published in unknown, City of Roswell, GA.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Road Bridges and Culverts dataset as of unknown. It is described as 'Bridges layers located in GIS and Transportation database.'. Data by this publisher are...

  16. PARAMETRIC STUDY OF SKEW ANGLE ON BOX GIRDER BRIDGE DECK

    OpenAIRE

    Shrikant D. Bobade *, Dr. Valsson Varghese

    2016-01-01

    Box girder bridge deck, is the most common type of bridges in world and India, it consists of several Slab or girders. The span in the direction of the roadway and connected across their tops and bottoms by a thin continuous structural stab, the longitudinal box girders can be made of steel or concrete. The Simple supported single span concrete bridge deck is presented in present study. Skewed bridges are suitable in highway design when the geometry of straight bridges is not possible. The sk...

  17. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...

  18. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    1998-01-01

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...

  19. Seismic Passive Control of Cable-Stayed Bridges

    Directory of Open Access Journals (Sweden)

    Hosam-Eddin M. Ali

    1995-01-01

    Full Text Available A three-dimensional modeling procedure is proposed for cable-stayed bridges with rubber, steel, and lead energy dissipation devices. The passive control technique is investigated by considering the response of bridge models with and without energy dissipation devices. The impact of various design parameters on the seismic response of current and future bridge designs is studied. Appropriate locations and properties of the passive devices can achieve better performance for cable-stayed bridges by balancing the significant reduction in earthquake-induced forces against tolerable displacements. Proper design of passive systems can help provide solutions for retro-fitting some existing bridges.

  20. Dynamic analysis of rail transit elevated bridge with ladder track

    Institute of Scientific and Technical Information of China (English)

    He XIA; Yushu DENG; Yongwei ZOU; Guido DE ROECK; Geert DEGRANDE

    2009-01-01

    In this paper, a dynamic analysis model of an elevated bridge with ladder tracks under moving train load is established. The whole process of a train running through an elevated bridge at different speeds is simulated.The dynamic responses of the elevated bridge with ladder track and the running safety and comfort index of train vehicles are evaluated. Compared with the dynamic responses of an elevated bridge with ordinary non-ballasted slab track, the ladder track's effect on reducing the vibration of an elevated bridge is analyzed. The analysis results show that the ladder track has good vibration reduction characteristics as compared to ordinary non-ballasted track.

  1. Suspension Bridge Flutter for Girder with Separate Control Flaps

    DEFF Research Database (Denmark)

    Huynh, T.; Thoft-Christensen, Palle

    Active vibration control of long span suspension bridge flutter using separated control flaps (SFSC) has shown to increase effectively the critical wind speed of bridges. In this paper, an SFSC calculation based on modal equations of the vertical and torsional motions of the bridge girder including...... the flaps is presented. The length of the flaps attached to the girder, the flap configuration and the flap rotational angles are parameters used to increase the critical wind speed of the bridge. To illustrate the theory a numerical example is shown for a suspension bridge of 1000m+2500m+1000m span based...

  2. Cross-bridge model of muscle contraction. Quantitative analysis.

    OpenAIRE

    Eisenberg, E.; Hill, T L; Chen, Y.

    1980-01-01

    We recently presented, in a qualitative manner, a cross-bridge model of muscle contraction which was based on a biochemical kinetic cycle for the actomyosin ATPase activity. This cross-bridge model consisted of two cross-bridge states detached from actin and two cross-bridge states attached to actin. In the present paper, we attempt to fit this model quantitatively to both biochemical and physiological data. We find that the resulting complete cross-bridge model is able to account reasonably ...

  3. Excitation of Arch and Suspension Bridges by Subwires

    Directory of Open Access Journals (Sweden)

    Noriaki Hiwatashi

    1993-01-01

    Full Text Available A force generation method using a subwire for arch and suspension bridges is proposed. The subwire is connected to the arch or the cable of the bridge through rollers. The uniform force produced by pulling and releasing the pretensioned subwires acts on the bridge as an externalforce. A new device called “the resonance force generator” is also developed to excite the bridges by applying a small force. To verify the proposed concept, a stress ribbon bridge was excited with the resonance force generator.

  4. Excitation of Arch and Suspension Bridges by Subwires

    OpenAIRE

    Noriaki Hiwatashi; Yoji Mizuta; Yutaka Ishihara; Itio Hirai

    1993-01-01

    A force generation method using a subwire for arch and suspension bridges is proposed. The subwire is connected to the arch or the cable of the bridge through rollers. The uniform force produced by pulling and releasing the pretensioned subwires acts on the bridge as an externalforce. A new device called “the resonance force generator” is also developed to excite the bridges by applying a small force. To verify the proposed concept, a stress ribbon bridge was excited with the resonance force ...

  5. Violin Bridge Mobility Analysis under In-Plane Excitation

    OpenAIRE

    Cheng-Zhong Zhang; Guang-Ming Zhang; Bang-Yan Ye; Li-Dong Liang

    2013-01-01

    The vibration of a violin bridge is a dynamic contact vibration with two interfaces: strings-bridge, and bridge feet-top plate. In this paper, the mobility of an isolated bridge under in-plane excitation is explored using finite element modeling based on the contact vibration model. Numerical results show that the dynamic contact stiffness in the two contact interfaces has a great impact on the bridge mobility. A main resonance peak is observed in the frequency range of 2–3 kHz in the frequen...

  6. Translating Climate Projections for Bridge Engineering

    Science.gov (United States)

    Anderson, C.; Takle, E. S.; Krajewski, W.; Mantilla, R.; Quintero, F.

    2015-12-01

    A bridge vulnerability pilot study was conducted by Iowa Department of Transportation (IADOT) as one of nineteen pilots supported by the Federal Highway Administration Climate Change Resilience Pilots. Our pilot study team consisted of the IADOT senior bridge engineer who is the preliminary design section leader as well as climate and hydrological scientists. The pilot project culminated in a visual graphic designed by the bridge engineer (Figure 1), and an evaluation framework for bridge engineering design. The framework has four stages. The first two stages evaluate the spatial and temporal resolution needed in climate projection data in order to be suitable for input to a hydrology model. The framework separates streamflow simulation error into errors from the streamflow model and from the coarseness of input weather data series. In the final two stages, the framework evaluates credibility of climate projection streamflow simulations. Using an empirically downscaled data set, projection streamflow is generated. Error is computed in two time frames: the training period of the empirical downscaling methodology, and an out-of-sample period. If large errors in projection streamflow were observed during the training period, it would indicate low accuracy and, therefore, low credibility. If large errors in streamflow were observed during the out-of-sample period, it would mean the approach may not include some causes of change and, therefore, the climate projections would have limited credibility for setting expectations for changes. We address uncertainty with confidence intervals on quantiles of streamflow discharge. The results show the 95% confidence intervals have significant overlap. Nevertheless, the use of confidence intervals enabled engineering judgement. In our discussions, we noted the consistency in direction of change across basins, though the flood mechanism was different across basins, and the high bound of bridge lifetime period quantiles exceeded

  7. Bridge health assessment system with fatigue analysis algorithm

    Science.gov (United States)

    Wang, Xuan; Wang, M. L.; Zhao, Yang

    2005-05-01

    A modern bridge is such a complicated system that is difficult to analyze by conventional mathematic tools. A rational bridge monitoring requires a good knowledge of the actual condition of various structural components. Fatigue analysis of concrete bridges is one of the most important problems. Concrete bridges are often undergoing a fatigue deterioration, starting with cracking and ending with large holes through the web. There is a need for the development of efficient health assessment system for fatigue evaluation and prediction of the remaining life. This information has clear economical consequences, as deficient bridges must be repaired or closed. The goal of this research is to provide a practical expert system in bridge health evaluation and improve the understanding of bridge behavior during their service. Efforts to develop a functional bridge monitoring system have mainly been concentrated upon successful implementation of experienced-based machine learning. The reliability of the techniques adopted for damage assessment is also important for bridge monitoring systems. By applying the system to an in-service PC bridge, it has been verified that this fuzzy logic expert system is effective and reliable for the bridge health evaluation.

  8. A Review of Indirect Bridge Monitoring Using Passing Vehicles

    Directory of Open Access Journals (Sweden)

    Abdollah Malekjafarian

    2015-01-01

    Full Text Available Indirect bridge monitoring methods, using the responses measured from vehicles passing over bridges, are under development for about a decade. A major advantage of these methods is that they use sensors mounted on the vehicle, no sensors or data acquisition system needs to be installed on the bridge. Most of the proposed methods are based on the identification of dynamic characteristics of the bridge from responses measured on the vehicle, such as natural frequency, mode shapes, and damping. In addition, some of the methods seek to directly detect bridge damage based on the interaction between the vehicle and bridge. This paper presents a critical review of indirect methods for bridge monitoring and provides discussion and recommendations on the challenges to be overcome for successful implementation in practice.

  9. Evaluating the life cycle environmental impact of short span bridges

    DEFF Research Database (Denmark)

    Du, Guangli; Pettersson, Lars; Karoumi, Raid

    2016-01-01

    Bridge infrastructure consumes large amount of energy and raw materials, leading to considerable environmental burdens. The traditional infrastructure construction prioritizes its technical and economic viability. In recent years, the society devotes an ever-increased attention to the environmental...... impact of the construction sector. Life cycle assessment (LCA) is a systematic method for assessing the environmental impact of products and systems, but its application in bridges is scarce. In Swede, most of the bridges are short spans and the type of concrete slab-frame bridge (CFB) accounts...... for a large share. Soil steel composite bridge (SSCB) is a functional equivalent solution for CFB. In order to mitigate the environmental burdens of short span bridges, this paper performed a comparative LCA study between these two types of bridge. The results indicate that the initial material consumption...

  10. Nonlinear Seismic Response Characteristics of Bridge with Double-column High-rise Piers Considering Pounding Effect%考虑碰撞效应的双柱式高墩桥梁非线性地震反应特性研究

    Institute of Scientific and Technical Information of China (English)

    高玉峰; 蒲黔辉; 李晓斌

    2011-01-01

    以西南山区线路中常用的双柱式高墩桥梁为研究对象,建立典型桥跨结构的空间动力分析模型,采用非线性动力时程分析方法,详细研究了考虑地震碰撞效应时桥梁结构的地震响应特性,并探讨了接触单元刚度取值、间隙宽度、桥台刚度以及支座滑动性能等非线性边界条件的影响.结果表明:梁间碰撞作用主要发生在近桥台伸缩缝处,碰撞作用减小桥墩的地震响应,同时在梁体中产生较大的短时加速度脉冲效应;考虑桥台的纵向约束作用将使得梁间碰撞效应增强;对于通常设计采用的间隙宽度范围,强震作用时碰撞现象会不可避免地发生;支座滑动性能对桥墩的地震响应起到隔震的作用,考虑支座滑动性能后梁间碰撞次数减少;各种非线性边界条件因素的综合作用使得桥跨结构的地震响应变得较为复杂,为获得结构真实响应结果应该合理考虑这些因素的影响.%Based on the double-column highway bridges with high-rise piers in southwest mountain area, the spatial dynamic analysis models of representative bridge span were established. The seismic response characteristics of the bridge considering the pounding effect were studied in detail by using nonlinear dynamic time history analysis method. The influence of some nonlinear boundary conditions, including value of contact element stiffness, gap width, abutment stiffness and sliding performance of bearings, were discussed. The results indicate that ( 1 ) the seismic pounding effect between adjacent beams occurs mainly in the expansion joint near the bridge abutments, the pounding reduces the seismic response of piers but generates high magnitude and short duration acceleration pluses in the beams; (2) the pounding effect between adjacent beams will be enhanced when the longitudinal constraint effect of abutments is considered; (3) for the range of gap width usually· adoptod in design, the pounding

  11. Online Bridge Crack Monitoring with Smart Film

    Directory of Open Access Journals (Sweden)

    Benniu Zhang

    2013-01-01

    Full Text Available Smart film crack monitoring method, which can be used for detecting initiation, length, width, shape, location, and propagation of cracks on real bridges, is proposed. Firstly, the fabrication of the smart film is developed. Then the feasibility of the method is analyzed and verified by the mechanical sensing character of the smart film under the two conditions of normal strain and crack initiation. Meanwhile, the coupling interference between parallel enameled wires of the smart film is discussed, and then low-frequency detecting signal and the custom communication protocol are used to decrease interference. On this basis, crack monitoring system with smart film is designed, where the collected crack data is sent to the remote monitoring center and the cracks are simulated and recurred. Finally, the monitoring system is applied to six bridges, and the effects are discussed.

  12. Bridge Condition Assessment Using D Numbers

    Directory of Open Access Journals (Sweden)

    Xinyang Deng

    2014-01-01

    Full Text Available Bridge condition assessment is a complex problem influenced by many factors. The uncertain environment increases more its complexity. Due to the uncertainty in the process of assessment, one of the key problems is the representation of assessment results. Though there exists many methods that can deal with uncertain information, however, they have more or less deficiencies. In this paper, a new representation of uncertain information, called D numbers, is presented. It extends the Dempster-Shafer theory. By using D numbers, a new method is developed for the bridge condition assessment. Compared to these existing methods, the proposed method is simpler and more effective. An illustrative case is given to show the effectiveness of the new method.

  13. Accelerated aging of polymer composite bridge materials

    Science.gov (United States)

    Carlson, Nancy M.; Blackwood, Larry G.; Torres, Lucinda L.; Rodriguez, Julio G.; Yoder, Timothy S.

    1999-05-01

    Accelerated aging research on samples of composite materials and candidate UV protective coatings is determining the effects of six environmental factors on material durability. Candidate fastener materials are being evaluated to determine corrosion rates and crevice corrosion effects at load-bearing joints. This work supports field testing of a 30-ft long, 18-ft wide polymer matrix composite (PMC) bridge at the Idaho National Engineering and Environmental Laboratory. Durability results and sensor data form test with live loads provide information required for determining the cost/benefit measures to use in life-cycle planning, determining a maintenance strategy, establishing applicable inspection techniques, and establishing guidelines, standards and acceptance criteria for PMC bridges for use in the transportation infrastructure.

  14. Tacoma Bridge Failure-- a Physical Model

    CERN Document Server

    Green, D; Green, Daniel; Unruh, William G.

    2004-01-01

    The cause of the collapse of the Tacoma Narrows Bridge has been a topic of much debate and confusion since the day it fell. Many mischaracterizations of the observed phenomena have limited the widespread understanding of the problem. Nevertheless, there has always been an abundance of evidence in favour of a negative damping model. Negative damping, or positive feedback, is responsible for many large amplitude oscillations observed in many applications. In this paper, we will explain some well-known examples of positive feedback. We will then present a feedback model, derived from fundamental physics, capable of explaining a number of features observed in the instabilities of many bridge decks. This model is supported by computational, experimental and historical data.

  15. Fatigue-Prone Details in Steel Bridges

    Directory of Open Access Journals (Sweden)

    Mohsen Heshmati

    2012-11-01

    Full Text Available This paper reviews the results of a comprehensive investigation including more than 100 fatigue damage cases, reported for steel and composite bridges. The damage cases are categorized according to types of detail. The mechanisms behind fatigue damage in each category are identified and studied. It was found that more than 90% of all reported damage cases are of deformation-induced type and generated by some kind of unintentional or otherwise overlooked interaction between different load-carrying members or systems in the bridge. Poor detailing, with unstiffened gaps and abrupt changes in stiffness at the connections between different members were also found to contribute to fatigue cracking in many details.

  16. A liquid bridge connecting moving porous surfaces

    Science.gov (United States)

    Gharib, Morteza; Gat, Amir; Navaz, Homayun

    2011-11-01

    We study the coupled problem of a liquid bridge connecting two porous surfaces where the gap between the surfaces is an externally controlled function of time. The relative motion between the surfaces affects the geometry and the pressure distribution of the liquid bridge, thus influencing the diffusion speed and penetration topology within the porous material. Utilizing the lubrication approximation and Darcy's phenomenological law we obtain a relation between the diffusion into the porous surface and the relative motion between the surfaces. A scheme to control the diffusion topology is presented and illustrated for the case of conical penetration topology with an arbitrary cone opening angle. Analytic expressions describing the penetration topology for the case of constant speed of the surfaces and the relative motion between the surfaces required to create a conical penetration topology are obtained and compared to experimental and numerical data. This project was supported by the Defense Threat Reduction Agency (DTRA), Award Number: 330233-A.

  17. Bridging the Divide between Science and Journalism

    OpenAIRE

    Marincola Francesco M; Van Eperen Laura; Strohm Jennifer

    2010-01-01

    Abstract There are countless reasons nearly every scientist should learn how to communicate effectively with the media, including increased understanding of critical research findings to attract or sustain funding and build new professional partnerships that will further propel forward research. But where do scientists begin? Bridging the Divide between Science and Journalism offers practical tips for any scientist looking to work with the media. Given the traditional and internet-based sourc...

  18. Fatigue-Prone Details in Steel Bridges

    OpenAIRE

    Mohsen Heshmati; Mohammad Al-Emrani; Reza Haghani

    2012-01-01

    This paper reviews the results of a comprehensive investigation including more than 100 fatigue damage cases, reported for steel and composite bridges. The damage cases are categorized according to types of detail. The mechanisms behind fatigue damage in each category are identified and studied. It was found that more than 90% of all reported damage cases are of deformation-induced type and generated by some kind of unintentional or otherwise overlooked interaction between different load-carr...

  19. Design of bridges against large tectonic deformation

    Institute of Scientific and Technical Information of China (English)

    I.Anastasopoulost; G.Gazetas; V.Drosos; T.Georgarakos; R.Kourkoulis

    2008-01-01

    The engineering community has devoted much effort to understanding the response of soil-structure systems to seismic ground motions,but little attention to the effects of an outcropping fault offset.The 1999 earthquakes of Turkey and Taiwan,offering a variety of case histories of structural damage due to faulting,have (re)fueled the interest on the subject.This paper presents a methodology for design of bridges against tectonic deformation.The problem is decoupled in two analysis steps:the first (at the local level) deals with the response of a single pier and its foundation to fault rupture propagating through the soil,and the superstructure is modeled in a simplified manner;and the second (at the global level)investigates detailed models of the superstructure subjected to the support (differential) displacements of Step 1.A parametric study investigates typical models of viaduct and overpass bridges,founded on piles or caissons.Fixed-head piled foundations are shown to be rather vulnerable to faulting-induced deformation.End-bearing piles in particular are unable to survive bedrock offsets exceeding 10 cm.Floating piles perform better,and if combined with hinged pile-to-cap connections,they could survive much larger offsets.Soil resilience is beneficial in reducing pile distress.Caisson foundations are almost invariably successful.Statically-indeterminate superstructures are quite vulnerable,while statically-determinate are insensitive (allowing differential displacements and rotations without suffering any distress).For large-span cantilever construction bridges,where a statically determinate system is hardly an option,inserting resilient seismic isolation bearings is advantageous as long as ample seating can prevent the deck from falling off the supports.An actual application of the developed method is presented for a major bridge,demonstrating the feasibility of design against tectonic deformation.

  20. Bridge Inspections and Being an ERC

    OpenAIRE

    Hoernschemeyer, Keith; Miller, Jessica

    2015-01-01

    This presentation will discuss recent changes to the County Bridge Inspection Program from the perspective of both the FHWA and INDOT. We will also discuss the responsibilities of the local public agency’s (LPA’s) employee in responsible charge (ERC) with respect to managing this program. As this course is a yearly requirement, all county ERCs are encouraged to attend. Pre-registering is strongly encouraged by e-mailing your contact information to .

  1. Liquid bridge simulations with OpenFOAM

    OpenAIRE

    Guirao Aguilar, Guillermo

    2011-01-01

    Any liquid-gas interface being under a temperature gradient is subject to a thermocapillary flow generated by the differences in the surface tension. In the particular case of liquid bridges, this flow can evolve into a oscillatory or travelling flow known as hydrothermal wave. This works aims to achieve a better understanding of the formation of this kind of flow by means of computational fluid dynamics techniques using a specific software package. For that, a simplified model of the liquid ...

  2. Legendrian framings for two-bridge links

    CERN Document Server

    Baader, Sebastian

    2009-01-01

    We define the Thurston-Bennequin polytope of a two-component link as the convex hull of all pairs of integers that arise as framings of a Legendrian representative. The main result of this paper is a description of the Thurston-Bennequin polytope for two-bridge links. As an application, we construct non-quasipositive surfaces in $\\R^3$ all whose sub-annuli are quasipositive.

  3. Ether bridge formation in loline alkaloid biosynthesis

    OpenAIRE

    Pan, Juan; Bhardwaj, Minakshi; Faulkner, Jerome R.; Nagabhyru, Padmaja; Charlton, Nikki D.; Higashi, Richard M.; Miller, Anne-Frances; Young, Carolyn A; Grossman, Robert B.; Schardl, Christopher L

    2013-01-01

    Lolines are potent insecticidal agents produced by endophytic fungi of cool-season grasses. These alkaloids are composed of a pyrrolizidine ring system and an uncommon ether bridge linking carbons 2 and 7. Previous results indicated that 1-aminopyrrolizidine was a pathway intermediate. We used RNA interference to knock down expression of lolO, resulting in the accumulation of a novel alkaloid identified as exo-1-acetamidopyrrolizidine based on high-resolution MS and NMR. Genomes of endophytes...

  4. Bridging the Gap: Linking Simulation and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Krajewski, Paul E.; Carsley, John; Stoudt, Mark R.; Hovanski, Yuri

    2012-09-01

    The Materials Genome Initiative (MGI) which is a key enabler for the Advanced Manufacturing Partnership, announced in 2011 by U.S. President Barack Obama, was established to accelerate the development and deployment of advanced materials. The MGI is driven by the need to "bridge the gap" between (I) experimental results and computational analysis to enable the rapid development and validation of new mateirals, and (II) the processes required to convert these materials into useable goods.

  5. 固定桥基牙牙槽骨吸收三维有限元模型的建立%Construction of a three-dimensional finite element model of the absorbed alveolar bone of fixed partial denture abutments

    Institute of Scientific and Technical Information of China (English)

    陈艳; 吴娴; 张一岭; 张翼

    2011-01-01

    目的:通过建立左侧下颌后牙5单位固定桥双基牙侧牙槽骨吸收的有限元模型,为分析双基牙侧牙槽骨吸收对牙周膜应力的影响打下基础.方法:采用多层螺旋CT扫描技术与Mimics、Ansys软件相结合对88张层厚为0.6 mm的CT断层影像进行三维重建,在此基础上建立双基牙侧牙槽骨吸收模型.结果:建立了5单位固定桥有限元模型及双基牙侧牙槽骨吸收的有限元模型,包括牙齿、牙周膜、牙槽骨.结论:所建模型结构完整,单元划分精细,能够较精确地模拟牙槽骨吸收的实体状态,为加载后的基牙牙周膜应力分析提供基础.%AIM : To construct three-dimensional finite element models ( FEMs) of five-unit fixed partial denture of left mandible so as to analyze the effects of double abutments alveolar bone resorption on periodontal ligament stress.METHODS: Eighty-eight CT slice pictures (0.6mm in thickness) were treated with multislice helical computed tomography scanning technology, Mimics and Ansys Software to build the FEMs.Then the alveolar bone of double abutments inordinately absorbed models on the basis of the FEMs was built.RESULTS : A three-dimensional FEMs of five - unit fixed partial denture and al,veolar hone resorption of double abutments model were constructed, including teeth.periodontal ligaments and alveolar bone.CONCLUSION : The constructed models had the advantages of intact structure, precise elements and can simulate the natural situation of alveolar bone resorbtion and can provide basis for further research of periodontal ligament stress induced by loading.

  6. Bridge concrete deteriorating diagnosis by infrared thermography

    Science.gov (United States)

    Shibata, Hiroki; Fukuyama, Nobuhiro; Sakuma, Joji; Mochizuki, Jun; Kimura, Yukinori

    2006-04-01

    Bridge is indispensable as social overhead capital. In the past, concrete construction was believed to be semi-permanent. Actually, however, concrete is deteriorated by various factors including seawater damage, annual temperature change, etc. Therefore, it is now obvious that maintenance and management are essential to keep performance of the bridge. In Japan, we had many reports of using infrared thermography for diagnosis of building, mainly for delamination of tile and mortar used for surface of the building for more than 10 years. In recent years, infrared thermogrephy is more actively used for delamination of surface of the bridge. Passive method is usually used for open-air concrete structure diagnosis, which utilizes intraday environmental temperature change and/or radiation energy emitted from the sun which create delta-T of delamination portion of the concrete structure. It is very important to take thermal image at right conditions. Otherwise, you may easily fall onto false diagnosis. In our presentation, many case examples and study of thermal data will be shown, which are taken at the right condition.

  7. Building water bridges in air: Electrohydrodynamics of the Floating Water Bridge

    CERN Document Server

    Marin, Alvaro G

    2010-01-01

    The interaction of electrical fields and liquids can lead to phenomena that defies intuition. Some famous examples can be found in Electrohydrodynamics as Taylor cones, whipping jets or non-coalescing drops. A less famous example is the Floating Water Bridge: a slender thread of water held between two glass beakers in which a high voltage difference is applied. Surprisingly, the water bridge defies gravity even when the beakers are separated at distances up to 2 cm. In the presentation, experimental measurements and simple models are proposed and discussed for the stability of the bridge and the source of the flow, revealing an important role of polarization forces on the stability of the water bridge. On the other hand, the observed flow can only be explained due to the non negligible free charge present in the surface. In this sense, the Floating Water Bridge can be considered as an extreme case of a leaky dielectric liquid (J. R. Melcher and G. I. Taylor, Annu. Rev. Fluid Mech., 1:111, 1969).

  8. SMART BRIDGE: A tool for estimating the military load classification of bridges using varying levels of information

    Energy Technology Data Exchange (ETDEWEB)

    Van Groningen, C.N.; Paddock, R.A.

    1997-03-01

    A major consideration in planning and executing military deployments is determining the routes available for moving troops and equipment. Part of this planning ensures that all of the bridges along the routes can support the specialized equipment needed. Because few trained and experienced bridge analysts are available, and automated tool is required to help military engineers and planners quickly and accurately determine the capacity, or the military load classification, of bridges. However, because detailed information about each bridge may not always be available, the tool also needs to include alternative methods for estimating bridge capacities. SMART BRIDGE, developed by Argonne National Laboratory, provides this capacity. The tool consists of a collection of modules that interact with each other to accommodate various bridge types, analytical techniques, and database functions. 5 refs., 6 figs., 2 tabs.

  9. The Internet Inter-Orb Protocol Security Bridge

    Directory of Open Access Journals (Sweden)

    Pawel Slowikowski

    1999-01-01

    Full Text Available In this paper, we present a security bridge for the Internet protocol of interoperability amongst CORBA objects and the Internet inter-ORB Protocol (IIOP. The bridge helps in making accessible objects in the Internet and makes possible the access control to them. The bridge was realized in the popular request broker the Visigenic's VisiBroker under Windows 95/NT and Solaris 2.X operating systems. We describe two ways of locating the bridge in the request broker. The first means uses one name domain of broker and is not transparent for client. The second one uses two name domains and provides objects protection on the level of the Naming Service and is transparent lor the client. We also describe the variant ofthe second means with using GateKeeper server to support IIOP tunneling within HTTP. We emphasize the importance of a firewall, cooperating with a bridge. which is required for the purpose of providing object protection. The paper presents an original conception of security managing, basing on the ideas of users, groups and resources defined using the standard terms of CORBA, IIOP and TCP/IP, that allows to control positively and negatively the access to classes (interfaces, objects and also to their individual methods. This conception was effectively implemented in a functioning bridge. Further chapters describe the foundations and some details of the bridge implementation sueli as the use ofthe Interface Repository, cache memory application, thread synchronization and the way of synchronization of the configuration applet with the bridge's objects. We discuss the influence of these solutions on the efficiency ofthe bridge and its source code portability. We also present the general structure of the component objects ofthe bridge with a scheme. ln the next part we characterize the implementation foundations ofthe bridge manager, realized as an applet in Java, with the stress on the possibility of the bridge configuration through the

  10. Bridges analysis, design, structural health monitoring, and rehabilitation

    CERN Document Server

    Bakht, Baidar

    2015-01-01

    This book offers a valuable guide for practicing bridge engineers and graduate students in structural engineering; its main purpose is to present the latest concepts in bridge engineering in fairly easy-to-follow terms. The book provides details of easy-to-use computer programs for: ·      Analysing slab-on-girder bridges for live load distribution. ·      Analysing slab and other solid bridge components for live load distribution. ·      Analysing and designing concrete deck slab overhangs of girder bridges under vehicular loads. ·      Determining the failure loads of concrete deck slabs of girder bridges under concentrated wheel loads. In addition, the book includes extensive chapters dealing with the design of wood bridges and soil-steel bridges. Further, a unique chapter on structural health monitoring (SHM) will help bridge engineers determine the actual load carrying capacities of bridges, as opposed to their perceived analytical capacities. The chapter addressing structures...

  11. Field Tests and Simulation of Lion-Head River Bridge

    Directory of Open Access Journals (Sweden)

    Yao-Min Fang

    2007-01-01

    Full Text Available Lion-Head River Bridge is a twin bridge in parallel position. The east-bounded was designed and constructed as a traditional prestress concrete box girder bridge with pot bearings; and the west-bounded was installed with seismic isolation devices of lead rubber bearings. The behavior of the isolated bridge is compared with that of the traditional bridge through several field tests including the ambient vibration test, the force vibration test induced by shakers, the free vibration test induced by a push and fast release system, and the truck test. The bridges suffered from various extents of damage due to the Chi-Chi and the Chi-I earthquakes of great strength during the construction and had been retrofitted. The damage was reflected by the change of the bridges' natural frequencies obtained from the ambient vibration tests. The models of the two bridges are simulated by the finite element method based on the original design drawings. Soil-structure interaction was also scrutinized in this study. The simulation was then modified based on the results from the field tests. Dynamic parameters of bridges are identified and compared with those from theoretical simulation. The efficiency is also verified to be better for an isolated bridge.

  12. Aerodynamic stability of cable-supported bridges using CFRP cables

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-jun; YING Lei-dong

    2007-01-01

    To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are designed, in which the cable's cross-sectional area is determined by the principle of equivalent axial stiffness.Numerical investigations on the aerodynamic stability of the two bridges are conducted by 3D nonlinear aerodynamic stability analysis. The results showed that as CFRP cables are used in cable-supported bridges, for suspension bridge, its aerodynamic stability is superior to that of the case using steel cables due to the great increase of the torsional frequency; for cable-stayed bridge,its aerodynamic stability is basically the same as that of the case using steel stay cables. Therefore as far as the wind stability is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable's cross-sectional area should be determined by the principle of equivalent axial stiffness.

  13. A cloud-based information repository for bridge monitoring applications

    Science.gov (United States)

    Jeong, Seongwoon; Zhang, Yilan; Hou, Rui; Lynch, Jerome P.; Sohn, Hoon; Law, Kincho H.

    2016-04-01

    This paper describes an information repository to support bridge monitoring applications on a cloud computing platform. Bridge monitoring, with instrumentation of sensors in particular, collects significant amount of data. In addition to sensor data, a wide variety of information such as bridge geometry, analysis model and sensor description need to be stored. Data management plays an important role to facilitate data utilization and data sharing. While bridge information modeling (BrIM) technologies and standards have been proposed and they provide a means to enable integration and facilitate interoperability, current BrIM standards support mostly the information about bridge geometry. In this study, we extend the BrIM schema to include analysis models and sensor information. Specifically, using the OpenBrIM standards as the base, we draw on CSI Bridge, a commercial software widely used for bridge analysis and design, and SensorML, a standard schema for sensor definition, to define the data entities necessary for bridge monitoring applications. NoSQL database systems are employed for data repository. Cloud service infrastructure is deployed to enhance scalability, flexibility and accessibility of the data management system. The data model and systems are tested using the bridge model and the sensor data collected at the Telegraph Road Bridge, Monroe, Michigan.

  14. Disulfide Bridges: Bringing Together Frustrated Structure in a Bioactive Peptide.

    Science.gov (United States)

    Zhang, Yi; Schulten, Klaus; Gruebele, Martin; Bansal, Paramjit S; Wilson, David; Daly, Norelle L

    2016-04-26

    Disulfide bridges are commonly found covalent bonds that are usually believed to maintain structural stability of proteins. Here, we investigate the influence of disulfide bridges on protein dynamics through molecular dynamics simulations on the cysteine-rich trypsin inhibitor MCoTI-II with three disulfide bridges. Correlation analysis of the reduced cyclic peptide shows that two of the three disulfide distances (Cys(11)-Cys(23) and Cys(17)-Cys(29)) are anticorrelated within ∼1 μs of bridge formation or dissolution: when the peptide is in nativelike structures and one of the distances shortens to allow bond formation, the other tends to lengthen. Simulations over longer timescales, when the denatured state is less structured, do not show the anticorrelation. We propose that the native state contains structural elements that frustrate one another's folding, and that the two bridges are critical for snapping the frustrated native structure into place. In contrast, the Cys(4)-Cys(21) bridge is predicted to form together with either of the other two bridges. Indeed, experimental chromatography and nuclear magnetic resonance data show that an engineered peptide with the Cys(4)-Cys(21) bridge deleted can still fold into its near-native structure even in its noncyclic form, confirming the lesser role of the Cys(4)-Cys(21) bridge. The results highlight the importance of disulfide bridges in a small bioactive peptide to bring together frustrated structure in addition to maintaining protein structural stability. PMID:27119635

  15. Construction and control technology of the main bridge superstructure of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Hong; Luo Chenbin; Zhang Yongtao; You Xinpeng

    2009-01-01

    The Sutong Yangtze River Bridge (short as Sutong Bridge) is now the largest span cable-stayed bridge in the world. The construction of the superstructure of the middle bridge covered several stages including erection of the big block girders for the side span, assistant span and tower area, erection of standard girders and closure of the middle span. The big block girders were hoisted by a floating crane, and the standard girders were hoisted by a double crane system on the deck. The pushing assistant method was adopted for the middle span closure construction. Furthermore, key technologies and innovative methods used in the processes of girder erection and cable assemblage in all stages were expatiated systematically. An all-stage self- adaptive geometry control method was used in the construction process. By accurately controlling the unstressed dimensions and shape of all structural components in each step, and realization that the control system and the controlled system adapt to each other, the goal was to make control of the final line shape and inner force of the bridge structure achievable. Two solutions, including GPS based and total station based dynamic geometry monitoring systems, were used to resolve the measure problem under the wide-range of wind-induced vibrations in the long cantilever state. Finally, research on the wind-induced vibration of the superstructure during the construction period was executed. Buffeting response analysis to the longest single and double cantilever states were carried out. The analysis and evaluation of wind resistance safety of the main girders under the longest single cantilever state was made, and corresponding wind resistance measures were suggested. The as-built geometric error and cable force error were controlled in a required design range, and this whole technological achievement can be a benchmark for construction of other large span cable-stayed bridges in the future.

  16. 第三磨牙倾斜不同角度对下颌双端固定桥应力的影响%Effect of different tilting angels of third molar on the stress distribution of the rigid fixed bridge in deletion of first molar and second molar in mandibular

    Institute of Scientific and Technical Information of China (English)

    张翼; 吴娴; 张一岭; 陈艳; 刘波; 廖沐莹

    2011-01-01

    Objective: To evaluate the influence of different tilting angles of the mandibular third molar on the stress distribution in the restoration, odontal tissue and periodontal membrane as bridge abutments after the restoration of fixed partial denture. Methods: Based on a 3-D finite element model of three abutments of the rigid fixed bridge in deletion of first molar and second molar in mandibular, evaluate the influence of the mandibular third molar with different tilting angles of 0°, 10°, 20°, 30° and 40° on the stress distribution in the restoration, odontal tissue and periodontal membrane by a software named Ansys. Results: When the tilting angle of third molar was increasing, the max Von Mises stresses of the restoration, odontal tissue and periodontal membrane were increasing. When third molar tilted at 30°, the Von Mises stress peak value (9.1 IMPa) on the peridental membrane of third molar was 2.4 times than the normal third molar(3.81MPa). Conclusions: The tooth tilted more than 30° could not be selected as an abutment in the restoration of fixed partial denture, and the clinicians should lower the height of the cusp to reduce the oblique load of the abutment when fixed bridge was used as a treatment%目的:下颌第一二磨牙缺失三基牙双端固定桥修复的条件下,分析近中倾斜不同角度的第三磨牙作为基牙后受力时修复体、牙体组织及牙周膜的应力分布情况,为临床修复提供理论依据.方法:在已建好的第一二磨牙缺失三基牙双端固定桥修复的三维有限元模型基础上,将第三磨牙近中倾斜0°、10°、20°、30°和40°,通过Ansys软件分析修复体、牙体以及牙周膜的应力变化情况.结果:无论是垂直加载还是倾斜加载,修复体的等效应力最大值位于第二三磨牙之间的连接体处;随着第三磨牙倾斜角度的增加,修复体、牙体以及牙周膜的等效应力极值增加.当第三磨牙倾斜30°时,垂直载荷下,第三磨

  17. Clinical evaluation of tilted implant and angled abutement.%倾斜种植体与角度基台在种植修复中的临床应用

    Institute of Scientific and Technical Information of China (English)

    铁朝荣; 张文捷; 陈建钢

    2011-01-01

    目的:观察倾斜种植体与角度基台联合应用的临床疗效,探讨相关手术和修复技巧.方法:牙列缺损(失)病例17例,倾斜植入种植体25枚,随访时间0.5~2年,观察种植体稳定性、炎症、X线改变等指标,评价临床疗效.结果:除2例种植体脱落外,其余25枚种植体均获成功,临床成功率92%.结论:倾斜种植体在骨量不足或邻牙倾斜种植修复中可发挥独特的作用.但由于倾斜种植体应力主要集中在其颈部,临床应用应以多枚种植体连冠修复为宜,以便分散应力;在无牙颌修复中,为减轻远中扭力,应尽量减少游离端长度.%Objective: To study the outcome of tilted implant and angle abutement in clinic. Method:17 patients recived 27tilted implant. In 0.5~2 years of follow-up, implant stability, inflammation, and X-rays change were obtained and assessed. Rusult:25 implant were remained, 2 implants were lost, successful rate was 92 %. Conclusion: tilted implant with angle abutement could be used in patients with inadequate bone or inclined tooth. Because the stress was located in the neck of tilted implant, It is recommended that connected tooth-tooth restorations was useful. In edentulous patients, long cantilever should be avoided.

  18. Investigation of Aerodynamic Interference of Double Deck Bridges

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC)

    2016-05-01

    Construction of a twin bridge can be a cost effective and minimally disruptive way to increase capacity when an existing bridge is not near the end of its service life. With ever growing vehicular traffic, when demand approaches the capacity of many existing roads and bridges. Remodeling a structure with an insufficient number of lanes can be a good solution in case of smaller and less busy bridges. Closing down or reducing traffic on crossings of greater importance for the construction period, however, can result in major delays and revenue loss for commerce and transportation as well as increasing the traffic load on alternate route bridges. Multiple-deck bridges may be the answer to this issue. A parallel deck can be built next to the existing one, without reducing the flow. Additionally, a new bridge can be designed as a twin or multi-deck structure. Several such structures have been built throughout the United States, among them: - The New NY Bridge Project - the Tappan Zee Hudson River Crossing, - SR-182 Columbia River Bridge, - The Thaddeus Kosciusko Bridge (I-87), - The Allegheny River Bridge, Pennsylvania, which carries I76, - Fred Hartman Bridge, TX, see Figure 1.2. With a growing number of double deck bridges, additional, more detailed, studies on the interaction of such bridge pairs in windy conditions appears appropriate. Aerodynamic interference effects should be examined to assure the aerodynamic stability of both bridges. There are many studies on aerodynamic response of single deck bridges, but the literature on double-deck structures is not extensive. The experimental results from wind tunnels are still limited in number, as a parametric study is required, they can be very time consuming. Literature review shows that some investigation of the effects of gap-width and angle of wind incidence has been done. Most of the CFD computational studies that have been done were limited to 2D simulations. Therefore, it is desirable to investigate twin decks

  19. Structural safety monitoring for Nanjing Yangtze River Bridge

    Institute of Scientific and Technical Information of China (English)

    黄方林; 何旭辉; 陈政清; 曾储惠

    2004-01-01

    In order to evaluate objectively and accurately the integrity, safety and operating conditions in real time for the Nanjing Yangtze River Bridge, a large structural safety monitoring system was described. The monitoring system is composed of three parts: sensor system, signal sampling and processing system, and safety monitoring and assessment system. Combining theoretical analysis with measured data analysis, main monitoring contents and layout of measuring points were determined. The vibration response monitoring was significantly investigated. The main contents of safety monitoring on vibration response monitoring are vibration of the main body of the Nanjing Yangtze river bridge, collision avoidance of the bridge piers, vibration of girders on high piers for the bridge approach and earthquake. As a field laboratory, the safety monitorying system also provides information to investigate the unknown and indeterminate problems on bridge structures and specific environment around bridges.

  20. Development of a nondestructive evaluation method for FRP bridge decks

    Science.gov (United States)

    Brown, Jeff; Fox, Terra

    2010-05-01

    Open steel grids are typically used on bridges to minimize the weight of the bridge deck and wearing surface. These grids, however, require frequent maintenance and exhibit other durability concerns related to fatigue cracking and corrosion. Bridge decks constructed from composite materials, such as a Fiber-reinforced Polymer (FRP), are strong and lightweight; they also offer improved rideability, reduced noise levels, less maintenance, and are relatively easy to install compared to steel grids. This research is aimed at developing an inspection protocol for FRP bridge decks using Infrared thermography. The finite element method was used to simulate the heat transfer process and determine optimal heating and data acquisition parameters that will be used to inspect FRP bridge decks in the field. It was demonstrated that thermal imaging could successfully identify features of the FRP bridge deck to depths of 1.7 cm using a phase analysis process.