A Bridge to the Future

ERIC Educational Resources Information Center

Anderson, Richard

2008-01-01

Career and technical education (CTE) has a promising future at Darlington (WI) High School. In this article, the author describes how a class bridge project became a real-world, project-based learning opportunity involving higher-level thinking skills that are at the core of CTE at his school. It began when a local citizen approached him at the…

THE BRIDGE PROJECT FOLLOWUP STUDY.

ERIC Educational Resources Information Center

GREENBERG, HAROLD; AND OTHERS

AN EXPERIMENT CONDUCTED AT THE JUNIOR HIGH SCHOOL LEVEL IN NEW YORK CITY TO EVALUATE THE EFFECTIVENESS OF A NEW KIND OF LEARNING ENVIRONMENT ON THE EDUCATION OF DISADVANTAGED YOUTH WAS UNDERTAKEN AS A FOLLOWUP TO THE "BRIDGE" PROJECT. THE FUNDAMENTALS INVOLVED USING A NEW TYPE OF TEAM-TEACHING INSTRUCTION IN THE AREAS OF ENGLISH,…

Monitoring and Risk Identification Caused by High Water, Floods and Erosion Processes in Urban Part of Sava Riverbed

NASA Astrophysics Data System (ADS)

Oskoruš, D.; Miković, N.; Ljevar, I.

2012-04-01

Riverbed erosion and bottom deepening are part of natural fluvial processes in the upper stream of Sava River. The increasing gradient of those changes is interconnected with the level of human influence in the river basin and riverbed as well. In time period of last forty years the consequences of riverbed erosion are become serious as well as dangerous and they threaten the stability of hydro technical structures. The increasing value of flow velocity in riverbed in urban part of river section during high water level, mud and debris flow during the floods as well, is especially dangerous for old bridges. This paper contains result of velocity measurements during high waters taken by Hydrological Service of Republic Croatia, load transport monitoring during such events and cross sections in some vulnerable location. In this paper is given one example of Jakuševac railway bridge in Zagreb, heavily destroyed during high water event on the 30 March 2009., recently reconstructed by "Croatian Railways" company. Keywords: Riverbed erosion, flow velocity, mud and debris flow, risk identification, stability of bridges

Fiber grating systems for traffic monitoring

NASA Astrophysics Data System (ADS)

Udd, Eric; Kunzler, Marley; Laylor, Harold M.; Schulz, Whitten L.; Kreger, Stephen T.; Corones, John C.; McMahon, Robert; Soltesz, Steven M.; Edgar, Robert

2001-08-01

Blue Road Research has designed, built, and installed fiber grating sensor systems onto bridges, and most recently into an asphalt and concrete highway test pad. The sensitivity levels of the fiber grating sensors are sufficiently high to enable detection of people standing on the bridge or highway. This paper briefly overviews the usage of these sensors for traffic monitoring.

Cycling firing method for bypass operation of bridge converters

DOEpatents

Zabar, Zivan

1982-01-01

The bridge converter comprises a number of switching elements and an electronic logic system which regulated the electric power levels by controlling the firing, i.e., the initiation of the conduction period of the switching elements. Cyclic firing of said elements allows the direct current to bypass the alternating current system with high power factor and negligible losses.

A passive dual-circulator based transmit/receive switch for use with reflection resonators in pulse EPR

PubMed Central

Subramanian, V. S.; Epel, Boris; Mailer, Colin; Halpern, Howard J.

2009-01-01

In order to protect the low noise amplifier (LNA) in the receive arm of a pulsed 250 MHz EPR bridge, it is necessary to install as much isolation as possible between the power exciting the spin system and the LNA when high power is present in the receive arm of the bridge, while allowing the voltage induced by the magnetization in the spin sample to be passed undistorted and undiminished to the LNA once power is reduced below the level that can cause a LNA damage. We discuss a combination of techniques to accomplish this involving the power-routing circulator in the bridge, a second circulator acting as an isolator with passive shunt PIN diodes immediately following the second circulator. The low resistance of the forward biased PIN diode passively generates an impedance mismatch at the second circulator output port during the high power excitation pulse and resonator ring down. The mismatch reflects the high power to the remaining port of the second circulator, dumping it into a system impedance matched load. Only when the power diminishes below the diode conduction threshold will the resistance of the PIN diode rise to a value much higher than the system impedance. This brings the device into conduction mode. We find that the present design passively limits the output power to 14 dBm independent of the input power. For high input power levels the isolation may exceed 60 dB. This level of isolation is sufficient to fully protect the LNA of pulse EPR bridge. PMID:20052312

A 12-year National Study of Suicide by Jumping From Bridges in Norway.

PubMed

Sæheim, Aleksandra; Hestetun, Ingebjørg; Mork, Erlend; Nrugham, Latha; Mehlum, Lars

2017-01-01

Studies from several countries suggest that erecting fences on bridges more commonly used for suicide by jumping may be an effective way of reducing the risk of suicide by jumping from these bridges. Distribution of suicides by jumping off bridges has not yet been studied on a national level in any country. This study included all suicides by jumping from high places registered in the Norwegian Cause of Death Registry (COD) in the period 1999-2010 (n = 319). Combining data from the COD registry and information from police records, 71 cases of suicide by jumping off a bridge were identified involving 36 bridges. This form of suicide constituted approximately 1% of all suicides in Norway in the period 1999-2010. Almost half of these suicides were registered at only 6 bridges. Three Norwegian bridges were secured during the observation period of this study. Two bridges had barriers installed on the full length of the bridge with 11 suicides registered before barriers were installed, and none after. On the 1 bridge that was only partially secured, no change in numbers of suicides was observed after barriers were installed. One-third of jumps from bridges occurred over land. We found that although suicide by jumping off bridges was a relatively rare event, there is a potential for saving lives by installing physical barriers on bridges that are more commonly used for suicide by jumping.

Big data and high-performance analytics in structural health monitoring for bridge management

NASA Astrophysics Data System (ADS)

Alampalli, Sharada; Alampalli, Sandeep; Ettouney, Mohammed

2016-04-01

Structural Health Monitoring (SHM) can be a vital tool for effective bridge management. Combining large data sets from multiple sources to create a data-driven decision-making framework is crucial for the success of SHM. This paper presents a big data analytics framework that combines multiple data sets correlated with functional relatedness to convert data into actionable information that empowers risk-based decision-making. The integrated data environment incorporates near real-time streams of semi-structured data from remote sensors, historical visual inspection data, and observations from structural analysis models to monitor, assess, and manage risks associated with the aging bridge inventories. Accelerated processing of dataset is made possible by four technologies: cloud computing, relational database processing, support from NOSQL database, and in-memory analytics. The framework is being validated on a railroad corridor that can be subjected to multiple hazards. The framework enables to compute reliability indices for critical bridge components and individual bridge spans. In addition, framework includes a risk-based decision-making process that enumerate costs and consequences of poor bridge performance at span- and network-levels when rail networks are exposed to natural hazard events such as floods and earthquakes. Big data and high-performance analytics enable insights to assist bridge owners to address problems faster.

Radio Hazard Safety Assessment for Marine Ship Transmitters: Measurements Using a New Data Collection Method and Comparison with ICNIRP and ARPANSA Limits

PubMed Central

Halgamuge, Malka N.

2015-01-01

We investigated the levels of radio frequency electromagnetic fields (RF EMFs) emitted from marine ship transmitters. In this study, we recorded the radio frequency (RF) electric field (EF) levels emitted from transmitters from a marine vessel focusing on the areas normally occupied by crew members and passengers. Previous studies considered radiation hazard safety assessment for marine vessels with a limited number of transmitters, such as very high-frequency (VHF) transceivers, radar and communication transmitters. In our investigation, EF levels from seven radio transmitters were measured, including: VHF, medium frequency/high frequency (MF/HF), satellite communication (Sat-Com C), AISnavigation, radar X-band and radar S-band. Measurements were carried out in a 40 m-long, three-level ship (upper deck, bridge deck and bridge roof) at 12 different locations. We developed a new data-collection protocol and performed it under 11 different scenarios to observe and measure the radiation emissions from all of the transmitters. In total, 528 EF field measurements were collected and averaged over all three levels of the marine ship with RF transmitters: the measured electric fields were the lowest on the upper deck (0.82–0.86 V/m), the highest on the bridge roof (2.15–3.70 V/m) and in between on the bridge deck (0.47–1.15 V/m). The measured EF levels were then assessed for compliance with the occupational and general public reference levels of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) standards. The ICNIRP and the ARPANSA limits for the general public were exceeded on the bridge roof; nevertheless, the occupational limits were respected everywhere. The measured EF levels, hence, complied with the ICNIRP guidelines and the ARPANSA standards. In this paper, we provide a new data collection model for future surveys, which could be conducted with larger samples to verify our observations. Furthermore, this new method could be useful as a reference for researchers and industry professionals without direct access to the necessary equipment. PMID:25996887

Are polynuclear superhalogens without halogen atoms probable? A high-level ab initio case study on triple-bridged binuclear anions with cyanide ligands

NASA Astrophysics Data System (ADS)

Yin, Bing; Li, Teng; Li, Jin-Feng; Yu, Yang; Li, Jian-Li; Wen, Zhen-Yi; Jiang, Zhen-Yi

2014-03-01

The first theoretical exploration of superhalogen properties of polynuclear structures based on pseudohalogen ligand is reported here via a case study on eight triply-bridged [Mg2(CN)5]- clusters. From our high-level ab initio results, all these clusters are superhalogens due to their high vertical electron detachment energies (VDE), of which the largest value is 8.67 eV at coupled-cluster single double triple (CCSD(T)) level. Although outer valence Green's function results are consistent with CCSD(T) in most cases, it overestimates the VDEs of three anions dramatically by more than 1 eV. Therefore, the combined usage of several theoretical methods is important for the accuracy of purely theoretical prediction of superhalogen properties of new structures. Spatial distribution of the extra electron of high-VDE anions here indicates two features: remarkable aggregation on bridging CN units and non-negligible distribution on every CN unit. These two features lower the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to detachment of CN-1 were also investigated for these anions. The collection of these results indicates that polynuclear structures based on pseudohalogen ligand are promising candidates for new superhalogens with enhanced properties.

Are polynuclear superhalogens without halogen atoms probable? A high-level ab initio case study on triple-bridged binuclear anions with cyanide ligands.

PubMed

Yin, Bing; Li, Teng; Li, Jin-Feng; Yu, Yang; Li, Jian-Li; Wen, Zhen-Yi; Jiang, Zhen-Yi

2014-03-07

The first theoretical exploration of superhalogen properties of polynuclear structures based on pseudohalogen ligand is reported here via a case study on eight triply-bridged [Mg2(CN)5](-) clusters. From our high-level ab initio results, all these clusters are superhalogens due to their high vertical electron detachment energies (VDE), of which the largest value is 8.67 eV at coupled-cluster single double triple (CCSD(T)) level. Although outer valence Green's function results are consistent with CCSD(T) in most cases, it overestimates the VDEs of three anions dramatically by more than 1 eV. Therefore, the combined usage of several theoretical methods is important for the accuracy of purely theoretical prediction of superhalogen properties of new structures. Spatial distribution of the extra electron of high-VDE anions here indicates two features: remarkable aggregation on bridging CN units and non-negligible distribution on every CN unit. These two features lower the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to detachment of CN(-1) were also investigated for these anions. The collection of these results indicates that polynuclear structures based on pseudohalogen ligand are promising candidates for new superhalogens with enhanced properties.

Ecological bridges and barriers in pelagic ecosystems

NASA Astrophysics Data System (ADS)

Briscoe, Dana K.; Hobday, Alistair J.; Carlisle, Aaron; Scales, Kylie; Eveson, J. Paige; Arrizabalaga, Haritz; Druon, Jean Noel; Fromentin, Jean-Marc

2017-06-01

Many highly mobile species are known to use persistent pathways or corridors to move between habitat patches in which conditions are favorable for particular activities, such as breeding or foraging. In the marine realm, environmental variability can lead to the development of temporary periods of anomalous oceanographic conditions that can connect individuals to areas of habitat outside a population's usual range, or alternatively, restrict individuals from areas usually within their range, thus acting as ecological bridges or ecological barriers. These temporary features can result in novel or irregular trophic interactions and changes in population spatial dynamics, and, therefore, may have significant implications for management of marine ecosystems. Here, we provide evidence of ecological bridges and barriers in different ocean regions, drawing upon five case studies in which particular oceanographic conditions have facilitated or restricted the movements of individuals from highly migratory species. We discuss the potential population-level significance of ecological bridges and barriers, with respect to the life history characteristics of different species, and inter- and intra-population variability in habitat use. Finally, we summarize the persistence of bridge dynamics with time, our ability to monitor bridges and barriers in a changing climate, and implications for forecasting future climate-mediated ecosystem change.

BUILDING A BETTER GLUTEAL BRIDGE: ELECTROMYOGRAPHIC ANALYSIS OF HIP MUSCLE ACTIVITY DURING MODIFIED SINGLE-LEG BRIDGES.

PubMed

Lehecka, B J; Edwards, Michael; Haverkamp, Ryan; Martin, Lani; Porter, Kambry; Thach, Kailey; Sack, Richard J; Hakansson, Nils A

2017-08-01

Gluteal strength plays a role in injury prevention, normal gait patterns, eliminating pain, and enhancing athletic performance. Research shows high gluteal muscle activity during a single-leg bridge compared to other gluteal strengthening exercises; however, prior studies have primarily measured muscle activity with the active lower extremity starting in 90 ° of knee flexion with an extended contralateral knee. This standard position has caused reports of hamstring cramping, which may impede optimal gluteal strengthening. The purpose of this study was to determine which modified position for the single-leg bridge is best for preferentially activating the gluteus maximus and medius. Cross-Sectional. Twenty-eight healthy males and females aged 18-30 years were tested in five different, randomized single-leg bridge positions. Electromyography (EMG) electrodes were placed on subjects' gluteus maximus, gluteus medius, rectus femoris, and biceps femoris of their bridge leg (i.e., dominant or kicking leg), as well as the rectus femoris of their contralateral leg. Subjects performed a maximal voluntary isometric contraction (MVIC) for each tested muscle prior to performing five different bridge positions in randomized order. All bridge EMG data were normalized to the corresponding muscle MVIC data. A modified bridge position with the knee of the bridge leg flexed to 135 ° versus the traditional 90 ° of knee flexion demonstrated preferential activation of the gluteus maximus and gluteus medius compared to the traditional single-leg bridge. Hamstring activation significantly decreased (p < 0.05) when the dominant knee was flexed to 135 ° (23.49% MVIC) versus the traditional 90 ° (75.34% MVIC), while gluteal activation remained similarly high (51.01% and 57.81% MVIC in the traditional position, versus 47.35% and 57.23% MVIC in the modified position for the gluteus maximus and medius, respectively). Modifying the traditional single-leg bridge by flexing the active knee to 135 ° instead of 90 ° minimizes hamstring activity while maintaining high levels of gluteal activation, effectively building a bridge better suited for preferential gluteal activation. 3.

4. A river level view of the Broad Street bridge ...

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

4. A river level view of the Broad Street bridge and Columbus skyline from the railroad truss north of the bridge. - Broad Street Bridge, Spanning Scioto River at U.S. Route 40 (Broad Street), Columbus, Franklin County, OH

Precision liquid level sensor

DOEpatents

Field, M.E.; Sullivan, W.H.

A precision liquid level sensor utilizes a balanced bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

Implementation of Teacher Consultation and Coaching in Urban Schools: A Mixed Method Study

PubMed Central

Cappella, Elise; Jackson, Daisy R.; Kim, Ha Yeon; Bilal, Caroline; Holland, Sibyl; Atkins, Marc S.

2015-01-01

Guided by implementation science scholarship and school mental health research, the current study uses qualitative and quantitative data to illuminate the barriers, opportunities, and processes underlying the implementation of a teacher consultation and coaching model (BRIDGE) in urban elementary schools. Data come from five public elementary schools, 12 school mental health staff (BRIDGE consultants), and 18 teachers participating in a classroom-randomized trial of BRIDGE. Findings from directed content analysis of teacher focus group and interview data suggest that aspects of the BRIDGE intervention model, school organization and classroom contexts, and teachers/consultants and their relationship were relevant as implementation facilitators or barriers. In addition, case study analysis of intervention materials and fidelity tools from classrooms with moderate-to-high dosage and adherence suggest variation in consultation and coaching by initial level of observed classroom need. Results illuminate the need for implementation research to extend beyond simple indicators of fidelity to the multiple systems and variation in processes at play across levels of the implementation context. PMID:27293490

Precision liquid level sensor

DOEpatents

Field, Michael E.; Sullivan, William H.

1985-01-01

A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge.

Investigation of Thermocapillary Convection of High Prandtl Number Fluid Under Microgravity

NASA Technical Reports Server (NTRS)

Liang, Ruquan; Duan, Guangdong

2012-01-01

Thermocapillary convection in a liquid bridge, which is suspended between two coaxial disks under zero gravity, has been investigated numerically. The Navier-Stokes equations coupled with the energy conservation equation are solved on a staggered grid, and the level set approach is used to capture the free surface deformation of the liquid bridge. The velocity and temperature distributions inside the liquid bridge are analyzed. It is shown from this work that as the development of the thermocapillary convection, the center of the vortex inside the liquid bridge moves down and reaches an equilibrium position gradually. The temperature gradients in the regions near the upper center axis and the bottom cold corner are higher than those in the other regions.

Precision liquid level sensor

DOEpatents

Field, M.E.; Sullivan, W.H.

1985-01-29

A precision liquid level sensor utilizes a balanced R. F. bridge, each arm including an air dielectric line. Changes in liquid level along one air dielectric line imbalance the bridge and create a voltage which is directly measurable across the bridge. 2 figs.

Potential-scour assessments and estimates of scour depth using different techniques at selected bridge sites in Missouri

USGS Publications Warehouse

Huizinga, Richard J.; Rydlund, Jr., Paul H.

2004-01-01

The evaluation of scour at bridges throughout the state of Missouri has been ongoing since 1991 in a cooperative effort by the U.S. Geological Survey and Missouri Department of Transportation. A variety of assessment methods have been used to identify bridges susceptible to scour and to estimate scour depths. A potential-scour assessment (Level 1) was used at 3,082 bridges to identify bridges that might be susceptible to scour. A rapid estimation method (Level 1+) was used to estimate contraction, pier, and abutment scour depths at 1,396 bridge sites to identify bridges that might be scour critical. A detailed hydraulic assessment (Level 2) was used to compute contraction, pier, and abutment scour depths at 398 bridges to determine which bridges are scour critical and would require further monitoring or application of scour countermeasures. The rapid estimation method (Level 1+) was designed to be a conservative estimator of scour depths compared to depths computed by a detailed hydraulic assessment (Level 2). Detailed hydraulic assessments were performed at 316 bridges that also had received a rapid estimation assessment, providing a broad data base to compare the two scour assessment methods. The scour depths computed by each of the two methods were compared for bridges that had similar discharges. For Missouri, the rapid estimation method (Level 1+) did not provide a reasonable conservative estimate of the detailed hydraulic assessment (Level 2) scour depths for contraction scour, but the discrepancy was the result of using different values for variables that were common to both of the assessment methods. The rapid estimation method (Level 1+) was a reasonable conservative estimator of the detailed hydraulic assessment (Level 2) scour depths for pier scour if the pier width is used for piers without footing exposure and the footing width is used for piers with footing exposure. Detailed hydraulic assessment (Level 2) scour depths were conservatively estimated by the rapid estimation method (Level 1+) for abutment scour, but there was substantial variability in the estimates and several substantial underestimations.

Simplified bridge load rating methodology using the national bridge inventory file : user manual

DOT National Transportation Integrated Search

1988-08-01

The purpose of this research was to develop a computerized system to determine the adequacy of a bridge or group of bridges to carry specified overload vehicles. The system utilizes two levels of analysis. The Level 1 analysis is the basic rating sys...

Simplified bridge load rating methodology using the national bridge inventory file : program listing

DOT National Transportation Integrated Search

1987-08-01

The purpose of this research was to develop a computerized system to determine the adequacy of a bridge or group of bridges to carry specified overload vehicles. The system utilizes two levels of analysis. The Level 1 analysis is the basic rating sys...

How useful is determination of anti-factor Xa activity to guide bridging therapy with enoxaparin? A pilot study.

PubMed

Hammerstingl, Christoph; Omran, Heyder; Tripp, Christian; Poetzsch, Bernd

2009-02-01

Low-molecular-weight heparins (LMWH) are commonly used as peri-procedural bridging anticoagulants. The usefulness of measurement of anti-factor Xa activity (anti-Xa) to guide bridging therapy with LMWH is unknown. It was the objective of this study to determine levels of anti-Xa during standard bridging therapy with enoxaparin, and to examine predictors for residual anti-Xa. Consecutive patients receiving enoxaparin at a dosage of 1 mg/kg body weight/12 hours for temporary interruption of phenprocoumon were prospectively enrolled to the study. Blood-samples were obtained 14 hours after LMWH-application immediately pre- procedurally. Procedural details, clinical and demographic data were collected and subsequently analyzed. Seventy patients were included (age 75.2 +/- 10.8 years, Cr Cl 55.7 +/- 21.7ml/min, body mass index [BMI] 27.1 +/- 4.9). LMWH- therapy was for a mean of 4.2 +/- 1.6 days; overall anti-Xa was 0.58 +/- 0.32 U/ml. In 37 (52.8%) of patients anti-Xa was > or U/ml, including 10 (14.3%) patients with anti-Xa > 1U/ml. Linear regression analysis of single variables and logistic multivariable regression analysis failed to prove a correlation between anti-Xa and single or combined factors. No major bleeding, no thromboembolism and four (5.7%) minor haemorrhages were observed. When bridging OAC with therapeutic doses of enoxaparin a high percentage of patients undergo interventions with high residual anti-Xa. The levels of anti-Xa vary largely and are independent of single or combined clinical variables. Since the anti-Xa-related outcome of patients receiving bridging therapy with LMWH is not investigated, no firm recommendation on the usefulness of monitoring of anti-Xa can be given at this stage.

Linear beam raster magnet driver based on H-bridge technique

DOEpatents

Sinkine, Nikolai I.; Yan, Chen; Apeldoorn, Cornelis; Dail, Jeffrey Glenn; Wojcik, Randolph Frank; Gunning, William

2006-06-06

An improved raster magnet driver for a linear particle beam is based on an H-bridge technique. Four branches of power HEXFETs form a two-by-two switch. Switching the HEXFETs in a predetermined order and at the right frequency produces a triangular current waveform. An H-bridge controller controls switching sequence and timing. The magnetic field of the coil follows the shape of the waveform and thus steers the beam using a triangular rather than a sinusoidal waveform. The system produces a raster pattern having a highly uniform raster density distribution, eliminates target heating from non-uniform raster density distributions, and produces higher levels of beam current.

Parryville Bridge (S.R. 2008, section 01B Bridge) looking north across ...

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

Parryville Bridge (S.R. 2008, section 01B Bridge) looking north across traffic level, showing village of Parryville. - Parryville Bridge, State Route 2008 over Pohapoco Creek, Parryville, Carbon County, PA

Creosote retention levels of timber highway bridge superstructures in Michigan’s Lower Peninsula.

Treesearch

James P. Wacker; Douglas M. Crawford; Merv O. Eriksson

2003-01-01

Environmental concerns about preservative bleeding (or migrating) from timber bridges have increased in recent years. This preliminary study examined the creosote retention levels at six timber highway bridges in Michigan's lower peninsula during the summer of 2000. Several test core samples were removed from the bridge superstructures (four bleeders and two...

Identifying hidden sexual bridging communities in Chicago.

PubMed

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-average AIDS prevalence, above-average bridging and AIDS prevalence, and above-average bridging and below-average AIDS prevalence (hidden bridgers). The majority of the 1,068 study participants were male (63%), African American (74%), and very poor, and the median age was 44 years. Most (85%) were sexually active, and 725 provided useable geographic information regarding 1,420 sexual partnerships that involved 57 Chicago community areas. Eight community areas met or came close to meeting the definition of hidden bridgers. Six areas were near the city's periphery, and all eight areas likely had high inflows or outflows of low-income persons displaced by gentrification. The results suggest that further research on this method is warranted, and we propose a means for public health officials in other cities to duplicate the analysis.

Estimation of potential bridge scour at bridges on state routes in South Dakota, 2003-07

USGS Publications Warehouse

Thompson, Ryan F.; Fosness, Ryan L.

2008-01-01

Flowing water can erode (scour) soils and cause structural failure of a bridge by exposing or undermining bridge foundations (abutments and piers). A rapid scour-estimation technique, known as the level-1.5 method and developed by the U.S. Geological Survey, was used to evaluate potential scour at bridges in South Dakota in a study conducted in cooperation with the South Dakota Department of Transportation. This method was used during 2003-07 to estimate scour for the 100-year and 500-year floods at 734 selected bridges managed by the South Dakota Department of Transportation on State routes in South Dakota. Scour depths and other parameters estimated from the level-1.5 analyses are presented in tabular form. Estimates of potential contraction scour at the 734 bridges ranged from 0 to 33.9 feet for the 100-year flood and from 0 to 35.8 feet for the 500-year flood. Abutment scour ranged from 0 to 36.9 feet for the 100-year flood and from 0 to 45.9 feet for the 500-year flood. Pier scour ranged from 0 to 30.8 feet for the 100-year flood and from 0 to 30.7 feet for the 500-year flood. The scour depths estimated by using the level-1.5 method can be used by the South Dakota Department of Transportation and others to identify bridges that may be susceptible to scour. Scour at 19 selected bridges also was estimated by using the level-2 method. Estimates of contraction, abutment, and pier scour calculated by using the level-1.5 and level-2 methods are presented in tabular and graphical formats. Compared to level-2 scour estimates, the level-1.5 method generally overestimated scour as designed, or in a few cases slightly underestimated scour. Results of the level-2 analyses were used to develop regression equations for change in head and average velocity through the bridge opening. These regression equations derived from South Dakota data are compared to similar regression equations derived from Montana and Colorado data. Future level-1.5 scour investigations in South Dakota may benefit from the use of these South Dakota-specific regression equations for estimating change in stream head and average velocity at the bridge.

Hydrodynamic Influence Dabanhu River Bridge Holes Widening Based on Two-Dimensional Finite Element Numerical Model

NASA Astrophysics Data System (ADS)

Li, Dong Feng; Bai, Fu Qing; Nie, Hui

2018-06-01

In order to analyze the influence of bridge holes widening on hydrodynamic such as water level, a two-dimensional mathematical model was used to calculate the hydrodynamic factors, river network flow velocity vector distribution is given, water level and difference of bridge widening before and after is calculated and charted, water surface gradient in seven different river sections near the upper reaches of bridges is counted and revealed. The results of hydrodynamic calculation indicate that The Maximum and the minimum deducing numerical value of the water level after bridge widening is 0.028m, and 0.018m respective. the seven sections water surface gradient becomes smaller until it becomes negative, the influence of bridge widening on the upstream is basically over, the range of influence is about 450m from the bridge to the upstream. reach

Noise Exposure on a Warship during Firing of a Heavy Machine Gun.

PubMed

Paddan, Gurmail S

2015-11-01

Sound pressure levels were measured on a military ship during firing of a Heavy Machine Gun (HMG). Measurements were made at three locations on the ship's bridge (the wheelhouse) and one location on the starboard bridge wing. The highest peak sound pressure levels measured on the bridge wing and on the bridge were 160.7 dB(C) (2170 Pa) and 122.7 dB(C) (27.3 Pa), respectively. The highest sound exposure levels measured on the bridge wing and on the bridge corresponding to one round being fired were 127.8 dB(A) and 88.9 dB(A), respectively. The ship's structure provided about 40 dB attenuation in the transmitted noise. The operator of the weapon would be required to wear some form of hearing protection. Based on the measured peak noise levels, there would be no requirement for bridge crew to wear any hearing protection during firing of a HMG. However, crew exposure to noise on the bridge is likely to exceed the upper exposure action value corresponding to 85 dB(A) after about 11 750 rounds. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

5. View showing Crooked River High Bridge in background and ...

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

5. View showing Crooked River High Bridge in background and Ralph Modjeski railroad bridge in foreground - Crooked River High Bridge, Spanning Crooked River Gorge at Dalles-California Highway, Terrebonne, Deschutes County, OR

Real-time seismic monitoring of the integrated cape girardeau bridge array and recorded earthquake response

USGS Publications Warehouse

Celebi, M.

2006-01-01

This paper introduces the state of the art, real-time and broad-band seismic monitoring network implemented for the 1206 m [3956 ft] long, cable-stayed Bill Emerson Memorial Bridge in Cape Girardeau (MO), a new Mississippi River crossing, approximately 80 km from the epicentral region of the 1811-1812 New Madrid earthquakes. The bridge was designed for a strong earthquake (magnitude 7.5 or greater) during the design life of the bridge. The monitoring network comprises a total of 84 channels of accelerometers deployed on the superstructure, pier foundations and at surface and downhole free-field arrays of the bridge. The paper also presents the high quality response data obtained from the network. Such data is aimed to be used by the owner, researchers and engineers to assess the performance of the bridge, to check design parameters, including the comparison of dynamic characteristics with actual response, and to better design future similar bridges. Preliminary analyses of ambient and low amplitude small earthquake data reveal specific response characteristics of the bridge and the free-field. There is evidence of coherent tower, cable, deck interaction that sometimes results in amplified ambient motions. Motions at the lowest tri-axial downhole accelerometers on both MO and IL sides are practically free from any feedback from the bridge. Motions at the mid-level and surface downhole accelerometers are influenced significantly by feedback due to amplified ambient motions of the bridge. Copyright ASCE 2006.

Bridging: Locating Critical Connectors in a Network

PubMed Central

Valente, Thomas W.; Fujimoto, Kayo

2010-01-01

This paper proposes several measures for bridging in networks derived from Granovetter's (1973) insight that links which reduce distances in a network are important structural bridges. Bridging is calculated by systematically deleting links and calculating the resultant changes in network cohesion (measured as the inverse average path length). The average change for each node's links provides an individual level measure of bridging. We also present a normalized version which controls for network size and a network level bridging index. Bridging properties are demonstrated on hypothetical networks, empirical networks, and a set of 100 randomly generated networks to show how the bridging measure correlates with existing network measures such as degree, personal network density, constraint, closeness centrality, betweenness centrality, and vitality. Bridging and the accompanying methodology provide a family of new network measures useful for studying network structure, network dynamics, and network effects on substantive behavioral phenomenon. PMID:20582157

Several N-Glycans on the HIV Envelope Glycoprotein gp120 Preferentially Locate Near Disulphide Bridges and Are Required for Efficient Infectivity and Virus Transmission.

PubMed

Mathys, Leen; Balzarini, Jan

2015-01-01

The HIV envelope glycoprotein gp120 contains nine disulphide bridges and is highly glycosylated, carrying on average 24 N-linked glycans. Using a probability calculation, we here demonstrate that there is a co-localization of disulphide bridges and N-linked glycans in HIV-1 gp120, with a predominance of N-linked glycans in close proximity to disulphide bridges, at the C-terminal side of the involved cysteines. Also, N-glycans are frequently found immediately adjacent to disulphide bridges in gp120 at the N-terminal side of the involved cysteines. In contrast, N-glycans at positions close to, but not immediately neighboring disulphide bridges seem to be disfavored at the N-terminal side of the involved cysteines. Such a pronounced co-localization of disulphide bridges and N-glycans was also found for the N-glycans on glycoprotein E1 of the hepatitis C virus (HCV) but not for other heavily glycosylated proteins such as E2 from HCV and the surface GP from Ebola virus. The potential functional role of the presence of N-glycans near disulphide bridges in HIV-1 gp120 was studied using site-directed mutagenesis, either by deleting conserved N-glycans or by inserting new N-glycosylation sites near disulphide bridges. The generated HIV-1NL4.3 mutants were subjected to an array of assays, determining the envelope glycoprotein levels in mutant viral particles, their infectivity and the capture and transmission efficiencies of mutant virus particles by DC-SIGN. Three N-glycans located nearby disulphide bridges were found to be crucial for the preservation of several of these functions of gp120. In addition, introduction of new N-glycans upstream of several disulphide bridges, at locations where there was a significant absence of N-glycans in a broad variety of virus strains, was found to result in a complete loss of viral infectivity. It was shown that the N-glycan environment around well-defined disulphide bridges of gp120 is highly critical to allow efficient viral infection and transmission.

Several N-Glycans on the HIV Envelope Glycoprotein gp120 Preferentially Locate Near Disulphide Bridges and Are Required for Efficient Infectivity and Virus Transmission

PubMed Central

Mathys, Leen; Balzarini, Jan

2015-01-01

The HIV envelope glycoprotein gp120 contains nine disulphide bridges and is highly glycosylated, carrying on average 24 N-linked glycans. Using a probability calculation, we here demonstrate that there is a co-localization of disulphide bridges and N-linked glycans in HIV-1 gp120, with a predominance of N-linked glycans in close proximity to disulphide bridges, at the C-terminal side of the involved cysteines. Also, N-glycans are frequently found immediately adjacent to disulphide bridges in gp120 at the N-terminal side of the involved cysteines. In contrast, N-glycans at positions close to, but not immediately neighboring disulphide bridges seem to be disfavored at the N-terminal side of the involved cysteines. Such a pronounced co-localization of disulphide bridges and N-glycans was also found for the N-glycans on glycoprotein E1 of the hepatitis C virus (HCV) but not for other heavily glycosylated proteins such as E2 from HCV and the surface GP from Ebola virus. The potential functional role of the presence of N-glycans near disulphide bridges in HIV-1 gp120 was studied using site-directed mutagenesis, either by deleting conserved N-glycans or by inserting new N-glycosylation sites near disulphide bridges. The generated HIV-1NL4.3 mutants were subjected to an array of assays, determining the envelope glycoprotein levels in mutant viral particles, their infectivity and the capture and transmission efficiencies of mutant virus particles by DC-SIGN. Three N-glycans located nearby disulphide bridges were found to be crucial for the preservation of several of these functions of gp120. In addition, introduction of new N-glycans upstream of several disulphide bridges, at locations where there was a significant absence of N-glycans in a broad variety of virus strains, was found to result in a complete loss of viral infectivity. It was shown that the N-glycan environment around well-defined disulphide bridges of gp120 is highly critical to allow efficient viral infection and transmission. PMID:26121645

Synergistic role of ADP and Ca2+ in diastolic myocardial stiffness

PubMed Central

Sequeira, Vasco; Najafi, Aref; McConnell, Mark; Fowler, Ewan D; Bollen, Ilse A E; Wüst, Rob C I; dos Remedios, Cris; Helmes, Michiel; White, Ed; Stienen, Ger J M; Tardiff, Jil; Kuster, Diederik W D; van der Velden, Jolanda

2015-01-01

Abstract Heart failure (HF) with diastolic dysfunction has been attributed to increased myocardial stiffness that limits proper filling of the ventricle. Altered cross-bridge interaction may significantly contribute to high diastolic stiffness, but this has not been shown thus far. Cross-bridge interactions are dependent on cytosolic [Ca2+] and the regeneration of ATP from ADP. Depletion of myocardial energy reserve is a hallmark of HF leading to ADP accumulation and disturbed Ca2+ handling. Here, we investigated if ADP elevation in concert with increased diastolic [Ca2+] promotes diastolic cross-bridge formation and force generation and thereby increases diastolic stiffness. ADP dose-dependently increased force production in the absence of Ca2+ in membrane-permeabilized cardiomyocytes from human hearts. Moreover, physiological levels of ADP increased actomyosin force generation in the presence of Ca2+ both in human and rat membrane-permeabilized cardiomyocytes. Diastolic stress measured at physiological lattice spacing and 37°C in the presence of pathological levels of ADP and diastolic [Ca2+] revealed a 76 ± 1% contribution of cross-bridge interaction to total diastolic stress in rat membrane-permeabilized cardiomyocytes. Inhibition of creatine kinase (CK), which increases cytosolic ADP, in enzyme-isolated intact rat cardiomyocytes impaired diastolic re-lengthening associated with diastolic Ca2+ overload. In isolated Langendorff-perfused rat hearts, CK inhibition increased ventricular stiffness only in the presence of diastolic [Ca2+]. We propose that elevations of intracellular ADP in specific types of cardiac disease, including those where myocardial energy reserve is limited, contribute to diastolic dysfunction by recruiting cross-bridges, even at low Ca2+, and thereby increase myocardial stiffness. Key points Diastolic dysfunction in heart failure patients is evident from stiffening of the passive properties of the ventricular wall. Increased actomyosin interactions may significantly limit diastolic capacity, however, direct evidence is absent. From experiments at the cellular and whole organ level, in humans and rats, we show that actomyosin-related force development contributes significantly to high diastolic stiffness in environments where high ADP and increased diastolic [Ca2+] are present, such as the failing myocardium. Our basal study provides a mechanical mechanism which may partly underlie diastolic dysfunction. PMID:26096258

Conversion between network-level and project-level units of measure for use in a bridge-management system.

DOT National Transportation Integrated Search

1998-01-01

VDOT is implementing Pontis 3.0 to provide the analytical component of its Bridge Management System (BMS). This system prioritizes bridge maintenance, repair, rehabilitation, and replacement (MRR & R) needs using cost/benefit analysis. The accuracy o...

Occupational Noise Exposure on a Royal Navy Warship During Weapon Fire

PubMed Central

Paddan, Gurmail Singh

2016-01-01

Introduction: Measurements were made of the sound pressure levels on a military ship HMS Grimsby during firing of a Heavy Machine Gun (HMG) mounted on the starboard bridge wing. The measurement positions comprised three locations on the ship's bridge (the wheelhouse) and one location on the starboard bridge wing. Equipment and Procedure: The three locations on the bridge were the starboard door, centre and port door. A total of 255 burst firings were measured during the survey comprising 850 rounds with each burst encompassing from 1 to 10 rounds. Analysis: The data have been assessed and interpreted in accordance with the Control of Noise at Work Regulations 2005. Results: The highest peak sound pressure levels measured on the bridge wing and on the bridge were 160.7 dB(C) (2170 Pa) and 122.7 dB(C) (27.3 Pa), respectively. The highest sound exposure levels measured on the bridge wing and on the bridge corresponding to one round being fired were 127.8 dB(A) and 88.9 dB(A), respectively. The ship's structure provided about 40 dB attenuation in the transmitted noise. Discussion: The operator of the weapon would be required to wear some form of hearing protection. On the basis of the measured peak noise levels, there would be no requirement for bridge crew to wear any hearing protection during firing of a HMG. However, crew exposure to noise on the bridge is likely to exceed the upper exposure action value corresponding to 85 dB(A) after about 11,750 rounds. Conclusions: Measurements made on the bridge wings are likely to be affected by reflections from the ship's structure. PMID:27762256

Occupational noise exposure on a Royal Navy warship during weapon fire.

PubMed

Paddan, Gurmail Singh

2016-01-01

Measurements were made of the sound pressure levels on a military ship HMS Grimsby during firing of a Heavy Machine Gun (HMG) mounted on the starboard bridge wing. The measurement positions comprised three locations on the ship's bridge (the wheelhouse) and one location on the starboard bridge wing. Equipment and Procedure: The three locations on the bridge were the starboard door, centre and port door. A total of 255 burst firings were measured during the survey comprising 850 rounds with each burst encompassing from 1 to 10 rounds. The data have been assessed and interpreted in accordance with the Control of Noise at Work Regulations 2005. The highest peak sound pressure levels measured on the bridge wing and on the bridge were 160.7 dB(C) (2170 Pa) and 122.7 dB(C) (27.3 Pa), respectively. The highest sound exposure levels measured on the bridge wing and on the bridge corresponding to one round being fired were 127.8 dB(A) and 88.9 dB(A), respectively. The ship's structure provided about 40 dB attenuation in the transmitted noise. The operator of the weapon would be required to wear some form of hearing protection. On the basis of the measured peak noise levels, there would be no requirement for bridge crew to wear any hearing protection during firing of a HMG. However, crew exposure to noise on the bridge is likely to exceed the upper exposure action value corresponding to 85 dB(A) after about 11,750 rounds. Measurements made on the bridge wings are likely to be affected by reflections from the ship's structure.

High-temperature brushless DC motor controller

DOEpatents

Cieslewski, Crzegorz; Lindblom, Scott C.; Maldonado, Frank J.; Eckert, Michael Nathan

2017-05-16

A motor control system for deployment in high temperature environments includes a controller; a first half-bridge circuit that includes a first high-side switching element and a first low-side switching element; a second half-bridge circuit that includes a second high-side switching element and a second low-side switching element; and a third half-bridge circuit that includes a third high-side switching element and a third; low-side switching element. The motor controller is arranged to apply a pulse width modulation (PWM) scheme to switch the first half-bridge circuit, second half-bridge circuit, and third half-bridge circuit to power a motor.

Feasibility and Costs of Natural Gas as a Bridge to Deep Decarbonization in the United States

NASA Astrophysics Data System (ADS)

Jones, A. D.; McJeon, H. C.; Muratori, M.; Shi, W.

2015-12-01

Achieving emissions reductions consistent with a 2 degree Celsius global warming target requires nearly complete replacement of traditional fossil fuel combustion with near-zero carbon energy technologies in the United States by 2050. There are multiple technological change pathways consistent with this deep decarbonization, including strategies that rely on renewable energy, nuclear, and carbon capture and storage (CCS) technologies. The replacement of coal-fired power plants with natural gas-fired power plants has also been suggested as a bridge strategy to achieve near-term emissions reduction targets. These gas plants, however, would need to be replaced by near-zero energy technologies or retrofitted with CCS by 2050 in order to achieve longer-term targets. Here we examine the costs and feasibility of a natural gas bridge strategy. Using the Global Change Assessment (GCAM) model, we develop multiple scenarios that each meet the recent US Intended Nationally Determined Contribution (INDC) to reduce GHG emissions by 26%-28% below its 2005 levels in 2025, as well as a deep decarbonization target of 80% emissions reductions below 1990 levels by 2050. We find that the gas bridge strategy requires that gas plants be retired on average 20 years earlier than their designed lifetime of 45 years, a potentially challenging outcome to achieve from a policy perspective. Using a more idealized model, we examine the net energy system costs of this gas bridge strategy compared to one in which near-zero energy technologies are deployed in the near tem. We explore the sensitivity of these cost results to four factors: the discount rate applied to future costs, the length (or start year) of the gas bridge, the relative capital cost of natural gas vs. near-zero energy technology, and the fuel price of natural gas. The discount rate and cost factors are found to be more important than the length of the bridge. However, we find an important interaction as well. At low discount rates, the gas bridge is more expensive and a shorter bridge is preferred. At high discount rates, the gas bridge is less expensive and a longer bridge is preferred. This result indicates that the valuation of future expenditures relative to present day expenditures is a major factor in determining the merits of a gas bridge strategy.

Bridge deterioration models to support Indiana's bridge management system.

DOT National Transportation Integrated Search

2016-02-01

An effective bridge management system that is equipped with reliable deterioration models enables agency engineers to carry out : monitoring and long-term programming of bridge repair actions. At the project level, deterioration models help the agenc...

Bridging the Silos of Service Delivery for High-Need, High-Cost Individuals.

PubMed

Sherry, Melissa; Wolff, Jennifer L; Ballreich, Jeromie; DuGoff, Eva; Davis, Karen; Anderson, Gerard

2016-12-01

Health care reform efforts that emphasize value have increased awareness of the importance of nonmedical factors in achieving better care, better health, and lower costs in the care of high-need, high-cost individuals. Programs that care for socioeconomically disadvantaged, high-need, high-cost individuals have achieved promising results in part by bridging traditional service delivery silos. This study examined 5 innovative community-oriented programs that are successfully coordinating medical and nonmedical services to identify factors that stimulate and sustain community-level collaboration and coordinated care across silos of health care, public health, and social services delivery. The authors constructed a conceptual framework depicting community health systems that highlights 4 foundational factors that facilitate community-oriented collaboration: flexible financing, shared leadership, shared data, and a strong shared vision of commitment toward delivery of person-centered care.

Hydrodynamic forces on inundated bridge decks

DOT National Transportation Integrated Search

2009-05-01

The hydrodynamic forces experienced by an inundated bridge deck have great importance in the design of bridges. Specifically, the drag force, lift force, and the moment acting on the bridge deck under various levels of inundation and a range of flow ...

Investigation and Taguchi Optimization of Microbial Fuel Cell Salt Bridge Dimensional Parameters

NASA Astrophysics Data System (ADS)

Sarma, Dhrupad; Barua, Parimal Bakul; Dey, Nabendu; Nath, Sumitro; Thakuria, Mrinmay; Mallick, Synthia

2018-01-01

One major problem of two chamber salt bridge microbial fuel cells (MFCs) is the high resistance offered by the salt bridge to anion flow. Many researchers who have studied and optimized various parameters related to salt bridge MFC, have not shed much light on the effect of salt bridge dimensional parameters on the MFC performance. Therefore, the main objective of this research is to investigate the effect of length and cross sectional area of salt bridge and the effect of solar radiation and atmospheric temperature on MFC current output. An experiment has been designed using Taguchi L9 orthogonal array, taking length and cross sectional area of salt bridge as factors having three levels. Nine MFCs were fabricated as per the nine trial conditions. Trials were conducted for 3 days and output current of each of the MFCs along with solar insolation and atmospheric temperature were recorded. Analysis of variance shows that salt bridge length has significant effect both on mean (with 53.90% contribution at 95% CL) and variance (with 56.46% contribution at 87% CL), whereas the effect of cross sectional area of the salt bridge and the interaction of these two factors is significant on mean only (with 95% CL). Optimum combination was found at 260 mm salt bridge length and 506.7 mm2 cross sectional area with 4.75 mA of mean output current. The temperature and solar insolation data when correlated with each of the MFCs average output current, revealed that both external factors have significant impact on MFC current output but the correlation coefficient varies from MFC to MFC depending on salt bridge dimensional parameters.

8. West side of north end of bridge resting on ...

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

8. West side of north end of bridge resting on approach abutment. Oblique detail view northeast (from below roadbed level, beside bridge). 150 mm lens. - Gault Bridge, Spanning Deer Creek at South Pine Street, Nevada City, Nevada County, CA

Structural bridging network position is associated with HIV status in a younger Black men who have sex with men epidemic.

PubMed

Shah, Nirav S; Iveniuk, James; Muth, Stephen Q; Michaels, Stuart; Jose, Jo-Anne; Laumann, Edward O; Schneider, John A

2014-02-01

Younger Black men who have sex with men (BMSM) ages 16-29 have the highest rates of HIV in the United States. Despite increased attention to social and sexual networks as a framework for biomedical intervention, the role of measured network positions, such as bridging and their relationship to HIV risk has received limited attention. A network sample (N = 620) of BMSM respondents (N = 154) and their MSM and transgendered person network members (N = 466) was generated through respondent driven sampling of BMSM and elicitation of their personal networks. Bridging status of each network member was determined by a constraint measure and was used to assess the relationship between this bridging and unprotected anal intercourse (UAI), sex-drug use (SDU), group sex (GS) and HIV status within the network in South Chicago. Low, moderate and high bridging was observed in 411 (66.8 %), 81 (13.2 %) and 123 (20.0 %) of the network. In addition to age and having sex with men only, moderate and high levels of bridging were associated with HIV status (aOR 3.19; 95 % CI 1.58-6.45 and aOR 3.83; 95 % CI 1.23-11.95, respectively). Risk behaviors observed including UAS, GS, and SDU were not associated with HIV status, however, they clustered together in their associations with one another. Bridging network position but not risk behavior was associated with HIV status in this network sample of younger BMSM. Socio-structural features such as position within the network may be important when implementing effective HIV prevention interventions in younger BMSM populations.

7. Photocopy of photograph, date unknown. VIEW OF WEST HIGH ...

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

7. Photocopy of photograph, date unknown. VIEW OF WEST HIGH STREET BRIDGE OVER SOUTH BRANCH OF FRENCH CREEK, WITH PENN RAILROAD BRIDGE IN BACKGROUND. (Original in Union City Historical Museum.) 8'x10' enlargement from 4'x5' negative. - Bridge Street Bridge, Spanning Little French Creek at Bridge Street, Union City, Erie County, PA

Superhydrophobic engineered cementitious composites for highway applications : phase I.

DOT National Transportation Integrated Search

2013-05-01

The strength and durability of highway bridges are two of the key components in maintaining a high level of freight transportation capacity on the nations highways. This research focused on developing new hybrid superhydrophobic engineered cementi...

Enhancement of the FDOT's project level and network level bridge management analysis tools

DOT National Transportation Integrated Search

2011-02-01

Over several years, the Florida Department of Transportation (FDOT) has been implementing the AASHTO Pontis Bridge Management System to support network-level and project-level decision making in the headquarters and district offices. Pontis is an int...

Stability and Responsiveness in a Self-Organized Living Architecture

PubMed Central

Garnier, Simon; Murphy, Tucker; Lutz, Matthew; Hurme, Edward; Leblanc, Simon; Couzin, Iain D.

2013-01-01

Robustness and adaptability are central to the functioning of biological systems, from gene networks to animal societies. Yet the mechanisms by which living organisms achieve both stability to perturbations and sensitivity to input are poorly understood. Here, we present an integrated study of a living architecture in which army ants interconnect their bodies to span gaps. We demonstrate that these self-assembled bridges are a highly effective means of maintaining traffic flow over unpredictable terrain. The individual-level rules responsible depend only on locally-estimated traffic intensity and the number of neighbours to which ants are attached within the structure. We employ a parameterized computational model to reveal that bridges are tuned to be maximally stable in the face of regular, periodic fluctuations in traffic. However analysis of the model also suggests that interactions among ants give rise to feedback processes that result in bridges being highly responsive to sudden interruptions in traffic. Subsequent field experiments confirm this prediction and thus the dual nature of stability and flexibility in living bridges. Our study demonstrates the importance of robust and adaptive modular architecture to efficient traffic organisation and reveals general principles regarding the regulation of form in biological self-assemblies. PMID:23555219

Personal Exposure, Behavior, and Work Site Conditions as Determinants of Blood Lead Among Bridge Painters

PubMed Central

Rodrigues, Ema G.; Virji, M. Abbas; McClean, Michael D.; Weinberg, Janice; Woskie, Susan; Pepper, Lewis D.

2009-01-01

Bridge painters are exposed to lead during several job tasks performed during the workday, such as sanding, scraping, and blasting. After the Occupational Safety and Health Administration standard was passed in 1993 to control lead exposures among construction workers including bridge painters, this study was conducted among 84 bridge painters in the New England area to determine the significant predictors of blood lead levels. Lead was measured in personal air and hand wipe samples that were collected during the 2-week study period and in blood samples that were collected at the beginning and at the end of the study period. The personal air and hand wipe data as well as personal behaviors (i.e., smoking, washing, wearing a respirator) and work site conditions were analyzed as potential determinants of blood lead levels using linear mixed effects models. Our results show that the mean air lead levels over the 2-week period were the most predictive exposure measure of blood lead levels. Other individual-level significant predictors of blood lead levels included months worked on bridge painting crews, education, and personal hygiene index. Of the site-level variables investigated, having a containment facility on site was a significant predictor of blood lead levels. Our results also indicate that hand wipe lead levels were significantly associated with higher blood lead levels at the end of the study period compared with the beginning of the study period. Similarly, smoking on site and respirator fit testing were significantly associated with higher blood lead levels at the end of the study period. This study shows that several individual-level and site-level factors are associated with blood lead levels among bridge painters, including lead exposure through inhalation and possible hand-to-mouth contact, personal behaviors such as smoking on site, respirator fit testing, and work site conditions such as the use of better containment facilities. Accordingly, reduction in blood lead levels among bridge painters can be achieved by improving these workplace practices. PMID:19953411

Estimated and measured bridge scour at selected sites in North Dakota, 1990-97

USGS Publications Warehouse

Williams-Sether, Tara

1999-01-01

A Level 2 bridge scour method was used to estimate scour depths at 36 selected bridge sites located on the primary road system throughout North Dakota. Of the 36 bridge sites analyzed, the North Dakota Department of Transportation rated 15 as scour critical. Flood and scour data were collected at 19 of the 36 selected bridge sites during 1990-97. Data collected were sufficient to estimate pier scour but not contraction or abutment scour. Estimated pier scour depths ranged from -10.6 to -1.2 feet, and measured bed-elevation changes at piers ranged from -2.31 to +2.37 feet. Comparisons between the estimated pier scour depths and the measured bed-elevation changes indicate that the pier scour equations overestimate scour at bridges in North Dakota.A Level 1.5 bridge scour method also was used to estimate scour depths at 495 bridge sites located on the secondary road system throughout North Dakota. The North Dakota Department of Transportation determined that 26 of the 495 bridge sites analyzed were potentially scour critical.

Bridge Crossing Simulator

DTIC Science & Technology

2014-10-07

is counted as. Per the TDTC, a test bridge with longitudinal and/or lateral symmetry under non- eccentric loading can be considered as 1, 2, or 4...Level Run036 3 MLC70T (tracked) BA Run046 6 AB Run055 9 AB Run060 9 BA Run064 12 BA Run071 15 AB Run155 3 MLC96W ( wheeled ) AB...Run331 9 AB Run359 15 AB Run430 12 MLC96W ( wheeled ) BA Run434 12 AB Run447 3 BA Bank Condition: Side Slope, Even Strain Channels High

Effects of Fragmentation and Sea-Level Changes upon Frog Communities of Land-Bridge Islands off the Southeastern Coast of Brazil

PubMed Central

Bittencourt-Silva, Gabriela B.; Silva, Hélio R.

2014-01-01

We investigate the composition of anuran communities of land-bridge islands off the southeastern coast of Brazil. These islands provide natural long-term experiments on the effects of fragmentation in the Brazilian Atlantic Forest (BAF). We hypothesize that Pleistocene sea-level changes, in combination with other abiotic variables such as area and habitat diversity, has affected anuran species richness and community composition on these islands. Data from the literature and collections databases were used to produce species lists for eight land-bridge islands and for the mainland adjacent to the islands. We assess the effects of area, number of breeding habitats and distance to the mainland upon anuran species richness on land-bridge islands. Additionally we use nestedness analysis to quantify the extent to which the species on smaller and less habitat-diverse islands correspond to subsets of those on larger and more diverse ones. We found that area has both direct and indirect effects on anuran species richness on land-bridge islands, irrespective of distance to the mainland. However, on islands with comparable sizes, differences in species richness can be attributed to the number and quality of breeding habitats. Anuran communities on these islands display a nested pattern, possibly caused by selective extinction related to habitat loss. Common lowland pond-breeders were conspicuous by their absence. In the BAF, the conservation of fragments with a high diversity of breeding habitats could compensate for the generally negative effect of small area upon species richness. We suggest that sea-level changes have an important role in shaping composition of anuran species on coastal communities. PMID:25068643

Evaluation of a highway bridge constructed using high strength lightweight concrete bridge girders.

DOT National Transportation Integrated Search

2011-04-01

The purpose of this research was to characterize the performance of High Strength Lightweight Concrete (HSLW) in precast, prestressed bridge girders and to evaluate their performance in a highway bridge. The mechanical properties and long-term time-d...

Two test level 4 bridge railing and transition systems for transverse timber deck bridges

Treesearch

Ronald K. Faller; Michael A. Ritter; Barry T. Rosson; Michael D. Fowler; Sheila R. Duwadi

2000-01-01

The Midwest Roadside Safety Facility, in cooperation with the Forest Products Laboratory, which is part of the U.S. Department of Agricultureas Forest Service, and FHWA, designed two bridge railing and approach guardrail transition systems for use on bridges with transverse glue-laminated timber decks. The bridge raging and transition systems were developed and crash...

The medial temporal lobe-conduit of parallel connectivity: a model for attention, memory, and perception.

PubMed

Mozaffari, Brian

2014-01-01

Based on the notion that the brain is equipped with a hierarchical organization, which embodies environmental contingencies across many time scales, this paper suggests that the medial temporal lobe (MTL)-located deep in the hierarchy-serves as a bridge connecting supra- to infra-MTL levels. Bridging the upper and lower regions of the hierarchy provides a parallel architecture that optimizes information flow between upper and lower regions to aid attention, encoding, and processing of quick complex visual phenomenon. Bypassing intermediate hierarchy levels, information conveyed through the MTL "bridge" allows upper levels to make educated predictions about the prevailing context and accordingly select lower representations to increase the efficiency of predictive coding throughout the hierarchy. This selection or activation/deactivation is associated with endogenous attention. In the event that these "bridge" predictions are inaccurate, this architecture enables the rapid encoding of novel contingencies. A review of hierarchical models in relation to memory is provided along with a new theory, Medial-temporal-lobe Conduit for Parallel Connectivity (MCPC). In this scheme, consolidation is considered as a secondary process, occurring after a MTL-bridged connection, which eventually allows upper and lower levels to access each other directly. With repeated reactivations, as contingencies become consolidated, less MTL activity is predicted. Finally, MTL bridging may aid processing transient but structured perceptual events, by allowing communication between upper and lower levels without calling on intermediate levels of representation.

Identification of sudden stiffness changes in the acceleration response of a bridge to moving loads using ensemble empirical mode decomposition

NASA Astrophysics Data System (ADS)

Aied, H.; González, A.; Cantero, D.

2016-01-01

The growth of heavy traffic together with aggressive environmental loads poses a threat to the safety of an aging bridge stock. Often, damage is only detected via visual inspection at a point when repairing costs can be quite significant. Ideally, bridge managers would want to identify a stiffness change as soon as possible, i.e., as it is occurring, to plan for prompt measures before reaching a prohibitive cost. Recent developments in signal processing techniques such as wavelet analysis and empirical mode decomposition (EMD) have aimed to address this need by identifying a stiffness change from a localised feature in the structural response to traffic. However, the effectiveness of these techniques is limited by the roughness of the road profile, the vehicle speed and the noise level. In this paper, ensemble empirical mode decomposition (EEMD) is applied by the first time to the acceleration response of a bridge model to a moving load with the purpose of capturing sudden stiffness changes. EEMD is more adaptive and appears to be better suited to non-linear signals than wavelets, and it reduces the mode mixing problem present in EMD. EEMD is tested in a variety of theoretical 3D vehicle-bridge interaction scenarios. Stiffness changes are successfully identified, even for small affected regions, relatively poor profiles, high vehicle speeds and significant noise. The latter is due to the ability of EEMD to separate high frequency components associated to sudden stiffness changes from other frequency components associated to the vehicle-bridge interaction system.

Long-term Testing Results for the 2008 Installation of LED Luminaires at the I-35 West Bridge in Minneapolis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinzey, Bruce R.; Davis, Robert G.

2014-09-30

This document reports the long-term testing results from an extended GATEWAY project that was first reported in “Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting at the I-35W Bridge, in Minneapolis, MN,” August 2009. That original report presented the results of lighting the newly reconstructed I 35W Bridge using LEDs in place of conventional high-pressure sodium (HPS) roadway luminaires, comparing energy use and illuminance levels with a simulated baseline condition. That installation was an early stage implementation of LED lighting and remains one of the oldest installations in continued operation today. This document provides an update of the LED system’smore » performance since its installation in September 2008.« less

Mechanical Modeling and Computer Simulation of Protein Folding

ERIC Educational Resources Information Center

Prigozhin, Maxim B.; Scott, Gregory E.; Denos, Sharlene

2014-01-01

In this activity, science education and modern technology are bridged to teach students at the high school and undergraduate levels about protein folding and to strengthen their model building skills. Students are guided from a textbook picture of a protein as a rigid crystal structure to a more realistic view: proteins are highly dynamic…

Hot-Air Balloons: Project-Centered Study as a Bridge between Science and Technology Education.

ERIC Educational Resources Information Center

Barak, Moshe; Raz, Eli

2000-01-01

Describes the development of a project-based unit on hot-air balloons used with Israeli junior high school students. Concludes that students in the program gained experience with high-level scientific principles and technological processes, the project allows for a learning environment of cooperation and teamwork, and collaboration between…

Bridging Physics to Electronics--An Outreach Effort

ERIC Educational Resources Information Center

Tan, Kok-Kiong; Tang, Kok-Zuea; Ng, Vivian; Tay, Arthur; Yen, Shih-Cheng; Lee, Tong-Heng

2010-01-01

Physics has been an important part of the science curriculum in high schools. Without the appropriate high school physics background, it is difficult for a student subsequently to pursue an electronics engineering program at the university level since a good understanding of many concepts in physics is required to comprehend the material covered…

Student Perspectives on Quality Teaching: Words and Images

ERIC Educational Resources Information Center

Bell, Athene; Ewaida, Marriam; Lynch, Megan R.; Zenkov, Kristien

2011-01-01

This article reports on the findings of a photography and literacy project ("Through Students' Eyes") the authors conducted with middle level English language learners and alternative high school youth from a mid-Atlantic (US) ex-urban area. In order to bridge middle and high school settings, the authors used multimodal and photo…

Transitions: How Music Can Help Build a Bridge from Middle School to High School

ERIC Educational Resources Information Center

Poliniak, Susan

2011-01-01

When students first enter high school, the change can be overwhelming on many levels. All at once, or very nearly, they're dealing with an onslaught of new educational concerns, weighty academic decisions, different extracurricular options, unfamiliar teachers, and potentially bewildering social atmospheres. Meanwhile, former middle school…

Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting at the I-35W Bridge, Minneapolis, MN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinzey, Bruce R.; Myer, Michael

2009-08-31

This report describes the process and results of a demonstration of solid-state lighting (SSL) technology conducted in 2009 at the recently reconstructed I-35W bridge in Minneapolis, MN. The project was supported under the U.S. Department of Energy (DOE) Solid-State Lighting GATEWAY Technology Demonstration Program. Other participants in the demonstration project included the Minnesota Department of Transportation (Mn/DOT), Federal Highways Administration (FHWA), and BetaLED™ (a division of Ruud Lighting). Pacific Northwest National Laboratory (PNNL) conducted the measurements and analysis of the results. DOE has implemented a three-year evaluation of the LED luminaires in this installation in order to develop new longitudinalmore » field data on LED performance in a challenging, real-world environment. This document provides information through the initial phase of the I-35W bridge project, up to and including the opening of the bridge to the public and the initial feedback received on the LED lighting installation from bridge users. Initial findings of the evaluation are favorable, with minimum energy savings level of 13% for the LED installation relative to the simulated base case using 250W high-pressure sodium (HPS) fixtures. The LEDs had an average illuminance level of 0.91 foot candles compared to 1.29 fc for the HPS lamps. The LED luminaires cost $38,000 more than HPS lamps, yielding a lengthy payback period, however the bridge contractor had offered to include the LED luminaires as part of the construction package at no additional cost. One potentially significant benefit of the LEDs in this installation is avoiding rolling lane closures on the heavily-traveled interstate bridge for the purpose of relamping the HPS fixtures. Rolling lane closures involve multiple crew members and various maintenance and safety vehicles, diversion of traffic, as well as related administrative tasks (e.g., approvals, scheduling, etc.). Mn/DOT records show an average cost of relamping fixtures along interstate roadways of between $130-150 per pole. The previous bridge saw a lamp mortality rate of approximately 50% every two years, though the new bridge was designed to minimize many of the vibration issues. A voluntary Web-based feedback survey of nearly 500 self-described bridge users showed strong preference for the LED lighting - positive comments outnumbered negative ones by about five-to-one.« less

Considerations and Recommendations for Implementing a Dual-Enrollment Program: Bridging the Gap between High School and College Level Science

ERIC Educational Resources Information Center

Lukes, Laura A.

2014-01-01

Dual-enrollment (DE) science courses offer a way to strengthen the science, technology, engineering, and mathematics pipeline between high school and college. These courses offer high school students the opportunity to experience college science in a more supported environment, allowing them to adjust to the different academic and social demands…

Superhydrophobic engineered cementitious composites for highway applications : phase II.

DOT National Transportation Integrated Search

2013-06-01

The strength and durability of highway bridges are two of the key components in maintaining a : high level of freight transportation capacity on the nations highways. : The CFIRE project 04-09 demonstrated the feasibility of a new hybrid engineered...

13. A streetcar crosses the Cuyahoga River in the waning ...

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

13. A streetcar crosses the Cuyahoga River in the waning days of Cleveland's trolley age. Copy of photograph taken by Herbert H. Harwood, Jr., Baltimore, Maryland, photo courtesy Mr. Harwood - Detroit Superior High Level Bridge, Cleveland, Cuyahoga County, OH

19. Stress sheet for the river span dated 7/13/12; revised ...

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

19. Stress sheet for the river span dated 7/13/12; revised Oct. 18 and 21, 1912. Drawing courtesy Office of the Cuyahoga County Engineer, Cleveland, Ohio. - Detroit Superior High Level Bridge, Cleveland, Cuyahoga County, OH

8. VIEW OF OPEN HEARTH NO. 5 FROM THE HOMESTEAD ...

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

8. VIEW OF OPEN HEARTH NO. 5 FROM THE HOMESTEAD HIGH LEVEL BRIDGE. NO. 2 FORGE SHOP IS VISIBLE ON THE RIGHT - U.S. Steel Homestead Works, Open Hearth Steelmaking Plant, Along Monongahela River, Homestead, Allegheny County, PA

9. VIEW OF OPEN HEARTH NO. 5 FROM THE HOMESTEAD ...

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

9. VIEW OF OPEN HEARTH NO. 5 FROM THE HOMESTEAD HIGH LEVEL BRIDGE. NO. 2 FORGE SHOP IS VISIBLE ON THE RIGHT. - U.S. Steel Homestead Works, Open Hearth Steelmaking Plant, Along Monongahela River, Homestead, Allegheny County, PA

An overheight vehicle bridge collision monitoring system using piezoelectric transducers

NASA Astrophysics Data System (ADS)

Song, G.; Olmi, C.; Gu, H.

2007-04-01

With increasing traffic volume follows an increase in the number of overheight truck collisions with highway bridges. The detection of collision impact and evaluation of the impact level is a critical issue in the maintenance of a concrete bridge. In this paper, an overheight collision detection and evaluation system is developed for concrete bridge girders using piezoelectric transducers. An electric circuit is designed to detect the impact and to activate a digital camera to take photos of the offending truck. Impact tests and a health monitoring test were conducted on a model concrete bridge girder by using three piezoelectric transducers embedded before casting. From the experimental data of the impact test, it can be seen that there is a linear relation between the output of sensor energy and the impact energy. The health monitoring results show that the proposed damage index indicates the level of damage inside the model concrete bridge girder. The proposed overheight truck-bridge collision detection and evaluation system has the potential to be applied to the safety monitoring of highway bridges.

Environmental impacts of bridge cleaning operations.

DOT National Transportation Integrated Search

2003-02-01

Cleaning (washing) operations of existing leaded paints on bridges were studied to determine the level of lead contamination in the resulting wastewater. Twelve experimental overcoating projects were let on bridges with various types of existing pain...

Bridge Failure Due to Inadequate Design of Bed Protection

NASA Astrophysics Data System (ADS)

Gupta, Yogita; Kaur, Suneet; Dindorkar, Nitin

2017-12-01

The shallow foundation is generally provided on non-erodible strata or where scour depth is less. It is also preferable for low perennial flow or standing water condition. In the present case study shallow foundation is adopted for box type bridge. The total length of the bridge is 132.98 m, consisting of eight unit of RCC box. Each unit is composed of three cell box. The bottom slab of box unit is acted as raft foundation, founded 500 mm below ground level. River bed protection work is provided on both upstream and downstream side along the whole length of the bridge as it is founded above scour level. The bridge collapsed during the monsoon just after two years of service. The present paper explains the cause of failure. This study on failure of the bridge illustrates the importance of bridge inspection before and after monsoon period and importance of the timely maintenance. Standard specifications of Indian Road Congress for the river bed protection work are also included.

Agar-based bridges as biocompatible candidates to provide guide cues in spinal cord injury repair.

PubMed

Martín-López, Eduardo; Darder, Margarita; Ruiz-Hitzky, Eduardo; Nieto Sampedro, Manuel

2013-01-01

Spinal bridge implants are strategic to provide growth surfaces for axonal regeneration after spinal cord injuries. The design of an appropriate substrate, one that is suitable for implantation, must involve careful testing of the biomaterial properties both in vitro and in vivo. The goal of this work was to test the structure, stability and biological response after spinal bridges implantation of several biopolymers, composed of mixtures of agar (AG), as structural matrix scaffold, with κ-carrageenan (Kc), gelatin (G), xanthan gum (Xn) and polysulfone (PS). Biopolymer structures were studied by environmental scanning electron microscopy, whereas the stability of gels was analyzed by in vitro degradation and swelling tests. The biocompatibility of these materials and their ability to promote cell growth and axonal regeneration were studied by implantation of spinal bridges containing empty linear channels in an acute rat spinal cord transection model at thoracic level (T8). All gel mixtures gave rise to porous structures and they were stables to degradation, excepting the AG+G mixture. Spinal bridges constructed from all mixtures were implanted during a month in adult rats. After this time a low host reaction occurred to all bridge materials as well as neurite and cell ingrowths through the empty channels. Neurites within the bridges were mostly peripheral sensory fibers such as those positive for CGRP, whereas there was a lack of regeneration of central axons crossing from the spinal tissue to bridges. Many of these neurites established closed contacts with non-myelin Schwann cells. The histological analysis revealed a high accumulation of collagen fibers within the channels. Unexpected was the apparent loss of channels linearity which affected the growth of neurites and cells, indicating the need for additional regeneration strategies and vertebrae bridge fixing.

Mechanical Flexibility of Zinc Oxide Thin-Film Transistors Prepared by Transfer Printing Method

NASA Astrophysics Data System (ADS)

Eun, K. T.; Hwang, W. J.; Sharma, B. K.; Ahn, J. H.; Lee, Y. K.; Choa, S. H.

In the present study, we demonstrate the performance of Zinc oxide thin film transistors (ZnO TFTs) array subjected to the strain under high bending test and the reliability of TFTs was confirmed for the bending fatigue test of 2000 cycles. Initially, ZnO TFTs were fabricated on Si substrate and subsequently transferred on flexible PET substrate using transfer printing process. It was observed that when the bending radius reached ≥ 11 mm then cracks start to initiate first at SiO2 bridges, acting as interconnecting layers among individual TFT. Whatever the strain is applied to the devices, it is almost equivalently adopted by the SiO2 bridges, as they are relatively weak compared to rest of the part. The initial cracking of destructed SiO2 bridge leads to the secondary cracks to the ITO electrodes upon further increment of bending radius. Numerical simulation suggested that the strain of SiO2 layer reached to fracture level of 0.55% which was concentrated at the edge of SiO2 bridge layer. It also suggests that the round shape of SiO2 bridge can be more fruitful to compensate the stress concentration and to prevent failure of device.

Long-term bridge performance high priority bridge performance issues.

DOT National Transportation Integrated Search

2014-10-01

Bridge performance is a multifaceted issue involving performance of materials and protective systems, : performance of individual components of the bridge, and performance of the structural system as a whole. The : Long-Term Bridge Performance (LTBP)...

Analysis of Static Load Test of a Masonry Arch Bridge

NASA Astrophysics Data System (ADS)

Shi, Jing-xian; Fang, Tian-tian; Luo, Sheng

2018-03-01

In order to know whether the carrying capacity of the masonry arch bridge built in the 1980s on the shipping channel entering and coming out of the factory of a cement company can meet the current requirements of Level II Load of highway, through the equivalent load distribution of the test vehicle according to the current design specifications, this paper conducted the load test, evaluated the bearing capacity of the in-service stone arch bridge, and made theoretical analysis combined with Midas Civil. The results showed that under the most unfavorable load conditions the measured strain and deflection of the test sections were less than the calculated values, the bridge was in the elastic stage under the design load; the structural strength and stiffness of the bridge had a certain degree of prosperity, and under the in the current conditions of Level II load of highway, the bridge structure was in a safe state.

Study of technology of pile foundation construction of no.5 main pier of Shoujiang bridge in Wenchuan County

NASA Astrophysics Data System (ADS)

Huang, Xianbin; Liu, Chenyang; Chen, Chunyang; Wangren, Yahong; Xu, Jialin; Xian, Jin

2018-03-01

The group of pile foundation of no.5 pier in Shoujiang Bridge needs to overcome the big load of large span continuous steel structure. The length of single pile foundation is 77m and the diameter of single pile foundation is 250cm. It not only faces the flood in the upstream of Shoujiang river, the construction obstacles during summer rain period, but also the reservoir clearance activity of Zipingpu reservoir and the high water level in winter and other water level fluctuation that have huge impact on platform of pile foundation construction. This article introduces the preparation in aspect of personnel, material, equipment and so on of pile foundation construction, and also conduct intensive research on leveling the field, assaying pile location, the embedment of the steel casing, installing the drill, mixing mud, drilling, final hole inspection and clearance, steel cage construction, perfusing concrete under water.

3. VIEW OF EAST SOUTHEAST, GROUND LEVEL VIEW OF ...

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

3. VIEW OF EAST - SOUTHEAST, GROUND LEVEL VIEW OF APPROACH SPANS, NORTH END OF BRIDGE, MAIN SPANS IN BACKGROUND - Buffalo River Bridge, Spanning Buffalo River on U.S. Highway 65, Marshall, Searcy County, AR

Bridging High School and Introductory Undergraduate Courses in Geographic Information Science and Technology

ERIC Educational Resources Information Center

Journal of Geography, 2018

2018-01-01

This article presents the findings of a study to determine the degree of consistency in what is taught and learned in high school and college-level introductory courses in geographic information science and technology (GIS&T). A content analysis identified sixteen topics that are generally representative of the knowledge, skills, and abilities…

Impedance-based detection of corrosion in post-tensioned cables : phase 2 extension of sensor development : [summary].

DOT National Transportation Integrated Search

2015-08-01

In post-tensioning construction, steel cables : running through PVC pipes buried in concrete : construction components are subjected to a high : level of tension and then secured. This gives the : component significant strength, allowing bridge : spa...

2. VIEW OF OPEN HEARTH NO. 5 FROM THE HOMESTEAD ...

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

2. VIEW OF OPEN HEARTH NO. 5 FROM THE HOMESTEAD HIGH LEVEL BRIDGE. NO. 2 FORGE SHOP IS VISIBLE ON THE RIGHT. (Jet Lowe) - U.S. Steel Homestead Works, Open Hearth Steelmaking Plant, Along Monongahela River, Homestead, Allegheny County, PA

Vibration analysis of the Second Saikai Bridge—a concrete filled tubular (CFT) arch bridge

NASA Astrophysics Data System (ADS)

Yoshimura, Mistuhiro; Wu, Qingxiong; Takahashi, Kazuo; Nakamura, Shozo; Furukawa, Kazuyoshi

2006-02-01

Concrete-filled steel tubular (CFT) arch bridges have been rapidly developing in China since 1990. Research has focused on the static behavior, thermal stress and erection technique, however, and there has been very little research of natural vibrations and dynamic responses of these bridges. Japan's first CFT arch bridge in highway bridges, the Second Saikai Bridge, is now under construction in Nagasaki Prefecture. Furthermore, this bridge has a pedestrian bridge that is suspended under the girder, which is rare. Therefore, the natural vibration properties are examined, and the influence of pedestrian bridge structure on the natural vibration of main bridge is discussed first. Response analysis under a moving vehicle and pedestrian is carried out, and the response characteristics and response level are clarified. The natural vibrations and responses are compared to those of CFT arch bridges that have been constructed in China. Results show the fine performance of both main bridge and pedestrian bridge of the Second Saikai Bridge.

58. MISSISSIPPI, NOXUBEE CO. MACON MAHORNER'S BRIDGE, 1884, Ms. 14, ...

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

58. MISSISSIPPI, NOXUBEE CO. MACON MAHORNER'S BRIDGE, 1884, Ms. 14, E 6.5 mi. to McLeod, 4.5 miles S on McLeod-Shuqualak road. Mahorner's bridge (1884). Lower panel point, west span. View is at right-angles to the bridge and from below deck level. show pin connection, floor beams, and stringers. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

Evaluation of a highway bridge constructed using high strength lightweight concrete bridge girders.

DOT National Transportation Integrated Search

2011-04-01

The use of high performance concretes to provide longer bridge spans has been limited due to the capacity of existing infrastructure to handle the load of the girders during transportation. The use of High Strength Lightweight Concrete (HSLW) can pro...

The Rationale for the Middle Level School. Practitioner's Monograph No. 9.

ERIC Educational Resources Information Center

Lake, Sara

Almost from the beginning, the junior high school was based on the same vision driving today's middle level schooling: the creation of a unique middle tier of education that bridges the gap between elementary and secondary education and focuses on meeting early adolescent students' academic and personal needs. In the 1950s and 1960s, middle school…

61. MISSISSIPPI, NOXUBEE CO. MACON MAHORNER'S BRIDGE Ms. 14, 6 ...

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

61. MISSISSIPPI, NOXUBEE CO. MACON MAHORNER'S BRIDGE Ms. 14, 6 miles E to McLeod, 4.5 miles S on McLeod-Shuqualak road. Overall view of bridge, looking E along N side, from below deck level. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

78 FR 2683 - Carriage Standards for Bridge Navigational Watch Alarm Systems (BNWAS) Aboard U.S. Flagged Vessels

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-14

... Bridge Navigational Watch Alarm Systems (BNWAS) Aboard U.S. Flagged Vessels AGENCY: Coast Guard, DHS... carriage standards for Bridge Navigational Watch Alarm Systems (BNWAS), in accordance with the Articles of... carriage of a BNWAS should not lead to a reduction in manning levels on the bridge. Consistent with the...

Performance analysis of cascaded h-bridge multilevel inverter using mixed switching frequency with various dc-link voltages

NASA Astrophysics Data System (ADS)

Citarsa, I. B. F.; Satiawan, I. N. W.; Wiryajati, I. K.; Supriono

2016-01-01

Multilevel inverters have been widely used in many applications since the technology is advantageous to increase the converter capability as well as to improve the output voltage quality. According to the applied switching frequency, multilevel modulations can be subdivided into three classes, i.e: fundamental switching frequency, high switching frequency and mixed switching frequency. This paper investigates the performance of cascaded H-bridge (CHB) multilevel inverter that is modulated using mixed switching frequency (MSF) PWM with various dc-link voltage ratios. The simulation results show the nearly sinusoidal load output voltages are successfully achieved. It is revealed that there is improvement in output voltages quality in terms of THD and low-order harmonics content. The CHB inverter that is modulated using MSF PWM with equal dc-link voltage ratio (½ Vdc: ½ Vdc) produces output voltage with the lowest low-order harmonics (less than 1% of fundamental) while the CHB inverter that is modulated using MSF PWM with un-equal dc-link voltage ratio (2/3 Vdc: 1/3 Vdc) produces a 7-level output voltage with the lowest THD (16.31%) compared to the other PWM methods. Improvement of the output voltage quality here is also in line with improvement of the number of available levels provided in the output voltage. Here only 2 cells H-bridge inverter (contain 8 switches) are needed to produce a 7- level output voltage, while in the conventional CHB inverter at least 3 cells of H-bridge inverter (contain 12 switches) are needed to produce a 7-level output voltage. Hence it is valuable in term of saving number of component.

An impedance bridge measuring the capacitance ratio in the high frequency range up to 1 MHz

NASA Astrophysics Data System (ADS)

Bee Kim, Dan; Kew Lee, Hyung; Kim, Wan-Seop

2017-02-01

This paper describes a 2-terminal-pair impedance bridge, measuring the capacitance ratio in the high frequency range up to 1 MHz. The bridge was configured with two voltage sources and a phase control unit which enabled the bridge balance by synchronizing the voltage sources with an enhanced phase resolution. Without employing the transformers such as inductive voltage divider, injection and detection transformers, etc, the bridge system is quite simple to set up, and the balance procedure is quick and easy. Using this dual-source coaxial bridge, the 1:1 and 10:1 capacitance ratios were measured with 1 pF-1 nF capacitors in the frequency range from 1 kHz to 1 MHz. The measurement values obtained by the dual-source bridge were then compared with reference values measured using a commercial precision capacitance bridge of AH2700A, the Z-matrix method developed by ourselves, and the 4-terminal-pair coaxial bridge by the Czech Metrological Institute. All the measurements agreed within the reference uncertainty range of an order of 10-6-10-5, proving the bridge ability as a trustworthy tool for measuring the capacitance ratio in the high frequency range.

Backwater effects of Piers in Subcritical Flow

DOT National Transportation Integrated Search

2001-10-01

Construction or renovation of bridge structures may require placement of bridge piers within the channel or floodplain of natural waterways. These piers will obstruct the flow and may cause an increase in water levels upstream of the bridge structure...

Evaluation of a Highway Bridge Constructed Using High Strength Lightweight Concrete Bridge Girders : final report.

DOT National Transportation Integrated Search

2011-04-01

The use of high performance concretes to provide longer bridge spans has been limited due to the capacity of existing infrastructure to handle the load of the girders during transportation. The use of High Strength Lightweight Concrete (HSLW) can pro...

Use of Infrasound for evaluating potentially hazardous conditions for barge transit on the Mississippi River at Vicksburg, Mississippi

NASA Astrophysics Data System (ADS)

McKenna, M. H.; Simpson, C. P.; Jordan, A. M.

2017-12-01

Navigating the Mississippi River in Vicksburg, MS is known to be difficult for barge traffic in even the best of conditions due to the river's sharp bend 2 km north of the Highway 80 Bridge. When river levels rise, the level of difficulty in piloting barges under the bridge rises. Ongoing studies by the U.S. Army Engineer Research and Development Center (ERDC) are investigating infrasound as a means to correlate the low frequency acoustics generated by the river with the presence of hazardous conditions observed during flood stage, i.e., rough waters and high currents, which may lead to barge-bridge impacts. The Denied Area Monitoring and Exploitation of Structures (DAMES) Array at the ERDC Vicksburg, MS campus is a persistent seismic-acoustic array used for structural monitoring and explosive event detection. The DAMES Array is located 4.3 km from the Mississippi River/Highway 80 Bridge junction and recorded impulsive sub-audible acoustic signals, similar to an explosive event, from barge-bridge collisions that occurred between 2011 and 2017. This study focuses on five collisions that occurred during January 2016, which resulted in closing the river for barge transit and the Highway 80 Bridge for rail transit for multiple days until safety inspections were completed. The Highway 80 Bridge in Vicksburg, MS is the only freight-crossing over the Mississippi River between Baton Rouge, LA and Memphis, TN, meaning delays from these closings have significant impacts on all transit of goods throughout the Southeastern United States. River basin data and regional meteorological data have been analyzed to find correlations between the river conditions in January 2016, and recorded infrasound data with the aim of determining the likelihood that hazardous conditions are present on the river. Frequency-wavenumber analysis was used to identify the transient signals associated with the barge-bridge impacts and calculate the backazimuth to their source. Then, with the use of Sandia National Laboratory's Infratool, the collected infrasound data were analyzed before, during, and after each collision to identify patterns in the continuous-wave acoustics associated with the river's turbulence at the bend in the river 2 km north of the bridge. Permission to publish was granted by Director, Geotechnical and Structures Laboratory.

Increase in mean platelet volume in patients with myocardial bridge.

PubMed

Bilen, Emine; Tanboga, Ibrahim Halil; Kurt, Mustafa; Kocak, Umran; Ayhan, Huseyin; Keles, Telat; Bozkurt, Engin

2013-01-01

Myocardial bridge is associated with atherosclerosis altered in shear stress and endothelial dysfunction. Mean platelet volume (MPV), a determinant of platelet activation, is shown to be related with atherosclerosis and endothelial dysfunction. In this study, we aimed to evaluate platelet function assessed by MPV in patients with myocardial bridge. Forty-two patients with myocardial bridge in the left anterior descending artery (LAD) and 43 age- and gender-matched healthy participants were included in the study. Myocardial bridging was defined as an intramyocardial systolic compression or milking of a segment of an epicardial coronary artery on angiography. For the entire study population, MPV was measured using an automatic blood counter. The study population consisted of 42 patients with myocardial bridge (52.7 ± 10.2, 76.2% male) and 43 age- and sex-matched healthy control participants (52.1 ± 10.4, 74.4% male). Compared to the control group, MPV value was significantly higher in patients with myocardial bridge (8.9 ± 1.24 vs 8.3 ± 0.78; P = .01). Further, there were no significant differences between groups regarding hemoglobin level, platelet count, fasting blood glucose, and creatinine levels. Our study findings indicated that myocardial bridge is associated with elevated MPV values. Our results might partly explain the increased cardiovascular events in patients with myocardial bridge.

Cost and Ecological Feasibility of using UHPC in Highway Bridges

DOT National Transportation Integrated Search

2017-11-15

There is a growing interest in expanding the use of Ultra-high performance concrete (UHPC) from bridge deck joints for accelerated bridge construction to complex architectural and advanced structural applications. The high costs currently associated ...

Development and performance evaluation of fiber reinforced polymer bridge : [technical summary].

DOT National Transportation Integrated Search

2014-03-01

Conventionally, highway bridge decks in the US are predominantly made of steel-reinforced concrete. However, repair and : maintenance costs of these bridges incurred at the federal and state levels are overwhelming. As a result, for many years, there...

Safety Identifying of Integral Abutment Bridges under Seismic and Thermal Loads

PubMed Central

Easazadeh Far, Narges; Barghian, Majid

2014-01-01

Integral abutment bridges (IABs) have many advantages over conventional bridges in terms of strength and maintenance cost. Due to the integrity of these structures uniform thermal and seismic loads are known important ones on the structure performance. Although all bridge design codes consider temperature and earthquake loads separately in their load combinations for conventional bridges, the thermal load is an “always on” load and, during the occurrence of an earthquake, these two important loads act on bridge simultaneously. Evaluating the safety level of IABs under combination of these loads becomes important. In this paper, the safety of IABs—designed by AASHTO LRFD bridge design code—under combination of thermal and seismic loads is studied. To fulfill this aim, first the target reliability indexes under seismic load have been calculated. Then, these analyses for the same bridge under combination of thermal and seismic loads have been repeated and the obtained reliability indexes are compared with target indexes. It is shown that, for an IAB designed by AASHTO LRFD, the indexes have been reduced under combined effects. So, the target level of safety during its design life is not provided and the code's load combination should be changed. PMID:25405232

The effect of bridge exercise method on the strength of rectus abdominis muscle and the muscle activity of paraspinal muscles while doing treadmill walking with high heels.

PubMed

Kang, Taewook; Lee, Jaeseok; Seo, Junghoon; Han, Dongwook

2017-04-01

[Purpose] The purpose of this research is to investigate the effect of the method of bridge exercise on the change of rectus abdominis muscle and the muscle activity of paraspinal muscles while doing treadmill walking with high heels. [Subjects and Methods] The subjects of this research are healthy female students consisting of 10 persons performing bridge exercises in a supine group, 10 persons performing bridge exercises in a prone group, and 10 persons in a control group while in S university in Busan. Bridge exercise in supine position is performed in hook lying position. Bridge exercise in prone position is plank exercise in prostrate position. To measure the strength of rectus abdominis muscle, maintaining times of the posture was used. To measure the muscle activity of paraspinal muscles, EMG (4D-MT & EMD-11, Relive, Korea) was used. [Results] The strength of rectus abdominis muscle of both bridge exercises in the supine group and bridge exercises in the prone group increases significantly after exercise. The muscle activity of paraspinal muscle such as thoracic parts and lumbar parts in bridge exercises in the prone group decreases statistically while walking on a treadmill with high heels. Muscle activity of thoracic parts paraspinal muscle and bridge exercises in the supine group decreased significantly. [Conclusion] According to this study, we noticed that bridge exercise in a prone position is desirable for women who prefer wearing high heels as a back pain prevention exercise method.

Are neighborhood bonding and bridging social capital protective against depressive mood in old age? A multilevel analysis in Japan.

PubMed

Murayama, Hiroshi; Nofuji, Yu; Matsuo, Eri; Nishi, Mariko; Taniguchi, Yu; Fujiwara, Yoshinori; Shinkai, Shoji

2015-01-01

While the importance of distinguishing between bonding and bridging social capital is now understood, evidence remains sparse on their contextual effects on health. We examined the associations of neighborhood bonding and bridging social capital with depressive mood among older Japanese. A questionnaire survey of all community residents aged 65 and older in the city of Yabu, Hyogo Prefecture, Japan was conducted in July and August 2012. Bonding and bridging social capital were assessed by evaluating individual homogeneous and heterogeneous social networks in relation to age, gender, and socioeconomic status. Individual responses in each neighborhood were aggregated to create an index of neighborhood-level bonding/bridging social capital. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the associations of such social capital with depressive mood using multilevel binomial logistic regression analysis. Of the 7271 questionnaires distributed, 6416 were analyzed (covering 152 administrative neighborhoods). Approximately 56.8% of respondents were women, and the mean age was 76.2 ± 7.1 years. Neighborhood-level bonding social capital was inversely associated with depressive mood (OR = 0.84, 95% CI = 0.75-0.94), but neighborhood-level bridging social capital was not. Gender-stratified analysis revealed that neighborhood-level bonding social capital was inversely associated with depressive mood in both genders (OR = 0.83, 95% CI = 0.72-0.96 for men; OR = 0.85, 95% CI = 0.72-0.99 for women), while neighborhood-level bridging social capital was positively associated with depressive mood in women (OR = 1.15, 95% CI = 1.00-1.34). There was also a significant interaction between individual- and neighborhood-level bonding social capital, indicating that people with a weaker homogeneous network and living in a neighborhood with weaker bonding social capital were more likely to have depressive mood. Our results suggest that neighborhood social capital does not necessarily benefit mental health in old age. These findings might stimulate further discussion on the relationship of bonding and bridging social capital with mental health. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lessons learned from the Tappan Zee Bridge, New York

DOT National Transportation Integrated Search

2003-01-01

The Governor Malcolm E. Wilson Tappan Zee Bridge carries the New York Thruway's mainline across the Hudson River. The bridge showed signs of deterioration from the early 1990s. Damage due to increased traffic levels, chloride ion penetration in the c...

Analysis, inspection, and repair methods for pin connections on Illinois bridges

DOT National Transportation Integrated Search

1992-04-01

This report documents methods used in Illinois for analysis, inspection, and repair of pin connections in bridges. Weldable foil strain gages were used to detect the effects of unknown levels of fixity in pins on cantilever truss bridges. Other metho...

Seismic response of precast segmental bridge superstructures.

DOT National Transportation Integrated Search

2006-12-01

Precast segmental construction of bridges can accelerate construction and minimize the cost of bridges in highly congested urban environments and environmentally sensitive regions. Despite their proven benefits, the use of precast segmental bridges i...

Bridging the Gap: Implementing School-to-Work Transition in Austin, Texas. Policy Research Project Report Number 103.

ERIC Educational Resources Information Center

Texas Univ., Austin. Lyndon B. Johnson School of Public Affairs.

Recognizing the difficult time most youths face in finding a good job after high school graduation, the Austin (Texas) Independent School District developed strategies to improve the transition. A high level of collaborative activity was already underway in Austin between the school district and the community, but most programs had been started…

Simple model of cable-stayed bridge deck subjected to static wind loading

NASA Astrophysics Data System (ADS)

Kang, Yi-Lung; Wang, Yang Cheng

1997-05-01

Cable-stayed bridges have been known since 18th century with aesthetics design. The structural system and the structural behavior are significantly different from those of continuous bridges. Compared to continuous bridge, cable- stayed bridges have more flexure bridge deck than those of continuous bridges.On the other hand, cable-stayed bridges have less stiffness to resist wind loading especially for lateral loads. The first considering of bridge engineering is safety. In 1940's, Tacoma Narrows Suspension Bridge destroyed by wind loading is a good example even though it is not a cable-stayed bridge. After the bridge was destroyed, a lot of research articles have been published regarding cable supported bridge subjected to wind loading. In recent days, high strength materials have been served. The bridge engineers use the advantages to expand the span length of cable-stayed bridges. Due to the span length increased and the use of high strength materials, cable- stayed bridges have more significant nonlinear behavior subjected to wind loading. In this paper, a slice bridge deck of cable-stayed bridge connected to internal support cables is considered. The deck has been considered to be subjected to lateral static wind loading. Since cables can not take compressive force, the deck has strongly nonlinear behavior even though the materials are linear elastic. Several primary load combinations have ben considered in this paper such as the bridge deck supposed to be moved horizontally without rotation or the bridge deck supposed to be moved horizontally with rotational deformation. The mathematical formulas and the numerical solutions are found and represented in graphical forms. The results can be provided to bridge designers and researchers for further study of this type of structure subjected to wind loading.

Comparison between Phase-Shift Full-Bridge Converters with Noncoupled and Coupled Current-Doubler Rectifier

PubMed Central

Tsai, Cheng-Tao; Tseng, Sheng-Yu

2013-01-01

This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications. PMID:24381521

Comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier.

PubMed

Tsai, Cheng-Tao; Su, Jye-Chau; Tseng, Sheng-Yu

2013-01-01

This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications.

Investigating the Associations between Ethnic Networks, Community Social Capital, and Physical Health among Marriage Migrants in Korea.

PubMed

Kim, Harris Hyun-Soo

2018-01-17

This study examines factors associated with the physical health of Korea's growing immigrant population. Specifically, it focuses on the associations between ethnic networks, community social capital, and self-rated health (SRH) among female marriage migrants. For empirical testing, secondary analysis of a large nationally representative sample (NSMF 2009) is conducted. Given the clustered data structure (individuals nested in communities), a series of two-level random intercepts and slopes models are fitted to probe the relationships between SRH and interpersonal (bonding and bridging) networks among foreign-born wives in Korea. In addition to direct effects, cross-level interaction effects are investigated using hierarchical linear modeling. While adjusting for confounders, bridging (inter-ethnic) networks are significantly linked with better health. Bonding (co-ethnic) networks, to the contrary, are negatively associated with immigrant health. Net of individual-level covariates, living in a commuijnity with more aggregate bridging social capital is positively linked with health. Community-level bonding social capital, however, is not a significant predictor. Lastly, two cross-level interaction terms are found. First, the positive relationship between bridging network and health is stronger in residential contexts with more aggregate bridging social capital. Second, it is weaker in communities with more aggregate bonding social capital.

Prevention of Bridge Scour with Non-uniform Circular Piers Plane under Steady Flows

NASA Astrophysics Data System (ADS)

Chen, Hsing-Ting; Wang, Chuan-Yi

2017-04-01

River bed scour and deposit variation extremely severe because of most of rivers are steep and rapid flows, and river discharge extremely unstable and highly unsteady during different seasons in Taiwan. In addition to the obstruction of piers foundation, it causes local scour and threatens the safety of bridges. In the past, riprap, wire gabion or wrap pier works were adopted as the protections of piers foundation, but there were no effectual outcomes. The events of break off piers still happen sometimes. For example, typhoon Kalmaegi (2008) and Morakot (2009) caused heavy damages on Ho-Fon bridge in the Da-jia river and Shuang-Yuan bridge in the Kao-Ping river, respectively. Accordingly, to understand the piers scour system and propose an appropriate protection of piers foundation becomes an important topic for this study currently. This research improves the protection works of the existing uniform bridge pier (diameter D) to ensure the safety of the bridge. The non-uniform plane of circular piers (diameter D*) are placed on the top of a bridge pier foundation to reduce the down flow impacting energy and scour by its' surface roughness characteristics. This study utilize hydraulic models to simulate local scour depth and scour depth change with time for non-uniform pier diameter ratio D/D* of 0.3,0.4,0.5,0.6,0.7 and 0.8, and different type pier and initial bed level (Y) relative under the foundation top elevation under steady flows of V/Vc=0.95,0.80 and 0.65. The research results show that the scour depth increases with an increase of flow intensity (V/Vc) under different types of steady flow hydrographs. The scour depth decreases with increase of initial bed level (Y=+0.2D*,0D*and -0.2D*) relative under the foundation top elevation of the different type pier. The maximum scour depth occurred in the front of the pier for all conditions. Because of the scouring retardation by the non-uniform plane of foundation, the scour depth is reduced for the un-exposed bridge foundation (Y=+0.2D*) under any steady flows. Opposite results are found for the exposed (Y=-0.2D*) bridge foundation. For the condition non-uniform pier diameter ratio (D/D*=0.3 0.8) scours, when D/D* is equal to 0.4, because pier oncoming flow area is the smallest one so that down flow intensity is less; as non-uniform area is bigger and decrease more down flow energy so that bring smaller scour depth and effect area. Therefore, local scour depth for pier diameter ratio of 0.4 is less than other type of pier. Considering the safety of bridge structure, a non-uniform circular pier with D/D* which equals to 0.4 and initial bed level relative to Y=+0.2D* is the most ideal pier allocations.

Innovative concrete bridging systems for pedestrian bridges : implementation and monitoring.

DOT National Transportation Integrated Search

2013-08-01

Two precast, prestressed pedestrian bridges were designed for rapid construction in Rolla, MO, utilizing high-strength concrete (HSC) : and high-strength self-consolidating concrete (HS-SCC) with a target 28 day compressive strength of 68.9 MPa (10,0...

High levels of telomere dysfunction bestow a selective disadvantage during the progression of human oral squamous cell carcinoma.

PubMed

Gordon, Katrina E; Ireland, Hazel; Roberts, Meryl; Steeghs, Karen; McCaul, James A; MacDonald, D Gordon; Parkinson, E Kenneth

2003-01-15

Human epithelial cells experience multiple barriers to cellular immortality in culture (mortality mechanisms 0, 1, and 2). Mortality mechanism 2 (M2) is termed crisis and involves telomere dysfunction due to lack of telomerase. However, proliferating normal keratinocytes in vivo can express telomerase, so it is unclear whether human squamous cell carcinomas (SCCs), which usually have high telomerase levels, develop from preexisting telomerase-positive precursors or by the activation of telomerase in telomerase-deficient somatic cells. We show that 6 of 29 oral SCCs show characteristics of M2 crisis in vivo, as indicated by a high anaphase bridge index (ABI), which is a good correlate of telomere dysfunction, and that 25 of 29 tumors possess some anaphase bridges. ABIs in excess of 0.2 in the primary tumor showed a decrease in the corresponding lymph node metastases. This suggests that high levels of telomere dysfunction (>0.2) and, by inference, M2 crisis bestow a selective disadvantage on SCCs during progression stages of the disease. Supporting this, SCCs with high levels of telomere dysfunction grow poorly in culture, and the ectopic expression of telomerase corrects this, together with other features of M2 crisis. Our data suggest that a substantial proportion of oral SCCs in vivo ultimately arise from telomerase-deficient keratinocytes rather than putative telomerase-proficient cells in the undifferentiated parts of the epithelium. Furthermore, the presence of significant levels of telomere dysfunction in a high proportion of SCCs at diagnosis but not in the normal epithelium implies that the therapeutic inhibition of telomerase should selectively compromise the growth of such tumors.

Bridge scour monitoring technologies : development of evaluation and selection protocols for application on river bridges in Minnesota.

DOT National Transportation Integrated Search

2010-03-01

Bridge failure or loss of structural integrity can result from scour of riverbed sediment near bridge abutments or : piers during high-flow events in rivers. In the past 20 years, several methods of monitoring bridge scour have been : developed spann...

Structural evaluation of the John A. Roebling Suspension Bridge : element level analysis.

DOT National Transportation Integrated Search

2008-07-01

The primary objective of the structural evaluation of the John A. Roebling Bridge is to determine the maximum allowable gross vehicle weight (GVW) that can be carried by the bridge deck structural elements such as the open steel grid deck, channels, ...

78 FR 64189 - Drawbridge Operation Regulation; Raccoon Creek, Bridgeport, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-28

... governs the U.S. Route 130 lift Bridge over Raccoon Creek at mile marker 1.8 in Bridgeport, NJ. Bridge...-lift bridge is 5 feet above mean high water in the closed position and 64 above mean high water in the...

Evaluation of high performance pavement and bridge deck wearing surface repair materials.

DOT National Transportation Integrated Search

2016-08-01

This project provided for a laboratory and field testing of several high performance repair materials for : pavements and concrete bridge decks. The main purpose was to provide ODOT with materials and procedures : to shorten road and bridge closures....

Probabilistic Fatigue Life Updating for Railway Bridges Based on Local Inspection and Repair.

PubMed

Lee, Young-Joo; Kim, Robin E; Suh, Wonho; Park, Kiwon

2017-04-24

Railway bridges are exposed to repeated train loads, which may cause fatigue failure. As critical links in a transportation network, railway bridges are expected to survive for a target period of time, but sometimes they fail earlier than expected. To guarantee the target bridge life, bridge maintenance activities such as local inspection and repair should be undertaken properly. However, this is a challenging task because there are various sources of uncertainty associated with aging bridges, train loads, environmental conditions, and maintenance work. Therefore, to perform optimal risk-based maintenance of railway bridges, it is essential to estimate the probabilistic fatigue life of a railway bridge and update the life information based on the results of local inspections and repair. Recently, a system reliability approach was proposed to evaluate the fatigue failure risk of structural systems and update the prior risk information in various inspection scenarios. However, this approach can handle only a constant-amplitude load and has limitations in considering a cyclic load with varying amplitude levels, which is the major loading pattern generated by train traffic. In addition, it is not feasible to update the prior risk information after bridges are repaired. In this research, the system reliability approach is further developed so that it can handle a varying-amplitude load and update the system-level risk of fatigue failure for railway bridges after inspection and repair. The proposed method is applied to a numerical example of an in-service railway bridge, and the effects of inspection and repair on the probabilistic fatigue life are discussed.

Probabilistic Fatigue Life Updating for Railway Bridges Based on Local Inspection and Repair

PubMed Central

Lee, Young-Joo; Kim, Robin E.; Suh, Wonho; Park, Kiwon

2017-01-01

Railway bridges are exposed to repeated train loads, which may cause fatigue failure. As critical links in a transportation network, railway bridges are expected to survive for a target period of time, but sometimes they fail earlier than expected. To guarantee the target bridge life, bridge maintenance activities such as local inspection and repair should be undertaken properly. However, this is a challenging task because there are various sources of uncertainty associated with aging bridges, train loads, environmental conditions, and maintenance work. Therefore, to perform optimal risk-based maintenance of railway bridges, it is essential to estimate the probabilistic fatigue life of a railway bridge and update the life information based on the results of local inspections and repair. Recently, a system reliability approach was proposed to evaluate the fatigue failure risk of structural systems and update the prior risk information in various inspection scenarios. However, this approach can handle only a constant-amplitude load and has limitations in considering a cyclic load with varying amplitude levels, which is the major loading pattern generated by train traffic. In addition, it is not feasible to update the prior risk information after bridges are repaired. In this research, the system reliability approach is further developed so that it can handle a varying-amplitude load and update the system-level risk of fatigue failure for railway bridges after inspection and repair. The proposed method is applied to a numerical example of an in-service railway bridge, and the effects of inspection and repair on the probabilistic fatigue life are discussed. PMID:28441768

Building Better Bridges into STEM: A Synthesis of 25 Years of Literature on STEM Summer Bridge Programs

PubMed Central

Ashley, Michael; Cooper, Katelyn M.; Cala, Jacqueline M.; Brownell, Sara E.

2017-01-01

Summer bridge programs are designed to help transition students into the college learning environment. Increasingly, bridge programs are being developed in science, technology, engineering, and mathematics (STEM) disciplines because of the rigorous content and lower student persistence in college STEM compared with other disciplines. However, to our knowledge, a comprehensive review of STEM summer bridge programs does not exist. To provide a resource for bridge program developers, we conducted a systematic review of the literature on STEM summer bridge programs. We identified 46 published reports on 30 unique STEM bridge programs that have been published over the past 25 years. In this review, we report the goals of each bridge program and whether the program was successful in meeting these goals. We identify 14 distinct bridge program goals that can be organized into three categories: academic success goals, psychosocial goals, and department-level goals. Building on the findings of published bridge reports, we present a set of recommendations for STEM bridge programs in hopes of developing better bridges into college. PMID:29146667

Long-Term Structural Health Monitoring System for a High-Speed Railway Bridge Structure.

PubMed

Ding, You-Liang; Wang, Gao-Xin; Sun, Peng; Wu, Lai-Yi; Yue, Qing

2015-01-01

Nanjing Dashengguan Bridge, which serves as the shared corridor crossing Yangtze River for both Beijing-Shanghai high-speed railway and Shanghai-Wuhan-Chengdu railway, is the first 6-track high-speed railway bridge with the longest span throughout the world. In order to ensure safety and detect the performance deterioration during the long-time service of the bridge, a Structural Health Monitoring (SHM) system has been implemented on this bridge by the application of modern techniques in sensing, testing, computing, and network communication. The SHM system includes various sensors as well as corresponding data acquisition and transmission equipment for automatic data collection. Furthermore, an evaluation system of structural safety has been developed for the real-time condition assessment of this bridge. The mathematical correlation models describing the overall structural behavior of the bridge can be obtained with the support of the health monitoring system, which includes cross-correlation models for accelerations, correlation models between temperature and static strains of steel truss arch, and correlation models between temperature and longitudinal displacements of piers. Some evaluation results using the mean value control chart based on mathematical correlation models are presented in this paper to show the effectiveness of this SHM system in detecting the bridge's abnormal behaviors under the varying environmental conditions such as high-speed trains and environmental temperature.

Quantification of cracks in concrete bridge decks in Ohio District 3.

DOT National Transportation Integrated Search

2012-02-01

The development of cracks in reinforced bridge decks is a critical problem, not only in Ohio state, but the whole of United States. Many bridge decks constructed within the last 10 years in Ohio have already shown varying levels and patterns of crack...

Quantification of cracks in concrete bridge decks in Ohio district 3.

DOT National Transportation Integrated Search

2012-02-01

The development of cracks in reinforced bridge decks is a critical problem, not only in Ohio state, but the whole of United States. Many bridge decks constructed within the last 10 years in Ohio have already shown varying levels and patterns of crack...

Level II scour analysis for Bridge 28 (BRNATH00660028) on Town Highway 66, crossing Locust Creek, Barnard, Vermont

USGS Publications Warehouse

Severence, Timothy

1997-01-01

The Town Highway 66 crossing of the Locust Creek is a 41-ft-long, one-lane bridge consisting of a 39 ft steel stringer type bridge with a concrete deck (Vermont Agency of Transportation, written communication, August 24, 1994). The clear span is 36.8 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The upstream right wingwall is protected by stone fill. The channel is skewed approximately 10 degrees to the opening while the opening-skew-to-roadway is 0 degrees. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E.

Design, construction, and field testing of an ultra high performance concrete pi-girder bridge.

DOT National Transportation Integrated Search

2011-01-01

The Jakway Park Bridge in Buchanan County, Iowa is the first bridge constructed with a new prestesssed girder system composed of : precast Ultra-High Performance Concrete (UHPC). These girders employ an integral deck to facilitate construction and ar...

Anomalies in Network Bridges Involved in Bile Acid Metabolism Predict Outcomes of Colorectal Cancer Patients

PubMed Central

Yoon, Seyeol; Lee, Jae W.; Lee, Doheon

2014-01-01

Biomarkers prognostic for colorectal cancer (CRC) would be highly desirable in clinical practice. Proteins that regulate bile acid (BA) homeostasis, by linking metabolic sensors and metabolic enzymes, also called bridge proteins, may be reliable prognostic biomarkers for CRC. Based on a devised metric, “bridgeness,” we identified bridge proteins involved in the regulation of BA homeostasis and identified their prognostic potentials. The expression patterns of these bridge proteins could distinguish between normal and diseased tissues, suggesting that these proteins are associated with CRC pathogenesis. Using a supervised classification system, we found that these bridge proteins were reproducibly prognostic, with high prognostic ability compared to other known markers. PMID:25259881

H-Bridge Inverter Loading Analysis for an Energy Management System

DTIC Science & Technology

2013-06-01

In order to accomplish the stated objectives, a physics-based model of the system was developed in MATLAB/Simulink. The system was also implemented ...functional architecture and then compile the high level design down to VHDL in order to program the designed functions to the FPGA. B. INSULATED

Challenges and Opportunities for Evaluating Environmental Education Programs

ERIC Educational Resources Information Center

Carleton-Hug, Annelise; Hug, J. William

2010-01-01

Environmental education organizations can do more to either institute evaluation or improve the quality of their evaluation. In an effort to help evaluators bridge the gap between the potential for high quality evaluation systems to improve environmental education, and the low level of evaluation in actual practice, we reviewed recent…

Development of methods for improving levels 1 and 2 met/ocean parameter predictions

DOT National Transportation Integrated Search

2011-02-01

The prediction of storm surge and wave forces and moments on bridges requires knowledge of design (100-year) water levels and wave heights and periods (met/ocean conditions) as well as bridge dimensions, elevation, orientation, etc. The American Asso...

Solar power generation system for reducing leakage current

NASA Astrophysics Data System (ADS)

Wu, Jinn-Chang; Jou, Hurng-Liahng; Hung, Chih-Yi

2018-04-01

This paper proposes a transformer-less multi-level solar power generation system. This solar power generation system is composed of a solar cell array, a boost power converter, an isolation switch set and a full-bridge inverter. A unipolar pulse-width modulation (PWM) strategy is used in the full-bridge inverter to attenuate the output ripple current. Circuit isolation is accomplished by integrating the isolation switch set between the solar cell array and the utility, to suppress the leakage current. The isolation switch set also determines the DC bus voltage for the full-bridge inverter connecting to the solar cell array or the output of the boost power converter. Accordingly, the proposed transformer-less multi-level solar power generation system generates a five-level voltage, and the partial power of the solar cell array is also converted to AC power using only the full-bridge inverter, so the power efficiency is increased. A prototype is developed to validate the performance of the proposed transformer-less multi-level solar power generation system.

Developing a Tele-Robotic Platform for Bridge Inspection

DOT National Transportation Integrated Search

2011-05-01

There are many bridges in Virginia with high traffic volumes or difficult access conditions which make these bridges difficult and expensive to inspect. In addition, the inspection of many bridges exposes the inspectors to hazardous conditions such a...

An expert system for the esthetic rating of bridges.

DOT National Transportation Integrated Search

1990-01-01

The expert system presented should facilitate the in-depth analysis of bridge esthetics and encourage high standards for the appearance of bridges. The procedure described systematically evaluates features of a target bridge in relation to a similar ...

High-efficiency emitting materials based on phenylquinoline/carbazole-based compounds for organic light emitting diode applications

NASA Astrophysics Data System (ADS)

Jin, Sung-Ho

2009-08-01

Highly efficient light-emitting materials based on phenylquinoline-carbazole derivative has been synthesized for organic-light emitting diodes (OLEDs). The materials form high quality amorphous thin films by thermal evaporation and the energy levels can be easily adjusted by the introduction of different electron donating and electron withdrawing groups on carbazoylphenylquinoline. Non-doped deep-blue OLEDs using Et-CVz-PhQ as the emitter show bright emission (CIE coordinates, x=0.156, y=0.093) with an external quantum efficiency of 2.45 %. Furthermore, the material works as an excellent host material for BCzVBi to get high-performance OLEDs with excellent deep-blue CIE coordinates (x=0.155, y=0.157), high power efficiency (5.98 lm/W), and high external quantum efficiency (5.22 %). Cyclometalated Ir(III) μ-chloride bridged dimers were synthesized by iridium trichloride hydrate with an excess of our developed deep-blue emitter, Et-CVz-PhQ. The Ir(III) complexes were prepared by the dimers with the corresponding ancillary ligands. The chloride bridged diiridium complexes can be easily converted to mononuclear Ir(III) complexes by replacing the two bridging chlorides with bidentate monoanionic ancillary ligands. Among the various types of ancillary ligands, we firstly used picolinic acid N-oxide, including picolinic acid and acetylacetone as an ancillary ligands for Ir(III) complexes. The PhOLEDs also shows reasonably high brightness and good luminance efficiency of 20,000 cd/m2 and 12 cd/A, respectively.

Displacement monitoring and modelling of a high-speed railway bridge using C-band Sentinel-1 data

NASA Astrophysics Data System (ADS)

Huang, Qihuan; Crosetto, Michele; Monserrat, Oriol; Crippa, Bruno

2017-06-01

Bridge displacement monitoring is one of the key components of bridge structural health monitoring. Traditional methods, usually based on limited sets of sensors mounted on a given bridge, collect point-like deformation information and have the disadvantage of providing incomplete displacement information. In this paper, a Persistent Scatterer Interferometry (PSI) approach is used to monitor the displacements of the Nanjing Dashengguan Yangtze River high-speed railway bridge. Twenty-nine (29) European Space Agency Sentinel-1A images, acquired from April 25, 2015 to August 5, 2016, were used in the PSI analysis. A total of 1828 measurement points were selected on the bridge. The results show a maximum longitudinal displacement of about 150 mm on each side of the bridge. The measured displacements showed a strong correlation with the environmental temperature at the time the images used were acquired, indicating that they were due to thermal expansion of the bridge. At each pier, a regression model based on the PSI-measured displacements was compared with a model based on in-situ measurements. The good agreement of these models demonstrates the capability of the PSI technique to monitor long-span railway bridge displacements. By comparing the modelled displacements and dozens of PSI measurements, we show how the performance of movable bearings can be evaluated. The high density of the PSI measurement points is advantageous for the health monitoring of the entire bridge.

Detection of CMOS bridging faults using minimal stuck-at fault test sets

NASA Technical Reports Server (NTRS)

Ijaz, Nabeel; Frenzel, James F.

1993-01-01

The performance of minimal stuck-at fault test sets at detecting bridging faults are evaluated. New functional models of circuit primitives are presented which allow accurate representation of bridging faults under switch-level simulation. The effectiveness of the patterns is evaluated using both voltage and current testing.

The Role of Visuospatial Resources in Generating Predictive and Bridging Inferences

ERIC Educational Resources Information Center

Fincher-Kiefer, Rebecca; D'Agostino, Paul R.

2004-01-01

It has been suggested that predictive and bridging inferences are generated at different levels of text representation: predictive inferences at a reader's situation model and bridging inferences at a reader's propositional textbase (Fincher-Kiefer, 1993, 1996; McDaniel, Schmalhofer, & Keefe, 2001; Schmalhofer, McDaniel, & Keefe, 2002). Recently,…

Contributions of diesel truck emissions to indoor elemental carbon concentrations in homes in proximity to Ambassador Bridge

NASA Astrophysics Data System (ADS)

Baxter, Lisa K.; Barzyk, Timothy M.; Vette, Alan F.; Croghan, Carry; Williams, Ronald W.

Ambassador Bridge, connecting Detroit, Michigan and Windsor, Ontario, is the busiest international commercial vehicle crossing in North America, with a large percentage of heavy duty diesel trucks. This study seeks to examine the contribution of diesel truck traffic across Ambassador Bridge to indoor exposure patterns of elemental carbon (EC), a common surrogate for diesel exhaust particles, in homes in close proximity to the bridge. We also aim to understand the relative importance of home ventilation characteristics and wind speed. Measurements were collected as part of the Detroit Exposure and Aerosol Research Study (DEARS). Residential indoor and outdoor EC measurements were collected over five consecutive 24 h periods in both the summer and winter at 16 homes in close proximity to Ambassador Bridge. Ambient concentrations and meteorological data were collected at a central-site monitor, and home air exchange rates were estimated using a perfluorocarbon tracer. The contributions of ambient concentrations and Ambassador Bridge, and potential effect modification by wind speed and home ventilation status were quantified with regression analyses. Both ambient concentrations and the percentage of time a home was downwind from the bridge were associated with an increase in indoor concentrations. Ambient concentrations significantly contributed to indoor concentrations regardless of wind speed category but were a greater influence in home experiencing calm winds. The effect of the percent of time downwind variable on indoor levels was only significant in homes where the ventilation status was high. The distance a home was from the bridge tollbooth complex was not significantly associated with indoor concentrations. We conclude that diesel traffic emissions related to Ambassador Bridge may have an impact on indoor EC exposures. Given that people spend the majority of their time indoors, it is important to evaluate the impact of traffic-related pollution in the home environment.

Feeding a sub-ns-risetime rectangular pulse onto a rod-shaped resistive high-voltage divider in risetime <2 ns

NASA Astrophysics Data System (ADS)

Zeng, Zhengzhong; Ma, Lianying

2004-01-01

A simple and effective bridge-type feeding network consisting only of ordinary resistors and conductive wires is designed and tested which launches a 0.8 ns risetime, 40 ns width, and kV-level rectangular pulse from a coaxial cable onto a rod-shaped resistive high-voltage divider with risetime <2 ns with no significant distortion.

Back to the Future with Business and Marketing Education. Annual Atlantic Coast Business and Marketing Education Conference Proceedings (12th, Raleigh, North Carolina, February 17-18, 1995).

ERIC Educational Resources Information Center

Joyner, Randy L., Ed.

This proceedings includes: "Bridging the International Learning Gap" (Arnold); "Back to the Future" (Baker); "Conducting Successful Class Projects over the Internet" (Beasley); "The Need for Ethics Instruction at the High School Level" (Brown); "Incorporating Industry-Based Skills Standards into High School Secretarial Programs" (Bunn);…

Terrorism Risk Modeling for Intelligence Analysis and Infrastructure Protection

DTIC Science & Technology

2007-01-01

comparatively high risk of CBRN attacks. Estimates of sabotage risk are highly dependent on proximity of nuclear power plants , chemical plants , or oil...and casinos, airports, nuclear power plants 3 Military, train and subway stations, stadiums, bridges and tunnels 4 Industrial facilities, oil and...airspace zones 8 Power plants , dams, railway networks levels. Collecting and incorporating such data for specific localities or industry sectors would

Application of Classical Land Surveying Measurement Methods for Determining the Vertical Displacement of Railway Bridges

NASA Astrophysics Data System (ADS)

Gawronek, Pelagia; Makuch, Maria

2017-12-01

The classical measurements of stability of railway bridge, in the context of determining the vertical displacements of the object, consisted on precise leveling of girders and trigonometric leveling of controlled points (fixed into girders' surface). The construction elements, which were measured in two ways, in real terms belonged to the same vertical planes. Altitude measurements of construction were carried out during periodic structural stability tests and during static load tests of bridge by train. The specificity of displacement measurements, the type of measured object and the rail land surveying measurement conditions were determinants to define methodology of altitude measurement. The article presents compatibility of vertical displacements of steel railway bridge, which were developed in two measurement methods. In conclusion, the authors proposed the optimum concept of determining the vertical displacements of girders by using precise and trigonometric leveling (in terms of accuracy, safety and economy of measurement).

Structural monitoring of Rigolets Pass Bridge : LTRC technical summary report 437.

DOT National Transportation Integrated Search

2009-09-01

The Louisiana Department of Transportation and Development (LADOTD) has been gradually : introducing high performance concrete (HPC) into their bridge construction programs. The : Rigolets Pass Bridge is a 62-span bridge with a total length of 5,489 ...

Improved Simplified Methods for Effective Seismic Analysis and Design of Isolated and Damped Bridges in Western and Eastern North America

NASA Astrophysics Data System (ADS)

Koval, Viacheslav

The seismic design provisions of the CSA-S6 Canadian Highway Bridge Design Code and the AASHTO LRFD Seismic Bridge Design Specifications have been developed primarily based on historical earthquake events that have occurred along the west coast of North America. For the design of seismic isolation systems, these codes include simplified analysis and design methods. The appropriateness and range of application of these methods are investigated through extensive parametric nonlinear time history analyses in this thesis. It was found that there is a need to adjust existing design guidelines to better capture the expected nonlinear response of isolated bridges. For isolated bridges located in eastern North America, new damping coefficients are proposed. The applicability limits of the code-based simplified methods have been redefined to ensure that the modified method will lead to conservative results and that a wider range of seismically isolated bridges can be covered by this method. The possibility of further improving current simplified code methods was also examined. By transforming the quantity of allocated energy into a displacement contribution, an idealized analytical solution is proposed as a new simplified design method. This method realistically reflects the effects of ground-motion and system design parameters, including the effects of a drifted oscillation center. The proposed method is therefore more appropriate than current existing simplified methods and can be applicable to isolation systems exhibiting a wider range of properties. A multi-level-hazard performance matrix has been adopted by different seismic provisions worldwide and will be incorporated into the new edition of the Canadian CSA-S6-14 Bridge Design code. However, the combined effect and optimal use of isolation and supplemental damping devices in bridges have not been fully exploited yet to achieve enhanced performance under different levels of seismic hazard. A novel Dual-Level Seismic Protection (DLSP) concept is proposed and developed in this thesis which permits to achieve optimum seismic performance with combined isolation and supplemental damping devices in bridges. This concept is shown to represent an attractive design approach for both the upgrade of existing seismically deficient bridges and the design of new isolated bridges.

Engaging Faculty for Innovative STEM Bridge Programs

ERIC Educational Resources Information Center

Goldfien, Andrea C.; Badway, Norena Norton

2014-01-01

Bridge programs, in which underprepared students gain the academic and technical skills necessary for college level courses and entry-level employment, are a promising initiative for expanding access to, and success in, community college education. For career pathways related to science, technology, engineering, or mathematics (STEM), bridge…

Bridge Displacement Monitoring Method Based on Laser Projection-Sensing Technology

PubMed Central

Zhao, Xuefeng; Liu, Hao; Yu, Yan; Xu, Xiaodong; Hu, Weitong; Li, Mingchu; Ou, Jingping

2015-01-01

Bridge displacement is the most basic evaluation index of the health status of a bridge structure. The existing measurement methods for bridge displacement basically fail to realize long-term and real-time dynamic monitoring of bridge structures, because of the low degree of automation and the insufficient precision, causing bottlenecks and restriction. To solve this problem, we proposed a bridge displacement monitoring system based on laser projection-sensing technology. First, the laser spot recognition method was studied. Second, the software for the displacement monitoring system was developed. Finally, a series of experiments using this system were conducted, and the results show that such a system has high measurement accuracy and speed. We aim to develop a low-cost, high-accuracy and long-term monitoring method for bridge displacement based on these preliminary efforts. PMID:25871716

8. Copyphoto of 1934 aerial photo, view to the east, ...

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

8. Copy-photo of 1934 aerial photo, view to the east, by the U.S. Army Air Corps, showing bridge tender's station and Mud Bayou Railway Bridge under construction - High Island Bridge Tender's Station, State Highway 124 Crossing of Mud Bayou, High Island, Galveston County, TX

Long-term monitoring of the HPC Charenton Canal Bridge.

DOT National Transportation Integrated Search

2011-08-01

The report contains long-term monitoring data collection and analysis of the first fully high : performance concrete (HPC) bridge in Louisiana, the Charenton Canal Bridge. The design of this : bridge started in 1997, and it was built and opened to tr...

Short- and long-term monitoring of underwater sound levels in the Hudson River (New York, USA).

PubMed

Martin, S Bruce; Popper, Arthur N

2016-04-01

There is a growing body of research on natural and man-made sounds that create aquatic soundscapes. Less is known about the soundscapes of shallow waters, such as in harbors, rivers, and lakes. Knowledge of soundscapes is needed as a baseline against which to determine the changes in noise levels resulting from human activities. To provide baseline data for the Hudson River at the site of the Tappan Zee Bridge, 12 acoustic data loggers were deployed for a 24-h period at ranges of 0-3000 m from the bridge, and four of the data loggers were re-deployed for three months of continuous recording. Results demonstrate that this region of the river is relatively quiet compared to open ocean conditions and other large river systems. Moreover, the soundscape had temporal and spatial diversity. The temporal patterns of underwater noise from the bridge change with the cadence of human activity. Bridge noise (e.g., road traffic) was only detected within 300 m; farther from the bridge, boating activity increased sound levels during the day, and especially on the weekend. Results also suggest that recording near the river bottom produced lower pseudo-noise levels than previous studies that recorded in the river water column.

Long-Term Structural Health Monitoring System for a High-Speed Railway Bridge Structure

PubMed Central

Wu, Lai-Yi

2015-01-01

Nanjing Dashengguan Bridge, which serves as the shared corridor crossing Yangtze River for both Beijing-Shanghai high-speed railway and Shanghai-Wuhan-Chengdu railway, is the first 6-track high-speed railway bridge with the longest span throughout the world. In order to ensure safety and detect the performance deterioration during the long-time service of the bridge, a Structural Health Monitoring (SHM) system has been implemented on this bridge by the application of modern techniques in sensing, testing, computing, and network communication. The SHM system includes various sensors as well as corresponding data acquisition and transmission equipment for automatic data collection. Furthermore, an evaluation system of structural safety has been developed for the real-time condition assessment of this bridge. The mathematical correlation models describing the overall structural behavior of the bridge can be obtained with the support of the health monitoring system, which includes cross-correlation models for accelerations, correlation models between temperature and static strains of steel truss arch, and correlation models between temperature and longitudinal displacements of piers. Some evaluation results using the mean value control chart based on mathematical correlation models are presented in this paper to show the effectiveness of this SHM system in detecting the bridge's abnormal behaviors under the varying environmental conditions such as high-speed trains and environmental temperature. PMID:26451387

Drowned reefs and antecedent karst topography, Au'au channel, S.E. Hawaiian Islands

USGS Publications Warehouse

Grigg, R.W.; Grossman, E.E.; Earle, S.A.; Gittings, S.R.; Lott, D.; McDonough, J.

2002-01-01

During the last glacial maximum (LGM), about 21,000 years ago, the Hawaiian Islands of Maui, Lanai, and Molokai were interconnected by limestone bridges, creating a super-island known as Maui-Nui. Approximately 120 m of sea-level rise during the Holocene Transgression flooded, and then drowned, these bridges separating the islands by inter-island channels. A new multibeam high-resolution bathymetric survey of the channels between the islands, coupled with observations and video-transects utilizing DeepWorker-2000 submersibles, has revealed the existence of numerous drowned reef features including concentric solution basins, solution ridges (rims), sand and sediment plains, and conical-shaped reef pinnacles. The concentric basins contain flat lagoon-like bottoms that are rimmed by steep-sided limestone walls. Undercut notches rim the basins at several depths, marking either sea-level still stands or paleo-lake levels. All of the solution basins shallower than 120 m were subaerial at the LGM, and at one stage or another may have been shallow shoreline lakes. Today, about 70 drowned reef pinnacles are scattered across the Maui-Lanai underwater bridge and all are situated in wave-sheltered positions. Most drowned during the interval between 14,000 and 10,000 years ago when sea-level rise averaged 15 mm/year. Virtually all of the surficial topography in the Au'au Channel today is a product of karst processes accentuated by marginal reef growth during the Holocene. Both the submerged basins and the drowned reefs represent an archive of sea-level and climate history in Hawaii during the late Quaternary.

Interracial Bridging Social Capital among Students of a Multicultural University in Malaysia

ERIC Educational Resources Information Center

Tamam, Ezhar

2013-01-01

In this study, the influence of interracial socialization and race on interracial bridging social capital among Malaysian students of a multicultural Malaysian public university was examined. Results reveal a narrowed level of interracial bridging social capital among the students. The minority Chinese and the majority Malays do not differ in…

Bridging Learning Opportunities: AMTEC '93 Conference Proceedings (Windsor, Ontario, Canada, June 14-16, 1993).

ERIC Educational Resources Information Center

Selby, Stuart, Ed.; Marzotto, Esio, Ed.

The bridging theme of the AMTEC'93 conference provided the stimulation to look beyond traditional boundaries: across international borders; across levels of disciplines and school systems; across social differences and across individual differences. These bridges can help make learning more effective, as can attention to related contemporary…

A Temperature-Based Monitoring System for Scour and Deposition at Bridge Piers

DOT National Transportation Integrated Search

2017-05-01

Stream flows around a bridge pier can be fast and highly turbulent causing large shear stresses that may mobilize streambed sediment resulting in scour around bridge foundations. Scour is the leading cause of bridge failure in the USA because it comp...

Extreme storms, sea level rise, and coastal change: implications for infrastructure reliability in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Anarde, K.; Kameshwar, S.; Irza, N.; Lorenzo-Trueba, J.; Nittrouer, J. A.; Padgett, J.; Bedient, P. B.

2016-12-01

Predicting coastal infrastructure reliability during hurricane events is important for risk-based design and disaster planning, such as delineating viable emergency response routes. Previous research has focused on either infrastructure vulnerability to coastal flooding or the impact of changing sea level and landforms on surge dynamics. Here we investigate the combined impact of sea level, morphology, and coastal flooding on the reliability of highway bridges - the only access points between barrier islands and mainland communities - during future extreme storms. We forward model coastal flooding for static projections of geomorphic change using ADCIRC+SWAN. First-order parameters that are adjusted include sea level and elevation. These are varied for each storm simulation to evaluate relative impact on the reliability of bridges surrounding Freeport, TX. Simulated storms include both synthetic and historical events, which are classified by intensity using the storm's integrated kinetic energy, a metric for surge generation potential. Reliability is estimated through probability of failure - given wave and surge loads - and time inundated. Findings include that: 1) bridge reliability scales inversely with surge height, and 2) sea level rise reduces bridge reliability due to a monotonic increase in surge height. The impact of a shifting landscape on bridge reliability is more complex: barrier island rollback can increase or decrease inundation times for storms of different intensity due to changes in wind-setup and back-barrier bay interactions. Initial storm surge readily inundates the coastal landscape during large intensity storms, however the draining of inland bays following storm passage is significantly impeded by the barrier. From a coastal engineering standpoint, we determine that to protect critical infrastructure, efforts now implemented that nourish low-lying barriers may be enhanced by also armoring back-bay coastlines and elevating bridge approach ramps.

Role of the Conserved Disulfide Bridge in Class A Carbapenemases*

PubMed Central

Smith, Clyde A.; Nossoni, Zahra; Toth, Marta; Stewart, Nichole K.; Frase, Hilary; Vakulenko, Sergei B.

2016-01-01

Some members of the class A β-lactamase family are capable of conferring resistance to the last resort antibiotics, carbapenems. A unique structural feature of these clinically important enzymes, collectively referred to as class A carbapenemases, is a disulfide bridge between invariant Cys69 and Cys238 residues. It was proposed that this conserved disulfide bridge is responsible for their carbapenemase activity, but this has not yet been validated. Here we show that disruption of the disulfide bridge in the GES-5 carbapenemase by the C69G substitution results in only minor decreases in the conferred levels of resistance to the carbapenem imipenem and other β-lactams. Kinetic and circular dichroism experiments with C69G-GES-5 demonstrate that this small drop in antibiotic resistance is due to a decline in the enzyme activity caused by a marginal loss of its thermal stability. The atomic resolution crystal structure of C69G-GES-5 shows that two domains of this disulfide bridge-deficient enzyme are held together by an intensive hydrogen-bonding network. As a result, the protein architecture and imipenem binding mode remain unchanged. In contrast, the corresponding hydrogen-bonding networks in NMCA, SFC-1, and SME-1 carbapenemases are less intensive, and as a consequence, disruption of the disulfide bridge in these enzymes destabilizes them, which causes arrest of bacterial growth. Our results demonstrate that the disulfide bridge is essential for stability but does not play a direct role in the carbapenemase activity of the GES family of β-lactamases. This would likely apply to all other class A carbapenemases given the high degree of their structural similarity. PMID:27590339

Role of the Conserved Disulfide Bridge in Class A Carbapenemases.

PubMed

Smith, Clyde A; Nossoni, Zahra; Toth, Marta; Stewart, Nichole K; Frase, Hilary; Vakulenko, Sergei B

2016-10-14

Some members of the class A β-lactamase family are capable of conferring resistance to the last resort antibiotics, carbapenems. A unique structural feature of these clinically important enzymes, collectively referred to as class A carbapenemases, is a disulfide bridge between invariant Cys 69 and Cys 238 residues. It was proposed that this conserved disulfide bridge is responsible for their carbapenemase activity, but this has not yet been validated. Here we show that disruption of the disulfide bridge in the GES-5 carbapenemase by the C69G substitution results in only minor decreases in the conferred levels of resistance to the carbapenem imipenem and other β-lactams. Kinetic and circular dichroism experiments with C69G-GES-5 demonstrate that this small drop in antibiotic resistance is due to a decline in the enzyme activity caused by a marginal loss of its thermal stability. The atomic resolution crystal structure of C69G-GES-5 shows that two domains of this disulfide bridge-deficient enzyme are held together by an intensive hydrogen-bonding network. As a result, the protein architecture and imipenem binding mode remain unchanged. In contrast, the corresponding hydrogen-bonding networks in NMCA, SFC-1, and SME-1 carbapenemases are less intensive, and as a consequence, disruption of the disulfide bridge in these enzymes destabilizes them, which causes arrest of bacterial growth. Our results demonstrate that the disulfide bridge is essential for stability but does not play a direct role in the carbapenemase activity of the GES family of β-lactamases. This would likely apply to all other class A carbapenemases given the high degree of their structural similarity. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Design and Comparison of Cascaded H-Bridge, Modular Multilevel Converter, and 5-L Active Neutral Point Clamped Topologies for Motor Drive Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marzoughi, Alinaghi; Burgos, Rolando; Boroyevich, Dushan

This paper presents the design procedure and comparison of converters currently used in medium-voltage high-power motor drive applications. For this purpose, the cascaded H-bridge (CHB), modular multilevel converter (MMC), and five-level active neutral point clamped (5-L ANPC) topologies are targeted. The design is performed using 1.7-kV insulated gate bipolar transistors (IGBTs) for CHB and MMC converters, and utilizing 3.3- and 4.5-kV IGBTs for 5-L ANPC topology as normally done in industry. The comparison is done between the designed converter topologies at three different voltage levels (4.16, 6.9, and 13.8 kV, with only the first two voltage levels in case ofmore » the 5-L ANPC) and two different power levels (3 and 5 MVA), in order to elucidate the dependence of different parameters on voltage and power rating. Finally, the comparison is done from several points of view such as efficiency, capacitive energy storage, semiconductor utilization, parts count (for measure of reliability), and power density.« less

Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks : free shrinkage, moisture optimization and concrete production : final report.

DOT National Transportation Integrated Search

2009-08-01

The development and evaluation of low-cracking high-performance concrete (LC-HPC) for use in bridge decks : is described based on laboratory test results and experience gained during the construction of 14 bridges. This report : emphasizes the materi...

Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks : free shrinkage, moisture optimization and concrete production : summary report.

DOT National Transportation Integrated Search

2009-08-01

The development and evaluation of low-cracking high-performance concrete (LC-HPC) for use in bridge decks : is described based on laboratory test results and experience gained during the construction of 14 bridges. This report : emphasizes the materi...

Long-Term Deflection Prediction from Computer Vision-Measured Data History for High-Speed Railway Bridges

PubMed Central

Lee, Jaebeom; Lee, Young-Joo

2018-01-01

Management of the vertical long-term deflection of a high-speed railway bridge is a crucial factor to guarantee traffic safety and passenger comfort. Therefore, there have been efforts to predict the vertical deflection of a railway bridge based on physics-based models representing various influential factors to vertical deflection such as concrete creep and shrinkage. However, it is not an easy task because the vertical deflection of a railway bridge generally involves several sources of uncertainty. This paper proposes a probabilistic method that employs a Gaussian process to construct a model to predict the vertical deflection of a railway bridge based on actual vision-based measurement and temperature. To deal with the sources of uncertainty which may cause prediction errors, a Gaussian process is modeled with multiple kernels and hyperparameters. Once the hyperparameters are identified through the Gaussian process regression using training data, the proposed method provides a 95% prediction interval as well as a predictive mean about the vertical deflection of the bridge. The proposed method is applied to an arch bridge under operation for high-speed trains in South Korea. The analysis results obtained from the proposed method show good agreement with the actual measurement data on the vertical deflection of the example bridge, and the prediction results can be utilized for decision-making on railway bridge maintenance. PMID:29747421

Random vibration analysis of train-bridge under track irregularities and traveling seismic waves using train-slab track-bridge interaction model

NASA Astrophysics Data System (ADS)

Zeng, Zhi-Ping; Zhao, Yan-Gang; Xu, Wen-Tao; Yu, Zhi-Wu; Chen, Ling-Kun; Lou, Ping

2015-04-01

The frequent use of bridges in high-speed railway lines greatly increases the probability that trains are running on bridges when earthquakes occur. This paper investigates the random vibrations of a high-speed train traversing a slab track on a continuous girder bridge subjected to track irregularities and traveling seismic waves by the pseudo-excitation method (PEM). To derive the equations of motion of the train-slab track-bridge interaction system, the multibody dynamics and finite element method models are used for the train and the track and bridge, respectively. By assuming track irregularities to be fully coherent random excitations with time lags between different wheels and seismic accelerations to be uniformly modulated, non-stationary random excitations with time lags between different foundations, the random load vectors of the equations of motion are transformed into a series of deterministic pseudo-excitations based on PEM and the wheel-rail contact relationship. A computer code is developed to obtain the time-dependent random responses of the entire system. As a case study, the random vibration characteristics of an ICE-3 high-speed train traversing a seven-span continuous girder bridge simultaneously excited by track irregularities and traveling seismic waves are analyzed. The influence of train speed and seismic wave propagation velocity on the random vibration characteristics of the bridge and train are discussed.

Long-Term Deflection Prediction from Computer Vision-Measured Data History for High-Speed Railway Bridges.

PubMed

Lee, Jaebeom; Lee, Kyoung-Chan; Lee, Young-Joo

2018-05-09

Management of the vertical long-term deflection of a high-speed railway bridge is a crucial factor to guarantee traffic safety and passenger comfort. Therefore, there have been efforts to predict the vertical deflection of a railway bridge based on physics-based models representing various influential factors to vertical deflection such as concrete creep and shrinkage. However, it is not an easy task because the vertical deflection of a railway bridge generally involves several sources of uncertainty. This paper proposes a probabilistic method that employs a Gaussian process to construct a model to predict the vertical deflection of a railway bridge based on actual vision-based measurement and temperature. To deal with the sources of uncertainty which may cause prediction errors, a Gaussian process is modeled with multiple kernels and hyperparameters. Once the hyperparameters are identified through the Gaussian process regression using training data, the proposed method provides a 95% prediction interval as well as a predictive mean about the vertical deflection of the bridge. The proposed method is applied to an arch bridge under operation for high-speed trains in South Korea. The analysis results obtained from the proposed method show good agreement with the actual measurement data on the vertical deflection of the example bridge, and the prediction results can be utilized for decision-making on railway bridge maintenance.

An Electron-Deficient Building Block Based on the B←N Unit: An Electron Acceptor for All-Polymer Solar Cells.

PubMed

Dou, Chuandong; Long, Xiaojing; Ding, Zicheng; Xie, Zhiyuan; Liu, Jun; Wang, Lixiang

2016-01-22

A double B←N bridged bipyridyl (BNBP) is a novel electron-deficient building block for polymer electron acceptors in all-polymer solar cells. The B←N bridging units endow BNBP with fixed planar configuration and low-lying LUMO/HOMO energy levels. As a result, the polymer based on BNBP units (P-BNBP-T) exhibits high electron mobility, low-lying LUMO/HOMO energy levels, and strong absorbance in the visible region, which is desirable for polymer electron acceptors. Preliminary all-polymer solar cell (all-PSC) devices with P-BNBP-T as the electron acceptor and PTB7 as the electron donor exhibit a power conversion efficiency (PCE) of 3.38%, which is among the highest values of all-PSCs with PTB7 as the electron donor. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Probing the Properties of Polynuclear Superhalogens without Halogen Ligand via ab Initio Calculations: A Case Study on Double-Bridged [Mg2 (CN)5 ](-1) Anions.

PubMed

Li, Jin-Feng; Li, Miao-Miao; Bai, Hongcun; Sun, Yin-Yin; Li, Jian-Li; Yin, Bing

2015-12-01

An ab initio study of the superhalogen properties of eighteen binuclear double-bridged [Mg2 (CN)5 ](-1) clusters is reported herein by using various theoretical methods. High-level CCSD(T) results indicate that all the clusters possess strong superhalogen properties owing to their high vertical electron detachment energies (VDEs), which exceed 6.8 eV (highest: 8.15 eV). The outer valence Green's function method provides inaccurate relative VDE values; hence, this method is not suitable for this kind of polynuclear superhalogens. Both the HF and MP2 results are generally consistent with the CCSD(T) level regarding the relative VDE values and-especially interesting-the average values of the HF and MP2 VDEs are extremely close to the CCSD(T) results. The distributions of the extra electrons of the anions are mainly aggregated into the terminal CN units. These distributions are apparently different from those of previously reported triple-bridged isomers and may be the reason for the decreased VDE values of the clusters. In addition, comparisons of the VDEs of binuclear and mononuclear superhalogens as well as studies of the thermodynamic stabilities with respect to the detachment of various CN(-1) ligands are also performed. These results confirm that polynuclear structures with pseudohalogen ligands can be considered as probable new superhalogens with enhanced properties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Bridge of Knowledge

ERIC Educational Resources Information Center

Dong, Yu Ren

2014-01-01

Although many English language learners (ELLs) in the United States have knowledge gaps that make it hard for them to master high-level content and skills, ELLs also often have background knowledge relevant to school learning that teachers neglect to access, this author argues. In the Common Core era, with ELLs being the fastest growing population…

The Generalizability of Students' Interests in Biology across Gender, Country and Religion

ERIC Educational Resources Information Center

Hagay, G.; Baram-Tsabari, A.; Ametller, J.; Cakmakci, G.; Lopes, B.; Moreira, A.; Pedrosa-de-Jesus, H.

2013-01-01

In order to bridge the existing gap between biology curricula and students' interests in biology, a strategy for identifying students' interest based on their questions and integrating them into the curriculum was developed. To characterize the level of generalizability of students' science interests over 600 high school students from Portugal,…

The Role of Professional Development in Bridging Research and Practice in Adult Literacy and Basic Education

ERIC Educational Resources Information Center

Smith, Cristine

2016-01-01

In this brief article, Cristine Smith discusses the development and use of professional development activities at the national, state and local program level. Professional development systems and funding exist in every state, and the Workforce Innovation and Opportunity Act (WIOA) has prioritized high-quality professional development for…

Diderot: a Domain-Specific Language for Portable Parallel Scientific Visualization and Image Analysis.

PubMed

Kindlmann, Gordon; Chiw, Charisee; Seltzer, Nicholas; Samuels, Lamont; Reppy, John

2016-01-01

Many algorithms for scientific visualization and image analysis are rooted in the world of continuous scalar, vector, and tensor fields, but are programmed in low-level languages and libraries that obscure their mathematical foundations. Diderot is a parallel domain-specific language that is designed to bridge this semantic gap by providing the programmer with a high-level, mathematical programming notation that allows direct expression of mathematical concepts in code. Furthermore, Diderot provides parallel performance that takes advantage of modern multicore processors and GPUs. The high-level notation allows a concise and natural expression of the algorithms and the parallelism allows efficient execution on real-world datasets.

Energy harvesting from electrospun piezoelectric nanofibers for structural health monitoring of a cable-stayed bridge

NASA Astrophysics Data System (ADS)

Maruccio, Claudio; Quaranta, Giuseppe; De Lorenzis, Laura; Monti, Giorgio

2016-08-01

Wireless monitoring could greatly impact the fields of structural health assessment and infrastructure asset management. A common problem to be tackled in wireless networks is the electric power supply, which is typically provided by batteries replaced periodically. A promising remedy for this issue would be to harvest ambient energy. Within this framework, the present paper proposes to harvest ambient-induced vibrations of bridge structures using a new class of piezoelectric textiles. The considered case study is an existing cable-stayed bridge located in Italy along a high-speed road that connects Rome and Naples, for which a recent monitoring campaign has allowed to record the dynamic responses of deck and cables. Vibration measurements have been first elaborated to provide a comprehensive dynamic assessment of this infrastructure. In order to enhance the electric energy that can be converted from ambient vibrations, the considered energy harvester exploits a power generator built using arrays of electrospun piezoelectric nanofibers. A finite element analysis is performed to demonstrate that such power generator is able to provide higher energy levels from recorded dynamic loading time histories than a standard piezoelectric energy harvester. Its feasibility for bridge health monitoring applications is finally discussed.

Determination and reoxidation of the disulfide bridges of a squash-type trypsin inhibitor from Sechium edule seeds.

PubMed

Faça, Vitor M; Pereira, Sandra R; Laure, Hélen J; Greene, Lewis J

2004-07-01

The determination of the disulfide pairings of SETI-II, a trypsin inhibitor isolated from Sechium edule, is described herein. The inhibitor contains 31 amino acid residues per mol, 6 of which are cysteine. Forty-five nmol (160 microg) of SETI-II was hydrolyzed with 20 microg thermolysin for 48 hr at 45 degrees C, and peptides were separated by reverse phase high performance liquid chromatography (RP-HPLC). The major products were identified by amino acid composition, Edman degradation, and on the basis of the sequence of the inhibitor. The disulfide bridge pairings and (yields) are: Cys1-Cys4 (79%), Cys2-Cys5 (21%) and Cys3-Cys6 (43%). When the reduced inhibitor was reoxidized with glutathione reduced form (GSH)/glutathione oxidized form (GSSG) at pH 8.5 for 3 hr, full activity was recovered. These data show that disulfide bridge pairing and oxidation can be determined at nanomole levels and that sensitive and quantitative Edman degradation can eliminate the final time- and material-consuming step of disulfide determinations by eliminating the need to purify and cleave each peptide containing a disulfide bridge.

Ecological Perspectives for Successful Schooling Practice. Bridging Meeting Report (Elkridge, Maryland, November 15-17, 1981).

ERIC Educational Resources Information Center

Ward, Beatrice A.; And Others

This is a report of a meeting held: (1) to examine and discuss the results of the Junior High Transition Study in light of the work of other researchers; and (2) to develop a collective statement about what is and is not known about successful schooling at the junior high level and about problems on which future efforts should focus. The first…

High performance concrete bridges

DOT National Transportation Integrated Search

2000-08-01

This compilation of FHWA reports focuses on high performance concrete bridges. High performance concrete is described as concrete with enhanced durability and strength characteristics. Under the Strategic Highway Research Program (SHRP), more than 40...

Evaluation of streambed scour at bridges over tidal waterways in Alaska

USGS Publications Warehouse

Conaway, Jeffrey S.; Schauer, Paul V.

2012-01-01

The potential for streambed scour was evaluated at 41 bridges that cross tidal waterways in Alaska. These bridges are subject to several coastal and riverine processes that have the potential, individually or in combination, to induce streambed scour or to damage the structure or adjacent channel. The proximity of a bridge to the ocean and water-surface elevation and velocity data collected over a tidal cycle were criteria used to identify the flow regime at each bridge, whether tidal, riverine, or mixed, that had the greatest potential to induce streambed scour. Water-surface elevations measured through at least one tide cycle at 32 bridges were correlated to water levels at the nearest tide station. Asymmetry of the tidal portion of the hydrograph during the outgoing tide at 12 bridges indicated that riverine flows were stored upstream of the bridge during the tidal exchange. This scenario results in greater discharges and velocities during the outgoing tide compared to those on the incoming tide. Velocity data were collected during outgoing tides at 10 bridges that experienced complete flow reversals, and measured velocities during the outgoing tide exceeded the critical velocity required to initiate sediment transport at three sites. The primary risk for streambed scour at most of the sites considered in this study is from riverine flows rather than tidal fluctuations. A scour evaluation for riverine flow was completed at 35 bridges. Scour from riverine flow was not the primary risk for six tidally-controlled bridges and therefore not evaluated at those sites. Field data including channel cross sections, a discharge measurement, and a water-surface slope were collected at the 35 bridges. Channel instability was identified at 14 bridges where measurable scour and or fill were noted in repeated surveys of channel cross sections at the bridge. Water-surface profiles for the 1-percent annual exceedance probability discharge were calculated by using the Hydrologic Engineering Center’s River Analysis System model, and scour depths were calculated using methods recommended by the Federal Highway Administration. Computed contraction-scour depths were greater than 2.0 feet at five bridges and computed pier-scour depths were 4.0 feet or greater at 15 bridges. The potential for streambed scour by both coastal and riverine processes at the bridges considered in this study were evaluated, ranked, and summed to determine a cumulative risk factor for each bridge. Possible factors that could mitigate the scour risks were investigated at 22 bridges that had high individual or cumulative rankings. Mitigating factors such as piers founded in bedrock, deep pier foundations relative to scour depths, and lack of observed scour during field measurements were documented for 13 sites, but additional study and monitoring is needed to better quantify the streambed scour potential for nine sites. Three bridges prone to being affected by storm surges will require more data collection and possibly complex hydrodynamic modeling to accurately quantify the streambed scour potential. Continuous monitoring of water-surface and streambed elevation at one or more piers is needed for two bridges to better understand the tidal and riverine influences on streambed scour.

Fitness Effects of Chlorpyrifos in the Damselfly Enallagma cyathigerum Strongly Depend upon Temperature and Food Level and Can Bridge Metamorphosis

PubMed Central

Janssens, Lizanne; Stoks, Robby

2013-01-01

Interactions between pollutants and suboptimal environmental conditions can have severe consequences for the toxicity of pollutants, yet are still poorly understood. To identify patterns across environmental conditions and across fitness-related variables we exposed Enallagma cyathigerum damselfly larvae to the pesticide chlorpyrifos at two food levels or at two temperatures and quantified four fitness-related variables (larval survival, development time, mass at emergence and adult cold resistance). Food level and temperature did not affect survival in the absence of the pesticide, yet the pesticide reduced survival only at the high temperature. Animals reacted to the pesticide by accelerating their development but only at the high food level and at the low temperature; at the low food level, however, pesticide exposure resulted in a slower development. Chlorpyrifos exposure resulted in smaller adults except in animals reared at the high food level. Animals reared at the low food level and at the low temperature had a higher cold resistance which was not affected by the pesticide. In summary our study highlight that combined effects of exposure to chlorpyrifos and the two environmental conditions (i) were mostly interactive and sometimes even reversed in comparison with the effect of the environmental condition in isolation, (ii) strongly differed depending on the fitness-related variable under study, (iii) were not always predictable based on the effect of the environmental condition in isolation, and (iv) bridged metamorphosis depending on which environmental condition was combined with the pesticide thereby potentially carrying over from aquatic to terrestrial ecosystems. These findings are relevant when extrapolating results of laboratory tests done under ideal environmental conditions to natural communities. PMID:23840819

Remediation: Higher Education's Bridge to Nowhere

ERIC Educational Resources Information Center

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…

Development and simulation of microfluidic Wheatstone bridge for high-precision sensor

NASA Astrophysics Data System (ADS)

Shipulya, N. D.; Konakov, S. A.; Krzhizhanovskaya, V. V.

2016-08-01

In this work we present the results of analytical modeling and 3D computer simulation of microfluidic Wheatstone bridge, which is used for high-accuracy measurements and precision instruments. We propose and simulate a new method of a bridge balancing process by changing the microchannel geometry. This process is based on the “etching in microchannel” technology we developed earlier (doi:10.1088/1742-6596/681/1/012035). Our method ensures a precise control of the flow rate and flow direction in the bridge microchannel. The advantage of our approach is the ability to work without any control valves and other active electronic systems, which are usually used for bridge balancing. The geometrical configuration of microchannels was selected based on the analytical estimations. A detailed 3D numerical model was based on Navier-Stokes equations for a laminar fluid flow at low Reynolds numbers. We investigated the behavior of the Wheatstone bridge under different process conditions; found a relation between the channel resistance and flow rate through the bridge; and calculated the pressure drop across the system under different total flow rates and viscosities. Finally, we describe a high-precision microfluidic pressure sensor that employs the Wheatstone bridge and discuss other applications in complex precision microfluidic systems.

Army ants dynamically adjust living bridges in response to a cost-benefit trade-off.

PubMed

Reid, Chris R; Lutz, Matthew J; Powell, Scott; Kao, Albert B; Couzin, Iain D; Garnier, Simon

2015-12-08

The ability of individual animals to create functional structures by joining together is rare and confined to the social insects. Army ants (Eciton) form collective assemblages out of their own bodies to perform a variety of functions that benefit the entire colony. Here we examine ‟bridges" of linked individuals that are constructed to span gaps in the colony's foraging trail. How these living structures adjust themselves to varied and changing conditions remains poorly understood. Our field experiments show that the ants continuously modify their bridges, such that these structures lengthen, widen, and change position in response to traffic levels and environmental geometry. Ants initiate bridges where their path deviates from their incoming direction and move the bridges over time to create shortcuts over large gaps. The final position of the structure depended on the intensity of the traffic and the extent of path deviation and was influenced by a cost-benefit trade-off at the colony level, where the benefit of increased foraging trail efficiency was balanced by the cost of removing workers from the foraging pool to form the structure. To examine this trade-off, we quantified the geometric relationship between costs and benefits revealed by our experiments. We then constructed a model to determine the bridge location that maximized foraging rate, which qualitatively matched the observed movement of bridges. Our results highlight how animal self-assemblages can be dynamically modified in response to a group-level cost-benefit trade-off, without any individual unit's having information on global benefits or costs.

49 CFR 236.1021 - Discontinuances, material modifications, and amendments.

Code of Federal Regulations, 2011 CFR

2011-10-01

... such as landslide, burned bridge, high water, high and wide load, or tunnel protection when the unusual... to provide protection against unusual contingencies such as landslide, burned bridges, high water...

49 CFR 236.1021 - Discontinuances, material modifications, and amendments.

Code of Federal Regulations, 2010 CFR

2010-10-01

... such as landslide, burned bridge, high water, high and wide load, or tunnel protection when the unusual... to provide protection against unusual contingencies such as landslide, burned bridges, high water...

49 CFR 235.7 - Changes not requiring filing of application.

Code of Federal Regulations, 2013 CFR

2013-10-01

... unusual contingencies such as landslide, burned bridge, high water, high and wide load, or tunnel... used to provide protection against unusual contingencies such as landslide, burned bridges, high water...

49 CFR 235.7 - Changes not requiring filing of application.

Code of Federal Regulations, 2014 CFR

2014-10-01

... unusual contingencies such as landslide, burned bridge, high water, high and wide load, or tunnel... used to provide protection against unusual contingencies such as landslide, burned bridges, high water...

49 CFR 236.1021 - Discontinuances, material modifications, and amendments.

Code of Federal Regulations, 2013 CFR

2013-10-01

... such as landslide, burned bridge, high water, high and wide load, or tunnel protection when the unusual... to provide protection against unusual contingencies such as landslide, burned bridges, high water...

49 CFR 236.1021 - Discontinuances, material modifications, and amendments.

Code of Federal Regulations, 2014 CFR

2014-10-01

... such as landslide, burned bridge, high water, high and wide load, or tunnel protection when the unusual... to provide protection against unusual contingencies such as landslide, burned bridges, high water...

49 CFR 235.7 - Changes not requiring filing of application.

Code of Federal Regulations, 2012 CFR

2012-10-01

... unusual contingencies such as landslide, burned bridge, high water, high and wide load, or tunnel... used to provide protection against unusual contingencies such as landslide, burned bridges, high water...

49 CFR 236.1021 - Discontinuances, material modifications, and amendments.

Code of Federal Regulations, 2012 CFR

2012-10-01

... such as landslide, burned bridge, high water, high and wide load, or tunnel protection when the unusual... to provide protection against unusual contingencies such as landslide, burned bridges, high water...

Condition assessment of timber bridges. 2, Evaluation of several stress-wave tools

Treesearch

Brian K. Brashaw; Robert J. Vatalaro; James P. Wacker; Robert J. Ross

2005-01-01

This study was conducted to evaluate the accuracy and reliability of several stress-wave devices widely used for locating deteriorated areas in timber bridge members. Bridge components containing different levels of natural decay were tested using various devices. The specimens were then sawn (along their length) into slabs to expose their interior condition. The...

Open to Critique: Predictive Effects of Academic Outcomes from a Bridging/Foundation Programme on First-Year Degree-Level Study

ERIC Educational Resources Information Center

Curtis, Elana; Wikaire, Erena; Jiang, Yannan; McMillan, Louise; Loto, Robert; Fonua, Sonia; Herbert, Rowan; Hori, Melissa; Ko, Teri; Newport, Rochelle; Salter, David; Wiles, Janine; Airini; Reid, Papaarangi

2017-01-01

Bridging/foundation programmes are often provided by tertiary institutions to increase equity in access and academic performance of students from under-served communities. Little empirical evidence exists to measure the effectiveness of these bridging/foundation programmes on undergraduate academic outcomes. This research identifies the predictive…

15. 'Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, ...

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

15. 'Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, California, A.J. Logan, County Surveyor, H.J. Brunnier, Consulting Engineer, March 7, 1919,' showing general plan, plan of top chord, elevation of main girder, transverse section, plan section at deck level. - Salt River Bridge, Spanning Salt River at Dillon Road, Ferndale, Humboldt County, CA

Study on Construction Technology of Municipal Road and Bridge Concrete

NASA Astrophysics Data System (ADS)

Tang, Fuyong

2018-03-01

With the continuous development of social economy and the accelerating process of urbanization, municipal road and bridge projects have also shown a trend of rapid development. Municipal road and bridge work can fully reflect the economic and cultural development level of cities and is also an important symbol of urban development. As a basic material of construction, concrete is widely used in engineering construction. This article will analyze the municipal road and bridge concrete construction technology, put forward corresponding measures.

18. Photocopy of photograph of WalpoleWestminster bridge at high water ...

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

18. Photocopy of photograph of Walpole-Westminster bridge at high water during flood of November, 1927; photograph from Walpole Historical Society scrapbook collection. View west: Walpole approach (railroad station and store) and Connecticut River at flood stage, November, 1927. - Walpole-Westminster Bridge, Spanning Connecticut River between Walpole, NH & Westminster, VT, Walpole, Cheshire County, NH

Invited Article: Bridging the Gap--Supporting the Transition from High School to College

ERIC Educational Resources Information Center

Frischmann, Julie A.; Moor, Kelly S.

2017-01-01

Idaho State University's Bengal Bridge is a summer program designed to help students successfully transition from high school to their first year of college at Idaho State University. All Bridge students at ISU take two general education courses, plus an additional credit of supplemental instruction focused on academic strategies specific to the…

Development, verification, and application of a simplified method to estimate total-streambed scour at bridge sites in Illinois

USGS Publications Warehouse

Holmes, Robert R.; Dunn, Chad J.

1996-01-01

A simplified method to estimate total-streambed scour was developed for application to bridges in the State of Illinois. Scour envelope curves, developed as empirical relations between calculated total scour and bridge-site chracteristics for 213 State highway bridges in Illinois, are used in the method to estimate the 500-year flood scour. These 213 bridges, geographically distributed throughout Illinois, had been previously evaluated for streambed scour with the application of conventional hydraulic and scour-analysis methods recommended by the Federal Highway Administration. The bridge characteristics necessary for application of the simplified bridge scour-analysis method can be obtained from an office review of bridge plans, examination of topographic maps, and reconnaissance-level site inspection. The estimates computed with the simplified method generally resulted in a larger value of 500-year flood total-streambed scour than with the more detailed conventional method. The simplified method was successfully verified with a separate data set of 106 State highway bridges, which are geographically distributed throughout Illinois, and 15 county highway bridges.

Effects of Irregular Bridge Columns and Feasibility of Seismic Regularity

NASA Astrophysics Data System (ADS)

Thomas, Abey E.

2018-05-01

Bridges with unequal column height is one of the main irregularities in bridge design particularly while negotiating steep valleys, making the bridges vulnerable to seismic action. The desirable behaviour of bridge columns towards seismic loading is that, they should perform in a regular fashion, i.e. the capacity of each column should be utilized evenly. But, this type of behaviour is often missing when the column heights are unequal along the length of the bridge, allowing short columns to bear the maximum lateral load. In the present study, the effects of unequal column height on the global seismic performance of bridges are studied using pushover analysis. Codes such as CalTrans (Engineering service center, earthquake engineering branch, 2013) and EC-8 (EN 1998-2: design of structures for earthquake resistance. Part 2: bridges, European Committee for Standardization, Brussels, 2005) suggests seismic regularity criterion for achieving regular seismic performance level at all the bridge columns. The feasibility of adopting these seismic regularity criterions along with those mentioned in literatures will be assessed for bridges designed as per the Indian Standards in the present study.

Internal curing of high-performance concrete for bridge decks.

DOT National Transportation Integrated Search

2013-03-01

High performance concrete (HPC) provides a long lasting, durable concrete that is typically used in bridge decks due to its low permeability, high abrasion resistance, freeze-thaw resistance and strength. However, this type of concrete is highly susc...

Exploring Strong Interactions in Proteins with Quantum Chemistry and Examples of Their Applications in Drug Design.

PubMed

Xie, Neng-Zhong; Du, Qi-Shi; Li, Jian-Xiu; Huang, Ri-Bo

2015-01-01

Three strong interactions between amino acid side chains (salt bridge, cation-π, and amide bridge) are studied that are stronger than (or comparable to) the common hydrogen bond interactions, and play important roles in protein-protein interactions. Quantum chemical methods MP2 and CCSD(T) are used in calculations of interaction energies and structural optimizations. The energies of three types of amino acid side chain interactions in gaseous phase and in aqueous solutions are calculated using high level quantum chemical methods and basis sets. Typical examples of amino acid salt bridge, cation-π, and amide bridge interactions are analyzed, including the inhibitor design targeting neuraminidase (NA) enzyme of influenza A virus, and the ligand binding interactions in the HCV p7 ion channel. The inhibition mechanism of the M2 proton channel in the influenza A virus is analyzed based on strong amino acid interactions. (1) The salt bridge interactions between acidic amino acids (Glu- and Asp-) and alkaline amino acids (Arg+, Lys+ and His+) are the strongest residue-residue interactions. However, this type of interaction may be weakened by solvation effects and broken by lower pH conditions. (2) The cation- interactions between protonated amino acids (Arg+, Lys+ and His+) and aromatic amino acids (Phe, Tyr, Trp and His) are 2.5 to 5-fold stronger than common hydrogen bond interactions and are less affected by the solvation environment. (3) The amide bridge interactions between the two amide-containing amino acids (Asn and Gln) are three times stronger than hydrogen bond interactions, which are less influenced by the pH of the solution. (4) Ten of the twenty natural amino acids are involved in salt bridge, or cation-, or amide bridge interactions that often play important roles in protein-protein, protein-peptide, protein-ligand, and protein-DNA interactions.

Experimental assessment of an RFID-based crack sensor for steel structures

NASA Astrophysics Data System (ADS)

E Martínez-Castro, R.; Jang, S.; Nicholas, J.; Bansal, R.

2017-08-01

The use of welded steel cover plates had been a common design practice to increase beam section capacity in regions of high moment for decades. Many steel girder bridges with cover plates are still in service. Steel girder bridges are subject to cyclic loading, which can initiate crack formation at the toe of the weld and reduce beam capacity. Thus, timely detection of fatigue cracks is of utmost importance in steel girder bridge monitoring. To date, crack monitoring methods using in-house radio frequency identification (RFID)-based sensors have been developed to complement visual inspection and provide quantitative information of damage level. Offering similar properties at a reduced cost, commercial ultra-high frequency (UHF) passive RFID tags have been identified as a more financially viable option for pervasive crack monitoring using a dense array of sensors. This paper presents a study on damage sensitivity of low-cost commercial UHF RFID tags for crack detection and monitoring on metallic structures. Using backscatter power as a parameter for damage identification, a crack sensing system has been developed for single and multiple tag configurations for increased sensing pervasiveness. The effect on backscatter power of the existence and stage of crack propagation has been successfully characterized. For further automation of crack detection, a damage index based on the variation of backscatter power has also been established. The tested commercial RFID-based crack sensor contributes to the usage of this technology on steel girder bridges.

Effect of π-bridge units on properties of A-π-D-π-A-type nonfullerene acceptors for organic solar cells.

PubMed

Wang, Yan-Ling; Li, Quan-Song; Li, Ze-Sheng

2018-05-15

Acceptor-π-donor-π-acceptor (A-π-D-π-A)-types of small molecules are very promising nonfullerene acceptors to overcome the drawbacks of fullerene derivatives such as the weak absorption ability and electronic adjustability. However, only few attempts have been made to develop π-bridge units to construct highly efficient acceptors in OSCs. Herein, taking the reported acceptor P1 as a reference, five small-structured acceptors (P2, P3, P4, P5, and P6) have been designed via the replacement of the π-bridge unit. A combination of quantum chemistry and Marcus theory approaches is employed to investigate the effect of different π-bridge units on the optical, electronic, and charge transport properties of P1-P6. The calculation results show that the designed molecules P2 and P5 can become potential acceptor replacements of P1 due to their red-shifted absorption bands, appropriate energy levels, low exciton binding energy, and high electron affinity and electron mobility. Additionally, compared with P3HT/P1, P3HT/P2 and P3HT/P5 exhibit stronger and wider absorption peaks, larger electron transfer distances (DCT), greater transferred charge amounts (Δq), and smaller overlaps (Λ), which shows that P2 and P5 have more significant electron transfer characteristics and favorable exciton dissociation capabilities for enhancing the short-circuit current density (JSC) and thus, they are potential acceptors in OSCs.

Assessment of bridge abutment scour and sediment transport under various flow conditions

NASA Astrophysics Data System (ADS)

Gilja, Gordon; Valyrakis, Manousos; Michalis, Panagiotis; Bekić, Damir; Kuspilić, Neven; McKeogh, Eamon

2017-04-01

Safety of bridges over watercourses can be compromised by flow characteristics and bridge hydraulics. Scour process around bridge foundations can develop rapidly during low-recurrence interval floods when structural elements are exposed to increased flows. Variations in riverbed geometry, as a result of sediment removal and deposition processes, can increase flood-induced hazard at bridge sites with catastrophic failures and destructive consequences for civil infrastructure. The quantification of flood induced hazard on bridge safety generally involves coupled hydrodynamic and sediment transport models (i.e. 2D numerical or physical models) for a range of hydrological events covering both high and low flows. Modelled boundary conditions are usually estimated for their probability of occurrence using frequency analysis of long-term recordings at gauging stations. At smaller rivers gauging station records are scarce, especially in upper courses of rivers where weirs, drops and rapids are common elements of river bathymetry. As a result, boundary conditions that accurately represent flow patterns on modelled river reach cannot be often reliably acquired. Sediment transport process is also more complicated to describe due to its complexity and dependence to local flow field making scour hazard assessment a particularly challenging issue. This study investigates the influence of flow characteristics to the development of scour and sedimentation processes around bridge abutments of a single span masonry arch bridge in south Ireland. The impact of downstream weirs on bridge hydraulics through variation of downstream model domain type is also considered in this study. The numerical model is established based on detailed bathymetry data surveyed along a rectangular grid of 50cm spacing. Acquired data also consist of riverbed morphology and water level variations which are monitored continuously on bridge site. The obtained data are then used to compare and calibrate numerical models for several flood scenarios. The determination of the boundary conditions is followed by physical modelling to investigate the development of scour around bridge elements. The comparison of surveyed data with the obtained numerical and physical modelling results provide an insight of various flow patterns and their influence on riverbed morphology. This can deliver important information needed for assessment of structural risk associated with flood events. Acknowledgement: The authors wish to acknowledge the financial support of the European Commission, through the Marie Curie action Industry-Academia Partnership and Pathways Network BRIDGE SMS (Intelligent Bridge Assessment Maintenance and Management System) - FP7-People-2013-IAPP- 612517.

Numerical simulation of wind-sand movement in the reversed flow region of a sand dune with a bridge built downstream.

PubMed

He, Wei; Huang, Ning; Xu, Bin; Wang, Wenbo

2018-04-23

A bridge built inside the reversed flow region of a sand dune will change the characteristics of wind-sand movement in this region. The Reynolds-averaged Navier-Stokes simulation and discrete particle tracing are used to simulate the wind-sand movement around a sand dune with a bridge built inside the reversed region. Three cases with different bridge positions are studied. The results show that 1) compared with the isolated dune case, a tall bridge built at the leeward toe leads to an increase in the deposition rate on the leeward slope and a longer reversed flow region downstream of the sand dune; meanwhile, the high speed of crosswind on the bridge indicates that some measures should be taken to protect trains from strong crosswind; 2) a low bridge at the leeward toe has little effect on the sand deposition and reversed flow region of the dune; however, low sand transport rate and crosswind speed on the bridge show that anti-crosswind/sand measures should be taken according to the actual situation and 3) a low bridge on the leeward slope has little effect on the length of reversed flow region, however, high crosswind speed and sand flux on the bridge reveal the need of anti-crosswind/sand measures on the bridge. Moreover, the bridges in the reversed flow region increase the sand flux near the leeward crest; as a result, the moving patterns of the sand dune are changed.

Relevance feedback-based building recognition

NASA Astrophysics Data System (ADS)

Li, Jing; Allinson, Nigel M.

2010-07-01

Building recognition is a nontrivial task in computer vision research which can be utilized in robot localization, mobile navigation, etc. However, existing building recognition systems usually encounter the following two problems: 1) extracted low level features cannot reveal the true semantic concepts; and 2) they usually involve high dimensional data which require heavy computational costs and memory. Relevance feedback (RF), widely applied in multimedia information retrieval, is able to bridge the gap between the low level visual features and high level concepts; while dimensionality reduction methods can mitigate the high-dimensional problem. In this paper, we propose a building recognition scheme which integrates the RF and subspace learning algorithms. Experimental results undertaken on our own building database show that the newly proposed scheme appreciably enhances the recognition accuracy.

78 FR 55337 - Buy America Waiver Notification

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-10

... components for construction of Monon Trail Bridge over SR 25 in Indiana. DATES: The effective date of the... bridge components for construction of Monon Trail Bridge over SR 25 in Indiana. The Indiana Department of Transportation (INDOT) requested this waiver for an overpass to carry the Monon High Bridge Trail across the new...

The bridging conformations of double-end anchored polymer-surfactants destabilize a hydrogel of lipid membranes

NASA Astrophysics Data System (ADS)

Slack, N. L.; Davidson, P.; Chibbaro, M. A.; Jeppesen, C.; Eiselt, P.; Warriner, H. E.; Schmidt, H.-W.; Pincus, P.; Safinya, C. R.

2001-10-01

Double-end-anchored poly-ethylene-glycol-surfactants (DEA-PEG-surfactants) induce the gelation of lyotropic lamellar Lα phases stabilized by undulation forces. The physical hydrogel (Lα,g) derives its viscoelasticity from the proliferation of defects at a mesoscopic level. The DEA-PEG-surfactants assume both looping and bridging conformations. The existence of novel bridging conformations is indicated by the coexistence of two lamellar phases and the limited swelling of the Lα and Lα,g phases. Modeling of the polymer decorated membranes demonstrates the existence of bridging and yields a rapidly decreasing density of bridging conformations with increasing interlayer spacing.

Internally cured concrete for pavement and bridge deck applications : [summary].

DOT National Transportation Integrated Search

2015-08-01

High-strength-high-performance concrete (HSHPC) is used for rapid repair of concrete : bridge decks and pavement. However, HSHPC has very high early shrinkage, often leading to : cracking, made worse by high ambient temperatures and a large surface a...

Seminar on Use of High Strength Deformed Bars

NASA Astrophysics Data System (ADS)

1981-04-01

Steel requirements, cost and energy for two lane curved and straight bridges for 20 m span are studied. Saving in steel cost and energy by using high strength bars is also discussed. Only 20 m span, straight simply supported and 5 deg, 10 deg and 15 deg curved simply supported bridges are considered. The width of bridge is taken as 7.8 m. Bridges are designed with steel stresses 1900 kgs/cm sq, 2100 kgs/sq cm and 2500 kgs/sq cm and saving in steel, cost and energy is given.

Performance of two solid fumigants in covered bridges

Treesearch

Matthew J. Konkler; Mark A. Newbill; Stan Lebow; Jeffrey J. Morrell

2017-01-01

The potential for two solid wood fumigants, dazomet and methylisothiocyanate (MITC), to move through wood at levels sufficient to arrest decay in covered bridges was assessed. Dazomet alone failed to decompose to MITC and move into the wood at effective levels, probably because too little moisture was available for breakdown. Adding a copper accelerant improved dazomet...

Minimally Invasive Osteosynthesis with a Bridge Plate Versus a Functional Brace for Humeral Shaft Fractures: A Randomized Controlled Trial.

PubMed

Matsunaga, Fabio Teruo; Tamaoki, Marcel Jun Sugawara; Matsumoto, Marcelo Hide; Netto, Nicola Archetti; Faloppa, Flavio; Belloti, Joao Carlos

2017-04-05

Nonoperative treatment has historically been considered the standard for fractures of the shaft of the humerus. Minimally invasive bridge-plate osteosynthesis for isolated humeral shaft fractures has been proven to be a safe technique, with good and reproducible results. This study was designed to compare clinical and radiographic outcomes between patients who had been treated with bridge plate osteosynthesis and those who had been managed nonoperatively with a functional brace. A prospective randomized trial was designed and included 110 patients allocated to 1 of 2 groups: surgery with a bridge plate or nonoperative treatment with a functional brace. The primary outcome was the Disabilities of the Arm, Shoulder and Hand (DASH) score at 6 months. The score on the Short Form-36 (SF-36) life-quality questionnaire, complications of treatment, Constant-Murley score for the shoulder, pain level, and radiographic results were assessed as secondary outcomes. Participants were assessed at 2 weeks; 1, 2, and 6 months; and 1 year after the interventions. The mean DASH score of the bridge plate group was statistically superior to that of the functional brace group (mean scores, 10.9 and 16.9, respectively; p = 0.046) only at 6 months. The bridge plate group also had a significantly more favorable nonunion rate (0% versus 15%) and less mean residual angular displacement seen on the anteroposterior radiograph (2.0° versus 10.5°) (both p < 0.05). No difference between the groups was detected with regard to the SF-36 score, pain level, Constant-Murley score, or angular displacement seen on the lateral radiograph. This trial demonstrates that, compared with functional bracing, surgical treatment with a bridge plate has a statistically significant advantage, of uncertain clinical benefit, with respect to self-reported outcome (DASH score) at 6 months, nonunion rate, and residual deformity in the coronal plane as seen on radiographs. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Regulation of the Dynamic Live Load Factor for Calculation of Bridge Structures on High-Speed Railway Mainlines

NASA Astrophysics Data System (ADS)

Dyachenko, Leonid K.; Benin, Andrey V.

2017-06-01

When the high-speed railway traffic is being organized, it becomes necessary to elaborate bridge design standards for high-speed railways (HSR). Methodology of studying the issues of HSR bridge design is based on the comprehensive analysis of domestic research as well as international experience in design, construction and operation of high-speed railways. Serious requirements are imposed on the HSR artificial structures, which raise a number of scientific tasks associated mainly with the issues of the dynamic interaction of the rolling stock and the bridge elements. To ensure safety of traffic and reliability of bridges during the whole period of operation one needs to resolve the dynamic problems of various types of high-speed trains moving along the structures. The article analyses dependences of the magnitude of inertial response on the external stress parameters and proposes a simplified method of determination of the dynamic live load factor caused by the passage of high-speed trains. The usefulness of the given research arises from the reduction of complexity of the complicated dynamic calculations needed to describe a high-speed train travelling along the artificial structures.

CF60 Concrete Composition Design and Application on Fudiankou Xijiang Super Large Bridge

NASA Astrophysics Data System (ADS)

Qiu, Yi Mei; Wen, Sen Yuan; Chen, Jun Xiang

2018-06-01

Guangxi Wuzhou City Ring Road Fudiankou Xijiang super large bridge CF60 concrete is a new multi-phase composite high-performance concrete, this paper for the Fudiankou Xijiang bridge structure and characteristics of the project, in accordance with the principle of local materials and technical specification requirements, combined with the site conditions of CF60 engineering high performance concrete component materials, proportion and the technical performance, quantify the main physical and mechanical performance index. Analysis main influencing factors of the technical indicators, reasonable adjustment of concrete mix design parameters, and the use of technical means of admixture and multi-function composite admixture of concrete, obtain the optimal proportion of good work, process, mechanical properties stability and durability of engineering properties, recommend and verification of concrete mix; to explore the CF60 high performance concrete Soil in the Fudiankou Xijiang bridge application technology, detection and tracking the quality of concrete construction, concrete structure during the construction of the key technology and control points is proposed, evaluation of CF60 high performance concrete in the actual engineering application effect and benefit to ensure engineering quality of bridge structure and service life, and super long span bridge engineering construction to provide basis and reference.

Experimental analysis of a high-speed railway bridge under Thalys trains

NASA Astrophysics Data System (ADS)

Xia, H.; De Roeck, G.; Zhang, N.; Maeck, J.

2003-11-01

In this paper dynamic experiments on the Antoing Bridge located on the high-speed railway line between Paris and Brussels are reported. The experiments were co-operatively carried out by the Northern Jiaotong University from China, the Catholic University of Leuven, the Free University of Brussels and the Belgium Railway Company NMBS-SNCB from Belgium. The bridge is composed of multi-span simply supported PC girders with spans of 50 m and U-shaped sections. The loads are the high-speed Thalys trains with articulated vehicles. The speeds of the Thalys trains were between 265 and 310 km/h. In the experiments, the dynamic responses of the bridge such as the deflections, the accelerations and the strains that were measured by a laser velocity displacement transducer accelerometers and strain gauges, respectively. Many useful results have been obtained from the analysis of the recorded data. The tests and the measured results can be a reference for the study and the design of high-speed railway bridges.

Wireless Smart Sensor Network System Using SmartBridge Sensor Nodes for Structural Health Monitoring of Existing Concrete Bridges

NASA Astrophysics Data System (ADS)

Gaviña, J. R.; Uy, F. A.; Carreon, J. D.

2017-06-01

There are over 8000 bridges in the Philippines today according to the Department of Public Works and Highways (DPWH). Currently, visual inspection is the most common practice in monitoring the structural integrity of bridges. However, visual inspections have proven to be insufficient in determining the actual health or condition of a bridge. Structural Health Monitoring (SHM) aims to give, in real-time, a diagnosis of the actual condition of the bridge. In this study, SmartBridge Sensor Nodes were installed on an existing concrete bridge with American Association of State Highway and Transportation Officials (AASHTO) Type IV Girders to gather vibration of the elements of the bridge. Also, standards on the effective installation of SmartBridge Sensor Nodes, such as location and orientation was determined. Acceleration readings from the sensor were then uploaded to a server, wherein they are monitored against certain thresholds, from which, the health of the bridge will be derived. Final output will be a portal or webpage wherein the information, health, and acceleration readings of the bridge will be available for viewing. With levels of access set for different types of users, the main users will have access to download data and reports. Data transmission and webpage access are available online, making the SHM system wireless.

Multi-Hazard Assessment of Scour Damaged Bridges with UAS-Based Measurements

NASA Astrophysics Data System (ADS)

Özcan, O.; Ozcan, O.

2017-12-01

Flood and stream induced scour occurring in bridge piers constructed on rivers is one of the mostly observed failure reasons in bridges. Scour induced failure risk in bridges and determination of the alterations in bridge safety under seismic effects has the ultimate importance. Thus, for the determination of bridge safety under the scour effects, the scour amount under bridge piers should be designated realistically and should be tracked and updated continuously. Hereby, the scour induced failures in bridge foundation systems will be prevented and bridge substructure design will be conducted safely. In this study, in order to measure the amount of scour in bridge load bearing system (pile foundations and pile abutments) and to attain very high definition 3 dimensional models of river flood plain for the flood analysis, unmanned aircraft system (UAS) based measurement methods were implemented. UAS based measurement systems provide new and practical approach and bring high precision and reliable solutions considering recent measurement systems. For this purpose, the reinforced concrete (RC) bridge that is located on Antalya Boğaçayı River, Turkey and that failed in 2003 due to flood-induced scour was selected as the case study. The amount of scour occurred in bridge piers and piles was determined realistically and the behavior of bridge piers under scour effects was investigated. Future flood effects and the resultant amount of scour was determined with HEC-RAS software by using digital surface models that were obtained at regular intervals using UAS for the riverbed. In the light of the attained scour measurements and expected scour after a probable flood event, the behavior of scour damaged RC bridge was investigated by pushover and time history analyses under lateral and vertical seismic loadings. In the analyses, the load and displacement capacity of bridge was observed to diminish significantly under expected scour. Thus, the deterioration in multi hazard performance of the bridge was monitored significantly in the light of updated bridge load bearing system capacity. Regarding the case study, UAS based and continuously updated bridge multi hazard risk detection system was established that can be used for bridges located on riverbed.

SCB initiator

DOEpatents

Bickes Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

1994-11-01

A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

SCB initiator

DOEpatents

Bickes, Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

1994-01-01

A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

Multi-Level Evaluation of Cooperative Research Centers: Bridging between the Triple Helix and the Science of Team Science

ERIC Educational Resources Information Center

Gray, Denis O.; Sundstrom, Eric

2010-01-01

Two emergent conceptual models for fostering the development of innovative technology through applied science at Cooperative Research Centers (CRCs)--the Triple Helix and the science of team science--have proved highly productive in stimulating research into how the innovation process works. Although the two arenas for fostering innovation have…

10. copy of a construction progress photograph taken by the ...

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

10. copy of a construction progress photograph taken by the Hunkin-Conkey Construction Company, dated October 25, 1916. Photo shows the reinforced concrete subway deck as it appeared shortly after construction. A portion of arch number 12, can be see. Photo courtesy of Cleveland Public Library. - Detroit Superior High Level Bridge, Cleveland, Cuyahoga County, OH

Bridging the Gap: On Ways to Improve Collaboration between Secondary Teachers and University Professors

ERIC Educational Resources Information Center

Juarez-Dappe, Patricia

2011-01-01

The importance of content-focused professional development for high school teachers has been widely recognized by educators and legislators. Professionals in education at all levels have long argued for more contacts between secondary and post-secondary instructors as one important way to improve subject matter mastery. In response to this call,…

Upward Mobility Through Job Restructuring. Personnel Management Series No. 26.

ERIC Educational Resources Information Center

Civil Service Commission, Washington, DC.

The May, 1974, bulletin issued by the Civil Service Commission deals with job restructuring, the process of realigning job duties to develop technician-type or "bridge" jobs in Federal agencies, as a means to provide upward mobility for employees. Besides being highly beneficial to employees in dead end jobs at low grade levels, job restructuring…

Bridging the Gap: The Struggle of One Hispanic Father

ERIC Educational Resources Information Center

Vasquez, Sarah

2016-01-01

Parent involvement has been shown to be one of the keys to student educational success, their ability to perform at a high level and persevere. The latest government statistics reveal that 53 million Hispanics now reside in the United States and 75 % of this population speaks Spanish at home [Cooper, M. (2014). "Hispanics in America and in…

The Rational Number Sub-Constructs as a Foundation for Problem Solving

ERIC Educational Resources Information Center

Doyle, Kathleen M.; Dias, Olen; Kennis, James R.; Czarnocha, Bronislaw; Baker, William

2016-01-01

One of the many roles of two year community colleges in the United States is to bridge the gap between secondary school and college for students who graduate from high school with weak mathematics skills that prevent them from enrolling in college level mathematics courses. At community colleges remedial or developmental mathematics courses review…

Hybrid networking sensing system for structural health monitoring of a concrete cable-stayed bridge

NASA Astrophysics Data System (ADS)

Torbol, Marco; Kim, Sehwan; Chien, Ting-Chou; Shinozuka, Masanobu

2013-04-01

The purpose of this study is the remote structural health monitoring to identify the torsional natural frequencies and mode shapes of a concrete cable-stayed bridge using a hybrid networking sensing system. The system consists of one data aggregation unit, which is daisy-chained to one or more sensing nodes. A wireless interface is used between the data aggregation units, whereas a wired interface is used between a data aggregation unit and the sensing nodes. Each sensing node is equipped with high-precision MEMS accelerometers with adjustable sampling frequency from 0.2 Hz to 1.2 kHz. The entire system was installed inside the reinforced concrete box-girder deck of Hwamyung Bridge, which is a cable stayed bridge in Busan, South Korea, to protect the system from the harsh environmental conditions. This deployment makes wireless communication a challenge due to the signal losses and the high levels of attenuation. To address these issues, the concept of hybrid networking system is introduced with the efficient local power distribution technique. The theoretical communication range of Wi-Fi is 100m. However, inside the concrete girder, the peer to peer wireless communication cannot exceed about 20m. The distance is further reduced by the line of sight between the antennas. However, the wired daisy-chained connection between sensing nodes is useful because the data aggregation unit can be placed in the optimal location for transmission. To overcome the limitation of the wireless communication range, we adopt a high-gain antenna that extends the wireless communication distance to 50m. Additional help is given by the multi-hopping data communication protocol. The 4G modem, which allows remote access to the system, is the only component exposed to the external environment.

Carbon-bridged oligo(p-phenylenevinylene)s for photostable and broadly tunable, solution-processable thin film organic lasers

PubMed Central

Morales-Vidal, Marta; Boj, Pedro G.; Villalvilla, José M.; Quintana, José A.; Yan, Qifan; Lin, Nai-Ti; Zhu, Xiaozhang; Ruangsupapichat, Nopporn; Casado, Juan; Tsuji, Hayato; Nakamura, Eiichi; Díaz-García, María A.

2015-01-01

Thin film organic lasers represent a new generation of inexpensive, mechanically flexible devices for spectroscopy, optical communications and sensing. For this purpose, it is desired to develop highly efficient, stable, wavelength-tunable and solution-processable organic laser materials. Here we report that carbon-bridged oligo(p-phenylenevinylene)s serve as optimal materials combining all these properties simultaneously at the level required for applications by demonstrating amplified spontaneous emission and distributed feedback laser devices. A series of six compounds, with the repeating unit from 1 to 6, doped into polystyrene films undergo amplified spontaneous emission from 385 to 585 nm with remarkably low threshold and high net gain coefficients, as well as high photostability. The fabricated lasers show narrow linewidth (<0.13 nm) single mode emission at very low thresholds (0.7 kW cm−2), long operational lifetimes (>105 pump pulses for oligomers with three to six repeating units) and wavelength tunability across the visible spectrum (408–591 nm). PMID:26416643

High-sensitivity strain visualization using electroluminescence technologies

NASA Astrophysics Data System (ADS)

Xu, Jian; Jo, Hongki

2016-04-01

Visualizing mechanical strain/stress changes is an emerging area in structural health monitoring. Several ways are available for strain change visualization through the color/brightness change of the materials subjected to the mechanical stresses, for example, using mechanoluminescence (ML) materials and mechanoresponsive polymers (MRP). However, these approaches were not effectively applicable for civil engineering system yet, due to insufficient sensitivity to low-level strain of typical civil structures and limitation in measuring both static and dynamic strain. In this study, design and validation for high-sensitivity strain visualization using electroluminescence technologies are presented. A high-sensitivity Wheatstone bridge, of which bridge balance is precisely controllable circuits, is used with a gain-adjustable amplifier. The monochrome electroluminescence (EL) technology is employed to convert both static and dynamic strain change into brightness/color change of the EL materials, through either brightness change mode (BCM) or color alternation mode (CAM). A prototype has been made and calibrated in lab, the linearity between strain and brightness change has been investigated.

Development of a nondestructive evaluation method for FRP bridge decks

NASA Astrophysics Data System (ADS)

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.

Performance Evaluation of an Intel Haswell- and Ivy Bridge-Based Supercomputer Using Scientific and Engineering Applications

NASA Technical Reports Server (NTRS)

Saini, Subhash; Hood, Robert T.; Chang, Johnny; Baron, John

2016-01-01

We present a performance evaluation conducted on a production supercomputer of the Intel Xeon Processor E5- 2680v3, a twelve-core implementation of the fourth-generation Haswell architecture, and compare it with Intel Xeon Processor E5-2680v2, an Ivy Bridge implementation of the third-generation Sandy Bridge architecture. Several new architectural features have been incorporated in Haswell including improvements in all levels of the memory hierarchy as well as improvements to vector instructions and power management. We critically evaluate these new features of Haswell and compare with Ivy Bridge using several low-level benchmarks including subset of HPCC, HPCG and four full-scale scientific and engineering applications. We also present a model to predict the performance of HPCG and Cart3D within 5%, and Overflow within 10% accuracy.

Bridge Crack Detection Using Multi-Rotary Uav and Object-Base Image Analysis

NASA Astrophysics Data System (ADS)

Rau, J. Y.; Hsiao, K. W.; Jhan, J. P.; Wang, S. H.; Fang, W. C.; Wang, J. L.

2017-08-01

Bridge is an important infrastructure for human life. Thus, the bridge safety monitoring and maintaining is an important issue to the government. Conventionally, bridge inspection were conducted by human in-situ visual examination. This procedure sometimes require under bridge inspection vehicle or climbing under the bridge personally. Thus, its cost and risk is high as well as labor intensive and time consuming. Particularly, its documentation procedure is subjective without 3D spatial information. In order cope with these challenges, this paper propose the use of a multi-rotary UAV that equipped with a SONY A7r2 high resolution digital camera, 50 mm fixed focus length lens, 135 degrees up-down rotating gimbal. The target bridge contains three spans with a total of 60 meters long, 20 meters width and 8 meters height above the water level. In the end, we took about 10,000 images, but some of them were acquired by hand held method taken on the ground using a pole with 2-8 meters long. Those images were processed by Agisoft PhotoscanPro to obtain exterior and interior orientation parameters. A local coordinate system was defined by using 12 ground control points measured by a total station. After triangulation and camera self-calibration, the RMS of control points is less than 3 cm. A 3D CAD model that describe the bridge surface geometry was manually measured by PhotoscanPro. They were composed of planar polygons and will be used for searching related UAV images. Additionally, a photorealistic 3D model can be produced for 3D visualization. In order to detect cracks on the bridge surface, we utilize object-based image analysis (OBIA) technique to segment the image into objects. Later, we derive several object features, such as density, area/bounding box ratio, length/width ratio, length, etc. Then, we can setup a classification rule set to distinguish cracks. Further, we apply semi-global-matching (SGM) to obtain 3D crack information and based on image scale we can calculate the width of a crack object. For spalling volume calculation, we also apply SGM to obtain dense surface geometry. Assuming the background is a planar surface, we can fit a planar function and convert the surface geometry into a DSM. Thus, for spalling area its height will be lower than the plane and its value will be negative. We can thus apply several image processing technique to segment the spalling area and calculate the spalling volume as well. For bridge inspection and UAV image management within a laboratory, we develop a graphic user interface. The major functions include crack auto-detection using OBIA, crack editing, i.e. delete and add cracks, crack attributing, 3D crack visualization, spalling area/volume calculation, bridge defects documentation, etc.

Investigation into shrinkage of high-performance concrete used for Iowa bridge decks and overlays.

DOT National Transportation Integrated Search

2013-09-01

High-performance concrete (HPC) overlays have been used increasingly as an effective and economical method for bridge decks in Iowa and other states. However, due to its high cementitious material content, HPC often displays high shrinkage cracking p...

High power density dc-to-dc converters for aerospace applications

NASA Technical Reports Server (NTRS)

Divan, Deepakraj M.

1990-01-01

Three dc-to-dc converter topologies aimed at high-power high-frequency applications are introduced. Major system parasitics, namely, the leakage inductance of the transformer and the device output capacitance are efficiently utilized. Of the three circuits, the single-phase and three-phase versions of the dual active bridge topology demonstrate minimal stresses, better utilization of the transformer, bidirectional, and buck-boost modes of operation. All circuits operate at a constant switching frequency, thus simplifying design of the reactive elements. The power transfer characteristics and soft-switching regions on the Vout-Iout plane are identified. Two coaxial transformers with different cross-sections were built for a rating of 50 kVA. Based on the single-phase dual active bridge topology, a 50 kW, 50 kHz converter operating at an input voltage of 200 Vdc and an output voltage of 1600 Vdc was fabricated. Characteristics of current-fed output make the dual active bridge topologies amenable to paralleling and hence extension to megawatt power levels. Projections to a 1 MW system operating from a 500 Vdc input, at an output voltage of 10 kVdc and a switching frequency of 50 kHz, using MOS-controlled thyristors, coaxially wound transformers operating at three times the present current density with cooling, and multilayer ceramic capacitors, suggests an overall power density of 0.075 to 0.08 kg/kW and an overall efficiency of 96 percent.

Rapid-estimation method for assessing scour at highway bridges

USGS Publications Warehouse

Holnbeck, Stephen R.

1998-01-01

A method was developed by the U.S. Geological Survey for rapid estimation of scour at highway bridges using limited site data and analytical procedures to estimate pier, abutment, and contraction scour depths. The basis for the method was a procedure recommended by the Federal Highway Administration for conducting detailed scour investigations, commonly referred to as the Level 2 method. Using pier, abutment, and contraction scour results obtained from Level 2 investigations at 122 sites in 10 States, envelope curves and graphical relations were developed that enable determination of scour-depth estimates at most bridge sites in a matter of a few hours. Rather than using complex hydraulic variables, surrogate variables more easily obtained in the field were related to calculated scour-depth data from Level 2 studies. The method was tested by having several experienced individuals apply the method in the field, and results were compared among the individuals and with previous detailed analyses performed for the sites. Results indicated that the variability in predicted scour depth among individuals applying the method generally was within an acceptable range, and that conservatively greater scour depths generally were obtained by the rapid-estimation method compared to the Level 2 method. The rapid-estimation method is considered most applicable for conducting limited-detail scour assessments and as a screening tool to determine those bridge sites that may require more detailed analysis. The method is designed to be applied only by a qualified professional possessing knowledge and experience in the fields of bridge scour, hydraulics, and flood hydrology, and having specific expertise with the Level 2 method.

Dynamic response for structural health monitoring of the Penang (I) cable-stayed bridge

NASA Astrophysics Data System (ADS)

Mohammed, M. I.; Sulaeman, E.; Mustapha, F.

2017-03-01

The paper discusses the dynamic response of the Penang (I) cable stayed bridge structure under various moving load representing typical traffic load of the bridge. The bridge has a total span of 440 m excluding the transition bridge that assumed to be not connected structurally to the main bridge structure. The bridge that links the fast growing Pinang Island and the Malaysian Mainland Peninsula has been known to be fully utilized which leads to the construction of Penang (II) bridge and now the third one. Due to highly traffic use of the bridge that may lead to reduction of the bridge design life, the dynamic response of the bridge becomes important to predict critical part of the bridge structure elements including the main girder and the 144 stay cables. The present study reveals that, due to flexible nature of the cable stayed bridge, the moving load that interacts with the natural dynamic characteristics of the bridge, gives significant stress increment compare to proportional static load especially when the moving load is un-symmetric. For this reason, several classes of typical vehicle passing the bridge with various vehicle speeds are investigated to demonstrate their effect on the bridge displacement, internal forces and stresses. The results can be used for further fatigue assessment of the bridge.

Community Sexual Bridging Among Heterosexuals at High-Risk of HIV in New York City.

PubMed

Neaigus, Alan; Jenness, Samuel M; Reilly, Kathleen H; Youm, Yoosik; Hagan, Holly; Wendel, Travis; Gelpi-Acosta, Camila

2016-04-01

Community sexual bridging may influence the socio-geographic distribution of heterosexually transmitted HIV. In a cross-sectional study, heterosexual adults at high-risk of HIV were recruited in New York City (NYC) in 2010 for the Centers for Disease Control and Prevention-sponsored National HIV Behavioral Surveillance system. Eligible participants were interviewed about their HIV risk behaviors and sexual partnerships and tested for HIV. Social network analysis of the geographic location of participants' recent sexual partnerships was used to calculate three sexual bridging measures (non-redundant ties, flow-betweenness and walk-betweenness) for NYC communities (defined as United Hospital Fund neighborhoods), which were plotted against HIV prevalence in each community. The analysis sample comprised 494 participants and 1534 sexual partnerships. Participants were 60.1 % male, 79.6 % non-Hispanic black and 19.6 % Hispanic race/ethnicity; the median age was 40 years (IQR 24-50); 37.7 % had ever been homeless (past 12 months); 16.6 % had ever injected drugs; in the past 12 months 76.7 % used non-injection drugs and 90.1 % engaged in condomless vaginal or anal sex; 9.6 % tested HIV positive (of 481 with positive/negative results). Sexual partnerships were located in 33 (78.6 %) of 42 NYC communities, including 13 "high HIV-spread communities", 7 "hidden bridging communities", 0 "contained high HIV prevalence communities", and 13 "latent HIV bridging communities". Compared with latent HIV bridging communities, the population racial/ethnic composition was more likely (p < 0.0001) to be black or Hispanic in high HIV-spread communities and to be black in hidden bridging communities. High HIV-spread and hidden bridging communities may facilitate the maintenance and spread of heterosexually transmitted HIV in black and Hispanic populations in NYC.

Relation of channel stability to scour at highway bridges over waterways in Maryland

USGS Publications Warehouse

Doheny, Edward J.; ,

1993-01-01

Data from assessments of channel stability and observed-scour conditions at 876 highway bridges over Maryland waterways were entered into a database. Relations were found to exist among specific, deterministic variables and observed-scour and debris conditions. Relations were investigated between (1) high-flow angle of attack and pier- and abutment-footing exposure, (2)abutment location and abutment-footing exposure, (3) type of bed material and pier-footing exposure, (4) tree cover on channel banks and mass wasting of the channel banks, and (5) land use near the bridge and the presence of debris blockage at the bridge opening. The results of the investigation indicate the following: (1) The number of pier and abutment-footing exposures increased for increasing high-flow angles of attack, (2) the number of abutment-footing exposures increased for abutments that protrude into the channel, (3) pier-footing exposures were most common for bridges over streams with channel beds of gravel, (4) mass wasting of channel banks with tree cover of 50 percent or greater near the bridge was less than mass wasting of channel banks with tree cover of less than 50 percent near the bridge, and (5) bridges blockage than bridge in row crop and swamp basins.

VALVE TOWER FROM HIGH GROUND NEAR APPROACH BRIDGE. VIEW FACING ...

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

VALVE TOWER FROM HIGH GROUND NEAR APPROACH BRIDGE. VIEW FACING NORTHEAST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas

NASA Astrophysics Data System (ADS)

Gou, Jun; Niu, Qingchen; Liang, Kai; Wang, Jun; Jiang, Yadong

2018-03-01

Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360* n ( n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.

Frequency Modulation and Absorption Improvement of THz Micro-bolometer with Micro-bridge Structure by Spiral-Type Antennas.

PubMed

Gou, Jun; Niu, Qingchen; Liang, Kai; Wang, Jun; Jiang, Yadong

2018-03-05

Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO 2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360*n (n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.

Assessment and mitigation of liquefaction hazards to bridge approach embankments in Oregon : final report.

DOT National Transportation Integrated Search

2002-11-01

The seismic performance of bridge structures and appurtenant components (i.e., approach spans, abutments and foundations) has been well documented following recent earthquakes worldwide. This experience demonstrates that bridges are highly vulnerable...

Precision monitoring of bridge deck curvature change during replacement.

DOT National Transportation Integrated Search

2016-05-01

This project was focused on development and deployment of a system for monitoring vertical : displacement in bridge decks and bridge spans. The system uses high precision wireless inclinometer : sensors to monitor inclinations at various points of a ...

Implementing HPC on the Sunshine Bridge project

DOT National Transportation Integrated Search

2007-11-01

This report presents the research work from a pilot program regarding the feasibility of implementing high performance concrete on Arizona bridge decks, using the Sunshine Bridge in Holbrook, Arizona as a test case. An existing concrete slab was remo...

Abrasion-resistant concrete mix designs for precast bridge deck panels.

DOT National Transportation Integrated Search

2010-08-01

The report documents laboratory investigations undertaken to develop high performance concrete (HPC) for precast and pre-stressed bridge deck components that would reduce the life-cycle cost of bridges by improving the studded tire wear (abrasion) re...

Implementing HPC on the Sunshine Bridge Project

DOT National Transportation Integrated Search

2007-11-16

This report presents the research work from a pilot program regarding the feasibility of implementing high performance concrete on Arizona bridge decks, using the Sunshine Bridge in Holbrook, Arizona as a test case. An existing concrete slab was remo...

U.S. Geological Survey - Virginia Department of Transportation: Bridge scour pilot study

USGS Publications Warehouse

Austin, Samuel H.

2018-02-27

BackgroundCost effective and safe highway bridge designs are required to ensure the long-term sustainability of Virginia’s road systems. The streamflows that, over time, scour streambed sediments from bridge piers inherently affect bridge safety and design costs. To ensure safety, bridge design must anticipate streambed scour at bridge piers over the lifespan of a bridge. Until recently Federal Highway Administration (FHWA) guidance provided only for scour estimates of granular, noncohesive, highly erosive material yielding overestimates of scour potential in instances when streambed materials offer some resistance to scour. This study seeks to estimate stream power and streambed scour for these more resistive sites, with bridge piers potentially established in cohesive soil or erodible rock. This new knowledge may provide significant construction cost savings while ensuring design and construction of safe highway bridges.

Seismic Performance of Self-Consolidating Concrete Bridge Columns : Research Brief

DOT National Transportation Integrated Search

2017-09-01

Rectangular bridge columns in high seismic areas require high amounts of confining steel. Self-consolidating concrete is ideal for the construction of concrete members with high steel congestion. However, there is lack of data on the seismic performa...

Endovascular Treatment of Wide-Necked Visceral Artery Aneurysms Using the Neurovascular Comaneci Neck-Bridging Device: A Technical Report.

PubMed

Maingard, Julian; Kok, Hong Kuan; Phelan, Emma; Logan, Caitriona; Ranatunga, Dinesh; Brooks, Duncan Mark; Chandra, Ronil V; Lee, Michael J; Asadi, Hamed

2017-11-01

Visceral and renal artery aneurysms (VRAAs) are an uncommon clinical entity but carry a risk of rupture with associated morbidity and mortality. The rupture risk is particularly high when the aneurysms are large, of unfavourable morphology or in the setting of pregnancy and perioperative period. Endovascular approaches are now first line in the treatment of VRAA, but conventional techniques may be ineffective in excluding aneurysms with unfavourable anatomy such as those with wide necks or at arterial bifurcation points. The neurovascular Comaneci neck-bridging device is used to temporarily cover the neck of intracranial aneurysms without occluding forward arterial flow during endovascular coiling. We report the novel use of the Comaneci neck-bridging device for the treatment of complex peripheral VRAAs. We describe the treatment of two patients with renal and splenic artery aneurysms demonstrating unfavourable anatomic morphology for conventional endovascular approaches. In the first patient, the renal artery aneurysm was situated at the intrarenal bifurcation of the main renal artery in the setting of a solitary kidney. In the second patient, the splenic artery aneurysm was situated close to the splenic hilum at the distal splenic arterial bifurcation. The Comaneci neck-bridging device was successfully used in both cases to assist coil embolisation with visceral preservation. The Comaneci neck-bridging device is potentially safe and effective for the treatment of peripheral VRAA with unfavourable anatomic characteristics that would have been deemed unsuitable for treatment using conventional techniques. Level 4, Technical Report.

78 FR 55215 - Drawbridge Operation Regulation; New Jersey Intracoastal Waterway (NJICW), Atlantic City, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-10

.../Absecon Boulevard Bridge across Beach Thorofare, NJICW mile 67.2, and the US40-322 (Albany Avenue) across... Bridge across Beach Thorofare, NJICW mile 67.2, and the US40-322 (Albany Avenue) across Inside Thorofare...-type bridge is 20 feet above mean high water. US40-322 (Albany Avenue) Bridge The current operating...

Application of Crack Identification Techniques for an Aging Concrete Bridge Inspection Using an Unmanned Aerial Vehicle.

PubMed

Kim, In-Ho; Jeon, Haemin; Baek, Seung-Chan; Hong, Won-Hwa; Jung, Hyung-Jo

2018-06-08

Bridge inspection using unmanned aerial vehicles (UAV) with high performance vision sensors has received considerable attention due to its safety and reliability. As bridges become obsolete, the number of bridges that need to be inspected increases, and they require much maintenance cost. Therefore, a bridge inspection method based on UAV with vision sensors is proposed as one of the promising strategies to maintain bridges. In this paper, a crack identification method by using a commercial UAV with a high resolution vision sensor is investigated in an aging concrete bridge. First, a point cloud-based background model is generated in the preliminary flight. Then, cracks on the structural surface are detected with the deep learning algorithm, and their thickness and length are calculated. In the deep learning method, region with convolutional neural networks (R-CNN)-based transfer learning is applied. As a result, a new network for the 384 collected crack images of 256 × 256 pixel resolution is generated from the pre-trained network. A field test is conducted to verify the proposed approach, and the experimental results proved that the UAV-based bridge inspection is effective at identifying and quantifying the cracks on the structures.

A Simplified Technique for Implant-Abutment Level Impression after Soft Tissue Adaptation around Provisional Restoration

PubMed Central

Kutkut, Ahmad; Abu-Hammad, Osama; Frazer, Robert

2016-01-01

Impression techniques for implant restorations can be implant level or abutment level impressions with open tray or closed tray techniques. Conventional implant-abutment level impression techniques are predictable for maximizing esthetic outcomes. Restoration of the implant traditionally requires the use of the metal or plastic impression copings, analogs, and laboratory components. Simplifying the dental implant restoration by reducing armamentarium through incorporating conventional techniques used daily for crowns and bridges will allow more general dentists to restore implants in their practices. The demonstrated technique is useful when modifications to implant abutments are required to correct the angulation of malpositioned implants. This technique utilizes conventional crown and bridge impression techniques. As an added benefit, it reduces costs by utilizing techniques used daily for crowns and bridges. The aim of this report is to describe a simplified conventional impression technique for custom abutments and modified prefabricated solid abutments for definitive restorations. PMID:29563457

Multilevel-Dc-Bus Inverter For Providing Sinusoidal And Pwm Electrical Machine Voltages

DOEpatents

Su, Gui-Jia [Knoxville, TN

2005-11-29

A circuit for controlling an ac machine comprises a full bridge network of commutation switches which are connected to supply current for a corresponding voltage phase to the stator windings, a plurality of diodes, each in parallel connection to a respective one of the commutation switches, a plurality of dc source connections providing a multi-level dc bus for the full bridge network of commutation switches to produce sinusoidal voltages or PWM signals, and a controller connected for control of said dc source connections and said full bridge network of commutation switches to output substantially sinusoidal voltages to the stator windings. With the invention, the number of semiconductor switches is reduced to m+3 for a multi-level dc bus having m levels. A method of machine control is also disclosed.

Hydrographic surveys of the Missouri and Yellowstone Rivers at selected bridges and through Bismarck, North Dakota, during the 2011 flood

USGS Publications Warehouse

Densmore, Brenda K.; Strauch, Kellan R.; Dietsch, Benjamin J.

2013-01-01

The U.S. Geological Survey (USGS), in cooperation with the North Dakota Department of Transportation and the North Dakota State Water Commission, completed hydrographic surveys at six Missouri River bridges and one Yellowstone River bridge during the 2011 flood of the Missouri River system. Bridges surveyed are located near the cities of Cartwright, Buford, Williston, Washburn, and Bismarck, N. Dak. The river in the vicinity of the bridges and the channel through the city of Bismarck, N. Dak., were surveyed. The hydrographic surveys were conducted using a high-resolution multibeam echosounder (MBES), the RESON SeaBatTM 7125, during June 6–9 and June 28–July 9, 2011. The surveyed area at each bridge site extended 820 feet upstream from the bridge to 820 feet downstream from the bridge. The surveyed reach through Bismarck consisted of 18 miles of the main channel wherever depth was sufficient. Results from these emergency surveys aided the North Dakota Department of Transportation in evaluating the structural integrity of the bridges during high-flow conditions. In addition, the sustained high flows made feasible the surveying of a large section of the normally shallow channel with the MBES. In general, results from sequential bridge surveys showed that as discharge increased between the first and second surveys at a given site, there was a general trend of channel scour. Locally, complex responses of scour in some areas and deposition in other areas of the channel were identified. Similarly, scour around bridge piers also showed complex responses to the increase in flow between the two surveys. Results for the survey area of the river channel through Bismarck show that, in general, scour occurred around river structures or where the river has tight bends and channel narrowing. The data collected during the surveys are provided electronically in two different file formats: comma delimited text and CARIS Spatial ArchiveTM (CSARTM) format.

[2.2]paracyclophane-bridged mixed-valence compounds: application of a generalized Mulliken-Hush three-level model.

PubMed

Amthor, Stephan; Lambert, Christoph

2006-01-26

A series of [2.2]paracylophane-bridged bis-triarylamine mixed-valence (MV) radical cations were analyzed by a generalized Mulliken-Hush (GMH) three-level model which takes two transitions into account: the intervalence charge transfer (IV-CT) band which is assigned to an optically induced hole transfer (HT) from one triarylamine unit to the second one and a second band associated with a triarylamine radical cation to bridge (in particular, the [2.2]paracyclophane bridge) hole transfer. From the GMH analysis, we conclude that the [2.2]paracyclophane moiety is not the limiting factor which governs the intramolecular charge transfer. AM1-CISD calculations reveal that both through-bond as well as through-space interactions of the [2.2]paracyclophane bridge play an important role for hole transfer processes. These electronic interactions are of course smaller than direct pi-conjugation, but from the order of magnitude of the couplings of the [2.2]paracyclophane MV species, we assume that this bridge is able to mediate significant through-space and through-bond interactions and that the cyclophane bridge acts more like an unsaturated spacer rather than a saturated one. From the exponential dependence of the electronic coupling V between the two triarylamine localized states on the distance r between the two redox centers, we infer that the hole transfer occurs via a superexchange mechanism. Our analysis reveals that even significantly longer pi-conjugated bridges should still mediate significant electronic interactions because the decay constant beta of a series of pi-conjugated MV species is small.

High extinction ratio terahertz wire-grid polarizers with connecting bridges on quartz substrates.

PubMed

Cetnar, John S; Vangala, Shivashankar; Zhang, Weidong; Pfeiffer, Carl; Brown, Elliott R; Guo, Junpeng

2017-03-01

A terahertz (THz) wire-grid polarizer with metallic bridges on a quartz substrate was simulated, fabricated, and tested. The device functions as a wide-band polarizer to incident THz radiation. In addition, the metallic bridges permit the device to function as a transparent electrode when a DC bias is applied to it. Three design variations of the polarizer with bridges and a polarizer without bridges were studied. Results show the devices with bridges have average s-polarization transmittance of less than -3  dB and average extinction ratios of approximately 40 dB across a frequency range of 220-990 GHz and thus are comparable to a polarizer without bridges.

Facilitators and barriers of adopting healthy lifestyle in rural China: a qualitative analysis through social capital perspectives.

PubMed

Zhang, Yan; Ma, Defu; Cui, Renzhe; Haregot Hilawe, Esayas; Chiang, Chifa; Hirakawa, Yoshihisa; Hu, Yonghua; Wang, Peiyu; Iso, Hiroyasu; Aoyama, Atsuko

2016-05-01

Non-communicable diseases (NCDs) are the major public health concerns in China. However, little has been known yet about the background social factors that influence lifestyles as possible NCD risk factors. This qualitative study aimed to explore facilitators and barriers of adopting healthy lifestyles among residents in a rural community of China. Three age-stratified focus group discussions (FGDs) were conducted in Fangshan district of Beijing in 2013. A FGD guide was designed to elicit the participants' perception and experience regarding their lifestyles. The audio-records were transcribed, and data were qualitatively analyzed through thematic approach. Through social capital framework with bonding, bridging, and linking classifications, we identified the following facilitators and barriers to adopt healthy lifestyles. (1) Facilitators: mutual support from family/friends and motivation to participate in regular exercises (bonding); cooperative relationships with community health workers (bridging); and nationwide high level of healthy lifestyle awareness (linking). (2) Barriers: negative influence from family/friends, insufficient support from family/friends, peer pressure and tolerance towards unhealthy lifestyles (bonding); insufficient support from health professionals (bridging); and inequity in allocation of public resources (linking). This study revealed that bonding, bridging and linking social capital would work as facilitators and barriers to adopt healthy lifestyles among rural residents in China.

Great Salt Lake, Utah, USA

NASA Technical Reports Server (NTRS)

1990-01-01

As seen from space, the Great Salt Lake, Utah, USA (41.5N, 112.5W) appears as two separate bodies of water with a narrow divider in the middle. At the turn of the century, a railroad bridge without culverts, was built across the lake and ever since, the water and salinity levels have been uneqal on either side. Fed by snowmelt from the nearby Wasatch Mountains, the lake in recent years has had record high water levels, threatening to flood the local areas.

Great Salt Lake, Utah, USA

NASA Image and Video Library

1990-03-04

As seen from space, the Great Salt Lake, Utah, USA (41.5N, 112.5W) appears as two separate bodies of water with a narrow divider in the middle. At the turn of the century, a railroad bridge without culverts, was built across the lake and ever since, the water and salinity levels have been uneqal on either side. Fed by snowmelt from the nearby Wasatch Mountains, the lake in recent years has had record high water levels, threatening to flood the local areas.

Fatigue crack modeling in bridge deck connection details

DOT National Transportation Integrated Search

1999-12-01

Many steel bridges built prior to 1960 have bridge deck connections that are subject to high cycle fatigue. These connections may be nearing their fatigue limit and will require increased inspection and repair over the next 10 - 20 years. Current ins...

8. The entire south face of the Broad Street bridge ...

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

8. The entire south face of the Broad Street bridge as seen from the flood levy in front of Central High School. - Broad Street Bridge, Spanning Scioto River at U.S. Route 40 (Broad Street), Columbus, Franklin County, OH

Reflective Cracking between Precast Prestressed Box Girders

DOT National Transportation Integrated Search

2017-06-30

The adjacent precast prestressed concrete box-beam bridge is the bridge of choice for short and short-to-medium span bridges. This choice is because of the ease of construction, favorable span-to-depth ratios, aesthetic appeal, and high torsional sti...

9. View to northeast. Oblique view of upstream side of ...

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

9. View to northeast. Oblique view of upstream side of bridge from approximately deck level. (90mm lens) - South Fork Trinity River Bridge, State Highway 299 spanning South Fork Trinity River, Salyer, Trinity County, CA

Environmental classification scheme for Pontis.

DOT National Transportation Integrated Search

1994-01-01

In an effort to comply with the federal mandate for bridge management systems, many states have chosen to implement an existing system rather than develop their own. One such system is Pontis, the network-level bridge management system developed thro...

Use of high performance, high strength concrete (HPC) bulb-tee girders saves millions on I-10 twin span bridge in New Orleans district.

DOT National Transportation Integrated Search

2005-01-01

History: LADOTD has been gradually introducing high performance, high strength concrete into its bridge construction program. At the same time, LTRC has been sponsoring research work to address design and construction issues related to the utilizatio...

Plans for a sensitivity analysis of bridge-scour computations

USGS Publications Warehouse

Dunn, David D.; Smith, Peter N.

1993-01-01

Plans for an analysis of the sensitivity of Level 2 bridge-scour computations are described. Cross-section data from 15 bridge sites in Texas are modified to reflect four levels of field effort ranging from no field surveys to complete surveys. Data from United States Geological Survey (USGS) topographic maps will be used to supplement incomplete field surveys. The cross sections are used to compute the water-surface profile through each bridge for several T-year recurrence-interval design discharges. The effect of determining the downstream energy grade-line slope from topographic maps is investigated by systematically varying the starting slope of each profile. The water-surface profile analyses are then used to compute potential scour resulting from each of the design discharges. The planned results will be presented in the form of exceedance-probability versus scour-depth plots with the maximum and minimum scour depths at each T-year discharge presented as error bars.

Acoustic energy propagation around railways

NASA Astrophysics Data System (ADS)

Cizkova, Petra

2017-09-01

The article deals with the issues of acoustic energy propagation around railways. The research subject was noise emission spreading into the surroundings during the passage of trains over a directly travelled steel bridge construction. Noise emissions were measured using direct measurements in the field. The measurements were performed in two measurement profiles. The noise exposures A LAE measured near the steel bridge construction were compared against the noise exposures A LAE captured on an open track. From the difference of these data, the noise level of the steel bridge structure was determined. Part of the research was to evaluate the effect of the reconstruction of the railway track superstructure on the acoustic situation in the given section of the railway track. The article describes the methodology of measurements, including the processing and evaluation of measured data. The article points out the noise levels of the steel bridge construction and assesses changes in the acoustic situation after the reconstruction.

High performance concrete in a bridge in Richlands, Virginia

DOT National Transportation Integrated Search

1999-09-01

The Virginia Department of Transportation built a high-performance concrete (HPC) bridge with high-strength and low-permeability concrete in Richlands. The beams had a minimum compressive strength of 69 MPa (10,000 psi) at 28 days and large, 15 mm (0...

Building Better Bridges into STEM: A Synthesis of 25 Years of Literature on STEM Summer Bridge Programs.

PubMed

Ashley, Michael; Cooper, Katelyn M; Cala, Jacqueline M; Brownell, Sara E

2017-01-01

Summer bridge programs are designed to help transition students into the college learning environment. Increasingly, bridge programs are being developed in science, technology, engineering, and mathematics (STEM) disciplines because of the rigorous content and lower student persistence in college STEM compared with other disciplines. However, to our knowledge, a comprehensive review of STEM summer bridge programs does not exist. To provide a resource for bridge program developers, we conducted a systematic review of the literature on STEM summer bridge programs. We identified 46 published reports on 30 unique STEM bridge programs that have been published over the past 25 years. In this review, we report the goals of each bridge program and whether the program was successful in meeting these goals. We identify 14 distinct bridge program goals that can be organized into three categories: academic success goals, psychosocial goals, and department-level goals. Building on the findings of published bridge reports, we present a set of recommendations for STEM bridge programs in hopes of developing better bridges into college. © 2017 M. Ashley, K. M. Cooper, et al. CBE—Life Sciences Education © 2017 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Flood-inundation maps for the Wabash River at Memorial Bridge at Vincennes, Indiana

USGS Publications Warehouse

Fowler, Kathleen K.; Menke, Chad D.

2017-08-23

Digital flood-inundation maps for a 10.2-mile reach of the Wabash River from Sevenmile Island to 3.7 mile downstream of Memorial Bridge (officially known as Lincoln Memorial Bridge) at Vincennes, Indiana, were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Office of Community and Rural Affairs. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/ depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at USGS streamgage 03343010, Wabash River at Memorial Bridge at Vincennes, Ind. Near-real-time stages at this streamgage may be obtained on the Internet from the USGS National Water Information System at http://waterdata.usgs.gov/ or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at http:/water.weather.gov/ahps/, which also forecasts flood hydrographs at this site.For this study, flood profiles were computed for the Wabash River reach by means of a one-dimensional stepbackwater model. The hydraulic model was calibrated by using the most current stage-discharge relations at USGS streamgage 03343010, Wabash River at Memorial Bridge at Vincennes, Ind., and preliminary high-water marks from a high-water event on April 27, 2013. The calibrated hydraulic model was then used to determine 19 water-surface profiles for flood stages at 1-foot intervals referenced to the streamgage datum and ranging from 10 feet (ft) or near bankfull to 28 ft, the highest stage of the current stage-discharge rating curve. The simulated water-surface profiles were then combined with a Geographic Information System (GIS) digital elevation model (DEM, derived from Light Detection and Ranging [lidar] data having a 0.98-ft vertical accuracy and 4.9-ft horizontal resolution) in order to delineate the area flooded at each water level.The availability of these maps—along with Internet information regarding current stage from the USGS streamgage 03343010, and forecast stream stages from the NWS AHPS—provides emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, as well as for post-flood recovery efforts.

The Effects of Interdiction in World War II: The European Theater of Operation

DTIC Science & Technology

1984-05-07

columns, bridges , communication centers, signal communications, ’and anti-aircraft artillery. * ic.X -. •:. ~uc I Unclassified SECURITY CL ASSI FIC...concentrations, enemy coiumns, bridges , communication centers, signal communications, and anti-aircraft artillery. I TABLE Of CONTENT lUTLE EAUi CHAPTER I... bridge destruction and traffic levels. This report made only a minor contribution because it covered 3ust one-week. Another report from the same

Building the Bridge: Inservice Training for Teachers of Educationally Disadvantaged. Final Report: July 1, 1980-August 31, 1981.

ERIC Educational Resources Information Center

Bitterlin, Gretchen

This three-part report describes the Bridging Program at San Diego Mesa College (SDMC), a basic skills program to prepare students functioning at the 7th grade level or below and to thus provide a bridge between developmental education and adult basic education (ABE). Part I begins with a review of the program's background and a list of its…

Bridging the Divide: Examining Professional Unity and the Extended Teacher Union Role in Sweden

ERIC Educational Resources Information Center

Milner, Alison

2018-01-01

Sweden has experienced increasing educational inequity levels within its highly decentralized school system. With a reduced capacity to bargain collectively, the two Swedish teacher trade unions, the Swedish Teachers' Union (Lärarförbundet) and the National Union of Teachers in Sweden (Lärarnas Riksförbund), have sought to extend their role in…

Two-dimensional analysis of coupled heat and moisture transport in masonry structures

NASA Astrophysics Data System (ADS)

Krejčí, Tomáš

2016-06-01

Reconstruction and maintenance of historical buildings and bridges require good knowledge of temperature and moisture distribution. Sharp changes in the temperature and moisture can lead to damage. This paper describes analysis of coupled heat and moisture transfer in masonry based on two-level approach. Macro-scale level describes the whole structure while meso-scale level takes into account detailed composition of the masonry. The two-level approach is very computationally demanding and it was implemented in parallel. The two-level approach was used in analysis of temperature and moisture distribution in Charles bridge in Prague, Czech Republic.

Bridging the gap between system and cell: The role of ultra-high field MRI in human neuroscience.

PubMed

Turner, Robert; De Haan, Daniel

2017-01-01

The volume of published research at the levels of systems and cellular neuroscience continues to increase at an accelerating rate. At the same time, progress in psychiatric medicine has stagnated and scientific confidence in cognitive psychology research is under threat due to careless analysis methods and underpowered experiments. With the advent of ultra-high field MRI, with submillimeter image voxels, imaging neuroscience holds the potential to bridge the cellular and systems levels. Use of these accurate and precisely localized quantitative measures of brain activity may go far in providing more secure foundations for psychology, and hence for more appropriate treatment and management of psychiatric illness. However, fundamental issues regarding the construction of testable mechanistic models using imaging data require careful consideration. This chapter summarizes the characteristics of acceptable models of brain function and provides concise descriptions of the relevant types of neuroimaging data that have recently become available. Approaches to data-driven experiments and analyses are described that may lead to more realistic conceptions of the competences of neural assemblages, as they vary across the brain's complex neuroanatomy. © 2017 Elsevier B.V. All rights reserved.

Improving resistance of high strength concrete (HSC) bridge beams to frost and defrosting salt attack by application of hydrophobic agent

NASA Astrophysics Data System (ADS)

Kolisko, Jiri; Balík, Lukáš; Kostelecka, Michaela; Pokorný, Petr

2017-09-01

HSC (High Strength Concrete) is increasingly used for bearing bridge structures nowadays. Bridge structures in the Czech Republic are exposed to severe conditions in winter time and durability of the concrete is therefore a crucial requirement. The high strength and low water absorption of HSC suggests that the material will have high durability. However, the situation may not be so straightforward. We carried out a study of the very poor durability of HSC concrete C70/85 used to produce prestresed beams 37.1 m in length to build a 6-span highway bridge. After the beams were cast, a production control test indicated some problems with the durability of the concrete. There was a danger that 42 of the beams would not be suitable for use. All participants in the bridge project finally decided, after extensive discussions, to attempt to improve the durability of the concrete by applying a hydrophobic agent. Paper will present the results of comparative tests of four hydrophobic agents in order to choose one for real application and describes this application on construction site.

Using Ground Radar Interferometry for Precise Determining of Deformation and Vertical Deflection of Structures

NASA Astrophysics Data System (ADS)

Talich, Milan

2017-12-01

The paper describes possibilities of the relatively new technics - ground based radar interferometry for precise determining of deformation of structures. Special focus on the vertical deflection of bridge structures and on the horizontal movements of high-rise buildings and structural objects is presented. The technology of ground based radar interferometry can be used in practice to the contactless determination of deformations of structures with accuracy up to 0.01 mm in real time. It is also possible in real time to capture oscillations of the object with a frequency up to 50 Hz. Deformations can be determined simultaneously in multiple places of the object, for example a bridge structure at points distributed on the bridge deck at intervals of one or more meters. This allows to obtain both overall and detailed information about the properties of the structure during the dynamic load and monitoring the impact of movements either individual vehicles or groups. In the case of high-rise buildings, it is possible to monitor the horizontal vibration of the whole object at its different height levels. It is possible to detect and determine the compound oscillations that occur in some types of buildings. Then prevent any damage or even disasters in these objects. In addition to the necessary theory basic principles of using radar interferometry for determining of deformation of structures are given. Practical examples of determining deformation of bridge structures, water towers reservoirs, factory chimneys and wind power plants are also given. The IBIS-S interferometric radar of the Italian IDS manufacturer was used for the measurements.

Assessment of bridge scour in the lower, middle, and upper Yangtze River estuary with riverbed sonar profiling techniques.

PubMed

Zheng, Shuwei; Xu, Y Jun; Cheng, Heqin; Wang, Bo; Lu, Xuejun

2017-12-12

Riverbed scour of bridge piers can cause rapid loss in foundation strength, leading to sudden bridge collapse. This study used multi-beam echo sounders (Seabat 7125) to map riverbed surrounding the foundations of four major bridges in the lower, middle, and upper reaches of the 700-km Yangtze River Estuary (YRE) during June 2015 and September 2016. The high-resolution data were utilized to analyze the morphology of the bridge scour and the deformation of the wide-area riverbed (i.e., 5-18 km long and 1.3-8.3 km wide). In addition, previous bathymetric measurements collected in 1998, 2009, and 2013 were used to determine riverbed erosion and deposition at the bridge reaches. Our study shows that the scour depth surrounding the bridge foundations progressed up to 4.4-19.0 m in the YRE. Over the past 5-15 years, the total channel erosion in some river reaches was up to 15-17 m, possessing a threat to the bridge safety in the YRE. Tide cycles seemed to have resulted in significant variation in the scour morphology in the lower and middle YRE. In the lower YRE, the riverbed morphology displayed one long erosional ditch on both sides of the bridge foundations and a long-strip siltation area distributed upstream and downstream of the bridge foundations; in the middle YRE, the riverbed morphology only showed erosional morphology surrounding the bridge foundations. Large dunes caused deep cuts and steeper contours in the bridge scour. Furthermore, this study demonstrates that the high-resolution grid model formed by point cloud data of multi-beam echo sounders can clearly display the morphology of the bridge scour in terms of wide areas and that the sonar technique is a very useful tool in the assessment of bridge scours.

A Bridge to Active Learning: A Summer Bridge Program Helps Students Maximize Their Active-Learning Experiences and the Active-Learning Experiences of Others

ERIC Educational Resources Information Center

Cooper, Katelyn M.; Ashley, Michael; Brownell, Sara E.

2017-01-01

National calls to improve student academic success in college have sparked the development of bridge programs designed to help students transition from high school to college. We designed a 2-week Summer Bridge program that taught introductory biology content in an active-learning way. Through a set of exploratory interviews, we unexpectedly…

Assessment of impact of mass movements on the upper Tayyah valley's bridge along Shear escarpment highway, Asir region (Saudi Arabia) using remote sensing data and field investigation

NASA Astrophysics Data System (ADS)

Youssef, A. M.; Al-Kathery, M.; Pradhan, B.

2015-01-01

Escarpment highways, roads and mountainous areas in Saudi Arabia are facing landslide hazards that are frequently occurring from time to time causing considerable damage to these areas. Shear escarpment highway is located in the north of the Abha city. It is the most important escarpment highway in the area, where all the light and heavy trucks and vehicle used it as the only corridor that connects the coastal areas in the western part of the Saudi Arabia with the Asir and Najran Regions. More than 10 000 heavy trucks and vehicles use this highway every day. In the upper portion of Tayyah valley of Shear escarpment highway, there are several landslide and erosion potential zones that affect the bridges between tunnel 7 and 8 along the Shear escarpment Highway. In this study, different types of landslides and erosion problems were considered to access their impacts on the upper Tayyah valley's bridge along Shear escarpment highway using remote sensing data and field investigation. These landslides and erosion problems have a negative impact on this section of the highway. Results indicate that the areas above the highway and bridge level between bridge 7 and 8 have different landslides including planar, circular, rockfall failures and debris flows. In addition, running water through the gullies cause different erosional (scour) features between and surrounding the bridge piles and culverts. A detailed landslides and erosion features map was created based on intensive field investigation (geological, geomorphological, and structural analysis), and interpretation of Landsat image 15 m and high resolution satellite image (QuickBird 0.61 m), shuttle radar topography mission (SRTM 90 m), geological and topographic maps. The landslides and erosion problems could exhibit serious problems that affect the stability of the bridge. Different mitigation and remediation strategies have been suggested to these critical sites to minimize and/or avoid these problems in the future.

Army ants dynamically adjust living bridges in response to a cost–benefit trade-off

PubMed Central

Reid, Chris R.; Lutz, Matthew J.; Powell, Scott; Kao, Albert B.; Couzin, Iain D.; Garnier, Simon

2015-01-01

The ability of individual animals to create functional structures by joining together is rare and confined to the social insects. Army ants (Eciton) form collective assemblages out of their own bodies to perform a variety of functions that benefit the entire colony. Here we examine ‟bridges” of linked individuals that are constructed to span gaps in the colony’s foraging trail. How these living structures adjust themselves to varied and changing conditions remains poorly understood. Our field experiments show that the ants continuously modify their bridges, such that these structures lengthen, widen, and change position in response to traffic levels and environmental geometry. Ants initiate bridges where their path deviates from their incoming direction and move the bridges over time to create shortcuts over large gaps. The final position of the structure depended on the intensity of the traffic and the extent of path deviation and was influenced by a cost–benefit trade-off at the colony level, where the benefit of increased foraging trail efficiency was balanced by the cost of removing workers from the foraging pool to form the structure. To examine this trade-off, we quantified the geometric relationship between costs and benefits revealed by our experiments. We then constructed a model to determine the bridge location that maximized foraging rate, which qualitatively matched the observed movement of bridges. Our results highlight how animal self-assemblages can be dynamically modified in response to a group-level cost–benefit trade-off, without any individual unit’s having information on global benefits or costs. PMID:26598673

High cycle fatigue crack modeling and analysis for deck truss flooring connection details : final report.

DOT National Transportation Integrated Search

1997-07-01

The Oregon Department of Transportation is responsible for many steel deck truss bridges containing connection details that are fatigue prone. A typical bridge, the Winchester Bridge in Roseburg, Oregon, was analyzed to assess the loading conditions,...

Highly accelerated lifetime for externally applied bond critical fiber-reinforced polymer (FRP) infrastructure materials : [summary].

DOT National Transportation Integrated Search

2014-03-01

The Florida Department of Transportation (FDOT) uses fiber-reinforced polymer (FRP) composites to repair bridges and strengthen bridge decks. Proven mechanical characteristics make FRP composites cost-effective in extending the life span of bridges o...

Forces in wingwalls from thermal expansion of skewed semi-integral bridges.

DOT National Transportation Integrated Search

2010-11-01

Jointless bridges, such as semi-integral and integral bridges, have become more popular in recent years because of their simplicity in the construction and the elimination of high costs related to joint maintenance. Prior research has shown that skew...

Fatigue crack modeling in bridge deck connection details : final report.

DOT National Transportation Integrated Search

1999-12-01

Many steel bridges built prior to 1960 have bridge deck connections that are subject to high cycle fatigue. These connections may be nearing their fatigue limit and will require increased inspection and repair over the next 10 - 20 years. Current ins...

Developing cost effective plans for low volume bridges

DOT National Transportation Integrated Search

2006-09-01

There is currently an escalating concern across the state of Kansas with respect to the age : and condition of low volume bridges and methods available to modify or replace them. A : high percentage of low volume bridges in the state of Kansas requir...

Delineation of tidal scour through marine geophysical techniques at Sloop Channel and Goose Creek bridges, Jones Beach State Park, Long Island, New York

USGS Publications Warehouse

Stumm, Frederick; Chu, Anthony; Reynolds, Richard J.

2001-01-01

Inspection of the Goose Creek Bridge in southeastern Nassau County in April 1998 by the New York State Department of Transportation (NYSDOT) indicated a separation of bridge piers from the road bed as a result of pier instability due to apparent seabed scouring by tidal currents. This prompted a cooperative study by the U.S. Geological Survey with the NYSDOT to delineate the extent of tidal scour at this bridge and at the Sloop Channel Bridge, about 0.5 mile to the south, through several marine- geophysical techniques. These techniques included use of a narrow-beam, 200-kilohertz, research-grade fathometer, a global positioning system accurate to within 3 feet, a 3.5 to 7-kilohertz seismic-reflection profiler, and an acoustic Doppler current profiler (ADCP). The ADCP was used only at the Sloop Channel Bridge; the other techniques were used at both bridges.Results indicate extensive tidal scour at both bridges. The fathometer data indicate two major scour holes nearly parallel to the Sloop Channel Bridge—one along the east side, and one along the west side (bridge is oriented north-south). The scour-hole depths are as much as 47 feet below sea level and average more than 40 feet below sea level; these scour holes also appear to have begun to connect beneath the bridge. The deepest scour is at the north end of the bridge beneath the westernmost piers. The east-west symmetry of scour at Sloop Channel Bridge suggests that flood and ebb tides produce extensive scour.The thickness of sediment that has settled within scour holes could not be interpreted from fathometer data alone because fathometer frequencies cannot penetrate beneath the sea-floor surface. The lower frequencies used in seismic-reflection profiling can penetrate the sea floor and underlying sediments, and indicate the amount of infilling of scour holes, the extent of riprap under the bridge, and the assemblages of clay, sand, and silt beneath the sea floor. The seismic- reflection surveys detected 2 to 5 feet of sediment filling the scour holes at both bridges; this indicates that the fathometer surveys were undermeasuring the effective depth of bridge scour by 2 to 5 feet through their inability to penetrate the infilled sediment. Several clay layers with thicknesses of 3 to 5 feet were detected beneath the sea floor at both bridges. Most of the piers beneath Sloop Channel Bridge appear to be surrounded by riprap, but, in several areas the riprap appears to be slumping or sliding into adjacent scour holes. Similar slumping was indicated at the Goose Creek Bridge. Most of the sediment underlying the sea floor at both bridges is interpreted as a fine-grained, cross-bedded sand.ADCP data from Sloop Channel indicate that the constricted flow beneath the bridge increases the horizontal current velocities from 2 to 6 feet per second. Total measured discharge beneath Sloop Channel Bridge was 41,800 cubic feet per second at flood tide and 27,600 cubic feet per second at ebb tide.

Repair of earthquake-damaged bridge columns with interlocking spirals and fractured bars.

DOT National Transportation Integrated Search

2014-07-01

During earthquakes, reinforced concrete (RC) bridge columns may experience different levels of damage such as cracking, spalling, or crushing of concrete and yielding, buckling, or fracture of reinforcing bars. Although several repair options exist f...

Condition assessment of short-line railroad bridges in Pennsylvania.

DOT National Transportation Integrated Search

2010-02-01

Current levels of available resources to maintain and preserve the Pennsylvania short-line railroad (SLRR) bridge infrastructure require that important priority decisions be made on an annual basis. The primary objective of this study was to establis...

4. View to westsouthwest. Oblique view of upstream side of ...

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

4. View to west-southwest. Oblique view of upstream side of bridge from approximately deck level. (90mm lens) - South Fork Trinity River Bridge, State Highway 299 spanning South Fork Trinity River, Salyer, Trinity County, CA

Acoustic emission techniques applied to conventionally reinforced concrete bridge girders.

DOT National Transportation Integrated Search

2008-09-01

Reinforced concrete (RC) bridges generally operate at service-level loads except during discrete overload events that can reduce the integrity of the structure by initiating concrete cracks, widening or extending of existing concrete cracks, as well ...

Herschel Spectroscopy of the Taffy Galaxies (UGC 12914/12915 = VV 254): Enhanced [C II] Emission in the Collisionally Formed Bridge

NASA Astrophysics Data System (ADS)

Peterson, B. W.; Appleton, P. N.; Bitsakis, T.; Guillard, P.; Alatalo, K.; Boulanger, F.; Cluver, M.; Duc, P.-A.; Falgarone, E.; Gallagher, S.; Gao, Y.; Helou, G.; Jarrett, T. H.; Joshi, B.; Lisenfeld, U.; Lu, N.; Ogle, P.; Pineau des Forêts, G.; van der Werf, P.; Xu, C. K.

2018-03-01

Using the PACS and SPIRE spectrometers on board Herschel, we obtained observations of the Taffy galaxies (UGC 12914/12915) and bridge. The Taffy system is believed to be the result of a face-on collision between two gas-rich galaxies, in which the stellar disks passed through each other, but the gas was dispersed into a massive H I and molecular bridge between them. Emission is detected and mapped in both galaxies and the bridge in the [C II]157.7 μm and [O I]63.2 μm fine-structure lines. Additionally, SPIRE FTS spectroscopy detects the [C I] {}3{{{P}}}2\\to {}3{{{P}}}1(809.3 {GHz}) and [C I] {}3{{{P}}}1\\to 3{{{P}}}0(492.2 {GHz}) neutral carbon lines, and weakly detects high-J CO transitions in the bridge. These results indicate that the bridge is composed of a warm multi-phase medium consistent with shock and turbulent heating. Despite low star formation rates in the bridge, the [C II] emission appears to be enhanced, reaching [C II]/FIR ratios of 3.3% in parts of the bridge. Both the [C II] and [O I] lines show broad intrinsic multi-component profiles, similar to those seen in previous CO (1–0) and H I observations. The [C II] emission shares similar line profiles with both the double-peaked H I profiles and shares a high-velocity component with single-peaked CO profiles in the bridge, suggesting that the [C II] emission originates in both the neutral and molecular phases. We show that it is feasible that a combination of turbulently heated H2 and high column-density H I, resulting from the galaxy collision, is responsible for the enhanced [C II] emission.

Flood Early Warning in Bridge Management System: from idea to implementation

NASA Astrophysics Data System (ADS)

Kerin, Igor; Bekić, Damir; Michalis, Panagiotis; Šolman, Hrvoje; Cahill, Paul; Gilja, Gordon; Pakrashi, Vikram; Lapthorne, John; McKeogh, Eamon

2017-04-01

Recent advances in computational speed, cloud systems and GPRS data are some of the factors that have resulted in an increased number of operational and fully automatized Flood Early Warning Systems (FEWS). Flood forecasting is becoming a well-recognised solution for flood management as an indirect measure for minimising the risk should preventive or defence measures prove ineffective or are not feasible for implementation. Public acceptance of FEWS as a standalone solution is still considered to be at low level. Further public engagement regarding engineering risks and providing timely notifications and warnings can, however, establish the true value of such a system to the society in general. Flood risks can be direct, resulting in damage to buildings, infrastructure and natural resources, or indirect, which can be related to disaster losses leading to declines in commercial output or revenue and impact on wellbeing of people, typically from disruptions to the flow of goods and services. Flood risk and structural risks are closely related, thereby impacting the maintenance and management of bridges assets over watercourses. Many studies indicate that most bridge collapses are related to hydraulic effects and consequently scour issues (i.e. the removal of riverbed around bridge foundations due to flowing water). Consequently, hydraulic, hydrologic and geotechnical expertise and knowledge can lead to introducing FEWS as a key tool for Bridge Scour Management System (BSMS), forming a part of a BMS. The implementation of this concept was initiated with the EU/FP7 funded project BRIDGE SMS. The project introduces BSMS into the overall BMS to develop a reliable decision support tool which would efficiently manage bridge failure risks in a cost-effective way. This is accomplished through the development of FEWS, alongside monitoring systems that can provide important information about environmental and structural conditions at the catchment area and bridge site respectively. The recorded rainfall from instrumentation deployed over a catchment is used as input data for hydrological modelling and now-casting, which results in flow hydrographs at the bridge containing flow rates and water level information. Soil moisture data is also used to determine the appropriate hydrological model set-up, such as dry, medium or saturated catchment conditions. The output from the hydrological model is a now-cast flow hydrograph, with a lag time of up to 24 hours. Discharge hydrograph is correlated to water levels using an existing rating curve and to the flow velocity using discharge-flow velocity curve. Water levels and flow rates are correlated to the flow velocity which provide the basis for the prediction of scour depth. FEWS in BMS introduces readiness for extreme flood events, pointing out key indicators prior to an event. Also, by considering climate change effects which is resulting in more extreme weather phenomena's, FEWS provides important information about bridge safety and assists to coordinate resources in an efficient and cost-effective way. Acknowledgement The authors wish to acknowledge the financial support of the European Commission, through the Marie-Curie Industry-Academia Partnership and Pathways Network BRIDGE SMS (Intelligent Bridge Assessment Maintenance and Management System) - FP7-People-2013-IAPP- 612517.

Development of Murray Loop Bridge for High Induced Voltage

NASA Astrophysics Data System (ADS)

Isono, Shigeki; Kawasaki, Katsutoshi; Kobayashi, Shin-Ichi; Ishihara, Hayato; Chiyajo, Kiyonobu

In the case of the cable fault that ground fault resistance is less than 10MΩ, Murray Loop Bridge is excellent as a fault locator in location accuracy and the convenience. But, when the induction of several hundred V is taken from the single core cable which adjoins it, a fault location with the high voltage Murray Loop Bridge becomes difficult. Therefore, we developed Murray Loop Bridge, which could be applied even when the induced voltage of several hundred V occurs in the measurement cable. The evaluation of the fault location accuracy was done with the developed prototype by the actual line and the training equipment.

Walla Walla River Basin Fish Screen Evaluations; Nursery Bridge Fishway and Garden City/Lowden II Sites, 2005-2006 Progress Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chamness, Mickie

2006-06-01

Pacific Northwest National Laboratory (PNNL) evaluated two fish screen facilities in the Walla Walla River basin in 2005 and early 2006. The Garden City/Lowden screen site was evaluated in April and June 2005 to determine whether the fish screens met National Marine Fisheries Service criteria to provide safe passage for juvenile salmonids. Louvers behind the screens at the Nursery Bridge Fishway were modified in fall 2005 in an attempt to minimize high approach velocities. PNNL evaluated the effects of those modifications in March 2006. Results of the Garden City/Lowden evaluations indicate the site performs well at varying river levels andmore » canal flows. Approach velocities did not exceed 0.4 feet per second (fps) at any time. Sweep velocities increased toward the fish ladder in March but not in June. The air-burst mechanism appears to keep large debris off the screens, although it does not prevent algae and periphyton from growing on the screen face, especially near the bottom of the screens. At Nursery Bridge, results indicate all the approach velocities were below 0.4 fps under the moderate river levels and operational conditions encountered on March 7, 2006. Sweep did not consistently increase toward the fish ladder, but the site generally met the criteria for safe passage of juvenile salmonids. Modifications to the louvers seem to allow more control over the amount of water moving through the screens. We will measure approach velocities when river levels are higher to determine whether the louver modifications can help correct excessive approach velocities under a range of river levels and auxiliary water supply flows.« less

Evaluation of lightweight high performance concrete in bulb-T beams and decks in two bridges on Route 33 in Virginia.

DOT National Transportation Integrated Search

2009-01-01

Lightweight high performance concrete (LWHPC) is expected to provide high strength and high durability along with reduced weight. The purpose of this research was to evaluate and compare the prestressed LWHPC bulb-T beams and decks in two bridge stru...

Developing cost effective plans for low volume bridges

DOT National Transportation Integrated Search

2006-09-01

There is currently an escalating concern across the state of Kansas with respect to the age and condition of low volume bridges and methods available to modify or replace them. A high percentage of low volume bridges in the state of Kansas require or...

Behavior of field-cast ultra-high performance concrete bridge deck connections under cyclic and static structural loading

DOT National Transportation Integrated Search

2010-11-01

The use of modular bridge deck components has the potential to produce higher quality, more durable bridge decks; however, the required connections have often proved lacking, resulting in less than desirable overall system performance. Advanced cemen...

Cost effective bridge deck reconstruction in Kansas using high-density concrete overlays and asphalt membrane overlays : final report.

DOT National Transportation Integrated Search

2009-08-01

In 1976 the Federal Highway Administration (FHWA) approved federal aid funding for experimental : installations of corrosion protection for reinforcing steel in existing concrete bridge decks. Sixteen of the sixty-nine : Kansas bridges with Cost Effe...

Integration of a versatile bridge concept in a 34 GHz pulsed/CW EPR spectrometer

NASA Astrophysics Data System (ADS)

Band, Alan; Donohue, Matthew P.; Epel, Boris; Madhu, Shraeya; Szalai, Veronika A.

2018-03-01

We present a 34 GHz continuous wave (CW)/pulsed electron paramagnetic resonance (EPR) spectrometer capable of pulse-shaping that is based on a versatile microwave bridge design. The bridge radio frequency (RF)-in/RF-out design (500 MHz to 1 GHz input/output passband, 500 MHz instantaneous input/output bandwidth) creates a flexible platform with which to compare a variety of excitation and detection methods utilizing commercially available equipment external to the bridge. We use three sources of RF input to implement typical functions associated with CW and pulse EPR spectroscopic measurements. The bridge output is processed via high speed digitizer and an in-phase/quadrature (I/Q) demodulator for pulsed work or sent to a wideband, high dynamic range log detector for CW. Combining this bridge with additional commercial hardware and new acquisition and control electronics, we have designed and constructed an adaptable EPR spectrometer that builds upon previous work in the literature and is functionally comparable to other available systems.

Synthesis and structural studies of two pyridine-armed reinforced cyclen chelators and their transition metal complexes.

PubMed

Wilson, Kevin R; Cannon-Smith, Desiray J; Burke, Benjamin P; Birdsong, Orry C; Archibald, Stephen J; Hubin, Timothy J

2016-08-16

Two novel pyridine pendant-armed macrocycles structurally reinforced by an ethyl bridge, either between adjacent nitrogens (for side-bridged) or non-adjacent nitrogens (for cross-bridged), have been synthesized and complexed with a range of transition metal ions (Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ ). X-ray crystal structures of selected cross-bridged complexes were obtained which showed the characteristic cis-V configuration with potential labile cis binding sites. The complexes have been characterized by their electronic spectra and magnetic moments, which show the expected high spin divalent metal complex in most cases. Exceptions are the nickel side-bridged complex, which shows a mixture of high-spin and low spin, and the cobalt cross-bridged complex which has oxidized to cobalt(III). Cyclic voltammetry in acetonitrile was carried out to assess the potential future use of these complexes in oxidation catalysis. Selected complexes offer significant catalytic potential enhanced by the addition of the pyridyl arm to a reinforced cyclen backbone.

Implementation program on high performance concrete: guidelines for instrumentation on bridges

DOT National Transportation Integrated Search

1996-08-01

This report provides an outline for the instrumentation of bridges being constructed under the Federal Highway Administration's (FHWA's) Strategic Highway Research Program (SHRP) implementation effort in High Performance Concrete (HPC). The report de...

Self-Consolidating Concrete for Prestressed Bridge Girders : Research Brief

DOT National Transportation Integrated Search

2017-08-01

Self-consolidating concrete (SCC) is commonly used as an alternative to conventional concrete (CC) in precast, prestressed concrete (PSC) bridge girders. The high strength, highly workable mixture can flow through dense reinforcement to fill formwork...

Seismic Performance of Self-Consolidating Concrete Bridge Columns

DOT National Transportation Integrated Search

2017-09-01

The high amount of confining lateral steel required by seismic design provisions for rectangular bridge columns can cause steel congestion. The high amount of confining steel may hinder the placement of conventional concrete (CC). Self-consolidating ...

Semiconductor bridge (SCB) detonator

DOEpatents

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.

Contemporary Parenteral Antiplatelet Bridging Strategies: A Single-Center Real-World Experience at a Tertiary Care Center.

PubMed

Stern, Gretchen; Rimsans, Jessica; Qamar, Arman; Vaduganathan, Muthiah; Bhatt, Deepak L

2018-03-13

Oral antiplatelet therapy may require interruption soon after percutaneous coronary intervention (PCI) or acute coronary syndrome. The optimal parenteral antiplatelet bridge strategy with glycoprotein IIb/IIIa inhibitors or cangrelor, a P2Y12 inhibitor, is unclear. We explore real-world use of cangrelor or eptifibatide for antiplatelet bridging at a large tertiary-care center. Thirty-one patients (9 eptifibatide, 20 cangrelor, and 2 both) received bridge therapy from October 2015 to June 2017. Primary bridge therapy indications included surgery (68%), limited enteral access/absorption (16%), and high-perceived bleed risk (16%). Median duration of bridge therapy was 61 (20-100) hours for cangrelor and 83 (19-98) hours for eptifibatide. Severe/life-threatening bleeding or stent thrombosis was not observed. GUSTO-defined bleeding occurred in 30% (cangrelor) and 27% (eptifibatide). Initial dosing errors occurred in 23% of patients. Death during hospitalization occurred in 16% of patients. Parenteral antiplatelet bridging was used for ~3 days in this single-center, tertiary care experience, commonly for unplanned surgery following PCI. Despite high-risk presentations with >15% in-hospital mortality, efficacy profiles were reassuring with no identified stent thrombosis, but bleeding and dosing errors were common. Antiplatelet bridging should only be used in well-selected patients at the appropriate dose for the minimal necessary duration.

Slip and creep of thermal spray coatings : [tech brief].

DOT National Transportation Integrated Search

2014-09-01

All steel bridge systems and their components need some level : of corrosion protection to assure a serviceable life. One of two : approaches is typically used: either the bridge component is : fabricated from a corrosion-resistant alloy, or the stee...

BATS IN AMERICAN BRIDGES: RESOURCE PUBLICATION NO. 4

DOT National Transportation Integrated Search

1999-01-01

Bridges and culverts were evaluated as bat roosting habitat in 25 states at elevations from sea level to 10,000 feet. Field surveys were conducted at 2,421 highway structures. Scientific literature was reviewed, and local biologists and engineers wer...

Establishment of Maximum Voluntary Compressive Neck Tolerance Levels

DTIC Science & Technology

2011-07-01

Bridges Casey Pirnstill Chris Burneka John Plaga Grant Roush Biosciences and Performance Division Vulnerability Analysis Branch July 2011...S) Michael Cote, John Buhrman, Nathaniel Bridges, Casey Pirnstill, Chris Burneka, John Plaga , Grant Roush 5d. PROJECT NUMBER OSMS 5e. TASK

Acoustic emission techniques applied to conventionally reinforced concrete bridge girders : final report.

DOT National Transportation Integrated Search

2008-09-01

Reinforced concrete (RC) bridges generally operate at service-level loads except during discrete overload events that can reduce the integrity of the structure by initiating concrete cracks, widening or extending of existing concrete cracks, as well ...

GPS for structural health monitoring - case study on the Basarab overpass cable-stayed bridge

NASA Astrophysics Data System (ADS)

Lepadatu, Alexandru; Tiberius, Christian

2014-04-01

The Basarab cable-stayed bridge is a newly built structure in Bucharest, Romania, which was inaugurated in June 2011. Before the oficial opening, in order to assure its qualification for trafic, it had to pass several loading tests with convoys of trucks and trams. For this, besides a priori evaluation using the Finite Element Method (FEM), levelling and acceleration measurements were made to identify vertical displacements, as well as vibration frequencies of the bridge. The three-day loading trial of the bridge represented a good opportunity for setting-up a GPS campaign for structural monitoring of the Basarab bridge. Taking advantage of the redundancy obtained via simultaneous multi-sensor measurements, it was possible to compare and validate the GPS estimated displacements with both FEM and levelling. Moreover, the dynamic behaviour of the bridge during a dynamic loading test was evaluated using a 20 Hz GPS observation rate and validated afterwards with vibration frequency estimates from acceleration time series. Along with simulations (FEM) and laboratory tests, the in situ monitoring of a structure has a particular importance in establishing the safety of a newly-built structure. Furthermore, in some cases permanent monitoring is needed for safety and economic reasons, especially for strategic structures such as dams and bridges. GPS technology can satisfy this request due to its real-time processing capability and thus it can be looked upon as a new and promising tool for dynamic evaluation of engineering structures. In this contribution we have also assessed the performance of GPS with regard to accuracy and false alarm probability demands for the continuous monitoring of the Basarab cable-stayed bridge.

Ergonomics of bridge employment.

PubMed

Mohamed, Mokdad

2012-01-01

In many countries of the world, retirement is mandatory at the age at which persons who hold certain jobs or offices are required by employment law to leave their employment, or retire (60 to 65 years). Typically, this is justified by the argument that certain occupations are either too dangerous or require high levels of physical skills and mental work. Every worker has to leave the workforce at that age. However, starting from the last two decades of the last century, it is observed that retirees live more years in retirement than ever before. This relatively long retirement as well as retirees' body fitness made many of them engage in new jobs which are either similar to their career jobs, or completely different from them. In this new type of employment which is called "bridge employment', the retired worker may spend more than ten years. But, to what extent these new jobs are fitted to the aged worker? Considering that experiencing any type of event increases the risk of worse health outcomes over time, bridge employment should be ergonomically designed if it is to fit the aged worker characteristics (physical, mental and affective).

Assessment of the transportation route of oversize and excessive loads in relation to the load-bearing capacity of existing bridges

NASA Astrophysics Data System (ADS)

Doležel, Jiří; Novák, Drahomír; Petrů, Jan

2017-09-01

Transportation routes of oversize and excessive loads are currently planned in relation to ensure the transit of a vehicle through critical points on the road. Critical points are level-intersection of roads, bridges etc. This article presents a comprehensive procedure to determine a reliability and a load-bearing capacity level of the existing bridges on highways and roads using the advanced methods of reliability analysis based on simulation techniques of Monte Carlo type in combination with nonlinear finite element method analysis. The safety index is considered as a main criterion of the reliability level of the existing construction structures and the index is described in current structural design standards, e.g. ISO and Eurocode. An example of a single-span slab bridge made of precast prestressed concrete girders of the 60 year current time and its load bearing capacity is set for the ultimate limit state and serviceability limit state. The structure’s design load capacity was estimated by the full probability nonlinear MKP analysis using a simulation technique Latin Hypercube Sampling (LHS). Load-bearing capacity values based on a fully probabilistic analysis are compared with the load-bearing capacity levels which were estimated by deterministic methods of a critical section of the most loaded girders.

Design, installation, and condition assessment of a concrete bridge deck constructed with ASTM A1035 CS no. 4 bars.

DOT National Transportation Integrated Search

2017-06-01

Recently developed corrosion-resistant reinforcing structural design guidelines were used to design, construct, and : assess a reinforced concrete bridge deck with high-strength ASTM A1035 CS steel bars. The bridge replacement is located : along the ...

The medial temporal lobe—conduit of parallel connectivity: a model for attention, memory, and perception

PubMed Central

Mozaffari, Brian

2014-01-01

Based on the notion that the brain is equipped with a hierarchical organization, which embodies environmental contingencies across many time scales, this paper suggests that the medial temporal lobe (MTL)—located deep in the hierarchy—serves as a bridge connecting supra- to infra—MTL levels. Bridging the upper and lower regions of the hierarchy provides a parallel architecture that optimizes information flow between upper and lower regions to aid attention, encoding, and processing of quick complex visual phenomenon. Bypassing intermediate hierarchy levels, information conveyed through the MTL “bridge” allows upper levels to make educated predictions about the prevailing context and accordingly select lower representations to increase the efficiency of predictive coding throughout the hierarchy. This selection or activation/deactivation is associated with endogenous attention. In the event that these “bridge” predictions are inaccurate, this architecture enables the rapid encoding of novel contingencies. A review of hierarchical models in relation to memory is provided along with a new theory, Medial-temporal-lobe Conduit for Parallel Connectivity (MCPC). In this scheme, consolidation is considered as a secondary process, occurring after a MTL-bridged connection, which eventually allows upper and lower levels to access each other directly. With repeated reactivations, as contingencies become consolidated, less MTL activity is predicted. Finally, MTL bridging may aid processing transient but structured perceptual events, by allowing communication between upper and lower levels without calling on intermediate levels of representation. PMID:25426036

An investigation of several aspects of LANDSAT-5 data quality. [Palmer County, Shelby, mt; White sands, NM; Great Salt Lake, UT; San Matted Bridge and Sacramento, California

NASA Technical Reports Server (NTRS)

Wrigley, R. C. (Principal Investigator)

1984-01-01

Band-to-band registration, geodetic registration, interdector noise, and the modulation transfer function (MTE) are discussed for the Palmer County; TX scene. Band combinations for several LANDSAT 4 and LANDSAT 5 scenes; the geodetic registration test for the Sacramento, CA area; periodic noise components in TM band 5; and grey level measurements by detector for Great Salt Lake (UT) dark water forescans and backscans are considered. Results of MTF analyses of the San Mateo Bridge and of TM high resolution and aerial Daedalus scanner imagery are consistent and appear to be repeatable. An oil-on-sand target was constructed on the White Sands Missile Range in New Mexico. The two-image analysis procedure used is summarized.

High-performance fiber-reinforced concrete in a bridge deck.

DOT National Transportation Integrated Search

2005-01-01

The purpose of this research was to compare the performance of high-performance fiber-reinforced concrete (FRC) with that of conventional concrete in a bridge deck. FRC is expected to increase toughness, provide enhanced residual strength, and minimi...

Thermal response of a highly skewed integral bridge.

DOT National Transportation Integrated Search

2012-06-01

The purpose of this study was to conduct a field evaluation of a highly skewed semi-integral bridge in order to provide : feedback regarding some of the assumptions behind the design guidelines developed by the Virginia Department of : Transportation...

Exploring the relevance of thiophene rings as bridge unit in acceptor-bridge-donor dyes on self-aggregation and performance in DSSCs.

PubMed

Zarate, Ximena; Saavedra-Torres, Mario; Rodriguez-Serrano, Angela; Gomez, Tatiana; Schott, Eduardo

2018-04-30

The possibility of dye charge recombination in DSSCs remains a challenge for the field. This consists of: (a) back-transfer from the TiO 2 to the oxidized dye and (b) intermolecular electron transfer between dyes. The latter is attributed to dye aggregation due to dimeric conformations. This leads to poor electron injection which decreases the photocurrent conversion efficiency. Most organic sensitizers are characterized by an Acceptor-Bridge-Donor (A-Bridge-D) arrangement that is commonly employed to provide charge separation and, therefore, lowering the unwanted back-transfer. Here, we address the intermolecular electron transfer by studying the dimerization and photovoltaic performance of a group of A-Bridge-D structured dyes. Specifically, eight famous sulfur containing π-bridges were analyzed (A and D remained fixed). Through quantum mechanical and molecular dynamics approaches, it was found that the formation of weakly stabilized dimers is allowed. The dyes with covalently bonded and fused thiophene rings as Bridges, 6d and 7d as well as 8d with a fluorene, would present high aggregation and, therefore, high probability of recombination processes. Conversely, using TiO 2 cluster and surface models, delineated the shortest bridges to improve the adsorption energy and the stability of the system. Finally, the elongation of the bridge up to 2 and 3 units and their photovoltaic parameters were studied. These results showed that all the sensitizers are able to provide similar photocurrent outcomes, regardless of whether the bridge is elongated. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Level II scour analysis for Bridge 6 (MORRTH00030006) on Town Highway 3, crossing Ryder Brook, Morristown, Vermont

USGS Publications Warehouse

Boehmler, Erick M.; Hammond, Robert E.

1997-01-01

This report provides the results of a detailed Level II analysis of scour potential at structure MORRTH00030006 on Town Highway 3 crossing Ryder Brook, Morristown, 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 north-central Vermont. The 19.1-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover also is forested. In the study area, Ryder Brook has a straight channel with an average channel top width of 450 ft and an average bank height of 7 ft. The predominant channel bed material is silt and clay with a median grain size (D50) of 0.0719 mm (0.000236 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 18, 1996, indicated that the reach was aggraded, but the channel through the bridge was scoured. The Town Highway 3 crossing of Ryder Brook is a 72-ft-long, two-lane bridge consisting of one 70-foot steel-beam span (Vermont Agency of Transportation, written communication, January 31, 1996). The bridge is supported by vertical, concrete abutments with spill-through embankments and wingwalls. The channel is not skewed to the opening and the opening-skew-to-roadway is zero degrees. Channel scour under the bridge was evident at this site during the Level I assessment. The depth of the channel increases from 3 feet at the upstream bridge face to 10 feet at the downstream bridge face. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) on the spill-through embankments of each abutment, the upstream road embankments and the downstream left road embankment. 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, 1995). 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 20.4 to 25.8 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 8.3 to 10.5 ft. The worst-case abutment scour also 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 cross-section 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-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Bridging the Gap: Extending the Life of Marine Corps F/A-18 Hornets

DTIC Science & Technology

2011-04-28

Flight Support Team Fatigue Usage Index Full Up System Level High Flight Hours Initial Operational Capability Initial Operational Test and Evaluation...SLMP SRA STOVL TAT TMS T&R TRAP VMFAT WRA Naval Aviation Enterprise Naval Air Systems Command Naval Inventory Control Point Operational ...suggestions for reducing this burden Ia Washingl!ln Headquarters Service, Directorate for Information Operations and Reports, 1215 Jefferson Davis

High Voltage Testing. Volume 2. Specifications and Test Procedures

DTIC Science & Technology

1982-08-01

the greatest impact on the initial assumption and criteria developed in the published criteria documents include: dielectric withstanding voltage...3382-75 Measurement of Energy and Integrated Charge Transfer Due to Partial Discharges (Corona) Using Bridge Techniques. ASTM-D 3426 - Dielectric... Energy (NEMA Publication No. WC 7-1971). NEMA Publication No. 109 - AIEE-EEI-NEMA Standard Basic Insulation Level. 092-57 - Method of Test for Flash and

Synthesis of falsework, formwork and scaffolding for highway bridge structures

DOT National Transportation Integrated Search

1994-08-01

Following the collapse of the Route 198 bridge over the Baltimore-Washington Parkway in 1989, the FHWA determined that there was a need to reassess, on a national level, the specifications currently used to design, construct, and inspect falsework an...

Calibration of LRFR live load factors using weigh-in-motion data.

DOT National Transportation Integrated Search

2006-06-01

The Load and Resistance Factor Rating (LRFR) code for load rating bridges is based on factors calibrated from structural : load and resistance statistics to achieve a more uniform level of reliability for all bridges. The liveload factors in the : LR...

Summer Bridge Programs. What Works Clearinghouse Intervention Report

ERIC Educational Resources Information Center

What Works Clearinghouse, 2016

2016-01-01

"Summer bridge programs" are designed to ease the transition to college and support postsecondary success by providing students with the academic skills and social resources needed to succeed in a college environment. These programs occur in the summer "bridge" period between high school and college. Although the content of…

Wind Tunnel Measurements for Flutter of a Long-Afterbody Bridge Deck

PubMed Central

Chen, Zeng-Shun; Zhang, Cheng; Wang, Xu; Ma, Cun-Ming

2017-01-01

Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao Bridge, as an example to investigate the flutter of the bridge deck. Firstly, aerodynamic force models for flutter of bridges were introduced. Then, wind tunnel tests of the bridge deck during the construction and the operation stages, under different wind attack angles and wind velocities, were carried out using a high frequency base balance (HFBB) system and laser displacement sensors. From the tests, the static aerodynamic forces and flutter derivatives of the bridge deck were observed. Correspondingly, the critical flutter wind speeds of the bridge deck were determined based on the derivatives, and they are compared with the directly measured flutter speeds. Results show that the observed derivatives are reasonable and applicable. Furthermore, the critical wind speeds in the operation stage is smaller than those in the construction stage. Besides, the flutter instabilities of the bridge in the construction and the operation stages are good. This study helps guarantee the design and the construction of the Jianghai Channel Bridge, and advances the understanding of flutter of long afterbody bridge decks. PMID:28208773

Wind Tunnel Measurements for Flutter of a Long-Afterbody Bridge Deck.

PubMed

Chen, Zeng-Shun; Zhang, Cheng; Wang, Xu; Ma, Cun-Ming

2017-02-09

Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao Bridge, as an example to investigate the flutter of the bridge deck. Firstly, aerodynamic force models for flutter of bridges were introduced. Then, wind tunnel tests of the bridge deck during the construction and the operation stages, under different wind attack angles and wind velocities, were carried out using a high frequency base balance (HFBB) system and laser displacement sensors. From the tests, the static aerodynamic forces and flutter derivatives of the bridge deck were observed. Correspondingly, the critical flutter wind speeds of the bridge deck were determined based on the derivatives, and they are compared with the directly measured flutter speeds. Results show that the observed derivatives are reasonable and applicable. Furthermore, the critical wind speeds in the operation stage is smaller than those in the construction stage. Besides, the flutter instabilities of the bridge in the construction and the operation stages are good. This study helps guarantee the design and the construction of the Jianghai Channel Bridge, and advances the understanding of flutter of long afterbody bridge decks.

No Bridge Too High: Infants Decide Whether to Cross Based on the Probability of Falling not the Severity of the Potential Fall

ERIC Educational Resources Information Center

Kretch, Kari S.; Adolph, Karen E.

2013-01-01

Do infants, like adults, consider both the probability of falling and the severity of a potential fall when deciding whether to cross a bridge? Crawling and walking infants were encouraged to cross bridges varying in width over a small drop-off, a large drop-off, or no drop-off. Bridge width affects the probability of falling, whereas drop-off…

Development of an intelligent hydroinformatic system for real-time monitoring and assessment of civil infrastructure

NASA Astrophysics Data System (ADS)

Cahill, Paul; Michalis, Panagiotis; Solman, Hrvoje; Kerin, Igor; Bekic, Damir; Pakrashi, Vikram; McKeogh, Eamon

2017-04-01

With the effects of climate change becoming more apparent, extreme weather events are now occurring with greater frequency throughout the world. Such extreme events have resulted in increased high intensity flood events which are having devastating consequences on hydro-structures, especially on bridge infrastructure. The remote and often inaccessible nature of such bridges makes inspections problematic, a major concern if safety assessments are required during and after extreme flood events. A solution to this is the introduction of smart, low cost sensing solutions at locations susceptible to hydro-hazards. Such solutions can provide real-time information on the health of the bridge and its environments, with such information aiding in the mitigation of the risks associated with extreme weather events. This study presents the development of an intelligent system for remote, real-time monitoring of hydro-hazards to bridge infrastructure. The solution consists of two types of remote monitoring stations which have the capacity to monitor environmental conditions and provide real-time information to a centralized, big data database solution, from which an intelligent decision support system will accommodate the results to control and manage bridge, river and catchment assets. The first device developed as part of the system is the Weather Information Logging Device (WILD), which monitors rainfall, temperature and air and soil moisture content. The ability of the WILD to monitor rainfall in real time enables flood early warning alerts and predictive river flow conditions, thereby enabling decision makers the ability to make timely and effective decisions about critical infrastructures in advance of extreme flood events. The WILD is complemented by a second monitoring device, the Bridge Information Recording Device (BIRD), which monitors water levels at a given location in real-time. The monitoring of water levels of a river allows for, among other applications, hydraulic modelling to assess the likely impact that severe flood events will have on a bridges foundation, particularly due to scour. The process of reading and validating data from the WILD and BIRD buffer servers is outlined, as is the transmission protocol used for the sending of recorded data to a centralized repository for further use and analysis. Finally, the development of a centralized repository for the collection of data from the WILD and BIRD devices is presented. Eventually the big data solution would be used to receive, store and send the monitored data to the hydrological models, whether existing or developed, and the results would be transmitted to the intelligent decision support system based on a web-based platform, for managing, planning and executing data, processes and procedures for bridge assets. The development of intelligent hydroinformatic system is an important tool for the protection of key infrastructure assets from the increasingly common effects of climate change. Acknowledgement The authors wish to acknowledge the financial support of the European Commission, through the Marie Curie Industry-Academia Partnership and Pathways Network BRIDGE SMS (Intelligent Bridge Assessment Maintenance and Management System) - FP7-People-2013-IAPP- 612517.

Monitoring steel bridge renovation using lead isotopic tracing.

PubMed

Salome, Fred; Gulson, Brian; Chiaradia, Massimo; Davis, Jeffrey; Morris, Howard

2017-05-01

Monitoring removal of lead (Pb) paint from steel structures usually involves analysis of environmental samples for total lead and determination of blood Pb levels of employees involved in the Pb paint removal. We used high precision Pb isotopic tracing for a bridge undergoing Pb paint removal to determine if Pb in the environmental and blood samples originated from the bridge paint. The paint system on the bridge consisted of an anti-corrosive red Pb primer top-coated with a Micaceous Iron Oxide (MIO) alkyd. Analysis of the red Pb primer gave uniform isotopic ratios indicative of Pb from the geologically-ancient Broken Hill mines in western New South Wales, Australia. Likewise waste abrasive material, as anticipated, had the same isotopic composition as the paint. The isotopic ratios for other samples lay on 2 separate linear arrays on a 207 Pb/ 204 Pb versus 206 Pb/ 204 Pb diagram, one largely defined by gasoline and the majority of the ambient air data, and the other by data for one sample each of gasoline and ambient air and underwater sediments. Isotopic ratios in background ambient air samples for the project were characteristic of leaded gasoline. Air sampling during paint removal showed a contribution of paint Pb ranging from about 20 to 40%. Isotopic ratios in the blood of 8 employees prior to the commencement of work showed that 6 of these had been previously exposed to the Broken Hill Pb possibly from earlier bridge paint removal projects. One subject appeared to have increased exposure to Pb probably from the paint renovations. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

USGS Publications Warehouse

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 to provide quality-assurance/quality-control measures for the level-1.5 scour estimates. An attempt was made to use the same flows among replicate analyses. Scour estimates do not necessarily have to be in numerical agreement to give the same results. For example, if contraction scour replicate analyses are 18.8 and 30.8 feet, both scour depths can indicate susceptibility to scour for which countermeasures may be needed, even though one number is much greater than the other number. Contraction scour has perhaps the greatest potential for being estimated differently in replicate visits. For contraction scour estimates at the various flows analyzed, differences between results ranged from -7.8 to 5.5 feet, with a median difference of 0.4 foot and an average difference of 0.2 foot. Abutment scour appeared to be nearly as reproducible as contraction scour. For abutment scour estimates at the varying flows analyzed, differences between results ranged from -17.4 to 11 feet, with a median difference of 1.4 feet and an average difference of 1.7 feet. Estimates of pier scour tended to be the most consistently reproduced in replicate visits, with differences between results ranging from -0.3 to 0.5 foot, with a median difference of 0.0 foot and an average difference of 0.0 foot. The U.S. Army Corps of Engineers Hydraulics Engineering Center River Analysis Systems (HEC-RAS) software package was used to model stream hydraulics at the 41 sites with level-2 analyses. Level-1.5 analyses also were completed at these sites, and the performance of the level-1.5 method was assessed by comparing results to those from the more rigorous level-2 method. The envelope curve approach used in the level-1.5 method is designed to overestimate scour relative to the estimate from the level-2 scour analysis. In cases where the level-1.5 method estimated less scour than the level-2 method, the amount of underestimation generally was less than 3 feet. The level-1.5 method generally overestimated contraction, abutment, and pier scour relative to the level-2 method, as intended. Although the level-1.5 method is designed to overestimate scour relative to more involved analysis methods, many assumptions, uncertainties, and estimations are involved. If the envelope curves are adjusted such that the level-1.5 method never underestimates scour relative to the level-2 method, an accompanying result may be excessive overestimation.

A Bridge Too Far - Revisited: Reframing Bruer's Neuroeducation Argument for Modern Science of Learning Practitioners.

PubMed

Horvath, Jared C; Donoghue, Gregory M

2016-01-01

In Education and the Brain: A Bridge Too Far, John Bruer argues that, although current neuroscientific findings must filter through cognitive psychology in order to be applicable to the classroom, with increased knowledge the neuroscience/education bridge can someday be built. Here, we suggest that translation cannot be understood as a single process: rather, we demonstrate that at least four different 'bridges' can conceivably be built between these two fields. Following this, we demonstrate that, far from being a matter of information lack, a prescriptive neuroscience/education bridge (the one most relevant to Bruer's argument) is a practical and philosophical impossibility due to incommensurability between non-adjacent compositional levels-of-organization: a limitation inherent in all sciences. After defining this concept in the context of biology, we apply this concept to the learning sciences and demonstrate why all brain research must be behaviorally translated before prescriptive educational applicability can be elucidated. We conclude by exploring examples of how explicating different forms of translation and adopting a levels-of-organization framework can be used to contextualize and beneficially guide research and practice across all learning sciences.

Pathway-based discovery of genetic interactions in breast cancer

PubMed Central

Xu, Zack Z.; Boone, Charles; Lange, Carol A.

2017-01-01

Breast cancer is the second largest cause of cancer death among U.S. women and the leading cause of cancer death among women worldwide. Genome-wide association studies (GWAS) have identified several genetic variants associated with susceptibility to breast cancer, but these still explain less than half of the estimated genetic contribution to the disease. Combinations of variants (i.e. genetic interactions) may play an important role in breast cancer susceptibility. However, due to a lack of statistical power, the current tests for genetic interactions from GWAS data mainly leverage prior knowledge to focus on small sets of genes or SNPs that are known to have an association with breast cancer. Thus, many genetic interactions, particularly among novel variants, remain understudied. Reverse-genetic interaction screens in model organisms have shown that genetic interactions frequently cluster into highly structured motifs, where members of the same pathway share similar patterns of genetic interactions. Based on this key observation, we recently developed a method called BridGE to search for such structured motifs in genetic networks derived from GWAS studies and identify pathway-level genetic interactions in human populations. We applied BridGE to six independent breast cancer cohorts and identified significant pathway-level interactions in five cohorts. Joint analysis across all five cohorts revealed a high confidence consensus set of genetic interactions with support in multiple cohorts. The discovered interactions implicated the glutathione conjugation, vitamin D receptor, purine metabolism, mitotic prometaphase, and steroid hormone biosynthesis pathways as major modifiers of breast cancer risk. Notably, while many of the pathways identified by BridGE show clear relevance to breast cancer, variants in these pathways had not been previously discovered by traditional single variant association tests, or single pathway enrichment analysis that does not consider SNP-SNP interactions. PMID:28957314

A Conversion of Wheatstone Bridge to Current-Loop Signal Conditioning for Strain Gages

NASA Technical Reports Server (NTRS)

Anderson, Karl F.

1995-01-01

Current loop circuitry replaced Wheatstone bridge circuitry to signal-condition strain gage transducers in more than 350 data channels for two different test programs at NASA Dryden Flight Research Center. The uncorrected test data from current loop circuitry had a lower noise level than data from comparable Wheatstone bridge circuitry, were linear with respect to gage-resistance change, and were uninfluenced by varying lead-wire resistance. The current loop channels were easier for the technicians to set up, verify, and operate than equivalent Wheatstone bridge channels. Design choices and circuit details are presented in this paper in addition to operational experience.

Acoustic Emission Monitoring for Assessment of Steel Bridge Details

NASA Astrophysics Data System (ADS)

Kosnik, D. E.; Hopwood, T.; Corr, D. J.

2011-06-01

Acoustic emission (AE) testing was deployed on details of two large steel Interstate Highway bridges: one cantilever through-truss and one trapezoidal box girder bridge. Quantitative measurements of activity levels at known and suspected crack locations were made by monitoring AE under normal service loads (e.g., live traffic and wind). AE indications were used to direct application of radiography, resulting in identification of a previously unknown flaw, and to inform selection of a retrofit detail.

Evaluation of a Summer Bridge: Critical Component of the Leadership 2.0 Program.

PubMed

Pritchard, Tracy J; Perazzo, Joseph D; Holt, Julie A; Fishback, Benjamin P; McLaughlin, Michaela; Bankston, Karen D; Glazer, Greer

2016-04-01

Summer bridges facilitate the transition from high school to college. Although many schools employ summer bridges, few have published outcomes. This article's purpose is to share preconceptions of college by underrepresented and disadvantaged nursing students and describe important elements and long-term impact of a summer bridge, a component of the Leadership 2.0 program. A longitudinal study design was used to collect baseline, short-term, and long-term post-summer bridge data. Methods included pre- and postsurveys, interviews, and focus groups. After bridge completion, students felt more prepared for the nursing program. Students ranked socialization components as most important. The summer bridge had lasting impact through the first year, where grade point average and retention of underrepresented and disadvantaged bridge students was comparable to the majority first-year students. The summer bridge was effective in preparing nursing students for the first year of college. Through holistic evaluation, unique aspects of socialization critical to student success were uncovered. Copyright 2016, SLACK Incorporated.

Proof of concept for using unmanned aerial vehicles for high mast pole and bridge inspections.

DOT National Transportation Integrated Search

2015-06-01

Bridges and high mast luminaires (HMLs) are key components of transportation infrastructures. Effective inspection : processes are crucial to maintain the structural integrity of these components. The most common approach for : inspections is visual ...

Implementation of high performance concrete in Louisiana bridges : interim report.

DOT National Transportation Integrated Search

1998-02-01

The report contains a research plan to assist in the implementation of high performance concrete in the Charenton Canal Bridge in Louisiana. The research involves a literature review, plan review, development of a quality control program for the conc...

Brief communication: Preoperative anticoagulant activity after bridging low-molecular-weight heparin for temporary interruption of warfarin.

PubMed

O'Donnell, Martin J; Kearon, Clive; Johnson, Judy; Robinson, Marlene; Zondag, Michelle; Turpie, Irene; Turpie, Alexander G

2007-02-06

Preoperative low-molecular-weight heparin (LMWH) is often used when warfarin therapy is interrupted for surgery. To determine the preoperative anticoagulant activity of LMWH following a standardized "bridging" regimen. Prospective cohort study. Single university hospital. Consecutive patients who had warfarin therapy interrupted before an invasive procedure. Enoxaparin, 1 mg/kg of body weight, twice daily. The last dose was administered the evening before surgery. Blood anti-factor Xa heparin levels measured shortly before surgery. Preoperative anti-Xa heparin levels were obtained in 80 patients at an average of 14 hours after the last dose of enoxaparin was administered. The average anti-Xa heparin level was 0.6 U/mL. The anti-Xa heparin level, measured shortly before surgery, was 0.5 U/mL or greater in 54 (68%) patients and 1.0 U/mL or greater in 13 (16%) patients. A shorter interval since the last dose (P < 0.001) and a higher body mass index (P = 0.001) were associated with higher preoperative anti-Xa heparin levels. The small sample size limits accurate estimates of the frequency of the clinical outcomes. A single regimen of LMWH was evaluated. Anti-Xa heparin levels often remain high at the time of surgery if a last dose of a twice-daily regimen of LMWH is given the evening before surgery.

Bridge Therapy Outcomes in Patients With Mechanical Heart Valves.

PubMed

Delate, Thomas; Meisinger, Stephanie M; Witt, Daniel M; Jenkins, Daniel; Douketis, James D; Clark, Nathan P

2017-11-01

Bridge therapy is associated with an increased risk of major bleeding in patients with atrial fibrillation and venous thromboembolism (TE) without a corresponding reduction in TE. The benefits of bridge therapy in patients with mechanical heart valve (MHV) prostheses interrupting warfarin for invasive procedures are not well described. A retrospective cohort study was conducted at an integrated health-care delivery system. Anticoagulated patients with MHV interrupting warfarin for invasive diagnostic or surgical procedures between January 1, 2006, and March 31, 2012, were identified. Patients were categorized according to exposure to bridge therapy during the periprocedural period and TE risk (low, medium, and high). Outcomes validated via manual chart review included clinically relevant bleeding, TE, and all-cause mortality in the 30 days following the procedure. There were 547 procedures in 355 patients meeting inclusion criteria. Mean cohort age was 65.2 years, and 38% were female. Bridge therapy was utilized in 466 (85.2%) procedures (95.2%, 77.3%, and 65.8% of high, medium, and low TE risk category procedures, respectively). The 30-day rate of clinically relevant bleeding was numerically higher in bridged (5.8%; 95% confidence interval [CI], 3.9%-8.3%) versus not bridged procedures (1.2%; 95% CI, <0.1%-6.7%; P = .102). No TEs or deaths were identified. The use of bridge therapy is common among patients with MHV and may be associated with increased bleeding risk. Further research is needed to determine whether bridge therapy reduces TE in patients with MHV interrupting warfarin for invasive procedures.

Sequential big endothelin plasma levels in heart transplant recipients during bridging therapy and after successful heart transplantation.

PubMed

Strametz-Juranek, Jeanette; Pacher, Richard; Kos, Thomas; Woloszczuk, Wolfgang; Grimm, Michael; Zuckermann, Andreas; Stanek, Brigitte

2003-07-01

The purpose of this study was to investigate the impact of successful heart transplantation in patients with refractory heart failure receiving bridging therapy on sequential plasma levels of big endothelin, norepinephrine, atrial natriuretic peptide and aldosterone. Fourteen patients (2 women, 12 men) accepted for heart transplantation were studied. All had severe chronic heart failure refractory to optimized oral therapy with angiotensin-converting enzyme inhibitors and furosemide, were in New York Heart Association functional Class IV, and had a left ventricular ejection fraction of <15%, Right heart catheterization was performed in all patients (cardiac index 1.9 +/- 0.1 liters/min. m(2), pulmonary capillary wedge pressure 30 +/- 2 mmHg, systemic vascular resistance index 2,827 +/- 253 dyn. s/cm(5). m(2)). As bridging therapy, patients received either prostaglandin E(1), prostaglandin E(1) and dobutamine or dobutamine alone as a continuous infusion. Neurohumoral variables were measured prior to bridging therapy and 3.5 months before and 7 and 10 months after successful heart transplantation. Big endothelin, norepinephrine and atrial natriuretic peptide plasma levels decreased from 7.4 +/- 2.9 fmol/ml, 1112 +/- 686 pg/ml and 366 +/- 312 pg/ml to 6.0 +/- 4.5 fmol/ml, 720 +/- 503 pg/ml and 198 +/- 160 pg/ml, respectively, after bridging therapy, and further to 2.1 +/- 0.9 fmol/ml (p < 0.00001 vs baseline), 527 +/- 31 pg/ml (p < 0.02 vs baseline) and 115 +/- 70 pg/ml (p < 0.03 vs baseline), respectively, after cardiac transplantation. Aldosterone plasma levels decreased from 242 +/- 220 pg/ml to 183 +/- 142 pg/ml during bridging therapy and increased after heart transplantation to 252 +/- 189 pg/ml. Plasma creatinine levels increased from 1.2 +/- 0.4 mg/dl at baseline to 1.4 +/- 0.2 mg/dl after transplantation (NS). The study suggests that excessive overproduction of big endothelin, atrial natriuretic peptide and norepinephrine is predominantly related to pump failure and, after cardiac transplantation, a moderate spillover of big endothelin persists. Its specific origin, however, remains to be elucidated. Furthermore, our data suggest a protective effect of prostaglandin E(1) on kidney function after heart transplantation.

Sky-blue emitting bridged diiridium complexes: beneficial effects of intramolecular π-π stacking.

PubMed

Congrave, Daniel G; Hsu, Yu-Ting; Batsanov, Andrei S; Beeby, Andrew; Bryce, Martin R

2018-02-06

The potential of intramolecular π-π interactions to influence the photophysical properties of diiridium complexes is an unexplored topic, and provides the motivation for the present study. A series of diarylhydrazide-bridged diiridium complexes functionalised with phenylpyridine (ppy)-based cyclometalating ligands is reported. It is shown by NMR studies in solution and single crystal X-ray analysis that intramolecular π-π interactions between the bridging and cyclometalating ligands rigidify the complexes leading to high luminescence quantum efficiencies in solution and in doped films. Fluorine substituents on the phenyl rings of the bridge promote the intramolecular π-π interactions. Notably, these non-covalent interactions are harnessed in the rational design and synthesis of the first examples of highly emissive sky-blue diiridium complexes featuring conjugated bridging ligands, for which they play a vital role in the structural and photophysical properties. Experimental results are supported by computational studies.

Long-term Cerec 3D chairside bridges milled from IPS e.max CAD LT blocks.

PubMed

Schneider, Oliver

The experienced Cerec user can manufacture high-quality, esthetic anterior and posterior bridges from IPS e.max CAD in a manageable 3-hour chairside session. On the basis of over 8 years of experience, it can be said that these restorations are clinically very well proven, provided they are used within the range of recommended indications. Experimental retainer bridges with extensions can be seen as highly interesting alternatives, although more clinical data are required for further confirmation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, T.J.; Nowlen, S.P.; Anderson, D.J.

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 environmentalmore » 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.« less

BRIDG: a domain information model for translational and clinical protocol-driven research.

PubMed

Becnel, Lauren B; Hastak, Smita; Ver Hoef, Wendy; Milius, Robert P; Slack, MaryAnn; Wold, Diane; Glickman, Michael L; Brodsky, Boris; Jaffe, Charles; Kush, Rebecca; Helton, Edward

2017-09-01

It is critical to integrate and analyze data from biological, translational, and clinical studies with data from health systems; however, electronic artifacts are stored in thousands of disparate systems that are often unable to readily exchange data. To facilitate meaningful data exchange, a model that presents a common understanding of biomedical research concepts and their relationships with health care semantics is required. The Biomedical Research Integrated Domain Group (BRIDG) domain information model fulfills this need. Software systems created from BRIDG have shared meaning "baked in," enabling interoperability among disparate systems. For nearly 10 years, the Clinical Data Standards Interchange Consortium, the National Cancer Institute, the US Food and Drug Administration, and Health Level 7 International have been key stakeholders in developing BRIDG. BRIDG is an open-source Unified Modeling Language-class model developed through use cases and harmonization with other models. With its 4+ releases, BRIDG includes clinical and now translational research concepts in its Common, Protocol Representation, Study Conduct, Adverse Events, Regulatory, Statistical Analysis, Experiment, Biospecimen, and Molecular Biology subdomains. The model is a Clinical Data Standards Interchange Consortium, Health Level 7 International, and International Standards Organization standard that has been utilized in national and international standards-based software development projects. It will continue to mature and evolve in the areas of clinical imaging, pathology, ontology, and vocabulary support. BRIDG 4.1.1 and prior releases are freely available at https://bridgmodel.nci.nih.gov . © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Level II scour analysis for Bridge 34 (CORITH0050034) on Town Highway 50, crossing the South Branch Waits River, Corinth, Vermont

USGS Publications Warehouse

Ivanoff, Michael A.

1997-01-01

This report provides the results of a detailed Level II analysis of scour potential at structure CORITH00500034 on Town Highway 50 crossing the South Branch Waits River, Corinth, 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 35.9-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 the immediate banks have dense woody vegetation. In the study area, the South Branch Waits River has an incised, meandering channel with a slope of approximately 0.005 ft/ft, an average channel top width of 63 ft and an average bank height of 6 ft. The channel bed material ranges from sand to cobble with a median grain size (D50) of 23.7 mm (0.078 ft). The geomorphic assessment at the time of the Level I and Level II site visit on September 5, 1995, indicated that the reach was stable. The Town Highway 50 crossing of the South Branch Waits River is a 56-ft-long, one-lane bridge consisting of one 54-foot steel thru-truss span (Vermont Agency of Transportation, written communication, March 24, 1995). The opening length of the structure parallel to the bridge face is 51.5 ft.The bridge is supported by vertical, concrete abutments with no wingwalls. Stone fill and bank material in front of the abutments create spill-through embankments. The channel is skewed approximately 30 degrees to the opening while the opening-skew-to-roadway is 15 degrees. A scour hole 2.5 ft deeper than the mean thalweg depth was observed along the left bank through the bridge during the Level I assessment. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) along the left and right banks extending from upstream to downstream through the bridge. The stone fill under the bridge creates spill-through embankments. 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 was determined and analyzed as other potential 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 0.0 to 3.0 ft. The worst-case contraction scour occurred at the incipient roadway-overtopping discharge, which was less than the 100-year discharge. Abutment scour ranged from 2.4 to 6.3 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 cross-section 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-size distribution. It is generally accepted that the Froehlich and HIRE equations (abutment scour) give “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Semiconductor bridge (SCB) detonator

DOEpatents

Bickes, R.W. Jr.; Grubelich, M.C.

1999-01-19

The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge (SCB) 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. 3 figs.

Development and validation of deterioration models for concrete bridge decks - phase 2 : mechanics-based degradation models.

DOT National Transportation Integrated Search

2013-06-01

This report summarizes a research project aimed at developing degradation models for bridge decks in the state of Michigan based on durability mechanics. A probabilistic framework to implement local-level mechanistic-based models for predicting the c...

Load capacity of hollowed timber piles.

DOT National Transportation Integrated Search

1998-12-01

The goal of this study was to develop a reliable load-rating methodology for timber piles based on the level of documented damage. Louisiana currently has over 4,000 timber bridges in its inventory of over 13,800 bridges. A quarter of these 4,000 tim...

33 CFR 165.811 - Atchafalaya River, Berwick Bay, LA-regulated navigation area.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Bridge. (c) When the Morgan City River gauge reads 3.0 feet or above mean sea level, in addition to the... apply to a towing vessel which will navigate: (1) under the lift span of the SPRR Bridge; or (2) through...

33 CFR 165.811 - Atchafalaya River, Berwick Bay, LA-regulated navigation area.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Bridge. (c) When the Morgan City River gauge reads 3.0 feet or above mean sea level, in addition to the... apply to a towing vessel which will navigate: (1) under the lift span of the SPRR Bridge; or (2) through...

33 CFR 165.811 - Atchafalaya River, Berwick Bay, LA-regulated navigation area.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Bridge. (c) When the Morgan City River gauge reads 3.0 feet or above mean sea level, in addition to the... apply to a towing vessel which will navigate: (1) under the lift span of the SPRR Bridge; or (2) through...

33 CFR 165.811 - Atchafalaya River, Berwick Bay, LA-regulated navigation area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Bridge. (c) When the Morgan City River gauge reads 3.0 feet or above mean sea level, in addition to the... apply to a towing vessel which will navigate: (1) under the lift span of the SPRR Bridge; or (2) through...

Underwater acoustic noise generation and propagation resulting from pile driving for Oregon bridge construction.

DOT National Transportation Integrated Search

2014-06-01

There is growing concern about noise levels from pile driving activities associated with the : construction of highway bridges and other in-water structures. It has been demonstrated that noise : generated from pile driving with an impact hammer can ...

Natural canopy bridges effectively mitigate tropical forest fragmentation for arboreal mammals.

PubMed

Gregory, Tremaine; Carrasco-Rueda, Farah; Alonso, Alfonso; Kolowski, Joseph; Deichmann, Jessica L

2017-06-20

Linear infrastructure development and resulting habitat fragmentation are expanding in Neotropical forests, and arboreal mammals may be disproportionately impacted by these linear habitat clearings. Maintaining canopy connectivity through preservation of connecting branches (i.e. natural canopy bridges) may help mitigate that impact. Using camera traps, we evaluated crossing rates of a pipeline right-of-way in a control area with no bridges and in a test area where 13 bridges were left by the pipeline construction company. Monitoring all canopy crossing points for a year (7,102 canopy camera nights), we confirmed bridge use by 25 mammal species from 12 families. With bridge use beginning immediately after exposure and increasing over time, use rates were over two orders of magnitude higher than on the ground. We also found a positive relationship between a bridge's use rate and the number of species that used it, suggesting well-used bridges benefit multiple species. Data suggest bridge use may be related to a combination of bridge branch connectivity, multiple connections, connectivity to adjacent forest, and foliage cover. Given the high use rate and minimal cost, we recommend all linear infrastructure projects in forests with arboreal mammal populations include canopy bridges.

Use and selection of bridges as day roosts by Rafinesque's Big Eared Bats.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, Frances, M.; Loeb, Susan, C.; Bunch, Mary, S.

ABSTRACT.—Rafinesque’s big-eared bats (Corynorhinus rafinesquii) use bridges as day roosts in parts of their range, but information on bridge use across their range is lacking. From May to Aug. 2002 we surveyed 1129 bridges (12.5%) within all 46 counties of South Carolina to determine use and selection of bridges as day roosts by big-eared bats and to document their distribution across the state. During summer 2003, we visited 235 bridges in previously occupied areas of the state to evaluate short-term fidelity to bridge roosts. We found colonies and solitary big-eared bats beneath 38 bridges in 2002 and 54 bridges inmore » 2003. Construction type and size of bridges strongly influenced use in both years; bats selected large, concrete girder bridges and avoided flat-bottomed slab bridges. The majority of occupied bridges (94.7%) were in the Upper and Lower Coastal Plains, but a few bridges (5.3%) were located in the Piedmont. Rafinesque’s big-eared bats were absent beneath bridges in the Blue Ridge Mountains. We established new records of occurrence for 10 counties. In the Coastal Plains, big-eared bats exhibited a high degree of short-term fidelity to roosts in highway bridges. For bridges that were occupied at least once, mean frequency of use was 65.9%. Probability of finding bats under a bridge ranged from 0.46 to 0.73 depending on whether the bridge was occupied in the previous year. Thus, bridges should be inspected three to five times in a given year to determine whether they are being used. Regional bridge roost surveys may be a good method for determining the distribution of C. rafinesquii, particularly in the Coastal Plains, and protection of suitable bridges may be a viable conservation strategy where natural roost sites are limited.« less

Shear test of high performance steel hybrid girders.

DOT National Transportation Integrated Search

2005-06-01

High performance steel (HPS) has been used in hundreds of bridges in the United States. A large percentage of these bridges have used HPS in the form of hybrid girder design. One limit with hybrid girder design, which decreases the beneficial aspects...

Design and evaluation of a single-span bridge using ultra-high performance concrete.

DOT National Transportation Integrated Search

2009-09-01

"Research presented herein describes an application of a newly developed material called Ultra-High Performance Concrete (UHPC) to a : single-span bridge. The two primary objectives of this research were to develop a shear design procedure for possib...

Design and evaluation of a single-span bridge using ultra-high performance concrete.

DOT National Transportation Integrated Search

2009-09-01

Research presented herein describes an application of a newly developed material called Ultra-High Performance Concrete (UHPC) to a : single-span bridge. The two primary objectives of this research were to develop a shear design procedure for possibl...

Quality assurance testing of a high performance steel bridge in Virginia.

DOT National Transportation Integrated Search

2005-01-01

One of the original objectives of this study was to recommend appropriate procedures for welding bridge members of high performance steel HPS70W to assure quality welds. The final objective was to determine whether hydrogen-induced microcracking migh...

Test plan : Branson TRIP travel time/data accuracy

DOT National Transportation Integrated Search

2000-04-01

In the mid 1990's the FHWA established a High Performance Concrete (HPC) program aimed at demonstrating the positive effects of utilizing HPC in bridges. Research on the benefits of using high performance concrete for bridges has shown a number of be...

Geomorphology and river dynamics of the lower Copper River, Alaska

USGS Publications Warehouse

Brabets, Timothy P.; Conaway, Jeffrey S.

2009-01-01

Located in south-central Alaska, the Copper River drains an area of more than 24,000 square miles. The average annual flow of the river near its mouth is 63,600 cubic feet per second, but is highly variable between winter and summer. In the winter, flow averages approximately 11,700 cubic feet per second, and in the summer, due to snowmelt, rainfall, and glacial melt, flow averages approximately 113,000 cubic feet per second, an order of magnitude higher. About 15 miles upstream of its mouth, the Copper River flows past the face of Childs Glacier and enters a large, broad, delta. The Copper River Highway traverses this flood plain, and in 2008, 11 bridges were located along this section of the highway. The bridges cross several parts of the Copper River and in recent years, the changing course of the river has seriously damaged some of the bridges.Analysis of aerial photography from 1991, 1996, 2002, 2006, and 2007 indicates the eastward migration of a channel of the Copper River that has resulted in damage to the Copper River Highway near Mile 43.5. Migration of another channel in the flood plain has resulted in damage to the approach of Bridge 339. As a verification of channel change, flow measurements were made at bridges along the Copper River Highway in 2005–07. Analysis of the flow measurements indicate that the total flow of the Copper River has shifted from approximately 50 percent passing through the bridges at Mile 27, near the western edge of the flood plain, and 50 percent passing through the bridges at Mile 36–37 to approximately 5 percent passing through the bridges at Mile 27 and 95 percent through the bridges at Mile 36–37 during average flow periods.The U.S. Geological Survey’s Multi-Dimensional Surface-Water Modeling System was used to simulate water-surface elevation and velocity, and to compute bed shear stress at two areas where the Copper River is affecting the Copper River Highway. After calibration, the model was used to examine the effects that betterments, such as guide banks or bridge extensions, would have on flow conditions and to provide sound conceptual information that could help decide if a proposed betterment will work or determine potential problems that need to be addressed for a particular betterment. The ability of the model to simulate these hydraulic conditions was constrained by the accuracy and level of channel geometry detail, which is constantly changing in the lower Copper River.

Reconfigurable wireless monitoring systems for bridges: validation on the Yeondae Bridge

NASA Astrophysics Data System (ADS)

Kim, Junhee; Lynch, Jerome P.; Zonta, Daniele; Lee, Jong-Jae; Yun, Chung-Bang

2009-03-01

The installation of a structural monitoring system on a medium- to large-span bridge can be a challenging undertaking due to high system costs and time consuming installations. However, these historical challenges can be eliminated by using wireless sensors as the primary building block of a structural monitoring system. Wireless sensors are low-cost data acquisition nodes that utilize wireless communication to transfer data from the sensor to the data repository. Another advantageous characteristic of wireless sensors is their ability to be easily removed and reinstalled in another sensor location on the same structure; this installation modularity is highlighted in this study. Wireless sensor nodes designed for structural monitoring applications are installed on the 180 m long Yeondae Bridge (Korea) to measure the dynamic response of the bridge to controlled truck loading. To attain a high nodal density with a small number (20) of wireless sensors, the wireless sensor network is installed three times with each installation concentrating sensors in one portion of the bridge. Using forced and free vibration response data from the three installations, the modal properties of the bridge are accurately identified. Intentional nodal overlapping of the three different sensor installations allows mode shapes from each installation to be stitched together into global mode shapes. Specifically, modal properties of the Yeondae Bridge are derived off-line using frequency domain decomposition (FDD) modal analysis methods.

Cognitive Bridging: Using Strategic Communication To Connect Abstract Goals With The Means To Achieve Them.

PubMed

Katz, Sherri Jean; Byrne, Sahara

2018-01-29

Three studies test several mechanisms of cognitive bridging, or how a strategic communication message functions to connect the abstract goal of an individual with the specific means to achieve the goal. Across all of the experiments (n = 276, n = 209, n = 145), it was demonstrated that participants who received an induced bridging mechanism were more likely to produce cognitive bridging outputs and report more abstract responses than participants who did not receive a bridging technique. We do not find the same pattern of results among participants who received an integrated bridging technique. Taken together, these studies provide evidence that how abstractly or concretely an individual is thinking can be influenced by abstraction cues planted within a strategic message, providing promise for messaging efforts at the moment of decision. In other words, the level of abstract thinking an individual is carrying into an exposure situation is possible to change using cues within the message itself. This is the first article to juxtapose the induced and integrated mechanisms of cognitive bridging.

Research on Damage Identification of Bridge Based on Digital Image Measurement

NASA Astrophysics Data System (ADS)

Liang, Yingjing; Huan, Shi; Tao, Weijun

2017-12-01

In recent years, the number of the damage bridge due to excessive deformation gradually increased, which caused significant property damage and casualties. Hence health monitoring and the damage detection of the bridge structure based on the deflection measurement are particularly important. The current conventional deflection measurement methods, such as total station, connected pipe, GPS, etc., have many shortcomings as low efficiency, heavy workload, low degree of automation, operating frequency and working time constrained. GPS has a low accuracy in the vertical displacement measurement and cannot meet the dynamic measured requirements of the current bridge engineering. This paper presents a bridge health monitoring and damage detection technology based on digital image measurement method in which the measurement accuracy is sub-millimeter level and can achieve the 24-hour automatic non-destructive monitoring for the deflection. It can be concluded from this paper that it is feasible to use digital image measurement method for identification of the damage in the bridge structure, because it has been validated by the theoretical analysis, the laboratory model and the application of the real bridge.

Crevasse detection with GPR across the Ross Ice Shelf, Antarctica

NASA Astrophysics Data System (ADS)

Delaney, A.; Arcone, S.

2005-12-01

We have used 400-MHz ground penetrating radar (GPR) to detect crevasses within a shear zone on the Ross Ice Shelf, Antarctica, to support traverse operations. The transducer was attached to a 6.5-m boom and pushed ahead of an enclosed tracked vehicle. Profile speeds of 4.8-11.3 km / hr allowed real-time crevasse image display and a quick, safe stop when required. Thirty-two crevasses were located with radar along the 4.8 km crossing. Generally, crevasse radar images were characterized by dipping reflections above the voids, high-amplitude reflections originating from ice layers at the base of the snow-bridges, and slanting, diffracting reflections from near-vertical crevasse walls. New cracks and narrow crevasses (<50 cm width) show no distinct snow bridge structure, few diffractions, and a distinct band where pulse reflections are absent. Wide (0.5-5.0 m), vertical wall crevasses show distinct dipping snow bridge layering and intense diffractions from ice layers near the base of the snow bridge. Pulse reflections are absent from voids beneath the snow bridges. Old, wide (3.0-8.0 m) and complexly shaped crevasses show well-developed, broad, dipping snow-bridge layers and a high-amplitude, complex, diffraction pattern. The crevasse mitigation process, which included hot-water drilling, destroying the bridges with dynamite, and back-filling with bulldozed snow, afforded an opportunity to ground-truth GPR interpretations by comparing void size and snow-bridge geometry with the radar images. While second and third season radar profiles collected along the identical flagged route confirmed stability of the filled crevasses, those profiles also identified several new cracks opened by ice extension. Our experiments demonstrate capability of high-frequency GPR in a cold-snow environment for both defining snow layers and locating voids.

KENNEDY SPACE CENTER, FLA. - This bird's-eye view of a high bay in the Orbiter Processing Facility (OPF) shows the open payload bay of Space Shuttle Discovery surrounded by the standard platforms and equipment required to process a Space Shuttle orbiter. The high bay is 197 feet (60 meters) long, 150 feet (46 meters) wide, 95 feet (29 meters) high, and encompasses a 29,000-square-foot (2,694-meter) area. The 30-ton (27-metric-ton) bridge crane (yellow device, right) has a hook height of approximately 66 feet (20 meters). Platforms, a main access bridge, and two rolling bridges with trucks provide access to various parts of the orbiter. In addition to routine servicing and checkout, the inspections and modifications made to enhance Discovery's performance and upgrade its systems were performed in the OPF during its recently completed Orbiter Major Modification (OMM) period.

NASA Image and Video Library

2003-09-02

KENNEDY SPACE CENTER, FLA. - This bird's-eye view of a high bay in the Orbiter Processing Facility (OPF) shows the open payload bay of Space Shuttle Discovery surrounded by the standard platforms and equipment required to process a Space Shuttle orbiter. The high bay is 197 feet (60 meters) long, 150 feet (46 meters) wide, 95 feet (29 meters) high, and encompasses a 29,000-square-foot (2,694-meter) area. The 30-ton (27-metric-ton) bridge crane (yellow device, right) has a hook height of approximately 66 feet (20 meters). Platforms, a main access bridge, and two rolling bridges with trucks provide access to various parts of the orbiter. In addition to routine servicing and checkout, the inspections and modifications made to enhance Discovery's performance and upgrade its systems were performed in the OPF during its recently completed Orbiter Major Modification (OMM) period.

Development of wave and surge atlas for the design and protection of coastal bridges in south Louisiana : [tech summary].

DOT National Transportation Integrated Search

2015-02-01

The failures of highway bridges on the Gulf Coast seen in the aftermath of Hurricane Katrina in 2005 were unprecedented. : In the past four decades, wind waves accompanied by high surges from hurricanes have damaged a number of coastal : bridges alon...

75 FR 54771 - Drawbridge Operation Regulation; Trent River, New Bern, NC

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-09

... New Bern, NC, to accommodate a Bridge Run. This deviation allows the drawbridge to be maintained in... approximately 14 feet above mean high water. On behalf of the Neuse River Bridge Run Organization and the City... Bridge Run schedule for Saturday, October 16, 2010. Under this deviation, the drawbridge would be allowed...

Group involvement and self-rated health among the Japanese elderly: an examination of bonding and bridging social capital

PubMed Central

2013-01-01

Background To date, only a small amount of research on bonding/bridging social capital has separately examined their effects on health though they have been thought to have differential effects on health outcomes. By using a large population-based sample of elderly Japanese people, we sought to investigate the association between bonding and bridging social capital and self-rated health for men and women separately. Methods In August 2010, questionnaires were sent to all residents aged ≥65 years in three municipalities in Okayama prefecture (n = 21232), and 13929 questionnaires were returned (response rate: 65.6%). Social capital was measured from survey responses to questions on participation in six different types of groups: a) the elderly club or sports/hobby/culture circle; b) alumni association; c) political campaign club; d) citizen’s group or environmental preservation activity; e) community association; and f) religious organization. Participant perception of group homogeneity (gender, age, and previous occupation) was used to divide social capital into bonding or bridging. Odds ratios (ORs) and 95% confidence intervals (CIs) for poor self-rated health were calculated. Results A total of 11146 subjects (4441 men and 6705 women) were available for the analysis. Among men, bonding and bridging social capital were inversely associated with poor self-rated health (high bonding social capital; OR: 0.55, 95% CI: 0.31–0.99; high bridging social capital; OR: 0.62, 95% CI: 0.48–0.81) after adjusting for age, educational attainment, smoking status, frequency of alcohol consumption, overweight, living arrangements, and type-D personality. The beneficial effect among women was more likely limited to bonding social capital (high bonding social capital; OR: 0.34, 95% CI: 0.12–1.00), and the association between bridging social capital and self-rated health was less clear (high bridging social capital; OR: 0.69, 95% CI: 0.44–1.07). Conclusions Bonding/bridging social capital could have differential associations with self-rated health among the Japanese elderly depending on the individual’s sex. Considering the lack of consensus on how to measure bonding and bridging social capital, however, we need to carefully assess the generalizability of our findings. Further research is warranted to identify health-relevant dimensions of social capital in different cultural or economic settings. PMID:24341568

Integration of a versatile bridge concept in a 34 GHz pulsed/CW EPR spectrometer.

PubMed

Band, Alan; Donohue, Matthew P; Epel, Boris; Madhu, Shraeya; Szalai, Veronika A

2018-03-01

We present a 34 GHz continuous wave (CW)/pulsed electron paramagnetic resonance (EPR) spectrometer capable of pulse-shaping that is based on a versatile microwave bridge design. The bridge radio frequency (RF)-in/RF-out design (500 MHz to 1 GHz input/output passband, 500 MHz instantaneous input/output bandwidth) creates a flexible platform with which to compare a variety of excitation and detection methods utilizing commercially available equipment external to the bridge. We use three sources of RF input to implement typical functions associated with CW and pulse EPR spectroscopic measurements. The bridge output is processed via high speed digitizer and an in-phase/quadrature (I/Q) demodulator for pulsed work or sent to a wideband, high dynamic range log detector for CW. Combining this bridge with additional commercial hardware and new acquisition and control electronics, we have designed and constructed an adaptable EPR spectrometer that builds upon previous work in the literature and is functionally comparable to other available systems. Published by Elsevier Inc.

The effects of anisotropy on the nonlinear behavior of bridged cracks in long strips

NASA Technical Reports Server (NTRS)

Ballarini, R.; Luo, H. A.

1994-01-01

A model which can be used to predict the two-dimensional nonlinear behavior of bridged cracks in orthotropic strips is presented. The results obtained using a singular integral equation formulation which incorporates the anisotropy rigorously show that, although the effects of anisotropy are significant, the nondimensional quantities employed by Cox and Marshall can generate nearly universal results (R-curves, for example) for different levels of relative anisotropy. The role of composite constituent properties in the behavior of bridged cracks is clarified.

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

USGS Publications Warehouse

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 the mean thalweg depth was observed along the downstream left retaining wall (extended concrete footing) during the Level I assessment. It was also observed that the right abutment is undermined with a scour depth of 0.5 ft. The scour protection at the site was limited to four large boulders (type-4, less than 60 inches diameter) along the downstream right retaining wall. The channel under the bridge is a “corduroy” log mat floor composed of 13 logs which are parallel to the bridge face and extend from 5 ft under the bridge to the downstream bridge face. The most downstream log is approximately 0.3 to 0.4 ft higher than the other logs and controls flow at lower flows. 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). 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 0.3 to 0.6 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 14.1 to 16.0 ft at the left abutment and from 6.8 to 7.6 ft at the right abutment. 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 cross-section 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-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Readiness for self-directed learning: How bridging and traditional nursing students differs?

PubMed

Alharbi, Homood A

2018-02-01

The dean of the nursing college has an initiative to reform the BSN program in the college to minimize the use of lecturing and maximize interactive and lifelong learning. Appropriate assessment of how our students are prepared to be self-directed learners is crucial. To compare traditional and bridging students in regard to their SDLR scores in the nursing college in Saudi Arabia. This was a comparative study to compare traditional and bridging students in regard to their self-directed learning readiness scores (SDLR). The data was collected at the Nursing College, King Saud University, Riyadh, Saudi Arabia. A convenient sample of undergraduate nursing students at the sixth and eighth levels in both regular and bridging programs were recruited in this study to indicate their SDLR scores. The study used Fisher et al.'s (2001) Self-Directed Learning Readiness Scale to measure the self-directed learning readiness among undergraduate nursing students. The total mean score of SDLR was 144 out of 200, which indicated a low level of readiness for SDL. There were significant variations between the included academic levels among participants. Students in the sixth academic level scored higher in the total SDLR scores compared to eighth-level students. There were no significant variations with gender and program types in the total SDLR scores. A comprehensive plan is needed to prepare both faculty members and students to improve the SDL skills. Copyright © 2017 Elsevier Ltd. All rights reserved.

Element level bridge inspection : benefits and use of data for bridge management.

DOT National Transportation Integrated Search

2016-02-01

In 2012, Congress passed the Moving Ahead for Progress in the 21st Century Act (MAP-21) and committed to the development of a datadriven, : risk based approach to asset management in the United States. This law requires the collection and submission ...

SMART PEBBLES : passive embeddable wireless sensors for chloride ingress monitoring in bridge decks.

DOT National Transportation Integrated Search

2003-06-01

SRI International has developed a wireless sensor for monitoring the level of chloride : ingress into concrete bridge decks. We call this device a Smart Pebble since it has : roughly the size and weight of a typical piece of the rock aggregate tha...

Bridge maintenance to enhance corrosion resistance and performance of steel girder bridges

NASA Astrophysics Data System (ADS)

Moran Yanez, Luis M.

The integrity and efficiency of any national highway system relies on the condition of the various components. Bridges are fundamental elements of a highway system, representing an important investment and a strategic link that facilitates the transport of persons and goods. The cost to rehabilitate or replace a highway bridge represents an important expenditure to the owner, who needs to evaluate the correct time to assume that cost. Among the several factors that affect the condition of steel highway bridges, corrosion is identified as the main problem. In the USA corrosion is the primary cause of structurally deficient steel bridges. The benefit of regular high-pressure superstructure washing and spot painting were evaluated as effective maintenance activities to reduce the corrosion process. The effectiveness of steel girder washing was assessed by developing models of corrosion deterioration of composite steel girders and analyzing steel coupons at the laboratory under atmospheric corrosion for two alternatives: when high-pressure washing was performed and when washing was not considered. The effectiveness of spot painting was assessed by analyzing the corrosion on steel coupons, with small damages, unprotected and protected by spot painting. A parametric analysis of corroded steel girder bridges was considered. The emphasis was focused on the parametric analyses of corroded steel girder bridges under two alternatives: (a) when steel bridge girder washing is performed according to a particular frequency, and (b) when no bridge washing is performed to the girders. The reduction of structural capacity was observed for both alternatives along the structure service life, estimated at 100 years. An economic analysis, using the Life-Cycle Cost Analysis method, demonstrated that it is more cost-effective to perform steel girder washing as a scheduled maintenance activity in contrast to the no washing alternative.

Local-based damage detection of cyclically loaded bridge piers using wireless sensing units

NASA Astrophysics Data System (ADS)

Hou, Tsung-Chin; Lynch, Jerome P.; Parra-Montesinos, Gustavo

2005-05-01

Concrete bridge piers are a common structural element employed in the design of bridges and elevated roadways. In order to ensure adequate behavior under earthquake-induced displacements, extensive reinforcement detailing in the form of closely spaced ties or spirals is necessary, leading to congestion problems and difficulties during concrete casting. Further, costly repairs are often necessary in bridge piers after a major earthquake which in some cases involve the total or partial shutdown of the bridge. In order to increase the damage tolerance while relaxing the transverse reinforcement requirements of bridge piers, the use of high-performance fiber reinforced cementitious composites (HPFRCC) in earthquake-resistant bridge piers is explored. HPFRCCs are a relatively new class of cementitious material for civil structures with tensile strain-hardening behavior and high damage tolerance. To monitor the behavior of this new class of material in the field, low-cost wireless monitoring technologies will be adopted to provide HPFRCC structural elements the capability to accurately monitor their performance and health. In particular, the computational core of a wireless sensing unit can be harnessed to screen HPFRCC components for damage in real-time. A seismic damage index initially proposed for flexure dominated reinforced concrete elements is modified to serve as an algorithmic tool for the rapid assessment of damage (due to flexure and shear) in HPFRCC bridge piers subjected to large shear reversals. Traditional and non-traditional sensor strategies of an HPFRCC bridge pier are proposed to optimize the correlation between the proposed damage index model and the damage observed in a circular pier test specimen. Damage index models are shown to be a sufficiently accurate rough measure of the degree of local-area damage that can then be wirelessly communicated to bridge officials.

Analysis of shielded CPW discontinuities with air-bridges

NASA Technical Reports Server (NTRS)

Dib, N. I.; Katehi, P. B.; Ponchak, George E.

1992-01-01

The effect of air-bridges on the performance of various coplanar waveguides (CPW) discontinuities is studied. Specifically, the coupled open-end CPW's and the short-end shunt CPW stub discontinuities are considered. The high frequency effect of the air-bridge is evaluated using a hybrid technique. At first, the frequency dependent equivalent circuit of the planar discontinuity without the air-bridge is derived using the Space Domain Integral Equation (SDIE) method. Then, the circuit is modified by incorporating the air-bridge's parasitic inductance and capacitance which are evaluated using a simple quasi-static model. The frequency response of each discontinuity with and without the air-bridge is studied and the scattering parameters are plotted in the frequency range 30-50 GHz for typical CPW dimensions.

High Strength Reinforcing Steel Bars : Concrete Shear Friction Interface : final report : Part A.

DOT National Transportation Integrated Search

2017-03-01

High-strength steel (HSS) reinforcement, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) steel reinf...

High strength reinforcing steel bars : concrete shear friction interface : final report : Part A.

DOT National Transportation Integrated Search

2017-03-01

High-strength steel (HSS) reinforcement, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) steel reinf...

First bridge structure with lightweight high-performance concrete beams and deck in Virginia.

DOT National Transportation Integrated Search

2005-01-01

This study involved the construction and early performance of the first bridge in Virginia constructed with lightweight high-performance concrete (LWHPC) having a density of 120 lb/ft3 in the beams and deck. The design strength and permeability were ...

High strength reinforcing steel bars : low cycle fatigue behavior : final report - part B.

DOT National Transportation Integrated Search

2017-03-01

High-strength steel (HSS) reinforcing steel, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) reinfor...

Feasibility evaluation of utilizing high-strength concrete in design and construction of highway bridge structures.

DOT National Transportation Integrated Search

1994-01-01

The objective of this investigation was to evaluate the feasibility of using high-strength concrete in the design and construction of highway bridge structures. A literature search was conducted; a survey of five regional fabrication plants was perfo...

High strength reinforcing steel bars : low-cycle fatigue behavior : final report - part B.

DOT National Transportation Integrated Search

2017-03-01

High-strength steel (HSS) reinforcing steel, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) reinfor...

TOMML: A Rule Language for Structured Data

NASA Astrophysics Data System (ADS)

Cirstea, Horatiu; Moreau, Pierre-Etienne; Reilles, Antoine

We present the TOM language that extends JAVA with the purpose of providing high level constructs inspired by the rewriting community. TOM bridges thus the gap between a general purpose language and high level specifications based on rewriting. This approach was motivated by the promotion of rule based techniques and their integration in large scale applications. Powerful matching capabilities along with a rich strategy language are among TOM's strong features that make it easy to use and competitive with respect to other rule based languages. TOM is thus a natural choice for querying and transforming structured data and in particular XML documents [1]. We present here its main XML oriented features and illustrate its use on several examples.

A Liver-centric Multiscale Modeling Framework for Xenobiotics ...

EPA Pesticide Factsheets

We describe a multi-scale framework for modeling acetaminophen-induced liver toxicity. Acetaminophen is a widely used analgesic. Overdose of acetaminophen can result in liver injury via its biotransformation into toxic product, which further induce massive necrosis. Our study focuses on developing a multi-scale computational model to characterize both phase I and phase II metabolism of acetaminophen, by bridging Physiologically Based Pharmacokinetic (PBPK) modeling at the whole body level, cell movement and blood flow at the tissue level and cell signaling and drug metabolism at the sub-cellular level. To validate the model, we estimated our model parameters by fi?tting serum concentrations of acetaminophen and its glucuronide and sulfate metabolites to experiments, and carried out sensitivity analysis on 35 parameters selected from three modules. Our study focuses on developing a multi-scale computational model to characterize both phase I and phase II metabolism of acetaminophen, by bridging Physiologically Based Pharmacokinetic (PBPK) modeling at the whole body level, cell movement and blood flow at the tissue level and cell signaling and drug metabolism at the sub-cellular level. This multiscale model bridges the CompuCell3D tool used by the Virtual Tissue project with the httk tool developed by the Rapid Exposure and Dosimetry project.

Ultra-high performance fiber-reinforced concrete (UHPFRC) for infrastructure rehabilitation Volume II : behavior of ultra-high strength concrete bridge deck panels compared to conventional stay-in-place deck panels

DOT National Transportation Integrated Search

2017-08-01

The remarkable features of ultra-high performance concrete (UHPC) have been reported. Its application in bridge construction has been an active research area in recent years, attributed to its higher compressive strength, higher ductility and reduced...

21. VIEW OF MIANUS RIVER RAILROAD BRIDGE LOOKING NORTHEAST FROM ...

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

21. VIEW OF MIANUS RIVER RAILROAD BRIDGE LOOKING NORTHEAST FROM THE REMAINS OF THE COS COB POWER PLANT COALING DOCK. THE BRIDGE IS A ROLLING LIFT BASCULE TYPE BUILT IN 1894-1895. NOTE THE ABSENCE OF CATENARY OVER THE CHANNEL AND THE METHOD OF CARRYING POWER FEED OVER THE RIVER ON THE HIGH TOWERS ADJACENT TO THE LIFT SECTION OF THE BRIDGE. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

Studies of Biosilicification; The Role of Proteins, Carbohydrates and Model Compounds in Structure Control

DTIC Science & Technology

2005-12-31

No. carbons Pore volume data. Resolution of complex monosaccharide mixtures from plant cell wall isolates by high pH anion exchange chromatography. To...interwoven polysaccharide chains embedded in a gel matrix of galacturonic acid rich polysaccharides connected by calcium bridges. This network also...picomolar levels). Also, it allows the determination of intact monosaccharides without pre or post column derivatisation, decreasing the time of

The role of salt bridges on the temperature adaptation of aqualysin I, a thermostable subtilisin-like proteinase.

PubMed

Jónsdóttir, Lilja B; Ellertsson, Brynjar Ö; Invernizzi, Gaetano; Magnúsdóttir, Manuela; Thorbjarnardóttir, Sigríður H; Papaleo, Elena; Kristjánsson, Magnús M

2014-12-01

Differences in salt bridges are believed to be a structural hallmark of homologous enzymes from differently temperature-adapted organisms. Nevertheless, the role of salt bridges on structural stability is still controversial. While it is clear that most buried salt bridges can have a functional or structural role, the same cannot be firmly stated for ion pairs that are exposed on the protein surface. Salt bridges, found in X-ray structures, may not be stably formed in solution as a result of high flexibility or high desolvation penalty. More studies are thus needed to clarify the picture on salt bridges and temperature adaptation. We contribute here to this scenario by combining atomistic simulations and experimental mutagenesis of eight mutant variants of aqualysin I, a thermophilic subtilisin-like proteinase, in which the residues involved in salt bridges and not conserved in a psychrophilic homolog were systematically mutated. We evaluated the effects of those mutations on thermal stability and on the kinetic parameters. Overall, we show here that only few key charged residues involved in salt bridges really contribute to the enzyme thermal stability. This is especially true when they are organized in networks, as here attested by the D17N mutation, which has the most remarkable effect on stability. Other mutations had smaller effects on the properties of the enzyme indicating that most of the isolated salt bridges are not a distinctive trait related to the enhanced thermal stability of the thermophilic subtilase. Copyright © 2014 Elsevier B.V. All rights reserved.

Anticoagulation Bridge Therapy in Patients with Atrial Fibrillation: Recent Updates Providing a Rebalance of Risk and Benefit.

PubMed

Garwood, Candice L; Korkis, Bianca; Grande, Domenico; Hanni, Claudia; Morin, Amy; Moser, Lynette R

2017-06-01

In 2011 we reviewed clinical updates and controversies surrounding anticoagulation bridge therapy in patients with atrial fibrillation (AF). Since then, options for oral anticoagulation have expanded with the addition of four direct oral anticoagulant (DOAC) agents available in the United States. Nonetheless, vitamin K antagonist (VKA) therapy continues to be the treatment of choice for patients who are poor candidates for a DOAC and for whom bridge therapy remains a therapeutic dilemma. This literature review identifies evidence and guideline and consensus statements from the last 5 years to provide updated recommendations and insight into bridge therapy for patients using a VKA for AF. Since our last review, at least four major international guidelines have been updated plus a new consensus document addressing bridge therapy was released. Prospective trials and one randomized controlled trial have provided guidance for perioperative bridge therapy. The clinical trial data showed that bridging with heparin is associated with a significant bleeding risk compared with not bridging; furthermore, data suggested that actual perioperative thromboembolic risk may be lower than previously estimated. Notably, patients at high risk for stroke have not been adequately represented. These findings highlight the importance of assessing thrombosis and bleeding risk before making bridging decisions. Thrombosis and bleeding risk tools have emerged to facilitate this assessment and have been incorporated into guideline recommendations. Results from ongoing trials are expected to provide more guidance on safe and effective perioperative management approaches for patients at high risk for stroke. © 2017 Pharmacotherapy Publications, Inc.

Enhancing the Thermal Resistance of a Novel Acidobacteria-Derived Phytase by Engineering of Disulfide Bridges.

PubMed

Tan, Hao; Miao, Renyun; Liu, Tianhai; Cao, Xuelian; Wu, Xiang; Xie, Liyuan; Huang, Zhongqian; Peng, Weihong; Gan, Bingcheng

2016-10-28

A novel phytase of Acidobacteria was identified from a soil metagenome, cloned, overexpressed, and purified. It has low sequence similarity (<44%) to all the known phytases. At the optimum pH (2.5), the phytase shows an activity level of 1,792 μmol/min/mg at physiological temperature (37°C) and could retain 92% residual activity after 30 min, indicating the phytase is acidophilic and acidostable. However the phytase shows poor stability at high temperatures. To improve its thermal resistance, the enzyme was redesigned using Disulfide by Design 2.0, introducing four additional disulfide bridges. The half-life time of the engineered phytase at 60°C and 80°C, respectively, is 3.0× and 2.8× longer than the wild-type, and its activity and acidostability are not significantly affected.

Feasibility evaluation of utilizing high strength concrete in design and construction of highway bridge structures : interim report.

DOT National Transportation Integrated Search

1992-12-01

The objective of this investigation was to evaluate the feasibility of using high-strength concrete in the design and construction of highway bridge structures. A literature search was conducted; a survey of five regional fabrication plants was perfo...

78 FR 17747 - Agency Information Collection Activities: Request for Comments for a New Information Collection.

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-22

... define the types of analyses to be used to evaluate benefits, cost-effectiveness and feasibility...: Feasibility of Element-Level Bridge Inspection for Non- National Highway System Bridges. Background: The... a requirement for a study on the benefits, cost-effectiveness, and feasibility of requiring element...

MASH TL-3 testing and evaluation of the TXDOT T131RC bridge rail transition.

DOT National Transportation Integrated Search

2013-03-01

This project designed and crash tested a transition design for the Texas Department of Transportation (TxDOT) T131RC Bridge Rail that would meet the strength and safety performance criteria for Test Level 3 of American Association of State Highway Of...

Progression into Engineering. Building Bridges between Education, Training and Employment.

ERIC Educational Resources Information Center

Evans, Karen; And Others

This publication reports findings of a 12-month study of progression opportunities in engineering education and training, a study which explored ways of bridging the gap between skills and knowledge acquired through basic training and prevocational education and those required for progression to higher levels of occupational training and…

Modal Parameter Identification and Numerical Simulation for Self-anchored Suspension Bridges Based on Ambient Vibration

NASA Astrophysics Data System (ADS)

Liu, Bing; Sun, Li Guo

2018-06-01

This paper chooses the Nanjing-Hangzhou high speed overbridge, a self-anchored suspension bridge, as the research target, trying to identify the dynamic characteristic parameters of the bridge by using the peak-picking method to analyze the velocity response data under ambient excitation collected by 7 vibration pickup sensors set on the bridge deck. The ABAQUS is used to set up a three-dimensional finite element model for the full bridge and amends the finite element model of the suspension bridge based on the identified modal parameter, and suspender force picked by the PDV100 laser vibrometer. The study shows that the modal parameter can well be identified by analyzing the bridge vibration velocity collected by 7 survey points. The identified modal parameter and measured suspender force can be used as the basis of the amendment of the finite element model of the suspension bridge. The amended model can truthfully reflect the structural physical features and it can also be the benchmark model for the long-term health monitoring and condition assessment of the bridge.

Software user's guide for determining the Pennsylvania scour critical indicator code and streambed scour assessment rating for roadway bridges

USGS Publications Warehouse

Henneberg, M.F.; Strause, J.L.

2002-01-01

This report presents the instructions required to use the Scour Critical Bridge Indicator (SCBI) Code and Scour Assessment Rating (SAR) calculator developed by the Pennsylvania Department of Transportation (PennDOT) and the U.S. Geological Survey to identify Pennsylvania bridges with excessive scour conditions or a high potential for scour. Use of the calculator will enable PennDOT bridge personnel to quickly calculate these scour indices if site conditions change, new bridges are constructed, or new information needs to be included. Both indices are calculated for a bridge simultaneously because they must be used together to be interpreted accurately. The SCBI Code and SAR calculator program is run by a World Wide Web browser from a remote computer. The user can 1) add additional scenarios for bridges in the SCBI Code and SAR calculator database or 2) enter data for new bridges and run the program to calculate the SCBI Code and calculate the SAR. The calculator program allows the user to print the results and to save multiple scenarios for a bridge.

Medium Bandgap Conjugated Polymer for High Performance Polymer Solar Cells Exceeding 9% Power Conversion Efficiency.

PubMed

Jung, Jae Woong; Liu, Feng; Russell, Thomas P; Jo, Won Ho

2015-12-02

Two medium-bandgap polymers composed of benzo[1,2-b:4,5-b']dithiohpene and 2,1,3-benzothiadiazole with 6-octyl-thieno[3,2-b]thiophene as a π-bridge unit are synthesized and their photovoltaic properties are analyzed. The two polymers have deep highest occupied molecular orbital energy levels, high crystallinity, optimal bulk-heterojunction morphology, and efficient charge transport, resulting in a power conversion efficiency of as high as 9.44% for a single-junction polymer solar-cell device. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Covered Bridge Security Manual

Treesearch

Brett Phares; Terry Wipf; Ryan Sievers; Travis Hosteng

2013-01-01

The design, construction, and use of covered timber bridges is all but a lost art in these days of pre-stressed concrete, high-performance steel, and the significant growth both in the volume and size of vehicles. Furthermore, many of the existing covered timber bridges are preserved only because of their status on the National Registry of Historic Places or the...

The Case for Summer Bridge: Building Social and Cultural Capital for Talented Black STEM Students

ERIC Educational Resources Information Center

Stolle-McAllister, Kathleen

2011-01-01

This study uses focus groups to examine the importance of a pre-college summer bridge program for highly talented black students in science, technology, engineering, and mathematics (STEM). Longitudinal data were collected from 134 participants who identified three aspects of Summer Bridge that were particularly helpful: academic, social, and…

Multiple Channel Bridges for Spinal Cord Injury: Cellular Characterization of Host Response

PubMed Central

Yang, Yang; Laporte, Laura De; Zelivyanskaya, Marina L.; Whittlesey, Kevin J.; Anderson, Aileen J.; Cummings, Brian J.

2009-01-01

Bridges for treatment of the injured spinal cord must stabilize the injury site to prevent secondary damage and create a permissive environment that promotes regeneration. The host response to the bridge is central to creating a permissive environment, as the cell types that respond to the injury have the potential to secrete both stimulatory and inhibitory factors. We investigated multiple channel bridges for spinal cord regeneration and correlated the bridge structure to cell infiltration and axonal elongation. Poly(lactide-co-glycolide) bridges were fabricated by a gas foaming/particulate leaching process. Channels within the bridge had diameters of 150 or 250 μm, and the main body of the bridge was highly porous with a controllable pore size. Upon implantation in a rat spinal cord hemisection site, cells infiltrated into the bridge pores and channels, with the pore size influencing the rate of infiltration. The pores had significant cell infiltration, including fibroblasts, macrophages, S-100β-positive cells, and endothelial cells. The channels of the bridge were completely infiltrated with cells, which had aligned axially, and consisted primarily of fibroblasts, S-100β-positive cells, and endothelial cells. Reactive astrocytes were observed primarily outside of the bridge, and staining for chondroitin sulfate proteoglycans was decreased in the region surrounding the bridge relative to studies without bridges. Neurofilament staining revealed a preferential growth of the neural fibers within the bridge channels relative to the pores. Multiple channel bridges capable of supporting cellular infiltration, creating a permissive environment, and directing the growth of neural fibers have potential for promoting and directing spinal cord regeneration. PMID:19382871

A data management infrastructure for bridge monitoring

NASA Astrophysics Data System (ADS)

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.

Determination Method of Bridge Rotation Angle Response Using MEMS IMU.

PubMed

Sekiya, Hidehiko; Kinomoto, Takeshi; Miki, Chitoshi

2016-11-09

To implement steel bridge maintenance, especially that related to fatigue damage, it is important to monitor bridge deformations under traffic conditions. Bridges deform and rotate differently under traffic load conditions because their structures differ in terms of length and flexibility. Such monitoring enables the identification of the cause of stress concentrations that cause fatigue damage and the proposal of appropriate countermeasures. However, although bridge deformation monitoring requires observations of bridge angle response as well as the bridge displacement response, measuring the rotation angle response of a bridge subject to traffic loads is difficult. Theoretically, the rotation angle response can be calculated by integrating the angular velocity, but for field measurements of actual in-service bridges, estimating the necessary boundary conditions would be difficult due to traffic-induced vibration. To solve the problem, this paper proposes a method for determining the rotation angle response of an in-service bridge from its angular velocity, as measured by a inertial measurement unit (IMU). To verify our proposed method, field measurements were conducted using nine micro-electrical mechanical systems (MEMS) IMUs and two contact displacement gauges. The results showed that our proposed method provided high accuracy when compared to the reference responses calculated by the contact displacement gauges.

Cane Creek flood-flow characteristics at State Route 30 near Spencer, Tennessee

USGS Publications Warehouse

Gamble, Charles R.

1983-01-01

The Tennessee Department of Transportation has constructed a new bridge and approaches on State Route 30 over Cane Creek near Spencer, Tennessee. The old bridge and its approaches were fairly low, permitting considerable flow over the road during high floods. The new bridge and its approaches are considerably higher, causing different flow conditions at the site. Analysis of the effects of the new bridge, as compared to the old bridge, on floods of the magnitude of the May 27, 1973, flood is presented. The May 27, 1973, flood was greater than a 100-year flood. Analysis of the 50- and 100-year floods for the new bridge are also presented. Results of the study indicate that the new construction will increase the water-surface elevation for a flood equal to the May 27, 1973, flood by approximately 1 foot upstream from bridge. (USGS)

Free energy landscape of a minimalist salt bridge model.

PubMed

Li, Xubin; Lv, Chao; Corbett, Karen M; Zheng, Lianqing; Wu, Dongsheng; Yang, Wei

2016-01-01

Salt bridges are essential to protein stability and dynamics. Despite the importance, there has been scarce of detailed discussion on how salt bridge partners interact with each other in distinct solvent exposed environments. In this study, employing a recent generalized orthogonal space tempering (gOST) method, we enabled efficient molecular dynamics simulation of repetitive breaking and reforming of salt bridge structures within a minimalist salt-bridge model, the Asp-Arg dipeptide and thereby were able to map its detailed free energy landscape in aqueous solution. Free energy surface analysis shows that although individually-solvated states are more favorable, salt-bridge states still occupy a noticeable portion of the overall population. Notably, the competing forces, e.g. intercharge attractions that drive the formation of salt bridges and solvation forces that pull the charged groups away from each other, are energetically comparable. As the result, the salt bridge stability is highly tunable by local environments; for instance when local water molecules are perturbed to interact more strongly with each other, the population of the salt-bridge states is likely to increase. Our results reveal the critical role of local solvent structures in modulating salt-bridge partner interactions and imply the importance of water fluctuations on conformational dynamics that involves solvent accessible salt bridge formations. © 2015 The Protein Society.

Regional Greenland accumulation variability from Operation IceBridge airborne accumulation radar

NASA Astrophysics Data System (ADS)

Lewis, Gabriel; Osterberg, Erich; Hawley, Robert; Whitmore, Brian; Marshall, Hans Peter; Box, Jason

2017-03-01

The mass balance of the Greenland Ice Sheet (GrIS) in a warming climate is of critical interest to scientists and the general public in the context of future sea-level rise. An improved understanding of temporal and spatial variability of snow accumulation will reduce uncertainties in GrIS mass balance models and improve projections of Greenland's contribution to sea-level rise, currently estimated at 0.089 ± 0.03 m by 2100. Here we analyze 25 NASA Operation IceBridge accumulation radar flights totaling > 17 700 km from 2013 to 2014 to determine snow accumulation in the GrIS dry snow and percolation zones over the past 100-300 years. IceBridge accumulation rates are calculated and used to validate accumulation rates from three regional climate models. Averaged over all 25 flights, the RMS difference between the models and IceBridge accumulation is between 0.023 ± 0.019 and 0.043 ± 0.029 m w.e. a-1, although each model shows significantly larger differences from IceBridge accumulation on a regional basis. In the southeast region, for example, the Modèle Atmosphérique Régional (MARv3.5.2) overestimates by an average of 20.89 ± 6.75 % across the drainage basin. Our results indicate that these regional differences between model and IceBridge accumulation are large enough to significantly alter GrIS surface mass balance estimates. Empirical orthogonal function analysis suggests that the first two principal components account for 33 and 19 % of the variance, and correlate with the Atlantic Multidecadal Oscillation (AMO) and wintertime North Atlantic Oscillation (NAO), respectively. Regions that disagree strongest with climate models are those in which we have the fewest IceBridge data points, requiring additional in situ measurements to verify model uncertainties.

On the utilization of hydrological modelling for road drainage design under climate and land use change.

PubMed

Kalantari, Zahra; Briel, Annemarie; Lyon, Steve W; Olofsson, Bo; Folkeson, Lennart

2014-03-15

Road drainage structures are often designed using methods that do not consider process-based representations of a landscape's hydrological response. This may create inadequately sized structures as coupled land cover and climate changes can lead to an amplified hydrological response. This study aims to quantify potential increases of runoff in response to future extreme rain events in a 61 km(2) catchment (40% forested) in southwest Sweden using a physically-based hydrological modelling approach. We simulate peak discharge and water level (stage) at two types of pipe bridges and one culvert, both of which are commonly used at Swedish road/stream intersections, under combined forest clear-cutting and future climate scenarios for 2050 and 2100. The frequency of changes in peak flow and water level varies with time (seasonality) and storm size. These changes indicate that the magnitude of peak flow and the runoff response are highly correlated to season rather than storm size. In all scenarios considered, the dimensions of the current culvert are insufficient to handle the increase in water level estimated using a physically-based modelling approach. It also appears that the water level at the pipe bridges changes differently depending on the size and timing of the storm events. The findings of the present study and the approach put forward should be considered when planning investigations on and maintenance for areas at risk of high water flows. In addition, the research highlights the utility of physically-based hydrological models to identify the appropriateness of road drainage structure dimensioning. Copyright © 2014 Elsevier B.V. All rights reserved.

Design optimization of high frequency transformer with controlled leakage inductance for current fed dual active bridge converter

NASA Astrophysics Data System (ADS)

Jung, Tae-Uk; Kim, Myung-Hwan; Yoo, Jin-Hyung

2018-05-01

Current fed dual active bridge converters for photovoltaic generation may typically require a given leakage or extra inductance in order to provide proper control of the currents. Therefore, the many researches have been focused on the leakage inductance control of high frequency transformer to integrate an extra inductor. In this paper, an asymmetric winding arrangement to get the controlled leakage inductance for the high frequency transformer is proposed to improve the efficiency of the current fed dual active bridge converter. In order to accurate analysis, a coupled electromagnetic analysis model of transformer connected with high frequency switching circuit is used. A design optimization procedure for high efficiency is also presented using design analysis model, and it is verified by the experimental result.

A Novel Method for Characterizing Fatigue Delamination Growth Under Mode I Using the Double Cantilever Beam Specimen

NASA Technical Reports Server (NTRS)

Carvalho, Nelson; Murri, G.

2014-01-01

A novel method is proposed to obtain Mode I delamination growth rate from a Double Cantilever Beam (DCB) specimen. In the proposed method, Unidirectional (UD) DCB specimens are tested in fatigue at different initial maximum energy release rates levels. The growth rate data obtained in the first increments of crack growth at each maximum energy release rate level are used to generate a Paris Law equation, which characterizes delamination growth rate without fiber-bridging, and can also be used to determine a delamination onset curve. The remaining delamination growth rate data from each test are used to determine a modified Paris law, which characterizes the delamination growth rate in a DCB specimen, explicitly accounting for fiber-bridging. The proposed expression captures well the scatter in experimental data obtained using the DCB specimens, suggesting its adequacy. The Paris Law characterizing delamination growth rate without fiber-bridging predicts higher delamination growth rates for the same maximum energy release rate applied, leading to a conservative estimate for delamination growth. This is particularly relevant, since in generic ply interfaces, fiber-bridging is less predominant than in UD DCB specimens. Failing to account for fiber-bridging in UD DCB specimens may underestimate the delamination growth rate, yielding non-conservative predictions.

Secondary Structural Changes of Intact and Disulfide Bridges-Cleaved Human Serum Albumins in Thermal Denaturation up to 130°C - Additive Effects of Sodium Dodecyl Sulfate on the Changes.

PubMed

Moriyama, Yoshiko; Takeda, Kunio

2017-05-01

The secondary structural changes of human serum albumin with the intact 17 disulfide bridges (HSA) and the disulfide bridges-cleaved human serum albumin (RCM-HSA) in thermal denaturation were examined. Most of the helical structures of HSA, whose original helicity was 66%, were sharply disrupted between 50 and 100°C. However, 14% helicity remained even at 130°C. The temperature dependence of the degree of disrupted helical structures of HSA was discussed in connection with questions about a general protein denaturation model. When HSA lost the disulfide bridges, about two-thirds of the original helices were disrupted. Although the helices of RCM-HSA remaining after the cleavage of the disulfide bridges were relatively resistant against the heat treatment, the helicity changed from 22% at 25°C to 14% at 130℃. The helicity of RCM-HSA at 130°C agreed with the helicity of HSA at the same temperature, indicating that the same helical moieties of the polypeptides remained unaffected at this high temperature. The additive effects of sodium dodecyl sulfate (SDS) on the structural changes of HSA and RCM-HSA in thermal denaturation were also examined. A slight amount of SDS protected the helical structures of HSA from thermal denaturation below 80°C. Upon cooling to 25°C after heat treatment at temperatures below 70°C with the coexistence of SDS of low concentrations, the helical structures of HSA were reformed to the original level at 25°C before heating. A similar tendency was also observed after heat treatment at 80°C. In contrast, the helical structures of the RCM-HSA complexes with SDS are completely recovered upon cooling to 25°C even after heat treatment up to 100°C. Similar investigations were also carried out on bovine serum albumins which had the intact 17 disulfide bridges and lost all of the bridges.

Chk1 protects against chromatin bridges by constitutively phosphorylating BLM serine 502 to inhibit BLM degradation.

PubMed

Petsalaki, Eleni; Dandoulaki, Maria; Morrice, Nick; Zachos, George

2014-09-15

Chromatin bridges represent incompletely segregated chromosomal DNA connecting the anaphase poles and can result in chromosome breakage. The Bloom's syndrome protein helicase (BLM, also known as BLMH) suppresses formation of chromatin bridges. Here, we show that cells deficient in checkpoint kinase 1 (Chk1, also known as CHEK1) exhibit higher frequency of chromatin bridges and reduced BLM protein levels compared to controls. Chk1 inhibition leads to BLM ubiquitylation and proteasomal degradation during interphase. Furthermore, Chk1 constitutively phosphorylates human BLM at serine 502 (S502) and phosphorylated BLM localises to chromatin bridges. Mutation of S502 to a non-phosphorylatable alanine residue (BLM-S502A) reduces the stability of BLM, whereas expression of a phospho-mimicking BLM-S502D, in which S502 is mutated to aspartic acid, stabilises BLM and prevents chromatin bridges in Chk1-deficient cells. In addition, wild-type but not BLM-S502D associates with cullin 3, and cullin 3 depletion rescues BLM accumulation and localisation to chromatin bridges after Chk1 inhibition. We propose that Chk1 phosphorylates BLM-S502 to inhibit cullin-3-mediated BLM degradation during interphase. These results suggest that Chk1 prevents deleterious anaphase bridges by stabilising BLM. © 2014. Published by The Company of Biologists Ltd.

High-Frequency Fe-H Vibrations in a Bridging Hydride Complex Characterized by NRVS and DFT.

PubMed

Pelmenschikov, Vladimir; Gee, Leland B; Wang, Hongxin; MacLeod, K Cory; McWilliams, Sean F; Skubi, Kazimer L; Cramer, Stephen P; Holland, Patrick L

2018-05-30

High-spin iron species with bridging hydrides have been detected in species trapped during nitrogenase catalysis, but there are few general methods of evaluating Fe-H bonds in high-spin multinuclear iron systems. An 57 Fe nuclear resonance vibrational spectroscopy (NRVS) study on an Fe(μ-H) 2 Fe model complex reveals Fe-H stretching vibrations for bridging hydrides at frequencies greater than 1200 cm -1 . These isotope-sensitive vibrational bands are not evident in infrared (IR) spectra, showing the power of NRVS for identifying hydrides in this high-spin iron system. Complementary density functional theory (DFT) calculations elucidate the normal modes of the rhomboidal iron hydride core. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

63. Photocopy of photograph (original print in the Minnesota Historical ...

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

63. Photocopy of photograph (original print in the Minnesota Historical Society, St. Paul, Minnesota, 1958. #31008. Photographer: St. Paul Dispatch-Pioneer Press.) AERIAL VIEW OF HIGH BRIDGE, LOOKING SOUTHWEST, 1958 - Smith Avenue High Bridge, Smith Avenue between Cherokee Avenue & Cliff Street, Saint Paul, Ramsey County, MN

70. Photocopy of photograph (original print in the Minnesota Historical ...

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

70. Photocopy of photograph (original print in the Minnesota Historical Society, St. Paul, Minnesota, 1904. #18613g. Photographer: Albert Munson) VIEW TO WEST, SHOWING FALSEWORK USED IN RECONTRUCTING THE HIGH BRIDGE, 1904. - Smith Avenue High Bridge, Smith Avenue between Cherokee Avenue & Cliff Street, Saint Paul, Ramsey County, MN

Academic Wholism: Bridging the Gap between High School and College

ERIC Educational Resources Information Center

Giuliano, Barbara; Sullivan, Judith

2007-01-01

Without adequate reading comprehension, writing proficiency, math competency, and critical thinking skills, students pursuing higher education are vulnerable to failure. An environmental Science course built around academic wholism is the focus of a summer program designed to bridge the gap between high school and college. Students self-reflect…

High Performance Concrete in Washington State SR 18/SR 516 Overcrossing: Interim Report on Girder Monitoring

DOT National Transportation Integrated Search

2000-04-01

In the mid 1990s the Federal Highway Administration (FHWA) established a High Performance Concrete (HPC) program aimed at demonstrating the positive effects of utilizing HPC in bridges. Research on the benefits of using HPC for bridges has shown a nu...

High performance concrete in Washington state SR 18/SR 516 overcrossing : interim report on materials tests

DOT National Transportation Integrated Search

2000-04-01

In the mid 1990s the Federal Highway Administration (FHWA) established a High Performance Concrete (HPC) program aimed at demonstrating the positive effects of utilizing HPC in bridges. Research on the benefits of using HPC for bridges has shown a nu...

Precast concrete deck panel performance on long span, high traffic volume bridges : final report.

DOT National Transportation Integrated Search

2006-02-01

The NHDOT prohibited the use of partial depth precast deck panels on its long span, high traffic volume bridges until it could investigate if the precast : slabs and the concrete overpour were acting in a composite manner. The NHDOT also wanted to en...

Randomized controlled trial of peer-led recovery education using Building Recovery of Individual Dreams and Goals through Education and Support (BRIDGES).

PubMed

Cook, Judith A; Steigman, Pamela; Pickett, Sue; Diehl, Sita; Fox, Anthony; Shipley, Patricia; MacFarlane, Rachel; Grey, Dennis D; Burke-Miller, Jane K

2012-04-01

The purpose of this study was to test the efficacy of a peer-led, mental illness education intervention called Building Recovery of Individual Dreams and Goals through Education and Support (BRIDGES). Subjects were recruited from outpatient community mental health settings in eight Tennessee communities. Using a single-blind, randomized controlled trial design, 428 individuals with serious mental illness (SMI) were interviewed at baseline and assigned to BRIDGES or to a services as usual wait list control condition. Two-and-one-half hour classes were taught once a week for 8 weeks by peers who were certified BRIDGES instructors. Subjects were followed-up at immediate post-intervention and 6-months later. The primary outcome was self-perceived recovery, measured by the Recovery Assessment Scale (RAS). A secondary outcome was hopefulness as assessed by the State Hope Scale (SHS). An exploratory hypothesis examined the impact of depressive symptoms on both recovery outcomes. Eighty six percent of participants were followed up. On average, participants attended five sessions. Intent-to-treat analysis using mixed-effects random regression found that, compared to controls, intervention participants reported: 1) significantly greater improvement in total RAS scores as well as subscales measuring personal confidence and tolerable symptoms; and 2) significantly greater improvement in hopefulness as assessed by the agency subscale of the SHS. While study subjects with high levels of depressive symptoms had significantly poorer outcomes, outcomes were superior for BRIDGES participants regardless of depressive symptoms. Peer-led mental illness education improves participants' self-perceived recovery and hopefulness over time, even controlling for severity of depressive symptoms. Copyright © 2011 Elsevier B.V. All rights reserved.

The (Im)possible Pursuit of the College Degree: Exploring the Experiences of a Small Urban High School's Alumni

ERIC Educational Resources Information Center

Rivera-McCutchen, Rosa L.

2016-01-01

Bridges Institute is a small public urban high school founded in 1994 as part of the restructuring of a failing comprehensive high school. Part of a network of "critical" small schools in New York City, Bridges aims to interrupt the educational neglect of their students through carefully designed student-centered instruction and…

KENNEDY SPACE CENTER, FLA. - This bird's-eye view of a high bay in the Orbiter Processing Facility (OPF) shows Space Shuttle Atlantis surrounded by the standard platforms and equipment required to process a Space Shuttle orbiter for flight. The high bay is 197 feet (60 meters) long, 150 feet (46 meters) wide, 95 feet (29 meters) high, and encompasses a 29,000-square-foot (2,694-meter) area. Platforms, a main access bridge, and two rolling bridges with trucks provide access to various parts of the orbiter. The next mission scheduled for Atlantis is STS-114, a utilization and logistics flight to the International Space Station.

NASA Image and Video Library

2003-09-03

KENNEDY SPACE CENTER, FLA. - This bird's-eye view of a high bay in the Orbiter Processing Facility (OPF) shows Space Shuttle Atlantis surrounded by the standard platforms and equipment required to process a Space Shuttle orbiter for flight. The high bay is 197 feet (60 meters) long, 150 feet (46 meters) wide, 95 feet (29 meters) high, and encompasses a 29,000-square-foot (2,694-meter) area. Platforms, a main access bridge, and two rolling bridges with trucks provide access to various parts of the orbiter. The next mission scheduled for Atlantis is STS-114, a utilization and logistics flight to the International Space Station.

Verification of image orthorectification techniques for low-cost geometric inspection of masonry arch bridges

NASA Astrophysics Data System (ADS)

González-Jorge, Higinio; Riveiro, Belén; Varela, María; Arias, Pedro

2012-07-01

A low-cost image orthorectification tool based on the utilization of compact cameras and scale bars is developed to obtain the main geometric parameters of masonry bridges for inventory and routine inspection purposes. The technique is validated in three different bridges by comparison with laser scanning data. The surveying process is very delicate and must make a balance between working distance and angle. Three different cameras are used in the study to establish the relationship between the error and the camera model. Results depict nondependence in error between the length of the bridge element, the type of bridge, and the type of element. Error values for all the cameras are below 4 percent (95 percent of the data). A compact Canon camera, the model with the best technical specifications, shows an error level ranging from 0.5 to 1.5 percent.

Assessment of the integrity of concrete bridge structures by acoustic emission technique

NASA Astrophysics Data System (ADS)

Yoon, Dong-Jin; Park, Philip; Jung, Juong-Chae; Lee, Seung-Seok

2002-06-01

This study was aimed at developing a new method for assessing the integrity of concrete structures. Especially acoustic emission technique was used in carrying out both laboratory experiment and field application. From the previous laboratory study, we confirmed that AE analysis provided a promising approach for estimating the level of damage and distress in concrete structures. The Felicity ratio, one of the key parameter for assessing damage, exhibits a favorable correlation with the overall damage level. The total number of AE events under stepwise cyclic loading also showed a good agreement with the damage level. In this study, a new suggested technique was applied to several concrete bridges in Korea in order to verify the applicability in field. The AE response was analyzed to obtain key parameters such as the total number and rate of AE events, AE parameter analysis for each event, and the characteristic features of the waveform as well as Felicity ratio analysis. Stepwise loading-unloading procedure for AE generation was introduced in field test by using each different weight of vehicle. According to the condition of bridge, for instance new or old bridge, AE event rate and AE generation behavior indicated many different aspects. The results showed that the suggested analyzing method would be a promising approach for assessing the integrity of concrete structures.

Development of bridge-scour instrumentation for inspection and maintenance personnel

USGS Publications Warehouse

Mueller, David S.; Landers, Mark N.; ,

1993-01-01

Inspecting bridges and monitoring scour during high flow can improve public transportation safety by providing early identification of scour and stream stability problems at bridges. Most bridge-inspection data are collected during low flow, when scour holes may have refilled. More than 25 percent of the States that responded to a questionnaire identified lack of adequate methodology and/or equipment as reasons for not collecting scour data during high-flow conditions. Therefore, the U.S. Geological Survey (USGS), in cooperation with the Federal Highway Administration, has begun to develop instrumentation for measuring scour that could be used by inspection and maintenance personnel during high-flow conditions. A variety of instruments and techniques for measuring scour were tested and evaluated in real-time bridge-scour data-collection studies by the USGS. In the National Scour study, fathometers were found to be superior to sounding weights and will be the primary bed-measuring instrument. The ability of low-cost fathometers and fish finders to locate the bed accurately is being evaluated. Simple and efficient methods for deploying the transducer during floods are also important for a successful measurement. The information and additional testing are being used to design new, portable scour-measuring systems.

Strengthening of bridges by post-tensioning using monostrands in substituted cable ducts

NASA Astrophysics Data System (ADS)

Klusáček, Ladislav; Svoboda, Adam

2017-09-01

Post-tensioning is suitable, reliable and durable method of strengthening existing engineering structures, especially bridges. The high efficiency of post-tensioning can be seen in many applications throughout the world. In this paper the method is extended by a structural system of substituted cable ducts, which allows for significantly widening application of prestressing so it’s convenient mostly for application on beam bridges or slab bridges (built in years 1920 - 1960). The method of substituted cable ducts is based on theoretical knowledge and technical procedures, which were made possible through the development in prestressing systems, particularly the development of prestressing tendons (monostrands) and encased anchorages, as well as progress in drilling technology. This technique is highly recommended due to minimization of interventions into the constructions, unseen method of cable arrangement and hence the absence of impact on appearance, which is appreciated not only in case of valuable historical structures but also in general. It is possible to summarise that posttensioning by monostrands in substituted cable ducts is a highly effective method of strengthening existing bridges in order to increase their load capacities in terms of current traffic load and to extend their service life.

A Bridge to Active Learning: A Summer Bridge Program Helps Students Maximize Their Active-Learning Experiences and the Active-Learning Experiences of Others

PubMed Central

Cooper, Katelyn M.; Ashley, Michael; Brownell, Sara E.

2017-01-01

National calls to improve student academic success in college have sparked the development of bridge programs designed to help students transition from high school to college. We designed a 2-week Summer Bridge program that taught introductory biology content in an active-learning way. Through a set of exploratory interviews, we unexpectedly identified that Bridge students had developed sophisticated views of active learning, even though this was not an explicit goal of the program. We conducted an additional set of semistructured interviews that focused on active learning and compared the interviews of Bridge students with those from non-Bridge students who had been eligible for but did not participate in the program. We used the constant comparative method to identify themes from the interviews. We found that Bridge students perceived that, because they knew how to approach active learning and viewed it as important, they benefited more from active learning in introductory biology than non-Bridge students. Specifically, Bridge students seemed to be more aware of their own learning gains from participating in active learning. Compared with the majority of non-Bridge students, the majority of Bridge students described using a greater variety of strategies to maximize their experiences in active learning. Finally, in contrast to non-Bridge students, Bridge students indicated that they take an equitable approach to group work. These findings suggest that we may be able to prime students to maximize their own and other’s experiences in active learning. PMID:28232588

77 FR 44143 - Drawbridge Operation Regulation; New Jersey Intracoastal Waterway (NJICW); Atlantic City, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-27

.../Absecon Boulevard Bridge across Beach Thorofare, NJICW mile 67.2 and the US40-322 (Albany Avenue) across... Route 30/Absecon Boulevard Bridge across Beach Thorofare, NJICW mile 67.2 and the US40-322 (Albany... mean high water. US40-322 (Albany Avenue) Bridge The current operating regulation for the US40-322...

78 FR 76195 - Drawbridge Operation Regulations; Hackensack River, New Jersey

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-17

... Upper Hack and HX Bridges, miles 6.9 and 7.7, respectively, all across the Hackensack River, NJ to... Upper Hack Bridge, mile 6.9, has a vertical clearance of 8 feet at mean high water, and 13 feet at mean... so at all times. Under this temporary deviation the PATH, Portal, Upper Hack and HX bridges may...

Bridging the Gap: An Impact Study of Eight Developmental Summer Bridge Programs in Texas. NCPR Brief

ERIC Educational Resources Information Center

Barnett, Elisabeth A.; Bork, Rachel Hare; Mayer, Alexander K.; Pretlow, Joshua; Wathington, Heather D.; Weiss, Madeline Joy

2012-01-01

Across the country, a growing number of recent high school graduates are participating in summer bridge programs. These programs provide accelerated and focused learning opportunities in order to help students acquire the knowledge and skills needed for college success. The state of Texas has given particular attention to summer programs as a way…

Integrating Satellite Image Identification and River Routing Simulation into the Groundwater Simulation of Chou-Shui Basin

NASA Astrophysics Data System (ADS)

Yao, Y.; Yang, S.; Chen, Y.; Chang, L.; Chiang, C.; Huang, C.; Chen, J.

2012-12-01

Many groundwater simulation models have been developed for Chou-Shui River alluvial fan which is one of the most important groundwater areas in Taiwan. However, the exchange quantity between Chou-Shui River, the major river in this area, and the groundwater system itself is seldom studied. In this study, the exchange is evaluated using a river package (RIV) in the groundwater simulation model, MODFLOW 2000. Several critical parameters and variables used in RIV such as wet area and river level for each cell below the Chou-Shui River are respectively determined by satellite image identification and HEC-RAS simulation. The monthly average of river levels obtained from four stations include Chang-Yun Bridge, Xi-Bin Bridge, Chi-Chiang Bridge and Si-Jou Bridge during 2008 and the river cross-section measured on December 2007 are used in the construction of HEC-RAS model. Four FORMOSAT multispectral satellite images respectively obtained on January 2008, April 2008, July 2008, and November 2008 are used to identify the wet area of Chou-Shui River during different seasons. Integrating the simulation level provided by HEC-RAS and the identification result are used as the assignment of RIV. First, based on the simulation results of HEC-RAS, the water level differences between flooding period and draught period are 1.4 (m) and 2.0 (m) for Xi-Bin Bridge station (downstream) and Chang-Yun Bridge station (upstream) respectively. Second, based on the identified results, the wet areas for four seasons are 24, 24, 40 and 12 (km2) respectively. The variation range of areas in 2008 is huge that the area for winter is just 30% of the area for summer. Third, based on the simulation of MODFLOW 2000 and RIV, the exchange between the river and the groundwater system is 414 million cubic meters which contains 526 for recharge to river and 112 for discharging from river during 2008. The total recharge includes river exchange and recharge from non-river area is 2023 million cubic meters. The pumping quantity is 1930 million cubic meters.

9. VIEW OF INTAKE PIER AND MAIN SPAN OF ACCESS ...

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

9. VIEW OF INTAKE PIER AND MAIN SPAN OF ACCESS BRIDGE FROM WATER LEVEL, LOOKING NORTHWEST. - Sacramento River Water Treatment Plant Intake Pier & Access Bridge, Spanning Sacramento River approximately 175 feet west of eastern levee on river; roughly .5 mile downstream from confluence of Sacramento & American Rivers, Sacramento, Sacramento County, CA

49 CFR 38.83 - Mobility aid accessibility.

Code of Federal Regulations, 2010 CFR

2010-10-01

... shall provide a level-change mechanism or boarding device (e.g., lift, ramp or bridge plate) complying... required. (2) Exception. If lifts, ramps or bridge plates meeting the requirements of this section are... accommodated on a single vehicle. (b) Vehicle lift—(1) Design load. The design load of the lift shall be at...

36 CFR 1192.81 - Lighting.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Vehicles and Systems § 1192.81 Lighting. (a) Any stepwell or doorway with a lift, ramp or bridge plate... measured on the step tread or lift platform. (b) Other stepwells, and doorways with lifts, ramps or bridge... lift or ramp, when deployed at the vehicle floor level. (c) The doorways of vehicles not operating at...

36 CFR 1192.81 - Lighting.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Vehicles and Systems § 1192.81 Lighting. (a) Any stepwell or doorway with a lift, ramp or bridge plate... measured on the step tread or lift platform. (b) Other stepwells, and doorways with lifts, ramps or bridge... lift or ramp, when deployed at the vehicle floor level. (c) The doorways of vehicles not operating at...

49 CFR 38.83 - Mobility aid accessibility.

Code of Federal Regulations, 2011 CFR

2011-10-01

... shall provide a level-change mechanism or boarding device (e.g., lift, ramp or bridge plate) complying... required. (2) Exception. If lifts, ramps or bridge plates meeting the requirements of this section are... accommodated on a single vehicle. (b) Vehicle lift—(1) Design load. The design load of the lift shall be at...

"Bridging Activities," New Media Literacies, and Advanced Foreign Language Proficiency

ERIC Educational Resources Information Center

Thorne, Steven L.; Reinhardt, Jonathon

2008-01-01

In this article we propose the pedagogical model "bridging activities" to address advanced foreign language proficiency in the context of existing and emerging internet communication and information tools and communities. The article begins by establishing the need for language and genre-focused activities at the advanced level that attend to the…

Prior Decisions and Experiences about Mathematics of Students in Bridging Courses

ERIC Educational Resources Information Center

Gordon, Sue; Nicholas, Jackie

2013-01-01

We report on the survey responses of 51 students attending mathematics bridging courses at a major Australian university, investigating what mathematics, if any, these students had studied in the senior years of schooling and what factors affected their decisions about the level of mathematics chosen. Quantitative findings are augmented by…

Reading?...Pah! (I Got It!): Innovative Reading Techniques for Successful Deaf Readers.

ERIC Educational Resources Information Center

Schimmel, Connie (Ruth) S.; Edwards, Sandra G.; Prickett, Hugh T.

1999-01-01

A reading program utilizing five components (a shortcut to phonemic awareness, Adapted Dolch words, Bridge lists and the Bridging process, reading comprehension, and American Sign Language development/language experience stories) resulted in dramatic gains in the reading levels of 48 elementary students at a residential school for the deaf.…

Level II scour analysis for Bridge 42 (RANDVT00120042) on State Highway 12, crossing Third Branch White River, Randolph, Vermont

USGS Publications Warehouse

Olson, Scott A.; Weber, Matthew A.

1996-01-01

bridge consisting of four concrete spans. The maximum span length is 57 ft. (Vermont Agency of Transportation, written commun., July 29, 1994). The bridge is supported by vertical, concrete abutments and three concrete piers. The toe of the left abutment is at the channel edge. The toe of the right abutment is set back on the right over-bank. The roadway centerline on the structure has a slight horizontal curve; however, the main channel is skewed approximately 5 degrees to the bridge. 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). Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. The scour analysis results are presented in tables 1 and 2 and a graph of the scour depths is presented in figure 8.

The cross-bridge dynamics is determined by two length-independent kinetics: Implications on muscle economy and Frank-Starling Law.

PubMed

Amiad Pavlov, Daria; Landesberg, Amir

2016-01-01

The cellular mechanisms underlying the Frank-Starling Law of the heart and the skeletal muscle force-length relationship are not clear. This study tested the effects of sarcomere length (SL) on the average force per cross-bridge and on the rate of cross-bridge cycling in intact rat cardiac trabeculae (n=9). SL was measured by laser diffraction and controlled with a fast servomotor to produce varying initial SLs. Tetanic contractions were induced by addition of cyclopiazonic acid, to maintain a constant activation. Stress decline and redevelopment in response to identical ramp shortenings, starting at various initial SLs, was analyzed. Both stress decline and redevelopment responses revealed two distinct kinetics: a fast and a slower phase. The duration of the rapid phases (4.2 ± 0.1 msec) was SL-independent. The second slower phase depicted a linear dependence of the rate of stress change on the instantaneous stress level. Identical slopes (70.5 ± 1.6 [1/s], p=0.33) were obtained during ramp shortening at all initial SLs, indicating that the force per cross-bridge and cross-bridge cycling kinetics are length-independent. A decrease in the slope at longer SLs was obtained during stress redevelopment, due to internal shortening. The first phase is attributed to rapid changes in the average force per cross-bridge. The second phase is ascribed to both cross-bridge cycling between its strong and weak conformations and to changes in the number of strong cross-bridges. Cross-bridge cycling kinetics and muscle economy are length-independent and the Frank-Starling Law cannot be attributed to changes in the force per cross-bridge or in the single cross-bridge cycling rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

Three Dimensional Mesoscale Analysis of Translamellar Cross-Bridge Morphologies in the Annulus Fibrosus using Optical Coherence Tomography

PubMed Central

Han, Sang Kuy; Chen, Chao-Wei; Wierwille, Jerry; Chen, Yu; Hsieh, Adam H.

2014-01-01

The defining characteristic of the annulus fibrosus (AF) of the intervertebral disc (IVD) has long been the lamellar structures that consist of highly ordered collagen fibers arranged in alternating oblique angles from one layer to the next. However, a series of recent histologic studies have demonstrated that AF lamellae contain elastin- and type VI collagen-rich secondary “cross-bridge” structures across lamellae. In this study, we use optical coherence tomography (OCT) to elucidate the three-dimensional (3D) morphologies of these translamellar cross-bridge in AF tissues. Mesoscale volumetric images by OCT reveal a highly heterogeneous spatial network and distribution of 3-D translamellar cross-bridges. The results of this study confirm the translamellar cross-bridge is identified as a distinguishable structure, which is laid in the interbundle space of adjacent lamellae and crisscrosses multiple lamellae in the radial direction. In contrast to previously proposed models extrapolated from 2-D sections, results from this current study show that translamellar cross-bridges exist as a complex, interconnected network. We also found much greater variation in lengths of cross-bridges within the interbundle space of lamellae (0.8-1.4 mm from the current study versus 0.3-0.6 mm from 2-D sections). OCT-based 3-D morphology of translamellar cross-bridge provides novel insight into the AF structure. PMID:25564974

Utilization of wireless structural health monitoring as decision making tools for a condition and reliability-based assessment of railroad bridges

NASA Astrophysics Data System (ADS)

Flanigan, Katherine A.; Johnson, Nephi R.; Hou, Rui; Ettouney, Mohammed; Lynch, Jerome P.

2017-04-01

The ability to quantitatively assess the condition of railroad bridges facilitates objective evaluation of their robustness in the face of hazard events. Of particular importance is the need to assess the condition of railroad bridges in networks that are exposed to multiple hazards. Data collected from structural health monitoring (SHM) can be used to better maintain a structure by prompting preventative (rather than reactive) maintenance strategies and supplying quantitative information to aid in recovery. To that end, a wireless monitoring system is validated and installed on the Harahan Bridge which is a hundred-year-old long-span railroad truss bridge that crosses the Mississippi River near Memphis, TN. This bridge is exposed to multiple hazards including scour, vehicle/barge impact, seismic activity, and aging. The instrumented sensing system targets non-redundant structural components and areas of the truss and floor system that bridge managers are most concerned about based on previous inspections and structural analysis. This paper details the monitoring system and the analytical method for the assessment of bridge condition based on automated data-driven analyses. Two primary objectives of monitoring the system performance are discussed: 1) monitoring fatigue accumulation in critical tensile truss elements; and 2) monitoring the reliability index values associated with sub-system limit states of these members. Moreover, since the reliability index is a scalar indicator of the safety of components, quantifiable condition assessment can be used as an objective metric so that bridge owners can make informed damage mitigation strategies and optimize resource management on single bridge or network levels.

64. Photocopy of photograph (original print in the Minnesota Historical ...

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

64. Photocopy of photograph (original print in the Minnesota Historical Society, St. Paul Minnesota, ca. 1891. #35805. Photographer: Haynes and Bros., St. Paul.) VIEW TO SOUTH, SHOWING FOUR PERCENT GRADE OF HIGH BRIDGE, ca. 1981 - Smith Avenue High Bridge, Smith Avenue between Cherokee Avenue & Cliff Street, Saint Paul, Ramsey County, MN

Evidence for Milankovitch periodicities in Cenomanian-Turonian lithologic and geochemical cycles, western interior U.S.A.

USGS Publications Warehouse

Sageman, B.B.; Rich, J.; Arthur, M.A.; Birchfield, G.E.; Dean, W.E.

1997-01-01

The limestone/marlstone bedding couplets of the Bridge Creek Limestone Member, Cenomanian-Turonian Greenhorn Formation, were analyzed by applying spectral techniques to high-resolution lithologic and geochemical data from a core. The results suggest that the Bridge Creek contains a complex record of orbital cyclicity. The dominant signal appears to be obliquity, but signals corresponding to precession and eccentricity were also observed. The development of the bedding couplets is interpreted to have resulted from a combination of factors, including insolation-controlled changes in higher-latitude precipitation leading to dilution/redox cycles, and in lower-latitude evaporation, leading to changes in surface water conditions and productivity cycles in the calcareous plankton. The data interpreted to reflect redox cycles appear to be more strongly influenced by obliquity, and show a weak precessional signal. In contrast, trends in the carbonate record show the opposite response. The complex bedding pattern observed in the Bridge Creek Limestone is interpreted to result from the competing influences of different orbital cycles expressed through different pathways of the depositional system, and was also affected by changes in sedimentation rates related to relative sea level fluctuations, aperiodic dilution by volcanic ash, and changes in organic-matter production and redox conditions related to a global "oceanic anoxic event". These factors complicate cycle analysis in the lower part of the member but leave a relatively undisturbed record in the upper Bridge Creek Limestone. Copyright ?? 1997, SEPM (Society for Sedimentary Geology).

Level II scour analysis for Bridge 35, (ANDOVT00110035) on State Route 11, crossing the Middle Branch Williams River, Andover, Vermont

USGS Publications Warehouse

Burns, Ronda L.; Wild, Emily C.

1998-01-01

This report provides the results of a detailed Level II analysis of scour potential at structure ANDOVT00110035 on State Route 11 crossing the Middle Branch Williams River, Andover, 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 (Federal Highway Administration, 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 south-central Vermont. The 4.65-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is forest on the left bank and small trees and brush on the right bank upstream and downstream of the bridge. In the study area, the Middle Branch Williams River has an incised, meandering channel with a slope of approximately 0.02 ft/ft, an average channel top width of 57 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 31.4 mm (0.103 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 28, 1996, indicated that the reach was laterally unstable. There are cut-banks upstream and downstream of the bridge and an island in the channel upstream. The State Route 11 crossing of the Middle Branch Williams River is a 28-ft-long, two-lane bridge consisting of one 24-ft concrete tee-beam span (Vermont Agency of Transportation, written communication, March 28, 1995). The opening length of the structure parallel to the bridge face is 23.6 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 45 degrees to the opening while the computed opening-skew-to-roadway is 25 degrees. A scour hole ranging from 1.5 to 1.75 ft deeper than the mean thalweg depth was observed along the upstream left wingwall, the left abutment, and the downstream left wingwall during the Level I assessment. The scour countermeasures at the site included type-1 stone fill (less than 12 inches diameter) at the right road approach upstream and downstream of the bridge and type-2 stone fill (less than 36 inches diameter) at the left road approach upstream and downstream of the bridge. 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 Davis, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge was determined and analyzed as another potential 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 2.0 to 4.3 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 14.4 to 16.5 ft at the left abutment and from 6.3 to 8.8 ft at the right abutment. 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 cross-section 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-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and Davis, 1995, p. 46). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

High-Performance Visible-Blind UV Phototransistors Based on n-Type Naphthalene Diimide Nanomaterials.

PubMed

Song, Inho; Lee, Seung-Chul; Shang, Xiaobo; Ahn, Jaeyong; Jung, Hoon-Joo; Jeong, Chan-Uk; Kim, Sang-Wook; Yoon, Woojin; Yun, Hoseop; Kwon, O-Pil; Oh, Joon Hak

2018-04-11

This study investigates the performance of single-crystalline nanomaterials of wide-band gap naphthalene diimide (NDI) derivatives with methylene-bridged aromatic side chains. Such materials are found to be easily used as high-performance, visible-blind near-UV light detectors. NDI single-crystalline nanoribbons are assembled using a simple solution-based process (without solvent-inclusion problems), which is then applied to organic phototransistors (OPTs). Such OPTs exhibit excellent n-channel transistor characteristics, including an average electron mobility of 1.7 cm 2 V -1 s -1 , sensitive UV detection properties with a detection limit of ∼1 μW cm -2 , millisecond-level responses, and detectivity as high as 10 15 Jones, demonstrating the highly sensitive organic visible-blind UV detectors. The high performance of our OPTs originates from the large face-to-face π-π stacking area between the NDI semiconducting cores, which is facilitated by methylene-bridged aromatic side chains. Interestingly, NDI-based nanoribbon OPTs exhibit a distinct visible-blind near-UV detection with an identical detection limit, even under intense visible light illumination (for example, 10 4 times higher intensity than UV light intensity). Our findings demonstrate that wide-band gap NDI-based nanomaterials are highly promising for developing high-performance visible-blind UV photodetectors. Such photodetectors could potentially be used for various applications including environmental and health-monitoring systems.

Determination Method of Bridge Rotation Angle Response Using MEMS IMU

PubMed Central

Sekiya, Hidehiko; Kinomoto, Takeshi; Miki, Chitoshi

2016-01-01

To implement steel bridge maintenance, especially that related to fatigue damage, it is important to monitor bridge deformations under traffic conditions. Bridges deform and rotate differently under traffic load conditions because their structures differ in terms of length and flexibility. Such monitoring enables the identification of the cause of stress concentrations that cause fatigue damage and the proposal of appropriate countermeasures. However, although bridge deformation monitoring requires observations of bridge angle response as well as the bridge displacement response, measuring the rotation angle response of a bridge subject to traffic loads is difficult. Theoretically, the rotation angle response can be calculated by integrating the angular velocity, but for field measurements of actual in-service bridges, estimating the necessary boundary conditions would be difficult due to traffic-induced vibration. To solve the problem, this paper proposes a method for determining the rotation angle response of an in-service bridge from its angular velocity, as measured by a inertial measurement unit (IMU). To verify our proposed method, field measurements were conducted using nine micro-electrical mechanical systems (MEMS) IMUs and two contact displacement gauges. The results showed that our proposed method provided high accuracy when compared to the reference responses calculated by the contact displacement gauges. PMID:27834871

Monitoring and Evaluation of a Long-Span Raiway Bridge Using SENTINEL-1 Data

NASA Astrophysics Data System (ADS)

Huang, Q.; Crosetto, M.; Monserrat, O.; Crippa, B.

2017-09-01

This paper is focused on displacement monitoring of a bridge, which is one of the key aspects of its structural health monitoring. A simplified Persistent Scatterer Interferometry (PSI) approach is used to monitor the displacements of the Nanjing Dashengguan Yangtze River High-speed Railway Bridge (China). This bridge is 1272 m long and hosts a total of 6 railway lines. The analysis was based on a set of twenty-nine Sentinel-1A images, acquired from April 2015 to August 2016. A dense set of measurement points were selected on the bridge. The PSI results show a maximum longitudinal displacement of 150 mm, on each side of the bridge. The displacements are strongly correlated with the temperature, showing that they are due to thermal expansion. Using the PSI results, the Coefficient of Thermal Expansion (CTE) of the whole bridge was estimated. The result agrees well with the CTE of the bridge materials. Using a regression model, the PSI-measured displacements were compared with in-situ measurements. The paper proposes a procedure to assess the performance of the movable bearings of the bridge, which is based on the PSI measurements.

Spatial discrimination of persistent EUV oscillations in a hot waning light bridge

NASA Astrophysics Data System (ADS)

Walsh, D.; Yuan, R. W.

2016-10-01

A light bridge is usually formed as a lower atmospheric structure in nascent or decaying sunspots; it divides the umbra into separate regions. Convection, which is normally suppressed by a sunspot's strong magnetic field, is partially restored and upflows are usually observed at the spine of a bridge with downflows (or return flows) at the two flanks. This study outlines observations a light bridge unusually sustained at coronal temperatures. Viewed in AR11520 on 12th July 2012 by the High Resolution Coronal Imager (HiC) and AIA/SDO, the EUV emission intensity exhibits two persistent oscillations. The approximate 5-minute oscillations are distributed along the spine of the light bridge whereas sub-minute oscillations are distinctively co-spatial along each bridge flank (though there is a distinct time-lag between them). This indicates strongly that (i) the oscillatory driver at the flanks is connected with the collective interactions between magnetic fields of the bridge and the sunspot itself and (ii) the internal magnetic structure of the bridge is twisted. The presentation will outline the distinct oscillatory maps generated and provide insight into determining the magnetic morphology until the bridge wans several hours later.

Effects of bridge construction on songbirds and small mammals at Blennerhassett Island, Ohio River, USA.

PubMed

Vance, Joshua A; Angus, Norse B; Anderson, James T

2013-09-01

Construction of man-made objects such as roads and bridges may have impacts on wildlife depending on species or location. We investigated songbirds and small mammals along the Ohio River, WV, USA at a new bridge both before and after construction and at a bridge crossing that was present throughout the study. Comparisons were made at each site over three time periods (1985-1987 [Phase I] and 1998-2000 [Phase II] [pre-construction], 2007-2009 [Phase III] [post-construction]) and at three distances (0, 100, 300 m) from the bridge or proposed bridge location. Overall, 70 songbirds and 10 small mammals were detected during the study. Cliff swallows (Petrochelidon pyrrhonota) and rock pigeons (Columba livia) showed high affinity for bridges (P < 0.05). Combined small mammal abundances increased between Phases I and II (P < 0.05), but did not differ between Phases II and III (P > 0.05). Species richness and diversity for songbirds and small mammals did not differ before and after bridge construction (P > 0.05). We found that most species sampled did not respond to the bridge crossing, and believe that the bridge is not causing any measurable negative density impacts to the species we investigated. The new bridge does provide habitat for exotic rock pigeons that are adjusted to man-made structures for nesting.

Key Royale bridge five year evaluation.

DOT National Transportation Integrated Search

2013-06-01

This report describes the design, construction, instrumentation, and five-year evaluation of the Key Royale Bridge substructure. The primary focus was the evaluation of the implementation of highly reactive supplementary cementitious materials (SCM) ...

Non-linear vehicle-bridge-wind interaction model for running safety assessment of high-speed trains over a high-pier viaduct

NASA Astrophysics Data System (ADS)

Olmos, José M.; Astiz, Miguel Á.

2018-04-01

In order to properly study the high-speed traffic safety on a high-pier viaduct subject to episodes of lateral turbulent winds, an efficient dynamic interaction train-bridge-wind model has been developed and experimentally validated. This model considers the full wheel and rail profiles, the friction between these two bodies in contact, and the piers P-Delta effect. The model has been used to determine the critical train and wind velocities from which the trains cannot travel safely over the O'Eixo Bridge. The dynamic simulations carried out and the results obtained in the time domain show that traffic safety rates exceed the allowed limits for turbulent winds with mean velocities at the deck higher than 25 m/s.

Radical polymerization of capillary bridges between micron-sized particles in liquid bulk phase as a low temperature route to produce porous solid materials.

PubMed

Hauf, Katharina; Riazi, Kamran; Willenbacher, Norbert; Koos, Erin

2017-10-01

We present a generic and versatile low temperature route to produce macro-porous bodies with porosity and pore size distribution that are adjustable in a wide range. Capillary suspensions, where the minor fluid is a monomer, are used as pre-cursors. The monomer is preferentially located between the particles, creating capillary bridges, resulting in a strong, percolating network. Thermally induced polymerization of these bridges at temperatures below 100 °C for less than 5 hours and subsequent removal of the bulk fluid yields macroscopic, self-supporting solid bodies with high porosity. This process is demonstrated using methylmethacrylate and hydroxyethylmethacrlyate with glass particles as a model system. The produced PMMA had a molecular weight of about 500.000 g/mol and dispersity about three. Application specific porous bodies, including PMMA particles connected by PMMA bridges, micron-sized capsules containing phase change material with high inner surface, and porous graphite membranes with high electrical conductivity, are also shown.

Radical polymerization of capillary bridges between micron-sized particles in liquid bulk phase as a low temperature route to produce porous solid materials

PubMed Central

Hauf, Katharina; Riazi, Kamran; Willenbacher, Norbert; Koos, Erin

2018-01-01

We present a generic and versatile low temperature route to produce macro-porous bodies with porosity and pore size distribution that are adjustable in a wide range. Capillary suspensions, where the minor fluid is a monomer, are used as pre-cursors. The monomer is preferentially located between the particles, creating capillary bridges, resulting in a strong, percolating network. Thermally induced polymerization of these bridges at temperatures below 100 °C for less than 5 hours and subsequent removal of the bulk fluid yields macroscopic, self-supporting solid bodies with high porosity. This process is demonstrated using methylmethacrylate and hydroxyethylmethacrlyate with glass particles as a model system. The produced PMMA had a molecular weight of about 500.000 g/mol and dispersity about three. Application specific porous bodies, including PMMA particles connected by PMMA bridges, micron-sized capsules containing phase change material with high inner surface, and porous graphite membranes with high electrical conductivity, are also shown. PMID:29503494

Designing Better Scaffolding in Teaching Complex Systems with Graphical Simulations

NASA Astrophysics Data System (ADS)

Li, Na

Complex systems are an important topic in science education today, but they are usually difficult for secondary-level students to learn. Although graphic simulations have many advantages in teaching complex systems, scaffolding is a critical factor for effective learning. This dissertation study was conducted around two complementary research questions on scaffolding: (1) How can we chunk and sequence learning activities in teaching complex systems? (2) How can we help students make connections among system levels across learning activities (level bridging)? With a sample of 123 seventh-graders, this study employed a 3x2 experimental design that factored sequencing methods (independent variable 1; three levels) with level-bridging scaffolding (independent variable 2; two levels) and compared the effectiveness of each combination. The study measured two dependent variables: (1) knowledge integration (i.e., integrating and connecting content-specific normative concepts and providing coherent scientific explanations); (2) understanding of the deep causal structure (i.e., being able to grasp and transfer the causal knowledge of a complex system). The study used a computer-based simulation environment as the research platform to teach the ideal gas law as a system. The ideal gas law is an emergent chemical system that has three levels: (1) experiential macro level (EM) (e.g., an aerosol can explodes when it is thrown into the fire); (2) abstract macro level (AM) (i.e., the relationships among temperature, pressure and volume); (3) micro level (Mi) (i.e., molecular activity). The sequencing methods of these levels were manipulated by changing the order in which they were delivered with three possibilities: (1) EM-AM-Mi; (2) Mi-AM-EM; (3) AM-Mi-EM. The level-bridging scaffolding variable was manipulated on two aspects: (1) inserting inter-level questions among learning activities; (2) two simulations dynamically linked in the final learning activity. Addressing the first research question, the Experiential macro-Abstract macro-Micro (EM-AM-Mi) sequencing method, following the "concrete to abstract" principle, produced better knowledge integration while the Micro-Abstract macro-Experiential macro (Mi-AM-EM) sequencing method, congruent with the causal direction of the emergent system, produced better understanding of the deep causal structure only when level-bridging scaffolding was provided. The Abstract macro-Micro-Experiential macro (AM-Mi-EM) sequencing method produced worse performance in general, because it did not follow the "concrete to abstract" principle, nor did it align with the causal structure of the emergent system. As to the second research question, the results showed that level-bridging scaffolding was important for both knowledge integration and understanding of the causal structure in learning the ideal gas law system.

Revealing the hidden structures of an historical bridge by high resolution geophysical methods : A case study of Pont de Coq, France

NASA Astrophysics Data System (ADS)

Antoine, R.; Fauchard, C.

2012-04-01

In the last decades, public institutions have shown an increased interest in heritage conservation and monuments protection. Geophysical methods have been used for 20 years as powerful tools to assist in the curation of buildings. Ancient masonry bridges usually exhibit a complex structure/geometry. This complexity makes the use of combined geophysical methods highly necessary to obtain a meaningful model of the internal structure of such constructions and their environment. A high resolution geophysical survey was carried out at a stone arch bridge called Pont de Coq and located near Menerval, Normandy (France) in 2011. This decameter-sized bridge was built 400 years ago and crosses the Epte river, which is a tributary of the Seine river. The main objective of this work was to evaluate the structural state of the bridge and its vicinities. Two complementary methods were used : Electrical Resistivity tomography (ERT) and Ground Penetrating radar (GPR). Several profiles were realized along the road crossing the bridge and transversally to the construction, as well as on the two banks of the Epte river. High resolution electrical resistivity data were obtained both in the horizontal and vertical direction up to 8 meter-depth by two ERT methods (Wenner/Schlumberger and dipole-dipole). The GPR was used with shielded antennas at three different frequencies (200 MHz, 400 MHz and 1.5 GHz). This approach lead to the investigation of the subsurface up to approximately 6 meters-depth, with a resolution in the range of 0.04 m-0.40m. An excellent correlation is obtained between the ERT and the GPR methods, allowing us to propose a precise structural model of the Pont de Coq and to characterize the soil under the building. Several anomalies are observed within the roadway of the bridge at 50 cm-depth, as well as within the vaulting, corresponding to the presence of voids and a root network which lead to the slow destruction of the structure.

Level II scour analysis for Bridge 33 (WWINTH00300033) on Town Highway 30, crossing Mill Brook, West Windsor, Vermont

USGS Publications Warehouse

Wild, Emily C.; Flynn, Robert H.

1998-01-01

This report provides the results of a detailed Level II analysis of scour potential at structure WWINTH00300033 on Town Highway 30 crossing Mill Brook, West Windsor, 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 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 east-central Vermont. The 24.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream of the bridge while the immediate banks have dense woody vegetation. Downstream of the bridge is forested. In the study area, Mill Brook has an incised, sinuous channel with a slope of approximately 0.004 ft/ft, an average channel top width of 58 ft and an average bank height of 5 ft. The channel bed material ranges from sand to boulder with a median grain size (D50) of 65.7 mm (0.215 ft). The geomorphic assessment at the time of the Level I and Level II site visit on June 5, 1996, indicated that the reach was stable. The Town Highway 30 crossing of the Mill Brook is a 46-ft-long, one-lane covered bridge consisting of a 40-foot wood-beam span (Vermont Agency of Transportation, written communication, March 23, 1995). The opening length of the structure parallel to the bridge face is 36.3 ft. The bridge is supported by vertical, concrete capped laid-up stone abutments with wingwalls. The channel is skewed approximately 10 degrees to the opening while the opening-skew-to-roadway is zero degrees. The only scour protection measure at the site was type-2 stone fill (less than 36 inches diameter) along the upstream right bank, the upstream right wingwall, the right abutment and the downstream left wingwall. 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 Davis, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge was analyzed since it had 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 0.0 to 0.1 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour ranged from 6.0 to 16.0 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 cross-section 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-size distribution. Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Salt-bridge networks within globular and disordered proteins: characterizing trends for designable interactions.

PubMed

Basu, Sankar; Mukharjee, Debasish

2017-07-01

There has been considerable debate about the contribution of salt bridges to the stabilization of protein folds, in spite of their participation in crucial protein functions. Salt bridges appear to contribute to the activity-stability trade-off within proteins by bringing high-entropy charged amino acids into close contacts during the course of their functions. The current study analyzes the modes of association of salt bridges (in terms of networks) within globular proteins and at protein-protein interfaces. While the most common and trivial type of salt bridge is the isolated salt bridge, bifurcated salt bridge appears to be a distinct salt-bridge motif having a special topology and geometry. Bifurcated salt bridges are found ubiquitously in proteins and interprotein complexes. Interesting and attractive examples presenting different modes of interaction are highlighted. Bifurcated salt bridges appear to function as molecular clips that are used to stitch together large surface contours at interacting protein interfaces. The present work also emphasizes the key role of salt-bridge-mediated interactions in the partial folding of proteins containing long stretches of disordered regions. Salt-bridge-mediated interactions seem to be pivotal to the promotion of "disorder-to-order" transitions in small disordered protein fragments and their stabilization upon binding. The results obtained in this work should help to guide efforts to elucidate the modus operandi of these partially disordered proteins, and to conceptualize how these proteins manage to maintain the required amount of disorder even in their bound forms. This work could also potentially facilitate explorations of geometrically specific designable salt bridges through the characterization of composite salt-bridge networks. Graphical abstract ᅟ.

Multilevel cascade voltage source inverter with seperate DC sources

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

1997-01-01

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Multilevel cascade voltage source inverter with seperate DC sources

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

2002-01-01

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Multilevel cascade voltage source inverter with seperate DC sources

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

2001-04-03

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

Multilevel cascade voltage source inverter with separate DC sources

DOEpatents

Peng, F.Z.; Lai, J.S.

1997-06-24

A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations. 15 figs.

Synthesis of concrete bridge piles prestressed with CFRP systems.

DOT National Transportation Integrated Search

2017-06-01

The Texas Department of Transportation frequently constructs prestressed concrete piles for use in bridge : foundations. Such prestressed concrete piles are typically built with steel strands that are highly susceptible to : environmental degradation...

Functional Land Management: Bridging the Think-Do-Gap using a multi-stakeholder science policy interface.

PubMed

O'Sullivan, Lilian; Wall, David; Creamer, Rachel; Bampa, Francesca; Schulte, Rogier P O

2018-03-01

Functional Land Management (FLM) is proposed as an integrator for sustainability policies and assesses the functional capacity of the soil and land to deliver primary productivity, water purification and regulation, carbon cycling and storage, habitat for biodiversity and recycling of nutrients. This paper presents the catchment challenge as a method to bridge the gap between science, stakeholders and policy for the effective management of soils to deliver these functions. Two challenges were completed by a wide range of stakeholders focused around a physical catchment model-(1) to design an optimised catchment based on soil function targets, (2) identify gaps to implementation of the proposed design. In challenge 1, a high level of consensus between different stakeholders emerged on soil and management measures to be implemented to achieve soil function targets. Key gaps including knowledge, a mix of market and voluntary incentives and mandatory measures were identified in challenge 2.

Caisson disease during the construction of the Eads and Brooklyn Bridges: A review.

PubMed

Butler, W P

2004-01-01

The Eads Bridge (St. Louis) and the Brooklyn Bridge (New York City) were testing grounds for caisson construction. These caissons were enormous compressed air boxes used to build riverine piers and abutments anchoring the bridges. Caisson meant faster and cheaper construction, but there was a hidden cost---caisson disease (decompression sickness). Within caissons, workers labored at pressures as high as 55 psig and caisson disease was common. This discourse is a brief history of the caisson, a brief discussion of the illness as viewed in the mid 1800's, and an abbreviated history of the Eads and Brooklyn Bridges. It also provides a detailed description and evaluation of the observations, countermeasures, and recommendations of Dr. Alphonse Jaminet, the Eads Bridge physician, and Dr. Andrew Smith, the Brooklyn Bridge physician, who published reports of their experience in 1871 and 1873, respectively. These and other primary sources permit a detailed examination of early caisson disease and Jaminet's and Smith's thinking also serve as good examples from which to study and learn.

Lateral dynamic interaction analysis of a train girder pier system

NASA Astrophysics Data System (ADS)

Xia, H.; Guo, W. W.; Wu, X.; Pi, Y. L.; Bradford, M. A.

2008-12-01

A dynamic model of a coupled train-girder-pier system is developed in this paper. Each vehicle in a train is modeled with 27 degrees-of-freedom for a 4-axle passenger coach or freight car, and 31 for a 6-axle locomotive. The bridge model is applicable to straight and curved bridges. The centrifugal forces of moving vehicles on curved bridges are considered in both the vehicle model and the bridge model. The dynamic interaction between the bridge and train is realized through an assumed wheel-hunting movement. A case study is performed for a test train traversing two straight and two curved multi-span bridges with high piers. The histories of the train traversing the bridges are simulated and the dynamic responses of the piers and the train vehicles are calculated. A field experiment is carried out to verify the results of the analysis, by which the lateral resonant train speed inducing the peak pier-top amplitudes and some other observations are validated.

Scour assessments and sediment-transport simulation for selected bridge sites in South Dakota

USGS Publications Warehouse

Niehus, C.A.

1996-01-01

Scour at bridges is a major concern in the design of new bridges and in the evaluation of structural stability of existing bridges. Equations for estimating pier, contraction, and abutment scour have been developed from numerous laboratory studies using sand-bed flumes, but little verification of these scour equations has been done for actual rivers with various bed conditions. This report describes the results of reconnaissance and detailed scour assessments and a sediment-transport simulation for selected bridge sites in South Dakota. Reconnaissance scour assessments were done during 1991 for 32 bridge sites. The reconnaissance assessments for each bridge site included compilation of general and structural data, field inspection to record and measure pertinent scour variables, and evaluation of scour susceptibility using various scour-index forms. Observed pier scour at the 32 sites ranged from 0 to 7 feet, observed contraction scour ranged from 0 to 4 feet, and observed abutment scour ranged from 0 to 10 feet. Thirteen bridge sites having high potential for scour were selected for detailed assessments, which were accomplished during 1992-95. These detailed assessments included prediction of scour depths for 2-, 100-, and 500-year flows using selected published scour equations; measurement of scour during high flows; comparison of measured and predicted scour; and identification of which scour equations best predict actual scour. The medians of predicted pier-scour depth at each of the 13 bridge sites (using 13 scour equations) ranged from 2.4 to 6.8 feet for the 2-year flows and ranged from 3.4 to 13.3 feet for the 500-year flows. The maximum pier scour measured during high flows ranged from 0 to 8.5 feet. Statistical comparison (Spearman rank correlation) of predicted pier-scour depths (using flow data col- lected during scour measurements) indicate that the Laursen, Shen (method b), Colorado State University, and Blench (method b) equations correlate closer with measured scour than do the other prediction equations. The predicted pier-scour depths using the Varzeliotis and Carstens equations have weak statistical rela- tions with measured scour depths. Medians of predicted pier-scour depth from the Shen (method a), Chitale, Bata, and Carstens equations are statistically equal to the median of measured pier-scour depths, based on the Wilcoxon signed-ranks test. The medians of contraction scour depth at each of the 13 bridge sites (using one equation) ranged from -0.1 foot for the 2- year flows to 23.2 feet for the 500-year flows. The maximum contraction scour measured during high flows ranged from 0 to 3.0 feet. The contraction- scour prediction equation substantially overestimated the scour depths in almost all comparisons with the measured scour depths. A significant reason for this discrepancy is due to the wide flood plain (as wide as 5,000 feet) at most of the bridge sites that were investigated. One possible way to reduce this effect for bridge design is to make a decision on what is the effective approach section and thereby limit the size of the bridge flow approach width. The medians of abutment-scour depth at each of the 13 bridge sites (using five equations) ranged from 8.2 to 16.5 feet for the 2-year flows and ranged from 5.7 to 41 feet for the 500-year flows. The maximum abutment scour measured during high flows ranged from 0 to 4.0 feet. The abutment-scour prediction equations also substantially overestimated the scour depths in almost all comparisons with the measured scour depths. The Liu and others (live bed) equation predicted abutment-scour depths substantially lower than the other four abutment-scour equations and closer to the actual measured scour depths. However, this equation at times predicted greater scour depths for 2-year flows than it did for 500-year flows, making its use highly questionable. Again, limiting the bridge flow approach width would produce more reasonable predicted abutment scour.

When the human viral infectome and diseasome networks collide: towards a systems biology platform for the aetiology of human diseases

PubMed Central

2011-01-01

Background Comprehensive understanding of molecular mechanisms underlying viral infection is a major challenge towards the discovery of new antiviral drugs and susceptibility factors of human diseases. New advances in the field are expected from systems-level modelling and integration of the incessant torrent of high-throughput "-omics" data. Results Here, we describe the Human Infectome protein interaction Network, a novel systems virology model of a virtual virus-infected human cell concerning 110 viruses. This in silico model was applied to comprehensively explore the molecular relationships between viruses and their associated diseases. This was done by merging virus-host and host-host physical protein-protein interactomes with the set of genes essential for viral replication and involved in human genetic diseases. This systems-level approach provides strong evidence that viral proteomes target a wide range of functional and inter-connected modules of proteins as well as highly central and bridging proteins within the human interactome. The high centrality of targeted proteins was correlated to their essentiality for viruses' lifecycle, using functional genomic RNAi data. A stealth-attack of viruses on proteins bridging cellular functions was demonstrated by simulation of cellular network perturbations, a property that could be essential in the molecular aetiology of some human diseases. Networking the Human Infectome and Diseasome unravels the connectivity of viruses to a wide range of diseases and profiled molecular basis of Hepatitis C Virus-induced diseases as well as 38 new candidate genetic predisposition factors involved in type 1 diabetes mellitus. Conclusions The Human Infectome and Diseasome Networks described here provide a unique gateway towards the comprehensive modelling and analysis of the systems level properties associated to viral infection as well as candidate genes potentially involved in the molecular aetiology of human diseases. PMID:21255393

Bridge effects on light harvesting of a DBfA type polymer system

NASA Astrophysics Data System (ADS)

Sun, Sam-Shajing; Hasib, Muhammad; Gavrilenko, Alexander V.; Devan, Joshua; Gavrilenko, Vladimir

2016-09-01

Plastic optoelectronic materials and thin film devices are very attractive in future optical sensor and solar energy applications due to their lightweight, flexible shape, high photon absorption coefficients, low cost, and environmental benefits. In this study, optoelectronic properties of D, D/fA blend, DfA, and a series of DBfA type of conjugated block copolymers has been investigated, where D is a donor type PPV conjugated block, B is a non-conjugated and flexible aliphatic hydrocarbon bridge chain containing different number of aliphatic methylene units, and fA is a fluorinated acceptor type PPV conjugated block. The optical absorptions of the D/fA blend, DfA, and DBfAs are typical overlaps of individual absorptions of D and fA blocks, while the solution steady state photoluminescence (PL) emission of D were quenched to different levels in blends and block copolymers, with DBfAs containing one methylene unit bridge (DB1fA) quenched most. This could be attributed to an intra-molecular photo induced electron transfer or charge separation in DBfA systems. Theoretical first principles study of the equilibrium atomic configuration of DfA reveals the existence of twisting angles between the D and fA blocks in DfA stable states which may account for a less PL quenching of DfA as compared to DB1fA. These results are important for designing and developing high efficiency polymer based optoelectronic systems.

Synthesis, structure characterization, and anticancer activity of a novel oxygen-bridged tricyclic Biginelli adduct

NASA Astrophysics Data System (ADS)

Ibrahim, Mohamed M.; El-Sheshtawy, Hamdy S.; El-Kemary, Maged; Al-Juaid, Salih; Youssef, Mohamed; El-Azab, Islam H.

2017-06-01

Herein, we report the one-pot cyclization of Biginelli Adduct, ethyl 4-(2-hydroxyphenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (I) to the oxygen-bridged adduct, ethyl 2-methyl-4-thioxo-3,4,5,6-tetrahydro-2H-2,6-methanobenzo[g] [1,3,5]oxadiazocine-11-carboxylate (II) in a high yield and purity under mild reaction condition using zinc(II) perchlorate hexahydrate as a highly efficient catalyst. The cyclic product (II) was characterized both in the solid state and in solution using FT-IR, 1H NMR, and UV-visible spectroscopy. Theoretical calculations using density functional theory with B3LYP/6-311++G(d,p) level were used to further investigate the structure properties. DFT calculations (gas phase) revealed the stability of cyclic compound II (3.45 kcal/mol) than compound I. In addition, the anticancer activity of II was investigated using MCF-7 human breast cell line. The results revealed a moderate activity with 223.55 μg/ml IC50 value.

Analysis of developed transition road safety barrier systems.

PubMed

Soltani, Mehrtash; Moghaddam, Taher Baghaee; Karim, Mohamed Rehan; Sulong, N H Ramli

2013-10-01

Road safety barriers protect vehicles from roadside hazards by redirecting errant vehicles in a safe manner as well as providing high levels of safety during and after impact. This paper focused on transition safety barrier systems which were located at the point of attachment between a bridge and roadside barriers. The aim of this study was to provide an overview of the behavior of transition systems located at upstream bridge rail with different designs and performance levels. Design factors such as occupant risk and vehicle trajectory for different systems were collected and compared. To achieve this aim a comprehensive database was developed using previous studies. The comparison showed that Test 3-21, which is conducted by impacting a pickup truck with speed of 100 km/h and angle of 25° to transition system, was the most severe test. Occupant impact velocity and ridedown acceleration for heavy vehicles were lower than the amounts for passenger cars and pickup trucks, and in most cases higher occupant lateral impact ridedown acceleration was observed on vehicles subjected to higher levels of damage. The best transition system was selected to give optimum performance which reduced occupant risk factors using the similar crashes in accordance with Test 3-21. Copyright © 2013 Elsevier Ltd. All rights reserved.

Bridging the Gap between Physiology and Behavior: Evidence from the sSoTS Model of Human Visual Attention

ERIC Educational Resources Information Center

Mavritsaki, Eirini; Heinke, Dietmar; Allen, Harriet; Deco, Gustavo; Humphreys, Glyn W.

2011-01-01

We present the case for a role of biologically plausible neural network modeling in bridging the gap between physiology and behavior. We argue that spiking-level networks can allow "vertical" translation between physiological properties of neural systems and emergent "whole-system" performance--enabling psychological results to be simulated from…

Adaptive laboratory evolution resolves energy depletion to maintain high aromatic metabolite phenotypes in Escherichia coli strains lacking the Phosphotransferase System.

PubMed

McCloskey, Douglas; Xu, Sibei; Sandberg, Troy E; Brunk, Elizabeth; Hefner, Ying; Szubin, Richard; Feist, Adam M; Palsson, Bernhard O

2018-06-15

Aromatic metabolites provide the backbone for numerous industrial and pharmaceutical compounds of high value. The Phosphotransferase System (PTS) is common to many bacteria, and is the primary mechanism for glucose uptake by Escherichia coli. The PTS was removed to conserve phosphoenolpyruvate (pep), which is a precursor for aromatic metabolites and consumed by the PTS, for aromatic metabolite production. Replicate adaptive laboratory evolution (ALE) of PTS and detailed omics data sets collected revealed that the PTS bridged the gap between respiration and fermentation, leading to distinct high fermentative and high respiratory rate phenotypes. It was also found that while all strains retained high levels of aromatic amino acid (AAA) biosynthetic precursors, only one replicate from the high glycolytic clade retained high levels of intracellular AAAs. The fast growth and high AAA precursor phenotypes could provide a starting host for cell factories targeting the overproduction aromatic metabolites. Copyright © 2018 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Bridging a cultural gap

NASA Astrophysics Data System (ADS)

Leviatan, Talma

2008-09-01

There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmes—aimed at bridging the gap between high-school mathematics and tertiary mathematics—is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of a potential bridging programme, this paper aims at demonstrating that the gap can be bridged, by presenting an ongoing modular bridging programme especially designed for the diverse types of student populations in teachers training colleges. We also present here some innovative teaching and assessment methods that were judged essential for the success of these programmes—focusing mainly on the "Questionnaire Based Instruction Method". Finally we suggest directions of follow up and research.

Networking via wireless bridge produces greater speed and flexibility, lowers cost.

PubMed

1998-10-01

Wireless computer networking. Computer connectivity is essential in today's high-tech health care industry. But telephone lines aren't fast enough, and high-speed connections like T-1 lines are costly. Read about an Ohio community hospital that installed a wireless network "bridge" to connect buildings that are miles apart, creating a reliable high-speed link that costs one-tenth of a T-1 line.

75. Photocopy of photograph (original print in the Minnesota Historical ...

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

75. Photocopy of photograph (original print in the Minnesota Historical Society, St. Paul, Minnesota, ca. 1870s. #22006. Photographer: Illingworth.) VIEW TO SOUTHEAST, SHOWING THE UPPER LEVEE AND BLUSS (on left) TO WHICH THE HIGH BRIDGE WAS BUILT - Smith Avenue High Bridge, Smith Avenue between Cherokee Avenue & Cliff Street, Saint Paul, Ramsey County, MN

Intercultural Communication Barriers and Bridges: Talking with High School Teachers about Multi-Culturalism.

ERIC Educational Resources Information Center

Gougeon, Thomas D.; Hutton, Susan I.

As part of a larger study of school system communication with second language parents in three Alberta (Canada) urban senior high schools, this study focused on analysis of interview data from teachers responding to questions on intercultural communication barriers and bridges with students and immigrant parents. Data were collected through 30…

Structural characterization of UHPC waffle bridge deck and connections : [tech transfer summary].

DOT National Transportation Integrated Search

2014-07-01

Contribute to design an innovative and durable precast deck alternative : using ultra-high performance concrete (UHPC) for accelerated bridge : construction : Evaluate the structural characteristics of the UHPC waffle deck, : critical connect...

Vehicle Signal Analysis Using Artificial Neural Networks for a Bridge Weigh-in-Motion System

PubMed Central

Kim, Sungkon; Lee, Jungwhee; Park, Min-Seok; Jo, Byung-Wan

2009-01-01

This paper describes the procedures for development of signal analysis algorithms using artificial neural networks for Bridge Weigh-in-Motion (B-WIM) systems. Through the analysis procedure, the extraction of information concerning heavy traffic vehicles such as weight, speed, and number of axles from the time domain strain data of the B-WIM system was attempted. As one of the several possible pattern recognition techniques, an Artificial Neural Network (ANN) was employed since it could effectively include dynamic effects and bridge-vehicle interactions. A number of vehicle traveling experiments with sufficient load cases were executed on two different types of bridges, a simply supported pre-stressed concrete girder bridge and a cable-stayed bridge. Different types of WIM systems such as high-speed WIM or low-speed WIM were also utilized during the experiments for cross-checking and to validate the performance of the developed algorithms. PMID:22408487

Vehicle Signal Analysis Using Artificial Neural Networks for a Bridge Weigh-in-Motion System.

PubMed

Kim, Sungkon; Lee, Jungwhee; Park, Min-Seok; Jo, Byung-Wan

2009-01-01

This paper describes the procedures for development of signal analysis algorithms using artificial neural networks for Bridge Weigh-in-Motion (B-WIM) systems. Through the analysis procedure, the extraction of information concerning heavy traffic vehicles such as weight, speed, and number of axles from the time domain strain data of the B-WIM system was attempted. As one of the several possible pattern recognition techniques, an Artificial Neural Network (ANN) was employed since it could effectively include dynamic effects and bridge-vehicle interactions. A number of vehicle traveling experiments with sufficient load cases were executed on two different types of bridges, a simply supported pre-stressed concrete girder bridge and a cable-stayed bridge. Different types of WIM systems such as high-speed WIM or low-speed WIM were also utilized during the experiments for cross-checking and to validate the performance of the developed algorithms.

Monitoring of air pollution levels related to Charilaos Trikoupis Bridge.

PubMed

Sarigiannis, D A; Handakas, E J; Kermenidou, M; Zarkadas, I; Gotti, A; Charisiadis, P; Makris, K; Manousakas, M; Eleftheriadis, K; Karakitsios, S P

2017-12-31

Charilaos Trikoupis bridge is the longest cable bridge in Europe that connects Western Greece with the rest of the country. In this study, six air pollution monitoring campaigns (including major regulated air pollutants) were carried out from 2013 to 2015 at both sides of the bridge, located in the urban areas of Rio and Antirrio respectively. Pollution data were statistically analyzed and air quality was characterized using US and European air quality indices. From the overall campaign, it was found that air pollution levels were below the respective regulatory thresholds, but once at the site of Antirrio (26.4 and 52.2μg/m 3 for PM 2.5 and ΡΜ 10 , respectively) during the 2nd winter period. Daily average PM 10 and PM 2.5 levels from two monitoring sites were well correlated to gaseous pollutant (CO, NO, NO 2 , NO x and SO 2 ) levels, meteorological parameters and factor scores from Positive Matrix Factorization during the 3-year period. Moreover, the elemental composition of PM 10 and PM 2.5 was used for source apportionment. That analysis revealed that major emission sources were sulfates, mineral dust, biomass burning, sea salt, traffic and shipping emissions for PM 10 and PM 2.5 , for both Rio and Antirrio. Seasonal variation indicates that sulfates, mineral dust and traffic emissions increased during the warm season of the year, while biomass burning become the dominant during the cold season. Overall, the contribution of the Charilaos Trikoupis bridge to the vicinity air pollution is very low. This is the result of the relatively low daily traffic volume (~10,000 vehicles per day), the respective traffic fleet composition (~81% of the traffic fleet are private vehicles) and the speed limit (80km/h) which does not favor traffic emissions. In addition, the strong and frequent winds further contribute to the rapid dispersion of the emitted pollutants. Copyright © 2017. Published by Elsevier B.V.

Reducing local scouring at bridge piles using collars and geobags.

PubMed

Akib, Shatirah; Liana Mamat, Noor; Basser, Hossein; Jahangirzadeh, Afshin

2014-01-01

The present study examines the use of collars and geobags for reducing local scour around bridge piles. The efficiency of collars and geobags was studied experimentally. The data from the experiments were compared with data from earlier studies on the use of single piles with a collar and with a geobag. The results showed that using a combination of a steel collar and a geobag yields the most significant scour reduction for the front and rear piles, respectively. Moreover, the independent steel collar showed better efficiency than the independent geobag below the sediment level around the bridge piles.

Reducing Local Scouring at Bridge Piles Using Collars and Geobags

PubMed Central

Akib, Shatirah; Liana Mamat, Noor; Basser, Hossein; Jahangirzadeh, Afshin

2014-01-01

The present study examines the use of collars and geobags for reducing local scour around bridge piles. The efficiency of collars and geobags was studied experimentally. The data from the experiments were compared with data from earlier studies on the use of single piles with a collar and with a geobag. The results showed that using a combination of a steel collar and a geobag yields the most significant scour reduction for the front and rear piles, respectively. Moreover, the independent steel collar showed better efficiency than the independent geobag below the sediment level around the bridge piles. PMID:25247201

Solid-state circuit breaker with current-limiting characteristic using a superconducting coil

DOEpatents

Boenig, H.J.

1982-08-16

A thyristor bridge interposes an ac source and a load. A series connected DC source and superconducting coil within the bridge biases the thyristors thereof so as to permit bidirectional ac current flow therethrough under normal operating conditions. Upon a fault condition a control circuit triggers the thyristors so as to reduce ac current flow therethrough to zero in less than two eyeles and to open the bridge thereafter. Upon a temporary overload condition the control circuit triggers the thyristors so as to limit ac current flow therethrough to an acceptable level.

Solid-state circuit breaker with current limiting characteristic using a superconducting coil

DOEpatents

Boenig, Heinrich J.

1984-01-01

A thyristor bridge interposes an ac source and a load. A series connected DC source and superconducting coil within the bridge biases the thyristors thereof so as to permit bidirectional ac current flow therethrough under normal operating conditions. Upon a fault condition a control circuit triggers the thyristors so as to reduce ac current flow therethrough to zero in less than two cycles and to open the bridge thereafter. Upon a temporary overload condition the control circuit triggers the thyristors so as to limit ac current flow therethrough to an acceptable level.

Effectiveness of a Short, Intense Bridging Course for Scaffolding Students Commencing University-level Study of Chemistry

NASA Astrophysics Data System (ADS)

Schmid, Siegbert; Youl, David J.; George, Adrian V.; Read, Justin R.

2012-05-01

Bridging courses designed to support students commencing tertiary education are widespread, and some evidence for the value of semester-length courses has been reported; however, little attention has been paid to short-but-intense bridging courses, and empirical evidence of their effectiveness is particularly sparse. The current study followed the academic performance of a cohort of students enrolled in a first-year chemistry unit of study designed for those with little or no background knowledge of chemistry. The aims of this study are two-fold: first to determine the strength of the linkage between prior knowledge in chemistry and performance on the end of semester exam, and secondly, to explore the reasons for any differences observed. In particular, the value of the week-long intensive-mode bridging course offered by the University of Sydney was analysed. Quantitative and qualitative data were collected. The research has shown that participation in the chemistry bridging course is associated with 'bridging the gap' in academic performance between students with No Prior Chemistry background and those with a Strong Background. While the content of the bridging course is a significant contributor to academic success, so too is the confidence in their own learning that the course engenders among participants.