Assessment of seismic performance of skew reinforced concrete box girder bridges
NASA Astrophysics Data System (ADS)
Abdel-Mohti, Ahmed; Pekcan, Gokhan
2013-12-01
The seismic vulnerability of highway bridges remains an important problem and has received increased attention as a consequence of unprecedented damage observed during several major earthquakes. A significant number of research studies have examined the performance of skew bridges under service and seismic loads. The results of these studies are particularly sensitive to modeling assumptions in view of the interacting parameters. In the present study, three-dimensional improved beam-stick models of two-span highway bridges with skew angles varying from 0° to 60° are developed to investigate the seismic response characteristics of skew box girder bridges. The relative accuracy of beam-stick models is verified against counterpart finite element models. The effect of various parameters and conditions on the overall seismic response was examined such as skew angle, ground motion intensity, soil condition, abutment support conditions, bridge aspect ratio, and foundation-base conditions. The study shows that the improved beam-stick models can be used to conduct accurate nonlinear time history analysis of skew bridges. Skew angle and interacting parameters were found to have significant effect on the behavior of skewed highway bridges. Furthermore, the performance of shear keys may have a predominant effect on the overall seismic response of the skew bridges.
Construction engineering of steel tub-girder bridge systems for skew effects
NASA Astrophysics Data System (ADS)
Jimenez Chong, Juan Manuel
Closed structural sections, such as those having circular, rectangular or trapezoidal shape, possess high rotational rigidity when compared to open sections such as I-girders. The high torsional rigidity of closed sections makes them ideal for use in highly curved bridges. In this case, the geometry of the bridge results in large torsional forces. Because of structural efficiency and economy reasons, most of these closed-section bridges consist of a trapezoidal cross-section, with a top concrete slab and bottom and side steel plates. The slab is cast after the steel is erected and thus a system of internal diaphragms and braces is necessary to stabilize the system during erection. During the steel erection and the early stages of the concrete deck placement, the section can be considered as quasi-closed as the top concrete flange has not been cast or is not yet effective. During steel erection, undetermined and/or large torsional forces and/or displacements may result in fit-up problems requiring large stresses to overcome. During concrete deck placement, the undetermined displacements can affect the control of the deck thickness and the final deck geometry, such as the alignment of deck joints and the matching of stages in phased constructions projects. Due to the interactions between their various components, the behavior of curved and skewed tub-girder bridges is significantly more complex than that of straight bridges. When skewed supports are used in tub-girders, the interaction of the girder bending rotations and the displacement constraints induced by the skewed support diaphragms causes twisting of the girders at the supports. These twist rotations introduce additional torques into the system. Both curvature and skew can cause design and construction difficulties, especially at the supports, where the corresponding steel dead load deflections and the large torsional stiffness of the girders may lead to large fit-up forces. Currently, the general understanding of the level of sophistication of analysis models required to properly predict forces and deformations of curved and/or skewed bridges during construction is limited. The development of guidelines regarding the sufficiency of simplified methods of structural analysis is the overall motivation and objective of this dissertation. This research addresses the construction load effects due to skew and due to combined skew and curvature and develops design recommendations and analytical tools for the construction engineering of tub-girder bridges. The effects of skew and curvature are studied by examining the results for different levels of analysis for 18 representative bridges. These bridges reflect the range of bridge curvature and skew used in current practice. By comparing the output from simplified analysis methods to validated refined 3D FEA solutions, general conclusions are developed as to when the simplified methods provide sufficient results. An important original contribution of this research is that the data generated constitutes the first systematic study on a large set of curved and skewed tub-girder bridges using consistent refined 3D FEA models to model construction forces and deformations. As such, the results of this research can serve as a benchmark for current and future improvements in methods of analysis and design for the construction engineering of curved and skewed tub-girder bridges. In the current research, this data has been used in both straight and curved tub-girder bridges to: • Develop a simplified 1D analysis method to account for the effect of skew on girder twist rotations and internal torques, • Evaluate the effect of skew on component forces, and propose improved simplified procedures to capture these effects, • Identify interactions between components and develop improved simplified analysis methods to account for these effects, • Establish limits for when the improved 1D and 2D simplified methods of analysis are sufficient for construction engineering analysis, and • Identify sources of steel erection fit-up proble
Evaluating the performance of skewed prestressed concrete bridge after strengthening
NASA Astrophysics Data System (ADS)
Naser, Ali; Zonglin, Wang
2013-06-01
The objectives of this paper are to explain the application of repairing and strengthening methods on the damaged members of the bridge structure, to analyze the static and dynamic structural response under static and dynamic loads after strengthening, and to evaluate the structural performance after application of strengthening method. The repairing and strengthening methods which are used in this study include treatment of the cracks, thickening the web of box girder along the bridge length and adding internal pre-stressing tendons in the thickening web, and construct reinforced concrete cross beams (diaphragms) between two box girders. The results of theoretical analysis of static and dynamic structural responses after strengthening show that the tensile stresses are decreased and become less than the allowable limit values in the codes. The values of vertical deflection are decreased after strengthening. The values of natural frequencies after strengthening are increased, indicating that the strengthening method is effective to reduce the vibration of the bridge structure. Therefore, the strengthening methods are effective to improve the bearing capacity and elastic working state of the bridge structure and to increase the service life of the bridge structure.
NASA Astrophysics Data System (ADS)
Ghotbi, Abdoulreza
This study aims to investigate the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Both deterministic (i.e., pushover and nonlinear dynamic analyses) and probabilistic approaches were utilized. A set of response sensitivity analyses was performed considering various skew angles, column elements, and soil properties for bridge considered both as fixed-base and SSI models. It has been observed that as the skew angle increased, the bridge responded more severely to the ground motion. For instance, the deck rotation and shear-keys displacement increased with an increase in the skew angle. A modal pushover analysis was also performed in conjunction with the nonlinear dynamic analysis. It has been found that combining the bridge responses for various modes of vibration resulted in a relatively accurate seismic response compared to the nonlinear dynamic analysis while saving time and analysis cost, to a great extent. A probabilistic analysis was also performed considering record-to-record variability in ground motion, and a set of probabilistic seismic demand and fragility plots was generated. The effects of change in the skew angle and also SSI were studied to see various bridge responses. The damage probability increased especially with respect to deck rotation as the skew angle increased. The SSI had a decreasing effect on the overall response of the bridge with pile foundation.
Load distribution effects and repair procedures for existing skewed plate girder bridges
Crozier, Allen R
1992-01-01
by the presence of diaphragms. Present thinking in the bridge engineering community now questions the need for diaphragms except for constructability. It has been suggested that temporary diaphragms be used during construction, but be removed after the bridge... has been built. This thesis follows the format of the Journal of Structural En ineerin , American Society of Civil Engineers. Typically the girders of a straight, non-horizontally curved bridge with diaphragm members would be designed the same...
NASA Astrophysics Data System (ADS)
Ghotbi, Abdoul R.
2014-09-01
The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation, shear keys failure, abutment unseating and column-bent drift. This research, therefore, aims to study the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Due to several sources of uncertainty associated with the ground motions, soil and structure, a probabilistic approach is needed. Thus, a probabilistic methodology similar to the one developed by the Pacific Earthquake Engineering Research Center (PEER) has been utilized to assess the probability of damage due to various levels of shaking using appropriate intensity measures with minimum dispersions. The probabilistic analyses were performed for various bridge configurations and site conditions, including sand ranging from loose to dense and clay ranging from soft to stiff, in order to evaluate the effects. The results proved a considerable susceptibility of skewed bridges to deck rotation and shear keys displacement. It was also found that SSI had a decreasing effect on the damage probability for various demands compared to the fixed-base model without including SSI. However, deck rotation for all types of the soil and also abutment unseating for very loose sand and soft clay showed an increase in damage probability compared to the fixed-base model. The damage probability for various demands has also been found to decrease with an increase of soil strength for both sandy and clayey sites. With respect to the variations in the skew angle, an increase in skew angle has had an increasing effect on the amplitude of the seismic response for various demands. Deck rotation has been very sensitive to the increase in the skew angle; therefore, as the skew angle increased, the deck rotation responded accordingly. Furthermore, abutment unseating showed an increasing trend due to an increase in skew angle for both fixed-base and SSI models.
Ioannis Vayas; Theodoros Adamakos; Aristidis Iliopoulos
2011-01-01
A new improved way for modeling steel composite straight bridges has been presented (Vayas, 2009; Vayas, 2010). The proposed\\u000a model is based on the representation of steel I-girders through the use of equivalent trusses. The concrete slab is suitably\\u000a represented by a set of bar elements. Diaphragms and stiffeners may also be taken into account. In contrast to the grillage
Bridges from top to bottom: Expressway Bridge, Liberty Memorial Bridge, Burlington Northern SantaFe Railway Bridge, and Interstate 94 Grant Marsh Bridge. Photo taken by USGS personnel on a Civil Air Patrol flight....
K. Lingaiah; S. T. Murthy
1991-01-01
Results are presented of a photoelastic study of skew plates commonly employed in machine members and structures such as parts of airplane wings, missiles, ship decks and floor slabs of skew bridges and buildings. The investigation involved skew sandwich plates made of Araldite varying in width from 80 mm to 40 mm and skew angle varying from 0 to 40
NSDL National Science Digital Library
2011-05-26
In this activity, students adjust the median and standard deviation of a skewed Gaussian distribution. Then they can create a histogram from that distribution. This activity allows students to explore the idea of a skewed distribution. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.
NSDL National Science Digital Library
2012-07-19
Bridges come in a wide variety of sizes, shapes, and lengths and are found all over the world. It is important that bridges are strong so they are safe to cross. Design and build a your own model bridge. Test your bridge for strength using a force sensor that measures how hard you pull on your bridge. By observing a graph of the force, determine the amount of force needed to make your bridge collapse.
Bridges A bridge, also known as a fixed removable denture, is made to replace one or more missing teeth. Bridges can be supported in any of three ways: ... a combination of teeth and implants A traditional bridge is made by creating a crown for the ...
NSDL National Science Digital Library
Leske, Cavin.
Bridges have been drawing plenty of attention lately, with numerous construction projects around the world and the controversy over the deteriorating bridge infrastructure in the US. They have been an essential part of transportation for hundreds of years, and it is the job of civil engineers to design the safest, most durable bridges possible.Bridge Basics (1) has a large list of different types of bridges with brief explanations. This is a good place for beginners to learn about various bridge designs and parts. The Web site of a nationwide engineering design contest (2) offers free West Point Bridge Designer software. This educational tool allows the user to create a custom virtual bridge model. Although this year's contest is over, another one is planned for next year. Rice University is the home of the Bridges Project (3), a comprehensive database of "all 74 1,000 ft. span bridges in the United States." For each of these, a short description and construction history are given, and some include photos and other interesting facts. The Gibraltar Bridge, a proposed nine mile bridge that connects Europe and Africa, was recently featured on the Discovery Channel's Engineering the Impossible (4). This Web site discusses its specifications, as well as the many challenges that must be overcome for it to be a reality. The Innovative Bridge Research and Construction Program (5) investigates new technologies that can be used in the "repair, rehabilitation, replacement and new construction of bridges" in the US. This is particularly important now, since a large portion of the countries bridges are badly in need of maintenance. A more specific area of research being conducted to protect bridge infrastructure involves the corrosion of steel reinforcements in concrete bridges (6). The material on this site provides an in-depth report on the findings of the Turner-Fairbank Highway Research Center. Technical reports and papers are published in the bimonthly Journal of Bridge Engineering (7). It covers almost any topic related to bridges, and is offered free online by the American Society of Civil Engineers. Fun activities for grade school students are given on this page (8). Separated into three levels of difficulty, the projects give students freedom to learn about and design any kind of bridge structure that interests them. A list of materials and criteria are given, but there are few explicit instructions, allowing for maximum creativity.
NSDL National Science Digital Library
Integrated Teaching and Learning Program,
Through a five-lesson series that includes numerous hands-on activities, students are introduced to the importance and pervasiveness of bridges for connecting people to resources, places and other people, with references to many historical and current-day examples. In learning about bridge types—arch, beam, truss and suspension—students explore the effect of tensile and compressive forces. Students investigate the calculations that go into designing bridges; they learn about loads and cross-sectional areas by designing and testing the strength of model piers. Geology and soils are explored as they discover the importance of foundations, bearing pressure and settlement considerations in the creation of dependable bridges and structures. Students learn about brittle and ductile material properties. Students also learn about the many cost factors that comprise the economic considerations of bridge building. Bridges are unique challenges that take advantage of the creative nature of engineering.
C. Cuell; G. W. Patrick
2007-04-27
Skew critical problems occur in continuous and discrete nonholonomic Lagrangian systems. They are analogues of constrained optimization problems, where the objective is differentiated in directions given by an apriori distribution, instead of tangent directions to the constraint. We show semiglobal existence and uniqueness for nondegenerate skew critical problems, and show that the solutions of two skew critical problems have the same contact as the problems themselves. Also, we develop some infrastructure that is necessary to compute with contact order geometrically, directly on manifolds.
Clock Skew Scheduling with Delay Padding for Prescribed Skew Domains
Chuan Lin; Hai Zhou
2007-01-01
Clock skew scheduling is a technique that intentionally in- troduces skews to memory elements to improve the perfor- mance of a sequential circuit. It was shown in (21) that the full optimization potential of clock skew scheduling can be reliably implemented using a few skew domains. In this paper we present an optimal skew scheduling algorithm for sequential circuits with
NASA Astrophysics Data System (ADS)
Audenaert, Koenraad M. R.
2014-11-01
In this paper, we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.
Physical aware clock skew rescheduling
Xinjie Wei; Yici Cai; Xianlong Hong
2007-01-01
Yield driven skew scheduling method leads to a clock tree with much greater wire length and buffer number that is not acceptable by designer. Geometry based register position relationships are converted to skew constraints and are combined with timing constraints harmoniously. With the two kinds of skew constraints together, our algorithm solves the skew scheduling problem for both restrictions and
NASA Astrophysics Data System (ADS)
Lingaiah, K.; Murthy, S. T.
Results are presented of a photoelastic study of skew plates commonly employed in machine members and structures such as parts of airplane wings, missiles, ship decks and floor slabs of skew bridges and buildings. The investigation involved skew sandwich plates made of Araldite varying in width from 80 mm to 40 mm and skew angle varying from 0 to 40 deg with a 10 x 10 mm skewed cutout located at the center of the flat plate subjected to inplane loads offset from the centroidal axis of the plates. The maximum tangential stress was found to increase at critical point A around cutout boundary on the maximum stress face of the plate as the eccentricity increases for various values of skew angles and different cutout-to-width ratios. The minimum stress occurs on the minimum stress face of the skew plate at critical point C. The stress concentration factor decreases at C with an increase in eccentricity for various values of cutout-to-width ratios and skew angles.
Koenraad M. R. Audenaert
2014-08-30
In this paper we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by L. Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.
Skew resisting hydrodynamic seal
William T. Conroy; Lannie L. Dietle; Jeffrey D. Gobeli; Manmohan S. Kalsi
2001-01-01
A novel hydrodynamically lubricated compression type rotary seal that is suitable for lubricant retention and environmental exclusion. Particularly, the seal geometry ensures constraint of a hydrodynamic seal in a manner preventing skew-induced wear and provides adequate room within the seal gland to accommodate thermal expansion. The seal accommodates large as-manufactured variations in the coefficient of thermal expansion of the sealing
Hendrickson, B.; Leland, R. [Sandia National Labs., Albuquerque, NM (United States); Van Driessche, R. [Alcatel Telecom, Antwerp (Belgium)
1997-02-01
Graph partitioning is an important abstraction used in solving many scientific computing problems. Unfortunately, the standard partitioning model does not incorporate considerations that are important in many settings. We address this by describing a generalized partitioning model which incorporates the notion of partition skew and is applicable to a variety of problems. We then develop enhancements to several important partitioning algorithms necessary to solve the generalized partitioning problem. Finally we demonstrate the benefit of employing several of these generalized methods to static decomposition of parallel computing problems.
Barry C. Arnold; Robert J. Beaver
2000-01-01
Suppose (X,Y) has a (k+1)-dimensional Cauchy distribution. Consider the conditional distribution of X given Y>y0, for some fixed value of y0?R. The resulting distribution is the multivariate skewed Cauchy, in which there is truncation with respect to Y: this is but one of a general class of skewed distributions for which the initial distribution is symmetric. The skewing function, which
Measuring Skewness: A Forgotten Statistic?
ERIC Educational Resources Information Center
Doane, David P.; Seward, Lori E.
2011-01-01
This paper discusses common approaches to presenting the topic of skewness in the classroom, and explains why students need to know how to measure it. Two skewness statistics are examined: the Fisher-Pearson standardized third moment coefficient, and the Pearson 2 coefficient that compares the mean and median. The former is reported in statistical…
Skewed Rotation Symmetry Group Detection
Seungkyu Lee; Yanxi Liu
2010-01-01
Abstract—We present a novel and effective algorithm for affinely skewed,rotation symmetry,group detection from real-world images. We define a complete,skewed,rotation symmetry,detection problem,as discovering,five independent,properties of a skewed,rotation symmetry,group: (1) the center of rotation; (2) the affine deformation; (3) the type of the symmetry,group; (4) the cardinality of the symmetry,group; and (5) the supporting,region of the symmetry,group in the image. We propose,a
Multivariate measures of skewness for the skew-normal distribution
N. Balakrishnan; Bruno Scarpa
2012-01-01
The main objective of this work is to calculate and compare different measures of multivariate skewness for the skew-normal family of distributions. For this purpose, we consider the Mardia (1970)Â [10], Malkovich and Afifi (1973) [9], Isogai (1982)Â [17], Srivastava (1984) [15], Song (2001) [14], Móri etÂ al. (1993) [11], Balakrishnan etÂ al. (2007) [3] and Kollo (2008) [7] measures
Skew resisting hydrodynamic seal
Conroy, William T. (Pearland, TX); Dietle, Lannie L. (Sugar Land, TX); Gobeli, Jeffrey D. (Houston, TX); Kalsi, Manmohan S. (Houston, TX)
2001-01-01
A novel hydrodynamically lubricated compression type rotary seal that is suitable for lubricant retention and environmental exclusion. Particularly, the seal geometry ensures constraint of a hydrodynamic seal in a manner preventing skew-induced wear and provides adequate room within the seal gland to accommodate thermal expansion. The seal accommodates large as-manufactured variations in the coefficient of thermal expansion of the sealing material, provides a relatively stiff integral spring effect to minimize pressure-induced shuttling of the seal within the gland, and also maintains interfacial contact pressure within the dynamic sealing interface in an optimum range for efficient hydrodynamic lubrication and environment exclusion. The seal geometry also provides for complete support about the circumference of the seal to receive environmental pressure, as compared the interrupted character of seal support set forth in U.S. Pat. Nos. 5,873,576 and 6,036,192 and provides a hydrodynamic seal which is suitable for use with non-Newtonian lubricants.
Skew grids and irrotational flow
NASA Astrophysics Data System (ADS)
Bernard, Robert S.
1988-03-01
Finite-difference computation of incompressible flow through regions of arbitrary shape often requires the implementation of boundary-fitted coordinates for which the grid lines may be non-orthogonal (skew). When the governing equations are expressed in terms of pressure and velocity, conservation of mass is maintained by the gradient of the pressure. In principle, the gradient is irrotational and should have no effect on the existing circulation in the flow field; but if the grid lines are skew, the discrete representation of the gradient can generate spurious vorticity near the boundaries. In the present work this difficulty is eliminated for uniform skew grids, and markedly reduced for non-uniform skew grids, by adopting a discrete formulation of the pressure gradient that helps maintain irrotationality near boundaries. The procedure is applicable for staggered grids with either Poisson or Chorin equations for pressure.
Skewed rotation symmetry group detection.
Lee, Seungkyu; Liu, Yanxi
2010-09-01
We present a novel and effective algorithm for affinely skewed rotation symmetry group detection from real-world images. We define a complete skewed rotation symmetry detection problem as discovering five independent properties of a skewed rotation symmetry group: 1) the center of rotation, 2) the affine deformation, 3) the type of the symmetry group, 4) the cardinality of the symmetry group, and 5) the supporting region of the symmetry group in the image. We propose a frieze-expansion (FE) method that transforms rotation symmetry group detection into a simple, 1D translation symmetry detection problem. We define and construct a pair of rotational symmetry saliency maps, complemented by a local feature method. Frequency analysis, using Discrete Fourier Transform (DFT), is applied to the frieze-expansion patterns (FEPs) to uncover the types (cyclic, dihedral, and O2), the cardinalities, and the corresponding supporting regions, concentric or otherwise, of multiple rotation symmetry groups in an image. The phase information of the FEP is used to rectify affinely skewed rotation symmetry groups. Our result advances the state of the art in symmetry detection by offering a unique combination of region-based, feature-based, and frequency-based approaches. Experimental results on 170 synthetic and natural images demonstrate superior performance of our rotation symmetry detection algorithm over existing methods. PMID:20634559
ON SKEW PRIMENESS OF INNER FUNCTIONS
Fuhrmann, Paul A.
ON SKEW PRIMENESS OF INNER FUNCTIONS matrices is extended to the context of inner functions. Skew primeness is related to a geometric of a lin* *ear transformation, when does it have a complementary invariant subspace. Moreover, given
Practical Skew Handling in Parallel Joins
David J. Dewitt; Jeffrey F. Naughton; Donovan A. Schneider; S. Seshadri
1992-01-01
We present an approach to dealing with skew in parallel joins in database systems.Our approach is easily implementable within current parallel DBMS, and performs well onskewed data without degrading the performance of the system on non-skewed data. Themain idea is to use multiple algorithms, each specialized for a different degree of skew, and touse a small sample of the relations
Kinematic correction for roller skewing
NASA Technical Reports Server (NTRS)
Savage, M.; Loewenthal, S. H.
1980-01-01
A theory of kinematic stabilization of rolling cylinders is developed for high-speed cylindrical roller bearings. This stabilization requires race and roller crowning to product changes in the rolling geometry as the roller shifts axially. These changes put a reverse skew in the rolling elements by changing the rolling taper. Twelve basic possible bearing modifications are identified in this paper. Four have single transverse convex curvature in the rollers while eight have rollers with compound transverse curvature composed of a central cylindrical band of constant radius surrounded by symmetric bands with both slope and transverse curvature.
Roller skewing measurements in cylindrical roller bearings
NASA Technical Reports Server (NTRS)
Nypan, L. J.
1981-01-01
Measurements of roller skewing in a 118 mm bore roller bearing operating at shaft speeds to 12,000 rpm are reported. High speed motion pictures of a modified roller were taken through a derotation prism to record skewing as the roller moved through loaded and unloaded regions of the bearing. Subsequent frame by frame measurement of the photographic film provided information on roller skewing. Radial and tangential skew amplitudes of 0.4 to 0.5 degrees were observed with 0.5 degree misalignment.
Predicted and Measured Performance of Prestressed Concrete Bridges
Chun S. Cai; Mohsen Shahawy
2004-01-01
Testing results of six existing prestressed concrete bridges are used to evaluate analytical methodologies. These bridges cover different span lengths, number of lanes, and skew angles. Strains, load distribution factors, and ratings predicted by finite-element analyses and AASHTO code specifications are compared with those from measurements. The comparison reveals a significant difference between the analytical and test results due to
Graf, Darin C. (Edgewood, NM); Warpinski, Norman R. (Albuquerque, NM)
1996-01-01
A system for single-phase, steady-state permeability measurements of porous rock utilizes a fluid bridge arrangement analogous to a Wheatstone bridge. The arms of the bridge contain the sample and calibrated flow resistors.
Development of a baseline model for a steel girder bridge using remote sensing and load tests
Kaoshan Dai; Shen-En Chen; Jeremy Scott; Marcus Schmieder; Wanqiu Liu; Edd Hauser
2011-01-01
A new skewed two span continuous steel girder bridge was constructed and opened to traffic recently. This bridge uses high performance steel (HPS 100W) in the flanges of the negative moment region over the intermediate pier. For construction verification and long-term structural health monitoring purposes, a finite element (FE) model was developed for the bridge superstructure. Various field tests were
Portfolio optimization with skewness and kurtosis
NASA Astrophysics Data System (ADS)
Lam, Weng Hoe; Jaaman, Saiful Hafizah Hj.; Isa, Zaidi
2013-04-01
Mean and variance of return distributions are two important parameters of the mean-variance model in portfolio optimization. However, the mean-variance model will become inadequate if the returns of assets are not normally distributed. Therefore, higher moments such as skewness and kurtosis cannot be ignored. Risk averse investors prefer portfolios with high skewness and low kurtosis so that the probability of getting negative rates of return will be reduced. The objective of this study is to compare the portfolio compositions as well as performances between the mean-variance model and mean-variance-skewness-kurtosis model by using the polynomial goal programming approach. The results show that the incorporation of skewness and kurtosis will change the optimal portfolio compositions. The mean-variance-skewness-kurtosis model outperforms the mean-variance model because the mean-variance-skewness-kurtosis model takes skewness and kurtosis into consideration. Therefore, the mean-variance-skewness-kurtosis model is more appropriate for the investors of Malaysia in portfolio optimization.
Modeling Skewness in Human Transcriptomes
Casellas, Joaquim; Varona, Luis
2012-01-01
Gene expression data are influenced by multiple biological and technological factors leading to a wide range of dispersion scenarios, although skewed patterns are not commonly addressed in microarray analyses. In this study, the distribution pattern of several human transcriptomes has been studied on free-access microarray gene expression data. Our results showed that, even in previously normalized gene expression data, probe and differential expression within probe effects suffer from substantial departures from the commonly assumed symmetric Gaussian distribution. We developed a flexible mixed model for non-competitive microarray data analysis that accounted for asymmetric and heavy-tailed (Student’s t distribution) dispersion processes. Random effects for gene expression data were modeled under asymmetric Student’s t distributions where the asymmetry parameter (?) took values from perfect symmetry (??=?0) to right- (?>0) or left-side (?>0) over-expression patterns. This approach was applied to four free-access human data sets and revealed clearly better model performance when comparing with standard approaches accounting for traditional symmetric Gaussian distribution patterns. Our analyses on human gene expression data revealed a substantial degree of right-hand asymmetry for probe effects, whereas differential gene expression addressed both symmetric and left-hand asymmetric patterns. Although these results cannot be extrapolated to all microarray experiments, they highlighted the incidence of skew dispersion patterns in human transcriptome; moreover, we provided a new analytical approach to appropriately address this biological phenomenon. The source code of the program accommodating these analytical developments and additional information about practical aspects on running the program are freely available by request to the corresponding author of this article. PMID:22701729
Modeling skewness in human transcriptomes.
Casellas, Joaquim; Varona, Luis
2012-01-01
Gene expression data are influenced by multiple biological and technological factors leading to a wide range of dispersion scenarios, although skewed patterns are not commonly addressed in microarray analyses. In this study, the distribution pattern of several human transcriptomes has been studied on free-access microarray gene expression data. Our results showed that, even in previously normalized gene expression data, probe and differential expression within probe effects suffer from substantial departures from the commonly assumed symmetric gaussian distribution. We developed a flexible mixed model for non-competitive microarray data analysis that accounted for asymmetric and heavy-tailed (Student's t distribution) dispersion processes. Random effects for gene expression data were modeled under asymmetric Student's t distributions where the asymmetry parameter (?) took values from perfect symmetry (??=?0) to right- (?>0) or left-side (?>0) over-expression patterns. This approach was applied to four free-access human data sets and revealed clearly better model performance when comparing with standard approaches accounting for traditional symmetric gaussian distribution patterns. Our analyses on human gene expression data revealed a substantial degree of right-hand asymmetry for probe effects, whereas differential gene expression addressed both symmetric and left-hand asymmetric patterns. Although these results cannot be extrapolated to all microarray experiments, they highlighted the incidence of skew dispersion patterns in human transcriptome; moreover, we provided a new analytical approach to appropriately address this biological phenomenon. The source code of the program accommodating these analytical developments and additional information about practical aspects on running the program are freely available by request to the corresponding author of this article. PMID:22701729
NSDL National Science Digital Library
Museum of Science and Industry, Chicago
2012-01-01
Learners design, build and test a model bridge out of straws. The bridge must span 25 cm across a gap between two tables or two chairs. To measure the load, the bridge must securely hold a small cup. Learners test the load by placing as many pennies in the cup as possible and counting how many the bridge can hold.
An Analytical Evaluation of Distortion-Induced Fatigue in Steel Bridges
Hassel, Heidi L.
2011-02-04
................................................................................................................................... 4 Distortion-Induced Fatigue Retrofit Techniques ...................................................................................................... 5 Stiffening or Softening Out-Of-Plane Connection Elements... ON DISTORTION-INDUCED FATIGUE IN SKEWED STEEL BRIDGES Abstract........................................................................................................................................................................ 17 1: Introduction...
Extraction of skewed parton distributions from experiment
Andreas Freund
1999-05-04
In this paper we will discuss algorithms for extracting skewed parton distributions (SPD's) from experiment as well as the relevant process and experimental observable suitable for the extraction procedure.
Skewness and large-scale structure
NASA Astrophysics Data System (ADS)
Coles, Peter; Frenk, Carlos S.
1991-12-01
The evolution of the skewness of the cosmological mass distribution into the nonlinear regime is discussed. Various analytical estimates of the skewness of initially Gaussian (i.e., unskewed) density perturbations are compared with each other, with N-body results, and with real clustering data. In general, the skewness is simply related to the rms mass fluctuation on the scale in question. The relationship can be used to construct a simple but potentially powerful test of the hypothesis that large-scale structure in the universe evolved from Gaussian initial conditions. The measured skewness of the QDOT-redshift-survey density distribution is compatible with the gravitational evolution of sufficiently high-amplitude Gaussian fluctuations. There is therefore no need to invoke non-Gaussian initial fluctuations to explain these data. The role of discreteness (i.e., shot noise) effects upon the interpretation of cell-count statistics is also discussed.
Autoregresive conditional volatility, skewness and kurtosis
Ángel León; Gonzalo Rubio; Gregorio Serna
2005-01-01
This paper proposes a GARCH-type model allowing for time-varying volatility, skewness and kurtosis. The model is estimated assuming a Gram–Charlier (GC) series expansion of the normal density function for the error term, which is easier to estimate than the non-central t distribution proposed by [Harvey, C. R. & Siddique, A. (1999). Autorregresive Conditional Skewness. Journal of Financial and Quantitative Analysis
On the Construction of Skew Quasi-Cyclic Codes
Taher Abualrub; Ali Ghrayeb; Nuh Aydin; Irfan Siap
2008-01-01
In this paper we study a special type of quasi-cyclic (QC) codes called skew QC codes. This set of codes is constructed using a non- commutative ring called the skew polynomial rings F(x; ). After a brief description of the skew polynomial ring F(x; ) it is shown that skew QC codes are left submodules of the ring Rls =
NSDL National Science Digital Library
IEEE
2013-08-30
In this activity, learners explore how engineering has impacted the development of bridges over time, including innovative designs and the challenge of creating bridges that become landmarks for a city. Learners work in teams of "engineers" to design and build their own bridge out of glue and popsicle sticks. Learners test their bridges using weights, evaluate their results, and present their findings to the group.
NSDL National Science Digital Library
2012-06-23
In this engineering activity, learners investigate the differences between the strength of bridges made from flat and round building materials. They construct simple bridges out of linguine, which has a rectangular shape, and spaghetti, which has a circular shape. They then test and compare the weight capacity of the bridges.
Graf, D.C.; Warpinski, N.R.
1996-08-13
A system is described for single-phase, steady-state permeability measurements of porous rock which utilizes a fluid bridge arrangement analogous to a Wheatstone bridge. The arms of the bridge contain the sample and calibrated flow resistors. 8 figs.
NSDL National Science Digital Library
2014-09-18
Students learn about the types of possible loads, how to calculate ultimate load combinations, and investigate the different sizes for the beams (girders) and columns (piers) of simple bridge design. Students learn the steps that engineers use to design bridges: understanding the problem, determining the potential bridge loads, calculating the highest possible load, and calculating the amount of material needed to resist the loads.
Factor Analysis for Skewed Data and Skew-Normal Maximum Likelihood Factor Analysis
Gaucher, Beverly Jane
2013-04-04
and Main Properties . . . . . . . . . . . . . . . 15 2.4.3 Spherical Distributions and Elliptical Distributions . . . . 16 2.4.4 The Multivariate Elliptically Contoured Distribution . . . 17 2.4.5 The Unified Skew-Elliptical Distribution... SKEWED DISTRIBUTIONS 44 3.1 Selection Distributions . . . . . . . . . . . . . . . . . . . . . . . . 44 3.2 Selection Factor Models . . . . . . . . . . . . . . . . . . . . . . . . 45 3.3 Selection Factor Models for Elliptically Contoured and Gaussian...
NSDL National Science Digital Library
2002-01-01
"The Digital Bridges Web site consists of a collection of thirty representative 19th century American bridge engineering monographs, manuals, and documents from the Lehigh University Libraries' Special Collections." The archive provides an interesting retrospective into the beginnings of major bridge projects; the material is complete with high-resolution photographs and text scanned from original books. In addition to historical literature, Digital Bridges also features brief accounts of notable people and companies that influenced bridge construction across the country. A glossary of terms commonly used in the documents is also provided.
Skew chicane based betatron eigenmode exchange module
Douglas, David (Yorktown, VA)
2010-12-28
A skewed chicane eigenmode exchange module (SCEEM) that combines in a single beamline segment the separate functionalities of a skew quad eigenmode exchange module and a magnetic chicane. This module allows the exchange of independent betatron eigenmodes, alters electron beam orbit geometry, and provides longitudinal parameter control with dispersion management in a single beamline segment with stable betatron behavior. It thus reduces the spatial requirements for multiple beam dynamic functions, reduces required component counts and thus reduces costs, and allows the use of more compact accelerator configurations than prior art design methods.
NSDL National Science Digital Library
Worcester Polytechnic Institute
2013-01-01
Learners explore the field of civil engineering by making a bridge using spaghetti as their primary building material. Then they test their bridges to see how much weight they can carry before breaking. This activity allows learners to engage in the entire engineering process as they design, build, test, then discuss their bridges. Resource includes investigating questions to extend learning. Time estimated for activity can be split across multiple meetings.
Thermal postbuckling analysis of FGM skew plates
T. Prakash; M. K. Singha; M. Ganapathi
2008-01-01
In this paper, the postbuckling behavior of functionally graded material (FGM) skew plates under thermal load is investigated based on the shear deformable finite element approach. The material is graded in the thickness direction according to a power-law distribution in terms of the volume fractions of the constituents. The Mori–Tanaka homogenization method is used to estimate the effective material properties
Irreducible complex skew-Berger algebras
Anton S. Galaev
2008-01-01
Irreducible skew-Berger algebras $\\\\g\\\\subset\\\\gl(n,\\\\Co)$, i.e. algebras spanned by the images of the linear maps $R:\\\\odot^2\\\\Co^n\\\\to\\\\g$ satisfying the Bianchi identity, are classified. These Lie algebras can be interpreted as irreducible complex Berger superalgebras contained in $\\\\gl(0|n,\\\\Co)$.
Irreducible complex skew-Berger algebras
Anton S. Galaev
2009-01-01
Irreducible skew-Berger algebras g?gl(n,C), i.e. algebras spanned by the images of the linear maps R:?2Cn?g satisfying the Bianchi identity, are classified. These Lie algebras can be interpreted as irreducible complex Berger superalgebras contained in gl(0|n,C).
Skewness correction in automatic license plate recognition
NASA Astrophysics Data System (ADS)
Huttunen, Heikki J.
2005-03-01
Improvement of the accuracy of an automatic car license plate recognition system is studied. The recognition system has been installed in several ports, factories and national borders around Europe and Middle East. The paper describes the anatomy of a portable version of the recognition system, in which the requirements are different from a fixed installation. For example, the portable system recognizes the license plates with no external triggers (such as inductive loops) and the installation is left to the end-user. The placement of the recognition camera in such systems is often a compromise and cannot be fully controlled. The system learns the characteristics of the setup and tries to correct the imperfections that are due to the installation by a non-expert. One of the main problems is the angle in which the camera is looking at the road, which causes the plate and the characters appear skewed. This paper proposes an algorithm for cancelling the skewness effect. The skewness parameters can be estimated from the earlier recognition results, and the proposed system learns to correct the skewness resulting in improved recognition results. The improvement of the recognition accuracy is illustrated by experiments with an annotated database of license plate images.
NLO evolution kernels for skewed transversity distributions
A. V. Belitsky; A. Freund; D. Müller
2000-08-03
We present a calculation of the two-loop evolution kernels of the twist-two transversally polarized quark and linearly polarized gluon skewed parton distributions in the minimal subtraction scheme and discuss a solution of the evolution equations suitable for numerical implementations.
On the construction of skew quasi-cyclic codes
Taher Abualrub; Ali Ghrayeb; Nuh Aydin; Irfan Siap
2010-01-01
In this paper, we study a special type of quasi-cyclic (QC) codes called skew QC codes. This set of codes is constructed using a noncommutative ring called the skew polynomial ring F[x;¿]. After a brief description of the skew polynomial ring F[x;¿], it is shown that skew QC codes are left submodules of the ring Rsl=( F[x;¿]\\/(xs-1) )l. The notions
NSDL National Science Digital Library
Integrated Teaching and Learning Program,
Working as engineering teams, students design and create model beam bridges using plastic drinking straws and tape as their construction materials. Their goal is to build the strongest bridge with a truss pattern of their own design, while meeting the design criteria and constraints. They experiment with different geometric shapes and determine how shapes affect the strength of materials. Let the competition begin!
Skewness as a test for Quartessence
R. R. R. Reis; M. Makler; I. Waga
2004-03-16
Quartessence is one of the alternatives to Lambda-CDM that has lately attracted considerable interest. According to this unifying dark matter/energy scenario, the Universe evolved from an early non-relativistic matter-dominated phase to a more recent accelerated expansion phase, driven by a single fluid component. Recently, it has been shown that some problems of the quartessence model, such as the existence of instabilities and oscillations in the matter power spectrum, can be avoided if a specific type of intrinsic entropy perturbation is considered. In the present article we explore the role of skewness in constraining this non-adiabatic scenario. We show that non-adiabatic quartessence and quintessence have different signatures for the skewness of the density distribution on large scales and suggest that this quantity might prove helpful to break possible degeneracies between them.
Analysis of Parasite and Other Skewed Counts
Alexander, Neal
2012-01-01
Objective To review methods for the statistical analysis of parasite and other skewed count data. Methods Statistical methods for skewed count data are described and compared, with reference to those used over a ten year period of Tropical Medicine and International Health. Two parasitological datasets are used for illustration. Results Ninety papers were identified, 89 with descriptive and 60 with inferential analysis. A lack of clarity is noted in identifying measures of location, in particular the Williams and geometric mean. The different measures are compared, emphasizing the legitimacy of the arithmetic mean for skewed data. In the published papers, the t test and related methods were often used on untransformed data, which is likely to be invalid. Several approaches to inferential analysis are described, emphasizing 1) non-parametric methods, while noting that they are not simply comparisons of medians, and 2) generalized linear modelling, in particular with the negative binomial distribution. Additional methods, such as the bootstrap, with potential for greater use are described. Conclusions Clarity is recommended when describing transformations and measures of location. It is suggested that non-parametric methods and generalized linear models are likely to be sufficient for most analyses. PMID:22943299
... flow enough that myocardial ischemia develops, especially during exercise or when the heart is beating quickly. What are the symptoms? Up to one-third of patients with a myocardial bridge do not have any ...
... dose regimen, for example, enoxaparin (Lovenox) 1 mg/kg twice daily, is often used in North America, ... allocated to receive bridging anticoagulation (dalteparin 100 IU/kg twice daily) or matching placebo when warfarin is ...
NSDL National Science Digital Library
2012-12-13
Play with your food while learning about engineering! Build a spaghetti bridge, then test its strength by piling on the marshmallows, raw spaghetti, raw linguine and coins. Investigate the difference between the strength of bridges made from flat and round building materials (spaghetti is round, while linguine is flat). Learn by doing that circles are among the strongest shapes in nature, and that external and internal stress distributes itself evenly throughout a round structure.
Inferring climate variability from skewed proxy records
NASA Astrophysics Data System (ADS)
Emile-Geay, J.; Tingley, M.
2013-12-01
Many paleoclimate analyses assume a linear relationship between the proxy and the target climate variable, and that both the climate quantity and the errors follow normal distributions. An ever-increasing number of proxy records, however, are better modeled using distributions that are heavy-tailed, skewed, or otherwise non-normal, on account of the proxies reflecting non-normally distributed climate variables, or having non-linear relationships with a normally distributed climate variable. The analysis of such proxies requires a different set of tools, and this work serves as a cautionary tale on the danger of making conclusions about the underlying climate from applications of classic statistical procedures to heavily skewed proxy records. Inspired by runoff proxies, we consider an idealized proxy characterized by a nonlinear, thresholded relationship with climate, and describe three approaches to using such a record to infer past climate: (i) applying standard methods commonly used in the paleoclimate literature, without considering the non-linearities inherent to the proxy record; (ii) applying a power transform prior to using these standard methods; (iii) constructing a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting the skewness in the proxy leads to erroneous conclusions and often exaggerates changes in climate variability between different time intervals. In contrast, an explicit treatment of the skewness, using either power transforms or a Bayesian inversion of the mechanistic model for the proxy, yields significantly better estimates of past climate variations. We apply these insights in two paleoclimate settings: (1) a classical sedimentary record from Laguna Pallcacocha, Ecuador (Moy et al., 2002). Our results agree with the qualitative aspects of previous analyses of this record, but quantitative departures are evident and hold implications for how such records are interpreted, and compared to other proxy records. (2) a multiproxy reconstruction of temperature over the Common Era (Mann et al., 2009), where we find that about one third of the records display significant departures from normality. Accordingly, accounting for skewness in proxy predictors has a notable influence on both reconstructed global mean and spatial patterns of temperature change. Inferring climate variability from skewed proxy records thus requires cares, but can be done with relatively simple tools. References - Mann, M. E., Z. Zhang, S. Rutherford, R. S. Bradley, M. K. Hughes, D. Shindell, C. Ammann, G. Faluvegi, and F. Ni (2009), Global signatures and dynamical origins of the little ice age and medieval climate anomaly, Science, 326(5957), 1256-1260, doi:10.1126/science.1177303. - Moy, C., G. Seltzer, D. Rodbell, and D. Anderson (2002), Variability of El Niño/Southern Oscillation activ- ity at millennial timescales during the Holocene epoch, Nature, 420(6912), 162-165.
Dimensions of Attractors in Pinched Skew Products
NASA Astrophysics Data System (ADS)
Gröger, M.; Jäger, T.
2013-05-01
We study dimensions of strange non-chaotic attractors and their associated physical measures in so-called pinched skew products, introduced by Grebogi and his coworkers in 1984. Our main results are that the Hausdorff dimension, the pointwise dimension and the information dimension are all equal to one, although the box-counting dimension is known to be two. The assertion concerning the pointwise dimension is deduced from the stronger result that the physical measure is rectifiable. Our findings confirm a conjecture by Ding, Grebogi and Ott from 1989.
The b-u skewed parton distributions
P. Kroll
2000-03-10
The b - u skewed parton distributions (SPDs) are discussed. The SPDs allow an unambigous superposition of overlap and resonsance contributions and their zeroth order moments represent the B - pi transition form factors. The values of the form factors at maximum recoil are found to be F+(0)=F0(0)=0.22 with an error of 0.05 in agreement with measurements of the B - pi pi branching ratio. The branching ratios for the semi-leptonic B - pi decays are evaluated too.
Strong GC and AT Skew Correlation in Chicken Genome
Xuegong Deng; Xuemei Deng; Ilkka Havukkala
2007-01-01
Chicken genome AT and GC skews for individual chromosomes were visualized simultaneously using a novel method of 2-dimensional\\u000a color-coded pixel matrix. The visualizations were compared to those of human, mouse and possum genomes. A strikingly strong\\u000a correlation of AT skew and GC from small to large scale in chicken genome was found, compared to the other vertebrates. Some\\u000a local skew
Sequential Skewing: An Improved Skewing Algorithm Soumya Ray sray@cs.wisc.edu
Ray, Soumya
. While greedy learning strategies have many advanÂ tages, they are known to su#er from myopia optimal choices. The myopia of greedy learning strategies such as topÂ down decision tree learners has an approach called Skewing (Page & Ray, 2003), which attempts to alÂ leviate the myopia of greedy tree
Sequential Skewing: An Improved Skewing Algorithm Soumya Ray sray@cs.wisc.edu
Ray, Soumya
greedy learning strategies have many advan- tages, they are known to suffer from myopia. This refers optimal choices. The myopia of greedy learning strategies such as top- down decision tree learners has an approach called Skewing (Page & Ray, 2003), which attempts to al- leviate the myopia of greedy tree
Multivariate Skew-t Distributions in Econometrics and Environmetrics
Marchenko, Yulia V.
2012-02-14
likelihood estimators for this model. We compare the performance of the selection-t model to the Heckman selection model and apply it to analyze ambulatory expenditures. iv In the second article we introduce a family of multivariate log-skew-elliptical dis... prop- erties. We demonstrate, for example, that as for the log-t distribution, the positive moments of the log-skew-t distribution do not exist. Our emphasis is on two special cases, the log-skew-normal and log-skew-t distributions, which we use...
Phylogenetic skew: an index of community diversity.
Chen, Hungyen; Shao, Kwang-Tsao; Kishino, Hirohisa
2015-02-01
The distribution of divergence times between member species of a community reflects the pattern of species composition. In this study, we contrast the species composition of a community against the meta-community, which we define as the species composition of a set of target communities. We regard the collection of species that comprise a community as a sample from the set of member species of the meta-community, and interpret the pattern of the community species composition in terms of the type of species sampled from the meta-community. A newly defined effective species sampling proportion explains the amount of the difference between the divergence time distributions of the community and that of the meta-community, assuming random sampling. We propose a new index of phylogenetic skew (PS), as the ratio of the maximum-likelihood estimate of the effective species sampling proportion to the observed sampling proportion. A PS value of 1 is interpreted as random sampling. If the value is >1, the sampling is suspected to be phylogenetically skewed. If it is <1, systematic thinning of species is likely. Unlike other indices, the PS does not depend on species richness as long as the community has more than a few members of a species. Because it is possible to compare partially observed communities, the index may be effectively used in exploratory analysis to detect candidate communities with unique species compositions from a large number of communities. PMID:25580733
GC skew and mitochondrial origins of replication.
Sahyoun, Abdullah H; Bernt, Matthias; Stadler, Peter F; Tout, Kifah
2014-07-01
The comprehensive understanding of mitochondrial genome evolution requires a detailed mechanistic picture of mitogenomic replication. Despite many previous efforts it has remained a non-trivial problem to determine the origins of replication and trace their fate across rearrangements of the gene order even in the small genomes of animal mitochondria. We elaborate here on the observation that the GC skew is correlated with the distance from the replication origins. This effect has been explained as a consequence of the standard model of mitochondrial DNA replication, i.e. the strand displacement model. According to this model chemical damage accumulates proportional to the duration that DNA is exposed in single-stranded form during replication (Dssh) which depends on the relative position with respect to the replication origins. Based on this model we developed a computational method to infer the positions of both the heavy strand and the light strand origin from nucleotide skew data. In a comprehensive survey of deuterostome mitochondria we infer conserved replication origins for the vast majority of vertebrates and cephalochordates. Deviations from the consensus picture are presumably associated with genome rearrangements. PMID:24911382
Temperature-Compensated Clock Skew Adjustment
Castillo-Secilla, Jose María; Palomares, Jose Manuel; Olivares, Joaquín
2013-01-01
This work analyzes several drift compensation mechanisms in wireless sensor networks (WSN). Temperature is an environmental factor that greatly affects oscillators shipped in every WSN mote. This behavior creates the need of improving drift compensation mechanisms in synchronization protocols. Using the Flooding Time Synchronization Protocol (FTSP), this work demonstrates that crystal oscillators are affected by temperature variations. Thus, the influence of temperature provokes a low performance of FTSP in changing conditions of temperature. This article proposes an innovative correction factor that minimizes the impact of temperature in the clock skew. By means of this factor, two new mechanisms are proposed in this paper: the Adjusted Temperature (AT) and the Advanced Adjusted Temperature (A2T). These mechanisms have been combined with FTSP to produce AT-FTSP and A2T-FTSP Both have been tested in a network of TelosB motes running TinyOS. Results show that both AT-FTSP and A2T-FTSP improve the average synchronization errors compared to FTSP and other temperature-compensated protocols (Environment-Aware Clock Skew Estimation and Synchronization for WSN (EACS) and Temperature Compensated Time Synchronization (TCTS)). PMID:23966192
Bridged graphite oxide materials
NASA Technical Reports Server (NTRS)
Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)
2010-01-01
Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.
NSDL National Science Digital Library
2014-04-25
In this engineering activity, challenge learners to construct a paper bridge that can support 100 pennies. Learners discover how they can make a weak material like paper strong enough to support a load pennies by changing the shape of the paper (by rolling, crumpling or folding it).
ERIC Educational Resources Information Center
Murfin, Brian
2000-01-01
Describes the famous swing bridge in Belize. Students build bridges from a variety of materials and answer the questions, What are different types of bridges?, How do bridges work?, How can you tell if a bridge design will be safe?, and What is the best way to build a bridge over a river while still allowing boat traffic? (SAH)
Bridge Inspector's Training Manual.
ERIC Educational Resources Information Center
Federal Highway Administration (DOT), Washington, DC. Bureau of Public Roads.
A guide for the instruction of bridge inspectors is provided in this manual as well as instructions for conducting and reporting on a bridge inspection. The chapters outline the qualifications necessary to become a bridge inspector. The subject areas covered are: The Bridge Inspector, Bridge Structures, Bridge Inspection Reporting System,…
Digital Bridges: Bridges of the Nineteenth Century
NSDL National Science Digital Library
2002-01-01
The collection consists of thirty representative 19th-century American bridge engineering monographs, manuals, and documents from the Lehigh University Libraries' Special Collections. The source documents have been scanned, converted to text, and partially corrected to make all significant terms and personal and proper names retrievable through the site's search engine. Topics include specific bridges (the Brooklyn Bridge, the East River Bridge), bridge types (suspension bridges, wrought iron bridges), bridge components (cabling, foundations), bridge design, bridge disasters, and others. The collection is browseable by title and searchable by keyword. Printable versions of the documents are also available. A glossary is also provided with definitions of terms, short biographies of authors, and descriptions of some of the bridges
Fertility signalling and reproductive skew in queenless ants
Virginie Cuvillier-Hot; Alain Lenoir; Robin Crewe; Christian Malosse; Christian Peeters
2004-01-01
Social insects often show an extreme reproductive skew. In queenless ants, colonies consist of morphologically identical workers that can all potentially reproduce sexually. Similarly to that in social vertebrates, aggression in these ants functions to select the reproductive(s). We investigated the mechanisms underlying reproductive skew in the monogynous queenless ant Streblognathus peetersi. Behavioural observations of disturbed hierarchies were integrated with
A Method for Controlling Skew on Linked Surfaces
BENZLEY,STEVEN E.; KERR,ROBERT A.; MITCHELL,SCOTT A.; WHITE,DAVID R.
1999-09-27
A new method for lessening skew in mapped meshes is presented. This new method involves progressive subdivision of a surface into loops consisting of four sides. Using these loops, constraints can then be set on the curves of the surface, which will propagate interval assignments across the surface, allowing a mesh with a better skew metric to be generated.
ON THE SPECTRUM OF SKEW-SHIFT SCHRODINGER HELGE KRUGER
Krueger, Helge
ON THE SPECTRUM OF SKEW-SHIFT SCHRÂ¨ODINGER OPERATORS HELGE KRÂ¨UGER Abstract. I prove that the spectrum of a skew-shift SchrÂ¨odinger operator contains larges interval in the semi-classical regime-classical regime, that is for h > 0 sufficiently small, I will show that the spectrum of the operator Hh contains
Skewed Base Compositions, Asymmetric Transition Matrices, and Phylogenetic Invariants
Sankoff, David
Skewed Base Compositions, Asymmetric Transition Matrices, and Phylogenetic Invariants V. FERRETTI a class of semigroups Sc containing matrices of form |1\\p=n-\\acaa1\\p=n-\\ca|toaccount for A+T versus G+C as models for evolution where the phylogenetic inference problem involves species with skewed (AT-rich or AT
An Upper Bound on Expected Clock Skew in Synchronous Systems
Steven D. Kugelmass; Kenneth Steiglitz
1990-01-01
A statistical model is considered for clock skew in which the propagation delays on every source-to-processor path are sums of independent contributions, and are identically distributed. Upper bounds are derived for expected skew, and its variance, in tree distribution systems with N synchronously clocked processing elements. The results are applied to two special cases of clock distribution. In the first,
Skewed parton distributions and wide-angle exclusive scattering
P. Kroll
2000-11-22
The overlap representation of skewed parton distributions is discussed and applications to wide-angle Compton scattering and electroproduction of mesons are presented. The amplitudes for these processes factorise into parton-level subprocess amplitudes and form factors representing 1/x-moments of skewed parton distributions.
Analysis of carbon dioxide concentration skewness at a rural site.
Pérez, Isidro A; Sánchez, M Luisa; García, M Ángeles; Ozores, Marta; Pardo, Nuria
2014-04-01
This paper provides evidence that symmetry of CO2 concentration distribution may indicate sources or dispersive processes. Skewness was calculated by different procedures with CO2 measured at a rural site using a Picarro G1301 analyser over a two-year period. The usual skewness coefficient was considered together with fourteen robust estimators. A noticeable contrast was obtained between day and night, and skewness decreased linearly with the logarithm of the height. One coefficient was selected from its satisfactory relationship with the median concentration in daily evolution. Three analyses based on the kernel smoothing method were conducted with this coefficient to investigate its response to yearly and daily evolutions, wind direction, and wind speed. Left-skewed distributions were linked to thermal turbulence during midday, especially in spring-summer, or with high wind speeds. Almost symmetric distributions were associated with sources, such as the Valladolid City plume reinforced with spring emissions and the lack of emissions in summer in the remaining directions. Finally, right-skewed distributions were related to low wind speeds and stable stratification at night, furthered by strong emissions in spring. Skewness intervals were proposed and their average median concentrations were calculated such that the relationship between skewness and concentration depends on the analysis performed. Since some skewness coefficients may also be negative, they provide better information about sources or dispersive processes than concentration. PMID:24463252
Graded D-branes and skew categories
NASA Astrophysics Data System (ADS)
Lazaroiu, Calin I.
2007-08-01
I describe extended gradings of open topological field theories in two dimensions in terms of skew categories, proving a result which alows one to translate between the formalism of graded open 2d TFTs and equivariant cyclic categories. As an application of this formalism, I describe the open 2d TFT of graded D-branes in Landau-Ginzburg models in terms of an equivariant cyclic structure on the triangulated category of `graded matrix factorizations' introduced by Orlov. This leads to a specific conjecture for the Serre functor on the latter, which generalizes results known from the minimal and Calabi-Yau cases. I also give a description of the open 2d TFT of such models which manifestly displays full grading induced by the vector-axial R-symmetry group.
NSDL National Science Digital Library
Twin Cities Public Television, Inc.
2008-01-01
This is a quick activity (on page 2 of the PDF) about how the arrangement of carbon atoms determines carbon's different properties. Learners will build bridges with Post-It notes that model two types of carbon molecules, graphite and carbon nanotubes, and test which structure of the same material can bear the weight of the most pennies. Also relates to linked video, DragonflyTV Nano: Hockey Sticks.
ERIC Educational Resources Information Center
Tabor, Josh
2010-01-01
On the 2009 AP[c] Statistics Exam, students were asked to create a statistic to measure skewness in a distribution. This paper explores several of the most popular student responses and evaluates which statistic performs best when sampling from various skewed populations. (Contains 8 figures, 3 tables, and 4 footnotes.)
Development of a baseline model for a steel girder bridge using remote sensing and load tests
NASA Astrophysics Data System (ADS)
Dai, Kaoshan; Chen, Shen-En; Scott, Jeremy; Schmieder, Marcus; Liu, Wanqiu; Hauser, Edd
2011-04-01
A new skewed two span continuous steel girder bridge was constructed and opened to traffic recently. This bridge uses high performance steel (HPS 100W) in the flanges of the negative moment region over the intermediate pier. For construction verification and long-term structural health monitoring purposes, a finite element (FE) model was developed for the bridge superstructure. Various field tests were performed to verify the model: 1) LiDAR scan, 2) static truck load tests, and 3) Laser doppler vibrometer testing. LiDAR scanner was introduced to gain geometrical information of the bridge in the real world. It was also used to measure girder deflections during load tests. The fundamental frequency of the bridge vibration was obtained by using a Laser doppler vibrometer. Both dynamic and static measurements are then used to update the FE model. This valid bridge superstructure FE model was provided to local DOT bridge engineers with the completion of this study.
Female reproductive synchrony predicts skewed paternity across primates
Nunn, Charles L.; Schülke, Oliver
2008-01-01
Recent studies have uncovered remarkable variation in paternity within primate groups. To date, however, we lack a general understanding of the factors that drive variation in paternity skew among primate groups and across species. Our study focused on hypotheses from reproductive skew theory involving limited control and the use of paternity “concessions” by investigating how paternity covaries with the number of males, female estrous synchrony, and rates of extragroup paternity. In multivariate and phylogenetically controlled analyses of data from 27 studies on 19 species, we found strong support for a limited control skew model, with reproductive skew within groups declining as female reproductive synchrony and the number of males per group increase. Of these 2 variables, female reproductive synchrony explained more of the variation in paternity distributions. To test whether dominant males provide incentives to subordinates to resist matings by extragroup males, that is, whether dominants make concessions of paternity, we derived a novel prediction that skew is lower within groups when threat from outside the group exists. This prediction was not supported as a primary factor underlying patterns of reproductive skew among primate species. However, our approach revealed that if concessions occur in primates, they are most likely when female synchrony is low, as these conditions provide alpha male control of paternity that is assumed by concessions models. Collectively, our analyses demonstrate that aspects of male reproductive competition are the primary drivers of reproductive skew in primates. PMID:19018288
NSDL National Science Digital Library
2010-01-01
In this interactive game, students build bridges using fractional lengths in the form of fraction bars. Gap length may be known or unknown, entirely empty or partially filled. Fractions to fill the gap must be constructed in specific ways, using the four basic operations. After five tries at one level, the game resets. Note that the game sometimes expects particular answers: students may need to multiply 2/5 by 3 rather than multiplying 3/5 by 2, for example, even though both computations would produce the same result.
NSDL National Science Digital Library
This web page describes different aspects of designing bridges. It relates the concept of bridge designing with the real life scenarios. It also includes some bridges around the world and gives some specifications of them.
Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices
ERIC Educational Resources Information Center
Glaister, P.
2008-01-01
The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.
Bicriterion seriation methods for skew-symmetric matrices.
Brusco, Michael J; Stahl, Stephanie
2005-11-01
The decomposition of an asymmetric proximity matrix into its symmetric and skew-symmetric components is a well-known principle in combinatorial data analysis. The seriation of the skew-symmetric component can emphasize information corresponding to the sign or absolute magnitude of the matrix elements, and the choice of objective criterion can have a profound impact on the ordering. In this research note, we propose a bicriterion approach for seriation of a skew-symmetric matrix incorporating both sign and magnitude information. Two numerical demonstrations reveal that the bicriterion procedure is an effective alternative to direct seriation of the skew-symmetric matrix, facilitating favourable trade-offs among sign and magnitude information. PMID:16293204
The Overlap Representation of Skewed Quark and Gluon Distributions
M. Diehl; Th. Feldmann; R. Jakob; P. Kroll
2001-02-20
Within the framework of light-cone quantisation we derive the complete and exact overlap representation of skewed parton distributions for unpolarised and polarised quarks and gluons. Symmetry properties and phenomenological applications are discussed.
Flow in Rotating Serpentine Coolant Passages With Skewed Trip Strips
NASA Technical Reports Server (NTRS)
Tse, David G.N.; Steuber, Gary
1996-01-01
Laser velocimetry was utilized to map the velocity field in serpentine turbine blade cooling passages with skewed trip strips. The measurements were obtained at Reynolds and Rotation numbers of 25,000 and 0.24 to assess the influence of trips, passage curvature and Coriolis force on the flow field. The interaction of the secondary flows induced by skewed trips with the passage rotation produces a swirling vortex and a corner recirculation zone. With trips skewed at +45 deg, the secondary flows remain unaltered as the cross-flow proceeds from the passage to the turn. However, the flow characteristics at these locations differ when trips are skewed at -45 deg. Changes in the flow structure are expected to augment heat transfer, in agreement with the heat transfer measurements of Johnson, et al. The present results show that trips are skewed at -45 deg in the outward flow passage and trips are skewed at +45 deg in the inward flow passage maximize heat transfer. Details of the present measurements were related to the heat transfer measurements of Johnson, et al. to relate fluid flow and heat transfer measurements.
ON POLYNOMIAL STABILITY FOR SKEW-EVOLUTION SEMIFLOWS ON BANACH SPACES
Boyer, Edmond
for skew-evolution semiflows in the nonuniform setting arises as natural, relative to the third variable in the nonuniform case. 2. Skew-evolution semiflows This section gives the notion of skew-evolution semiflowON POLYNOMIAL STABILITY FOR SKEW-EVOLUTION SEMIFLOWS ON BANACH SPACES CODRUTÂ¸A STOICA Abstract
NSDL National Science Digital Library
This wonderful site, provided by NOVA Online, brings to life the engineering challenges inherent to bridge-building. Designed for those who want the challenge, the site offers four bridging scenarios (with photos): "a 5,000-foot span across an ocean bay where huge ships come and go, ... a 700-foot span across a deep canyon gorge," and two others. A step-by-step tutorial teaches about four different bridge types (arch, beam, suspension, and cable-stayed), after which the user may select a bridge type for each scenario. The site is enhanced by links to other bridge resources, such as the famous bridge-building disaster of the century (Tacoma Narrows Bridge) and the Golden Gate Bridge site, which in turn, links users to other famous bridges including Japan's brand new Akashi Kaikyo Bridge, the longest bridge in the world.
Sample Skewness as a Statistical Measurement of Neuronal Tuning Sharpness
Samonds, Jason M.; Potetz, Brian R.; Lee, Tai Sing
2014-01-01
We propose using the statistical measurement of the sample skewness of the distribution of mean firing rates of a tuning curve to quantify sharpness of tuning. For some features, like binocular disparity, tuning curves are best described by relatively complex and sometimes diverse functions, making it difficult to quantify sharpness with a single function and parameter. Skewness provides a robust nonparametric measure of tuning curve sharpness that is invariant with respect to the mean and variance of the tuning curve and is straightforward to apply to a wide range of tuning, including simple orientation tuning curves and complex object tuning curves that often cannot even be described parametrically. Because skewness does not depend on a specific model or function of tuning, it is especially appealing to cases of sharpening where recurrent interactions among neurons produce sharper tuning curves that deviate in a complex manner from the feedforward function of tuning. Since tuning curves for all neurons are not typically well described by a single parametric function, this model independence additionally allows skewness to be applied to all recorded neurons, maximizing the statistical power of a set of data. We also compare skewness with other nonparametric measures of tuning curve sharpness and selectivity. Compared to these other nonparametric measures tested, skewness is best used for capturing the sharpness of multimodal tuning curves defined by narrow peaks (maximum) and broad valleys (minima). Finally, we provide a more formal definition of sharpness using a shape-based information gain measure and derive and show that skewness is correlated with this definition. PMID:24555451
NSDL National Science Digital Library
2014-09-18
Students are presented with a brief history of bridges as they learn about the three main bridge types: beam, arch and suspension. They are introduced to two natural forces — tension and compression — common to all bridges and structures. Throughout history, and today, bridges are important for connecting people to resources, places and other people. Students become more aware of the variety and value of bridges around us in our everyday lives.
Significant reproductive skew in the facultatively polygynous ant Pheidole pallidula.
Fournier, D; Aron, S; Keller, L
2004-01-01
Reproductive skew - the extent to which reproduction is unevenly shared between individuals in a social group - varies greatly between and within animal species. In this study, we investigated how queens share parentage in polygynous (multiple queen) colonies of the Mediterranean ant Pheidole pallidula. We used highly polymorphic microsatellites markers to determine parentage of gynes (new queens), males and workers in P. pallidula field colonies. The comparison of the genotypes of young and adult workers revealed a very low queen turnover (less than 2%). The first main finding of the study of reproductive skew in these colonies was that there was a significant departure from equal contribution of queens to gyne, male and worker production. Reproductive skew was greater for male production than for queen and worker production. There was no relationship between the magnitude of the reproductive skew and the number of reproductive queens per colony, their relatedness and the overall colony productivity, some of the factors predicted to influence the extent of reproductive skew. Finally, our study revealed for the first time a trade-off in the relative contribution of nestmate queens to gyne and worker production. The queens contributing more to gyne production contributed significantly less to worker production. PMID:14653800
Bridging consent: from toll bridges to lift bridges?
2011-01-01
Background The ability to share human biological samples, associated data and results across disease-specific and population-based human research biobanks is becoming increasingly important for research into disease development and translation. Although informed consent often does not anticipate such cross-domain sharing, it is important to examine its plausibility. The purpose of this study was to explore the feasibility of bridging consent between disease-specific and population-based research. Comparative analyses of 1) current ethical and legal frameworks governing consent and 2) informed consent models found in disease-specific and population-based research were conducted. Discussion Ethical and legal frameworks governing consent dissuade cross-domain data sharing. Paradoxically, analysis of consent models for disease-specific and population-based research reveals such a high degree of similarity that bridging consent could be possible if additional information regarding bridging was incorporated into consent forms. We submit that bridging of consent could be supported if current trends endorsing a new interpretation of consent are adopted. To illustrate this we sketch potential bridging consent scenarios. Summary A bridging consent, respectful of the spirit of initial consent, is feasible and would require only small changes to the content of consents currently being used. Under a bridging consent approach, the initial data and samples collection can serve an identified research project as well as contribute to the creation of a resource for a range of other projects. PMID:21970509
Konrad Zilch; Hermann Weiher; Mathias Riesemann
This article gives an overview over the state of the art of concrete bridges in Germany. In addition to the presentation of actual bridges projects (e.g. winners of German bridge award) new trends in bridge construction and post-tensioning technology will be presented. One is prestressing by combining unbonded internal and external tendons which already had been realized at the pilot-projects
Minimal Skew Clock Embedding Considering Time Variant Temperature Gradient
He, Lei
- ing points can be shifted with presence of the temperature gradient. As a result, it requires a clockMinimal Skew Clock Embedding Considering Time Variant Temperature Gradient Hao Yu, Yu Hu, Chunchen-aware clock embedding assumes a time-invariant temperature gradient. However, it is not solved how to find
Making Skew-Resistant Fabrics For Composite Layups
NASA Technical Reports Server (NTRS)
Farley, Gary L.
1994-01-01
Fabrics used in curved composite-material structures prevented from skewing during composite layup by weaving them in modified process in which warp and fill yarns bonded together at their points of contact. (Bonding concept may prove similarly beneficial for braided and knitted fabrics.) In modified weaving process, adhesives prevent excessive shifting of warp and fill yarns with respect to each other.
Electronic skewing circuit monitors exact position of object underwater
NASA Technical Reports Server (NTRS)
Roller, R.; Yaroshuk, N.
1967-01-01
Linear Variable Differential Transformer /LVDT/ electronic skewing circuit guides a long cylindrical capsule underwater into a larger tube so that it does not contact the tube wall. This device detects movement of the capsule from a reference point and provides a continuous signal that is monitored on an oscilloscope.
The Pill skews natural instincts BY NATASHA RUDRA
Lummaa, Virpi
The Pill skews natural instincts BY NATASHA RUDRA 08 Oct, 2009 08:07 AM Birth control pills could emerging evidence, including a study of lap dancers, shows the pill has an impact on women's ability a woman's oestrogen levels, the pill could change a woman's mating preferences. She could be less
Skewed Parton Distributions in Real and Virtual Compton Scattering
M. Diehl; T. Feldmann; R. Jakob; P. Kroll
1999-06-24
The handbag contribution to Compton scattering at moderately large momentum transfer factorises into parton-photon subprocess amplitudes and new form factors representing 1/x-moments of skewed parton distributions. A detailed phenomenological study for polarised and unpolarised real and virtual Compton scattering is presented
PERSPECTIVES Biodiversity loss, trophic skew and ecosystem functioning
Duffy, J. Emmett
IDEAS AND PERSPECTIVES Biodiversity loss, trophic skew and ecosystem functioning J. Emmett Duffy biodiversity effects on ecosystem functioning have been criticized on the basis that their random impacts of biodiversity change on ecosystem functioning appear to be trophically mediated, with important
Arc voltage distribution skewness as an indicator of electrode gap during vacuum arc remelting
Williamson, R.L.; Zanner, F.J.; Grose, S.M.
1998-01-13
The electrode gap of a VAR is monitored by determining the skewness of a distribution of gap voltage measurements. A decrease in skewness indicates an increase in gap and may be used to control the gap. 4 figs.
Cluster Rendering of Skewed Datasets via Visualization Keke Chen Ling Liu
Liu, Ling
Cluster Rendering of Skewed Datasets via Visualization Keke Chen Ling Liu College of Computing clustering approach with visualization techniques, aiming at the datasets that have skewed cluster information visualization methods into the clustering process in order to enhance the understanding
PHASE RESPONSE CURVE SKEWNESS CONTROLS NETWORK SYNCHRONY Ramana Dodla and Charles J.Wilson
Dodla, Ramana
that are associated with motor function disorders such as Parkinson's disease. Introduction Inhibitory Network Type-1 with skewness. Large skewness can thus cause a network to become asynchronous. We test this result here among
Arakawa, Kazuharu; Tomita, Masaru
2007-01-01
Circular bacterial chromosomes have highly polarized nucleotide composition in the two replichores, and this genomic strand asymmetry can be visualized using GC skew graphs. Here we propose and discuss the GC skew index (GCSI) for the quantification of genomic compositional skew, which combines a normalized measure of fast Fourier transform to capture the shape of the skew graph and Euclidean distance between the two vertices in a cumulative skew graph to represent the degree of skew. We calculated GCSI for all available bacterial genomes, and GCSI correlated well with the visibility of GC skew. This novel index is useful for estimating confidence levels for the prediction of replication origin and terminus by methods based on GC skew and for measuring the strength of replicational selection in a genome. PMID:19461976
A low nasal bridge is a flattening of the top part of the nose. ... Decreased growth (hypoplasia) of the nasal bridge may due to infections or genetic diseases. A decrease in the height of the nasal bridge is best seen from a side ...
The Skew of Polar Crown X-ray Arcades
NASA Astrophysics Data System (ADS)
McAllister, A. H.; Mackay, D.; Hundhausen, A. J.; Priest, E.
1997-05-01
A one-to-one relationship between the chirality of filament channels and the skew (relative orientation) of the overlying coronal arcades, as seen with the Yohkoh Soft X-ray Telescope (SXT) was found by Martin and McAllister [1997]. The basis of the relationship is a sample of over 30 mid-and low-latitude filaments during a 6 month period in early 1992. This relationship can be coupled with the predictions for the axial component of polar crown filaments based on the work of Leroy et al. [1983] to predict the skew of polar crown arcades in the recent cycle 22. Thus the axial component of the filament fields along the southern polar crown is predicted to point to the west and a similar component in the corona will lead to right skewed arcades. As has been pointed out in the past, this orientation is inconsistent with the action of photospheric differential rotation on an east-west arcade [Ballegooijen and Martens, 1990]. In this poster we report on the results of a recent survey of the SXT images over the whole declining phase of cycle 22 (Oct. 1991 to June 1995). These results are not in general agreement with those expected based on the past filament observations. They show highly left skewed polar arcades rather than the predicted right skew. The observations are, however, in general agreement with the effects of differential rotation and with recent numerical simulations of polar crown structures, which we will also briefly present. This posses an unexpected and challenging problem and we will discuss some possible ways of reconciling the different observational results. Leroy, Bommier, and Sahal-Brechot, The Magnetic Field in Prominences of the Polar Crown, Solar Physics, 83, 135-142, 1983. Martin and McAllister, The Chirality of X-ray Coronal Arcades Overlying Quiescent Filaments, Astrophys. Journ., submitted, 1997. Ballegooijen and Martens, Magnetic Fields in Quiescent Prominences, ApJ, 361, 283-289, 1990.
Root waving and skewing: unexpectedly in micro-g.
Roux, Stanley J
2012-01-01
Gravity has major effects on both the form and overall length of root growth. Numerous papers have documented these effects (over 300 publications in the last 5 years), the most well-studied being gravitropism, which is a growth re-orientation directed by gravity toward the earth's center. Less studied effects of gravity are undulations due to the regular periodic change in the direction root tips grow, called waving, and the slanted angle of growth roots exhibit when they are growing along a nearly-vertical surface, called skewing. Although diverse studies have led to the conclusion that a gravity stimulus is needed for plant roots to show waving and skewing, the novel results just published by Paul et al. (2012) reveal that this conclusion is not correct. In studies carried out in microgravity on the International Space Station, the authors used a new imaging system to collect digital photographs of plants every six hours during 15 days of spaceflight. The imaging system allowed them to observe how roots grew when their orientation was directed not by gravity but by overhead LED lights, which roots grew away from because they are negatively phototropic. Surprisingly, the authors observed both skewing and waving in spaceflight plants, thus demonstrating that both growth phenomena were gravity independent. Touch responses and differential auxin transport would be common features of root waving and skewing at 1-g and micro-g, and the novel results of Paul et al. will focus the attention of cell and molecular biologists more on these features as they try to decipher the signaling pathways that regulate root skewing and waving. PMID:23217095
UST\\/DME: a clock tree router for general skew constraints
Chung-Wen Albert Tsao; Cheng-Kok Koh
2000-01-01
In this paper, we propose new approaches for solving the useful-skew tree (UST) routing problem [17]: Clock routing subject to general skew constraints. The clock layout synthesis engine of our UST algorithms is based on the deferred-merge embedding (DME) paradigm for zero-skew tree [5; 1] and bounded-skew tree [8; 2] routings; hence, the names UST\\/DME and Greedy-UST\\/DME for our algorithms.
UST\\/DME: a clock tree router for general skew constraints
Chung-wen Albert Tsao; Cheng-kok Koh
2002-01-01
In this article, we propose new approaches for solving the useful-skew tree (UST) routing problem [Xi and Dai 1997]: clock routing subject to general skew constraints. The clock layout synthesis engine of our UST algorithms is based on the deferred-merge embedding (DME) paradigm for the zero-skew tree (ZST) [Edahiro 1992; Chao et al. 1992] and bounded-skew tree (BST) [Cong and
A Request Skew Aware Heterogeneous Distributed Storage System Based on Cassandra
Zhen Ye; Shanping Li
2011-01-01
many distributed storage systems have been proposed to provide high scalability and high availability for modern web applications. However, most of those applications only aware data skew while actually request skew is also widely exist and needed to be considered as well. In this paper, we present a request skew aware heterogeneous distributed storage system based on Cassandra—a famous NoSQL
A Tight Lower Bound for Top-Down Skew Heaps Berry Schoenmakers
Schoenmakers, Berry
A Tight Lower Bound for Top-Down Skew Heaps Berry Schoenmakers January, 1997 Abstract Previously of operations on top-down skew heaps in which each application of meld and delmin requires approximately log n to a sequence known as Hofstadter's G-sequence. 1 Introduction Top-down skew heaps are probably the simplest
Loukas, Marios; Von Kriegenbergh, Katrina; Gilkes, Mathangi; Tubbs, R Shane; Walker, Christi; Malaiyandi, Deepa; Anderson, Robert H
2011-09-01
Much has been written regarding the potential clinical significance of myocardial bridges. As such bridging is often seen in normal individuals, it is clear that not all arteries bridged by myocardial segments produce clinical symptoms thereby suggesting that this feature may simply be an anatomical variant. However, some authors who have considered these bridges as the cause of cardiac ischemia have suggested two potential mechanisms for their pathophysiology. The first is a phasic systolic compression of the bridged segment with persistent mid-to-late diastolic reduction in arterial diameter and the second proposes a reduction in arterial flow. Both mechanisms may contribute to a reduced reserve in coronary blood flow. In this review, we discuss the evidence that exists regarding myocardial bridging and the potential for bridging to cause myocardial ischemia. PMID:21751254
Genomic comparisons between paired bacterial strains with strong and weak GC skews.
Song, Tie-Jun; Wang, Yue; Shen, Jian-Gen; Pan, Jian-Ping; Huang, Jun
2014-02-01
A majority of known eubacterial genomes are characteristic of GC skew, i.e., the leading strand has exceeding number of G over C. The cause of this compositional bias is still not very clear. In this study, we chose five pairs of genomes from distantly related bacterial genera, i.e., Buchnera, Haemophilus, Mycoplasma, Mycobacterium, and Synechococcus, each containing one with strong GC skew and the other with weak GC skew. Through comparison of the orthologous genes in these genera, we found that neither chromosomal rearrangement nor CDS skew has direct relationship with GC skew. PMID:23457112
Skewed X Chromosome Inactivation and Trisomic Spontaneous Abortion: No Association
Warburton, Dorothy; Kline, Jennie; Kinney, Ann; Yu, Chih-yu; Levin, Bruce; Brown, Stephen
2009-01-01
Several studies suggest that highly skewed X chromosome inactivation (HSXI) is associated with recurrent spontaneous abortion. We hypothesized that this association reflects an increased rate of trisomic conceptions due to anomalies on the X chromosome that lead both to HSXI and to a diminished oocyte pool. We compared the distribution of X chromosome inactivation (XCI) skewing percentages (range: 50%–100%) among women with spontaneous abortions in four karyotype groups—trisomy (n = 154), chromosomally normal male (n = 43), chromosomally normal female (n = 38), nontrisomic chromosomally abnormal (n = 61)—to the distribution for age-matched controls with chromosomally normal births (n = 388). In secondary analyses, we subdivided the nontrisomic chromosomally abnormal group, divided trisomies by chromosome, and classified women by reproductive history. Our data support neither an association of HSXI with all trisomies nor an association of HSXI with chromosomally normal male spontaneous abortions. We also find no association between HSXI and recurrent abortion (n = 45). PMID:19646676
Universal relation between skewness and kurtosis in complex dynamics
NASA Astrophysics Data System (ADS)
Cristelli, Matthieu; Zaccaria, Andrea; Pietronero, Luciano
2012-06-01
We identify an important correlation between skewness and kurtosis for a broad class of complex dynamic systems and present a specific analysis of earthquake and financial time series. Two regimes of non-Gaussianity can be identified: a parabolic one, which is common in various fields of physics, and a power law one, with exponent 4/3, which at the moment appears to be specific of earthquakes and financial markets. For this property we propose a model and an interpretation in terms of very rare events dominating the statistics independently on the nature of the events considered. The predicted scaling relation between skewness and kurtosis matches very well the experimental pattern of the second regime. Regarding price fluctuations, this situation characterizes a universal stylized fact.
Identification of spots in rotated and skewed microarray images
NASA Astrophysics Data System (ADS)
Le Brese, Christopher; Zou, Ju Jia
2009-12-01
DNA microarray image processing has vast potential in the measurement of mass gene expression. A common approach to processing microarrays consists of spot identification, spot segmentation, and information extraction. We are concerned with spot identification. We aim to tackle the problem of identifying spots in rotated and skewed arrays via an automated process. The method proposed is composed of three steps, namely, array orientation calculation based on the Hough transform, affine calculation and correction, and gridding. The method is able to correctly identify spots in a microarray that has been rotated or skewed at an angle between 0 and +/-30 deg and corrupted by various types of noise such as high-intensity streaks, Gaussian noise, and salt-and-pepper noise.
Flexible modeling of longitudinal highly-skewed outcomes
Chen, Huichao; Manatunga, Amita K.; Lyles, Robert H.; Peng, Limin; Marcus, Michele
2010-01-01
The analysis of data from epidemiologic and environmental studies present challenges such as skewness of distribution, rounding and multiple measurements over time. To model trends over time based on repeated measurements, we propose a general latent model suitable for highly skewed data. The model assumes that the observed outcome is determined by an unobservable outcome which follows a Weibull distribution. To accommodate correlations among repeated responses over time, we introduce a general random effect from the power variance function (PVF) family of distributions, including the gamma distribution often employed in the literature. The resulting marginal likelihood has a closed form without resorting to numerical or approximation methods. We study estimation and hypothesis testing under these models, with different choices of random effect distributions. Simulation studies are conducted to evaluate their performance. Finally, we apply the proposed method to exposure data collected from the Michigan polybrominated biphenyl (MIPBB) study. PMID:19856304
Skewed Brownian Fluctuations in Single-Molecule Magnetic Tweezers
Burnham, Daniel R.; De Vlaminck, Iwijn; Henighan, Thomas; Dekker, Cees
2014-01-01
Measurements in magnetic tweezers rely upon precise determination of the position of a magnetic microsphere. Fluctuations in the position due to Brownian motion allows calculation of the applied force, enabling deduction of the force-extension response function for a single DNA molecule that is attached to the microsphere. The standard approach relies upon using the mean of position fluctuations, which is valid when the microsphere axial position fluctuations obey a normal distribution. However, here we demonstrate that nearby surfaces and the non-linear elasticity of DNA can skew the distribution. Through experiment and simulations, we show that such a skewing leads to inaccurate position measurements which significantly affect the extracted DNA extension and mechanical properties, leading to up to two-fold errors in measured DNA persistence length. We develop a simple, robust and easily implemented method to correct for such mismeasurements. PMID:25265383
Newspaper Coverage of Intimate Partner Violence: Skewing Representations of Risk
Carlyle, Kellie E.; Slater, Michael D.; Chakroff, Jennifer L.
2011-01-01
How media portray intimate partner violence (IPV) has implications for public perceptions and social policy. Therefore, to better understand these portrayals, this study content analyzes a nationally representative sample of newspaper coverage of IPV over a two-year-period and compares this coverage to epidemiological data in order to examine the implications of the discrepancies between coverage and social reality. Stratified media outlets across the country were used to obtain a representative sample of daily newspapers based on their designated market areas, resulting in 395 IPV-related articles. Results show that newspaper framing of IPV tends to be heavily skewed toward episodic framing. In addition, there are significant differences between our data and epidemiological estimates, particularly in the coverage of homicide and use of alcohol and illegal drugs, which may skew public perceptions of risk. Implications for public perceptions and social policy are discussed. PMID:21297889
Singularity analysis and steering control laws for adaptive-skew pyramid-type control moment gyros
NASA Astrophysics Data System (ADS)
Kojima, Hirohisa
2013-04-01
In contrast to past studies that have treated the skew angle as fixed in pyramid-type control moment gyro (CMG) systems, this paper treats the adaptive-skew pyramid-type CMG (ASCMG) system, in which the skew angle is one of the control variables for generating torques. The singular surfaces of the fixed-skew CMG are analyzed and visualized to illustrate how they depend on the skew angle, and the singular surfaces of the ASCMGs are also analyzed and visualized from a viewpoint of null motion for not only the gimbal angle but also the skew angle. The steering control laws are presented, and we numerically study their effectiveness for the reduction of settling time as compared to the fixed-skew pyramid-type CMGs.
Skewness as a Test of Non-Gaussian Primordial Density Fluctuations
NASA Astrophysics Data System (ADS)
Coles, P.; Moscardini, L.; Lucchin, F.; Matarrese, S.; Messina, A.
1993-10-01
We investigate the evolution of the skewness of the distribution of density fluctuations in CDM models with both Gaussian and non-Gaussian initial fluctuations. We show that the skewness of galaxy counts is a potentially powerful test of the hypothesis of Gaussian primordial density fluctuations. We find, as expected, that the skewness of the mass distribution in models with initially non-Gaussian fluctuations shows systematic departures from the corresponding behaviour for Gaussian fluctuations on intermediate to large scales. We investigate the effect of peculiar velocity distortions and normalization upon the relationship between skewness and variance. These effects are generally small for the models we consider. Comparing our results to the QDOT measurements of the skewness, we find that our initially positive-skew models are clearly excluded by this analysis, but the available data do not rule out the negative-skew models.
The Skew of Polar Crown X-ray Arcades
A. H. McAllister; D. Mackay; A. J. Hundhausen; E. Priest
1997-01-01
A one-to-one relationship between the chirality of filament channels and the skew (relative orientation) of the overlying coronal arcades, as seen with the Yohkoh Soft X-ray Telescope (SXT) was found by Martin and McAllister [1997]. The basis of the relationship is a sample of over 30 mid-and low-latitude filaments during a 6 month period in early 1992. This relationship can
Writer Identification from Non-uniformly Skewed Handwriting Images
H. E. S. Said; G. S. Peake; T. N. Tan; Keith D. Baker
1998-01-01
Many techniques have been reported for handwriting-based writer identification. Most such techniques assume that the written text is fixed (e.g., in signature verification). In this paper we attempt to eliminate this assumption by presenting a novel algorithm for automatic text-independent writer identification from non-uniformly skewed handwriting images. Given that the handwriting of different people is often visually distinctive, we take
Left-App rings of skew generalized power series
Zhao, Renyu
2010-01-01
A ring $R$ is called a left APP-ring if the left annihilator $l_{R}(Ra)$ is right $s$-unital as an ideal of $R$ for any $a\\in R$. Let $R$ be a ring, $(S,\\leq)$ a strictly ordered monoid and $\\omega:S\\longrightarrow {\\rm End}(R)$ a monoid homomorphism. The skew generalized power series ring $[[R^{S,\\leq},\\omega
Head-position-dependent Adaptation of Nonconcomitant Vertical Skew
JAMES S. MAXWELL; CLIFTON M. SCHOR
Vertical phoria can be trained to vary with either head position or orbital eye position. The present experiments show that subjects can simultaneously adapt their eye-position-specific (nonconcomi- tant) vertical phorias in different directions at different head positions. Eye-position-dependent and head-position-dependent adaptive pathways, therefore, are not independent. Rather, the adaptation of vertical skew takes into account both eye and head position.
Head-position-dependent Adaptation of Nonconcomitant Vertical Skew
JAMES S MAXWELL; CLIFTON M SCHOR
1997-01-01
Vertical phoria can be trained to vary with either head position or orbital eye position. The present experiments show that subjects can simultaneously adapt their eye-position-specific (nonconcomitant) vertical phorias in different directions at different head positions. Eye-position-dependent and head-position-dependent adaptive pathways, therefore, are not independent. Rather, the adaptation of vertical skew takes into account both eye and head position. In
Skew and twist resistant hydrodynamic rotary shaft seal
Dietle, L.; Kalsi, M.S.
1999-02-23
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland. 14 figs.
Skew and twist resistant hydrodynamic rotary shaft seal
Dietle, Lannie (Sugar Land, TX); Kalsi, Manmohan Singh (Houston, TX)
1999-01-01
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which and cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland.
MEASURING LOCAL GRADIENT AND SKEW QUADRUPOLE ERRORS IN RHIC IRS.
CARDONA,J.; PEGGS,S.; PILAT,R.; PTITSYN,V.
2004-07-05
The measurement of local linear errors at RHIC interaction regions using an ''action and phase'' analysis of difference orbits has already been presented. This paper evaluates the accuracy of this technique using difference orbits that were taken when known gradient errors and skew quadrupole errors were intentionally introduced. It also presents action and phase analysis of simulated orbits when controlled errors are intentionally placed in a RHIC simulation model.
1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT ...
1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT LEFT AND THE ROCK CREEK AND POTOMAC PARKWAY RAMP AT RIGHT. VIEW TAKEN FROM THE REAR OF THE LINCOLN MEMORIAL. - Arlington Memorial Bridge, Watergate & Bridge Plaza, Adjacent to Arlington Memorial Bridge & Lincoln Memorial, Washington, District of Columbia, DC
LOOKING WNW, CHEVROLET AVENUE BRIDGE CROSSING FLINT RIVER. BRIDGE CONNECTED ...
LOOKING WNW, CHEVROLET AVENUE BRIDGE CROSSING FLINT RIVER. BRIDGE CONNECTED NORTH AND SOUTH PORTIONS OF FACTORY COMPLEX. DANIEL LUTEN DESIGNED THE BRIDGE, AND ILLINOIS BRIDGE COMPANY BUILT IT IN 1918. THE BRIDGE WAS THE SITE OF THE BATTLE OF RUNNING BULLS IN THE 1936-1937 GM SIT DOWN STRIKE. - Delphi Flint West, 300 Chevrolet Avenue, Flint, Genesee County, MI
A longitudinal analysis of reproductive skew in male rhesus macaques.
Widdig, Anja; Bercovitch, Fred B.; Streich, Wolf Jürgen; Sauermann, Ulrike; Nürnberg, Peter; Krawczak, Michael
2004-01-01
One of the basic tenets of sexual selection is that male reproductive success should be large in polygynous species. Here, we analysed 6 years of molecular genetic data from a semi-free-ranging population of rhesus macaques (Macaca mulatta), using Nonac's B index, to assess the level of male reproductive skew in the study troop. On average, the top sire in each year produced 24% of the infants, while 71% of troop males sired no offspring at all. Consequently, 74% of infants had at least one paternal half-sibling in their own birth cohort. Reproductive success was greatest for high-ranking males, males who spent the whole mating season in the troop and males of 9-11 years of age. Heterozygosity for major histocompatibility complex (MHC) class II gene DQB1 was the strongest single predictor of male reproductive success. A negative relationship suggestive of female mate choice was noted between the B index and the proportion of extragroup paternities. Reproductive skew was not associated with relatedness among potential sires or with female cycle synchrony. We conclude that reproductive skew in male rhesus macaques is best accounted for by the 'limited-control' model, with multiple factors interacting to regulate individual reproductive output. PMID:15255100
Validation of an Acoustic Impedance Prediction Model for Skewed Resonators
NASA Technical Reports Server (NTRS)
Howerton, Brian M.; Parrott, Tony L.
2009-01-01
An impedance prediction model was validated experimentally to determine the composite impedance of a series of high-aspect ratio slot resonators incorporating channel skew and sharp bends. Such structures are useful for packaging acoustic liners into constrained spaces for turbofan noise control applications. A formulation of the Zwikker-Kosten Transmission Line (ZKTL) model, incorporating the Richards correction for rectangular channels, is used to calculate the composite normalized impedance of a series of six multi-slot resonator arrays with constant channel length. Experimentally, acoustic data was acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3500 Hz at 120 and 140 dB OASPL. Normalized impedance was reduced using the Two-Microphone Method for the various combinations of channel skew and sharp 90o and 180o bends. Results show that the presence of skew and/or sharp bends does not significantly alter the impedance of a slot resonator as compared to a straight resonator of the same total channel length. ZKTL predicts the impedance of such resonators very well over the frequency range of interest. The model can be used to design arrays of slot resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.
Petersen-Gauthier, Joel
2013-08-09
Engineering Copyright 2013 Joel Petersen-Gauthier ii ABSTRACT Transverse load distribution behavior amongst bridge girders is influenced by many parameters including girder material properties, spacing, skew, deck design, and stiffening element... with his impressive technical knowledge and practical engineering solutions. Both of these professors, on behalf of the Civil Engineering Department, are also responsible for the generous financial support that allowed me to continue my higher education...
Osegueda, Roberto Alejandro
1983-01-01
. Background and Significant Work Purdue University-Indiana State Highway Corrnrission New York State Thruway Authority . . . . . . . . . . . . New York State Department of Transportation . Pennsylvania Turnpike Commission Interstate 80 Overpass, Oakland... York Thruway Authority 7 Roundout Creek Bridge Deck, Kingston, New York. New York State Department of Transportation 8 Delaware River Bridge, New York-Pennsylvania. New York State Department of Transportation 10 9 Erie County Bridge Deck...
Semiconductor bridge (SCB) detonator
Bickes, Jr., Robert W. (Albuquerque, NM); Grubelich, Mark C. (Albuquerque, NM)
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.
Semiconductor bridge (SCB) detonator
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.
Secondary anisotropies in CMB, skew-spectra and Minkowski Functionals
NASA Astrophysics Data System (ADS)
Munshi, Dipak; Coles, Peter; Heavens, Alan
2013-01-01
Secondary contributions to the anisotropy of the cosmic microwave background (CMB), such as the integrated Sachs-Wolfe (ISW) effect, the thermal Sunyaev-Zel'dovich (tSZ) effect, and the effect of gravitational lensing, have distinctive non-Gaussian signatures, and full descriptions therefore require information beyond that contained in their power spectra. The Minkowski Functionals (MF) are well-known as tools for quantifying any departure from Gaussianity and are affected by noise and other sources of confusion in a different way from the usual methods based on higher-order moments or polyspectra, thus providing complementary tools for CMB analysis and cross-validation of results. In this paper we use the recently introduced skew-spectra associated with the MFs to probe the topology of CMB maps to probe the secondary non-Gaussianity as a function of beam smoothing in order to separate various contributions. We devise estimators for these spectra in the presence of realistic observational masks and present expressions for their covariance as a function of instrumental noise. Specific results are derived for the mixed ISW-lensing and tSZ-lensing bispectra as well as contamination due to point sources for noise levels that correspond to the Planck (143 GHz channel) and Experimental Probe of Inflationary Cosmology (EPIC; 150 GHz channel) experiments. The cumulative signal-to-noise ratio (S/N) for one-point generalized skewness parameters can reach an order of O(10) for Planck and two orders of magnitude higher forEPIC, i.e. O(10^3). We also find that these three skew-spectra are correlated, having correlation coefficients r ˜ 0.5-1.0; higher l modes are more strongly correlated. Although the values of S/N increase with decreasing noise, the triplets of skew-spectra that determine the MFs become more correlated; the S/N of lensing-induced skew-spectra are smaller compared to that of a frequency-cleaned tSZ map.
GOETHALS BRIDGE FROM NORTH SIDE OVER ARTHUR KILL. RAILROAD BRIDGE ...
GOETHALS BRIDGE FROM NORTH SIDE OVER ARTHUR KILL. RAILROAD BRIDGE IN FOREGROUND - Goethals Bridge, Spanning Arthur Kill from New Jersey to Staten Island, Staten Island (subdivision), Richmond County, NY
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM ENTRY. VIEW FACING NORTHWEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM BELOW, SHOWING VALVE TOWER TO RIGHT. VIEW FACING NORTH - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI
4. View of bridge deck from northeast approach (bridge deck ...
4. View of bridge deck from northeast approach (bridge deck from southwest approach is virtually identical - Big Cottonwood River Bridge No. 246, Spanning Big Cottonwood River at Cottonwood Street (City Road No. 165), New Ulm, Brown County, MN
Sulphite Railroad Bridge1896, Title Sheet Sulphite Railroad Bridge, Former ...
Sulphite Railroad Bridge-1896, Title Sheet - Sulphite Railroad Bridge, Former Boston & Maine Railroad (originally Tilton & Franklin Railroad) spanning Winnipesautee River, Franklin, Merrimack County, NH
LODGEPOLE BRIDGE, FACING SOUTHEAST Generals Highway, Lodge Pole Bridge, ...
LODGEPOLE BRIDGE, FACING SOUTHEAST - Generals Highway, Lodge Pole Bridge, Spanning Marble Fork of Kaweah River, approximately 21 miles northwest of Ash Mountain Entrance, Three Rivers, Tulare County, CA
LODGEPOLE BRIDGE, FACING NORTHWEST Generals Highway, Lodge Pole Bridge, ...
LODGEPOLE BRIDGE, FACING NORTHWEST - Generals Highway, Lodge Pole Bridge, Spanning Marble Fork of Kaweah River, approximately 21 miles northwest of Ash Mountain Entrance, Three Rivers, Tulare County, CA
Wessendorf, Kurt O. (Albuquerque, NM)
2001-01-01
An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.
The Bryce Canyon Natural Bridge. Technically, this is not a natural bridge, which forms when running water erodes a tunnel into a rock formation. Instead, this is a natural arch, similar to the ones in nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is...
NSDL National Science Digital Library
Jenkins, Davis
This report discusses bridge training programs which are designed to "prepare individuals without the requisite basic skills for postsecondary training leading to career-path employment and further learning in a specific industry or occupational sector." This guide is intended to help those representing community colleges, community organizations, and others plan the development of bridge training programs.
Support column of bridge across Struve Slough, Highway 1. Enlargement of hole where support enters the ground is an effect of lateral shaking, which caused the concrete to break up where the column joined the bridge and was instrumental in the roadbed collapse....
Analysis of land bridge transportation
Yong Qi; Yan Wang
1991-01-01
Land bridge transportation means transportation from one seaport to another by railway across continents instead of by ocean\\u000a ship. At present, there are two common routes for using land bridge transportation in the world. One is Asia—America—Europe\\u000a land bridge, the other is Europe—Asia land bridge.\\u000a \\u000a Eurasia land bridge has obvious advantages over Asia—America—Europe land bridge due to its shorter distance,
Effect of Resonator Axis Skew on Normal Incidence Impedance
NASA Technical Reports Server (NTRS)
Parrott, Tony L.; Jones, Michael G.; Homeijer, Brian
2003-01-01
High by-pass turbofan engines have fewer fan blades and lower rotation speeds than their predecessors. Consequently, the noise suppression at the low frequency end of the noise spectra has become an increasing concern. This has led to a renewed emphasis on improving noise suppression efficiency of passive, duct liner treatments at the lower frequencies. For a variety of reasons, passive liners are comprised of locally-reacting, resonant absorbers. One reason for this design choice is to satisfy operational and economic requirements. The simplest liner design consists of a single layer of honeycomb core sandwiched between a porous facesheet and an impervious backing plate. These resonant absorbing structures are integrated into the nacelle wall and are very ef- ficient over a limited bandwidth centered on their resonance frequency. Increased noise suppression bandwidth and greater suppression at lower frequencies is typically achieved for conventional liners by increasing the liner depth and incorporating thin porous septa into the honeycomb core. However, constraints on liner depth in modern high by-pass engine nacelles severely limit the suppression bandwidth extension to lower frequencies. Also, current honeycomb core liners may not be suitable for irregular geometric volumes heretofore not considered. It is of interest, therefore, to find ways to circumvent liner depth restrictions and resonator cavity shape constraints. One way to increase effective liner depth is to skew the honeycomb core axis relative to the porous facesheet surface. Other possibilities are to alter resonator cavity shape, e.g. high aspect ratio, narrow channels that possibly include right angle bends, 180. channel fold-backs, and splayed channel walls to conform to irregular geometric constraints. These possibilities constitute the practical motivation for expanding impedance modeling capability to include unconventional resonator orientations and shapes. The work reported in this paper is in the nature of a progress report and is limited to examining the implications of resonator axis skew on the composite normal incidence impedance of an array of resonator channels. Specifically, experimental results are compared with a modified impedance prediction model for highaspect- ratio, rectangular, resonator channels with varying amounts of skew relative to the incident particle velocity. It is shown that for resonator channel widths of 1 to 2 mm, aspect ratios of 25 to 50, and skew angles of zero to sixty degrees, the surface impedance of test models can be predicted with good accuracy. Predicted resistances and reactances are particularly well correlated through the first resonance and first anti-resonance for all six test models investigated. Beyond the first anti-resonance, the impedance prediction model loses the ability to predict details of resistance and reactance but still predicts the mean trends very well.
Wigner-Yanase skew information as tests for quantum entanglement
Chen Zeqian [Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, P.O. Box 71010, 30 West District, Xiao-Hong-Shan, Wuhan 430071 (China)
2005-05-15
A Bell-type inequality is proposed in terms of Wigner-Yanase skew information, which is quadratic and involves only one local spin observable at each site. This inequality presents a hierarchic classification of all states of multipartite quantum systems from separable to fully entangled states, which is more powerful than the one presented by quadratic Bell inequalities from two-entangled to fully entangled states. In particular, it is proved that the inequality provides an exact test to distinguish entangled from nonentangled pure states of two qubits. Our inequality sheds considerable light on relationships between quantum entanglement and information theory.
Generally astigmatic Gaussian beam representation and optimization using skew rays
NASA Astrophysics Data System (ADS)
Colbourne, Paul D.
2014-12-01
Methods are presented of using skew rays to optimize a generally astigmatic optical system to obtain the desired Gaussian beam focus and minimize aberrations, and to calculate the propagating generally astigmatic Gaussian beam parameters at any point. The optimization method requires very little computation beyond that of a conventional ray optimization, and requires no explicit calculation of the properties of the propagating Gaussian beam. Unlike previous methods, the calculation of beam parameters does not require matrix calculations or the introduction of non-physical concepts such as imaginary rays.
Skewed parton distributions for B->pi transitions
Th. Feldmann; P. Kroll
1999-05-15
We investigate the b-u skewed parton distributions (SPDs) for B->pi transitions and determine the contributions from several sources (overlaps of soft light-cone wave functions, quark-antiquark annihilations and meson resonances). The B->pi transition form factors, which are relevant in exclusive semi-leptonic and non-leptonic B-decays, are obtained by integrating the b-u SPDs over the momentum fraction x. A phenomenological determination of the relevant parameters allows us to predict the form factors and to obtain the branching ratios for semi-leptonic B->pi decays.
Skewed multivariate models related to hidden truncation and\\/or selective reporting
Barry C. Arnold; Robert J. Beaver; A. Azzalini; N. Balakrishnan; A. Bhaumik; D. K. Dey; C. M. Cuadras; J. M. Sarabia
2002-01-01
The univariate skew-normal distribution was introduced by Azzalini in 1985 as a natural extension of the classical normal\\u000a density to accommodate asymmetry. He extensively studied the properties of this distribution and in conjunction with coauthors,\\u000a extended this class to include the multivariate analog of the skew-normal. Arnold et al. (1993) introduced a more general\\u000a skew-normal distribution as the marginal distribution
Base Composition Skews, Replication Orientation, and Gene Orientation in 12 Prokaryote Genomes
Michael J. McLean; Kenneth H. Wolfe; Kevin M. Devine
1998-01-01
. Variation in GC content, GC skew and AT skew along genomic regions was examined at third codon positions in completely sequenced\\u000a prokaryotes. Eight out of nine eubacteria studied show GC and AT skews that change sign at the origin of replication. The\\u000a leading strand in DNA replication is G-T rich at codon position 3 in six eubacteria, but C-T
Skewness and shock formation in laboratory-scale supersonic jet data.
Gee, Kent L; Neilsen, Tracianne B; Atchley, Anthony A
2013-06-01
Spatial properties of noise statistics near unheated, laboratory-scale supersonic jets yield insights into source characteristics and near-field shock formation. Primary findings are (1) waveforms with positive pressure skewness radiate from the source with a directivity upstream of maximum overall level and (2) skewness of the time derivative of the pressure waveforms increases significantly with range, indicating formation of shocks during propagation. These results corroborate findings of a previous study involving full-scale engine data. Further, a comparison of ideally and over-expanded laboratory data show that while derivative skewness maps are similar, waveform skewness maps are substantially different for the two cases. PMID:23742445
Bandyopadhyay, Dipankar; Lachos, Victor H.; Castro, Luis M.; Dey, Dipak K.
2012-01-01
Often in biomedical studies, the routine use of linear mixed-effects models (based on Gaussian assumptions) can be questionable when the longitudinal responses are skewed in nature. Skew-normal/elliptical models are widely used in those situations. Often, those skewed responses might also be subjected to some upper and lower quantification limits (viz. longitudinal viral load measures in HIV studies), beyond which they are not measurable. In this paper, we develop a Bayesian analysis of censored linear mixed models replacing the Gaussian assumptions with skew-normal/independent (SNI) distributions. The SNI is an attractive class of asymmetric heavy-tailed distributions that includes the skew-normal, the skew-t, skew-slash and the skew-contaminated normal distributions as special cases. The proposed model provides flexibility in capturing the effects of skewness and heavy tail for responses which are either left- or right-censored. For our analysis, we adopt a Bayesian framework and develop a MCMC algorithm to carry out the posterior analyses. The marginal likelihood is tractable, and utilized to compute not only some Bayesian model selection measures but also case-deletion influence diagnostics based on the Kullback-Leibler divergence. The newly developed procedures are illustrated with a simulation study as well as a HIV case study involving analysis of longitudinal viral loads. PMID:22685005
Crossover ensembles of random matrices and skew-orthogonal polynomials
Kumar, Santosh, E-mail: skumar.physics@gmail.com [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067 (India); Pandey, Akhilesh, E-mail: ap0700@mail.jnu.ac.in [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067 (India)
2011-08-15
Highlights: > We study crossover ensembles of Jacobi family of random matrices. > We consider correlations for orthogonal-unitary and symplectic-unitary crossovers. > We use the method of skew-orthogonal polynomials and quaternion determinants. > We prove universality of spectral correlations in crossover ensembles. > We discuss applications to quantum conductance and communication theory problems. - Abstract: In a recent paper (S. Kumar, A. Pandey, Phys. Rev. E, 79, 2009, p. 026211) we considered Jacobi family (including Laguerre and Gaussian cases) of random matrix ensembles and reported exact solutions of crossover problems involving time-reversal symmetry breaking. In the present paper we give details of the work. We start with Dyson's Brownian motion description of random matrix ensembles and obtain universal hierarchic relations among the unfolded correlation functions. For arbitrary dimensions we derive the joint probability density (jpd) of eigenvalues for all transitions leading to unitary ensembles as equilibrium ensembles. We focus on the orthogonal-unitary and symplectic-unitary crossovers and give generic expressions for jpd of eigenvalues, two-point kernels and n-level correlation functions. This involves generalization of the theory of skew-orthogonal polynomials to crossover ensembles. We also consider crossovers in the circular ensembles to show the generality of our method. In the large dimensionality limit, correlations in spectra with arbitrary initial density are shown to be universal when expressed in terms of a rescaled symmetry breaking parameter. Applications of our crossover results to communication theory and quantum conductance problems are also briefly discussed.
Checa, Antonio G; Cartwright, Julyan H E; Willinger, Marc-Georg
2011-12-01
We confirm with high-resolution techniques the existence of mineral bridges between superposed nacre tablets. In the towered nacre of both gastropods and the cephalopod Nautilus there are large bridges aligned along the tower axes, corresponding to gaps (150-200nm) in the interlamellar membranes. Gaps are produced by the interaction of the nascent tablets with a surface membrane that covers the nacre compartment. In the terraced nacre of bivalves bridges associated with elongated gaps in the interlamellar membrane (>100nm) have mainly been found at or close to the edges of superposed parental tablets. To explain this placement, we hypothesize that the interlamellar membrane breaks due to differences in osmotic pressure across it when the interlamellar space below becomes reduced at an advanced stage of calcification. In no cases are the minor connections between superimposed tablets (<60nm), earlier reported to be mineral bridges, found to be such. PMID:21982842
NSDL National Science Digital Library
2011-01-01
This article, written for middle grades students, relates the history of the famous Konigsberg Bridge problem and introduces the idea of networks and paths that do not retrace themselves. The article concludes with a path the student must work out.
... made by the dental lab. Porcelain-fused-to-metal bridge The restoration (the part that looks like ... porcelain attached and fused to a framework of metal. The Implant Process The time it takes to ...
NSDL National Science Digital Library
These interactive learning modules and simulations allow students to explore the science, technology and people involved in building the New Bay Bridge, which is intended as a replacement for the historic San Francisco-Oakland Bay Bridge that was damaged in the 1989 Loma Prieta Earthquake. In the interactive module "Quake Country," students investigate plate tectonics as the driving force behind the faulting and resulting earthquakes in the Bay area. In the "Engineering for Earthquakes" simulation, students act as engineers, design their own bridges, and test them against the Maximum Credible Earthquake (MCE), the worst earthquake that might hit the Bay area every 1500 years. In the module "Two Miles and 2,000 Hands," students learn about the people who perform a large variety of jobs in building the new bridge.
Design Squad: Suspension Bridge
NSDL National Science Digital Library
WGBH Educational Foundation
2007-08-09
In this video segment adapted from Design Squad—a PBS TV series featuring high school contestants tackling engineering challenges—students employ the concepts of tension and compression to build a suspension bridge without the aid of power tools.
2001-01-01
A detailed 3D model was created to show the 500-million dollar construction project of a 10-mile section of I-95 at the Virginia \\/ Maryland Border, it includes four multi-level interchanges and a major bridge (Woodrow Wilson Bridge) across the Potomac River. Using AutoCAD Land evelopment and 3D Studio Max 3.1, a multi gigabyte 3D database was created to engineering accuracy.
NSDL National Science Digital Library
This is an animation of a bridge rectifier circuit or diode bridge. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations. A link provides an optional Quicktime version of this same animation.Other 3-D Circuit Animations can be seen here.
2008-10-15
] describe a particular type of immature astrocyte that seems to provide a very successful bridging material. The idea of using embryonic CNS tissue and embryonic astrocytes for repairing the spinal cord has a long history. Axons grow in the embryonic CNS, so... at various mechanisms, including neutrali- zation of inhibitory molecules, promotion of plasticity, direct stimulation of axon regeneration, bridging and control of inflammation. A combination of two or more of these approaches will be needed to achieve...
COMPENSATION OF FAST KICKER ROLLS WITH SKEW QUADRUPOLES
Pinayev, I.
2011-03-28
The development of the third generation light sources lead to the implementation of the top-up operation, when injection occurs while users collect data. The beam excursions due to the non-closure of the injection bump can spoil the data and need to be suppressed. In the horizontal plane compensation can be achieved by adjusting timing and kick amplitudes. The rolls of the kicker magnets create non-closure in the vertical plane and usually there is no means for correction. In the paper we describe proposed compensation scheme utilizing two skew quadrupoles placed inside the injection bump. The third generation light sources implement top-up operation firstly introduced at Advanced Photon Source. In this mode the circulating beam current is supported near constant by frequent injection of small charge, while photon beam is delivered for users. The beam perturbations caused by the mismatched injection bump can provide undesired noise in the user data. Usually the injection trigger is distributed to the users end stations so that those affected would be able to blank data acquisition. Nevertheless, as good operational practice such transients should be suppressed as much as possible. In the horizontal plane (which is commonly used for injection) one can adjust individual kicker strength as well as trigger delay while observing motion of the stored beam centroid. In the vertical plane such means are unavailable in the most cases. The possible solutions include dedicated weak vertical kickers and motorized adjustment of the roll angle of the injection kickers. Both abovementioned approaches are expensive and can significantly deteriorate reliability. We suggest two employ two skew quadrupoles (to correct both angle and position) placed inside the injection bump. In this case the beam position itself serves as measure of the kicker strength (assuming that kickers are well matched) and vertical kicks from the skew quadrupoles will be self synchronized with injection bump. In this paper we will consider the case when injection hardware (kickers and septa) are located in the same straight. Such an approach simplifies consideration but it can be generalized.
Testing reproductive skew models in a communally breeding bird, the pukeko, Porphyrio porphyrio
Jamieson, I. G.
1997-01-01
Recent attempts to explain variation among social species in the degree to which reproduction is shared among group members are focused on what are known as reproductive skew models. Reproduction within social groups can vary from an even distribution among all adults (i.e. low skew) to complete monopolization by a dominant individual (high skew). Three critical predictions derived from these models have remained largely untested: (1) reduced chances of independent breeding due to strong ecological constraints results in high reproductive skew; (2) the lower the genetic relatedness within social groups the lower the skew; and, counter-intuitively, (3) dominance-related aggression will be more prevalent in social groups composed of close kin where reproductive skew is predicted to be high. Here I test these predictions by comparing two populations of the communally breeding pukeko (Porphyrio porphyrio), which show extremes in social organization, namely social groups consisting of close kin versus groups made up of unrelated breeders. I report evidence from both cobreeding males and females in support of the above predictions. The results also indicate that low reproductive skew among unrelated group members may be prevalent in social species that possess weapons that can inflict serious injury in situations where reproductive competition may escalate to fighting. The consistency between these results and those from studies of social insects suggests that reproductive skew models may represent a unifying framework for understanding the factors shaping complex animal societies.
POPULATION GENETICS MODELS WITH SKEWED FERTILITIES: A FORWARD AND BACKWARD ANALYSIS
Paris-Sud XI, UniversitÃ© de
POPULATION GENETICS MODELS WITH SKEWED FERTILITIES: A FORWARD AND BACKWARD ANALYSIS THIERRY HUILLET, MARTIN MÂ¨OHLE Abstract. Discrete population genetics models with unequal (skewed) fertil- ities. For each class the asymptotic behavior as the total population size N tends to infinity is investigated
On fast and accurate detection of unauthorized wireless access points using clock skews
Suman Jana; Sneha Kumar Kasera
2008-01-01
We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unau- thorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limita- tions of existing solutions - the inability to effectively de- tect Medium Access Control (MAC) address spoofing. We
On Fast and Accurate Detection of Unauthorized Wireless Access Points Using Clock Skews
Suman Jana; Sneha K. Kasera
2010-01-01
We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions - the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock
NPIP: A skew line needle configuration optimization system for HDR brachytherapy
Goldberg, Ken
NPIP: A skew line needle configuration optimization system for HDR brachytherapy Timmy Siauwa) Purpose: In this study, the authors introduce skew line needle configurations for high dose rate (HDR needles than the current HDR brachytherapy workflow. Combined with robot assisted brachytherapy
J. Symbolic Computation (1997) 0, 1000. To appear. Factoring in Skew-Polynomial Rings
Giesbrecht, Mark
J. Symbolic Computation (1997) 0, 1Â000. To appear. Factoring in Skew-Polynomial Rings over Finite, R3T 2N2 mwg@cs.umanitoba.ca (Received April 10, 1994) Efficient algorithms are presented for factoring polynomials in the skew-polynomial ring F[x; ], a non-commutative generalization of the usual ring
J. Symbolic Computation (1997) 0, 1--000. To appear. Factoring in SkewPolynomial Rings
Giesbrecht, Mark
J. Symbolic Computation (1997) 0, 1--000. To appear. Factoring in SkewÂPolynomial Rings over Finite, Canada, R3T 2N2 mwg@cs.umanitoba.ca (Received April 10, 1994) E#cient algorithms are presented for factoring polynomials in the skewÂpolynomial ring F[x; #], a nonÂcommutative generalization of the usual
Pamela L. Reynolds; John F. Bruno
2012-01-01
Widespread overharvesting of top consumers of the world’s ecosystems has “skewed” food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have
Chi Chen; Carton W Chen
2007-01-01
BACKGROUND: Most bacterial chromosomes exhibit asymmetry of base composition with respect to leading vs. lagging strands (GC and AT skews). These skews reflect mainly those in protein coding sequences, which are driven by asymmetric mutation pressures during replication and transcription (notably asymmetric cytosine deamination) plus subsequent selection for preferred structures, signals, amino acid or codons. The transcription-associated effects but not
Low dimensional chaos in the AT and GC skew profiles of DNA sequences
Qian Zhou; Zeng-Qiang Chen
2010-01-01
This paper investigates the existence of low-dimensional deterministic chaos in the AT and GC skew profiles of DNA sequences. It has taken DNA sequences from eight organisms as samples. The skew profiles are analysed using continuous wavelet transform and then nonlinear time series methods. The invariant measures of correlation dimension and the largest Lyapunov exponent are calculated. It is demonstrated
STATISTICAL GENERIC AND CHIP-SPECIFIC SKEW ASSIGNMENT FOR IMPROVING TIMING YIELD OF FPGAS
Bazargan, Kiarash "Kia"
be adjusted either pre-silicon(based on timing slack dis- tribution) or post-silicon to fix paths that violate by adjusting the clock skews of flip-flops. This involves making the clock distribution network tunable to adjust the phase of clocks but they are limited in number and do not provide fine control of skews
Soft bounds on diffusion produce skewed distributions and Gompertz growth
NASA Astrophysics Data System (ADS)
Mandrà, Salvatore; Lagomarsino, Marco Cosentino; Gherardi, Marco
2014-09-01
Constraints can affect dramatically the behavior of diffusion processes. Recently, we analyzed a natural and a technological system and reported that they perform diffusion-like discrete steps displaying a peculiar constraint, whereby the increments of the diffusing variable are subject to configuration-dependent bounds. This work explores theoretically some of the revealing landmarks of such phenomenology, termed "soft bound." At long times, the system reaches a steady state irreversibly (i.e., violating detailed balance), characterized by a skewed "shoulder" in the density distribution, and by a net local probability flux, which has entropic origin. The largest point in the support of the distribution follows a saturating dynamics, expressed by the Gompertz law, in line with empirical observations. Finally, we propose a generic allometric scaling for the origin of soft bounds. These findings shed light on the impact on a system of such "scaling" constraint and on its possible generating mechanisms.
Skew detection and correction of ancient Tamil documents using particle swarm optimization
NASA Astrophysics Data System (ADS)
Sridevi, N.; Subashini, P.
2012-04-01
When a document is fed to a scanner either mechanically or by a human operator for digitization, it suffers from some degrees of skew or tilt. Skew detection is one of the first operations to be applied to scanned documents when converting data to a digital format. Its aim is to align an image before processing because text segmentation and recognition methods require properly aligned lines. This paper presents a new approach for skew detection and correction of documents. Particle Swarm Optimization (PSO) is used for solving skew optimization. A new objective function based on local maxima and minima of projection profile is formulated and PSO is used to find the best angle that maximizes the objective function. The proposed method is compared with existing methods like Hough transform, Fourier transform. Experimental results show that the proposed method corrects the skew with the maximum error rate of +/- 1° .
A proof for Rhiel's range estimator of the coefficient of variation for skewed distributions.
Rhiel, G Steven
2007-02-01
In this research study is proof that the coefficient of variation (CV(high-low)) calculated from the highest and lowest values in a set of data is applicable to specific skewed distributions with varying means and standard deviations. Earlier Rhiel provided values for d(n), the standardized mean range, and a(n), an adjustment for bias in the range estimator of micro. These values are used in estimating the coefficient of variation from the range for skewed distributions. The d(n) and an values were specified for specific skewed distributions with a fixed mean and standard deviation. In this proof it is shown that the d(n) and an values are applicable for the specific skewed distributions when the mean and standard deviation can take on differing values. This will give the researcher confidence in using this statistic for skewed distributions regardless of the mean and standard deviation. PMID:17451028
Large replication skew domains delimit GC-poor gene deserts in human.
Zaghloul, Lamia; Drillon, Guénola; Boulos, Rasha E; Argoul, Françoise; Thermes, Claude; Arneodo, Alain; Audit, Benjamin
2014-12-01
Besides their large-scale organization in isochores, mammalian genomes display megabase-sized regions, spanning both genes and intergenes, where the strand nucleotide composition asymmetry decreases linearly, possibly due to replication activity. These so-called skew-N domains cover about a third of the human genome and are bordered by two skew upward jumps that were hypothesized to compose a subset of "master" replication origins active in the germline. Skew-N domains were shown to exhibit a particular gene organization. Genes with CpG-rich promoters likely expressed in the germline are over represented near the master replication origins, with large genes being co-oriented with replication fork progression, which suggests some coordination of replication and transcription. In this study, we describe another skew structure that covers ?13% of the human genome and that is bordered by putative master replication origins similar to the ones flanking skew-N domains. These skew-split-N domains have a shape reminiscent of a N, but split in half, leaving in the center a region of null skew whose length increases with domain size. These central regions (median size ?860 kb) have a homogeneous composition, i.e. both a null and constant skew and a constant and low GC content. They correspond to heterochromatin gene deserts found in low-GC isochores with an average gene density of 0.81 promoters/Mb as compared to 7.73 promoters/Mb genome wide. The analysis of epigenetic marks and replication timing data confirms that, in these late replicating heterochomatic regions, the initiation of replication is likely to be random. This contrasts with the transcriptionally active euchromatin state found around the bordering well positioned master replication origins. Altogether skew-N domains and skew-split-N domains cover about 50% of the human genome. PMID:25224847
NASA Technical Reports Server (NTRS)
Nypan, L. J.
1980-01-01
Measurements of roller skewing in a 118 mm bore roller bearing operating at shaft speeds to 12000 rpm are reported. High speed motion pictures of a modified roller were taken through a derotation prism to record skewing as the roller moved through loaded and unloaded regions of the bearing. Subsequent frame by frame measurement of the photographic film provided information on roller skewing. Radial and tangential skew amplitudes of .4 to .5 degrees were observed with .5 degree misalignment.
NSDL National Science Digital Library
Covered bridges cause moments of delight for historic preservationists, and they entered a new place in American popular culture when they figured prominently in a certain Clint Eastwood film in the early 1990s. Recently, staff members and student assistants at Bucknell University spent a significant amount of time creating this digital collection of covered bridge photographs. Interestingly enough, the original photographs were taken by a long-time member of the biology faculty at Bucknell, one Professor Nelson F. Davis. The photos date from 1898 to 1939, and all told, there are over 300 images in this collection. Visitors will enjoy looking over this collection, and these documents will be of great interest to anyone fascinated by these types of bridges, engineering, or the history of rural Pennsylvania.
Axionometric Cutaway of Bridge Structure Shoreham Railroad Bridge, Former ...
Axionometric Cutaway of Bridge Structure - Shoreham Railroad Bridge, Former Addison County Railroad (later, Rutland Railroad, Addison Branch), spanning Lemon Fair River above Richville Pond, west of East Shoreham Road, Shoreham, Addison County, VT
Shoreham Railroad Bridge, Title Sheet Shoreham Railroad Bridge, Former ...
Shoreham Railroad Bridge, Title Sheet - Shoreham Railroad Bridge, Former Addison County Railroad (later, Rutland Railroad, Addison Branch), spanning Lemon Fair River above Richville Pond, west of East Shoreham Road, Shoreham, Addison County, VT
`Smart bridge' technology helps monitor I-35W bridge behavior
Minnesota, University of
the bridge's structural behavior in a project funded by the Minnesota Department of Transportation (MnDOT). During its construction, the bridge was instrumented with more than 500 sensors that monitor strain, load
4. VIEW OF SILVER BRIDGE (ST. MARY'S BRIDGE), CARRYING COUNTY ...
4. VIEW OF SILVER BRIDGE (ST. MARY'S BRIDGE), CARRYING COUNTY ROAD OVER SOURIS RIVER NEAR SOUTH END OF REFUGE, LOOKING NORTHEAST - Upper Souris National Wildlife Refuge Dams, Souris River Basin, Foxholm, Ward County, ND
Dog Bridge, view of the deck of the bridge and ...
Dog Bridge, view of the deck of the bridge and rails looking from Linden Lane - National Park Seminary, Bounded by Capitol Beltway (I-495), Linden Lane, Woodstove Avenue, & Smith Drive, Silver Spring, Montgomery County, MD
22. BRIDGE CREEK BRIDGE, AVENUE OF THE GIANTS, OLD HIGHWAY ...
22. BRIDGE CREEK BRIDGE, AVENUE OF THE GIANTS, OLD HIGHWAY 101. HUMBOLDT COUNTY, CALIFORNIA. LOOKING E. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA
Large-scale genomic 2D visualization reveals extensive CG-AT skew correlation in bird genomes
Xuegong Deng; Ilkka Havukkala; Xuemei Deng
2007-01-01
BACKGROUND: Bird genomes have very different compositional structure compared with other warm-blooded animals. The variation in the base skew rules in the vertebrate genomes remains puzzling, but it must relate somehow to large-scale genome evolution. Current research is inclined to relate base skew with mutations and their fixation. Here we wish to explore base skew correlations in bird genomes, to
R. Chitroju; C. Sadarangani
2009-01-01
Skewing which is commonly used in smaller sized induction motors for the reduction of magnetic noise causes higher cross currents in the rotor bars. This leads to a substantial increase of stray losses in the skewed rotor. Reduction of these losses can be achieved by eliminating skew, but at the cost of increased noise level and torque ripple in the
1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT ...
1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT LEFT AND THE ROCK CREEK AND POTOMAC PARKWAY RAMP AT RIGHT. VIEW TAKEN FROM THE REAR OF THE LINCOLN MEMORIAL. - Arlington Memorial Bridge, Boundary Channel Extension, Spanning Mount Vernon Memorial Highway & Boundary Channel, Washington, District of Columbia, DC
18. GRAYS RIVER BRIDGE PLAN, DATED 1905 (Original bridge plan ...
18. GRAYS RIVER BRIDGE PLAN, DATED 1905 (Original bridge plan was lost after the plan was photographed.) this photograph is an 8x10-inch enlargement from a 4x5-inch negative) - Grays River Covered Bridge, Worrel Road spanning Grays River, Grays River, Wahkiakum County, WA
Bridging Brown County Case Study Bridging Brown County Case Study
Minnesota, University of
Bridging Brown County Case Study Bridging Brown County Case Study Connecting Communities Capacity 4 Collaboration 4 Networking 4 Community Vitality 4 Social Capital #12;Bridging Brown County Case, in 1998 a tornado caused severe damage in parts of the county. As Katie assisted groups and coordinated
Log Pearson type 3 quantile estimators with regional skew information and low outlier adjustments
Griffis, V.W.; Stedinger, J.R.; Cohn, T.A.
2004-01-01
[1] The recently developed expected moments algorithm (EMA) [Cohn et al., 1997] does as well as maximum likelihood estimations at estimating log-Pearson type 3 (LP3) flood quantiles using systematic and historical flood information. Needed extensions include use of a regional skewness estimator and its precision to be consistent with Bulletin 17B. Another issue addressed by Bulletin 17B is the treatment of low outliers. A Monte Carlo study compares the performance of Bulletin 17B using the entire sample with and without regional skew with estimators that use regional skew and censor low outliers, including an extended EMA estimator, the conditional probability adjustment (CPA) from Bulletin 17B, and an estimator that uses probability plot regression (PPR) to compute substitute values for low outliers. Estimators that neglect regional skew information do much worse than estimators that use an informative regional skewness estimator. For LP3 data the low outlier rejection procedure generally results in no loss of overall accuracy, and the differences between the MSEs of the estimators that used an informative regional skew are generally modest in the skewness range of real interest. Samples contaminated to model actual flood data demonstrate that estimators which give special treatment to low outliers significantly outperform estimators that make no such adjustment.
National Cancer Institute Bridging the Funding Gap for Promising Cancer Therapeutics, Imaging Technologies, Interventional Devices, Diagnostics, and Prognostics SBIR Phase II Bridge Award The National Cancer Institute (NCI) Small Business Innovation
Bridge Types: Tensile & Compressive Forces
NSDL National Science Digital Library
Integrated Teaching and Learning Program,
Students explore how tension and compression forces act on three different bridge types. Using sponges, cardboard and string, they create models of beam, arch and suspension bridges and apply forces to understand how they disperse or transfer these loads.
77 FR 16784 - General Bridge Regulation; Amendment
Federal Register 2010, 2011, 2012, 2013, 2014
2012-03-22
...USCG-2008-1188] RIN 1625-AB36 General Bridge Regulation; Amendment AGENCY: Coast...rulemaking concerning amendments to the general bridge regulations. The rulemaking was initiated...clarify the statutory responsibilities of bridge owners to remove their bridges from...
NSDL National Science Digital Library
A Guide to Covered Bridges, offered by Drexel University, Philadelphia, Pennsylvania, transforms the Web into a time machine. Find the answer to the question, why are there so many covered bridges, and why in Pennsylvania and the Northeast? The Drexel University Honors Program sponsors this guide to dozens of covered bridges of the Philadelphia region. Driving tours are suggested, and bridge images are indexed by season (fall color, winter, snow and ice, spring/summer) and structure as well as county.
ERIC Educational Resources Information Center
Johnson, Susan Moore; Kardos, Susan M.
2005-01-01
The lack of instructional continuity in schools negates every effort of principals to provide an environment where all students would be successful. One solution could be to bridge the gap between the professional knowledge and skills of experienced teachers and the energy and fresh ideas of new recruits so that the latter are provided support…
NASA Astrophysics Data System (ADS)
Muhammad, Sadiq; Tavakoli, Armin; Kurant, Maciej; Paw?owski, Marcin; ?ukowski, Marek; Bourennane, Mohamed
2014-04-01
Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain an advantage in a famous, immensely popular, card game—bridge. The essence of a winning strategy in bridge is efficient communication between the partners. The rules of the game allow only a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits). Surprisingly, our quantum technique does not violate the existing rules of the game (as there is no increase in information flow). We show that our quantum bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt game, which is equivalent to a 2?1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.
Bryce Canyon's Natural Bridge is technically a natural arch, similar to those in the nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates...
ERIC Educational Resources Information Center
Salter, Colin
2009-01-01
The political context of the conversion of the Historic Tramway Bridge, adjacent to Sandon Point in Bulli (NSW, Australia), and how this was exploited to serve predetermined ends, illustrates that technologies can be designed to have particular social (and political) effects. Through reflection on this relatively small engineering project, this…
Thomas M. Storey; Wojciech Maly
1990-01-01
The authors compare the performance of two test generation techniques, stuck fault testing and current testing, when applied to CMOS bridging faults. Accurate simulation of such faults mandated the development of several new design automation tools, including an analog-digital fault simulator. The results of this simulation are analyzed. It is shown that stuck fault test generation, while inherently incapable of
Jean Carracilli
2001-01-01
This study is based on the development and implementation of the REVE system, an acquisition system of traffic load effects over long periods, from one to several years. The objective is to measure, globally and experimentally, the dynamic effects of real road traffic by measuring strain extrema on a certain number of bridge construction details, using smart sensors networks. It
Nicole Aragi
2008-01-01
The project that came to be known as URI Student Bridge began with my amazing college experience and my desire to share that experience with others who were making the decision of whether to begin a college experience of their own. I have been very fortunate to have the funding and motivation to attend college, and have had many opportunities
ERIC Educational Resources Information Center
Roy, Michael; Doss, Laurie K.
2007-01-01
The Building Migratory Bridges (BOMB) program--a collaboration between the Marvel wood School and Audubon Sharon in Connecticut and Conservation Research Education Action (CR EA), a U.S. not-for-profit in Panama--uses nontropical migratory bird research in the United States and Panama to demonstrate how negative environmental impacts in one…
NSDL National Science Digital Library
WGBH Educational Foundation
2007-08-09
In this video segment adapted from Design Squad—a PBS TV series featuring high school contestants tackling engineering challenges—students employ the concepts of tension and compression as they build a truss bridge without the aid of power tools.
ERIC Educational Resources Information Center
Bohnen, Elizabeth; Klie, Judy
This report describes BRIDGES, an employment equity special measures training program developed by the City of Toronto (Ontario, Canada). It was designed to help women employees move from their traditional jobs into trades, technical or operation (TTO) jobs within their own organization. The program is a combination of classroom sessions, shop…
Low dimensional chaos in the AT and GC skew profiles of DNA sequences
NASA Astrophysics Data System (ADS)
Zhou, Qian; Chen, Zeng-Qiang
2010-09-01
This paper investigates the existence of low-dimensional deterministic chaos in the AT and GC skew profiles of DNA sequences. It has taken DNA sequences from eight organisms as samples. The skew profiles are analysed using continuous wavelet transform and then nonlinear time series methods. The invariant measures of correlation dimension and the largest Lyapunov exponent are calculated. It is demonstrated that the AT and GC skew profiles of these DNA sequences all exhibit low dimensional chaotic behaviour. It suggests that chaotic properties may be ubiquitous in the DNA sequences of all organisms.
This photograph shows Lowe's Bridge off ME-15 in Guilford, Maine, spanning the Piscataquis River. USGS gaging station 01031500 is located on the downstream side of the bridge. The original bridge, built in 1857, washed away in the flood of 1987, and was rebuilt on the original abutments in 1990....
Schrodinger Bridges classical and quantum
system to a final probability distribution Yongxin Chen, Tryphon T. Georgiou, Michele Pavon #12;Â· History://arxiv.org/abs/1405.6650 Positive contraction mappings for classical and quantum Schrodinger systems Tryphon T of Schrodinger bridges Â· Bridges for Markov chains Â· The Hilbert metric Â· Bridges for quantum (TPTP) evolutions
Crossover ensembles of random matrices and skew-orthogonal polynomials
NASA Astrophysics Data System (ADS)
Kumar, Santosh; Pandey, Akhilesh
2011-08-01
In a recent paper (S. Kumar, A. Pandey, Phys. Rev. E, 79, 2009, p. 026211) we considered Jacobi family (including Laguerre and Gaussian cases) of random matrix ensembles and reported exact solutions of crossover problems involving time-reversal symmetry breaking. In the present paper we give details of the work. We start with Dyson's Brownian motion description of random matrix ensembles and obtain universal hierarchic relations among the unfolded correlation functions. For arbitrary dimensions we derive the joint probability density (jpd) of eigenvalues for all transitions leading to unitary ensembles as equilibrium ensembles. We focus on the orthogonal-unitary and symplectic-unitary crossovers and give generic expressions for jpd of eigenvalues, two-point kernels and n-level correlation functions. This involves generalization of the theory of skew-orthogonal polynomials to crossover ensembles. We also consider crossovers in the circular ensembles to show the generality of our method. In the large dimensionality limit, correlations in spectra with arbitrary initial density are shown to be universal when expressed in terms of a rescaled symmetry breaking parameter. Applications of our crossover results to communication theory and quantum conductance problems are also briefly discussed.
Regression for Skewed Biomarker Outcomes Subject to Pooling
Mitchell, Emily M.; Lyles, Robert H.; Manatunga, Amita K.; Danaher, Michelle; Perkins, Neil J.; Schisterman, Enrique F.
2014-01-01
Summary Epidemiological studies involving biomarkers are often hindered by prohibitively expensive laboratory tests. Strategically pooling specimens prior to performing these lab assays has been shown to effectively reduce cost with minimal information loss in a logistic regression setting. When the goal is to perform regression with a continuous biomarker as the outcome, regression analysis of pooled specimens may not be straightforward, particularly if the outcome is right-skewed. In such cases, we demonstrate that a slight modification of a standard multiple linear regression model for poolwise data can provide valid and precise coefficient estimates when pools are formed by combining biospecimens from subjects with identical covariate values. When these x-homogeneous pools cannot be formed, we propose a Monte Carlo Expectation Maximization (MCEM) algorithm to compute maximum likelihood estimates (MLEs). Simulation studies demonstrate that these analytical methods provide essentially unbiased estimates of coefficient parameters as well as their standard errors when appropriate assumptions are met. Furthermore, we show how one can utilize the fully observed covariate data to inform the pooling strategy, yielding a high level of statistical efficiency at a fraction of the total lab cost. PMID:24521420
Statistics on Cannabis Users Skew Perceptions of Cannabis Use
Burns, Rachel M.; Caulkins, Jonathan P.; Everingham, Susan S.; Kilmer, Beau
2013-01-01
Collecting information about the prevalence of cannabis use is necessary but not sufficient for understanding the size, dynamics, and outcomes associated with cannabis markets. This paper uses two data sets describing cannabis consumption in the United States and Europe to highlight (1) differences in inferences about sub-populations based on the measure used to quantify cannabis-related activity; (2) how different measures of cannabis-related activity can be used to more accurately describe trends in cannabis usage over time; and (3) the correlation between frequency of use in the past-month and average grams consumed per use-day. Key findings: focusing on days of use instead of prevalence shows substantially greater increases in U.S. cannabis use in recent years; however, the recent increase is mostly among adults, not youth. Relatively more rapid growth in use days also occurred among the college-educated and Hispanics. Further, data from a survey conducted in seven European countries show a strong positive correlation between frequency of use and quantity consumed per day of use, suggesting consumption is even more skewed toward the minority of heavy users than is suggested by days-of-use calculations. PMID:24223560
Oberg, Kevin A.; Mades, Dean M.
1987-01-01
Four techniques for estimating generalized skew in Illinois were evaluated: (1) a generalized skew map of the US; (2) an isoline map; (3) a prediction equation; and (4) a regional-mean skew. Peak-flow records at 730 gaging stations having 10 or more annual peaks were selected for computing station skews. Station skew values ranged from -3.55 to 2.95, with a mean of -0.11. Frequency curves computed for 30 gaging stations in Illinois using the variations of the regional-mean skew technique are similar to frequency curves computed using a skew map developed by the US Water Resources Council (WRC). Estimates of the 50-, 100-, and 500-yr floods computed for 29 of these gaging stations using the regional-mean skew techniques are within the 50% confidence limits of frequency curves computed using the WRC skew map. Although the three variations of the regional-mean skew technique were slightly more accurate than the WRC map, there is no appreciable difference between flood estimates computed using the variations of the regional-mean technique and flood estimates computed using the WRC skew map. (Peters-PTT)
Preconfigured, skewed distribution of firing rates in the hippocampus and entorhinal cortex
Mizuseki, Kenji; Buzsáki, György
2013-01-01
Summary Despite the importance of the discharge frequency in neuronal communication, little is known about the firing rate patterns of cortical populations. Using large-scale recordings from multiple layers of the entorhinal-hippocampal loop, we found that firing rates of principal neurons showed a lognormal-like distribution in all brain states. Mean and peak rates within place fields of hippocampal neurons were also strongly skewed. Importantly, firing rates of the same neurons showed reliable correlations in different brain states, testing situations and across familiar and novel environments. The fraction of neurons participating in population oscillations displayed a lognormal pattern. Such skewed rates of individual neurons may be brought about by skewed distribution of synaptic weights, supported by our observation of a lognormal distribution of the efficacy of spike transfer from principal neurons to interneurons. The persistent skewed distribution of firing rates implies that a preconfigured highly active minority dominates information transmission in cortical networks. PMID:23994479
Wong, A M F
2015-02-01
The otolith organs consist of the utricle and saccule. The utricle mediates the utriculo-ocular reflex by detecting horizontal head translation and static head tilt. Skew deviation is a vertical strabismus caused by imbalance of the utriculo-ocular reflex pathway and is commonly caused by lesions in the brainstem or cerebellum. It is associated with abnormal utriculo-ocular reflexes including asymmetric reduction of the translational vestibulo-ocular and ocular counterroll responses. Skew deviation is also associated with head position-dependent changes in ocular torsion and vertical strabismus. The reduction in ocular torsion and vertical strabismus when changing from an upright to supine position in skew deviation allows us to devise a new bedside 'upright-supine test' to differentiate skew deviation from fourth nerve palsy and other causes of vertical strabismus. PMID:25323854
Skewness in large-scale structure and non-Gaussian initial conditions
NASA Technical Reports Server (NTRS)
Fry, J. N.; Scherrer, Robert J.
1994-01-01
We compute the skewness of the galaxy distribution arising from the nonlinear evolution of arbitrary non-Gaussian intial conditions to second order in perturbation theory including the effects of nonlinear biasing. The result contains a term identical to that for a Gaussian initial distribution plus terms which depend on the skewness and kurtosis of the initial conditions. The results are model dependent; we present calculations for several toy models. At late times, the leading contribution from the initial skewness decays away relative to the other terms and becomes increasingly unimportant, but the contribution from initial kurtosis, previously overlooked, has the same time dependence as the Gaussian terms. Observations of a linear dependence of the normalized skewness on the rms density fluctuation therefore do not necessarily rule out initially non-Gaussian models. We also show that with non-Gaussian initial conditions the first correction to linear theory for the mean square density fluctuation is larger than for Gaussian models.
A Thouless formula and Aubry duality for long-range Schrödinger skew-products
NASA Astrophysics Data System (ADS)
Haro, Alex; Puig, Joaquim
2013-05-01
In this paper, we study the dynamical properties of a class of ergodic linear skew-products which includes the linear skew-products defined by quasi-periodic Schrödinger operators and their duals, in Aubry sense, when the potential is a trigonometric polynomial. Notably, these linear skew-products preserve an adapted complex-symplectic structure. We prove a Thouless formula relating the sum of the positive Lyapunov exponents and the logarithmic potential associated with the density of states of the corresponding operator. In particular, for quasi-periodic Schrödinger operators and their duals, we prove an identity for the upper Lyapunov exponent of the skew-product and the sum of the positive Lyapunov exponents of their dual, which generalizes the well-known formula for the Almost Mathieu. We illustrate these identities with some numerical illustrations.
Zhai, Rong-Rong; Jiang, Ai-Ping; Wang, Hai-Bo; Ma, Li; Ren, Xiao-Xin; Jiang, Jin-Feng; Wu, Li; Wei, Ji-Fu; Wang, Jian-Hua
2013-08-01
Altered cytokine profiles and imbalanced frequencies of CD4(+) T helper cell subsets are thought to be linked with HIV-1/AIDS pathogenesis, but the causes need to be further clarified. Histamine, a biogenic amine with many functions, shows enhancement in HIV-1 infected individuals, which are considered to link with disease progression, but is poorly understood. This study investigated histamine-assisted HIV-1 modulation of dendritic cell (DC) functions. Histamine and HIV-1 showed a synergistic role in induction of interleukin-10; histamine inhibited HIV-1-induced IL-12 production from MDDCs (monocyte-derived DCs); notably, histamine augmented HIV-1-induced MDDC functional polarization and skewed naïve T cell differentiation toward regulatory T cells (Tregs). The results indicate the novel role of histamine in HIV-1-induced DC functional regulation, which promoted Treg cell differentiation and up-regulated immunosuppressive factors. These findings help to bridge the correlation between elevated histamine and increased Treg cell frequency in HIV-1 infected individuals, and add to our understanding of HIV-1-induced immunosuppression. PMID:23652320
An Adaptive Method for Reducing Clock Skew in an Accumulative Z-Axis Interconnect System
NASA Technical Reports Server (NTRS)
Bolotin, Gary; Boyce, Lee
1997-01-01
This paper will present several methods for adjusting clock skew variations that occur in a n accumulative z-axis interconnect system. In such a system, delay between modules in a function of their distance from one another. Clock distribution in a high-speed system, where clock skew must be kept to a minimum, becomes more challenging when module order is variable before design.
COMPUTING EXPONENTIALS OF SKEW-SYMMETRIC MATRICES AND LOGARITHMS OF ORTHOGONAL MATRICES
J. Gallier; D. Xu
2000-01-01
The authors show that there is a generalization of Rodrigues' formula for computing the exponential map exp: so(n) ?SO(n) from skew- symmetric matrices to orthogonal matrices when n ? 4, and give a method for computing some determination of the (multivalued) function log: SO(n) ? so(n). The key idea is the decomposition of a skew-symmetric n×n matrix B in terms
Planar-DME: a single-layer zero-skew clock tree router
Andrew B. Kahng; Chung-wen Albert Tsao
1996-01-01
This paper presents new single-layer, i.e., planar-embeddable, clock tree constructions with exactzero skew under either the linear or the Elmore delay model. Our method, called Planar-DME,consists of two parts. The first algorithm, called Linear-Planar-DME, guarantees an optimal planarzero-skew clock tree (ZST) under the linear delay model. The second algorithm, called ElmorePlanar-DME, uses the Linear-Planar-DME connection topology in constructing a low-cost
NASA Technical Reports Server (NTRS)
Majumdar, A. K.
1979-01-01
Expressions are derived for higher-order skewness and excess coefficients using central moments and cumulants up to 8th order. These coefficients are then calculated for three probability distributions: (1) Log-normal, (2) Rice-Nakagami, and (3) Gamma distributions. Curves are given to shown the variation of skewness with excess coefficients for these distributions. These curves are independent of the particular distribution parameters. This method is useful for studying fluctuating phenomena, which obey non-Gaussian statistics.
Climbing techniques for bridge inspection
NASA Astrophysics Data System (ADS)
Kaslan, Erol C.
1998-03-01
California has about 24,000 publicly owned bridges that require routine structural evaluations to comply with National Bridge Inspection Standard (NBIS) mandates. Of these, about 800 are identified as possessing fatigue prone or fracture critical details requiring thorough tactile investigations. Gaining access to bridge elements to perform these investigations has become increasingly difficult and costly. The traditional uses of under bridge inspection trucks, lift equipment and rigging are economically and practically limited by bridge size, structure type, traffic demands and support costs. In some cases, bridges that have become damaged by earthquakes cannot safely support the loads of heavy personnel lift equipment. The California Department of Transportation (Caltrans)'s Office of Structural Materials and Office of Structure Maintenance and Investigations evaluated the use of rock climbing and mountaineering techniques as an alternative means of gaining access for bridge inspections. Under a small research grant, a bridge climbing training course was developed through a local University of California outdoor recreation group and 7 engineers and technicians were initially trained. A comprehensive Code of Safe Practices was created and standards of training, procedures and equipment required for bridge inspections were established. A successful climb investigation on a large, previously inaccessible arch bridge was completed at the end of the training that proved the techniques safe, economical and effective. Within one year, 20 bridge maintenance engineers were trained, and a formal program was established to organize, schedule, equip and certify engineers and technicians for bridge climbing. Several other offices within Caltrans as well as the California Department of Water Resources have since adopted these techniques for specialized structural inspection tasks. Climbing techniques are now used routinely in California as an alterative means of gaining access to bridges and structures, and over 100 bridges have been identified as those where climbing is the only means available to perform structural investigations.
Electrical Actuation Technology Bridging
NASA Technical Reports Server (NTRS)
Hammond, Monica (compiler); Sharkey, John (compiler)
1993-01-01
This document contains the proceedings of the NASA Electrical Actuation Technology Bridging (ELA-TB) Workshop held in Huntsville, Alabama, September 29-October 1, 1992. The workshop was sponsored by the NASA Office of Space Systems Development and Marshall Space Flight Center (MSFC). The workshop addressed key technologies bridging the entire field of electrical actuation including systems methodology, control electronics, power source systems, reliability, maintainability, and vehicle health management with special emphasis on thrust vector control (TVC) applications on NASA launch vehicles. Speakers were drawn primarily from industry with participation from universities and government. In addition, prototype hardware demonstrations were held at the MSFC Propulsion Laboratory each afternoon. Splinter sessions held on the final day afforded the opportunity to discuss key issues and to provide overall recommendations. Presentations are included in this document.
NSDL National Science Digital Library
Grace Eason
2004-11-01
A newly appointed joint hire in the College of Arts and Sciences, Department of Natural Sciences and the College of Education, Department of Middle/Secondary Education, was charged with the responsibility of bridging the communication gap between these two departments and colleges. To meet this challenge, four collaborative projects were developed between the Natural Sciences faculty and Middle/Secondary Education science students that will become formally established in future university courses.
NSDL National Science Digital Library
2010-01-01
In this activity, learners use recycled materials to build a bridge that holds as many potatoes as possible. They investigate weight, height, strength, and measurement as they seek design solutions. The activity instructions include ways to adjust the level of challenge for learners of different ages. Try this at family events or to engage all ages. Available as a web page and a downloadable PDF. Students should have the ability to use tape and scissors.
Update in bridging anticoagulation
Scott Kaatz; David Paje
2011-01-01
Patients treated with a vitamin K antagonist may require interruption of their anticoagulation prior to an invasive procedure\\u000a or surgery, and as a result, may be placed at a higher risk for thromboembolic events during this time. Either low-molecular-weight\\u000a heparin (LMWH) or unfractionated heparin is frequently used to bridge the gap in anticoagulation treatment because of their\\u000a relatively rapid onset
Tacoma Narrows Bridge: Extreme History
NSDL National Science Digital Library
Stretching across the southern portion of Puget Sound, the elegant Tacoma Narrows bridge is considered one of the finest suspension bridges in the United States. The current bridge is the second on the site, as it was constructed in 1950 to serve as a replacement to the famous "Galloping Gertie" bridge, which collapsed in a windstorm in the fall of 1940. Currently, the Washington State Department of Transportation is building a bridge to replace the existing structure, and it is anticipated that it will be completed in 2007. This site offers a host of materials on all three structures, including ample information on the construction of the bridges and their aesthetic appeal. Along with these materials, the site also provides a glossary of related terms, Weird Facts, and some information about the dog "Tubby", who perished when "Galloping Gertie" collapsed on that fateful fall day back in 1940.
Wessendorf, K.O.
1998-07-01
This paper describes the Active-Bridge Oscillator (ABO), a new concept in high-stability oscillator design. The ABO is ab ridge-type oscillator design that is easly to design and overcomes many of the operational and design difficulties associated with standard bridge oscillator designs. The ABO will oscillate with a very stable output amplitude over a wide range of operating conditions without the use of an automatic-level-control (ALC). A standard bridge oscillator design requires an ALC to maintain the desired amplitude of oscillation. for this and other reasons, bridge oscilaltors are not used in mainstream designs. Bridge oscillators are generally relegated to relatively low-volume, high-performance applications. The Colpitts and Pierce designs are the most popular oscillators but are typically less stable than a bridge-type oscillator.
2014-01-01
Background In insect societies, intracolonial genetic variation is predicted to affect both colony efficiency and reproductive skew. However, because the effects of genetic variation on these two colony characteristics have been tested independently, it remains unclear whether they are affected by genetic variation independently or in a related manner. Here we test the effect of genetic variation on colony efficiency and reproductive skew in a rhinotermitid termite, Reticulitermes speratus, a species in which female-female pairs can facultatively found colonies. We established colonies using two types of female-female pairs: colonies founded by sisters (i.e., sister-pair colonies) and those founded by females from different colonies (i.e., unrelated-pair colonies). Colony growth and reproductive skew were then compared between the two types of incipient colonies. Results At 15 months after colony foundation, unrelated-pair colonies were larger than sister-pair colonies, although the caste ratio between workers and nymphs, which were alternatively differentiated from young larvae, did not differ significantly. Microsatellite DNA analyses of both founders and their parthenogenetically produced offspring indicated that, in both sister-pair and unrelated-pair colonies, there was no significant skew in the production of eggs, larvae, workers and soldiers. Nymph production, however, was significantly more skewed in the sister-pair colonies than in unrelated-pair colonies. Because nymphs can develop into winged adults (alates) or nymphoid reproductives, they have a higher chance of direct reproduction than workers in this species. Conclusions Our results support the idea that higher genetic variation among colony members could provide an increase in colony productivity, as shown in hymenopteran social insects. Moreover, this study suggests that low genetic variation (high relatedness) between founding females increases reproductive skew via one female preferentially channeling her relatives along the reproductive track. This study thus demonstrated that, in social insects, intracolonial genetic variation can simultaneously affect both colony efficiency and reproductive skew. PMID:25123355
Static performance investigation of a skewed-throat multiaxis thrust-vectoring nozzle concept
NASA Technical Reports Server (NTRS)
Wing, David J.
1994-01-01
The static performance of a jet exhaust nozzle which achieves multiaxis thrust vectoring by physically skewing the geometric throat has been characterized in the static test facility of the 16-Foot Transonic Tunnel at NASA Langley Research Center. The nozzle has an asymmetric internal geometry defined by four surfaces: a convergent-divergent upper surface with its ridge perpendicular to the nozzle centerline, a convergent-divergent lower surface with its ridge skewed relative to the nozzle centerline, an outwardly deflected sidewall, and a straight sidewall. The primary goal of the concept is to provide efficient yaw thrust vectoring by forcing the sonic plane (nozzle throat) to form at a yaw angle defined by the skewed ridge of the lower surface contour. A secondary goal is to provide multiaxis thrust vectoring by combining the skewed-throat yaw-vectoring concept with upper and lower pitch flap deflections. The geometric parameters varied in this investigation included lower surface ridge skew angle, nozzle expansion ratio (divergence angle), aspect ratio, pitch flap deflection angle, and sidewall deflection angle. Nozzle pressure ratio was varied from 2 to a high of 11.5 for some configurations. The results of the investigation indicate that efficient, substantial multiaxis thrust vectoring was achieved by the skewed-throat nozzle concept. However, certain control surface deflections destabilized the internal flow field, which resulted in substantial shifts in the position and orientation of the sonic plane and had an adverse effect on thrust-vectoring and weight flow characteristics. By increasing the expansion ratio, the location of the sonic plane was stabilized. The asymmetric design resulted in interdependent pitch and yaw thrust vectoring as well as nonzero thrust-vector angles with undeflected control surfaces. By skewing the ridges of both the upper and lower surface contours, the interdependency between pitch and yaw thrust vectoring may be eliminated and the location of the sonic plane may be further stabilized.
The Adaptive Use Bridge Project
NSDL National Science Digital Library
University of Massachusetts, Amherst
The Adaptive Use Bridge Project website is a repository for work being conducted at the University of Massachusetts, Amherst, in which historic iron bridges are rehabilitated, documented, and analyzed. The purpose of the project is to preserve the civil engineering heritage of New England and to develop instructional material for use in undergraduate civil engineering curricula. Upon completion of this long-term project, a protocol for adaptive pedestrian use of historic bridges will be created.
BRIDGE: Briefings on Development & Gender
NSDL National Science Digital Library
BRIDGE (briefings on development and gender) is an information service provided by the Institute of Development Studies (IDS) at the University of Sussex. BRIDGE supplies development agencies with briefings that "present state of the art research findings, review current policy debates, synthesize best practice, and evaluate strategies for translating gender policies into practice." This site includes full-text BRIDGE publications, a bibliographic database, and links to other gender and development resources.
47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.
Code of Federal Regulations, 2010 CFR
2010-10-01
...Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section...SERVICES Radiotelephone Installations Required by the Bridge-to-Bridge Act § 80.1007...
47 CFR 80.331 - Bridge-to-bridge communication procedure.
Code of Federal Regulations, 2010 CFR
2010-10-01
...Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge communication procedure. 80.331 Section 80...Alarm, Urgency and Safety Procedures § 80.331 Bridge-to-bridge communication procedure. (a)...
West Point Bridge Design Contest
NSDL National Science Digital Library
The second annual West Point Bridge Design Contest concluded in May 2003. Although it is uncertain whether the contest will receive funding for future competitions, its Web site has a number of educational resources for middle and high school students. The main feature is the bridge design software, which allows the user to "model, test, and optimize a steel highway bridge, based on realistic specifications, constraints, and performance criteria." Completed designs can be submitted online for unofficial judging. The book, Designing and Building File-Folder Bridges, can also be freely downloaded. [CL
West Point Bridge Design Contest
NSDL National Science Digital Library
The West Point Bridge Design Contest Web site has a number of educational resources for middle and high school students. The main feature is the bridge design software, which allows the user to "model, test, and optimize a steel highway bridge, based on realistic specifications, constraints, and performance criteria." Completed designs can be submitted online for unofficial judging. The book, Designing and Building File-Folder Bridges, can also be freely downloaded. This site is also reviewed in the July 4, 2003 NSDL MET Report.
West Point Bridge Design Contest
NSDL National Science Digital Library
2003-01-01
The second annual West Point Bridge Design Contest concluded in May 2003. Although it is uncertain whether the contest will receive funding for future competitions, its Web site has a number of educational resources for middle and high school students. The main feature is the bridge design software, which allows the user to "model, test, and optimize a steel highway bridge, based on realistic specifications, constraints, and performance criteria." Completed designs can be submitted online for unofficial judging. The book, Designing and Building File-Folder Bridges, can also be freely downloaded. This site is also reviewed in the July 4, 2003 NSDL MET Report.
Nasal Bridge Intramuscular Hemangioma
Hamir Basah, Zulkifli; Ramza Ramli, Ramiza; Gayadh, Maha Khadum; Mutum, Samarendra Singh
2015-01-01
Intramuscular haemangioma (IMH) is a benign mesenchymal tumour. It appears as a deep, nontender mass within the soft tissue, particularly in the extremities. This tumour may not be obvious on clinical examination. Head and neck IMHs represent only 13.5% of the total IMHs. The most common site for a head and neck IMH is the masseter muscle, followed by trapezius, sternocleidomastoid, and very rarely temporalis muscle. We present a patient with left nasal bridge swelling which was excised and histologically confirmed as intramuscular hemangioma. PMID:25709848
NSDL National Science Digital Library
Twin Cities Public Television, Inc.
2006-01-01
In this quick activity (page 1 of the PDF), learners will test how many pennies a flat paper index card bridging the gap between two stacks of books is able to support. Then, learners alter the structure of the same card by folding it accordion-style and retest by again stacking pennies on top. Learners look for a relationship between the number of folds and the number of pennies the card can hold by creating a scatter plot. Relates to the linked video, DragonflyTV: Tug O’ War.
NSDL National Science Digital Library
Bobby JeanPierre
2008-09-01
The West Point Bridge Design (WPBD) building project engages students in project-based learning by giving them a real-life problem to solve. By using technology, students are able to become involved in solving problems that they normally would not encounter. Involvement with interactive websites, such as WPBD, assists students in using higher-level thinking skills and problem solving (NSTA 2006). It is important that we keep our students engaged in learning science, as the scientific society of tomorrow depends upon the science students of today.
Extended bridge algorithms for large networks
W. D. Sincoskie; C. J. Cotton
1988-01-01
A network bridge is a device that operates at the ISO data link level and routes packets across extended networks, commonly composed of multiple local area networks (LANs) and bridges. A set of algorithms that greatly extends the application of the network bridge is presented. This multitree bridge algorithm allows networks of arbitrary topology and capacity to use bridge routing.
Prediction of Scour Depth around Bridge Piers using Adaptive Neuro-Fuzzy Inference Systems (ANFIS)
NASA Astrophysics Data System (ADS)
Valyrakis, Manousos; Zhang, Hanqing
2014-05-01
Earth's surface is continuously shaped due to the action of geophysical flows. Erosion due to the flow of water in river systems has been identified as a key problem in preserving ecological health of river systems but also a threat to our built environment and critical infrastructure, worldwide. As an example, it has been estimated that a major reason for bridge failure is due to scour. Even though the flow past bridge piers has been investigated both experimentally and numerically, and the mechanisms of scouring are relatively understood, there still lacks a tool that can offer fast and reliable predictions. Most of the existing formulas for prediction of bridge pier scour depth are empirical in nature, based on a limited range of data or for piers of specific shape. In this work, the application of a Machine Learning model that has been successfully employed in Water Engineering, namely an Adaptive Neuro-Fuzzy Inference System (ANFIS) is proposed to estimate the scour depth around bridge piers. In particular, various complexity architectures are sequentially built, in order to identify the optimal for scour depth predictions, using appropriate training and validation subsets obtained from the USGS database (and pre-processed to remove incomplete records). The model has five variables, namely the effective pier width (b), the approach velocity (v), the approach depth (y), the mean grain diameter (D50) and the skew to flow. Simulations are conducted with data groups (bed material type, pier type and shape) and different number of input variables, to produce reduced complexity and easily interpretable models. Analysis and comparison of the results indicate that the developed ANFIS model has high accuracy and outstanding generalization ability for prediction of scour parameters. The effective pier width (as opposed to skew to flow) is amongst the most relevant input parameters for the estimation.
Experimental Study of the Effect of a Skewed Inlet Flow Profile on Stenotic Flow Development
NASA Astrophysics Data System (ADS)
Peterson, Sean; Plesniak, Michael
2006-11-01
Blood flows through a constricted artery, or stenosis, are known to be sensitive to geometric and velocity perturbations. The effect of a skewed mean inlet velocity on the flow development distal to an axisymmetric stenosis (modeling a diseased carotid artery) driven by a physiological forcing waveform is studied. In the physiological environment, a skewed mean velocity profile (plus a secondary flow) can be produced, e.g. by vessel curvature. This study attempts to decouple the mean flow profile and the secondary flow in order to ascertain the impact of each disturbance individually. The skewed inlet profile is produced by a porous insert designed to replicate the mean flow profile downstream of a bend. LDV and PIV data are acquired to assess the impact of the skewed velocity profile on flow features. The skewed velocity profile was observed to promote earlier reattachment of the stenotic jet by deflecting it towards the wall sooner than in a baseline study. In a second experiment, the impact of secondary flow on the stenotic jet development is investigated by the introduction of a 180 bend upstream of the stenosis. The mean flow profile is similar in character to that produced by the porous insert.
NASA Astrophysics Data System (ADS)
Kim, Tae-Woo; Chang, Jung-Hwan
2013-08-01
This paper suggests an effective step-skew method to reduce the cogging torque of a surface-mounted permanent magnet synchronous motor (SPMSM). The main concept of the proposed method is to adjust each step length by considering the non-uniform air gap flux density distribution in the axial direction. The results show that the proposed step-skew method reduces the net cogging torque compared with the conventional step-skew method and is more effective for smaller stacking lengths and larger skew steps.
49 CFR 236.713 - Bridge, movable.
Code of Federal Regulations, 2010 CFR
2010-10-01
...Transportation 4 2010-10-01 2010-10-01 false Bridge, movable. 236.713 Section 236.713 Transportation...SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.713 Bridge, movable. That section of a structure bridging a...
33 CFR 115.40 - Bridge repairs.
Code of Federal Regulations, 2010 CFR
2010-07-01
...Waters 1 2010-07-01 2010-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE...
A METHOD TO MEASURE THE SKEW QUADUPOLE STRENGTHS IN THE SIS-18 USING TWO BPMS.
FRANCHI,A.BEIER,T.KIRK,M.MORITZ,P.RUMOLO,G.TOMAS,R.
2004-07-05
In the GSI synchrotron SIS-18 a new set of skew quadrupoles has been installed to improve the multi-turn-injection. Anew method based on the measurement of the resonance driving terms (RDT) has been proposed to cross-check the nominal values and polarities of their gradients. Once a beam is transversely kicked, it experiences oscillations whose spectrum contains both the betatron tune line and secondary lines. The amplitude of each line is proportional to the strength of the multipoles, such as skew quadrupoles and sextupoles, present in the lattice. In this paper, a recursive algorithm to derive the magnet strength from the spectral lines and the application of this method to the eight skew quadrupoles in the SIS-18 are presented.
The log-dynamic brain: how skewed distributions affect network operations.
Buzsáki, György; Mizuseki, Kenji
2014-04-01
We often assume that the variables of functional and structural brain parameters - such as synaptic weights, the firing rates of individual neurons, the synchronous discharge of neural populations, the number of synaptic contacts between neurons and the size of dendritic boutons - have a bell-shaped distribution. However, at many physiological and anatomical levels in the brain, the distribution of numerous parameters is in fact strongly skewed with a heavy tail, suggesting that skewed (typically lognormal) distributions are fundamental to structural and functional brain organization. This insight not only has implications for how we should collect and analyse data, it may also help us to understand how the different levels of skewed distributions - from synapses to cognition - are related to each other. PMID:24569488
The log-dynamic brain: how skewed distributions affect network operations
Buzsáki, György; Mizuseki, Kenji
2014-01-01
We often assume that the variables of functional and structural brain parameters — such as synaptic weights, the firing rates of individual neurons, the synchronous discharge of neural populations, the number of synaptic contacts between neurons and the size of dendritic boutons — have a bell-shaped distribution. However, at many physiological and anatomical levels in the brain, the distribution of numerous parameters is in fact strongly skewed with a heavy tail, suggesting that skewed (typically lognormal) distributions are fundamental to structural and functional brain organization. This insight not only has implications for how we should collect and analyse data, it may also help us to understand how the different levels of skewed distributions — from synapses to cognition — are related to each other. PMID:24569488
A Berger-type theorem for metric connections with skew-symmetric torsion
NASA Astrophysics Data System (ADS)
Reggiani, Silvio
2013-03-01
We prove a Berger-type theorem which asserts that if the orthogonal subgroup generated by the torsion tensor (pulled back to a point by parallel transport) of a metric connection with skew-symmetric torsion is not transitive on the sphere, then the space must be locally isometric to a Lie group with a bi-invariant metric or its symmetric dual (we assume the space to be locally irreducible). We also prove that a (simple) Lie group with a bi-invariant metric admits only two flat metric connections with skew-symmetric torsion: the two flat canonical connections. In particular, we get a refinement of a well-known theorem of Cartan and Schouten. Finally, we show that the holonomy group of a metric connection with skew-symmetric torsion on these spaces generically coincides with the Riemannian holonomy.
Elevated Mortality among Birds in Chernobyl as Judged from Skewed Age and Sex Ratios
Møller, Anders Pape; Bonisoli-Alquati, Andrea; Rudolfsen, Geir; Mousseau, Timothy A.
2012-01-01
Background Radiation has negative effects on survival of animals including humans, although the generality of this claim is poorly documented under low-dose field conditions. Because females may suffer disproportionately from the effects of radiation on survival due to differences in sex roles during reproduction, radiation-induced mortality may result in male-skewed adult sex ratios. Methodology/Principal Finding We estimated the effects of low-dose radiation on adult survival rates in birds by determining age ratios of adults captured in mist nets during the breeding season in relation to background radiation levels around Chernobyl and in nearby uncontaminated control areas. Age ratios were skewed towards yearlings, especially in the most contaminated areas, implying that adult survival rates were reduced in contaminated areas, and that populations in such areas could only be maintained through immigration from nearby uncontaminated areas. Differential mortality in females resulted in a strongly male-skewed sex ratio in the most contaminated areas. In addition, males sang disproportionately commonly in the most contaminated areas where the sex ratio was male skewed presumably because males had difficulty finding and acquiring mates when females were rare. The results were not caused by permanent emigration by females from the most contaminated areas because none of the recaptured birds had changed breeding site, and the proportion of individuals with morphological abnormalities did not differ significantly between the sexes for areas with normal and higher levels of contamination. Conclusions/Significance These findings are consistent with the hypothesis that the adult survival rate of female birds is particularly susceptible to the effects of low-dose radiation, resulting in male skewed sex ratios at high levels of radiation. Such skewed age ratios towards yearlings in contaminated areas are consistent with the hypothesis that an area exceeding 30,000 km2 in Chernobyl’s surroundings constitutes an ecological trap that causes dramatic excess mortality. PMID:22514722
NASA Technical Reports Server (NTRS)
Levine, Joel S.
1990-01-01
Most burning of biomass is the result of human activity, and on a global scale it is increasing. Tropospheric concentrations of CO2, CO, CH4, non-methane hydrocarbons, and ozone are all increasing with time; global biomass burning may make an important contribution to this increase and thus to potential global climate change. The nitrogen cycle also can have important climatic effects. Nitrous oxide put into the atmosphere by biomass burning is a greenhouse gas 250 times more powerful (molecule for molecule) than carbon dioxide. Nitric oxide, as well as being a photochemical precursor of ozone, a major pollutant in the troposphere, produces nitric acid, the fastest-growing component of acid rain. Hence, the new bridge in the nitrogen cycle is of more than mere technical interest.
NSDL National Science Digital Library
Bridging the Watershed (BTW) is an outreach program of the Alice Ferguson Foundation in partnership with the National Park Service and area schools. It promotes national parks as learning laboratories and provides a model that can be replicated in other parks and watersheds. The program is based in the Washington, D.C. metropolitan area. BTW partners share a fundamental goal to educate the public about the Potomac River and Chesapeake Bay watersheds in order to heighten awareness and develop stewardship for these resources. Science curriculum modules have been developed for high school students studying Earth science, chemistry, and the life sciences. Each module is composed of performance-based activities in which students examine and analyze the health of their watershed by applying science, math, problem-solving and action skills. Students gather authentic data to assess and problem solve real-world issues in the parks and watershed.
NSDL National Science Digital Library
Stanford University's Bridge Project: Strengthening K-16 Transition Policies emphasizes that "reforms affecting K-12 and higher education must occur across systems in order to achieve the desired outcomes." Their approach is to improve opportunities for all students to enter and succeed in higher education by strengthening the alignment between higher education admissions-related requirements and K-12 curriculum frameworks, standards, and assessments. They conduct research that is meant to inform educational institutions and federal, state, and local agencies through descriptive analysis of the policies, identification of "disjunctures that exist in the current policy environment," and recommendations for improving the current system. Details about this program as well as their policy reports and briefs are available from their website.
Marie Touchon; Eduardo P. C. Rocha
2007-01-01
Compositional asymmetries are pervasive in DNA sequences. They are the result of the asymmetric interactions between DNA and cellular mechanisms such as replication and transcription. Here, we review many of the methods that have been proposed over the years to analyse com- positional asymmetries in DNA sequences. Among these we list GC skews, oligonucleotide skews and wavelets, which among other
Marie Touchon; Eduardo P. C. Rocha
2008-01-01
Compositional asymmetries are pervasive in DNA sequences. They are the result of the asymmetric interactions between DNA and cellular mechanisms such as replication and transcription. Here, we review many of the methods that have been proposed over the years to analyse compositional asymmetries in DNA sequences. Among these we list GC skews, oligonucleotide skews and wavelets, which among other uses
Jang-Young Choi; Seok-Myeong Jang; Kyoung-Jin Ko
2009-01-01
This paper deals with experimental verification and analytical approach to influence stator skew on electromagnetic performance of a permanent magnet generator (PMG) with multipole rotor. The analytical expressions for magnetic field distributions are due to permanent magnets and the two-dimensional permeance function considering skew effects are established. On the basis of these analytical solutions, the analytical solutions for cogging torque
MAY 1998 831G R I F F I E S The GentMcWilliams Skew Flux
to be used in ocean models. With this closure, certain adiabatic stirring effects from ocean mesoscale eddies Dynamics Laboratory, Princeton University, Princeton, New Jersey (Manuscript received 5 May 1997, in final) eddy-induced transport in terms of a skew-diffusive flux. A skew-diffusive tracer flux is directed
NASA Astrophysics Data System (ADS)
Choi, Jang-Young; Jang, Seok-Myeong; Ko, Kyoung-Jin
2009-04-01
This paper deals with experimental verification and analytical approach to influence stator skew on electromagnetic performance of a permanent magnet generator (PMG) with multipole rotor. The analytical expressions for magnetic field distributions are due to permanent magnets and the two-dimensional permeance function considering skew effects are established. On the basis of these analytical solutions, the analytical solutions for cogging torque and back-emf considering skew effects are also derived. Then, by applying estimated electrical parameters to a simple equivalent circuit of one phase for the PMG, output performances of the PMG with/without a skewed stator are investigated. Finally, by confirming that all analytical results are validated extensively by nonlinear finite element calculations and measurements, the validity of analysis methods presented in this paper is verified, and the influence stator skew on cogging torque, back-emf, and output performances of the PMG is also clearly described.
Skew angle effects in shingled magnetic recording system with double/triple reader head array
NASA Astrophysics Data System (ADS)
Elidrissi, Moulay Rachid; Sann Chan, Kheong; Greaves, Simon; Kanai, Yasushi; Muraoka, Hiroaki
2014-05-01
Shingled Magnetic Recording (SMR) is a scheme used to extend the life of the current perpendicular magnetic recording technology. SMR enables writing narrow tracks with a wide writer. Currently, SMR employs a single reader and will suffer inter-track interference (ITI) as the tracks become comparable in width to the reader. ITI can be mitigated by using narrower readers; however, narrower readers suffer from increased reader noise. Another approach to combat ITI is to process 2D readback and use ITI cancellation schemes to retrieve the data track. Multiple readbacks can be obtained either with a single reader and multiple revolutions or with a reader array. The former suffers from increased readback latency. In this work, we focus on the latter. When using a reader array, the skew angle poses major challenges. During writing, there is increased adjacent track erasure, and during readback the effective reader pitch varies and there is an increase in the 2D intersymbol interference caused by the rotated reader profile. In this work, we run micromagnetic simulations at different skew angles to train the grain flipping probability model, and then evaluate raw bit channel error rate performance at skew. In particular, we investigate the performance degradation caused by skewing of the 2 or 3 read head array for various read-head geometries.
The effect of skewness and kurtosis on the robustness of linear mixed models.
Arnau, Jaume; Bendayan, Rebecca; Blanca, María J; Bono, Roser
2013-09-01
This study analyzes the robustness of the linear mixed model (LMM) with the Kenward-Roger (KR) procedure to violations of normality and sphericity when used in split-plot designs with small sample sizes. Specifically, it explores the independent effect of skewness and kurtosis on KR robustness for the values of skewness and kurtosis coefficients that are most frequently found in psychological and educational research data. To this end, a Monte Carlo simulation study was designed, considering a split-plot design with three levels of the between-subjects grouping factor and four levels of the within-subjects factor. Robustness is assessed in terms of the probability of type I error. The results showed that (1) the robustness of the KR procedure does not differ as a function of the violation or satisfaction of the sphericity assumption when small samples are used; (2) the LMM with KR can be a good option for analyzing total sample sizes of 45 or larger when their distributions are normal, slightly or moderately skewed, and with different degrees of kurtosis violation; (3) the effect of skewness on the robustness of the LMM with KR is greater than the corresponding effect of kurtosis for common values; and (4) when data are not normal and the total sample size is 30, the procedure is not robust. Alternative analyses should be performed when the total sample size is 30. PMID:23299397
Large-Scale Age-Dependent Skewed Sex Ratio in a Sexually Dimorphic Avian Scavenger
Lambertucci, Sergio A.; Carrete, Martina; Donázar, José Antonio; Hiraldo, Fernando
2012-01-01
Age-dependent skewed sex ratios have been observed in bird populations, with adult males generally outnumbering females. This trend is mainly driven by higher female mortality, sometimes associated with anthropogenic factors. Despite the large amount of work on bird sex ratios, research examining the spatial stability of adult sex ratios is extremely scarce. The Andean condor (Vultur gryphus) is the only bird of prey with strong sexual dimorphism favouring males (males are 30% heavier than females). By examining data from most of its South-American range, we show that while the juvenile sex ratio is balanced, or even female-skewed, the sex ratio becomes increasing male-skewed with age, with adult males outnumbering females by >20%, and, in some cases by four times more. This result is consistent across regions and independent of the nature of field data. Reasons for this are unknown but it can be hypothesized that the progressive disappearance of females may be associated with mortality caused by anthropogenic factors. This idea is supported by the asymmetric habitat use by the two sexes, with females scavenging in more humanized areas. Whatever the cause, male-skewed adult sex ratios imply that populations of this endangered scavenger face higher risks of extinction than previously believed. PMID:23029488
One-Sided Confidence Intervals for Means of Positively Skewed Distributions
Xiao-Hua Zhou; Sujuan Gao
2000-01-01
In this article, we study the coverage accuracy of one-sided confidence intervals based on Hall's and Johnson's transformation methods and their bootstrap versions for means of positively skewed distributions. We confirm Hall's finding that a lower endpoint confidence interval based on his transformation method provides better coverage accuracy than Johnson's transformation method. We also find that Hall's upper endpoint confidence
Research article Breeding system and reproductive skew in a highly polygynous ant population
Alvarez, Nadir
Research article Breeding system and reproductive skew in a highly polygynous ant population C determinants of nest kin structure, we conducted a detailed analysis of the breeding system of the ant Formica a sub-sample of queens to assess their reproductive status. We also used microsatellites to estimate
RIS-M-2353 A PARAMETRIC DESCRIPTION OF A SKEWED PUFF IN THE DIABATIC
RISÃ?-M-2353 A PARAMETRIC DESCRIPTION OF A SKEWED PUFF IN THE DIABATIC SURFACE LAYER Torben puff diffusion model. INIS descriptors: AIR POLLUTION; CLUSTER EMMISSION MODEL; DIFFUSION; GAUSSIAN of vertical puff diffusion 5 2.2. Numerical solutions 12 2.3. Basalts 13 3. THE MODEL 14 3.1. Horisontal puff
A PARAMETRIC DESCRIPTION OF A SKEWED PUFF IN THE DIABATIC SURFACE LAYER
Ris0-R~476 A PARAMETRIC DESCRIPTION OF A SKEWED PUFF IN THE DIABATIC SURFACE LAYER Torben Mikkelsen, and unstable surface layers is parameterized in a form appropriate for use with an operational puff diffusion report (Ris0-R-476) is part of the thesis: FORMULATION AND EXPERIMENTAL EVALUATION OF AN OPERATIONAL PUFF
Dever, Jennifer A.
for selection M. C. LORENZI & G. SELLA Department of Animal and Human Biology, University of Turin, Turin, Italy for Correspondence: M.C. Lorenzi, Department of Animal and Human Biology, University of Turin, Italy, Via Accademia, the reproductive skew for the female function becomes greater than that for the male function, moving from monogamy
Using social parasitism to test reproductive skew models in a primitively eusocial wasp
Green, Jonathan P.; Cant, Michael A.; Field, Jeremy
2014-01-01
Remarkable variation exists in the distribution of reproduction (skew) among members of cooperatively breeding groups, both within and between species. Reproductive skew theory has provided an important framework for understanding this variation. In the primitively eusocial Hymenoptera, two models have been routinely tested: concessions models, which assume complete control of reproduction by a dominant individual, and tug-of-war models, which assume on-going competition among group members over reproduction. Current data provide little support for either model, but uncertainty about the ability of individuals to detect genetic relatedness and difficulties in identifying traits conferring competitive ability mean that the relative importance of concessions versus tug-of-war remains unresolved. Here, we suggest that the use of social parasitism to generate meaningful variation in key social variables represents a valuable opportunity to explore the mechanisms underpinning reproductive skew within the social Hymenoptera. We present a direct test of concessions and tug-of-war models in the paper wasp Polistes dominulus by exploiting pronounced changes in relatedness and power structures that occur following replacement of the dominant by a congeneric social parasite. Comparisons of skew in parasitized and unparasitized colonies are consistent with a tug-of-war over reproduction within P. dominulus groups, but provide no evidence for reproductive concessions. PMID:24990668
An Inconvenient Sea Truth: Spread, Steepness, and Skewness of Surface Slopes
Walter Munk
2009-01-01
Bréon and Henriot (BH) have collected eight million globally distributed satellite images of sunglitter, which yield a few simple, robust rules about the statistics of surface slopes: 1) constant angular spread, 2) linear steepness, and 3) sigmoid (near stepwise) skewness (all with respect to wind speed). Yet the information is sparse because it says nothing about time and space scales.
Bayesian Non-parametric Modeling With Skewed and Heavy-tailed Data
Draper, David
variable scale Â· Risk assessment for nuclear waste disposal: Frequentist and Bayesian non care plus in-home geriatric assessment (IHGA): preventive medicine in which each person's medical: Â· In-home geriatric assessment: Parametric and Bayesian non-parametric modeling of skewed and over
On the Out-of-Sample Importance of Skewness and Asymmetric Dependence for Asset Allocation
Andrew J. Patton
2004-01-01
Recent studies in the empirical finance literature have reported evidence of two types of asymmetries in the joint distribution of stock returns. The first is skewness in the distribution of individual stock returns. The second is an asymmetry in the dependence between stocks: stock returns appear to be more highly correlated during market downturns than during market upturns. In this
Preconfigured, skewed distribution of firing rates in the hippocampus and entorhinal cortex.
Mizuseki, Kenji; Buzsáki, György
2013-09-12
Despite the importance of the discharge frequency in neuronal communication, little is known about the firing-rate patterns of cortical populations. Using large-scale recordings from multiple layers of the entorhinal-hippocampal loop, we found that the firing rates of principal neurons showed a lognormal-like distribution in all brain states. Mean and peak rates within place fields of hippocampal neurons were also strongly skewed. Importantly, firing rates of the same neurons showed reliable correlations in different brain states and testing situations, as well as across familiar and novel environments. The fraction of neurons that participated in population oscillations displayed a lognormal pattern. Such skewed firing rates of individual neurons may be due to a skewed distribution of synaptic weights, which is supported by our observation of a lognormal distribution of the efficacy of spike transfer from principal neurons to interneurons. The persistent skewed distribution of firing rates implies that a preconfigured, highly active minority dominates information transmission in cortical networks. PMID:23994479
On Some Confidence Intervals for Estimating the Mean of a Skewed Population
ERIC Educational Resources Information Center
Shi, W.; Kibria, B. M. Golam
2007-01-01
A number of methods are available in the literature to measure confidence intervals. Here, confidence intervals for estimating the population mean of a skewed distribution are considered. This note proposes two alternative confidence intervals, namely, Median t and Mad t, which are simple adjustments to the Student's t confidence interval. In…
Parallel spinors and connections with skew-symmetric torsion in string theory
Thomas Friedrich; Stefan Ivanov
2001-01-01
We describe all almost contact metric, almost hermitian and $G_2$-structures admitting a connection with totally skew-symmetric torsion tensor, and prove that there exists at most one such connection. We investigate its torsion form, its Ricci tensor, the Dirac operator and the $\\\
Heat transfer in rotating serpentine passages with trips skewed to the flow
B. V. Johnson; J. H. Wagner; G. D. Steuber; F. C. Yeh
1994-01-01
Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large-scale, multipass, heat transfer model with both radially inward and outward flow. Trip strips, skewed at 45 deg to the flow direction, were machined on the leading and trailing surfaces of the radial
Spatial involute gearing -a new type of skew gears Hellmuth Stachel
Stachel, Hellmuth
Spatial involute gearing - a new type of skew gears Hellmuth Stachel Institute of Discrete stachel@dmg.tuwien.ac.at Abstract This is a geometric approach to spatial involute gearing which has recently been developed by Jack Phillips [4]. Due to Phillips' fundamental theorems helical involute gears
A real-time embedded solution for skew correction in banknote analysis
Adnan Rashid; Andrea Prati; Rita Cucchiara
2011-01-01
Several industrial applications do require embedded solutions both for compacting the hardware occupation and reducing energy consumption, and for achieving high speed performance. This paper presents a computer vision system developed for correcting image skew in applications for banknote analysis and classification. The system must be very efficient and run on a fixed-point DSP with limited computational resources. Consequently, we
Lie bundle on the space of deformed skew-symmetric matrices
NASA Astrophysics Data System (ADS)
Dobrogowska, Alina; Goli?ski, Tomasz
2014-11-01
We study a Lie algebra A_{a_1,ldots ,a_{n-1}} of deformed skew-symmetric n × n matrices endowed with a Lie bracket given by a choice of deformed symmetric matrix. The deformations are parametrized by a sequence of real numbers a1, …, an - 1. Using isomorphism (A_{a_1,ldots ,a_{n-1}})^*
Saltzman, Wendy; Digby, Leslie J; Abbott, David H
2009-02-01
Common marmosets are cooperatively breeding monkeys that exhibit high reproductive skew: most subordinate females fail to reproduce, while others attempt to breed but produce very few surviving infants. An extensive dataset on the mechanisms limiting reproduction in laboratory-housed and free living subordinate females provides unique insights into the causes of reproductive skew. Non-breeding adult females undergo suppression of ovulation and inhibition of sexual behaviour; however, they receive little or no aggression or mating interference by dominants and do not exhibit behavioural or physiological signs of stress. Breeding subordinate females receive comparable amounts of aggression to non-breeding females but are able to conceive, gestate and lactate normally. In groups containing two breeding females,however, both dominant and subordinate breeders kill one another's infants. These findings suggest that preconception reproductive suppression is not imposed on subordinate females by dominants, at a proximate level, but is instead self-imposed by most subordinates, consistent with restraint models of reproductive skew. In contrast to restraint models, however, this self-suppression probably evolved not in response to the threat of eviction by dominant females but in response to the threat of infanticide. Thus,reproductive skew in this species appears to be generated predominantly by subordinate self-restraint, in a proximate sense, but ultimately by dominant control over subordinates' reproductive attempts. PMID:18945663
NASA Astrophysics Data System (ADS)
Nidzieko, N. J.; Ralston, D. K.
2012-03-01
It is often assumed that, in short, shallow estuaries, at leading order velocity and elevation are exactly out of phase, so that duration asymmetries in the rise and fall of the tide should be manifest as skewed velocities. We observed alternating ebb- and flood-dominant velocity skew in response to the spring-neap modulation of incident asymmetry generated by the mixed, mainly semidiurnal astronomical tides within the macrotidal Skagit River delta in Puget Sound, Washington. We describe three factors that may contribute to local asymmetries: (1) ebb dominance caused by phase lags between the surface gradient and local depth, (2) ebb dominance due to fluvial discharge, and (3) near-bed flood dominance due to baroclinicity. Large spring tides led to greater frictionally generated phase lags and resulted in ebb-dominant velocity skew. This ebb dominance caused by tidal drainage was reinforced by fluvial discharge across the tidal flat at lower-low water. The baroclinic component of this discharge, however, produced flood-dominant near-bed velocity skew that countered the ebb dominance of the frictional effects. The balance of these processes depends strongly on the spring-neap cycle, magnitude of river discharge, and position within the tidal flat and channel system. Our observations are notable in the context of previous studies describing these processes because our analyses indicate that these mechanisms are relevant over very short spatial scales of just a few kilometers and in very shallow systems.
Skewness in the cosmic microwave background anisotropy from an inflationary gravity wave background
Souradeep, Tarun
Skewness in the cosmic microwave background anisotropy from an inflationary gravity wave background In the context of inflationary scenarios, the observed large angle anisotropy of the cosmic microwave background , the cosmic microwave background CMB has proved to be an ex- tremely significant observational guide in our
Skewness in the cosmic microwave background anisotropy from an inflationary gravity wave background
Souradeep, Tarun
Skewness in the cosmic microwave background anisotropy from an inflationary gravity wave background microwave background ~CMB! temperature is believed to probe the primordial metric perturbations from. INTRODUCTION Since its discovery by Penzias and Wilson @1#, the cosmic microwave background ~CMB! has proved
Lu, Xiaosun; Huang, Yangxin
2014-07-20
It is a common practice to analyze complex longitudinal data using nonlinear mixed-effects (NLME) models with normality assumption. The NLME models with normal distributions provide the most popular framework for modeling continuous longitudinal outcomes, assuming individuals are from a homogeneous population and relying on random-effects to accommodate inter-individual variation. However, the following two issues may standout: (i) normality assumption for model errors may cause lack of robustness and subsequently lead to invalid inference and unreasonable estimates, particularly, if the data exhibit skewness and (ii) a homogeneous population assumption may be unrealistically obscuring important features of between-subject and within-subject variations, which may result in unreliable modeling results. There has been relatively few studies concerning longitudinal data with both heterogeneity and skewness features. In the last two decades, the skew distributions have shown beneficial in dealing with asymmetric data in various applications. In this article, our objective is to address the simultaneous impact of both features arisen from longitudinal data by developing a flexible finite mixture of NLME models with skew distributions under Bayesian framework that allows estimates of both model parameters and class membership probabilities for longitudinal data. Simulation studies are conducted to assess the performance of the proposed models and methods, and a real example from an AIDS clinical trial illustrates the methodology by modeling the viral dynamics to compare potential models with different distribution specifications; the analysis results are reported. PMID:24623529
Bayesian Two-part Tobit Models with Left-Censoring, Skewness and Non-Ignorable Missingness.
Dagne, Getachew A; Huang, Yangxin
2014-06-01
ABSTRACT In a longitudinal HIV/AIDS study with response data, observations may be missing because of patient dropouts due to drug intolerance or other problems, resulting in non-ignorable missing data. In addition to non-ignorable missingness, there are also problems of skewness and left-censoring in the response variable because of a lower limit of detection (LOD). There has been relatively little work published simultaneously dealing with these features of longitudinal data. In particular, one of the features may sometimes be the existence of a larger proportion of left-censored data falling below LOD than expected under a usually assumed log-normal distribution. When this happens, an alternative model which can account for a high proportion of censored data should be considered. We present an extension of the random effects Tobit model that incorporates a mixture of true undetectable observations and those values from a skew-normal distribution for an outcome with left-censoring, skewness and non-ignorable missingness. A unifying modeling approach is used to assess the impact of left-censoring, skewness, non-ignorable missingness and measurement error in covariates on a Bayesian inference. The proposed methods are illustrated using real data from an AIDS clinical study. PMID:24905924
On the skew-symmetric character of the couple-stress tensor
Ali R. Hadjesfandiari
2015-01-20
In this paper, the skew-symmetric character of the couple-stress tensor is established as the result of arguments from tensor analysis. Consequently, the couple-stress pseudo-tensor has a true vectorial character. The fundamental step in this development is that the isotropic couple-stress tensor cannot exist.
Washed Out Bridge, Snake Creek Near Whitesburg
Tributary to Snake Creek, near Whitesburg, Georgia, showing a washed out bridge. When bridges such as this one collapse during a flood, it is rarely the pressure of the rushing water against the bridge that causes the bridge to fail. Rather, the rushing water erodes the ground underneath and surroun...
Mineral bridges in nacre revisited
Antonio G. Checa; Julyan H. E. Cartwright; Marc-Georg Willinger
2012-07-20
We confirm with high-resolution techniques the existence of mineral bridges between superposed nacre tablets. In the towered nacre of both gastropods and the cephalopod Nautilus there are large bridges aligned along the tower axes, corresponding to gaps (150-200 nm) in the interlamellar membranes. Gaps are produced by the interaction of the nascent tablets with a surface membrane that covers the nacre compartment. In the terraced nacre of bivalves bridges associated with elongated gaps in the interlamellar membrane (> 100 nm) have mainly been found at or close to the edges of superposed parental tablets. To explain this placement, we hypothesize that the interlamellar membrane breaks due to differences in osmotic pressure across it when the interlamellar space below becomes reduced at an advanced stage of calcification. In no cases are the minor connections between superimposed tablets (mineral bridges, found to be such.
NSDL National Science Digital Library
Bridges.org is "an international non-profit organisation that promotes the effective use of Information and communications technology (ICT) in the developing world to reduce poverty and improve people's lives." The focus of its work involves ICT-related policy analysis, but organization "also promote best practice in ground-level technology implementation through research and evaluations." It provides information and resources, support grassroots projects and other efforts, and advise decision-makers and the public on key issues. As members of the technology community, the organization brings "an entrepreneurial attitude" and an understanding of technology as well as its commitment to work with governments and the private sector to achieve the goal of "spanning the international digital divide." The website provides an overview of the "digital divide" and describes the organization's approach to addressing these issues. Policy reports, case studies and evaluation guidelines are posted on this website. The organization's current work includes a comparison study of open source and proprietary software, which is also described here.
BRIDGES IN VIBRATED GRANULAR MEDIA
Anita Mehta
We study a particular consequence of the dynamics of vibrated granular media, which is the spontaneous formation of stable\\u000a bridges. Here we examine their geometrical characteristics, and compare the results of a simple theory with those of independent\\u000a simulations of three-dimensional hard spheres. Our conclusion is that bridges are the signatures of spatiotemporal inhomogeneities,\\u000a the carriers of the so-called ‘force
Reynolds, Pamela L.; Bruno, John F.
2012-01-01
Widespread overharvesting of top consumers of the world’s ecosystems has “skewed” food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey species richness, affect ecosystem functioning. We experimentally measured the effects of trophic skew on production in an estuarine food web by manipulating ratios of species richness across three trophic levels in experimental mesocosms. After 24 days, increasing macroalgal richness promoted both plant biomass and grazer abundance, although the positive effect on plant biomass disappeared in the presence of grazers. The strongest trophic cascade on the experimentally stocked macroalgae emerged in communities with a greater ratio of prey to predator richness (bottom-rich food webs), while stronger cascades on the accumulation of naturally colonizing algae (primarily microalgae with some early successional macroalgae that recruited and grew in the mesocosms) generally emerged in communities with greater predator to prey richness (the more top-rich food webs). These results suggest that trophic skewing of species richness and overall changes in food web topology can influence marine community structure and food web dynamics in complex ways, emphasizing the need for multitrophic approaches to understand the consequences of marine extinctions and invasions. PMID:22693549
Development of Inspection Robots for Bridge Cables
Kim, Se-Hoon; Lee, Jong-Jae
2013-01-01
This paper presents the bridge cable inspection robot developed in Korea. Two types of the cable inspection robots were developed for cable-suspension bridges and cable-stayed bridge. The design of the robot system and performance of the NDT techniques associated with the cable inspection robot are discussed. A review on recent advances in emerging robot-based inspection technologies for bridge cables and current bridge cable inspection methods is also presented. PMID:24459453
Xia, Xuhua
GC skew in protein-coding genes between the leading and lagging strands in bacterial genomes: New DNA replication GC skew Genomic evolution a b s t r a c t The DNA strands in most prokaryotic genomes composition, typically measured by GC skew, between the leading and the lagging strand. Casting such strand
49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312...Interlocking Standards § 236.312 Movable bridge, interlocking of signal appliances with...
Weigh-in-motion and smart bridges
NASA Astrophysics Data System (ADS)
Lai, Leon L.
1997-05-01
The bridge Weigh-In-Motion (WIM) system uses bridge structures as weigh scales to measure axle and gross vehicle weights and vehicle configurations without stopping or detouring the vehicles. Because the system is mobile and is almost invisible to the truck drivers, it can be used to collect unbiased traffic data for transportation and loadometer study. The WIM + RESPONSE system, which is an expansion of the original WIM system, was developed to collect additional bridge response data and perform bridge structural evaluation. These additional bridge response data provide bridge engineers with information necessary for improving bridge design and evaluation procedures. Bridge health monitoring and damage detection may also be conducted with long term installation of the WIM + RESPONSE system. This paper discusses what has been achieved by the WIM + RESPONSE system and how the system can be further improved to enhance its functions in a smart bridge.
Huylebrouck, Dirk
2013-01-01
On folio 855 recto of the Codex Atlanticus, Leonardo da Vinci drew three 'easily movable' bridges, but one of them is enigmatic: all 'replicas' in Leonardo museums and exhibitions come as a surprise, to say the least, to any engineer or architect whose attention is drawn to it. This is the case for models in Amboise (France), Chicago and Portland (USA), Florence (Italy) and for the one of the traveling exhibition by the Australian company 'Grande Exhibitions' that already visited 40 major cities in the world. All 'replicas' of the bridge model attributed to Leonardo have pillars standing on the deck of the bridge, while the deck is suspended by cables attached on these pillars. At first sight this problem does not catch the attention of the observer, as the bridge seems to be a mixed form of a beam and a suspension bridge, but it was not overlooked by my colleague architect-engineer Dr. Laurens Luyten (Gent, Belgium). Yet, after a TV-interview in Brussels so much pressure was exerted by some of the museum col...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2011 CFR
2011-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2014 CFR
2014-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...
23 CFR 650.409 - Evaluation of bridge inventory.
Code of Federal Regulations, 2010 CFR
2010-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2013 CFR
2013-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...
23 CFR 650.409 - Evaluation of bridge inventory.
Code of Federal Regulations, 2014 CFR
2014-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2012 CFR
2012-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...
23 CFR 650.409 - Evaluation of bridge inventory.
Code of Federal Regulations, 2011 CFR
2011-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...
23 CFR 650.409 - Evaluation of bridge inventory.
Code of Federal Regulations, 2013 CFR
2013-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...
23 CFR 650.409 - Evaluation of bridge inventory.
Code of Federal Regulations, 2012 CFR
2012-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2010 CFR
2010-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...
Construction Technologies: Create the Strongest Bridge
NSDL National Science Digital Library
K-12 Outreach Office,
Students work in pairs to create three simple types of model bridges (beam, arch, suspension). They observe quantitatively how the bridges work under load and why engineers use different types of bridges for different places. They also get an idea of the parts needed to build bridges, and their functions. The strength of model bridges is mainly a factor of the quality of materials used, and therefore they do not provide a clear visual representation of tension and compression forces involved. Yet, students are able to see these forces at work in three prototype designs and draw conclusions about their dependence on span, width and supporting structures of the bridge designs.
Kalkan, Erol; Kwong, Neal S.
2010-01-01
The earthquake engineering profession is increasingly utilizing nonlinear response history analyses (RHA) to evaluate seismic performance of existing structures and proposed designs of new structures. One of the main ingredients of nonlinear RHA is a set of ground-motion records representing the expected hazard environment for the structure. When recorded motions do not exist (as is the case for the central United States), or when high-intensity records are needed (as is the case for San Francisco and Los Angeles), ground motions from other tectonically similar regions need to be selected and scaled. The modal-pushover-based scaling (MPS) procedure recently was developed to determine scale factors for a small number of records, such that the scaled records provide accurate and efficient estimates of 'true' median structural responses. The adjective 'accurate' refers to the discrepancy between the benchmark responses and those computed from the MPS procedure. The adjective 'efficient' refers to the record-to-record variability of responses. Herein, the accuracy and efficiency of the MPS procedure are evaluated by applying it to four types of existing 'ordinary standard' bridges typical of reinforced-concrete bridge construction in California. These bridges are the single-bent overpass, multi span bridge, curved-bridge, and skew-bridge. As compared to benchmark analyses of unscaled records using a larger catalog of ground motions, it is demonstrated that the MPS procedure provided an accurate estimate of the engineering demand parameters (EDPs) accompanied by significantly reduced record-to-record variability of the responses. Thus, the MPS procedure is a useful tool for scaling ground motions as input to nonlinear RHAs of 'ordinary standard' bridges.
Optimization Of Mean-Semivariance-Skewness Portfolio Selection Model In Fuzzy Random Environment
NASA Astrophysics Data System (ADS)
Chatterjee, Amitava; Bhattacharyya, Rupak; Mukherjee, Supratim; Kar, Samarjit
2010-10-01
The purpose of the paper is to construct a mean-semivariance-skewness portfolio selection model in fuzzy random environment. The objective is to maximize the skewness with predefined maximum risk tolerance and minimum expected return. Here the security returns in the objectives and constraints are assumed to be fuzzy random variables in nature and then the vagueness of the fuzzy random variables in the objectives and constraints are transformed into fuzzy variables which are similar to trapezoidal numbers. The newly formed fuzzy model is then converted into a deterministic optimization model. The feasibility and effectiveness of the proposed method is verified by numerical example extracted from Bombay Stock Exchange (BSE). The exact parameters of fuzzy membership function and probability density function are obtained through fuzzy random simulating the past dates.
Maneuver planning of a rigid spacecraft with two skew control moment gyros
NASA Astrophysics Data System (ADS)
Gui, Haichao; Jin, Lei; Xu, Shijie
2014-11-01
The attitude maneuver planning of a rigid spacecraft using two skew single-gimbal control moment gyros (CMGs) is investigated. First, two types of restrictions are enforced on the gimbal motions of two skew CMGs, with each restriction yielding continuous control torque along a principal axis of the spacecraft. Then, it is proved that any axis fixed to the spacecraft can be pointed along an arbitrary inertial direction by at most two sequent rotations around the two actuated axes. Given this fact, a two-step eigenaxis rotation strategy, executing by the two single-axis torques respectively, is designed to point a given body-fixed axis along a desired direction. Furthermore, a three-step eigenaxis rotation strategy is constructed to achieve an arbitrary rest-to-rest attitude maneuver. The rotation angles required for the single-axis pointing and arbitrary attitude maneuver schemes are all analytically solved. Numerical examples are presented to demonstrate the effectiveness of the proposed algorithms.
Research on the Multi-variable Optimization of Forward-skewed Blade
NASA Astrophysics Data System (ADS)
Yang, Bo; Gu, Chuan Gang
2011-12-01
This is a study of the multi-variable optimization of the forward-skewed blade by means of the Genetic Algorithms combined with an improved Hierarchical Fair Competition model. In this optimization scheme, the Bezier curves were used to describe the airfoil profiles, numerical simulations were adopted to estimate the aerodynamic performance of the axial-flow machine and a specific fitness function was put forwards to evaluate the fitness level of every individual. In order to testify the optimization algorithms and to study the effects of the forward-skewed blades on the fan performance, a series of comparative experiments and calculations were carried out to illustrate the performance difference between the optimized and the other three fans.
Skew ray tracing in a step-index optical fiber using Geometric Algebra
Ang, Angeleene; McNamara, Daniel J
2015-01-01
We used Geometric Algebra to compute the paths of skew rays in a cylindrical, step-index multimode optical fiber. To do this, we used the vector addition form for the law of propagation, the exponential of an imaginary vector form for the law of refraction, and the juxtaposed vector product form for the law of reflection. In particular, the exponential forms of the vector rotations enables us to take advantage of the addition or subtraction of exponential arguments of two rotated vectors in the derivation of the ray tracing invariants in cylindrical and spherical coordinates. We showed that the light rays inside the optical fiber trace a polygonal helical path characterized by three invariants that relate successive reflections inside the fiber: the ray path distance, the difference in axial distances, and the difference in the azimuthal angles. We also rederived the known generalized formula for the numerical aperture for skew rays, which simplifies to the standard form for meridional rays.
Skewed X-chromosome inactivation in women affected by Alzheimer's disease.
Bajic, Vladan; Mandusic, Vesna; Stefanova, Elka; Bozovic, Ana; Davidovic, Radoslav; Zivkovic, Lada; Cabarkapa, Andrea; Spremo-Potparevic, Biljana
2015-01-01
X-chromosome instability has been a long established feature in Alzheimer's disease (AD). Premature centromere division and aneuploidy of the X-chromosome has been found in peripheral blood lymphocytes and neuronal tissue in female AD patients. Interestingly, only one chromosome of the X pair has been affected. These results raised a question, "Is the X-chromosome inactivation pattern altered in peripheral blood lymphocytes of women affected by AD?" To address this question, we analyzed the methylation status of androgen receptor promoter which may show us any deviation from the 50 : 50% X inactivation status in peripheral blood lymphocytes of women with AD. Our results showed skewed inactivation patterns (>90%). These findings suggest that an epigenetic alteration on the inactivation centers of the X-chromosome (or skewing) relates not only to aging, by might be a novel property that could account for the higher incidence of AD in women. PMID:25159673
Skew Projection of Echo-Detected EPR Spectra for Increased Sensitivity and Resolution
Bowman, Michael K.; Krzyaniak, Matthew D.; Cruce, Alex A.; Weber, Ralph T.
2013-01-01
The measurement of EPR spectra during pulsed EPR experiments is commonly accomplished by recording the integral of the electron spin echo as the applied magnetic field is stepped through the spectrum. This approach to echo-detected EPR spectral measurement (ED-EPR) limits sensitivity and spectral resolution and can cause gross distortions in the resulting spectra because some of the information present in the electron spin echo is discarded in such measurements. However, Fourier Transformation of echo shapes measured at a series of magnetic field values followed by skew projection onto either a magnetic field or resonance frequency axis can increase both spectral resolution and sensitivity without the need to trade one against the other. Examples of skew-projected spectra with single crystals, glasses and powders show resolution improvements as large as a factor of seven with sensitivity increases of as much as a factor of five. PMID:23644351
Molecular-cytogenetic investigation of skewed chromosome X inactivation in Rett syndrome.
Yurov, Y B; Vorsanova, S G; Kolotii, A D; Iourov, I Y
2001-12-01
We have developed an approach to differentiate homologous X chromosomes in metaphase chromosomes and interphase nuclei by a fluorescence in situ hybridization (FISH) technique with chromosome X-specific alpha-satellite DNA probe. FISH analysis of metaphase chromosomes in a cohort of 33 girls with Rett syndrome (RTT) allowed us to detect eight girls with structurally different X chromosomes, one X chromosome with a large and another one with a small centromeric heterochromatin (so-called chromosomal heteromorphism). Step-wise application of differential replication staining and the FISH technique to identify the inactivation status of paternal and maternal chromosome X in RTT girls was applied. Skewed X inactivation in seven RTT girls with preferential inactivation of one X chromosome over the other X chromosome was detected in 62-93% of cells. Therefore, non-random or skewed X inactivation with variable penetrance in blood cells could take place in RTT. PMID:11738875
Bridge Decomposition of Restriction Measures
NASA Astrophysics Data System (ADS)
Alberts, Tom; Duminil-Copin, Hugo
2010-08-01
Motivated by Kesten's bridge decomposition for two-dimensional self-avoiding walks in the upper half plane, we show that the conjectured scaling limit of the half-plane SAW, the SLE(8/3) process, also has an appropriately defined bridge decomposition. This continuum decomposition turns out to entirely be a consequence of the restriction property of SLE(8/3), and as a result can be generalized to the wider class of restriction measures. Specifically we show that the restriction hulls with index less than one can be decomposed into a Poisson Point Process of irreducible bridges in a way that is similar to Itô's excursion decomposition of a Brownian motion according to its zeros.
Bridge Decomposition of Restriction Measures
Tom Alberts; Hugo Duminil-Copin
2010-07-03
Motivated by Kesten's bridge decomposition for two-dimensional self-avoiding walks in the upper half plane, we show that the conjectured scaling limit of the half-plane SAW, the SLE(8/3) process, also has an appropriately defined bridge decomposition. This continuum decomposition turns out to entirely be a consequence of the restriction property of SLE(8/3), and as a result can be generalized to the wider class of restriction measures. Specifically we show that the restriction hulls with index less than one can be decomposed into a Poisson Point Process of irreducible bridges in a way that is similar to Ito's excursion decomposition of a Brownian motion according to its zeros.
One-sided confidence intervals for population variances of skewed distributions
Vesna Cojbasic; Dragan Loncar
2011-01-01
In this article we study the coverage accuracy of one-sided bootstrap-t confidence intervals for the population variances combined with Hall's and Johnson's transformation. We compare the coverage accuracy of all suggested intervals and intervals based on the Chi-square statistic for variances of positively skewed distributions. In addition, we describe and discuss an application of the presented methods for measuring and
NASA Technical Reports Server (NTRS)
Ebner, R. E.; Howell, W. E.
1979-01-01
Requirements for a redundant strapdown inertial sensor complex applied to V/STOL aircraft as developed by NASA are presented. Flight test data of a redundant, skewed axis strapdown inertial system are given, demonstrating the feasibility of the primary design aspects. This data consisted of parity equation responses through various flight conditions, showing residual noise levels on redundant gyro and accelerometer comparisons as a measure of minimum failure-level detectability, plus failure isolation and navigation performance through several simulated instrument failures.
A model for coupled magnetic-electric circuits in electric machines with skewed slots
F. Piriou; A. Razek
1990-01-01
A model permitting the simulation of skewed-slot saturated machines associated with nonlinear external circuits is proposed. To take the slot effects into account, the magnetic circuit is modeled through the combined two-dimensional calculations along the machine axis. In this simulation the electric circuit equation is directly coupled with the magnetic one. The solution of the resulting nonlinear time-dependent equation is
No evidence of skewed secondary sex ratios in nestlings of the Common Raven ( Corvus corax )
Sascha Rösner; Kirsten Bogatz; Hendrik Trapp; Thomas Grünkorn; Roland Brandl
2009-01-01
Many bird species adjust their offspring sex ratio as a response to environmental conditions or sexual dimorphism in size\\u000a and dispersal. Offspring sex ratios may therefore vary among populations depending on the different demographic and ecological\\u000a trajectories. We sampled Common Raven Corvus corax nestlings close to the fledging stage from three Central European regions to test for skewed secondary sex
Skew of Mononucleotide Frequencies, Relative Abundance of Dinucleotides, and DNA Strand Asymmetry
Chiharu Shioiri; Naoyuki Takahata
2001-01-01
. Based on 152 mitochondrial genomes and 36 bacterial chromosomes that have been completely sequenced, as well as three long\\u000a contigs for human chromosomes 6, 21, and 22, we examined skews of mononucleotide frequencies and the relative abundance of\\u000a dinucleotides in one DNA strand. Each group of these genomes has its own characteristics. Regarding mitochondrial genomes,\\u000a both CpG and GpT
Effect of phase response curve skew on synchronization with and without conduction delays
Canavier, Carmen C.; Wang, Shuoguo; Chandrasekaran, Lakshmi
2013-01-01
A central problem in cortical processing including sensory binding and attentional gating is how neurons can synchronize their responses with zero or near-zero time lag. For a spontaneously firing neuron, an input from another neuron can delay or advance the next spike by different amounts depending upon the timing of the input relative to the previous spike. This information constitutes the phase response curve (PRC). We present a simple graphical method for determining the effect of PRC shape on synchronization tendencies and illustrate it using type 1 PRCs, which consist entirely of advances (delays) in response to excitation (inhibition). We obtained the following generic solutions for type 1 PRCs, which include the pulse-coupled leaky integrate and fire model. For pairs with mutual excitation, exact synchrony can be stable for strong coupling because of the stabilizing effect of the causal limit region of the PRC in which an input triggers a spike immediately upon arrival. However, synchrony is unstable for short delays, because delayed inputs arrive during a refractory period and cannot trigger an immediate spike. Right skew destabilizes antiphase and enables modes with time lags that grow as the conduction delay is increased. Therefore, right skew favors near synchrony at short conduction delays and a gradual transition between synchrony and antiphase for pairs coupled by mutual excitation. For pairs with mutual inhibition, zero time lag synchrony is stable for conduction delays ranging from zero to a substantial fraction of the period for pairs. However, for right skew there is a preferred antiphase mode at short delays. In contrast to mutual excitation, left skew destabilizes antiphase for mutual inhibition so that synchrony dominates at short delays as well. These pairwise synchronization tendencies constrain the synchronization properties of neurons embedded in larger networks. PMID:24376399
Permanent Magnet Skew Quadrupoles for the Low Emittance LER Lattice of PEP-II
Decker, F.-J.; Anderson, S.; Kharakh, D.; Sullivan, M.; /SLAC
2011-07-05
The vertical emittance of the low energy ring (LER) in the PEP-II B-Factory was reduced by using skew quadrupoles consisting of permanent magnet material. The advantages over electric quadrupoles or rotating existing normal quadrupoles are discussed. To assure a high field quality, a Biot-Savart calculation was used to cancel the natural 12-pole component by using different size poles over a few layers. A magnetic measurement confirmed the high quality of the magnets. After installation and adjusting the original electric 12 skew and 16 normal quadrupoles the emittance contribution from the region close to the interaction point, which was the biggest part in the original design, was considerably reduced. To strengthen the vertical behavior of the LER beam, a low emittance lattice was developed. It lowered the original vertical design emittance from 0.54 nm-rad to 0.034 nm-rad. In order to achieve this, additional skew quadrupoles were required to bring the coupling correction out of the arcs and closer to the detector solenoid in the straight (Fig. 1). It is important, together with low vertical dispersion, that the low vertical emittance is not coupled into the horizontal, which is what we get if the coupling correction continues into the arcs. Further details of the lattice work is described in another paper; here we concentrate on the development of the permanent skew (PSK) quadrupole solution. Besides the permanent magnets there are two other possibilities, using electric magnets or rotating normal quadrupoles. Electric magnets would have required much more additional equipment like magnets stands, power supply, and new vacuum chamber sections. Rotating existing quadrupoles was also not feasible since they are mostly mounted together with a bending magnet on the same support girder.
Vertical-Velocity Skewness in the Buoyancy-Driven Boundary Layer
Chin-Hoh Moeng; Richard Rotunno
1990-01-01
A number of puzzling features of the skewness of the vertical velocity field, Sw(z), are found in observations and large-eddy simulations (LES) of the buoyancy-driven planetary boundary layer (PBL). For example, observations of Sw(z) in cases where the air is heated from below indicate that Sw(z) > 0 and remains relatively constant for z 0.3zi, whereas all large-eddy simulations of
Balanced bridge feedback control system
NASA Technical Reports Server (NTRS)
Lurie, Boris J. (inventor)
1990-01-01
In a system having a driver, a motor, and a mechanical plant, a multiloop feedback control apparatus for controlling the movement and/or positioning of a mechanical plant, the control apparatus has a first local bridge feedback loop for feeding back a signal representative of a selected ratio of voltage and current at the output driver, and a second bridge feedback loop for feeding back a signal representative of a selected ratio of force and velocity at the output of the motor. The control apparatus may further include an outer loop for feeding back a signal representing the angular velocity and/or position of the mechanical plant.
Local scour at bridge abutments
Froehlich, David C.
1989-01-01
Comparison of local scour depths at bridge abutments computed using different equations yields a large variation in predicted values. To consolidate the fragmented results of previous investigations and assemble the most comprehensive data set possible, reported laboratory measurements of local scour at the end of an obstruction protruding from the side of an open channel of rectangular cross section were compiled from several sources. Regression analysis of these data was used to develop an equation that predicts maximum relative depth of local scour at bridge abutments for both clear-water and live-bed scour conditions.
Excitation Methods for Bridge Structures
Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.
1999-02-08
This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.
NSDL National Science Digital Library
This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: The picture shows islands connected by bridges. To cross a bridge, you must pay a toll in coins. If you start on the island marked in blue with 100 coi...
The Equilibrium Allele Frequency Distribution for a Population with Reproductive Skew
Der, Ricky; Plotkin, Joshua B.
2014-01-01
We study the population genetics of two neutral alleles under reversible mutation in a model that features a skewed offspring distribution, called the ?-Fleming–Viot process. We describe the shape of the equilibrium allele frequency distribution as a function of the model parameters. We show that the mutation rates can be uniquely identified from this equilibrium distribution, but the form of the offspring distribution cannot itself always be so identified. We introduce an estimator for the mutation rate that is consistent, independent of the form of reproductive skew. We also introduce a two-allele infinite-sites version of the ?-Fleming–Viot process, and we use it to study how reproductive skew influences standing genetic diversity in a population. We derive asymptotic formulas for the expected number of segregating sites as a function of sample size and offspring distribution. We find that the Wright–Fisher model minimizes the equilibrium genetic diversity, for a given mutation rate and variance effective population size, compared to all other ?-processes. PMID:24473932
An Inconvenient Sea Truth: Spread, Steepness, and Skewness of Surface Slopes
NASA Astrophysics Data System (ADS)
Munk, Walter
2009-01-01
Bréon and Henriot (BH) have collected eight million globally distributed satellite images of sunglitter, which yield a few simple, robust rules about the statistics of surface slopes: 1) constant angular spread, 2) linear steepness, and 3) sigmoid (near stepwise) skewness (all with respect to wind speed). Yet the information is sparse because it says nothing about time and space scales. The BH rules are an inconvenient sea truth, too fundamental to be ignored, too incomplete to be understood. With regard to BH rule 1 (BH:1), I suggest that the constant spread is associated with a wake-like geometry of the short gravities. Steepness linearity (BH:2) remains an enigma. Skewness (BH:3) appears to be correlated with a rather sudden onset of breaking for winds above 4 m s-1. I do not think that skewness comes from parasitic capillaries. These are tentative conclusions; I look forward to intensive sea-going experiments over the next few years demolishing the proposed interpretations.
An inconvenient sea truth: spread, steepness, and skewness of surface slopes.
Munk, Walter
2009-01-01
Bréon and Henriot (BH) have collected eight million globally distributed satellite images of sunglitter, which yield a few simple, robust rules about the statistics of surface slopes: 1) constant angular spread, 2) linear steepness, and 3) sigmoid (near stepwise) skewness (all with respect to wind speed). Yet the information is sparse because it says nothing about time and space scales. The BH rules are an inconvenient sea truth, too fundamental to be ignored, too incomplete to be understood. With regard to BH rule 1 (BH:1), I suggest that the constant spread is associated with a wake-like geometry of the short gravities. Steepness linearity (BH:2) remains an enigma. Skewness (BH:3) appears to be correlated with a rather sudden onset of breaking for winds above 4 m s(-1). I do not think that skewness comes from parasitic capillaries. These are tentative conclusions; I look forward to intensive sea-going experiments over the next few years demolishing the proposed interpretations. PMID:21141042
A QTL Study for Regions Contributing to Arabidopsis thaliana Root Skewing on Tilted Surfaces
Vaughn, Laura M.; Masson, Patrick H.
2011-01-01
Plant root systems must grow in a manner that is dictated by endogenous genetic pathways, yet sensitive to environmental input. This allows them to provide the plant with water and nutrients while navigating a heterogeneous soil environment filled with obstacles, toxins, and pests. Gravity and touch, which constitute important cues for roots growing in soil, have been shown to modulate root architecture by altering growth patterns. This is illustrated by Arabidopsis thaliana roots growing on tilted hard agar surfaces. Under these conditions, the roots are exposed to both gravity and touch stimulation. Consequently, they tend to skew their growth away from the vertical and wave along the surface. This complex growth behavior is believed to help roots avoid obstacles in nature. Interestingly, A. thaliana accessions display distinct growth patterns under these conditions, suggesting the possibility of using this variation as a tool to identify the molecular mechanisms that modulate root behavior in response to their mechanical environment. We have used the Cvi/Ler recombinant inbred line population to identify quantitative trait loci that contribute to root skewing on tilted hard agar surfaces. A combination of fine mapping for one of these QTL and microarray analysis of expression differences between Cvi and Ler root tips identifies a region on chromosome 2 as contributing to root skewing on tilted surfaces, potentially by modulating cell wall composition. PMID:22384323
Joint Skewness and Its Application in Unsupervised Band Selection for Small Target Detection
Geng, Xiurui; Sun, Kang; Ji, Luyan; Tang, Hairong; Zhao, Yongchao
2015-01-01
Few band selection methods are specially designed for small target detection. It is well known that the information of small targets is most likely contained in non-Gaussian bands, where small targets are more easily separated from the background. On the other hand, correlation of band set also plays an important role in the small target detection. When the selected bands are highly correlated, it will be unbeneficial for the subsequent detection. However, the existing non-Gaussianity-based band selection methods have not taken the correlation of bands into account, which generally result in high correlation of obtained bands. In this paper, combining the third-order (third-order tensor) and second-order (correlation) statistics of bands, we define a new concept, named joint skewness, for multivariate data. Moreover, we also propose an easy-to-implement approach to estimate this index based on high-order singular value decomposition (HOSVD). Based on the definition of joint skewness, we present an unsupervised band selection for small target detection for hyperspectral data, named joint skewness band selection (JSBS). The evaluation results demonstrate that the bands selected by JSBS are very effective in terms of small target detection. PMID:25873018
Townsend, Andrea K; Clark, Anne B; McGowan, Kevin J; Lovette, Irby J
2009-02-01
Understanding the benefits of cooperative breeding for group members of different social and demographic classes requires knowledge of their reproductive partitioning and genetic relatedness. From 2004-2007, we examined parentage as a function of relatedness and social interactions among members of 21 American crow (Corvus brachyrhynchos) family groups. Paired female breeders monopolized maternity of all offspring in their broods, whereas paired male breeders sired 82.7% of offspring, within-group auxiliary males sired 6.9% of offspring, and extragroup males sired 10.4% of offspring. Although adult females had fewer opportunities for direct reproduction as auxiliaries than males, they appeared to have earlier opportunities for independent breeding. These different opportunities for direct reproduction probably contributed to the male biased adult auxiliary sex ratio. Patterns of reproductive partitioning and conflict among males were most consistent with a synthetic reproductive skew model, in which auxiliaries struggled with breeders for a limited reproductive share, beyond which breeders could evict them. Counter to a frequent assumption of reproductive skew models, female breeders appeared to influence paternity, although their interests might have agreed with the interests of their paired males. Unusual among cooperative breeders, close inbreeding and incest occurred in this population. Incest avoidance between potential breeders did not significantly affect reproductive skew. PMID:20126287
Ng, Benjamin; Cai, Wenju; Walsh, Kevin
2014-01-01
A positive Indian Ocean Dipole (IOD) tends to have stronger cold sea surface temperature anomalies (SSTAs) over the eastern Indian Ocean with greater impacts than warm SSTAs that occur during its negative phase. Two feedbacks have been suggested as the cause of positive IOD skewness, a positive Bjerknes feedback and a negative SST-cloud-radiation (SCR) feedback, but their relative importance is debated. Using inter-model statistics, we show that the most important process for IOD skewness is an asymmetry in the thermocline feedback, whereby SSTAs respond to thermocline depth anomalies more strongly during the positive phase than negative phase. This asymmetric thermocline feedback drives IOD skewness despite positive IODs receiving greater damping from the SCR feedback. In response to global warming, although the thermocline feedback strengthens, its asymmetry between positive and negative IODs weakens. This behaviour change explains the reduction in IOD skewness that many models display under global warming. PMID:25112717
NASA Technical Reports Server (NTRS)
Weick, Fred E; Harris, Thomas A
1934-01-01
This report covers the sixth of a series of investigations in which various lateral control devices are compared with particular reference to their effectiveness at high angles of attack. The present report deals with flap-type ailerons hinged about axes having an angle with respect to the leading and trailing edges of the wing. Tests were made on four different skewed ailerons, including two different angles of skew and two sizes of ailerons. At the high angles of attack, all the skewed ailerons tested were slightly inferior with respect to rolling and yawing moments to straight ailerons having the same span and average chord. Computations indicate that the skewed ailerons are also inferior with respect to hinge moments.
Ng, Benjamin; Cai, Wenju; Walsh, Kevin
2014-01-01
A positive Indian Ocean Dipole (IOD) tends to have stronger cold sea surface temperature anomalies (SSTAs) over the eastern Indian Ocean with greater impacts than warm SSTAs that occur during its negative phase. Two feedbacks have been suggested as the cause of positive IOD skewness, a positive Bjerknes feedback and a negative SST-cloud-radiation (SCR) feedback, but their relative importance is debated. Using inter-model statistics, we show that the most important process for IOD skewness is an asymmetry in the thermocline feedback, whereby SSTAs respond to thermocline depth anomalies more strongly during the positive phase than negative phase. This asymmetric thermocline feedback drives IOD skewness despite positive IODs receiving greater damping from the SCR feedback. In response to global warming, although the thermocline feedback strengthens, its asymmetry between positive and negative IODs weakens. This behaviour change explains the reduction in IOD skewness that many models display under global warming. PMID:25112717
NASA Astrophysics Data System (ADS)
Ng, Benjamin; Cai, Wenju; Walsh, Kevin
2014-08-01
A positive Indian Ocean Dipole (IOD) tends to have stronger cold sea surface temperature anomalies (SSTAs) over the eastern Indian Ocean with greater impacts than warm SSTAs that occur during its negative phase. Two feedbacks have been suggested as the cause of positive IOD skewness, a positive Bjerknes feedback and a negative SST-cloud-radiation (SCR) feedback, but their relative importance is debated. Using inter-model statistics, we show that the most important process for IOD skewness is an asymmetry in the thermocline feedback, whereby SSTAs respond to thermocline depth anomalies more strongly during the positive phase than negative phase. This asymmetric thermocline feedback drives IOD skewness despite positive IODs receiving greater damping from the SCR feedback. In response to global warming, although the thermocline feedback strengthens, its asymmetry between positive and negative IODs weakens. This behaviour change explains the reduction in IOD skewness that many models display under global warming.
Ivanoff, Michael A.; Song, Donald L.
1996-01-01
The town highway 5 crossing of the Black River is a 70-ft-long, two-lane bridge consisting of one 65-foot clear span (Vermont Agency of Transportation, written commun., August 2, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. There is also a retaining wall along the upstream side of the road embankments. The channel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is 15 degrees. A scour hole 3.0 ft deeper than the mean thalweg depth was observed along the right abutment. The scour hole was 27 feet long, 15 feet wide, and was 2.5 feet below the abutment footing at the time of the Level I assessment. This right abutment had numerous cracks and had settled. 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.
M. A. Alhamadi; N. A. Demerdash
1991-01-01
A method for computation of the parameters and performance of permanent-magnet brushless DC motor drives is developed in which the concept of skewing is implemented through the geometries of permanent magnet mounting on the rotor and not through the usual skewing of the armature slots. This technique of permanent-magnet mounting eliminates the 2-D axial symmetry in the resulting magnetic fields.
Kazuharu Arakawa; Haruo Suzuki; Masaru Tomita
2009-01-01
BACKGROUND: Due to their bi-directional replication machinery starting from a single finite origin, bacterial genomes show characteristic nucleotide compositional bias between the two replichores, which can be visualised through GC skew or (C-G)\\/(C+G). Although this polarisation is used for computational prediction of replication origins in many bacterial genomes, the degree of GC skew visibility varies widely among different species, necessitating
T. Skrypnyk
2009-01-01
We construct generalized Gaudin systems in an external magnetic field corresponding to arbitrary so(3)-valued non-skew-symmetric r-matrices with spectral parameters and non-homogeneous external magnetic fields. In the case of r-matrices diagonal in the sl(2) basis we calculate the spectrum and the eigen-values of the corresponding generalized Gaudin hamiltonians using the algebraic Bethe ansatz. We explicitly consider several one-parametric families of non-skew-symmetric
75 FR 41281 - Bridge Safety Standards
Federal Register 2010, 2011, 2012, 2013, 2014
2010-07-15
...bridges. The evaluation of a bridge requires...conduct regular comprehensive inspections of...might begin a comprehensive inspection and evaluation of a large structure...necessary for a comprehensive evaluation and...
Wind effect on long span bridge
Zhang, Xi, M. Eng. Massachusetts Institute of Technology
2012-01-01
This thesis has studied different types of reactions of long span bridge under wind load, such as vortex shedding, flutter and buffeting. Since all of these conditions have the chance to damage bridge structure, we calculate ...
Overweight permit formulas for simply supported bridges
Mattox, Michael Joseph
1992-01-01
operational moments will not cause failure, the loads allowed will do more long term damage to the bridge than inventory values. Therefore, the lifetime of a bridge will be shortened if repeated loadings based on operational values pass over it...
Coil Creep and Skew-Quadrupole Field Components in the Tevatron
Annala, G.; Harding, D.J.; Syphers, M.J.; /Fermilab
2011-07-11
During the start-up of Run II of the Tevatron Collider program, several issues surfaced which were not present, or not seen as detrimental, during Run I. These included the repeated deterioration of the closed orbit requiring orbit smoothing every two weeks or so, the inability to correct the closed orbit to desired positions due to various correctors running at maximum limits, regions of systematically strong vertical dipole corrections, and the identification of very strong coupling between the two transverse degrees-of-freedom. It became apparent that many of the problems being experienced operationally were connected to a deterioration of the main dipole magnet alignment, and remedial actions were undertaken. However, the alignment alone was not enough to explain the corrector strengths required to handle transverse coupling. With one exception, strong coupling had generally not been an issue in the Tevatron during Run I. Based on experience with the Main Ring, the Tevatron was designed with a very strong skew quadrupole circuit to compensate any quadrupole alignment and skew quadrupole field errors that might present themselves. The circuit was composed of 48 correctors placed evenly throughout the arcs, 8 per sector, evenly placed in every other cell. Other smaller circuits were installed but not initially needed or commissioned. These smaller circuits were composed of individual skew quadrupole correctors on either side of the long straight sections. These circuits were tuned by first bringing the horizontal and vertical tunes near each other. The skew quadrupoles were then adjusted to minimize tune split, usually to less than 0.003. Initially, the main skew quad circuit (designated T:SQ) could accomplish this global decoupling with only 4% of its possible current, and the smaller circuits were not required at all. The start-up of Run Ib was complicated by what was later discovered to be a rolled triplet quadrupole magnet in one of the Interaction Regions. This led to a reduction in luminosity of nearly 50%, as well as operational confusion until it was uncovered. By the time Collider Run II began, the current needed on the main SQ circuit had increased to 60% of its maximum value. Some of the smaller circuits were also needed to fully decouple the tunes. With this history, several studies were performed early in Run II to search for strong local coupling sources like the triplet quadrupole, but without success. The strong corrector settings were indicative of a much larger problem than a single rolled magnet, and the locality of the error was hard to deduce from the setting of a global correction system. Several possible reasons for the increase in coupling were investigated.
1. NORTH HAMMA HAMMA BRIDGE LOOKING SOUTH THROUGH PORTALS OF ...
1. NORTH HAMMA HAMMA BRIDGE LOOKING SOUTH THROUGH PORTALS OF BOTH THE NORTH AND SOUTH BRIDGES - North Hamma Hamma River Bridge, Spanning Hamma Hamma River Bridge at U.S. Route 101, Eldon, Mason County, WA
33 CFR 118.90 - Bridges crossing channel obliquely.
Code of Federal Regulations, 2010 CFR
2010-07-01
...Waters 1 2010-07-01 2010-07-01 false Bridges crossing channel obliquely. 118.90 Section 118...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.90 Bridges...
49 CFR 237.103 - Bridge inspection procedures.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 4 2010-10-01 2010-10-01 false Bridge inspection procedures. 237.103 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.103 Bridge inspection...
49 CFR 237.107 - Conduct of bridge inspections.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Conduct of bridge inspections. 237.107 Section 237.107 ...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.107 Conduct of bridge...
49 CFR 237.71 - Determination of bridge load capacities.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Determination of bridge load capacities. 237.71 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Capacity of Bridges § 237.71 Determination of bridge load...
49 CFR 237.109 - Bridge inspection records.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 4 2010-10-01 2010-10-01 false Bridge inspection records. 237.109 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.109 Bridge inspection...
49 CFR 237.53 - Railroad bridge inspectors.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Railroad bridge inspectors. 237.53 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Qualifications and...Responsible Persons § 237.53 Railroad bridge inspectors. A railroad bridge...
49 CFR 237.111 - Review of bridge inspection reports.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Review of bridge inspection reports. 237.111 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.111 Review of bridge...
23 CFR 650.809 - Movable span bridges.
Code of Federal Regulations, 2011 CFR
2011-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...
23 CFR 650.809 - Movable span bridges.
Code of Federal Regulations, 2013 CFR
2013-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...
23 CFR 650.809 - Movable span bridges.
Code of Federal Regulations, 2010 CFR
2010-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...
23 CFR 650.809 - Movable span bridges.
Code of Federal Regulations, 2014 CFR
2014-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...
23 CFR 650.809 - Movable span bridges.
Code of Federal Regulations, 2012 CFR
2012-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...
28. Under ninth bridge, view to concrete dam and eighth ...
28. Under ninth bridge, view to concrete dam and eighth bridge in background during heavy rain, view to the SW. - Vicksburg National Military Park Roads & Bridges, Melan Arch Bridges, Spanning various tributaries at Confederate Avenue, Vicksburg, Warren County, MS
Bridge Programs in Illinois: Results of the 2010 Illinois Bridge Status Survey
ERIC Educational Resources Information Center
Taylor, J. L.; Harmon, T.
2010-01-01
This report provides a summary of major results of the Illinois Bridge Status Survey, administered online between April and June 2010. The purpose of the survey was to understand the extent to which bridge programs are being implemented in Illinois, as well as to build an online directory of bridge programs. Bridge programs are an emerging…
47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Watch required by the Bridge-to-Bridge Act. 80.309 Section 80.309 Telecommunication...Safety Watches § 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch...
47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 false Operator requirements of the Bridge-to-Bridge Act. 80.163 Section 80.163 Telecommunication...Requirements § 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the...
FEM analysis of vehicle-bridge vibration considering bridge deck's vibration
Yong Ding; Shuqing Kong; Jianyuan Huang; Xu Xie
2010-01-01
This paper is to analyze the vehicle-bridge interaction system based on finite element method (FEM). The vehicle is studied as FEM model as well as the bridge: the bridge structure modeled by shell element considering the bridge deck's vibration, and the vehicle is also modeled by FEM. The coupling effect is implemented by displacement coordination condition and Newmark-? method is
NONLINEAR AERODYNAMIC ANALYSIS OF BRIDGES UNDER TURBULENT WINDS: THE NEW FRONTIER IN BRIDGE
Kareem, Ahsan
, Wind load, Bridge, Random vibration. INTRODUCTION The estimation of wind induced buffeting responseNONLINEAR AERODYNAMIC ANALYSIS OF BRIDGES UNDER TURBULENT WINDS: THE NEW FRONTIER IN BRIDGE. In this study, a time domain analysis framework for predicting the flutter and buffeting responses of bridges
Bridge building and bridge conservation in agreement with the genius loci
Dirk Bühler
Bridges ideally stand for the convergence of engineering landmarks and aesthetical attractions. But what's even more: bridges can be signs that reveal their meaning only by means of a skilful integration to their surrounding landscape or urban context. The appreciation of the spirit of place where bridge building happens is a substantial part for successful bridge design. The paper includes
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…
Timber bridge ruins, not passable.
, sandstone, mudstone, and shale of the Lambert Shale, and San Lorenzo and Purisma Formations. Tertiary Basalt. Fractured, weathered lava flows and shallow intrusives of the Mindego Basalt. Veins of calcite and quartz over basalt. Qf Qs Qt Qc Tb Ts House. Rip rap revetment. Concrete wall. Geogrid. Bridge or crossing
NSDL National Science Digital Library
2012-08-30
In this activity, students graph a quadratic function that models the shape of a bridge trestle and then solve the related quadratic equation by completing the square. Students use the calculators’ capabilities to find the x-intercepts and the maximum value on the graph. Teacher notes, detailed instructions on using graphing calculators, and questions to check comprehension aid in teaching the lesson.
BRIDGING ACADEMIA, PRACTICE, LAW AND
Martin, Ralph R.
INSIDE BRIDGING ACADEMIA, PRACTICE, LAW AND POLICY - MISSION CRITICAL FOR THE IISTL Page 2 team of experts from academia, industry and legal practice and provided a platform for its members figure both in legal practice and academia. On individual level, the members of the IISTL remain
ERIC Educational Resources Information Center
Sementelli, Catherine
2001-01-01
At the Bridge School (Hillsborough, California), children with severe speech and physical disabilities are trained in the use of augmentative and alternative communication technologies, transitioned back to their home school districts, and given continuing support. Outreach and research endeavors keep the broader community informed and educated…
Building Cultural Bridges. Research Brief
ERIC Educational Resources Information Center
Burton, Ella
2007-01-01
The book "Building Cultural Bridges" is designed to increase multi-cultural awareness and sensitivity. There are supplemental materials available that include a leader's guide, reproducible student workbook, readings, worksheets, and activities. This material is recommended for use with students in grades 7-12. The materials included with this…
Percentage Problems in Bridging Courses
ERIC Educational Resources Information Center
Kachapova, Farida; Kachapov, Ilias
2012-01-01
Research on teaching high school mathematics shows that the topic of percentages often causes learning difficulties. This article describes a method of teaching percentages that the authors used in university bridging courses. In this method, the information from a word problem about percentages is presented in a two-way table. Such a table gives…
Bridging steady states with renormalization group analysis
Li, Charles
Outline Bridging steady states with renormalization group analysis Yueheng Lan Department of Physics Tsinghua University April, 2013 Yueheng Lan Bridging steady states with RG analysis #12;Outline Yueheng Lan Bridging steady states with RG analysis #12;Outline Main contents 1 Introduction Physics
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 not reach…
Stability of connected cylindrical liquid bridges.
Patel, Neha M; Dodge, Mohammad Reza; Alexander, J Iwan D; Slobozhanin, Lev A; Taylor, P L; Rosenblatt, Charles
2002-02-01
Two cylindrical liquid bridges, with a conduit to facilitate flow of liquid from one bridge to the other, were levitated against gravity in a magnetic field gradient. The stability limit of the bridges subjected to near zero total body force was measured as a function of their slenderness ratios, and found to be in good agreement with theoretical predictions. PMID:11863652
The breaking of axisymmetric slender liquid bridges
J. Meseguer
1983-01-01
Liquids held by surface tension forces can bridge the gap between two solid bodies placed not too far apart from each other. The equilibrium conditions and stability criteria for static, cylindrical liquid bridges are well known. However, the behaviour of an unstable liquid bridge, regarding both its transition toward breaking and the resulting configuration, is a matter for discussion. The
Building Bridges One Line at a Time
ERIC Educational Resources Information Center
Grigsby, Cathy Murray
2012-01-01
In this article, first-grade students were taught the different kinds of lines that were part of the construction of various bridges--the curved lines of the arches of stone bridges, straight lines connecting the cables of a suspension bridge, vertical lines, horizontal lines, and so on. They gained practice in drawing structures and in fine brush…
TAYLOR BRIDGE -FIELD ASSESSMENT Doug STEWARTi
system used to reduce the data collected from the bridge into engineering information which can be used as reinforcement and prestessing tendons, the bridge is I Wardrop Engineering Inc., Winnipeg, Manitoba, Canada R3CTAYLOR BRIDGE - FIELD ASSESSMENT Doug STEWARTi , Emile SHEHATAi , Gamil TADROS2 and Sami RIZKALLA2
Removal of failed crown and bridge
Rahul, G R.; Poduval, Soorya T.; Shetty, Karunakar
2012-01-01
Crown and bridge have life span of many years but they fail for a number of reasons. Over the years, many devices have been designed to remove crowns and bridges from abutment teeth. While the removal of temporary crowns and bridges is usually very straightforward, the removal of a definitive cast crown with unknown cement is more challenging. Removal is often by destructive means. There are a number of circumstances, however, in which conservative disassembly would aid the practitioner in completing restorative/endodontic procedures. There are different mechanisms available to remove a failed crown or bridge. But there is no information published about the classification of available systems for crown and bridge removal. So it is logical to classify these systems into different groups which can help a clinician in choosing a particular type of system depending upon the clinical situation. The aim of this article is to provide a classification for various crown and bridge removal systems; describe how a number of systems work; and when and why they might be used. A PubMed search of English literature was conducted up to January 2010 using the terms: Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. Additionally, the bibliographies of 3 previous reviews, their cross references as well as articles published in various journals like International Endodontic Journal, Journal of Endodontics and were manually searched. Key words:Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. PMID:24558549
Canonical forms for cycles in bridge graphs
S. Gill Williamson
1993-01-01
Let G = (V,E) be a biconnected graph and let C be a cycle in G. The subgraphs of G identified with the biconnected components of the contraction of C in G are called the bridges of C. Associated with the set of bridges of a cycle C is an auxilliary graphical structure GC called a bridge graph or an
Removal of failed crown and bridge.
Sharma, Ashu; Rahul, G R; Poduval, Soorya T; Shetty, Karunakar
2012-07-01
Crown and bridge have life span of many years but they fail for a number of reasons. Over the years, many devices have been designed to remove crowns and bridges from abutment teeth. While the removal of temporary crowns and bridges is usually very straightforward, the removal of a definitive cast crown with unknown cement is more challenging. Removal is often by destructive means. There are a number of circumstances, however, in which conservative disassembly would aid the practitioner in completing restorative/endodontic procedures. There are different mechanisms available to remove a failed crown or bridge. But there is no information published about the classification of available systems for crown and bridge removal. So it is logical to classify these systems into different groups which can help a clinician in choosing a particular type of system depending upon the clinical situation. The aim of this article is to provide a classification for various crown and bridge removal systems; describe how a number of systems work; and when and why they might be used. A PubMed search of English literature was conducted up to January 2010 using the terms: Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. Additionally, the bibliographies of 3 previous reviews, their cross references as well as articles published in various journals like International Endodontic Journal, Journal of Endodontics and were manually searched. Key words:Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. PMID:24558549
Chaos theory analysis of cable-stayed bridge vibration
Richard A. Livingston; Shuang Jin
2006-01-01
Cable-stayed bridges are a recent development in bridge structural design in which the cables meet the bridge deck at an acute angle rather than perpendicularly. Some early cable-stayed bridges have exhibited large amplitude stay cable oscillations. One such bridge, the Fred Hartman Bridge across the Houston Ship Channel in Texas displayed two different modes of vibration: a local mode involving
Li Yan; Bi Hong-tao
2010-01-01
The vibration problem induced by vehicle moving over cable-stayed bridge has been widely investigated, but most of previous work focused on dynamic response and security of bridge. In the view of comfort properties, the effects of bridge vibration on vehicle driving comfort are discussed in present paper. Taking the Nanjing 2nd bridge in China for example, applying self-compiling vehicle-bridge coupling
Right Coronary Artery Distribution of Myocardial Bridging
Nguyen, Trung H.; Burnside, Patrick R.; Dieter, Robert S.; Nanjundappa, Aravinda
2007-01-01
Myocardial bridging has been observed to provoke symptoms in association with strenuous physical activity and hypertrophic cardiomyopathy; more recently, bridging has been thought to cause coronary vasospasm. Autopsy findings tend to reveal higher incidences of bridging than do angiography series, but both show an almost uniform predilection for left coronary artery distribution—especially in regard to bridging that manifests itself clinically. Herein, we report an unusual case of myocardial bridging with right coronary artery distribution and important clinical implications for physicians' management of similar cases in the future. PMID:18172538
Strengthening Bridges with Prestressed CFRP Strips
NASA Astrophysics Data System (ADS)
Siwowski, Tomasz; ?ó?towski, Piotr
2012-06-01
Limitation of bridge's carrying bearing capacity due to aging and deterioration is a common problem faced by road administration and drivers. Rehabilitation of bridges including strengthening may be applied in order to maintain or upgrade existing bridge parameters. The case studies of strengthening of two small bridges with high modulus prestressed CFRP strips have been presented in the paper. The first one - reinforced concrete slab bridge - and the other - composite steel-concrete girder bridge - have been successfully upgraded with quite new technology. In both cases the additional CFRP reinforcement let increasing of bridge carrying capacity from 15 till 40 metric tons. The CFRP strip prestressing system named Neoxe Prestressing System (NPS), developed by multi-disciplinary team and tested at full scale in Rzeszow University of Technology, has been also described in the paper.
Social queuing in animal societies: a dynamic model of reproductive skew
Kokko, H.; Johnstone, R. A.
1999-01-01
Previously developed models of reproductive skew have overlooked one of the main reasons why subordinates might remain in a group despite restricted opportunities to breed: the possibility of social queuing, i.e. acquiring dominant status in the future. Here, we present a dynamic ESS model of skew in animal societies that incorporates both immediate and future fitness consequences of the decisions taken by group members, based on their probability of surviving from one season to the next (when post-breeding survival probabilities drop to zero, our analysis reduces to the model produced by Reeve and Ratnieks in 1993, which considered only a single breeding season). This allows us to compare the delayed benefits of philopatry and the immediate opportunities for independent breeding. We show that delayed benefits greatly reduce the need for dominants to offer reproductive concessions to retain subordinates peacefully in the group. Moreover, this effect is strong enough that differences in survival have a much greater impact on the group structure than differences in other parameters, such as relatedness. When the possibility of acceding to dominant status is taken into account, groups where the dominant completely monopolizes reproduction can be stable, even if they consist of unrelated individuals, and even if subordinates have a reasonably high probability of winning a fight for dominance. Finally, we show that stable groups are possible even if association leads to a decrease in current productivity. Subordinates may still stand to gain from group membership under these circumstances, as acquiring breeding positions by queuing may be more efficient than the attempt to establish a new territory. At the same time, the dominant may be unable to exclude unwelcome subordinates, may enjoy increased survival when they are present, or may gain indirect benefits from allowing relatives to stay and queue for dominance. We conclude that reproductive skew in animal groups, ranging from eusocial insect colonies to mating aggregations (leks), will be strongly influenced by the future prospects of group members.
Heat transfer in rotating serpentine passages with trips skewed to the flow
NASA Technical Reports Server (NTRS)
Johnson, B. V.; Wagner, J. H.; Steuber, G. D.; Yeh, F. C.
1992-01-01
Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large scale, multi-pass, heat transfer model with both radially inward and outward flow. Trip strips, skewed at 45 deg to the flow direction, were machined on the leading and trailing surfaces of the radial coolant passages. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature, rotation number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges which are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from similar stationary and rotating models with smooth walls and with trip strips normal to the flow direction. The heat transfer coefficients on surfaces, where the heat transfer decreased with rotation and buoyancy, decreased to as low as 40 percent of the value without rotation. However, the maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels previously obtained with the smooth wall models. It was concluded that (1) both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips, (2) the effects of rotation are markedly different depending upon the flow direction, and (3) the heat transfer with skewed trip strips is less sensitive to buoyancy than the heat transfer in models with either smooth or normal trips. Therefore, skewed trip strips rather than normal trip strips are recommended and geometry-specific tests are required for accurate design information.
Sustainability in bridge construction processes
Pedro Pacheco; António P. Adão da Fonseca; André Resende; Rui Campos
2010-01-01
Sustainability must be seen as a global issue. In order to achieve that goal, it is necessary to apply its principles to all\\u000a industrial activities, including those that are not traditionally engaged with such guidelines, which is the case of Bridge\\u000a Construction. This paper evaluates the consumption of steel and energy and the emissions of carbon dioxide due to the
Structure-induced negatively skewed X-ray diffraction pattern of carbon onions
NASA Astrophysics Data System (ADS)
Siklitskaya, Alexandra; Yastrebov, Sergey; Smith, Roger
2013-10-01
The idea is discussed that a gradual change of intershell separation in carbon onions may introduce a negative skewness into the most intense X-ray diffraction band. As an example, the experimental X-ray diffraction pattern of carbon onions is analysed using a weighted Lorentzian X-ray profile broadening model for each intershell separation contributing to the profile. The dependence of the mean radius for carbon onion shells on the intershell spacing between the adjacent shells is derived from the model analysis. Comparison with the internal distribution of atomic density in carbon onions measured with high resolution transmission electron microscopy is discussed.
Skewness in (1 +1 ) -dimensional Kardar-Parisi-Zhang-type growth
NASA Astrophysics Data System (ADS)
Singha, Tapas; Nandy, Malay K.
2014-12-01
We use the (1 +1 ) -dimensional Kardar-Parisi-Zhang equation driven by a Gaussian white noise and employ the dynamic renormalization-group of Yakhot and Orszag without rescaling [J. Sci. Comput. 1, 3 (1986), 10.1007/BF01061452]. Hence we calculate the second- and third-order moments of height distribution using the diagrammatic method in the large-scale and long-time limits. The moments so calculated lead to the value S =0.3237 for the skewness. This value is comparable with numerical and experimental estimates.
Evolution kernels of skewed parton distributions: method and two-loop results
A. V. Belitsky; A. Freund; D. Müller
1999-12-16
We present a formalism and explicit results for two-loop flavor singlet evolution kernels of skewed parton distributions in the minimal subtraction scheme. This approach avoids explicit multiloop calculations in QCD and is based on the known pattern of conformal symmetry breaking in this scheme as well as constraints arising from the graded algebra of the $\\cN = 1$ super Yang-Mills theory. The conformal symmetry breaking part of the kernels is deduced from commutator relations between scale and special conformal anomalies while the symmetric piece is recovered from the next-to-leading order splitting functions and $\\cN = 1$ supersymmetry relations.
Local obstructions to projective surfaces admitting skew-symmetric Ricci tensor
NASA Astrophysics Data System (ADS)
Randall, Matthew
2014-02-01
The equation determining whether a projective structure admits a connection in its given projective class that has skew-symmetric Ricci tensor is an overdetermined system of semi-linear partial differential equations which we call the projective Einstein-Weyl (pEW) equation. In 2-dimensions, we give local obstructions for projective surfaces to admit such a connection in its projective class. The obstructions are the resultants of polynomial equations that have to be satisfied for there to admit any pEW solution.
Lumia, Richard; Baevsky, Yvonne Halpern
2000-01-01
Flood-frequency relations that are developed by fitting the logarithms of annual peak discharges to a Pearson Type-III distribution are sensitive to skew coefficients. Estimates of population skew for a site are improved when computed from the weighted average of (1) the sample (station) skew, and (2) an unbiased, generalized skew estimate. A weighting technique based on the number of years of record at each of 226 sites was used to develop a contour map of unbiased, generalized skew coefficients for New York. An attempt was made to group (regionalize) the station skew coefficients into five hydrologically similar areas of New York, but the statewide version proved to be as accurate as the regionalized version and therefore was adopted as the final generalized skew-coefficient map for New York. An error analysis showed the statewide contour map to have lower MSE?s (mean square errors) than those computed from (1) the five regional skewcoefficient contour maps, (2) a previously used (1982) nationwide skew coefficient map, and (3) the weighted mean of skew coefficients for sites within each of five hydrologically uniform, but distinct areas of New York.
NASA Astrophysics Data System (ADS)
Singh, S. K.; Chakrabarti, A.
2013-08-01
Static, vibration and buckling behavior of laminated composite and sandwich skew plates is studied using an efficient C0 FE model developed based on refined higher order zigzag theory. The C0 FE model satisfies the interlaminar shear stress continuity at the interfaces and zero transverse shear stress conditions at plate top and bottom. In this model, the first derivatives of transverse displacement have been treated as independent variables to overcome the problem of C1 continuity associated with the plate theory. The C0 continuity of the present element is compensated in the stiffness matrix formulation by adding a suitable term. In order to avoid stress oscillations observed in the displacement based finite element, the stress field derived from temperature is made consistent with the total strain field by using field consistent approach. Numerical results are presented for different static, vibration and buckling problems by applying the FE model under thermo mechanical loading, where a nine noded C0 continuous isoparametric element is used. It is observed that there are very few results available in the literature on laminated composite and sandwich skew plates based on refined theories. As such many new results are also generated for future reference
NASA Astrophysics Data System (ADS)
Sardeshmukh, Prashant D.; Penland, Cécile
2015-03-01
The probability distributions of large-scale atmospheric and oceanic variables are generally skewed and heavy-tailed. We argue that their distinctive departures from Gaussianity arise fundamentally from the fact that in a quadratically nonlinear system with a quadratic invariant, the coupling coefficients between system components are not constant but depend linearly on the system state in a distinctive way. In particular, the skewness arises from a tendency of the system trajectory to linger near states of weak coupling. We show that the salient features of the observed non-Gaussianity can be captured in the simplest such nonlinear 2-component system. If the system is stochastically forced and linearly damped, with one component damped much more strongly than the other, then the strongly damped fast component becomes effectively decoupled from the weakly damped slow component, and its impact on the slow component can be approximated as a stochastic noise forcing plus an augmented nonlinear damping. In the limit of large time-scale separation, the nonlinear augmentation of the damping becomes small, and the noise forcing can be approximated as an additive noise plus a correlated additive and multiplicative noise (CAM noise) forcing. Much of the diversity of observed large-scale atmospheric and oceanic probability distributions can be interpreted in this minimal framework.
Fuel cell plates with skewed process channels for uniform distribution of stack compression load
Granata, Jr., Samuel J. (Greensburg, PA); Woodle, Boyd M. (North Huntingdon Township, Westmoreland County, PA)
1989-01-01
An electrochemical fuel cell includes an anode electrode, a cathode electrode, an electrolyte matrix sandwiched between electrodes, and a pair of plates above and below the electrodes. The plate above the electrodes has a lower surface with a first group of process gas flow channels formed thereon and the plate below the electrodes has an upper surface with a second group of process gas flow channels formed thereon. The channels of each group extend generally parallel to one another. The improvement comprises the process gas flow channels on the lower surface of the plate above the anode electrode and the process gas flow channels on the upper surface of the plate below the cathode electrode being skewed in opposite directions such that contact areas of the surfaces of the plates through the electrodes are formed in crisscross arrangements. Also, the plates have at least one groove in areas of the surfaces thereof where the channels are absent for holding process gas and increasing electrochemical activity of the fuel cell. The groove in each plate surface intersects with the process channels therein. Also, the opposite surfaces of a bipolar plate for a fuel cell contain first and second arrangements of process gas flow channels in the respective surfaces which are skewed the same amount in opposite directions relative to the longitudinal centerline of the plate.
Pronounced reproductive skew in a natural population of green swordtails, Xiphophorus helleri.
Tatarenkov, Andrey; Healey, Christiane I M; Grether, Gregory F; Avise, John C
2008-10-01
For many species in nature, a sire's progeny may be distributed among a few or many dams. This poses logistical challenges--typically much greater across males than across females--for assessing means and variances in mating success (number of mates) and reproductive success (number of progeny). Here we overcome these difficulties by exhaustively analyzing a population of green swordtail fish (Xiphophorus helleri) for genetic paternity (and maternity) using a suite of highly polymorphic microsatellite loci. Genetic analyses of 1476 progeny from 69 pregnant females and 158 candidate sires revealed pronounced skews in male reproductive success both within and among broods. These skews were statistically significant, greater than in females, and correlated in males but not in females with mating success. We also compare the standardized variances in swordtail reproductive success to the few such available estimates for other taxa, notably several mammal species with varied mating systems and degrees of sexual dimorphism. The comparison showed that the opportunity for selection on male X. helleri is among the highest yet reported in fishes, and it is intermediate compared to estimates available for mammals. This study is one of a few exhaustive genetic assessments of joint-sex parentage in a natural fish population, and results are relevant to the operation of sexual selection in this sexually dimorphic, high-fecundity species. PMID:18986497
Heat transfer in rotating serpentine passages with trips skewed to the flow
NASA Technical Reports Server (NTRS)
Johnson, B. V.; Wagner, J. H.; Steuber, G. D.; Yeh, F. C.
1992-01-01
Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large scale, multi-pass heat transfer model with both radially inward and outward flow. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature, rotation number, Reynolds number, and radius-to-passage hydraulic diameter ratio. Results were correlated and compared to previous results from similar stationary and rotating models with smooth walls and with trip strips normal to the flow direction. It was concluded that (1) both Coriolis and buoyancy must be considered in turbine blade cooling designs with trip strips, (2) the effects of rotation are markedly different depending upon the flow direction, and (3) the heat transfer with skewed trip strips is less sensitive to buoyancy than the heat transfer models with either smooth or normal trips. Therefore, skewed trip strips rather than normal trip strips are recommended and geometry-specific tests are required for accurate design.
Skew-symmetric convection form and secondary conservative finite difference methods for moving grids
NASA Astrophysics Data System (ADS)
Morinishi, Yohei; Koga, Kazuki
2014-01-01
The secondary conservative finite difference method for the convective term is recognized as a useful tool for unsteady flow simulations. However, the secondary conservative convection scheme and associated skew-symmetric form have not been extended to those for moving grids. In this study, the skew-symmetric form and the secondary conservative convection schemes for ALE type moving grid simulations are proposed. For the moving grid simulations, the geometric conservation law (GCL) for metrics and the Jacobian is known as a mathematical constraint for capturing a uniform flow. A new role of the GCL is revealed in association with the commutability and conservation properties of the convection schemes. The secondary conservative convection schemes for moving grids are then constructed for compressible and incompressible flows, respectively. For compressible flows, it is necessary to introduce a shock capturing method to resolve discontinuities. However, the shock capturing methods do not work well for turbulent flow simulations because of their excessive numerical dissipation. On the other hand, the secondary conservative finite difference method does not work well for flows with discontinuities. In this study, we also present a computational technique that combines the shock capturing and the secondary conservative finite difference methods. In order to check the commutability and conservation properties of the convection schemes, numerical tests are done for compressible and incompressible inviscid periodic flows on moving grids. Then, the reliabilities of the schemes are demonstrated on the piston problem, the flow around pitching airfoil, and the flow around an oscillating square cylinder.
Fourier transform assisted deconvolution of skewed peaks in complex multi-dimensional chromatograms.
Hanke, Alexander T; Verhaert, Peter D E M; van der Wielen, Luuk A M; Eppink, Michel H M; van de Sandt, Emile J A X; Ottens, Marcel
2015-05-15
Lower order peak moments of individual peaks in heavily fused peak clusters can be determined by fitting peak models to the experimental data. The success of such an approach depends on two main aspects: the generation of meaningful initial estimates on the number and position of the peaks, and the choice of a suitable peak model. For the detection of meaningful peaks in multi-dimensional chromatograms, a fast data scanning algorithm was combined with prior resolution enhancement through the reduction of column and system broadening effects with the help of two-dimensional fast Fourier transforms. To capture the shape of skewed peaks in multi-dimensional chromatograms a formalism for the accurate calculation of exponentially modified Gaussian peaks, one of the most popular models for skewed peaks, was extended for direct fitting of two-dimensional data. The method is demonstrated to successfully identify and deconvolute peaks hidden in strongly fused peak clusters. Incorporation of automatic analysis and reporting of the statistics of the fitted peak parameters and calculated properties allows to easily identify in which regions of the chromatograms additional resolution is required for robust quantification. PMID:25841612
Semiparametric regression models for a right-skewed outcome subject to pooling.
Mitchell, Emily M; Lyles, Robert H; Manatunga, Amita K; Schisterman, Enrique F
2015-04-01
Pooling specimens prior to performing laboratory assays has various benefits. Pooling can help to reduce cost, preserve irreplaceable specimens, meet minimal volume requirements for certain lab tests, and even reduce information loss when a limit of detection is present. Regardless of the motivation for pooling, appropriate analytical techniques must be applied in order to obtain valid inference from composite specimens. When biomarkers are treated as the outcome in a regression model, techniques applicable to individually measured specimens may not be valid when measurements are taken from pooled specimens, particularly when the biomarker is positive and right skewed. In this paper, we propose a novel semiparametric estimation method based on an adaptation of the quasi-likelihood approach that can be applied to a right-skewed outcome subject to pooling. We use simulation studies to compare this method with an existing estimation technique that provides valid estimates only when pools are formed from specimens with identical predictor values. Simulation results and analysis of a motivating example demonstrate that, when appropriate estimation techniques are applied to strategically formed pools, valid and efficient estimation of the regression coefficients can be achieved. PMID:25737248
Weighted skewness and kurtosis unbiased by sample size and Gaussian uncertainties
NASA Astrophysics Data System (ADS)
Rimoldini, Lorenzo
2014-07-01
Central moments and cumulants are often employed to characterize the distribution of data. The skewness and kurtosis are particularly useful for the detection of outliers, the assessment of departures from normally distributed data, automated classification techniques and other applications. Estimators of higher order moments that are robust against outliers are more stable but might miss characteristic features of the data, as in the case of astronomical time series exhibiting brief events like stellar bursts or eclipses of binary systems, while weighting can help identify reliable measurements from uncertain or spurious outliers. Furthermore, noise is an unavoidable part of most measurements and their uncertainties need to be taken properly into account during the data analysis or biases are likely to emerge in the results, including basic descriptive statistics. This work provides unbiased estimates of the weighted skewness and kurtosis moments and cumulants, corrected for biases due to sample size and Gaussian noise, under the assumption of independent data. A comparison of biased and unbiased weighted estimators is illustrated with simulations as a function of sample size and signal-to-noise ratio, employing different data distributions and weighting schemes related to measurement uncertainties and the sampling of the signal. Detailed derivations and figures of simulation results are presented in the Appendices available online.
Differential properties and attracting sets of a simplest skew product of interval maps
Efremova, Lyudmila S [N. I. Lobachevski State University of Nizhni Novgorod, Nizhnii Novgorod (Russian Federation)
2010-08-12
For a skew product of interval maps with a closed set of periodic points, the dependence of the structure of its {omega}-limit sets on its differential properties is investigated. An example of a map in this class is constructed which has the maximal differentiability properties (within a certain subclass) with respect to the variable x, is C{sup 1}-smooth in the y-variable and has one-dimensional {omega}-limit sets. Theorems are proved that give necessary conditions for one-dimensional {omega}-limit sets to exist. One of them is formulated in terms of the divergence of the series consisting of the values of a function of x; this function is the C{sup 0}-norm of the deviation of the restrictions of the fibre maps to some nondegenerate closed interval from the identity on the same interval. Another theorem is formulated in terms of the properties of the partial derivative with respect to x of the fibre maps. A complete description is given of the {omega}-limit sets of certain class of C{sup 1}-smooth skew products satisfying some natural conditions. Bibliography: 33 titles.
Dynamics and Statics of Nonaxisymmetric Liquid Bridges
NASA Technical Reports Server (NTRS)
Alexander, J. Iwan D.; Resnick, Andrew H.; Slobozhanin, L. A.
1996-01-01
Theoretical and experimental investigation of the stability of nonaxisymmetric and nonaxisymmetric bridges contained between equal and unequal radii disks as a function of Bond and Weber number with emphasis on the transition from unstable axisymmetric to stable nonaxisymmetric shapes, are conducted. Numerical analysis of the stability of nonaxisymmetric bridges between unequal disks for various orientations of the gravity vector is performed. Experimental and theoretical investigation of large (nonaxisymmetric) oscillations and breaking of liquid bridges are also conducted.
Measurement of Deflection Line on Bridges
NASA Astrophysics Data System (ADS)
Urban, Rudolf; Štroner, Martin
2013-12-01
Prestressed concrete bridges are very sensitive to the increase in long-term deflections. Reliable forecasts of deflections of bridge structures during construction and durability are crucial for achieving good durability. The main results of measurements are the changes of the deflection line of the bridge structures, which places special demands on the measurement procedure. Results from measurements are very useful for the improvement of mathematical prediction methods of behaviour of long span prestressed concrete structures.
Harvesting traffic-induced bridge vibrations
T. Galchev; J. McCullagh; R. L. Peterson; K. Najafi
2011-01-01
This paper demonstrates the harvesting of low-frequency and low-amplitude vibration energy from a suspension bridge. The performance of a Parametric Frequency Increased Generator (PFIG) (1) is evaluated at different locations along the bridge. Bridge vibrations have very low acceleration 0.1-1 m\\/s 2 and variable frequency characteristics (1-40 Hz), making them very challenging to harvest. Field test results show consistent operation
NASA Astrophysics Data System (ADS)
Guo, Fu-sheng; Chen, Xiang-ning; Li, Jiangbo
2007-11-01
Document skew is often introduced into the scanned or printed document, so the document skew detection and correction play an important role in the document image processing. This paper gives a whole review of existent algorithms and describes their respective shortcomings. We propose a novel algorithm combined with run-length smoothing, Hough transform, Mathematical Morphology and Wavelet, as to improve its precision and speed. The algorithm this paper gives is feasible and effective, and it can be run automatically. It can be faster and more accurate than other methods and can be applied in document words identify.
Development of Hybrid Bridges: State of Arts and Conceptual Design
Suhaib Yahya Kasim Al-Darzi; Airong Chen
2006-01-01
A state of the art of developments of the Hybrid bridges is presented focusing on steel-concrete composite bridges, considering the steel beam, concrete deck and connections developments. The analysis and design methods of composite bridge structures, connections, the reliability and life cycle of bridges, new bridge system forms and the use of alternative materials are reviewed with some possible applications.
Piezoelectric energy harvesting from traffic-induced bridge vibrations
Paris-Sud XI, UniversitÃ© de
Piezoelectric energy harvesting from traffic-induced bridge vibrations MichaÂ¨el Peigney1 harvesting of traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case-induced bridge vibrations 2 1. Introduction This paper focuses on using bridge vibrations as an energy source
1 INTRODUCTION Full-scale dynamic testing of operational bridges
Lynch, Jerome P.
to monitor the vibration response of the 180 meter long Yeondae Bridge, Korea. The bridge consists of a steel1 INTRODUCTION Full-scale dynamic testing of operational bridges can be carried out for a multitude of a bridge. Fur- thermore, the overall state or condition of a bridge can be determined using response data
6. VIEW OF GDOT BRIDGE NO. 02700268X00678N BRIDGE PLATE IDENTIFYING ...
6. VIEW OF GDOT BRIDGE NO. 027-00268X-00678N BRIDGE PLATE IDENTIFYING COUNTY COMMISSIONERS AT THE TIME OF CONSTRUCTION. - GDOT Bridge No. 027-00268X-00678N, County Road 268-Empress Road span Piscola Creek, Quitman, Brooks County, GA
I.-Wen Wu; Chung-Yue Wang; Ming-Hung Chen; Hao-Lin Wang; Allen Cheng; Patrick Tsai; David Wu; Hung-Wei ChangChien; Hentai Shang
2007-01-01
The FBG bending gauge developed by POFC is applied in several situations involving bridge safety\\/health monitoring. Under static loading conditions, the FBG bending gauge serves as an excellent tool to deduce an overall deflection curve on the bridge section under study. The gauge also works well in dynamic situations where instantaneous vertical deflections of bridge structures resulting from a cruising
Salt-bridge energetics in halophilic proteins.
Nayek, Arnab; Sen Gupta, Parth Sarthi; Banerjee, Shyamashree; Mondal, Buddhadev; Bandyopadhyay, Amal K
2014-01-01
Halophilic proteins have greater abundance of acidic over basic and very low bulky hydrophobic residues. Classical electrostatic stabilization was suggested as the key determinant for halophilic adaptation of protein. However, contribution of specific electrostatic interactions (i.e. salt-bridges) to overall stability of halophilic proteins is yet to be understood. To understand this, we use Adaptive-Poison-Boltzmann-Solver Methods along with our home-built automation to workout net as well as associated component energy terms such as desolvation energy, bridge energy and background energy for 275 salt-bridges from 20 extremely halophilic proteins. We then perform extensive statistical analysis on general and energetic attributes on these salt-bridges. On average, 8 salt-bridges per 150 residues protein were observed which is almost twice than earlier report. Overall contributions of salt-bridges are -3.0 kcal mol-1. Majority (78%) of salt-bridges in our dataset are stable and conserved in nature. Although, average contributions of component energy terms are equal, their individual details vary greatly from one another indicating their sensitivity to local micro-environment. Notably, 35% of salt-bridges in our database are buried and stable. Greater desolvation penalty of these buried salt-bridges are counteracted by stable network salt-bridges apart from favorable equal contributions of bridge and background terms. Recruitment of extensive network salt-bridges (46%) with a net contribution of -5.0 kcal mol-1 per salt-bridge, seems to be a halophilic design wherein favorable average contribution of background term (-10 kcal mol-1) exceeds than that of bridge term (-7 kcal mol-1). Interiors of proteins from halophiles are seen to possess relatively higher abundance of charge and polar side chains than that of mesophiles which seems to be satisfied by cooperative network salt-bridges. Overall, our theoretical analyses provide insight into halophilic signature in its specific electrostatic interactions which we hope would help in protein engineering and bioinformatics studies. PMID:24743799
Salt-Bridge Energetics in Halophilic Proteins
Nayek, Arnab; Sen Gupta, Parth Sarthi; Banerjee, Shyamashree; Mondal, Buddhadev; Bandyopadhyay, Amal K.
2014-01-01
Halophilic proteins have greater abundance of acidic over basic and very low bulky hydrophobic residues. Classical electrostatic stabilization was suggested as the key determinant for halophilic adaptation of protein. However, contribution of specific electrostatic interactions (i.e. salt-bridges) to overall stability of halophilic proteins is yet to be understood. To understand this, we use Adaptive-Poison-Boltzmann-Solver Methods along with our home-built automation to workout net as well as associated component energy terms such as desolvation energy, bridge energy and background energy for 275 salt-bridges from 20 extremely halophilic proteins. We then perform extensive statistical analysis on general and energetic attributes on these salt-bridges. On average, 8 salt-bridges per 150 residues protein were observed which is almost twice than earlier report. Overall contributions of salt-bridges are ?3.0 kcal mol?1. Majority (78%) of salt-bridges in our dataset are stable and conserved in nature. Although, average contributions of component energy terms are equal, their individual details vary greatly from one another indicating their sensitivity to local micro-environment. Notably, 35% of salt-bridges in our database are buried and stable. Greater desolvation penalty of these buried salt-bridges are counteracted by stable network salt-bridges apart from favorable equal contributions of bridge and background terms. Recruitment of extensive network salt-bridges (46%) with a net contribution of ?5.0 kcal mol?1 per salt-bridge, seems to be a halophilic design wherein favorable average contribution of background term (?10 kcal mol?1) exceeds than that of bridge term (?7 kcal mol?1). Interiors of proteins from halophiles are seen to possess relatively higher abundance of charge and polar side chains than that of mesophiles which seems to be satisfied by cooperative network salt-bridges. Overall, our theoretical analyses provide insight into halophilic signature in its specific electrostatic interactions which we hope would help in protein engineering and bioinformatics studies. PMID:24743799
NASA Astrophysics Data System (ADS)
Lantz, Juliette M.; Feindt, Jenny E.; Lewellyn, Eric P. B.; Walczak, Mary M.
1999-12-01
The Bridge of Mandolin County is a case designed to teach the general chemistry principles of molar mass, ions and aqueous reactions, solubility rules, and inorganic nomenclature. Through the instructor-facilitated class discussion, students consider the options before the Mandolin Town Council regarding deicing the newly constructed bridge connecting Mandolin with a large nearby city. The students must decipher contradictory claims made on behalf of sodium chloride, the traditional deicer, and calcium magnesium acetate, a new environmentally friendly deicer, to arrive at the most cost-effective and environmentally appropriate deicing product. As they work through the analysis they raise questions that can be addressed in a laboratory setting. Four optional role-playing experiments are included, which can be used by the students to gather information helpful to resolution of the case. The case is intended to be used over two class periods, with a laboratory period in between, though suggestions for other models are provided. Laboratory procedures include an EDTA titration for Ca2+ and Mg2+, a gravimetric analysis, a qualitative examination of ions and solubility, an introduction to freezing point depression and measurement, and an experimental design activity. This case can also successfully be used without alteration in non-majors chemistry or environmental chemistry courses, or upper-level analytical or environmental chemistry courses.
2. Contextual view of bridge in setting, from northwest end ...
2. Contextual view of bridge in setting, from northwest end of bridge, view to south-southeast with Rawson Road in foreground. - Red Bank Creek Bridge, Spanning Red Bank Creek at Rawson Road, Red Bluff, Tehama County, CA
6. EARLY MORNING VIEW OF BOTH JOSO HIGH BRIDGE (UNION ...
6. EARLY MORNING VIEW OF BOTH JOSO HIGH BRIDGE (UNION PACIFIC RAILROAD) IN BACKGROUND AND LYONS FERRY BRIDGE IN THE FOREGROUND - Snake River Bridge at Lyons' Ferry, State Route 261 spanning Snake River, Starbuck, Columbia County, WA
9. View of bridge looking west. A fundraising marathon is ...
9. View of bridge looking west. A fund-raising marathon is in prgress. The traffic levels outside the main arch were added in 1965 when the bridge underwent extensive rehabilitation. - Detroit Superior High Level Bridge, Cleveland, Cuyahoga County, OH
25 CFR 170.507 - Who reviews bridge inspection reports?
Code of Federal Regulations, 2010 CFR
2010-04-01
...2010-04-01 2010-04-01 false Who reviews bridge inspection reports? 170.507 Section...Indian Reservation Roads Program Facilities Bridge Inspection § 170.507 Who reviews bridge inspection reports? The person...
49 CFR 237.51 - Railroad bridge engineers.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Railroad bridge engineers. 237.51 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Qualifications and...Responsible Persons § 237.51 Railroad bridge engineers. (a) A railroad...
33 CFR 118.100 - Retroreflective panels on bridge piers.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 2010-07-01 false Retroreflective panels on bridge piers. 118.100 Section 118.100 Navigation...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.100...
21 CFR 872.3770 - Temporary crown and bridge resin.
Code of Federal Regulations, 2010 CFR
2010-04-01
...2010-04-01 false Temporary crown and bridge resin. 872.3770 Section 872.3770...Devices § 872.3770 Temporary crown and bridge resin. (a) Identification. A temporary crown and bridge resin is a device composed of a...
33 CFR 115.70 - Advance approval of bridges.
Code of Federal Regulations, 2010 CFR
2010-07-01
...2010-07-01 2010-07-01 false Advance approval of bridges. 115.70 Section 115.70 Navigation and Navigable...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE...
29 CFR 1917.124 - Dockboards (car and bridge plates).
Code of Federal Regulations, 2010 CFR
2010-07-01
...2010-07-01 false Dockboards (car and bridge plates). 1917.124 Section 1917... § 1917.124 Dockboards (car and bridge plates). (a) General. The...Reserved] (c) Dockboards (car and bridge plates). (1) Dockboards shall...
33 CFR 164.15 - Navigation bridge visibility.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 2010-07-01 false Navigation bridge visibility. 164.15 Section 164...REGULATIONS § 164.15 Navigation bridge visibility. (a) The arrangement...the field of vision from the navigation bridge conforms as closely as possible to...
49 CFR 236.766 - Locking, movable bridge.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Locking, movable bridge. 236.766 Section 236.766 Transportation... Definitions § 236.766 Locking, movable bridge. The rail locks, bridge locks, bolt locks, circuit controllers,...
49 CFR 237.101 - Scheduling of bridge inspections.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Scheduling of bridge inspections. 237.101 Section 237.101 ...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.101 Scheduling of...
49 CFR 237.31 - Adoption of bridge management programs.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Adoption of bridge management programs. 237.31 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance § 237.31 Adoption of...
49 CFR 237.55 - Railroad bridge supervisors.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Railroad bridge supervisors. 237.55 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Qualifications and...Responsible Persons § 237.55 Railroad bridge supervisors. A railroad...
49 CFR 237.33 - Content of bridge management programs.
Code of Federal Regulations, 2010 CFR
2010-10-01
...2010-10-01 2010-10-01 false Content of bridge management programs. 237.33 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance § 237.33 Content of...
1. AERIAL VIEW LOOKING SOUTHWEST (OLD HARVARD STREET BRIDGE AT ...
1. AERIAL VIEW LOOKING SOUTHWEST (OLD HARVARD STREET BRIDGE AT LEFT, NEW BRIDGE AT RIGHT) - Old Harvard Street Bridge, Spanning Rock Creek at National Zoological Park, Washington, District of Columbia, DC
1. VIEW, LOOKING NORTH, SHOWING GROTON BRIDGE (FOREGROUND) AND HIGHWAY ...
1. VIEW, LOOKING NORTH, SHOWING GROTON BRIDGE (FOREGROUND) AND HIGHWAY BRIDGE (BACKGROUND) - New York, New Haven & Hartford Railroad, Groton Bridge, Spanning Thames River between New London & Groton, New London, New London County, CT
Vincent Thomas Bridge Vibration Debasis Karmakar, Ho Lee
Shinozuka, Masanobu
Vincent Thomas Bridge Vibration Debasis Karmakar, Ho Lee Faculty Advisor: Prof. Masanobu Shinozuka of bridge performance under live load (e.g. truck load) before and after the retrofitting of the bridge
2. Contextual view of bridge in setting, from north end ...
2. Contextual view of bridge in setting, from north end of bridge, view to north along Dillon Road. Former Valley Flower Creamery at right center. - Salt River Bridge, Spanning Salt River at Dillon Road, Ferndale, Humboldt County, CA
23 CFR 650.705 - Application for discretionary bridge funds.
Code of Federal Regulations, 2011 CFR
2011-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Discretionary Bridge Candidate Rating Factor § 650.705 Application for discretionary bridge funds. Each year...
23 CFR 650.705 - Application for discretionary bridge funds.
Code of Federal Regulations, 2010 CFR
2010-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Discretionary Bridge Candidate Rating Factor § 650.705 Application for discretionary bridge funds. Each year...
23 CFR 650.705 - Application for discretionary bridge funds.
Code of Federal Regulations, 2012 CFR
2012-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Discretionary Bridge Candidate Rating Factor § 650.705 Application for discretionary bridge funds. Each year...
23 CFR 650.807 - Bridges requiring a USCG permit.
Code of Federal Regulations, 2010 CFR
2010-04-01
...ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges...at the appropriate level by FHWA for structural concepts, hydraulics, and navigational clearances prior to submission of the...
23 CFR 650.807 - Bridges requiring a USCG permit.
Code of Federal Regulations, 2014 CFR
2014-04-01
...ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges...at the appropriate level by FHWA for structural concepts, hydraulics, and navigational clearances prior to submission of the...
23 CFR 650.705 - Application for discretionary bridge funds.
Code of Federal Regulations, 2014 CFR
2014-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Discretionary Bridge Candidate Rating Factor § 650.705 Application for discretionary bridge funds. Each year...
23 CFR 650.807 - Bridges requiring a USCG permit.
Code of Federal Regulations, 2011 CFR
2011-04-01
...ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges...at the appropriate level by FHWA for structural concepts, hydraulics, and navigational clearances prior to submission of the...
23 CFR 650.807 - Bridges requiring a USCG permit.
Code of Federal Regulations, 2012 CFR
2012-04-01
...ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges...at the appropriate level by FHWA for structural concepts, hydraulics, and navigational clearances prior to submission of the...
23 CFR 650.705 - Application for discretionary bridge funds.
Code of Federal Regulations, 2013 CFR
2013-04-01
...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Discretionary Bridge Candidate Rating Factor § 650.705 Application for discretionary bridge funds. Each year...
23 CFR 650.807 - Bridges requiring a USCG permit.
Code of Federal Regulations, 2013 CFR
2013-04-01
...ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges...at the appropriate level by FHWA for structural concepts, hydraulics, and navigational clearances prior to submission of the...
2. GENERAL VIEW OF BRIDGE FROM ROADBED WITH 4' RANGE ...
2. GENERAL VIEW OF BRIDGE FROM ROADBED WITH 4' RANGE POLE NEAR NORTHWEST CORNER OF BRIDGE, LOOKING SOUTH - North Fork Bridge, Spans North Fork of White River at State Highway 5, Norfork, Baxter County, AR
8. West side of north end of bridge resting on ...
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
14. REPRESENTATIVE DETAIL VIEW OF THE TWO ARCHED PEDESTRIAN BRIDGES ...
14. REPRESENTATIVE DETAIL VIEW OF THE TWO ARCHED PEDESTRIAN BRIDGES OVER THE CANALS. THIS BRIDGE IS THE GRAND CANAL COURT BRIDGE OVER CARROLL CANAL - Venice Canals, Community of Venice, Los Angeles, Los Angeles County, CA
25. REPRESENTATIVE DETAIL VIEW OF THE TWO ARCHED PEDESTRIAN BRIDGES ...
25. REPRESENTATIVE DETAIL VIEW OF THE TWO ARCHED PEDESTRIAN BRIDGES OVER THE CANALS, SHOWING PLANKS AND RAILS. THIS BRIDGE IS THE LINNIE CANAL COURT BRIDGE OVER EASTERN CANAL. - Venice Canals, Community of Venice, Los Angeles, Los Angeles County, CA
1. OVERALL VIEW OF BRIDGE AND LINCOLN HIGHWAY, SHOWING NORTH ...
1. OVERALL VIEW OF BRIDGE AND LINCOLN HIGHWAY, SHOWING NORTH APPROACH TO BRIDGE. VIEW TO SOUTH. - Rock Valley Bridge, Spanning North Timber Creek at Old U.S. Highway 30, Marshalltown, Marshall County, IA
7. VIEW ACROSS BRIDGE FROM NORTHWEST CORNER WITH WIDE ANGLE ...
7. VIEW ACROSS BRIDGE FROM NORTHWEST CORNER WITH WIDE ANGLE LENS SHOWING BRIDGE IN LANDSCAPE. - Wildcat Creek Bridge, Spanning Wildcat Creek on New Big Oak Flat Road, Yosemite Village, Mariposa County, CA
5. HISTORIC VIEW LOOKING FROM PENNSYLVANIA AVENUE BRIDGE SOUTH TO ...
5. HISTORIC VIEW LOOKING FROM PENNSYLVANIA AVENUE BRIDGE SOUTH TO OLD (1907 STEEL-GIRDER) K STREET BRIDGE. MLK LIBRARY. - K Street Bridge, Spanning Rock Creek & Potomac Parkway, Washington, District of Columbia, DC
6. DRAWING OF ORIGINAL K STREET BRIDGE, LEONARD HARBAUGH ARCHITECT, ...
6. DRAWING OF ORIGINAL K STREET BRIDGE, LEONARD HARBAUGH ARCHITECT, 28TH MARCH, 1792. USED IN OCTAGON BRIDGE EXHIBIT, NOVEMBER 1975; SOURCE, COMMISSION OF FINE ARTS. - K Street Bridge, Spanning Rock Creek & Potomac Parkway, Washington, District of Columbia, DC
Plastic Hinging Behavior of Reinforced Concrete Bridge Columns
Firat Alemdar, Zeynep
2010-04-27
The location of inelastic deformations in reinforced concrete bridge columns has been examined to simulate the nonlinear response of bridge columns and estimate the ultimate displacement capacity. In bridge columns, these ...
INNOVATIVE INVESTIGATIONS IN A PRESTRESSED CONCRETE BRIDGE Adrien Houel1
Boyer, Edmond
external additional prestressing. KEYWORDS : prestressed concrete bridge, fatigue, residual lifetime, non launch the project of heavy repair of the bridge per external additional prestressing. 1 PRESENTATIONINNOVATIVE INVESTIGATIONS IN A PRESTRESSED CONCRETE BRIDGE Adrien Houel1 , Michel Valade1 , Didier
10. Detail, dedication plaque on the bridge's northeast end (plaque ...
10. Detail, dedication plaque on the bridge's northeast end (plaque on southwest end of bridge is identical - Big Cottonwood River Bridge No. 246, Spanning Big Cottonwood River at Cottonwood Street (City Road No. 165), New Ulm, Brown County, MN
12. Interior detail of bridge operator's house showing generator and ...
12. Interior detail of bridge operator's house showing generator and bridge operator, Mr. Gene Amonette, facing west. - Palm Valley Bridge, County Road 210 spanning Intracoastal Waterway, Ponte Vedra Beach, St. Johns County, FL
Sundararajan, N; Ganapathi, M; 10.1016/j.finel.2005.06.001
2011-01-01
The nonlinear formulation developed based on von Karman's assumptions is employed to study the free vibration characteristics of functionally graded material (FGM) plates subjected to thermal environment. Temperature field is assumed to be a uniform distribution over the plate surface and varied in the thickness direction. The material is assumed to be temperature dependent and graded in the thickness direction according to the power-law distribution in terms of volume fractions of the constituents. The effective material properties are estimated from the volume fractions and the material properties of the constituents using Mori-Tanaka homogenization method. The nonlinear governing equations obtained using Lagrange's equations of motion are solved using finite element procedure coupled with the direct iteration technique. The variation of nonlinear frequency ratio with amplitude is highlighted considering various parameters such as gradient index, temperature, thickness and aspect ratios, and skew angle. For...
Flight demonstration of redundancy management algorithms for a skewed array of inertial sensors
NASA Technical Reports Server (NTRS)
Morrell, F. R.; Bailey, M. L.; Motyka, P. R.
1988-01-01
Flight test results for two fault-tolerance algorithms developed for a redundant strapdown inertial measurement unit consisting of four 2-DOF gyros and accelerometers mounted on the faces of a semioctahedron are presented. Although both algorithms provided timely detection and isolation of flight control level failures, the generalized likelihood test algorithm provided more timely detection and isolation of low-level sensor failures than the edge vector test algorithm. The generalized likelihood test produced a false isolation for the case of a dual low-level failure applied to the sensitive axes of an accelerometer. Both of the algorithms were shown to provide dual fail-operational performance for the skewed array of inertial sensors.
Infrared Thermography Testing of FRP Bridge Decks
Cheng L. Hing; Udaya B. Halabe; Powsiri Klinkhachorn; Hota V. S. GangaRao
2007-01-01
This paper presents the results from an experimental study that investigated the use of infrared thermography for subsurface defect detection in Fiber Reinforced Polymer (FRP) bridge decks. FRP bridge deck specimens were cast with embedded subsurface defects (air- and water-filled) of varying planar sizes and thicknesses. These decks were tested using infrared thermography under the influence of several heating sources
NSDL National Science Digital Library
2012-06-26
In this hands-on activity, learners make a bridge out of a folded piece of paper and two blocks. Then they test their structure by stacking coins (and other things) on it, discovering how much weight the bridge can support before it collapses. This activity explores engineering, technology, architecture, weight, compression, tension, and balance.
The adventures of the bridge jumper
Jacob Smith
2010-01-01
Steve Brodie's 1886 jump from the Brooklyn Bridge created a particularly modern fame that has much to tell us about the emergence of modern media celebrity and the kinds of spectacular stunt performances that could be mobilised to create it in the years just before the cinema. Bridge jumpers such as Brodie took the modern urban landscape as their backdrop,
The Heart Failure Bridge Clinic Quality
von der Heydt, Rüdiger
The Heart Failure Bridge Clinic Quality Improvement Project My project involved working with my failure case manager. The heart failure bridge clinic (HFBC), is a standalone clinic that was created for patients, with the primary diagnosis of congestive heart failure (CHF), to be seen in an outpatient setting
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…
Teaching Elements and Principles of Bridge Design
ERIC Educational Resources Information Center
Beck, Charles
2005-01-01
Bridge construction is a popular classroom activity. However, the basic principles of tension, compression, and counterbalance are not always clearly represented and defined. The common materials used to construct model bridges, such as straws, toothpicks, Legos[TM], and building blocks, are often too flexible or stationary to demonstrate the…
Instrumentation for load rating of bridges
NASA Astrophysics Data System (ADS)
Fuchs, P. A.; Chase, Steven B.
1998-03-01
A large percentage of the nation's bridges are classified as structurally deficient or functionally obsolete. Many bridges are classified as such due to the bridge's load rating. However, the vast majority of bridges are not actually tested to determine their load capacity. In general, actually testing a structure to determine the load rating is time consuming and expensive. As a result only a low number of bridges can be tested. A main time consuming portion of the load test is the setup of conventional instrumentation to monitor the status of the bridge under test. Typically strain gages and LVDT (or similar) deflection transducers are used. Instrumentation which would allow rapid load testing of bridges is currently being developed and tested at the Federal Highway Administration. This instrumentation includes wireless data acquisition systems interfaced with clamp-on strain gages, which can be placed at a measurement location in a matter of minutes. Also, the instrumentation includes a remote laser- based deflection measurement system. The combination of the two types of instrumentation, wireless data acquisition and laser-based deflection measurements, has the potential to allow a greater number of structures to be load rated giving a more accurate picture of the health of the nation's bridges.
Seismic Risk Management Framework of Bridge Engineering
Lu Mingqi; Qu Weibo
2009-01-01
Seismic damages of bridges may have great effects on traffic transport. In order to reduce the losses of the disaster, it is necessary to carry out seismic risk management of bridge engineering. In the paper, the seismic risk management framework was proposed and the main steps of risk management including risk identification, risk analysis, risk assessment and risk control were
Bridges to Healthy Communities. AACC Project Brief.
ERIC Educational Resources Information Center
Ottenritter, Nan; Barnett, Lynn
The Bridges to Healthy Communities project assists community colleges in offering education and information services that help prevent HIV infection and other serious health problems in students. The five-year Bridges project emphasizes service learning as a community-building and intervention strategy for preventing HIV infection. This initiative…
BDES: A bridge design expert system
Mrinmay Biswas; James G. Welch
1987-01-01
The expert system described here designs superstructures for small to medium span highway bridges. The system addresses a domain within the engineering design consultation paradigm. It is installed in a personal microcomputer environment. This paper examines the nature of the bridge design domain as practiced in the United States and its suitability for expert system application. The architecture, the context
Effect of modal damping on bridge aeroelasticity
Anurag Jain; Nicholas P. Jones; Robert H. Scanlan
1998-01-01
Estimation of modal damping is always a critical first step in the analytical estimation of the flutter and buffeting reponses of long-span suspended bridges. The impact of under or over estimation of modal damping on the aerodynamic and aeroelastic behavior of suspended bridges is not clear. This issue surfaced when a seismic retrofit of the Golden Gate birdge using viscous
Paul Dirac:. Building Bridges of the Mind
NASA Astrophysics Data System (ADS)
Brown, Laurie M.
2003-12-01
Paul Dirac was a brilliant and original thinker. He used his physical intuition and his ideal of mathematical beauty to construct bridges between major areas of physics. This article discusses several such important works, including the bridge between quantum mechanics and relativity that led to his prediction of the existence of antimatter.
Bridges 2013 Poetry Anthology Sarah Glaz, Editor
Glaz, Sarah
Bridges 2013 Poetry Anthology Sarah Glaz, Editor Contents Introduction Poems by Bridges Enschede Featured Poets Michael Bartholomew-Biggs Numerical Analysis Quasi-Haiku Sequence 3 Teaching Practice 4 Two Strip 55 Infinity to the Nth Power 56 Mathematical Poetry Anthologies 57 #12;
Flexural Strengthening of Prestressed Bridge Slabs
Flexural Strengthening of Prestressed Bridge Slabs with FRP Systems Tarek Hassan Ph.D. Candidate prestressed concrete members. Half-scale models of a prestressed concrete bridge were constructed and tested were investigated including near surface mounted Leadline bars, C-Bars, CFRP strips and externally
NASA Astrophysics Data System (ADS)
Shiau, T. N.; Chen, E. C.; Huang, K. H.; Hsu, W. C.
In this study the global assumed mode method (GAMM) is used to analyze the dynamic behavior of a spinning Timoshenko beam subjected to a moving skew force with general boundary conditions. The moving skew force is usually caused by the frictional effect or the weight of the components. Considering three general geometric boundaries, i.e. hinged-hinged, clamped-clamped, and clamped-hinged, the system equations of motion are derived by the Lagrangian approach combining with the GAMM. The transient response of the system due to a moving skew force is evaluated by the Runge-Kutta method. The numerical results show that the lateral deflections due to the skew force for the hinged-hinged boundary case are smaller than those in the case of a clamped-clamped or clamped-hinged boundary. And the axial deflections due to the skew force are larger in the case of a hinged-hinged boundary.
NASA Astrophysics Data System (ADS)
Sawetsakulanond, Budhapon; Kinnares, Vijit
This paper presents analysis and investigation of the skew effect on behavior and performance of a three-phase, 220/380V, 8.7/5.0A, ?/Y connected, 4 poles, 2.2kW self-excited induction generator (SEIG) with different angles rotor skewing. A 2D finite element analysis (2D-FEA) is used to consider core loss, flux density and circuit parameters. Analysis of excitation capacitor values for the SEIG based on a steady-state equivalent circuit model including rotor skew effect is given. Skewed rotor slots with angle of 0° (non-skew), 5° and 10° for the SEIGs are employed. Testing and performance comparisons under steady-state operation with a pure resistive load have been conducted. Obtained results can be guidelines and recommendations for development of effective wind induction generators.
Th1-skewed tissue responses to a mycolyl glycolipid in mycobacteria-infected rhesus macaques
Morita, Daisuke; Miyamoto, Ayumi; Hattori, Yuki; Komori, Takaya [Laboratory of Cell Regulation, Institute for Virus Research, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan)] [Laboratory of Cell Regulation, Institute for Virus Research, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Nakamura, Takashi [Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan)] [Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan); Igarashi, Tatsuhiko, E-mail: tigarash@virus.kyoto-u.ac.jp [Laboratory of Primate Model, Institute for Virus Research, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan)] [Laboratory of Primate Model, Institute for Virus Research, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan); Harashima, Hideyoshi, E-mail: harasima@pharm.hokudai.ac.jp [Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan)] [Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan); Sugita, Masahiko, E-mail: msugita@virus.kyoto-u.ac.jp [Laboratory of Cell Regulation, Institute for Virus Research, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan)] [Laboratory of Cell Regulation, Institute for Virus Research, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 (Japan)
2013-11-08
Highlights: •Glucose monomycolate (GMM) is a marker glycolipid for active tuberculosis. •Tissue responses to GMM involved up-regulation of Th1-attracting chemokines. •Th1-skewed local responses were mounted at the GMM-injected tissue. -- Abstract: Trehalose 6,6?-dimycolate (TDM) is a major glycolipid of the cell wall of mycobacteria with remarkable adjuvant functions. To avoid detection by the host innate immune system, invading mycobacteria down-regulate the expression of TDM by utilizing host-derived glucose as a competitive substrate for their mycolyltransferases; however, this enzymatic reaction results in the concomitant biosynthesis of glucose monomycolate (GMM) which is recognized by the acquired immune system. GMM-specific, CD1-restricted T cell responses have been detected in the peripheral blood of infected human subjects and monkeys as well as in secondary lymphoid organs of small animals, such as guinea pigs and human CD1-transgenic mice. Nevertheless, it remains to be determined how tissues respond at the site where GMM is produced. Here we found that rhesus macaques vaccinated with Mycobacterium bovis bacillus Calmette–Guerin mounted a chemokine response in GMM-challenged skin that was favorable for recruiting T helper (Th)1 T cells. Indeed, the expression of interferon-?, but not Th2 or Th17 cytokines, was prominent in the GMM-injected tissue. The GMM-elicited tissue response was also associated with the expression of monocyte/macrophage-attracting CC chemokines, such as CCL2, CCL4 and CCL8. Furthermore, the skin response to GMM involved the up-regulated expression of granulysin and perforin. Given that GMM is produced primarily by pathogenic mycobacteria proliferating within the host, the Th1-skewed tissue response to GMM may function efficiently at the site of infection.
Dennis, Patricia M; Rajala-Schultz, Paivi J; Funk, Julie A; Blumer, Evan S; Miller, R Eric; Wittum, Thomas E; Saville, William J A
2007-12-01
The skew toward males in the sex ratio of calves is considered to be a problem for the captive population of black rhinoceroses (Diceros bicornis) in North America. This study used a retrospective case-control design to determine whether there was a predisposition toward birth of male calves over female calves and to examine risk factors associated with the occurrence of any detected skewed natal sex ratio in captive black rhinoceroses in the United States. The study population included captive female black rhinoceroses housed in the United States that had given birth to at least one calf of known sex. This study confirmed a skewing of the natal sex ratio toward male calves in the captive black rhinoceros population. The skewed ratio was found in calves born to wild-born dams, for which an increased time in captivity, irrespective of age, was associated with an increased likelihood of a male calf. Dams between 12 and 19 yr of age had a decreased likelihood of a male calf. The data also suggested a possible trend for the southern subspecies of black rhinoceros (Diceros bicornis minor) to be more likely to produce male calves than the eastern subspecies (Diceros bicornis michaeli). No associations were found with the sex of offspring in captive-born dams: however, this lack of association could be a result of low power in the study. PMID:18229858
Ibbotson, Paul
2013-01-01
We use the Google Ngram database, a corpus of 5,195,769 digitized books containing ~4% of all books ever published, to test three ideas that are hypothesized to account for linguistic generalizations: verbal semantics, pre-emption and skew. Using 828,813 tokens of un-forms as a test case for these mechanisms, we found verbal semantics was a good predictor of the frequency of un-forms in the English language over the past 200 years—both in terms of how the frequency changed over time and their frequency rank. We did not find strong evidence for the direct competition of un-forms and their top pre-emptors, however the skew of the un-construction competitors was inversely correlated with the acceptability of the un-form. We suggest a cognitive explanation for this, namely, that the more the set of relevant pre-emptors is skewed then the more easily it is retrieved from memory. This suggests that it is not just the frequency of pre-emptive forms that must be taken into account when trying to explain usage patterns but their skew as well. PMID:24399991
Niibori, Y.; Tochiyama, O.; Chida, T. [Tohoku Univ., Sendai (Japan)
1997-12-31
The authors have investigated the characteristic permeability on the basis of some probability density functions of permeability, applying the Monte Carlo method and FEM. It was found that its value does not depend on type of probability density function of permeability, but on the arithmetic mean, the standard deviation and the skewness of permeability. This paper describes the use of the stochastic values of permeability for estimating the rate of radioactivity release to the accessible environment, applying the advection-dispersion model to two-dimensional, heterogeneous media. When a discrete probability density function (referred to as the Bernoulli trials) and the lognormal distribution have common values for the arithmetic mean, the standard deviation and the skewness of permeability, the calculated transport rates (described as the pseudo impulse responses) show good agreements for Peclet number around 10 and the dimensionless standard deviation around 1. Further, it is found that the transport rates apparently depends not only on the arithmetic mean and the standard deviation, but also on the skewness of permeability. When the value of skewness does not follow the lognormal distribution which has only two independent parameters (the mean and the standard deviation), the authors can replicate the three moments estimated from an observed distribution of permeability, by using the Bernoulli trials having three independent parameters.
Starks, Philip
, we test predictions of `classical' two-person skew models as well as more complex `N-person' models. In contrast to N-person model predictions, group size tended to increase with relatedness. Although we did offspring emergence (reviewed in Reeve 1991; Starks 2001; SeppaÂ¨ et al. 2002; Tibbetts & Reeve 2003; but see
Seismic response of steel suspension bridge
McCallen, D.B. [Lawrence Livermore National Lab., CA (United States); Astaneh-Asl, A. [California Univ., Berkeley, CA (United States). Dept. of Civil and Environmental Engineering
1996-11-01
Performing accurate, realistic numerical simulations of the seismic response of long-span bridges presents a significant challenge to the fields of earthquake engineering and seismology. Suspension bridges in particular represent some of the largest and most important man-made structures and ensuring the seismic integrity of these mega-structures is contingent on accurate estimations of earthquake ground motions and accurate computational simulations of the structure/foundation system response. A cooperative, multi-year research project between the Univ. of California and LLNL was recently initiated to study engineering and seismological issues essential for simulating the response of major structures. Part of this research project is focused on the response of the long-span bridges with the San Francisco-Oakland Bay Bridge serving as a case study. This paper reports on the status of this multi-disciplinary research project with emphasis on the numerical simulation of the transient seismic response of the Bay Bridge.
An update on resin-bonded bridges.
Barber, M W; Preston, A J
2008-03-01
Since the introduction of the 'Rochette' bridge in the 1970s the resin-bonded bridge has undergone a number of developments to become a commonly used technique for replacement of a missing tooth, especially in a minimally restored dentition. One of the major advantages of the resin-bonded bridge is that it requires less tooth preparation than conventional bridgework, with some authorities advising no preparation at all. Some reports have suggested poor long-term success rates, however, if used in appropriate clinical situations, this treatment modality can be extremely successful. The aim of this paper is to review the literature relating to resin-bonded bridges and suggest recommendations for clinicalpractice concerning the provision of resin-bonded bridges. PMID:18468318
Politicizing NIH funding: a bridge to nowhere.
Epstein, Jonathan A
2011-09-01
We live in a time of increased spending, mounting debt, and few remedies for balancing the federal budget that have bipartisan support. Unfortunately, one recent target for decreased allocations of the federal budget is the NIH; the discussion of the awarded grants and the grant funding process has been skewed and altered to present medical research in an unfriendly light, and this can have very damaging repercussions. Politicizing this process could ultimately challenge human health, technology, and economic growth. PMID:21881213