Horizontal Arch Research Articles

The effects of unilateral premature loss of maxillary primary molars on the dental arch dimensions

Background: The aim of the study was to evaluate the amount of changes in the horizontal and vertical maxillary arch dimensions measurements following the premature loss of primary molars. Materials and methods: The sample consist of (50) children with unilateral prematurely extracted either first or second primary molars at the mixed dentition stage. Results and Conclusions: Results shows that there was an increase in the vertical incisor to canine distance (A) with both premature loss of first & second primary molars due to distal movement of primary canines and at the same time there were a significant loss of space in the extraction space with premature loss of second primary molar due to a mesial movement of maxillary first permanent molars which at the same time tip lingually and this is clear obvious from the decrease in the inter-molars distances horizontally.

Local buckling and concrete confinement of concrete-filled box columns under axial load

Nine square concrete-filled box column (CFBC) specimens were fabricated and tested under monotonic axial loading. The loading tests were simulated with the commercial finite element program ABAQUS. The feasibility of the finite element models was verified. Based on tests and FEM simulation results, the following conclusions can be made. The development procedure of the concrete confinement mechanism of CFBCs was identified. After concrete crushing occurs, concrete confinement provided by the horizontal arch action starts to become noticeable. After buckling of the column wall, vertical arch action, which provides additional concrete confinement, is developed. Horizontal arch action acting together with vertical arch action provides significant confinement for the concrete to gain and recover its strength. A larger width-to-thickness ratio of the column wall results in the earlier development of vertical arch action. From the concrete confinement mechanism, there will be a strength drop and a strength recovery in the concrete component of the load versus axial strain curve. As a result of these findings, Mander's concrete confinement model and Sakino's concrete analytical model were not able to reasonably predict the stress–strain behavior of the concrete inside CFBCs.

Sound localising ability in children with bilateral sequential cochlear implants

ObjectivesTo evaluate the sound localisation ability in children with sequential bilateral cochlear implants and the potential influence of age at the time of the first implantation, years of experience with the first implanted ear and the inter-implant interval (time between the first and the second cochlear implantation). MethodsSixty-three prelingually deaf children (mean age, 11.03; range, 6.5–17 years; SD, 3.09) were tested after 12 and 24 months of using bilateral cochlear implants. Every child was tested with each ear alone and both ears together. Five loudspeakers were placed in a 180° horizontal arch with 45° of separation between each loudspeaker. The child was placed 1.5m from the speakers. For each test run, three stimuli were presented at 65dB (A) from each speaker for a total of 15 stimulus presentations. For each test run, we calculated the mean angular error (MAE) and the proportion of correct speakers identified (CSS: correct speaker score). Performance by chance for the MAE was 72° and for the CSS was 20% (1 of 5 speakers). ResultsAfter 12 months of using bilateral CIs, the added effect of the second CI in the MAE was minor, and there was no significant difference in CSS between listening in the unilateral condition and listening in bilateral condition. After 24 months, however, the added effect of the second CI in the MAE was significant (mean diff=12.2°; 95% CI; 4.5–20.0°, p=0.003). The mean bilateral CSS increased significantly to 38% (diff=7.7%; 95% CI; 1.4–14.0%; p=0.019) while the mean unilateral CSS remained at a similar level (27%). The influence of age at the time of the first implantation on CSS after 24 months was not significant (p=0.96). However, the inter-implant interval showed a significant decrease in score by 1.4% per year between the two implants (p=0.04). ConclusionSound localisation with two versus one CI in children with a sequential bilateral cochlear implantation was significantly improved 24 months (but not 12 months) after the second implantation. A shorter inter-implant interval showed a small but significant beneficial effect on sound localisation.

The contribution of horizontal arching to tunnel face stability

AbstractThe article revisits the classic problem of tunnel face stability with special emphasis on the effect of horizontal stresses. These are important for shear resistance and thus also for the equilibrium of the potentially unstable body in front of the tunnel face, but they also present the difficulty of static indeterminacy. Starting from the computational model of Anagnostou and Kovári, an alternative model is presented, which is based on the so‐called method of slices, and is consistent with silo theory, but does not need an a priori assumption as to the distribution of horizontal stress. In addition, a simple design equation for estimating support pressure under this model is presented and the results of comparative analyses concerning the average stresses in the wedge and the effects of shear resistance at the lateral slip surfaces are shown. The analytical results obtained by the method of slices agree very well with published results of numerical analyses and physical tests.Beitrag der räumlichen Tragwirkung zur Stabilität der Tunnelbrust. Der vorliegende Artikel untersucht das klassische Problem der Stabilität der Ortsbrust unter besonderer Beachtung der Horizontalspannungen. Letztere sind zwar sehr wichtig für den Gleitwiderstand und somit auch für die Stabilität von potenziellen Bruchkörpern, können aber nicht allein aufgrund von Gleichgewichtsbetrachtungen ermittelt werden. Im Beitrag wird eine Berechnungsmethode vorgestellt, die das Berechnungsmodell nach Anagnostou und Kovári insofern verbessert, dass sie keine a priori Annahme über die Verteilung der Spannungen im keilförmigen Bruchkörper vor der Ortsbrust benötigt und auf konsistente Weise das Gleichgewicht im Keil und im darüber liegenden prismatischen Bruchkörper analysiert. Basierend auf der Lamellenmethode wird eine einfache Bemessungsformel aufgestellt und der Einfluss der horizontalen Verspannung auf den erforderlichen Stützdruck der Ortsbrust aufgezeigt. Die Modellprognosen stimmen mit veröffentlichten Ergebnissen von numerischen Spannungsanalysen sowie mit Versuchsresultaten gut überein.

A34 開張率と開張角の信頼性と開張足の診断基準値と障害予防の検討(計測・診断技術)

It proposed the index value of the open Cho rate and the open Cho angle where the spread foot is simply judged without using X rays, and the relation to other diseases is investigated. As a result on subjects, 37% or more in open, 15 degrees or more reached the index value, and the pain by hallux valgus and the pain of the second metatarsal bone were often the cases in open. It seems to be necessary that some treatment with in-sole are required at the early stage to prevent from the injury if the decrease of horizontal arch is found.

Nanning Butterfly Tied Arch Bridge Over the Yong River in China

The Nanning Butterfly Tied Arch is a unique three-dimensional (3D) arch that incorporates several design and analysis innovations. The curved orthotropic deck with a horizontally draped internal tie resists both arch thrust and serves as a horizontal arch to resist out-of-balance lateral forces imparted by the asymmetric arch ribs. This force resisting system was confirmed and refined by 3D shape-finding studies. The arch rib segments are orthotropic boxes, which is a first for long span arches. And most notably, this is the last bridge worked on by the late Prof. T.Y. Lin.

Modelling of an arch dam by polynomial interpolation

Polynomial curves controlled by points as well as by the tangents in them allow for a great margin of freedom, far from the conditions implied by the use of conventional curves, in the design of free-form curves. The lofting technique, in turn, permits us to generate surfaces that include a series of given curves. The algorithms propitiated to generate these curves and surfaces are very suitable for the geometric design of the arch dam, since they provide for a design of the curves forming the horizontal arches in which the dam can conceivably be divided taking into account, besides, the angle among the tangents to the arch at its ends as well as the hillsides of the closed arch. Once these curves are designed, the facings of a dam can be generated as the surfaces involving both series of previous curves. This paper presents the geometric calculations behind the generation of both surfaces and their computerized processing, in addition to a practical example of the use of the proposed methodology.

‘Connecticut motive’: Beatrix Farrand and the Marsh Botanic Garden of Yale University 1922–1939

Little survives today of the Marsh Botanic Garden of Yale University as it was designed and planted by Beatrix Farrand in the 1920s. But there still endures, the venerable white oak, a critical player in the dialogue that accompanied the garden's evolution. It remains standing in the center of the eight-acre garden that surrounds a turreted stone mansion at the top of science hill on Prospect Street in New Haven, its central branches rent by storms into a horizontal silhouette, which stoops and arches, still casting its cool shade across Yale afternoons. It was there, on one such Saturday afternoon, in the autumn of 1931, that a group of field botanists, members of the Connecticut Botanical Society, ‘remained to lunch under one of the great white oak trees in the grounds surrounding the Marsh gardens’ (figure 1). They had been admiring the two rare gordonia shrubs blooming in the Farnam Memorial Garden on the opposite side of Prospect Street. A year earlier, the same group had witnessed gentians from the pine barrens of New Jersey, pinks from the salt marshes, 25 varieties of aster and 35 of goldenrod, and a dozen different sunflowers: all plants indigenous to North America, raised from collected seed and ‘now in full bloom in the ordinary garden soil’ of the Marsh Botanic Garden.1

Long-term monitoring of SIDD Type IV installations

An evaluation of the standard installation direct design (SIDD) prediction method has been undertaken by constructing and monitoring full-scale test beds installed according to SIDD Type IV specifications at four test sites across southern Ontario, Canada. Stresses around the test beds were monitored over a period of 20 months. The internal diameter of the test pipe segments varied from 600 mm to 900 mm; in situ soil conditions ranged from organic clay to sand, and burial depths varied from 1.5 to 3 times the diameter of the installed pipe. All test sections were subjected to frequent heavy traffic loads, representing a worse case loading scenario. Measurements from the 20 month monitoring period were compared with predictions from Ontario Provincial Standards and SIDD specifications. It was concluded that the SIDD method reasonably predicts the stress envelope around a buried rigid pipe installed using the cut-and-cover construction method. The indirect design method currently used by the Ontario Provincial Standards was found to provide an overly conservative prediction of soil stresses at the invert of the pipe. Field measurements also suggest that the value of the horizontal arching factor (HAF) currently recommended by SIDD for Type IV installations is overly conservative and can be increased while maintaining a conservative design approach.Key words: soil, pipe, interaction, rigid, SIDD, monitoring.

Study of Aerodynamical Behavior of Suspension Footbridges against Wind Load

An aerodynamical analysis of four existing light footbridges of different measures of making span of footbridges stiff enough (i.e. inclined cable system, horizontal truss, horizontal arches) is presented. A model of wind load adopted in agreement with a quasi-steady concept takes into consideration not only unsteady air onflow but also motion of the structure itself. Wind load caused by vortices is neglected. In addition, it is assumed, that considered structures behave in a linear elastic way. Flaga A. Bosak G. Michalowski T. 2 2 / ) ' ( 2 s u u q + = ρ e e e α e α α η α ξ − + − + − − + − + = * * * )] ' /( )] sin( ) cos( [ ) ' /( ) cos sin ' ( s G G s s u u Y X u u v W Theoretical approach to a problem An analysis of four existing light footbridges is made at assumptions as follows : • Wind action on pylons and cable systems of footbridges is of static-type; • Wind action on spans of footbridges is considered in accordance with a quasi-steady theory [1, 5]. • Linearised small vibrations of footbridges around their mean (static) position are considered. Quasi-steady theory enables to consider several aerodynamic phenomena, such as galloping, special type of flutter, buffeting, and divergence. Three components of wind load include static and dynamic wind actions on span footbridges. These three components of wind load, i.e. drag force, lift force and aerodynamic moment, can be given by : (1) (2) wx = q H [Cx + Cxy W] (3) wy = q H [Cy + Cyx W] (4) wm = q H [Cm + Cmm W] (5) where: ρ density of air; u, u’, v’, α, η, ξ, e – as in fig. 1; H – characteristic diameter of cross-section; XG and YG – coordinate of geometric centre of the outline curve of cros-ssection; Cx , Cxy , Cy , Cyx , Cm, Cmm – aerodynamic coe-fficients; – time averaged value; ∗ = d /dt; ’ – fluctuations; s – spatially averaged value. Fig. 1 Systems of coordinates and relations between different geometrical quantities in the case of a moving structure and an unsteady air onflow 3 EECWE, May, 2002,Kiev, Ukraine 3 Mathematical model of the htree degrees of freedom system as a substitutional system of existing structure Spans of the considered footbridges should be treated as a slender structures, which can be divided into m elements. Each of them is represented by the inner point k of the cross-section (see fig. 2). Fig. 2 A sector of span of bridge under wind load Formulas (1-5), which are related to all points of span next are transformed to the global system of coordinates. It is assumed, that the structures behave in a linear elastic way. Their motion can be described by a matrix equation : [M]{r} + [C]{r} + [K]{r}={w} (6) The Bubnow-Galerkin’s method is adopted. As a result, a system of many degrees of freedom is substituted by a representative system of three degrees of freedom. Motion of the substitutional system under wind load described by the formulas (1-6) can be expressed by : (7) {A(t)}j = [CxWK(t), CxyWK(t)ak(t), CxyWK(t)bk(t), -CxyWK(t)ck(t), CxyWK(t)dk(t), CxyWK(t)ek(t), -CxyWK(t)] (8) {A(t)}j = [CyWK(t), CyxWk(t)ak(t), CyxWk(t)bk(t), CyxWk(t)ck(t), CyxWk(t)dk(t), CyxWk(t)ek(t), CyxWk(t),] (9) {A(t)}j = [HCmWK(t), HCmmWK(t)ak(t), HCmmWK(t)bk(t), -HCmmWK(t)ck(t), HCmmWK(t)dk(t), HCmmWK(t)ek(t), -HCmmWK(t)] (10) ∑ 〉 Φ + + 〈 = = Ψ + Ψ + Ψ m k k T k j T k j T k j j j j j j j t t A t A Y t A X t K t C t M )] ( [ )} ( { )} ( { )} ( { ) ( ) ( ) ( * * *

Arching effects behind a soldier pile wall

A wall consisting of anchored steel piles with horizontal timber laggings was selected to support a 16 m deep excavation with a length of more than three kilometres near Cologne in Germany. Vertical holes were bored on the wall line, at 4 m centres, and steel piles were placed within these holes. Good contact between the piles and the surrounding soil was ensured by concreting the remaining space in the holes. In this way the earth pressure behind the wall was transferred to the piles through horizontal arching, so relieving the timber laggings. As a result, lighter timber laggings could be used and the economy of the wall construction could be increased. In situ tests as well as non-linear 3D finite element (FE) analyses were carried out. Horizontal arching was promoted by means of flexible horizontal lagging timbers and solid contact between the piles and the surrounding soil. Vertical arching was induced by high pre-stress forces in the upper ground anchors. FE analyses were based on both the elasto-plastic Mohr–Coulomb model and a more advanced hardening-soil model.

The new method of arch dam stress calculation and the application of GTSTRUDL CAE/CAD system

In this paper, a new method for arch dam stress calculation is provided. In this method, the recurrence formulation for determining the mechanical parameters in the horizontal arch is obtained by recurrence method from arch ends to arch crown where the reacting forces at the arch ends are considered as the initial parameters. Then, the equations for arch crown cantilever nodes are obtained by using the conditions of internal force equilibrium and displacement continuity. The computer program using this method saves a lot of CPU time and computer storage. The computation results for engineering problems and the comparison with finite element method from GTSTRODL software illustrate that this program is reliable and efficient.

Stress Transfer and Deformation Mechanisms around a Diaphragm Wall Panel

Practicing engineers and researchers are becoming aware of the importance of ground movements and stress changes in the ground that may occur during the construction of a diaphragm wall type of retaining walls. In this paper, the construction sequence of a typical diaphragm wall panel in stiff clay is fully simulated using a three-dimensional finite difference program. Computed results are compared with some reported results of centrifuge model tests and relevant case histories. It has been found that the influence zone due to the diaphragm wall panel installation falls within a normal distance of approximately one panel depth, D, from the face of the panel, 1/3D below from the toe and 1/3L from the edge and along the length of the panel (L). Significant horizontal stress reduction behind the center of the panel is attributed to both the downward load transfer and the horizontal arching mechanisms. A settlement bowl appears behind the panel. The maximum settlement occurs at a distance of about 0.2D behind...

Harmonic thermal fracture of multiple crack system and the stability of cracks in RCC arch dam

This work is concerned with formulating the harmonic state linear thermoelastic problem for bodies with finite dimension and multiple cracks. The fundamental solutions for temperature and stress fields caused by a point harmonic heat source in an infinite plane are presented. The boundary integral equations are obtained by the superposition of displacements and stresses caused by the prescribing displacements/tractions and thermal disturbance in an infinite region on the site that conforms to the boundary of the finite body, and that in an infinite region with cracks subjected to the negative tractions obtained from the mechanical and thermal loadings. A numerical result is obtained for two inclined cracks in a rectangular plate. The convergency of the method is examined. As an example of engineering application, a horizontal arch with cracks in a RCC arch dam in south China is analyzed. The variations of SIF at the tip of cracks with the changes of environmental temperature and water level are given. It shows that the stress distribution in the arch can be improved by artificial short joints located upstream of the abutment, and the water pressure should be kept constant during February-April for the consideration of stability of cracks.

Anatomical Relationship between the Renal Venous Arrangement and the Kidney Collecting System

The anatomical relationships between the renal venous arrangement and the pelviocaliceal system were studied in 52, 3-dimensional polyester resin corrosion endocasts. In 53.8% of the cases, there were 3 large venous trunks and in 28.8% there were 2 venous trunks joining to form the main renal vein. Intrarenal veins demonstrated free anastomoses that were disposed in 3 systems of longitudinal arcades (stellate, arcuate and interlobar veins). There were large venous collars around caliceal necks and also horizontal arches crossing over calices to link anterior and posterior veins. In 84.6% of the cases the upper caliceal group was encircled anteriorly and posteriorly by venous plexuses, which coursed parallel to the infundibulum. In 50.0% of the cases the lower caliceal group also was enriched by 2 venous plexuses. A close relationship existed between a large inferior tributary of the renal vein and the anterior aspect of the ureteropelvic junction in 40.4% of the cases. In 69.2% of the cases there was a posterior (retropelvic) vein: in 48.1% this vein had a close relationship to the junction of the pelvis with the upper calix and in 21.1% it crossed the middle posterior surface of the renal pelvis. (J. Urol., 144: 1089–1093, 1990)

Horizontal Configuration and the Rate of Erosion of Niagara Falls

The rate of regression of the Horseshoe Falls of Niagara River in the Upper Great Gorge, the upstream portion of the Niagara Canyon, appears to have been quite variable. Historically, comparison of the surveys from 1842 to 1966 shows recession rates that are faster when the Horseshoe has a well-defined horizontal notch in the crest and slower when the crest is in the form of a horizontal arch. Examination of waterfalls in central New York State shows that plunge pools are generally deeper where the horizontal configuration of the crest of the waterfall is an arch. The horizontal arch is thus shown to be the more stable configuration. Soundings by the Canadian Government in the Maid of the Mist Pool in the Upper Great Gorge reveal the river bottom to be a series of basins—plunge pools—which are progressively lower in elevation in an upstream direction. The basins are separated by highs which likewise decrease in elevation upstream. The basins are interpreted as places where the Falls stood for a long time with a horizontal arch configuration in which the stresses were relatively low. The highs are interpreted as places where horizontal notches developed in the crest with resulting relatively higher stresses and faster recession. Photoelastic comparison of the notched crest of 1819 with the arched crest of 1966 indicates that the stresses in the notched crest are about three times those in the arched crest. The soundings reveal a narrow trough in the river bottom opposite the Prospect Point side of the American Falls. This trough is interpreted as a relict notched crest, during the formation of which the canyon wall near Prospect Point was subjected to much greater stress than during the formation of the arched crest of the Horseshoe Falls near the Goat Island side of the American Falls. The much greater amount of fracturing of the rock in the American Falls near Prospect Point than near Goat Island substantiates this interpretation.

On the Noetzlis-Theory Requirement for Deflections Equalization between the two Systems of horizontal Arch and vertical Cantilever of an Arch Dam

On the Noetzlis-Theory Requirement for Deflections Equalization between the two Systems of horizontal Arch and vertical Cantilever of an Arch Dam

EFFECT OF DEFORMATION ON FOUNDATION ON THE STRESS IN ARCH DAM

In the present paper the effect of the error in estimating EC/ER when an arch dam is designed, on the stress in and the deflection of the arch dam is analitically studied two dimensionally and three dimensionally. It is explained that the thinner the arch dam is and the larger its center angle is, the less effect of the foundation deformation and it has an excellent characteristic from the stand point of the stress in the dam body, and further it has been made clear that the difference in the condition of boundary deformation does not so much affect the horizontal arch stress, but greatly affects the vertical stress of the arch, and that if the EC/ER becomes larger, the vertical tensile strength at the upstream base which is generally problematical in relation to the allowable tensile stress, becomes smaller. The clever action of the dam stress adjustment derived from the statical indetermin-ability of high degree which is intrinsically held in the arch dam, is quantitatively discussed and a convenient numerical table is presented. The effect of consolidation grout on the dam body stress is also discussed to a certain extent.

Arch Dams: The Reno Di Lei Double - Curvature Arch Dam

Design by trial-load method of unusual dam; center lines of horizontal arches shaped to approximately coincide with funicular curves of arch loads; design is not yet complete and will be verified by model studies.

Analysis of Arch Dams by the Trial Load Method

This paper presents a method of arch dam analysis that has been gradually developed in the Designing Office of the United States Bureau of Reclamation. It has also been used by the Salt River Valley Water Users Association, the Middle Rio Grande Conservancy District, and by one of the writers for a high arch dam in Mexico. It is base d on the assumption that an arch dam is composed of systems of horizontal arches and vertical cantilevers, that each system carries a proportion of the total load, and that the deflections of the two systems are equal.The method consists in applying a series of assumed proportional loads to each system and computing their deflections. When a proportionate loading has been found that gives equal deflections at all points for both systems, the stresses are computed and are considered to be those which will obtain in the dam.The mathematical treatment of the problem has been gradually developed and improved. The final form is given in the Appendix. If applied to the earlier designs, the numerical results would be slightly different, but the stresses and the shape of the loads would not be greatly changed.