End Sections Research Articles

Investigation of the Energy Efficiency and CO2 Emission Characteristics of Pre-stressed Composite Beams

In this work, the energy efficiency and CO2 emission characteristics of a pre-stressed steel-framed reinforced concrete composite beam were investigated for application in high rise apartment buildings. The beam consisted of pre-cast and cast-in-place concrete with a structural T at the end section of the pre-cast concrete. As a result, CO2 emissions were significantly reduced by decreasing the quantity of steel. The composite beams were tested which demonstrated acceptable structural performance as flexural members. The measured flexible strengths of the pre-stressed composite beams were compared with the calculated flexural strengths based on the strain compatibility approach in the yield limit state and maximum load limit state. Good agreement between the experimental and analytical flexural capacities was observed. The application of the pre-stressed composite beams capable of enhancing energy efficiencies while decreasing CO2 emissions could provide a safe structure for a comfortable built environment and will be of great benefits to the welfare of a community as well. This work demonstrates that reduced CO2 emissions can be achieved by introducing pre-stressing in a concrete composite beam and by installing a structural T only at the end of the composite beam.

Relative abundance and reproductive tactics of a Loricariidae species at Saraiva Lagoon, Ilha Grande National Park, MS-PR, Brazil

This study aimed to evaluate population abundance patterns and the main events in the reproductive cycle of Loricariichthys platymetopon at Saraiva Lagoon, Ilha Grande National Park, MS-PR, Brazil. Monthly samplings were conducted from October 2004 to September 2005 in three sections of the lagoon: entrance, middle and end, which resulted in the capture of 175 individuals. Spatial and temporal variation in abundance was obtained through CPUE (number of captured individuals/1000 m² of gillnets in 12 hours). The reproductive tactics considered were: duration, time and location of spawning, oocyte diameter and fecundity. The highest relative abundance was recorded in February, in the middle section of the lagoon, and the reproductive period lasted from September to February. The prevalence of females with spent ovaries and at rest in the following months indicated that reproductive activity ceased during autumn and winter. We observed that reproduction was high at the end section of the lagoon. The recorded mean oocyte diameter was 1.67 (SD ± 0.76) mm, mean absolute fecundity was 962.1 (SD ± 382.48) oocytes, and relative fecundity was 7.60 (SD ± 2.25) oocytes/g and 5.13 (SD ± 0.75) oocytes/cm. These tactics, probably are related to the settlement of L. platymetopom in Saraiva Lagoon, as well as in the different biotopes of the Upper Paraná River floodplain.

Buckling of a composite cantilever circular cylindrical shell subjected to uniform external lateral pressure

In this paper a solution is presented for a buckling problem formulated for the cantilever circular cylindrical composite shell subjected to uniform external lateral pressure. The edge of the shell is fully clamped at one end of the cylinder and is free at the open section of the other end. An analytical formula for critical pressure has been derived using the generalised Galerkin method. The approach is illustrated by the buckling analyses of composite, orthotropic and isotropic shells. The results are verified using the finite-element method. It has been shown that the analytical solution provides an accurate estimate of the critical load and does not involve any computationally expensive procedures. This is particularly useful in the design optimisation of composite structures.

Finding an efficient shape for the cross section of the front end of a tubular semifinished product to perform drawing

Pipe plants use radial forging to reduce the diameter of shafts, tubes, and axles. A three-dimensional finite-element method employing the software DEFORM-3D is used to optimize the radial forging operation. Three different tool configurations are examined for obtaining smooth and folded reduced semifinished products, and suggestions are made for an efficient shape for the tubular semifinished product prior to drawing, the design of the dies, and the configuration of the tool.

Moment modification factor of I-girder with trapezoidal-web-corrugations considering concentrated load height effects

Moment modification factors of the I-girder with trapezoidal web corrugations subjected to concentrated load, applied at different heights on the cross section and various end restraint conditions, are investigated. The moment modification factors are obtained by finite element buckling analyses. The new FEM program is developed by using beam elements and new general formulas of cross-section properties as well as a new warping constant of the I-girder with trapezoidal web corrugations. The theoretical results of moment modification factors are compared with commercial finite element software (ABAQUS) using shell elements. A series of finite element analyses with different corrugation profiles and lengths is performed. Through comparative numerical studies, the theoretical results are successfully verified. The moment modification factors from the SSRC Guide are compared with present FEM results. The new values of the variable C b , the moment modification factor, in the SSRC Guide are proposed as the variable C b,c to improve the accuracy of lateral–torsional buckling strength.

An Indicator for National Systems of Innovation: Methodology and Application to 17 Industrialized Countries

We develop a composite indicator measuring the performance of national innovation systems. The indicator takes into account both hard factors that are quantifiable (such as R&D spending, number of patents) and soft factors like the assessment of preconditions for innovation by managers. We apply the methodology to a set of 17 industrialized countries on a yearly basis between 2007 and 2009. The indicator combines results from public opinion surveys on the process of change, social capital, trust and science and technology to achieve an assessment of a country's social climate for innovation. After calculating and ranking the innovation indicator scores for the 17 countries, we group them into three classes: innovation leader, middle group and end section. Using multiple sensitivity analysis approaches, we show that the indicator reacts robustly to different weights within these country groups. While leading countries like Switzerland, the USA and the Nordic countries have an innovation system with high scores and ranks in every sub indicator, the middle group consisting among others of Germany Japan, the UK and France, can be characterized by higher variation within ranks. In the end section, countries like Italy and Spain have bad scores for almost all indicators.

Effects of near‐fault ground motions on the nonlinear dynamic response of base‐isolated r.c. framed buildings

SUMMARYNear‐fault ground motions are characterized by long‐period horizontal pulses and high values of the ratio between the peak value of the vertical acceleration, PGAV, and the analogous value of the horizontal acceleration, PGAH, which can become critical for base‐isolated (BI) structures. The objective of the present work is to check the effectiveness of the base isolation of framed buildings when using High‐Damping‐Rubber Bearings (HDRBs), taking into consideration the combined effects of the horizontal and vertical components of near‐fault ground motions. To this end, a numerical investigation is carried out with reference to BI reinforced concrete buildings designed according to the European seismic code (Eurocode 8). The design of the test structures is carried out in a high‐risk region considering (besides the gravity loads) the horizontal seismic loads acting alone or in combination with the vertical ones and assuming different values of the ratio between the vertical and horizontal stiffnesses of the HDRBs. The nonlinear seismic analysis is performed using a step‐by‐step procedure based on a two‐parameter implicit integration scheme and an initial‐stress‐like iterative procedure. At each step of the analysis, plastic conditions are checked at the potential critical sections of the girders (i.e. end sections of the sub‐elements in which a girder is discretized) and columns (i.e. end sections), where a bilinear moment–curvature law is adopted; the effect of the axial load on the ultimate bending moment (M‐N interaction) of the columns is also taken into account. The response of an HDRB is simulated by a model with variable stiffness properties in the horizontal and vertical directions, depending on the axial force and lateral deformation, and linear viscous damping. Copyright © 2011 John Wiley & Sons, Ltd.

Differential morphological features of two Dendronephthya soft coral species suggest differences in feeding niches

Octocorals are characterized by pinnate tentacles and internal sclerites. Their feeding ability is determined by the morphological features of the polyps. Capture of their food by these corals is also affected by the flexibility of the colony, which in turn is determined by the features of the sclerites. We studied the morphological features of two azooxanthellate octocorals, Dendronephthya hemprichi and D. sinaiensis, whose depth distribution partially overlaps at Eilat (northern Red Sea). Following Gause’s Law, such coexistence is considered to be possible if each species is adapted to utilize different food items. In order to examine this Law, the features of the polyps of the two species and their sclerites were studied. Each side of their tentacles displays 11–13 pinnules, which are longer at the tentacles’ distal end compared to its median section and proximal end, with the distal pinnules of D. sinaiensis being longer than those of D. hemprichi. At the proximal end of the tentacles of D. sinaiensis, the pinnules emerge perpendicularly, unlike in D. hemprichi, where they emerge from the lateral sides; the distance between the rows of pinnules is, therefore, shorter for the former. These findings imply that the filtered phytoplankton by the two species may differ in size. Their sclerites also differ in size and shape, and therefore the expansion and contraction abilities of their polyps also differ, and may thus affect their respective feeding abilities. The findings indicate that D. hemprichi and D. sinaiensis are adapted to utilize different food items, and therefore support Gause’s Law and explain the coexistence of the two species.

일정체적을 갖는 포물선형 중공 보-기둥의 자유진동 해석

This paper deals with free vibrations of the parabolic hollowed beam-columns with constant volume. The cross sections of beam-column taper are the hollowed regular polygons whose depths are varied with the parabolic functional fashion. Volumes of the objective beam-columns are always held constant regardless given geometrical conditions. Ordinary differential equation governing free vibrations of such beam-columns are derived and solved numerically for determining the natural frequencies. In the numerical examples, hinged-hinged, hinged-clamped and clamped-clamped end constraints are considered. As the numerical results, the relationships between non-dimensional frequency parameters and various beam-column parameters such as end constraints, side number, section ratio, thickness ratio and axial load are reported in tables and figures.

UHF센서를 이용한 가스절연송전선로 절연파괴 위치 추정에 관한 연구

This paper deals with the method and algorithm used to find fault locations in gas insulated transmission line. The method uses UHF sensors and digital oscilloscope to detect discharge signals emitted to the outside through insulating spacer in the event of breakdown inside GIL. UHF sensors are the external type and installed at outside of insulating spacers of GIL. And we used wavelet signal processing to analyze the discharge signals and confirm the exact fault location findings in the GIL test line.BR This method can overcome demerit of TDR(Time Domain Reflectometer) method having been applied to detect fault location for conventional underground transmission lines, and Ground Fault Sensors used in conventional GIS systems. TDR method requires high level of specialty and experience in analyzing the measured signals. Ground fault sensors are installed inside GIL and can be destroyed by high transient voltage.BR This paper’s method can simplify the fault location process and minimize the damage of sensors. In addition, this method can estimate the fault location only by the time difference when discharge signals are arrived to detecting sensors at the ends of GIL sections without reasons of breakdown.BR To test the performance of our method, we installed sensors at the ends of test line of GIL(84m) and sensed discharge signals occurred in GIL, energized with AC voltage generator up to 700㎸.

Simple two‐strip monopole with a parasitic shorted strip for internal eight‐band LTE/WWAN laptop computer antenna

AbstractA dual‐wideband internal antenna formed by a simple two‐strip monopole (a longer strip and a shorter strip) and a parasitic shorted strip for eight‐band long tern evolution/wireless wide area network operation (698–960/1710–2690 MHz) in the laptop computer is presented.The parasitic shorted strip is excited capacitively by the shorter strip of the two‐strip monopole and contributes two resonant modes to the antenna, with one in the lower band and one in the upper band, thereby effectively widening the bandwidths of the antenna's two operating bands. Further, the parasitic strip short‐circuited to the top shielding metal wall of the display ground in the laptop computer is configured such that its end section with the shorting point is positioned at the side edge of the antenna. This configuration allows the antenna to be placed closely to a nearby grounded plate, with very small effects on the performances of the antenna. This is an advantage for the proposed antenna in practical applications since the antenna requires a very small isolation distance at its side edge to nearby metal objects (such as a metal screw at the top shielding metal wall to fix the display ground to the casing of the laptop computer). Hence, in addition to the small antenna volume of 4 × 12 × 70 mm3 at the top shielding metal wall, compact integration of the proposed antenna along the shielding metal wall of the display ground can also be obtained. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:706–712, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25836

Phytohormone Changes and Carbohydrate Status in Sweet Orange Fruit from Huanglongbing-infected Trees

Huanglongbing (HLB) infection alters citrus fruit growth and development, resulting in small, misshapen, and poorly colored fruit containing aborted or partially developed seeds. Typically, symptomatic fruit have delayed maturation and abscise prematurely. We studied carbohy- drate and phytohormone changes in HLB-affected fruit to explain symptom development because (1) carbohydrate shortage has been linked to fruit growth arrest and eventually abscission and (2) hormonal signals regulate, at least par- tially, fruit set and development. Symptomatic fruit (S), asymptomatic fruit (AS) from symptomatic trees, and healthy fruit (H) from asymptomatic trees were harvested from 'Valencia' sweet orange trees (Citrus sinensis (L.) Osbeck) infected with the HLB pathogen or not, as verified by PCR. Mature S weighed less, had lower Brix, were smaller, had more aborted seeds, and were greener than AS or H. Starch and sucrose contents were lower in mature S flavedo compared with that of H and AS. S and AS harvested 7 and 12 months after full bloom produced significantly less ethylene than H. Indole-3-acetic acid (IAA) and abscisic acid (ABA) contents in flavedo removed from the stylar end, middle section, or stem end of fruit generally were higher in S flavedo than in AS and H. ABA content was fourfold higher in flavedo from the middle section of S than in AS and H. Flavedo excised from the large shoulder of misshapen S had significantly higher IAA content when compared with the normal-sized area of the same fruit on the opposite side. This increase corresponded to an increase in hypodermal cell area in S flavedo. Overall, these data reveal an imbalance of carbohydrate and phytohormone status in fruit from HLB- infected trees and suggest a role of such changes in fruit symptom development.

Forgeability and Machinability of Stir Cast Aluminum Alloy Metal Matrix Composites

In the present paper, the aluminum alloy i.e. LM6 based composites reinforced with different weight fraction of SiC particles was produced by stir cast technique and the effect of reinforced ratios on the forgeability and the machinability was examined. The test results show that the increment in weight fraction of reinforcement particles in the matrix metal produced better mechanical property like hardness but the forgeability of the cast MMCs decreases. The forgeability of the as cast MMCs were also varied with the change in thickness of the casting. The results show that the forgeability of cast metal matrix composites at the mid section of the casting is minimum compared to both end section of a three-step casting. The effect of machining parameters, e.g. cutting speed and depth of cut on the surface roughness and cutting forces at constant feed rate was investigated during experimentation. The results show that higher weight percentage of SiCp reinforcement produced a higher surface roughness and needs higher cutting forces during machining operation. It has also observed that the depth of cut and the cutting speed at constant feed rate affected the surface roughness and the cutting forces. This practical research analysis and test results on the forgeability and machinability of Al/SiC-MMC will provide useful guidelines to the present day manufacturing engineers.

Shears of helical reinforcement in the deformed composite

The solution of the problem, relating to the reinforcement shear and matrix of the composite is associated with the problem of its mechanical resistance, strength and stability. The interest to the spiral reinforcement is determined by using of its geometric peculiarities in order to minimize as regards to the shear in the loaded composite. We present a model problem of bending of a cylindrical rod with a screw armature. It is shown that the length step of the spiral reinforcement and the axial length of the deformation zone of the rod determine the critical shears values: in case of the multiplicity of the length of the deformation zone and the propeller pitch the shears in the end sections of the deformation zone are absent. We also show that there exists a critical length of the deformation zone, for which the maximum shears are realized. The problem is generalized for the case of armoring by a finite family of left-hand screw fittings. The results of work are used in designing of special aseismic composite supports, as well as structural design of electrical and optical cables.

The small free oscillations of a strip

The refined equations of the free oscillations of a rod-strip, constructed previously in a first approximation by reducing the two-dimensional equations to one-dimensional equations by using trigonometric basis functions and satisfying the static boundary conditions on the boundary surfaces are analysed. These equations, the solutions of which are obtained for the case of hinge-supported end sections of the rod, are split into two independent systems of equations. The first of these describe non-classical fixed longitudinal-transverse forms of free oscillations, which are accompanied by a distortion of the plane form of the cross section. It is shown that the oscillation frequencies corresponding to them depend considerably on Poisson's ratio and the modulus of elasticity in the transverse direction, while for a rod of average thickness for the same value of the frequency parameter (the tone) they may be considerably lower than the frequencies corresponding to the classical longitudinal forms of free oscillations, which are performed while preserving the plane form of the cross sections. The second system of equations describes transverse flexural-shear forms of free oscillations, whose frequencies decrease as the transverse shear modulus decreases. They are practically equivalent in quality and content to the similar equations of well-known versions of the refined theories, but, unlike them, when the number of the tone increases and the relative thickness parameter decreases they lead to the solutions of the classical theory of rods.

Post-buckling behaviour and strength of cold-formed steel lipped channel columns experiencing distortional/global interaction

This paper reports the results of a numerical investigation concerning the elastic and elastic–plastic post-buckling behaviour of cold-formed steel lipped channel columns affected by distortional/global (flexural–torsional) buckling mode interaction. The results presented and discussed were obtained by means of analyses performed using the finite element code Abaqus and adopting column discretisations into fine 4-node isoparametric shell element meshes. The columns analysed (i) are simply supported (locally/globally pinned end sections that may warp freely), (ii) have cross-section dimensions and lengths that ensure equal distortional and global (flexural–torsional) critical buckling loads, thus maximising the distortional/global mode interaction effects, and (iii) contain critical-mode initial geometrical imperfections exhibiting different configurations, all corresponding to linear combinations of the two “competing” critical buckling modes. After briefly addressing the lipped channel column “pure” distortional and global post-buckling behaviours, one presents and discusses in great detail a fair number of numerical results concerning the post-buckling behaviour and strength of similar columns experiencing strong distortional/global mode interaction effects. These results consist of (i) elastic (mostly) and elastic–plastic non-linear equilibrium paths, (ii) curves or figures providing the evolution of the deformed configurations of several columns (expressed as linear combination of their distortional and global components) and, for the elastic–plastic columns, (iii) figures enabling a clear visualisation of (iii1) the location and growth of the plastic strains and (iii2) the characteristics of the failure mechanisms more often detected in the course of this research work.

알루미늄 판재의 압출전단접합에 관한 연구

Abstract It was investigated that two plates of aluminum can be welded by hot extru-shear welding process with extru-shear welding dies, and that the welding strength and metal flow on the welding section were analyzed by computer simulation according to the welding variables such as inclined angle of cutter and overlapped length of plates and temperature of plates. It was known by computer simulation that welding strength on the welding section of plates could be influenced by the inclined angle of cutter and overlapped length of plates and temperature of plates. And it was known by experiments that two plates of aluminum can be welded on the end sections by hot extru-shear welding process using extru-shear welding dies, and that welding strength is the highest when inclined angle of dies is 70 o , and overlapped length is 1.2 mm, and temperature is 520 o , when aluminum 5052 two plates with 1.6 mm thickness are used as welding material. Key Words : Extru-Shear Welding(ESW), Extru-Rivet Welding(ERW), Pressure Welding, Friction Stir Welding, Welding Dies, Aluminum Plate

Study on the Inner Helical Gear Form Grinding Wheel Dressing Technology

Based on the gear meshing theory, the mathematical model of inner helical gear form grinding is established. In order to get rid of the grinding interference, numerical simulation is used to optimize the diameter of grinding wheel and its installation angle. The wheel profile obtained by means of numerical simulation is transformed into the end section of tooth firstly, and then compared with the theoretical involute tooth. Substitute the optimized diameter of grinding wheel and its installation angle into meshing equation, the wheel profile can be obtained by solving meshing equation with Newton iteration method. Wheel dressing and simulating analysis software are prepared based on VC++6.0.

Design Optimization of an Automobile Connecting Rod Using FEM

Abstract In automotive engines, the connecting rod is subjected to high cyclic loads. These are represented by high compressive loads due to combustion, and high tensile loads due to the connecting rod mass of inertia. The main objective of this study is to optimize the shape of a connecting rod in an automobile engine. A model of the connecting rod has numerically been built and has been solved by the Finite Element Method (FEM) using the ANSYS package to determine the stresses distribution over the entire rod. In addition, the transition force analysis of the connecting rod and the verification of the analysis are shown. The aim of the optimization has been to minimize the respective Von Mises stresses which occur at connected rod in both cases, i. e. compressive loads coming from the gas pressure at maximum engine output and the bending loads resulting from the inertia force at the maximum engine power. The weight of the connecting rod should be maintained to prevent increasing of the inertia force. The results of this study indicate that the maximum compression stress occur at compressing loads at the small end section of the connecting rod. Optimizing the radius at the small end decreases such stresses. On the other hand, the inertia forces of the connecting rod mass cause a maximum bending stress at the large end section. By changing the shape and geometry of this section the maximum Von Mises stresses are reduced by 16.5 %, as compared to the original design. A buckling analysis has been carried out for the original and the optimized model and the results have been compared. The load factor (critical load / applied load) is increased by 7 % compared to the original design. Finally, a shape optimization for connecting rod reduces the stresses over the entire rod.

An Alternative Isovelocity Surface Model for Quantitation of Effective Regurgitant Orifice Area in Mitral Regurgitation With an Elongated Orifice: Application to Functional Mitral Regurgitation

The purpose of this study was to develop and test a simple, clinically practical alternative isovelocity surface (ISVS) model for calculating effective regurgitant orifice area (EROA) in mitral regurgitation (MR) when the regurgitant orifice is elongated, such as in functional MR. Clinical experience and 3-dimensional imaging suggest that the traditional hemispheric ISVS model used in the conventional proximal isovelocity surface area (PISA) calculation is invalid in certain MR cases and can cause erroneous EROA values. Our ISVS model consisted of 3 sections of equal radius (R): a cylindrical midsection of length (L) positioned between 2 hemispheroidal end sections. Total ISVS area (T(S)) is equal to 2πR(2) + πLR and EROA is equal to (V(N/)V(CW))T(S), where V(N) is the flow velocity crossing perpendicular to the ISVS, and V(CW) is the peak MR jet velocity by continuous-wave Doppler. This EROA was corrected for any obtuse angle, θ formed by tented leaflets, by multiplying T(S) by a planar factor, (θ/180) or a combination of this planar factor for the cylindrical midsection and the solid-angle factor, 1-cos(θ/2), for the 2 spheroidal end sections. In 24 cases of severe or 3+ functional MR, we calculated EROA using 3 traditional hemispheric surfaces and 3 alternative ISVS models that differed in the leaflet angle correction applied. Results were compared with continuity-based EROA using the standard mitral valve - aortic valve stroke volume method and with predictions based upon theoretical geometric considerations. The mean differences between continuity EROA and ISVS area-based EROA for no angle correction, planar correction, or combined angle correction were, respectively, 0.38, 0.32, and 0.28 cm(2) for the 3 spherical surface models and 0.17, 0.018, and -0.012 cm(2) for the 3 alternative 3-section ISVS models. The empiric EROA results with both the traditional spherical and alternative ISVS models agreed well with theoretical geometric predictions. The traditional spherical PISA model underestimates EROA in functional MR. For elongated MR orifices, an ISVS model that mirrors orifice shape yields more accurate EROA values. Correction to the ISVS area for obtuse leaflet angulation improves accuracy of EROA estimation.