Load Distribution Function Research Articles

Analysis and Design of Steel Bridges with Ballastless Track

Currently the modernisation of railways is in progress in a large global scale. While classic ballast is verified in the long term and quite popular, the structural solutions using more quality materials (concrete, asphalt) are more and more preferred. Therefore, the slab track system (STS) was developed that is characterized as relatively maintenance-free structure of the railway superstructure where the reinforced concrete slab accepts the load distribution function of the ballast [1-4]. In the case of bridge structures, the slab tracks are built mainly on concrete bridges where the rigid connection between the STS and the bridge deck is solved using the cross-shaped slab directly concreted on the bridge deck. Application of STS on steel bridges is rarer and therefore the design is not entirely clear. Therefore, the main purpose of this work is to analyse the possibilities of utilizations of STS on steel bridges.

Mechanical Properties Analysis for Compression Equipment of Underground Lifting Compression Processing Station

Underground lifting compression processing station is the core equipment for domestic waste disposal. Compression equipment is the elementary equipment of underground lifting compression processing station and its mechanical properties will affect on compression effect of domestic waste. In order to analyze mechanical properties of compression equipment, the garbage curved surface shape function is established base on Eggshell theory, the load distribution of domestic waste inside compression box is studied, the density and load models of compressed domestic waste are established, and the load distribution function of compressed domestic waste for underground lifting compression processing station is deduced. Base on finite element method, the mechanical properties for compression equipment of underground lifting compression processing station is studied, which provides the basis for structure lightweight design.

Effect of railway roughness on soil vibrations due to moving trains by 2.5D finite/infinite element approach

The railway irregularity and dynamic properties of the moving train is newly incorporated in the 2.5D finite/infinite element simulation of the soil vibrations caused by subway trains. For soils that are uniform along the railway, only a 2D profile of the soil perpendicular to the railway needs to be considered, of which the near field is simulated by finite elements and the far field by infinite elements. Besides the in-plane degrees of freedom (DOFs) for plane elements, an extra DOF is needed to account for the out-of-plane vibration. The train is modeled by a series of mass-spring-dashpot units moving over rails with the irregularity profile simulated as a stationary ergodic Gaussian random process. By summing up the load distribution function for each axle load moving over an infinite elastically supported beam, the wheel-rail interaction forces are obtained in the Fourier domain. The reliability of the proposed approach is verified by comparing the results obtained with the existing ones. Besides, the effect of floating slabs on the vibration isolation of railway tracks with respect to rail irregularity is also investigated. It is concluded that the velocity and acceleration responses of the soil are largely amplified due to the presence of rail irregularity, and that the high-frequency components induced by rail irregularity can be effectively reduced via installation of the floating slabs.

Nonlinear transient analysis of FGM and FML plates under blast loads by experimental and mixed FE methods

Nonlinear transient behavior of fiber–metal laminated (FML) composite plates under non-ideal blast loads are investigated by both experimental and numerical techniques. In the experiments three plates with different aspect ratios are tested under blast loads and their response is also simulated and compared with both the developed mixed finite element method and the commercial software ANSYS. Furthermore parametric numerical analyses are conducted for nonlinear transient behavior of functionally graded (FGM) thin plates under blast loads with mixed FEM. In these parametric analyses the effect of aspect ratio, load distribution and impulse function in time domain are investigated. In the developed mixed FE formulation, the von Kármán plate theory is used. Nonlinear functional is developed using the Hellinger–Reissner principle and linearized with the incremental formulation. Dynamic analyses are carried using the Newmark method with the Newton–Raphson iterations. Condensation is not performed hence time derivative of internal forces are also calculated during the solutions. Damping is incorporated to the analysis in the sense of the Rayleigh damping. As a result of conducted analyses, there is a good and reliable agreement between the numerical and the experimental results. Moreover, the developed mixed FEM results are almost identical to the ANSYS results.

인터넷 환경에서 서버간 부하 분산을 위한 새로운 웹 클러스터 기법

This paper presents a new web cluster scheme based on dispatcher which does not depend on operating system for server and can examine server`s status interactively. Two principal functions are proposed for new web cluster technique. The one is self-controlled load distribution and the other is transaction fail-safe. Self-controlled load distribution function checks response time and status of servers periodically, then it decides where the traffic goes to guarantee rapid response for every query. Transaction fail-safe function can recover lost queries including broken transaction immediately from server errors. Proposed new web cluster scheme is implemented by C language on Unix operating system and compared with legacy web cluster products. On the comparison with broadcast based web cluster, proposed new web cluster results higher performance as more traffic comes. And on the comparison with a round-robin DNS based web cluster, it results similar performance at the case of traffic processing. But when the situation of one server crashed, proposed web cluster processed traffics more reliably without lost queries. So, new web cluster scheme Proposed on this dissertation can give alternative plan about highly increasing traffics and server load due to heavy traffics to build more reliable and utilized services.

Meniscal regeneration or meniscal transplantation?

Owing to the initial necrosis to which any freely transplanted biological graft is subjected, meniscus transplantation is based on similar principles to meniscal regeneration. Both methods rely on repopulation of extrinsic cells of the graft. In the former procedure a biological matrix (meniscus, tendon, fatpad) is used as graft (scaffold), whereas in meniscal regeneration commercially available resorbable or non-resorbable scaffolds are implanted. However, the cellular (re)population and (re)vitalization process is deleterious rather than beneficial for the function of the graft as the remodelling of the tissue leads to shrinkage and narrowing of the implant. In addition, improper fixation and subsequent elongation of the anterior and posterior bony attachments leads to peripheral graft dislocation, loss of the load distribution function, and subsequently to cartilage degeneration. Hence, meniscus transplantation or regeneration faces two major problems: 1) remodelling of graft to inferior tissue properties after allograft transplantation, or lacking establishment of normal tissue properties after use of biological matrixes other than the meniscus (fatpad, tendon), or commercially available matrixes; 2) improper fixation with elongation of the anterior and posterior attachments. Furthermore, use of allografts incorporates the risk for disease transmission. Today we are unable to control these problems, and therefore the concept of meniscal replacement does not work yet. Further research is necessary to control remodelling and improve fixation to make this procedure a successful one in the future.

The menisci of the knee joint. Anatomical and functional characteristics, and a rationale for clinical treatment.

The menisci and their insertions into bone (entheses) represent a functional unit. Thanks to their firm entheses, the menisci are able to distribute loads and therefore reduce the stresses on the tibia, a function which is regarded essential for cartilage protection and prevention of osteoarthrosis. The tissue of the hypocellular meniscal body consists mainly of water and a dense elaborate type I collagen network with a predominantly circumferential alignment. The content of different collagens, proteoglycans and nonproteoglycan proteins shows significant regional variations probably reflecting functional adaptation. The meniscal horns are attached via meniscal insertional ligaments mainly to tibial bone. At the enthesis, the fibres of the insertional ligaments attach to bone via uncalcified and calcified fibrocartilages. This anatomical configuration of gradual transition from soft to hard tissue, which is identical to other ligament entheses, is certainly essential for normal mechanical function and probably protects this vulnerable transition between 2 biomechanically different tissues from failure. Clinical treatment of meniscal tears needs to be based on these special anatomical and functional characteristics. Partial meniscectomy will preserve some of the load distribution function of the meniscus only when the meniscal body enthesis entity is preserved. Repair of peripheral longitudinal tears will heal and probably preserve the load distribution function of the meniscus, whereas radial tears through the whole meniscal periphery or more central and complex tears may be induced to heal, but probably do not preserve the load distribution function. There is no proof that replacement of the meniscus with an allograft can reestablish some of the important meniscal functions, and thereby prevent or reduce the development of osteoarthrosis which is common after meniscectomy. After implantation, major problems are the remodelling of the graft to inferior structural, biochemical and mechanical properties and its insufficient fixation to bone which fails to duplicate a normal anatomical configuration and therefore a functional meniscal enthesis.

Steady-State Load Distribution of Insoluble Particles in Alveolar Macrophages

This paper describes an effort to derive, under steady-state conditions, the number and mass load distribution functions of the macrophage pool on the alveolar surface of a new, physiology-oriented compartmental kinetics model of alveolar retention of inhaled insoluble particles in rats. Quantitative relationships are derived and discussed with regard to the limitations of the mathematical approach. It appears that the results are compatible with existing experimental data obtained by bronchoalveolar lavage of rat lungs.

Large deflections of a cantilever beam subjected to a rotational distributed loading

Large deflection problems of a uniform cantilever beam under a rotational distributed loading are formulated by means of a second order nonlinear integro-differential equation. The problem is numerically solved by considering a uniform rotational distributed load and a linearly varying rotational distributed load along the span of the beam. The details of load deflection curves are presented. Assuming Dirac delta function as a load distribution function along the span of the beam, the present general formulation yields the solution for the problem of a uniform cantilever beam with end rotational concentrated load. The numerical results for this case are found to be in good agreement with existing closed form solutions. As the formulation is general, the problem with nonuniform rotational distributed load of any complexity can be solved following the present numerical procedure which is quite simple, accurate and involves less computational time.

The Inclusion of Dynamic Factors in Statistical Power System Cost Models Part II: Part Loading and Reserve Costs

For pt.I see ibid., vol.4, no.2, p.419-25 (1989). Techniques are developed for analyzing the costs of maintaining adequate operating reserver on power systems, within probabilistic production costing models and other based on load distribution functions. The aim is to show that such models can be developed to approximate the full range of dynamic penalties associated with practical power system operation. Algorithms for costing predetermined part loading are presented, taking into account the need for bringing plant online out of strict merit order. The author describes how a prediction error function can be used to estimate the probability that the specified spinning reserve is insufficient and hence approximate for the cost of gas turbine or storage utilization for dynamic control. This allows estimation of optimal reserve levels. The author discusses the analysis of longer term reserve from banked thermal units. Some results of the model are compared to those reported from hourly simulation studies. >

The inclusion of dynamic factors in statistical power system cost models. II. Part loading and reserve costs

This paper develops techniques for analysing the costs of maintaining adequate operating reserve on power systems, within probabilistic production costing models and others based upon load distribution functions. The aim is to show that such models can be developed to approximate the full range of dynamic penalties associated with practical power system operation. Algorithms for costing predetermined part loading are presented, including the need for bringing plant on-line out of strict merit order. The paper then describes how an prediction error function can be used to estimate the probability that the specified spinning reserve is insufficient, and hence approximate the cost of gas turbine or storage utilisation for dynamic control. This allows estimation of optimal reserve levels. The paper also discusses the analysis of longer term reserve from banked thermal units. Finally, some results of the model are compared with those reported from hourly simulation studies.

Large deflection of circular plate under compound load

By means of the perturbation method, this paper presents an approximate solution for large deflection of clamped circular plate under uniform pressure together with a concentrated load at the center. The special case of vanishing central deflection is also discussed. In this paper, a load distribution function is introduced so as to make the compound loads depend on a single load parameter, and average angular deflection is used as the single displacement perturbation parameter.

Tapered Cantilevers with Varying Distributed Loads

Many investigators have considered the problems of cantilever beams undergoing large deflections. Barton and Bisshopp and Drucker solved exactly a cantilever carrying a concentrated load at its free end. Hummell and Morton, Bickley, and Rhode presented an approximate treatment of a cantilever beam under uniformly distributed load. All of the above cases were for beams of constant section. Recently, Kemper solved the problems of tapered cantilevers subjected to a concentrated load at the free end by computer methods, considering both rectangular and round cross sections, and the results were checked by experimental verification. In the present note, a slender cantilever beam with a uniform taper of the rectangular cross section, carrying varying distributed loads, is considered, and the solution is obtained by the use of power series method. A general load distribution function is introduced and a set of coefficients are provide for various kinds of load distribution. Numerical results of load-deflection relationships are also presented for a cantilever with a uniformly distributed load.