Distribution Of Specific Load Research Articles

Structural design of responsive under-deck cable-stayed footbridges

The use of prestressing through external tendons has been extensively adopted in bridges to optimize the internal stress distribution. The contribution in withstanding permanent and live loads depends on the initial stressing and the relative stiffness between the deck and the tendons. However, these configurations only allow an optimal structural behaviour for a specific load distribution. This paper proposes to extend this ideal behaviour for any loading condition, using a responsive system which gradually modifies the tension in the cables as the live load increases. The responsive system is applied to a footbridge, where the adaptive behavior is materialized through a linear actuator located between the deck and the under-deck cable-stayed system.This study presents analytical and numerical analyses to shed light on the structural design of these systems. Considering a variable degree of responsiveness, it is possible to quantify the benefits of the responsive system. Furthermore, several parametric analyses are carried out to identify the optimal solution in terms of material savings. In addition, it is verified that fatigue in cables, vibrations and the eventual shutdown of the actuator do not compromise the structural performance of the system.Results show that a relevant material reduction can be achieved using partially responsive systems. Specifically, the slenderness of the structure can almost be doubled if compared to the same system without any responsive behaviour.

Short term forecasting of electrical consumption using a neural network: joint approximate diagonal eigenvalue

This article aims <span lang="EN-US">to estimate the load profiling of electricity that provides information on the electrical load demand. In achieving this research implemented the neural network algorithm of joint approximate diagonalisation of eigen-matrices (JADE) to describe the load profile pattern for each point. Nowadays, utility providers claim that natural sources are used to generate power by rising consumer demands for energy. However, occasionally utility workers need to know the demand at certain location, corresponding to maintenance issues or for any shutdown area involved.<br /> A distribution pattern based on the data can be predicted based on the incoming data profile without having detailed information of certain load bus, the concept of derivatives was relevant to forecast the types of distribution data. The model was constructed with load profile information based on three different locations, and the concept of derivative was recognized, including the type of incoming data. Historical data were captured from a selected location in Malaysia that was proposed to train the JADE algorithm from three different empirical distributions of consumers, recording every 15 minutes per day. The results were analyzed based on the error measurement and compared with the real specific load distribution feeder information of needed profiles.</span>

Експериментальні дослідження розподілу питомого завантаження суміші по площі нахиленого лотка

The regularities of specific loading distribution of loose mixture on the area of a working surface of the inclined tray are established in the work. The studies were performed on the experimental setup consisting of a storage hopper and inclined flat trays of different lengths. The material of the study was a grain mixture of winter wheat variety "Myronivska 30". The magnitude of the load was determined using a receiving device, which allowed to obtain the specific load distribution on the width and length of the tray and over time. The specific loading of the tray is uneven in the area of the working surface: the central section is overloaded, and the wall is underloaded. The largest deviations of the specific load at the inlet of the tray, but with length they decrease, approaching a uniform distribution. The specific load profile across the width of the tray is asymmetric and has a local extremum. As the tray length increases, at the certain initial speed and angle, the specific load decreases and the mixture flow slows down. With a constant supply of material from the hopper, there is a gradual accumulation of the mixture in the tray, compaction and growth of the layer, which leads to complete cessation of flow. Uneven loading of the tray occurs due to uneven supply of material from the storage hopper, in which the movement begins. The initial feed varies across the width of the tray and over time, and the nature of the specific load profile formed at the entrance to the tray is preserved for almost its entire length. The movement of the mixture flow in the inclined tray is non-stationary, the specific load varies significantly over the entire surface area and largely depends on the initial conditions of movement. The obtained regularities of specific loading on the working surface area of the tray can be used in the calculation of the modes of loose mixtures movement and substantiation of the equipment parameters for loading the working bodies of machines.

Analysis of Wind-Turbine Main Bearing Loads Due to Constant Yaw Misalignments over a 20 Years Timespan

The compact design of modern wind farms means that turbines are located in the wake over a certain amount of time. This leads to reduced power and increased loads on the turbine in the wake. Currently, research has been dedicated to reduce or avoid these effects. One approach is wake-steering, where a yaw misalignment is introduced in the upstream wind turbine. Due to the intentional misalignment of upstream turbines, their wake flow can be forced around the downstream turbines, thus increasing park energy output. Such a control scheme reduces the turbulence seen by the downstream turbine but introduces additional load variation to the turbine that is misaligned. Within the scope of this investigation, a generic multi body simulation model is simulated for various yaw misalignments. The time series of the calculated loads are combined with the wind speed distribution of a reference site over 20 years to investigate the effects of yaw misalignments on the turbines main bearing loads. It is shown that damage equivalent loads increase with yaw misalignment within the range considered. Especially the vertical in-plane force, bending and tilt moment acting on the main bearing are sensitive to yaw misalignments. Furthermore, it is found that the change of load due to yaw misalignments is not symmetrical. The results of this investigation are a primary step and can be further combined with distributions of yaw misalignments for a study regarding specific load distributions and load cycles.

Effects of eccentricity and vibration response on high-speed rigid rotor supported by hybrid foil-magnetic bearing

A hybrid foil-magnetic bearing (HFMB) consists of an air foil bearing (AFB) and an active magnetic bearing (AMB). The HFMB, inherently proposed as a backup bearing for an AMB, has many advantages, such as good controllability and the ability to exhibit preload sharing with the two types of bearings (i.e., the AFB and AMB) in high-speed turbomachinery. However, because the bearing has a limited clearance, the eccentric position of the rotor affects its stability and the reliability parameters of the AFBs such as the initial preload rub. In this study, a rigid rotor supported by an HFMB was operated at speeds of up to 18 kr/min and was tested using a proportional-derivative control algorithm, in order to reduce the vibration amplitude. In addition, to elucidate the effect of the initial eccentric position of the rotor, the control algorithm was started from the initial position of the rotor (X: from –100 to 100 µm and Y: from –80 to 200 µm) using a constant gain value. When the HFMB was active, the magnetic control force was remarkably effective in reducing the subsynchronous vibration of the rotor supported by the HFMB. Eccentricities of 0.2–0.5 corresponded to appropriate rotor positions for the hybrid bearing, and the corresponding load distribution of the AFB was found to be the optimal one. In addition, the proportional-derivative control gain was not very high. The performance of the bearing could be improved further by controlling the eccentricity. An HFMB was tested experimentally, and it was verified that it is possible to determine the effective load carrying capacity for a specific load distribution of the AFB.

Internal Force Analysis and Load Distribution for Cooperative Multi-Robot Manipulation

The load distribution strategy in cooperative manipulation tasks allocates suitable force and torque setpoints to an ensemble of manipulators in order to implement a desired action on the manipulated object. Due to the manipulator redundancy, the load distribution computed by means of a generalized inverse of the grasp matrix is not uniquely determined. Controversial results on the nonsqueezing property of specific load distributions exist in the literature. In this paper, we propose a new paradigm for the analysis of internal wrenches based on the kinematic constraints imposed to the manipulator ensemble. We unify previous results by showing that there exists no unique nonsqueezing load distribution and illustrate the consequences of our findings by means of several examples. In particular, the presented results provide a new perspective on the decomposition of interaction forces into internal and external components as required for cooperative multimanipulator control schemes.

Sensitivity of patient-specific vertebral finite element model from low dose imaging to material properties and loading conditions

Patient-specific modeling could help in predicting vertebral osteoporotic fracture. The accuracy requirement for input data available in clinical routine is related to the model sensitivity. The objective of this study is to assess the relative impact of material properties and of loading conditions on vertebral strength using a finite element model. Fourteen subject-specific vertebral finite element models were used to investigate the effect of material properties and loading conditions. A design of experiment was set to study three parameters: Young's moduli of trabecular bone and cortico-trabecular bone (outer 3mm of the vertebra), and load location. Cortico-trabecular bone modulus variation from 270 to 478MPa made fracture load vary from 22 to 51%, depending on other parameters. Trabecular bone modulus variation from 115 to 258MPa made fracture load vary from 11 to 43%. Displacing load location by 1cm resulted in a mean decrease of 48-60% of the fracture load. Anterior bending induced strain concentration in vertebral anterior wall. Material properties of both type of bone have about the same effect. Load location is the most sensitive. Effort should be made to take into account patients' specific load distribution regarding its sagittal balance, in addition to bone properties.

Load Transmission Characteristic to Ballast Layer Focused on Deformation Mode of Sleeper

In this paper, we report the experimental modal analysis as developed for the 3PR-sleeper and the dynamic response measurement in the existing track in order to clarify the transmission characteristic of a dynamic load to the ballast layer. The result shows that the sleeper vibrates in its normal mode by some frequencies with a superior response of the load at the lower side of a sleeper, in addition, the deformed shape of sleeper's normal mode cause specific load distributions at the lower side of a sleeper.

Foreland basin—a FORTRAN program to model the formation of foreland basins resulting from the flexural deflection of the lithosphere caused by a time-varying distributed load

A FORTRAN program is described that calculates the deflection of a thin elastic plate resulting from a time-varying distributed load. The program is useful for modeling the subsidence of a foreland basin where the elastic plate is the lithosphere and the distributed load is a wedge-shaped thrust sheet. The deflection is calculated for a specific load distribution, and hence at a specific time but one can prescribe various loads at different times in the loading history so that the basin subsidence history can be shown.

Wear behavior of WC-Co hard alloys in liquid nitrogen

1. A study was made of the effects of track length and load upon the wear of VK6, VK6M, and VK60M alloys. It was established experimentally that the variation of the wear as a function of these parameters is in accord with the law of abrasive wear. 2. The applicability of the law of abrasive wear to hard-alloy pairs operating in liquid nitrogen makes it possible to solve problems arising in the establishment of the relationship between the frictional surface area and the track length and in the determination of the distribution of specific load over the frictional surface.