Search results for "Boom"
showing 10 items of 45 documents
Novel concept for stabilising a hydraulic circuit containing counterbalance valve and pressure compensated flow supply
2016
In this paper, a novel concept for stabilising a hydraulic system containing a counterbalance valve and a pressure compensated flow supply is presented. The concept utilizes a secondary circuit where a low-pass filtered value of the load pressure is generated and fed back to the compensator of the flow supply valve. The novel concept has been investigated theoretically and experimentally. A linear model has been developed to verify the improved stability conditions. The novel concept has been implemented on a single boom actuated by a cylinder. The results show that the pressure oscillations in an otherwise unstable system can be suppressed with the novel concept. This happens without any c…
A model for torque losses in variable displacement axial piston motors
2018
This paper includes a comparison of earlier presented models for torque losses in hydraulic motors and several proposed models that all rely on data typically available for a system engineer. The new models and the old ones are compared. The new models are all based on a model developed by Jeong 2007 with an expansion that include variable displacement. All of the new models yield very good accuracy down to approximately 50% of maximum displacement and down to approximately 15% of maximum speed. In these operational ranges the deviation in torque is less than 1%. The main purpose of the new models is to facilitate simulations of hydraulically actuated winches with a balance between accuracy…
Powered by assemblage : language for multiplicity
2021
Abstract Assemblage is one way to examine complexities in today’s world. In Deleuzian thinking, assemblage refers to both the act of assembling diverse elements and the arrangements of these elements for a specific purpose. Importantly, it is the interaction between elements that allows the assemblage to become more than the sum of its parts. Applying this concept to long-term research on Cold Rush – the transformation of the Arctic commons into commodities – I argue that examining the boom, bust, and buzz around the commons can be fruitfully conceptualised and studied with assemblage. This approach brings with it an ontological shift from binaries into multiplicities and multiple temporali…
Media portrayals of transitions from work to retirement in two ageing societies : the case of ageing baby boomers in Japan and Finland
2021
This article explores media portrayals of the transition from work to retirement under the circumstances of demographic change through a focus on newspaper discussions about ageing baby boomers in Japan and Finland. Due to their shared characteristics as a distinct population group that advances the rapid ageing of the population, media representations of Japanese and Finnish baby boomers during the transitional period to retirement give insight into the social perceptions of retirement and their implications on later life. Manifest content analysis and subsequent thematic analysis identify that the topic of “work, retirement and pension” dominates media discussions in both countries. Analy…
Application of Model Predictive Control in Discrete Displacement Cylinders to Drive a Knuckle Boom Crane
2018
In this paper, two Discrete Displacement Cylinders (DDCs) are used to drive the boom of a knuckle boom crane. DDCs operate by connecting one of several available pressure levels to each chamber in order to produce different forces. A trade-off exists with such systems, between the accuracy of tracking and energy dissipation due to switching. A popular way to approach this problem is a Force Shifting Algorithm (FSA). However, in this paper, the trade-off is managed by use of a Model Predictive Control (MPC) algorithm. The tracking accuracy and energy efficiency of the MPC and FSA strategies for DDCs are compared to a PID strategy for standard cylinders. The comparison is obtained by use of a…
Development of Point-to-Point Path Control in Actuator Space for Hydraulic Knuckle Boom Crane
2020
This paper presents a novel method for point-to-point path control for a hydraulic knuckle boom crane. The developed path control algorithm differs from previous solutions by operating in the actuator space instead of the joint space or Cartesian space of the crane. By operating in actuator space, almost all the parameters and constraints of the system become either linear or constant, which greatly reduces the complexity of both the control algorithm and path generator. For a given starting point and endpoint, the motion for each actuator is minimized compared to other methods. This ensures that any change in direction of motion is avoided, thereby greatly minimizing fatigue, jerky motion,…
Model Based Design Optimization of Operational Reliability in Offshore Boom Cranes
2013
AbstractThis paper presents a model based approach for design of reliable electro-hydraulic motion control systems for offshore material handling cranes. The approach targets the system engineer and is based on steady-state computations, dynamic time domain simulation and numerical optimization.In general, the modelling takes into account the limited access to component data normally encountered by engineers working with system design. A system model is presented which includes the most important characteristics of both mechanical system and hydraulic components such as the directional control valve and the counterbalance valve.The model is used to optimize the performance of an initial des…
Analysis of Offshore Knuckle Boom Crane - Part Two: Motion Control
2013
In this paper design of electro-hydraulic motion control systems for offshore knuckle boom cranes is discussed. The influence of the control valve bandwidth along with the ramp time for the control signal are investigated both analytically with simplified system models and numerically with an experimentally verified crane model. The results of both types of investigations are related to general design rules for selection of control valves and ramp times and the relevance of these design rules is discussed. Generally, they are useful but may be too conservative for offshore knuckle boom cranes. However, as demonstrated in the paper, the only proper way to determine this is to evaluate the mo…
Literaturas nacionales y literaturas nacionalizadas. Consideraciones en torno a la recepción del boom hispanoamericano en España / National Literatur…
2017
Resumen: Este artículo reflexiona en torno a la noción de literatura nacional a partir de la relación recepción que los escritores latinoamericanos del boom tuvieron en el campo literario español. ¿Cómo dar cuenta, a la hora de estudiar el proceso de la vida literaria nacional, de la presencia de textos literarios “extranjeros” que circulan ampliamente y sin necesidad de que medie traducción alguna? Para dar cuenta de las dificultades y contradicciones de esa relación se propone el concepto de literatura nacionalizada, poniendo el énfasis en los procesos de ‘nacionalización’ que tienen lugar en un campo literario específico.Palabras clave: Boom, Latinoamérica, España, literatura nacional, …
Ciudades creativas y pueblos con encanto: los nuevos procesos patrimoniales del siglo XXI
2017
Durante las últimas décadas hemos asistido a un crecimiento espectacular del fenómeno patrimonial. La eclosión patrimonial, entre otras cosas, puede ser leída como una cara más del tercer espíritu del capitalismo. El desembarco de la economía de los intangibles y el acento en la producción del valor de lo inmaterial ha cambiado las reglas del juego de la economía mundial. Nuestra hipótesis de partida es que hemos asistido a una importante transformación en las activaciones patrimoniales: del nacionalismo político, que impulsó el patrimonio colectivo en el XIX, hemos pasado al nacionalismo de consumo en el siglo XXI. En este contexto, este artículo analiza el distinto impacto que tienen los …