6 resultados para Reactive force field
em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland
Resumo:
Yhtiössä on tehty vuoden 2005 aikana strategiaprosessi, jonka tuloksena on päätetty alueiden vähentämisestä seitsemästä neljään sekä konttoriverkoston supistamisesta. Osa yhteyspäälliköistä tulee siirtymään työpisteisiin tai kotikonttoreihin, jolloin esimiestyön haasteet kasvavat maantieteellisistä etäisyyksistä johtuen. Työn keskeisenä sisältönä ovat operatiivisen johdon toimintamallit muutosten toteuttamiseksi ja johtajiston ja esimiesten vastuunkanto yhteisistä päätöksistä. Pitkään jatkuneen stabiilin tilan jälkeen muutosten toteuttaminen on aiheuttanut paljon muutosvastarintaa, joten esimiesten toimintaa ja osaamista pyritään kehittämään muutosta tukevaksi. Työn keskeisenä tuloksena ovat muutoksen perusteet: selkeän vision, yrityskulttuurin ja asenteiden kääntäminen muutosta tukevaksi, viestinnän merkitys ja esimiesten yhteinen linja henkilöstöjohtamisessa. Aluejohdon ajankäytön muutos ja oman toiminnan muuttaminen ovat työn keskeisiä tuloksia, joilla uusia toimintamalleja voidaan viedä organisaatiossa eteenpäin.
Resumo:
The need for high performance, high precision, and energy saving in rotating machinery demands an alternative solution to traditional bearings. Because of the contactless operation principle, the rotating machines employing active magnetic bearings (AMBs) provide many advantages over the traditional ones. The advantages such as contamination-free operation, low maintenance costs, high rotational speeds, low parasitic losses, programmable stiffness and damping, and vibration insulation come at expense of high cost, and complex technical solution. All these properties make the use of AMBs appropriate primarily for specific and highly demanding applications. High performance and high precision control requires model-based control methods and accurate models of the flexible rotor. In turn, complex models lead to high-order controllers and feature considerable computational burden. Fortunately, in the last few years the advancements in signal processing devices provide new perspective on the real-time control of AMBs. The design and the real-time digital implementation of the high-order LQ controllers, which focus on fast execution times, are the subjects of this work. In particular, the control design and implementation in the field programmable gate array (FPGA) circuits are investigated. The optimal design is guided by the physical constraints of the system for selecting the optimal weighting matrices. The plant model is complemented by augmenting appropriate disturbance models. The compensation of the force-field nonlinearities is proposed for decreasing the uncertainty of the actuator. A disturbance-observer-based unbalance compensation for canceling the magnetic force vibrations or vibrations in the measured positions is presented. The theoretical studies are verified by the practical experiments utilizing a custom-built laboratory test rig. The test rig uses a prototyping control platform developed in the scope of this work. To sum up, the work makes a step in the direction of an embedded single-chip FPGA-based controller of AMBs.
Resumo:
The purpose of this dissertation is to increase the understanding and knowledge of field sales management control systems (i.e. sales managers monitoring, directing, evaluating and rewarding activities) and their potential consequences on salespeople. This topic is important because research conducted in the past has indicated that the choice of control system type can on the other hand have desirable consequences, such as high levels of motivation and performance, and on the other hand leadto harmful unintended consequences, such as opportunistic or unethical behaviors. Despite the fact that marketing and sales management control systems have been under rigorous research for over two decades, it still is at a very early stage of development, and several inconsistencies can be found in the research results. This dissertation argues that these inconsistencies are mainly derived from misspecification of the level of analysis in the past research. These different levels of analysis (i.e. strategic, tactical, and operational levels) involve very different decision-making situations regarding the control and motivation of sales force, which should be taken into consideration when conceptualizing the control. Moreover, the study of salesperson consequences of a field sales management control system is actually a cross-level phenomenon, which means that at least two levels of analysis are simultaneously involved. The results of this dissertation confirm the need to re-conceptualize the field sales management control system concept. It provides empirical evidence for the assertion that control should be conceptualized with more details atthe tactical/operational level of analysis than at the strategic levelof analysis. Moreover, the results show that some controls are more efficiently communicated to field salespeople than others. It is proposed that this difference is due to different purposes of control; some controls aredesigned for influencing salespersons' behavior (aim at motivating) whereas some controls are designed to aid decision-making (aim at providing information). According to the empirical results of this dissertation, the both types of controls have an impact to the sales force, but this impactis not as strong as expected. The results obtained in this dissertation shed some light to the nature of field sales management control systems, and their consequences on salespeopl
Resumo:
It is necessary to use highly specialized robots in ITER (International Thermonuclear Experimental Reactor) both in the manufacturing and maintenance of the reactor due to a demanding environment. The sectors of the ITER vacuum vessel (VV) require more stringent tolerances than normally expected for the size of the structure involved. VV consists of nine sectors that are to be welded together. The vacuum vessel has a toroidal chamber structure. The task of the designed robot is to carry the welding apparatus along a path with a stringent tolerance during the assembly operation. In addition to the initial vacuum vessel assembly, after a limited running period, sectors need to be replaced for repair. Mechanisms with closed-loop kinematic chains are used in the design of robots in this work. One version is a purely parallel manipulator and another is a hybrid manipulator where the parallel and serial structures are combined. Traditional industrial robots that generally have the links actuated in series are inherently not very rigid and have poor dynamic performance in high speed and high dynamic loading conditions. Compared with open chain manipulators, parallel manipulators have high stiffness, high accuracy and a high force/torque capacity in a reduced workspace. Parallel manipulators have a mechanical architecture where all of the links are connected to the base and to the end-effector of the robot. The purpose of this thesis is to develop special parallel robots for the assembly, machining and repairing of the VV of the ITER. The process of the assembly and machining of the vacuum vessel needs a special robot. By studying the structure of the vacuum vessel, two novel parallel robots were designed and built; they have six and ten degrees of freedom driven by hydraulic cylinders and electrical servo motors. Kinematic models for the proposed robots were defined and two prototypes built. Experiments for machine cutting and laser welding with the 6-DOF robot were carried out. It was demonstrated that the parallel robots are capable of holding all necessary machining tools and welding end-effectors in all positions accurately and stably inside the vacuum vessel sector. The kinematic models appeared to be complex especially in the case of the 10-DOF robot because of its redundant structure. Multibody dynamics simulations were carried out, ensuring sufficient stiffness during the robot motion. The entire design and testing processes of the robots appeared to be complex tasks due to the high specialization of the manufacturing technology needed in the ITER reactor, while the results demonstrate the applicability of the proposed solutions quite well. The results offer not only devices but also a methodology for the assembly and repair of ITER by means of parallel robots.
Resumo:
Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor’s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque reference. This method is however parameter sensitive and requires a safety margin between the theoretical torque maximum and the actual torque limit. The DTC modulation principle allows however a direct load angle adjustment without any current control. In this work a direct load angle control method has been developed. The method keeps the drive stabile and allows the maximal utilisation of the drive without a safety margin in the torque limitation.
Resumo:
Large amplitude bus bar aeolian vibration may lead to post insulator damage. Different damping applications are used to decrease the risk of large amplitude aeolian vibration. In this paper the post insulator load caused by the bus bar aeolian vibration and the effect of damping methods are evaluated. The effects of three types of bus bar connectors and three types of primary structures are studied. Two actual damping devices, damping cable and their combinations are studied. The post insulator loads are studied with strain gage based custom made force sensors installed on the both ends of the post insulator and with the displacement sensor installed on the midpoint of the bus bar. The post insulator loads are calculated from the strain values and the damping properties are determined from the displacement history. The bus bar is deflected with a hanging weight. The weight is released and the bus bar is left to free damped vibration. Both actual bus bar vibration dampers RIBE and SBI were very effective against the aeolian vibration. Combining vibration damper with damping cable will increase the damping ratio but it may be unnecessary considering the extra effort. Bus bar connector type or primary structure have no effect on the vertical load. The bending moment at the post insulator with double sided bus bar connector is significantly higher than at the post insulator with single sided bus bar connector. No reliable conclusions about bus bar connector type effect can be done, but the roller bearing type or central bearing type connector may reduce the bending moment. The RHS steel frame as primary structure may increase the bending moment peak values since it is the least rigid primary structure type and it may start to vibrate as a response to the awakening force of the vibrating bus bar.