Livin on chinese rocks

Luettua

Rakentaako Chen evaluaatiotutkimukselle sen tuolista puuttuvat kaksi jalkaa - vai vahvistaako hän jo olemassa olevaa? Entä selkänoja? Tarvitseeko evaluaatiotutkimus laajemmasta näkökulmasta oman irtotuolin sijasta penkin vai torin, jolla ei ole edes penkkejä?

Abstract:Does evaluation need a three-legged stool? Should there be even more legs in the stool for evaluation or should evaluation have a bench? Or would it be best or more practical for evaluation if it was a square or marketplace without any kind of stools or bench? What is Huey-Tsyh Chen doing for evaluation in his new "Practical evaluation"?

Kuljetusvirtojen yhdistely kannattavaksi kuljetussuoritteeksi maatalouteen liittyvissä tuoteryhmissä

Diplomityön tavoitteena on arvioida kuljetusvirtojen yhdistämisen kannattavuutta. Kannattavuuden arvioimiseksi määritetään kuljetusvirtojen yhdistämisestä syntyneiden kuljetusreittien hinnat, jotka perustuvat reitillä käytettävien ajoneuvojen kuljetuskustannuksiin. Työssä kuvataan reitin hinnan määrittämiseksi rakennetun hinnoittelutyökalun ominaisuuksia ja käyttöä. Kova kilpailu ja huomattava kuljetuskustannusten osuus kaikista logistiikkakustannuksista haastavat yritykset kehittämään toimituspalveluistaan yhä tehokkaampia. Jotta niin asiakkaiden, toimittajien kuin kuljetusyritystenkin tarpeet voidaan mahdollisimman hyvin huomioida, on ensisijaisesti tarkasteltava yrityksen omaa toimintaa ja sen kehittymisvalmiuksia kuljetusten hallinnassa. Kuljetuskustannusten muodostumisen havainnollistamiseksi työssä perehdytään raskaan kuljetuskaluston kustannuslaskelmiin eri tekijöineen. Perusteluja kuljetusten yhdistämisen kannattavuudelle haetaan yritysmaailmassa jo toteutetuista esimerkeistä ja kuljetusten yhdistämisen rajoituksista. Kuljetusvirtojen yhdistelyn avulla yrityksen on mahdollista tehostaa logistisia palveluitaan kuljetusten osalta. Taulukkolaskentapohjainen työkalu auttaa tyhjänä ajettavien reittiosuuksien minimoinnissa. Tyhjänä ajon vähentymisen vaikutus näkyy kuljetuskustannusten alenemisena, jonka hyötyjä voidaan pitkällä aikavälillä jakaa useamman sidosryhmän kesken.

Modeling and Parameter Estimation of Double-Star Permanent Magnet Synchronous Machines

The power rating of wind turbines is constantly increasing; however, keeping the voltage rating at the low-voltage level results in high kilo-ampere currents. An alternative for increasing the power levels without raising the voltage level is provided by multiphase machines. Multiphase machines are used for instance in ship propulsion systems, aerospace applications, electric vehicles, and in other high-power applications including wind energy conversion systems. A machine model in an appropriate reference frame is required in order to design an efficient control for the electric drive. Modeling of multiphase machines poses a challenge because of the mutual couplings between the phases. Mutual couplings degrade the drive performance unless they are properly considered. In certain multiphase machines there is also a problem of high current harmonics, which are easily generated because of the small current path impedance of the harmonic components. However, multiphase machines provide special characteristics compared with the three-phase counterparts: Multiphase machines have a better fault tolerance, and are thus more robust. In addition, the controlled power can be divided among more inverter legs by increasing the number of phases. Moreover, the torque pulsation can be decreased and the harmonic frequency of the torque ripple increased by an appropriate multiphase configuration. By increasing the number of phases it is also possible to obtain more torque per RMS ampere for the same volume, and thus, increase the power density. In this doctoral thesis, a decoupled d–q model of double-star permanent-magnet (PM) synchronous machines is derived based on the inductance matrix diagonalization. The double-star machine is a special type of multiphase machines. Its armature consists of two three-phase winding sets, which are commonly displaced by 30 electrical degrees. In this study, the displacement angle between the sets is considered a parameter. The diagonalization of the inductance matrix results in a simplified model structure, in which the mutual couplings between the reference frames are eliminated. Moreover, the current harmonics are mapped into a reference frame, in which they can be easily controlled. The work also presents methods to determine the machine inductances by a finite-element analysis and by voltage-source inverters on-site. The derived model is validated by experimental results obtained with an example double-star interior PM (IPM) synchronous machine having the sets displaced by 30 electrical degrees. The derived transformation, and consequently, the decoupled d–q machine model, are shown to model the behavior of an actual machine with an acceptable accuracy. Thus, the proposed model is suitable to be used for the model-based control design of electric drives consisting of double-star IPM synchronous machines.

Viability of part cargoes in tramp shipping company’s routing and scheduling decisions

Operational excellence of individual tramp shipping companies is important in today’s market, where competition is intense, freight revenues are modest and capital costs high due to global financial crisis, and tighter regulatory framework is generating additional costs and challenges to the industry. This thesis concentrates on tramp shipping, where a tramp operator in a form of an individual case company, specialized in short-sea shipping activities in the Baltic Sea region, is searching ways to map their current fleet operations and better understand potential ways to improve the overall routing and scheduling decisions. The research problem is related to tramp fleet planning where several cargoes are carried on board at the same time, which are here systematically referred to as part cargoes. The purpose is to determine the pivotal dimensions and characteristics of these part cargo operations in tramp shipping, and offer both the individual case company and wider research community better understanding of potential risks and benefits related to utilization of part cargo operations. A mixed method research approach is utilized in this research, as the objectives are related to complex, real-life business practices in the field of supply chain management and more specifically, maritime logistics. A quantitative analysis of different voyage scenarios is executed, including alternative voyage legs with varying cost structure and customer involvement. An on-line-based questionnaire designed and prepared by case company’s decision group again provides desired data of predominant attitudes and views of most important industrial customers regarding the part cargo-related operations and potential future utilization of this business model. The results gained from these quantitative methods are complied with qualitative data collection tools, along with suitable secondary data sources. Based on results and logical analysis of different data sources, a framework for characterizing the different aspects of part cargo operations is developed, utilizing both existing research and empirical investigation of the phenomenon. As conclusions, part cargoes have the ability to be part of viable fleet operations, and even increase flexibility among the fleet to a certain extent. Naturally, several hinderers for this development is recognized as well, such as potential issues with information gathering and sharing, inefficient port activities, and increased transit times.