Browsing by Author "Kokkonen, Jukka"

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A Fiber-Optic Interferometer for Lase Linewidth Measurements
(1996) Kokkonen, Jukka
Helsinki University of Technology | Master's thesis
On-time Delivery Performance and a Demand Planning Solution
(2006) Kokkonen, Jukka
Helsinki University of Technology | Master's thesis
In recent years companies have put a lot of effort both into supply chain management and demand chain management activities hoping to create an environment that supports customer relationships and value creation in supply operations. The recent theoretical development in this area is demand-supply network management, which combines both demand and supply chain activities. The result is a superior capability to maximise the value in the network through customer specific supply operations. In this thesis we have shown that demand-supply network management has to be supported by efficient demand planning and communication processes. Otherwise, demand chain management efforts, which at their best provide an access to early and accurate demand information, cannot be leveraged in supply operations. This was the situation of the case company of this thesis. Supply operations were experiencing problems, especially related to on-time delivery performance levels. When investigated further, it was found that the demand planning processes were not on the level they should have been. Demand information existed in the sales companies, but demand planning activities did not support efficient use of it. Also, it was shown that on-time delivery problems and demand planning were related to each other and therefore, an enhanced demand planning solution was developed. Demand planning solution incorporates both strategic and tactical level planning tasks. Tactical level planning with forecasting, safety buffer analysis, demand-supply balancing and what-if-analysis make up the core of the solution. These tasks are complemented with measurements and active communication tasks. Also, planning cycles and planning organisation are defined. When depicted as a process these activities comprise the core demand planning solution that the case company should incorporate to its operations in order to enhance on-time delivery performance. Important deliverables of this thesis include following: - Connection between demand-supply network management and demand planning. - Connection between on-time delivery performance and demand planning. - Incorporation of demand-supply balancing in the demand planning process. - Demand planning solution for case company modernisation business.
A silicon detector for neutrino physics
(2002-05-17) Kokkonen, Jukka
Doctoral dissertation (article-based)
In order to demonstrate the feasibility of conducting future νμ → ντ oscillation searches using a high-resolution, large-area silicon microstrip detector, the Silicon TARget (STAR) detector was built. STAR was installed in the NOMAD short baseline neutrino oscillation experiment at the CERN SPS neutrino beam, where it recorded approximately 10 000 neutrino interactions during the operation of the detector in the period 1997-98. It consists of five layers of silicon detectors interleaved with four layers of passive boron carbide as the target. The target mass is 45 kg, while the total silicon surface area is 1.14 m2 and contains 32 000 readout channels. The individual modules have a length of 72 cm, the longest built to date. The detection of τ particles, produced in ντ charged-current interactions, would require a tracking detector with a precision of a few tens of microns in order to measure the position of the neutrino interaction vertex as well as the impact parameter of the τ decay products. The performance of STAR was studied by reconstructing the decays of K0S mesons produced in νμ charged-current interactions. For both the primary and secondary vertices, the resolution in the y direction was found to be approximately 20 μm, while that in the z direction was found to be approximately 100 μm. The double vertex resolution, a measure of how accurately the distance between the vertices can be measured, was found to be approximately 20 μm in the y direction and 300 μm in the z direction. The impact parameter resolution of the muons resulting from νμ charged-current interactions, with respect to the primary vertex, was found to be 25 μm. The vertex resolution and impact parameter results show that a microstrip silicon detector would be well-suited to measuring νμ → ντ oscillations. The high precision of silicon detectors has several other applications within neutrino physics, such as using a silicon detector as the near-detector in a future neutrino factory facility.