Darbas skirtas skylių gręžimo stiklo tekstolito plokštėse kokybės užtikrinimo problemoms spręsti. Teoriškai išanalizuoti įvairūs gręžimo būdai: mechaninis, lazerinis,  plazminis. Išdėstyti pagrindiniai faktoriai, lemiantys skylių kokybinius parametrus.Eksperimentinis tyrimas buvo atliekamas Tauragėje AB „Telga“, gręžimo ceche. Programinėmis gręžimo staklėmis TIMAX MDR 2002 gręžtas stiklo tekstolitas FR–4, skirtingais pjovimo režimais. Mikroskopu įvertinta įvairiais režimais ir grąžtais gautų paviršių kokybė. Išaiškinti optimalūs darbo režimai priklausomai  nuo skylių kokybės keliamų reikalavimų. / This work deals with the quality problems of hole drilling in the glass textolite panels. Different drilling methods: mechanical, laser based and plasmic drilling have been analysed theoretically. The main factors, determining qualitative parameters of holes, have been stated. Experimental study has been performed in Tauragė, AB „Telga“ drilling workshop. Glass textolite FR–4 has been drilled using programmable drilling machine TIMAX MDR 2002 and applying different cutting modes. The quality of surfaces obtained after drilling by different modes and drills has been evaluated by using microscope. Optimal performance modes depending on the requirements for the quality of holes have been explored. The work consists of four parts: introduction, literature review, experimental analysis and conclusions.

No description available.

Undervisning om multiplikationstabellen består främst av lärande genom repetition eller strategi. Syftet med litteraturstudien är att utifrån forskning undersöka och jämföra inlärning av multiplikationstabellen genom strategi- och repetitionsbaserad undervisning. Studien avgränsas till elever i årskurs 1 till 6. Materialet samlades in genom en iterativ sökning på åtta databaser för vetenskapliga publikationer. Det insamlade materialet bestod av sjutton vetenskapliga publikationer. Resultatet visade att både lärande genom repetition och lärande genom strategi möjliggör för elever att automatisera multiplikationstabellen. Resultatet visade också att lärande genom strategi gör att elever kan använda sina kunskaper i nya matematiska sammanhang. En nackdel med lärande genom repetition är att det är svårt att lära sig multiplikationstabellen utan att använda mönster och samband. Strategi- och repetitionsbaserad undervisning leder till olika felsvar. Felsvaren förklaras bland annat med att eleven övat för lite eller att de har en bristande taluppfattning. Forskningen presenterar en stadieteori som beskriver lärandet av multiplikationstabellen och två olika teorier som beskriver hur multiplikationskombinationer memoreras. Kombinationerna memoreras som enskilda enheter eller som system av sammankopplade erfarenheter. / Teaching of the multiplication table mainly consists of learning through drill or learning through strategy. The aim of this literature study is to investigate and compare the learning of the multiplication table through strategy and drill. The study is an analysis of previous research and limited to research on pupils in grade 1 to 6. The material was collected through an iterative search in eight databases of scientific literature. The retrieved material contained seventeen scientific publications. The analysis showed that both learning through drill as well as learning through strategy make pupils develop automaticity of the multiplication table. It also showed that learning based on strategies enable pupils to use acquired knowledge in new mathematical areas. A disadvantage of learning through drill is that it is difficult to learn multiplication facts without utilizing patterns and connections. Pupils make different errors depending on whether they have been taught through strategies or through drill. Errors are explained with a variety of factors, for instance a lack of practice or a lack of number sense. Previous research present three phases that pupils go through in order to master the multiplication table and two different theo-ries of how the multiplication facts are memorized. The multiplication facts are memorized either as separate entities or as a system of interrelated experiences.

This thesis analyzes the nonlinear dynamics of a drill-string including uncertainty modeling. A drill-string is a slender flexible structure that rotates and digs into the rock in search of oil. A mathematical-mechanical model is developed for this structure including fluid-structure interaction, impact, geometrical nonlinearities and bit-rock interaction. After the derivation of the equations of motion, the system is discretized by means of the finite element method and a computer code is developed for the numerical computations using the software MATLAB. The normal modes of the dynamical system in the prestressed configuration are used to construct a reduced order model for the system. To take into account uncertainties, the nonparametric probabilistic approach, which is able to take into account both system-parameter and model uncertainties, is used. The probability density functions related to the random variables are constructed using the maximum entropy principle and the stochastic response of the system is calculated using the Monte Carlo method. A novel approach to take into account model uncertainties in a nonlinear constitutive equation (bit-rock interaction model) is developed using the nonparametric probabilistic approach. To identify the probabilistic model of the bit-rock interaction model, the maximum likelihood method together with a statistical reduction in the frequency domain (using the Principal Component Analysis) is applied. Finally, a robust optimization problem is performed to find the operational parameters of the system that maximizes its performance, respecting the integrity limits of the system, such as fatigue and instability

The seabed is envisaged to meet the increased future demands for minerals from the rapidly growing industrialized societies of the world. Shipboard analysis of cores can significantly reduce the cost and time spent at the exploratory drilling stage by obviating the need to go back to land for analysis. It can further speed the exploration process by enabling a quick modification of the exploration plan based on the results of the shipboard analysis. A ²⁵²Cf-based analyzer utilizing the prompt gamma neutron activation analysis technique has been designed. The analyzer is a spherical iron shell with the source at its center. The seabed core is passed through a hollow composite tube which is positioned a short distance directly below the source and the resulting prompt gamma rays are collimated to a HPGe detector. The rest of the sphere is filled with paraffin. The gamma ray flux at the detector is converted into a count rate by using a semi-empirical detector response function. This count rate data are then used to determine the sensitivity and detection limits for the chosen elements (Mg, Al, Ti, Cr, Mn, Fe, Ni and Cu). Monte Carlo simulations using the Monte Carlo neutron photon coupled transport code, MCNP, were carried out for a parametric study of important variables influencing the design of the analyzer. These parameters included the moderator type, source to sample distance and sample porosity. MCNP was then used to model the analyzer and to generate the neutron flux profiles in the sample and the prompt gamma flux at the detector. Due to the non-availability of the prompt gamma data for most of the elements of economic interest in the ENDF/B-V cross section libraries associated with MCNP, the point kernel photon transport code ISOSHLD-II (modified for high energy gamma rays) was used to generate the gamma flux at the detector for specific elements. The ISOSHLD-II source term was calculated based on known gamma production data (thermal capture only) and the thermal neutron flux in the sample obtained from MCNP computations. The sensitivity and detection limits obtained from the isotopic source based analyzer were compared for the case of aluminum with values reported from reactor facilities. The results obtained indicate that the analyzer designed in this work could prove suitable for the on-line analysis of many elements of economic interest in seabed cores at the 1 weight percent level. / Graduation date: 1992

Zugl.: Göttingen, Univ., Diss., 2009

Thesis (Ph. D.)--Rice University, 1974. / Includes bibliographical references (leaves 112-125).

Thesis (M.S.)--Western Washington University, 2010. / Includes bibliographical references (leaves 104-115). Also issued online.

Thesis (M.S.)--Baylor University, 2009. / Superscript: 6 and 3 in "106m3". Includes bibliographical references (p. 170-175).

This thesis project was conducted in connection with the project, Stockholm’s future sewer pipeline, which is a planned sewer pipe that will run through a tunnel from western to southern Stockholm. This tunnel will pass under Lake Mälaren between Eolshäll and Smedslätten, where there are two faults indicated on the geological map, that could affect the tunnelling and create risks during the construction. Geophysical- and water-loss measurements along with core drilling have been carried out in the area. The objectives of this thesis are to create a structural and engineering geological understanding of the passage beneath Lake Mälaren based on drill core mapping, field work, data from previous investi-gations and 2D-models of the tunnel excavation both within and outside the indicated fault zone. The core mapping supports the existence of one fault zone, which is indicated on the geological map supported by water-losses at several places along the drill core as well as core losses. Field work indi-cated the existence of a conjugate fracture sets.The 2D-models present plastic behaviour of the rock in the fault zone as the worst case scenario during excavation with the highest deformation displacement. The excavation procedure and the tunnel form also play a significant role. Since this thesis highlights some significant risks and problems that can occur during tunnelling, its findings may be useful during the tunnel construction. / Denna uppsats är skriven med koppling till projektet, Stockholms framtida avloppsledning, vilket inkluderar en ny tunnel för transport av avloppsvatten från västra till södra Stockholm. Tunneln kommer att passera under Mälaren mellan Smedslätten och Eolshäll, där det är två förkastningar indikerade på geologiska kartor som kan orsaka stora risker för byggnationen av tunneln. Geofysiska mätningar, kärnborrning och vattenförlustmätning har tidigare utförts i området. Målen för denna uppsats är att skapa en geologisk- och bergmekanisk förståelse för tunnelpassagen under Mälaren utifrån kärnkartering, fältarbete, data från tidigare undersökningar och 2D-modeller av tunneluttag i den indikerade zonen och utanför. Kärnkarteringen stödjer existensen av en förkastningszon som finns på den geologiska kartan. Flertalet vattenförluster är indikerade längs med hela kärnan tillsammans med en del förekomster av kärnförluster. Fältarbetet indikerar på förekomst av ett konjugerande sprickset. 2D-modeller över tunneln visade att olika egenskaper på berget samt hur uttaget av tunneln sker har betydelse för deformationernas storlek. Den här uppsatsen belyser några viktiga problem och risker som kan uppstå under tunnelbyggnationen, dessa upptäckter kan därför vara användbara och värdefulla under hela byggnationen.