Search

Due to the advances in information retrieval in the past decades, search engines have become extremely efficient at acquiring useful sources in response to a user’s query. However, for more prolonged and complex information seeking tasks, these search engines are not as well suited. During complex information seeking tasks, various stages may occur, which imply varying support needs for users. However, the implications of theoretical information seeking models for concrete search user interfaces (SUI) design are unclear, both at the level of the individual features and of the whole interface. Guidelines and design patterns for concrete SUIs, on the other hand, provide recommendations for feature design, but these are separated from their role in the information seeking process. This chapter addresses the question of how to design SUIs with enhanced support for the macro-level process, first by reviewing previous research. Subsequently, we outline a framework for complex task support, which explicitly connects the temporal development of complex tasks with different levels of support by SUI features. This is followed by a discussion of concrete system examples which include elements of the three dimensions of our framework in an exploratory search and sensemaking context. Moreover, we discuss the connection of navigation with the search-oriented framework. In our final discussion and conclusion, we provide recommendations for designing more holistic SUIs which potentially evolve along with a user’s information seeking process.

The combined treatment of pressurized gas nitriding and cold rolling is proposed as a new approach to rapid preparation of a strong and tough nitrided layer for steel 38CrMoAlA. The microstructural characteristics and properties of the modified surface layer in comparison with those of the conventionally gas nitrided sample have systematically been evaluated. The results show that the hardness and toughness of the nitrided surface layer can be significantly improved by the combined treatment. Especially, the wear resistance of nitrided surface layer under heavy loads was greatly enhanced. It can provide a new approach to rapidly preparing a nitrided layer with high strength and toughness.

Nuclear-grade 316LN stainless steel was subjected to single and double compressions at 1173–1473 K and strain rates of 0.01–10 s⁻¹. The dynamic and postdeformation recrystallization was investigated through analysis of the stress–strain curves and microstructure evolution. The thermal deformation equation and the quantitative relationships between the critical stress for the initiation of dynamic recrystallization and the Zener–Hollomon parameter, Z, and between the dynamic recrystallization grain size D and Z were derived. Dynamic recrystallization developed through an ordinary mechanism at low Z values and through a necklace mechanism at high Z values, with a critical Z value of about 3.6 10¹⁶ . At 1273–1473 K, softening of 316LN stainless steel after deformation was characterized by an Avrami-type equation, where the Avrami parameter, n, has no appreciable temperature dependence, and an average value of n and the activation energy, Qrex , were 0.68 and 129 kJ/mol, respectively. Нержавеющая сталь 316LN ядерного класса подвергалась одно- и двукратному сжатию при 1173...1473 К и скорости деформации 0,01...10 с⁻¹. Динамическая и постдеформационная рекристаллизация изучалась с помощью анализа зависимости деформации от напряжения и развития микроструктуры. Были выведены уравнение тепловой деформации и количественные зависимости между критическим напряжением инициирования динамической рекристаллизации и параметром Зенера Холломона Z, а также между размером зерна D при динамической рекристаллизации и Z. Динамическая рекристаллизация развивалась по обычному механизму при низких значениях Z и по механизму ожерелья при высоких значениях Z, при критическом значении Z примерно 3 6 10¹⁶. При 1273...1473 К разупрочнение нержавеющей стали 316LN после деформирования описывается уравнением Аврами, где параметр Аврами n не проявляет выраженной температурной зависимости, а его среднее значение и энергия активации Qrex составляют 0,68 и 129 кДж/моль соответственно.

Four new Ln(III) complexes (Ln = Eu, Tb) with furan-2,5-dicarboxylic acid (H2FDA) as a ligand have been synthesized and characterized in the solid state. Luminescence studies indicate that the compounds exhibit line-like luminescence characteristic of the lanthanide centre upon excitation in the ligand absorption bands. Single crystal X-ray diffraction study of {[Eu(FDA)(H2O)5]·½(FDA)·3H2O}n shows the formation of an inorganic polymer with infinite Eu-FDA chains.

The three phases of the mononuclear two-step spin crossover compound [Fe(bapbpy)(NCS)2] (1) are characterized by powder X-ray diffraction, Mo¨ssbauer spectroscopy, Raman spectroscopy, calorimetry, and magnetic susceptibility measurements. Mo¨ssbauer and Raman spectroscopies confirm the results obtained from previous single crystal X-ray diffraction studies, as they show that the intermediate phase is characterized by a 1:2 high-spin/low-spin ratio and that it is not a mixture of the high-spin state (HS) and low-spin state (LS) phases. Sample preparation and sample history studies show that the spin crossover (SCO) properties of this compound are quite robust, as the two steps and hysteresis cycles are present both in the powder and in recrystallized samples and conserved when the sample is cooled and heated several times. Compound 2, a DMF solvate having the formula [Fe(bapbpy)(NCS)2] · 2DMF, shows SCO properties but no cooperative effects. The origin of the strong cooperativity found in compound 1 is discussed. Finally, external perturbations have been applied to compound 1. First, light irradiation at low temperatures promotes the LS f HS transition with reasonably good optical conversions [∼70%, T(LIESST) ) 56 K]. Second, the application of hydrostatic pressure increases both the temperature and the hysteresis width of the higher-temperature transition (HS T IP), while unexpectedly suppressing the lower-temperature transition (IP T LS).

The three phases of the mononuclear two-step spin crossover compound [Fe(bapbpy)(NCS)2] (1) are characterized by powder X-ray diffraction, Mo¨ssbauer spectroscopy, Raman spectroscopy, calorimetry, and magnetic susceptibility measurements. Mo¨ssbauer and Raman spectroscopies confirm the results obtained from previous single crystal X-ray diffraction studies, as they show that the intermediate phase is characterized by a 1:2 high-spin/low-spin ratio and that it is not a mixture of the high-spin state (HS) and low-spin state (LS) phases. Sample preparation and sample history studies show that the spin crossover (SCO) properties of this compound are quite robust, as the two steps and hysteresis cycles are present both in the powder and in recrystallized samples and conserved when the sample is cooled and heated several times. Compound 2, a DMF solvate having the formula [Fe(bapbpy)(NCS)2] · 2DMF, shows SCO properties but no cooperative effects. The origin of the strong cooperativity found in compound 1 is discussed. Finally, external perturbations have been applied to compound 1. First, light irradiation at low temperatures promotes the LS f HS transition with reasonably good optical conversions [∼70%, T(LIESST) ) 56 K]. Second, the application of hydrostatic pressure increases both the temperature and the hysteresis width of the higher-temperature transition (HS T IP), while unexpectedly suppressing the lower-temperature transition (IP T LS).

The first examples of lanthanide complexes with a 2-hydroxyisophthalate ligand are reported; the blue-emitting ligand acts as a very efficient sensitizer of the Tb(III) green emissions and does so in the near-UV region.

The compounds LaBaACu3O7-d (A = Ca and Sr) have been prepared and characterized by X-ray diffraction and electron microscopy. Their structure is similar to that of YBa2Cu3O7, except that they are tetragonal. Electron diffraction of LaCaBaCu3O7-d reveals the presence of a weak superstructure having doubled, a, b and c axes. The oxygen content and superconducting transition temperature were found to vary significantly, depending on the post-annealing conditions. Oxygen- and air-annealed samples have Tc values of 76 K and 60 K for A = Ca and 50 K and 33 K for A = Sr respectively. Air-quenched samples exhibit semiconductor-like behaviour in both cases. The d.c. resistivity and a.c. susceptibility vs. temperature data for LaBaSrCu3O7-d are presented. The absence of an orthorhombic unit cell for these compounds is discussed and a model for the oxygen-vacancy ordering is proposed to explain the observed superstructure in LaBaCaCu3O7-d.

Generating white light with LED technology requires a trick; one of them is to use color-converting (phosphor) layer that covers the LED chip. Suitable phosphors that can be excited with LEDs are scarce, necessitating research in this area. Complexes of the trivalent lanthanoids are interesting candidates, as their absorption properties can be tuned by modification of the organic part of the molecule, while the emission is line-like in nature and characteristic for the Ln(III) ion. In this thesis, several classes of Ln(III) coordination compounds are explored and their photophysical properties investigated. Several compounds with promising properties, such as a long-wavelength excitation maximum and a high photoluminescence quantum yield are reported.