High Temperature Expansion and Exact Diagonalization of the Rhodium Nuclear Spin System Compared to Experimental Results

The nuclear spin system of Rh metal has recently been investigated experimentally. No nuclear magnetic ordering was observed in these measurements, in spite of the very low nuclear entropy achieved. To study this system theoretically, we have applied the method of exact diagonalization to a 16 spin I=1/2 fcc cluster with both Ruderman-Kittel and dipolar interactions. In this work, we compare the results of this method with the experimental data and the high temperature expansion results in the paramagnetic state. The high temperature expansions agree with the experimental data down to 1 nK, while the exact diagonalisation results are less accurate.     

Effect of Annealing Conditions on the Texture and Normal Anisotropy of Al‐Killed Steels in Simulated Batch Annealing

Three commercial cold rolled Al‐killed steels were investigated to study the effect of annealing conditions on the crystallographic texture and the resulting plastic anisotropy. The heating rates, maximum temperatures and isothermal holding times were varied in 18 laboratory scale thermal cycles applied to all steels. The annealed and skin‐passed samples were tensile tested to determine mechanical properties and anisotropy parameters. Grain structures and average grain sizes were examined by an optical microscope and the textures were measured by X‐ray diffraction. It was found that the chemical composition of the steel had a significant effect on the texture and normal anisotropy obtained at certain heating rates. The differences between the current steels were discussed in the light of the competition between the kinetics of AIN precipitation and recrystallization. Excess heating rates led to a low normal anisotropy, which was not improved by extending the isothermal time of annealing. Pancake grain structure and the grain size larger than 20 mm were found to be indicators of the properly chosen heating rate and resulting in high normal anisotropy. At the proper heating rate high normal anisotropy was attained at low annealing temperatures and in short isothermal times, but a longer isothermal annealing was required to obtain a low yield strength.     

Fatigue,residual strength and non-destructive tests of an aging aircraft’s wing detail

This study concentrates on fatigue, residual strength and non-destructive tests of an aging aircraft’s wing detail of the Finnish Air Force’s Hawk Mk.51 jet trainer. The studied detail was the integral stiffener with a drain hole near the wing root. Fatigue tests were deemed necessary to verify experimentally the analytically observed short fatigue life, significant crack growth rates and eventually to re-assess the detail’s inspection period for the fleet jets. The results of the study have been utilized e.g. at the complementary type approval accomplished for the Finnish Air Force’s Hawk.     

The psychology of working: The clinical context.

Vocational psychology increasingly has identified the centrality of work in people's lives. Yet in clinical practice, vocational and personal issues do not always receive equivalent attention, with vocational concerns often being overlooked. With a case study, the author illustrates several factors that can serve as barriers to the successful integration of work and personal concerns. The benefits of integration are then offered, along with strategies that have been proposed to more effectively address both work and personal issues. The author concludes with specific recommendations for integrating work and personal issues in psychological practice, as well as recommendations for training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polarized Nuclei in Normal and Superconducting Rhodium

We performed SQUID-NMR measurements on a rhodium single crystal at ultra-low nuclear-spin temperatures. With initial polarizations up to p=0.95, the antiferromagnetic tendency was clear, but surprisingly no indication of actual nuclear magnetic ordering was obtained. The lowest nuclear temperatures achieved were below 100 pK, whereas the lowest directly measured temperature was 280 pK. Double-spin-flip and evidence for triple-spin-flip resonance lines were detected, yielding direct information of the interactions between the nuclear spins. The superconducting transition of rhodium was observed with the critical values, T_c=210 K and B_c(0)=3.4 T. For the first time, measurements with substantially correlated nuclei were performed in the superconducting state, where the effect of the coherent electron system on the spin-lattice relaxation rate was studied. The spin-lattice relaxation time was longer in the superconducting state at all temperatures and displayed a strong dependence on nuclear susceptibility.     

Combined blowing with three ‐ hole lance in a sidewall blowing converter

Traditionally, in stainless steelmaking converters, oxygen has been blown by a one‐hole lance (1 HL) and sidewall tuyères. In order to reduce the tap‐to‐tap time, the multi‐hole lance has been used for oxygen blowing. The aim of this work was to develop blowing practise for a multi‐hole lance to reduce the tap‐to‐tap time and minimise metal splashing and spitting in the sidewall blowing converter (chromium converter). In the chromium converter the chemical energy of liquid ferrochrome (which contains 4 % silicon and 7 % carbon) is utilised for scrap melting by oxidising the silicon and the part of carbon. The research has been made by a dynamically scaled water model and full‐scale converter. Used parameters were the gas flowrate from sidewall tuyères and lance, lance height, charge weight and position of multi‐hole lance. Splashing has been measured during blowing from walls (splashing) and mouth of the converter model (spitting). The model tests indicated less splashing and spitting by the three‐hole lance (3 HL) than traditional 1 HL. The 1 HL caused strong skulling of the converter cone. By 3 HL blowing the position of the lance has a remarkable effect on the direction and the amount of splashing and lance life. Because of hot metal‐slag splashes, the life time of the 3 HL was halved by position 1 (compared to 1 HL). With the lance position 2 the splashing decreased by approx. 50% in model tests and lance life time increased by ~ 50% (compared to 1 HL) in the full‐scale converter. The model agreed well with the full‐scale converter. According to the process tests, the nominal productivity of the chromium converter has increased 15 % and depending on the refining practise and the silicon content of ferrochromium the lining life has increased 20 ‐ 30 %. In the future the multi‐hole lance will be tested in the AOD vessel.     

Impact strength of high density microcellular poly(vinyl chloride) foams

The impact strength of microcellular poly(vinyl chloride) (PVC) produced from an industrial formulation was investigated. The solid‐state process with carbon dioxide as the blowing agent was used to prepare the specimens. Processing conditions were explored to produce microcellular PVC with a relative density of 0.6 and higher. These foams were impact tested by using a falling‐weight impact tester. Impact strength of microcellular PVC was found to decrease linearly with relative density. The gas saturation pressure did not significantly affect the impact strength of microcellular PVC foams. Microcellular PVC foams with up to 40% reduction in density possessed a normalized mean failure energy of 3.8 J/mm (0.85 in.‐lb/0.001 in.).     

Nuclei in Cooperation

We analyze and discuss two distinct resonance phenomena at high nuclear polarizations, which give independent experimental information about the exchange couplings, direct or indirect, between the nuclear spins in solids. In cases of more than one isotope with a nuclear spin, there is an isotopic-interference effect, sometimes referred to as a suppression-enhancement effect. Even in cases with just one spin species, one may observe harmonic lines of the ordinary Larmor resonance. By analyzing the shifts and intensities of the resonance lines as functions of the nuclear polarization, one can find the sign and magnitude of the exchange couplings. The focus of this paper is in experiments on nuclear magnetic ordering in pure metals. We present studies on copper, silver, rhodium, thallium, and gold, and discuss shortly our ongoing work on lithium. PACS numbers: 76.60.-k, 76.60.Jx, 75.30.Et, 75.10.Jm.     

Properties and Stability of Mining-Induced Meromixis in Two Small Boreal Lakes in Eastern Finland

Mine waters are a significant point source stressor for aquatic environments, not only due to their acidity and high metal concentrations, but also because of their high electrolyte concentrations. Ion-rich mine waters can disturb the seasonal mixing of lake waters, even leading to permanent stratification, i.e. meromixis. In this study, we investigated two small natural lakes receiving waters from closed Ni-Cu mines. To characterize the present chemical and physical conditions of these two boreal lakes, we collected water samples and in-situ water column measurements seasonally in 2017 and 2018. We modelled the stability of meromixis in the lakes under varying physico-chemical and meteorological conditions with the MATLAB-based open-source model code, MyLake. Chemical analyses and water column measurements show that both lakes are currently meromictic with a chemocline separating the circulating, well-oxygenated upper water from the non-circulating, hypoxic bottom water. The main anion was SO₄ in both lakes, while the main cations were Ca, Mg, Na, and K. Elevated concentrations of conservative elements flowing from the mine areas are crucial in maintaining the meromixis. Modelling scenarios suggest that the meromixis would be sustained for several decades even if the external load ceased completely. Lake morphology and sheltered surroundings also seem to contribute to maintaining the meromixis in these lakes. Consequently, our results indicate that small headwaters are sensitive to persistent meromixis even when external loading is mild.

     

Cluster analysis by self-organizing maps: An application to the modelling of water quality in a treatment process

The unit processes in water treatment involve many complex physical and chemical phenomena which are difficult to assess using traditional data analysis methods. Moreover, measurement data gathered from the process is often challenging with respect to modelling purposes, because there is a lack of continuous online measurements, for which sparse laboratory measurement data have to be conducted to compensate them.This paper reports on the application of self-organizing map (SOM) techniques combined with K-means clustering to model water quality in the treatment of drinking water. At the first phase of the study, a SOM was produced by using both on-line and laboratory data of the treatment process and raw water. At the second phase, the reference vectors of the map were classified by K-means algorithm into clusters, which can be used to present different states of the process. At the final phase, the results were interpreted by analyzing the reference vectors in the clusters. The introduced approach offers a straightforward method for assessing the essential characteristics of the process. In addition, the results clearly demonstrate some challenges in the modelling of water quality in treatment processes.