Previous mineralogical investigations (QemSCAN) performed on all effluent flotation streams of Mimosa mine (Zimbabwe) indicated the presence of appreciable amounts of platinum group minerals (PGMs), which are not recovered. Most, generally in excess of 70%, of the liberated PGMs in these streams belonged to the Pt-Pd-Bi-Te class in all the samples investigated. In the first part of this work, electrochemical investigations, electrochemically-controlled contact angle measurements and Raman spectroscopy have been employed to investigate the interaction of ethyl xanthate with Pd-Bi-Te and PtAs2. Impedance measurements showed lower capacitance values in solutions containing KEX indicating the formation of a continuous surface layer. Anodic and cathodic polarization diagrams show the mixed potential to be higher than the reversible potential of the xanthate-dixanthogen equilibrium reaction, hence the formation of dixanthogen on the surface is possible. Electrochemically controlled in situ Raman spectroscopy has confirmed the co-presence of xanthate with dixanthogen indicating that xanthate retains its molecular integrity when it adsorbs on the surface of the Pd-Bi-Te. The result of this investigation has shown dixanthogen to be present on both the minerals (PtAs2 and Pd-Bi-Te) when the surfaces are anodically polarized. Chemisorbed xanthate could be identified within 120 seconds yielding a hydrophobic surface as indicated by electrochemically-controlled contact angle measurements. Maximum contact angles of 63o were measured in the case Pd-Bi-Te. As a result the mineral surface is expected to be hydrophobic and a lack of collector interaction with the mineral is not the reason for low PGM recoveries experienced. Secondly, the flotation recovery of synthetically prepared Pd-Bi-Te was compared with that of chalcopyrite (a typical fast-floating mineral) and pyrrhotite (a typical slow-floating mineral), with microflotation tests. These indicated Pd-Bi-Te to be a fast-floater with flotation rates exceeding that of chalcopyrite. Predicted flotation rate constants (from the Ralston model) were significantly lower for small particles (with diameters similar to those lost to the effluent streams) compared with those of particle with intermediate sizes. This supports the suggestion that losses to effluent streams are caused by particle size effects. / Thesis (PhD (Metallurgical Engineering))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted

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<p>Rad,Edukativni i op&scaron;ti model kritičnih protoka materijala PD - Precedence Diagramming Structure, predstavlja integralni deo teorijskih i eksperimentalnih istraživanja vezanih za razvoj stohastičkih mreža PD-modela iz operacionih istraživanja, kao i modela za odgovarajuću edukaciju kadrova iz oblasti mrežnog upravljanja tokovima materijala u ma&scaron;inogradnji. U tom smislu u radu su razvijeni i re&scaron;avani, putem analitičkih i numeričkih metoda, sledeći modeli:</p><ul><li>Mrežni PD-model sa jednim kritičnim tokom.</li><li>Mrežni PD-model sa isključivo autonomnim (paralelnim) kritičnim tokovima.</li><li>Op&scaron;ti model sa varijantom kritičnih tokova autonomno-unijatnog tipa.</li><li>Edukativni model za efikasno re&scaron;avanje postavljenih problema upravljanjatokovima materijala u pojedinačnoj proizvodnji.</li><li>Modeli za vrednovanje metoda i postupaka iz ovih oblasti operacionih istraživanja, kao i samog edukativnog modela, na bazi razvijenih kvantitativnih i kvalitativnih kriterijuma.</li></ul><p>Ovim istraživanjem stvorene su određene podloge za dalji rad u predmetnom području, posebno sa stanovi&scaron;ta neinvesticionog povećanja efekata materijalne proizvodnje, putem primene razvijenih opercionih modela i edukativnih metoda za njihovo re&scaron;avanje.</p> / <p>The paper &quot;THE EDUCATIVE AND GENERAL MODEL OF THE CRITICAL MATERIAL FLOWS, PD-PRECEDENCE DIAGRAMMING STRUCTURE&quot; makes the integral part bof the theoretical and experimental researches connected for the development of the stochastic network PD - models of the opertions research, as well the models for the appropriote personal cadres edu cation in the field of network control of materijal flows in production of machinery. In the paper are also developed and solved, by analytic and numeric methods, the next models:</p><p>* The network PD-model with one critical flow.</p><p>* The network PD-model with excusively autonomus (parallel) critical flows.</p><p>* The general model with the variant of the critical flows of the autonomus -uniate type.</p><p>* The educative model for the effective solving of the stated problems of the material flows control in isolated production.</p><p>* The models and methods valuation of these fields of the operations researches, as well the educative model itself on the basic of the developed quantative and qualitative criteria.</p><p>With these researches are created the defined bases for further work in the subject field, particularly from the attitude of the noninvestment increasing of the effects of the materijal production, using the developed operations models and the educative models for their solving.</p>

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This work focuses on a search of available literature on the theory of transmission lines and verify the possibility of simulation processes on these lines using a suitable simulation program. Initially, for the introduction to the parameters and the phenomenon that characterize the line and are important for understanding the issue. These parameters are then measured and compared with traces from the simulation in program PSpice. In another part of the work, the reader is familiar with the basics of reflectometry and fault detection capabilities on transmission lines with the basic reflectometry methods TDR and FDR, as well as with other methods of OTDR, MSR, and PD-FDR. For the TDR, FDR and MSR methods were made experimental measurements with a view to determining the position of the various types of faults on the tested leadership.

This paper addresses the issue of design and implementation of syntactic analysis based on the context sensitive languages, respectively, grammars that contains constructs, which isn't possible to analyze with the help of the standard parsers based on the context free grammars. More specifically, this paper deals with the possibility of adding context sensitive support to the classic LL-analysis by replacing the standard pushdown automata (PDA) with deep pushdown automata (DP), which were introduced and published by prof. Alexander Meduna.

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Ziel der Arbeit war es einerseits die intrinsischen katalytischen Eigenschaften der intermetallischen Verbindungen In3Pt2, In2Pt und In7Pt3 in der MSR zu untersuchen. Dabei sollten Volumenproben mit verschiedenen Methoden im Volumen und an der Oberfläche hinsichtlich ihrer in situ Stabilität untersucht werden. Andererseits sollten Pd/In2O3 und Pt/In2O3 Aerogele als Katalysatormaterialien untersucht werden und strukturelle Veränderungen dieser Materialien mit den katalytischen Eigenschaften korreliert werden. Phasenreine Volumenverbindungen der drei indiumreichen Verbindungen des In-Pt Systems, In3Pt2, In2Pt und In7Pt3, wurden in dieser Arbeit hergestellt. Katalytische Untersuchungen zeigten eine starke Abhängigkeit der CO2 Selektivität von der gewählten Verbindung, wobei In2Pt mit einer CO2 Selektivität von 99,4% die höchste Selektivität aufweist (Abbildung 77). Mittels XRD und operando TGA/MS Messungen konnte gezeigt werden, dass In2Pt und In7Pt3 unter Reaktionsbedingungen teilweise zu In3Pt2 und In2O3 oxidiert werden. Mittels in situ XPS Untersuchungen konnte zudem nachgewiesen werden, dass auch In3Pt2 eine minimale oberflächliche Oxidation aufweist. Dementsprechend sind in keinem Fall die intrinsischen katalytischen Eigenschaften, sondern die Eigenschaften einer teilweise oxidierten Oberfläche bestimmt worden. Dies ist analog den zinkreichen ZnPd Verbindungen. Bei den Aerogelen wurden mittels kontrollierter partieller Reduktion die intermetallische Verbindungen InPd und In2Pt für das Pd/In2O3 bzw. Pt/In2O3 einphasig auf In2O3 erhalten. In katalytischen Tests zeigten beide Materialien ausgezeichnete Selektivitäten, welche mit ≥ 99% über den Volumenverbindungen und bekannten Materialien liegen. Über den Vergleich der kristallinen Struktur vor und nach der Katalyse konnte gezeigt werden, dass nicht die ursprüngliche kristalline Struktur erhalten bleibt, sondern in Abhängigkeit der Temperatur und der Gasphasenzusammensetzung die Verbindungen InPd und In3Pd2 bzw. In3Pt2 und In2Pt im Gleichgewicht miteinander vorliegen. Mittels ex situ HR-TEM konnte zudem nachgewiesen, dass bei InPd/In2O3 und In2Pt/In2O3 im selektiven und aktiven Zustand die Ausbildung einer oxidischen Schicht um die intermetallischen Partikel auftritt. Mit 18O-markierten Isotopenexperimenten konnte gezeigt werden, dass die Grenzfläche zwischen intermetallischen Verbindungen und oxidischem Indium katalytisch aktiv ist und der enthaltene Sauerstoff aktiv im katalytischen Zyklus beteiligt ist. Aufgrund der Eingrenzung der aktiven Region auf die Grenzfläche zwischen Oxid und intermetallischer Verbindungen bzw. grenzflächennahe Bereiche mittels Spillovers, sowie der strukturellen Veränderungen unter Reaktionsbedingungen konnte abgeleitet werden, dass der katalytische Zyklus an Pd/In2O3 und Pt/In2O3 Materialien eine Redoxreaktion verschiedener intermetallischer Verbindungen umfasst. Im Zuge dieser Phasenumwandlungen wird chemisch gebundener Sauerstoff aus dem Katalysatormaterial in die Reaktionsprodukte eingebracht. Inwieweit partiell reduzierte Indiumoxide dabei als aktive Zentren fungieren, wurde nicht weiter untersucht. Die Wahl intermetallischer Verbindungen als Katalysatormaterialien in der MSR wird demnach nicht nur durch die Neigung zur Oxidation, sondern auch zur Reduktion bestimmt, sodass die Möglichkeit eines Redoxzyklus unter Reaktionsbedingungen besteht, welcher in einer aktiven und selektiven Oberflächenstruktur resultiert. Dieser Zyklus kann entweder durch die Wahl der im Katalysatormaterial enthaltenen Elemente oder durch eine Anpassung der Gasphase gesteuert werden., beispielsweise führte die Erhöhung des Wassergehaltes beim In2Pt/In2O3 Material zur Ausbildung der bei 300 °C beobachteten Redoxchemie bei 400 °C. Dies zeigt, dass die Kenntnis der thermodynamischen Daten für (potenzielle) Katalysatorsys-teme hochgradig wichtig ist, um über die Ermittlung der Gibbs-Energie die Redoxchemie ei-nes bestimmten Systems, beispielsweise In-Pd, In-Pt oder Zn-Pd, über eine Anpassung der Reaktandenkonzentration zu beeinflussen. Über die Beimischung von reduzierenden Additi-ven ist diese Redoxchemie eventuell auch für oxidativ desaktivierende Systeme wie Sn-Pd oder Ga-Pd realisierbar.

Philosophiae Doctor - PhD / In this thesis, we describe linear codes over prime fields obtained from incidence designs of iterated line graphs of complete graphs Li(Kn) where i = 1,2. In the binary case, results are extended to codes from neighbourhood designs of the line graphs Li+l(Kn) using certain elementary relations. Codes from incidence designs of complete graphs, Kn' and neighbourhood designs of their line graphs, £1(Kn) (the so-called triangular graphs), have been considered elsewhere by others. We consider codes from incidence designs of Ll(Kn) and L2(Kn), and neighbourhood designs of L2(Kn) and L3(Kn). In each case, the basic parameters of the codes are determined. Further, we introduce a family of vertex-transitive graphs Rn that are embeddable into the strong product Ll(Kn) ~ K2' of triangular graphs and K2' a class that at first sight may seem unnatural but, on closer look, is a repository of graphs rich with combinatorial structures. For instance, unlike most regular graphs considered here and elsewhere that only come with incidence and neighbourhood designs, Rn also has what we have termed as 6-cycle designs. These are designs in which the point set contains vertices of the graph and every block contains vertices of a 6-cycle in the graph. Also, binary codes from incidence matrices of these graphs have other minimum words in addition to incidence vectors of the blocks. In addition, these graphs have induced subgraphs isomorphic to the family Hn of complete porcupines (see Definition 4.11). We describe codes from incidence matrices of Rn and Hn and determine their parameters. The discussion is concluded with a look at complements of Rn and Hn, respectively denoted by Rn and Hn. Among others, the complements rn are contained in the union of the categorical product Ll(Kn) x Kn' and the categorical product £1(Kn) x Kn (where £1(Kn) is the complement of the iii triangular graph £1(Kn)). As with the other graphs, we have also considered codes from the span of incidence matrices of Rn and Hn and determined some of their properties. In each case, automorphisms of the graphs, designs and codes have been determined. For the codes from incidence designs of triangular graphs, embeddings of Ll(Kn) x K2 and complements of complete porcupines, we have exhibited permutation decoding sets (PD-sets) for correcting up to terrors where t is the full error-correcting capacity of the codes. For the remaining codes, we have only been able to determine PD-sets for which it is possible to correct a fraction of t-errors (partial permutation decoding). For these codes, we have also determined the number of errors that can be corrected by permutation decoding in the worst-case.

Background: Data regarding both drug-related and non-drug-related costs in patients with Parkinson's disease (PD) are scarce, mainly due to the difficulties in data acquisition in experimental designs. Likewise, the reported impact of drug costs on total direct costs varies across different studies. In addition, the influence of comorbidities on both treatment costs and health-related quality of life has not been adequately evaluated. Methods: A sample of office-based neurologists (n = 315) in Germany was asked to examine up to five consecutive patients with PD (n = 1449) on a specified day during the study period. Patients of all ages were eligible and their evaluation was performed using standardized questionnaires. Results: PD-specific therapy costs increased with the stage of the disease, early onset of the disease and disease duration. The major costs were due to PD-related therapy, whereas other medications only resulted in minor costs. Disease stage mainly influenced direct therapy costs, with an observed increase of total daily costs from €7.3 to €11.3/day. In addition, disease onset at age < 65 years resulted in total daily costs of €11.2 compared to late onset of disease (> 75 years) with daily therapy costs of €5.3. In this patient group neuropsychiatric comorbidities such as dementia and depression were only insufficiently treated. In addition, these comorbidities severely affected health-related quality of life. Conclusion: Therapy costs were influenced by disease stage, disease onset as well as present comorbidities. Furthermore, comorbidities such as depression and dementia were diagnosed but were not adequately treated.