Effect of Carbon Content on Variant Pairing in Bainitic Low Alloy Steel

Metallurgical and Materials Transactions A - Variant pairing in bainite was evaluated in four different commercial low alloy steels with medium to high carbon content. The steels investigated were...     

Approximability of Clausal Constraints

We study a family of problems, called Maximum Solution (Max Sol), where the objective is to maximise a linear goal function over the feasible integer assignments to a set of variables subject to a set of constraints. When the domain is Boolean (i.e. restricted to {0,1}), the maximum solution problem is identical to the well-studied Max Ones problem, and the complexity and approximability is completely understood for all restrictions on the underlying constraints. We continue this line of research by considering the Max Sol problem for relations defined by regular signed logic over finite subsets of the natural numbers; the complexity of the corresponding decision problem has recently been classified by Creignou et al. (Theory Comput. Syst. 42(2):239–255, 2008). We give sufficient conditions for when such problems are polynomial-time solvable and we prove that they are APX-hard otherwise. Similar dichotomies are also obtained for variants of the Max Sol problem.     

Induction and Synchronous Motors Compared for System Stability

A comparison is made between synchronous motors and induction motors with regard to industrial power system stability. Representation of motor loads in stability studies is reviewed. The specific system studied is an infinite bus supplying a combination induction and synchronous motor load through a transmission line and transformer. The system is subjected to a fault at the transformer and critical values of fault clearing time are computer calculated for ratios of synchronous motor load to induction motor load from zero to unity. The effect of variation of motor parameters on clearing times is discussed.     

Effect of carbon content on variant pairing of martensite in Fe–C alloys

The effect of carbon content on the variant pairing tendency of martensite formed in Fe–C alloys is investigated by means of electron backscattered diffraction analysis. The method used is based on experimentally determined orientation relationships between austenite and martensite. The results show that the carbon content has a strong effect on the martensite variant pairing tendency. This observed change in variant pairing tendency is discussed in relation to the well-known morphological transition from lath to plate martensite in Fe–C alloys and the formation of packets and plate groups. The results indicate that quantitative analysis of variant pairing, as demonstrated here, may facilitate martensite characterization in Fe–C alloys as well as in other alloy systems.     

Spektroskopische Untersuchungen an organischen Carbonylverbindungen. VI. NMR-Studien an substituierten β-Diketonen und ihren vinylogen Derivaten

Spectroscopic Investigations on Organic Carbonyl Compounds. VI. N.M.R.-Studies on Substituted β;-Diketones and their Vinyloge Derivatives . ¹³C- and ¹H-n.m.r.-data of substituted β-diketones and their vinyloge derivatives are presented. Most of the compounds exist chiefly in the enol-form. Only in the case of 4-dimethyl-aminodibenzoylmethane a keto-enol-equilibrium is registered. The influence of the substituent A and the chainlength on the position of the enol proton is discussed.     

Vibronic spectral behaviour of molecules. XV. Study on the T1 → S0 Phosphorescence of Isomeric Terphenyls

Underlying the completely-optimized S₀ and T₁ molecular geometries of isomeric terphenyls the corresponding theoretical vibronic T₁ → S₀ ‘line’ spectra calculated within the CONDON approach, are presented and compared with the experimental phosphorescences. The influence of possible conformations on the vibronic spectral behaviour is studied theoretically. The DUSHINSKY effect is found to be most important to the T₁ → S₀ phosphorescence of m-terphenyl. An analysis of the spectroscopically relevant vibrational modes is given.     

Health assessment of artisanal gold miners in Indonesia

Small scale miners use mercury to extract gold from ore in many countries. An environmental and health assessment was performed in Indonesia in two regions, Galangan in Central Kalimantan and Talawaan in Northern Sulawesi. The environmental assessment showed severe mercury contamination of the sediments, and increased mercury levels in local fish. For the health investigation 281 volunteers were recruited and examined by a standardized questionnaire, a neurological examination and neuro-psychological tests. A medical score was used consisting of significant factors of mercury intoxication. Mercury exposed workers showed typical symptoms of mercury intoxication, such as movement disorders (ataxia, tremor, dysdiadochokinesia, etc.). Blood, urine and hair samples were taken from any participant and analyzed for mercury. The mercury concentration in the biomonitors was high, partly extreme high in the working population, increased in the population living in the same habitat and low in the control group. By a standard protocol which includes a combination of threshold values of mercury in the biomonitors and a medical sum score the diagnosis of chronic mercury intoxication was made for highly burdened workers (amalgam smelters) in 55% in Sulawesi and in 62% in Kalimantan. Less exposed mineral processors and the general population in the mining areas were also intoxicated to a high percentage.