Magnetit in Eisenerzsintern

Eigenschaften von Magnetit. Erörterung bisheriger Untersuchungsergebnisse an Hand des Schrifttums. Erscheinungsbild des Magnetits in selbstgängigen und hochbasischen Sintern. Bildungsverhältnisse bei Anwesenheit von Calcium, Magnesium und Aluminium. Einfluβ der Bedingungen während des Sinter- und Abkühlungsvorganges auf die Kristallisation des Magnetits. Rückschlüsse auf Sinterfestigkeit und Reduzierbarkeit.     

The Stokes coagulation model

The coagulation problem related to the kinetic theory of motion of particles according to the Boltzmann equation. The coagulation equation brought from the infinite space to the limited one. A real boundary condition for the Stokes coagulation limiting the purified zones without the nonmetallic inclusions. The equivalent relative boundary conditions. The Stokes coagulation as function of time.     

Effect of protein level and methionine supplementation on dairy cows during the transition period

Cows experience a significant negative protein balance during the first 30 d of lactation. Given the functional effects of AA on health, especially in challenging periods such as calving, higher levels of protein and specific AA in the diet may act to improve health and feed intake. The response of dairy cows to 3 protein supplementation strategies during the transition period and through the first 45 d in milk was evaluated. The final data set had 39 Holstein cows blocked based on parity (primiparous vs. multiparous) and expected calving and randomly assigned within each block to one of 3 dietary treatments: low protein (LP), high protein (HP), or high protein plus rumen-protected methionine (HPM). Treatments were offered from d ?18 ± 5 to 45 d relative to parturition. Pre- and postpartum diets were formulated for high metabolizable protein (MP) supply from soybean meal, and HP and HPM provided higher MP balance than LP. Preplanned contrasts were LP versus HP+HPM and HP versus HPM. Significance was declared at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. Cows fed HP and HPM had greater fry matter intake (DMI) prepartum than LP (+2 kg/d), and there was a trend for greater DMI with HPM than with HP (+1.6 kg/d). Body weight and condition score before and after calving did not differ among treatments. High protein (HP and HPM) tended to increase milk yield during the first 45 d of lactation (+1.75 kg/d), increased milk lactose content and urea-N in milk and plasma, tended to increase blood BHB 14 d postpartum, and tended to reduce milk/DMI compared with LP. Blood concentrations of calcium at calving and of glucose, and nonesterified fatty acids pre- and postpartum did not differ. High protein induced lower concentration of plasma IL-1 at calving and lowered blood lymphocytes 21 d postpartum, suggestive of a reduced inflammatory status compared with LP. The concentrations of IL-10, tumor necrosis factor alpha, and other hemogram variables did not differ among treatments. Addition of rumen-protected methionine to the HP diet did not alter milk yield but increased fat and total solids concentrations. The rumen-protected methionine had no effect on blood metabolites and immunity markers, with the exception of increased pre-partum insulin concentrations. The data indicate that dairy cows around calving respond positively to an increase in the supply of MP and to rumen-protected methionine supplementation of the HP diet by increasing intake and improving immune status.     

Modeling domains using Bézier surfaces in plane boundary problems defined by the Navier–Lame equation with body forces

The paper presents an effective and powerful way of solving boundary problems modeled by the Navier–Lame equation with body forces. We considered domains of complex shapes defined using Bézier surfaces, which are well-known in computer graphics. Obtained results were compared with analytical and numerical solutions received by the boundary element method (BEM). The analysis of the results has confirmed reliability and effectiveness of the proposed approach and its applicability to a variety of practical problems.     

Activation Energy in Hot Forming and Recrystallization Models for Magnesium Alloy AZ31

Kinetics of the dynamic, as well as postdynamic recrystallization of the wrought magnesium alloy AZ31, was ascertained. Continuous compression tests associated with the study of dynamic recrystallization were realized at temperatures from 523 to 723 K and at the strain rates from 0.001 to 10 s^?1. The activation energy in hot forming was determined as Q = 158 kJ/mol for stress-strain curves of conventional shape, or Q = 146 kJ/mol for stress-strain curves with the concave initial phase affected by twinning. If the Zener-Hollomon parameter Z > 9.1 × 10¹² s^?1 the deformation necessary for the initiation of dynamic recrystallization is almost independent on the forming parameters. Using the results of the stress relaxation tests, equations describing the kinetics of metadynamic recrystallization and the grain size originated in such a way were developed and the effect of individual variables was evaluated.     

Synthesis of 2-Propanoyl-5-Norbornene in Pyridinium Ionic Liquids Catalyzed by Yttrium Salts

Abstract  

The use of pyridinium ionic liquids as solvent and catalytic systems based on yttrium salts dissolved in pyridinium ionic liquids for the synthetically important Diels–Alder reaction between cyclopentadiene and ethyl-vinyl ketone was studied. Both chloride and triflate were active catalysts in cycloaddition, strongly improving the reaction rate and stereoselectivity. The catalytic system—1 mol% YCl₃/[C₄-3-C₁py][OTf] (N-butyl-3-methylpyridinium trifluoromethanesulfonate) proved to be stable under recycling conditions.     

Effects of metabolizable protein supply and amino acid supplementation on nitrogen utilization, milk production, and ammonia emissions from manure in dairy cows

Two experiments were conducted with the objective of investigating the effects of rumen-protected methionine (RPMet) supplementation of metabolizable protein (MP)-deficient or MP-adequate but Met-deficient diets on dairy cow performance. Experiment (Exp.) 1 utilized 36 Holstein dairy cows blocked in 12 blocks of 3 cows each. Cows within block were assigned to one of the following dietary treatments: (1) MP-adequate diet [AMP; positive MP balance according to the National Research Council (2001) dairy model]; (2) an MP-deficient diet supplemented with 100g of rumen-protected Lys (RPLys)/cow per day (DMPL); and (3) DMPL supplemented with 24g of RPMet/cow per day (DMPLM). Experiment 2 utilized 120 Holstein cows assigned to 6 pens of 20 cows each. Pens (3 per treatment) were assigned to one of the following dietary treatments: (1) AMP diet supplemented with 76g of RPLys/cow per day (AMPL); and (2) AMPL (74g of RPLys/cow per day) supplemented with 24g of RPMet/cow per day (AMPLM). Each experiment lasted for 10wk (2-wk adaptation and 8-wk experimental periods) following a 2-wk covariate period (i.e., a total of 12wk). In Exp. 1, the MP-deficient diets decreased apparent total-tract nutrient digestibility but had no statistical effect on dry matter intake (DMI), milk yield, or milk fat percentage and yield. Compared with AMP, DMPL decreased milk protein content; both DMPL and DMPLM diets decreased milk protein yield. Urinary N losses and milk urea-N concentration were decreased by the MP-deficient diets compared with AMP. The ammonia emitting potential of manure from the MP-deficient diets was decreased by about 37% compared with that of AMP manure. Plasma Lys and Met concentrations were not affected by treatment, but concentrations of His, Thr, and Val were lower for the MP-deficient diets compared with AMP. In Exp. 2, the AMPLM diet had lower milk yield than AMPL due to numerically lower DMI; no other effects were observed in Exp. 2. In conclusion, feeding MP-deficient diets supplemented with RPLys and RPMet did not statistically decrease milk yield in dairy cows in Exp. 1. However, without RPMet supplementation, milk protein content was decreased compared with the MP-adequate diet. Other amino acids, possibly His, may limit milk production in MP-deficient, corn or corn silage-based diets. A summary of 97 individual cow data from trials in which MP-deficient diets were fed suggested the National Research Council (2001) model under-predicts milk yield in cows fed MP-deficient diets (MP balance of -20 to -666g/d) in a linear manner: milk yield under-prediction [National Research Council (2001) MP-allowable milk yield, kg/d - actual milk yield, kg/d] = 0.0991 (±0.0905) + 0.0230 (±0.0003) × MP balance, g/d (R(2)=0.99).     

Generation of Nonlinear Force Driven Blocks from Skin Layer Interaction of Petawatt-Picosecond Laser Pulses for ICF

The discovery of the essential difference of maximum ion energy for TW-ps laser plasma interaction compared with the 100 ns laser pulses led to the theory of a skin layer model where the control of prepulses suppressed the usual relativistic self-focusing.The subsequent generation of two nonlinear force driven blocks has been demonstrated experimentally and in extensive numerical studies where one block moves against the laser light and the other block into the irradiated target.These blocks of nearly solid state density DT plasma correspond to ion beam current densities exceeding 10^10 A/cm^2 where the ion velocity can be chosen up to highly relativistic values.Using the results of the expected ignition of DT fuel by light ion beams,a selfsustained fusion reaction front may be generated even into uncompressed solid DT fuel similar to the Nuckolls-Wood scheme where 10 kJ laser pulses produce 100 MJ fusion energy.This new and simplified scheme of laser-ICF needs and optimisation of the involved parameters.     

A separation of the boundary geometry from the boundary functions in PIES for 3D problems modeled by the Navier–Lamé equation

In this paper, we present a modification of the Somigliana identity for the 3D Navier–Lamé equation in order to analytically include in its mathematical formalism the boundary represented by Coons and Bézier parametric surface patches. As a result, the equations called the parametric integral equation system (PIES) with integrated boundary shape are obtained. The PIES formulation is independent from the boundary shape representation and it is always, for any shape, defined in the parametric domain and not on the physical boundary as in the traditional boundary integral equations (BIE). This feature is also helpful during numerical solving of PIES, as from a formal point of view, a separation between the approximation of the boundary and the boundary functions is obtained. In this paper, the generalized Chebyshev series are used to approximate the boundary functions. Numerical examples demonstrate the effectiveness of the presented strategy for boundary representation and indicate the high accuracy of the obtained results.     

Untersuchung über die metallurgischen Eigenschaften und das Schwellverhalten von Eisenerzen,Sintern und Pellets

Verhalten von Erzen, Sintern und Pellets während der Reduktion außerhalb des Hochofens und unter den Bedingungen während der Verhüttung. Einfluß der Temperatur und des Reduktionsgrades auf die Festigkeit, Porigkeit und das Schwellen von Erzen, Sintern und Pellets. Untersuchungen mit Hilfe eines Rasterelektronenmikroskops und einer Mikrosonde.