Die Design for Near-Net Shape Forging

This paper discusses the use of conventional forging equipment for the manufacture of precise forging without flash. An analysis is presented of the factors influencing the forging process and the conditions for establishing this technique in a forge based on practical experience at the SKODA Auto forge. The main problem is usually the excess volume of billet material. Three basic forms of die design for overload protection are illustrated and discussed

THE INFLUENCE OF SILAGE ADDITIVES FOR QUALITATIVE PARAMETERS OF CLOVER-GRASS SILAGES

We observed the infl uence of silage additives for choice qualitative parameters at 109 samples of clovergrass silages in working conditions. We evaluated total classifi cation and categorization to quality classes according to fermentation process. It has been found out positive effect of the silage additives for fermentation class and for total silage quality of silages. This positive effec t has been more considerable at classifi cation to the fermentation classes at clover-grass silages. The high content of crude fi bre decreased fermentation results and total silage quality at test clover-grass silages. The greatest (deterioration) infl uence for clasifi cation to total quality class has crude fi bre content. It is see from correlation coefi cient at clover-grass silages – r = 0,75 (P < 0,05). The weak dependence r = 0,37 (P < 0,05) was detected between fermentation class and acetic acid content. It was detected large dependence between fermentation class and butyric acid content r = 0,73 (P < 0,05)

A TFETI Domain Decomposition Solver for Elastoplastic Problems

We propose an algorithm for the efficient parallel implementation of elastoplastic problems with hardening based on the so-called TFETI (Total Finite Element Tearing and Interconnecting) domain decomposition method. We consider an associated elastoplastic model with the von Mises plastic criterion and the linear isotropic hardening law. Such a model is discretized by the implicit Euler method in time and the consequent one time step elastoplastic problem by the finite element method in space. The latter results in a system of nonlinear equations with a strongly semismooth and strongly monotone operator. The semismooth Newton method is applied to solve this nonlinear system. Corresponding linearized problems arising in the Newton iterations are solved in parallel by the above mentioned TFETI domain decomposition method. The proposed TFETI based algorithm was implemented in Matlab parallel environment and its performance was illustrated on a 3D elastoplastic benchmark. Numerical results for different time discretizations and mesh levels are presented and discussed and a local quadratic convergence of the semismooth Newton method is observed

VLIV ADITIV NA VYBRANÉ KVALITATIVNÍ UKAZATELE JETELOTRAVNÍCH SILÁŽÍ

We observed the infl uence of silage additives for choice qualitative parameters at 109 samples of clovergrass silages in working conditions. We evaluated total classifi cation and categorization to quality classes according to fermentation process. It has been found out positive effect of the silage additives for fermentation class and for total silage quality of silages. This positive effec t has been more considerable at classifi cation to the fermentation classes at clover-grass silages. The high content of crude fi bre decreased fermentation results and total silage quality at test clover-grass silages. The greatest (deterioration) infl uence for clasifi cation to total quality class has crude fi bre content. It is see from correlation coefi cient at clover-grass silages – r = 0,75 (P < 0,05). The weak dependence r = 0,37 (P < 0,05) was detected between fermentation class and acetic acid content. It was detected large dependence between fermentation class and butyric acid content r = 0,73 (P < 0,05).U 109 vzorků jetelotravních siláží byl v provozních podmínkách sledován vliv silážních aditiv na kvalitativní ukazatele. Posuzováno bylo jednak celkové zatřídění a zařazení do tříd jakosti podle fermentačního procesu. U silážovaných krmiv bylo potvrzeno, že aditiva mají pozitivní vliv na fermentační proces a tím i na celkovou kvalitu siláží. Tento pozitivní vliv byl ještě více patrný na zatřídění do třídy fermentace. Vysoký obsah vlákniny u sledovaných silážovaných krmiv zhoršoval fermentační výsledky i celkovou jakost siláží. Z korelačních koefi cientů hodnotící jetelotravní siláže je patrné, že největší (zhoršující) vliv na zařazení do celkové třídy jakosti má množství vlákniny r 0,75 (P < 0,05). Mírná závislost r 0,37 (P < 0,05) byla zjištěna mezi třídou fermentace a obsahem kyseliny octové. Mezi třídou fermentace a obsahem kyseliny máselné byla zjištěna velká závislost r 0,73 (P < 0,05)

The Influence of Management on Health Status of \u3cem\u3eFestuca Rubra\u3c/em\u3e in Mountain Meadows

Snijders & Winkelhorst (1996) investigated swards in West Europe and showed that it was not the snow mould (Microdochium nivale) but other species of the genus Fusarium (F. cerealis (Cooke) Sacc., F. graminearum Schwabe, F. culmorum (Wm. G. Sm.) Sacc. and F. acuminatum Ellis & Everh.) that caused serious damage to grasslands where Lolium perenne L. and Festuca rubra L. were dominant components. In this study the spread and harmfulness of pathogeneous fungi involved in damage to and death of some species (Festuca rubra L., Holcus mollis L.) in grass swards was examined

Electrical characterization of fluorinated benzothiadiazole based conjugated copolymer – a promising material for high-performance solar cells

Measurements of electrical conductivity, electron work function, carrier mobility of holes and the diffusion length of excitons were performed on samples of conjugated polymers relevant to polymer solar cells. A state of the art fluorinated benzothiadiazole based conjugated copolymer (PBDTTHD − DTBTff) was studied and benchmarked against the reference polymer poly-3-hexylthiophene (P3HT). We employed, respectively, four electrode conductivity measurements, Kelvin probe work function measurements, carrier mobility using charge extraction by linearly increasing voltage (CELIV) measurements and diffusion length determinaton using surface photovoltage measurements

Studies of Charge Exchange in a High‐Pressure Pulsed Electron Impact Source

This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/56/3/10.1063/1.1677327.A high pressure pulsed ion source has been used in a time‐of‐flight mass spectrometer in order to study the charge exchangereactions in Ar–H2 and Ar–D2 systems using the ion source in the Čermák mode of operation. As the source was used in a pulsed mode, it was possible to identify the various secondary ions arising from the charge exchangereactions in these systems. Very good agreement has been shown to exist between the experimental results and simple theoretical deductions. Calculations have been made to determine the cross sections for the charge exchangereactions between the various species from the experimental data

Thin static charged dust Majumdar-Papapetrou shells with high symmetry in D >= 4

We present a systematical study of static D >= 4 space-times of high symmetry with the matter source being a thin charged dust hypersurface shell. The shell manifold is assumed to have the following structure S_(beta) X R^(D-2-beta), beta (in the interval ) is dimension of a sphere S_(beta). In case of (beta) = 0, we assume that there are two parallel hyper-plane shells instead of only one. The space-time has Majumdar-Papapetrou form and it inherits the symmetries of the shell manifold - it is invariant under both rotations of the S_(beta) and translations along R^(D-2-beta). We find a general solution to the Einstein-Maxwell equations with a given shell. Then, we examine some flat interior solutions with special attention paid to D = 4. A connection to D = 4 non-relativistic theory is pointed out. We also comment on a straightforward generalisation to the case of Kastor-Traschen space-time, i.e. adding a non-negative cosmological constant to the charged dust matter source.Comment: Accepted in Int. J. Theor. Phy