Facettes of terrace-building in the culture of the Pero, Longuda and Tula people in north-eastern Nigeria

In the culture of the Pero, Longuda and Tula People in the south-eastern part of Bauchi State, north-eastern Nigeria, terraces are found as traditional means to improve the environmental condition and to secure the survival of the people. To classify those terraces according to their form and function, the techniques and customs of their building and the traditional structures of their development they have to be compared in the context of their own culture. The paper gives a few examples showing that the importance of terraces for the historic and religious concepts of the Pero, Longuda and Tula People is expressed through a tight network of oral traditions, social and religious customs and structures of belief and explanation, which, once they were woven together, eventually build what a malam from Tula called a glue of inheritance, identity, integrity, continuity and security

Kinetic theory of quantum transport at the nanoscale

We present a quantum-kinetic scheme for the calculation of non-equilibrium transport properties in nanoscale systems. The approach is based on a Liouville-master equation for a reduced density operator and represents a generalization of the well-known Boltzmann kinetic equation. The system, subject to an external electromotive force, is described using periodic boundary conditions. We demonstrate the feasibility of the approach by applying it to a double-barrier resonant tunneling structure

Model vrtulové pohonné jednotky s variabilním úhlem náběhu

The contribution deals with the mathematical model of the propeller drive unit with variable pitch. The introductory part of the article aims at a general mathematical description of the internal structure of the aircraft propulsion. The DC motor and propeller model are presented in next chapter. The last part presents the comparison between MatLab Simulink model and experimental laboratory stand of variable pitch drive unit. Variable pitch propeller drive is useful to minimize power consumption. The use of these units for the drones is only experimental in terms of optimization of energy consumption.V tomto článku je popsán matematický model vrtulové pohonné jednotky s variabilním úhlem náběhu vrtulových listů (VPPU). V úvodní části článku je popsán základní matematický model celé pohonné jednotky. V další části je popsán model motoru ve vazbě s vrtulí. V závěru článku je prezentován výstup simulací v MatLab Simulink v porovnání s výstupy s laboratorního standu. Význam VPPU je v možné úspoře energie letounu. Využití těchto jednotek pro pohon dronů za účelem snižování spotřeby energie je v současnosti jen na experimentální úrovni

Fission decay of N = Z nuclei at high angular momentum: 60^{60}Zn

Using a unique two-arm detector system for heavy ions (the BRS, binary reaction spectrometer) coincident fission events have been measured from the decay of $^{60}$Zn compound nuclei formed at 88MeV excitation energy in the reactions with $^{36}$Ar beams on a $^{24}$Mg target at $E_{lab}(^{36}$Ar) = 195 MeV. The detectors consisted of two large area position sensitive (x,y) gas telescopes with Bragg-ionization chambers. From the binary coincidences in the two detectors inclusive and exclusive cross sections for fission channels with differing losses of charge were obtained. Narrow out-of-plane correlations corresponding to coplanar decay are observed for two fragments emitted in binary events, and in the data for ternary decay with missing charges from 4 up to 8. After subtraction of broad components these narrow correlations are interpreted as a ternary fission process at high angular momentum through an elongated shape. The lighter mass in the neck region consists dominantly of two or three-particles. Differential cross sections for the different mass splits for binary and ternary fission are presented. The relative yields of the binary and ternary events are explained using the statistical model based on the extended Hauser-Feshbach formalism for compound nucleus decay. The ternary fission process can be described by the decay of hyper-deformed states with angular momentum around 45-52 $hbar$.Comment: 23 pages, 25 figure

Optimizing of metal foam design for the use as a heat exchanger

The work deals with possibilities of using this specific material. It is focused on cast metal foams with a regular arrangement of internal cells and it refers to already used casting technologies - the production of metal foamswith the aid of sand cores. Metal foamsare used in many industries, such as: automotive, aerospace, construction, power engineering. They have unique propertiesand due to lower weight with sufficient strength and greater contact surface can be used, for example, for the conduction of heat. This article deals with the useof the metal foam as a heat exchanger. The efficiency of the heat exchanger depends on its shape and size and therefore the study is focused first on the optimization of the shape before the proper manufacture.Web of Science6341881187