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

The F5 Criterion revised

The purpose of this work is to generalize part of the theory behind Faugere's "F5" algorithm. This is one of the fastest known algorithms to compute a Groebner basis of a polynomial ideal I generated by polynomials f_{1},...,f_{m}. A major reason for this is what Faugere called the algorithm's "new" criterion, and we call "the F5 criterion"; it provides a sufficient condition for a set of polynomials G to be a Groebner basis. However, the F5 algorithm is difficult to grasp, and there are unresolved questions regarding its termination. This paper introduces some new concepts that place the criterion in a more general setting: S-Groebner bases and primitive S-irreducible polynomials. We use these to propose a new, simple algorithm based on a revised F5 criterion. The new concepts also enable us to remove various restrictions, such as proving termination without the requirement that f_{1},...,f_{m} be a regular sequence.Comment: Originally submitted by Arri in 2009, with material added by Perry since 2010. The 2016 editions correct typographical issues not caught in previous editions bring the theory of the body into conformity with the published version of the pape

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

NON-FARM LABOR SUPPLY: THEORY AND ESTIMATION

During the last decade considerable research has been carried out on the non-farm labor supply of farm households. New insights and hypotheses on the economic behavior of households, known as "new home economics," and progress in applying more sophisticated estimation techniques have stimulated these research activities. The focus of this paper is the standard neoclassical model of labor supply and a corresponding empirical research strategy. The empirical model refers to household-level data from West Germany. As the results reveal, farm households decide on the allocation of their resources in a very rational manner. This shows their high capacity and flexibility to adjust to varying economic circumstances.Labor and Human Capital,