Review on Timber Portal Frames and Their Architectural Characteristics

Portal frames being the effective methods of construction today, have a lot to study in terms of their efficiency and material behavior. This review paper focuses on Timber as the material for the frames and its relevance. It involves the architectural features and its use in different types of occupancies with its changing character. Keywords: Timber, cost effective, reliable, simple construction.

Reliability and Effectiveness of Sprinkler Systems in Poland

The article presents research on the reliability and effectiveness of sprinkler systems in selected countries around the world as well as results of similar studies conducted in Poland based on the data of the State Fire Service. First discussed are the specifics of analysed data and the problems regarding its acquisition and presentation in a simplified form without proper reflection and the assessment of its specificity, quality, detail, uncertainty and completeness. The next step presents the methodology of detailed data analysis based on full description of fire events and the segregation of fire events into separate subcategories. Such an analysis allowed the presumption that in the five-year period 2013–2017, in 94.4% of relevant fire events sprinkler systems in Poland have demonstrated the achievement of their intended goals. This result is similar to the results achieved in other countries known for high level of fire safety culture (USA, UK, Sweden). In the author’s opinion, this proves the high immanent reliability of these systems, which results from their simple construction and proper maintenance, and not from the country in which they were installed. Taking into account these results, it is recommended that Poland should update its regulations in a manner similar to that of developed countries, so that they take into account in a greater extent the protective value and characteristics of sprinkler systems and the benefits resulting from their application. It is also recommended to increase the detail of publicly collected data on fire protection systems in buildings because better knowledge about the characteristics of these systems in Poland may allow achieving an even higher level of their reliability and effectiveness.

Typical curve with G1 constraints for curve completion

This paper presents a novel algorithm for planar G1 interpolation using typical curves with monotonic curvature. The G1 interpolation problem is converted into a system of nonlinear equations and sufficient conditions are provided to check whether there is a solution. The proposed algorithm was applied to a curve completion task. The main advantages of the proposed method are its simple construction, compatibility with NURBS, and monotonic curvature.

A unique yet technically simple type of joint allows for the high mobility of scorpion tails

Although being one of the most well-known animal groups, functional and constructional aspects of scorpions and especially of their tail (metasoma) have so far been overlooked. This tail represents a special construction, as it consists of five tube-shaped segments made up of strong cuticle, which are movable against each other and thus manoeuvre the notorious stinger both quickly and very precisely in space. This high mobility of an exoskeletal structure can be attributed to the connection between the segments described here for the first time. This joint allows for the twisting and bending at the same time in a single, simple construction: adjoining metasomal segments each possess an almost circular opening posteriorly, where the next segment is lodged. Anteriorly, these segments possess two saddle-like protrusions laterally, which are able to rotate in two directions on the rim of the posterior circular opening of the previous segment allowing for twisting and bending. The metasomal joint is particularly noteworthy since its mechanism can be compared to that of arthropod appendages. The scorpion metasoma is actually the only known case in Chelicerata, in which an entire body section has been modified to perform tasks similar to that of an appendage while containing digestive organs. The joint mechanism can also inspire technical applications, for instance in robotics.

Modelling of Stator Coil–To–Ground Faults in Induction Motor

Three–phase squirrel cage induction motors are the most widespread types of electrical motors which can be found in both industrial and tertiary applications. There are some reasons why they are so often used, such as simple construction, nearly maintenance-free, advantageous price and the possibility to feed them directly from the AC network. Even if their reliability is very high, some unexpected breakdowns can occur during their operation. In this paper, coil–to–ground faults of motor stator winding have been taken into consideration. These failures have been modelled in several points of one stator phase using COMSOL software. As seen from simulation results these failures have a significant impact on current distribution in stator phases causing changes in rotor currents, motor inner torque, speed, etc., depending strongly on the actual point of the failure.

Clifford Spinors and Root System Induction: $$H_4$$ and the Grand Antiprism

Recent work has shown that every 3D root system allows the construction of a corresponding 4D root system via an ‘induction theorem’. In this paper, we look at the icosahedral case of $$H_3\rightarrow H_4$$ H 3 → H 4 in detail and perform the calculations explicitly. Clifford algebra is used to perform group theoretic calculations based on the versor theorem and the Cartan–Dieudonné theorem, giving a simple construction of the $${\mathrm {Pin}}$$ Pin and $${\mathrm {Spin}}$$ Spin covers. Using this connection with $$H_3$$ H 3 via the induction theorem sheds light on geometric aspects of the $$H_4$$ H 4 root system (the 600-cell) as well as other related polytopes and their symmetries, such as the famous Grand Antiprism and the snub 24-cell. The uniform construction of root systems from 3D and the uniform procedure of splitting root systems with respect to subrootsystems into separate invariant sets allows further systematic insight into the underlying geometry. All calculations are performed in the even subalgebra of $${\mathrm {Cl}}(3)$$ Cl ( 3 ) , including the construction of the Coxeter plane, which is used for visualising the complementary pairs of invariant polytopes, and are shared as supplementary computational work sheets. This approach therefore constitutes a more systematic and general way of performing calculations concerning groups, in particular reflection groups and root systems, in a Clifford algebraic framework.