The Composition of the Cuticular and Internal Free Fatty Acids and Alcohols from Lucilia sericata Males and Females

GC, GC–MS, and HPLC–LLSD analyses were used to identify and quantify cuticular and internal lipids in males and females of the blow-fly (Lucilia sericata). Sixteen free fatty acids, seven alcohols and cholesterol were identified and quantitatively determined in the cuticular lipids of L. sericata. Cuticular fatty acids ranged from C6 to C20 and included unsaturated entities such as 16:1n-9, 18:1n-9, 20:4n-3 and 20:5n-3. Cuticular alcohols (only saturated and even-numbered) ranged from C12 to C20 in males and C10 to C22 in females. Only one sterol was found in the cuticular lipids of both males and females. 23 free fatty acids, five alcohols and cholesterol were identified in the internal lipids. Internal fatty acids were present in large amounts—7.4 mg/g (female) and 10.1 mg/g (male). Only traces of internal alcohols (from C14 to C26 in males, from C14 to C22 in females) were found in L. sericata. Large amounts of internal cholesterol were identified in L. sericata males and females (0.49 and 0.97 mg/g of the insect body, respectively)

Autotransformer feeding multi pulse rectifier circuits - methods of its inductance calculation at current feed

Autotransformers used for feeding rectifier circuits are multi-windings and with three columns. Rectifier simulations require leakage inductance matrix of the autotransformer. The methods of leakage inductance calculation of the autotransformers at constant current feed was presented in this article. Method of one 2D window cross section, two 2D windows cross section, and 3D method were discussed. These methods require various software and they have various hardware requirements, but their results are different from each other. This article shows that the reason for the differences among individual elements of leakage inductance matrix, obtained using different calculation methods, are various influences from the main magnetic circuit and differences in zero component. Influences from the main magnetic circuit in the leakage are not dangerous for simulation, because their high values already exist in main magnetic circuit. However it is important to improve eigenvalues of the zero components. The article shows how to improve these eigenvalues. This article is the second one out of four articles presented at this Seminar

The axial flux in the 3D FEM model of the induction machine

Artykuł poświęcony jest wyjaśnieniu zagadnienia powstawania strumienia magnetycznego osiowego w maszynie elektrycznej na przykładzie maszyny indukcyjnej. Przedstawiono podstawy teoretyczne oraz warunki konieczne powstawania strumienia osiowego. W celu ich potwierdzenia obliczeniami, stworzono model 3D maszyny. Wykorzystuje on elementy skończone węzłowe do aproksymacji potencjału skalarnego oraz krawędziowe do aproksymacji potencjału magnetycznego wektorowego. Uwzględnia skos prętów wirnika oraz prądy skrośne w blachach wirnika. Strumień osiowy jest obliczany przez całkowanie potencjału wektorowego wokół wału maszyny. Trójfazowe uzwojenia stojana zasilane są czteroprzewodowo. Przeprowadzono obliczenia stanów po załączeniu maszyny przy różnych prędkościach obrotowych. Symulowano pęknięcia pierścienia oraz pręta. Wyniki symulacji potwierdziły wyprowadzenia teoretyczne.The aim of this paper is to provide the explanation of the phenomenon of axial magnetic flux formation in the electric machine on the example of the induction machine. The theoretical bases and necessary conditions of the axial flux formation were presented. In order to verify theoretical considerations the 3D finite elements model of the induction machine was created. This model utilizes both nodal-based and edge-based formulation respectively for scalar and vector potential approximation. The rotor bar skew and cross currents were taken into consideration. The axial flux was calculated by the integration of the vector potential round the machine shaft. The three phase stator windings were supplied with the four-wire line. The calculations/simulations of the transient states of the machine at different rotational speeds were performed. The rotor bar and end ring faults were simulated. The theoretical considerations were confirmed by the results of simulations

Autotransformer feeding multi pulse rectifier circuits - choosing the circuit to study

Some uncontrolled 18-pulse rectifier circuits feeding by autotransformer were presented in this article. Using simplified methods, excluding leakage inductance, the analysis of this circuits was carried out considering harmonic currents and usage of autotransformer power. As it turned out, simplified results are comparable with exact results, obtained using the simulation of the full circuit with autotransformer inductance. The only exception were mains currents of this circuits and specially their THD coefficient. High level of the 3rd harmonic current in the autotransformer winding shows that additional windings connected in triangle should be used. This article is the first one out of four articles presented at this Seminar

Autotransformer feeding multi pulse rectifier circuits - methods of its inductance calculation at voltage feed

3D finite element method was used in this article to calculate inductance matrix of the autotransformer, divided into eigenvectors [W] and eigenvalues [D]. The autotransformer windings were powered by monoharmonic voltages. This method, as an equivalent of the short circuit tests, is more suitable for calculating small values of leakage inductance. The equivalent are here the methods which are using feeding the autotransformer windings by fixed currents (it is equivalent of the idle running tests). The relationship between autotransformer inductance matrix and ripple was obtained. It appeared, that eigenvectors matrix of the inductance matrix of the autotransformer is almost independent from the ripple, and its elements are real numbers. It was treated as transformation matrix: flux linkages - windings currents flows. Relation from the ripple of the eigenvalues of inductance matrix was synthesized by means of ladder circuits. As a result the exact substitute diagram of the autotransformer was obtained. This article is the third one out of four articles presented at this Seminar

24-pulse rectifier with non-coupled chokes

Operating principle of the 24-pulse rectifier circuit with non-coupled chokes was presented in this article. Thanks to the work of this circuit we can obtain small higher harmonics currents content of the rectified current. Transistors T1, T2, T3, T4 were used to regulate the value of rectified current. Fulfillment of their control by using the PWM method regulates the rectified current. In addition this paper provides the ability of such controlling of transistors work, that the mains current of the circuit contains the smallest possible higher harmonics content, expressed by small value of the THD coefficient

Electronic filtration of the direct current

The circuit, which allows to reduce the current ripples rectified by the 6-pulse rectifier, was presented in this article. Usually for this purpose we can use the choke, but it makes some difficulties and increases costs. In this paper we present the alternative way of the current smoothing, which uses the capacitor, with controlling electronic circuit, instead of choke to smooth the current. The presented simulations shows, that the method of the controlling of the switching on that capacitor in the direct current circuit provides effective method to reduce the higher harmonics of the rectified current. The size of the device which uses electronic filtration of the direct current, presented in this paper, is also smaller than the device with chokes