The Diagenesis of Plant Lipids during the Formation of the Krepoljin Coal Basin(Serbia)—Using Multivariate Statistical Analysis in the Saturated Biomarkers

The composition of the saturated hydrocarbon fraction of soluble organic matter （bitumen） from the Krepoljin brown coal basin （East Serbia） of Miocene age was investigated. The Krepoljin basin is especially interesting from a geochemical point of view. Namely, by the end of Tertiary Period, the basin was covered by powerful Mesozoic formations of great possibilities, the bedding became hermetically enclosed and protected from subsequent external influences. The nature of early diagenetic processes in the environment with abundant accumulation of organic substance is defined by the molecular content of bitumen through the connections of molecular structures to potential precursors in paleoplant phylla, as well as by the degree of their diagenetic transformations. The hierarchy of parameters based on molecules of saturated hydrocarbons was determined by applying the principal component analysis to the soluble organic matter. The most significant, most ＂loadings＂ values of component CI, are the plant types such as precursors or participants in early diagenetic transformations of steranes Cs27-algal precursor material, Cs28-moulds, Cs29-higher land and water plants; resinous from the group of higher plant gymnosperms （G）; also triterpanes a and β-amirindicotyledonous angiosperms （A） and bacterial and/or terrestrial plants population represented by hopanes/moretanes; as well as the parameters which describe the degree of diagenetic/maturation transformation of precursor biomass, and based on next reactions： （1） shifting of methyl group, influenced by the inorganic sediment constitutents, sterane-rearranged steranes, （2） isomerization in the ring system, ααα→βββ C29 sterane as well as （3） isomerization on chiral center of the side chain sequence R→S C29 sterane S/（S＋R）. Additionally, a pyrite-derived inhibitory effect on the rearrangment of C29 steranes must be taken into account, but not on triterpanes reaction. Non- appearance of statistically important correlations, before all with maturational depended parameters, and after all also with source indicators contributies to the affirmation of the newly-suggested parameter α-Phyllocladane/S27 as the real source biomarker of coal. Indicators derived from the distribution and abundance of n-alkanes and isoprenoid alkanes are of less significance in hierarchy of parameters.

Research of a fractional-turn ratio saturable pulse transformer and its application in a microsecond-range pulse modulator

As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is constructed and analyzed in this paper.Preliminary experimental results show that if the primary energy storage capacitors are charged to 300 V,an output voltage of about 19 kV can be obtained across the capacitor connected to the secondary windings of a fractional-tum ratio saturable pulse transformer.Theoretical and experimental results reveal that this kind of pulse transformer is not only able to integrate a step-up transformer and a magnetic switch into one device,but can also lower the saturable inductance of its secondary windings,thus leading to the relatively high step-up ratio of the pulse transformer.Meanwhile,the application of the fractional-turn ratio saturable pulse transformer in a μs range pulse modulator as a voltage step-up device and main switch is also included in this paper.The demonstrated experiments display that an output voltage with an amplitude of about 29 kV,and a 1.6 μs pulse width can be obtained across a 3500 Ω resistive load,based on a pulse modulator,if the primary energy storage capacitors are charged to 300 V.This compact fractional-turn ratio saturable pulse transformer can be applied in many other fields such as surface treatment,corona plasma generation and dielectric barrier discharge.

A High Power Semiconductor Switch RSD for Pulsed Power Applications

High power switch is one of the most important components in pulsed power technology. The RSD （Reversely Switched Dynistor）, turned on by a thin layer of an electron-hole plasma, is a high power semiconductor switch. In this study, the RSD turn-on conditions were investigated by numerical analysis and device simulation as well as the experiments conducted to validate the turn-on conditions. A design of a triggering high-voltage RSD is presented based on a saturable transformer.

Impedance Model for Instability Analysis of LCC-HVDCs Considering Transformer Saturation

In line commutated converter based high-voltage direct current(LCC-HVDC)transmission systems,the transformer saturation can induce harmonic instability,which poses a serious threat to the safe operation of the power system.However,the nonlinear characteristics of the power grids introduced by the transformer saturation considerably limit the application of the conventional analysis methods.To address the issue,this paper derives a linear model for the transformer saturation caused by the DC current due to the converter modulation.Afterwards,the nonlinear characteristics of power grids with the transformer saturation is described by a complex valued impedance matrix.Based on the derived impedance matrix,the system harmonic stability is analyzed and the mechanism of the transformer saturation induced harmonic instability is revealed.Finally,the sensitivity analysis is conducted to find the key factors that influence the system core saturation instability.The proposed impedance model is verified by the electromagnetic transient simulation,and the simulation results corroborate the effectiveness of the proposed impedance model.Index TermsLine commutated converter based high voltage direct current(LCC-HVDC),transformer saturation,harmonic instability,impedance model.

Transmission Line Distance Protection Under Current Transformer Saturation

Conventional transmission line distance protection approaches are subject to malfunction under reverse fault-induced current transformer(CT) saturation for the typically employed breaker-and-a-half configuration. This paper addresses this issue by proposing a new distance protection approach that combines the blocking and unblocking criteria of distance protection based on the values of incomplete differential current,operation voltage, and current harmonic content. The proposed approach is verified by theoretical analysis, dynamic simulation testing, and field operation to ensure that the obtained distance protection is reliable and refrains from operating unnecessarily under reverse fault-induced CT saturation in the breaker-and-ahalf configuration. Meanwhile, the proposed approach is demonstrated can operate reliably when forward faults occur or various reverse faults are converted to forward faults.

Deuterium depth distribution study in Yb

The deuterium depth distribution for a 20 keV/D D_3~＋beam implanted into ytterbium（Yb） at a temperature between 300 and 340 K was studied using the D（d,p）T reaction.By analyzing the proton yields,the deuterium depth distribution from the front surface to 500 nm depth was found.The results indicate that an equilibrium deuterium distribution region from the front surface to a depth approximately equal to the mean range of implanted deuterons was formed in Yb during the implantation.The deduced deuterium concentration in the equilibrium deuterium distribution region was D/Yb = 22%.