Breakdown Distribution Research Articles

Thermoelectric coupling analysis of high-voltage breakdown industrial frequency pyrolysis in Fuyu oil shale

A high voltage can achieve the electrical breakdown of an oil shale, and a heating channel is formed inside the oil shale. Subsequently, the industrial electrical frequency is used to heat the oil shale with the produced plasma and the inner surface of the conductive carbonization channel, which then causes the oil shale to crack. A three-dimensional coupling model of an oil shale is established by the finite element analysis software, and the temperature field distribution of a high-voltage breakdown of an oil shale is obtained by numerical calculations. The reliability of the numerical simulation is verified by laboratory tests. When the voltage is 1000 V, the breakdown current in the oil shale is 22 A. After heating for 6 min, the heating channel temperature of the oil shale reaches 643 °C. Within a 25-mm heating channel length, the temperature reaches 347 °C, which meets the demand of oil shale pyrolysis. Combined with the numerical simulations and experimental results, the high-voltage industrial-frequency pyrolysis oil shale has high heating efficiency and high energy utilization efficiency. Thermoelectric coupling analysis is an effective way to study the high-voltage-breakdown industrial-frequency pyrolysis of oil shale.

FINANCIAL AND CREDIT IMPERATIVES OF ALTERGLOBALIZATION THE EMERGING MARKETS

The article analyzes the financial and credit imperatives of alterglobalization the emerging markets. In the study, it is researched the theory of financial globalization and there are established advantages, benefits and disadvantages of financial globalization for emerging markets. There are defined the main conditions and risks of global financial stability and there are analyzed the capital flows to emerging market economies. In the article, it is researched that the combination of declining global trade and growth would increase corporate vulnerability. It is concluded the distribution of government debt breakdown of emerging market economies in foreign currency and nonresident holdings of local currency. In the research, it is established a correlation between emerging market economy and advanced economy volatilities. In the study, it is proved that disadvantages of financial globalization include availability of crises, shocks, risks, external risks and nonliquidity. In the article, it is developed the financial-credit imperatives of alterglobalization the emerging markets and it is argued the transition of emerging markets to an alternative global model of economic development.

Prediction of lightning impulse voltage induced breakdown in vacuum interrupters

A concept to predict the Lightning Impulse Voltage (LIV) breakdown probability of medium voltage Vacuum Interrupter (VI) tubes has been developed and tested for the first time employing the Voltage Holding Prediction Model (VHPM) originally formulated at Consorzio RFX. The VHPM is capable to calculate the Weibull breakdown probability curve of any multi-electrode multi-voltage system insulated in vacuum under dc voltage. Even though the possibility to employ the VHPM in the prediction of voltage breakdown under LIV conditions is not straightforward, the potential benefits of the VHPM usage in VI tube technology with regard to development, design and testing at medium and high voltage levels, strongly recommend the assessment of VHPM under LIV conditions. The paper aims to describe the methodology adopted to identify experimentally the VHPM parameters to be employed in such a novel application to assess its prediction capability. The measurements have been done in the Siemens Berlin VI tube factory test stand for LIV, compliant with the IEC standard. Different vacuum tube types manufactured by Siemens were investigated. The main difficulty was to obtain, with such a test bed, voltage breakdown distributions well fitted by a Weibull Distribution — upon which the VHPM is based — primarily due to the difficulty to reach a well-defined end of the conditioning test sequence preceding the relevant voltage breakdown test sequence suitable to be analyzed by the VHPM. Nevertheless, the VHPM prediction resulted in reasonable agreement with the measured probability curves. Finally, investigating VI tubes with spiral-type Radial Magnetic Field (RMF) contacts, characterized by a geometry strongly deviating from axial 2-D symmetry, the first implementation of a full 3-D version of the VHPM has been tested.

Dielectric properties of sandwich-structured BaTiO3/polyimide hybrid films

In this paper, sandwich structured polyimide hybrid films were prepared by layered coating, in which middle layer is different volume fraction BT/PI monolayer film and both the bottom and the top layers are pure PI. Compared with monolayer hybrid films, sandwich structured hybrid films exert much lower dielectric loss and conductivity, which owe to pure PI layers as insulation layers effective block off conductive paths of middle layer. Besides, the SEM images show hybrid film has obvious layering and without defects. This sandwich structure can redistribute electric field between three layers to optimize breakdown performance, which correspond to data processed by Weibull breakdown distribution. When the intermediary volume fraction is 3 vol%, the breakdown strength of sandwich structured hybrid films is 344.26 kV/mm, which is 1.26 times enhancement than pure PI film. In addition, based on the improvement of the breakdown strength, the energy storage density of hybrid films is improved significantly. When the electric field is 344.26 kV/mm, its energy storage density reached 1.94 J/cm3, which is 1.72 times enhancement of pure PI film.

Soil aggregate breakdown in response to wetting rate during the inter-rill and rill stages of erosion in a contour ridge system

Wetting rate is one of the major factors determining the magnitude of slaking force in soils. Differences in wetting rate result in varying degrees of soil aggregate breakdown that alters the distribution of particle sizes in sediment. The objective of the present study was to determine how various wetting rates affected soil aggregate breakdown and soil fraction distribution in a contour ridge system. In the simulated rainfall experiment, the breakdown of 16 sizes soil aggregate was evaluated under five wetting rates (10, 20, 30, 60, and 90mmh−1) at different stages of erosion. The greatest fraction of sediment was microaggregate (accounting for 63.66%–69.19% of the total), and 20–50μm and 50–100μm classes were dominant within microaggregate fraction. The obviously increased loss of sediment from these two sizes occurred mainly as a result of the breakdown of 2–5mm and 1–2mm fractions during the inter-rill stage of erosion, and it was induced by the collapse of 0.25–0.5mm, 0.5–1mm, and 100–200μm aggregates during rill erosion. Critical wetting rate thresholds of 20mmh−1 controlled the breakdown of 2–5mm and 1–2mm fractions during the inter-rill stage. During the rill stage, when the wetting rate exceeded 10mmh−1, the breakdown of 0.25–0.5mm and 0.5–1mm sizes intensified and the critical threshold for the collapse of 100–200μm aggregate was 20mmh−1. These findings enhance our understanding of the breakdown mechanism of soil aggregates and supply guidance for implementing contour ridge systems.

БОТАНІКО-ГЕОГРАФІЧНА ХАРАКТЕРИСТИКА ВИДІВ РОДУ THYMUS L. (LAMIACEAE) У ФЛОРІ ЗАХІДНИХ РЕГІОНІВ УКРАЇНИ

The paper presents the results of botanical-geographical analysis of Thymus L. species in the flora of western regions of Ukraine. The study of current thyme distribution on this territory shows that a significant part of the identified species is confined to the Transcarpathian lowland, Ukrainian Carpathians, Pre-Carpathians and the southwestern part of Podillya height. Here is located one of the centers of Thymus diversity in Ukraine. Distribution of the range-bordered species within the studied area has been clarified: Th. serpyllum L. emend. Mill., Th. pannonicus All., Th. glabrescens Willd., and Th. alternans Klokov. It was revealed that Thymus species in the flora of western regions of Ukraine are featured in relatively high variety of geographic range types. Based on the zonal characteristics, altitudinal breakdown, and regional distribution patterns, the species with temperate-submeridional, plain, and European types of range, respectively, are predominant. According to the climate affinity, the ranges of most Thymus species in this area are inclined towards regions with oceanic climate. Thus, thyme species composition in western regions of Ukraine shows closer affinity to thyme diversity in the flora of Central Europe than of the eastern and south-eastern regions of Ukraine. The analysis of geographical elements shows the dominance of species belonging to the mountain type of geoelements.

Technoeconomic Assessment of an Advanced Aqueous Ammonia-Based Postcombustion Capture Process Integrated with a 650-MW Coal-Fired Power Station.

Using a rigorous, rate-based model and a validated economic model, we investigated the technoeconomic performance of an aqueous NH3-based CO2 capture process integrated with a 650-MW coal-fired power station. First, the baseline NH3 process was explored with the process design of simultaneous capture of CO2 and SO2 to replace the conventional FGD unit. This reduced capital investment of the power station by US$425/kW (a 13.1% reduction). Integration of this NH3 baseline process with the power station takes the CO2-avoided cost advantage over the MEA process (US$67.3/tonne vs US$86.4/tonne). We then investigated process modifications of a two-stage absorption, rich-split configuration and interheating stripping to further advance the NH3 process. The modified process reduced energy consumption by 31.7 MW/h (20.2% reduction) and capital costs by US$55.4 million (6.7% reduction). As a result, the CO2-avoided cost fell to $53.2/tonne: a savings of $14.1 and $21.9/tonne CO2 compared with the NH3 baseline and advanced MEA process, respectively. The analysis of energy breakdown and cost distribution indicates that the technoeconomic performance of the NH3 process still has great potential to be improved.

Controlled functionalization of poly(4-methyl-1-pentene) films for high energy storage applications

A new family of poly(4-methyl-1-pentene) ionomers with high energy density at a high breakdown strength, high charge-discharge energy efficiency and a very narrow breakdown distribution for energy storage in future capacitor devices.

Nanoscale Characterization of High-K/IL Gate Stack TDDB Distributions After High-Field Prestress Pulses

The effect of single nondestructive pulsed voltage prestresses on the time to breakdown distributions of a SiON/HfSiON bilayer gate stack is investigated at nanometric scale using an atomic force microscope in conduction mode under ultrahigh vacuum. The results are compared with the degradation due to a voltage pulse of the SiON layer alone. It is found that only the shape parameters of the distributions are affected by the prestress pulses. This effect is then discussed in terms of a progressive degradation starting at the Si/SiON interface, and an extrapolation formula is given to predict the decrease of the time to breakdown of the bilayer gate stack as a function of the prestress pulse parameters.

Large-area dielectric breakdown performance of polymer films – Part II: Interdependence of filler content, processing and breakdown performance in polypropylene-silica nanocomposites

In this study, large-area dielectric breakdown performances of various bi-axially oriented polypropylene (BOPP)-silica nanocomposite films are studied by utilizing the self-healing multi-breakdown method presented in the Part I of this publication. In particular, the effects of silica filler content, pre-mixing method, co-stabilizer content and film processing on the large-area breakdown performance are analyzed. Nanostructural and film cross-sectional analyses are correlated to the breakdown responses. The optimum silica filler content is found to reside at the low fill fraction level (~1 wt-%) and automatic pre-mixing of the raw materials and the optimization of the orientation temperature are found to be preferable. The co-stabilizer Irgafos 168 is found to have a significant effect on the breakdown distribution homogeneity of the reference BOPP films. The breakdown response of the silica nanocomposites is found to be not only dependent on the active measurement area but also on the voltage ramp rate, indicating that the silica nanocomposites exhibit altered internal charge behavior under DC electric field. The area- and ramp-rate-dependence results exemplify the importance of careful breakdown strength evaluation of dielectric polymer nanocomposites. Above all, the results emphasize the fact that a thorough understanding and the optimization of the film processing parameters are crucial for achieving improved breakdown response in dielectric polymer nanocomposite films.

Large-area dielectric breakdown performance of polymer films - part i: measurement method evaluation and statistical considerations on area-dependence

A multi-breakdown measurement method for large-area dielectric breakdown characterization of polymer films is presented and evaluated. Based on the self-healing breakdown capability of metalized film, large amount of breakdown data can be obtained from a relatively large total film area, thus enabling the execution of detailed breakdown performance analysis. The studied films include non-metalized laboratoryscale, pilot-scale and commercial capacitor-grade bi-axially oriented polypropylene films in the thickness range of 14-25 μm. With the active measurement area of 81 cm2 per sample, breakdown distributions covering total film areas of 486-972 cm2 are presented. Various aspects encompassing the sample film preparation, measurement procedure, breakdown progression, discharge event characterization, breakdown field determination, data validation and statistical analysis are discussed. Comparative small-area breakdown measurements were performed in order to study the relationship between the large-area multi-breakdown measurement method and a conventional small-area (1 cm2) manual breakdown measurement method. Implications of the areadependence and the applicability of the Weibull area-scaling are also discussed.

極薄シリコン酸化膜における原子レベルの膜厚均一性と信頼性

In this paper, the evaluation methods of the degradation and dielectric breakdown of ultrathin SiO2 thermally grown on Si, which are one of most superior dielectric films, are introduced along with some examples. SISuR (Stress-Induced oxide Surface Roughness) method with using a reaction between SiO2 films with trapped charges and etching solution is available to clarify that the degradation in SiO2 film under high electric field stress is not uniform. Furthermore, it is indicated that thermal oxidation of the atomically-flat Si terrace surface does not progress two-dimensionally uniformly, strictly speaking. The non-uniform oxidation is one of the origins of the wide lifetime distribution of dielectric breakdown of the ultrathin SiO2 films.

Thickness-dependence of the breakdown strength: Analysis of the dielectric and mechanical failure

Abstract The breakdown strength as well as the mechanical strength of ceramic materials decreases with increasing volume. The volume-effect of the mechanical strength can be explained by the Weibull theory. For the breakdown strength the same explanation has been often assumed. In order to validate this assumption breakdown strength and mechanical strength of alumina samples with defined porosities were compared. Differences in the Weibull moduli of breakdown and mechanical strength distributions indicate that the volume-effect cannot explain the thickness-dependence of the breakdown strength. In particular, the thickness-dependence of the breakdown strength always leads to a Weibull modulus of two which is not in agreement with the measured Weibull moduli for samples with constant thickness. It can be concluded that the thickness-dependence of the breakdown strength cannot be explained by the Weibull concept. A recently developed breakdown model which is based on space charge injection is able to explain the experimental results.

A relationship between statistical time to breakdown distributions and pre-breakdown negative differential resistance at nanometric scale

Using an ultra-high vacuum Conductive atomic force microscopy (C-AFM) current voltage, pre-breakdown negative differential resistance (NDR) characteristics are measured together with the time dependent dielectric breakdown (TDDB) distributions of Si/SiON (1.4 and 2.6 nm thick). Those experimental characteristics are systematically compared. The NDR effect is modelled by a conductive filament growth. It is showed that the Weibull TDDB statistic distribution scale factor is proportional to the growth rate of an individual filament and then has the same dependence on the electric field. The proportionality factor is a power law of the ratio between the surfaces of the CAFM tip and the filament's top. Moreover, it was found that, for the high fields used in those experiments, the TDDB acceleration factor as the growth rate characteristic is proportional to the Zener tunnelling probability. Those observations are discussed in the framework of possible breakdown or forming mechanism.

La estadística de las exportaciones argentinas, 1875-1913. Nuevas evidencias e interpretaciones

Argentine export statistics from the last decades of the nineteenth century up until the First World War has been widely revisited over the years. This paper presents a reconstruction of an economic data series, contributing to well-documented debates around the reliability and limitations of existing official records. This new database adopts a systematic, multilateral and long-term approach. The level of granularity both, in terms of product breakdown and geographic distribution, is its main contribution.Through this work, we describe how original data was modified, and our results are compared with previous data series. Key highlights from our research include: the identification of export cycles, the performance of volumes vs. prices, the fragmentation trend of the Argentine international trade, a revaluation of the intermediate ports, and the diversification destinations.

Cu配線の信頼性と界面： EM，SIV，TDDBにおける界面の寄与と制御

The contributions of the “interface” on interconnect reliability are investigated in some previous work. For electromigration and stress-induced voiding, Cu/dielectrics interface has a key role as a dominant diffusion path of Cu. A surface treatment after chemical mechanical polishing affects lifetime distribution of time-dependent dielectric breakdown. The defect density on the interface is a key factor to control the early failure. In this paper, some advanced metallization process and its effects to suppress the reliability issues are introduced. To adapt the novel process technologies successfully in product line, these results will provide valuable information.

Time-dependent-dielectric-breakdown characteristics of Hf-doped Ta2O5/SiO2 stack

The Time-Dependent-Dielectric Breakdown (TDDB) characteristics of MOS capacitors with Hf-doped Ta2O5 films (8nm) have been analyzed. The devices were investigated by applying a constant voltage stress at gate injection, at room and elevated temperatures. Stress voltage and temperature dependences of hard breakdown of undoped and Hf-doped Ta2O5 were compared. The doped Ta2O5 exhibits improved TDDB characteristics in regard to the pure one. The maximum voltage projected for a 10years lifetime at room temperature is −2.4V. The presence of Hf into the matrix of Ta2O5 modifies the dielectric breakdown mechanism making it more adequate to the percolation model. The peculiarities of Weibull distribution of dielectric breakdown are discussed in terms of effect of three factors: nature of pre-existing traps and trapping phenomena; stress-induced new traps generation; interface layer degradation.

Impact of bilayer character on High K gate stack dielectrics breakdown obtained by conductive atomic force microscopy

The time to breakdown distribution of bilayer gate stack dielectrics is measured at nanometric scale using an atomic force microscope in conduction mode under ultra-high vacuum. The bilayer consists of a SiON interfacial layer and a HfSiON High-K layer. Thanks to the small tip/sample contact area the time to breakdown distribution of the single interfacial layer is measured separately. It is found that the Weibull parameters of the Interfacial layer distribution are the same as those of the high percentile part of the bilayer bimodal distribution. This experimentally confirms the validity of former dielectric breakdown model assumptions. Considering the fields in each layer an accurate evaluation of acceleration factors and voltage scaling of the bimodal distribution are given.

Microscopic Modeling of Electrical Stress-Induced Breakdown in Poly-Crystalline Hafnium Oxide Dielectrics

We present a quantitative physical model describing degradation of poly-crystalline HfO2 dielectrics subjected to electrical stress culminating in the dielectric breakdown (BD). The model accounts for the morphology of the hafnium oxide film and considers the interaction of the injected electrons with the atomic defects supporting the charge transport to calculate the 3-D power dissipation and temperature maps across the dielectric. This temperature map, along with that of the electric field, is used to self-consistently calculate the stress-induced defect generation rates in the dielectric during stress. The model quantitatively reproduces the evolution of the currents measured on HfO2 MIM capacitors during constant voltage stress, up to the onset of BD, and the dependencies of the time-dependent dielectric breakdown distributions on stress temperature and voltage. It represents a powerful tool for statistical reliability predictions that can be extended to other high-κ materials, multilayer stacks, and resistive RAM devices based on transition metal oxides.

Time-dependent dielectric breakdown in pure and lightly Al-doped Ta2O5 stacks

The time-dependent dielectric breakdown (TDDB) characteristics of 7 nm pure and lightly Al-doped Ta2O5 (equivalent oxide thickness of 2.2 and 1.5 nm, respectively) with W gate electrodes in MOS capacitor configuration are studied using gate injection and constant voltage stress. The effect of both the process-induced defects and the dopant on the breakdown distribution, and on the extracted Weibull slope values, are discussed. The pre-existing traps which provoke weak spots dictate early breakdowns. Their effect is compounded of both the stress-induced new traps generation (percolation model is valid) and the inevitable lower-k interface layer in the region with long time-to-breakdown. The domination of one of these competitive effects defines the mechanism of degradation: the trapping at pre-existing traps appears to dominate in Ta2O5; Al doping reduces defects in Ta2O5, the generation of new traps prevails over the charge trapping in the doped samples, and the mechanism of breakdown is more adequate to the percolation concept. The doping of high-k Ta2O5 even with small amount (5 at.%) may serve as an engineering solution for improving its TDDB characteristics and reliability.