Influence Of Insulation Research Articles

Influence of sheath thickness and core rod diameter on fault temperature rise of composite insulator

Infrared temperature measurement is an effective means for insulator health monitoring, and the theoretical basis and the subsequent diagnosis methods have been widely studied. However, in practical applications, the influence of insulator itself on fault temperature rise is rarely considered. In this paper, the temperature rise experiment of composite insulator was conducted to study the influence of sheath thickness and core rod diameter on fault temperature rise. According to the experimental results, the evolution law of fault temperature rise with the change of sheath thickness and core rod diameter was obtained. On this basis, the design strategy for composite insulators was proposed.

Insulator-based loops mediate the spreading of H3K27me3 over distant micro-domains repressing euchromatin genes

Abstract Background Chromosomes are subdivided spatially to delimit long-range interactions into topologically associating domains (TADs). TADs are often flanked by chromatin insulators and transcription units that may participate in such demarcation. Remarkably, single-cell Drosophila TAD units correspond to dynamic heterochromatin nano-compartments that can self-assemble. The influence of insulators on such dynamic compartmentalization remains unclear. Moreover, to what extent heterochromatin domains are fully compartmentalized away from active genes remains unclear from Drosophila to human. Results Here, we identify H3K27me3 micro-domains genome-wide in Drosophila, which are attributed to the three-dimensional spreading of heterochromatin marks into euchromatin. Whereas depletion of insulator proteins increases H3K27me3 spreading locally, across heterochromatin borders, it concomitantly decreases H3K27me3 levels at distant micro-domains discrete sites. Quantifying long-range interactions suggests that random interactions between heterochromatin TADs and neighbor euchromatin cannot predict the presence of micro-domains, arguing against the hypothesis that they reflect defects in self-folding or in insulating repressive TADs. Rather, micro-domains are predicted by specific long-range interactions with the TAD borders bound by insulator proteins and co-factors required for looping. Accordingly, H3K27me3 spreading to distant sites is impaired by insulator mutants that compromise recruitment of looping co-factors. Both depletions and insulator mutants significantly reduce H3K27me3 micro-domains, deregulating the flanking genes. Conclusions Our data highlight a new regulatory mode of H3K27me3 by insulator-based long-range interactions controlling distant euchromatic genes.

Umweltwirkungen von Bauprodukten – Möglichkeiten und Grenzen beim Vergleich verschiedener Wandkonstruktionen

AbstractLife cycle assessments quantify the environmental impact of goods and services. Increasingly, their results should be used for variant comparisons in construction planning and procurement. For the ecological assessment of wall building materials, this should not be limited to the assessment of the blocks, but the influence of insulation, plaster and mortar have to be taken into account as well. The considered wall should also fulfil predetermined properties such as a certain U‐value.The LCA data available today still do not permit any comparison of variants. For this, product‐specific life cycle assessments/environmental product declarations would have to exist on the basis of uniform background data. Because the latter are being constantly developed and there are hardly any product‐specific calculations, comparisons today are very inaccurate and subject to great uncertainties.

Study on the influence of insulator on the coupling effect of transmission tower-line system

There is a coupling between transmission tower and lines. Traditionally, it is assumed that an insulator is in a tight connection with tower. In fact, both tight and loose connections exist. This paper studies the influence of connection state on system dynamics. The tower-line system rigged with the adjustable connection state of insulator was built. We used modal test method to study the coupling effect. The influence of the line is mainly in the longitudinal and torsional mode. It has less influence on the lateral mode. The damping increases for tower-line system and is the largest for loose connection state. The loose connected system’s first three modal frequencies are almost the same as that of the tower. However, the tight connected system’s longitudinal and torsional frequency decreases. The difference caused by connection state of insulator should be considered. Modelling method under different connection state should be different. The traditional finite element method can be used for tight connection. Under loose connection state, the insulator-line system can be regarded as a tuned mass damper attached to the tower.

Influence of Insulation on Quench and Recovery of YBCO Tape Under DC Impact

A dc superconducting fault current limiting device can effectively limit the fast rising dc fault current and ensure the safety and reliability of the power grid. However, during the limiting period, the superconducting unit withstands the high voltage. Polymer film, kapton, and polytetrafluoroethylene (PTFE) have an excellent insulation performance at low temperature, which can solve the insulation problem. Quench and recovery is important characteristic, especially for the fault current limiting device. In this work, we measured the resistance development in YBCO tape with three insulation modes. In this work, a new insolating method for YBCO tape is investigated. We measured the resistance development in YBCO tape with three insulation modes. The experiment results show that the PTFE can be used, which can decrease the recovery time 30% ~ 50% than the naked one. As to the high-voltage superconducting fault current limiting device, the PTFE film can be put in the first layer, then twined the kapton film outside, which reduce recovery time about 20% ~ 40%.

Influence of Insulation on Thermal Behavior of Overhead Line Conductors

Influence of Insulation on Thermal Behavior of Overhead Line Conductors

Influence of Insulation Monitoring Devices on the Operation of DC Control Circuits

The insulation level of DC control circuits is an important safety-critical factor and, thus, should be subject to continuous and periodic monitoring. The methods used for monitoring the insulation in live circuits may, however, disturb the reliable operation of control relays. The risks of misoperation and failure to reset of relays posed by the operation of various insulation monitoring and fault location systems are evaluated.

The influence of insulation of walls of industrial objects on thermal regime at the heating system of gas infrared radiators

The results of a numerical study of the process of heat transfer from the gas infrared emitters in the heated accommodation are represented. Simulation was conducted taking into account the heat withdrawal in the enclosing constructions and of heat exchange with the environment. The estimation of the average values of temperatures of air indoors in the dependence on the different intensity of heat withdrawal into the vertical walls is carried out (when the layer of insulation is present, and without it).

An Analysis of Insulation of Abandoned Oil Wells Reused for Geothermal Power Generation

Geothermal power generation from abandoned oil wells is a new way to utilize geothermal energy. An analysis model based on transient formation heat transfer is presented in this paper. Through the double-pipe heat exchanger, R143a is used as working fluid for obtaining geothermal energy from abandoned oil wells. The influence of insulation on heat transfer from the recovery well to the injection well is investigated. The result shows that the outlet temperature of fluid leaving the recovery well gradually increases with thickness of insulation increasing. The outlet temperature of fluid with the insulation of 0.03m polystyrene drops by 6K as compared to the outlet temperature with the perfect insulation. At the same thickness of insulation, the difference of the outlet temperature between with the insulation of polystyrene and with the perfect insulation decreases with the inlet velocity of fluid entering the injection well increasing.

The Study of Insulator Influence to the Electromagnetic Wave Propagation in GIS

GIS is the key equipment in power grid and partial discharge is the main cause leading to insulation breakdown. UHF detection is an effective method for PD detection in GIS. The insulator has great influence to the electromagnetic wave propagation in GIS. The FDTD simulation model of GIS is setup to study the influence of insulator to electromagnetic wave propagation. The amplitude and energy distribution at GIS model with and without insulator are study in this paper.

Influence of insulators on transgene expression from integrating and non-integrating lentiviral vectors

BackgroundThe efficacy and biosafety of lentiviral gene transfer is influenced by the design of the vector. To this end, properties of lentiviral vectors can be modified by using cis-acting elements such as the modification of the U3 region of the LTR, the incorporation of the central flap (cPPT-CTS) element, or post-transcriptional regulatory elements such as the woodchuck post-transcriptional regulatory element (WPRE). Recently, several studies evaluated the influence of the incorporation of insulators into the integrating lentiviral vector genome on transgene expression level and position effects.MethodsIn the present study, the influence of the matrix attachment region (MAR) of the mouse immunoglobulin-κ (Ig-κ) or the chicken lysozyme (ChL) gene was studied on three types of HIV-1-derived lentiviral vectors: self-inactivating (SIN) lentiviral vectors (LV), double-copy lentiviral vectors (DC) and non-integrating lentiviral vectors (NILVs) in different cell types: HeLa, HEK293T, NIH-3T3, Raji, and T Jurkat cell lines and primary neural progenitors.Results and DiscussionOur results demonstrate that the Ig-κ MAR in the context of LV slightly increases transduction efficiency only in Hela, NIH-3T3 and Jurkat cells. In the context of double-copy lentiviral vectors, the Ig-κ MAR has no effect or even negatively influences transduction efficiency. In the same way, in the context of non-integrating lentiviral vectors, the Ig-κ MAR has no effect or even negatively influences transduction efficiency, except in differentiated primary neural progenitor cells.The ChL MAR in the context of integrating and non-integrating lentiviral vectors shows no effect or a decrease of transgene expression in all tested conditions.ConclusionsThis study demonstrates that MAR sequences not necessarily increase transgene expression and that the effect of these sequences is probably context dependent and/or vector dependent. Thus, this study highlights the importance to consider a MAR sequence in a given context. Moreover, other recent reports pointed out the potential effects of random integration of insulators on the expression level of endogenous genes. Taken together, these results show that the use of an insulator in a vector for gene therapy must be well assessed in the particular therapeutic context that it will be used for, and must be balanced with its potential genotoxic effects.

Optimizing the Implementation of High-Temperature Fixed Points through the Use of Thermal Modeling

High-temperature fixed points (HTFP) have the potential to make a step-change improvement in high-temperature metrology, significantly reducing the uncertainty of scale realization of the current ITS-90 and improving dissemination of high-temperature scales to industry. However, in a practical implementation, the performance of HTFP could be limited, by, for example, injudicious use of insulation in the vicinity of the fixed point, furnace gradients, or incomplete filling. This article investigates some of these aspects for a selection of HTFP. Steady-state modeling of the influence of insulation on the radiance temperature was performed for Co–C (1,324°C), Pd–C (1,492°C), Pt–C (1,738°C), Ru–C (1,953°C), and Re–C (2,474°C) fixed points. This included studying mitigation scenarios through the insertion of different types and designs of insulation. The optimum design was identified to minimize the temperature drop in a particular furnace. It was found that, for the furnace and fixed-point combination modeled, the actual effect of the insulation was almost insignificant. Transient modeling was performed for a Re–C fixed point, to track the evolution of the radiance temperature through the melting transition. The starting point of the model was the beginning of the melt. The evolution of radiance temperature with time in “perfectly” filled cells was modeled with a range of linear temperature gradients across the eutectic cell. The gradient had a significant effect on the duration of the transition and on the structure of the melt itself. Despite the model’s simplicity, it qualitatively demonstrated that the melt transition temperature, as identified by the point of inflection, could be significantly affected by the presence of furnace gradients.

Influence of insulator along the plane of symmetry of a blade-plane gap on I–V characteristics in transformer oil

In the case of a blade-plane electrode geometry in transformer oil, conduction currents under dc stresses were exceedingly decreased by a solid insulator inserted along the plane of symmetry of an electrode gap whatever the polarity of the blade. However, the stationary relationship between current I and voltage V always showed the linear plots of V vs. I sol1 3 . The effect of the insulator on the current is discussed on the basis of the electrohydrodynamic (EHD) motion as well as the electric field of the blade edge taking into account the insulator surface charging.

Influence of insulators on R/W process in laminated film heads

The influence of insulators on read/write (R/W) process in laminated film heads was investigated by the Bitter method and computer simulations. Some unrecorded areas exist in a recording track, and the areas correspond to the position of insulators at the trailing side. The effective recording width depends on not only the recording current but also the relative positions of insulators at the leading and trailing edges. These results were confirmed by the simulation. In the reproducing process, the loss caused by the insulator is smaller than the ratio of the track width by the insulator's thickness. In both R/W characteristics, the laminated film head with inline insulators at both sides of the gap is superior to that with the staggered insulators.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Discussion: Time characteristics of fast pulsed flashover in vacuum (with reply by H. Karner)

For original paper see H.H. Zhong et al., ibid., vol.27, p.496-503 (1992). The discussor raises five points and adds comments concerning insulator shapes and the delivery of excessive discharge energy. H. Karner replies by first noting that he can answer only partly to some of the questions due to the fact that he wanted to investigate the influence of insulators on the speed of the voltage collapse which he had examined for a free vacuum gap. The discussor however, is mainly interested in strength problems of gaps with insulators, which he investigated only to a small extent. >

Development of a New Evaluation System of Frictional Static Charge

The influence of insulation and testpiece-size on the frictional charge have been investigated with various kinds of fabric by the KB-system. It was found that the frictional charge and the decay rate are significantly influenced by both insulation and testpiece-size, while the frictional charge and the decay rate of the fabric, in which grounded electro-conductive filament is contained, are not influenced by the testpiece-size.

ITPE technique applications to time-varying two-dimensional ground-coupling problems

The interzone temperature profile estimation (ITPE) procedure is used to find two-dimensional analytical series solutions for the time-varying heat transfer between ground and slab-on-grade floors or basements. The undisturbed soil temperature is approximated as a sinusoidal function of time and the ITPE procedure is coupled with the complex temperature technique to derive the steady-periodic solutions for both configurations. The influence of insulation and of a fixed-temperature water table on the temporal behavior of slab-on-grade floors and basements is treated analytically for the first time.

Corona Discharge Studies in SF6 with Insulators under Positive Switching Impulses

Corona discharge currents and corona inception time delays have been measured in SF6 with an insulating support under positive switching impulses. The insulator surface charging is found to have a significant influence on the corona discharge phenomena. Cumulative probability distribution function of the number of corona pulses is found to depend upon the insulator material and gas pressure. Based on the experimental results, the calculated corona inception time delay distribution with an insulator is found to fit into a log-normal distribution. The influence of insulator on electron initiating mechanism is analyzed using Von Laue diagrams for the corona time delay. The effect of gas pressure and the applied voltage on the inception time delay and pulse current with an insulator in the gap is discussed.

Influence of insulation on stability of interface shape and position in the vertical Bridgman-Stockbarger technique

The temperature field was calculated inside a vertical Bridgman-Stockbarger growth ampoule with insulation between the heater and the cooler. The isotherms in the insulated region are relatively planar. The sensitivity of the interface shape to system perturbations decreases dramatically with increasing thickness of the insulation, while the temperature gradient is only diminished slightly for high thermal conductivity materials. For a moving ampoule, the temperature field inside the ampoule is more sensitive to the heat transfer coefficient in the cooler than that in the heater.