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The oil-impregnated paper, which is the major section in converter transformer, plays a considerable role in the reliability and safety of power grid. However, the insulation degradation will be accelerated by the accumulation of charges that are on the surface of oil-impregnated paper. Therefore, the operating overvoltage occurs and irremediable damage will appear. Direct fluorination is an effective method of modifying the chemical components of polymer matrix so as to have effects on the surface characteristic of the insulating material without reforming the bulk properties. In this research, for studying effects of fluorination on charge behavior on the surface of oil-impregnated paper under the application of DC and impulse voltage, the F2/N2 compound, which the volume fraction for the F2 gas occupied 10 % and the pressure was 0.05 MPa in a reaction kettle for 5, 30 and 60 min respectively, was applied. Meanwhile, the chemical bond groups and the surface morphology of the fluorinated specimen were tested. Besides, the DC voltage amplitude was 4 kV and the applied time was 4 min. The impulse frequency was 500 Hz and the impulse voltage amplitude was 1, 2, 3 and 4 kV, respectively. The charge properties under various situations were investigated. From the research under the application of different fluorination time, impulse voltage amplitudes and polarities, conclusions can be drawn that, fluorination has significant effects on the chemical structure properties and surface characteristic of oil-impregnated paper. Furthermore, the initial potential can be reduced and the decay process of surface charge can be accelerated with different fluorination time increasing from 0 to 30 min. Nevertheless, the tendency is the opposite when the fluorination time continuously extends from 30 to 60 min. The trap distribution also exhibits alternation through the fluorination. [ABSTRACT FROM PUBLISHER]

Due to its excellent performance, oil-paper insulation has been widely used in many power apparatuses including converter transformer of high voltage direct current (HVDC) system. Space charge accumulation phenomena may significantly distort local electric field inside transformer and cause oil-paper insulation overstressing. As a result of long term operation, oil-paper gradually degrades. In most severe cases, the breakdown of insulation system may occur. In this work, the effect of space charge on breakdown characteristics of aged oil-paper insulation is investigated. Oil-paper samples with different aging states are obtained by thermally accelerated aging for various periods of time, categorized by the degree of polymerization (DP) of 1107 (new), 725, 504, 376 and 241, respectively. Experimental results show that the breakdown voltage of oil-paper samples without pre-stressing remains almost constant with thermal degradation. After the homo-polarity pre-stress, when the DP value is higher than ∼300 (from 1107 to 376), the breakdown voltage has an increasing tendency with an increase in thermal degradation. On the contrary, the breakdown voltage presents a decreasing tendency after the hetero-polarity pre-stress. When the DP is lower than ∼300 (DP241), the changes of breakdown voltage does not remain the same trend as previous samples after pre-stressing. Meanwhile, space charge distributions in different aged samples are measured by the pulsed electro-acoustic (PEA) method, and the trap parameters are correspondingly evaluated. It has been experimentally demonstrated that special attention should be paid to space charge accumulation and aging state of oil-paper insulation, which may lead to severe insulation accidents. [ABSTRACT FROM AUTHOR]

Oil-paper insulation system is an extraordinarily essential system of converter transformers as well as HVDC bushings. When the system changes its state, such as switching the thyristors, operating over-voltage appears, and the charge will deform the dielectric internal electric field, thus easily leading to the occurrence of discharge or insulation failure, so charge accumulation and dissipation on oil-paper insulation under pulse voltage need more investigation. This paper studies the surface charge behavior on double-layer oil-paper insulation under pulse voltage and inducing electrification was used to charge the oil-paper composite. Studies of various voltage amplitudes, pulse frequencies, numbers and polarities showed that the decay is fast initially, and then becomes slower with the time. Eventually the dissipation of charge behaviors tends to be flat. With the increase of voltage amplitudes, the surface potential rises, and less positive charges are accumulated on the surface than negative charges. The increase of the pulse frequency causes the initial values of surface potential a little smaller and the charge to dissipate more quickly. Also, with the increase of pulse numbers, the initial value gets bigger and the surface charge would be slowly dissipated. From the tdV/dt and decay time curves, the figures of positive voltage usually have two peaks, while there is only one peak in most of the curves under the negative one. With the increase of voltage amplitudes, the charge will dissipate more quickly. Additionally, the peak value and the characteristic time increase with the reduction of pulse frequency and the addition of numbers. [ABSTRACT FROM PUBLISHER]

A compact and flexible multiwalled carbon nanotubes (MWCNTs)-coated paper electrode was fabricated in this study. The shape of the paper electrode could be varied simply by cutting it. Further, its electrical resistance did not change appreciably either when it was bent with different curvatures or when it was subjected to repeated bending and stretching. An nanoscale energetic material (nEM)-on-MWCNTs paper chip formed by depositing an nEM thin film on the MWCNTs-coated paper electrode could be stably ignited by applying voltages higher than ∼ 15 V. The ignition and explosion characteristics of the chip were investigated systematically. It was found that the explosion reactivity of the chip increased with an increase in the thickness of the nEM thin film. Finally, the remote ignition of the nEM-on-MWCNTs paper chip was successfully demonstrated by explosively breaching a door, suggesting that such nEM-on-MWCNTs paper chips can be used as compact, flexible, and versatile igniters in various civil and military applications. [ABSTRACT FROM AUTHOR]

Oil-paper insulation system is an extraordinarily essential system of converter transformer as well as HVDC bushing. This paper studies the interface charge accumulation and dissipation characteristics of oil-paper insulation system under DC voltage. In this paper, an induced electrification was used to charge the oil-paper samples. The amplitudes of the DC voltage varied from 1 to 4 kV and the paper was 0.13 mm in thickness. From the research of different voltage amplitudes and charging times of the paper, conclusions can be drawn that the decay is fast initially, and then becomes slower with the lapse of time. At last the dissipation trend tends to be flat. With the increase of the voltage amplitudes, the surface potential rises more rapidly, and higher voltage would also cause the charge to dissipate more quickly. Longer charging times would cause the charge to dissipate a bit more slowly. The decay rate of the negative voltage is a little smaller than that of the positive charge. Moreover, when it comes to the effect on the interface charge of the paper layers, the surface potential is more proportional to the increase of paper layers. When the amplitude of the voltage applied in the test is small or the charging time is short enough, the interface charge can be hardly accumulated on the bottom layer. In addition, the tdV/dt and the decay time curves under the positive voltage usually have two peak values, while there is only one peak value in most of the curves under the negative condition. [ABSTRACT FROM PUBLISHER]

Here we report a new conductivity sensing mechanism using a closed bipolar electrode (BPE) system for the first time. Briefly, the voltage dropping across the ECL reporting cell will change with the sample conductivity of the analytes cell in a closed bipolar system. Thus, a quantitative relation between the electrochemiluminescence (ECL) response and the sample conductivity is established. Based on this principle, chemicals those are not electroactive materials and do not participate in the ECL process can be detected now, which greatly expands the application range of the BPE and the powerful ECL technique. Then a paper-based bipolar ECL conductivity sensing platform was constructed and carefully characterized, and the results proved the rationality of this newly-proposed bipolar conductivity sensing mechanism. More importantly, this design is also a universal sensing platform, suitable for all the electrolytes without electroactivity (newly proposed), electroactive chemicals and chemicals directly related to the ECL reaction. [ABSTRACT FROM AUTHOR]

A conductive carbon nanofiber (CNF) paper is described for the actuation of shape recovery of a shape-memory polymer (SMP) by electrically resistive Joule heating. The CNF paper was manufactured using a traditional physical vapor deposition process and the microscale morphology and structure of the CNF paper were observed using a scanning electron microscope. The CNF paper was found to be porous, with the pore size determined by the weight concentration of CNF. The excellent electrical properties of pure CNF papers and their SMP composites were characterized by the four-point probe method. Shape recovery actuation of this type of SMP composite induced by electrically resistive heating was achieved with a 12 V voltage. Additionally, the thermomechanical properties of the SMP composite were studied with respect to the volume fraction of CNF paper. [ABSTRACT FROM AUTHOR]

Space charge behavior is important in the oil-immersed-paper insulation in converter transformers for HVDC transmission. This paper reports an investigation of the space charge property in samples with two layers of oil-immersed-paper and oil. Based on pulsed electroacoustic (PEA) technique, a waveform recovery method was proposed to get rid of the effects of interface and anisotropy on PEA result, and the space charge distributions in the two-layer samples under different voltage and oil thicknesses were measured. It?s found that the charges with the same polarity as oil side electrode were accumulated at the interface and gradually increased with the increase of applied voltage. However, the positive charge charges always appeared in the oil under positive and negative voltages. Moreover, the charges in samples increased with the increase of applied voltage, while the amount of interface charges decreased with the increase of oil thickness. Due to the existence of interfacial charges, the electrical field in oil-immersed-paper was distorted with its maximum close to the interface. It is indicated that due to the different mobility properties of charges in paper and oil and the interface trap state, the interface between paper and oil plays an important role in charge formation and decay. [ABSTRACT FROM PUBLISHER]

An oil-paper insulation system which will withstand DC voltage under normal conditions is a key component of converter transformers as well as high voltage direct current (HVDC) bushings. When the system changes its state, operating overvoltage appears. This kind of overvoltage will consequently affect the application of oilimmersed facilities and the safety of entire grid. Therefore, this paper studies the charge coupling behavior of double-layer oil-paper insulation under DC and pulse voltages. From the research of different pulse voltage amplitudes, pulse numbers and polarity, conclusions can be drawn that, with the increase of the pulse voltage amplitudes, DC and pulse voltages in the same polarity cause the absolute value of the initial surface potential to decrease and then rise; while in different polarities, the charge with the same polarity as the pulse voltage increases. Furthermore, for the same pulse voltage, the absolute initial value of the DC voltage applied in the same polarity is higher than that in different polarities. Considering the pulse number effect, it is obvious that the initial value increases with the increase in the pulse number, and then reaches saturation. Also, with the increase in pulse number, the decay rate decreases and thus the charge is slowly dissipated. From the tdV/dt and the decay time curves, the peak value increases with the increase in the pulse number, while the characteristic time varies by the polarity of the DC and pulse voltages. [ABSTRACT FROM AUTHOR]

The paper presents new diagnostic method applied to assess aging degree for paper-oil insulation used in professional electrical power device, primarily including medium and high power transformers. The described method is based on modified diagnostics using the recovery voltage effect occurring in dielectrics (RVM ? Recovery Voltage Methods). Modification of the RVM method applied so far, which is now used only to assess moistening degree for paper-oil insulation in power transformers, consists in a new parametric analysis of recovery voltage time characteristics. Simulation and experimental tests carried out in laboratory conditions for adequately prepared insulation samples have proven that the time-constant of recovery voltage decay (?R_MIN) is the most susceptible parameter as regards quantitative change in the function of aging of the examined insulation. This conclusion is also confirmed by statistical studies, in which a multi-parameter variance analysis method has been applied. An original equivalent circuit diagram of the insulation has been used to simulate aging degree of paper-oil insulation samples in numerical tests. The diagram is based on the Cole-Cole type dielectric response model. [ABSTRACT FROM AUTHOR]

A method of predicting the residual breakdown electrical field strength of an epoxy-mica paper insulation system is described. This method was developed by using data on service?aged stator bars from generators as well as accelerated aging model bars. Thermal aging, mechanical aging, and combined thermal and mechanical aging were done individually as accelerated aging. The partial discharge characteristics, dissipation factor, and breakdown voltage were measured on the model bars and service?aged bars from generators. From these results, the residual breakdown electrical field strength was predicted based on the partial discharge characteristics and dissipation factor. First, the dominant type of deterioration (thermal or mechanical aging) on a bar?s insulation was determined by the pattern of voltage?partial discharge magnitude characteristics. Then the residual breakdown electrical field strength was predicted by using a predicting equation for both thermal and mechanical aging. Each predicting equation uses dissipation factor tip-up (i.e. difference in dissipation factor values between 2 kV and rated voltage) and partial discharge inception electrical field strength. The accuracy of this method was confirmed using data measured on 112 service-aged stator bars from generators and 10 accelerated aged model bars. The 95% confidence interval level included 94% of the measured residual breakdown electrical field strength values. This result shows that the method enables precise predictions of the residual breakdown electrical field strength of an epoxy-mica paper insulation system. [ABSTRACT FROM AUTHOR]

Paper-based microchip electrophoresis has the potential to bring laboratory electrophoresis tests to the point of need. However, high electric potential and current values induce pH and temperature shifts, which may affect biomolecule electrophoretic mobility thus decrease test reproducibility and accuracy of paper-based microfluidic electrophoresis. We have previously developed a microchip electrophoresis system, HemeChip, which has the capability of providing low-cost, rapid, reproducible, and accurate point-of-care (POC) electrophoresis tests for hemoglobin analysis. Here, we report the methodologies we implemented for characterizing HemeChip system pH and temperature during the development process, including utilizing commercially available universal pH indicator and digital camera pH shift characterization, and infrared camera characterizing temperature shift characterization. The characterization results demonstrated that pH shifts up to 1.1 units, a pH gradient up to 0.11 units/mm, temperature shifts up to 40 °C, and a temperature gradient up to 0.5 °C/mm existed in the system. Finally, we report an acid pre-treatment of the separation media, a cellulose acetate paper, mitigated both pH and temperature shifts and provided a stable environment for reproducible HemeChip hemoglobin electrophoresis separation. [ABSTRACT FROM AUTHOR]

Abstract: Space charge is a key insulation problem of HVDC equipment. In this paper, the influence of voltage polarity and electrode material were studied by the pulse electroacoustic (PEA) method. It had been found that the type of space charge accumulating at the interface was the same with the voltage polarity. With different electrode materials, the space charge injection was consequently different, but not evident. The interface made the drift velocity slower in two-layer samples. It suggested that the interface had a significant impact on space charge distribution and the contact state was complex, so a modified Maxwell–Wagner model was proposed. [Copyright &y& Elsevier]

Repeated impulses have long been considered to affect the insulation properties of electrical equipment. This interesting but rarely studied phenomenon may pose great risks to the reliable operation of power equipment. Therefore, in this work, we focus on the accumulative effect of repeated lightning impulses on the oil-impregnated paper (OIP) used in power transformers. Specifically, we study the effect of space charge on the accumulative characteristics of OIP. A repetitive impulse accumulating test platform was set up, and the tests were conducted to obtain the accumulative characteristics of OIP under repeated lightning impulses. The accumulative characteristics of OIP with various interval time were experimentally identified to study the influence of interval time on the accumulative effect. Then, space charge in OIP samples were investigated using the pulsed electro-acoustic technique. Charge behavior in OIP was analyzed under different conditions, i.e., changing the applied times, amplitude and interval time of the applied lightning impulses. Charge injection and transport occurred during lightning impulse accumulation. The increased application of lightning impulses, high applied voltage, and short interval time contributed to the accumulation and transport of space charges. At last, the possible mechanisms of the accumulative effect are discussed in this article based on the experimental results. [ABSTRACT FROM AUTHOR]

Abstract: Occluded gaseous cavities within the insulating materials are potential sources of electrical trees which can lead to continuous deterioration and breakdown of materials. To determine the suitability of use and to acquire the data for the dimensioning of electrical insulation systems breakdown voltage of insulators should be determined. In this paper, fuzzy logic (FL) method is used to model breakdown voltages of White Minilex Paper samples based on experimental data generated in the laboratory. Different models are proposed with different shapes of the membership functions for the FL under both dc and ac voltage conditions. The cavities are created artificially with different dimensions. Low values of mean absolute errors of the estimated breakdown voltage of the test data show the effectiveness of such models. [Copyright &y& Elsevier]

Traditional insulation paper (pressboard) used in power transformers has weaknesses such as poor thermostability, low breakdown voltage, and high permittivity, which leads to its degradation or even breakdown over time. For this paper, in order to judge if they could be used as new insulation materials for transformers, polycarbonate and polyester films were selected for electrical-thermal aging tests in temperatures of 110°C and 130°C in comparison with the insulation paper. Several infrared spectral tests were carried out on the three materials under a scanning electron microscope to analyze their electrical-thermal aging characteristics, mechanical behaviors, and degrees of polymerization. The functional group whose absorption peak intensity decreased drastically with aging was referred to as the characteristic functional group, and its peak absorption intensity was used to reflect its aging level. This paper found that the polycarbonate had a better aging resistance than both the insulation paper and PET. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

An experiment studying the physical principles of electrophoresis in liquids was developed for an undergraduate laboratory. We have improved upon the standard agarose gel electrophoresis experimental regime with a straightforward and cost-effective procedure, in which drops of widely available black food coloring were separated by electric field into their dye components on strips of chromatography paper soaked in a baking soda/water solution. Terminal velocities of seven student-safe dyes were measured as a function of the electric potential applied along the strips. The molecular mobility was introduced and calculated by analyzing data for a single dye. Sources of systematic and random errors were investigated. [ABSTRACT FROM AUTHOR]

Compared to conventional ac cables, the current rating of HVDC cable circuits is more complicated because the permissible current is not only limited by the operating temperature, but also by the electrical stress within the insulation. Therefore the IEC60287 current rating standard is considered insufficient for some HVDC applications because it fails to include the stress limitation. This paper presents an analytical methodology to calculate an electrical stress-limited rating for HVDC cables, which considers the maximum dielectric stress as the current limiting factor. This paper represents the first part of a project which has comprehensively reviewed cable rating calculations for mass impregnated HVDC cable systems. [ABSTRACT FROM PUBLISHER]

A novel colorimetric-fluorescent dual-mode sensing sensor JT5 was successfully synthesized, and exhibited red fluorescence enhancement effect and red colorimetric sensing, and excellent applicability through solid-state fluorescent strips and biological imaging experiments on zebrafish to highly sensitive monitoring Sn4+ ions. [Display omitted] • A novel and effective rhdamine B-based sensor JT5 successful development. • JT5 can serve as a fluorescent and colorimetric on-off sensor for Sn4+. • The sensor JT5 was successfully studied using fluorescence and colorimetric of the test strips. • Biomaging experiments for the sensor JT5 were conducted on zebrafish using a confocal microscope. A novel colorimetric-fluorescent dual-mode chemosensor (JT5) based on rhodamine B has been produced for monitoring Sn4+ in the DMSO/H 2 O (4:1, v/v) medium. It has high sensitivity, a low detection limit, a short response time (1 s) and high stability, and can still be maintained after two weeks with the red dual fluorescence/ colorimetric response. Enhancement of red fluorescence (591 nm) and red colorimetric (567 nm) response of JT5 by Sn4+ addition. The electrostatic potential of the sensor JT5 molecule was simulated to speculate on the sensing mechanism, and the IR, mass spectrometry and 1H NMR titration were utilized to further demonstrate that JT5 was coordinated to Sn4+ with a 1:1 type, the rhodamine spironolactam ring of JT5 opens up to form a penta-membered ring with Sn4+, meanwhile, its system may have chelation enhanced fluorescence (CHEF) effect. In addition, theoretical calculations were carried out to give the energy gaps of JT5 and [ JT5 + Sn4+] as well as to simulate the electronic properties of the maximal absorption peaks. Notably, the sensor JT5 was successfully applied to monitoring Sn4+ in zebrafish, and the JT5 -loaded filter paper provided a solid-state platform for detecting Sn4+ by both naked eye and fluorescent methods. In summary, this work contributes to monitoring Sn4+ in organisms and solid-state materials and promotes understanding of Sn4+ functions in biological systems, environments, and solid-state materials. [ABSTRACT FROM AUTHOR]

Abstract: The electrical sintering characteristics of inkjet-printed line patterns on a paper substrate were investigated by varying initial pattern resistance, input voltage, sintering time, and input voltage profile. The initial resistance was controlled by preheating the patterns, and its range was between 500Ω and 5MΩ. Depending on the input voltage and initial resistance, there exist three different regions: sintering, no change, and blowout. While no sintering is observed for too high initial resistance, blowout of printed lines occurs for a larger input voltage. For the initial resistance lower than ~100kΩ and the input voltage ranging from 20V to 40V, all the printed lines are electrically sintered within a short time without damaging the underlying paper substrates. When using the two-step voltage profile, the final resistance of lines becomes five times smaller than the resistance with the one-step voltage profile due to the increase in the grain size and the reduction in the void area, and no burning or blowout occurs in the lines. Due to its many advantages, the electrical sintering can provide a fast, reliable and effective way to fabricate high quality inkjet-printed conductive patterns for various printed electronics applications. [Copyright &y& Elsevier]

Voltage-controlled three-phase three-leg inverters are widely applied in various occasions. The inverters are generally switched to the current-controlled mode to limit the fault currents when short-circuit faults happen. Under symmetrical fault, the inverter can be controlled as a symmetrical, three-phase current source. However, the voltage limiting will happen under asymmetrical fault. As a result, the fault phase currents will be distorted and cannot be completely controlled. Considering that the voltage limiting is mainly caused by large load impedance of healthy phase under asymmetrical fault, the voltage limiting is avoided by paralleling the virtual impedance with the output filter capacitor in this paper. As a result, the current limiting loop is not broken and the fault phase currents can be effectively controlled. The implementation of virtual impedance in control system and the influence of virtual impedance on the stability of system are also analyzed in detail in this paper. The theoretical results are validated by experiments. [ABSTRACT FROM AUTHOR]

Low cost solutions for long tag display were proposed in this paper. Fewer IC chips were used in the new circuit which was proved to be feasible by simulation. In our scheme, the display area was divided into several parts and each part was controlled by a separate master switch which was connected to the additional TFT switch of every pixel in this partition. In this way, each part of the picture could be refreshed in turn. The total number of gate lines could be reduced by several times and fewer signal terminals of IC were required in a result. The simulation results of schematic and signal timing showed that the driving voltages in different regions could all meet the display requirements. [ABSTRACT FROM AUTHOR]

Paper Spray (PS) is an ambient ionisation technique that is conceptually simple, economical, direct and versatile. In its simplest form, the procedure for operation relies on the application of an electric potential to a triangular-shaped paper substrate with the addition of an extraction/spray solvent to generate charge droplets, without requiring any pneumatic assistance. Despite its promise and rapidly growing popularity, there are some practical challenges associated with PS implementation with scope to enhance its performance further. One such challenge relates to only a small fraction of the Taylor cone expansion being sampled at the MS inlet. In this work we propose a new arrangement for PS, which retains the inherent advantages of this popular technique without introducing additional variables, by using an ambient ion focusing lens that is held at the same potential as the paper substrate. A thorough investigation, consisting of visual spray inspection, electric field simulations and analytical evaluation, including analysis of paracetamol from saliva, shows that ambient ion focusing can provide up to a 50% improvement in spray stability, 60% increase in signal intensity and a 30% improvement in detection limits for routine paper spray mass spectrometry analysis. [Display omitted] • Ion lens arrangement provides a simple means to produce a stable and collimated beam profile. • Ambient ion focusing leads to improvements in spray stability, signal intensity, accuracy and detection limits. • Analysis of paracetamol in saliva is demonstrated using ambient ring lens paper spray mass spectrometry. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (μPADs) are a promising solution for a wide range of point-of-care applications. The feasibility of inducing ion concentration polarization (ICP) on μPADs has thus far attracted little attention. Accordingly, this study commences by demonstrating the ICP phenomenon in a μPAD with a Nafion ion-selective membrane. We are the first to measure the current-voltage curve on a Nafion-coated μPAD in order to indicate that the ion depletion occurs and the ICP is triggered when the current reaches the limiting current. The ICP effect is then exploited to preconcentrate fluorescein on μPADs incorporating straight and convergent channels. By an optimal geometric design, it is shown that the convergent channel results in a greater preconcentration effect than the straight channel. Specifically, a 20-fold enhancement in the sample concentration is achieved after 130 s given an initial concentration of 10-5 M and an external potential of 50V. By contrast, the straight channel yields only a 10-fold improvement in the concentration after 180 s. Further, the practical feasibility of the proposed convergent-channel μPAD is demonstrated using fluorescein isothiocyanate labeled bovine serum albumin. The experimental results show that a 15-fold enhancement of the initial sample concentration (10-5 M) is obtained after 120 s given an external potential of 50V. [ABSTRACT FROM AUTHOR]

Keywords: amides; carbodications; carbocations; cations; Lewis acids EN amides carbodications carbocations cations Lewis acids 1 1 1 10/24/23 20231018 NES 231018 B Dicationic diiminium pyridine adducts b distinctively concentrate their positive charges at the diiminium carbon atom, a characteristic vividly portrayed in their molecular electrostatic potential. Amides, carbodications, carbocations, cations, Lewis acids. [Extracted from the article]

In last period many distribution system operators (DSO) invest significant amount of money in smart metering system. Those investments are in part due to regulatory obligations and in part due to needs of DSO (utilities) for knowledge about electric energy consumption. Term - electric energy consumption, refers not only on real consumption of electric energy but also on data about peak power, unbalance, voltage profiles, power losses etc. Data which DSO can obtain from smart meters depend on type of smart metering system. Further, smart meters as source of data can be implemented in transformer stations (TS) MV/LV and in LV grid at consumer level. Generally, smart meters can be placed in any node of distribution grid. As amount of smart meters is greater, the possibility of data analysis is greater. In this paper a smart metering system of J.P Elektroprivreda HZ HB d.d, Mostar, Bosnia and Herzegovina will be presented. One statistical approach for analyzing of advanced metering data of TS MV/LV will be presented. Statistical approach presented here is powerful tool for analyzing great amount of data from distribution grid in simple way. For example, transformer in TS MV/LV can be overloaded for 30%, but overload period can be for example single one-hour period in whole year. With smart meter data, false conclusions can be avoided. In concerned case, grid operation engineer will not make decision of transformer replacing. With knowledge of only max. power of transformer (without time series data), false conclusion can be adopted about transformer replacing. This can increase costs of grid operation for DSO. Smart metering can help in transformer monitoring. Voltage drop in LV buses of TS MV/LV can be 10% for example. It means that quick intervention in grid must be performed. But, period of increased voltage drop can be only single one-hour period in whole year (for example). On other side, TS MV/LV can have voltage drop of 7% for example in halfyear period. These data, obtained by smart meters, can help in issuing of priority grid investments. Main contribution of this paper is in performing of the statistical analysis of smart meter data in distribution grid and using the obtained results in maintenance/investment planning process. [ABSTRACT FROM AUTHOR]

On the development of flexible electronics, a highly flexible nonvolatile memory, which is an important circuit component for the portability, is necessary. However, the flexibility of existing nonvolatile memory has been limited, e.g. the smallest radius into which can be bent has been millimeters range, due to the difficulty in maintaining memory properties while bending. Here we propose the ultra flexible resistive nonvolatile memory using Ag-decorated cellulose nanofiber paper (CNP). The Ag-decorated CNP devices showed the stable nonvolatile memory effects with 6 orders of ON/OFF resistance ratio and the small standard deviation of switching voltage distribution. The memory performance of CNP devices can be maintained without any degradation when being bent down to the radius of 350 mm, which is the smallest value compared to those of existing any flexible nonvolatile memories. Thus the present device using abundant and mechanically flexible CNP offers a highly flexible nonvolatile memory for portable flexible electronics. [ABSTRACT FROM AUTHOR]

As a critical component of a high-voltage direct current (HVDC) transmission system, resin impregnated paper (RIP) wall bushing has become a weak point because of its surface charge accumulation. This paper studies a model RIP wall bushing core designed by the equal capacitance method. The stationary resistive field along the gas–solid interface of the RIP wall bushing core is investigated theoretically by a gas model, which considers the non-linearly field-dependent volume conductivity. The results show that the gas conductivity along the core surface tends to be an arched distribution from the high-voltage conductor to the end shielding screen. The surface charge mainly accumulates at the turning point of the radius, which may threaten the core's insulation. Then, the surface charge is obtained through a measurement system, where the experimental results are highly consistent with the simulation results. Considering the time constant of charge dissipation is nearly 15 min, it would be better to measure the surface charge on one axial direction of RIP wall bushing core after each voltage application. The simulation and experimental results of this paper can guide the design of a RIP wall bushing core. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses recent progress in and challenges of threshold voltage control for advanced high-k/metal-gated (HKMG) devices. It presents the impact on threshold voltage (V t) control of incorporating La and Al into HKMG devices. A dipole moment model explaining V t tuning of HfSiON/metal-gated MOSFETs is proposed. In addition, a dual channel scheme that allows La2O3 capping in NMOS and a SiGe channel in PMOS to achieve acceptable V t for HKMG CMOS devices will be discussed. Also shown is the impact of the robustness of the SiO2/Si interface on the HKMG MOSFET V t-equivalent oxide thickness (EOT) roll-off. Finally, techniques to improve the interface quality of a HKMG stack will be discussed. [Copyright &y& Elsevier]

Tunable piezoresistive sensors based on a drawing on paper with different grades of pencils are proposed. While an external mechanical strain is applied to U-shape resistors prepared by pencil drawings on paper, an increase in the gauge factor with an increase in the graphite resistance is found. The result is attributed to the tunneling effect between neighboring graphite during the drawing process, further suggesting that different-grade pencil drawings can tune the piezoresistive properties. Through many cycles of repeatedly applied and released force, the output voltage for an HB pencil was found to be more sensitive than that for a 9B pencil. [ABSTRACT FROM AUTHOR]

Delivering high power quality in single‐phase distribution has witnessed more challenges especially with the increased penetration of single‐phase distributed generation (DG). This paper proposes a smart solid‐state‐based transformer, which aims to replace traditional ones, for single‐phase distribution laterals, and provide load balancing and protection to the three‐phase main feeders, that is based on connecting the single‐phase lateral to the three‐phase main feeder through a power electronics converter. This converter transfers balanced power from and to the three‐phase feeder while automatically regulating the lateral single‐phase voltage, hence, assuring high power quality without requiring any transformer on‐load tap changer. A 7‐level packed‐U‐cells (PUC) single‐phase inverter topology was used to deliver single‐phase regulated sinusoidal voltage to the AC loads, and at the same time, it is able to deliver DC power to DC loads. The simulation and hardware‐in‐the‐loop (HIL) results have shown that the proposed topology delivers high power quality for both AC and DC loads under different operating scenarios. Moreover, the converter can play the role of a solid‐state protection device coordinated with other up‐ and downstream protective devices. Finally, this system can be integrated within the smart grid allowing more flexibility for automation and efficient control of the grid. [ABSTRACT FROM AUTHOR]

Industrial wireless mesh networks (WMNs) have been widely deployed in various industrial sectors, providing services such as manufacturing process monitoring, equipment control, and sensor data collection. A notable characteristic of industrial WMNs is their distinct traffic pattern, where the majority of traffic flows originate from mesh nodes and are directed towards mesh gateways. In this context, this paper adopts and revisits a routing algorithm known as ALFA (autonomous load-balancing field-based anycast routing), tailored specifically for anycast (one-to-one-of-many) networking in WMNs, where traffic flows can be served through any one of multiple gateways. In essence, the scheme is a hybrid-type routing strategy that leverages the advantages of both back-pressure routing and geographic routing. Notably, its novelty lies in being developed by drawing inspiration from another field, specifically from the movement of charges in an electrostatic potential field. Expanding on the previous work, this paper explores further in-depth discussions that were not previously described, including a detailed description of the analogy between an electrostatic system and a WMN system based on precise mapping perspectives derived from intensive analysis, as well as discussions on anycast, numerical methods employed in devising the ALFA scheme, its characteristics, and complexity. It is worth noting that this paper addresses these previously unexplored aspects, representing significant contributions compared to previous works. As a completely new exploration, a new scheduling strategy is proposed that is compatible with the routing approach by utilizing the potential-based metric not only in routing but also in scheduling. This assigns higher medium access priority to links with a larger potential difference. Extensive simulation results demonstrate the superior performance of the proposed potential-based joint routing and scheduling scheme across various aspects within industrial WMN scenarios. [ABSTRACT FROM AUTHOR]

This study investigates the electrical aging characteristics of oil-paper composite insulation. In this paper, a coils model and test system for oil-paper transformer insulation are designed. The electrical aging tests of the model coils at room temperature and operating temperature are performed using the step-stress method. A new method for estimating the unknown parameters in the inverse power exponent model is proposed, and the inverse power model life formula expressed by voltage and electric field strength is obtained. Considering the electrical aging process at the operating temperature, the allowable field strength of the inter-turn insulation of oil-immersed transformers can be improved. The new parameter estimation method proposed in this paper can be used to calculate the unknown parameters of the step-stress solid insulation aging model. This method has a clear physical meaning and can be solved easily. When the stressed voltage is below a certain threshold value, the life of the transformer coil turn-to-turn insulation grease oiled paper model is longer at operating temperatures compared with that at room temperature; when the voltage is higher than the threshold, it presents the opposite tendency. [ABSTRACT FROM AUTHOR]

Abstract: Point-of-care testing (POCT) of infectious bacterial agents offers substantial benefits for disease diagnosis, mainly by shortening the time required to obtain results and by making the test available bedside or at remote care centers. Immunochromatographic lateral flow biosensors offer a low cost, highly sensitive platform for POCT. In this article, we describe the fabrication and testing of a multiplex immuno-disc sensor for the specific detection of Pseudomonas aeruginosa and Staphylococcus aureus. Antibody conjugated gold nanoparticles were used as the signaling agents. The detection range of the bacteria lies within 500–5000CFU/ml. The advantage of the immuno-disc sensor is that it does not require any preprocessing of biological sample and is capable of whole cell bacterial detection. We also describe the design and fabrication of a compact portable device which converts the color intensity of the gold nanoparticles that accumulate at the test region into a quantitative voltage reading proportional to the bacterial concentration in the sample. The combination of the immuno-disc and the portable color reader provides a rapid, sensitive, low cost, and quantitative tool for the detection of a panel of infectious agents present in the patient sample. [Copyright &y& Elsevier]

For islanded microgrids, droop-based control concepts have been developed both in single and three-phase variants. The three-phase controllers often assume a balanced network; hence, unbalance sharing and/or mitigation remains a challenging issue. Therefore, in this paper, unbalance is considered in a three-phase islanded microgrid in which the distributed generation (DG) units are operated by the voltage-based droop (VBD) control. For this purpose, the VBD control, which has been developed for single-phase systems, is extended for a three-phase application and an additional control loop is added for unbalance mitigation and sharing. The method is based on an unbalance mitigation scheme by DG units in grid-connected systems, which is altered for usage in grid-forming DG units with droop control. The reaction of the DG units to unbalance is determined by the main parameter of the additional control loop, viz., the distortion damping resistance, Rd. The effect of Rd on the unbalance mitigation is studied in this paper, i.e., dependent on Rd, the DG units can be resistive for unbalance (RU) or they can contribute in the weakest phase (CW). The paper shows that the RU method decreases the line losses in the system and achieves better power equalization between the DG unit's phases. However, it leads to a larger voltage unbalance near the loads. The CW method leads to a more uneven power between the DG unit's phases and larger line losses, but a better voltage quality near the load. However, it can negatively affect the stability of the system. In microgrids with multiple DG units, the distortion damping resistance is set such that the unbalanced load can be shared between multiple DG units in an actively controlled manner rather than being determined by the microgrid configuration solely. The unit with the lowest distortion damping resistance provides relatively more of the unbalanced currents. [ABSTRACT FROM AUTHOR]

Much of oil-filled (OF) cable has been used for a long time as 66- to 500-kV extrahigh-voltage cable. Sometimes we can see extremely degraded tan δ oil (several tens of percent of tan δ, for example) in joint boxes, etc. The values of tan δ calculated by a simple combination model of paper/oil show that the oil-impregnated paper with such a high tan δ oil likewise has an extremely high tan δ, which must result in thermal breakdown. However, such an event has not taken place up to the present in actually operated transmission lines. This fact suggests that some mechanism for the suppression of tan δ has acted in the paper insulation impregnated with degraded tan δ oil. Therefore, we investigated in detail the tan δ characteristics of paper impregnated with extremely high tan δ oil. In addition, based on the investigation results, we developed a method for simulation of heat generation by dielectric loss in an OF cable joint (which has degraded tan δ oil). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(1): 1-10, 2012; Published online in Wiley Online Library (). DOI 10.1002/eej.21184 [ABSTRACT FROM AUTHOR]

Abstract: The unwanted high threshold voltage (Vt ) is the major challenge for metal-gate/high-κ CMOS especially at small equivalent-oxide-thickness (EOT). We have investigated the high Vt issue that is due to flat-band voltage (Vfb ) roll-off at smaller EOT. A mechanism of charged oxygen vacancies formed by interface reaction was proposed to explain the Vfb roll-off effect. This interface reaction can be decreased by inserting a thin interfacial SiON and using novel low temperature process. The self-aligned and gate-first metal-gate/high-κ CMOSFETs using these methods have achieved low Vt and good control of Vfb roll-off at small 0.6–1.2nm EOT. [Copyright &y& Elsevier]