Primary Conductor Research Articles

Effects of PACAP on the Circadian Changes of Signaling Pathways in Chicken Pinealocytes

Pituitary adenylate cyclase-activating polypeptide (PACAP) is involved in the regulation of circadian rhythms. In mammals, the brain's biological clock is the suprachiasmatic nucleus, receiving photic information from the retina through the retinohypothalamic pathway, where PACAP is the main cotransmitter of glutamate. The primary conductor of circadian rhythms of birds is the pineal gland. The presence of PACAP has been demonstrated both in the rat and avian pineal gland, where PACAP stimulates melatonin synthesis. The signaling mechanism, by which PACAP modulates melatonin synthesis and circadian rhythmic functions of the pineal gland, is only partially known. The aim of the present study was to investigate the effects of PACAP on the changes of p38 mitogen-activated protein kinase (MAPK) and 14-3-3 protein in chick pineal cell culture both of which have been shown to participate in the regulation of rhythmic functions. Pineal cells were treated with 1, 10, or 100 nM PACAP38 every 4 h during a 24-h period. The phosphorylation of p38 MAPK showed obvious changes during the observed 24 h, while the level of 14-3-3 protein did not. We found that the lowest used dose of PACAP did not cause any phase alteration in p38 MAPK phosphorylation. Ten nM PACAP induced a 4-h-long delay and 100 nM abolished the circadian changes of p38 MAPK phosphorylation. PACAP was not effective on the level of 14-3-3 protein in the early morning hours, and only the highest tested dose (100 nM) could evoke a change in the appearance of 14-3-3 between midday and midnight hours. In summary, PACAP modulated the phosphorylation of p38 MAPK and the appearance of 14-3-3 protein in the chicken pineal cells, but these effects were dose dependent and also depended on the time of day.

Three-phase Current Measurement Using Single Toroidal-core Current Transformer

100:1 single-core prototype current transformer is described to measure line currents simultaneously in balanced or unbalanced three-phase systems. The transformer core comprises a toroidal and a wye-shaped inner core accommodating primary line conductors and secondary detecting windings. Mutual effects of line current fluxes on current measurements are eliminated by three air-gap slits introduced along the toroidal section of the core. Calibration and performance of the transformer are discussed for burdens 0.1 Ω and 1 Ω in the current range 0–50 A.

Wound magnetic core consequences on false residual currents

PurposeGeometric or magnetic anomalies in the wound magnetic core of a residual current circuit breaker can be responsible of its abnormal tripping. The purpose of this paper is to analyse the core shape contribution to false residual currents (FRCs).Design/methodology/approachTo study precisely the core shape contribution, FEM simulations are investigated. First a 2D multilayer geometry is described thanks to linear regions. Then an apparent anisotropic bulk core is developed and validated in 2D and in 3D.FindingsThe air gaps between the magnetic layers develop a shielding effect responsible of the core high sensibility to primary conductors eccentricity. This effect can be easily represented using an anisotropic bulk core model.Research limitations/implicationsThe anisotropic material model is basic and has known limitations. Future research should see the development of a new model.Originality/valueFRCs can considerably disturb operation of residual current device. This paper provides new hypothesis on the origin of theses currents and proposes an anisotropic magnetic material model that simplifies FRC study.

Effects of magnetic core geometry on false detection in residual current sensor

Under high-supply current, residual circuit breakers are subject to abnormal tripping, caused by false residual currents. Geometric or magnetic anomalies in the circuit breaker ring core seem to be responsible for these abnormal currents. This paper studies a few anomalies (spiral shape effect, conductor eccentricity, lamination effect) and calculates different contributions using the finite element simulations. The results show that the ring core, made of thin wound magnetic tape, is particularly sensitive to primary conductor eccentricity.

Ni/Cu 전극을 적용한 고효율 실리콘 태양전지의 제작 및 특성 평가

We have applied front contact metallization of plated nickel and copper for high efficiency passivated emitter rear contact(PERC) solar cell. Ni is shown to be a suitable barrier to Cu diffusion as well as desirable contact metal to silicon. The plating technique is a preferred method for commercial solar cell fabrication because it is a room temperature process with high growth rates and good morphology. In this system, the electroless plated Ni is utilized as the contact to silicon and the plated Cu serves as the primary conductor layer instead of traditional solution that are based on Ti/Pd/Ag contact system. Experimental results are shown for over 20 % PERC cells with the Plated Ni/Cu contact system for good performance at low cost.

Floating Capital: The Trouble with Whiteness on Twain's Mississippi

In the antebellum slave market that was rigorously conducted on and along the Mississippi River, Mark Twain recognized a fundamental plot that he found still visible in his own post-frontier United States, where the promise of a free, unbounded space of nationalist imagining had finally dried up. The fundamental national plot Twain noted in the antebellum Mississippi's volatile market culture involved selling something that does not belong to you, the misappropriation of others' labor and sentience. Since the late eighteenth century, the river had been a primary conductor of commercial traffic, carrying, among more innocent commodities, slaves and slave-grown cotton. Imagining the great river highway, Twain identified our American pleasure with a commercial imperialism which perpetuated the piracy and slaving that had characterized the era of mercantile capitalism; in his Mississippi River fictions, he reproduces in miniature the volatile commercial space of the early modern oceans. For Twain, the North American West had not been about the political disinterest, domestic economy, and republican virtue long associated with agricultural settlement, from eighteenth-century European agrarian philosophy through Thomas Jefferson. The Mississippi River was the West that Twain returned to, again and again, because it was water and not land that could ever be settled. The river was a carrier

High-frequency modeling of a current transformer by finite-element simulation

This paper depicts a method to elaborate a high-frequency (100 kHz to 50 MHz) model of a current transformer. The method uses finite-element analysis to determine the values of the parameters of the circuit model; all electrostatic and magnetic couplings are taken into account and calculated. The paper shows how parasitic capacitance and flux leakage alter the transformer frequency response. These effects are deeply modified by the primary conductor position, by an air gap in the core, and by the presence of a shielding case around the transformer. The paper compares simulation results with experimental ones to show the accuracy of the models.

Ni/Cu metallization for low-cost high-efficiency PERC cells

Abstract Low-cost metallization process with excellent performance for high-efficiency passivated emitter and rear cell (PERC) is described. The fabrication processes of the high-efficiency silicon solar cell are too expensive and complicated to be commercialized widely. It is necessary to develop inexpensive metallization technique without degradation of the cell performance. In this paper, Ni/Cu contact system was used to fabricate low-cost high-efficiency solar cells instead of traditional solution that are based on evaporated Ti/Pd/Ag. The electroless plated Ni is utilized as the contact to silicon and the electroplated Cu served as the primary conductor layer. This metallization scheme has proven to be successful.

The conductors of the 50 kA superconducting transformer for SSTF

The 50 kA transformer for Samsung Superconductor Test Facility (SSTF), which will charge the Korean Superconducting Tokamak Advanced Research cable-in-conduit conductor samples for 1 s is under design. The NbTi based conductors for primary and secondary windings are described. The primary winding conductor consists of six NbTi and six stainless steel strands cabled around rectangular copper core. Such a design was previously used by Kurchatov Institute in small SMES windings. The secondary winding conductor consists of 24 subcables wrapped around and soldered to a copper strip. Each subcable consists of six NbTi strands cabled around one copper strand. NbTi strands for both primary and secondary windings are 0.85 mm in diameter. NbTi wires have 8910 6-μm filaments. Both primary and secondary winding conductors have large current and temperature margins to ensure a reliable operation of the superconducting transformer.

Multilayered transformer utilizing Mn‐Zn ferrite and its application to a forward‐type DC–DC converter

AbstractThis paper describes the electrical characteristics of a multilayered transformer composed of a Mn‐Zn ferrite core, and primary and secondary conductors positioned alternately not only in the vertical direction but also in the horizontal direction. In order to elucidate the operating characteristics of the two types of transformers, one was given the conventional planar winding structure and the other the new winding structure described above, and a two‐dimensional finite element method that took account of the two conditions and a constant input voltage and load current was introduced. The coupling coefficient of the conventional multilayered transformer deteriorated with increasing load current. But the coupling coefficient of the proposed multilayered transformer was independent of the load current. A forward‐type DC–DC converter using the new multilayered transformer had higher efficiency than a converter using the conventional multilayered transformer. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 1–8, 2001

The superconducting transformer of the Samsung Superconductor Test Facility (SSTF)

In the frames of designing the SSTF (Samsung Superconductor Test Facility) for the KSTAR (Korea Superconducting Tokamak Advanced Research), the 50 kA transformer charging a CICC (cable-in-conduit conductor) short sample for one second is now under design. The primary winding conductor consists of six NbTi and six stainless steel strands tabled around a low RRR rectangular copper core, which was used by Kurchatov Institute in small SMES (superconducting magnetic energy storage) windings. The secondary winding consists of 24 subcables wrapped around and soldered to a low RRR copper strip. Each subcable consists of six NbTi strands cabled around a copper strand. The strands for primary and secondary windings are 0.85 mm diameter NbTi wires with six micrometer 8910 filaments. Both primary and secondary conductors have large current and temperature margins to ensure a reliable operation of the superconducting transformer. The primary coil is placed in a cylindrical LHe vessel. The four secondary turns are glued to the outer surface of the LHe vessel. The joints between the transformer and the sample are described.

Plasma-enhanced atomic layer deposition of Ta and Ti for interconnect diffusion barriers

Thin films of inert, refractory materials are used in semiconductor interconnect applications as diffusion barriers, seed, and adhesion layers. A typical example is the use of a thin, conformal Ta or Ti/TiN films on the walls of a dielectric trench or via which reduces or eliminates out-diffusion of the primary conductor, usually Cu, into the dielectric. Atomic layer deposition is a known technique which is intrinsically conformal and is appropriate for this application. Plasma enhancement of the process allows deposition at significantly lower temperatures than conventional chemical vapor deposition, which is a requirement for low-k dielectrics. Tantalum films deposited at 25–400 °C using ALD with a TaCl5 precursor and atomic hydrogen as the reactive species at up to a rate of 1.67 Ang/cycle are amorphous, conformal, and show moderate or controllable levels of impurities; primarily oxygen and a small level of Cl. Similar results have been observed for Ti using TiCl4 as a precursor. The process scales to manufacturing dimensions and applications and will facilitate the extension of interconnect technology beyond (below) 100 nm dimensions.

Ｍｎ‐Ｚｎフェライトを用いた積層型トランスにおける巻線構造に関する検討

This paper describes the characteristics of sandwich-type thin transformers with a fine-grain Mn-Zn ferrite core and three kinds of arrangements of planar windings. Thin transformer with primary and secondary conductors positioned alternately have excellent load characteristics. The results of the flux distribution analyses in the transformers with three kinds of winding structures show that the above mentioned transformer with primary and secondary conductors positioned alternately has good flux coupling between primary and secondary windings even when load current is flowing.

Sputter deposition for semiconductor manufacturing

Sputter deposition, also known as physical vapor deposition, or PVD, is a widely used technique for depositing thin metal layers on semiconductor wafers. These layers are used as diffusion barriers, adhesion or seed layers, primary conductors, antireflection coatings, and etch stops. With the progression toward finer topographical dimensions on wafers and increasing aspect ratios, the broad angular distribution of depositing, sputtered atoms leads to poor or nonexistent coverage in deep features. This has been partially addressed using directional sputtering techniques such as collimated sputtering or long-throw sputtering. More recently, work originating in IBM has moved toward the deposition of films from metal-rich plasmas fed by sputtering, a technique known as I-PVD (for ionized PVD). This technique, based on fairly minor modifications of existing PVD systems, solves many of the intrinsic problems of PVD and appears headed for widespread manufacturing applications.

Distribution feeder loss analysis by using an artificial neural network

This paper proposes an artificial neural network (ANN) based feeder loss analysis for distribution system analysis. The functional-link network model is examined to form the artificial neural network architecture to derive various loss calculation models for distribution feeders with different configurations. The ANN is a feedforward network that uses a standard back-propagation algorithm to adjust the weights on the connection path between any two processing elements. The typical daily load curve of the study feeder for each season is derived to field test data. A three-phase load flow program is then executed to create the ANN training sets to solve the exact feeder loss. A sensitivity analysis is performed to determine the key factors of feeder loss, which are feeder loading and power factor, primary and secondary conductor length, and transformer capacity. The above key factors form the variables of the ANN input layer. By applying the artificial neural network with pattern recognition capability, this study has developed the seasonal loss calculation models for both an overhead and an underground distribution feeder. Two practical feeders in the Taiwan Power Company (Taipower) distribution system have been selected for computer simulation to demonstrate the effectiveness and accuracy of the proposed ANN loss models. By comparing the loss models derived by the conventional regression technique, it is found that the proposed loss models can estimate feeder loss in a very effective manner and provide a better tool for distribution engineers to enhance system operation efficiency.

Signatures and software find high impedance faults

The detection of high-impedance faults on electrical distribution systems has been one of the most persistent and difficult problems facing the electric utility industry. High-impedance faults result from the unwanted contact of a primary circuit conductor with objects or surfaces that limit the current to levels below the detection thresholds of conventional protection devices. The author describes how recent advances in digital technology have enabled a practical solution for the detection of a high percentage of these previously undetectable faults.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Development of simplified loss models for distribution system analysis

This paper proposes a methodology to derive a simplified model for distribution system loss analysis. According to the typical daily load patterns and the energy consumption of customers, the hourly loading of distribution transformers can be solved. A three-phase load flow program is applied to calculate the feeder power flow so that the hourly feeder loading will be the same as that obtained by the field test. The hourly primary conductor loss, secondary conductor loss, transformer copper loss and core loss are then solved according to the mathematical modeling of system components. The sensitivity analysis of system loss with respect to the feeder loading, power factor, feeder length, transformer capacity is then performed to derive the simplified loss model of distribution feeders. A distribution feeder of Taipower system is then selected for computer simulation to demonstrate the effectiveness of the proposed method. By applying the simplified loss model derived, the daily loss pattern of distribution feeders is solved according to the actual hourly feeder loading. It is concluded that the proposed methodology provides a useful tool for distribution engineers to estimate the operation efficiency of distribution systems in a very effective manner. >

Fuel cell electrolytes: evolution, properties and future prospects

Any electrolyte with sufficient ionic conductivity may be used in a fuel cell, but to avoid concentration gradients in the electrolyte, active conduction should be via an ion produced in one electrode reaction and consumed in the other. This ion must be present at high concentration in the electrolyte. In aqueous fuel cells operating on hydrogen and oxygen, the only useful electrolytes have high concentrations of either H + or OH −, i.e. strong acids or bases. The product of the anode reaction in aqueous acids, H +, occurs as a ‘carrier ion’ complexed by H 2O as H(H 2O) n +, where n lies between 1 and 4. The corresponding cathodic product ion in bases, OH −, is itself a ‘carrier ion’, the reaction product of O 2− (from the reduction of O 2) and H 2O. Phosphoric acid is not an aqueous acid, but a unique self-ionizing amphoteric system, in effect a molten acidic (H +) salt. In molten salts, H + could be the primary conductor, e.g., in molten bisulfates. Less corrosive carbonate melts use a cathodic supply of CO 2 supplied via the gas phase to give CO 2 2− as the O 2− ‘carrier ion’. A similar approach may be used in aqueous carbonates. No carrier material is needed in solid oxides, which conduct directly via O 2− ion. The temperature windows for different electrolytes are limited by performance at the low end and materials considerations at the high end. As a result, there are no electrolyte capable of operation between 480 and 900 K, and between 1050 and 1220 K. Development of electrolytes for these temperature ranges would be valuable.

Application of and rating structure for ground and test devices used in metal-clad switchgear

Ground and test devices are accessories for use in grounding and testing the primary conductors in metal-clad switchgear. The types commonly available and their use are described. It is noted that these devices are not covered by any existing standards. Rating structures and test requirements that should apply to these devices are examined, and a proposal is made for the creation of a standard to cover ground and test devices. >

Residential magnetic and electric fields.

A magnetic flux density (MFD) and electric-field (E-field) data-acquisition system was built for characterizing extremely low-frequency fields in residences. Every 2 min during 24-h periods, MFD and E-field measurements were made in 43 homes in King, Pierce, and Snohomish counties of Washington State. The total electrical energy used in each residence during the 24-h measurement period was also recorded, and maps were drawn to scale of the distribution wiring within 43 m (140 ft) of these homes. Finally, on a separate date, field measurements were made in each home during an epidemiological interview. The results of this study can be summarized as follows: 1) 24-h-average MFD measured at two separate points in the family room were correlated, as were a 24-h-average bedroom measurement and the mean of the two family-room measurements. 2) The 24-h-average family-room MFD and E-field measurements were uncorrelated. 3) The 24-h-average total harmonic distortions of family-room MFD and E-fields were less than about 24% and 7%, respectively. 4) Residential MFD exhibited a definite 24-h (diurnal) cycle. 5) The 24-h-average and interviewer-measured MFD were correlated. 6) Residential 24-h-average MFD were correlated with the wiring code developed by Wertheimer and Leeper. 7) An improved prediction of 24-h-average residential MFD was obtained using the total number of service drops, the distance to neighboring transmission lines, and the number of primary phase conductors.