IR Voltage Research Articles

P‐70: A Novel Peak Luminance Correction Method Based on Global IR Drop Compensation System on AMOLED

In the past year, AMOLED have been widely used in smartphones, laptops, and vehicles. Local excitation luminance is one of the important parameters to measure AMOLED quality. This feature is of great significance for realization of HDR video and getting better visual experience in sunlight environment. Due to IR drop effect in the local display, the performance of peak luminance is often skewed by luminance, chrominance, and gamma curves. The solution is adding a set of Gamma curve debugging at peak luminance of local display, which results in longer take time (TT) and greater aging pressure at high luminance. In this paper, we propose a novel peak luminance correction method based on Global IR (GIR) voltage drop compensation system. In the compensation system, GIR compensation Look‐Up Tables (LUT) is used to accurately tune the luminance, chrominance, and gamma curves that correspond to the local excitation luminance.

“Water‐Salt‐in‐Deep Eutectic Solvent” Method to Optimize Conductivity, Viscosity and Freeze Resistance for Eutectic Electrolytes

AbstractA novel and simple “water‐salt‐in‐deep eutectic solvent” (WS‐DES) strategy is reported here to increase the ionic conductivity, while reducing the viscosity and freezing temperature of deep eutectic solvent (DES). Upon the addition of water and strong electrolyte salt to the DES of [LiTFSI][EG], the conductivity was increased by 16 times, the viscosity was decreased by 36 %, and the freezing temperature was decreased by 30 °C. Additionally, WS‐DES strategy can be well applied to electrolytes for supercapacitor devices. Compared to the initial DES, supercapacitors using WS‐DES electrolyte have higher specific capacitance, better rate performance, lower IR voltage drop, and lower internal resistance. Moreover, the WS‐DES electrolyte also exhibits excellent electrochemical stability under extreme condition even at −40 °C.

The Understanding of the Improved Catalytic Performance of Steam-Activated Fe-N-C Catalyst for Alkaline Hydrazine Fuel Cell

Fe-N-C materials are currently the most promising non-noble-metal-based ORR electrocatalyst, but their low density of surface active sites compared with Pt/C necessitates improving their utilization via porous structures. Previously, we studied modified Fe-N-C catalyst for the oxygen reduction reaction (ORR) in the cathodes of alkaline hydrazine liquid fuel cells (AHFC). Fe-N-C with magnetite particles and hierarchical pore structure was prepared by steam activation. The steam activation process significantly improves the power performance of the AHFC as indicated by the lower IR and activation voltage losses. The steam activation transformed the Fe3C nanoparticles in Fe-N-C into larger Fe3O4 particles, which caused the electrode surface to become more hydrophilic. Here, elimination of the Fe3O4 nanoparticles by acid leaching was conducted to investigate the effect of Fe3O4 nanoparticles, resulting in enhancing power performance for alkaline hydrazine liquid fuel cells.

Development of self-polarized PVDF films on carbon fabrics for sensing applications

The contribution of piezoelectric materials in electrical and electronic devices is increasing day by day owing to their promising unique characteristics. Here, polyvinylidene fluoride (P VDF) films were deposited on carbon fabric through solution cast technique. The evolution of ferroelectric β-phase in the films is controlled by the composition of the casting solution, number of layers of the films and drying conditions. The deposited films were characterized by FT IR, XRD, DSC, optical microscopy and open circuit voltage and closed-circuit current. The use of a hydrated salt in the casting solution, higher number of layers and drying in an oven at 50 °C results in higher content of β-phase. The observations depict that using this simple technique of deposition the output voltage and output current can be tailored as 95 V to 296 V and 1.5 μA to 5 μA for variable force.

Investigation of crevice corrosion of metallic fastened joints in carbon fiber reinforced polymer (CFRP) exposed to coastal seawater

Purpose The purpose of this paper is to study the susceptibility of these three commonly used corrosion resistance fasteners in seawater. For a more practical scenario, a local Atlantic coastal seawater as received was used. Design/methodology/approach Carbon fiber reinforced polymer (CFRP) was fabricated with T700 carbon fiber (Toray Inc.) and VE8084 vinyl ester resin (Ashland) to make a unidirectional composite panel of thickness 1.8 mm. A conductive paint was applied to one of the sample edges that was perpendicular to the fiber direction, providing an electrical contact with carbon fibers to connect a copper wire. This external electric connection was used for potential measurements of both the open circuit potential (OCP) of the CFRP sample, and the mixed potential of the fastened set: consisting of the CFRP and the metallic fastener fastened to it. Three common fastener alloys were selected: 316SS, Monel and Titanium. For this purpose, a high impedance voltmeter was used in conjunction with a saturated calomel reference electrode. Measurements were taken daily. For longer time measurements, a four-channel high impedance analog data logger was used with 30 min sampling rate. Findings For both 316SS and Monel fastened sets, crevice corrosion occurred inside the occluded regions of the set, when immersed in coastal seawater. The attack was more severe for 316 stainless steel set. An isolated island attack of faceted surfaces morphology was seen for 316SS set. While, a circular ring of preferential grain boundary attack appeared for Monel set, indicating an IR (voltage) drop mechanism is more likely operating. Titanium-fastened sets showed high resistance to crevice corrosion when simmered in seawater. However, for long-time exposure, the sets became more susceptible to crevice corrosion attack supported by CFRP attachment (oxygen reduction reaction taking place at the carbon fibers). Originality/value Evidently, titanium, stainless steels and Monel are good candidates for galvanic corrosion resistance. However, their susceptibility to crevice corrosion when coupled with CFRP is a new challenging topic that needs further investigation. This is very important today because the vast application witnessed for CFRP material. This work involves developing an original methodology for this kind of investigation and was done at advanced laboratories of SeaTech at Florida Atlantic University by the Atlantic coastline.

Steam activation of Fe-N-C catalyst for advanced power performance of alkaline hydrazine fuel cells

Alkaline hydrazine liquid fuel cells (AHFC) have been highlighted in terms of high power performance with non-precious metal catalysts. Although Fe-N-C is a promising non-Pt electrocatalyst for oxygen reduction reaction (ORR), the surface density of the active site is very low and the catalyst layer should be thick to acquire the necessary number of catalytic active sites. With this thick catalyst layer, it is important to have an optimum pore structure for effective reactant conveyance to active sites and an interface structure for faster charge transfer. Herein, we prepare a Fe-N-C catalyst with magnetite particles and hierarchical pore structure by steam activation. The steam activation process significantly improves the power performance of the AHFC as indicated by the lower IR and activation voltage losses. Based on a systematic characterization, we found that hierarchical pore structures improve the catalyst utilization efficiency of the AHFCs, and magnetite nanoparticles act as surface modifiers to reduce the interfacial resistance between the electrode and the ion-exchange membrane.

A Self-Calibration Method of Microbolometer With Vacuum Package

Microbolometer is often packaged in a vacuum atmosphere of < 1 Pa to improve its response. The internal pressure of vacuum package always drifts over time. This will lead to the response degradation of microbolometer. To maintain excellent performance and improve device lifetime, a self-calibration method of microbolometer with vacuum package is presented. This method uses the relative change rate obtained by self-heating response to calibrate the IR response according to the linear dependence of self-heating response and IR response at different pressures. Its validity is verified using a microbolometer with series diodes. The degraded IR voltage responses can be corrected to the normal value when the internal pressure increases from 1 Pa to 500 Pa. Furthermore, the relative standard of calibration deviation is small when the internal pressure is no more than 50 Pa.

Mask Technique for Fast and Efficient Training of Binary Resistive Crossbar Arrays

Resistive crossbar arrays, despite their advantages such as parallel processing, low power, and high density, suffer from the sneak path problem created by IR voltage drops. The crossbar non-idealities considerably degrade the accuracy of matrix multiplication operation, which is the cornerstone of hardware accelerated neural networks. In this paper, we propose a novel technique to capture the sneak path problem to enable off-chip learning and weight transfer. The proposed technique can be easily integrated into any neural network training framework. Performance results show a significant improvement after retraining the network with the proposed mask technique. Two mask solutions have been proposed and studied to capture the sneak path problem in resistive crossbar arrays. Both mask solutions were successfully able to achieve classification accuracy close to the baseline accuracy. The tradeoffs between the two solutions are discussed and compared in terms of accuracy, power, and area.

The effect of lithium loadings on anode to the voltage drop during charge and discharge of Li-ion capacitors

The IR voltage drop from the anode and cathode of Li-ion capacitors during charge and discharge was studied. Li-ion capacitors were made with activated carbon cathode and hard carbon anode with different loadings of stabilized lithium metal powder (SLMP). It was found that the LICs with high SLMP loadings showed smaller voltage drop than LICs with low SLMP loadings. It was also found that at low SLMP loadings, the IR voltage drops at high cell voltages were smaller than that at low cell voltages; while at high SLMP loadings, small IR voltage drops were obtained for both low and high cell voltages. The electrochemical impedance spectroscopy confirmed that voltage drops are directly related to the internal resistances of Li-ion capacitors.

Design and Implementation of Block-Based Partitioning for Parallel Flip-Chip Power-Grid Analysis

Power-grid analysis is one of the critical design steps to ensure circuit reliability and achieve performance targets for very large scale integration systems. With each new technology generation, the circuit size has decreased and the power density has increased. Consequently, power-grid analysis has become ever more complex with greater CPU runtime and memory usage requirements. For a state-of-the-art power-grid design with more than 100-million nodes, it is often desirable to partition the power grid into smaller regions and analyze them in parallel by exploiting the locality of flip-chip packages. However, the traditional area-based partitioning strategy may not be best suited to analyze the DC current and ohmic IR voltage drop of a design that has irregular power rails and nonuniform power consumption because such nonuniformity affects the locality of power supply network and the accuracy of analysis. In this paper, we will present the analysis of a flip-chip design with 136-million nodes and propose a block-based partitioning scheme to improve the accuracy of parallel power-grid analysis.

Effective Resistance of a Two Layer Mesh

The effective resistance of a resistive mesh is a commonly used analogy for various scientific and engineering problems such as voltage drop estimation, distributed control including time synchronization and sensor localization, determining the chemical distance among multiple bonds, and finding the distance between two vertices in a graph. Resistive networks are a commonly used structure in electronics to model different elements of an integrated circuit, such as a physical substrate, an integrated circuit layout, and a power distribution network. On-chip power and ground networks are composed of orthogonal metal lines from different metal layers, and a resistive mesh is typically used to model these networks. A two layer mesh is therefore commonly used to analyze IR voltage drops and decoupling capacitor placement. A closed-form expression is described here for the effective resistance between the intersections of a two layer resistive mesh where the horizontal and vertical unit resistances are different. The physical distance between the nodes of interest and the ratio between the horizontal and vertical resistances are included in the expression. The maximum error of the closed-form expression, as compared with the exact solution, is less than 5% for a wide range of . The error further decreases with greater separation between the nodes of interest.

Efficient algorithms for fast IR drop analysis exploiting locality

Closed-form expressions and related algorithms for fast power grid analysis are proposed in this paper. Four algorithms to determine the IR voltage drop at an arbitrary node are described when voltage supplies and current loads are non-uniformly distributed throughout a power grid. Two techniques are used to determine the effective impedance in a non-uniform and semi-uniform power grid. An effective resistance model is proposed for semi-uniform power grids. The principle of spatial locality is exploited to accelerate the proposed power grid analysis process. Since no iterations are required for the proposed IR drop analysis, the proposed algorithms are over 60 and two times faster for smaller power grids composed of less than five million nodes and over 175 and three times faster for larger power grids composed of more than 25million nodes as compared to, respectively, the random walk and second order iterative methods. The proposed method exhibits less than 0.3% error.

IR Voltage in Crevices during Crevice Corrosion and Sacrificial Cathodic Protection

This paper describes work related to Konrad G. Weil's research interests while a visiting scholar in the Pickering Laboratory at Penn State University in the period, 1991–2003. Specifically, this paper describes the role of IR voltage in (i) causing corrosion attack and hydrogen evolution and absorption inside crevices in iron, and (ii) increasing the lifetime of environmentally friendly electroplates used for corrosion prevention. I is the current flowing in a cavity's (e.g., crevice's) electrolyte and R is the resistance of this electrolyte path.

The role of electrolyte concentration on crevice corrosion of pure nickel

AbstractIn this work an artificial crevice electrode was used in conjunction with a fine microprobe assembly to measure the potential inside the crevice. Using this setup crevice corrosion of commercially pure nickel was investigated in sulfuric acid with concentrations: 0.5, 1 and 2N. The outer surface of the Ni was held at a passive potential of 530 mV(SCE) while the experiment was running. The results showed a steep potential decay observed in all concentrations. For 0.5, 1 and 2N H2SO4, the total potential drop inside the crevice was: 681, 619 and 593 mV, respectively. This indicates the higher the acid concentration is the lower the potential drop will be. On the other hand, the measured current was highest (4.09 mA) for 2N and lowest (1 mA) for 0.5N. On the crevice wall a boundary was found to exist between the passive and the active regions. These findings point toward the IR voltage drop mechanism operating for this system.

Effects of Clamp Load on PEFC Performance and Over Voltages (Comparison of Contact Pressure between Paper and Cloth Type GDLs)

The performance and over voltages of the polymer electrolyte fuel cells (PEFC) with paper and cloth type gas diffusion layers (GDL) were evaluated using a test apparatus in which the clamp load of a test cell could be changed. The contact pressure distribution of GDL was also evaluated using a pressure measuring film. Under moderate humidification condition, an increase in the clamp load is effective in reducing IR over voltage, and thereby improving the PEFC performance. The performance of the paper type GDL is higher than that of the cloth type GDL at all clamp loads. The GDL contact pressure has a peak at the center of the separator rib and has a bottom at the separator channel. The pressure distribution becomes more uniform when using the paper type GDL rather than the cloth type GDL. The GDL electrical resistance amounts to only about 20% of the overall IR resistance. The difference of the overall IR voltage between the paper and cloth type GDLs is more significant than that of the GDL electrical resistance. This is because the uniform pressure distribution obtained with the paper type GDL enhances the contact between MEA and GDL, thereby reducing the MEA resistance.

Fast Response Polypyrrole Actuators with Auxiliary Electrodes

Electrochemical polypyrrole (PPy) actuators, prepared electrochemically from a methyl benzoate solution of tetra-n-butylammonium trifluoromethanesulfonate (TBACF3SO3), have been studied to improve the response rate by two methods; 1) a PPy film attached with plural auxiliary electrodes of thin Au coils, 2) a PPy film equipped with a compliant Au electrode on one side of the film. With increasing the number of auxiliary electrodes for the first method, the film responded faster as if it were a shorter film. These results are due to the decrease in the IR voltage drop along the film from the electrodes and also due to the increased current to the whole film via plural electrodes. The PPy film with the Au thin layer (the second method) exhibited up to 8.8%/s strain rate, which was much faster than that (0.5%/s) without the auxiliary electrodes, keeping the maximum strain of 12–13%. The auxiliary electrodes improved not only the response speed of the PPy actuators but also the durability upon cycling electrochemically.

Evaluation of corrosion rate from polarisation curves not exhibiting a Tafel region

Evaluation of corrosion rate by Tafel extrapolation is often impossible, simply because an experimental polarisation curve does not exhibit linear Tafel regions. This paper shows how such curves for the Fe/H 2O/H +/O 2 corrosion system can be accurately deconstructed to furnish both kinetic and thermodynamic parameters for the anodic and cathodic reactions. The curved anodic branch (due to film formation) is then amenable to correction for IR voltage drop and the resulting Tafel slope and other parameters are then substituted in the Tafel equation to accurately determine i corr. An alternative method to obtain the anodic Tafel slope has been used to validate the above approach. Polarisation curves describing the inhibition of mild steel in industrial cooling water were scanned/digitised from the literature.

Simultaneous power supply planning and noise avoidance in floorplan design

With today's advanced integrated circuit manufacturing technology in deep submicron (DSM) environment, we can integrate entire electronic systems on a single system on a chip. However, without careful power supply planning in layout, the design of chips will suffer from local hot spots, insufficient power supply, and signal integrity problems. Postfloorplanning or postroute methodologies in solving power delivery and signal integrity problems have been applied but they will cause a long turnaround time, which adds costly delays to time-to-market. In this paper, we study the problem of simultaneous power supply planning and noise avoidance as early as in the floorplanning stage. We show that the problem of simultaneous power supply planning and noise avoidance can be formulated as a constrained maximum flow problem and present an efficient yet effective heuristic to handle the problem. Experimental results are encouraging. With a slight increase of total wirelength, we achieve almost no static IR (voltage)-drop requirement violation in meeting the current and power demand requirement imposed by the circuit blocks compared with a traditional floorplanner and 45.7% of improvement on a /spl Delta/I noise constraint violation compared with the approach that only considers power supply planning.

IR voltage switch in delayed crevice corrosion and active peak formation detected using a repassivation-type scan

This paper investigates the induction period preceding crevice corrosion in the spontaneously passive iron/0.2 M Na 2SO 4 + 0.025 M K 2CrO 4 (pH 9) system. The focus is on the interaction between pH, corrosion products and the IR > Δ ϕ * criterion for initiating crevice corrosion, where ionic current I is the accumulation of metal dissolution currents on the crevice wall, R is the resistance of this electrolyte path, and Δ ϕ * is the difference between E x = 0 at the crevice's opening and E A/P at the active/passive transition in the crevice solution's polarization curve. Potential microprobe measurements show that IR < Δ ϕ * switches to IR > Δ ϕ * to end the induction period and start crevice corrosion. Thus, the switch occurs at a critical combination of increasing E A/P (decreasing Δ ϕ *), i pass (increasing I), and gas accumulation which decreases the effective crevice opening dimension, a (increasing R). During the switch, E x = L at the bottom of the crevice, was just inside the active peak of the crevice solution's polarization curve, so crevice corrosion started at the bottom of the crevice. Arrival at the critical combination of E A/P, i pass and a was promoted by acidification of the crevice electrolyte. H 2 gas in the crevice also likely played a role. A repassivation-type scan revealed the active peak that had formed during the induction period as the pH decreased from 9 to 4.

Behaviour of crevice corrosion in iron

Crevice corrosion was investigated in iron exposed to a strong-buffered acetate solution (0.5 M CH 3COOH + 0.5 M NaC 2H 3O 2), pH = 4.66. The current and the potential gradient within the crevice were measured at crevice depth ( L) = 7.35, 8, 10, and 15 mm, for a crevice that was positioned facing the electrolyte in a downward position. A remarkable shift in potential (>1.2 V) in the active direction was measured inside the crevice cavity, when the potential at the outer surface was held at 800 mV(SCE). Experimentation showed that there is a critical depth value, above which little changes occur on the transition boundary between passive and active regions on the crevice wall, x pass, and below which x pass location shifts sharply towards the crevice bottom. Steeping of the potential gradient occurred with time indicating enhancement of crevice corrosion, which was seen by the gradual increase in the current. These findings were in close agreement with the IR voltage theory and related mathematical model predictions. Morphological examination showed an intergranular attack around the active/passive boundary ( x pass) on the crevice wall.