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Recently, there has been a huge spike in the number of automobiles in the urban areas of many countries, particularly in India. The number of vehicles are increasing rapidly and with the existing infrastructure, the traffic systems stand still during peak hours. Some of the main challenges for traffic management are the movement of overloaded vehicles beyond their restricted zone and time, reckless driving, and overlooking road safety rules. This paper proposes an Internet of Things (IoT)-based real-time Intelligent Traffic Signal System (ITSS), which consists of inductive loops and a programmable micro-controller to determine traffic density. Inter-communication in the centralized control unit sets the timer of the traffic light and synchronizes with the traffic density in real-time for smooth mobility of vehicles with less delay. Additionally, to prioritize emergency vehicles over other vehicles in the same lane, a pre-emption mechanism has been integrated through infrared sensors. The result of traffic density determines the timer of the light post in real-time, which in result enhances the smooth flow of vehicles with reduced delay for travelers. Using its automatic on-demand traffic signaling system, the presented solution has advantages over fixed systems. [ABSTRACT FROM AUTHOR]

A recent physics-based model for liquid and gaseous water transport in the cathode catalyst layer (CCL) is incorporated into our 1d ＋ 1d model for the PEM fuel cell impedance. The model includes parametric dependencies of the CCL oxygen diffusivity and proton conductivity on the liquid saturation. Fitting of the 1d ＋ 1d model to experimental impedance spectra of a PEM fuel cell reveals two intriguing effects. Contrary to common belief, the liquid water saturation in the CCL is nearly independent of cell current density due to the growing liquid pressure gradient that drives liquid water removal from the CCL. Further, the "dry" oxygen diffusivity of the catalyst layer increases with cell current density. Apparently, at small current density, electrochemical conversion proceeds primarily in narrow pores, where the Knudsen oxygen diffusivity is low. With growing current density, larger and better connected pores with higher oxygen diffusivity dominate in the current conversion, leading to increase in effective oxygen diffusivity observed in impedance spectroscopy data. • Two-phase water transport in the cathode catalyst layer (CCL) is incorporated into our model for PEMFC impedance. • The new model is fitted to experimental local impedance spectra. • Successful fitting of a low-frequency inductive loop due to liquid saturation transients in the CCL is demonstrated. • The fitting parameters show formation of a strong liquid pressure gradient in the CCL. • The effect of "dry" oxygen diffusivity growth with the cell current density is explained. [ABSTRACT FROM AUTHOR]

This report documents a practical work conducted at California PATH for developing a portable tool to be used at the control cabinet level to accurately diagnose any fault(s) of a loop detection system (including loop circuits, loop cards, cable links, etc.), to check the detection accuracy, to deal with sensitivity of detector card, and to correct the faulty data. To achieve these functionalities at the low level, it is necessary to utilize an independent source as a baseline data to compare against the loop detection system output. Such a comparison also permits an evaluation of the loop system. Since multiple-vehicle tracking technologies using digital video camera on freeways have been well-developed and tested at PATH, it is used as the baseline measurement in the portable tool for the loop fault diagnosis. This report presents the development of a prototype system including the hardware, the software, the data communication method, and the algorithms. Some preliminary consideration has also been conducted on lower (control cabinet) level data correction and communication system reliability of several Caltrans District for sensor data passing. Future work will be on systematic loop fault detection and lower level data correct.

In this work, a direct data-driven approach is employed to extract the distribution of relaxation times (DRT) from impedance data. The proposed procedure is based on the Loewner framework, that is a data driven methodology with theoretical basis in the linear system theory. One of the main advantages is that the DRT can be computed without need of regularization procedures or iterative optimization algorithms. We test the Loewner framework based algorithm on synthetic impedance data generated through equivalent circuit models widely used for modeling electrochemical systems. Impedance data set including noise are also processed. In addition, experimental electrochemical impedance spectroscopy (EIS) data are analyzed. The study shows a significant improvement in the accuracy and a high versatility of the methodology. However, the presence of significant amount of noise compromises the reliability of the obtained DRT due to the occurrence of artifact peaks. Some recommendations how to deal with noisy data are discussed. [Display omitted] • It is introduced an algorithm to determine the distribution of relaxation times. • Regularization or parameters adjustment is not necessary. • CPE, Gerischer behavior and inductive loops are analyzed with high accuracy. • Presence of noise in the data compromises the reliability of the obtained DRT. • Data pre-processing for noise cleaning is pointed out as solution. [ABSTRACT FROM AUTHOR]

A previously validated equivalent circuit model, in which two resonant circuits were inserted to represent the processes in the catalyst layers, is applied to fit the electrochemical impedance spectroscopy results of a single proton exchange membrane fuel cell exposed to accelerated stress test targeting catalyst degradation. The simulation results of the applied equivalent circuit model show very good agreement with the experimental data. The applied model is able to extract contributions of each of the model elements to the cell degradation. The obtained results indicate that the cathode catalyst layer resonant loop parameters, together with the cathode charge transfer resistance and cathode double-layer capacitance, change the most during the accelerated stress test. If each of the elements of the cathode resonant loop can be associated with physical processes inside the catalyst layer, the model may be used to give more insight into the degradation effects on functioning of the catalyst layer. From the conducted electrochemical impedance spectroscopy analysis, it seems that the low-frequency intercept in Nyquist plot shows the most significant change with degradation, so it may be used directly as a sufficient indicator of fuel cell performance degradation due to catalyst layer degradation. [ABSTRACT FROM AUTHOR]

The electrocatalytic performance of the impregnated La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF)-Y 2 O 3 stabilized ZrO 2 (YSZ) cathodes has been investigated by electrochemical impedance spectroscopy (EIS) using a “three-electrode” configuration for intermediate temperature solid oxide fuel cells. The significant inductive loop observed in the fourth quadrant was related to two factors, one is the amount of LSCF loading, the other is the testing temperatures. The inductive loop in the impedance spectra disappeared under dc bias or low oxygen partial pressure. Based on this, the inductive loop in the impedance spectra is closely related to the excess oxygen adsorbed on the surface of electrode can be concluded. [ABSTRACT FROM AUTHOR]

Representation of fuel cell processes by equivalent circuit models, involving resistance and capacitance elements representing activation losses on both anode and cathode in series with resistance representing ohmic losses, cannot capture and explain the inductive loop that may show up at low frequencies in Nyquist diagram representation of the electrochemical impedance spectra. In an attempt to explain the cause of the low-frequency inductive loop and correlate it with the processes within the fuel cell electrodes, a novel equivalent circuit model of a Proton Exchange Membrane (PEM) fuel cell has been proposed and experimentally verified here in detail. The model takes into account both the anode and the cathode, and has an additional resonant loop on each side, comprising of a resistance, capacitance and inductance in parallel representing the processes within the catalyst layer. Using these additional circuit elements, more accurate and better fits to experimental impedance data in the wide frequency range at different current densities, cell temperatures, humidity of gases, air flow stoichiometries and backpressures were obtained. [ABSTRACT FROM AUTHOR]

The results of electrochemical impedance spectroscopy of proton exchange membrane (PEM) fuel cells may exhibit inductive phenomena at low frequencies. The occurrence of inductive features at high frequencies is explained by the cables and wires of the test system. However, explanation of inductive loop at low frequencies requires a more detailed study. This review paper discusses several possible causes of such inductive behavior in PEM fuel cells, such as side reactions with intermediate species, carbon monoxide poisoning, and water transport, also as their equivalent circuit representations. It may be concluded that interpretation of impedance spectra at low frequencies is still ambiguous, and that better equivalent circuit models are needed with clearly defined physical meaning of each of the circuit elements. [ABSTRACT FROM AUTHOR]

This paper makes contributions toward adopting a systemic view of city-wide ubiquitous systems. Here, we present methods and techniques for combining multiple sensing modalities to measure and model traffic patterns in urban environments. We show how noise in one modality can be reduced by considering another more reliable modality and how two modalities can be combined. While much work in the literature deals with simulated data or small data sets, our work focuses on analyzing data from a permanent data collection infrastructure in a downtown area. We present results using a 3-week data set containing data of two modalities: inductive loop traffic detectors and Bluetooth scanners. [ABSTRACT FROM AUTHOR]

For comprehensive interpretation of the electrochemical processes occurring at silicon/electrolyte interfaces, the purpose of this work was to use electrochemical impedance measurements (EIS) to characterize silicon/electrolyte interfaces in the dark and to record the physical, electrical, and chemical processes during the different steps of silicon dissolution in hydrofluoric (HF) acid solution. In this study we used two main electrochemical techniques-potentiodynamic polarization and EIS under different bias potentials. The in-situ current-voltage I( V) characteristic clearly identifies the pore formation (porous silicon), transition, and electropolishing regions. Two series of impedance diagrams were recorded in the potential range in which the depletion layer was generated within the semiconductor substrate and in the range of potentials corresponding to the onset of an accumulation layer. Our results show that the impedance of silicon/electrolyte interfaces depends on the surface roughness and porosity of the substrate. At a particular positive value of the bias, an important induction loop was observed in addition to the usual capacitive behavior. It is highly significant that, for finite pore length, mass transfer and pore geometry might lead to different impedance curves. An electrical equivalent circuit model was used to fit the best experimental data to the theoretical data. [ABSTRACT FROM AUTHOR]

For the improvement of the effect of traffic multi-step forecasts using short-term data of loop in Sydney coordinated adaptive traffic system (SCATS) , on the basis of data preprocessing, traffic data and time points at time t over a sampling period of n intervals were included in the traffic state feature vector, Euclidean distance was used to measure the closeness between current traffic state and historical traffic state, the number of nearest neighbors corresponding to the minimum error of travel multi-step forecasts was selected, and the weights of k-nearest neighbors were identified by normalizing the reciprocal of the distance between traffic states, a new bi-level method of multi-step forecasting using k Nearest Neighbor (k-NN) algorithm was designed, including a multi-step forecasting method and a predictable steps on-line estimation method. The validity of the proposed method was tested with data measured from a megacity. The results indicate that the proposed method can further improve the effect of short-term traffic multi-step forecasts. [ABSTRACT FROM AUTHOR]

This paper presents a novel inductive loop sensor that can detect vehicles under a heterogeneous and less-lane-disciplined traffic and thus can be used to support a traffic control management system in optimizing the best use of existing roads. The loop sensor proposed in this paper detects large (e.g., bus) as well as small (e.g., bicycle) vehicles occupying any available space in the roadway, which is the main requirement for sensing heterogeneous and lane-less traffic. To accomplish the sensing of large as well as small vehicles, a multiple loop system with a new inductive loop sensor structure is proposed. The proposed sensor structure not only senses and segregates the vehicle type as bicycle, motor cycle, scooter, car, and bus but also enables accurate counting of the number of vehicles even in a mixed traffic flow condition. A prototype of the multiple loop sensing system has been developed and tested. Field tests indicate that the prototype successfully detected all types of vehicles and counted, correctly, the number of each type of vehicles. Thus, the suitability of the proposed sensor system for any type of traffic has been established. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a two-consecutive steps anodic dissolution mechanism is simulated at the atomic level by a Monte Carlo algorithm on a 3D lattice. In contrast with a previous work restricted to the 2D flat case, it is shown that the steady state and transient behaviors are controlled not only by the adsorbed intermediate coverage degree but also by the area of the rough interface build up by the dissolution of interfacial atoms. It is established that the complex impedance behavior results from a combination of the individual frequency responses of these two quantities. The emphasis is put on the specific properties of the impedance induced by the surface roughness relaxation for which a kinetic description is proposed and compared to the Monte Carlo data. It is clearly concluded that, by taking into consideration the surface re-arrangement, the number of frequency domains in the impedance may be larger than predicted by the derivation of a kinetic model on a flat interface. [Copyright &y& Elsevier]

Abstract: Much has been argued about the inductances in electrochemical impedance spectroscopy (EIS), which are recurrently ascribed to electrochemical or non-electrochemical events and even experimental artifacts. In the present paper, computational microscopic simulations of metallic dissolution based on the microscopic Monte Carlo algorithm allowed the effect of surface adsorbate relaxation to be isolated from other possible intervening features such as surface relaxation. Results have unambiguously shown that surface adsorbate relaxation can effectively yield inductive loops as predicted by the classical macroscopic description of the metal–electrolyte interface by kinetic equations. [Copyright &y& Elsevier]

Abstract: Electrochemical impedance spectroscopy was used to study the mechanism by which copper oxides are reduced in alkaline solutions. For the reductions of CuO and Cu2O, a capacitive loop and also an inductive loop under certain conditions were observed in the complex plane. The electrochemical impedance for CuO reduction was not greatly dependent on the solution alkalinity and the kind of alkali hydroxide. However, the electrochemical impedance for Cu2O reduction was considerably affected by the kind and concentration of alkali hydroxide. The diameter of the capacitive loop, i.e., the charge-transfer resistance (R ct), was increased with increase in solution alkalinity. It should also be noted that R ct was increased in the order of KOH6M) and LiOH (>0.2M) suggested the existence of an intermediate species (probably CuOH). The specific inhibitory effect of Li+ ions on the reduction of Cu2O might be explained by a possible stabilization of CuOH by Li+ ions. [Copyright &y& Elsevier]

Abstract: In this paper, a study on the electrochemical impedance of anodic decomposition of n-GaAs in 0.5 M sulfuric acid, combined with steady-state polarization techniques, is presented. Both dark and daylight conditions have been investigated for comparison of their influence on polarization curves and impedance by hole injection in a potential range from open circuit to breakdown. An inductive loop appears if a high enough positive potential is applied for both conditions, while recombination resistance is only observed for the daylight case. Quantitative simulation of the impedance spectra suggests that the rate-determining step for corrosion/photocorrosion is the generation of mobile intermediates, e.g., AsGa+, which are then replaced by competition between a Faradaic process involving immobile intermediate formation and a parallel chemical step to form AsGa–OH. [Copyright &y& Elsevier]

Abstract: Corrosion of GaAs can readily happen in acidic and alkaline aqueous electrolytes. The instability of GaAs is a major difficulty in implementing GaAs-based photoelectrochemical solar energy-conversion systems. In this paper, the corrosion behavior was investigated by electrochemical methods and surface-analysis approaches, in both H2SO4 and NH3·H2O solutions. Open-circuit testing showed that the GaAs surface was very sensitive to water/air although the process to build a stable interface between GaAs and electrolyte is slow. Comparison of the impedance data for n- and p-GaAs showed that an inductive loop only appeared at a high corrosion rate. This induction loop was due to the Faradaic adsorption process being the rate-determining step. This can only be explained by a mechanism in which a reaction intermediate, instead of holes, after capture of the first hole is the oxidant for further decomposition steps in combination with a chemical reaction with water. The results suggest that the same corrosion/decomposition mechanism occurred on both n- and p-GaAs and also in the two solutions. When the surface hole concentration was low, the hole injection or generation process was the rate-determining step. At large reverse bias on n-GaAs, with high hole concentration or forward biasing of p-GaAs, the corrosion rate was limited by a Faradaic adsorption process, involving an adsorbed intermediate. The different surface compositions after corrosion in the two solutions can be explained by the dissolution of As(0). It is pointed out that the further oxidation of As(0) to As(III) in NH3·H2O solution is still slow, as suggested from X-ray photoelectron spectroscopy (XPS) analysis. [Copyright &y& Elsevier]

• Analysis of inductive loops in EIS measurements of an open-cathode PEFC stack. • Impedance model to predict inductive loops in PEFC-EIS measurements. • Inductive loops associated to water vapour diffusion in cathode catalyst layer. • Relation between trend of inductive loops and phase angle in EIS measurements. In this study, an impedance model of a polymer electrolyte fuel cell (PEFC) is considered to simulate inductive loops at low frequencies from electrochemical impedance spectroscopy (EIS) measurements carried out in an open-cathode PEFC stack. The new impedance model proposed in this study is derived from the hypothesis that water vapour transport in the cathode catalyst layer (CCL) yields the formation of inductive loops at low frequencies. The impedance model of the PEFC considers the impedance model of the CCL reported in a previous study and considers an analytical expression for the impedance of water vapour diffusion in the CCL. The developed PEFC impedance model is validated with EIS measurements featuring inductive loops at low frequencies and carried out in the individual cells comprising an open-cathode PEFC stack at two current densities. The parameters related to the impedance of water vapour diffusion simulate the inductive loops at low frequencies and simulate a change of the size of the impedance spectrum of the PEFC. Therefore, the formation of inductive loops at low frequencies can be attributed to not only water vapour transport, but also ionomer swelling/shrinking (hydration/dehydration) in the CCL. The impedance model can provide an insight into the relation between the trend of the inductive loops at low frequency and the change in the phase angle in the EIS measurements which can indicate the hydrated state in the membrane-electrode assembly of the individual cells of the open-cathode PEFC stack. [ABSTRACT FROM AUTHOR]

• TMAZ-HAZ region showed elongated and refined grains due to the plastic deformation process. • 2D microhardness mapping exhibited higher values in the SZ region. • Passive film was completely reconstructed in the SZ at 6.0 and 11.5 mol L–1 HNO 3. • Fe and Cr contamination was deleterious to the TiO 2 film stability. • XPS measurements showed the presence of not native metal species in the passive film. Mechanical and microstructural characteristics of Ti-6Al-4V/stainless steel (SS) dissimilar friction stir welds have been well described in the literature; however, little is known about the electrochemical properties of such welds in terms of the passive film stability of TiO 2 grown in oxidizing media. To clarify this issue, potentiodynamic polarization, cyclic voltammetry, and electrochemical impedance measurements were carried out in the Ti-6Al-4V alloy to analyze the effects of Fe and Cr contamination from the underlying SS on the passive film stability of TiO 2 in concentrated (6.0 and 11.5 mol L–1) HNO 3 solutions. Lower transpassive potentials were observed for samples in the stirred zone (SZ) than those of the base metal (BM) due to Fe and Cr contamination. Anodic charges obtained during cyclic voltammetry using 6.0 mol L–1 HNO 3 showed that the grown passive film was completely dissolved and regrown after consecutive scans, except for the BM sample. According to the results of X-ray photoelectron spectroscopy (XPS) analyses an Al depleted layer was obtained for the latter condition, which confirms the stability of TiO 2 film. The increasing values of charge transfer resistance obtained through electrochemical impedance measurements at distinct potentials in the passive region also supported the stability of the TiO 2 film grown in 6.0 mol L–1 HNO 3 solution. The formation of a medium frequency inductive loop and low frequency constant phase element are related to the dissolution of the oxide film and adsorption of NO 3 species into the formed passive film, respectively, as evidenced by XPS analyses. [ABSTRACT FROM AUTHOR]

The low-frequency impedance hook in perovskite solar cells (PSC) is a feature that has been frequently associated with the behavior of passive circuits of inductors or negative capacitances. However, if the experimental impedance data do not transform according to the Kramers-Kronig (KK) relations, the system does not fulfill the conditions of linearity, stability, causality and finiteness necessary for validating the impedance measurements and fitting it using passive circuit elements. In this study, we found that the impedance hook in a standard PSC configuration is not compliant with the KK transforms, and as such the system is active and unstable. We propose a model for this low-frequency behavior based on the active gyrator element which consists of two cross-coupled voltage-controlled current sources and has the capability of turning a capacitance into its dual inductive impedance. Image 1 • Passive elements are shown to be invalid for the low-frequency inductive hook in perovskite solar cells. • We propose an active model for this inductive behavior based on the active gyrator and its impedance converting function. • The voltage-controlled current sources of the gyrator are analogous to the voltage-dependent charge injection/extraction processes. [ABSTRACT FROM AUTHOR]