DC Response Research Articles

Dc and ac electrical response of MOCVD grown GaN in p-i-n structure, assessed through I–V and admittance measurement

The electrical response of gallium nitride (GaN), produced through metal–organic chemical vapor deposition in a p-i-n structure was investigated through temperature-dependent current–voltage (I–V) and admittance measurement. The I–V curves showed double diode behavior together with several distinct regions in which trap-assisted tunnelling current has been identified at low and moderate forward/reverse direction and space charge limited current (SCLC) at large forward/reverse bias. The value of extracted energy (∼200 meV in forward and ∼70 meV in reverse direction) marked the tunnelling entity as electron and heavy hole in the present structure. These values were also obtained in space charge limited regime and considered as minority carriers which might originate the experimentally observed negative capacitance issue at low frequencies over the junction under both forward and reverse bias directions. Analytically derived expression for the admittance in the revised versions of SCLC model was also applied to explain the inductance effect, yielding good fits to the experimentally measured admittance data.

Exploring a Novel Methodology for DC Analysis in Memristive Circuits with Multiple Operating Points

The memristor and the memristive systems have represented a challenge to be incorporated into a simulation procedure in order to carry out novel applications. The discovery of the physical memristor by the HP Labs has caused widespread interest for modeling the memristive behavior in order to combine this new fundamental circuit element with traditional devices. DC domain analysis represents a fundamental stage in the circuit simulators because the DC operating points are used as starting points in other analysis domains. In this work, the DC response of mathematical memristive systems is explored in order to recognize different scenarios according to the nature of the memristive variable. The piecewise linear formulation has been used in order to establish the memristive phenomenon in the device. As a result of this exploration, a novel DC modeling methodology for memristive systems is introduced. This methodology is capable of generating current–voltage branch relationships that represent the memristive behavior of the device. The memristive model proposed is characterized in order to determinate the impact of the variables on the memristive behavior. Moreover, the existence of multiple DC operation points (MOPs) is treated and the conditions for the occurrence of MOPs are established by two cases of study. Finally, the new contributions of this work compared to previous work are presented and discussed.

Automatic computation and solution of generalized harmonic balance equations

Abstract Generalized methods are presented for generating and solving the harmonic balance equations for a broad class of nonlinear differential or difference equations and for a general set of harmonics chosen by the user. In particular, a new algorithm for automatically generating the Jacobian of the balance equations enables efficient solution of these equations using continuation methods. Efficient numeric validation techniques are also presented, and the combined algorithm is applied to the analysis of dc, fundamental, second and third harmonic response of a nonlinear automotive damper.

Immunomodulatory effect of cryopreserved platelets: altered BDCA3+ dendritic cell maturation and activation in vitro.

Cryopreservation of platelets (PLTs) is useful in remote areas to overcome logistic problems associated with supply and can extend the shelf life to 2 years. During cryopreservation, properties of PLTs are modified. Whether changes in the cryopreserved PLT (CPP) product are associated with modulation of recipients' immune function is unknown. We aimed to characterize the immune profile of myeloid dendritic cells (mDCs) and the specialized blood DC antigen (BDCA)3+ subset after exposure to CPPs. Using an in vitro whole blood model of transfusion, the effect of CPPs on mDC and BDCA3+ DC surface antigen expression and inflammatory mediator production was examined using flow cytometry. In parallel, polyinosinic:polycytidylic acid (poly(I:C)) or lipopolysaccharide (LPS) was utilized to model processes activated in viral or bacterial infection, respectively. Cryopreserved PLTs had minimal impact on mDC responses but significantly modulated BDCA3+ DC responses in vitro. Exposure to CPPs alone up regulated BDCA3+ DC CD86 expression and suppressed interleukin (IL)-8, tumor necrosis factor (TNF)-α, and interferon-γ inducible protein (IP)-10 production. In both models of infection-related processes, exposure to CPPs down regulated BDCA3+ DC expression of CD40, CD80, and CD83 and suppressed BDCA3+ DC production of IL-8, IL-12, and TNF-α. CPPs suppressed CD86 expression in the presence of LPS and IP-10 and IL-6 production with poly(I:C). Cryopreserved PLTs may be immunosuppressive, and this effect is more evident when processes associated with infection are concurrently activated, especially for BDCA3+ DCs. This suggests that transfusion of CPPs in patients with infection may result in impaired BDCA3+ DC responses.

Improved dynamic response of isolated full bridge DC to DC converter using BATA optimization tuned fuzzy sliding mode controller for solar applications

This paper deals with the achievement of dynamic response of high gain DC to DC converter in solar application using BAT Algorithm (BATA) optimization tuned Fuzzy Sliding Mode Controller. The dynamic and transient response of isolated full bridge DC to DC converter are improved by using BATA optimization tuned Fuzzy Sliding Mode Controller under starting and load step change conditions. The aim of the control is to regulate the output voltage beneath the load change. The model of the BATA tuned Fuzzy Sliding Mode Controller is implemented using sim power systems toolbox of MATLAB SIMULINK. Fuzzy Sliding Mode Controller is tuned by using BATA. Results are compared. Performance of the proposed dynamic novel control under step load change condition is investigated. Performance of proposed control is assessed through prototype hardware design.

Galvanostatic EFM: A New Approach for Testing and Monitoring Fuel Cells

Electrochemical Frequency Modulation (EFM) is a well-known technique which is mostly used for corrosion studies. It is generally performed in potentiostatic mode and allows calculating the corrosion current as well as Tafel parameters by rearranging the Butler-Volmer equation. It was recently also used for testing fuel cells. However, for electrochemical power systems, galvanostatic control is much more beneficial. Even small potential changes can lead to high currents if a system has a very low internal resistance which can lead to irreversible damages at the cell and safety risks. Nonetheless, no practical and theoretical approach has been published so far for EFM measurement in galvanostatic mode. This study presents first galvanostatic EFM measurements with fuel cells. The results are compared to other techniques which are typically used for analyzing fuel cells such as polarization experiments, electrochemical impedance spectroscopy (EIS), and current interrupt (CI). Measurements within this study are performed with a small Proton Exchange Membrane (PEM) fuel cell. During galvanostatic EFM experiments, a DC current signal is applied which is superimposed by a perturbation signal consisting of two sine waves with different frequencies (f 1, f 2). The measured voltage answer is more complex due to the non-linear behavior of fuel cells. The voltage signal can be subdivided into its DC response (zero frequency), harmonics (integral multiples of both base frequencies; f = n×f 1/2 where n is an integer > 0), as well as interharmonics (sum and difference of multiple harmonics; f = n×f 1 ± m×f 2 where n, m are integers > 0). In order to determine these terms, a fast Fourier transform (FFT) algorithm is employed on the measured signal. The voltage response can be plotted versus frequency in a so-called intermodulation spectrum. Harmonic and interharmonic amplitudes can be then used to calculate various parameters. As basis for all calculations serves the general equation for the cell voltage V cellof a fuel cell: V cell = E th - η act - η ohm - η conc The equation includes three major polarization terms that are responsible for voltage loss. These terms are the activation overpotential η act, the ohmic overpotential η ohm, and the concentration overpotential η conc. E th is the theoretical thermodynamic potential. The equation can be rearranged by expanding and substituting various terms. Similar to potentiostatic EFM, two causality factors can be extracted which can be used to proof validity of the measured results. Applicability of this method and its calculations are tested under various conditions such as different loads and oxygen concentrations. Finally, the results are compared with other techniques.

Abstract 3663: An anti-CD4 depleting antibody reverses regulatory T-cell-induced suppression of dendritic cells while preventing nonspecific CD4+ T cell responses in tumor-bearing mice

Abstract Administration of an anti-CD4 depleting antibody induces tumor-specific CD8+ T cell responses in tumor-bearing mice, although the mechanisms underlying this phenomenon remain unclear. CD4+ Foxp3+ regulatory T cells (Treg) impair antigen presentation by DCs through CTLA4-mediated down-regulation of CD80/CD86. In the present study, we investigated the effects of an anti-CD4 depleting monoclonal antibody (mAb) on DC responses in the B16F10 and LLC subcutaneous tumor models, and compared these effects with those of Treg targeting therapy. Administration of anti-CD4 mAb up-regulated CD80/CD86 in tumor-infiltrating DCs, and in migrating-type but not resident-type DC subsets in the tumor-draining lymph node. The upregulation of CD80/CD86 on these DC populations was correlated with increased proliferation of tumor-specific CD8+ T cells in the tumor-draining lymph node. Anti-CD4 mAb-induced CD80/CD86 up-regulation and tumor-specific CD8+ T cell responses were remarkably higher than that induced by an anti-CD25 depleting mAb or an anti-CTLA4 blocking mAb, and were equivalent to that induced by diphtheria-toxin-induced selective depletion of Tregs in Foxp3-DTR mice. Importantly, the activation of CD4+ conventional T cells and B cells in the peripheral lymph nodes that was observed following Treg depletion was not observed following anti-CD4 mAb administration. In conclusion, anti-CD4 depleting antibody therapy is an effective way to evoke anti-tumor CD8+ T cell responses by reversing regulatory T cell-induced suppression of dendritic cells, and to reduce the risk of severe autoimmunity in cancer patients. Citation Format: Satoshi Ueha, Haru Ogiwara, Shoji Yokochi, Yoshiro Ishiwata, Francis Shand, Shohei Hori, Kazuhiro Kakimi, Satoru Ito, Kouji Matsushima. An anti-CD4 depleting antibody reverses regulatory T-cell-induced suppression of dendritic cells while preventing nonspecific CD4+ T cell responses in tumor-bearing mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3663. doi:10.1158/1538-7445.AM2017-3663

Abstract 4021: Donor-specific primary monocyte-derived dendritic cell maturation model for high-throughput screening of immunostimulatory adjuvants

Abstract Dendritic cell (DC) based immunotherapy is a promising treatment alternative for various solid tumor and hematological malignancies. DCs are capable of initiating and propagating antigen-specific adaptive immune responses through their intrinsic maturation process. Identifying novel, effective adjuvant drug candidates that can stimulate DC maturation while understanding and accounting for the variability of patient-specific DC cell responses to the immunostimulatory adjuvants is essential for development of such immunotherapies. Reliable, high throughput assay platforms that characterize patient-specific modulatory effects during the DC maturation process in vivo and in vitro are also highly desirable. In this study, we present a high throughput in vitro primary cell assay to evaluate dose-dependent DC maturation in a panel of human leukocyte antigen (HLA) typed individual donors. CD14+ monocytes from four healthy donors were isolated from leukapheresis derived peripheral blood mononuclear cells (PBMC) and cultured for seven days with GM-CSF and IL-4 to achieve differentiation to DC. Cells were then stimulated for 24 hours with lipopolysaccharide (LPS), CpG oligonucleotides, or nine different novel toll-like receptor 4 (TLR4) ligands at three concentrations. To quantify the differentiation of monocytes into DC and subsequent maturation, flow cytometry was used to measure the expression of biomarkers, MHC-II, CD40, CD80, CD83, and CD86. Greater than 99% MHC-II expression was observed across all donors and confirmed successful differentiation to DC. The TLR4 ligands showed reduced biomarker expression, as compared to pathogenic E. coli LPS but similar to PHAD, a synthetic TLR4 agonist currently used in adjuvants. While monocytes from all donors responded to the ligands tested, the intensity of activation marker expression varied among donors with LPS/TLR4 ligand induced maturation process showing 43-91% CD40 and 27-82% CD83 expression, highlighting the necessity of multi-donor screening for drug development. In conclusion, a high throughput in vitro primary monocyte derived DC differentiation assay has been developed and is commercially available to assist researchers in characterizing donor-specific DC responses to immunostimulatory adjuvants. Citation Format: Qin Chen, Anthony Lawrenz, Alan Wang, Erin Kelly, Erin Harberts, Robert K. Ernst, Jay Tong. Donor-specific primary monocyte-derived dendritic cell maturation model for high-throughput screening of immunostimulatory adjuvants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4021. doi:10.1158/1538-7445.AM2017-4021

Dynamic conductance in double-bend silicene nanosystem

In this work, dynamic conductance transport properties are theoretically investigated in the zigzag silicene nanosystem with a double-bend structure. We numerically study the dc conductance and ac emittance in the nanosystem based on the tight-binding approach, Green's function method and ac transport theory, by considering the second-nearest-neighbor spin–orbit interaction (SOI) and external electric field. The numerical results suggest that the nanosystem undergoes a quantum phase transition driven by the relatively strong SOI, which results in a large dc conductance and a vanishing ac emittance around the Dirac point despite the interface scattering. The distribution of the local density of states in the real space reveals that the SOI induces the quantum edge state by establishing transport paths at the edge of the nanosystem. Further investigation indicates that the dynamic conductance related to the quantum edge state are topologically protected from the geometrical size change of the nanosystem. Finally, the nanosystem can be tuned to be a trivial band insulator without any dc or ac response by applying external electric field.

Tunable pseudogaps due to nonlocal coherent transport in voltage-biased three-terminal Josephson junctions

We investigate the proximity effect in junctions between $N=3$ superconductors under commensurate voltage bias. The bias is chosen to highlight the role of transport processes that exchange multiple Cooper pairs coherently between more than two superconductors. Such non-local processes can be studied in the dc response, where local transport processes do not contribute. We focus on the proximity-induced normal density of states that we investigate in a wide parameter space. We reveal the presence of deep and highly tunable pseudogaps and other rich structures. These are due to a static proximity effect that is absent for $N=2$ and is sensitive to an emergent superconducting phase associated to non-local coherent transport. In comparison with results for $N=2$, we find similarities in the signature peaks of multiple Andreev reflections. We discuss the effect of electron-hole decoherence and of various types of junction asymmetries. Our predictions can be investigated experimentally using tunneling spectroscopy.

Platelet concentrates modulate myeloid dendritic cell immune responses

Platelet transfusion has been reported to modulate the recipients’ immune system. To date, the precise mechanism(s) driving poor patient outcomes (e.g., increased rate of mortality, morbidity, infectious complications and prolonged hospital stays) following platelet transfusion are largely undefined. To determine the potential for platelet concentrates (PC) to modulate responses of crucial immune regulatory cells, a human in vitro whole blood model of transfusion was established. Maturation and activation of human myeloid dendritic cells (mDC) and the specialized subset blood DC antigen (BDCA)3+ DC were assessed following exposure to buffy-coat derived PC at day (D)2 (fresh) and D5 (date-of-expiry). In parallel, to model recipients with underlying viral or bacterial infection, polyinosinic:polycytidylic acid or lipopolysaccharide was added. Exposure to PC had less of an impact on mDC responses than BDCA3+ DC responses. PC alone downregulated BDCA3+ DC expression of co-stimulatory molecules CD40 and CD80. In the model of viral infection, PC downregulated expression of CD83, and in the bacterial model of infection, PC downregulated CD80, CD83, and CD86. PC alone suppressed mDC production of interleukin (IL)-8, IL-12 and tumor necrosis factor (TNF)-α and BDCA3+ DC production of IL-8, IL-12, and IL-6. In the model of viral infection, production of IL-12 and interferon-gamma inducible protein (IP)-10 was reduced in both DC subsets, and IL-8 was reduced in BDCA3+ DC following PC exposure. When modeling bacterial infection, PC suppressed mDC and BDCA3+ DC production of IL-6 and IL-10 with a reduction in TNF-α evident in mDC. This study assessed the impact of PC “transfusion” on DC surface antigen expression and inflammatory mediator production and provided the first evidence that PC transfusion modulates blood mDC and BDCA3+ DC maturation and activation, particularly in the models of infection. Results of this study suggest that patients who receive PC, particularly those with underlying infectious complications, may fail to establish an appropriate immune response precipitating poor patient outcomes.

Ab-Initio approach to Model Impedance and Charge-Discharge Characteristics of Electrical Double Layer Capacitors

Electrical double layer capacitors (EDLCs) are energy storage devices which primarily utilize ionic adsorption and high surface area electrodes to store electrostatic charge at electrode/electrolyte interface. In order to describe and correlate electrode architecture to the energy and power performance of capacitors, first principle models that can explain both the ac and dc response of the capacitor need to be developed. In this work, we describe an ab initio mathematical model that take into account both the double layer and interfacial resistance contributions at the electrode/electrolyte interface. The model was tested, and validated using experimental data of various carbon-based EDLCs using both electrochemical impedance spectroscopy (EIS) and galvanostatic discharge data. Physical parameters of the model were obtained through non-linear regression of frequency-domain EIS data, which was then transformed into time domain using numerical inverse Laplace transform to predict the potential-time discharge response of the capacitor. The experimental data was in excellent agreement with the model predictions. Figure 1

Zero-Free-Parameter, Mathematically Simple and Accurate Modeling of Battery Response to Discharge Profiles

Battery models are necessary since the response of batteries need to be predicted for a large number of applications. In automotive, consumer electronics and other fields, the AC response needs to be modeled in addition to the DC response of the battery for a full understanding of the voltages that will be encountered throughout the current profile that discharges(and potentially charges) the battery. Current battery models used for this prediction are either based on very tedious algebraic models that are hard to follow and implement [1], or they are based on oversimplified models that fail to predict the accurate detail of the response [2]. These models can predict the response of the battery either through complicated math that requires the knowledge of a large number of parameters a priori, or through a number of assumptions regarding those parameters. Both ways of modeling require kinetic and thermodynamic parameters that describe the various interfaces within the battery. One way of obtaining these parameters is through impedance spectroscopy. Typically, impedance spectra are fit to an equivalent circuit model in order to obtain these parameters. In some cases, these parameters are then further used to calculate the thermodynamic and kinetic parameters, in others, simple models are used as the circuit components that make up the battery in order to employ a circuit model to solve for the response of the battery. The models that are complicated enough to accurately represent the impedance data are detailed and involve transmission line models that are somewhere between hard to impossible to properly represent in time domain. This is why most of the models use much more simplified models which can simply be integrated to get to time domain responses, however, these models fail to accurately represent the detailed structure of the impedance spectrum. We are going to represent a brand new modeling paradigm where impedance data is not fit to any models, simple or complicated. Instead, the response of the battery to the desired time domain charge/discharge profile is calculated in the frequency domain. The discharge profile is transformed into the frequency domain, then, the frequency domain current signal is multiplied by the impedance data measured at every frequency of relevance in order to get the voltage as a function of frequency. This frequency domain voltage response is then brought to the time domain with an inverse Fourier transform. The DC response of the battery is simply added in after the inverse Fourier transform through the use of a state-of-charge vs. DC potential curve that is measured for the battery of interest. There are a number of advantages in this approach compared to the literature models. First, there are no free parameters in this model. The response calculated does not make any assumptions, just uses the impedance data as measured. The kinetic and the thermodynamic properties of the battery are not obtained individually, instead, their implications are used through the measured impedance at different frequencies. Furthermore, the math used in this approach is simple, straightforward and computationally cheap. We will demonstrate that through the use of this approach, the response of batteries to a variety of current profiles can be calculated. The only requirement is the measured impedance values at every frequency that is relevant to the measured profile. In the figure attached, we are showing the reponse of an LFP cell to two profiles that are relevant in automotive applications. [1]Fan G; Pan K; Canova M; Marcicki J; Yang XG; JECS 163(5)A666-A676 (2016) [2]Castano S; Gauchia L; Voncila E; Sanz J; Ener. Conv. And Man., 92,396-405(2015) Figure 1

Holographic thermal DC response in the hydrodynamic limit

We consider black hole solutions of Einstein gravity that describe deformations of CFTs at finite temperature in which spatial translations have been broken explicitly. We focus on deformations that are periodic in the non-compact spatial directions, which effectively corresponds to considering the CFT on a spatial torus with a non-trivial metric. We apply a DC thermal gradient and show that in a hydrodynamic limit the linearised, local thermal currents can be determined by solving linearised, forced Navier–Stokes equations for an incompressible fluid on the torus. We also show how sub-leading corrections to the thermal current can be calculated as well as showing how the full stress tensor response that is generated by the DC source can be obtained. We also compare our results with the fluid-gravity approach.

Zero-Free-Parameter Modeling Approach to Predict the Voltage of Batteries of Different Chemistries and Supercapacitors under Arbitrary Load

Performance modeling of electrochemical energy storage systems is gathering increasingly higher attention in recent years. With the ever increasing power demand of mobile applications, predicting voltage behavior under different load profiles is of utmost importance for communications, automotive and consumer electronics. The ideal modelling approach needs not only to accurately predict the response of the battery, but also be robust, easy to implement and have low computational complexity. We will present a new algorithm that is algebraically straightforward, that has no adjustable parameters and that can accurately predict the voltage response of batteries and supercapacitors. The approach works well in a variety of discharge profiles ranging from simple long DC discharge/charge profiles to pulse schemes based on drive schedules published by regulatory bodies. Our approach is based on Electrochemical Impedance Spectroscopy measurements done on the system to be predicted. The spectrum is used in the frequency domain without any further processing to predict the fast moving portion of the voltage in the frequency domain. DC response is added in through a straightforward lookup table. This widely applicable approach can predict the voltage of with less than 1% error, without any adjustable parameters to a large variety of discharge profiles.

Modeling of nonlinear interactions between guided waves and fatigue cracks using local interaction simulation approach

This article presents a parallel algorithm to model the nonlinear dynamic interactions between ultrasonic guided waves and fatigue cracks. The Local Interaction Simulation Approach (LISA) is further developed to capture the contact-impact clapping phenomena during the wave crack interactions based on the penalty method. Initial opening and closure distributions are considered to approximate the 3-D rough crack microscopic features. A Coulomb friction model is integrated to capture the stick-slip contact motions between the crack surfaces. The LISA procedure is parallelized via the Compute Unified Device Architecture (CUDA), which enables parallel computing on powerful graphic cards. The explicit contact formulation, the parallel algorithm, as well as the GPU-based implementation facilitate LISA’s high computational efficiency over the conventional finite element method (FEM). This article starts with the theoretical formulation and numerical implementation of the proposed algorithm, followed by the solution behavior study and numerical verification against a commercial finite element code. Numerical case studies are conducted on Lamb wave interactions with fatigue cracks. Several nonlinear ultrasonic phenomena are addressed. The classical nonlinear higher harmonic and DC response are successfully captured. The nonlinear mode conversion at a through-thickness and a half-thickness fatigue crack is investigated. Threshold behaviors, induced by initial openings and closures of rough crack surfaces, are depicted by the proposed contact LISA model.

On the Circuit-Level Reliability Degradation Due to AC NBTI Stress

In this paper, an experimental analysis of the impact of dynamic negative bias temperature instability (NBTI) stress on the CMOS inverter dc response and temporal performance is presented. We analyzed the circuit behavior subjected to ac NBTI in the prospect to correlate the induced degradation with that seen at PMOS device level. The results revealed that, while ac NBTI-induced shift of the inverter features shows both voltage and temperature dependence, it does not always exhibit stress time dependence. Indeed, the time exponent $n$ is found to depend on both voltage and temperature. The analysis of such behavior when correlated with the PMOS threshold shift points toward the coexistence of more than one physical mechanism behind the degradation, where one mechanism could dominate the other under certain stress conditions. Depending on these conditions, circuit lifetime could be more or less affected.

Integrated Silicon Directly Modulated Light Source Using p-Well in Standard CMOS Technology

This paper studies integrated silicon light emitter implemented in standard CMOS technologies. A new MOS-like structure utilizing deep p-well is presented, and compared with conventional planar p-n junction diode at visible wavelength and avalanching bias conditions. Prototype light emitter is fabricated in a 3- $\mu \text{m}$ standard CMOS technology, and its dc, phase shift, and direct modulation frequency response with nanowatt power level are characterized, with experimental results for a reverse-bias region showing light modulation with the simulated maximum modulation frequency around $\sim 45$ GHz being reported.

A new control method based on type-2 fuzzy neural PI controller to improve dynamic performance of a half-bridge DC–DC converter

Due to nonlinear behavior and the uncertainty with converter structure, controller design is difficult and accompanied with complexities. In this paper, a new control method based on Type-2 fuzzy neural PI (T2FN PI) controller is applied to improve the dynamic response of half-bridge DC–DC converters for different operation conditions. The T2FNN PI controller amends the specifications of the converter system by controlling its duty cycle of switching. In addition, proposed controller can property handle the uncertainty which is associated to converter structure, measuring devices and measured control signals.The T2FN PI controller is a combination of type-2 fuzzy linguistic process and neural network learning capability. The back-propagation algorithm is applied to train the parameters of T2FNN PI controller. Furthermore, PSO algorithm is applied to obtain the T2FN PI training pattern.In order to evaluate the performance of the proposed T2FN PI controller, it has been compared with a Fuzzy controller and the conventional PI controller for five different operating conditions. The simulation results show efficiency of the T2FNN PI controller in compare to Fuzzy controller and PI controller in terms of better rejection of disturbances, faster transient response and less peak overshoot.

An AC modulated near infrared gain calibration system for a "Violin-Mode" transimpedance amplifier, intended for advanced LIGO suspensions.

The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a "tall-thin" rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse "Violin-Mode" vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor's DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor's more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative role of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz-300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m(-1) was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC/DC transimpedance gain ratio of 922.5 for this sensor, at 500 Hz, translated into a maximum Violin-Mode (AC) responsivity of (1.16 ± 0.05) MV m(-1), at that frequency.