steady state analysis

Photovoltaic cells are intrinsic part of any photovoltaic system. As the need for more efficient clean source of renewable energy becomes paramount, it is required to know how the cells perform electrically with the change in solar insolation caused by the change in position of sun and the latitude of the place of solar incidence. A model of photovoltaic cell is evaluated using Matlab considering variable solar insolation level.

This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright. SPE-227845-MS the approach simplifies facility requirements, minimizes environmental and safety risks associated with handling high-H 2 S flows, and translates to lower equipment and maintenance expenditures related to the subsurface. The field data supports the conclusion that subsurface dilution enables safe well operations, by reducing the rupture exposure radius (RER). This deleted section is not necessary. This technology will help to unlock the sour gas potential at reduced costs. The rigless and remotely operated system allows wells to be quickly restarted, enhancing production continuity, reducing non-productive time (NPT), and extending well lifespan. The flexibility of the system also permits dynamic responses to fluctuating H 2 S levels without costly interventions, securing long-term cost savings and increased profitability. The rigless downhole gas sweetening using insert string e.g. inverse gas lift system presents a breakthrough in high-H 2 S well management by using precision downhole gas dilution to optimize production and reduce processing costs. Its rigless, versatile design promotes sustainable H 2 S management, enhances well productivity, and extends operational efficiency without requiring rig-based intervention. This adaptable, proactive approach to H 2 S management supports industry sustainability goals by offering a low-impact, optimized solution for managing high-H 2 S reservoirs.

The phenomenon of switch-like response to graded input signal is the theme involved in various signaling pathways in living systems. Positive feedback loops or double negative feedback loops embedded with nonlinearity exhibit these switch-like bistable responses. Such feedback regulations exist in insulin signaling pathway as well. In the current manuscript, a steady state analysis of the metabolic insulin-signaling pathway is presented. The threshold concentration of insulin required for glucose transporter GLUT4 translocation was studied with variation in system parameters and component concentrations. The dose response curves of GLUT4 translocation at various concentration of insulin obtained by steady state analysis were quantified in-terms of half saturation constant. We show that, insulin-stimulated GLUT4 translocation can operate as a bistable switch, which ensures that GLUT4 settles between two discrete, but mutually exclusive stable steady states. The threshold concentratio...

The primary goal of this work was to study advantages of numerical methods used for the creation of continuous time Markov chain models (CTMC) of voltage gating of gap junction (GJ) channels composed of connexin protein. This task was accomplished by describing gating of GJs using the formalism of the stochastic automata networks (SANs), which allowed for very efficient building and storing of infinitesimal generator of the CTMC that allowed to produce matrices of the models containing a distinct block structure. All of that allowed us to develop efficient numerical methods for a steady-state solution of CTMC models. This allowed us to accelerate CPU time, which is necessary to solve CTMC models, ∼20 times.

Resonant converters (RCs) are gaining attention from the research community due to their significant contributions to the architecture of electric vehicle (EV) charging infrastructure. The primary part of RC is responsible for enabling constant-current (CC) charging, which helps lower inrush current, decrease losses, and improve efficiency. While the load current stays constant during charging using the CC approach, the source current grows linearly with charging time. However, pulling a high source current increases the rating of the inverter switches, which stresses them, raises their temperature, increases heat sink demand, and causes conduction loss-all of which are undesirable. Consequently, the rated CC is provided by the P2 topology of RC, which has a lower peak current source than other topologies and will improve charger performance. However, this assertion must be verified by mathematical modeling, design with theoretical calculations, specifications, and MATLAB simulation before execution. By providing a constant load current of 5 A at a DC source voltage of 200 V, the P2 RC and the conventional LCL RC are designed to compare source current values.

This paper introduces a novel boosting multilevel inverter that utilizes switched capacitors. Current multilevel inverters (MLIs) face several issues, such as complex structures, intricate switching controls, and challenges in generating gate pulses, numerous components, and high voltage stress on semiconductors. The increase in the number of levels adds to the complexity and cost of the circuit and can reduce reliability in some cases. The proposed topology creates a 7-level voltage waveform using 9 switches, 1 diode, and 2 capacitors, and it triples the voltage gain. The capacitors maintain selfbalanced operation without the need for additional circuits. A simple logic gate-based pulse-width modulation (PWM) technique is presented to ensure power balancing of the capacitors. The proposed 7-level switched capacitor boosting multilevel inverter features a reduced switch count, lower voltage stress, and built-in fault tolerance. The paper includes a comprehensive comparison of various related topologies. The proposed topology is simulated in PSIM, with simulation results presented for different parameters.

This paper addresses the lack of robustness in three phase Induction Motors (I.M) speed control in presence of uncertainty and external unknown disturbance of Model Reference Adaptive Control (MRAC), and present an enhancement of robustness by employing the adaptive law modifications for robustness. Considered modifications were Dead zone modification, Sigma modification, e-modification and projection operator algorithm modification. Speed control of three phase induction motor in this paper was depend on decoupling benefits of rotor flux Indirect Field Orientation (IFO). Simulation results shows improved robustness characteristics and performance. In order to make the case study under consideration more realistic, the work considered the limitation imposed on supplied voltage in real application, where this was the other challenge which has been avoided by many researchers.

Choosing the right controller with the right approach is one of any power converter's biggest concerns. In order to optimise induction heating, a hybrid Cuk converter with a fractional-order proportional integral derivative (FOPID) controller is built. The findings show an improved time domain responsiveness in the FOPID controlled closed-loop hybrid DC-DC converter (CDHC) system. In order to improve the interface between the resonant inverter and DC source and to step up voltage with less output ripple, Cuk converters are used. The research project is concerned with modelling and simulating a hybrid closed-loop DC converter system. The findings show an improved time domain responsiveness in the FOPID controlled CDHC system. The suggested approach offers advantages such as high-power density and buck boost capability. After being inverted, the Cuk converter's output is applied to a DC load. The time responses of the closed loop proportional integral (PI) and FOPID controlled homogeneous charge compression ignition (HCCI) systems are compared. The hardware is implemented and tested for the CDHC system for electric vehicles. The results indicate that the FOPID controlled CDHC system has enhanced time response and benefits such as high-power density buck boost ability.

A primitive equation, hydrostatic, terrain-following coordinate ocean general circulation model Ž . OGCM is used to investigate the mean water mass pathways from the subtropics to the tropics in the Atlantic Ocean. The OGCM is used in a fully realistic configuration of the Atlantic, from 308S to 658N, with realistic bathymetry. Surface forcings are provided by the COADS climatology. A non-eddy-resolving numerical simulation is analyzed with 3r48 horizontal resolution and 20 terrain-following vertical levels. The primary objective of this study is to assess the theoretical framework extending the ventilated thermocline theory to the equator in the context of the numerical calculation, and to establish whether the predictions of a steady-state theory can be verified in a time-dependent simulation, in which rectified seasonal effects on the time mean yearly circulation may be important. The Bernoulli function is evaluated on isopycnal surfaces outcropping in the subtropics in both hemispheres and floats are injected at different northern and southern latitudes. In both hemispheres, the interior flow velocities are parallel to the Bernoulli streamlines that are significantly modified by inertia only very near the equator and on the Equatorial UnderCurrent Ž . EUC . In the Northern Atlantic, pathways from the subtropics to the tropics exist for the isopycnal surfaces outcropping at 20-228N. The injected floats reach the EUC following a zigzag pattern

The increasing use of renewable energy sources such as wind energy, bio-gas energy, solar energy, and hydro potential have become essential to adopt a low cost generating system, which are capable of operating in the remote areas, and in conjuction with the variety of prime movers. With wind turbines and mini/micro hydro generators as an alternative energy source, the induction generators are being considered as an alternative choice to well developed sysnchronous generators because of their lower unit cost, inherent ruggedness, operational and maintenance simplicity, absence of separate DC source, self-protection against overloads and short circuits etc. The research is underway to investigate the various issues related to the use of induction generator as potential alternative to the synchronous generator to utilize the small hydro and wind energy to accomplish the future energy requirement, and feed the power to remote locations and far flung areas, where extension of grid is not...

Background The pharmacokinetics of both propofol and remifentanil have been described extensively. Although they are commonly administered together for clinical anesthesia, their pharmacokinetic interaction has not been investigated so far. The purpose of the current investigation was to elucidate the nature and extent of pharmacokinetic interactions between propofol and remifentanil. Methods Twenty healthy volunteers aged 20-43 yr initially received either propofol or remifentanil alone in a stepwise incremental and decremental fashion a target controlled infusion. Thereafter, the respective second drug was infused to a fixed target concentration in the clinical range (0-4 microg/ml and 0-4 ng/ml for propofol and remifentanil, respectively) and the stepwise incremental pattern repeated. Frequent blood samples were drawn for up to 6 h for propofol and 40 min for remifentanil after the end of administration and assayed for the respective drug concentrations with gas chromatography-ma...

We investigated the effects of mutations K65R and K65R plus M184V on enzymatic function and mechanisms of drug resistance in subtype C reverse transcriptase (RT). Recombinant subtype C HIV-1 RTs containing K65R or K65R+M184V were purified from Escherichia coli. Enzyme activities and tenofovir (TFV) incorporation efficiency by wild-type (WT) and mutant RTs of both subtypes were determined in cell-free assays. Efficiency of (-) ssDNA synthesis and initiation by subtype C RTs was measured using gel-based assays with HIV-1 PBS RNA template and tRNA3 Lys as primer. Single-cycle processivity was assayed under variable dNTP concentrations. Steady-state analysis was performed to measure the relative inhibitory capacity (ki/ km) of TFV-disphosphate (TFV-DP). ATP-dependent excision and rescue of TFV-or ZDVterminated DNA synthesis was monitored in time-course experiments. The efficiency of tRNA-primed (-)ssDNA synthesis by subtype C RTs was: WT > K65R > K65R+M184V RT. At low dNTP concentration, K65R RT exhibited lower activity in single-cycle processivity assays while the K65R+M184V mutant showed diminished processivity independent of dNTP concentration. ATP-mediated excision of TFV-or ZDV-terminated primer was decreased for K65R and for K65R+M184V RT compared to WT RT. K65R and K65R+M184V displayed 9.8and 5-fold increases in IC50 for TFV-DP compared to WT RT. The Ki/Km of TFV was increased by 4.1-and 7.2-fold, respectively, for K65R and K65R+M184V compared to WT RT. The diminished initiation efficiency of K65R-containing RTs at low dNTP concentrations have been confirmed for subtype C as well as subtype B. Despite decreased excision, this decreased binding/incorporation results in diminished susceptibility of K65R and K65R+M184 RT to TFV-DP.

BackgroundWe investigated the effects of mutations K65R and K65R plus M184V on enzymatic function and mechanisms of drug resistance in subtype C reverse transcriptase (RT).MethodsRecombinant subtype C HIV-1 RTs containing K65R or K65R+M184V were purified fromEscherichia coli. Enzyme activities and tenofovir (TFV) incorporation efficiency by wild-type (WT) and mutant RTs of both subtypes were determined in cell-free assays. Efficiency of (-) ssDNA synthesis and initiation by subtype C RTs was measured using gel-based assays with HIV-1 PBS RNA template and tRNA3Lysas primer. Single-cycle processivity was assayed under variable dNTP concentrations. Steady-state analysis was performed to measure the relative inhibitory capacity (ki/km) of TFV-disphosphate (TFV-DP). ATP-dependent excision and rescue of TFV-or ZDV-terminated DNA synthesis was monitored in time-course experiments.ResultsThe efficiency of tRNA-primed (-)ssDNA synthesis by subtype C RTs was: WT > K65R > K65R+M184V RT. ...

The models for the production of methyl acetate from the esterification reaction of methanol and acetic acid in a reactive distillation column (RDC) were developed. Six trays were selected as the reactive zone; methyl acetate and water were produced with unreacted acid and methanol in the RDC. Azeotropic mixture of methyl acetatemethanol was formed at the top of the reactive distillation column. The constant boiling mixture of Methyl acetate-methanol was eliminated using pressure swing distillation (PSD) principle simulated in aspen plus. In aspen plus, the reactive distillation was configured as high pressure column (HDC) operated at 14bar and 70 o C and a second column as low pressure column (LPC) operated at 0.56 bar 44 o C. The results obtained from two simulation software (ASPEN PLUS and MATLAB) were compared as 0.3967 mole methanol and 0.5983 mole methyl acetate using Aspen Plus and 0.4408 mole methanol and 0.5592 mole methyl acetate using Mat lab before PSD and 0.2710 mole methanol and 0.7290 mole methyl acetate after PSD. The results obtained were validated using literature data, 0.2154 mole methanol and 0.7846 mole methyl acetate were compared with 0.2710 and 0.7290 obtained from aspen plus with percentage deviation of 20.50 for methanol and-7.63 for methyl acetate.

This letter studies the tracking performance of a stochastic gradient-based adaptive algorithm, namely the maximum correntropy criterion algorithm, where a random walk is used to model the non-stationarity. In our analysis, we use the energy conservation argument to derive expressions for the steady-state excess mean square error (EMSE). We consider two different cases for measurement of noise distribution including the Gaussian noise and general non-Gaussian noise. For the Gaussian case, we derive a fixed-point equation that can be solved numerically to find steady-state EMSE value. For the general non-Gaussian case, we derive an approximate closedform expression for EMSE. For both cases, unlike the stationary environment, the EMSE curves are not increasing functions of step size parameter. We use this observation to find the optimum step size learning parameter for general non-Gaussian case. The validity of the theoretical results are justified via simulation results.

Background: It has long been recognized that sensitivity analysis plays a key role in modeling and analyzing cellular and biochemical processes. Systems biology markup language (SBML) has become a well-known platform for coding and sharing mathematical models of such processes. However, current SBML compatible software tools are limited in their ability to perform global sensitivity analyses of these models. Results: This work introduces a freely downloadable, software package, SBML-SAT, which implements algorithms for simulation, steady state analysis, robustness analysis and local and global sensitivity analysis for SBML models. This software tool extends current capabilities through its execution of global sensitivity analyses using multi-parametric sensitivity analysis, partial rank correlation coefficient, SOBOL's method, and weighted average of local sensitivity analyses in addition to its ability to handle systems with discontinuous events and intuitive graphical user interface. SBML-SAT provides the community of systems biologists a new tool for the analysis of their SBML models of biochemical and cellular processes.

In this paper, a universal active power filter is proposed for harmonic and reactive power compensation in the single-phase to three-phase systems. The proposed configuration solves a typical problem found in remote (or rural) applications, where only a single-phase grid is available and there is a demand to supply three-phase loads. A suitable control strategy is presented to regulate the load voltage, the power factor, and to minimize the voltage and current harmonics simultaneously. Simulated and experimental results are also presented.

The main drawback of induction generator in wind energy conversion systems applications is its need for leading reactive power to build up the terminal voltage and to generate electric power. Using terminal capacitor across generator terminals can generate this leading reactive power. The capacitance value of the terminal capacitor is not constant but it is varying with many system parameters like shaft speed, load power and its power factor. If the proper value of capacitance is selected, the generator will operate in selfexcited mode. This paper presents direct methods derived from loop and nodal analyses to obtain different criteria for maintaining self-excitation and performance characteristics of an isolated, three-phase, selfexcited induction generator (SEIG). Results of a detailed investigation on a conventional 3kW induction motor operated as a SEIG are presented to illustrate the effectiveness of the proposed method.

where the output voltage at the termination point of the transmission line may not reach its steady state value during the clock period, it is possible to reduce energy dissipation while meeting a DC noise margin by driver sizing. This is in sharp contrast with the steady state analysis, which states that driver size has no impact on the energy dissipation per output change. In addition, we propose a new design metric which is the product of energy, delay and some measure of ringing in lossy transmission lines. In particular, this paper provides closed-form expressions for the energy dissipation, 50% propagation delay and the percentage of maximum undershoot when the circuit exhibits an underdamped behavior. This metric is used during the driver sizing problem formulation for minimum energy-delay-ringing product. The experimental results carried out by HSPICE simulation verify the accuracy of our models.

A 14 Mw TRIGA research reactor is operated on the Institute for Nuclear Research site. In the event of a nuclear accident or radiological emergency that may affect the public the effectiveness of protective actions depends on the adequacy of the selected accident scenarios and estimation of radiological consequences to public and environment, prepared in advance. The paper present comparative calculation for two accident scenarios and for both for HEU and LEU nuclear fuel. The evaluation of the radiological consequences considers both early and late consequences.

A perfect velocity tracking controller is synthesized involving a pneumatic muscle (PM) actuator which may be used for resistance exercise in space applications. In such biomedical devices, isokinetic (constant velocity) tracking is critically important for rehabilitation and emulation of limb motion. To wrap feedback around a pneumatic muscle to perform velocity tracking requires a careful analysis to ensure the efficacy of the device with human use. First a linearization of the dynamics of the PM is performed with a steady state analysis of a controller design. Generalization to nonlinear dynamics is then presented.

In this paper we introduce, numerical computation of some iterative techniques for solving system of linear simultaneous equations of 4 or more variables. Many iterative techniques is presented by the different formulae. Using Jacobi method, Seidel method and SOR method and their results are compared. The software, Matlab 2009a was used to find the solution of the linear simultaneous equations having diagonally dominant in coefficient matrix. Numerical rate of convergence of solution has been found in each calculation. It was observed that the Seidel method converges at the 12iteration while Jacobi and SOR methods converge to the exact value of X(x, y, z, t) with error level of accuracy 10-15 at the 22th iteration respectively. However, when we compare performance, we must compare both cost, speed of convergence. Some numerical examples are given to illustrate the efficiency and robustness of the techniques. It was then concluded that Seidel is the most effective technique.

The periodicity condition of state variable ensures the circuit periodic steady state. Circuits with linear dynamic elements and nonlinear resistors can be solved iteratively using the method of equivalent sources, by replacing the nonlinear resistors with controlled sources having constant resistance throughout the iterations. The final values of the state variables appear as affine functions of their initial values and only the additive term changes iteratively. By imposing a periodicity condition the initial values of the state variables are obtained by solving a linear system of equations in which the system matrix remains unchanged during each iteration and only the right hand side is modified. This matrix is inverted only once before the iterations begin.

This paper presents the development and application of a MATLAB-based numerical simulator for forecasting oil production from a multilateral, saturated reservoir. The simulator predicts reservoir pressure depletion, oil production and cumulative oil production over time for two formations, while accounting for physical assumptions such as solution gas drive and no fluid interaction between reservoirs. Using reservoir and well properties, the pressure and production trends of both the upper and lower formations are forecasted over a two-year period. Results indicate a 1000psi pressure drop in the lower formation and a 1157psi drop in the upper formation. Additionally, the simulator was used to investigate the impact of varying wellhead pressures on liquid holdup and oil production during the first 150 days. It was observed that a wellhead pressure of 1800psi minimized liquid holdup, although this did not correspond to the maximum oil production, highlighting the trade-off between reducing holdup and optimizing production. This research provides an adaptable tool for reservoir engineers to optimize production forecasting and holdup analysis under different operational conditions. Suggestions for further refinements and improvements to the simulator are welcomed to enhance its accuracy and application to broader reservoir scenarios.

In this paper, we present the steady state analysis of a doubly-fed induction generator (DFIG) adopted for wind power generation. The three-phase induction machine connected to the network, to work as a generator for wind farms, is excited on the rotor circuit by a slip-frequency current injected to the rotor, from an exciter mounted on the same shaft of the machine. The resulting rotating magnetic field rotates at synchronous speed; as such the generated power has a constant frequency independent of the shaft speed. Effects of the excitation voltage magnitude and phase angle on the active and reactive power are studied, when the machine runs at constant speed. It has been shown that by controlling the excitation voltage magnitude and phase angle would control the mode of operation of the machine; motor mode or generator mode. Furthermore, the effects of the shaft speed on the active and reactive power at constant excitation voltage magnitude and constant phase angle are also investigated.

Multilevel inverters (MLIs) are a key solution for converting DC to AC power. In this article, an improved single-source SC-MLI topology is developed for solar PV applications. It consists of 12 unidirectional switches, 3 capacitors, and 3 diodes to provide sextuple voltage boosting with a lower cost function. Since the capacitor's voltage is self-balanced, there is no need for an additional circuit or sensors, bringing down the circuit's complexity. A simple and fundamental frequency-based control strategy, nearest-level pulse width modulation, is applied to assess the viability of the proposed topology. As a result, the proposed topology has an efficiency of over 97%, and it can generate 13 levels with a total harmonic distortion (THD) of 6.51%. Comparative analysis is performed to show the feasibility of the proposed topology which outperformed other 13-level similar topologies in terms of component count, cost factor, and boosting factor. The proposed topology's performance is evaluated under static and dynamic loads. Furthermore, the thermal analysis is performed using PLECS software to determine the efficiency of the circuit topology. Finally, the feasibility of the proposed circuit is verified for solar PV application.

The foremost cause of harmonic contamination is the ample utilization of loads of non-linear type such as static power converters. Because of this load, the input power factor (PF) decreases heavily as they draw a current of non-sinusoidal in nature. This article gives a general presentation investigation of two PF rectification (PFR) converter (PFRC) geographies: Cuk type and single-ended primary-inductance converter or SEPIC type converter. The average current control (ACC) technique is utilized here. Notwithstanding, for control of output voltage, techniques like conventional proportional integral derivative controller (PIDC) or fractional order proportional integral derivative controller (FOPIDC) are used, and the gains of the controller are calculated using a novel teaching learning optimization technique (TLOT), considering integral time absolute error (ITAE). The analysis of both PFRC acted in Simulink/MATLAB and the estimated converters are studied under consistent and dynamic state conditions. The FOPIDC Cuk PFRC is providing 2.97% of THD compared to other converters.

Penetration of renewable energy in distribution generation increases power quality in the output. The harmonics inherent in the inverters are a major contributor to the power quality issues in the distribution system. Multilevel inverters are used to get rid of the harmonics inherent in the inverter output. Among the multilevel inverter topology cascaded multilevel inverters have taken center stage due to their simple topology and control with lesser components. This paper reviews different multilevel inverter topologies that have led to cascaded multilevel inverter topology and applies pulse width modulation (PWM) techniques to the topology. Phase disposition PWM technique is applied on the cascaded H-bridge multilevel inverter (MLI) topology for 5-level, 7-level, and 9-level inverter topologies. The total harmonic distortion (THD) obtained for these topologies is compared with and without the use of an LC filter in the inverter output. PWM techniques including phase disposition, for five-level, seven-level, and ninelevel MLI methods are applied on the cascaded multilevel inverter and results are compared for harmonic reduction in the inverter output.

We carried out experimental and theoretical research on dark Raman resonances in the absorption of the probe monochromatic wave in a thin vapor cell, whose length is much less than the diameters of probe and coupling laser beams. In this case, only the slow atoms have enough time to settle down to the dark quantum state during a free flight between the end walls of the cell. As a result, a sub-Doppler structure is observed when one sweeps both the coupling and probe laser frequencies keeping the Raman resonance condition. Second harmonic lock-in detection is used to evaluate sharpness of the dark-resonance line. The cell-length dependence of the observed spectral profile is satisfactorily reproduced by the steady-state analysis of the density matrix in which the velocity-dependent transit time effect is taken into account.

This manuscript explains the analysis of the soft switching technology to measure the energy loss of high-frequency closed loop boost converter with zero-current switching (ZCS) and zero-voltage switching (ZVS) techniques. To get these attributes, the use of soft power converters that utilize soft switching techniques is essential. This paper examines the ZCS/ZVS AC/DC converter design, used in high-power systems for renewable energy and battery charging. This converter architecture ensures semiconductor switches turn on and off at zero voltage and current. It smooths rectifier diodes, reducing switching and reverse recovery losses. It has better power quality, efficiency, and input power factor. Practical study has been done to verify the converter's theoretical analysis. Empirical research shows gentle switching enhances system efficiency. Energy losses are reduced by 26% while turning on and 20% when turning off compared to the ZVS and ZCS. The prototype converter is built to corroborate simulation results. Compared to ZVS and ZCS, switching losses are lower and efficiency decline is modest across the operating range. This shows that the simulation and experimental results are consistent.

Background: Structural analysis of cellular interaction networks contributes to a deeper understanding of network-wide interdependencies, causal relationships, and basic functional capabilities. While the structural analysis of metabolic networks is a well-established field, similar methodologies have been scarcely developed and applied to signaling and regulatory networks. We propose formalisms and methods, relying on adapted and partially newly introduced approaches, which facilitate a structural analysis of signaling and regulatory networks with focus on functional aspects. We use two different formalisms to represent and analyze interaction networks: interaction graphs and (logical) interaction hypergraphs. We show that, in interaction graphs, the determination of feedback cycles and of all the signaling paths between any pair of species is equivalent to the computation of elementary modes known from metabolic networks. Knowledge on the set of signaling paths and feedback loops facilitates the computation of intervention strategies and the classification of compounds into activators, inhibitors, ambivalent factors, and non-affecting factors with respect to a certain species. In some cases, qualitative effects induced by perturbations can be unambiguously predicted from the network scheme. Interaction graphs however, are not able to capture AND relationships which do frequently occur in interaction networks. The consequent logical concatenation of all the arcs pointing into a species leads to Boolean networks. For a Boolean representation of cellular interaction networks we propose a formalism based on logical (or signed) interaction hypergraphs, which facilitates in particular a logical steady state analysis (LSSA). LSSA enables studies on the logical processing of signals and the identification of optimal intervention points (targets) in cellular networks. LSSA also reveals network regions whose parametrization and initial states are crucial for the dynamic behavior. We have implemented these methods in our software tool CellNetAnalyzer (successor of FluxAnalyzer) and illustrate their applicability using a logical model of T-Cell receptor signaling providing non-intuitive results regarding feedback loops, essential elements, and (logical) signal processing upon different stimuli. The methods and formalisms we propose herein are another step towards the comprehensive functional analysis of cellular interaction networks. Their potential, shown on a realistic Tcell signaling model, makes them a promising tool.

In smelting processes, a large amount of off-gas emission is often generated, which can cause serious environmental and plant hygiene problems if not properly treated. Off-gas cleaning systems extract and treat the hazardous emissions, and ensure that the smelter operation is in accordance with environmental and industrial hygiene regulations. To this end, it is paramount that a well-designed control structure be incorporated into the system. In this work a plantwide control design procedure is applied to an industrial nickel smelter furnace off-gas cleaning system. We first approach the problem by conducting a steady-state analysis based on a nonlinear model of the process, where the objective is to determine how to achieve safe, clean and economic operation in terms of energy consumption. Results reveal that a large amount of energy can be saved by controlling the temperature in the furnace freeboard at its upper bound (active constraint). For the same reason, the temperatures in the two louvers (active constraints) should be controlled at their respective upper bounds so to minimize air intake into the system. The selection of the ''unconstrained'' variable to be controlled is found by applying the selfoptimizing control technique, and the results indicate that a small loss is acceptable when one of the manipulated variables is fixed at its nominal optimal operating point, a highly desirable choice from an operational viewpoint. The bottleneck of the system is identified as the fans' discharge pressures when we allow the feed rate as a degree of freedom. Furthermore, a design change consisting of the installation of an auxiliary air intake in the smelter furnace shows to be a very effective economic alternative to minimize energy consumption. A control structure is then designed where the issue is to keep pressures in the system well within the negative region by determining the configuration of the regulatory and supervisory control layers such that acceptable dynamic performance in face of known, deterministic disturbance is achieved. Nonlinear dynamic simulations are performed to validate the suggested control structure for both modes of operation in the original system and in the proposed design change. The results showed that both regulatory and supervisory designs should make use of the simplicity of decentralized PI control schemes associated with some cascaded configurations so as to boost the disturbance rejection capabilities of the system.

This paper presents a qualitative logic-based method for the steady-state analysis and revision of metabolic networks with inhibition. The approach is able to automatically revise an initial metabolic model -through the addition and removal of whole reactions or individual substrates, products and inhibitors -in order to ensure the existence of a steady-state behaviour consistent with a set of experimental observations. We show how this can be done in a nonmonotonic logic programming setting and discuss the challenges that arise when metabolic cycles or mutual inhibitions occur in the underlying network.

This paper presents a qualitative logic-based method for the steady-state analysis and revision of metabolic networks with inhibition. The approach is able to automatically revise an initial metabolic model -through the addition and removal of whole reactions or individual substrates, products and inhibitors -in order to ensure the existence of a steady-state behaviour consistent with a set of experimental observations. We show how this can be done in a nonmonotonic logic programming setting and discuss the challenges that arise when metabolic cycles or mutual inhibitions occur in the underlying network.

A generalized study of the parallel connection of Class-D parallel resonant ( ) inverters is presented. Steady-state analysis and design considerations are provided in detail, evaluating the current distribution, output power and efficiency of the circuit as a function of the number, , of phases. Inductor equivalent series resistance and MOSFET conduction losses are considered in order to foresee and optimize the inverter efficiency. The power supplied to the load can be controlled at constant switching frequency by using the phase displacement of the output voltages of each Class-D leg, although for the interests of this specific application, only one inverter is phase shifted. The applicability of the general analysis is demonstrated on two practical designs with three and five phases, resulting in 400-W and 1-kW high-pressure sodium lamp ballasts, respectively.

With advancement in new edge machine technology, self-excited induction generators (SEIG) has gained attention of researchers in the field of renewable energy exploration and exploitation. SEIG has increasingly been used in generating electrical energy from conventional and non-conventional energy sources. The main drawback of induction generator in wind energy conversion systems applications is its need for leading reactive power to build up the terminal voltage and to generate electric power. Using terminal capacitor across generator terminals can generate this leading reactive power. The capacitance value of the terminal capacitor is not constant but it is varying with many system parameters speed, load power and its power factor. If the proper value of capacitance is selected, the generator will operate in self-excited mode. To find this capacitor value two non-linear equations have to be solved. Different numerical methods for solving these equations under R-L load. This paper reviews the previous techniques and a complete mathematical analysis over starting period to find the minimum excitation capacitor required (𝐶 𝑒-𝑚𝑖𝑛 ) of self excited induction generators (SEIG)using two method Nodal Admittance Approach and Loop Impedance Approach

Multimodulus algorithms (MMA) based adaptive blind equalizers mitigate inter-symbol interference in a digital communication system by minimizing dispersion in the quadrature components of the equalized sequence in a decoupled manner, i.e., the in-phase and quadrature components of the equalized sequence are used to minimize dispersion in the respective components of the received signal. These unsupervised equalizers are mostly incorporated in bandwidth-efficient digital receivers (wired, wireless or optical) which rely on quadrature amplitude modulation based signaling. These equalizers are equipped with nonlinear error-functions in their update expressions which makes it a challenging task to evaluate analytically their steady-state performance. However, exploiting variance relation theorem, researchers have recently been able to report approximate expressions for steady-state excess mean square error (EMSE) of such equalizers for noiseless but interfering environment. In this work, in contrast to existing results, we present exact steady-state tracking analysis of two multimodulus equalizers in a non-stationary environment. Specifically, we evaluate expressions for steady-state EMSE of two equalizers, namely the MMA2-2 and the βMMA. The accuracy of the derived analytical results is validated using different set experiments and found in close agreement.

where the output voltage at the termination point of the transmission line may not reach its steady state value during the clock period, it is possible to reduce energy dissipation while meeting a DC noise margin by driver sizing. This is in sharp contrast with the steady state analysis, which states that driver size has no impact on the energy dissipation per output change. In addition, we propose a new design metric which is the product of energy, delay and some measure of ringing in lossy transmission lines. In particular, this paper provides closed-form expressions for the energy dissipation, 50% propagation delay and the percentage of maximum undershoot when the circuit exhibits an underdamped behavior. This metric is used during the driver sizing problem formulation for minimum energy-delay-ringing product. The experimental results carried out by HSPICE simulation verify the accuracy of our models.

The photovoltaic thermal collector can provide thermal and heat power at the same time. In this paper, a photovoltaic/thermal sheet and tube collector has been numerically investigated. The paper focuses on the development of a hybrid solar collector PV/T. This model will be applied to optimize the operation of the PVT collector in the semi-arid climate. A mathematical model has been developed to determine the dynamic behavior of the collector, based on the energy balance of six main components namely a transparent cover, a PV module, a plate absorber, a tube, water in the tube and insulation. It has been validated by comparing the obtained simulation results with experimental results available in literature, where good agreement has been noted. Using our developed model, the heat and electrical power of sheet and tube collector has been analyzed for four typical days of year with the meteorological parameters of Monastir, Tunisia. Furthermore, the effect of solar radiation, the inlet water temperature, the number of glazing covers and the conductive heat transfer coefficient between plate absorber and PV module have been involved to identify their influence on the thermal and electrical efficiencies. The monthly thermal and electrical energies is also evaluated.

In this paper, we are to develop a second-order LMS-type Volterra filter to reduce distortions of data transmission over analog telephone channels due the channel impulse response and inter-symbol interference (ISI). A novel approach for updating the linear and quadratic coefficients vectors of a second-order Volterra filter is presented. The innovative features of this algorithm provide distinct convergence treatment of the linear and quadratic Volterra filter kernels, and adaptive formulation for the convergence factors, hence providing a unique platform for both linear and nonlinear channel adaptive handling. Simulations are carried in an equalization set-up to compare the performance of this algorithm with conventional and variable step LMS algorithms. The obtained results show that this algorithm brings substantial increase in the convergence speed while keeping, to some extent, the simplicity of the conventional LMS algorithm. Considering the performance of the formulated algorithm, it could be a useful tool for adaptive equalization applications.

The regulation of density-dependent behaviour by means of quorum sensing is widespread in bacteria, the relevant phenomena including bioluminescence and population expansion by swarming, as well as virulence. The process of quorum sensing is regulated by the production and monitoring of certain molecules (referred to as QSMs); on reaching an apparent threshold concentration of QSMs (reflecting high bacterial density) the bacterial colony in concert 'switches on' the density-dependent trait. In this paper a mathematical model which describes bacterial population growth and quorum sensing in a well mixed system is proposed and studied. We view the population of bacteria as consisting of downregulated and up-regulated sub-populations, with QSMs being produced at a much faster rate by the up-regulated cells. Using curve fitting techniques for parameter estimation, solutions of the resulting system of ordinary differential equations are shown to agree well with experimental data. Asymptotic analysis in a biologically relevant limit is used to investigate the timescales for up-regulation of an exponentially growing population of bacteria, revealing the existence of bifurcation between limited and near-total upregulation. For a fixed population of cells steady-state analysis reveals that in general one physical steady-state solution exists and is linearly stable; we believe this solution to be a global attractor. A bifurcation between limited and near-total up-regulation is also discussed in the steady-state limit.

Due to speed fluctuations of unregulated wind turbines, the terminal voltage may increase to dangerously high levels which have been reported to cause capacitor failure at wind farms. In this topic this paper examines a steady state performance analysis of stand-alone double stator induction generator self excited with two independents capacitors banks. An impedance approach based on double three-phase induction-generator model is employed to derive steady equations of the studied double stator SEIG. Steady state characteristics of different configurations of the studied double stator self excited induction generator are clearly examined and compared.

We investigate the application of deterministic chaotic maps to model traffic sources in packet based networks, motivated in part by recent measurement studies which indicate the presence of significant statistical features in packet traffic more characteristic of fractal processes than conventional stochastic processes. We describe one approach whereby traffic sources can be modeled by chaotic maps, and illustrate the traffic characteristics that can be generated by analyzing several classes of maps. We outline a potential performance analysis approach based on chaotic maps that can be used to assess the traffic significance of fractal properties. We show that low order nonlinear maps can capture several of the fractal properties observed in actual data, and show that the source characteristics observed in actual traffic can lead to heavy-tailed queue length distributions. It is our conclusion that while there are considerable analytical difficulties, chaotic maps may allow accurate, yet concise, models of packet traffic, with some potential for transient and steady state analysis.

This paper presents the development and application of a MATLAB-based numerical simulator for forecasting oil production from a multilateral, saturated reservoir. The simulator predicts reservoir pressure depletion, oil production and cumulative oil production over time for two formations, while accounting for physical assumptions such as solution gas drive and no fluid interaction between reservoirs. Using reservoir and well properties, the pressure and production trends of both the upper and lower formations are forecasted over a two-year period. Results indicate a 1000psi pressure drop in the lower formation and a 1157psi drop in the upper formation. Additionally, the simulator was used to investigate the impact of varying wellhead pressures on liquid holdup and oil production during the first 150 days. It was observed that a wellhead pressure of 1800psi minimized liquid holdup, although this did not correspond to the maximum oil production, highlighting the trade-off between reducing holdup and optimizing production. This research provides an adaptable tool for reservoir engineers to optimize production forecasting and holdup analysis under different operational conditions. Suggestions for further refinements and improvements to the simulator are welcomed to enhance its accuracy and application to broader reservoir scenarios.

This paper provides comprehensive development procedures and final forms of mathematical models of unified power flow controller (UPFC) for steadystate, transient stability a$ eigenvalue studies. Based on the developed models, the impacts of control strategy, parameters and location of UPFC on power system operating conditions are discussed. The accuracy of the developed models is verified through comparing the study results with those obtained from detailed time-domain simulation using the Electromagnetic Transients Program (EMTP).

Simulation and experimental studies of two output series resonant inverter with Asymmetrical Duty Cycle (ADC) control are presented in this work. The prototype has been implemented using 06 MOSFET transistors with 06 antiparallel diodes as switches. The inverter is designed to supply two resonant loads. Simulation and experimental results of the output waveforms of the proposed inverter for RLC load are given. Good agreement was obtained between simulation and laboratory experiments. Keywords—A two output series resonant inverter, ADC contr l, Simulation, Exprimental, MOSFET

The oil and gas is a very vast industry. The production well is the crucial thing in oil and gas because it is the measurement of the profitability of the reservoir itself. It is a common thing that the production system will undergo multiphase condition due to the condition of the reservoir. Besides oil, other substance such as gas, water, sand, hydrates and waxes will be produce through the tubing string. The simultaneous flow of those substances will occur from the reservoir until the chrismas tree. It is very crucial to have a prediction tool so that optimum flow rate can be achieved with less pressure gradient and liquid holdup. Theoretically, a zero friction factor in a flowing fluid in a pipe cannot be achieved because it is only applicable to static fluid. Recovery from the wells need special challenges and requires accurate multiphase flow prediction tool for several applications, such as the design and schematic of the production systems, separation of phases in vertical wells, and multiple separation (topside, seabed or bottom-hole). As for any multiphase flow, the inlet condition such as flow rates, flow patterns, volume fractions of the fluids and the pressure need to be known. Due to that, it is crucial to have more accurate and efficient multiphase flow prediction tool. The method that being used now separates flow pattern and flow behaviour prediction modelling. Due to that, the results that being produced was inaccurate. As an example, a multiphase flow of oil and gas are treated as both single phase, and ignoring the interactions between both of the fluids such as the slippage. However, the improved prediction tools now will allow such interaction and more accurate result can be obtained.