Simulation of dynamic adjustment processes for network equilibrium problems using electronic circuit analysis software

The dynamic simulation of chemical processes is an indispensable and central tool for process design, analysis, and operation. Compared to a steady state simulation, the dynamic process simulation has some outstanding advantages, such as the assessment of control system reliability before its implementation on the real plant, the planning and testing of start-up and shutdown procedures, the training of operators, the possibility to investigate the causes of previous accidents, and to determine the consequences of possible accidents. In particular, as far as the accidents are concerned, it is not of minor importance that they are an economic liability to the company and the community (Fewtrell and Hirst, 1998). Fewtrell and Hirst highlighted also that high-cost accidents have some common features. The coupled dynamic simulation of process and accidents allows identifying the aforementioned deficiencies while moving towards a more safe and productive management of chemical processes. This manuscript analyzes the possible plant/accident interactions and suggests the simultaneous dynamic integration of process simulators and accident simulators. In fact, to simulate a realistic accident dynamics, both the dynamics of the plant and of the accidental event should be run simultaneously since they are biuniquely interrelated and they influence one another. The manuscript investigates the feedbacks and interactions between the process and the accident by means of a specific case study.

Supercritical fluid extraction (SFE) is a process in which a solute present in a homogeneous mixture is preferentially dissolved by a supercritical fluid (SCF) solvent. SCFs are gases or liquids above their critical points. Under these conditions SCFs exhibit enhanced solvating power, higher selectivities, and other desirable physicochemical properties which makes them particularly good solvents. A dynamic SFE process simulator has been developed by modeling various units of a typical SFE process, and realism of the simulated results is enhanced by accounting for instrument noise, random drifts, transport delays, and analyzer dead times. The process simulator has been compared with operating data from a pilot-scale SFE process and yields good agreement. The dynamic process simulator provides a much needed insight into various process interactions and the nonlinearities that can exist in an integrated, multiunit process

A dye-sensitized solar cell model implementable in electrical circuit simulators

Facing the requirements of advancing the strategy of training elite talents, optimizing the talent training system and building first-class undergraduate education, the training of elite talents not only emphasizes problem - solving “how to do it?”, but also emphasizes thinking about problems “what to do?” to help students view and solve problems from a broader perspective, interdisciplinary and systematic thinking. In the teaching process of “electronic circuits”, we have clearly realized that with the rapid development of electronic circuit technology, electronic equipment has become increasingly integrated, electronic design automation (EDA) and the rapid development of various circuit simulation software have greatly simplified the complex circuit analysis and calculations. Because the world is analog, the signals in nature are analog signals, and analog circuits are inseparable from real life. Therefore, we have proposed a comparative teaching strategy of electronic circuit technology with “analogous thinking method”. The so-called analogy thinking refers to the logical reasoning method that transfers the knowledge of one special thing to another special thing based on the similarity or similarity in some aspects between two or two kinds of things. When two types of things are the same or similar in one or some aspects, analogy thinking can be used. In this paper, application of analogy as well as inspiring methodology in teaching feedback amplifier circuit have been given as a case study.

A thermo-mechanical study on the electrical resistance of aluminum wire conductors

The aim of this paper is to create an education tool to estimate the losses and the dynamic behavior of the junction temperature of a semiconductor device, to be employed in a simulation software of electrical circuits. It must be highlighted that the temperature is one of the most important variables to be controlled in a switch-mode power converter and presents a great impact on converter efficiency and power density. Due to the lack of a simple tool to analyze the thermal behavior of a static converter, this paper proposes an algorithm to predict the losses (conduction and switching) and the temperature behavior in a semiconductor device. Using this algorithm the heat-sink design can be optimized in order to project a converter with high power density. The methodology which easily extracts the loss and thermal models, without huge computational efforts, is demonstrated. The proposed approach can be used as an educational tool, since it can be easily implemented in a circuit simulation software, assisting students of Power Electronics. It is important to note, that experimental results are presented to validate the proposed approach.

A subthreshold model for use in circuit simulation software is described. The model includes representation of nonuniform substrate impurity concentrations and short-channel and narrow-channel effects, while being simple in form. It has been developed in concert with an automated parameter-extraction methodology. The model adds only one parameter to the existing strong inversion model with which it is fully integrated. The accuracy and computational efficiency are suitable for circuit simulation. The results of an extraction carried out on nMOS transistors with channel widths from 70 to 0.9 mu m and channel lengths from 35 to 1.25 mu m over a wide range of bias conditions are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The equivalent impedance curve of a 40W electrodeless fluorescent lamp is measured. A simulation circuit is used in the circuit simulation software (orCAD). The simulated results are compared with the experiments. With the operation frequency increase, the error between the simulation and experiment is increase from 3.3% (198KHz) to 20.1% (233KHz). The analysis of the increase of error has also been discussed

In this paper, the design and simulation of the LED inverter circuit using NOR gate in Proteus software is described. The aim of the practical is to show that simple digital inverter can be created with the NOR gate which is the universal gate and the LED will be used to show that the logic circuit is working. Incidentally, to turn the NOR gate into an inverter, it simply involves linking both inputs together and that simplifies all the layout. The simulation of the circuit was done using proteus software and as the input of the NOR gate-based inverter is changed the output LED source is also changed, and the functionality of the circuit is proved. The paper includes information about control Nor Gate in inverter configuration, the significance of digital logic circuit in basic electronics, and the utility of the Proteus software within learning and prototyping settings. The outcome supports that a NOR gate can invert depicted input indication and can power an LED in a straightforward, low-priced circuit, which forms the basis of more complicated digital set of rules circuits

The analysis of dynamic deformation processes is an important task in civil and in mechanical engineering. One main emphasis is set on the derivation of the objects transmission function, represented by systems of ordinary or partial differential equations (“white box”-models). The parametric identification of the initial and boundary conditions and relevant material parameters is one of the new challenges in the application of least-square algorithms. Embedding the investigation of the deformation process in a combination of a theoretical and an experimental system analysis suitable methods are provided with adaptive KALMAN-filtering as central identification tool. In this paper the approach of a full system analysis is shown quantifying a dynamic “white-box”-model for the calculation of thermal deformations of bar-shaped machine elements. The task was motivied from mechanical engineering searching new methods for the precise prediction and computational compensation of thermal influences in the heating and cooling phases of machine tools (i.e. robot arms, etc.). The quantification of thermal deformations under variable dynamic loads requires the modelling of the non-stationary spatial temperature distribution inside the object. Based upon FOURIERS law of heat flow the high-grade non-linear temperature gradient is represented by a system of partial differential equations within the framework of a dynamic Finite Element topology. It is shown that adaptive KALMAN-filtering is suitable to quantify relevant disturbance influences and to identify thermal parameters (i.e. thermal diffusivity) with a deviation of only 0,2%. As result an identified (and verified) parametric model for the realistic prediction respectively simu-lation of dynamic temperature processes is presented. Classifying the thermal bend as the main deformation quantity of bar-shaped machine tools, the temperature model is extended to a temperature deformation model. In lab tests with an aluminium column control measurements show that the identified model can be used to predict the columns bend with a mean deviation smaller than 10 mgon. Consequently the deformation model is a precise predictor and suitable for realistic simulations of thermal deformations under variable dynamic loads. In future our activities will be primarily focussed on applications in industrial manufacturing. 1. Parametric identification of dynamic deformation processes The creation of a realistic parametric dynamic deformation model is directly associated with the task to combine systems of differential equations (theoretical physical model) with empirical measurements. Consequently basic principles of system theory can be adapted to the geodetic deformation analysis. The parametric identification of a dynamic “white box”-model 3rd IAG / 12th FIG Symposium, Baden, May 22-24, 2006

Extensive design tools are available today to develop digital application specific integrated circuits (ASICs), but the analog and mixed analog/digital ASIC arena is lagging behind. This panel will solicit views of tool developers and ASIC designers about the needs and direction of design tools for the development of mixed analog/digital ASIC over the next five years. The availability and usability of automatic/semi-automatic software and hardware for circuit partitioning, circuit simulation, place and route, silicon compilation and testing will be appraised Educational needs of the analog/digital designer will also be included in the discussions.

Numerical and field experimental investigation of wind turbine dynamic de-icing process

Introduction: The wide application of photovoltaic (PV) generation has practical significance for reducing fossil energy dependence and environmental pollution. To smooth the fluctuation of PV’s output power and eliminate the coupled double-line frequency ripple in two-stage grid-connected PV systems, it is indispensable to find an effective solution. This study aims to propose a control scheme based on supercapacitor energy storage and extended state optimal tracking control method to solve the problem of disturbance and oscillation fluctuations in the DC-bus voltage in the two-stage distributed grid-connected PV systems. Methods: Firstly, the dynamic model of the SC subsystem is established. Secondly, a mathematical model including all the unstable states of reference input, step, and double line frequency disturbance signals is built. Then, the extended state space model is constructed based on these two models. Furthermore, the optimal state feedback controller is designed by using the optimal tracking strategy. Results: In the case of the DC-bus voltage control test, when the PV output power fluctuates, the SC makes a rapid response and compensates for the power deficiency. After such a dynamic adjustment process, the DC-bus voltage stabilizes at the reference value of 400 V, which achieves the accurate regulation of the DC-bus voltage. The maximum absolute error is 1 V, the maximum relative error is 0.25%, the maximum overshoot is 0.75%, and the settling time is less than 10 ms. In the case of the gird-connected operation test, the dynamic responses of the DC-bus voltage and its error also demonstrate the excellent performance of accurate tracking and suppression of multiple fluctuations. Accordingly, the MPPT control functions well. For instance, taking 1.5 s, the PV output power drops suddenly, and the active power demand increases at the same time, which makes the power difference reach the maximum. Then, the SC promptly increases its output current to provide power support. At this time point, the maximum overshoot of the voltage tracking is 4.5%, and the maximum absolute error is less than 1 V. Discussion: This study provides a novel idea and approach to address the problem of suppressing the multiple fluctuations coupled to the DC-bus voltage in the two-stage grid-connected PV system via the single-phase DC/AC inverter. However, the results are limited to simulations. Hence, based on the work of this article, further studies should be conducted in applying the method in real operation systems and adapting it to deal with the multiple fluctuations suppression of the grid-- connected PV systems under asymmetrical grid conditions. Conclusion: The proposed control scheme can not only effectively restrain the fluctuations in the PV output power and load demand but also suppress the double line frequency ripple so that the DC-bus voltage can always be accurately regulated to its reference value, which also guarantees the reliable realization of the PV’s MPPT control. Additionally, the dynamic and static performances of the system, such as overshoot, rapidity, and tracking error, are satisfactory

This system consists of STM32F407 single chip microcomputer, STM32F103 single chip microcomputer, openmv vision module and k210 vision module are composed. Taking stm32f407 single chip microcomputer as the control core, combined with STM32F103 single chip microcomputer, openmv and k210, the device is designed to be used for drug transportation in wards and isolation wards with large workload in the hospital. The device uses openmv to identify the red solid line on the transportation ground of the hospital, Through the dynamic priority scheduling algorithm in PD algorithm, the priority of tasks is dynamically allocated according to the resource requirements of tasks, so as to have greater flexibility in resource allocation and scheduling, realize flexible tracking function and dynamic adjustment process, and make the car drive along the red. K210 visual module is used to reflect the appearance difference through the given training photos, which is as same as the identification number as possible, which is convenient to improve the identification rate. After more identification times, the identification number and its position information can be accurately identified, and the identified number and its position information can be transmitted to stm32f407 single chip microcomputer through serial port communication (considering the need to identify four numbers at the same time, two k210 are installed on the front of each vehicle), stm32f407 single chip microcomputer processes the identification information of k210 and tells STM32F103 single chip microcomputer the movement state of the car at this time through serial port communication. Finally, STM32F103 single chip microcomputer controls the car to move accordingly. The data interaction method of the two cars adopts wireless communication. The system has the advantages of short recognition time, digital recognition accuracy of up to 90% and good stability. It can better complete the drug delivery work required by hospital medical staff, and the work efficiency is higher than manual work. At the same time, the machine itself can also cut off the direct contact between medical staff and patients, which can greatly reduce the number of contact between medical staff and patients, Reduce the prevalence of cross infection and medical staff. The device adopts a multi-level priority scheduling algorithm to assign a priority to each process. During each process scheduling, the scheduler always schedules the task with the highest priority to execute, so as to make the car movement more flexible and more active. It is convenient to deal with some emergencies by using interrupts, which is more reasonable and suitable for real hospital medical work.

Researchers report a sizable number of companies that use cost‐plus pricing. While such a policy is normatively suspect, it is simple, conventional, and occasionally mandated by regulation. This paper investigates cost‐plus pricing as a dynamic adjustment process. As a dynamic policy, cost‐plus pricing is more flexible than has commonly been realized. When firms have constant or decreasing average costs, dynamic cost‐plus pricing typically exhibits rapid convergence to the attracting member of a pair of fixed points. If the average cost function is sufficiently U‐shaped, complicated and chaotic dynamics can emerge.