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A mandatory requirement for the concept of intelligent systems and of digital or cyber-physical twins is the availability of high-quality data. Therefore, the authors investigate the possibility to integrate sensors, actuators and information technologies in standardized machine elements such as screws, bearings and couplings. In this paper, the focus is on sensing machine elements, which are a sub-category of mechatronic machine elements. To gain insights about those in development as well as to verify and validate their functionality, prototypes are needed. Those prototypes should help the designer to gain knowledge about the product in development and they should preferably be developed with low efforts. Therefore, a method is proposed to analyse concepts of mechatronic machine elements, especially sensing machine elements, regarding critical aspects that may interfere with the functionality of the product. The method is based on analysing the flow of the signal that is used for the measurement, starting from its mechanical origin and ending at the analysis unit. Different examples of sensing machine elements are given in this article and the respective flow of the usable signal is analysed, leading to the identification of subsystems that can be tested individually. Based on this, prototypes for the subsystems are developed and introduced.

In this article, a six-port reflectometer is proposed, which utilizes nonmatched power detectors. In the presented solution, the signals reflected from power detectors are efficiently used to obtain a signal flow required for correct measurements. As a consequence, impedance matching networks for power detectors are no longer needed. Simultaneously, due to its balanced topology, the developed six-port exhibits advantageous measurement conditions and theoretically ideal matching at both its input and measurement ports. To experimentally validate the proposed concept, a six-port reflectometer operating at 2.4 GHz is designed, manufactured, and utilized in reflection coefficient measurements. The obtained results are consistent with the values measured using a commercial vector network analyzer. For additional verification, the impact of power detectors’ asymmetry is investigated theoretically and experimentally.

In the field of power system dynamics, a main challenge is to properly tune the inverter control parameters, where one important parameter is the inverter's output impedance, physical or virtual. In this work, we provide a proof showing that a minimal output impedance must be used in order to keep the system stable. Although this result is well-known among practicing engineers, our proof reveals a fundamental property which causes instabililty, namely the pole excess of the inverter dynamic model. To prove this claim we model the system as a signal flow diagram, where the output impedances of the inverters are described using static gain feedback. Based on this model, we show that the typical dynamic model of grid supporting inverters has a pole excess larger than 2, which causes instability when high feedback gain is used. This result may be used to design a numerical method for estimating the minimal impedance. The theorem is validated based on an array of photovoltaic plants in the Ramat Negev region, which is part of the Israeli power grid.

Phased-array multibeam RF beamformers require calibration of receivers used in an array of elements before the signals can be applied to an analog beamforming network. This article presents a fast $\mathcal {O}(n^2)$ algorithm for solving linear systems having a delay Vandermonde matrix (DVM) for the analog beamforming matrix. The structure of the DVM enables to obtain a fast algorithm to efficiently reverse multibeams at the DVM output such that calibration of the input low noise amplifiers can be achieved. The arithmetic complexity of the proposed DVM system solving algorithm is preferable over the standard matrix inversion consuming $\mathcal {O}(n^3)$ operations. Numerical experiments are presented for forward accuracy of the proposed algorithm computed at the calibration frequency. Moreover, numerical results are shown to compare the order of the arithmetic complexity and the execution time of the proposed algorithm. Signal flow graphs are presented for four- and eight-element multibeam phased arrays.

This paper presents a new approach to the thermal analysis of a solar concentrator. The Signal Flow Graph technique is applied to solve the heal Transfer problem in a flat receiver subjected to nonuniform flux distribution. Signal Flow Graph allows in a more easy graphical form to express the essential properties of the analyzed system, and directly obtain any parameter from the graph structural properties. With this method, there is no need of assuming uniform flux distribution over the whole receiver surface as in Hottel-Whillier-Woertz-Bliss approach, A Computer program has been established to obtain the thermal performance under different design and operating conditions using both approaches. In order to verify the theoretical results, an experimental concentrator was built with, one glass cover, flat receiver of 25 cm width and 94 cm length, The receiver is insulated with form plates of 3 cm thickness and fitted with two headers to supply the fresh water uniformly in the length direction. The reflecting surface is formed of unequal mirror segments which are arranged to concentrate most of the falling solar radiation on the upper third of the receiver surface. The set-up is suitably instrumented to measure the temperature at different points and the water mass flow rate through the receiver. The total and beam solar radiation intensities as well as the ambient temperature are also measured during the experimental work. Comparison between the predicted and measured results have shown that the thermal performance as calculated by the Signal Flow Graph is more fitted with the experimental results than that obtained by the HWWB approach. Therefore, the Signal Flow Graph approach is seen to be an easy and precise technique for the thermal analysis of concentrating collectors with nonuniform flux distribution on the receiver surface.

The development of mathematical modeling of infectious diseases is a key research area in various fields including ecology and epidemiology One aim of these models is to understand the dynamics of behavior in infectious diseases For the new strain of coronavirus (COVID-19), there is no vaccine to protect people and to prevent its spread so far Instead, control strategies associated with health care, such as social distancing, quarantine, travel restrictions, can be adopted to control the pandemic of COVID-19 This article sheds light on the dynamical behaviors of nonlinear COVID-19 models based on two methods: the homotopy perturbation method (HPM) and the modified reduced differential transform method (MRDTM) We invoke a novel signal flow graph that is used to describe the COVID-19 model Through our mathematical studies, it is revealed that social distancing between potentially infected individuals who are carrying the virus and healthy individuals can decrease or interrupt the spread of the virus The numerical simulation results are in reasonable agreement with the study predictions The free equilibrium and stability point for the COVID-19 model are investigated Also, the existence of a uniformly stable solution is proved © 2021 Tech Science Press All rights reserved

The pulse-frequency control systems are widely used in radar, space industry, for control of technological processes and robots and many other areas. Today, there are various approximate and accurate methods for the analysis and synthesis of pulse-frequency systems (PFS). However, the area of the practical application of the existed methods is mainly limited to single-variable systems. The classical methods provide the consideration of the initial structures of pulse-frequency systems as a whole. This article proposes the decomposition method for modeling and research pulse-frequency automatic control systems. The method is based on the mathematical apparatus of signal-flow graphs. We can use the method for analysis and synthesis of both single-variable and multivariable automatic control systems with pulse-frequency modulation

Although the impedance/admittance model of modular multilevel converter (MMC) considering internal harmonic is discussed extensively in the literature, few attentions have been focused on how to determine the number of harmonics to be included in the model. This article fills this gap by developing the MMC signal-flow graph (SFG), providing the analytical transfer function to quantitatively estimate the attenuation degree of MMC harmonics, so as to guide the model truncation. Besides, SFG offers an intuitive understanding on the mathematical characteristic of MMC, including the conjugate symmetry and the effect of phase reference on admittance, which helps to reduce the modeling calculation. Moreover, conversion formula of MMC multiple input multiple output and single input single output admittance is derived based on the truncated model to further simplify the stability analysis. The correctness of this article has been verified by simulation and experiment.

In this article, the optimal control for nonlinear SIRC model is studied in fractional order using the Caputo fractional derivative. Graph signal flow is given of the model and simulated by Simulink/Matlab which helps in discussing the topological structure of the model. Dynamics of the system versus certain parameters are studied via bifurcation diagrams, Lyapunov exponents and Poincare maps. The existence of a uniformly stable solution is proved after control. The obtained results display the activeness and suitability of the Mittag Generalized-Leffler function method (MGLFM). The approximate solution of the fractional order SIRC model using MGLFM is explained by giving the figures of solutions before and after control. Also, we plot the 3D relationships with different alpha (fractional order) which display the originality and suitability of the results.

In this study, a new CFOA-based PID controller circuit is designed and implemented by a systematic approach employing signal-flow graph theory which is a powerful tool for active circuit design. The proposed circuit has independently adjustable PID parameters ( $$K_\mathrm{P}$$ , $$K_\mathrm{I}$$ , $$K_\mathrm{D}$$ ) which are independently controlled by only one passive element. Having high input and low output impedances, it has the ability to cascade with other circuits. The proposed PID circuit is examined in a closed-loop control system with an example plant circuit. Mathematical analyses are performed and discussed. The PID controller is realized by using commercially available integrated circuit elements, and results are given to demonstrate the performance of the proposed PID controller.

In this work, a new design of continuous time current differencing buffered amplifier based low-pass, high-pass, band-pass, all-pass and notch fractional-order filters is reported. The design of proposed filters is based on the approximation of fractional-order filters by using an appropriate integer order transfer function. Signal flow graph approach is used for the realization of fractional-order filters of order (1 + α). The frequency responses of the proposed circuits are verified using MATLAB in conjunction with SPICE. The evaluation of the realized fractional-order filters are also performed through the AC analysis and corner analysis. Furthermore, stability and sensitivity investigations are also investigated. It is observed from the simulation results that the fractional-order filters are appropriate for IC implementation.

In this paper, Generalized Mittag-Leffler function method (GMLFM) and Sumudu transform method (STM) are applied to study and solve the fractional order smoking model, where the derivatives are defined in the Caputo fractional sense. The disease free equilibrium (DFE) and stability of equilibrium point are studied. Lyapunov exponents and Poincare map of the model are drawn to ensure the stability of the model. The obtained results show that the proposed methods are very effective and convenient. In addition, the model is presented by its signal flow graph and simulated using Matlab/Simulink.

We extend the signal flow calculus---a compositional account of the classical signal flow graph model of computation---to encompass affine behaviour, and furnish it with a novel operational semantics. The increased expressive power allows us to define a canonical notion of contextual equivalence, which we show to coincide with denotational equality. Finally, we characterise the realisable fragment of the calculus: those terms that express the computations of (affine) signal flow graphs., Comment: Accepted for publication in the proceedings of the 23rd International Conference on Foundations of Software Science and Computation Structures (FoSSaCS 2020)

Dynamic Networks are signal flow graphs explicitly partitioning structural information from dynamic or behavioral information in a dynamic system. This paper develops the mathematical foundations underlying this class of models, revealing structural roots for system concepts such as system behavior, well-posedness, causality, controllability, observability, minimality, abstraction, and realization. This theory of abstractions uses graph theory to systematically and rigorously relate LTI state space theory, developed by Kalman and emphasizing differential equations and linear algebra, to the operator theory of Weiner, emphasizing complex analysis, and Willem’s behavioral theory. New systems concepts, such as net effect, complete abstraction, and extraneous realization, are introduced, and we reveal conditions when acyclic abstractions exist for a given network, opening questions about their use in network reconstruction and other applications.

This paper presents a complex frequency domain approach to investigate the cluster tracking performance of linear heterogeneous multi-agent networks. Firstly, a designed graph matrix is given to eliminate the interaction influence between coupled subnetworks with different tracking signals. On this basis, the cluster tracking performance analysis problem is decomposed into two parts, i.e., stability analysis and steady-state performance analysis of multi-agent networks. Secondly, based on the network structure, a minimum separable subgraph set is proposed to transform the stability of the multi-agent network into the stability of the separable subnetworks. Further, a signal flow diagram is introduced to solve the stability of the separable subnetworks. Thirdly, in view of Final-value theorem, a necessary and sufficient condition is proposed for achieving the cluster tracking control for the closed-loop stable multi-agent network. This result provides a strong theoretical basis for the flexible design of controllers due to that it quantitatively reveals the inherent law of steady-state performance for multi-agent networks. Finally, an algorithm is established to calculate the steady-state error of a general directed multi-agent network. Some simulations are provided to demonstrate the effectiveness of the theoretical results.

This paper presents Signal Flow Graph (SFG) approach-based realization of Single Input Multiple Output (SIMO) filter topologies. A differentiator is placed as basic building block. A total of sixteen variants are derived from the proposed differentiator-based SFG. The Operational Trans-Resistance Amplifier (OTRA), an active block having low parasitics at input terminals, is used to validate the proposed methodology. All the derived filter structures use three OTRAs, six resistors and two capacitors. The filter performance parameters can be adjusted independently. The functional verification of the proposed method is done via SPICE simulations using 0.18 μm CMOS technology parameters from MOSIS.

Metamaterial (MM) slabs in close proximity can couple with one another. This coupling can modify the electromagnetic response of the overall MM structure involving individual MM resonators. The signal flow graph technique along with the ABCD parameters are applied to quantitatively and qualitatively examine this coupling from simulated/measured scattering parameters of cascade connection of closely or largely separated MM slabs. S-parameter measurements of a MM slab constructed by split-ring-resonators were carried out at X-band (8.2-12.4 GHz) to validate our theoretical analysis.

Based on the Transmission Line Method and Electromagnetic Topology theory, this paper proposes an analytical calculation method for solving the shielding effectiveness of irregular cavities. This method equates the apertures and the special-shaped structures into two-port networks, constructs the signal flow diagram based on the equivalent transmission line model, derives the scattering matrices, and solves the shielding effectiveness of the irregular cavity through the generalized BLT equation. Several typical structures are analyzed and the results are in good agreement with CST simulation when frequency exceeds the first resonant frequency of the cavity. The method can quickly obtain the shielding effectiveness and resonance characteristics of the irregular cavity with different structures, and the special-shaped structures are classified according to their features, which has guiding significance for the shielding effectiveness test of the irregular cavity.

Based on Mason’s signal flow graph analysis, an analytical model of the optical mode localization based on coupled ring resonators is established. The correctness of the theoretical model is proved by simulation. High sensitivity and common-mode rejection can be achieved by evaluating the modal power ratio from resonant peaks as sensing output. Based on the four-port structure, two output spectrum with mode localization (asymmetric mode splitting) and symmetric mode splitting allows the high-sensitivity sensing and dual-channel calibration to be carried out simultaneously, which can reduce the sensing errors. Monte-Carlo analysis showed that fabrication imperfection changes less than 6% of the performance in 90% cases, thus the construction of practical sensors is possible with appropriate tuning. The optical mode localized sensing has advantages in sensitivity, accuracy, anti-aliasing compared with conventional micro-mechanical mode localized sensor. Various types of high-sensitive sensor can be constructed through coupling parametric perturbation with measurands in different physical domains.

This letter analyzes a class of information freshness metrics for large IoT systems in which terminals employ slotted ALOHA to access a common channel. Considering a Gilbert- Elliot channel model, information freshness is evaluated through a penalty function that follows a power law of the time elapsed since the last received update, in contrast with the linear growth of age of information. By means of a signal flow graph analysis of Markov processes, we provide exact closed form expressions for the average penalty and for the peak penalty violation probability.

The paper presents kinematic analysis of a coupled and planetary gear with double bevel planetary wheels. The method is based on the concept of contour graphs assignment. Exemplary 1-dof and 2-dof epicyclic gear trains, and a complex planetary gear train are used to illustrate the application of this method. The well-known Willis’ formulas were utilized for comparisons. When designing planetary gears, it is difficult to determine all the parameters at the beginning of the design, in particular some parameters are selected on the basis of preliminary calculations. Graph methods allow to create a model of the analyzed gear, then determine the detailed ratios and algorithmically determine other quantities and their parameters. Isomorphism identification in the synthesis process and enumeration of 1- dof epicyclic gear train graphs can be found in cited bibliography. The signal flow graphs were utilized for choice of acceptable intervals for number of teeth. All together gives a spectrum of graph application for investigation of complex and coupled planetary gears.

Introduction In Chapter 2, a number of first-order active filters were realized along with the basic configuration of bilinear functions. Chapters 7 and 8 were devoted to the development of second-order filter sections using one or more than one OA (operational amplifier). However, as mentioned earlier, all filter specifications are not achievable only through second-order sections; higher-order filters become necessary. For the realization of higher-order filters, ladder simulation techniques through element (inductor/frequency dependent negative resistor: FDNR) substitution was discussed in Chapter 9. Ladder simulation using signal flow graph technique, which is better known as the operationally simulated method was also discussed in Chapter 9. The present chapter deals with another basic method of realizing higher-order filter sections known as the cascade design method . Section 10.2 will discuss the basics of cascade design and the conditions to be satisfied by first- or second-order sections in order that these could be used for cascading and obtaining higher-order filters. After taking up some examples of cascade design, the importance of cascade optimization will be discussed in Section 10.3 through an example section. While cascading a number of second-order sections, a proper combination of poles and zeroes (Section 10.3.1), correct assignment of gain for each section (Section 10.3.2) and their proper order (Section 10.3.2) play a very crucial role. Hence, all the three aspects will be discussed in some details. It is well-known that due to the tolerance associated with passive elements as well as with the parameters of the active elements, and their possible variation due to the change in the biasing voltage and operating temperature, filter parameters gets deviated. Therefore, it is imperative to provide on-chip tuning of the parameters, especially the pole frequency ω o and pole- Q of the individual second-order sections used in the cascade. This chapter introduces the idea of filter parameter tuning. In Section 10.4, we get a better insight into the cascade design method of filter design. Cascade Design Basics To realize higher-order filters, cascading of second-order sections finds considerable favour in the eyes of a majority of filter designers; a first-order section is also cascaded in case of an oddorder filter. It will be shown later that such a technique has few advantages like the ability to tune filter parameters easily, and that it possess controlled tunability of the filter parameters with respect to the elements used.

Electromechanical devices consist mainly of rotor systems. Vibration is the result of the interaction of the elements of the rotor system and is largely determined by the accuracy of manufacturing elements at the production stage and defects arising in the process of operation. The main components of the rotor systems that affect vibration are bearings. To determine the technical condition of the bearings and the service life of the rotor system, it is necessary to accurately measure the unobservable vibrations of the rotor. The article describes the model of the channel for measuring the vibration of an electromechanical system, built using the apparatus of bond graphs. The transfer function is obtained by analyzing the signal flow graph. The systematic and random errors of vibration measurement are analyzed depending on the mass ratio between the system case and the vibration transducer for various sensor masses and attachment rigidity.

This study reviews and categorises different structures of switched Z-source networks. Generally, these structures are divided into two groups of basic switched Z-source networks and switched Z-source networks with the capability of high boost. Each of these groups is divided into several subgroups and different structures are introduced. For each subsection, the general power circuit is proposed and the extraction method from general power circuit for each structure is obtained. This study also provides a complete analysis of structures by using a conventional control method with two shoot-through and non-shoot-through modes. Small signal analysis for structures with a basic switched Z-source network is conducted and the general signal flow graph is extracted. A comprehensive analysis of all structures with a switched Z-source network is done and the tree diagram for the division of these structures is provided. Finally, different industrial applications and outlook of Z-source networks are introduced.

A new ripple base signal flow graph (R-SFG) modelling method was proposed to accurately model and analyse a family of switching DC–DC converter. The performance of some DC–DC converters such as single-inductor multi-output converters is dependent on inductor current ripples. This makes the conventional modelling methods cannot fully predict the overall behaviour of converter. From this family and in this study, a single-inductor dual-output (SIDO) boost/boost converter has been modelled based on proposed R-SFG method. The simplicity and systematic procedure presented in this work showed that the R-SFG could be a good alternative for modelling switching converter with complicated structures and with high inductor current ripple. In the new R-SFG method, the effects of inductor current ripple have been considered to develop the conventional signal flow graph modelling method. In this work, a comparative study between two modelling methods has been carried out in a SIDO converter. A step-by-step direct mathematical manipulation was used to calculate the DC–DC transfer function of SIDO converter. The experimental results were included to show the validity of the obtained models. The experimental results showed that the maximum R-SFG modelling error was about 5% over the wide range of inductor current ripple.

This brief presents a modified radix-4 fast Fourier transform (FFT) signal flow graph, whose input and output both are in natural order. Compared with the conventional radix-4 signal flow graph, it does not buffer the result of the last stage or execute the bit-reverse operation to generate the result, but generates the result directly in the last stage. Thus, the number of iterations is reduced by one. In order to realize the proposed memory-based FFT processor by using the modified radix-4 FFT signal flow graph, a conflict-free strategy and corresponding memory-addressing scheme is proposed. At last, the hardware implementation for the proposed FFT processor is proposed. Through the adoption of this method, FFT processor of arbitrary point conforming to the radix-4 algorithm can be implemented. Compared with the previous memory-based FFT processors, the proposed FFT processor has less processing time under similar or lower resource consumption.

In this paper, the signal flow graph technique and Mason gain formula are applied for extracting small signal model and transfer functions from control to output and from input to output. In order to investigate a rather complex system, a four quadrant dc-dc Luo converter known as a second generation and high order power electronic converter is chosen for modeling and analyzing purposes. This converter has received the least attention and its dynamic modeling and analysis is not reported in literature. To get rid of complex equations in modeling high order converters, signal flow graph method is applied to manipulate the equations. Hence, the small signal models for two converters in different states are derived in detail and the obtained models are used to achieve the frequency responses and do stability analysis. The whole paper shows that using the proposed method, derivation of small signal models for all states and frequency domain analysis can be easily carried out in detail. Keywords: Frequency response, Four quadrant Luo converter, Mason gain formula, Modeling, Signal flow graph

In this article we examine the dynamical properties of the fractional version of the snap system by means of chaotic attractor, existence, and uniqueness of the solution, symmetry, dissipativity, stagnation point analysis, Lyapunov dynamics, K.Y. dimension, bifurcation diagram, etc. Also, parallel systems to this system are synchronized in presence of uncertainties and external disturbances using triple compound combination anti-synchronization by two ways. Synchronization time is compared with some other works. Also the utilization of achieved synchronization is illustrated in secure transmission. By constructing the snap system’s signal flow graph and its real electronic circuit, some of its additional invariants are investigated.

In order to analyze the testability of hierarchical system, a testability modeling and analysis method based on multi signal flow graph model is proposed. In this method, the hierarchical structure model of hierarchical system is established by using the multi signal flow graph model. When the testability analysis is carried out, the correlation model method is used to analyze the testability of the top-level model. When the hierarchical module cannot be distinguished from other modules Finally, a hierarchical filter amplifier circuit is used to verify the proposed method. The experimental results show that the proposed method is effective for time-sharing The testability modeling and analysis of layered system is effective, which can make effective diagnosis strategy for layered system.

The performance of analog circuits is susceptible to various layout constraints, such as symmetry, matching, etc. Modern analog placement and routing algorithms usually need to take these constraints as input for high quality solutions, while manually annotating such constraints is tedious and requires design expertise. Thus, automatic constraint annotation from circuit netlists is a critical step to analog layout automation. In this work, we propose a graph learning based framework to learn the general rules for annotation of the symmetry constraints with path-based feature extraction and label filtering techniques. Experimental results on the open-source analog circuit designs demonstrate that our framework is able to achieve significantly higher accuracy compared with the most recent works on symmetry constraint detection leveraging graph similarity and signal flow analysis techniques. The framework is general and can be extended to other pairwise constraints as well.

The chapter considers the prospects and possibilities of using artificial neural networks based on the faceted principle of data storage when applied to solving the pattern recognition problem. Basic discrepancies of widely known neural networks with the direct signal flow and their biological prototypes are discussed. It is found out that the main reason for these discrepancies is the structural stability of neural network models in the course of training, i.e. their passivity. The analysis was made of the modern concept of a biological nervous system functioning as a process of selective transfer of excitement in the hierarchical structure consisting of the ensembles of the nervous cages with high selectivity. On the basis of this analysis, it is offered to give up the attempts of imitation of a biological nervous system functioning at the level of elementary neurons functioning processes and to pass to the reproduction of the information structure of data storage and processing. The concept of a multi alternative structure and functioning of complex systems based on the multileveled of structure, the division of functions, and modularity was chosen as the basic concept of this approach to the formation of neural networks. It is shown that this concept satisfies the transition to the faceted principle of data storage which allows creating alternative neural networks with a mutable structure. The example is given of the creation of a hierarchical faceted neural network for the recognition of geometrical objects.

An overview of the BLUESSS simulation package is presented. The package is object-oriented simulation tool, related to the C++ language. It has a clear process/event structure and supports inheritance of object properties. It is pointed out that BLUESSS supports both discrete-event and continuous models. It includes several source code generators for models given by ordinary differential equations, bond graphs, and signal flow graphs, as well as the discrete-event models of queuing, waiting lines, and manufacturing.

part : TC 1: Foundations of Computer Science; International audience; Signal flow graphs are combinatorial models for linear dynamical systems, playing a foundational role in control theory and engineering. In this survey, we overview a series of works [3, 10, 11, 13, 15–18, 31, 51, 63] that develop a compositional theory of these structures, and explore several striking insights emerging from this approach. In particular, the use of string diagrams, a categorical syntax for graphical models, allows to switch from the traditional combinatorial treatment of signal flow graphs to an algebraic characterisation. Within this framework, signal flow graphs may then be treated as a fully-fledged (visual) programming language, and equipped with important meta-theoretical properties, such as a complete axiomatisation and a full abstraction theorem. Moreover, the abstract viewpoint offered by string diagrams reveals that the same algebraic structures modelling linear dynamical systems may also be used to interpret diverse kinds of models, such as electrical circuits and Petri nets.In this respect, our work is a contribution to compositional network theory (see e.g., [1, 2, 4–6, 9, 12, 20, 21, 23, 24, 26, 28–30, 32, 37, 49, 59], ?), an emerging multidisciplinary research programme aiming at a uniform compositional study of different sorts of computational models.

Frequency response functions (FRFs) lie within the framework of the linear response theory in elastic structures. In FRFs, the inputs/outputs relationships are strictly determined, but there is no way of knowing how waves are propagated and converted from the input signals into the output signals. Thus, the wave propagation between the inputs and outputs cannot be clearly understood by the FRFs. In this study, we succeeded in visualizing the contents of these FRFs by decomposing them into geometric paths using a signal flow graph. Moreover, we succeeded in quantitatively evaluating the contributions of the paths to these FRFs. In terms of application, when the noise or vibration of industrial products is loud and unpleasant, this analytical methodology can help identify the cause behind such nuisance by using paths in contribution to FRFs. This methodology is expected to pave the way for taking quantitative countermeasures on the basis of analytical results.

The biological neural network signal flow is a complex process and difficult to interpret. The purpose of this study is to build a model of a simplified cerebellum neural network and investigate its working behavior in generating neuronal patterns. The model is constructed by referring to the neural anatomic structure of the mammal cerebellum and then simulated using Matlab Simulink software. The artificial neural network dimension is much smaller than the size of the real cerebellar neural network in mammal due to hardware simulation resource limitation. Thus, the utilization of extensivescale spiking neural networks is limited due to the grown of computational costs associated with propagating bio-realistic neural models. The parameters correlated with the neuron function also affect the biological plausibility of the spiking neural network. At the conclusion, we present the pattern generation of a cerebellum- like neural network and briefly explained why such patterns are generated.

Considering the characteristics of reusable liquid rocket engines, a hierarchical modeling method of Reusable liquid rocket engines testability based on multi-signal flow model is proposed. Then, a testability model at whole engine, subsystem and component level is constructed. Testability analysis, calculation of testability indices and design improvement are conducted to verify the feasibility of the proposed modeling method. This study may provide a feasible way to future design of reusable liquid rocket engines testability.

Placement is among the most critical steps in analog/mixed-signal (AMS) circuit layout synthesis. It implicitly determines the wiring topology and therefore has considerable impacts on post-layout parasitics and coupling. Existing analog placement techniques are mainly focusing on geometric constraints in analog building blocks. However, there yet lacks an effective way to consider the system-level signal flow for sensitive AMS circuits. Leveraging prior knowledge from schematics, we propose to consider the critical signal paths in automatic AMS placement and present an efficient framework. Experimental results demonstrate our proposed framework's efficiency and effectiveness with a 22.8% reduction in routed wire-length compared to state-of-the-art AMS placer and 10 dB improvement in the signal-to-noise-and-distortion ratio (SNDR) for an ADC.

The actual question in the area of circuit analysis and synthesis methods is the problem of sensitivity determination. The proposed approaches for sensitivity calculation are directed to the obtaining of a symbolic form and to avoiding the direct differentiation by using a signal-flow graph. Interesting results in this topic are based on Mason's graphs, and Coates' graphs. This paper presents the comparison of some methods to finding the sensitivity to transfer branch: previously published algebraic method and proposed SFG method.

This article presents a design of high-order Elliptic ladder high-pass filter based on differentiators and integrator approach. Since the design of general Elliptic high-pass filter can be realized with high complexity, moreover the high-pass filter held very complicated design. The differentiators and integrator are deployed for synthesis high-pass filter from its Signal Flow Graph (SFG). The Elliptic RLC high-pass filter is transformed by using the original Elliptic RLC low-pass filter. The SFG is straightforward analyzed from the Elliptic RLC high-pass filter prototype. The SFG describes three differentiators and one integrator. The operational transconductance amplifiers (OTA) and grounded capacitors are preferred to implement the differentiators and integrator. The proposed filter contains only 7 OTAs with 4 grounded capacitors. The frequency responses can be varied between 100kHz and 10MHz by manipulating the bias current (I B ) from 1μA to 100μA. The performances and the capability are carried out by using PSpice simulation which agreed to the theory.

The six-port reflectometers are used for measuring the parameter of microwave signals and tracts in microwave drying and heating plant, telecommunication, radiolocation, medicine. One of the six-port reflectometers type is multiprobe microwave multimeter which microwave block is tract section with sensors. The problem considered in the report is sensors re-reflection in the microwave block of multiprobe multimeter. Earlier research using a signal flow graphs model not satisfy because ambiguity of the result. So we try another mathematical model. The proposed model of sensor re-reflection uses method of induced emfs and dyadic Green functions. The novelty of proposed approach is to determine the parameters of the scattering matrix of multiprobe microwave multimeter through the impedance matrix, and find the impedance matrix by the method of induced emfs