Closed-loop Diagram Research Articles

Highly Sensitive Micromachined Thermopile Infrared Sensor System With Chopper Operational Amplifier

A micromachined thermopile infrared sensor is designed and optimized with high detective sensitivity in the article. A matched chopper operational amplifier with good linearity is implemented for signal processing. Optimizations of the sensor’s structure are proposed by the adjustment of the length of the thermocouple pairs and the filling of the back-etched cavity based on the adopted thermocouple materials. A passivation layer is implemented to minimize the flicker noise of the sensor. Based on the requirement of the optimized thermopile sensor system, both the flicker noise and the low-frequency noise of the system are suppressed for achieving high sensitivity. The chopper operational amplifier circuit with a single-ended closed-loop diagram is specifically designed for signal amplification and noise suppression. The fabricated device shows improved characterizations, with the responsivity of 182.72 V/W, detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.47\times 10^{{8}}$ </tex-math></inline-formula> cmHz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> /W, time constant of 10 ms, and total resistance of 270 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> . The sensitivity of the designed system, including the sensor and the amplifier, is about 15 mV/°C, when the gain is 40 dB and the sensor-target distance is 3 cm. The system shows wide applications in the fields of noncontact temperature measurement and other special applications.

A solution for the chicken and egg paradox in taxi e-hailing platforms: some evidence from the MyTaxi – FreeNow case

PurposeThis study aims to explore the chicken and egg paradox in the taxi e-hailing business contributing to define a condition of system emergence. This paradox is a meaningful one as these platforms represent a system where the passengers systems have no reason to participate if they have no drivers-systems to answer their call, but, at the same time, the platform is not useful to the drivers-system if there are no passengers-systems using the platform.Design/methodology/approachTo understand how this paradox has been dealt with in the taxi e-hailing business, this study focused on a case study on a best practice in Italian taxi e-hailing industry (i.e. MyTaxi/FreeNow). This study wants to comprehend which actions have been implemented to solve this paradox and has tried to identify the interconnections between the various strategies to create a closed loop diagram for further testing.FindingsThis study has found that the company did not choose a single “subsystem” (passenger or driver), but it has stimulated the creation of several mutually reinforcing motivation for have both subsystems interact to help the company grow.Originality/valueTo the best of the authors’ knowledge, this paradox has never been studied using the complex adaptive system perspective. This perspective is particularly useful in this case and in the similar ones with several different interacting factors that cannot be really studied without using a higher order perspective.

Systems dynamic modeling to analyze the systemic viability of the combined use of regenerative converters and energy storage in a UPS manufacturer

Abstract The industrial sector is the largest consumer of energy in the world. In this sector, non-energy intensive companies have untapped energy efficiency potential, such as Uninterruptible Power Supply (UPS) manufacturers. Among the companies classified as non-energy-intensive, the International Energy Agency estimates that the untapped potential for energy efficiency is equivalent to the energy consumption of Japan and South Korea per year, together. In the literature, this unexplored potential is termed as a gap in energy management. The approaches found in the literature present a scenario where most companies exclusively use financial indicators to evaluate investment in energy efficiency. However, even if the results of these indicators are financially attractive, the level of adoption of energy efficiency technologies remains low. Studies on this unexplored potential present technological vies and do not contemplate conjuncture risks and uncertainties that may influence in the adoption of a technological solution. This study aims to analyze through practical application the systemic viability of the combined use of regenerative converters and energy storage in a UPS manufacturer, as well as the use of renewable energy sources for self-generation. The variables were identified through an SLR and combined into a closed loop diagram. A conceptual model was structured by representing the dynamic relationships between variables and the behavior of these variables in decisions related to energy efficiency. Systems Dynamic Modeling (SDM) was used to simulate the behavior of systems in different scenarios considering the use of such technologies and possible variations in energy supply and demand. The estimated financial results of each scenario are presented taking into account the assumptions of a computational model. The results of the model suggest that the use of Regenerative Converter Pulse Width Modulation (RC-PWM) is positive in any context, presenting ROI higher than 4 in the Red Rate Flag scenarios. The option for Distributed Microgeneration (DMG) exerts a negative influence on financial attractiveness, especially in the option of trading energy in a free environment. Government incentives and Peak Shaving (PS) have had a low influence on financial attractiveness for over 10 years. The developed model can be used to visualize alternatives and make decisions in similar situations.

Aplikasi Filter KALMAN Pada Gerak Matra Longitudinal Pesawat Udara Boeing-747

Many of aircraft perfonnance became from the stability and control of flight test data analysis. This paper introduces the Kalman Filter analysis on the Boeing 747 data aircraft to knawn the output response if disturbance (as turbulence or noise) absence on the closed loop control system. We found the output response of the plant on algorithm Kalman Filter tend to the unstable conditions, but we don't knaw the response of the whole of closed loop diagram block control system of Boeing 747 aircraft.Keywords : aircraft control system, turbulence, Kalman Filter

Linked-Cluster Formulation of Electron-Hole Interaction Kernel in Real-Space Representation without Using Unoccupied States.

Electron-hole or quasiparticle representation plays a central role in describing electronic excitations in many-electron systems. For charge-neutral excitation, the electron-hole interaction kernel is the quantity of interest for calculating important excitation properties such as optical gap, optical spectra, electron-hole recombination, and electron-hole binding energies. The electron-hole interaction kernel can be formally derived from the density-density correlation function using both Green's function and time-dependent density functional theory (TDDFT) formalism. The accurate determination of the electron-hole interaction kernel remains a significant challenge for precise calculations of optical properties in the GW+BSE formalism. From the TDDFT perspective, the electron-hole interaction kernel has been viewed as a path to systematic development of frequency-dependent exchange-correlation functionals. Traditional approaches, such as many-body perturbation theory formalism, use unoccupied states (which are defined with respect to Fermi vacuum) to construct the electron-hole interaction kernel. However, the inclusion of unoccupied states has long been recognized as the leading computational bottleneck that limits the application of this approach for larger finite systems. In this work, an alternative derivation that avoids using unoccupied states to construct the electron-hole interaction kernel is presented. The central idea of this approach is to use explicitly correlated geminal functions for treating electron-electron correlation for both ground and excited state wave functions. Using this ansatz, it is derived using both diagrammatic and algebraic techniques that the electron-hole interaction kernel can be expressed only in terms of linked closed-loop diagrams. It is proved that the cancellation of unlinked diagrams is a consequence of linked-cluster theorem in real-space representation. The electron-hole interaction kernel derived in this work was used to calculate excitation energies in many-electron systems, and results were found to be in good agreement with the EOM-CCSD and GW+BSE methods. The numerical results highlight the effectiveness of the developed method for overcoming the computational barrier of accurately determining the electron-hole interaction kernel to applications of large finite systems such as quantum dots and nanorods.

Multiple reentrance and fractal phase boundaries in the Barker–Fock model

The Barker–Fock model, which addresses the issue of closed-loop phase diagrams in binary liquid mixtures, is shown to exhibit a wealth of interesting and rather unexpected physical phenomena. For example, renormalization-group studies indicate that in addition to the standard closed-loop diagrams seen in many binary liquid mixtures, the Barker–Fock model also yields multiple reentrance – perhaps of unlimited degree. In addition, one of the “phase boundaries” in the model is actually many separate phases mixed together to form a “fractal foam”. Behavior of this kind is interesting in its own right, and particularly so when the underlying model has direct physical relevance.

Van der Waals-like global phase diagrams

Since the first global phase diagram (1970) based upon the van der Waals equation of state for binary mixtures, there have been many newer ones, most recently that obtained by Yelash and Kraska (Ber. Bunsen-Ges. Phys. Chem., 1998, 102 213) by combining the Carnahan and Starling hard-sphere equation of state (J. Chem. Phys., 1969, 51, 635) with the original van der Waals attraction. Of the various such equations the results for the original van der Waals equation seem to be the least satisfactory in comparison with the experimental one-component fluid, and probably also for binary mixtures. However the Carnahan and Starling equation diverges only at a density much higher than close-packed. Sanchez (J. Chem. Phys., 1994, 101, 7003) has developed a new 4,3 Pade′ approximant that fits the virial coefficients of the hard sphere fluid and which diverges almost exactly at the close-packed density. If this expression is used in a van der Waals-like equation of state, it produces the same kind of closed-loop diagrams that Yelash and Kraska found, although over a substantially smaller area of the global phase diagram. Extensions of global phase diagrams to mixtures of molecules of different size (even to polymer systems) seem promising. In particular a simple equation of state with the Flory mixing equation and the Prigogine entropy parameter (TheMolecularTheoryofSolutions, North Holland, Amsterdam, 1957, ch. XVI) has led to a satisfactory account of tricritical points in hydrocarbon systems and should be investigated further.

Ternary hydrogen-bonded polymer solutions

Ternary-phase diagrams have been experimentally determined at 100°C for systems containing a series of poly(n-alkyl methacrylates), poly(ethylene oxide) (PEO), and a solvent [4-ethyl phenol (EPh)]. A totally miscible phase diagram is experimentally determined for the poly(methyl methacrylate)/PEO/EPh system, while a closed-loop diagram is observed for the analogous system containing poly(ethyl methacrylate). The corresponding phase diagrams of analogous mixtures containing poly(n-propyl methacrylate) or poly(n-butyl methacrylate) exhibit large heterogeneous areas. Theoretically predicted phase diagrams calculated using an association model developed in our laboratory are in general accord with these observations for ternary hydrogen-bonded polymer/polymer solutions. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1265–1271, 1998

A segmental interaction model for liquid-liquid equilibria correlation and prediction

A segmental interaction model containing the combinatorial, free-volume and energetic contributions to the excess Gibbs energy has been developed. The energetic contribution is based on the solution of segment concept. The model has been applied to the system poly(vinyl alcohol)/water between 330 and 420 K. The closed loop diagram, the lower and upper critical temperatures are correlated, using weakly temperature dependent UNIQUAC parameters.

Some new frontiers in chemical engineering thermodynamics

The history of chemical engineering thermodynamics shows that its main concern has been development and extension of concepts and ideas that physicists and physical chemists have proposed in only general terms. For example, van der Waals proposed his theory of fluids in 1873 but its use for chemical engineering came only later, starting in the nineteen twenties, when MIT's Warren K. Lewis (and others) developed the generalized charts that we find today in Perry's Handbook and in undergraduate chemical engineering textbooks. Extension of van der Waals' theory remains a topic of active interest as indicated, for example, in the recent mixing rules of Wong and Sandler which significantly improve calculation of high-pressure phase equilibria for practical process design. A variety of recent concepts from physics and physical chemistry is now under active development by chemical engineering researchers. Examples include the integral theory of fluids, polymer equilibria, molecular simulation with computers, density functional theory, the theory of electrolytes, fluctuation theory and the properties of fluids under unusual conditions such as the critical region and the metastable state which contains supercooled fluids at negative pressures. Some of these topics are discussed at this symposium. In every case, remarkable progress has been made toward achieving a better understanding of the properties of matter. That understanding, in turn, is useful not only for better design of chemical processes, but also for discovering novel techniques for making new chemical products. Following a short introduction of these new developments, attention is given to an outline of progress in three areas under active investigation at Berkeley. The first area concerns phase equilibria in mixtures of polymers with solvents or with other polymers; the main focus is directed at liquid-liquid equilibria which are more difficult to describe than vapor-liquid equilibria. The basis of this description is a perturbation theory where the reference system is an equation of state for athermal chains based on a Percus-Yevick solution of the Ornstein-Zernike equation coupled with the restraint of chain connectivity. This perturbation theory can describe experimental data for systems with upper or lower consolute temperatures, or both, including closed-loop diagrams. The second area concerns the properties of polyelectrolyte hydrogels in contact with aqueous solutions. Here emphasis is on experimental studies of swelling properties with semi-quantitative description based on polymer-network elasticity and Donnan equilibria. The third area concerns selective precipitation of globular proteins from aqueous solution using a salt as the precipitating agent. A theoretical description, similar to that used for colloidal solutions, requires fundamental experimental data (e.g. osmotic virial coefficients) obtained by light-scattering and osmometry. For a given solution of proteins, this theory can identify not only the conditions that are required for precipitation (pH, concentration and nature of salt) but also the expected degree of protein separation.

Blob calculation method for the liquid-liquid equilibria of polymer solutions

A blob calculation method of two-step renormalizadon for the asymmetric closed-loop diagrams of polymersolvent mixtures, was developed in terms of blobs of polymers and a local composition model. When the interactions between polymer chains and solvent take place, the blobs of having comparable sizes and molecular weights with solvent are approximated to have an independent action from the neighboring blobs in the chain but only restricted by the local concentrations. In applying two-step renormalization of the decorated UNIQUAC, the effective interaction energies of sites are first calculated from the microstates of decorated cells and second the excess free energies are evaluated by a local composition model. For poly(ethyleneglycol)-water mixtures of a closed-loop diagram, the proposed method fairly reproduced the size and shape of the region of phase separations with the blobs and their temperature-independent interaction parameters.

Properties of binary and ternary mixtures in the vicinities of double critical points

The properties of binary mixtures with closed-loop diagrams are discussed. The topology of the phase diagram of a binary mixture with hydrogen-bonding is obtained in the mean-field approximation of the lattice mixture Hamiltonian. The algebraic formalism of fluctuation isomorphism theory is put forward. Changes of the phase diagram caused by small quantities of a third component and the boundaries of validity of Landau theory are considered.

Decorated lattice model for closed-loop liquid-liquid equilibria and its applications to pyridine derivatives-water mixtures

A decorated lattice model, that consists of decorated bonds and orientational configurations of basis in the decorated cell is presented with the use of arbitrary directionality and temperature-independent interaction energies of sites to calculate the closed-loop coexistence curves of two equilibrated binary liquid phases. For mixtures containing hydrogen bonding compounds, the closed-loop diagrams obtained by the decorated lattice model are in fair agreement with experiments in the size, the shape and the flatness near the lower consolute solution temperatures, and fairly reproduced for pyridine derivatives-water mixtures. The directional interaction energies between unlike molecules, representing the strong interactions such as hydrogen bonding, are found responsible for the enhanced miscibility below the lower consolute solution temperatures. Finally, an application of the modified solution model, based on the effective interaction energies is demonstrated in the prediction of the closed-loop behaviors.

Resolving the discrete ambiguities in amplitude determinations

Necessary and sufficient criteria are presented for eliminating discrete ambiguities in the determination of reaction amplitudes from the bilinear products of amplitudes that are measured in experiments. In terms of a geometrical analog, the criteria require closed loop diagrams with an odd number of broken lines and an odd number of solid lines. The results are applicable to the general mathematical problems of solving a set of simultaneous bilinear algebraic equations for several unknowns.

Ternary systems of two interacting copolymers and a solvent

Closed loop diagrams were obtained with ternary systems containing two interacting copolymers (styrene-4-vinylpyridine / styrene-methacrylic acid or methyl methacrylate-4-vinylpyridine / methyl methacrylate-methacrylic acid) and a solvent (dioxane or chloroform). Viscosimetric interaction parameters were determined in both solvents. Higher interactions in chloroform than in dioxane were evidenced from greater positive Δ b23.

The Role of Operator Ordering in Quantum Field Theory

We study the role of operator ordering in quantum field theory. Operator ordering techniques discussed in our previous papers in the quantum mechanical context are extended to field theory. In this case formally infinite terms appear which must be given a meaning in the framework of some definite regularization scheme. Different orderings for the non­ commuting operators in the interaction Hamiltonian lead in general to different expressions for the Dyson-Wick expansion of the S-matrix, implying different Feynman rules. Different orderings correspond to different assignments for the initially undetermined values of the contractions occurring in closed-loop diagrams. Combining a special class of ordering schemes (u-ordering, a generalization of Weyl-ordering) with dimensional regularization leads to important simplifications, and in this case manipulations in which ordering complications are neglected may be justified. We use our methods to discuss gauge invariance in scalar electrodynamics, and the equivalence theorem for a reducible field theoretical model.

Canonical perturbation theory for nonlinear systems

We study perturbation expansions for quantum systems which are nonlinear in the sense that they may contain derivative couplings. The characteristic feature of these systems is the occurrence of products of noncommuting operators in the interaction Hamiltonian. In order to perform perturbation expansions in the Dyson-Wick manner it is in general necessary to order these operators according to some ordering scheme. We determine the most general scheme of this sort which allows a Dyson-Wick expansion with pair contractions. It involves a set $\ensuremath{\lambda}$ of three dimensionless ordering parameters which are related to the three $a$ priori undetermined equal-time contractions. Different $\ensuremath{\lambda}$-ordering schemes are related via an "equal-time" or "static" Wick theorem. In order to be able to contract operators which may be taken either at equal or at different times we introduce a time-ordering operation ${T}_{\ensuremath{\lambda}}$ which extends Dyson's time-ordering operation to equal times in a fashion dependent on the $\ensuremath{\lambda}$ ordering. We arrive at a "dynamic" Wick theorem which enables us to decompose the ${T}_{\ensuremath{\lambda}}$ product of a set of operators taken at arbitrary times into a sum of ${\ensuremath{\lambda}}^{\ensuremath{'}}$ products, where the most important case is that in which ${\ensuremath{\lambda}}^{\ensuremath{'}}$ represents normal ordering. Contrary to the usual Wick theorem ours works also in the case when two or more times coincide. Applying this theorem to the scattering operator expressed as a ${T}_{\ensuremath{\lambda}}$ product we obtain a class of Dyson-Wick expansions for nonlinear systems. Different expansions correspond to different choices of the ordering $\ensuremath{\lambda}$ and lead to different Feynman rules. The resulting diagrammatic technique for nonlinear systems is seen to have the following special features: (i) The interaction vertices include terms which arise from "quantum corrections," which are dependent on the ordering \ensuremath{\lambda} chosen for the noncommuting factors in the interaction Hamiltonian, and (ii) the equal-time contractions which occur in the closed-loop diagrams must be assigned corresponding $\ensuremath{\lambda}$-dependent values. In this way individual diagrams are $\ensuremath{\lambda}$ dependent. Nevertheless their sum is $\ensuremath{\lambda}$ independent, confirming the fact that the complete scattering operator is independent of the particular ordering chosen. The ordering multiplicity is also reflected in functional versions of the Dyson-Wick expansion. In the path-integral version this multiplicity lurks in the different possible discretization prescriptions. We discuss the relevance of our considerations to the question of the invariance of a quantum theory with respect to nonlinear point transformations. For the special case of a reducible system we present explicit calculations which show how this invariance is maintained in perturbation theory, for any ordering scheme belonging to the $\ensuremath{\lambda}$ class. In any particular scheme the invariance is ensured by a more or less intricate cancellation mechanism between the individual diagrams.

Mesonic Second-Class Currents in NuclearβDecay

Mesonic second-class currents have been studied in semileptonic $\ensuremath{\Delta}S=0$ transitions. The closed-loop diagram is finite for the $\ensuremath{\pi}\ensuremath{\omega}$ current, and its energy-dependent lepton part is dominant over the contributions from the two-body exchange diagram. The two-body exchange diagram has energy-dependent and energy-independent lepton parts, which are of comparable magnitude for the $A=12$ triplet. A general form of the mesonic current has also been considered. A general theory of second-class effects, including both mesonic currents and the induced-tensor term for $\mathrm{ft}$ values and $\frac{K}{{\ensuremath{\beta}}^{+}}$ ratios, has been discussed.

Nonlinear Lagrangian Transformations

In nonlinear Lagrangian schemes it is useful to transform the nonderivative pion-nucleon coupling into the derivative coupling. The effect of such a transformation on renormalization constants and closed-loop diagrams is investigated by direct calculations of the second-order nucleon and pion self-energies and the fourth-order nucleon-nucleon interaction with the inclusion of the renormalization diagrams. By carefully combining the contributions of appropriate diagrams, the complete equivalence of the nonderivative and derivative couplings is demonstrated.

Massive Yang-Mills fields

Two problems are studied in the paper: (i) the relation between Lagrangian and Feynman rules if the Lagrangian contains derivative couplings and/or vector meson fields and (ii) the behaviour of certain two closed loop diagrams in the perturbation theory of Yang-Mills fields. With respect to (i), using an extremely simple regularisation procedure, the canonical formalism is shown to give directly manifestly covariant Feynman rules. With respect to (ii), a certain set of Feynman rules involving ghost particles is known to be valid for diagrams of the Yang-Mills theory with no or one close loop. It is shown however that with the same set of rules the imaginary part of the two-loop self-energy diagrams receives a non-zero contribution of the unphysical three-ghost intermediate state.