Polyphase Systems Research Articles

English

A chemostat cell culture is a polyphasic dispersed system. Three models using net transport and metabolization (T/M) kinetics of hyperbolic form have been described. The first uses only one metabolic pathway and has been studied under various conditions. The second uses two metabolic pathways, with either high or low affinity for the substrate. The third adds excretion of fermentative products to the pathways in model two. Examining the steady states at various dilution rates (D) reveals a critical value (threshold value, Dc), at which the substrate can abruptly invade the cells. If the substrate or its derivatives are active, this abrupt concentration increase may act as a signal at particular growth rates. The second model has been used to study cases where the extracellular compound is a limiting substrate. When part of the substrate was excreted in the form of metabolites, there was a sharp transition between the anabolic and excretion pathways. The excretion pathways are abruptly activated above a critical growth rate. In all cases, the “threshold effects” were related to global and intrinsic characteristics of the culture, represented by the formula . This result may be of practical importance for designing and optimizing biotechnological processes in continuous cultures. The derived model has been effectively used to describe the Crabtree effect in Saccharomyces cerevisiae, which likely implies at least two input pathways of the substrate. The weak affinity pathway is responsible for the respiratory-reproductive transition and leads to the excretion of the fermentation products, including ethanol in yeast and lactate for certain cancers. Key words: Threshold, metabolic switch, Crabtree effect, substrate transport, respiro-fermentative transition.

Effect of banana powder and butter on the formation of the crystalline phase of sugar fondant

Taking into consideration modern requirements to technological characteristics of decorative semi-finished products, micronutrient composition, we developed the formulation for the innovative confectionery semi-finished product, which is based on sugar fondant with addition of the mixture of butter, banana powder and the surface-active substance (citric acid ester, mono-diglycerides – SAS). It is universal and is designed for the production of a wide range of decorative semi-finished products (creams, fillings, icing, etc.).We conducted the study of the influence of the mixture of butter, banana powder and surfactant on thermo-physical properties and the structure of the confectionery semi-finished product for confectionery decoration.The aim of this research was to study the influence of the selected ingredients on the process of formation of the crystal phase of sugar fondant, which is the basis for the confectionery semi-finished product.Results of the study revealed that during the formation of the crystal phase of the semi-finished product, the existence of the banana powder components leads to differentiation of carbohydrates of sugar fondant by melting temperature. This suggests that recrystallization processes flow less intensively compared to the control sample during the storage of the enriched fondant cream.The addition of SAS helps obtain a homogeneous polyphase system, which is proved by the homogeneous elastic structure. Micro-structural research showed that fondant crystals and vegetable powder particles are surrounded by fat phase of butter and swollen powder particles do not form groups.Results of the micro-structural analysis and of the differential scanning calorimetry made it possible to propose the mechanism of interaction of banana powder particles with fat phase and the oversaturated solution of sucrose.The obtained results explain aggregation stability and thermal stability of the universal confectionery semi-finished product at multiple thermal and mechanical influence, which is of technological importance.

Integrated circuit for real-time poly-phase power quality monitoring

Low power quality may cause serious problems in electricity networks, among them there are: reduction of equipment lifetime; false activation of protection devices; and increase in electrical and thermal losses. Considering this, it is very important to monitor electrical power quality of an industrial facility. This paper describes the architecture of an application-specific integrated circuit IP-core for power quality measurements. The main focus are the digital signal processing modules, which are designed based on IEC standards. The proposed Integrated Circuit, which uses TowerJazz 180 nm CMOS technology, comprises seven measurement channels for poly-phase systems and generates high precision estimation for power quality parameters. Experimental and simulated results are used to validate the proposed system.

Application of the Conservative Power Theory Current Decomposition in a Load Power-Sharing Strategy Among Distributed Energy Resources

The conservative power theory (CPT) is a time-domain theory applicable to any periodic signal single- or polyphase system with or without a neutral conductor. The principle operation is the orthogonal decomposition of electrical variables, resulting in electrical quantities with physical meaning. An important feature of the CPT is the current decomposition. It consists of decomposing any current into five parts. The label of these parts is active current, reactive current, scattered active current, scattered reactive current, and generated current. This paper proposes the application of the current decomposition of the CPT in distributed energy resources (DERs). A supervisory controller (SC) uses the current decomposition in a load power-sharing strategy. The combination of these two issues is the main contribution of this paper. Moreover, the proposal of this paper is more attractive than the conventional droop strategy since the DERs follow their current reference in a current-controlled mode, making the load sharing faster, more reliable, and more accurate. A clear understanding of how the CPT decomposes load currents into its parts is presented, as well as the drawback found in droop strategy when dealing with load power sharing. Later, the SC load power-sharing strategy is described, indicating that the proposal of this paper makes an SC to have a broad option when managing a smart grid with dispatchable DERs. A case study with experimental results shows the efficacy of applying current decomposition of the CPT in load power-sharing strategies.

Six-Phase Bidirectional Rectifier: Modelling, Control and Experimental Results in αβ Reference Frame

Poly-phase machines have been used for many years in motor drives and more recently in wind power generation. In wind generation the most common poly-phase system is the six-phase, which consists of a dual three-phase system, shifted by 30 electrical degrees from each other and with no neutral connection. Typically, this system employs a twelve-pulse diode rectifier to convert AC to DC voltages. Better results can be achieved employing an active rectifier, since it can provide lower distortion in generator currents and regulated output voltage. However, the dynamic and stationary model of this converter are not reported in the literature, taking that into account, this paper proposes a six-phase active rectifier topology for a dual three-phase system. A stationary frame reference for six-phase system is applied to obtain the converter dynamic model in the $\alpha\beta$ coordinates and thus a control strategy is proposed in this frame reference. The proposed topology and control strategy were experimentally verified with a 12 kW prototype. The results were appropriated, providing a regulated output voltage, an input current with reduced harmonic distortion and thus high power factor.

Power definitions for polyphase systems based on Fortescue's symmetrical components

Power definitions for polyphase power systems with non-sinusoidal and unbalanced voltages and currents are considered in this paper. Based on application of Fortescue's transformation to time-varying voltage and current space vectors, a new approach to power definitions is proposed. Definitions of the complex, apparent, active and non-active powers in terms of the symmetrical components have been proposed. The analysis related to the influence of zero-sequence voltages to power quantities has been performed. The symmetrical components provide calculation of powers by omitting erroneous contribution of the zero-sequence voltages. A significant property of the proposed power definitions in terms of the symmetrical components is that they are invariant to the choice of the voltage reference. Application of the proposed power definitions in terms of the symmetrical components has been demonstrated by the examples of three-phase three-wire and four-wire systems.

Analog modeling of fault asperity kinematics using a modified squeeze-box design and wax media

Fault movement is strongly influenced by the physical characteristics of the fault surfaces. Fault surfaces are generally nonplanar and have a certain amount of roughness to them, which manifests as fault asperities. In order for a fault to continue moving along its preexisting surface, the asperities must either move past each other, which involves moving a large volume of rock around these obstacles, or create new fractures that “decapitate” and pulverize these asperities, ultimately leading to a smoother fault surface. We explore a new way to investigate fault asperity kinematics using a squeeze-box analog deformation rig. The more typical and classic squeeze-box model uses sand and/or clay to demonstrate fault and fold deformations. We have designed and built a new analog modeling rig that uses a dual-wax analog material. One constituent is white spherical wax particles that have been embedded in a lower-melting-temperature black matrix wax. Deformation of the analog material is facilitated by the addition of heating elements lining the underside and exterior walls of the squeeze-box reservoir. An aluminum asperity is secured to the floor of the reservoir. Additional overburden is simulated with lead shot that rests on the top surface of the wax block during deformation. Once the experiment is completed, the wax block can be finely sectioned, polished, and scanned in preparation for analysis. Here, we present the first results from this new deformation rig where we were able to generate realistic looking deformation features at different strain rate conditions. The results of this type of modeling provide unique information about fault localization, the role of fluids, and fault asperity kinematics in a polyphase system for a variety of physical conditions within the earth’s crust. These conditions are difficult to model with other analog or numerical techniques or to derive from field or seismic investigations.

Influence of Fine Fraction on Shear Parameters and Consolidation Behavior of Tropical Residual Soil

Objectives: Tropical residual soils are widely available in the southern part of India and the construction in this type of soils more challenge issue to the geotechnical engineers to design the structure in the settlement criteria. Analysis: Tropical residual soils are in general are regarded as multi component, polyphase, and particulate system with compositional and/ or structural discontinuities. Both index and engineering properties of natural soils primarily depend on mineralogy and percentage of fine fraction. Findings: In this paper, eight soil samples are considered for to obtain the influence of the fine fraction on shear parameters and consolidation behavior of tropical residual soils in Tirupati region. Shear strength tests and one-dimensional compression tests have been conducted apart from the classification and identification tests. Application/ Improvement: Based on the experimental test results and analysis, it has been found that the percentage fine fraction has a greater significant influence on engineering properties like cohesion, angle of internal friction and compression index of tropical residual soils.

Preparation, characterization and sintering of yttrium-doped ThO2 for oxygen sensors applications

The preparation of Th1-xYxO2-x/2 ceramics, to be used as electrolyte in oxygen sensors for sodium-cooled nuclear reactors, was successfully undertaken from oxalate precursors. Such method was found to provide quantitative precipitation of the cations into (Th,Y)(C2O4)2·2H2O solid solutions up to x = 0.15 while a polyphase system was obtained for x = 0.22. The corresponding oxides were obtained through heat treatment in air at 500 °C and characterized by the means of PXRD, SEM and statistical X-EDS measurements. The conditions for the densification of Th1-xYxO2-x/2 ceramics were further determined by dilatometry (T = 1575 °C, t = 8 h) resulting in densification rates up to 99%. Finally, a first estimation of the electrical properties of the solids was undertaken by impedance spectroscopy. Electrical conductivity was found to increase linearly with the incorporation of Y3+ content while the associated values of activation energy decreased, with a minimum value of 1.1 eV for Th0.85Y0.15O1.925.

Reducing the Spurious Oscillations in the Lumped Parameters Model using Low-Pass Filter

The second-order differential equations that describe the polyphase transmission line are difficult to solve due to the mutual coupling among them and the fact that the parameters are distributed along their length. A method for the analysis of polyphase systems is the technique that decouples their phases. Thus, a system that has n phases coupled can be represented by n decoupled single-phase systems which are mathematically identical to the original system. Once obtained the n-phase circuit, it's possible to calculate the voltages and currents at any point on the line using computational methods. The Universal Line Model (ULM) transforms the differential equations in the time domain to algebraic equations in the frequency domain, solve them and obtain the solution in the frequency domain using the inverse Laplace transform. This work will analyze the method of modal decomposition in a three-phase transmission line for the evaluation of voltages and currents of the line during the energizing process.

A Contactless Slipring System Based on Axially Traveling Magnetic Field

It is a preferable method to transfer power wirelessly using contactless slipring systems for rotary applications. The current single or multiple-unit single-phase systems often have limited power transfer capability, so they may not be able to meet the load requirements. This paper presents a contactless slipring system based on axially traveling magnetic field that can achieve a high output power level. A new index termed mutual inductance per pole is introduced to simplify the analysis of the mutually coupled poly-phase system to a single-phase basis. Both simulation and practical results have shown that the proposed system can transfer 2.7 times more power than a multiple-unit (six individual units) single-phase system with the same amount of ferrite and copper materials at higher power transfer efficiency. It has been found that the new system can achieve about 255.6 W of maximum power at 97% efficiency, compared to 68.4 W at 90% of a multiple-unit (six individual units) single-phase system.

Flotation of blue water

Flotation of ions and molecules represents a promising method of separating components from solution, or in our case, gelled copper salt from blue water. The method of flotation of ions and molecules is basically the flotation extraction process which produces different concentration gradients of multicomponent condensed phase system. Different concentration gradients in the flotation extraction are due to the driving forces of participating molecules driven by molecular interactions. Multicomponent condensed phase system, i.e. flotation pulp, consists of water molecules of solute, and a suitable reagent which has the role of connection the liquid and gaseous phases dispersed in a biphasic system. Such a system leads to the interaction of solute with reagent to the formation of coagulated component in water as solvent. Separation in the polyphased system is in accordance with the Van't Hoff equation, and spontaneously occurs in two-phase systems like gaseous-fluid, such as the system of flotation pulp. Using the osmotic pressure in a column flotation machine comes to separation of flotation pulp into heavy and light phase. This allows the water molecules to form their natural distances which are only valid for molecules of pure water or heavy phase. Also, the solute forms its light phase, copper - surfactant salt as insoluble product. For some polyphase systems such as colloidal systems like in the flotation process are sufficient atmospheric pressure conditions, and for others solutions should be applied overpressure while being aerated. This paper presents the results of research the flotation extraction of blue water, i.e. copper solution content of 0.2 g/l. It is concluded from results that there is a possibility of purifying the blue water from the copper mine tailing dump using the flotation extraction technology.

Through-Hole Contactless Slipring System Based on Rotating Magnetic Field for Rotary Applications

Contactless slipring system based on inductive power transfer is a preferable alternative to mechanical slipring assemblies. They are designed to deliver required output power to a rotary shaft without direct electrical contacts. The current single or multiple-unit through-hole single-phase systems often have limited power transfer capability within a confined physical space; thus, they may not be able to meet the load requirement for certain applications such as wind power pitch control. This paper presents an integrated polyphase through-hole contactless slipring system by generating a rotating primary magnetic field coupled with balanced power pickups at the secondary side with zero mechanical driving torque on the shaft. A new index termed “mutual inductance per pole” is introduced to simplify the analysis of the mutually coupled polyphase system to a single-phase basis. Simulation and practical experiments have demonstrated that, with the same physical size, the proposed contactless slipring setup can transfer 55% more power compared with the existing single-phase counterpart.

Computational analysis of nonlinear creep of polyphase aggregates: Influence of phase morphology

AbstractThe constitutive laws of polyphase aggregates dominantly depend on the operative deformation mechanisms, phase morphology and modes, and environmental conditions. Each of these factors has the potential to dramatically affect bulk mechanical properties as well as the local stress and strain rate distributions. To focus on the effects of phase morphology, we have developed a rigorous multiscale approach based on asymptotic expansion homogenization. The proposed methodology has two fundamental goals: (1) accurately predict bulk behavior in aggregates by explicitly taking into account phase morphology and (2) calculate detailed distributions of strain rates, stresses, and viscosities in heterogeneous materials. The methodology is able to consider general nonlinear phase constitutive laws that relate strain rates to stresses, temperature, and other factors such as water fugacity and grain size. We demonstrate the approach by analyzing power law creep of computer‐generated and natural polyphase systems and benchmarking the results against analytical solutions. As an outcome of this analysis, we find that the approximation of an aggregate as a power law material is reasonable for isotropic, homogeneous phase distributions but breaks down significantly with high degrees of phase organization. We also present distributions in strain rate, stress, and viscosity for different applied loading conditions. Results exhibit areas of high internal stresses and substantial localization. We describe and provide a freely available software package supporting these calculations.

Tesla: Inventor of the Electrical Age by W. Bernard Carlson (review)

Reviewed by: Tesla: Inventor of the Electrical Age by W. Bernard Carlson Michael Brian Schiffer (bio) Tesla: Inventor of the Electrical Age. By W. Bernard Carlson. (Princeton, N.J.: Princeton University Press, 2013. Pp. 520. $29.95 cloth) This book is the culmination of W. Bernard Carlson’s fifteen years of research on the life and inventions of Nikola Tesla and on the changing socioeconomic context in which he worked. Carlson’s articles and talks have teased electrical historians, raising our expectations that the final product will be special. And it is. Tesla is a tour de force of sound scholarship and cogent analysis that brings to life one of the most eccentric and enigmatic characters in the history of technology. Tesla is one person in technological history who has not been ignored, for much has been written about him during his lifetime and since. Not only are there many biographies, but he has also become a cult figure in popular culture, even featured in a recent movie. Accordingly, the book’s potential audience reaches well beyond scholars of electrical history, an expectation reflected in the very modest price. Having mined the primary sources in the United States, England, and Serbia to an unprecedented depth and breadth, Carlson unearthed much new information about Tesla’s life, inventions, and his relationships with potential and actual financial supporters, including John Jacob Astor and J. P. Morgan. Previous Tesla biographies have been “technology lite,” but Carlson exhaustively treats the inventions: how they worked or would supposedly work, supplemented by copious drawings and photographs of high quality. The book discusses Tesla’s successes and failures—in [End Page 522] invention and in raising money—and offers explanations for both. Conceived early in his career, Tesla’s most significant inventions were the AC motor and polyphase system of transmission, which were commercialized by Westinghouse. The Tesla technologies enabled the firm to surpass Edison’s DC system, which eventually forced Edison out of the electric-power industry. Readers who find the technical details off-putting may want to skip these descriptions; the narrative can still be followed. I did find tedious the surfeit of very long quotations that merely inflict on the reader the discourse styles of a century ago without necessarily advancing the story. What gives Tesla’s life and work an unexpected unity, and the narrative coherence and continuity, is Carlson’s analysis of Tesla’s mode of invention: the creation in his mind’s eye of an ideal—the vision of technology that might be. Carlson shows that this kind of vision or ideal spanned all of Tesla’s inventions and also affected the way he structured experiments, exploited the media, and approached donors. Carlson’s notion of the ideal helps to clarify many puzzling aspects of Tesla’s behavior. Of course no ideal was fully formed at birth and some were scientifically impossible; moreover, the amount of research and development needed to realize any of them, including the AC motor, was daunting. Tesla’s largest failing was, as Carlson points out so well, in the single-minded pursuit of his ideals, such as universal transmission of power through the earth, to the neglect of fully developing and bringing to market more mundane inventions that might have furnished steady support. Tesla’s strategy contrasted with Edison’s; the latter would commercialize anything, even a talking doll, to garner income for his invention factory. Historians of technology and science owe Carlson a debt of gratitude for undertaking this challenging project and bringing it to such a successful conclusion. His painstaking construction of Tesla—the man, his inventions, and societal context—will remain the definitive work for many decades. [End Page 523] Michael Brian Schiffer MICHAEL BRIAN SCHIFFER is the Fred A. Riecker Distinguished Professor of Anthropology at the University of Arizona. His recent books include Studying Technological Change: A Behavioral Approach (2011) and The Archaeology of Science: Studying the Creation of Useful Knowledge (2013). Copyright © 2014 Kentucky Historical Society

Multi-Way and Poly-Phase Aligned Feed-Forward Differential Phase Shifters

Traditional two-way passive differential phase shifters (DPSs) are comprised of a reference line and a delay line. To realize a passive multi-way poly-phase DPS, a single reference line is not possible and a cascaded network becomes necessary. This results in both a cumbersome and complex structure, with large phase error that propagates through the network. A novel phase shifter is presented here that allows multi-way and poly-phase differential phase shift using just one common reference line. This phase shifter is constructed using a newly proposed phase-shift component in all element designs, where each element maintains a constant phase shift with adjacent elements. This characteristic for DPSs offers a simple solution to multi-way poly-phase systems, such as those found in phased arrays. To validate the proposed concept, phase shifters are designed as a group of five different elements operating at 2 GHz, with each maintaining a constant phase shift (45 $^{\circ}$ , 90 $^{\circ}$ , 135 $^{\circ}$ , 180 $^{\circ}$ ) compared to a reference element. Measured results agree well with the theoretical analysis. Over a 40% bandwidth the achieved phase shifts are ${\hbox{45}}^{\circ} {\pm} {\hbox{0.9}}^{\circ},$ ${\hbox{90}}^{\circ} {\pm} {\hbox{1.5}}^{\circ},$ ${\hbox{135}}^{\circ} {\pm} {\hbox{4}}^{\circ}$ , and ${\hbox{180}}^{\circ} {\pm} {\hbox{4.2}}^{\circ}$ , while amplitude imbalances are all less than 0.25 dB.

Using Universal Line Model (ULM) for Simulating Electromagnetic Transients in Three-Phase Transmission Lines

The second-order differential equations that describe the polyphase transmission line are difficult to solve due to the mutual coupling among them and the fact that the parameters are distributed along their length. A method for the analysis of polyphase systems is the technique that decouples their phases. Thus, a system that has n phases coupled can be represented by n decoupled single-phase systems which are mathematically identical to the original system. Once obtained the n-phase circuit, it's possible to calculate the voltages and currents at any point on the line using computational methods. The Universal Line Model (ULM) transforms the differential equations in the time domain to algebraic equations in the frequency domain, solve them and obtain the solution in the frequency domain using the inverse Laplace transform. This work will analyze the method of modal decomposition in a three-phase transmission line for the evaluation of voltages and currents of the line during the energizing process.

The Alternating Evolution of DC Power Transmission [Historical

After more than one century of evolution of alternating current (ac) and thanks to the competitive costs of alternators and transformers, today a great majority of electricity is produced, transmitted, and distributed worldwide by means of ac polyphase systems [1], [2]. Nevertheless, about 200 high-voltage direct current (HVDC) systems are spread over the world to provide services where they are more convenient than ac systems. Moreover, the number of direct current (dc) systems is increasing, primarily due to the expansion of intermitted renewable energy sources and the inherent need to provide them with storage capabilities and, secondly, because of the enhanced competitiveness of solid-state converters. These two aspects can merge to form visionary concepts such as the energy hub, which fosters medium-voltage direct current transmission.

Approaching the seismogenic source of the Calabria 8 September 1905 earthquake: New geophysical, geological and biochemical data from the S. Eufemia Gulf (S Italy)

Recognizing the seismogenic source of major historical earthquakes, particularly when these have occurred offshore, is a long-standing issue across the Mediterranean Sea and elsewhere. The destructive earthquake (M ~ 7) that struck western Calabria (southern Italy) on the night of 8 September 1905 is one such case having various authors proposed a seismogenic source, with apparently diverse hypotheses and without achieving a unique solution. To gain novel insight into the crustal volume where the 1905 earthquake took place and to seek a more robust solution for the seismogenic source associated with this destructive event, we carried out a well-targeted multidisciplinary survey within the Gulf of S. Eufemia (SE Tyrrhenian Sea), collecting geophysical data, oceanographic measurements, and biological, chemical and sedimentary samples. We identified three main tectonic features affecting the sedimentary basin in the Gulf of S. Eufemia: 1) a NE-SW striking, ca. 13-km-long, normal fault, here named S. Eufemia Fault; 2) a WNW-striking polyphased fault system; and 3) a likely E-W trending lineament. Among these, the normal fault shows evidence of activity witnessed by the deformed recent sediments and by its seabed rupture along which, locally, fluid leakage occurs. Features in agreement with the anomalous distribution of prokaryotic abundance and biopolymeric C content, resulted from the shallow sediment analyses. The numerous seismogenic sources proposed in the literature during the past 15 yr make up a composite framework of this sector of western Calabria, that we tested against a) the geological evidence from the newly acquired dataset, and b) the regional seismotectonic models. Such assessment allows us to propose the NE-SW striking normal fault as the most probable candidate for the seismogenic source of the 1905 earthquake. Reappraising a major historical earthquake as the 1905 one enhances the seismotectonic picture of western Calabria. Further understanding of the region and better constraining the location of the seismogenic source may be attained through integrated interpretation of our data together with a) on-land field evidence, and b) seismological modeling.

Purification of uranothorite solid solutions from polyphase systems

The mineral coffinite, nominally USiO4, and associated Th1−xUxSiO4 uranothorite solid solutions are of great interest from a geochemical point of view and in the case of the direct storage of spent nuclear fuels. Nevertheless, they clearly exhibit a lack in the evaluation of their thermodynamic data, mainly because of the difficulties linked with their preparation as pure phases. This paper thus presents physical and chemical methods aiming to separate uranothorite solid solutions from oxide additional phases such as amorphous SiO2 and nanometric crystallized Th1−yUyO2.The repetition of centrifugation steps envisaged in first place was rapidly dropped due to poor recovery yields, to the benefit of successive washings in acid then basic media. Under both static and dynamic flow rates (i.e. low or high rate of leachate renewal), ICP-AES (Inductively Coupled Plasma – Atomic Emission Spectroscopy) analyses revealed the systematic elimination of Th1−yUyO2 in acid media and of SiO2 in basic media. Nevertheless, two successive steps were always needed to reach pure samples. On this basis, a first cycle performed in static conditions was chosen to eliminate the major part of the accessory phases while a second one, in dynamic conditions, allowed the elimination of the residual impurities. The complete purification of the samples was finally evidenced through the characterization of the samples by the means of PXRD (Powder X-Ray Diffraction), SEM (Scanning Electron Microscopy) observations and X-EDS (X-Ray Energy Dispersive Spectroscopy) analyses.