Phase Balance Research Articles

Investigation of oxidant and antioxidant levels in patients with acute stroke in the emergency service

ObjectiveIn this study, we aimed to identify oxidative stress and the disruption in the oxidant-antioxidant balance in the acute phase of stroke and, therefore, to detect markers that will guide in the diagnosis and treatment of stroke. Materials and MethodsEighty-six patients who were admitted to Antalya Training and Research Hospital Emergency Department between June 2013 and December 2013 and who were diagnosed as having stroke were enrolled in this study. The control group consisted of 40 healthy volunteers. Blood samples collected from all participants were screened for albumin, ischemic modified albumin (IMA), IMA/albumin ratio (IMAR), total antioxidant status, total oxidant status (TOS), and oxidative stress index (OSI). ResultsSixty (70%) patients were diagnosed as having acute cerebral infarction (ACI) and 26 (30%) as having acute intracerebral hemorrhage (AIH). Statistically significant difference was found between AIH and control groups in terms of albumin, IMAR, TOS, OSI levels (P < .001, P < .001, P < .001, and P < .001, respectively). Statistically significant difference was found between ACI and control groups in terms of albumin, IMA, IMAR, TOS, and OSI levels (P < .001, P = .045, P < .001, P < .001, and P < .001, respectively). There was no difference between ACI patients with detected acute infarcts on cranial computed tomographic scans (n = 31) and ACI patients with normal cranial computed tomography results (n = 29) in terms of oxidant-antioxidant levels. There was a significant difference between patients admitted within 3 hours and healthy adults regarding the levels of IMAR, TOS, and OSI (P < .001, P < .001, and P < .001, respectively). Discussion and ConclusionIt was seen that oxidant-antioxidant balance was impaired in favor of oxidants in ACI and AIH. In addition, impairment in oxidant-antioxidant balance was found in the early stages of ACI. Therefore, these biomarkers can be used especially in the early diagnosis of thrombolytic therapy candidates in ACI.

Driving forces for chymosin partitioning on the macromolecule-salt aqueous two phase system

Aqueous two-phase systems (ATPSs) are strategic liquid–liquid systems for extraction and purification of compounds. However, only a few studies have evaluated the thermodynamic parameters that allow comprehension of the partition process of different molecules. Here, we investigated the chymosin (Chy) partitioning behavior in macromolecule+salt+water ATPSs by obtaining the partition coefficient (KChy), Gibbs free energy change of transference (ΔGtr,Chy∞), enthalpy change of transference (ΔHtr,Chy∞), and entropy change of transference (ΔStr,Chy∞), at infinite dilution, and their dependence on the ATPS properties. Chy transfer from the bottom to the top phase of the ATPS was enthalpically driven, with −4.84kJmol−1<ΔHtr,Chy∞<−170.34kJmol−1 and −11.69Jmol−1K−1<ΔStr,Chy∞<−558.95Jmol−1K−1 characterizing an enthalpy–entropy compensation process; −1.36kJmol−1<ΔGtr,Chy∞<−3.77kJmol−1. ΔHtr,Chy∞ became more negative as the tie-line length increased, showing that specific macromolecule–Chy interactions determine the enzyme concentration in the top phase. The nature of the cation/anion, hydrophobic/hydrophilic balance of the top phase, and macromolecule molar mass influence the intermolecular interaction between Chy and top phase components, changing the enzyme partition behavior. Negative ΔStr,Chy∞ parameters were attributed to the Chy transfer from a higher (bottom phase) to the lower (top phase) configurational entropy region.

MASS TRANSPORT AND TURBULENCE IN GRAVITATIONALLY UNSTABLE DISK GALAXIES. II. THE EFFECTS OF STAR FORMATION FEEDBACK

ABSTRACT Self-gravity and stellar feedback are capable of driving turbulence and transporting mass and angular momentum in disk galaxies, but the balance between them is not well understood. In the previous paper in this series, we showed that gravity alone can drive turbulence in galactic disks, regulate their Toomre Q parameters to ∼1, and transport mass inwards at a rate sufficient to fuel star formation in the centers of present-day galaxies. In this paper we extend our models to include the effects of star formation feedback. We show that feedback suppresses galaxies’ star formation rates by a factor of ∼5 and leads to the formation of a multi-phase atomic and molecular interstellar medium. Both the star formation rate and the phase balance produced in our simulations agree well with observations of nearby spirals. After our galaxies reach steady state, we find that the inclusion of feedback actually lowers the gas velocity dispersion slightly compared to the case of pure self-gravity, and also slightly reduces the rate of inward mass transport. Nevertheless, we find that, even with feedback included, our galactic disks self-regulate to Q ∼ 1, and transport mass inwards at a rate sufficient to supply a substantial fraction of the inner disk star formation. We argue that gravitational instability is therefore likely to be the dominant source of turbulence and transport in galactic disks, and that it is responsible for fueling star formation in the inner parts of galactic disks over cosmological times.

Frequency modulated radar signal with combined chaotic sequence based on Bernoulli map

Chaotic signal shows amounts of advantages in the application of radar systems for its easy generation and control. The model of combined chaotic maps based on Bernoulli map is proposed in this paper. Then, the chaos based frequency modulated (FM) radar signal is put forward and the frequency spectrum, ambiguity function are also analyzed in theory. In simulation, the phase spaces, Approximate entropy (ApEn) and balance of the combined chaotic maps are investigated, which shows the combined maps sequences have greater performances than the initial sequences. Additionally, the Peak side-lobe level (PSL) and Integrated side-lobe level (ISL) of signal autocorrelation are discussed, and they drop greatly with the combined chaotic maps after frequency modulation. Simulation results also show that the FM signal based on combined chaotic maps has flatter frequency spectrum in the whole frequency band and a thumbtack ambiguity function.

Assessment of a Stirred-Cell Reactor Operated Semicontinuously for the Kinetic Study of Fast Direct Ozonation Reactions by Reactive Absorption

A jacketed stirred-cell reactor, operated semicontinuously, was used to assess the kinetics of fast ozonation reactions by reactive absorption. The method was applied to the direct ozone reaction with resorcinol. A high resorcinol concentration was used to reach a steady state and to neglect byproduct accumulation. Thus, the mass-transfer rate and, consecutively, the reaction rate were deduced from the ozone mass balance in the gas phase. The gas- and liquid-phase mass-transfer coefficients were previously measured directly through ozone absorption under appropriate conditions. The results emphasized the high sensitivity of the reaction rate constant to the ozone physicochemical properties, especially its solubility, which is controversial in the literature. Therefore, several correlations used to calculate the ozone solubility in water were considered to calculate the second-order reaction rate constant, which varied from 3.57–4.68 × 105 L mol–1 s–1 at 20 °C to 9.50–12.2 × 105 L mol–1 s–1 at 35 °C. The a...

A Broadband High-Power Five-Way Power Divider/Combiner

ABSTRACTA high-power five-way power divider/combiner utilizing strip-line architecture in the X-band is proposed. In this work, broadband non-uniform strip-line couplers are connected in a tree structure. A power-handling capability of 100 watts is verified by full-wave electromagnetic simulation. The simulation results indicate that the power divider/combiner exhibits a good amplitude, phase balance characteristics, and isolation between output ports, as well as a return loss at input and output ports better than 12 dB, while insertion loss is about 1.1 dB. A prototype of the power divider/combiner is fabricated and also measured. The measured results show very good agreement with those obtained by simulation.

Solar photocatalytic decomposition of ethyl paraben in zinc oxide suspensions

The photocatalytic degradation of ethyl paraben (EP) in zinc oxide (ZnO) suspensions under simulated solar radiation was investigated. The effect of EP concentration (500–1500μg/L), ZnO concentration (100–500mg/L), reaction time (3–9min), initial pH (3–9), light intensity (7.3 10−7–1.1 10−6 einstein/(L.s)) and the water matrix (0–10mg/L of humic acid) on degradation was evaluated implementing a factorial design methodology. Of the six variables tested, EP concentration, ZnO concentration, reaction time and the water matrix were found to be statistically significant variables, and also important was the second order interaction of EP concentration with reaction time. With the exception of the water matrix, all other effects were positive with respect to the concentration of EP removed.Experiments at increased EP concentration (20mg/L) were performed to identify transformation products (TPs) and assess the extent of mineralization. LC-TOF-MS analysis revealed the formation of seven early-stage TPs through hydroxylation and dealkylation reactions and a plausible reaction pathway was proposed. Besides the identified TPs, other unidentified TPs were also formed as has been verified measuring the extent of mineralization and performing a carbon balance in the liquid phase. EP at 20mg/L exhibited mild estrogenic activity, which was partially removed upon oxidation. The stability of ZnO was evaluated measuring the extent of zinc leaching, which was just 1.5%; moreover, ZnO was found to be more active than reference P25 TiO2 for EP degradation and mineralization.

EVOLUTION OF MOLECULAR AND ATOMIC GAS PHASES IN THE MILKY WAY

ABSTRACT We analyze radial and azimuthal variations of the phase balance between the molecular and atomic interstellar medium (ISM) in the Milky Way (MW) using archival CO(J = 1-0) and HI 21 cm data. In particular, the azimuthal variations—between the spiral arm and interarm regions—are analyzed without any explicit definition of the spiral arm locations. We show that the molecular gas mass fraction, i.e., , varies predominantly in the radial direction: starting from at the center, remaining to and decreasing to ∼10%–20% at when averaged over the whole disk thickness (from ∼100% to ≳60%, then to ∼50% in the midplane). Azimuthal, arm-interarm variations are secondary: only in the globally molecule-dominated inner MW, but becoming larger, ∼40%–50%, in the atom-dominated outskirts. This suggests that in the inner MW the gas remains highly molecular ( ) as it moves from an interarm region into a spiral arm and back into the next interarm region. Stellar feedback does not dissociate molecules much, and the coagulation and fragmentation of molecular clouds dominate the evolution of the ISM at these radii. The trend differs in the outskirts where the gas phase is globally atomic ( ). The HI and H2 phases cycle through spiral arm passage there. These different regimes of ISM evolution are also seen in external galaxies (e.g., the LMC, M33, and M51). We explain the radial gradient of using a simple flow continuity model. The effects of spiral arms on this analysis are illustrated in the Appendix.

Structural and Tribological Properties of Nanostructured Supersonic Cold Sprayed Ni-20 wt.% Sn Coatings

80-μm-thick nanostructured coatings consisting of a Ni solid solution, Ni3Sn, Ni3Sn2, and metastable NiSn intermetallic phases were deposited via supersonic cold spraying onto inconel 718 alloy substrates. These coatings have complex nanostructured metallurgical phases as revealed by transition electron microscopy, scanning electron microscopy, and x-ray diffraction techniques. Their mechanical properties were determined by nanoindentation measurements. Furthermore, the wear behavior of these nanostructured sprayed coatings was compared to the one of the industrial bulk or sprayed coated benchmark materials. It was found that the nanostructured coatings exhibit higher wear resistance than the industrial benchmarks, thanks to an appropriate balance of hard intermetallic phases and soft Ni matrix, as well as to their nanostructuring. Their frictional characteristics under reciprocating sliding are mainly determined by the formation of an oxide-based tribo-layer, which was analyzed by x-ray photoelectron spectroscopy. The role of intermetallic phases in these coatings on the friction and wear is also discussed.

Use of smart‐meter data to determine distribution system topology

Smart-meter data presents an opportunity for utilities to improve their database records, and develop a low-voltage (LV) model which may be useful for outage management and fault detection, isolation and response, phase balancing, and network planning. In addition, impact assessment studies on new technologies can be performed. This study presents several contributions in the area of determining the topology of the LV distribution system. This is in terms of identifying the transformer a particular installation control point is connected to, and the phase if that customer is single-phase. First, harmonic voltage correlation is proposed as it is more robust to noise and missing records than the prior algorithm of voltage correlation. Second, it is demonstrated that smart-meter data can be used to determine the transformer/phase to which a customer is connected and update database records in this regard. To achieve this, a new algorithm based on correlation analysis with the Fisher Z transform is developed. Third, a method to estimate LV feeder and service main impedances is presented. Further work is necessary; however, the results from trials in Auckland, New Zealand are highly promising.

Planning of unbalanced radial distribution systems using differential evolution algorithm

This paper presents a planning approach for unbalanced radial distribution systems using differential evolution algorithm (DE) so as to determine the optimal phase balancing and conductor sizes. The objective functions used in the planning are minimization of: (1) total complex power unbalance, (2) total power loss, (3) average voltage drop, (4) voltage unbalance factor, and (5) total neutral current. The optimization is done under the constraints of minimum and maximum voltage limits for each bus voltage and thermal limit of each line. A three phase forward–backward sweep load flow algorithm is developed and used for the determination of these objective functions. The effectiveness of the proposed planning algorithm is corroborated on 19-bus and IEEE 25-bus unbalanced radial distribution systems. The results show that significant improvements in power loss and voltage drop with simultaneous optimization for phase balancing and conductor sizes. The performance of DE is found to be better and consistent as compared to some other meta-heuristic algorithms studied here.

Multi-objective optimization of the balancing of phases in primary distribution circuits

The primary distribution systems are among the more unbalanced three-phase networks. The unbalance of the phase currents causes two fundamental problems in the circuits: the increase of energy losses in the primary feeders and the presence of a high neutral current in normal operating status that makes it difficult the detection of ground faults by corresponding protections. These circuits are always protected at the substation. Nevertheless, other protections can also be located downstream in some sections or laterals of the circuit. Additionally, a circuit or some section of it can be supplied from another adjacent circuit in emergency conditions. In all the points where a ground fault protection is used, the maximum current of imbalance must be reduced to a minimum considering the several operating conditions that can change the circuit topology. This paper formulates the problem of phase balancing as a multi-objective optimization problem that minimizes: the neutral current at the desired points of the circuit, the energy losses in the primary feeders and the number of reconnected elements to achieve these objectives. The Non-dominated Sorting Genetic Algorithm (NSGA-II) has been used to develop the optimization application, which has shown a very successful performance in the solution of the phase balancing problem. A test example with all the needed data is solved to show the advantages of the presented approach.

Compact microstrip branch-line coupler with wideband quadrature phase balance

This letter presents planar microstrip branch-line (BL) couplers with improved phase and amplitude stability bandwidth along with significant size reduction. The prototypes are designed to operate at 433 MHz frequency band suitable for ISM 433 MHz applications. The prototypes with symmetric polygonal modification (SPM) and asymmetric polygonal modification (ASPM) offer a wide quadrature phase bandwidth of 37.8% and 35.5% respectively, over which the phase imbalance is within 90°±5°. In SPM all four transmission lines of the BL coupler have been symmetrically modified to bring in 75.99% size reduction compared to the conventional design. Further asymmetric modification has been performed to bring an additional 12.34% size reduction, compared to symmetric, and providing an overall size reduction of 78.95% compared to conventional BL coupler. The prototypes are able to offer compactness without compromising much on the matching, transmission and isolation parameters. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1369–1374, 2016

2-6 GHz GaN distributed power amplifier MMIC with tapered gate-series/drain-shunt capacitors

In this article, using a 0.25 μm GaN HEMT process, we present a 2–6 GHz GaN two-stage distributed power amplifier MMIC that utilizes tapered gate series capacitors and nonuniform drain transmission lines with tapered shunt capacitors to simultaneously obtain a linear gain enhancement and optimum load line for each transistor. By using well-derived equations to provide each transistor with the optimum load impedance and to tune the phase delay between the input and output transmission lines, the nonuniform distributed power amplifier is designed for second-stage amplification, and satisfactory performance is demonstrated. The phase balance and tapering of the gate series capacitors have a role in improving the linear gain of the two-stage amplifier. The measured data show a linear gain of 22 ± 1 dB, an input/output return loss of more than 15 dB, saturated output power of 41.2–43.1 dBm under a continuous-wave mode, and a power-added efficiency of 18–22% from 2 to 6 GHz which are very competitive values compared with previous works. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:456–465, 2016.

Influência do aporte térmico sobre a morfologia da austenita e na quantidade das fases em chapas soldadas de aço inoxidável duplex SAF2205

Os aços inoxidáveis duplex possuem uma microestrutura na qual a composição de ferrita e austenita, tem frações volumétricas próximas a 50 %. Esses são utilizados na fabricação de diversos componentes e produtos, principalmente para aplicações na indústria petrolífera. Nestas aplicações muitas vezes são utilizados processos de soldagem. Para mitigar as alterações provocadas por esse processo nas propriedades do material é necessária uma escolha adequada dos parâmetros de soldagem. Neste contexto, o objetivo desse trabalho é avaliar o efeito do aporte térmico sobre a morfologia da austenita e na quantidade das fases, além de identificar qual condição de soldagem proporciona um equilíbrio das frações volumétricas de ferrita e austenita. Os materiais analisados são chapas de aço inoxidável duplex SAF2205, soldadas pelo processo de soldagem GMAW, na ESAB, variando-se o aporte térmico em 0,5, 1,0 e 1,5 kJ/mm. Após a soldagem, as chapas foram cortadas, preparadas para a análise metalográfica da morfologia de austenita formada e para a quantificação das fases. Os resultados mostraram a presença da austenita alotriomórfica de contorno de grão, a austenita de Widmanstätten e a austenita intragranular. Foi verificado que o aporte térmico que menos alterou o balanceamento das fases ferrita e austenita foi o de 1,5 kJ/mm, concluindo que se deve utilizá-lo quando o objetivo for manter a proporção volumétrica das fases no aço duplex SAF2205.

Model-centric Distribution Automation: Capacity, Reliability, and Efficiency

A series of analyses along with field validations that evaluate efficiency, reliability, and capacity improvements of model-centric distribution automation are presented. With model-centric distribution automation, the same model is used from design to real-time control calculations. A 14-feeder system with 7 substations is considered. The analyses involve hourly time-varying loads and annual load growth factors. Phase balancing and capacitor redesign modifications are used to better prepare the system for distribution automation, where the designs are performed considering time-varying loads. Coordinated control of load tap changing transformers, line regulators, and switched capacitor banks is considered. In evaluating distribution automation versus traditional system design and operation, quasi-steady-state power flow analysis is used. In evaluating distribution automation performance for substation transformer failures, reconfiguration for restoration analysis is performed. In evaluating distribution automation for storm conditions, Monte Carlo simulations coupled with reconfiguration for restoration calculations are used. The evaluations demonstrate that model-centric distribution automation has positive effects on system efficiency, capacity, and reliability.

Corrosion studies using potentiodynamic and EIS electrochemical techniques of welded lean duplex stainless steel UNS S82441

The corrosion characterisation of lean duplex stainless steel (1.4662) UNS S82441 welded joints using the potentiodynamic test and electrochemical impedance spectroscopy in 1M NaCl solution are discussed. The influence of autogenous TIG welding parameters (amount of heat input and composition of shielding gases like Ar and Ar–N2 and an Ar–He mixture), as well as A-TIG welding was studied. The influence of welding parameters on phase balance, microstructural changes and the protective properties of passive oxide films formed at the open circuit potential or during the anodic polarisation were studied.From the results of the potentiodynamic test and electrochemical impedance spectroscopy of TIG and A-TiG, welded joints show a lower corrosion resistance compared to non-welded parent metal, but introducing heat input properly during welding and applying shielding gases rich in nitrogen or helium can increase austenitic phase content, which is beneficial for corrosion resistance, and improves surface oxide layer resistance in 1M NaCl solution.

Considerations for On-Wafer Millimeter-Wave Measurements on Thin Ceramic Substrate

This paper presents an on-wafer millimeter-wave circuit’s characterization build on thin ceramic substrate having a high relative permittivity. An RF short circuit, designed with a quarter-wavelength radial stub, is used in load design and launch transition. To improve the design accuracy of electromagnetic (EM) tools, the dielectric constant of the ceramic substrate is extracted using measurements of several pairs of microstrip lines combined with EM simulations. The largest deviation obtained, compared with the mean value over the frequency band, is less than 1%. Thus, a new six-port circuit is designed and characterized using a millimeter-wave probe station. A comparison between the measurement and simulation results, using extracted manufacturer-recommended relative permittivity, is conducted. The six-port $q_{i}$ points’ location is close to the simulated and theoretical ones over the frequency band of interest. As demonstrated in this paper, the substrate permittivity extraction has improved the design accuracy of the millimeter-wave circuits. Excellent performance of this circuit in terms of matching, isolation, and amplitude and phase balance is obtained.

Application of Electromagnetic Transient-Transient Stability Hybrid Simulation to FIDVR Study

This paper deals with the development of a new electromagnetic transient (EMT)-transient stability (TS) hybrid simulation platform and its application to a detailed fault-induced delayed voltage recovery (FIDVR) study on the WECC system. A new EMT-TS hybrid simulation platform, which integrates PSCAD/EMTDC and the open source power system simulation software InterPSS has been developed. A combined interaction protocol with an automatic protocol switching control scheme is proposed. A multi-port three-phase Thevenin equivalent is developed for representing an external network in an EMT simulator. Correspondingly, the external network is represented in three-sequence, and a three-sequence TS simulation algorithm is developed. These techniques allow simulation of unsymmetrical faults within the internal network without the constraint of phase balance at the boundary. The effectiveness of the proposed techniques is first tested on the IEEE 9-bus system. Subsequently, the proposed hybrid simulation approach is applied to a detailed FIDVR study on a large WECC system. The study shows that a normally cleared single-line-to-ground (SLG) fault in the transmission system could lead to an FIDVR event, with compressor motors of the air conditioning units on the faulted phases stalling first, followed by a propagation of motor stalling to the unfaulted phase. Moreover, similar events are observed in simulations with a wide range of load compositions. Lastly, the effect of the point-on-wave (POW) at which a fault is applied on the occurrence of an FIVDR event is also analyzed.

A Dynamic and Heuristic Phase Balancing Method for LV Feeders

Due to the single-phase loads and their stochastic behavior, the current in the distribution feeders is not balanced. In addition, the single-phase loads are located in different positions along the LV feeders. So the amount of the unbalanced load and its location affect the feeder losses. An unbalanced load causes the feeder losses and the voltage drop. Because of time-varying behavior of the single-phase loads, phase balancing is a dynamic and combinatorial problem. In this research, a heuristic and dynamic solution for the phase balancing of the LV feeders is proposed. In this method, it is supposed that the loads’ tie could be connected to all phases through a three-phase switch. The aim of the proposed method is to make the feeder conditions as balanced as possible. The amount and the location of single-phase loads are considered in the proposed phase balancing method. Since the proposed method needs no communication interface or no remote controller, it is inexpensive, simple, practical, and robust. Applying this method provides a distributed and dynamic phase balancing control. In addition, the feasibility of reducing the used switches is investigated. The ability of the proposed method in the phase balancing of the LV feeders is approved by carrying out some simulations.