AC Phase Research Articles

Piezoimpedance of carbon nanotube yarns coupled with Raman spectroscopy and its implementation for sensing polymerization kinetics

The electrical response of carbon nanotube yarns (CNTYs) under alternating (AC) and direct current (DC) is investigated. Electrical measurements are conducted simultaneously with application of strain and under in situ Raman spectroscopy. In situ Raman spectroscopy is used to better understand the loading mechanisms and the electromechanical response of the CNTY upon axial stretching. The AC electrical response of the CNTYs is dominated by its resistive component, and a capacitive contribution arises at high frequencies (f > 105 Hz). This response obeys the hierarchical structure of the CNTY, where porosity between bundles form microcapacitors. Under AC, the impedance modulus showed a positive electrical sensitivity to strain with a maximum value of 0.33 at 100 kHz. This is slightly higher than the DC one (0.25). The AC phase angle showed very low sensitivity to strain. The small shift of the Raman bands with strain suggests that structural deformations at the bundle level are the dominant deformation mechanism. While the Raman shift is weak to identify unwinding and detaching of bundles, both the AC and DC electrical responses pinpoint such damage mechanisms by a change in trend. The promising application of the impedance response to monitor the curing kinetics of thermosetting polymers is proved.

초고속차단기와 바이패스 사이리스터를 이용한 MMC의 DC-Link 고장전류 차단 방법

The modular multi-level converter (MMC) has recently gotten great attention due to the installation of large renewable generation farms and high voltage direct current transmission (HVDC). In the same manner as the conventional inverters, MMC operates based on multiple insulated-gate bipolar transistors (IGBTs). Each IGBT is generally combined with an anti-parallel diode in the half-bridge MMC, the most efficient MMC topology. Due to the diode path, the DC fault current, caused by the AC phase voltage differences when its DC-Link bus shorts, flows the MMC freely. This paper proposes a DC-Link fault current interrupting method based on Ultra Fast Disconnectors (UFDs) and bypass thyristor. The proposed method is verified based on electromagnetic transient (EMT) level simulations, including several case studies with various short circuit ratios (SCRs) and reluctance per resistance (X/R) ratios. As a result, the proposed method successfully blocks the DC-Link fault current within at most one cycle. The case studies are conducted using a power system computer aided design and electromagnetic transient including DC (PSCAD/EMTDCTM).

Distribution of Hay-Hole Covers Prevents Injuries from Falls Through Hay Holes.

Hay-holes are openings on the second floor of barns used to drop feed to ground level. Hay-hole falls (HHFs) are a unique problem among Anabaptist communities, especially for children. To follow-up on our previous study that created the Anabaptist Youth Trauma Prevention Consortium with distribution of 231 hay-hole covers in South Central Pennsylvania, we compared a five-year period before cover distribution with the 5-year period after. Data were stratified by phase: Before Cover Implementation (BC): 1/2011-12/2016, After Cover Implementation (AC): 1/2017-12/2021. 49 patients met inclusion criteria. There was a 47% decrease in the number of HHF from the BC phase to the AC phase, suggesting that cover distribution has significantly impacted HHF incidence. Further investigation is needed to elucidate the long-term impact of cover distribution and to guide future interventions, such as another round of cover distribution or improvements in the design of these covers for long-term use.

An observational study of dose dense chemotherapy with lipegfilgrastim support in early breast cancer

PurposeBreast cancer is one of the most prevalent malignant diseases in women. The development of dose dense chemotherapy regimens has improved clinical outcomes but has been associated with increased hematological toxicity. Currently there is a paucity of data on the use of lipegfilgrastim in dose dense AC treatment in early breast cancer. The purpose of this study was to assess the use of lipegfilgrastim in the treatment of early breast cancer and to examine the incidence of treatment-related neutropenia during the dose dense AC phase and subsequent paclitaxel treatment.MethodsThis was a single arm, non-interventional, prospective study. The primary endpoint was to determine the rate of neutropenia defined as ANC of < 1.0 × 109/L, during four cycles of dose dense AC with lipegfilgrastim support. The secondary endpoints were the incidence of febrile neutropenia, (temperature > 38 °C and ANC < 1.0 × 109/L), treatment delays, premature treatment cessation and toxicity.ResultsForty-one participants were included in the study. Of the 160 planned dose dense AC treatments, 157 were administered, and 95% (152/160) of these were given on time. The rate of treatment delay was 5% (95% CI 2.2 to 9.9%) due to infection (4) and mucositis (1). Four (10%) patients developed febrile neutropenia. The most frequently occurring adverse event was grade 1 bone pain.ConclusionLipegfilgrastim is an effective option in the prophylaxis of chemotherapy-induced neutropenia, and its use in everyday anti-cancer treatment can be considered.

A randomized, double-blind, phase III, non-inferiority clinical trial comparing the efficacy and safety of TA4415V (a proposed Trastuzumab biosimilar) and Herceptin (Trastuzumab reference product) in HER2-positive early-stage breast Cancer patients

BackgroundThis study compared efficacy and safety of TA4415V, a trastuzumab biosimilar, with reference trastuzumab in patients with human epidermal growth factor receptor 2–positive (HER2-positive) early-stage breast cancer treated in the neoadjuvant setting in Iran.MethodsPatients were randomly assigned to receive neoadjuvant TA4415V or reference trastuzumab concurrently with docetaxel (TH phase) for 4 cycles after treatment with 4 cycles of doxorubicin and cyclophosphamide (AC phase). Chemotherapy was followed by surgery. The primary endpoint was the comparison of pathologic complete response (pCR) rate in the per-protocol population. Secondary endpoints included comparisons of overall response rate (ORR), breast-conserving surgery (BCS), safety, and immunogenicity.ResultsNinety-two participants were analyzed in the per-protocol population (TA4415V, n = 48; reference trastuzumab, n = 44). The pCR rates were 37.50% and 34.09% with TA4415V and reference drug, respectively. The 95% CI of the estimated treatment outcome difference (− 0·03 [95% CI − 0.23 to 0.16]) was within the non-inferiority margin. No statistically significant difference was observed between the groups for other efficacy variables in the ITT population: ORR (89.13% vs. 83.33%; p = 0.72) and BCS (20.37% vs. 12.96%; p = 0.42) in the TA4415V and reference drug group, respectively.At least one grade 3 or 4 adverse events occurred in 27 (50%) patients in the TA4415V group versus 29 (53.70%) in the reference trastuzumab group (p = 0.70). The decrease in left ventricular ejection fraction (LVEF), as an adverse event of special interest (AESI) for trastuzumab, was compared between treatment groups in TH phase. Results demonstrated an LVEF decrease in 7 (12.96%) and 9 (16.67%) patients in TA4415V and reference trastuzumab groups, respectively (p = 0.59). Anti-drug antibodies (ADA) were not detected in any samples of groups.ConclusionsNon-inferiority for efficacy was demonstrated between TA4415V and Herceptin based on the ratio of pCR rates in HER2-positive early breast cancer patients. In addition, ORR and BCS, as secondary endpoints, were not significantly different. Safety profile and immunogenicity were also comparable between the two groups.

Three-phase Active Tracking AC-AC Voltage Regulator based on Buck Converter with an Efficient Hybrid Control Technique

This study proposes a switch-mode three-phase active tracking AC-AC voltage regulator based on the buck converter. The regulator topology incorporates a moderate number of components with less complexity and high efficiency. An efficient hybrid control technique, based on a closed-loop PID controller that is supported with a new designed feedforward controller, is proposed for the regulator control different to the similar studies in the literature. The hybrid control technique augments the response of active tracking of the reference output phase voltages to achieve an improved quality close to sine-wave output phase voltages for either the input AC phase voltages that are ideal pure sine-wave or include various harmonics. The regulator topology has a modular structure for independent control of each output phase. So, the regulator can help to achieve close to sine-wave output phase voltages to supply a balanced/unbalanced wye-connected three-phase load or independent single-phase loads. The presented three-phase regulator and the control technique are tested with simulation and experimental studies. The laboratory set-up of the regulator is designed for 2.2 kW output power, 0-300 Vp input phase voltages (50 Hz), and 0-200 Vp output phase voltages. The results demonstrated that the proposed switch-mode three-phase buck-type active tracking voltage regulator can provide the desired AC phase voltages with less than 5% THD (total harmonic distortion) and low harmonics for different operating conditions.

Modeling dipolar excitation for quadrupole mass filter.

The results of modeling AC and DC dipole excitation of ion oscillations in a quadrupole mass filter are presented. The simulation is done by numerical integration of the ion motion equations, ions' initial coordinates and velocities are distributed normally. For AC dipole excitation the instability bands on the (a, q) stability diagram follow along the isolines and , creating regular dips on the transmission contour. We show that AC excitation at frequency Ω/2 makes it possible to control the resolution of the mass filter by either changing the AC amplitude or phase. Instability bands can be used for mass selective excitation in a linear ion trap. Options for the joint use of DC and AC dipole excitation to form the mass peak shape are considered.

Boost Converter Based 3-phase AC-AC Active Tracking Voltage Regulator Controlled by a Robust Hybrid Control Method

In this study, a switch-mode three-phase active tracking AC-AC voltage regulator based on the boost converter is proposed with a moderate number of active and passive elements used in the topology. A robust hybrid control, where a novel designed feedforward controller supports the closed-loop PID controller, is proposed for the control of the regulator apart from similar studies in the literature. Active tracking response of the reference output phase voltages is augmented by the proposed hybrid control method. Thus nearly close to sine-wave output phase voltages can be obtained, whether the input AC phase voltages are ideal pure sine or not. Also, the modular structure of the regulator topology enables independent control for each output phase. Thus, the supply of balanced/unbalanced wye-connected three-phase loads or independent single-phase loads with nearly close to ideal sine wave voltages can be achieved by the modularity of the regulator. Both experimental and simulation test studies are performed for the proposed regulator system. A laboratory set-up for the regulator is designed for 0-200 Vp input phase voltages (50 Hz), and 0-300 Vp output phase voltages, and 1.8 kW output power. The achieved results for both simulation and experimental tests verify the proposed switch-mode boost-type regulator’s ability to provide output phase voltages nearly close to sine wave with total harmonic distortion (THD) values under 5%.

PERANCANGAN TRANFORMASI DAYA LISTRIK DARI SISTEM 3 PHASA KE 9 PHASA MENGGUNAKAN TRANSFORMATOR BERINTIKAN BESI

Regarding the harmonics of AC current, when the AC phase is connected to the rectifier it will cause harmonics to appear on the AC line. In addition, this rectification process requires a large enough capacitor if you want to reduce the voltage ripple from the rectification result. The larger the capacitor, the smaller the ripple, but the higher the cost of the capacitor. So the author chose the title of the final project «Design of Electrical Power Transformation from 3 Phase to 9 Phase System Using an Iron Core Transformer. Problem Formulation How to design a multi-phase transformer, especially a 3-phase to 9-phase transformer. How to design a multi-phase transformer construction. For multiphase transformers, especially transformers from 3 phases to 9 phases, 3 single phase transformers can be used which have one coil on the primary side and 5 coils on the secondary side. To get a voltage on phase 2 with the same amplitude of 100 volts with phase 1 only 40 degrees different in phase, then a voltage of 113 volts on phase 1 with a phase angle of 0 degrees, plus a voltage on phase 4 of 74 volts with a phase angle 120 degrees. Then to get a voltage on phase 3 with the same amplitude of 100 volts, it takes a voltage of 74 volts on phase 1 with an angle of 0 degrees, plus a voltage on phase 4 of 113 volts with a phase angle of 120 degrees. trying to make this 3 phase to 9 phase transformer by using the construction of 1 3 phase transformer. do the calculation of the transformer power that will be designed.

AC conductivity and phase transition of the BST-BFO ceramic doped with Yb.

The homogeneity of the 0.8(Ba0.8Sr0.2)TiO3–0.2(Bi0.85Yb0.15)FeO3 ceramic, prepared by a solid-state process, was studied and quantitatively analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). At ambient temperature, X-ray diffraction shows the existence of only one perovskite phase in the tetragonal structure with the space group P4mm. The thermal variations of (real part of the dielectric permittivity) for this composition show extended peaks with temperature; this broadening of the peaks can be attributed to the diffuse character of the transition. As the frequency increases, Tm (temperature of maximum permittivity) moves at higher temperatures, and the maximum values of decrease. Moreover, the impedance spectra (−Z′′ vs. Z′) show the presence of two arcs of circles that have been modeled with an equivalent electrical circuit. The arcs of the circles centered under the real axis (Z) prove the Cole–Cole-type behavior. Each circle is associated with either the grain effect or grain boundaries. Electrical modulus analysis shows that the capacitance of the ceramic is enhanced, which is in good agreement with the results of complex impedance analysis. The AC conductivity complies with the universal power law. It disputes the modification of AC conductivity by adopting the Arrhenius-type of electrical conductivity. The temperature dependence of alternating current conductivity (σg) and direct current conductivity (σDC) confirms the existence of the ferroelectric–paraelectric phase transition.

AC phase controlled bridges – ground and main properties

This work describes the new approach to the improving of the accuracy of the bridge impedance measurements. By this approach, the bridge balance in a wide impedance range uses the control of the phases of the aggregate of the cardinal signals only. The optimal structure and algorithm of the control of this aggregate of the cardinal signals is determined. Using this approach accurate impedance meters with low size and price are developed. In the limit, this approach gets us the possibility to develop fully integrated impedance meters. Report shortly describes universal impedance meters with phase control, their balance and calibration algorithms.

Photon phase shift imaging research on frequency domain diffuse optic tomography

Diffuse optic imaging is an important biomedical optic research tool. Diffuse optic tomography (DOT) modality needs progressive philosophical approaches for scientific contribution. Technological developments and philosophical approaches should both go forward. Phase-shift based frequency domain diffuse optical tomography (FDDOT) method was well established in the literature. The instruments were tested for brain neurofunctional imaging. A mixture of AC laser intensity and phase data were used at these works. According to those works, deep tissue resolution was improved by only using phase data. Because phase data is only related to the photon mean free path in imaging tissue media. Besides this advantage, laser intensity data is also affected by noisy background light and electrical artifacts. Another most important advantage of only using phase data can be explained as time-resolved temporal change which can be directly related to the phase shift of modulated frequency source. In this work, the FDDOT imaging method which uses phase shift data were tested for simulation. Laser source-driven forward model problem weight matrix simulation data was given to the simple pseudo-inverse-based inverse problem solution algorithm for one inclusion example. The inclusion image was reconstructed and demonstrated successfully. Forward model problem weight functions inside the tissue simulation media were calculated and used based on the phase shifts at the same core modulation frequency. 100 MHz modulation frequency was selected due to its FDDOT standard. 13 sources and 13 detectors were placed on the back-reflected imaging surface. 40 x, y, z cartesian coordinate grid elements were used in the image reconstruction algorithm. Photon absorption coefficient: μa = 0.1 cm−1, and scattering coefficient: μs = 100 cm−1 values were set for simulation background. One inclusion object was embedded inside the background imaging tissue simulation environment. x, y, z cartesian coordinate grid sizes were selected for 1 μm for each direction. Photon phase shift fluencies were added to the forward model problem. The forward model problem was built according to the frequency domain photon migration diffusion equation (DE) approximation. The pseudoinverse mathematical inverse problem solution function was applied to test the results. The embedded inclusion object was reconstructed successfully with the high-resolution image quality. The philosophical approach has future promising DOT imaging capability. The phase shift version of the FDDOT modality has an important advantage for future purposes.

High-performance vector control without AC phase current sensors for induction motor drives: Simulation and real-time implementation

The main purpose of this paper is to develop a high-level performance, and low-cost current sensorless control strategy for Induction Motor (IM) drives. Therefore, a new phase-current regeneration method, for current sensorless vector control in induction motor drives is introduced. The idea is based on the reconfiguration of the Luenberger adaptive observer for currents estimation, using the information provided by the dc-link voltage sensor. The basis of the proposed control and the theoretical study of the modified adaptive observer are presented. Several simulation and experimental tests were performed on an induction motor of 1.1 kW working under different operating conditions. The obtained results prove and testify the relevance, workability, and practicability of the suggested currents sensorless vector control strategy.

AC Transport Loss in Superconductors Carrying Harmonic Current With Different Phase Angles for Large-Scale Power Components

It is of great industrial interest and academic importance to investigate current harmonics impacts on AC losses of superconductors, especially in large-scale power devices. However, only effect of amplitude of in-phase current harmonics on AC loss has been studied in the works of literature. We numerically characterized nonsinusoidal AC loss of superconducting tape carrying harmonic currents with orders below 20th versus phase angles. A drastic AC loss variation was found when phase angle was considered for harmonic components. We observed that different harmonic orders show different AC loss profile versus phase angle.

Co-optimization of multi-stage transmission expansion planning and grid operation

The ongoing transformation of the power system characterized by an increased share of renewable energy sources requires additional transmission capacities. Nevertheless, the need for new transmission capacities can be reduced by optimizing grid operation. This contribution presents a novel approach to the co-optimization of multi-stage transmission expansion planning and grid operation within a mixed-integer linear programming formulation. The expansion via AC systems and phase shifting transformers (PSTs) is combined with the control of PSTs and the determination of congestion management interventions such as redispatch of power plants or curtailment of renewable energies. The number of potential expansion candidates is reduced by linear programming relaxations. Exemplary results based on a synthetic test system containing 120 buses evidence the impact of the proposed approach on overall system costs. The proposed co-optimization reduces the total costs by 16.5 % when applied instead of the sole expansion via AC technology.

A Stationary Reference Frame Current Control Algorithm for Improvement of Transient Dynamics of a Single Phase Grid Connected Inverter

This paper proposes a stationary reference frame current control algorithm for a single-phase grid-connected inverter (GCI) for improvement of transient dynamic performance. Disturbance, i.e., grid voltage in a target system, is estimated using a stator current observer, and the estimated disturbance is applied to a current controller for implementation of disturbance rejection control (DRC). In the proposed current control algorithm, the disturbance rejection control algorithm is applied to reduce the overcurrent occurring in the single-phase grid-connected inverter when grid faults happen. In this paper, the AC phase current of a single-phase inverter is controlled, instead of the current vector, which is a DC signal. To compensate for the drawbacks of controlling the AC phase current, such as phase lag and steady-state error, command feedforward control is also applied in the proposed control system. The proposed control algorithm is mathematically derived and represented in transfer functions and implemented via simulation and experiment.

Decentralized Bidirectional Voltage Supporting Control for Multi-Mode Hybrid AC/DC Microgrid

A hybrid ac/dc microgrid consists of alternating current (ac) subgrid(s), direct current (dc) subgrid(s) and intermediate bidirectional power converters (BPCs). The presence of dc distribution networks complicates the operation and corresponding control of the hybrid ac/dc microgrid. This paper proposes a decentralized bidirectional voltage supporting control scheme for the multi-mode hybrid ac/dc microgrid, which can provide uninterruptable ac and dc voltages in case of unintentional ac and dc islanding events. An ac phase angle – dc voltage inverse droop control with virtual impedance are designed and implemented in BPCs, which can support the ac and dc voltages and enable seamless mode switching without additional voltage sources. Proper power sharing between ac and dc subgrids is realized without frequency deviation in the ac islanded mode. The stability of proposed control is analyzed under different modes, and its performance is verified by real-time hardware-in-loop (HIL) tests.

FEATURES OF THE STRUCTURE OF THE CARDIAC CYCLE IN RECRUITS TRAINING CENTER OF THE NAVY IN THE ARCTIC ZONE

Objective: to identify the features of the structure of the cardiac cycle among recruits of the Navy training center, who arrived from different climatic and geographical regions of the Russian Federation in the Arctic zone. Two groups of servicemen of 37 people were formed: the first group consisted of recruits from the southern regions of the Russian Federation, and the second — natives of the northern region. Each soldier was examined monthly for 5 months. To study the structure of the cardiac cycle, polycardiography was used, which included simultaneous recording of an electrocardiogram (ECG), phonocardiogram (PCG) and sphygmogram (SG) of the carotid artery. It was established that the duration of the asynchronous reduction (AS) phase for servicemen from the southern regions during the 5-month observation period only tended to decrease from 0,053±0,004 to 0,044±0,004 s, and starting from 3 months. In the group of servicemen-northerners, the duration of the AU phase during the observation period was statistically significantly reduced from 0,055±0,003 to 0,040±0,004 s, and in months 3, 4, and 5 from 22% to 27% (p&lt;0,05). The stress period (T) in the systole of the ventricles in military personnel from the southern regions also remained almost unchanged, while in the military northerners it was statistically significantly reduced from 0,085±0,002 to 0,080±0,001 s, as well as the duration of the total (electromechanical) systole (So) from 0,372±0,004 to 0,358±0,006 s. Thus, when training at the Navy training center located in the AZ, for recruits-northerners the duration of the AC phase decreases after 2 months, and after 4 months the time T and the duration of So decrease, indicating the beginning of a more efficient work of the myocardium. For recruits from the southern regions of the Russian Federation, by the end of their studies, there is only a slight tendency towards a decrease in the AU phase, which indicates a less efficient work of the myocardium in comparison with the group of northerners.

Fabrication of phase masks from amorphous carbon thin films for electron-beam shaping.

Background: Electron-beam shaping opens up the possibility for novel imaging techniques in scanning (transmission) electron microscopy (S(T)EM). Phase-modulating thin-film devices (phase masks) made of amorphous silicon nitride are commonly used to generate a wide range of different beam shapes. An additional conductive layer on such a device is required to avoid charging under electron-beam irradiation, which induces unwanted scattering events.Results: Phase masks of conductive amorphous carbon (aC) were successfully fabricated with optical lithography and focused ion beam milling. Analysis by TEM shows the successful generation of Bessel and vortex beams. No charging or degradation of the aC phase masks was observed.Conclusion: Amorphous carbon can be used as an alternative to silicon nitride for phase masks at the expense of a more complex fabrication process. The quality of arbitrary beam shapes could benefit from the application of phase masks made of amorphous C.

The Effects of a High Fiber Beta Glucan Talbina Meal on Emotional Well-being Among Syrian Refugees in Metropolitan Detroit (P08-076-19)

ObjectivesThe on-going Syrian War has affected Syrians’ mental health, causing anxiety, depression, stress, and mood disturbances. Barley β- glucan is a soluble fiber and its benefits for mental health have been reported in the literature. This study was designed to assess the possible therapeutic effects of β-glucan supplementation as a natural remedy for emotional disturbance control/prevention using a traditional Islamic homestyle meal, “Talbina”, a semi-solid meal made from ground whole grain, hulled barley (Hordeum vulgare). MethodsA single-blind randomized crossover design was conducted in free-living, stressed Syrian refugees using barley flour (active, AC) for 28 days and rice flour (placebo, PL) for 14 days as part of a breakfast. Subjects (14 females and 9 males, mean age: 41 ± 10 yrs) with normal-to-mild depression and anxiety scores were recruited from the Islamic Center of Detroit. More than 60% of the subjects self-rated their general health as good or very good. Only 4.3% reported poor mental health, and nearly 60% of the subjects reported having at least one non-communicable disease. Arabic validated self-administered questionnaires: The Hospital Anxiety and Depression Scale (HADS), Perceived Stress Scale (PSS), and The Profile of Mood States-short form (POMS-SF) were used to measure anxiety and depression states, stress, and mood, respectively. Body weight and height data were also collected. ResultsSubjects without depression showed a reduction in body mass index (BMI) at the end of the AC phase compared to the PL phase while depressed subjects showed an increase in BMI. The difference between these groups was significant (−.5 ± .5 kg/m2 vs .2 ± .8, P = 0.04). The results showed no differences in anxiety, depression, stress and mood scores between the AC and PL phases. ConclusionsThe findings of this study showed no significant improvement in emotional well-being, depression, or stress levels by eating Talbina. But the subjects with anxiety were benefited significantly by taking part in this study regardless of the key ingredients of their meals. These findings suggest that refugee communities need further social support. Future studies should be conducted with a higher dosage of β-glucan for a longer duration and with a larger sample size to examine the beneficial effects of β-glucan. Funding SourcesThe Department of Nutrition and Food Science at Wayne State University and the Department of Clinical Nutrition at Umm Al-Qura University.