Average Power Distribution Research Articles

Time-Resolved Optical Spectrum Measurement of Multi-Mode Fabry-Perot Laser Diodes

Fabry-Perot (FP) laser diodes usually have multiple longitudinal modes. An optical spectrum analyzer (OSA) is able to measure the average power distribution of the mode structure but cannot detect the dynamics of mode competition which is the origin of the mode partition noise. We demonstrate a time-resolved optical spectrum measurement technique based on frequency-to-time conversion through time gating, chromatic dispersion, and real-time waveform sampling. This allows to investigate the dynamics of mode competition and correlation of relative intensity noises among different FP modes of the diode laser.

Association of Gastric Myoelectrical Activity With Ghrelin, Gastrin, and Irisin in Adults With Metabolically Healthy and Unhealthy Obesity.

Background and Objective: Functional disturbances of gastric myoelectrical activity (GMA) might exist in obesity. However, studies on its association with the gastric hormones in obesity phenotypes are lacking. The objective was to study the association of GMA with the serum levels of key gastric hormones in different obesity phenotypes. Methods: A total of 139 adults (31.00 ± 11.12 years) were classified into different metabolic phenotypes of obesity: 1) normal weight-lean (NWL group): BMI <25 kg/m2 and the fat-mass index (FMI) ≤9.7 kg/m2 in females and ≤6.3 kg/m2 in males; 2) metabolically obese normal weight (MONW group): BMI <25 kg/m2 and FMI >9.7 kg/m2 in females and >6.3 kg/m2 in males; 3) metabolically healthy obese (MHO group): BMI ≥25 and FMI ≤9.7 kg/m2 in females and ≤6.3 kg/m2 in males; and 4) metabolically unhealthy obese (MUO group): BMI ≥25 and FMI >9.7 kg/m2 in females and >6.3 kg/m2 in males. The GMA was measured at the baseline and post-prandial state using a multichannel electrogastrography with a water load satiety test. The average power distribution by the frequency region and the average dominant frequency were used for analysis. Anthropometric measurements and bioelectric impedance analysis were performed to calculate the FMI and fat-free mass index (FFMI). Serum levels of ghrelin, gastrin, and irisin were measured by ELISA kits according to the manufacturer’s protocol. Results: Compared to the NWL group, gastrin and ghrelin levels were significantly low in the MUO participants, while irisin was significantly high. The EGG showed significantly lower baseline and 20-min normogastria frequencies in the MHO and MUO groups. In the MHO group, baseline duodenal frequency was positively correlated with the gastrin level, while normogastria times were positively associated with the irisin level and negatively associated with the ghrelin level. In the MUO group, percentages of bradygastria frequencies at 10, 20, and 30 min were positively correlated with the BMI and FFMI. This bradygastria was correlated positively with the irisin level and negatively with the ghrelin level. Conclusion: The EGG patterns might be associated with obesity-related gastric hormones in different obesity phenotypes. EGG may be a promising clinical tool in obesity assessment. The association of the EGG patterns with hormonal levels needs further investigation for potential practical uses.

A Power Management Scheme for Grid-connected PV Integrated with Hybrid Energy Storage System

The penetration of renewable energy sources (RESs) in the distribution system becomes a challenge for the reliable and safe operation of the existing power system. The sporadic characteristics of sustainable energy sources along with the random load variations greatly affect the power quality and stability of the system. Hence, it requires storage Systems with both high energy and high power handling capacity to coexist in microgrids. An efficient energy management structure is designed in this paper for a grid-connected PV system combined with hybrid storage of supercapacitor and battery. The combined supercapacitor and battery storage system grips the average and transient power changes, which provides a quick control for the DC-link voltage, i. e., it stabilizes the system and helps achieve the PV power smoothing. The average power distribution between the power grid and battery is done by checking the state of charge (SOC) of a battery, and an effective and efficient energy management scheme is proposed. Additionally, the use of a supercapacitor lessens the current stress on the battery system during unexpected disparity in the generated power and load requirement. The performance and efficacy of the proposed energy management scheme are justified by simulation studies.

Simulation of high-output and lightweight sliding-mode triboelectric nanogenerators

In light of the rapid growth in microelectronic technology, triboelectric nanogenerators (TENGs) have been exploited as securely sustainable substitutes for energy scavenging purposes as well as self-powered sensory utilization. In essence, TENGs’ energy output and average power distribution depend highly on certain key parameters including contact area, the thickness of electric films and external resistance. This study attempts to predict the behavior of TENGs based on variation of those key parameters and tries to optimize the associated characteristics leading to high-output and light-weight sliding-mode TENGs. To meet this problem, an artificial intelligence approach is taken into consideration and solutions for load resistance and geometry are presented. Furthermore, an experimental setup is designed to evaluate the accuracy of the simulation results, demonstrating the precision of the applied theory. The results revealed that the predefined sliding-mode TENG can harvest 0.25 mJ at each cycle in an open-circuit condition where the weight is almost 42.91 g. Moreover, simulation proves that an appropriate value for the external resistor can increase the scavenged energy up to 3.65 mJ at each reciprocal movement. Finally, temporal responses for charge, current, voltage, power output, and harvested energy are plotted and discussed, facilitating understanding of the relationship between scavenged energy and optimized parameters.

Burnup Calculation Study of Pebble Bed Equilibrium Core

Reaktor Daya Eksperimental (RDE) is a high temperature gas-cooled reactor (HTGR) producing a 10 MW thermal with a pebble bed fuels which being developed by BATAN. The purpose of this paper is to study the burnup distribution and characteristic in the equilibrium core for different multipass recirculation method. Understanding the reactor physics, in particular the burnup, is important for optimum design and safety analysis of nuclear reactor. Related with the design approval phase of RDE, this study provides a design data which needed for the RDE’s safety analysis report, e.g. fuel pebble performance analysis. Analysis in this study was performed using PEBBED diffusion code. PEBBED is designed to solve the neutronics and thermalhydraulics parameter cases for high temperature pebble bed reactors for different fuel recirculation including once-through-then-out (OTTO) and multipass scheme. The reactor core calculation was performed by applying multipass scheme with variation from 5 passes up to 15 passes. With energy and power as inputs, the calculations produce the burnup fraction at the end of the cycle and the fast and thermal neutron fluxes in 8 energy groups. The calculation results showed that the lowest 5 passes fuel recirculation pattern has the highest and lowest minimum discharged burnup value. This is related to the average power distribution in the core which means more passes will flatter the burnup distribution including the power distribution and also seen in the value of flux and power peaking factor produced. power peaking factor produced.

Study of a New Quick-Charging Strategy for Electric Vehicles in Highway Charging Stations

To solve the problem, because of which conventional quick-charging strategies (CQCS) cannot meet the requirements of quick-charging for multiple types of electric vehicles (EV) on highways where vehicle inflow is excessive, this paper proposed a new quick-charging strategy (NQCS) for EVs: on the premise of not affecting those EVs being charged, the remaining power of the quick-charging pile with multiple power output interfaces is used to provide a synchronous charging service for EVs waiting in the queue. To verify the effectiveness of this strategy, a power distribution model of charging pile and a queuing model of charging station (CS) were constructed. In addition, based on an actual highway service area where vehicle inflow is excessive during the simulation period (0:00–24:00), charging situations of CQCS and NQCS were respectively simulated in a charging station (CS), with different number of chargers, by basic queuing algorithm and an improved queuing algorithm. The simulation results showed that when the relative EV inflow is excessive, compared to CQCS, NQCS not only can reduce user waiting time, charging time, and stay time, but also can improve the utilisation rate of charging infrastructure and service capacity of CS and reduce the queue length of CS. At the same time, NQCS can reduce the impact on the power grid. In addition, in NQCS, the on-demand power distribution method is more efficient than the average power distribution method. Therefore, NQCS is more suitable for quick-charging for multiple types of EVs on highways where vehicle inflow is excessive.

Oil spill detection method using X-band marine radar imagery

A viable method to implement oil spill detection and monitoring based on marine radar is proposed. The primary data of this study are obtained from the X-band marine radar of the teaching–training ship, YUKUN, of the Dalian Maritime University on July 21, 2010, when a pipeline burst and an oil spill accident occurred at the Xingang Port in Dalian. Aiming at the working characteristics of marine radar, the adaptive median filter algorithm is improved to eliminate the radar shared-frequency interference by adding the identification of noise points and resetting the neighborhood window. A power attenuation correction method is proposed to solve the uneven distribution in resolution and echo intensity by acquiring the average power distribution of radar images simultaneously. Oil spill will be easily detected from different sea backgrounds after morphological processing, gray segmentation, and image smoothing. Comparison with the images extracted from a thermal infrared sensor on the same monitoring point demonstrates the validity of the extraction method for oil spill based on X-band marine radar.

Analysis of the 2-D C5G7 MOX Benchmark with VISWAM Code

The Indian nuclear power programme is being augmented with a variety of imported light water reactors (LWRs). Close interaction between the national labs, plant operators and educational institutions is required to meet the human resource requirements of this program. A neutronics code VISWAM for physics analysis of current and future power reactors is being developed as a part of the above long term goal. The overall plan is to develop a lattice code for generating few group cross sections and a diffusion theory based few group core solver for steady state and transient core calculations. As a first step towards this goal, we have taken up the development of a lattice burnup code. Initially, we used a combination of 1‐D multigroup transport for pincell and supercell calculations and 2‐D few‐group diffusion theory for assembly calculations. Although this method was fast and reasonably accurate for simple fuel assembly designs, we found that the power distribution errors were large in the vicinity of strong absorbers like burnable poison and control rod pins. We improved the solution method by using the 2‐D collision probability (CP) method for calculating the fluxes in each region and currents at each surface of a cell. Adjacent cells are coupled using interface currents at cell boundaries with double P2 (DP2) expansion of angular flux. The advantage of this method is that it can been extended for 2‐D full core solution of the neutron transport equation without spatial homogenization. We tested this code using the OECD/NEA 2‐D C5G7 MOX fuel assembly benchmark. The eigenvalue for the core calculation lies within 0.05% of the reference result. The average power distribution error is less than 1.0%.

LOKET—a gamma-ray spectroscopy system for in-pool measurements of thermal power distribution in irradiated nuclear fuel

An important issue in the operations of nuclear power plants is the independent validation of core physics codes like e.g. Westinghouse PHOENIX-4/POLCA-7. Such codes are used to predict the thermal power distribution down to single node level in the core. In this paper, a dedicated measurement system (LOKET) is described and experimental results are discussed. The system is based on a submergible housing, containing a high-resolution germanium detector, allowing for measurements in-pool. The system can be transported to virtually any nuclear power plant's fuel storage pool for measurements in-pool during outage. The methodology utilises gamma radiation specific for 140La, whose decay is governed by the parent 140Ba, reflecting a weighted average power distribution, representative for the last weeks of operation of the core. Good agreements between measured power distribution and core physics calculations (Ba distribution) have been obtained during a series of experiments at Leibstadt NPP in Switzerland and Cofrentes NPP in Spain (BWRs) for both fuel assemblies and single fuel rods. The system has proven as a very useful tool for the experimental validation of core calculations also for the most complex fuel designs and challenging core configurations. Experimental errors (on the 1− σ level), has been demonstrated below ±2% on nodal level for assembly measurements.

The shut-down of the Barsebäck 1 BWR: A unique opportunity to measure the power distribution in nuclear fuel rods

Reactor poolside measurements of gamma radiation specific for the fission product 140La (1596 keV) have been used for an experimental determination of axial power distributions in 55 nuclear fuel rods irradiated in the Barsebäck 1 BWR nuclear power plant. The measurements take advantage of the unique situation of a very short last reactor cycle of only three months due to the out-phasing of the reactor unit at November 30 1999. 140La whose decay is controlled by the mother nuclide 140Ba with the half-life 12.75 days reflects an average power distribution, representative for the latest weeks of core operation (in this case basically during November 1999). The measured intensities have been transformed into a 25 nodal representation to allow a precise and direct comparison with the corresponding calculated power distribution. The 55 rods were selected from two different fuel assemblies with average burn-ups of 1.9 and 9.7 MWd/kgU, respectively (that is one fresh bundle and one slightly more than one cycle bundle). The stability and the linearity of the measurement system were evaluated. The linearity was checked using the two-source method. The stability was checked by recurrent measurements on a reference fuel rod. The results have been used in the validation of the pin power reconstruction model of Westinghouse 3D core simulator POLCA-7. The deviation between measured and calculated 140Ba concentration (expressed as radial error) is typically a few percent on rod level. Results indicate that also Gd-rods are properly modelled over a broad range of conditions. It is indicated that predictions for fuel rods in their first month of operation are less accurate than for the rest of the rods.

Influence of various shapes of annular metallic support on microwave heating of 2D cylinders

A detailed analysis has been shown to illustrate the influence of various shapes of annular metallic support on microwave heating of 2D cylinders for beef samples. The beef samples are chosen to represent typical food materials with high dielectric loss. A preliminary analysis on microwave heating of samples has been shown via average power within a sample vs cylinder radius diagram in the absence of support and three regimes have been identified such that regimes I ( R = 0.50 cm ) and III ( R = 2 cm ) denote the local minima in average power and regime II ( R = 0.67 cm ) corresponds to a maxima in average power. In addition, regime I corresponds to a spatial maxima in power at the unexposed face, regime II corresponds to maxima in power at both the exposed and unexposed faces and regime III has two maxima at the exposed face and the center of the sample. The influence of support has been illustrated with average power distribution vs aspect ratio ( φ ) diagram. Three types of cross sections of annular supports such as circular (type I), horizontal square (type II) and inclined square (type III) are considered. It has been observed that the average power is enhanced due to the metallic support for φ ⩽ 0.3 . Type I support would correspond larger power distributions and heating rates, for regimes I and II whereas for regime III, the square shaped supports correspond to greater heating rates at larger aspect ratios. The location of spatial maxima in power or heating rate is found to be shifted due to metallic support with high aspect ratios. The shape of the support plays important role on localized heating for the samples corresponding to regime III.

Statistical properties of the field diffracted by an aperture with partially coherent illumination

The statistical properties of the electromagnetic field diffracted by a plane aperture illuminated by a fluctuating field have been studied in the Fresnel zone on the basis of the theory of partial coherence. The average power distribution and the amplitude and phase of the degree of coherence have been computed for several coherence lengths of the illuminating field ranging from 1/4 to 5 times the dimension of the aperture and for two geometries of the observation points. The obtained results indicate the limits of validity of the often assumed hypothesis of spatial stationarity and of the real Gaussian approximation for the degree of coherence of the diffracted field. It turns out also that the optimum position of a receiving phase-sensitive system placed in the field diffracted by an aperture may not be the focus of the aperture, since there the concentration of average power density is accompanied by a poor coherence of the field.

Foreign Language Dubbing

Dubbing, meaning postsynchronization, presents three problems: technicoartistic, technical and artistic. Several solutions are proposed and one universally accepted in Italy is illustrated. A good dubbing recording should match as closely as possible the sound quality expected in connection with the photographic image — resulting studio requirements are listed. Some features characteristic of the Italian language regarding structure of the audio signal, e.g. its average power distribution within the audiofrequency band, are listed and technical provisions to meet resulting requirements are analyzed. Some of the editing techniques adopted in Italy are described.

Voice Measurements with an Audio Spectrometer

The distribution of average power in various speech sounds as a function of frequency has been measured with an integrating audio spectrometer. This instrument divides the electrical signal into 14 frequency bands and simultaneously records the integrated square of the amplitude in each band over a measured time interval, usually 30 seconds. From these data and the known over-all calibration of the spectrometer channels one can compute the spectral distribution of average acoustic power at the location of the input microphone. The operation of the instrument and the procedure of measurement are described. Speech spectra are given which are average results for a trained crew of seven men, speaking into a condenser microphone in an anechoic chamber.

An Integrating Audiospectrometer

Equipment is described which measures the distribution of average power in a complex electrical signal as a function of frequency. The wave form to be studied is separated into 14 frequency bands extending from 20 to 9000 c.p.s. The mean square of the amplitude in each band is integrated and recorded on mechanical counters during a test period of approximately 30 seconds. If a calibrated microphone with a suitable response is used, these analyses will give spectral distributions of average acoustic power. Some examples are shown of measurements of the spectra of speech sounds.