Local Measurement Data Research Articles

A Cooperative Control Algorithm for Multiple SVRs Using Correlation of Measurement Data of Distribution Line

SUMMARYIn this paper, a cooperative control algorithm for multiple step voltage regulator (SVR) using correlation of measurement data of distribution line is proposed. Conventionally, the control time constant of a SVR placed on the feeder end side was set slower than a SVR placed on the substation side. The unnecessary tap movement of SVR was reduced by this setting. In this case, on the condition that “the photovoltaic power generation output of the feeder end fluctuates” and “only SVR of the end side works”, it is a problem that control of SVR becomes slow. By the proposed method, the SVR settled in end side of a feeder can change its tap rapidly only if the SVR settled in sending side of a feeder will not change its tap by using proposed method. The features of the method are followings: (1) to estimate tap change possibility of the sending side SVR using correlation model of both of the SVR, (2) only use local measurement data of the SVRs for tap change control. By the proposed method, unnecessary tap change operation and lag of tap control are reduced without communication networks.

Decentralized State-Observer-Based Traffic Density Estimation of Large-Scale Urban Freeway Network by Dynamic Model

In order to estimate traffic densities in a large-scale urban freeway network in an accurate and timely fashion when traffic sensors do not cover the freeway network completely and thus only local measurement data can be utilized, this paper proposes a decentralized state observer approach based on a macroscopic traffic flow model. Firstly, by using the well-known cell transmission model (CTM), the urban freeway network is modeled in the way of distributed systems. Secondly, based on the model, a decentralized observer is designed. With the help of the Lyapunov function and S-procedure theory, the observer gains are computed by using linear matrix inequality (LMI) technique. So, the traffic densities of the whole road network can be estimated by the designed observer. Finally, this method is applied to the outer ring of the Beijing’s second ring road and experimental results demonstrate the effectiveness and applicability of the proposed approach.

Modelling of Urban Near-Road Atmospheric PM Concentrations Using an Artificial Neural Network Approach with Acoustic Data Input

Air quality assessment is an important task for local authorities due to several adverse health effects that are associated with exposure to e.g., urban particle concentrations throughout the world. Based on the consumption of costs and time related to the experimental works required for standardized measurements of particle concentration in the atmosphere, other methods such as modelling arise as integrative options, on condition that model performance reaches certain quality standards. This study presents an Artificial Neural Network (ANN) approach to predict atmospheric concentrations of particle mass considering particles with an aerodynamic diameter of 0.25–1 μm (PM(0.25–1)), 0.25–2.5 μm (PM(0.25–2.5)), 0.25–10 μm (PM(0.25–10)) as well as particle number concentrations of particles with an aerodynamic diameter of 0.25–2.5 μm (PNC(0.25–2.5)). ANN model input variables were defined using data of local sound measurements, concentrations of background particle transport and standard meteorological data. A methodology including input variable selection, data splitting and an evaluation of their performance is proposed. The ANN models were developed and tested by the use of a data set that was collected in a street canyon. The ANN models were applied furthermore to a research site featuring an inner-city park to test the ability of the approach to gather spatial information of aerosol concentrations. It was observed that ANN model predictions of PM(0.25–10) and PNC(0.25–2.5) within the street canyon case as well as predictions of PM(0.25–2.5), PM(0.25–10) and PNC(0.25–2.5) within the case study of the park area show good agreement to observations and meet quality standards proposed by the European Commission regarding mean value prediction. Results indicate that the ANN models proposed can be a fairly accurate tool for assessment in predicting particle concentrations not only in time but also in space.

A comparison of model performance between ENVI-met and Austal2000 for particulate matter

This study evaluates the performance of the German dispersion model Austal2000 according to the technical instructions on air quality control (TA Luft), a Lagrangian model, in four real-world particulate matter test cases against ENVI-met, a microclimate model featuring a pollutant dispersion module that bases on the Eularian approach. The four test cases include different traffic induced area sources of PM10, complex terrain with varying ground surfaces and different urban obstacles i.e. buildings. A comparison is made between the calculated concentrations of both models. Furthermore, predictions are compared with field data. Particle measurements are conducted with an optical particle counter. For evaluation, quantile-quantile plots as well as further performance measures i.e. the fractional bias and the robust highest concentration that focuses on the important high-end concentrations are applied. Both models underpredicted observed PM(0.25;10) concentrations for all test cases. All datasets show that predictions of both simulation tools were closer to field observations in the high-end concentration range. Model calculation results show mostly better agreement to observations under neutral stability classes of the atmosphere. With the exception of ENVI-met in one test case predictions of simulation runs of both models lead to results closer to observations when initiated with local meteorological measurement data, where wind speed as one of the key drivers of dispersion models was lower. In almost all of the test cases, Austal2000's predictions were closer to the field observations than those of ENVI-met. The latter model undercut predicted PM10 concentrations of Austal2000 by the factor of around two. This evaluation indicates that Austal2000 is the stronger model compared with ENVI-met considering the distribution of PM10 in complex and urban terrain.

Estimating by inverse modeling the release of radioactive substances (133Xe, 131I, and 137Cs) into the atmosphere from Fukushima Daiichi nuclear disaster

The estimate of the release of radioactive substances (133Xe, 131I, and 137Cs) into the atmosphere from the Fukushima Daiichi nuclear disaster is presented. It was obtained using the FLEXPART Lagrangian dispersion model and the data of local ground-based measurements of radiation dose rate. The computation period covers the active phase of the nuclear disaster that lasted 20 days after the tsunami. To get the quantitative characteristics of emissions of radioactive substances, the inverse modeling based on the Bayesian approach is used. The emissions were estimated for three altitudes. The total emissions are equal to 2.1 + 0.4 kg (14 000 + 2700 PBq) for 133Xe, (3.8 + 0.4) x 10-2 kg (174 + + 18 PBq) for 131I, and 5.7 + 1.2 kg (18 + 4 PBq) for 137Cs that is consistent with the results of other studies. Retrieved emissions were used to provide the forward modeling for mapping the areas of radionuclide deposition. The developed method of retrieving the emission of radioactive substances makes a useful instrument that operationally estimates and localizes the areas of potential pollution in case of nuclear accidents and could be used for making decisions on the population evacuation.

局所計測を併用したレーザ干渉計のための新しい分布再構成法の開発

SUMMARY We have developed a novel reconstruction method for a laser interferometer to determine the radial electron density profile in a cylindrical plasma vessel under an axial symmetrical assumption with spline interpolation. This method can extend the reconstructible area out of the line-integrated density measurement area by using the additional local measurement data. Although both the ordinary Abel inversion and the basis function expansion method cannot reconstruct well out of the measurement area, the new method can reconstruct distributions even with nonzero electron density on the wall. In order to confirm the validity of the method, the error sensitivity is evaluated by Monte Carlo simulation.

Experimental study on two-dimensional film flow with local measurement methods

In an accident condition of a nuclear reactor, multidimensional two-phase flows may occur in the reactor vessel downcomer and reactor core. Therefore, those have been regarded as important issues for an advanced thermal-hydraulic safety analysis. In particular, the multi-dimensional two-phase flow in the upper downcomer during the reflood phase of large break loss of coolant accident appears with an interaction between a downward liquid and a transverse gas flow, which determines the bypass flow rate of the emergency core coolant and subsequently, the reflood coolant flow rate. At present, some thermal-hydraulic analysis codes incorporate multidimensional modules for the nuclear reactor safety analysis. However, their prediction capability for the two-phase cross flow in the upper downcomer has not been validated sufficiently against experimental data based on local measurements. For this reason, an experimental study was carried out for the two-phase cross flow to clarify the hydraulic phenomenon and provide local measurement data for the validation of the computational tools. The experiment was performed in a 1/10 scale unfolded downcomer of Advanced Power Reactor 1400 (APR1400). Pitot tubes, a depth-averaged PIV method and ultrasonic thickness gauge were applied for local measurement of the air velocity, the liquid film velocity and the liquid film thickness, respectively. The uncertainty of the depth-averaged PIV method for the averaged velocity of the liquid film was discussed. Also the local velocity profiles of air and liquid film and the liquid film thickness distribution were presented. These local experimental data of two-dimensional film flow which simulated the two-phase cross flow can be used to validate the multidimensional models in the system analysis codes and CFD codes.

Modeling and Stability Analysis of Automatic Generation Control Over Cognitive Radio Networks in Smart Grids

Due to its great potential to improve the overall performance of data transmission with its dynamic and adaptive spectrum allocation capability in comparison with many other networking technologies, cognitive radio (CR) networking technology has been increasingly employed in networking and communication infrastructures for smart grids. However, a secondary user (SU) of a CR network has to be squeezed out from a channel when a primary user reclaims the channel, which may occur in a randomized fashion. The random interruption of SU traffic may cause packet losses and delays for SU data, and it will in turn affect the stability of the monitoring and control of smart grids. In this paper, we address this problem and investigate the modeling and stability analysis of the automatic generation control (AGC) of a smart grid for which CR networks are used as the infrastructure for the aggregation and communication of both system-wide information and local measurement data. For this purpose, a randomly switched power system model is proposed for the AGC of the smart grid. By modeling the CR network as an On–Off switch with sojourn times, the stability of the AGC of the smart grid is analyzed. In particular, we investigate the smart grid with two main types of CR networks: 1) the sojourn times are arbitrary but bounded and 2) the sojourn times follow an independent and identical distribution process. The sufficient conditions are obtained for the stability of the AGC of the smart grid with these two CR networks, respectively. Simulation results show the effects of the CR networks on the dynamic performance of the AGC of the smart grid and illustrate the usefulness of the developed sufficient conditions in the design of CR networks in order to ensure the stability of the AGC of the smart grid.

自端計測情報の相関関係を利用した複数台SVRの協調制御手法の検討

In this paper, a cooperative control algorithm for multiple step voltage regulator (SVR) using correlation of measurement data of distribution line is proposed. Conventionally, the control time constant of a SVR placed on the feeder end side was set slower than a SVR placed on the substation side. The unnecessary tap movement of SVR was reduced by this setting. In this case, on the condition that “the photovoltaic power generation output of the feeder end fluctuates” and “only SVR of the end side works”, it is a problem that control of SVR becomes slow. By the proposed method, the SVR settled in end side of a feeder can change its tap rapidly only if the SVR settled in sending side of a feeder will not change its tap by using proposed method. The features of the method are followings: (1) to estimate tap change possibility of the sending side SVR using correlation model of both of the SVR, (2) only use local measurement data of the SVRs for tap change control. By the proposed method, unnecessary tap change operation and lag of tap control are reduced without communication networks.

Optimal Sensor Power Scheduling for State Estimation of Gauss–Markov Systems Over a Packet-Dropping Network

We consider sensor power scheduling for estimating the state of a general high-order Gauss-Markov system. A sensor decides whether to use a high or low transmission power to communicate its local state estimate or raw measurement data with a remote estimator over a packet-dropping network. We construct the optimal sensor power schedule which minimizes the expected terminal estimation error covariance at the remote estimator under the constraint that the high transmission power can only be used m <; T + 1 times, given the time-horizon from k = 0 to k = T. We also discuss how to extend the result to cases involving multiple power levels scheduling. Simulation examples are the provided to demonstrate the results.

Prediction of Falling Solids Film Thickness near the Wallin Circulating Fluidized Bed Risers

The solid particles distribution in circulating fluidized beds (CFB) has been extensively studied because of its importance in the design of CFB boilers and reactors. The previous studies report that in the circulating fluidized beds, the solids near the wall move down ward as a film with axial variable thickness. Therefore, it is very important to predict solids film thickness near the wall to estimate the heat transfer between a solid suspension in the bed and wall surface. In the present paper, an expression for the local solids film thickness has been suggested from the data of local solids flux measurements by using U-tube probe. The data measured in two laboratory scale CFB units which consist of 0.0508m diameter & 3 m height and 0.1016m diameter & 6m height. Sand (182 µm and 2560 kg//m3) and FCC particles (99 µm and 1600 kg/ m3) are used as bed material. The operating gas velocity and solid circulation rates are in the range of 1-6m/s and 5-125kg/m2-s respectively for the material considered. The R2 values for the correlation developed are 0.577 for literature data, 0.3904 for small column (0.0508m ID & 4m Height) and 0.886 for large column (0.1016m ID & 6m height).

Power System Voltage Stability Classification Using Interior Point Method Based Support Vector Machine(IPMSVM)

This paper present same thodology for the classification of power system voltage stability, the trajectory of which to instability is monotonic, using an interior point method based support vector machine(IPMSVM). The SVM based voltage stability classifier canp rovide real-time stability identification only using the local measurement data, without the topological information conventionally used.

Molecular Dynamic Studies on Deformation of Polymer Resist During Thermal Nano Imprint Lithographic Process

Molecular dynamic simulation of nano imprint lithography (NIL) in which nanoscale patterned stamp is pressed onto amorphous polyethylene (PE) surface is performed to study the deformation behavior of polymer resist. Force fields including bond, angle, torsion, and Lennard Jones potential are used to describe the inter-molecular and intra-molecular forces of PE molecules and stamp. Periodic boundary condition is used in horizontal direction and canonical NVT ensemble is employed to control the system temperature. Using the simulation results, the behavior of polymer resist is investigated during the imprinting process. The mechanism of resist deformation is analyzed by considering various parameters including the surface geometry, atom distribution, and density. Especially, the density in the bottom (emboss) region is found to be larger than the top (cavity) region due to compression of polymer molecules. The result indicates that small scale patterning of polymer resist largely depends on compression rather than the flow of molecules. The numerical results are compared with the local density measurement data using the atomic force microscope (AFM). They exhibit a similar behavior at least in a qualitative sense. Additional simulations, where the stamp geometry and molecular mobility are varied and are performed to investigate the deformation characteristics of polymer resist. From these simulations, important elements for understanding of NIL process are obtained.

The Heat/Mass Transfer Analogy for a Simulated Turbine Endwall With Fillets

Mass transfer measurements are employed as alternative methods for heat transfer measurement because of the difficulty of heat transfer measurements in thin boundary layers, complicated secondary flows, and large thermal gradients. Even though mass transfer experiments are fast and show detailed local measurement data, the conversion of mass transfer results to heat transfer data requires the heat/mass transfer analogy factors in detail. Therefore, the usefulness of mass transfer data depends on finding a simple analogy factor. The heat/mass transfer analogy on a simulated turbine endwall with fillets is evaluated in the present paper. Since the heat/mass transfer analogy factor may not be always the same, the heat/mass transfer analogy should be verified for other different geometries and experimental conditions. To utilize the heat/mass transfer analogy fully, it is necessary to check that the presence of different aerodynamic conditions caused by the fillets affects the heat/mass transfer analogy on a simulated turbine endwall with fillets. To compare heat transfer data and mass transfer data, heat transfer measurements on the endwall with fillets are conducted with a thermal boundary layer measurement technique and mass transfer measurements employing naphthalene sublimation technique on the endwall with the fillets are extracted from literature with equivalent experimental conditions and a similar geometry. As expected by heat transfer and mass transfer equations, the heat/mass transfer analogy factor is applied and shows a good agreement between heat transfer and mass transfer results on the endwall with the fillets from the leading edge to the trailing edge.

A method for retrieving soil moisture in Tibet region by utilizing microwave index from TRMM/TMI data

According to simulation analysis of the advanced integral equation model (AIEM), there is a good linear relationship between emissivity and soil moisture under conditions of given roughness. The normalized difference of emissivities at 19.35 GHz and 10.65 GHz with vertical polarization can partly eliminate the influence of roughness and the squared correlation coefficient is about 0.985. This paper uses the normalized brightness temperature for retrieving soil moisture in Tibet from TRMM/TMI data. This method avoids parametrizing the land surface temperature which is a key parameter for the computation of emissivity. We make some sensitivity analysis for the atmosphere which is the main influence factor for our method. The analysis results indicate that our method is very good for clear days but is not very good when there is rainfall. We evaluate our algorithm by using the ground truth data obtained from GAME‐Tibet and the retrieval error of soil moisture is about 0.04m3 m−3 relative to experimental data. The analysis indicates that the relationship obtained from the theoretical model should be revised through the local ground measurement data because the method is still influenced by roughness and vegetation. After making a regression revision, the retrieval error of soil moisture is under 0.02m3 m−3. Finally, we retrieve the soil moisture in Tibet from TRMM/TMI data, and the distribution trend of retrieval results is consistent with the real world.

Internal deformation behavior of geosynthetic-reinforced soil walls

Local deformation of geosynthetics, such as geogrids, and nonwoven and woven geotextiles, was measured to analyze the stability of geosynthetic-reinforced soil (GRS) structures. To analyze the deformation behavior of geosynthetics applied to a reinforced soil structure, the tensile load–elongation properties of the geosynthetic and local deformation measurement data are required. However, local deformation of nonwoven geotextile (NWGT), which is permeable, is difficult to measure with strain gauges. This study proposes a new, more convenient, method to measure the deformation behavior of NWGTs using a strain gauge and examines its suitability via laboratory tests and field trials on two GRS walls. A wide-width tensile test, conducted under a confining pressure of 70 kPa, showed that local deformation of NWGT, measured with strain gauges of type AE-11-S80N-120-EL, was similar to total deformation measured with linear variable deformation transformer (LVDT). In field trials, NWGT showed a larger deformation range than woven geotextile or geogrid. However, the deformation patterns of the three materials were similar. The strain gauges attached to NWGT in the walls worked normally for 16 months. Therefore, the method proposed in this study for measuring NWGT deformation using a strain gauge was effective and valuable. Pore water pressure in the GRS wall can be ignored since the backfill remains unsaturated regardless of rainfall. However, it should be noted for design purposes that horizontal earth pressures at the wall face are greater at the bottom and top of the wall than at rest.

GIS management of solar resource data

This paper employs a geographical information system (GIS) to map solar resources on the basis of satellite data (radiation at top of the atmosphere, albedo, downward radiation at surface) and to match it with demand modelling on a habitat basis (population density, energy demand intensity). PV potential use is based on estimates of practical areas for collection use (building roof areas, suitably inclined and oriented surfaces) combined with land use data (important for central receiver fields). Local measurement data have been converted to the GIS grid employed. This is a novel approach compared to previous assessment, planning and scenario work in the photovoltaic field, which has traditionally been country based.

Comparative atmospheric dynamics for terrestrial planets

A review is presented of theoretical ideas on the general circulations in the atmospheres of Earth, Mars and Venus and also of results of their theoretical modelling. The role of various factors is discussed in the formation of the circulations. These results are compared with observational data obtained by different means. Data of direct local measurements of meteorological parameters in the atmospheres of Venus and Mars are discussed including those obtained at their surfaces.