Enhancing microseismic/acoustic emission source localization accuracy with an outlier-robust kernel density estimation approach

Monitoring sensors in complex engineering environments often record abnormal data,leading to significant positioning errors.To reduce the influence of abnormal arrival times,we introduce an innovative,outlier-robust localization method that integrates kernel density estimation(KDE)with damping linear correction to enhance the precision of microseismic/acoustic emission(MS/AE)source positioning.Our approach systematically addresses abnormal arrival times through a three-step process:initial location by 4-arrival combinations,elimination of outliers based on three-dimensional KDE,and refinement using a linear correction with an adaptive damping factor.We validate our method through lead-breaking experiments,demonstrating over a 23%improvement in positioning accuracy with a maximum error of 9.12 mm(relative error of 15.80%)—outperforming 4 existing methods.Simulations under various system errors,outlier scales,and ratios substantiate our method’s superior performance.Field blasting experiments also confirm the practical applicability,with an average positioning error of 11.71 m(relative error of 7.59%),compared to 23.56,66.09,16.95,and 28.52 m for other methods.This research is significant as it enhances the robustness of MS/AE source localization when confronted with data anomalies.It also provides a practical solution for real-world engineering and safety monitoring applications.

Effects of sonic speed on location accuracy of acoustic emission source in rocks

To quantitatively study the location errors induced by deviation of sonic speed, the line and plane location tests were carried out. A broken pencil was simulated as acoustic emission source in the rocks. The line and plane location tests were carried out in the granite rod using two sensors and the cube of marble using four sensors, respectively. To compare the position accuracy between line and plane positions, the line poison test was also carried out on the marble surface. The results show that for line positioning, the maximum error of absolute distance is about 0.8 cm. With the speed difference of 200 m/s, the average value of absolute difference from the position error is about 0.4 cm. For the plane positioning, in the case of the sensor array of 30 cm, the absolute positioning distance is up to 8.7 cm. It can be seen that the sonic speed seriously impacts on the plane positioning accuracy. The plane positioning error is lager than the line positioning error, which means that when the line position can satisfy the need in practical engineering, it is better to use the line position instead of the plane location. The plane positioning error with the diagonal speed is the minimum one.

Acoustic emission source identification based on harmonic wavelet packet and support vector machine

In order to solve the fatigue damage identification problem of helicopter moving components, a new approach for acoustic emission （AE） source type identification based on the harmonic wavelet packet （HWPT） feature extraction and the hierarchy support vector machine （H-SVM） classifier is proposed. After a four-level decomposition of the HWPT, the energy feature of AE signals in different frequency bands is extracted, which overcomes the shortcomings of the traditional wavelet packet including energy leakage, and inflexible frequency band selection and different frequency resolutions on different levels. The H-SVM classifier is trained with a subset of the experimental data for known AE source types and tested using the remaining set of data. The results of pressure-off experiments on the specimens of carbon fiber materials indicate that the proposed approach can effectively implement the AE source type identification, and has a better performance in terms of computational efficiency and identification accuracy than the wavelet packet （WPT） feature extraction.

Effects of NO_x and VOCs from Five Emission Sources on Summer Surface O_3 over the Beijing–Tianjin–Hebei Region

The impacts of emissions from industry,power plant,transportation,residential,and biogenic sources on daily maximum surface ozone （O3DM） over the Beijing-Tianjin-Hebei （BTH） region in North China in the summer of 2007 were examined in a modeling study.The modeling system consisted of the Weather Research and Forecasting （WRF） model and the photochemical dispersion model,CAMx.The factor separation technique （FST） was used to quantify the effect of individual emission source types and the synergistic interactions among two or more types.Additionally,the effectiveness of emission reduction scenarios was explored.The industry,power plant,and transportation emission source types were found to be the most important in terms of their individual effects on O3DM.The key contributor to high surface O3 was power plant emissions,with a peak individual effect of 40 ppbv in the southwestern BTH area.The individual effect from the biogenic emission category was quite low.The synergistic effects from the combinations of each pair of anthropogenic emission types suppressed O3 formation,while the synergistic effects for combinations of three were favorable for O3 formation when the industrial and power plant emission source types coexisted.The quadruple synergistic effects were positive only with the combination of power plant,transportation,residential,and biogenic sources,while the quintuple synergistic effect showed only minor impacts on O3DM concentrations.A 30％ reduction in industrial and transportation sources produced the most effective impacts on O3 concentrations,with a maximum decrease of 20 ppbv.These results suggested that the synergistic impacts among emission source types should be considered when formulating emission control strategies for O3 reduction.

Gross nitrogen transformations and N2O emission sources in sandy loam and silt loam soils

The soil type is a key factor influencing N(nitrogen)cycling in soil;however,gross N transformations and N_(2)O emission sources are still poorly understood.In this study,a laboratory 15N tracing experiment was carried out at 60%WHC(water holding capacity)and 25℃to evaluate the gross N transformation rates and N_(2)O emission pathways in sandy loam and silt loam soils in a semi-arid region of Heilongjiang Province,China.The results showed that the gross rates of N mineralization,immobilization,and nitrification were 3.60,1.90,and 5.63 mg N/(kg·d)in silt loam soil,respectively,which were 3.62,4.26,and 3.13 times those in sandy loam soil,respectively.The ratios of the gross nitrification rate to the ammonium immobilization rate(n/ia)in sandy loam soil and silt loam soil were all higher than 1.00,whereas the n/ia in sandy loam soil(4.36)was significantly higher than that in silt loam soil(3.08).This result indicated that the ability of sandy loam soil to release and conserve the available N was relatively poor in comparison with silt loam soil,and the relatively strong nitrification rate compared to the immobilization rate may lead to N loss through NO_(3)–leaching.Under aerobic conditions,both nitrification and denitrification made contributions to N_(2)O emissions.Nitrification was the dominant pathway leading to N_(2)O production in soils and was responsible for 82.0%of the total emitted N_(2)O in sandy loam soil,which was significantly higher than that in silt loam soil(71.7%).However,the average contribution of denitrification to total N_(2)O production in sandy loam soil was 17.9%,which was significantly lower than that in silt loam soil(28.3%).These results are valuable for developing reasonable fertilization management and proposing effective greenhouse gas mitigation strategies in different soil types in semiarid regions.

Azimuthal distributions of final-state particles and fragments and transverse structure of emission source in high-energy nucleus-nucleus collisions

The azimuthal distributions of final-state particles and fragments produced in high-energy nucleus-nucleus collisions are described by a modified multisource ideal gas model which contains the expansions and movements of the emission sources. The transverse structures of the sources are given in the transverse plane by momentum components Px and Py, and described by parameters in the model. The results of the azimuthal distributions, calculated by the Monte Carlo method, are in good agreement with the experimental data in nucleus-nucleus collisions at high energies.

Loss prediction of three-level amplified spontaneous emission sources in radiation environment

A model of three-level amplified spontaneous emission(ASE)sources,considering radiation effect,is proposed to predict radiation induced loss of output power in radiation environment.Radiation absorption parameters of ASE sources model are obtained by the fitting of color centers generation and recovery process of gain loss data at lower dose rate.Gain loss data at higher dose is applied for self-validating.This model takes both the influence of erbium ions absorption and photon bleaching effect into consideration,which makes the prediction of different dose and dose rate more accurate and flexible.The fitness value between ASE model and gain loss data is 99.98%,which also satisfies the extrapolation at the low dose rate.The method and model may serve as a valuable tool to predict ASE performance in harsh environment.

Development of a procedure for estimating the parameters of mechanistic VOC emission source models from chamber testing data

In order to evaluate the impacts of volatile organic compounds(VOCs)emissions from building materials on the indoor air quality beyond the standard chamber test conditions and test period,mechanistic emission source models have been developed in the past.However,very limited data are available for the required model parameters including the initial concentration(C_(m0)),in-material diffusion coefficient(D_(m)),partition coefficient(Kma),and convective mass transfer coefficient(k_(m)).In this study,a procedure was developed for estimating the model parameters by using VOC emission data from standard small chamber tests.In the procedure,initial values of the model parameters were refined by multivariate regression analysis of the measured emission data.To verify the procedure and estimate its uncertainty,simulated chamber test data were generated by adding 10% experimental uncertainties on the theoretical curve from the analytical solution to a mechanistic emission model.Then the procedure was applied to the generated data to estimate the model parameters.Results indicated that estimates converged to the original parameter values used for the data generation and the error of estimated parameters D_(m1)C_(m0) and K_(ma) were within±10%,±23%,and±25%of the true values,respectively.The procedure was further demonstrated by applying it to estimate the model parameters from real chamber test data.Wide application of the procedure would result in a database of mechanistic source model parameters for assessing the impact of VOC emissions on indoor pollution load,which are essential input data for evaluating the effectiveness of various indoor air quality(IAQ)design and control strategies as well as the energy required for meeting given IAQ requirements.

Spatial distribution of health risks for residents located close to solvent-consuming industrial VOC emission sources

Emissions derived from the consumption of organic solvents have been proven to be the primary industrial source of volatile organic compounds(VOCs).In conjunction with epidemiologic studies, water-based paints(WBPs) and solvent-based paints(SBPs) were selected as representatives of newly developed solvents and traditional solvents, respectively,to simulate the effects of consuming solvents emitted during industrial production.And non-carcinogenic and carcinogenic risks to residents near emission sources were studied in detail.The results showed that the spatial distribution of health risks varied with meteorological conditions and type of emission source, and the prevailing wind direction strongly affected the distribution range and shape of the influenced area.The areas of influence maximized on heavy-polluting days for both WBP and SBP emission sources with the total span reaching 804 m and 16 km, respectively;meanwhile, the areas of influence for carcinogenic risk resulting from WBP emission sources were 1.2 and 2.3 times greater than those measured on fine and rainy days, respectively, and 1.8 and 2.9 times greater for SBP emission sources.Compared with WBPs, the total spans of negatively influenced regions resulting from SBP emission sources were 10.4, 12.5 and 19.9 times greater on fine, rainy and heavypolluting days, respectively.Therefore, carcinogenic risk was the dominant health threat for populations residing close to solvent-consuming industrial emission sources.The findings suggest that newly developed solvents are capable of significantly reducing consequent health threats, nevertheless, they could still pose occasional threats to nearby residents under specific meteorological conditions.

Feature analysis of acoustic emission sources for rail crack detection by the finite element method

The safety of rail is very important for the development of high speed railway, and it is necessary to investigate the features of inner cracks in rail. In order to obtain the features of Acoustic Emission （AE） sources of inner cracks in rail, AE sources with different types, depths and propagation distances are examined for crack in rail. The finite element method is utilized to model the rail with cracks and the results of experiment demonstrate the effectiveness of this model. Wavelet transform and Rayleigh-Lamb equations are utilized to extract the features of crack AE sources. The results illustrate that the intensity ratio among AE modes can identify the AE source types and the AE sources with different frequencies in rail. There are uniform AE mode features existing in the AE signals from AE sources in rail web, however AE signals from AE sources in rail head and rail base have the complex and unstable AE modes. Different AE source types have the different propagation features in rail. It is helpful to understand the rail cracks and detect the rail cracks based on the AE technique.

Compilation of Emission Inventory of Air Pollution Sources in Beijing and Suggestions on Emission Reduction Policies

By establishing emission inventory of air pollution sources in Beijing,and classifying and compiling the pollutant types and corresponding pollution source data in more detail,it could provide the reference for studying causes of haze and related policy impact assessment in Beijing.In this paper,selecting relevant data published in the Beijing Statistical Yearbook,referring to emission coefficients in the technical guidelines for the preparation of various pollution sources,and combining characteristics of energy consumption in Beijing,emission inventory of air pollution sources in six parts is established:thermal power plant,industrial combustion source(by industry),technological process source(by product variety),motor vehicle,building construction and residents life,and the contribution rate of each part to air pollutants is given.Finally,policy suggestions for haze control in Beijing are put forward.

Optimal reduction of anthropogenic emissions for air pollution control and the retrieval of emission source from observed pollutantsⅢ:Emission source inversion using a double correction iterative method

Using the incomplete adjoint operator method in part I of this series of papers,the total emission source S can be retrieved from the pollutant concentrationsρob obtained from the air pollution monitoring network.This paper studies the problem of retrieving anthropogenic emission sources from S.Assuming that the natural source Sn is known,and as the internal source Sc due to chemical reactions is a function of pollutant concentrations,if the chemical reaction equations are complete and the parameters are accurate,Sc can be calculated directly fromρob,and then Sa can be obtained from S.However,if the chemical reaction parameters(denoted asγ)are insufficiently accurate,bothγand Sc should be corrected.This article proposes a"double correction iterative method"to retrieve Sc and correctγand proves that this iterative method converges.

A Temperature-Insensitive Amplified Spontaneous Emission Broadband Source Based on Er-Doped Fiber

To obtain a stable amplified spontaneous emission（ASE） source for complex environment applications, we design an ASE source and study the output power and spectral characteristics under different ambient temperatures.We optimize the structure of the ASE source to flatten the ASE spectrum, and study the output characteristics in terms of output power and optical spectrum under different pump powers. Then the performance of the ASE source is investigated in the temperature range from-18.9°C to 50°C. A stable-power and flat-spectrum ASE source can be obtained by structural optimization and pump control.

Concentrations and isotopic characteristics of atmospheric reactive nitrogen around typical sources in Beijing,China

With rapid economic growth in China, anthropogenic reactive nitrogen （Nr） emissions have more than doubled over the last two or three decades. Atmospheric Nr pollution is an environmental concern in China especially in megacities such as Beijing. In order to identify the impact of emission sources on atmospheric Nr pollution, we measured atmospheric Nr concentrations and their isotopic composition （δ15N） dynamics at three typical sites： landfill, pig farm and road traffic sites in Beijing from April 2010 to March 2011. Passive samplers were used for monitoring ammonia （NH3） and nitrogen dioxide （NO2）, two major Nr species, while their δ15N values were measured by a diffusion method combined with mass spectrometer approach. The raw water pool of the landfill and fattening house of the pig farm were important NH3 sources with mean NH3 concentrations being 2,829 and 2,369 μg/m3, respectively, while the road traffic site was a minor NH3 source （10.6 μg/m3）. NH3 concentrations at sites besides the landfill and roads were high in summer and low in winter due to the annual variation of temperature and the change of emission source intensity. In contrast, the NH3 concentrations inside the pig farm house were high in winter and low in summer, for the barn windows were open in summer and closed in winter. The mean NO2 concentrations were 89.8, 32.9 and 23.0 μg/m3 at the road traffic, the landfill and pig farm sites, respectively. Due to vehicle fuel combustion, NO2 concentration at the road traffic was the highest among the three sources, and the road traffic was a main NO2 emission source. PM10, pNH4＊ and pNO3- concentrations in particulate matter were higher in summer than in winter （except PM10 for the pig farm）. The δ15NH3 values ranged from -19.14‰ to 7.82‰, with an average of-0.05‰ for the landfill site, and the lowest values were observed in June and July. The δ15NH3 values for the pig farm site ranged from -29.78‰ to-14.05‰ with an average of-24.51‰, and the 515NH3 values were more negative in summer than in the other seasons. The （515NO2 values were -9.63%o to 7.04‰ with an average of -3.72%0 for the road traffic site. The δ15NO2 values were more negative in summer than those in the other seasons. The different δ15N values for the various Nr species in different sources may serve as important indicators for identifying atmospheric Nr sources in megacities. The results may also provide the theoretical basis for research on the atmospheric N deposition and its sources.

Estimation of greenhouse gas emissions in China and the abatement measures

The major emission sources of carbon dioxide, methane, nitrous oxide and CFCs in China have been identified, and the emission trends has been estimated. Besides fossil fuel combustion, human respiration and biomass burning are important sources. Some feasible abatement measures on energy conservation, afforestation and biomass recycling have been discussed.

Chance-constrained programming (CCP)abatement of SO_2 emission for acid deposition control in Liuzhou City

A deterministic linear programming model which optimizes the abatement of each SO2 emission source, is extended into a CCP form by introducing equations of probabilistic constrained through the incorporation of uncertainty in the source-receptor-specific transfer coefficients. Based on the calculation of SO2 and sulfate average residence time for Liuzhou City, a sulfur deposition model has been developed and the distribution of transfer coefficients have been found to be approximately log-normal. Sulfur removal minimization of the model shows that the abatement of emission sources in the city is more effective, while control cost optimization provides the lowest cost programmes for source abatement at each allowable deposition limit under varied environmental risk levels. Finally a practicable programme is recommended.

Analysis of Effects of the Arc Voltage on Arc Discharges in a Cathode Ion Source of Neutral Beam Injector

A hot cathode bucket ion source is used for the EAST（experimental advanced superconducting tokamak）neutral beam injector.The thermal electrons emitted from the surface of the cathode are extracted and accelerated by the electric field formed by the arc voltage,which is applied between the arc chamber of the ion source and the cathode.This paper analyzes the effects of arc voltage on the arc discharge in a hot cathode high current ion source.

Valuations of Elemental Concentrations of Particle Matter in Ulaanbaatar, Mongolia

This study focused on the contents of the air particulate matter pollution in two districts of Ulaanbaatar and determined the chemical composition of air borne samples and the source of those particles. Samples of fine and coarse fractions of PM were collected using a “Gent” stacked filter unit in two fractions of 0 - 2.2 μm and 2.2 - 10 μm sizes in two semi-residential areas from September 2012 to August 2013. This paper points out that fine and coarse concentration varied seasonally with meteorological changes. In sampling site 3, Zuun Ail (Figure 1) combustion generators generate the majority of pollution around 50.6% of household waste furnace to create high-temperature combustion of 21.6%. However, this net contributes to soil contamination near the lower value (5%) that arises around the vacuum environment in substantial amounts (14%), where is open around the buildings and residential areas, and the soil is considered to be due to the construction. But the data point to the highway in the distance, where is 9% of contamination of all vehicles’ smoke, and exhaust is similar to the data collected in Ulaanbaatar. According to analysis of samples of Nuclear Research Center (NRC) sampling site 2, it shows burning source of Particulate Matter 2.5 pollution in the air is around 25.5% of household waste furnace to create high-temperature product of combustion. But here the very high net contribution to the pollution of soil, is 31.6%. Today’s emerging dust is around 15.2%, showing that motor vehicle pollution causes 19.7%. Since the analysis was done on a sample-by-sample basis, it is possible to estimate the daily contributions of pollution sources and provide useful information based on a limited number of samples in order to address air quality management issues in Ulaanbaatar.

An integrated chemical mass balance and source emission inventory model for the source apportionment of PM2.5 in typical coastal areas

The source apportionment of PM2.5 is essential for pollution prevention.In view of the weaknesses of individual models,we proposed an integrated chemical mass balancesource emission inventory(CMB-SEI)model to acquire more accurate results.First,the SEI of secondary component precursors(SO2,NOx,NH3,and VOCs)was compiled to acquire the emission ratios of these sources for the precursors.Then,a regular CMB simulation was executed to obtain the contributions of primary particle sources and secondary components(SO4^2-,NO3^-3,NH4^+,and SOC).Afterwards,the contributions of secondary components were apportioned into primary sources according to the source emission ratios.The final source apportionment results combined the contributions of primary sources by CMB and SEI.This integrated approach was carried out via a case study of three coastal cities(Zhoushan,Taizhou,and Wenzhou;abbreviated WZ,TZ,and ZS)in Zhejiang Province,China.The regular CMB simulation results showed that PM2.5 pollution was mainly affected by secondary components and mobile sources.The SEI results indicated that electricity,industrial production and mobile sources were the largest contributors to the emission of PM2.5 gaseous precursors.The simulation results of the CMB-SEI model showed that PM2.5 pollution in the coastal areas of Zhejiang Province presented complex pollution characteristics dominated by mobile sources,electricity production sources and industrial production sources.Compared to the results of the CMB and SEI models alone,the CMB-SEI model completely apportioned PM2.5 to primary sources and simultaneously made the results more accurate and reliable in accordance with local industrial characteristics.

Source mechanism of acoustic emission produced by pitting corrosion

Studies have been made on the source mechanism of acoustic emission produced by pitting corrosion. Methods for identifying pitting corrosion-related AE signals were proposed and the magnitude of surface displacement due to single pitting was estimated. It is concluded that differentiation between background noise and corrosion induced genuine AE signal is possible through using plate wave acoustic emission theory combined with parameter analysis method.