Identification Index Research Articles

A new index for damage identification in beam structures based on modal parameters

A new index for damage identification in beam structures based on modal parameters

Spatiotemporal Characteristics of the Water Quality and Its Multiscale Relationship with Land Use in the Yangtze River Basin

The spatiotemporal characteristics of river water quality are the key indicators for ecosystem health evaluation in basins. Land use patterns, as one of the main driving forces of water quality change, affect stream water quality differently with the variations in the spatiotemporal scales. Thus, quantitative analysis of the relationship between different land cover types and river water quality contributes to a better understanding of the effects of land cover on water quality, the landscape planning of water quality protection, and integrated water resources management. Based on water quality data of 2006–2018 at 18 typical water quality stations in the Yangtze River basin, this study analyzed the spatial and temporal variation characteristics of water quality by using the single-factor water quality identification index through statistical analysis. Furthermore, the Spearman correlation analysis method was adopted to quantify the spatial-scale and temporal-scale effects of various land uses, including agricultural land (AL), forest land (FL), grassland (GL), water area (WA), and construction land (CL), on the stream water quality of dissolved oxygen (DO), chemical oxygen demand (CODMn), and ammonia (NH3-N). The results showed that (1) in terms of temporal variation, the water quality of the river has improved significantly and the tributaries have improved more than the main rivers; (2) in the spatial variation respect, the water quality pollutants in the tributaries are significantly higher than those in the main stream, and the concentration of pollutants increases with the decrease of the distance from the estuary; and (3) the correlation between DO and land use is low, while that between NH3-N, CODMn, and land use is high. CL and AL have a negative effect on water quality, while FL and GL have a purifying effect on water quality. In particular, AL and CL have a significant positive correlation with pollutants in water. Compared with NH3-N, CODMn has a higher correlation with land use at a larger scale. The results highlight the spatial scale and seasonal dependence of land use on water quality, which can provide a scientific basis for land management and seasonal pollution control.

How environmental stress leads to alternative microbiota states in a river ecosystem: A new insight into river restoration

Catastrophic shifts in river ecosystems can abruptly degrade their structures and functions, often reducing the efficacy of traditional remediation targeting physicochemical properties. Alternative stable states theory can not only explain this phenomenon but also provide a new insight into river restoration; however, little is known about the existence and implications of alternative stable states in a river. Considering the important role of benthic microbiota in sustaining river ecosystem structures and functions, ecological theory and high-throughput sequencing were combined to firstly investigate multi-stability in microbial communities and its relationship with environmental factors in river sediments. The Nanjing reach of the Yangtze River was selected as the study area because of its huge spatial heterogeneity and varying degrees of pollution. Bimodal distributions combined with temporal variations of microbiota status provided direct evidence of bistability by showing the instability at the intermediate. In addition, environmental stress, particularly concentrations of NH4+−N and NO3−−N, was identified as an important driver of alternative microbiota states from the perspectives of the behavior of bistable ecosystems. Comparison of α-diversity indices and network properties between two alternative microbiota states revealed that the diversity and co-occurrence pattern of microbial communities will be high if they are settled in favorable environments (i.e., comprehensive sediment quality identification index > 3.7). Key taxa, including Clostridiales, Nitrospirales and Myxococcales, were discerned by combining LEfSe and network analysis, and their strong interspecies interactions were believed to be an important factor in triggering alternative microbiota states. This study suggests alternative stable states theory should be considered in river remediation to better understand the response of river ecosystems to environmental stress and the effect of hysteresis, benefiting the implementation of effective monitoring and restoration strategies in a river of urban area.

A Novel Two-Stage Structural Damage Identification Method Based on Superposition of Modal Flexibility Curvature and Whale Optimization Algorithm

A novel two-stage method is proposed to properly identify the location and severity of damage in plate structures. In the first stage, a superposition of modal flexibility curvature (SMFC) is adopted to locate the damage accurately, and the identification index of modal flexibility matrix is improved. The low-order modal parameters are used and a new column matrix is formed based on the modal flexibility matrix before and after the structure is damaged. The difference of modal flexibility matrix is obtained, which is used as a damage identification index. Meanwhile, based on SMFC, a method of weakening the “vicinity effect” is proposed to eliminate the impact of the surrounding elements to the damaged elements when damage identification is carried out for the plate-type structure. In the second stage, the objective function based on the flexibility matrix is constructed, and according to the damage location identified in the first stage, the actual damage severity is determined by the enhanced whale optimization algorithm (EWOA). In addition, the effects of 3% and 10% noise on damage location and severity estimation are also studied. By taking a simply supported beam and a four-side simply supported plate as examples, the results show that the method can accurately estimate the damage location and quantify the damage severity without noise. When considering noise, the increase of noise level will not affect the assessment of damage location, but the error of quantifying damage severity will increase. In addition, damage identification of a steel-concrete composite bridge (I-40 Bridge) under four damage cases is carried out, and the results show that the modified method can evaluate the damage location and quantify 5%–92% of the damage severity.

Temporal and Spatial Variation of water quality in the Yongding River Basin

For exploring the water quality and macroinvertebrate community characteristics of the Yongding River Basin, investigation of water environment and macroinvertebrates was conducted in 34 sampling sites in August 2016 and April 2017. Furthermore, Water Quality Index (WQI) and biological index (BI) were used to assess the water quality of studied rivers. According to the water quality evaluation results of the WQI and the BI method, the water quality of most sites in non-flood season were equal to or better than those in flood season, and these sites were mostly located in urban area. The dominant land use and non-point source pollution was the primary contributor to water quality degradation in rural areas. There are both similarities and differences between BI index and water quality identification index. From the evaluation results of Sanggan River, Yanghe River and Yongding River, the water quality of Yanghe River is better than that of Sanggan River and Yongding River.

Water quality assessment and pollution source analysis of Yaojiang River Basin: a case study of inland rivers in Yuyao City, China

Abstract To fully understand the water quality status of the Yuyao section in the Yaojiang River Basin, we utilized the single factor and comprehensive water quality identification index methods, as well as factor analysis in this study. The single factor water quality assessment results showed that the common parameters exceeding the standard in both the wet and dry seasons included dissolved oxygen and total nitrogen, which were inferior to the target water quality grade III by 1–6 grades. The comprehensive water quality order reaching the target grade III was Hutang River (87.5%), Changling River (50.0%), Yaojiang River (43.8%), and Linzhou River (37.5%). The comprehensive water quality in the dry season (90.0% standard-achieving rate) was better than that in the wet season (25.0% standard-achieving rate). These results suggested that the surface runoff might considerably impact water quality. The factor analysis results showed that the basin surveyed in 2018 was mainly polluted by urban sewage and agricultural sources, while the primary pollution source in 2019 was agricultural pollution. Integrated with comprehensive water quality assessment results, in this study, we demonstrated that the series of water treatment projects carried out in Yuyao City positively impacted municipal sewage treatment.

Correlation Analysis of Landscape Structure and Water Quality in Suzhou National Wetland Park, China

The newly issued “Guideline of General Planning of Wetland Parks”, China, reclassified the functional zoning of national wetland parks into three categories: conservation areas, restoration and reconstruction areas, and rational utilization areas. Therefore, the country is facing a new round of revision and compilation of the general planning of national wetland parks. The purpose of this paper was to provide information to guide wetland park functional zoning and to formulate the water pollution prevention and control strategy. In this study, 53 sampling points of 6 national wetland parks in Suzhou City were selected. Pearson’s correlation analysis, multiple stepwise regression analysis, redundancy analysis, single factor, and comprehensive water quality identification index methods were used to analyze the effects of wetland landscape types and landscape configuration on water quality. (1) Lakes and rivers in the wetland park had positive ecological effects and should be distributed in each functional zone. (2) Grassland ecology is fragile. Grasslands should be distributed in conservation areas and in restoration and reconstruction areas. (3) Woodland and cultivated land have both ecological and economic benefits. They can be used as ecological buffer and entertainment zones, which are respectively distributed in the restoration and reconstruction areas and in the reasonable utilization areas. (4) Built-up land is highly disturbed by humans. It should only occur in the rational utilization areas and far away from the conservation areas.

A Robust Scheme for Coherency Detection in Power Systems

This paper presents an approach for online generator coherency identification based on windowed dynamic time warping (DTW). Generator rotor speed deviations measured by phasor measurement units (PMUs) are used as input data to compute a DTW dissimilarity matrix. Using the dissimilarity matrix together with Agglomerative Hierarchical Clustering (AHC) and Hubert-Levin index (C-index), generators are optimally grouped into coherent clusters. In addition to the clustering of generators, an index for characterizing the transmission delay of a Wide Area Measurement System (WAMS) is presented. A data delay factor that can indicate whether there is an inconsistent PMU data transmission delay is also proposed. The coherency identification technique and indices were tested using simulations carried out on the IEEE 39-bus system. The test results indicate that the proposed scheme accurately clusters generators into coherent groups. The suggested indices were also found to be valid. Keywords : coherence identification, dynamic time warping, speed deviation, phasor measurement unit, dissimilarity matrix

Clinical features, cardiac magnetic resonance imaging findings and outcome of patients with suspected myocarditis.

Myocarditis is largely underdiagnosed due to subclinical symptoms and non-availability of diagnostic techniques necessitating high index of suspicion and early disease identification. This study aimed to assess the clinical presentation, cardiac magnetic resonance (CMR) imaging findings and prognosis of these patients. After reviewing the CMR data of Aga Khan University Hospital from January 2011 to December 2019, a total of 24 patients were included in the study with the confirmed diagnosis of myocarditis on CMR. Mean age was 33.4±15 years with the majority (58%) being male. Dyspnoea was the commonest symptom seen in 15(62%) cases followed by chest pain in 13 (54%). On echocardiogram, 15 (62.5%) cases showed LV dysfunction. Common CMR findings were late gadolinium enhancement in 18 (75%) and bright T2 signals in 11 (45%) patients. With a mean follow-up of 3.6±2 years, one patient died of non-cardiac cause. Nine out of 14 patients (for whom repeat echocardiogram was done) had resolution of LV dysfunction suggesting favourable prognosis.

Water Pollution Characteristics and Source Apportionment in Rapid Urbanization Region of the Lower Yangtze River: Considering the Qinhuai River Catchment

Clarifying the current situation of regional water pollutants and the relationship between pollutants and pollution sources is considered essential for managing the water environment. Water quality identification index (WQI), cluster analysis (CA), positive matrix factorization (PMF), and stable isotope analysis in R (SIAR) were employed to interpret a large and complex water quality data set of the Qinhuai River catchment generated during 2015 to 2019 to monitor of 11 parameters at 29 different sampling sites. WQI analysis indicated that water quality in Qinhuai River catchment is considered to have "moderate pollution," and an improving trend of water quality was observed at the interannual scale. TN was the most deteriorated of all pollution parameters. CA and PMF results on the spatial scale revealed that sampling sites located at downtown of Nanjing and Lishui District or Jangling University town were highly polluted due to the sewage from domestic sewage and business service sewage (28.88%) as well as industrial wastewater (27.43%), while sampling sites located at Hushu Street Administrative District, Ergan River, and Sangan River were slightly polluted by rural domestic wastewater and garbage (28.79%), and agricultural non-point source pollution (24.3%). The middle-lower reaches (Jiangning Development Zone and Moling Street) and middle reaches (Lukou Street Administrative District) were moderately polluted by industrial wastewater (27.25%), sewage from domestic wastewater and business service wastewater (31.62%) as well as inner sources (24.76%). The SIAR results showed that NO3--N was the main nitrogen form, and the NO3--N mainly originated from sewage (61%) and soil (34%) in the Yuntaishan River sub-catchment. These results will aid in the development of measures required to control water pollution in river catchments.

Significance of Cystatin C for Early Diagnosis of Contrast-Induced Nephropathy in Iraqi Patients Undergoing Coronary Angiography

Background: Contrast-induced nephropathy (CIN) has been traditionally defined as an increase in serum creatinine (sCr) after contrast media (CM) exposure. It is generally a transient and reversible form of acute renal failure. Objectives: The objective was to compare changes in serum creatinine and serum cystatin C (sCys C) in patients undergoing CM administration during coronary angiography (CAG) and/or intervention, and whether these changes are a reliable index for early identification of CIN. Materials and Methods: In this prospective study, 50 patients were included, 9 of them were omitted, and remaining 41 patients undergoing CAG and/or intervention. sCr, serum urea, sCys C, and estimated glomerular filtration rate (eGFR) were evaluated at baseline as well as 24 h after exposure to CM. Results: Forty one patients, six of them develop CIN (CIN group) and the remainder 35 not develop CIN (non-CIN group). Clinical parameters showed no significant association between CIN group and non-CIN group except in diabetes mellitus. As comparing patients before and after catheterization, the CIN group showed increase in sCr and serum urea, while remain nearly the same for sCys C, and obvious decrease for eGFR1 and eGFR2, in addition there is significant association for sCr, eGFR1, and eGFR2. In the non-CIN group, only the serum urea showed significant difference. Conclusion: The concentration change of sCr is significantly superior to cystatin C as an early biomarker in the CIN detection. An absolute increase of the concentration of sCr is highly sensitive and specific for the CIN in comparing to cystatin C.

Superpixel-guided preprocessing algorithm for accelerating hyperspectral endmember extraction based on spatial–spectral analysis

Preprocessing is a major area of interest in the field of hyperspectral endmember extraction, for it can provide a few high-quality candidates for fast endmember extraction without sacrificing endmember accuracy. We propose a superpixel-guided preprocessing (SGPP) algorithm to accelerate endmember extraction based on spatial compactness and spectral purity analysis. The proposed SGPP first transforms a hyperspectral image into low-dimension data using principal component analysis. SGPP then utilizes the superpixel method, which normally has linear complexity, to segment the first three components into a set of superpixels. Next, SGPP transforms low-dimension superpixels into noise-reduced superpixels and calculates their spatial compactness and spectral purity based on Tukey’s test and data convexity. SGPP finally retains a few high-quality pixels from each superpixel with high spatial compactness and spectral purity indices for subsequent endmember identification. Based on the spectral angle distance, root-mean-square error, and speedup, experiments are conducted on synthetic and real hyperspectral datasets, and they indicate that SGPP is superior to current state-of-the-art preprocessing techniques.

Mechanical criterion for coal and gas outburst: a perspective from multiphysics coupling

Although a series of hypotheses have been proposed, the mechanism underlying coal and gas outburst remains unclear. Given the low-index outbursts encountered in mining practice, we attempt to explore this mechanism using a multiphysics coupling model considering the effects of coal strength and gas mass transfer on failure. Based on force analysis of coal ahead of the heading face, a risk identification index Cm and a critical criterion (Cm ≥ 1) of coal instability are proposed. According to this criterion, the driving force of an outburst consists of stress and gas pressure gradients along the heading direction of the roadway, whereas resistance depends on the shear and tensile strengths of the coal. The results show that outburst risk decreases slightly, followed by a rapid increase, with increasing vertical stress, whereas it decreases with increasing coal strength and increases with gas pressure monotonically. Using the response surface method, a coupled multi-factor model for the risk identification index is developed. The results indicate strong interactions among the controlling factors. Moreover, the critical values of the factors corresponding to outburst change depending on the environment of the coal seams, rather than being constants. As the buried depth of a coal seam increases, the critical values of gas pressure and coal strength decrease slightly, followed by a rapid increase. According to its controlling factors, outburst can be divided into stress-dominated, coal-strength-dominated, gas-pressure-dominated, and multi-factor compound types. Based on this classification, a classified control method is proposed to enable more targeted outburst prevention.

Physiological response and evaluation of melon (Cucumis melo L.) germplasm resources under high temperature and humidity stress at seedling stage

Melon is a favourite fruit and is widely planted in China. High temperature and humidity (HTH) stress describes the main limiting factors for melon due to the continuous hot and rainy weather in summer. The physiological response of melon to HTH stress and an evaluation method for identifying varieties resistant to HTH have not been reported. In this study, seedlings of 56 melon germplasm resources were used to measure the growth indexes and physiological and biological indexes under high temperature and humidity stress and to evaluate the tolerance of different varieties to HTH. Compared with the control, the plant height (PH) grew rapidly, and stem diameter (SD), leaf length (LL), and leaf width (LW) were inhibited in all melon varieties. The photosynthetic parameters Pn and Fv/Fm decreased compared with the control. Most of the varieties showed increases in chlorophyll (Chl), soluble protein (SP) and MDA. According to the membership function value and cluster analysis methods, three varieties, M32, M52 and M56, were selected for their better HTH tolerance. Through correlation analysis, it was determined that Fv/Fm, Pn, Chl, LL, LW, PH, MDA and SD can be used as the identification indexes of early tolerance to HTH. In conclusion, this work provides basic materials for melon breeding and basic theories for the molecular mechanism of HTH tolerance in melon.

Divergence Distance Based Index for Discriminating Inrush and Internal Fault Currents in Power Transformers

This article puts forward a new algorithm based on Kullback–Leibler divergence (KLD) for discriminating inrush and internal fault currents in power transformers. Specifically, the main idea of this algorithm is to utilize the current signal discrepancy of the distribution with ideal fault current waveforms. To such an aim, the proposed index reproduces the differential current signal. Utilizing fast modified least squares technique, the differential current signal is generated. Applying the reconstructed differential current and ideal sinusoidal waveforms to the KLD indicator, the distribution discrepancy of the current signal from ideal sinusoidal waveform discriminates inrush and internal fault currents. Also, the internal/external identification index is introduced that utilizes the phase content of the signals from current transformers (CTs) on both sides to distinguish internal and external faults, especially the faults accompanied with CT saturation. As a result, the proposed method can distinguish inrush currents, internal and external fault currents with/without CT saturation, and internal fault currents during transformer energization. The performance of the proposed index is evaluated using practically recorded data and is further compared with the state of the art.

Electrocardiogram Changes in the Spectrum of TTNtv Dilated Cardiomyopathy: Accuracy and Predictive Value of a New Index for LV-Changes Identification

Truncating TTN variants (TTNtv) are the main cause of dilated cardiomyopathy (DCM). The dynamic nature of this entity has previously been described. Based on own empirical observations and previous evidences, this study assessed repolarisation patterns and the possible association with morphological and functional status of TTNtv-DCM patients. Electrocardiograms (ECGs) of index patients with TTNtv-DCM and their relatives were included and matched in time with an echocardiogram. All individuals were classified into five phenotype groups: 1) Reduced left ventricular ejection fraction (LVEF <50%); 2) Recovered LVEF: at least 10% increase and LVEF >30% after optimal medical treatment; 3) Borderline phenotype (mildly enlarged ventricle and/or hyper-trabeculation); 4) Genotype positive, phenotype negative; and 5) Non-carriers. All electrocardiograms were evaluated by two blinded observers in qualitative and quantitative terms [T index (mm)=Σ T-wave amplitude (V5, V6, II, aVF)] and these data were compared with demographic and clinical information. The Δ T-index was calculated in those individuals with more than one electrocardiogram. Seventy-eight (78) electrocardiograms were included (46% female, mean age 50 years). T-index and prevalence of an abnormal T-wave had significantly different results among the groups (p<0.0001). Age and haemodynamic factors were shown to be ECG-modifiers, especially in phenotype-negative patients. T-index enabled individuals with reduced LVEF (<2.5) to be identified and to differentiate patients with favourable and unfavourable responses to treatment (Δ T index >3.5 and ≤2, respectively). Repolarisation changes enabled characterisation of the spectrum of TTNtv-DCM. The T-index identified potential carriers and patients with the worst profiles of the spectrum of the disease.

Identification of Generating Units That Abuse Market Power in Electricity Spot Market Based on AdaBoost-DT Algorithm

The identification of generating units that abuse market power is an essential part of risk prevention in a spot market, especially in the early stage of the construction of the spot market. In this study, a model for identifying generating units that abuse market power is designed based on the AdaBoost-DT algorithm. It is targeted at the imbalance between samples of generating units that abuse market power and normal generating units in the spot market. First, the four main methods by which market power is abused by generating units in the spot market are described: collusion, economic withholding, physical withholding, and extreme quotation. Second, the specific characteristics of the four methods are analyzed, and the identification indexes for generating units that abuse market power are established. Thereafter, a sample set of generating units that abuse market power using different methods is constructed. Furthermore, a training set is formed with samples of normal generating units to construct a model based on the AdaBoost-DT algorithm, for identifying generating units that abuse market power. Finally, the spot market data of a certain region are used for an example analysis. The results show that the accuracy of model identification is 97%, which validates the method.

Macromolecular Characterization of Compound Selectivity for Oxidation and Oxidative Alterations of Dissolved Organic Matter by Manganese Oxide.

Manganese (Mn) oxides can oxidize dissolved organic matter (DOM) and alter its chemical properties and microbial degradability, but the compound selectivity for oxidation and oxidative alterations remain to be determined. We applied ultrahigh mass spectrometry to catalog the macromolecular composition of Suwannee River fulvic acid (SRFA) before and after oxidation by a Mn oxide (δ-MnO2) at pH 4 or 6. Polycyclic aromatic hydrocarbons, polyphenols, and carbohydrates were more reactive in reducing δ-MnO2 than highly unsaturated and phenolic (HuPh) compounds and aliphatics, but highly abundant HuPh contributed the most (∼50%) to the overall reduction of δ-MnO2. On average, oxidized species had higher molecular weights, aromaticity, carbon unsaturation degree, nominal oxidation state of carbon, and oxygen and nitrogen contents but were lower in hydrogen content compared to unoxidized species. The oxidation decreased these molecular indices and oxygen and nitrogen contents but increased the hydrogen content, with stronger changes at the lower pH. This DOM oxidation on polar mineral surfaces was more selective but shared similar selectivity rules to adsorption. The abiotic oxidation resembles microbial oxidative degradation of organic matter, and Mn oxide-oxidizable carbon may be a useful index for detection and identification of labile organic carbon.

Usefulness of different adiposity indexes for identification of metabolic disturbances in patients with obesity

Context Despite the role of BMI as a classical obesity index, other indexes reflecting mainly abdominal obesity, usually outperform BMI in terms of metabolic complications prediction. Objective The aim of the present study is to compare the usefulness of different adiposity indexes for the identification of metabolic disturbances in patients with obesity. Methods In the study, we included 461 patients – group 1 with obesity (n = 182), group 2 with prediabetes (n = 193), and group 3 with newly diagnosed type 2 diabetes (n = 86). Different anthropometric and adiposity indexes were calculated – WHR, WSR, VAI, ABSI, BRI, Hip index, WWI, LAP. Results VAI and LAP had the highest predictive value for the presence of carbohydrate disturbances. VAI also showed the strongest correlation with Framingham and SCORE compared to other adiposity indexes. Conclusions VAI and LAP are most useful for the identification of metabolic disturbances and cardiovascular risk in patients with obesity.

Data Growth Identification and Application Performance Index (APDEX) Evaluation on the Performance of Geospatial Information Mapping Applications

Data Growth Identification and Application Performance Index (APDEX) Evaluation on the Performance of Geospatial Information Mapping Applications