Reasonable Control Measures Research Articles

Soil respiration and its response to climate change and anthropogenic factors in a karst plateau wetland, southwest China.

It is important to investigate the responses of greenhouse gases to climate change (temperature, precipitation) and anthropogenic factors in plateau wetland. Based on the DNDC model, we used meteorological, soil, and land cover data to simulate the soil CO2 emission pattern and its responses to climate change and anthropogenic factors in Guizhou, China. The results showed that the mean soil CO2 emission flux in the Caohai Karst Plateau Wetland was 5.89 ± 0.17 t·C·ha-1·yr-1 from 2000 to 2019, and the annual variation showed an increasing trend with the rate of 23.02 kg·C·ha-1·yr-1. The soil total annual mean CO2 emissions were 70.62 ± 2.04 Gg·C·yr-1 (annual growth rate was 0.28 Gg·C·yr-1). Caohai wetland has great spatial heterogeneity. The emissions around Caohai Lake were high (the areas with high, middle, and low values accounted for 3.07%, 70.96%, and 25.97%, respectively), and the emission pattern was characterized by a decrease in radiation from Caohai Lake to the periphery. In addition, the cropland and forest areas exhibited high intensities (7.21 ± 0.15 t·C·ha-1·yr-1 and 6.73 ± 0.58 t·C·ha-1·yr-1, respectively) and high total emissions (54.97 ± 1.16 Gg·C·yr-1 and 10.24 ± 0.88 Gg·C·yr-1, respectively). Croplands and forests were the major land cover types controlling soil CO2 emissions in the Caohai wetland, while anthropogenic factors (cultivation) significantly increased soil CO2 emissions. Results showed that the soil CO2 emissions were positively correlated with temperature and precipitation; and the temperature change had a greater impact on soil respiration than the change in precipitation. Our results indicated that future climate change (increased temperature and precipitation) may promote an increase in soil CO2 emissions in karst plateau wetlands, and reasonable control measures (e.g. returning cropland to lakes and reducing anthropogenic factors) are the keys to controlling CO2 emissions.

Optimization of Rockburst Risk Control Measures for Deeply Buried TBM Tunnels: A Case Study

Choosing reasonable control measures for different intensity rockburst risks not only effectively prevents and mitigates rockburst risks but also reduces time and engineering investment costs. Due to the limitations of the tunnel boring machine’s structure and working conditions, tunnels excavated by TBMs are highly susceptible to rockbursts. What is even worse is that there are very few measures to control the rockburst risk in these tunnels. Implementing reasonable control measures from the limited mitigation measures to control and mitigate rockburst in TBM tunnels is an urgent problem that warrants a solution. In this paper, a large number of on-site rockburst risk control cases and a large amount of MS monitoring data (the total mileage of MS monitoring is approximately 7 km, lasting for 482 days) are used to derive a reasonable scheme to control the rockburst risk of different intensities in twin TBM tunnels. First, the rockburst early warning effect of the two headrace tunnels of the Neelum–Jhelum hydropower station based on microseismic monitoring is analyzed. Second, based on highly accurate rockburst warning results, 94 rockburst risk control cases are applied to analyze the control effect of different control measures at different intensities of rockburst risk. Then, by combining factors such as the time cost and expense cost of different control measures, more reasonable control measures for different intensity rockburst risks are proposed: for slight rockburst risk, normal excavation is preferred; for moderate rockburst risk, horizontal destress boreholes are preferred; and for intense rockburst risk, a combination of measures of shortening daily advance and horizontal destress boreholes is preferred. The research results can provide a reference for other TBM excavation projects to carry out rockburst risk prevention and mitigation.

Study on Queue Length in the Whole Process of a Traffic Accident in an Extra-Long Tunnel

To investigate traffic accident patterns in undersea tunnels and quantify the relationship among various factors and traffic accidents in undersea tunnels, we analyzed the rules of evolution during the entire process of vehicle congestion queuing. Additionally, we built a maximum queue-length estimation model based on shock-wave theory and a whole-process queue-length estimation model based on real-time data input. The results demonstrate that the model is most precise when the data are not smoothed and the time interval is 30 s. The maximum accuracy of the model is not improved by data smoothing processing, but it is substantially improved when the time interval is between 5 and 15 s. Various movable window lengths have no discernible effect on the results. Maximum queue-length estimation model accuracy is 92.34%, while real-time whole-process queue-length estimation model accuracy is 83.50%. The accuracy of the proposed model is greater than that of the input–output model, indicating that the proposed model can support timely and reasonable control measures.

Optimal Design of Segment Storage and Hoisting of Precast Segmental Composite Box Girders with Corrugated Steel Webs

To optimize the segment storage and hoisting plan of precast segmental composite box girders with corrugated steel web bridges, China’s first precast segmental composite girder bridge with corrugated steel webs is taken as the background. The difference between the precast segmental composite box girders with corrugated steel webs and the traditional concrete box girder is proven by numerical simulation. The stress and deformation characteristics of the segmental girder during storage and hoisting are analysed, and reasonable control measures are proposed. The data suggested that compared with ordinary concrete box girders, the smaller torsional stiffness and lateral stiffness of the precast segmental composite box girder with corrugated steel web segments lead to larger roof stress and deformation during the storage and hoisting periods. The number of storage layers of segmental girders should not exceed two, and the four hoisting point scheme should be adopted for hoisting. It is recommended to set one to two channel steel supports of no less than 20 grade steel between the top and bottom plates to avoid excessive deformation of the roof. With the increase in the segment length, the roof deformation and stress increased regardless of the storage period and the hoisting period. If the safety factor needs to be increased, when the segment length is short (1.6 m–3.2 m), increasing the support size is recommended. When the segment length is longer (4.0 m, 4.8 m), increasing the number of supports is recommended.

MRI and the control of electromagnetic fields at work regulations 2016 - professional body guidance.

The Control of Electromagnetic Fields at Work Regulations (2016) implement the requirements of the EU Physical Agents (Electromagnetic Fields) Directive 2013 into UK Law. These regulations prohibit exposure of employees to electromagnetic fields above defined exposure limit values (ELVs). However, for MRI work activities, there is an exemption from this requirement provided that exposures are reduced to a level that is as low as is reasonably practicable. There are additional requirements for an adequate risk assessment, provision for staff training and monitoring of any health effects.This document provides specific guidance on achieving compliance with the regulations in the MRI setting. Consideration of what level of exposure is 'reasonable' is key to the proper application of these regulations. The ELVs, as defined in the regulations, are presented in terms of their relevance to exposures in the MRI-setting, what the direct and indirect effects of exposures are likely to be and what reasonable control measures can be put in place. Worked examples provide a step-by-step guide to achieving compliance with the regulations.For typical MRI working practices, it is unlikely that any permanent health effects will be experienced. Indeed, any effects that are experienced are likely to be transient and have no long-term consequences. Control measures to minimise the risks to workers in the MRI environment should already be in place in well-run units and there should be no need to implement additional control measures for exposures above the ELVs.

Corporate Social Responsibility, Advertising Competition and Consumer Welfare: A Research on the Model of Oligopoly Competition Theory

The paper constructs an oligopoly competition model to explore the strategic choice of corporate social responsibility and advertising investment, which means to analyze the trade-off theoretically between advertising investment and the weight of social responsibility. The study found that, with the improvement of social responsibility performance, the dominant strategy of enterprises will evolve from advertising competition to production competition caused by social responsibility. Under certain restrictions, corporate social responsibility will promote advertising competition. Research shows that enterprises should pay attention to the benefits brought by advertising competition while paying attention to social responsibility and the government should also take reasonable control measures, otherwise social welfare and economic benefits of enterprises will be inhibited.

Control measures of collapse-pounding dynamic responses of adjacent structures under earthquake action

The adjacent structures are easy to impact under earthquake, and the huge impact force will destroy the structural members, such as beams and columns, and even cause partial or total structural collapse. In order to control the pounding and the collapse of the adjacent structures, the flexible control measures with steel strands is proposed, which has little influence on the dynamic characteristics of the structure itself. The 3-D calculation model of the adjacent 10-storey and 8-storey frame structures are established by explicit dynamic program. The influence of steel strand arrangements on pounding and collapse is studied, and the parameter analysis is conducted. The results show that the uncontrolled adjacent structures are prone to collapse under strong earthquake, and the reasonable control measures can avoid structure collapse when the PGA is 0.62g. The maximum reduction rate of the impact force is 38.28%, the maximum reduction rates of the inter storey displacement angles of the taller and the lower structures are 16.36% and 24.74%, respectively. The lower structure is more affected by the pounding compared with the taller structure. The impact force does not always decrease with the increase of the gap size, and the earthquake intensity is one of the factors affecting the change law. The height difference of adjacent structures has great influence on the impact force and vertical displacement. The structure damage is aggravated with the increase of seismic dimension. The reasonably designed flexible measures are very effective for controlling the pounding and collapse of the adjacent structures under earthquake.

Frost Heaving Damage Mechanism of a Buried Natural Gas Pipeline in a River and Creek Region.

When the buried pipeline passes through the permafrost zone, the phenomenon of frost swelling occurs in the permafrost zone, which causes a certain degree of bending and deformation of the pipeline. As a result, the pipeline’s structural safety is compromised, and the pipeline finally fails during operation, posing a serious hazard to the natural gas pipeline’s operation. Whereas the theoretical research on soil frost heave is relatively comprehensive, the applied research on engineering problems is not yet complete. Therefore, it is necessary to predict frost heaving through experiments and numerical simulation, and put forward reasonable control measures for existing or potential problems. For the problem of pipeline damage caused by frost swelling of soil in the natural gas high-pressure regulator station in a river and creek region, the Drucker–Prager elastic-ideal plastic model of soil was selected for finite element analysis, and a reasonable finite element model of pipe-soil was established in this paper. Through the temperature field analysis, it was found that the soil around the buried pipe is affected by the pipeline and is lower than its freezing temperature, which makes the soil freeze and swell. Furthermore, through the thermal–structural coupling analysis, it was found that the buried pipe is affected by the freezing and swelling of the soil and the structure is greatly likely to be damaged. In addition, by analyzing the temperature distribution and frost heave deformation of the soil around the pipeline, as well as the deformation and force of the pipeline at different pipe temperatures, this paper also determined the ideal temperature for preventing frost heave damage to natural gas at high-pressure regulator stations as −1 °C. Finally, based on the results of the abovementioned analysis, the heating method was determined to improve the frost damage phenomenon at the high-pressure regulator. The results of the anti-frost and swell study were used to conduct field trials at natural gas high-pressure regulator stations where frost and swell had occurred. By adding heating furnace to increase inlet temperature, frost heaving of gas transmission pipeline can be effectively prevented. The results of the research provide a reference for both existing and new natural gas pipelines, and also accumulate experience for winter maintenance design and construction of pipeline engineering in seasonally frozen soil areas.

First Report of Leaf Spot on Panax notoginseng Caused by Caryophylloseptoria pseudolychnidis in Yunnan, China.

Panax notoginseng is a unique traditional medicinal plant in China, which has the effects of improving myocardial ischemia, protecting liver and preventing cardiovascular diseases (Jiang, 2020). In July 2021, gray-brown round spots were found on the leaves of P. notoginseng in the plantations of Lincang City (23º43´10˝N, 100º7´32˝E). By September, the symptoms were observed on more P. notoginseng plants, with incidence reaching 31%. Initial symptoms on leaves were small, brown spots that expanded, with black granular bulges on the lesions, often surrounded with yellow halo. As the disease progressed, multiple lesions merged, leaves became yellow, and abscission occurred. To isolate the causal pathogen, twelve symptomatic leaves were randomly obtained from twelve P. notoginseng plants. Small pieces of infected leaf tissues (about 5 mm2) were disinfected with 75% ethanol for 30 s, soaked in 2% sodium hypochlorite for 3 min, and then rinsed 3 times with sterile water and blotted dry. Sample tissues were plated on potato dextrose agar (PDA) plates incubated at 25℃ for 5 days with 12 h light/dark photoperiod. Hyphal-tips from the growing edge of colonies were transferred to fresh PDA to obtain pure cultures. Eight isolates were obtained with similar colony morphology, gray (top view) or black (back view) coloration, with a villous surface, and slow-growing on PDA. Conidia were hyaline, slender and obtuse to subobtuse at both ends, 10.3 to 52.62 (av. 25.2) µm × 1.4 to 4.0 (av. 2.4) µm (n=200) in size. Characteristics of the colonies and conidia were consistent with Caryophylloseptoria pseudolychnidis as described by Quaedvlieg et al. (2013) and Verkley et al. (2013). Genomic DNA of three representative isolates (LINC-4 to LINC-6) was extracted, and the rDNA-ITS region, ACT, and LSU gene regions were amplified and sequenced using the primer pairs ITS4/ITS5, 512F/783R, and LSU1Fd/LR5, respectively. Sequences have been deposited in GenBank (OK614104-OK614106 for ITS, OK614109-OK614111 for LSU, OK628350-OK628352 for ACT). BLAST search showed that all sequences were 98% to 100% homology with the corresponding sequences of C. pseudolychnidis. ITS sequences of the three isolates (LINC-4 to LINC-6) showed 99.21% identity (500/504 bp) to C. pseudolychnidis strain CBS 128630 (GenBank accession no. NR156266). LSU sequences of the three isolates showed 99.76% identity (823/825 bp) to C. pseudolychnidis strain CBS 128630 (MH876481). For ACT sequences, LINC-4 and LINC-5 showed 98.53% identity (201/204 bp) to C. pseudolychnidis strain 128614 (KF253599); LINC-6 showed 99.02% identity (202/204 bp) to C. pseudolychnidis strain 128614 (KF253599). Further, the neighbor-joining and maximum-likelihood method were used for multilocus phylogenetic analysis of the obtained sequences using MEGA-X (Kumar et al. 2018). The three isolates were clustered in the same clade with two C. pesudolychidis from database. Three isolates (LINC-4 to LINC-6) were tested for pathogenicity to confirm Koch's postulates. Annual potted P. notoginseng was inoculated with spore suspension (105 spores.mL-1). Each isolate was inoculated onto two leaves each of five P. notoginseng plants. The controls were similarly mock-inoculated with sterile water. To maintain high humidity (>90% RH), all plants were placed in transparent plastic boxes in a greenhouse at 25℃ with a 12 h light/dark photoperiod. Fifteen days post-inoculation, inoculated leaves showed similar symptoms to those observed in the field, and control plants remained healthy. The pathogen were reisolated from symptomatic leaf spots, and the colony characteristics were the same as those of the original isolates. Morphological characteristics, molecular data, and Koch's postulates tests confirmed C. pseudolychnidis as the cause of P. notoginseng leaf spot disease. To our knowledge, this is the first report of C. pseudolychnidis causing leaf spot on P. notoginseng in Yunnan, China. The spread of this disease might pose a serious threat to the production of P. notoginseng. The occurrence and spread of this pathogen should be further studied in order to formulate reasonable control measures.

Enrichment and Ecological Risk Assessment of Available Phosphorus in Paddy Soil of Fujian Province Over Past 40 years

The ecological risks such as water eutrophication caused by soil phosphorus loss have attracted extensive attention, and its dynamic changes and enrichment effects are the basis for formulating reasonable control measures. In this study, based on the paddy soils of 1.8×106 hm2 in Fujian province, the dynamic changes and ecological risks of available phosphorus in paddy soils over the past 40 years were analyzedusing a soil database of 1:50000. The soil database contained 1471, 215534, and 2895 paddy soil samples in different periods, respectively. The paddy soil samples were derived from the 1982 Second National Soil Census, the 2008 Ministry of Agriculture and Rural Areas Soil Testing and Formulated Fertilization Project and the 2018 Ministry of Agriculture, and the Rural Areas Arable Land Quality Monitoring Project, respectively. The results showed that from 1982 to 2018, the content of available phosphorus in paddy soils increased by 47 mg·kg-1, and the enriched area reached 1.65×106 hm2, accounting for 91% of the total paddy soils in Fujian province. From 1982 to 2008, the available phosphorus content of paddy soils in Fujian province increased by 28 mg·kg-1, with the enriched area reaching 1.47×106 hm2, accounting for 82% of the total paddy soils in Fujian province. From 2008 to 2018, the available phosphorus content of paddy soils in Fujian province increased by 19 mg·kg-1, with the enriched area reaching 1.22×106 hm2, accounting for 69% of the total paddy soils in Fujian province. Further ecological risk assessment showed that from 2008 to 2018, the area of paddy soil with ecological phosphorus enrichment risk in the province gradually increased, mainly distributed in percogenic paddy soils and hydromorphic paddy soils with a slope of less than 2°. In the future, effective phosphorus fertilizer management measures should be formulated for different types of paddy soil to prevent the occurrence of environmental problems such as water eutrophication.

First Report of Anthracnose Disease on Bletilla striata Caused by Colletotrichum orchidophilum in Yunnan, China.

Bletilla striata (Thunb.) Reichb. f. has high ornamental and medicinal value. B. striata has been used in Chinese medicine for thousands of years to treat various diseases, such as peptic ulcers, gastrointestinal diseases, lung diseases, and traumatic bleeding (Jiang et al. 2021). In September 2020, about 30% of B. striata plants in a plantation in Lancang County (Puer City, Yunnan Province, 22°48'17" N, 99°46'58" E) were found with symptoms resembling Bletilla anthracnose disease. In May 2021, symptomatic leaves were observed again with a disease incidence rate reached 54.05%, and were collected. The initial symptoms were the appearance of one or more round light brown spots on the leaves. Subsequently, the lesions became larger, forming oval brown-black spots. On severely affected leaves, several spots coalesced, causing withering and death of the leaves. To isolate the pathogen, 10 symptomatic tissues (5mm2) of 10 infected leaves were disinfected in 75% ethanol for 30s then in 2% sodium hypochlorite for 3 minutes, rinsed with sterile water for 3 times, incubated on potato dextrose agar (PDA) plates at 25℃ for 5 to 7 days with a 12 h light/dark photoperiodic cycle. Finally, ten pathogen strains with similar morphology were isolated and pure cultures were obtained by single spore isolation. The morphology of fungal colonies was round, carpet-like, flat and neat, and the color was gray black. The conidiophores were colorless to brown and oval or stick-shaped. The conidia were cylindrical or oblong, consisted of a single cell with blunt round ends, and were on average 12.92 (8.13-21.21) μm×3.96 (2.55-5.90) μm (n=200) in size. Based on the morphology and conidial characteristics, the pathogen was identified as Colletotrichum sp. (Damm et al. 2012). The total genomic DNA of representative isolates (LCTJ-02, LCTJ-03, LCTJ-04, LCTJ-05 and LCTJ-06) was extracted and the ITS region, GAPDH, ACT and HIS3 gene regions were amplified and sequenced using the primer pairs ITS1/ITS4, GDF1/GDR1, 512F/783R, and CylH3F/CylH3R, respectively (Cai et al. 2009). The sequences were deposited in GenBank (MZ433189 to MZ433193 for ITS, MZ436430 to MZ436434 for GAPDH, MZ436435 to MZ436439 for HIS3 and MZ448474 to MZ448478 for ACT). BLAST search revealed that all sequences showed 98% to 100% homology with the corresponding sequences of C. orchidophilum ex-type (CBS 632.80). Phylogenetic trees were constructed using neighbor-joining and maximum likelihood methods for the combined data set of the ITS, GAPDH, ACT, and HIS3 genes by MEGA-X (Kumar et al.2018). In general, LCTJ-02, LCTJ-03, LCTJ-04, LCTJ-05, LCTJ-06, and C. orchidophilum type strains clustered on the same clade. To confirm pathogenicity, the five isolates of C. orchidophilum were inoculated in healthy leaves of potted B. striata, as described by Cai et al. (2009), with slight modifications. Each leaf was inoculated with three drops(10 µl drop-1) of conidia suspension (106 spores mL-1). The control group was mock inoculated with sterile water the same way. All samples were covered with plastic bags and maintained at 70% to 80% relative humidity for seven days. After this period, all inoculated leaves showed similar lesions, and the symptoms were identical to those observed in the field. The control plants remained healthy. The pathogens were re-isolated from two leaves of each treatment and re-identified as C. orchidophilum. To our knowledge, this is the first report of C. orchidophilum causing anthracnose on B. striata in China. In the future, the occurrence and transmission of this pathogen should be further studied in order to develop reasonable control measures.

Sand Bar Evolution Process Numerical Simulation Analyze Based on two Dimensional Numerical Model

The sand bar lies near the entrance to the sea, which is not only detrimental to the flood discharge and sediment discharge of the river, but also an important factor causing the swing the flow path to the sea. With the formation and development of the sand bar, the form of the sand bar is constantly changing, the river is expected to extend continuously, and the water level and velocity of the estuary river change within a certain range, thus affecting the estuary flood control and river management measures. It is of great significance to study the development process of sand bar and its form for flood control of estuarine rivers and to put forward reasonable control measures of the sand bar. The sediment inflow into the sea is calculated by using the validated two - dimensional numerical model of estuarine and rivers. In this paper, the variation and development process of the sediment form with time and space are analyzed from the following aspects: the process of sediment deposition thickness into the sea, the distribution chart of sediment deposition thickness along the direction of water flow into the sea, the process chart of seabed deposition height, the variation of intraday flow velocity along the sea and the analysis of the temporal and spatial variation of sediment concentration, etc. The calculated and analyzed results are consistent with the measured data.

Safety Analysis of Deep Foundation Excavation in Water-Rich Soft Soils Based on BIM

Recent years have seen a great concern on the construction safety of the deep foundation pit with complicated geological conditions due to an increasing number of accidents. However, there are not, currently, sufficient research studies on the safety analysis of the deep foundation pit in water-rich soft soils. As a result, dynamic predictions of the safety risk during the whole construction process are inadequate due to the lack of research studies. Therefore, this paper presents an approach for the construction safety of the deep foundation pit in water-rich soft soils, which combines the building information modeling (BIM), the finite element analysis (FEA), and the finite difference method (FDM). By using BIM technology, the author attempts to establish a 3D information model and a bracing structure model. Based on the application programming interface and the C# language, the data conversion from BIM-ANSYS-FLAC3D is realized. The author then attempts to analyze the ground surface settlement and horizontal displacement during the excavation of the deep foundation pit through FLAC3D, and the purpose of which is to identify potential safety hazards so that reasonable control measures can be taken. The approach presented in this article has been validated in the Project of Qinhuai River Ship Lock. Since the excavation and the after-construction stages of this project have been completed smoothly, this approach has been proved valid and applicable.

Time-domain simulation analysis of combined suppression measures for subsynchronous oscillators

Subsynchronous oscillation (SSO) may occur in High Voltage Direct Current (HVDC) transmission systems during operation. It seriously affects the stability of the power system, and, if no reasonable control measures are taken, the shaft system of the unit can break. To study the AC side shafting of an HVDC system, the parameters of the first IEEE standard model of SSO were taken as the reference and combined with the CIGRE Benchmark two-terminal DC transmission model to build a complete set of HVDC systems for SSO research. The system SSO phenomenon was realized by setting the fault of a Supplementary Subsynchronous Damping Controller with wideband connection and a Supplementary Excitation Damping Controller with separate modes. They were designed at the network side to suppress the SSO of the system effectively, and the effectiveness of the suppression effect was verified by time-domain simulation.

Drive comfort and safety evaluation for vortex-induced vibration of a suspension bridge based on monitoring data

Vortex-induced vibration (VIV) caused by wind excitation can seriously affect traffic comfort and safety. Therefore, reasonable control measures in the initial stage of VIV shall be formulated by the bridge management department to ensure the safety of passing vehicles. In this paper monitoring data of VIV of a suspension bridge from 2013 to 2017 were analyzed and the characteristics of structural vibration response factors such as wind parameters and Energy Concentration Coefficient (ECC) of VIV were studied. A dynamic monitoring model which used for VIV prediction was established based on the massive data collected by the existing structural health monitoring system and dynamic monitoring system of VIV installed on the bridge which is located in the East China Sea. The data measured in 2017 by the anemometers and acceleration sensors from dynamic monitoring system was taken as input to simulate the prediction process of VIV. The warning mechanism of VIV with 5 levels and corresponding measures were proposed. Results show that the root mean square (RMS) value of acceleration and ECC can be used as further criteria for judging the occurrence of VIV. The comprehensive decision method and trend analysis method can be used for VIV judgment. The recognition rate of the occurrence VIV is 88.00% and 93.24% by the comprehensive decision method and trend analysis method respectively, based on the dynamic monitoring model. The dynamic monitoring model for VIV can be adopted to timely predict VIV, and can be effectively applied in practical engineering.

Based on Finite Element Method Research on Treatment Measures of Crossing Gas Pipeline

The finite element method is used to analyze the stress and deformation of the crossing gas pipeline. The evaluation results show that the current pipeline stress and displacement cannot meet the allowable values specified in the specification. In order to ensure the safety of pipeline operation, it is necessary to treat the crossing gas pipeline. By investigating the pipeline construction period and operation period data, the deformation data collection and analysis of the pipeline has been carried out. It is speculated that the direct cause of the pipeline deformation is the temperature difference and the internal pressure and gravity. The indirect cause is that no appropriate compensation structure or sufficient restraint measures have been taken across the two ends. Cracking of the protective wall across the ends is a secondary failure of displacement. The finite element method is used to check the proposed governance measures, and finally determine more reasonable control measures. After the implementation of the treatment measures on the site, the better results were achieved. The pipeline stress and deformation were all within the requirements of the specification. The pipeline was in a safe state and the treatment measures were feasible and practical. The engineering application results show that the feasibility of checking the cross-section pipeline control measures by the finite element method has certain effectiveness and economic rationality, and can achieve the purpose of engineering governance.

Prediction analysis of vortex-induced vibration of long-span suspension bridge based on monitoring data

Vortex-induced vibration (VIV) is a kind of wind-induced vibration that occurs at low wind speeds. The actual effect of VIV in bridges is different from that in wind tunnels and has a severe impact on traffic safety. Therefore, to guide the bridge management department in taking reasonable control measures in the initial stage of VIV and ensure that vehicles pass over the bridge safely, an identification model for VIV is established based on a large amount of data collected from Zhoushan Sea Crossing Bridge. Firstly, the wind field and vibration characteristic parameters of VIV are calculated based on data measured from 2014 to 2016 by anemometers and acceleration sensors. Then, by the big-data significant differences method and distribution function fitting analysis, two wind field parameters and two vibration response parameters are determined to serve as indexes in the identification of VIV. Finally, based on a parameter optimization algorithm, the VIV identification model is established and the data of 2017 are used to test the prediction model. The results show that the recognition rate of VIV is 89% and the identification model can be used to warn about the occurrence of VIV in practical engineering.

The DC Bias Model and Simulation Analysis of Three-phase Five-limps Transformer Based on EIC Principle

In this paper, the model of transformer DC bias simulation is established based on EIC principle. This model considers the hysteresis loss and eddy current loss of the transformer core through the J-A model and the Bertotti theory. This model simulates the electromagnetic characteristics of the transformer under DC bias more accurately, providing a basis for reliable evaluation of transformer resistance to DC bias and determination of effective and reasonable control measures. Based on this model, the effects of DC bias on the operating characteristics of single-phase transformers are analyzed. Moreover, this paper summarizes the variation of field current and leakage flux as well.

Single-Phase DC Magnetic Bias Model and Simulation Analysis Based on EIC Principle

In this paper, the model of transformer DC bias simulation is established based on EIC principle. This model considers the hysteresis loss and eddy current loss of the transformer core through the J-A model and the Bertotti theory. This model simulates the electromagnetic characteristics of the transformer under DC bias more accurately, providing a basis for reliable evaluation of transformer resistance to DC bias and determination of effective and reasonable control measures.

Power Quality Assessment for a Fluctuating Load Based on the Electrical Transient Analysis Program

Before a new power customer is connected into the power grid, it is an important task to assess the possible impact of this new load on the power quality. This paper proposes a method to analyze the voltage fluctuations and harmonics for the characteristics of many types and quantities of internal frequency conversion equipment and motors in the power consumer. First, the principles and methods for model establishment of voltage fluctuation analysis and harmonic analysis are introduced. Then, according to the actual operation of the loads, the simulation model is established in ETAP (Electrical Transient Analysis Program). The voltage fluctuation and the harmonics injected into the power grid caused by the operation of loads are obtained through simulation. Since the phenomenon that the harmonics exceed the standard in the extreme operating condition, this paper gives reasonable control measures based on the actual condition of the load, the simulation results and the allowable values prescribed by national standards.