Dangerous Points Research Articles

Industrial and Clean Energy Hydrogen : An Overview

Global warming has several adverse impacts on climate and if not contained, may result in rising of sea level to a dangerous point when millions will be required to be displaced and rehabilitated. It is also responsible for climatic changes. Green house gases are the reason behind global warming. Carcon dioxide is main green house gas which is added due to continuing use of fossil fuels. To obtain carbon neutrality and Decarbonization, need of the hour is clean and carbon free source of energy. Hydrogen has emerged as a clean fuel as it does not contain carbon. But hydrogen does not occur in pure form in nature and eventually it has to be manufactured. Conventionally, it is manufactured from fossil fuels such as natural gas or coal and process is called steam reforming. This also requires source of energy. Use of fossil fuel results in green house gas. Hydrogen can also be produced by electrolysis of water and source of energy can be renewable energy like solar or wind energy. This obviates adding of greenhouse gas and is a clean process. There are several ways of producing hydrogen depending on raw input and source of energy, which quantify to what extent the produced hydrogen is green. Hydrogen offer variety of applications across many segments of industry. It is worthwhile to evaluate all manufacturing processes and applications of Hydrogen and its potential contribution in Decarbonization.

Laparoscopic distal pancreatectomy for pancreatic arteriovenous malformation complicated with portal hypertension.

Pancreatic arteriovenous malformation (PAVM) is defined as a vascular anomaly with an abnormal anastomosis of the arterial and portal networks within the pancreas. Treatment modalities of PAVM include transarterial embolisation (TAE), irradiation and operation. Most patients treated with TAE alone will experience recurrence, so surgery is the best radical treatment. A female patient was admitted to our institution for the treatment of haematemesis. Examination revealed varices in the oesophagus and stomach, collateral circulation development caused by portal hypertension and PAVM of the pancreas. Surgical treatment was intended to reduce left portal hypertension. In this case, collateral circulation were considered dangerous points for unexpected bleeding. TAE was performed on the splenic artery before surgery to reduce blood flow in the areas with collateral circulation. En bloc resection of retroperitoneal tissue using the surgical procedure of radical antegrade modular pancreatosplenectomy was effective to minimise blood loss.

Mechanical characteristics of dowel bar-concrete interaction: based on substructure experiment

ABSTRACT Loading tests were carried out on the dowel bar-concrete substructure of concrete pavement. Mechanical characteristics of dowel bar-concrete interaction were studied. In the elastic range of concrete, the bearing modulus, which is a crucial parameter but is usually determined by presumption, was calculated using classic Westergaard equations. Its influencing factors were evaluated such as concrete strength, dowel bar thickness, joint width, and anti-cohesive layer. Besides, a theoretical equation for tangential stress at the most dangerous point of concrete was deduced from Westergaard's and Timoshenko's equations. The equation reveals how the tangential stress of the most dangerous point at the dowel bar-concrete interface is affected by influencing factors. Lastly, the deterioration process of concrete around the dowel bar was revealed. The strain gauges’ data show that deterioration of concrete develops from the most dangerous point to far away from the dowel bar gradually. Two failure modes were found; one is circular spalling, the other is three main cracks. The initiation of the dowel-bar concrete structure's deterioration is circular spalling, attributed to high radial compressive stress in concrete. The deterioration starts around half the load capacity of the structure.

Notched Component Fatigue Life Prediction in Torsional Loading

Considering the situation that fatigue life prediction of notched component is an indispensable part in the process of design in engineering, it is necessary to find some ways to solve such problems effectively. The stress and strain state of notched specimen is more complex, compared with smooth specimen. As a result, some researchers take advantage of the finite element method to analyze the mechanical properties of these kind of specimens, they can get the stress and strain state at the dangerous point directly instead of using theoretical methods. At the same time, the equation of shear stress is fitted by analyzing stress distribution of the section of notch root. The integral of shear stress in the section is equal to the external load, and the true stress value of notch root is derived. Then, the fatigue damage evolution equation of notched specimens under torsional load is proposed based on the closed-form solution in this paper. Meanwhile, the nonlinear fatigue life prediction model of notched specimens under the torsional load is given by using the damage mechanics theory. The proposed model is validated by experimental data (30CrMnSiNi2A steel and 45# steel). The results show that the predicted life is not only close to the experimental results, but also tends to be safe. The fatigue life of notched specimen is predicted by using notch geometric parameters and material constants. The model has more concise calculation process, avoids complicated fatigue tests, and facilitates engineering application.

Safety assessment of buried gas pipeline subject to surface explosion: A case study in Wuhan, China

To ensure the safety of the underground gas pipeline in urban ground explosion construction and terrorist attack, a study of the safety of buried gas pipelines under surface explosions is inevitable. In this paper, an operating gas pipeline in Wuhan Economic Development Zone is taken as an example, and the surface explosion full-scale experiment is carried out in the open site. In the field experiment, small charge of No. 2 rock emulsion explosives were used to simulate ground construction blasting, the blasting vibration velocity tester (TC-4850) and dynamic strain measurement system (DH5956) are used to monitor data, the analysis of field data shows that the experimental data meet the general rules, which proves the reliability of the field experiment. Secondly, the numerical model of pipeline response characteristics under surface explosion is established, and the reliability of the model is verified by field monitoring data. In the numerical analysis, the operating pressure of 0.2 MPa is given to the pipeline following the actual working condition, and the response characteristics of the pipeline under the condition of large explosive charge blasting on the surface are discussed. Based on the simulation results, the dangerous section and dangerous point of the pipeline under the action of ground explosion are analyzed, and the functional relationship between the peak effective stress (PES) of pipeline dangerous point and the explosive charge on the surface is deduced. Finally, according to the pipeline control value of PES determined in relevant specifications, the controlled explosive charge of surface construction blasting is obtained. Further, the equivalent conversion analysis of No. 2 rock emulsion explosive and TNT explosive is carried out, and the TNT controlled explosive charge of ground terrorist attack is obtained.

When connectivity makes safer routes to school: Conclusions from aggregate data on child transportation in Shanghai

Following a rapid urban development and mass motorisation, Chinese city planning has started to refocus its attention towards active transportation. It is therefore an opportune time to address the under-investigated issue of young children’s transportation. Indeed, in the Shanghai city centre, more than a third of the pre-school students are walking to school while almost half of them are transported on two-wheeled vehicles, highlighting the necessity for appropriate urban design solutions. In a previous study Chevalier and al. initiated this work and examined the barriers to cycling on the way to kindergartens. Based on their conclusions, minor adjustments to existing infrastructure could help to meet the population’s expectations in terms of safety and comfort. Using a survey questionnaire on safety perception and drawings of the detailed route to school, together with its corresponding points of danger, over 400 responses were collected at kindergartens in inner Shanghai. Data analysis underscores the increase in perceived danger at crossroads, hinting us to the need for a refined study of the trajectories at major intersections. As a proof of concept we isolate a crossroad, thoroughly evaluate its surroundings, and suggest simple design solutions, which could result in drastic improvements for soft mobility. In particular we show that improving connectivity could foster solutions significantly lessening the perceived danger. We believe this approach represents a valuable asset to the development of active transportation, as it can be applied at little cost, allowing city planners to improve the existing infrastructure and vulnerable road users to feel safer.

Study of the Manufacturing Options for an Asymmetric Plate Made of 12X18N10T Steel

The analysis of possible options for manufacturing an asymmetric plate of 12X18N10T steel is presented. A phenomenological model of damage accumulation was used to analyse the probability of metal micro – and macro – destruction. The results of FEM modelling of technological processes of plate manufacturing are presented. Due to these results were made the conclusions about feasibility of their application based on the metal damage calculation. The choice of a rational technology to produce a plate is justified, in which the greatest metal ductility reserve takes place at a dangerous point. According to the proposed scheme, an experimental batch of plates have been made.

The intrinsic nature of materials failure and the global non-equilibrium energy criterion

Materials failure under some sort of loading is a well-known natural phenomenon, and the reliable prediction of materials failure is the most important key issue for many different kinds of engineering structures based on their safety considerations. In this research, instead of establishing empirical models, the material failure process was modeled as a nonequilibrium process based on the microstructural mechanism. Then, the evolution equations were established and the stability analysis was carried out to obtain the critical conditions for the materials failure. It was found that the material strength was a global property in nature, and the commonly used local criteria based on the most dangerous point failure were not the rational assumption. Based on the idea, some examples were considered, such as the size effect of the material strength, the strength of the polycrystalline metals, the stress-strain relationship of the ultrafine crystalline metal with nanoscale growth twins, the strength of lithium niobite crystal specimens with notches. All of the theoretical predictions gave reasonable results compared with the experimental data.

Al Hadba Minaret in the Last 100 Years

Al-Hadba minaret is located in a central location on the right side of the river Tigris within the city of Mosul North of Iraq. It is one of the important heritage landmarks in Iraq, Mostly characterized by its curvature and height. It was built before more than 800 years. Later, It was destroyed due to military actions in the summer of 2017. Recently plans for reconstruction are going on. Accordingly, many different data has to be collected and organized to help form a model closer to the original shape. Prior to its destruction, careful surveying was performed to record the shape and movement of the minaret. This research provides a description of the results of this work. For a century, the minaret leaning has been slowly growing closer to the danger point. Modern construction techniques can be used to rebuild a more stable structure and avoid that movement.

Investigation and motion characteristics analysis of dangerous rock in high and steep slope based on UAV

The geological conditions in Southwest China are complex, and the dangerous rock hazards developed in the high and steep slopes has extremely high harmfulness and concealment. The traditional contact survey method is difficult to find out the geological hazard effectively under the limitation of complex and changeable terrain conditions. Unmanned aerial vehicle photogrammetric system has high flexibility and can obtain high-efficient, high precision and high resolution remote sensing images of geological disaster investigation area. By using the UAV photogrammetry system, the dangerous rock mass of the intake slope of Jinping secondary hydropower station is investigated. The working principle of UAV, the acquisition of high-definition image data and the construction of 3D model are discussed, and the feasibility of using the model data obtained by the system to investigate dangerous rock mass is demonstrated. Through repeated analysis and interpretation of the 3D real-scene model, the distribution characteristics of the dangerous rock hazard points of the intake slope are found out. On this basis, four sections are selected to simulate the movement track of unstable dangerous rock mass with Rocfall software, and the movement velocity, jump height and impact energy of different characteristic points of falling rock are calculated quantitatively with the formula.The research results provide an important reference value for the investigation of dangerous rock mass of high and steep slope in southwest China.

Underground pipelines dynamics problem solution under longitudinal seismic loading

In this article are considered some problems of oscillations of underground pipelines under seismic loading. The resulting system of equations is solved by the finite-difference of the second order of accuracy. The program is based on a computer algorithm implementation on oriented language Borland Delphi 7. Conducted theoretical and computational-experimental studies solve the problem of assessing the stress-strain state of underground pipelines under seismic effect the axes of the pipeline. The Stress-strain state of the underground pipeline is studied at linear and non-linear interaction with the soil. Linear and non-linear solutions are compared. Dangerous points of maximum normal stress occurrence under seismic loading in the underground pipeline are determined to take into account elastic pipe-soil system interaction. The conducted computational and experimental studies allow solving the problems of assessing the stress-strain state of pipelines under seismic loading, which is important for practical calculations.

Research on Modal Analysis of Rotor Shaft System of Hydro-generator

In this paper, the influence degree of eccentricity distance and guide bearing stiffness change on the vibration characteristics of the unit under the condition of rotor mass misalignment is discussed respectively, and the modal characteristics of the unit are studied for the problem of generator mass eccentricity. First of all, the guide bearing is parameterized, the whole axle system modeling is calculated by FEM modal analysis method, the results of the analysis obtain the first 10th order critical frequency and vibration mode analysis results, further determine the danger point of displacement deformation concentration. Comparing the vibration type, critical frequency and center vibration trajectory of the guide bearing under different constraint conditions, the characteristics of the unit vibration caused by the rotor quality is: the axis tile gap is gradually enlarged due to the eccentric rotation of the rotor of the unit, and the vibration characteristics of the main frequency in the unit vibration signal are unchanged. The results are confirmed by field inspection data.

Application of Multi-data Fusion Technology in Landslide Monitoring

At present, there are more than 280,000 hidden danger points of geological disasters in China. It has been proved that one of effective ways of reducing geological disasters is using professional equipment to monitor and mobilize the masses. The commonly professional devices include slope radar, crack gauge, laser radar and optical images in early warning period and in rescue phase. Each device has its own unique advantages and we developed a reasonable technical route to achieve the aim that combining the advantages of these various data. The mainly steps: the first step is to process the various data separately; secondly, to fuse the data that can be merged; thirdly, to perform overlay analysis and display on non-integratable data. We takes the high-level landslide of Xinmo Village, Sichuan Province on June 24, 2017 to verify the route’s effective. The results show that the multi-data fusion method can not only achieved the all-round monitoring of key hidden points, but also combined the advantages of multiple data and achieved millimetre-level monitoring accuracy and clear and intuitive effects.

Determining safety limitations and the frequency of determining vessel location when establishing marine bases on the Vietnam’s sea areas

The article introduces the request of the International Maritime Organization (IMO) for accuracy of vessel position and the maximum interval between two consecutive ship positions. The author focuses on assessing the extent to which IMO’s requirements are met when planning a voyage, based on practical experience from himself and a number of other outstanding captains. At the same time, analyse theoretical and practical basis when making decisions about the limited distance to the danger point and the time interval between two determinations of consecutive ship locations to ensure maritime safety. The article builds the process of calculating and manipulating maritime routes to estimate safety through dangerous areas with full theoretical basis and practical seafaring experience.

STRUCTURAL HEALTH MONITORING ON SPANS USING THE RESONANCE REGIONS OF THE POWER SPECTRUM DENSITY (RR-PSD)

This article proposes a new method which can be used to evaluate the mechanical responses of damage detection in spans. This method can monitor the stiffness degradation of spans over time. This monitoring processes will be conducted at different measuring points on spans, on different spans at the same or different measuring periods. The obtained results show that the change of acreage in the resonance regions of the power spectrum density has brought many positive preliminary outcomes in evaluating the quality of projects during their operational period. The study also shows that the change of acreage in the resonance regions allows us to identify the dangerous points on different spans of a bridge.

The stress analysis of corrugated metal hose under bending conditions

Corrugated metal hose, as an improved type of pipe, plays an important role in the development of modern industry. With the help of workbench, the numerical analysis of the bellows bending is studied. The bellows deform with the applied load, and the closer it is to the free end, the greater the deformation. By observing the deformation and stress distribution of the bellows, we can find the danger points of the bellows, which has important reference value for the design and maintenance of the bellows.

Stress State Measurement and Result Analysis of Car Wheels

The stress state of the car wheel is one of the guiding design indicators for the wheel structure. This paper uses the combination of finite element method and bench test to study the stress state of the wheel when driving straight. Through the finite element simulation of bending fatigue and radial fatigue, the position of dangerous points during the use of the wheel is obtained. The location of the dangerous point is used as the strain measuring point, and the test bench is built. The strain gauge is used to measure the strain of these points in the straight running condition, and the test results are analyzed. The results show that when the vehicle is traveling straight, the tire will have a greater impact on the load of the wheel. The squeezing deformation between the tire and the wheel, as well as the positive and negative rotation, will have an effect on the stress state of the wheel. The maximum strain of the wheel appears on the inside of the wheel rim, the rim is in contact with the tire and along the circumference of the wheel. The strain near the center of the wheel is small. Different loads have no effect on the variation of wheel strain, but have an effect on the maximum and minimum peaks.

POWER LINE EXTRACTION AND ANALYSIS BASED ON LIDAR

Abstract. The traditional electrical power line inspection method has the disadvantages of high labor intensity, low efficiency and long cycle of re-inspection. Airborne LiDAR can quickly obtain the high-precision three-dimensional spatial information of transmission line, and the data which collected by it can make it possible to accurately detect the dangerous points.It is proposed to use the grid method to divide the data into multiple regions for the elevation histogram statistical method to obtain the power line point cloud at the complex mountainous terrain. In the non-ground point data, part of the vegetation point cloud is separated according to the point cloud dimension feature, and then the power line point and the pole point are distinguished according to the density characteristics of the point cloud so as to realize the point cloud classification of the transmission line corridor. On this basis, the power line safety distance detection is carried out on the power line points and vegetation points extracted by the classification, and the early warning analysis of the dangerous points of the transmission line tree barrier is completed. The experimental results show that the method can classify the acquired power line corridor point cloud and extract the complete power line, which effectively eliminates the hidden dangers and has certain practical significance.

Assessment of the Effect of Inertia Forces in Problems of Underground Pipeline Seismodynamics

A research to assess the effect of inertia forces in solving specific problems of seismodynamics of underground life support systems is conducted in the paper. A calculation algorithm is constructed using the finite difference method; a system of applied programs based on the developed algorithms and their debugging is created. Dangerous points of maximum normal stress occurrence under seismic loading in underground pipeline are determined taking into account elastic pipe-soil system interaction. The limits of inertial load effect on the behavior of underground systems are estimated. The possibility of considering the seismodynamic problems of underground structures in quasistatic and static statements is substantiated theoretically. The methods of solving the equations of underground pipeline vibrations are given with account for elastic interactions in the pipe-soil system under seismic effect - seismodynamic and quasistatic methods. The conducted computational and experimental studies allow solving the problems of assessing the stress-strain state of pipelines under seismic loading, which is important for practical calculations.

Risk Assessment Inference Approach Based on Geographical Danger Points Using Student Survey Data for Safe Routes to School

Safe Routes to School is very important for students to have good physical and psychologically healthy in school life. For providing safe routes based on risk analysis, finding out dangerous points and areas can be a target to avoid dangerous locations by pedestrians and drivers. However, analyzing the risk assessment to derive the safe routes requires a large amount of data with a certain time of observation by experts. Deep learning is a solution to provide information regarding safe routes based on expert knowledge. In this paper, we propose a risk assessment inference approach using a Recurrent Neural Network (RNN) model with Long-Short Term Memory (LSTM) cells based on geographical information for safe routes to school. However, geographical information including coordinates is difficult used in learning-based inference models because of the series of float values. For training the RNN model with the geographical data, coordinates of routes and danger points are translated to be geohash through the geohash converter. The geohash data with other data of features are fused and inputted to the one-hot encoder. The one-hot encoded data is used in the inputs of the RNN model to train the LSTMs. The input data of the training model is derived by the risk index model that is proposed to calculate the risk index based on distances of route coordinates and danger points. Therefore, the risk index is correlated with the training dataset. Through the proposed inference approach, the geographical information including multiple coordinates is enabled to be trained by RNN as a geohash-based input string. Moreover, the input string with other features is fused to support the one-hot encoding to get a better result in RNN models.