Search

The purpose of this study is to put forward a feature extraction and pattern recognition method for the flow noise signal of natural gas pipelines in view of the complex situation brought by the rapid development and expansion of urban natural gas infrastructure in China, especially in the case that there are active and abandoned pipelines, metal and nonmetal pipelines, and natural gas, water and power pipelines coexist in the underground of the city. Because the underground situation is unknown, gas leakage incidents caused by natural gas pipeline rupture occur from time to time, posing a threat to personal safety. Therefore, the motivation of this study is to provide a feasible method to accelerate the aging, renewal and transformation of urban natural gas pipelines to ensure the safe operation of urban natural gas pipeline network and promote the high-quality development of urban economy. Through the combination of experimental test and numerical simulation, this study establishes a database of urban natural gas pipeline flow noise signals, and uses principal component analysis (PCA) to extract the characteristics of flow noise signals, and develops a mathematical model for feature extraction. Then, a classification and recognition model based on backpropagation neural network (BPNN) is constructed, which realizes the detection and recognition of convective noise signals. The research results show that the theoretical method based on acoustic feature analysis provides guidance for the orderly and safe construction of urban natural gas pipeline network and ensures its safe operation. The research conclusion shows that through the simulation analysis of 75 groups of gas pipeline flow noise under different working conditions. Combined with the experimental verification of ground flow noise signals, the feature extraction and pattern recognition method proposed in this study has a recognition accuracy of up to 97% under strong noise background, which confirms the accuracy of numerical simulation and provides theoretical basis and technical support for the detection and recognition of urban gas pipeline flow noise.

To alleviate the shortage of natural gas supply, the in-situ conversion of coal to natural gas is more beneficial for advancing the clean and efficient use of energy. Since in-situ coal gas contains complex components, such as H2, CH4, and CO, their leakage poses a serious risk to human life and property. Currently, the area of consequence of the harm caused by a leak in a gathering pipeline transporting in-situ coal gas has not been clarified. Therefore, this paper adopted the method of numerical simulation to pre-study the concentration distribution of each component and determined that the main components of concern are CO and H2 components. Afterward, the diffusion law of in-situ coal gas is analyzed and studied under different working conditions, such as wind speed, temperature, pipe diameter, leakage direction, and leakage aperture ratio. The results indicate that when a pipeline leak occurs, the CO component has the largest influence range. With increasing wind speed, the warning boundary of CO rapidly expands downwind, then gradually diminishes, reaching a peak value of 231.62 m at 7 m/s. The range of influence of the leaked gas is inversely proportional to temperature and directly proportional to pipe diameter and leakage aperture ratio. When the gas leaks laterally, the diffusion early warning boundary value of each component is maximal. Among them, the leakage aperture ratio has a significant impact on the concentration distribution of in-situ coal gas, whereas the effect of temperature is relatively minor. This study contributes to an understanding of the leakage and diffusion characteristics of in-situ coal gas-gathering pipelines.

Abstract Objective To evaluate the incidence, clinical laboratory characteristics, and gene mutation spectrum of Ph‐negative MPN patients with atypical variants of JAK2, MPL, or CALR. Methods We collected a total of 359 Ph‐negative MPN patients with classical mutations in driver genes JAK2, MPL, or CALR, and divided them into two groups based on whether they had additional atypical variants of driver genes JAK2, MPL, or CALR: 304 patients without atypical variants of driver genes and 55 patients with atypical variants of driver genes. We analyzed the relevant characteristics of these patients. Results This study included 359 patients with Ph‐negative MPNs with JAK2, MPL, or CALR classical mutations and found that 55 (15%) patients had atypical variants of JAK2, MPL, or CALR. Among them, 28 cases (51%) were male, and 27 (49%) were female, with a median age of 64 years (range, 21–83). The age of ET patients with atypical variants was higher than that of ET patients without atypical variants [70 (28–80) vs. 61 (19–82), p = 0.03]. The incidence of classical MPL mutations in ET patients with atypical variants was higher than in ET patients without atypical variants [13.3% (2/15) vs. 0% (0/95), p = 0.02]. The number of gene mutations in patients with atypical variants of driver genes PV, ET, and Overt‐PMF is more than in patients without atypical variants of PV, ET, and Overt‐PMF [PV: 3 (2–6) vs. 2 (1–7), p

Global environmental problems have become increasingly prominent, and China, as one of the world’s major powers, should take action. China promises to achieve a “carbon peak” by 2030, and carbon dioxide emissions will no longer increase, and will gradually decrease after reaching the peak. To achieve “carbon neutrality” by 2060, all the carbon dioxide emissions will be offset by tree planting, energy saving and emission reduction. The optimization of pipeline energy consumption is also associated with it. In recent years, the transportation mode of the QT oil pipeline has changed from normal temperature transportation to heating transportation. The energy consumption of this transportation method mainly comes from heating furnaces and pumps. In order to reduce energy consumption and find a suitable pipeline operation plan, this article optimizes and analyzes the transformed QT oil pipeline under the premise of ensuring safe production. Based on programming software, this article establishes a corresponding mathematical model of energy consumption of the QT oil pipeline, and uses artificial bee colony algorithm, invasive weed algorithm and optimization algorithm based on biogeography to solve the model. The article innovatively introduces the speed of the variable frequency pump as a variable to study the energy consumption optimization problem of the oil pipeline, analyze the practical application of the oil pipeline of the QT oil pipeline, and obtains the best plan for the optimized operation of the oil pipeline of the QT oil pipeline It provided research basis and played a role in promoting the country’s dual-carbon goals.

The problem of global warming and climate change has attracted global attention, and reducing the concentration of CO2 in the atmosphere is an important step towards solving the problem. This paper mainly introduces the current development status, research hotspots, challenges and some emerging technologies of carbon capture, utilization and storage (CCUS). Among CO2 capture technologies, solvent absorption technology is currently the most mature and widely used technology, among which ionic liquid technology has great application prospects because its molecular structure can be designed and different functional groups can be connected. The surface functionalization of metal–organic frameworks in the adsorption method endows them with excellent CO2 adsorption capacity. In CO2 transportation, temperature and pressure must be considered in pipeline transportation, because they will affect the phase state of CO2 transportation. The impact of impurities on CO2 pipeline transportation is a challenge that affects pipeline design and transportation safety. In CO2 utilization, the key to enhanced oil recovery, gas recovery and displacement of coalbed methane is to increase the recovery rate and increase the storage capacity at the same time. Only by strengthening the research on the adsorption behavior between CO2 and CH4 and revealing the relevant mechanism can innovative technologies be developed. The chemical utilization of CO2 has formed many routes, but they all lack certain advantages. Most scholars are working on catalysts for CO2 conversion, especially copper-based catalysts that can convert CO2 into methanol. The conversion rate of CO2 can be effectively increased through doping or process improvement. The coupling of electrocatalytic technology and renewable energy is an important development direction in the future. In CO2 storage, geological storage is currently the most important method, especially in saline aquifers. There are currently critical issues concerning reservoir integrity and leakage potential that should be further investigated. CO2 leakage will cause serious environmental problems, and the common monitoring methods are reviewed and discussed in this paper. Finally, the research status, hotspots and cooperation networks of CCUS are summarized by using CiteSpace software in order to help the development of CCUS technology. In addition, through the review and analysis, it is found that CCUS is faced with challenges such as low capture efficiency, difficulties in transformation and utilization, high operating costs, lack of strong support policies, and lack of international cooperation, which restrict the further development of CCUS.

To explore the influence of the isolation ball in a crude oil pipeline running over complex terrain, a “U” undulating crude oil pipeline with a large drop was taken as a practical case (the maximum elevation difference was 1490 m). Based on the OLGA multiphase flow transient simulation method, this paper conducts a simulation study on the process of pushing water in a large drop crude oil pipe section. The effect of oil–water interface pig (isolation ball) in the process of pushing water from crude oil and the influence of key parameters such as isolation ball diameter were analyzed. the movement characteristics of the pig in the large-drop sections under the conditions of various throughputs and fluid volumes were studied and determined the maximum velocity, pressure, fluid-holding rate, travel distance, and slug behavior of the pig at various low points. The results show that in the selected pipe section, when the throughput was 900 m3/h to 2500 m3/h, the presence of the isolation ball reduced the mixture of oil and water by 84.2% to 93.7%, reduced the volume of gas generated by the vaporization of the light oil components during transport, and reduced the slug flow in the pipe, providing an effective basis for designing optimal conditions for crude oil pipeline transport.

As the characteristics of looseness, heterogeneity, and natural variability of soil, landslide–pipe interaction is a complicated process. PRCI guidelines consider soil as springs to analyze landslide–pipe interaction when soil is at the ultimate state. In this paper, the strength-reduction method was used to analyze the landslide–pipe interaction at the limit equilibrium state of the soil. The fluid–solid coupling model was introduced to analyze the influence of rainfall on slope stability. The soil–pipe interaction under the effect of slope instability induced by rainfall was simulated and the influence of different pipe diameter-to-thickness ratio, internal pressure, location of the potential failure surface (PFS), and buried depth on the mechanical response of pipe were investigated. It is found that the buried depth will influence the pipe–soil interaction mechanism. With the increase of buried depth, D/t of pipe, the maximum stress of pipe will be greater. While the increase of internal pressure can provide a uniform force to resist pipe deformation, the maximum pipe stress will be smaller. Besides, the slope PFS was divided into three parts to investigate pipe–soil interaction, the results showed that buried pipe at the slope toe has larger maximum stress. The safety factor of the slope was validated against Bishop and Janbu method.

Abstract Most of the crude oil produced in China is highly viscous and easy to condense, and the pipeline transportation method is mostly heated. At present, frequency conversion technology is gradually applied to oil pump units. In order to find the best pipeline operation scheme, this paper is based on MATLAB programming software and established a corresponding mathematical model of oil pipeline energy consumption. This model innovatively takes the rotational speed of the variable frequency pump as one of the model optimization variables, calculating the pressure change and temperature change between stations of the pipeline, predicting the energy consumption of the pipeline and can guide the optimized operation of the pipeline, which has a high popularization and application value. An example of Qingtie Fourth‐line crude oil pipeline shows that among the genetic algorithm, particle swarm optimization, and simulated annealing algorithms for solving the optimization model, the particle swarm optimization algorithm has fast convergence speed, short optimization time, obtains the most optimal scheme, and can reduce energy consumption by 7.84%, which proves the practicability and creativity of the optimization model.

Abstract To explore the problem of the slack flow and waterhead having a huge impact on the low point of a pipeline during the water‐filling process of a large‐drop pipeline, the crossing section of the Nujiang China‐Myanmar crude oil pipeline (for which the maximum height difference is 1480 m) is taken as an actual case, and water filling of an oil pipe segment with a large drop is simulated based on an OLGA multiphase flow transient simulation. The maximum velocity, pressure, and corresponding liquid holdup at different low points of the pipeline are studied, and the variations of water flow velocity, pressure, and liquid holdup with time at different low points under different load conditions are obtained. A stress analysis of the pipeline is performed through CAESAR II. The results showed that, when the volume flow rate was 900‐2000 m3/h, the probability of slug flow in pipe could be reduced by 57%. Meanwhile, the tube pressure fluctuation and damage to the pipeline and equipment are reduced and pipeline transportation efficiency is improved, thereby providing an effective basis for engineering practice.

Abstract In view of the complicated heat transfer calculation for air coolers and the difficulty of directly calculating the exit temperature of natural gas in a compressor station, taking the dry air cooler of model GP12 × 3‐6‐258‐13.0S‐S‐23.4/DR‐Ia configured in the West‐East Natural Gas Pipeline II as an example, a three‐dimensional simplified model of the air cooler is established. The model is used to simulate a temperature flow field of a dry air cooler‐finned tube based on Fluent flow field analysis software. This paper studies the cooling effect of the dry air cooler‐finned tube on high‐temperature and high‐pressure natural gas at compressor outlet. By comparing and analyzing the relationships among natural gas mass flow, inlet air temperature, inlet natural gas temperature, and outlet natural gas temperature for an air cooler, the formula of temperature drop of dry air cooler to natural gas is fitted, and the fitting formula is verified by field operation data. The results show that the average error between the fitting results and the actual data is less than 1.5%, which proves the correctness of the fitting formula and greatly simplifies the heat transfer calculation process for air coolers.

Abstract Much less attention has been focused on the particle deposition in rectifying plate though it is a common problem in shale gas pipe systems. The effects of particle parameter and flow field on the deposition and distribution of particle in a new‐type rectifying plate system are investigated. Both the computational fluid dynamics (CFD) method and the experiment method are used in order to analyze the particle deposition under various conditions. The accuracy of simulation model is verified with measurements in the experiment and from analyzing, and it is found that the Boltzmann equation can well describe the relationship between gas Reynolds number and particle deposition in the rectifying plate system. It is also found from investigation that the particle deposition is greatly affected by the particle parameter. Deposition rate rises with the increase of the particle diameter; however, it reduces gradually with the decrease of particle shape factor. Moreover, the particle mass concentration is an essential dimension that can give a prediction of where the particle may deposit.

The drainage process of a large drop natural gas pipeline after a pressure test is a complicated transient flow process. This process is a gas-phase and liquid-phase flow process connected by a pig, in which the pressure inside the tube, and the flow velocity of gas and liquid, and the movement state of the pig are constantly changing. At the same time, there are also a variety of complicated working conditions such as liquid evaporation and water hammer. Based on the pig transient model, a transient simulation model is established for the upstream gas section and downstream liquid sections of the pipeline in this paper, and the discrete vapor cavity model is used to simulate the drainage process. Taking a large drop pipe section of natural gas pipeline as an example, the paper studied the influences of key parameters such as flow velocity and pressure on the inlet and outlet of the pipeline on the drainage process and analyzed the complicated conditions such as discrete cavity and water hammer in the pipeline during the drainage process. In this paper, the law of pressure variation in the pipe is obtained, and the method of adjusting the inlet and outlet pressure and flow velocity of the pipe section by segmentation is proposed to avoid the occurrence of complex working conditions such as discrete cavity and water hammer.

Due to its strong carbon sequestration function, the accurate estimation method for Moso bamboo carbon storage is the basis of quantitative description for Moso bamboo ecological function and carbon trade in the region. Since common methods for estimating forest carbon storage are unsuitable for Moso bamboo with the empty culm which is no concept of volume and accumulation, this study provided an approach to estimating Moso bamboo carbon storage in the region. Based on the biomass of Moso bamboo permanent sample plots, Moso bamboo biomass probability density was calculated through the mixed Weibull density function, where parameters were fitted with the measured probability by the Kernel Density Method. Then the total carbon storage was estimated by the formula M=ωA∫bcmf(m)dm with the regional area of Moso bamboo forests. Comparisons for this method, the Mean Biomass Method (MBM) and the method on the lowest scale are as follows: 1) The new method takes the area of Moso bamboo as the scale conversion factor to carry out the scale conversion of carbon storage in the region uninvolved in the concept of volume and accumulation. 2) The estimation result of this is more reliable than MBM and simpler than the method on the lowest scale.

During the commissioning process of ”first injection of crude oil after water injection”, due to the density difference between crude oil and water, the oil pressure on the left side of the ”U” section is less than the right hydraulic pressure, and the running process of the oil head is stagnated in a hilly oil pipeline with high elevation difference. Concerning this problem, solution of discharging pressure by using relief valve in valve station nearby oil–water interfacial point is proposed in this paper. According to the actual data, gas–liquid flow in a gas-cap empty process of a big drop and hilly oil pipeline was numerically investigated by dynamic multiphase simulation software OLGA. Simulation data in terms of flow rate, pressure and leakage were compared under different leaking apertures. The simulation results show that the general pressure variation tendencies at the vent, bottom point or top and low elbows show no connection with vent diameters but its final fluctuation that the smaller the diameter is, the more intensive the fluctuation gets.. And as for the emptying of a big drop and hilly pipeline, appropriate increase of leaking aperture can improve the drainage ratio (leakage/general capacity of the pipeline) and drainage rate, but excessive aperture will cause severe negative pressure and breakage cavity which foster the likelihood of close water-surge and damage to the pipe safety. Keywords: Big drop, Oil pipeline, U-type, Water discharge, Leaking aperture

Based on the mutual coupling effect among the compressor, the air cooler and pipes in the system of natural gas pipeline, innovatively with the goal of minimum energy consumption, this paper established a combined operation optimization model of the air cooler and compressor through the optimization of the switching scheme of compressors and air coolers, which can greatly reduce the production energy consumption of the pipeline system. Moreover, when the air temperature is taken as an optimization variable, the most proper temperature to start the air cooler of each compressor station can be worked out to guide the optimized operation of the pipeline, which is of high value for promotion and application. The case analysis of west-east natural gas pipeline II showed that among genetic algorithm (GA), particle swarm optimization (PSO), and simulated annealing (SA) algorithm that are used to solve the optimization model, the genetic algorithm is the fastest, and the simulated annealing algorithm the slowest, but the optimization results of the simulated annealing algorithm is the best, in which the reduced production energy consumption accounted for 33.77%, testifying the practicability and creativity of the optimization model.

As the operation process of natural gas pipeline are affected by gas sources and the fluctuation of consumers' gas consumption, and the operation state changes with time, the transient optimization technology is more accurate and reliable for analysis. Based on the previous researches, this paper established a transient optimization model of natural gas pipeline for the purpose of minimum energy consumption. The model designer considered the switching condition of the compressor and the terminal condition of pipeline, introduced the measures of “pressure-regulating” and “flow-restricted”, and proposed a heuristic algorithm. The case analysis of West-East Gas Pipeline I showed that the optimization calculation can be completed within 15 minutes by an ordinary computer within a 24-hour optimization period. Moreover, the feasibility of the model and the calculation method is verified by the comparison between the result of transient operation optimization and that of steady operation optimization.

A considerable amount of oil contamination is caused by the presence of the trailing oil. This paper aims to simulate and analyze the influences of trailing oil on the quality of oil products in undulating sections. By studying the formation mechanism of mixed oil at inclining pipeline sections and the influences of velocity and oil batches on incline sections, as well as both ups and downs, the correlation is obtained between replacement time of different batches and velocity at various sections. By applying FLUENT 14.5, the maximum time of volume fraction of contaminant oil from 1% to 99% is simulated at cross-sections among different pipeline sections. Aiming at the relationship between oil product replacement time and change time of mixing section volume fraction and flow velocity, the mixing increment of undulating section relative to straight section is obtained. Combining with the empirical mixing length calculation equation, the equation for calculating mixing length considering terrain undulation is obtained. Combined with the actual operation data of Lan-Chengyu’s product oil pipeline, the error of the new mixed oil length calculation equation and actual oil mixing is 0.7966%. Excessive cutting amount of mixed oil will result in the waste of refined oil, and the less cutting amount will cause pollution of refined oil. The new mixed oil length calculation equation can more accurately guide the oil mixing cutting work at the oil station.

Bamboo forests are widespread in subtropical areas and are well known for their rapid growth and great carbon sequestration ability. To recognize the potential roles and functions of bamboo forests in regional ecosystems, forest aboveground biomass (AGB)—which is closely related to forest productivity, the forest carbon cycle, and, in particular, carbon sinks in forest ecosystems—is calculated and applied as an indicator. Among the existing studies considering AGB estimation, linear or nonlinear regression models are the most frequently used; however, these methods do not take the influence of spatial heterogeneity into consideration. A geographically weighted regression (GWR) model, as a spatial local model, can solve this problem to a certain extent. Based on Landsat 8 OLI images, we use the Random Forest (RF) method to screen six variables, including TM457, TM543, B7, NDWI, NDVI, and W7B6VAR. Then, we build the GWR model to estimate the bamboo forest AGB, and the results are compared with those of the cokriging (COK) and orthogonal least squares (OLS) models. The results show the following: (1) The GWR model had high precision and strong prediction ability. The prediction accuracy (R2) of the GWR model was 0.74, 9%, and 16% higher than the COK and OLS models, respectively, while the error (RMSE) was 7% and 12% lower than the errors of the COK and OLS models, respectively. (2) The bamboo forest AGB estimated by the GWR model in Zhejiang Province had a relatively dense spatial distribution in the northwestern, southwestern, and northeastern areas. This is in line with the actual bamboo forest AGB distribution in Zhejiang Province, indicating the potential practical value of our study. (3) The optimal bandwidth of the GWR model was 156 m. By calculating the variable parameters at different positions in the bandwidth, close attention is given to the local variation law in the estimation of the results in order to reduce the model error.

Ultrasonic flow meter has been used in natural gas metering for many years, however, the measurement accuracy of the ultrasonic flow meter is affected by the header, which leads to non-perfect fluid state in the flow meter. The objective of this research is to discuss the issues of dual-path ultrasonic flowmeter with a header. Computer fluid dynamic (CFD) method is used to simulate standard turbulent model. It is found that the flow state in the downstream is distorted by the header with secondary turbulence, swirl etc., and the velocity distribution of the gas is asymmetric; the farther the distance between the ultrasonic flow meter and the header, the smaller the distortion and the simulation error. When the downstream straight pipe length is greater than 27 − D (Diameter), the flow state will be steady. With the same diameter of the header, the shorter the meter header the greater the distortion of the gas in the downstream pipe. With the same length of the header, the smaller the diameter, the greater the distortion of the gas in the downstream. These results have a great guiding significance in the optimal design of the flow meter installation structure.

A pipeline operation optimization model with minimum energy consumption as the objective function was established based on the dynamic programming method. The model was applied to a 3840 km gas pipeline whose designed pipeline capacity was 170 × 10 8 t/a. There were 40 stations in the line, including 22 compressor stations and 32 compressors. The solution time was controlled within 60 s to show that the algorithm was fast and effective. The number of starting-up compressors in the optimized scheme is two more than that in the actual operation scheme, and the total pressure drop of the pipeline decreased by 3.40 MPa, the average efficiency of the gas turbine units increased by 4.234%, the average efficiency of the electric drive units increased by 4.875%, and the power decreased by 18,720.38 kW, confirming the validity and feasibility of the optimization model.

When a natural gas transmission and distribution station performs a planned or emergency venting operation, the jet noise produced by the natural gas venting pipe can have an intensity as high as 110 dB, thereby severely affecting the production and living environment. Jet noise produced by venting pipes is a type of aerodynamic noise. This study investigates the mechanism that produces the jet noise and the radiative characteristics of jet noise using a computational fluid dynamics method that combines large eddy simulation with the Ffowcs Williams–Hawkings acoustic analogy theory. The analysis results show that the sound pressure level of jet noise is relatively high, with a maximum level of 115 dB in the low-frequency range (0–1000 Hz), and the sound pressure level is approximately the average level in the frequency range of 1000–4000 Hz. In addition, the maximum and average sound pressure levels of the noise at the same monitoring point both slightly decrease, and the frequency of the occurrence of a maximum sound pressure level decreases as the Mach number at the outlet of the venting pipe increases. An increase in the flow rate can result in a shift from low-frequency to high-frequency noise. Subsequently, this study includes a design of an expansion-chamber muffler that reduces the jet noise produced by venting pipes and an analysis of its effectiveness in reducing noise. The results show that the expansion-chamber muffler designed in this study can effectively reduce jet noise by 10–40 dB and, thus, achieve effective noise prevention and control.

The numbers of long-distance transport pipelines constructed in areas with relatively complex terrain and large topographic changes have increased in recent years. A water hammer can occur easily during operational processes, such as the starting and stopping of a pump station, the adjustment of the speed of a pump unit, and a shutdown due to an incident and failure of a regulating valve. These operations may cause fluid column separation and form a dangerous water hammer due to the collapse of air cavities. Water hammers due to the collapse of air cavities are a complicated two-phase (gas–liquid) fluid mechanics problem. This study carries out a theoretical study and a numerical simulation of water hammers that occur due to the collapse of flow interruption–caused air cavities and their prevention. This study establishes and solves a discrete model for air cavities caused by flow interruptions and develops a program to numerically simulate water hammers that occur due to the collapse of these air cavities. In addition, based on an actual pipeline incident in which the stopping of a pump resulted in water hammers at multiple locations due to the collapse of air cavities from fluid column separation, numerical simulations are used to plot the lowest and highest hydraulic head envelope curves and the transient curves of the water hammer at the major points, analyze the transient process of the pipeline system, and propose a preventive measure that can effectively control the water hammer pressure and reduce the occurrence of incidents.

There are many compressor stations along long-distance natural gas pipelines. Natural gas can be transported using different boot programs and import pressures, combined with temperature control parameters. Moreover, different transport methods have correspondingly different energy consumptions. At present, the operating parameters of many pipelines are determined empirically by dispatchers, resulting in high energy consumption. This practice does not abide by energy reduction policies. Therefore, based on a full understanding of the actual needs of pipeline companies, we introduce production unit consumption indicators to establish an objective function for achieving the goal of lowering energy consumption. By using a dynamic programming method for solving the model and preparing calculation software, we can ensure that the solution process is quick and efficient. Using established optimization methods, we analyzed the energy savings for the XQ gas pipeline. By optimizing the boot program, the import station pressure, and the temperature parameters, we achieved the optimal energy consumption. By comparison with the measured energy consumption, the pipeline now has the potential to reduce energy consumption by 11 to 16 percent.

RN and SSR approaches are designed to detect NLOS propagation paths in this paper. When the NLOS propagation paths are detected, an estimation approach for the NLOS range errors is proposed by using residual-error decomposition. The approach can estimate the NLOS range errors quickly and effectively, even if there are multiple NLOS propagation paths. Combining the movement equation with observation position, the position of mobile target node can be tracked precisely with Kalman filter algorithm. Using the estimated NLOS range errors, we correct the localization result and modify Kalman filter to mitigate the NLOS propagations. The simulations demonstrate the validity with RN and SSR detection methods and analyze the impacts of NLOS range errors and number of NLOS anchor nodes. The estimated NLOS range errors are proved to be close to the true especially when the NLOS range errors are much bigger than LOS range errors. The simulation results show that the position of target node can be tracked precisely and effectively, when the NLOS mitigation is used to track the target node position with modified Kalman filter.