8 research outputs found
Research on Overflow Monitoring Mechanism Based on Downhole Microflow Detection
The flow rate variation of the drilling fluid and micro-overflow loss is difficult to analyze. The purpose to prevent the occurrence of kick, lost circulation, and other complex conditions is not easy to be achieved. Therefore, the microflow-induced annulus multiphase flow rate and annulus pressure field model were studied, and a downhole microflow measurement system has been developed. A differential pressure type flow measurement was used in the system, and real-time downhole information was obtained to achieve deep, narrow windows and other safety-density complex formation security. This paper introduced a new bottom-hole flow meter which can measure the annular flux while drilling and monitor overflow and circulation loss. The accuracy and reliability of the MPD (managed pressure drilling) system can be improved obviously by applying the device; as a result, the safety of drilling is enhanced and the cost is reduced
The Comparison between Endoscopic Submucosal Dissection and Surgery in Gastric Cancer: A Systematic Review and Meta-Analysis
Aims. There are two treatment modalities for early gastric cancer (EGC)—surgery and endoscopic submucosal dissection (ESD). We aimed to compare the safety and efficacy of ESD with surgery. Method. The article was performed by searching PubMed databases. Data were extracted using predefined form and odds ratios (OR) with 95% confidence intervals (CI) calculated and P value. Results. 13 studies were identified. The incidence of perforation in two groups was different [OR = 6.18 (95% CI: 1.37–27.98), P=0.02]. The prevalences of synchronous and metachronous cancer in the ESD group were higher than those in the surgery group [OR = 8.52 (95% CI: 1.99–36.56), P = 0.004 and OR = 7.15 (95% CI: 2.95–17.32), P<0.0001]. The recurrence and complete resection rates were different [OR = 6.93 (95% CI: 2.83–16.96), P<0.0001 and OR = 0.32 (95% CI: 0.20–0.52), P<0.00001]. Compared with the surgery group, the hospital stay was shorter [IV = −7.15 (95% CI: −9.08–5.22), P<0.00001], the adverse event rate was lower, and the quality of life (QOL) was better in the ESD group. The difference of bleeding was not found. Conclusion. ESD appears to be preferable for EGC, due to a lower rate of adverse events, shorter hospital stay, cheaper cost, and higher QOL
Method of Wireless Sensor Network Node Deployment for the Emergency Environment
Incidents could not always be avoided, resulting in significant losses for the state property and people's safety. Effective monitoring of incidents is becoming more and more important. Wireless sensor networks (WSNs) are widely used in environmental monitoring. On the basis of the existing wireless sensor network node deployment model, a network node deployment model was proposed, which was used in the monitoring of unexpected accidents. The model area was divided into the core area and the evacuation area, and different monitoring nodes deployment plans were applied in different areas. The simulation experiment is carried out by MATLAB, and the simulation results of the node coverage are obtained. Results show that the model for the practical application of the node deployment provides an effective deployment plan, as well as offers a strong basis for real-time monitoring and post-accident emergency evacuation
Method of Wireless Sensor Network Node Deployment for the Emergency Environment
Incidents could not always be avoided, resulting in significant losses for the state property and people's safety. Effective monitoring of incidents is becoming more and more important. Wireless sensor networks (WSNs) are widely used in environmental monitoring. On the basis of the existing wireless sensor network node deployment model, a network node deployment model was proposed, which was used in the monitoring of unexpected accidents. The model area was divided into the core area and the evacuation area, and different monitoring nodes deployment plans were applied in different areas. The simulation experiment is carried out by MATLAB, and the simulation results of the node coverage are obtained. Results show that the model for the practical application of the node deployment provides an effective deployment plan, as well as offers a strong basis for real-time monitoring and post-accident emergency evacuation
Design and Optimization of Annular Flow Electromagnetic Measurement System for Drilling Engineering
Using the downhole annular flow measurement system to get real-time information of downhole annular flow is the core and foundation of downhole microflux control drilling technology. The research work of electromagnetic flowmeter in recent years creates a challenge to the design of downhole annular flow measurement. This paper proposes a design and optimization of annular flow electromagnetic measurement system for drilling engineering based on the finite element method. Firstly, the annular flow measuring and optimization principle are described. Secondly, a simulation model of an annular flow electromagnetic measurement system with two pairs of coil is built based on the fundamental equation of electromagnetic flowmeter by COMSOL. Thirdly, simulations of the structure of excitation system of the measurement system are carried out, and simulations of the size of the electrode’s radius are also carried out based on the optimized structure, and then all the simulation results are analyzed to evaluate the optimization effect based on the evaluation indexes. The simulation results show that optimized shapes of the excitation system and electrode size can yield a better performance in the annular flow measurement
Real-Time and Robust Compressive Background Subtraction for Embedded Camera Networks
Real-time target tracking is an important service provided by embedded camera networks. The first step in target tracking is to extract the moving targets from the video frames, which can be realised by using background subtraction. For a background subtraction method to be useful in embedded camera networks, it must be both accurate and computationally efficient because of the resource constraints on embedded platforms. This makes many traditional background subtraction algorithms unsuitable for embedded platforms because they use complex statistical models to handle subtle illumination changes. These models make them accurate but the computational requirement of these complex models is often too high for embedded platforms. In this paper, we propose a new background subtraction method which is both accurate and computationally efficient. We propose a baseline version which uses luminance only and then extend it to use colour information. The key idea is to use random projection matrics to reduce the dimensionality of the data while retaining most of the information. By using multiple datasets, we show that the accuracy of our proposed background subtraction method is comparable to that of the traditional background subtraction methods. Moreover, to show the computational efficiency of our methods is not platform specific, we implement it on various platforms. The real implementation shows that our proposed method is consistently better and is up to six times faster, and consume significantly less resources than the conventional approaches. Finally, we demonstrated the feasibility of the proposed method by the implementation and evaluation of an end-to-end real-time embedded camera network target tracking application
The Comparison between Endoscopic Submucosal Dissection and Surgery in Gastric Cancer: A Systematic Review and Meta-Analysis
Aims. There are two treatment modalities for early gastric cancer (EGC)—surgery and endoscopic submucosal dissection (ESD). We aimed to compare the safety and efficacy of ESD with surgery. Method. The article was performed by searching PubMed databases. Data were extracted using predefined form and odds ratios (OR) with 95% confidence intervals (CI) calculated and P value. Results. 13 studies were identified. The incidence of perforation in two groups was different [OR = 6.18 (95% CI: 1.37–27.98), P=0.02]. The prevalences of synchronous and metachronous cancer in the ESD group were higher than those in the surgery group [OR = 8.52 (95% CI: 1.99–36.56), P = 0.004 and OR = 7.15 (95% CI: 2.95–17.32), P<0.0001]. The recurrence and complete resection rates were different [OR = 6.93 (95% CI: 2.83–16.96), P<0.0001 and OR = 0.32 (95% CI: 0.20–0.52), P<0.00001]. Compared with the surgery group, the hospital stay was shorter [IV = −7.15 (95% CI: −9.08–5.22), P<0.00001], the adverse event rate was lower, and the quality of life (QOL) was better in the ESD group. The difference of bleeding was not found. Conclusion. ESD appears to be preferable for EGC, due to a lower rate of adverse events, shorter hospital stay, cheaper cost, and higher QOL