As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change ...As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.展开更多
AIM: To determine the feasibility and potential role of combining radiostereometric analysis(RSA), gait analysis and activity monitoring in the follow-up of fracture patients.METHODS: Two patients with similar 41B3 ti...AIM: To determine the feasibility and potential role of combining radiostereometric analysis(RSA), gait analysis and activity monitoring in the follow-up of fracture patients.METHODS: Two patients with similar 41B3 tibial plateau fractures were treated by open reduction internal fixation augmented with impaction bone grafting and were instructed to partial weight bear to 10 kg for the first six postoperative weeks. Fracture reduction and fixation were assessed by postoperative computer tomographic(CT) scanning. Both patients had tantalum markers inserted intra-operatively to monitor their fracture stability during healing using RSA and differentially loaded RSA(DLRSA) at 6 and 12 wk postoperatively. Gait analyses were performed at 1, 2, 6, and 12 wk postoperatively. Activity monitors were worn for 4 wk between the 2 and 6 wk appointments. In addition to gait analysis, knee function was assessed using the patient reported Lysholm scores, and doctor reported knee range of motion and stability, at 6 and 12 wk postoperatively.RESULTS: There were no complications. CT demonstrated that both fractures were reduced anatomically. Gait analysis indicated that Patient 1 bore weight to 60% of body weight at 2 wk postoperative and 100% at 6 wk. Patient 2 bore weight at 10% of body weight to 6 wk and had very low joint contact forces to that time. At 12 wk however, there was no difference between the gait patterns in the two patients. Patient 1 increased activities of moderate-vigorous intensity from 20 to 60 min/d between 2 and 6 postoperative weeks, whereas Patient 2 remained more stable at 20-30 min/d. The Lysholm scores were similar for both patients and did not improve between 6 and 12 wk postoperatively. DLRSA examination at 12 wk showed that both patients were comfortable to weight bear to 80 kg and under this weight the fractures displaced less than 0.4 mm. RSA measurements demonstrated over time fracture migrations of less than 2 mm in both cases. However, Patient 2, who followed the postoperative weight bearing instructions most closely, displaced less(0.3 mm vs 1.6 mm). CONCLUSION: This study demonstrates the potential of using a combination of RSA, gait analysis and activity monitoring to obtain a comprehensive evidence base for postoperative weight bearing schedules during fracture healing.展开更多
Remote sensing, one of the most important reconnaissance and feature identifying tools generally applied for surface and groundwater investigation, was used for water resources mapping for the lower Son Valley in this...Remote sensing, one of the most important reconnaissance and feature identifying tools generally applied for surface and groundwater investigation, was used for water resources mapping for the lower Son Valley in this study. The mapping was done with the help of Indian Remote Sensing (IRS) satellite imagery IRS-LISS- 1-B1 for January 29, 1991 obtained during the day transit time. The area under study comprises adjoining parts of Uttar Pradesh and Bihar states of India and extends over the seven districts, namely Bhojpur, Rohtas, Patna, Jahanabad, Aurangabad, Ballia and Chapra. Geology of the study area is quite complex, tectonically disturbed and shows four major cycles of depositions after erosions during last one billion years (since Cretaceous). Two lineaments mapped by GSI (Geological Survey of India) in western side of river Son in the Bhojpur district can also be identified by the satellite imagery. In the present study, apart from these lineaments, two new lineaments have been investigated, which run almost parallel to river Ganga in northwest parts of the area in Ballia district. The lineaments may play a very vital role in groundwater monitoring in the area. The detailed study of geomorphology, vegetation and geology of the Lower Son valley on the basis of photo-interpretation techniques for surface features, drainage pattern and density, and drainage texture has been carried out to determine alluvial type, permeability, tributary, etc. These studies and Darcy velocity analysis show that the prospect of water is very good for entire lower Son valley. The Bhojpur district is most prospective for groundwater exploitation.展开更多
A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are un...A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.展开更多
基金supported jointly by the major projects of Basic and Applied Basic Research in Guangdong Province“Key Basic Theory Research for Natural Gas Hydrate Trial Production in Shenhu Pilot Test Area”(2020B0301030003)the project from Southern Marine Science&Engineering Guangdong Laboratory in Guangzhou City“Research on New Closed Circulation Drilling Technology without Riser”(GML2019ZD0501).
文摘As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.
文摘AIM: To determine the feasibility and potential role of combining radiostereometric analysis(RSA), gait analysis and activity monitoring in the follow-up of fracture patients.METHODS: Two patients with similar 41B3 tibial plateau fractures were treated by open reduction internal fixation augmented with impaction bone grafting and were instructed to partial weight bear to 10 kg for the first six postoperative weeks. Fracture reduction and fixation were assessed by postoperative computer tomographic(CT) scanning. Both patients had tantalum markers inserted intra-operatively to monitor their fracture stability during healing using RSA and differentially loaded RSA(DLRSA) at 6 and 12 wk postoperatively. Gait analyses were performed at 1, 2, 6, and 12 wk postoperatively. Activity monitors were worn for 4 wk between the 2 and 6 wk appointments. In addition to gait analysis, knee function was assessed using the patient reported Lysholm scores, and doctor reported knee range of motion and stability, at 6 and 12 wk postoperatively.RESULTS: There were no complications. CT demonstrated that both fractures were reduced anatomically. Gait analysis indicated that Patient 1 bore weight to 60% of body weight at 2 wk postoperative and 100% at 6 wk. Patient 2 bore weight at 10% of body weight to 6 wk and had very low joint contact forces to that time. At 12 wk however, there was no difference between the gait patterns in the two patients. Patient 1 increased activities of moderate-vigorous intensity from 20 to 60 min/d between 2 and 6 postoperative weeks, whereas Patient 2 remained more stable at 20-30 min/d. The Lysholm scores were similar for both patients and did not improve between 6 and 12 wk postoperatively. DLRSA examination at 12 wk showed that both patients were comfortable to weight bear to 80 kg and under this weight the fractures displaced less than 0.4 mm. RSA measurements demonstrated over time fracture migrations of less than 2 mm in both cases. However, Patient 2, who followed the postoperative weight bearing instructions most closely, displaced less(0.3 mm vs 1.6 mm). CONCLUSION: This study demonstrates the potential of using a combination of RSA, gait analysis and activity monitoring to obtain a comprehensive evidence base for postoperative weight bearing schedules during fracture healing.
文摘Remote sensing, one of the most important reconnaissance and feature identifying tools generally applied for surface and groundwater investigation, was used for water resources mapping for the lower Son Valley in this study. The mapping was done with the help of Indian Remote Sensing (IRS) satellite imagery IRS-LISS- 1-B1 for January 29, 1991 obtained during the day transit time. The area under study comprises adjoining parts of Uttar Pradesh and Bihar states of India and extends over the seven districts, namely Bhojpur, Rohtas, Patna, Jahanabad, Aurangabad, Ballia and Chapra. Geology of the study area is quite complex, tectonically disturbed and shows four major cycles of depositions after erosions during last one billion years (since Cretaceous). Two lineaments mapped by GSI (Geological Survey of India) in western side of river Son in the Bhojpur district can also be identified by the satellite imagery. In the present study, apart from these lineaments, two new lineaments have been investigated, which run almost parallel to river Ganga in northwest parts of the area in Ballia district. The lineaments may play a very vital role in groundwater monitoring in the area. The detailed study of geomorphology, vegetation and geology of the Lower Son valley on the basis of photo-interpretation techniques for surface features, drainage pattern and density, and drainage texture has been carried out to determine alluvial type, permeability, tributary, etc. These studies and Darcy velocity analysis show that the prospect of water is very good for entire lower Son valley. The Bhojpur district is most prospective for groundwater exploitation.
基金sponsored by the Jinsha River Development Corporation Ltd. Program of China Three Gorges Cooperation (JSJ(06)007)
文摘A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.
