In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy sec...In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy security. In order to improve the quality of water injection in the oilfield and gradually achieve efficient and stable production, Bohai Oilfield has launched a water injection well pressure optimization project, focusing on improving the efficiency and quality of water injection in the water injection wells, in order to achieve the optimal water injection plan. In practical work, P Oilfield continues to promote the development of water injection well pressure optimization projects, emphasizing practical exploration and continuous optimization of work plans. However, during the project implementation process, there were some problems, one of which was that the statistics of cumulative injection volume were not scientific enough, resulting in a more comprehensive and accurate presentation of the actual results of pressure optimization work. In the context of continuous improvement work, after careful analysis and research, P Oilfield has decided to optimize the cumulative injection rate algorithm to guide the oilfield’s water injection work in a more refined way, ensuring sufficient and good water injection, and enhancing the oilfield’s production efficiency and comprehensive competitiveness.展开更多
In this work,an oscillating-body wave energy converter(OBWEC)with a hydraulic power take-off(PTO)system named“Dolphin 1”is designed,in which the hydraulic PTO system is equivalent to a transfer station and plays a c...In this work,an oscillating-body wave energy converter(OBWEC)with a hydraulic power take-off(PTO)system named“Dolphin 1”is designed,in which the hydraulic PTO system is equivalent to a transfer station and plays a crucial role in ensuring the stability of the electrical energy output and the efficiency of the overall system.A corresponding mathematical model for the hydraulic PTO system has been established,the factors that influence its performance have been studied,and an algorithm for solving the optimal working pressure has been derived in this paper.Moreover,a PID control method to enable the hydraulic PTO system to automatically achieve optimal performance under different wave conditions has been designed.The results indicate that,compared with single-chamber hydraulic cylinders,double-chamber hydraulic cylinders have a wider application range and greater performance;the accumulator can stabilize the output power of the hydraulic PTO system and slightly increase it;excessively large or small hydraulic motor displacement hinders system performance;and each wave condition corresponds to a unique optimal working pressure for the hydraulic PTO system.In addition,the relationship between the optimal working pressure P_(m)and the pressure P_(h)of the wave force acting on the piston satisfies P_(m)^(2)=∫_(t_(1))^(t_(2))P_(h)^(2)dt/(t_(2)-t_(1)).Furthermore,adjusting the hydraulic motor displacement automatically via a PID controller ensures that the actual working pressure of the hydraulic PTO system consistently reaches or approaches its theoretically optimal value under various wave conditions,which is a very effective control method for enhancing the performance of the hydraulic PTO system.展开更多
Background: Non-implantable bone anchored hearing devices (BCHDs) are utilized for patients with conductive or mixed hearing loss who are unsuitable for conventional hearing aids or have unresolved middle ear issues. ...Background: Non-implantable bone anchored hearing devices (BCHDs) are utilized for patients with conductive or mixed hearing loss who are unsuitable for conventional hearing aids or have unresolved middle ear issues. These devices can be surgically implanted or attached using adhesive plates, dental sticks, elastic headbands, or bone conduction spectacles. Optimal fitting of bone conduction spectacles requires appropriate frame selection and contact pressure in the temporal and mastoid areas. The ANSI S3.6 and DIN EN ISO 389-3 standards recommend a contact area of approximately 1.75 cm2 and a maximum force of 5.4 N for effective sound transmission and comfort. Methods: This study aimed to evaluate the technical fit and mechanical stability of universal bone conduction hearing spectacles compared to established systems. A Sen-Pressure 02 thin-film sensor connected to an Arduino Uno R3 board measured contact force in the temporal and mastoid areas. Several BCHDs were tested, including the Bruckhoff la belle BC D50/70, Radioear B71 headset, Radioear B71 elastic headband, Cochlear Baha SoundArc M, and Cochlear Baha elastic headband, on a PVC artificial head, with data analyzed using ANOVA and LSD post hoc tests. Results: The la belle BC D50/70 spectacles showed comparable contact force to established BCHDs, ensuring adequate sound transmission and comfort. Significant differences were observed between the systems, with the Radioear B71 headset exhibiting the highest forces. The la belle BC D50/70 had similar forces to the Radioear B71 elastic headband. Conclusion: The la belle BC D50/70 universal bone conduction hearing spectacles are a technically equivalent alternative to established BCHDs, maintaining pressure below 5.4 N. Future research should explore the impact of different contact forces on performance and comfort, and the integration of force control in modified spectacles. This study indicates that the la belle BC D50/70 is a viable alternative that meets audiological practice requirements.展开更多
A surrogate based particle swarm optimization （SBPSO） algorithm which combines the surrogate modeling technique and particle swarm optimization is applied to the reliability- based robust design （RBRD） of composit...A surrogate based particle swarm optimization （SBPSO） algorithm which combines the surrogate modeling technique and particle swarm optimization is applied to the reliability- based robust design （RBRD） of composite pressure vessels. The algorithm and efficiency of SBPSO are displayed through numerical examples. A model for filament-wound composite pressure vessels with metallic liner is then studied by netting analysis and its responses are analyzed by using Finite element method （performed by software ANSYS）. An optimization problem for maximizing the performance factor is formulated by choosing the winding orientation of the helical plies in the cylindrical portion, the thickness of metal liner and the drop off region size as the design variables. Strength constraints for composite layers and the metal liner are constructed by using Tsai-Wu failure criterion and Mises failure criterion respectively. Numerical examples show that the method proposed can effectively solve the RBRD problem, and the optimal results of the proposed model can satisfy certain reliability requirement and have the robustness to the fluctuation of design variables.展开更多
At the beginning of 1980’s, the power equipment manufacturing industry in China introduced patent technology on designing and manufacturing the turbine, generator, boiler and their auxiliaries from USA owing to the p...At the beginning of 1980’s, the power equipment manufacturing industry in China introduced patent technology on designing and manufacturing the turbine, generator, boiler and their auxiliaries from USA owing to the policy of opening and reformation. In the meantime, our works also imported the patent technology on designing展开更多
In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based...In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based on the Gustav Lorntzen cycle. Emphasis was focused on how to determine the optimal discharge pressure of compressor in CO2 trans-critical cycle. The factors related with the optimal discharge pressure were analyzed. A formula was developed based on cycle simulation, which could be used to predict the optimal discharge pressure of a basic CO2 trans-critical cycle. After further studies on CO2 trans-critical cycles with a regenerator or expander, two more formulas were also developed. These formulas could provide an access to improve the COP of CO2 trans-critical cycle.展开更多
In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate...In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relation- ship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.展开更多
Background When resuscitating patients with septic shock,cerebrovascular reactivity parameters are calculated by monitoring regional cerebral oxygen saturation(rSO_(2))using near-infrared spectroscopy to determine the...Background When resuscitating patients with septic shock,cerebrovascular reactivity parameters are calculated by monitoring regional cerebral oxygen saturation(rSO_(2))using near-infrared spectroscopy to determine the optimal blood pressure.Here,we aimed to analyze the impact of cerebral autoregulation-directed optimal blood pressure management on the incidence of delirium and the prognosis of patients with septic shock.Methods This prospective randomized controlled clinical study was conducted in the Xiangya Hospital of Central South University,China.Fifty-one patients with septic shock(December 2020–May 2022)were enrolled and randomly allocated to the experimental(n=26)or control group(n=25).Using the ICM+software,we monitored the dynamic changes in rSO_(2) and mean arterial pressure(MAP)and calculated the cerebrovascular reactivity parameter tissue oxygen reactivity index to determine the optimal blood pressure to maintain normal cerebral autoregulation function during resuscitation in the experimental group.The control group was treated according to the Surviving Sepsis Campaign Guidelines.Differences in the incidence of delirium and 28-day mortality between the two groups were compared,and the risk factors were analyzed.Results The 51 patients,including 39 male and 12 female,had a mean age of(57.0±14.9)years.The incidence of delirium was 40.1%(23/51),and the 28-day mortality rate was 29.4%(15/51).The mean MAP during the first 24 h of intensive care unit(ICU)admission was higher([84.5±12.2]mmHg vs.[77.4±11.8]mmHg,P=0.040),and the incidence of delirium was lower(30.8%vs.60.0%,P=0.036)in the experimental group than in the control group.The use of cerebral autoregulation-directed optimal blood pressure(odds ratio[OR]=0.090,95%confidence interval[CI]:0.009 to 0.923,P=0.043)and length of ICU stay(OR=1.473,95%CI:1.093 to 1.985,P=0.011)were risk factors for delirium during septic shock.Vasoactive drug dose(OR=8.445,95%CI:1.26 to 56.576,P=0.028)and partial pressure of oxygen(PaO_(2))(OR=0.958,95%CI:0.921 to 0.996,P=0.032)were the risk factors for 28-day mortality.Conclusions The use of cerebral autoregulation-directed optimal blood pressure management during shock resuscitation reduces the incidence of delirium in patients with septic shock.展开更多
This study adopts a reliability-based optimization approach for the failure mechanism analysis and design of the retaining wall considering nonlinear soil backfills.The assumed failure mechanism is represented by rigi...This study adopts a reliability-based optimization approach for the failure mechanism analysis and design of the retaining wall considering nonlinear soil backfills.The assumed failure mechanism is represented by rigid blocks within a kinematically admissible framework in a rotational coordinate system.Then the active and passive earth pressures are derived from the optimization procedure.A convenient way for incorporating seepage effects is proposed and implemented in the nonlinear upper bound analysis.Finally,a novel response surface method is employed to calculate the failure probability considering different probabilistic scenarios and distribution types with high calculation efficacy.The accuracy of the proposed method is evaluated using the Monte Carlo simulations with 1 million trials.Sensitivity analysis indicated that soil unit weight and initial cohesion are the critical factors dominating the failure probability of passive and active mechanism,respectively.The reliability-based design can be performed to obtain the safe range of the lateral force against nonlinear soil backfills with a target failure probability.展开更多
文摘In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy security. In order to improve the quality of water injection in the oilfield and gradually achieve efficient and stable production, Bohai Oilfield has launched a water injection well pressure optimization project, focusing on improving the efficiency and quality of water injection in the water injection wells, in order to achieve the optimal water injection plan. In practical work, P Oilfield continues to promote the development of water injection well pressure optimization projects, emphasizing practical exploration and continuous optimization of work plans. However, during the project implementation process, there were some problems, one of which was that the statistics of cumulative injection volume were not scientific enough, resulting in a more comprehensive and accurate presentation of the actual results of pressure optimization work. In the context of continuous improvement work, after careful analysis and research, P Oilfield has decided to optimize the cumulative injection rate algorithm to guide the oilfield’s water injection work in a more refined way, ensuring sufficient and good water injection, and enhancing the oilfield’s production efficiency and comprehensive competitiveness.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52071094 and 51979065).
文摘In this work,an oscillating-body wave energy converter(OBWEC)with a hydraulic power take-off(PTO)system named“Dolphin 1”is designed,in which the hydraulic PTO system is equivalent to a transfer station and plays a crucial role in ensuring the stability of the electrical energy output and the efficiency of the overall system.A corresponding mathematical model for the hydraulic PTO system has been established,the factors that influence its performance have been studied,and an algorithm for solving the optimal working pressure has been derived in this paper.Moreover,a PID control method to enable the hydraulic PTO system to automatically achieve optimal performance under different wave conditions has been designed.The results indicate that,compared with single-chamber hydraulic cylinders,double-chamber hydraulic cylinders have a wider application range and greater performance;the accumulator can stabilize the output power of the hydraulic PTO system and slightly increase it;excessively large or small hydraulic motor displacement hinders system performance;and each wave condition corresponds to a unique optimal working pressure for the hydraulic PTO system.In addition,the relationship between the optimal working pressure P_(m)and the pressure P_(h)of the wave force acting on the piston satisfies P_(m)^(2)=∫_(t_(1))^(t_(2))P_(h)^(2)dt/(t_(2)-t_(1)).Furthermore,adjusting the hydraulic motor displacement automatically via a PID controller ensures that the actual working pressure of the hydraulic PTO system consistently reaches or approaches its theoretically optimal value under various wave conditions,which is a very effective control method for enhancing the performance of the hydraulic PTO system.
文摘Background: Non-implantable bone anchored hearing devices (BCHDs) are utilized for patients with conductive or mixed hearing loss who are unsuitable for conventional hearing aids or have unresolved middle ear issues. These devices can be surgically implanted or attached using adhesive plates, dental sticks, elastic headbands, or bone conduction spectacles. Optimal fitting of bone conduction spectacles requires appropriate frame selection and contact pressure in the temporal and mastoid areas. The ANSI S3.6 and DIN EN ISO 389-3 standards recommend a contact area of approximately 1.75 cm2 and a maximum force of 5.4 N for effective sound transmission and comfort. Methods: This study aimed to evaluate the technical fit and mechanical stability of universal bone conduction hearing spectacles compared to established systems. A Sen-Pressure 02 thin-film sensor connected to an Arduino Uno R3 board measured contact force in the temporal and mastoid areas. Several BCHDs were tested, including the Bruckhoff la belle BC D50/70, Radioear B71 headset, Radioear B71 elastic headband, Cochlear Baha SoundArc M, and Cochlear Baha elastic headband, on a PVC artificial head, with data analyzed using ANOVA and LSD post hoc tests. Results: The la belle BC D50/70 spectacles showed comparable contact force to established BCHDs, ensuring adequate sound transmission and comfort. Significant differences were observed between the systems, with the Radioear B71 headset exhibiting the highest forces. The la belle BC D50/70 had similar forces to the Radioear B71 elastic headband. Conclusion: The la belle BC D50/70 universal bone conduction hearing spectacles are a technically equivalent alternative to established BCHDs, maintaining pressure below 5.4 N. Future research should explore the impact of different contact forces on performance and comfort, and the integration of force control in modified spectacles. This study indicates that the la belle BC D50/70 is a viable alternative that meets audiological practice requirements.
基金supported by the Natural Science Foundation of China(No.10772070)National Basic Research Program of China(No.2011CB013800)
文摘A surrogate based particle swarm optimization （SBPSO） algorithm which combines the surrogate modeling technique and particle swarm optimization is applied to the reliability- based robust design （RBRD） of composite pressure vessels. The algorithm and efficiency of SBPSO are displayed through numerical examples. A model for filament-wound composite pressure vessels with metallic liner is then studied by netting analysis and its responses are analyzed by using Finite element method （performed by software ANSYS）. An optimization problem for maximizing the performance factor is formulated by choosing the winding orientation of the helical plies in the cylindrical portion, the thickness of metal liner and the drop off region size as the design variables. Strength constraints for composite layers and the metal liner are constructed by using Tsai-Wu failure criterion and Mises failure criterion respectively. Numerical examples show that the method proposed can effectively solve the RBRD problem, and the optimal results of the proposed model can satisfy certain reliability requirement and have the robustness to the fluctuation of design variables.
文摘At the beginning of 1980’s, the power equipment manufacturing industry in China introduced patent technology on designing and manufacturing the turbine, generator, boiler and their auxiliaries from USA owing to the policy of opening and reformation. In the meantime, our works also imported the patent technology on designing
基金This work was supported by Beijing Foundation for Academic Human Resources Development in Institution and the Beijing Foundation for Natural Science
文摘In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based on the Gustav Lorntzen cycle. Emphasis was focused on how to determine the optimal discharge pressure of compressor in CO2 trans-critical cycle. The factors related with the optimal discharge pressure were analyzed. A formula was developed based on cycle simulation, which could be used to predict the optimal discharge pressure of a basic CO2 trans-critical cycle. After further studies on CO2 trans-critical cycles with a regenerator or expander, two more formulas were also developed. These formulas could provide an access to improve the COP of CO2 trans-critical cycle.
文摘In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relation- ship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.
基金supported by the National Natural Science Foundation of China(82372199)National Natural Science Foundation of China(81901264,81974285)Clinical Medical Technology Innovation Guidance Project of Hunan Science and Technology Department(2021SK53803).
文摘Background When resuscitating patients with septic shock,cerebrovascular reactivity parameters are calculated by monitoring regional cerebral oxygen saturation(rSO_(2))using near-infrared spectroscopy to determine the optimal blood pressure.Here,we aimed to analyze the impact of cerebral autoregulation-directed optimal blood pressure management on the incidence of delirium and the prognosis of patients with septic shock.Methods This prospective randomized controlled clinical study was conducted in the Xiangya Hospital of Central South University,China.Fifty-one patients with septic shock(December 2020–May 2022)were enrolled and randomly allocated to the experimental(n=26)or control group(n=25).Using the ICM+software,we monitored the dynamic changes in rSO_(2) and mean arterial pressure(MAP)and calculated the cerebrovascular reactivity parameter tissue oxygen reactivity index to determine the optimal blood pressure to maintain normal cerebral autoregulation function during resuscitation in the experimental group.The control group was treated according to the Surviving Sepsis Campaign Guidelines.Differences in the incidence of delirium and 28-day mortality between the two groups were compared,and the risk factors were analyzed.Results The 51 patients,including 39 male and 12 female,had a mean age of(57.0±14.9)years.The incidence of delirium was 40.1%(23/51),and the 28-day mortality rate was 29.4%(15/51).The mean MAP during the first 24 h of intensive care unit(ICU)admission was higher([84.5±12.2]mmHg vs.[77.4±11.8]mmHg,P=0.040),and the incidence of delirium was lower(30.8%vs.60.0%,P=0.036)in the experimental group than in the control group.The use of cerebral autoregulation-directed optimal blood pressure(odds ratio[OR]=0.090,95%confidence interval[CI]:0.009 to 0.923,P=0.043)and length of ICU stay(OR=1.473,95%CI:1.093 to 1.985,P=0.011)were risk factors for delirium during septic shock.Vasoactive drug dose(OR=8.445,95%CI:1.26 to 56.576,P=0.028)and partial pressure of oxygen(PaO_(2))(OR=0.958,95%CI:0.921 to 0.996,P=0.032)were the risk factors for 28-day mortality.Conclusions The use of cerebral autoregulation-directed optimal blood pressure management during shock resuscitation reduces the incidence of delirium in patients with septic shock.
文摘This study adopts a reliability-based optimization approach for the failure mechanism analysis and design of the retaining wall considering nonlinear soil backfills.The assumed failure mechanism is represented by rigid blocks within a kinematically admissible framework in a rotational coordinate system.Then the active and passive earth pressures are derived from the optimization procedure.A convenient way for incorporating seepage effects is proposed and implemented in the nonlinear upper bound analysis.Finally,a novel response surface method is employed to calculate the failure probability considering different probabilistic scenarios and distribution types with high calculation efficacy.The accuracy of the proposed method is evaluated using the Monte Carlo simulations with 1 million trials.Sensitivity analysis indicated that soil unit weight and initial cohesion are the critical factors dominating the failure probability of passive and active mechanism,respectively.The reliability-based design can be performed to obtain the safe range of the lateral force against nonlinear soil backfills with a target failure probability.
