Path planning for recovery is studied on the engineering background of double unmanned surface vehicles(USVs)towing oil booms for oil spill recovery.Given the influence of obstacles on the sea,the improved artificial ...Path planning for recovery is studied on the engineering background of double unmanned surface vehicles(USVs)towing oil booms for oil spill recovery.Given the influence of obstacles on the sea,the improved artificial potential field(APF)method is used for path planning.For addressing the two problems of unreachable target and local minimum in the APF,three improved algorithms are proposed by combining the motion performance constraints of the double USV system.These algorithms are then combined as the final APF-123 algorithm for oil spill recovery.Multiple sets of simulation tests are designed according to the flaws of the APF and the process of oil spill recovery.Results show that the proposed algorithms can ensure the system’s safety in tracking oil spills in a complex environment,and the speed is increased by more than 40%compared with the APF method.展开更多
National navies equip their submarines with Autonomous Underwater Vehicle(AUV)technology.It has become an important component of submarine development in technologically-advanced countries.Employing advanced and relia...National navies equip their submarines with Autonomous Underwater Vehicle(AUV)technology.It has become an important component of submarine development in technologically-advanced countries.Employing advanced and reliable recovery systems directly improves the safety and operational efficiency of submarines equipped with AUVs.In this paper,based on aerial refueling technology,a cone-shaped recovery system with two different guiding covers(closed structure and frame structure)is applied to the submarine.By taking the Suboff model as the research object,STAR-CCM was used to study the influence of the installation position of the recovery system,and the length of the rigid rod,on the Suboff model.It was found that when the recovery system is installed in the middle and rear of the Suboff model at the same velocity and the same length of the rigid rod,the Suboff model has the good stability and less drag.It experiences the largest drag when being installed in the front of the rigid rod.Moreover,when the recovery system is installed in the front and middle of the rigid rod,the drag increases as its length increases,and the lift decreases as its length increases.Compared with the closed structure guiding cover,the Suboff model will have less drag and better stability when the recovery system uses the frame structure guiding cover.Besides,the deflection and vibration of the rigid rod were also analyzed via mathematical theory.展开更多
A qualification test for the reliability of a newly-developed Diver Gas Recovery System (DGRS) was carried out in the Naval Medical Research Institute of the People's Liberation Army, China from March 29 to April ...A qualification test for the reliability of a newly-developed Diver Gas Recovery System (DGRS) was carried out in the Naval Medical Research Institute of the People's Liberation Army, China from March 29 to April 2, 1995. A sequential test plan of high discrimination ratio for the mean time between failures (MTBF) was adopted. The test procedures simulated those of a 300 msw dive. A hyperbaric breathing machine was used for the simulation of diver's respiratory functions. Parameters, such as diving depth, respiratory minute volume (RMV), CO2 production, gas flow rate, partial pressure of carbon dioxide, and ambient temperature and himidity were all displayed and recorded with a microcomputer system. The results indicated that no failure occurred during the 91.5 h operation. According to the acceptance and rejection criteria specified in the statistical test plan, a no-failure score in the 88 h operation is acceptable. Therefore, the DGRS has been demonstrated to meet the requirements of MTBF specified in the contract.展开更多
The common problem of cold strip continuous annealing furnaces is high exhaust gas temperature and great energy consumption. Taking the cold-strip continuous annealing furnaces of Baosteel No. 4 cold mill plant as an ...The common problem of cold strip continuous annealing furnaces is high exhaust gas temperature and great energy consumption. Taking the cold-strip continuous annealing furnaces of Baosteel No. 4 cold mill plant as an example, several waste heat recovery systems in the annealing furnaces are compared and their advantages and disadvantages are analyzed through different energy-saving technologies.展开更多
Highly security-critical system should possess features of continuous service. We present a new Robust Disaster Recovery System Model （RDRSM）. Through strengthening the ability of safe communications, RDRSM guarante...Highly security-critical system should possess features of continuous service. We present a new Robust Disaster Recovery System Model （RDRSM）. Through strengthening the ability of safe communications, RDRSM guarantees the secure and reliable command on disaster recovery. Its self-supervision capability can monitor the integrality and security of disaster recovery system itself. By 2D and 3D rea-time visible platform provided by GIS, GPS and RS, the model makes the using, management and maintenance of disaster recovery system easier. RDRSM possesses predominant features of security, robustness and controllability. And it can be applied to highly security-critical environments such as E-government and bank. Conducted by RDRSM, an important E-government disaster recovery system has been constructed successfully. The feasibility of this model is verified by practice. We especially emphasize the significance of some components of the model, such as risk assessment, disaster recovery planning, system supervision and robust communication support.展开更多
Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter.The cold fresh air of those remote areas can be as severe as40℃ and commonly needs to be heated to around+3℃...Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter.The cold fresh air of those remote areas can be as severe as40℃ and commonly needs to be heated to around+3℃.This extensive amount of heating is usually provided by employing large-size air heaters,fueled by diesel,propane,natural gas,or heavy oil,leading to high energy costs and large carbon footprints.At the same time,the thermal energy content of a diesel generator sets(gen-sets)exhaust is known to be one-third of the total heating value of its combusted fuel.Exhaust heat recovery from diesel gen-sets is a growing technology that seeks to mitigate the energy costs by capturing and redirecting this commonly rejected exhaust heat to other applications such as space heating or pre-heating of the mine intake air.The present study investigated the possibility of employing a simple system based on off-theshelf heat exchanger technology,which can recover the waste heat from the exhaust of the power generation units(diesel gen-sets)in an off-grid,cold,remote mine in Canada for heating of the mine intake air.Data from a real mine was used for the analysis along with environmental data of three different location-scenarios with distinct climates.After developing a thermodynamic model,the heat savings were calculated,and an economic feasibility evaluation was performed.The proposed system was found highly viable with annual savings of up to C$6.7 million and capable enough to provide an average of around 75%of the heating demand for mine intake air,leading to a payback period of about eleven months or less for all scenarios.Deployment of seasonal thermal energy storage has also been recommended to mitigate the mismatch between supply and demand,mainly in summertime,possibly allowing the system to eliminate fuel costs for intake air heating.展开更多
After analyzing the working condition of the conventional diesel forklift,an energy recovery system in hybrid forklift is considered and its simulation model is built.Then,the control strategy for the proposed energy ...After analyzing the working condition of the conventional diesel forklift,an energy recovery system in hybrid forklift is considered and its simulation model is built.Then,the control strategy for the proposed energy recovery system is discussed,which is validated and evaluated by simulation.The simulation results show that the proposed control strategy can achieve balance of the power and keep the state of charge(SOC) of ultra capacitor in a reasonable range,and the fuel consumption can be reduced by about 20.8% compared with the conventional diesel forklift.Finally,the feasibility of the simulation results is experimentally verified based on the lifting energy recovery system.展开更多
In today’s fourth industrial revolution,various blockchain technologies are being actively researched.A blockchain is a peer-to-peer data-sharing structure lacking central control.If a user wishes to access stored da...In today’s fourth industrial revolution,various blockchain technologies are being actively researched.A blockchain is a peer-to-peer data-sharing structure lacking central control.If a user wishes to access stored data,she/he must employ a private key to prove ownership of the data and create a transaction.If the private key is lost,blockchain data cannot be accessed.To solve such a problem,public blockchain users can recover the key using a wallet program.However,key recovery in a permissioned blockchain(PBC)has been but little studied.The PBC server is Honest-but-Curious(HBC),and should not be able to learn anything of the user;the server should simply recover and store the key.The server must also be resistant to malicious attacks.Therefore,key recovery in a PBC must satisfy various security requirements.Here,we present a password-protected secret sharing(PPSS)key recovery system,protected by a secure password from a malicious key storage server of a PBC.We describe existing key recovery schemes and our PPSS scheme.展开更多
Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rank...Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rankine cycle was constructed and the dynamic behavior was presented. In the dynamic test, the pump was stopped and then started. In addition, there was a step change of the flue gas volume flow rate and the converter frequency of multistage pump, respectively. The results indicate that the working fluid flow rate has the shortest response time, followed by the expander inlet pressure and the expander inlet temperature.The operation frequency of pump is a key parameter for the ORC system. Due to a step change of pump frequency(39.49-35.24 Hz),the expander efficiency and thermal efficiency drop by 16% and 21% within 2 min, respectively. Besides, the saturated mixture can lead to an increase of the expander rotation speed.展开更多
In this paper, the underwater vehicle, sling and the mother ship are considered as a single degree of freedom system connected by a spring. Through the analysis of this system, a physical model is established, which d...In this paper, the underwater vehicle, sling and the mother ship are considered as a single degree of freedom system connected by a spring. Through the analysis of this system, a physical model is established, which describes the motion of the vehicle caused by the ship motion and wave motion. Furthermore, a mathematical model based on this physical model is obtained, and a numerical solution program is made. As an example, a practical launch and recovery system fbr an underwater robot is calculated by use of the program, and the motion track of the robot is obtained.展开更多
Concentrating Solar Power(CSP)plants offer a promising way to generate low-emission energy.However,these plants face challenges such as reduced sunlight during winter and cloudy days,despite being located in high sola...Concentrating Solar Power(CSP)plants offer a promising way to generate low-emission energy.However,these plants face challenges such as reduced sunlight during winter and cloudy days,despite being located in high solar radiation areas.Furthermore,their dispatch capacities and yields can be affected by high electricity consumption,particularly at night.The present work aims to develop an off-design model that evaluates the hourly and annual performances of a parabolic trough power plant(PTPP)equipped with a waste heat recovery system.The study aims to compare the performances of this new layout with those of the conventional Andasol 1 plant,with the aim of assessing the improvements achieved in the new design.Based on the results,it can be concluded that the new layout has increased the annual generated power to almost 183 GWh(an increase of about 7.60% is achieved compared to the Andasol 1 layout that generates 169 GWh annually).Additionally,the proposed installation has achieved an efficiency of 20.55%,which represents a 7.87% increase compared to the previous design(19.05%).The Levelized Cost of Electricity(LCOE)of the new layout has been reduced by more than 5.8% compared to the Andasol 1 plant.Specifically,it has decreased from 13.11 to 12.35 c/kWh.This reduction in LCOE highlights the improved cost-effectiveness of the newlayout,making it amore economically viable option for generating electricity compared to the conventional Andasol 1 plant.展开更多
Almost the same quantity to net output work of energy has been carried out and wasted by exhaust gas in typical automotive engine. Recovering the energy from exhaust gas and converting to mechanical energy will dramat...Almost the same quantity to net output work of energy has been carried out and wasted by exhaust gas in typical automotive engine. Recovering the energy from exhaust gas and converting to mechanical energy will dramatically increase the heat efficiency and decrease the fuel consumption. With the increasing demand of fuel conservation, exhaust gas energy recovery technologies have been a hot topic. At present, many researches have been focused on heating or cooling the cab, mechanical energy using and thermo-electronic converting. Unfortunately, the complicated transmission of mechanical energy using and the depressed efficiency of thermo-electronic converting restrict their widely applying. In this paper, a kind of exhaust gas energy recovery system of pneumatic driving automotive engine, in which highly compressed air acts as energy storing and converting carrier, has been established. Pneumatic driving motor can produce moderate speed and high torque output, which is compatible for engine using. The feasibility has been certificated by GT-Power simulation and laboratory testes. The technologies about increasing recovery efficiency have been discussed in detail. The results demonstrated that the in parallel exhaust gas energy recovery system, which is similar to the compound turbo-charger structure can recovery 8 to 10 percent of rated power output. At last, a comprehensive system, which includes Rankine cycle based power wheel cycle unit etc., has been introduced.展开更多
With the emphasis on energy and environmental protection,energy-conservation and emission-reduction become vital issues for industrial development.Moreover,with the development of legislation on marine environment,the...With the emphasis on energy and environmental protection,energy-conservation and emission-reduction become vital issues for industrial development.Moreover,with the development of legislation on marine environment,the marine diesel engine has become focusing on energy saving and emission reduction for ships.For low-speed diesel engines under high load,waste heat from exhaust gas can be recovered by the compact and efficient gas turbine.In this paper,the matching design research between low speed diesel engine and gas turbine is carried out.To balance efficiency and compactness,the impeller was adjusted and generated by ANSYS BLADEGEN,based on 1D thermodynamic design.And the 1D calculation is similar to the ANSYS CFX simulation result:the total-static efficiency is 73.8%compared to 76.7%.Moreover,the flow separation happened at the impeller suction side and created vortex due to the high incidence angle.The off-design operating point simulation of the turbine shows though the pressure ratio increase will cause the efficiency to decline a little,the total shaft power rises.In sum,this paper worked out a power turbine suitable for a low-speed diesel engine according to the turbine character matching design and simulation,which provides foundation to the construction of a steady operation of waste heat recovery system for marine diesel engine.展开更多
This paper presents the control algorithm for supercapacitor based kinetic energy recovery system. Supercapacitor shares energy with the motor drive DC link through bidirectional non-isolated converter. Two cascaded l...This paper presents the control algorithm for supercapacitor based kinetic energy recovery system. Supercapacitor shares energy with the motor drive DC link through bidirectional non-isolated converter. Two cascaded linear regulators control feedback linearized states of the system. As a result, the DC link voltage is stabilized and the supercapacitor voltage and current are limited. Control algorithm does not increase ripple of voltages and currents, and thus life time expectancy of supercapacitor is prolonged. In torque-controlled motor drives, current on DC side can rapidly change with bandwidth as high as 2 kHz. Based on measurements of KERS states, the algorithm estimates rapidly changing motor drive current on DC side and stabilizes the DC link voltage with overshoot less than 2%. Controller is independent from the motor drive parameters and relies only on its own measurements. This enables kinetic energy recovery system （KERS） to be a standalone device.展开更多
Steam is the typical working fluid to drive turbo-generators in coal-fired power plants. It is an effective working fluid, but some of its energy is extracted in an unusable form when condensed. A Power Recovery ...Steam is the typical working fluid to drive turbo-generators in coal-fired power plants. It is an effective working fluid, but some of its energy is extracted in an unusable form when condensed. A Power Recovery Cycle (PRC) using a more volatile Secondary Working Fluid (SWF) added to the steam cycle could improve energy efficiency. PRCs have been applied to the flue gas and for combined cycle systems but not to traditional plant steam cycles. This paper details an analysis of adding a steam cycle PRC to a 500 MW lignite coal-fired power plant. A validated model of the plant was developed and PRCs using the three most attractive SWFs, benzene, methanol and hydrazine, were then added to the model. Adding a benzene, methanol, or hydrazine steam cycle PRC will produce an additional 59, 34, and 49 MW, respectively. An AACE Class 4 factored broad capital cost estimate and comparable operating costs and revenue estimates were developed to evaluate PRC feasibility. The benzene, methanol, and hydrazine processes had 2019 Net Present Values (NPVs) @12% of -$32, -$59, and +$35 million ± 40%, respectively. Thus, a PRC may be profitable at current or modest increases to U.S. Upper Midwest electricity prices of around $0.0667/kWh.展开更多
<span style="font-family:Verdana;">The increase of energy production is very important nowadays. It is necessary to improve the performance and efficiency of heat production facilities. The objective i...<span style="font-family:Verdana;">The increase of energy production is very important nowadays. It is necessary to improve the performance and efficiency of heat production facilities. The objective is to reduce pollutant emissions and regulate investment costs. One </span><span style="font-family:Verdana;">of the </span><span style="font-family:Verdana;">solution</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> is to control fuel and electricity consumption. </span><span style="font-family:Verdana;">This article develops a new model of simulation heat diffusion on the recovery system of condensing boiler. The method is based on the first and second thermodynamic systems. The Numerical discrete Model (NDM) was applied using MATLAB to simulate different characteristics of heat transfer in the recovery system. The result shows that the recovery unit can absorb the following temperatures;the range from 88°C to 90.7°C when the length of the tube is between respectively 110 and 111 m. the energy efficiency was between 0.55 and 0.57 which allowed confirming the model. This new model has some advantages such as;the use of an instantaneous calculation time. The heat recovered by the water tank can also serve as preheating different systems. One part of the heat recovered will be accumulated to be used as domestic hot water.</span>展开更多
Oil products are processed and refined from refineries and transported to oil storage tanks in oil depots, and oil products are transported from water and land transportation to end customers. The turnover and storage...Oil products are processed and refined from refineries and transported to oil storage tanks in oil depots, and oil products are transported from water and land transportation to end customers. The turnover and storage process often involves several operations such as reconciliation, tank dumping, loading and unloading, etc. In the process of oil transportation turnover and oil storage, the volume of gas phase space in the storage tank is affected by the changes of pressure, temperature and other factors. The physical characteristics of some oil components are higher than their boiling points, which leads to the evaporation loss of oil and gas. There are potential safety hazards in the whole storage process. When the concentration of oil vapor in a closed environment reaches a certain level, it is easy to cause fire and explosion, which not only pollutes the ecological environment, but also wastes energy. Evaporation of oil products not only causes the natural loss of a large number of existing oil resources, but also causes the density of oil products to change and the quality of oil products to decline. These problems have already attracted the attention of oil companies, and relevant laws, regulations, norms and standards have been formulated from the aspects of environmental protection, industry technology, safety management and resource recovery, and oil and gas recovery facilities of oil loading system have been set up. At the same time, in order to effectively control the evaporation of oil products and reduce the research results of air pollution, many different types of oil and gas recovery facilities have been applied in oil depots. It can ensure that the discharge of the treatment medium completely meets the treatment efficiency and tail gas emission concentration limit stipulated by the national laws and regulations, and complete the treatment of oil and gas pollution and the recycling of harmful substances. The reasonable selection scheme of oil and gas recovery facilities is economically applicable to the safe production and operation of the product oil depot, and the corresponding conclusions and suggestions are given.展开更多
Given that a large amount of crude oil remains on the surface of rocks and is difficult to produce after conventional waterflooding,a new superwetting oil displacement system incorporating the synergy between a hydrox...Given that a large amount of crude oil remains on the surface of rocks and is difficult to produce after conventional waterflooding,a new superwetting oil displacement system incorporating the synergy between a hydroxyl anion compound(1OH-1C)and an extended surfactant(S-C_(13)PO_(13)S)was designed.The interfacial tension,contact angle and emulsification performance of the system were measured.The oil displacement effects and improved oil recovery(IOR)mechanisms of 1OH-1C,S-C_(13)PO_(13)S and their compound system were investigated by microscopic visualization oil displacement experiments and core displacement experiments.The results show that 1OH-1C creates a superwetting interface and electrostatic separation pressure on the solid surface,which destroys the strong interactions between crude oil and quartz to peel off the oil film.S-C_(13)PO_(13)S has low interfacial tension,which can promote the flow of remaining oil and emulsify it into oil-in-water emulsions.The compound system of 1OH-1C and S-C_(13)PO_(13)S has both superwettability and low IFT,which can effectively improve oil recovery through a synergistic effect.The oil displacement experiment of low-permeability natural core shows that the compound solution can increase the oil recovery by 16.4 percentage points after waterflooding.This new high-efficiency system is promising for greatly improving oil recovery in low-permeability reservoirs.展开更多
In deep oil reservoir development,enhanced oil recovery(EOR)techniques encounter significant challenges under high-temperature and high-salinity conditions.Traditional profile-control agents often fail to maintain sta...In deep oil reservoir development,enhanced oil recovery(EOR)techniques encounter significant challenges under high-temperature and high-salinity conditions.Traditional profile-control agents often fail to maintain stable blocking under extreme conditions and exhibit poor resistance to high temperature and high salinity.This study develops a functionalized nanographite system(the MEGO system)with superior high-temperature dispersibility and thermosalinity-responsive capability through polyether amine(PEA)grafting and noncovalent interactions with disodium naphthalene sulfonate(DNS)molecules.The grafted PEA and DNS provide steric hindrance and electrostatic repulsion,enhancing thermal and salinity resistance.After ten days of aggregation,the MEGO system forms stable particle aggregates(55.51-61.80 lm)that are suitable for deep reservoir migration and profile control.Both experiments and simulations reveal that particle size variations are synergistically controlled by temperature and salt ions(Na^(+),Ca^(2+),and Mg^(2+)).Compared with monovalent ions,divalent ions promote nanographite aggregation more strongly through double-layer compression and bridging effects.In core displacement experiments,the MEGO system demonstrated superior performance in reservoirs with permeabilities ranging from 21.6 to 103 mD.The aggregates formed within the pore throats significantly enhanced flow resistance,expanded the sweep volume,and increased the overall oil recovery to 56.01%.This research indicates that the MEGO system holds excellent potential for EOR in deep oil reservoirs.展开更多
BACKGROUND The clinical necessity of routine abdominal drainage following radical gastrectomy remains controversial,particularly under the enhanced recovery after surgery(ERAS)protocol.ERAS advocates a multimodal peri...BACKGROUND The clinical necessity of routine abdominal drainage following radical gastrectomy remains controversial,particularly under the enhanced recovery after surgery(ERAS)protocol.ERAS advocates a multimodal perioperative strategy designed to attenuate surgical stress and optimize postoperative convalescence.AIM To evaluate the necessity of abdominal drainage tube placement following radical gastrectomy in the context of ERAS protocols.METHODS A systematic review and meta-analysis were conducted by searching PubMed,EMBASE,Cochrane Library,Web of Science,China National Knowledge Infrastructure,Wanfang,VIP Information,and SinoMed databases for randomized controlled trials comparing outcomes of abdominal drainage vs no drainage after gastrectomy under ERAS protocols.Primary outcomes included time to gastrointestinal function recovery,drainage tube removal time,postoperative complication rates,and length of hospital stay.Review Manager 5.4 was used for statistical analysis,and heterogeneity was assessed using the I2 statistic.RESULTS A total of 21 randomized controlled trials involving 1652 patients were included.Compared with routine abdominal drainage,the ERAS group without drainage showed significantly faster gastrointestinal recovery[standardized mean difference=-1.30,95%confidence interval(CI):-1.66 to-0.94,P<0.00001]and shorter hospital stay(standardized mean difference=-1.37,95%CI:-1.86 to-0.88,P<0.00001).The incidence of total postoperative complications was also significantly lower(odds ratio=0.53,95%CI:0.40-0.70,P<0.00001),particularly for anastomotic leakage and pulmonary infection.No significant differences were observed in surgical site infections or urinary tract infections.Sensitivity and subgroup analyses indicated stability of results,although some heterogeneity was noted.CONCLUSION Avoiding routine abdominal drainage under ERAS could lead to faster recovery,reduced complications,and shorter hospital stay following radical gastrectomy,supporting the selective use of drainage rather than routine.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 52071097)Hainan Provincial Natural Science Foundation of China (Grant No. 522MS162)Research Fund from Science and Technology on Underwater Vehicle Technology Laboratory (Grant No. 2021JCJQ-SYSJJ-LB06910)。
文摘Path planning for recovery is studied on the engineering background of double unmanned surface vehicles(USVs)towing oil booms for oil spill recovery.Given the influence of obstacles on the sea,the improved artificial potential field(APF)method is used for path planning.For addressing the two problems of unreachable target and local minimum in the APF,three improved algorithms are proposed by combining the motion performance constraints of the double USV system.These algorithms are then combined as the final APF-123 algorithm for oil spill recovery.Multiple sets of simulation tests are designed according to the flaws of the APF and the process of oil spill recovery.Results show that the proposed algorithms can ensure the system’s safety in tracking oil spills in a complex environment,and the speed is increased by more than 40%compared with the APF method.
基金This work was financially supported by the Innovation Fund from Chinese Academy of Sciences(Grant No.CXJJ-17-M130)the Research Fund of the State Key Laboratory of Robotics(Gant No.Y91Z0904).
文摘National navies equip their submarines with Autonomous Underwater Vehicle(AUV)technology.It has become an important component of submarine development in technologically-advanced countries.Employing advanced and reliable recovery systems directly improves the safety and operational efficiency of submarines equipped with AUVs.In this paper,based on aerial refueling technology,a cone-shaped recovery system with two different guiding covers(closed structure and frame structure)is applied to the submarine.By taking the Suboff model as the research object,STAR-CCM was used to study the influence of the installation position of the recovery system,and the length of the rigid rod,on the Suboff model.It was found that when the recovery system is installed in the middle and rear of the Suboff model at the same velocity and the same length of the rigid rod,the Suboff model has the good stability and less drag.It experiences the largest drag when being installed in the front of the rigid rod.Moreover,when the recovery system is installed in the front and middle of the rigid rod,the drag increases as its length increases,and the lift decreases as its length increases.Compared with the closed structure guiding cover,the Suboff model will have less drag and better stability when the recovery system uses the frame structure guiding cover.Besides,the deflection and vibration of the rigid rod were also analyzed via mathematical theory.
文摘A qualification test for the reliability of a newly-developed Diver Gas Recovery System (DGRS) was carried out in the Naval Medical Research Institute of the People's Liberation Army, China from March 29 to April 2, 1995. A sequential test plan of high discrimination ratio for the mean time between failures (MTBF) was adopted. The test procedures simulated those of a 300 msw dive. A hyperbaric breathing machine was used for the simulation of diver's respiratory functions. Parameters, such as diving depth, respiratory minute volume (RMV), CO2 production, gas flow rate, partial pressure of carbon dioxide, and ambient temperature and himidity were all displayed and recorded with a microcomputer system. The results indicated that no failure occurred during the 91.5 h operation. According to the acceptance and rejection criteria specified in the statistical test plan, a no-failure score in the 88 h operation is acceptable. Therefore, the DGRS has been demonstrated to meet the requirements of MTBF specified in the contract.
文摘The common problem of cold strip continuous annealing furnaces is high exhaust gas temperature and great energy consumption. Taking the cold-strip continuous annealing furnaces of Baosteel No. 4 cold mill plant as an example, several waste heat recovery systems in the annealing furnaces are compared and their advantages and disadvantages are analyzed through different energy-saving technologies.
基金Supported by the 10th Five Year High-Tech Researchand Development Plan of China (2002AA1Z67101)
文摘Highly security-critical system should possess features of continuous service. We present a new Robust Disaster Recovery System Model （RDRSM）. Through strengthening the ability of safe communications, RDRSM guarantees the secure and reliable command on disaster recovery. Its self-supervision capability can monitor the integrality and security of disaster recovery system itself. By 2D and 3D rea-time visible platform provided by GIS, GPS and RS, the model makes the using, management and maintenance of disaster recovery system easier. RDRSM possesses predominant features of security, robustness and controllability. And it can be applied to highly security-critical environments such as E-government and bank. Conducted by RDRSM, an important E-government disaster recovery system has been constructed successfully. The feasibility of this model is verified by practice. We especially emphasize the significance of some components of the model, such as risk assessment, disaster recovery planning, system supervision and robust communication support.
文摘Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter.The cold fresh air of those remote areas can be as severe as40℃ and commonly needs to be heated to around+3℃.This extensive amount of heating is usually provided by employing large-size air heaters,fueled by diesel,propane,natural gas,or heavy oil,leading to high energy costs and large carbon footprints.At the same time,the thermal energy content of a diesel generator sets(gen-sets)exhaust is known to be one-third of the total heating value of its combusted fuel.Exhaust heat recovery from diesel gen-sets is a growing technology that seeks to mitigate the energy costs by capturing and redirecting this commonly rejected exhaust heat to other applications such as space heating or pre-heating of the mine intake air.The present study investigated the possibility of employing a simple system based on off-theshelf heat exchanger technology,which can recover the waste heat from the exhaust of the power generation units(diesel gen-sets)in an off-grid,cold,remote mine in Canada for heating of the mine intake air.Data from a real mine was used for the analysis along with environmental data of three different location-scenarios with distinct climates.After developing a thermodynamic model,the heat savings were calculated,and an economic feasibility evaluation was performed.The proposed system was found highly viable with annual savings of up to C$6.7 million and capable enough to provide an average of around 75%of the heating demand for mine intake air,leading to a payback period of about eleven months or less for all scenarios.Deployment of seasonal thermal energy storage has also been recommended to mitigate the mismatch between supply and demand,mainly in summertime,possibly allowing the system to eliminate fuel costs for intake air heating.
基金Project(2013BAF07B02)supported by National Science and Technology Support Program of China
文摘After analyzing the working condition of the conventional diesel forklift,an energy recovery system in hybrid forklift is considered and its simulation model is built.Then,the control strategy for the proposed energy recovery system is discussed,which is validated and evaluated by simulation.The simulation results show that the proposed control strategy can achieve balance of the power and keep the state of charge(SOC) of ultra capacitor in a reasonable range,and the fuel consumption can be reduced by about 20.8% compared with the conventional diesel forklift.Finally,the feasibility of the simulation results is experimentally verified based on the lifting energy recovery system.
基金This research was supported by the MSIT(Ministry of Science and ICT),Korea,under the ITRC(Information Technology Research Center)support program(IITP-2020-2015-0-00403)supervised by the IITP(Institute for Information&communications Technology Planning&Evaluation)This research was supported by the Soonchunhyang University Research Fund.
文摘In today’s fourth industrial revolution,various blockchain technologies are being actively researched.A blockchain is a peer-to-peer data-sharing structure lacking central control.If a user wishes to access stored data,she/he must employ a private key to prove ownership of the data and create a transaction.If the private key is lost,blockchain data cannot be accessed.To solve such a problem,public blockchain users can recover the key using a wallet program.However,key recovery in a permissioned blockchain(PBC)has been but little studied.The PBC server is Honest-but-Curious(HBC),and should not be able to learn anything of the user;the server should simply recover and store the key.The server must also be resistant to malicious attacks.Therefore,key recovery in a PBC must satisfy various security requirements.Here,we present a password-protected secret sharing(PPSS)key recovery system,protected by a secure password from a malicious key storage server of a PBC.We describe existing key recovery schemes and our PPSS scheme.
基金Project(2009Gk2009)supported by the Science and Technology Department Funds of Hunan Province,ChinaProject(12C0379)supported by the Scientific Research Fund of Hunan Province,ChinaProject(13QDZ04)supported by the Scientific Research Foundation for Doctors of Xiang Tan University,China
文摘Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rankine cycle was constructed and the dynamic behavior was presented. In the dynamic test, the pump was stopped and then started. In addition, there was a step change of the flue gas volume flow rate and the converter frequency of multistage pump, respectively. The results indicate that the working fluid flow rate has the shortest response time, followed by the expander inlet pressure and the expander inlet temperature.The operation frequency of pump is a key parameter for the ORC system. Due to a step change of pump frequency(39.49-35.24 Hz),the expander efficiency and thermal efficiency drop by 16% and 21% within 2 min, respectively. Besides, the saturated mixture can lead to an increase of the expander rotation speed.
文摘In this paper, the underwater vehicle, sling and the mother ship are considered as a single degree of freedom system connected by a spring. Through the analysis of this system, a physical model is established, which describes the motion of the vehicle caused by the ship motion and wave motion. Furthermore, a mathematical model based on this physical model is obtained, and a numerical solution program is made. As an example, a practical launch and recovery system fbr an underwater robot is calculated by use of the program, and the motion track of the robot is obtained.
文摘Concentrating Solar Power(CSP)plants offer a promising way to generate low-emission energy.However,these plants face challenges such as reduced sunlight during winter and cloudy days,despite being located in high solar radiation areas.Furthermore,their dispatch capacities and yields can be affected by high electricity consumption,particularly at night.The present work aims to develop an off-design model that evaluates the hourly and annual performances of a parabolic trough power plant(PTPP)equipped with a waste heat recovery system.The study aims to compare the performances of this new layout with those of the conventional Andasol 1 plant,with the aim of assessing the improvements achieved in the new design.Based on the results,it can be concluded that the new layout has increased the annual generated power to almost 183 GWh(an increase of about 7.60% is achieved compared to the Andasol 1 layout that generates 169 GWh annually).Additionally,the proposed installation has achieved an efficiency of 20.55%,which represents a 7.87% increase compared to the previous design(19.05%).The Levelized Cost of Electricity(LCOE)of the new layout has been reduced by more than 5.8% compared to the Andasol 1 plant.Specifically,it has decreased from 13.11 to 12.35 c/kWh.This reduction in LCOE highlights the improved cost-effectiveness of the newlayout,making it amore economically viable option for generating electricity compared to the conventional Andasol 1 plant.
基金National Natural Science Foundation of China ( No. 50976046)
文摘Almost the same quantity to net output work of energy has been carried out and wasted by exhaust gas in typical automotive engine. Recovering the energy from exhaust gas and converting to mechanical energy will dramatically increase the heat efficiency and decrease the fuel consumption. With the increasing demand of fuel conservation, exhaust gas energy recovery technologies have been a hot topic. At present, many researches have been focused on heating or cooling the cab, mechanical energy using and thermo-electronic converting. Unfortunately, the complicated transmission of mechanical energy using and the depressed efficiency of thermo-electronic converting restrict their widely applying. In this paper, a kind of exhaust gas energy recovery system of pneumatic driving automotive engine, in which highly compressed air acts as energy storing and converting carrier, has been established. Pneumatic driving motor can produce moderate speed and high torque output, which is compatible for engine using. The feasibility has been certificated by GT-Power simulation and laboratory testes. The technologies about increasing recovery efficiency have been discussed in detail. The results demonstrated that the in parallel exhaust gas energy recovery system, which is similar to the compound turbo-charger structure can recovery 8 to 10 percent of rated power output. At last, a comprehensive system, which includes Rankine cycle based power wheel cycle unit etc., has been introduced.
文摘With the emphasis on energy and environmental protection,energy-conservation and emission-reduction become vital issues for industrial development.Moreover,with the development of legislation on marine environment,the marine diesel engine has become focusing on energy saving and emission reduction for ships.For low-speed diesel engines under high load,waste heat from exhaust gas can be recovered by the compact and efficient gas turbine.In this paper,the matching design research between low speed diesel engine and gas turbine is carried out.To balance efficiency and compactness,the impeller was adjusted and generated by ANSYS BLADEGEN,based on 1D thermodynamic design.And the 1D calculation is similar to the ANSYS CFX simulation result:the total-static efficiency is 73.8%compared to 76.7%.Moreover,the flow separation happened at the impeller suction side and created vortex due to the high incidence angle.The off-design operating point simulation of the turbine shows though the pressure ratio increase will cause the efficiency to decline a little,the total shaft power rises.In sum,this paper worked out a power turbine suitable for a low-speed diesel engine according to the turbine character matching design and simulation,which provides foundation to the construction of a steady operation of waste heat recovery system for marine diesel engine.
文摘This paper presents the control algorithm for supercapacitor based kinetic energy recovery system. Supercapacitor shares energy with the motor drive DC link through bidirectional non-isolated converter. Two cascaded linear regulators control feedback linearized states of the system. As a result, the DC link voltage is stabilized and the supercapacitor voltage and current are limited. Control algorithm does not increase ripple of voltages and currents, and thus life time expectancy of supercapacitor is prolonged. In torque-controlled motor drives, current on DC side can rapidly change with bandwidth as high as 2 kHz. Based on measurements of KERS states, the algorithm estimates rapidly changing motor drive current on DC side and stabilizes the DC link voltage with overshoot less than 2%. Controller is independent from the motor drive parameters and relies only on its own measurements. This enables kinetic energy recovery system （KERS） to be a standalone device.
文摘Steam is the typical working fluid to drive turbo-generators in coal-fired power plants. It is an effective working fluid, but some of its energy is extracted in an unusable form when condensed. A Power Recovery Cycle (PRC) using a more volatile Secondary Working Fluid (SWF) added to the steam cycle could improve energy efficiency. PRCs have been applied to the flue gas and for combined cycle systems but not to traditional plant steam cycles. This paper details an analysis of adding a steam cycle PRC to a 500 MW lignite coal-fired power plant. A validated model of the plant was developed and PRCs using the three most attractive SWFs, benzene, methanol and hydrazine, were then added to the model. Adding a benzene, methanol, or hydrazine steam cycle PRC will produce an additional 59, 34, and 49 MW, respectively. An AACE Class 4 factored broad capital cost estimate and comparable operating costs and revenue estimates were developed to evaluate PRC feasibility. The benzene, methanol, and hydrazine processes had 2019 Net Present Values (NPVs) @12% of -$32, -$59, and +$35 million ± 40%, respectively. Thus, a PRC may be profitable at current or modest increases to U.S. Upper Midwest electricity prices of around $0.0667/kWh.
文摘<span style="font-family:Verdana;">The increase of energy production is very important nowadays. It is necessary to improve the performance and efficiency of heat production facilities. The objective is to reduce pollutant emissions and regulate investment costs. One </span><span style="font-family:Verdana;">of the </span><span style="font-family:Verdana;">solution</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> is to control fuel and electricity consumption. </span><span style="font-family:Verdana;">This article develops a new model of simulation heat diffusion on the recovery system of condensing boiler. The method is based on the first and second thermodynamic systems. The Numerical discrete Model (NDM) was applied using MATLAB to simulate different characteristics of heat transfer in the recovery system. The result shows that the recovery unit can absorb the following temperatures;the range from 88°C to 90.7°C when the length of the tube is between respectively 110 and 111 m. the energy efficiency was between 0.55 and 0.57 which allowed confirming the model. This new model has some advantages such as;the use of an instantaneous calculation time. The heat recovered by the water tank can also serve as preheating different systems. One part of the heat recovered will be accumulated to be used as domestic hot water.</span>
文摘Oil products are processed and refined from refineries and transported to oil storage tanks in oil depots, and oil products are transported from water and land transportation to end customers. The turnover and storage process often involves several operations such as reconciliation, tank dumping, loading and unloading, etc. In the process of oil transportation turnover and oil storage, the volume of gas phase space in the storage tank is affected by the changes of pressure, temperature and other factors. The physical characteristics of some oil components are higher than their boiling points, which leads to the evaporation loss of oil and gas. There are potential safety hazards in the whole storage process. When the concentration of oil vapor in a closed environment reaches a certain level, it is easy to cause fire and explosion, which not only pollutes the ecological environment, but also wastes energy. Evaporation of oil products not only causes the natural loss of a large number of existing oil resources, but also causes the density of oil products to change and the quality of oil products to decline. These problems have already attracted the attention of oil companies, and relevant laws, regulations, norms and standards have been formulated from the aspects of environmental protection, industry technology, safety management and resource recovery, and oil and gas recovery facilities of oil loading system have been set up. At the same time, in order to effectively control the evaporation of oil products and reduce the research results of air pollution, many different types of oil and gas recovery facilities have been applied in oil depots. It can ensure that the discharge of the treatment medium completely meets the treatment efficiency and tail gas emission concentration limit stipulated by the national laws and regulations, and complete the treatment of oil and gas pollution and the recycling of harmful substances. The reasonable selection scheme of oil and gas recovery facilities is economically applicable to the safe production and operation of the product oil depot, and the corresponding conclusions and suggestions are given.
基金Supported by the National Key R&D Program of China(2019YFA0708700,2023YFF0614100)CNPC Major Science and Technology Project(2021ZZ01,2023ZZ04).
文摘Given that a large amount of crude oil remains on the surface of rocks and is difficult to produce after conventional waterflooding,a new superwetting oil displacement system incorporating the synergy between a hydroxyl anion compound(1OH-1C)and an extended surfactant(S-C_(13)PO_(13)S)was designed.The interfacial tension,contact angle and emulsification performance of the system were measured.The oil displacement effects and improved oil recovery(IOR)mechanisms of 1OH-1C,S-C_(13)PO_(13)S and their compound system were investigated by microscopic visualization oil displacement experiments and core displacement experiments.The results show that 1OH-1C creates a superwetting interface and electrostatic separation pressure on the solid surface,which destroys the strong interactions between crude oil and quartz to peel off the oil film.S-C_(13)PO_(13)S has low interfacial tension,which can promote the flow of remaining oil and emulsify it into oil-in-water emulsions.The compound system of 1OH-1C and S-C_(13)PO_(13)S has both superwettability and low IFT,which can effectively improve oil recovery through a synergistic effect.The oil displacement experiment of low-permeability natural core shows that the compound solution can increase the oil recovery by 16.4 percentage points after waterflooding.This new high-efficiency system is promising for greatly improving oil recovery in low-permeability reservoirs.
基金supported by the General Program of the National Natural Science Foundation of China(52074335)the National Key Research and Development Program of China(2022YFE0129900 and 2019YFA0708700)+1 种基金the Fundamental Research Funds for the Central Universities(23CX07003A)the Special Funding Program for the Operational Expenses of National Research Institutions(SKLDOG2024-ZYRC-01).
文摘In deep oil reservoir development,enhanced oil recovery(EOR)techniques encounter significant challenges under high-temperature and high-salinity conditions.Traditional profile-control agents often fail to maintain stable blocking under extreme conditions and exhibit poor resistance to high temperature and high salinity.This study develops a functionalized nanographite system(the MEGO system)with superior high-temperature dispersibility and thermosalinity-responsive capability through polyether amine(PEA)grafting and noncovalent interactions with disodium naphthalene sulfonate(DNS)molecules.The grafted PEA and DNS provide steric hindrance and electrostatic repulsion,enhancing thermal and salinity resistance.After ten days of aggregation,the MEGO system forms stable particle aggregates(55.51-61.80 lm)that are suitable for deep reservoir migration and profile control.Both experiments and simulations reveal that particle size variations are synergistically controlled by temperature and salt ions(Na^(+),Ca^(2+),and Mg^(2+)).Compared with monovalent ions,divalent ions promote nanographite aggregation more strongly through double-layer compression and bridging effects.In core displacement experiments,the MEGO system demonstrated superior performance in reservoirs with permeabilities ranging from 21.6 to 103 mD.The aggregates formed within the pore throats significantly enhanced flow resistance,expanded the sweep volume,and increased the overall oil recovery to 56.01%.This research indicates that the MEGO system holds excellent potential for EOR in deep oil reservoirs.
文摘BACKGROUND The clinical necessity of routine abdominal drainage following radical gastrectomy remains controversial,particularly under the enhanced recovery after surgery(ERAS)protocol.ERAS advocates a multimodal perioperative strategy designed to attenuate surgical stress and optimize postoperative convalescence.AIM To evaluate the necessity of abdominal drainage tube placement following radical gastrectomy in the context of ERAS protocols.METHODS A systematic review and meta-analysis were conducted by searching PubMed,EMBASE,Cochrane Library,Web of Science,China National Knowledge Infrastructure,Wanfang,VIP Information,and SinoMed databases for randomized controlled trials comparing outcomes of abdominal drainage vs no drainage after gastrectomy under ERAS protocols.Primary outcomes included time to gastrointestinal function recovery,drainage tube removal time,postoperative complication rates,and length of hospital stay.Review Manager 5.4 was used for statistical analysis,and heterogeneity was assessed using the I2 statistic.RESULTS A total of 21 randomized controlled trials involving 1652 patients were included.Compared with routine abdominal drainage,the ERAS group without drainage showed significantly faster gastrointestinal recovery[standardized mean difference=-1.30,95%confidence interval(CI):-1.66 to-0.94,P<0.00001]and shorter hospital stay(standardized mean difference=-1.37,95%CI:-1.86 to-0.88,P<0.00001).The incidence of total postoperative complications was also significantly lower(odds ratio=0.53,95%CI:0.40-0.70,P<0.00001),particularly for anastomotic leakage and pulmonary infection.No significant differences were observed in surgical site infections or urinary tract infections.Sensitivity and subgroup analyses indicated stability of results,although some heterogeneity was noted.CONCLUSION Avoiding routine abdominal drainage under ERAS could lead to faster recovery,reduced complications,and shorter hospital stay following radical gastrectomy,supporting the selective use of drainage rather than routine.
