In order to address the issues of narrow seeding adjustment range and low accuracy of grain placement in the existing rice seeders,a mechanically and pneumatically adjustable precision hole-type seeder is designed.It ...In order to address the issues of narrow seeding adjustment range and low accuracy of grain placement in the existing rice seeders,a mechanically and pneumatically adjustable precision hole-type seeder is designed.It is primarily composed of a seeding disk,air chamber,seed box,and seed discharge device.The design incorporates a symmetrical structure with dual disks and dual casings,enabling both single-sided and double-sided single-row and synchronized seeding.Based on theoretical analysis of seed charging,seed protection,and seed release,the following parameters were determined:seeding disk diameter of 192 mm,suction hole diameter of 1.48-1.52 mm,suction hole spacing of 3.04-9.41 mm,type hole distribution circle radius of about 62.1-77.0 mm,type hole diameter of 9 mm,stirrer plate length of 4.705-9.410 mm,and stirrer plate inclination angle of 0°-30°.Using a coupled simulation method of EDEM-Fluent,the impact of different type hole distributions,stirrer plate lengths,and inclination angles on seeding performance was analyzed.The results indicate that the main and secondary influencing factors on seed charging qualification rate are type hole diameter,stirrer plate inclination angle,and stirrer plate length.The optimal performance is achieved with a type hole diameter of 6 mm,stirrer plate length of 5 mm,and stirrer plate inclination angle of 10°,resulting in a seed charging qualification rate of 71.42%.Furthermore,Fluent software was utilized to analyze the influence of different suction hole spacings,diameters,and air chamber radii on seeding performance.The results revealed that the suction of rice seeds by the hole can be better realized with a suction hole spacing of 6 mm,a suction hole diameter of 1.5 mm,and an air chamber radius of 62 mm,at which the average negative pressure in the suction hole center was about 2824.56 Pa.A bench test and a field test were further performed on the device.The results showed that increasing the number of type holes and suction holes can contribute to more stable regulation of the seeding amount.The optimal single-sided seed metering could achieve a maximum qualified rate of 82.5%,a missing rate of 12.5%,and a repeating rate of 5%;while the optimal double-sided seed metering could obtain a maximum qualified rate,missing rate,and repeating rate of 72.5%,15%,and 12.5%,respectively.This adjustable precision seeder can meet the requirements of precision sowing of Huanghuazhan rice varieties,and the research findings can provide reference for the structural optimization of precision rice seeders.展开更多
The growth and production of yeast in the industrial fermentation are seriously restrained by heat stress and exacerbated by heat induced oxidative stress.In this study,a novel synthetic biology approach was developed...The growth and production of yeast in the industrial fermentation are seriously restrained by heat stress and exacerbated by heat induced oxidative stress.In this study,a novel synthetic biology approach was developed to globally boost the viability and production ability of S.cerevisiae at high temperature through rationally designing and combing heat shock protein(HSP)and superoxide dismutase(SOD)genetic devices to ultimately synergistically alleviate both heat stress and oxidative stress.HSP and SOD from extremophiles were constructed to be different genetic devices and they were preliminary screened by heat resistant experiments and anti-oxidative experiments,respectively.Then in order to customize and further improve thermotolerance of S.cerevisiae,the HSP genetic device and SOD genetic device were rationally combined.The results show the simply assemble of the same function genetic devices to solve heat stress or oxidative stress could not enhance the thermotolerance considerably.Only S.cerevisiae with the combination genetic device(FBA1p-sod-MB4-FBA1p-shsp-HB8)solving both stress showed 250%better thermotolerance than the control and displayed further 55%enhanced cell density compared with the strains with single FBA1p-sod-MB4 or FBA1p-shsp-HB8 at 42C.Then the most excellent combination genetic device was introduced into lab S.cerevisiae and industrial S.cerevisiae for ethanol fermentation.The ethanol yields of the two strains were increased by 20.6%and 26.3%compared with the control under high temperature,respectively.These results indicate synergistically defensing both heat stress and oxidative stress is absolutely necessary to enhance the thermotolerance and production of S.cerevisiae.展开更多
For intermediate water depths(typically ranging from 50 m to 80 m),designing steel catenary mooring systems for floating marine renewable energy(FMRE)platforms can be challenging due to the limited weight of suspended...For intermediate water depths(typically ranging from 50 m to 80 m),designing steel catenary mooring systems for floating marine renewable energy(FMRE)platforms can be challenging due to the limited weight of suspended mooring lines.This can substantially increase mooring line tensions following large platform offsets.In contrast,mooring systems using synthetic fibre ropes offer the potential to prevent large platform offsets while reducing peak mooring line tensions.In this study,novel semi-taut moor-ing systems incorporating polyester ropes and steel chains are proposed for a combined wind and wave energy system-the semi-submersible flap torus combination(STFC)concept,deployed at a 50 m wa-ter depth.The STFC integrates a semi-submersible floating offshore wind turbine(FOWT),a torus wave energy converter(WEC)and three flap-type WECs.The dynamic responses of the STFC with different semi-taut mooring configurations under operational and survival environmental conditions are assessed in terms of key performance parameters such as the platform’s motion responses and mooring line ten-sions.These performance parameters are compared against those of a chain-catenary mooring system.With the use of semi-taut mooring systems,significantly smaller mooring footprints as compared to the chain-catenary mooring systems can be achieved.Moreover,it is demonstrated that the semi-taut moor-ing systems are effective in reducing the maximum tension of the mooring lines.A basic cost analysis further indicates that semi-taut mooring systems offer substantial cost advantages over chain-catenary moorings in intermediate water depths.展开更多
A detailed model of thermally-driven combined thermoelectric(TE) heating device is established. The device consists of twostage TE heat pump(TTEH) and two-stage TE generator(TTEG) with four external heat exchangers(HE...A detailed model of thermally-driven combined thermoelectric(TE) heating device is established. The device consists of twostage TE heat pump(TTEH) and two-stage TE generator(TTEG) with four external heat exchangers(HEXs). Both internal losses and external heat transfer irreversibilities are considered in the model. The heating capacity and the coefficient of performance(COP) of the device are improved through numerical optimization,which is of great significance to the application of the device. The distribution of the total TE element number among four TE devices and the distribution of the total external heat conductance among the four external HEXs are optimized. The results show that both the reservoir temperatures of TTEG and TTEH have significant influences on the performance and the corresponding optimum parameters of the device. The COP can reach 0.14 after optimization when the temperature difference of heat source is 150 K and the temperature difference of heating is 10 K.展开更多
A thermodynamic model of a thermoelectric generator(TEG)-driven thermoelectric cooler(TEC) device considering Thomson effect and external heat transfer(HT) is established based on the combination of non-equilibrium an...A thermodynamic model of a thermoelectric generator(TEG)-driven thermoelectric cooler(TEC) device considering Thomson effect and external heat transfer(HT) is established based on the combination of non-equilibrium and finite time thermodynamic theories. The expressions of cooling capacity and coefficient of performance(COP) are obtained. Performances are compared with and without considering Thomson effect using numerical optimization method. The influences of Thomson effect on the optimal performances, optimum allocations of thermoelectric(TE) element number and HT surface area are discussed. The results indicate that Thomson effect decreases the maximum cooling capacity and COP. More TE elements should be allocated to TEG, and more HT area should be allocated to the heat exchanger(HEX) of TEG, the hot-side HEX of TEG and the cold-side HEX of TEC in the design of the device considering Thomson effect. The results obtained can be used to help design TEG-TEC devices.展开更多
Based on the non-equilibrium thermodynamics and energy and exergy analyses,a thermodynamic model of two-stage thermoelectric(TE)cooler(TTEC)driven by two-stage TE generator(TTEG)(TTEG-TTEC)combined TE device is establ...Based on the non-equilibrium thermodynamics and energy and exergy analyses,a thermodynamic model of two-stage thermoelectric(TE)cooler(TTEC)driven by two-stage TE generator(TTEG)(TTEG-TTEC)combined TE device is established with involving Thomson effect by fitting method of variable physical parameters of TE materials.Taking total number of TE elements as constraint,influences of number distributions of TE elements on three device performance indictors,that is,cooling load,maximum COP and maximum exergetic efficiency,are analyzed.Three number distributions of TE elements are optimized with three maximum performance indictors as the objectives,respectively.Influences of hot-junction temperature of TTEG and coldjunction temperature of TTEC on optimization results are analyzed,and difference between optimization results corresponding to three performance indicators are studied.Optimal performance intervals and optimal variable intervals are provided.Influences of Thomson effect on three general performance indicators,three optimal performance indicators and optimal variables are comparatively discussed.Thomson effect reduces three general performance indicators and three optimal performance indicators of device.When hot-and cold-junction temperatures of TTEG and TTEC are 450,305,325 and 295 K,respectively,Thomson effect reduced maximum cooling load,maximum COP and maximum exergetic efficiency from 9.528 W,9.043×10^(-2)and2.552%to 6.651 W,6.286×10^(-2)and 1.752%,respectively.展开更多
基金supported by the Outstanding Young and Middle-aged Science and Technology Innovation Team Program of Colleges and Universities of Hubei Province(Grant No.T201934)the Development and Application of Rice and Camellia Fruit Mechanized Short Board Machine(Grant No.HBSNYT202208).
文摘In order to address the issues of narrow seeding adjustment range and low accuracy of grain placement in the existing rice seeders,a mechanically and pneumatically adjustable precision hole-type seeder is designed.It is primarily composed of a seeding disk,air chamber,seed box,and seed discharge device.The design incorporates a symmetrical structure with dual disks and dual casings,enabling both single-sided and double-sided single-row and synchronized seeding.Based on theoretical analysis of seed charging,seed protection,and seed release,the following parameters were determined:seeding disk diameter of 192 mm,suction hole diameter of 1.48-1.52 mm,suction hole spacing of 3.04-9.41 mm,type hole distribution circle radius of about 62.1-77.0 mm,type hole diameter of 9 mm,stirrer plate length of 4.705-9.410 mm,and stirrer plate inclination angle of 0°-30°.Using a coupled simulation method of EDEM-Fluent,the impact of different type hole distributions,stirrer plate lengths,and inclination angles on seeding performance was analyzed.The results indicate that the main and secondary influencing factors on seed charging qualification rate are type hole diameter,stirrer plate inclination angle,and stirrer plate length.The optimal performance is achieved with a type hole diameter of 6 mm,stirrer plate length of 5 mm,and stirrer plate inclination angle of 10°,resulting in a seed charging qualification rate of 71.42%.Furthermore,Fluent software was utilized to analyze the influence of different suction hole spacings,diameters,and air chamber radii on seeding performance.The results revealed that the suction of rice seeds by the hole can be better realized with a suction hole spacing of 6 mm,a suction hole diameter of 1.5 mm,and an air chamber radius of 62 mm,at which the average negative pressure in the suction hole center was about 2824.56 Pa.A bench test and a field test were further performed on the device.The results showed that increasing the number of type holes and suction holes can contribute to more stable regulation of the seeding amount.The optimal single-sided seed metering could achieve a maximum qualified rate of 82.5%,a missing rate of 12.5%,and a repeating rate of 5%;while the optimal double-sided seed metering could obtain a maximum qualified rate,missing rate,and repeating rate of 72.5%,15%,and 12.5%,respectively.This adjustable precision seeder can meet the requirements of precision sowing of Huanghuazhan rice varieties,and the research findings can provide reference for the structural optimization of precision rice seeders.
基金The authors acknowledge funding support from the National High Technology Research and Development Program of China(863 Program)(No.2012AA02A704)the Major State Basic Research Development Program of China(973 Program)(No.2013CB733900)the National Natural Science Foundation of China(No.21376028,No.21425624,No.21476026).
文摘The growth and production of yeast in the industrial fermentation are seriously restrained by heat stress and exacerbated by heat induced oxidative stress.In this study,a novel synthetic biology approach was developed to globally boost the viability and production ability of S.cerevisiae at high temperature through rationally designing and combing heat shock protein(HSP)and superoxide dismutase(SOD)genetic devices to ultimately synergistically alleviate both heat stress and oxidative stress.HSP and SOD from extremophiles were constructed to be different genetic devices and they were preliminary screened by heat resistant experiments and anti-oxidative experiments,respectively.Then in order to customize and further improve thermotolerance of S.cerevisiae,the HSP genetic device and SOD genetic device were rationally combined.The results show the simply assemble of the same function genetic devices to solve heat stress or oxidative stress could not enhance the thermotolerance considerably.Only S.cerevisiae with the combination genetic device(FBA1p-sod-MB4-FBA1p-shsp-HB8)solving both stress showed 250%better thermotolerance than the control and displayed further 55%enhanced cell density compared with the strains with single FBA1p-sod-MB4 or FBA1p-shsp-HB8 at 42C.Then the most excellent combination genetic device was introduced into lab S.cerevisiae and industrial S.cerevisiae for ethanol fermentation.The ethanol yields of the two strains were increased by 20.6%and 26.3%compared with the control under high temperature,respectively.These results indicate synergistically defensing both heat stress and oxidative stress is absolutely necessary to enhance the thermotolerance and production of S.cerevisiae.
文摘For intermediate water depths(typically ranging from 50 m to 80 m),designing steel catenary mooring systems for floating marine renewable energy(FMRE)platforms can be challenging due to the limited weight of suspended mooring lines.This can substantially increase mooring line tensions following large platform offsets.In contrast,mooring systems using synthetic fibre ropes offer the potential to prevent large platform offsets while reducing peak mooring line tensions.In this study,novel semi-taut moor-ing systems incorporating polyester ropes and steel chains are proposed for a combined wind and wave energy system-the semi-submersible flap torus combination(STFC)concept,deployed at a 50 m wa-ter depth.The STFC integrates a semi-submersible floating offshore wind turbine(FOWT),a torus wave energy converter(WEC)and three flap-type WECs.The dynamic responses of the STFC with different semi-taut mooring configurations under operational and survival environmental conditions are assessed in terms of key performance parameters such as the platform’s motion responses and mooring line ten-sions.These performance parameters are compared against those of a chain-catenary mooring system.With the use of semi-taut mooring systems,significantly smaller mooring footprints as compared to the chain-catenary mooring systems can be achieved.Moreover,it is demonstrated that the semi-taut moor-ing systems are effective in reducing the maximum tension of the mooring lines.A basic cost analysis further indicates that semi-taut mooring systems offer substantial cost advantages over chain-catenary moorings in intermediate water depths.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.11974429 and 51576207)the Natural Science Foundation of Naval University of Engineering(Grant No.20161505)。
文摘A detailed model of thermally-driven combined thermoelectric(TE) heating device is established. The device consists of twostage TE heat pump(TTEH) and two-stage TE generator(TTEG) with four external heat exchangers(HEXs). Both internal losses and external heat transfer irreversibilities are considered in the model. The heating capacity and the coefficient of performance(COP) of the device are improved through numerical optimization,which is of great significance to the application of the device. The distribution of the total TE element number among four TE devices and the distribution of the total external heat conductance among the four external HEXs are optimized. The results show that both the reservoir temperatures of TTEG and TTEH have significant influences on the performance and the corresponding optimum parameters of the device. The COP can reach 0.14 after optimization when the temperature difference of heat source is 150 K and the temperature difference of heating is 10 K.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51576207, and 11305266)the Natural Science Foundation of Naval University of Engineering (Greant No. 20161505)
文摘A thermodynamic model of a thermoelectric generator(TEG)-driven thermoelectric cooler(TEC) device considering Thomson effect and external heat transfer(HT) is established based on the combination of non-equilibrium and finite time thermodynamic theories. The expressions of cooling capacity and coefficient of performance(COP) are obtained. Performances are compared with and without considering Thomson effect using numerical optimization method. The influences of Thomson effect on the optimal performances, optimum allocations of thermoelectric(TE) element number and HT surface area are discussed. The results indicate that Thomson effect decreases the maximum cooling capacity and COP. More TE elements should be allocated to TEG, and more HT area should be allocated to the heat exchanger(HEX) of TEG, the hot-side HEX of TEG and the cold-side HEX of TEC in the design of the device considering Thomson effect. The results obtained can be used to help design TEG-TEC devices.
基金supported by the National Natural Science Foundation of China(Grant No.52171317)。
文摘Based on the non-equilibrium thermodynamics and energy and exergy analyses,a thermodynamic model of two-stage thermoelectric(TE)cooler(TTEC)driven by two-stage TE generator(TTEG)(TTEG-TTEC)combined TE device is established with involving Thomson effect by fitting method of variable physical parameters of TE materials.Taking total number of TE elements as constraint,influences of number distributions of TE elements on three device performance indictors,that is,cooling load,maximum COP and maximum exergetic efficiency,are analyzed.Three number distributions of TE elements are optimized with three maximum performance indictors as the objectives,respectively.Influences of hot-junction temperature of TTEG and coldjunction temperature of TTEC on optimization results are analyzed,and difference between optimization results corresponding to three performance indicators are studied.Optimal performance intervals and optimal variable intervals are provided.Influences of Thomson effect on three general performance indicators,three optimal performance indicators and optimal variables are comparatively discussed.Thomson effect reduces three general performance indicators and three optimal performance indicators of device.When hot-and cold-junction temperatures of TTEG and TTEC are 450,305,325 and 295 K,respectively,Thomson effect reduced maximum cooling load,maximum COP and maximum exergetic efficiency from 9.528 W,9.043×10^(-2)and2.552%to 6.651 W,6.286×10^(-2)and 1.752%,respectively.
