The addition of silicon(Si)and organic fertilizers to soil conditioners can inhibit the transfer of heavy metal ions from soil to crops.However,it is not clear how Si and organic fertilizers affect soil properties and...The addition of silicon(Si)and organic fertilizers to soil conditioners can inhibit the transfer of heavy metal ions from soil to crops.However,it is not clear how Si and organic fertilizers affect soil properties and the micro-ecological environment and thereby reduce cadmium(Cd)accumulation in rice.In this study,the effects of L-type soil conditioners containing Si and organic fertilizers on bacterial and fungal community diversity,soil pH,organic matter,and available Si were analyzed with field experiments at two sites in Liuzhou City and Hezhou City,respectively,in Guangxi,China.With the increase of Si and organic fertilizer content in soil conditioner,rice yield respectively increased by 16.8–25.8 and 6.8–13.1%,and rice Cd content decreased significantly by 8.2–21.1 and 10.8–40.6%,respectively,at the two experimental sites.Soil microbiome analysis showed that the increase in abundance of Firmicutes and Actinobacteriota bacteria associated with Cd adsorption and sequestration,and Basidiomycota fungal populations associated with degradation of macromolecules favored the inhibition of soil Cd activity(soil exchangeable Cd decreased by 14.4–14.8 and 18.1–20.6%).This was associated with an increase in organic matter and Si content caused by applying soil conditioners.In conclusion,L-type soil conditioners,rich in Si and organic fertilizer,can reduce soil Cd bioavailability by regulating the dominant Cd passivating flora in the soil and ultimately reduce Cd accumulation in rice.展开更多
This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a u...This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.展开更多
Traditional air conditioner used to be in local control mode. However, with the development of modern information technology, the control of air conditioner will have to support many more functions. As a first step ...Traditional air conditioner used to be in local control mode. However, with the development of modern information technology, the control of air conditioner will have to support many more functions. As a first step in such a development, we have implemented a remote monitoring system of unitary air conditioners, using the manufacturing message specification (MMS). MMS is an OSI application protocol designed for the remote control and monitoring of real devices. The functions supported are those that an operator would do normally at the console of the unitary air conditioner. Due to the accomplishment of UMCS (Unitary air conditioner MMS Control System), there will be a leap of the application of MMS and the control technology of unitary air conditioner.展开更多
To investigate the effects of Tianshifu soil conditioners on rice growth and their control effects on Cd absorption and accumulation in rice, a test was carded out in the field typically polluted by Cd in Hunan Provin...To investigate the effects of Tianshifu soil conditioners on rice growth and their control effects on Cd absorption and accumulation in rice, a test was carded out in the field typically polluted by Cd in Hunan Province. The results showed that the Tianshifu soil conditioner, soil bacterial conditioner and the combination of Tian- shifu soil conditioner and soil bacterial conditioner all could promote rice growth, im- prove rice yield and reduce significantly Cd content in rice grains. In Beishan, the Cd contents in rice grains treated by Tianshifu soil conditioner, soil bacterial condi- tioner and the combination of Tianshifu soil conditioner and soil bacterial conditioner were reduced by 37.63% (P〈0.05), 32.59% (P〈0.05) and 27.95% (P〈0.05) respec- tively compared with that in rice grains treated by conventional fertilization; In Xiang- tan, the Cd contents in rice grains were reduced by 54.36% (P〈0.05), 50.19% (P〈 0.05) and 45.22% (P〈0.05) respectively. The rice grains harvested at the two test sites all met the national food safety standards. Considering the control effect on Cd contamination, Tianshifu soil conditioner 〉 combination of Tianshifu soil condi- tioner and soil bacterial conditioner 〉 Tianshifu soil bacterial conditioner. In addition to reducing Cd absorption in rice, as described in the lime application treatment, the application of Tianshifu soil conditioners also inhibited the transportation of Cd from rice straws to rice grains. The Tianshifu soil conditioner, soil bacterial conditioner and combination of Tianshifu soil conditioner and soil bacterial conditioner also effec- tively improved the soil acidity, increased the soil pH value and reduced soil avail- able Cd content to some extent.展开更多
A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of...A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of pneumatic valve the displacement is controlled by electronic control valve. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed according to the geometrical and kinematical information of the compressor. Using the model, the effect of relevant parameters on variable displace control is estimated. It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneumatic valves. And by using this new electronic control device, the optimum systemic control of AAC is available.展开更多
Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, mo...Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index (GI), were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.展开更多
A pot experiment was conducted to investigate the effects of various soil treatments on the growth of vetiver grass ( Vetiveria zizanioides (L.) Nash) with the objective of formulating appropriate soil media for use i...A pot experiment was conducted to investigate the effects of various soil treatments on the growth of vetiver grass ( Vetiveria zizanioides (L.) Nash) with the objective of formulating appropriate soil media for use in sulfide-bearing mined areas. An acidic mine site acid sulfate soil (pH 2.8) was treated with different soil conditioner formula including hydrated lime, red mud (bauxite residues), zeolitic rock powder, biosolids and a compound fertilizer. Soils treated with red mud and hydrated lime corrected soil acidity and reduced or eliminated metal toxicity enabling the establishment of vetiver grass.Although over-liming affected growth, some seedlings of vetiver survived the initial strong alkaline conditions. Addition of appropriate amounts of zeolitic rock powder also enhanced growth, but over-application caused detrimental effects. In this experiment, soil medium with the best growth performance of vetiver was 50 g of red mud, 10 g of lime, 30 g of zeolitic rock powder and 30 g of biosolids with 2000 g of mine soils (100% survival rate with the greatest biomass and number of new shoots), but adding a chemical fertilizer to this media adversely impacted plant growth. In addition, a high application rate of biosolids resulted in poorer growth of vetiver, compared to a moderate application rate.展开更多
In order to investigate how the aerodynamic drag and noise produced by the roof air conditioner of a high-speed train can be reduced,the related unsteady flow in the near-field was computed using the method of large e...In order to investigate how the aerodynamic drag and noise produced by the roof air conditioner of a high-speed train can be reduced,the related unsteady flow in the near-field was computed using the method of large eddy simulation.In this way,the aerodynamic source for noise generation has initially been determined.Then,the far-field aerodynamic noise has been computed in the framework of the Lighthill’s acoustics analogy theory.The propulsion height and flow-guide angle of the roof air conditioner were set as the design variables.According to the computational results,a lower propulsion height or flow-guide angle is beneficial in terms of aerodynamic drag and noise mitigation.However,compared to the design scheme with propulsion height of 0mm,the aerodynamic drag coefficient of the configuration with propulsion height of 190mm and flow-guide angle of 30°is slightly larger,while the aerodynamic noise is obviously reduced.Thus,from the viewpoint of the aerodynamic drag and noise,the design scheme with propulsion height of 190 mm and flow-guide angle of 30°is the optimal configuration in the range of conditions examined in the present work.展开更多
This experiment was conducted to investigate the effects of feed conditioners(single-layer, double-layer and retentionconditioner) on the growth performance, meat quality and intestinal morphology of pigs throughout t...This experiment was conducted to investigate the effects of feed conditioners(single-layer, double-layer and retentionconditioner) on the growth performance, meat quality and intestinal morphology of pigs throughout the growing to finishing phase. A total of 96 growing pigs((28.70±3.20) kg) were selected and randomized into three treatment groups with four replicates per group. Eight pigs were used per replicate for the 17-week feeding trial. The grower diet was given at 0 to 6 weeks and a finisher diet was given at 6 to 17 weeks. The treatments were as follows: SC diet(control; single-layer conditioning), DC diet(double-layer conditioning), and RC diet(retention-conditioning). Starch gelatinization was significantly higher(P<0.05) in the RC treatment than in the SC treatment, however, there was no significant difference in the starch gelatinization between the DC group and the RC group. In the growing phase, the feed to gain index(F:G) was significantly lower(P<0.05) in the RC group than in the SC and DC groups. Between growing and finishing, the F:G was the lowest(P<0.05) in the SC group compared to the RC or DC group. Drip loss, a measurement of meat quality, was significantly lower(P<0.05) in longissimus dorsi tissue collected from pigs fed the RC diet than in tissues collected from pigs fed the SC diet. The intestinal quality of the duodenum and jejunum tissues showed a significant increase(P<0.05) in the crypt depth and villus height in the RC group compared to the SC-or DC-treated pigs. These results demonstrated that the retentionconditioner treatment decreased the F:G in growing pigs, improved intestinal morphology and enhanced the meat quality in the finishing pigs. However, the retention-conditioner treatment had a negative impact on growth performance in the finishing pigs.展开更多
Oyster shell soil conditioner had significant influence on soil and rhizospheric microorganisms in their biomass,respiratory intensity and nutritional requirement. It could stimulate growth of soil and rhizospheric mi...Oyster shell soil conditioner had significant influence on soil and rhizospheric microorganisms in their biomass,respiratory intensity and nutritional requirement. It could stimulate growth of soil and rhizospheric microorganisms, especially nitrogen-fixers, and intensify soil respiration in proportion to the dose and fertilizing time of the conditioner, leading to the increase in the number of nitrogen fixing bacteria and the decrease in the number of bacteria with special nutrition demands.展开更多
A field experiment was conducted to evaluate the remediation effects of 14 soil conditioners for Cd-polluted paddy fields contrasted with conventional fertilization and liming.The results showed that soil conditioners...A field experiment was conducted to evaluate the remediation effects of 14 soil conditioners for Cd-polluted paddy fields contrasted with conventional fertilization and liming.The results showed that soil conditioners had no significant impact on rice yields.Though the soil conditioners had stable effects on decreasing the Cd content in grains,the effects varied with the category of conditioners.In general,The Cd contents of early rice and late rice were reduced by 22.65%~44.24%and 15.20%~63.03%,respectively.Additionally,the stem and leaves showed the same decreasing tendency.Cluster analysis suggested that soil conditioners can be divided into three categories:the first category increases the soil pH to inhibit the Cd activity and cut down the Cd translocation from soil to stem and leaves,which is most efficient in the reduction of Cd content in rice grains;the other category relies on the antagonism or co-precipitation between Cd and certain elements to inhibit the translocation and redistribution of Cd from rice stems to grains,providing a common effect on Cd reduction;the last category can be seen as a combination of the former two categories from the perspective of its functional mechanism and it has a moderate effect on the reduction of Cd contents in rice grains.展开更多
According to the requirements of welding process for vortex type compressor of air conditioner manufactured in product line, a special girth welding machine with PLC as control core was developed, which had both uprig...According to the requirements of welding process for vortex type compressor of air conditioner manufactured in product line, a special girth welding machine with PLC as control core was developed, which had both upright and 45 ° incline service positions. And some key technologies were researched, such as structural design of machine body, reliable conduction of rotary weldments and quality control of welding process and so on. The experimental results showed that this machine could satisfy the requirements of welding quality and girth welding technology, results also proved the machine was a high-effwiency and low-cost automatic welding device.展开更多
The effects of biochar as a soil conditioner on microbial communities were studied. The results showed that, at all the growth stages of tobacco, the quantity of microorganisms in the rhizosphere soil added with the s...The effects of biochar as a soil conditioner on microbial communities were studied. The results showed that, at all the growth stages of tobacco, the quantity of microorganisms in the rhizosphere soil added with the soil conditioner was higher than control (CK). The results of metagenome detection indicated that the diversity of microbial communities in soil added with the soil conditioner was also higher than the CK, and the rate of tobacco bacterial wilt and the disease index decreased by 27.6% and 34.6%, respectively, compared with the CK. In conclusion, the soil con- ditioner could reduce the soil-borne disease by improving micro-ecological environ- ment and diversity of microbial communities in rhizosphere soil to maintain the soil balance.展开更多
This paper presents the simulation results of a 9000 BTU/h air conditioner with some selected fluids that have been assessed for their suitability as alternatives to R22 for air conditioners. Only those refrigerants w...This paper presents the simulation results of a 9000 BTU/h air conditioner with some selected fluids that have been assessed for their suitability as alternatives to R22 for air conditioners. Only those refrigerants with zero Ozone Depletion Potential (ODP) are considered. The performances of 11 refrigerants were comparatively studied using the simulation software NIST Cycle_D. R134a, R290, R600, R404A, R407A, R407B, R407C, 407D, R410A, R410B, and R417A are considered in this study. The thermal performances, which are obtained with R 134a and R290, are very close to those of R22. The power consumptions of the unit operating with R404A, R407C, and R410A are higher in the range 22-31% with respect of R22. For the units operating with 407A, R407B, R407D, R407E, and R410B, the electric consumptions are higher in the range 10-23%. For R600, the power consumptions are in the range 6-8%. For all the fluids, the COP is lower by 7-24% than R22, except for R600 for which the COP is higher by 7-9%, and R134a and R290 which exhibit the same COP as R22. When considering the thermal and environmental parameters, R290 is identified as the best candidate for R22, provided the safety aspects of using R290 are addressed.展开更多
Diamond grits may be thermally weakened during the high temperature cycle of brazing.This weakening may exhibit as diamond breakage.During the dressing action,taller diamond grits are more likely to break due to the h...Diamond grits may be thermally weakened during the high temperature cycle of brazing.This weakening may exhibit as diamond breakage.During the dressing action,taller diamond grits are more likely to break due to the higher stress present.展开更多
Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into p...Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.展开更多
High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial asp...High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled(EV-cooled)greenhouse in winter and summer seasons.Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University,Oman,with dimensions of 6.0 m long and 3.0 m wide.The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes(LED)lights were used as a source of light,while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source.Three cultivars of high-value lettuce were grown for experimentation.To evaluate the technical efficiency of greenhouse performance,we conducted measures on land use efficiency(LUE),water use efficiency(WUE),gross water use efficiency(GWUE)and energy use efficiency(EUE).Financial analysis was conducted to compare the profitability of both greenhouses.The results showed that the LUE in winter were 10.10 and 14.50 kg/m^(2) for the AC-and EV-cooled greenhouses,respectively.However,the values reduced near to 6.80 kg/m^(2) in both greenhouses in summer.The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8%in winter and 26.8%in summer.The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water;it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%.The EUE in the EV-cooled greenhouse was higher in both seasons.Financial analysis showed that in winter,gross return,net return and benefit-to-cost ratio were better in the EVcooled greenhouse,while in summer,those were higher in the AC-cooled greenhouse.The values of internal rate of return in the AC-and EV-cooled greenhouses were 63.4%and 129.3%,respectively.In both greenhouses,lettuce investment was highly sensitive to changes in price,yield and energy cost.The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter.Finally,more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.展开更多
This work demonstrates the possibility to make a full valuation of a solid waste such as turkey manure, to obtain methane and a soil conditioner/fertilizer from turkey manure anaerobic digestion in a mesophilic pilot-...This work demonstrates the possibility to make a full valuation of a solid waste such as turkey manure, to obtain methane and a soil conditioner/fertilizer from turkey manure anaerobic digestion in a mesophilic pilot-scale continuous stirred tank reactor at different organic loading rates (OLR) (from 0.5 to 2.5 kgVS/m3d). The application of the anaerobic mono-digestion for the turkey manure treatment was an efficient alternative, because high volatile solids removal and methane were obtained in addition to obtaining a stabilized solid waste that can be applied as soil conditioner, based on its nutritional parameters and humic substances content. In this way, the turkey manure anaerobic digestion can be applied avoiding the co-digestion of the manure with other wastes and allows a process devoid of pollutant emissions, obtaining two products. The reactor operation depends on the OLR, and its operation does not allow an OLR above 1.5 kgVS/m3d. Higher OLR produced a decrease in the TS and VS removals and methane productivity.展开更多
This paper presents a new AC chopper voltage conditioner, which can generate high quality sinusoidal waveforms with adjustable amplitudes. The circuit structure, operation principle, and control mode are analyzed in d...This paper presents a new AC chopper voltage conditioner, which can generate high quality sinusoidal waveforms with adjustable amplitudes. The circuit structure, operation principle, and control mode are analyzed in detail, the system essentially consisting of an equal duty cycle modulation AC voltage buck chopper and a voltage polarity change H-bridge, a full-wave rectifier, to perform tightly closed-loop control of the AC chopper voltage condtioner, a digital controller on a new converter model has been developed. The controller has very well dynamic response. To evaluate the new circuit and proposed control scheme, a 5kW conditioner is developed and the experimental results demonstrate that the system has good performances.展开更多
基金supported by the National Natural Science Foundation of China(31560122)the Guangxi Key Laboratory of Agro-Environment and Agric-Products Safety,China。
文摘The addition of silicon(Si)and organic fertilizers to soil conditioners can inhibit the transfer of heavy metal ions from soil to crops.However,it is not clear how Si and organic fertilizers affect soil properties and the micro-ecological environment and thereby reduce cadmium(Cd)accumulation in rice.In this study,the effects of L-type soil conditioners containing Si and organic fertilizers on bacterial and fungal community diversity,soil pH,organic matter,and available Si were analyzed with field experiments at two sites in Liuzhou City and Hezhou City,respectively,in Guangxi,China.With the increase of Si and organic fertilizer content in soil conditioner,rice yield respectively increased by 16.8–25.8 and 6.8–13.1%,and rice Cd content decreased significantly by 8.2–21.1 and 10.8–40.6%,respectively,at the two experimental sites.Soil microbiome analysis showed that the increase in abundance of Firmicutes and Actinobacteriota bacteria associated with Cd adsorption and sequestration,and Basidiomycota fungal populations associated with degradation of macromolecules favored the inhibition of soil Cd activity(soil exchangeable Cd decreased by 14.4–14.8 and 18.1–20.6%).This was associated with an increase in organic matter and Si content caused by applying soil conditioners.In conclusion,L-type soil conditioners,rich in Si and organic fertilizer,can reduce soil Cd bioavailability by regulating the dominant Cd passivating flora in the soil and ultimately reduce Cd accumulation in rice.
文摘This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.
文摘Traditional air conditioner used to be in local control mode. However, with the development of modern information technology, the control of air conditioner will have to support many more functions. As a first step in such a development, we have implemented a remote monitoring system of unitary air conditioners, using the manufacturing message specification (MMS). MMS is an OSI application protocol designed for the remote control and monitoring of real devices. The functions supported are those that an operator would do normally at the console of the unitary air conditioner. Due to the accomplishment of UMCS (Unitary air conditioner MMS Control System), there will be a leap of the application of MMS and the control technology of unitary air conditioner.
文摘To investigate the effects of Tianshifu soil conditioners on rice growth and their control effects on Cd absorption and accumulation in rice, a test was carded out in the field typically polluted by Cd in Hunan Province. The results showed that the Tianshifu soil conditioner, soil bacterial conditioner and the combination of Tian- shifu soil conditioner and soil bacterial conditioner all could promote rice growth, im- prove rice yield and reduce significantly Cd content in rice grains. In Beishan, the Cd contents in rice grains treated by Tianshifu soil conditioner, soil bacterial condi- tioner and the combination of Tianshifu soil conditioner and soil bacterial conditioner were reduced by 37.63% (P〈0.05), 32.59% (P〈0.05) and 27.95% (P〈0.05) respec- tively compared with that in rice grains treated by conventional fertilization; In Xiang- tan, the Cd contents in rice grains were reduced by 54.36% (P〈0.05), 50.19% (P〈 0.05) and 45.22% (P〈0.05) respectively. The rice grains harvested at the two test sites all met the national food safety standards. Considering the control effect on Cd contamination, Tianshifu soil conditioner 〉 combination of Tianshifu soil condi- tioner and soil bacterial conditioner 〉 Tianshifu soil bacterial conditioner. In addition to reducing Cd absorption in rice, as described in the lime application treatment, the application of Tianshifu soil conditioners also inhibited the transportation of Cd from rice straws to rice grains. The Tianshifu soil conditioner, soil bacterial conditioner and combination of Tianshifu soil conditioner and soil bacterial conditioner also effec- tively improved the soil acidity, increased the soil pH value and reduced soil avail- able Cd content to some extent.
文摘A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of pneumatic valve the displacement is controlled by electronic control valve. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed according to the geometrical and kinematical information of the compressor. Using the model, the effect of relevant parameters on variable displace control is estimated. It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneumatic valves. And by using this new electronic control device, the optimum systemic control of AAC is available.
基金Projects(50978087,50908081)supported by the National Natural Science Foundation of China
文摘Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index (GI), were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.
基金Project partly supported by a grant from Expressway International Ltd., USA.
文摘A pot experiment was conducted to investigate the effects of various soil treatments on the growth of vetiver grass ( Vetiveria zizanioides (L.) Nash) with the objective of formulating appropriate soil media for use in sulfide-bearing mined areas. An acidic mine site acid sulfate soil (pH 2.8) was treated with different soil conditioner formula including hydrated lime, red mud (bauxite residues), zeolitic rock powder, biosolids and a compound fertilizer. Soils treated with red mud and hydrated lime corrected soil acidity and reduced or eliminated metal toxicity enabling the establishment of vetiver grass.Although over-liming affected growth, some seedlings of vetiver survived the initial strong alkaline conditions. Addition of appropriate amounts of zeolitic rock powder also enhanced growth, but over-application caused detrimental effects. In this experiment, soil medium with the best growth performance of vetiver was 50 g of red mud, 10 g of lime, 30 g of zeolitic rock powder and 30 g of biosolids with 2000 g of mine soils (100% survival rate with the greatest biomass and number of new shoots), but adding a chemical fertilizer to this media adversely impacted plant growth. In addition, a high application rate of biosolids resulted in poorer growth of vetiver, compared to a moderate application rate.
基金supported by the National Key R&D Program of China(No.2016YFB1200504-F)the National Natural Science Foundation of China(No.51705267)+1 种基金the China Postdoctoral Science Foundation(No.2018M630750)the China Railway R&D Program(No.2015J009-D).
文摘In order to investigate how the aerodynamic drag and noise produced by the roof air conditioner of a high-speed train can be reduced,the related unsteady flow in the near-field was computed using the method of large eddy simulation.In this way,the aerodynamic source for noise generation has initially been determined.Then,the far-field aerodynamic noise has been computed in the framework of the Lighthill’s acoustics analogy theory.The propulsion height and flow-guide angle of the roof air conditioner were set as the design variables.According to the computational results,a lower propulsion height or flow-guide angle is beneficial in terms of aerodynamic drag and noise mitigation.However,compared to the design scheme with propulsion height of 0mm,the aerodynamic drag coefficient of the configuration with propulsion height of 190mm and flow-guide angle of 30°is slightly larger,while the aerodynamic noise is obviously reduced.Thus,from the viewpoint of the aerodynamic drag and noise,the design scheme with propulsion height of 190 mm and flow-guide angle of 30°is the optimal configuration in the range of conditions examined in the present work.
基金financially supported by the National Key Research and Development Program of China(2016YFF0201800)the National Natural Science Foundation of China(31572631,31372539)+3 种基金the Beijing Technology System for Sturgeon and Salmonids,China(SCGWZJ 20171103-1)the National Basic Research Program of China(2014CB138600)the Fundamental Research Funds of China(1610382016010)the Special Scientific Research Fund of Agriculture Public Welfare Profession of China(201203015)
文摘This experiment was conducted to investigate the effects of feed conditioners(single-layer, double-layer and retentionconditioner) on the growth performance, meat quality and intestinal morphology of pigs throughout the growing to finishing phase. A total of 96 growing pigs((28.70±3.20) kg) were selected and randomized into three treatment groups with four replicates per group. Eight pigs were used per replicate for the 17-week feeding trial. The grower diet was given at 0 to 6 weeks and a finisher diet was given at 6 to 17 weeks. The treatments were as follows: SC diet(control; single-layer conditioning), DC diet(double-layer conditioning), and RC diet(retention-conditioning). Starch gelatinization was significantly higher(P<0.05) in the RC treatment than in the SC treatment, however, there was no significant difference in the starch gelatinization between the DC group and the RC group. In the growing phase, the feed to gain index(F:G) was significantly lower(P<0.05) in the RC group than in the SC and DC groups. Between growing and finishing, the F:G was the lowest(P<0.05) in the SC group compared to the RC or DC group. Drip loss, a measurement of meat quality, was significantly lower(P<0.05) in longissimus dorsi tissue collected from pigs fed the RC diet than in tissues collected from pigs fed the SC diet. The intestinal quality of the duodenum and jejunum tissues showed a significant increase(P<0.05) in the crypt depth and villus height in the RC group compared to the SC-or DC-treated pigs. These results demonstrated that the retentionconditioner treatment decreased the F:G in growing pigs, improved intestinal morphology and enhanced the meat quality in the finishing pigs. However, the retention-conditioner treatment had a negative impact on growth performance in the finishing pigs.
基金support from the 863 National High-Technology Program of China(819-07-10).
文摘Oyster shell soil conditioner had significant influence on soil and rhizospheric microorganisms in their biomass,respiratory intensity and nutritional requirement. It could stimulate growth of soil and rhizospheric microorganisms, especially nitrogen-fixers, and intensify soil respiration in proportion to the dose and fertilizing time of the conditioner, leading to the increase in the number of nitrogen fixing bacteria and the decrease in the number of bacteria with special nutrition demands.
基金Supported by Specialized Scientific Research in Public Welfare Sector Water Resources Ministry(201501019)Scientific and Technological Innovation Project in Hunan Academy of Agricultural Sciences(2017JC57)+1 种基金Science and Technology Planning Project in Changsha(kq1703010)Post Scientist of Rice Industrial System in China(CARS-01-28)~~
文摘A field experiment was conducted to evaluate the remediation effects of 14 soil conditioners for Cd-polluted paddy fields contrasted with conventional fertilization and liming.The results showed that soil conditioners had no significant impact on rice yields.Though the soil conditioners had stable effects on decreasing the Cd content in grains,the effects varied with the category of conditioners.In general,The Cd contents of early rice and late rice were reduced by 22.65%~44.24%and 15.20%~63.03%,respectively.Additionally,the stem and leaves showed the same decreasing tendency.Cluster analysis suggested that soil conditioners can be divided into three categories:the first category increases the soil pH to inhibit the Cd activity and cut down the Cd translocation from soil to stem and leaves,which is most efficient in the reduction of Cd content in rice grains;the other category relies on the antagonism or co-precipitation between Cd and certain elements to inhibit the translocation and redistribution of Cd from rice stems to grains,providing a common effect on Cd reduction;the last category can be seen as a combination of the former two categories from the perspective of its functional mechanism and it has a moderate effect on the reduction of Cd contents in rice grains.
文摘According to the requirements of welding process for vortex type compressor of air conditioner manufactured in product line, a special girth welding machine with PLC as control core was developed, which had both upright and 45 ° incline service positions. And some key technologies were researched, such as structural design of machine body, reliable conduction of rotary weldments and quality control of welding process and so on. The experimental results showed that this machine could satisfy the requirements of welding quality and girth welding technology, results also proved the machine was a high-effwiency and low-cost automatic welding device.
基金Supported by Science and Technology Project of Nanping Tobacco Company(NYK2012-14-3)~~
文摘The effects of biochar as a soil conditioner on microbial communities were studied. The results showed that, at all the growth stages of tobacco, the quantity of microorganisms in the rhizosphere soil added with the soil conditioner was higher than control (CK). The results of metagenome detection indicated that the diversity of microbial communities in soil added with the soil conditioner was also higher than the CK, and the rate of tobacco bacterial wilt and the disease index decreased by 27.6% and 34.6%, respectively, compared with the CK. In conclusion, the soil con- ditioner could reduce the soil-borne disease by improving micro-ecological environ- ment and diversity of microbial communities in rhizosphere soil to maintain the soil balance.
文摘This paper presents the simulation results of a 9000 BTU/h air conditioner with some selected fluids that have been assessed for their suitability as alternatives to R22 for air conditioners. Only those refrigerants with zero Ozone Depletion Potential (ODP) are considered. The performances of 11 refrigerants were comparatively studied using the simulation software NIST Cycle_D. R134a, R290, R600, R404A, R407A, R407B, R407C, 407D, R410A, R410B, and R417A are considered in this study. The thermal performances, which are obtained with R 134a and R290, are very close to those of R22. The power consumptions of the unit operating with R404A, R407C, and R410A are higher in the range 22-31% with respect of R22. For the units operating with 407A, R407B, R407D, R407E, and R410B, the electric consumptions are higher in the range 10-23%. For R600, the power consumptions are in the range 6-8%. For all the fluids, the COP is lower by 7-24% than R22, except for R600 for which the COP is higher by 7-9%, and R134a and R290 which exhibit the same COP as R22. When considering the thermal and environmental parameters, R290 is identified as the best candidate for R22, provided the safety aspects of using R290 are addressed.
文摘Diamond grits may be thermally weakened during the high temperature cycle of brazing.This weakening may exhibit as diamond breakage.During the dressing action,taller diamond grits are more likely to break due to the higher stress present.
文摘Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.
文摘High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled(EV-cooled)greenhouse in winter and summer seasons.Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University,Oman,with dimensions of 6.0 m long and 3.0 m wide.The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes(LED)lights were used as a source of light,while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source.Three cultivars of high-value lettuce were grown for experimentation.To evaluate the technical efficiency of greenhouse performance,we conducted measures on land use efficiency(LUE),water use efficiency(WUE),gross water use efficiency(GWUE)and energy use efficiency(EUE).Financial analysis was conducted to compare the profitability of both greenhouses.The results showed that the LUE in winter were 10.10 and 14.50 kg/m^(2) for the AC-and EV-cooled greenhouses,respectively.However,the values reduced near to 6.80 kg/m^(2) in both greenhouses in summer.The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8%in winter and 26.8%in summer.The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water;it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%.The EUE in the EV-cooled greenhouse was higher in both seasons.Financial analysis showed that in winter,gross return,net return and benefit-to-cost ratio were better in the EVcooled greenhouse,while in summer,those were higher in the AC-cooled greenhouse.The values of internal rate of return in the AC-and EV-cooled greenhouses were 63.4%and 129.3%,respectively.In both greenhouses,lettuce investment was highly sensitive to changes in price,yield and energy cost.The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter.Finally,more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.
文摘This work demonstrates the possibility to make a full valuation of a solid waste such as turkey manure, to obtain methane and a soil conditioner/fertilizer from turkey manure anaerobic digestion in a mesophilic pilot-scale continuous stirred tank reactor at different organic loading rates (OLR) (from 0.5 to 2.5 kgVS/m3d). The application of the anaerobic mono-digestion for the turkey manure treatment was an efficient alternative, because high volatile solids removal and methane were obtained in addition to obtaining a stabilized solid waste that can be applied as soil conditioner, based on its nutritional parameters and humic substances content. In this way, the turkey manure anaerobic digestion can be applied avoiding the co-digestion of the manure with other wastes and allows a process devoid of pollutant emissions, obtaining two products. The reactor operation depends on the OLR, and its operation does not allow an OLR above 1.5 kgVS/m3d. Higher OLR produced a decrease in the TS and VS removals and methane productivity.
文摘This paper presents a new AC chopper voltage conditioner, which can generate high quality sinusoidal waveforms with adjustable amplitudes. The circuit structure, operation principle, and control mode are analyzed in detail, the system essentially consisting of an equal duty cycle modulation AC voltage buck chopper and a voltage polarity change H-bridge, a full-wave rectifier, to perform tightly closed-loop control of the AC chopper voltage condtioner, a digital controller on a new converter model has been developed. The controller has very well dynamic response. To evaluate the new circuit and proposed control scheme, a 5kW conditioner is developed and the experimental results demonstrate that the system has good performances.