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A Sensorless I-F Start-up Strategy for Flying Start of Ultra-high-speed Permanent Magnet Motors based on Short-circuit Transient Differentiation 认领 引用
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作者 Wei Chen Peizhe Liu +2 位作者 Lixiang Zhu Xinmin Li Zhezhun Xu 《CES Transactions on Electrical Machines and Systems》 EI CSCD 2026年第2期228-239,共12页
Conventional current-to-frequency(I-F)start-up strategies apply only to zero-speed conditions.When a nonzero initial speed(referred to as a flying start)exists,loss of synchronism is likely to occur because the virtua... Conventional current-to-frequency(I-F)start-up strategies apply only to zero-speed conditions.When a nonzero initial speed(referred to as a flying start)exists,loss of synchronism is likely to occur because the virtual synchronous reference frame fails to align with the rotor flux linkage direction.To meet the flying start requirements of ultra-highspeed permanent magnet motors,this paper proposes a sensorless I-F start-up strategy for flying starts based on differential analysis of short-circuit transients.Upon power-up,the inverter places the three-phase stator windings in a controlled short-circuit state and applies two short-duration short-circuit pulses at different instants.By sampling the phase variation of the stator current vectors during the two shortcircuit transients,differential current characteristics are extracted to rapidly estimate the initial rotor position and speed,thereby facilitating smooth I-F start-up.The proposed method overcomes the limitations of conventional I-F strategies confined to zero-speed start-up and is applicable to oil-film and airbearing supported motor systems.Experimental results validate a smooth flying start featuring continuous and impact-free stator currents,effective suppression of mechanical friction prior to airfilm formation,and the enhanced stability and robustness of I-F start-up. 展开更多
关键词 Ultra-high-speed permanent magnet motor Current-to-frequency(I-F)start-up Flying start Short-circuit transient Sensorless control
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Efficient start-up of anaerobic methanogenesis process for kitchen waste biodegradation utilizing polyurethane sponge 认领 引用
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作者 Yijuan Yan Jinming Qiu +5 位作者 Hongming Wu Takuro Kobayashi Samir I.Gadow Chenming Xu Yong Hu Xueying Zhang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2026年第5期522-534,共13页
The delayed start-up phase of anaerobic digestion(AD)of kitchen waste(KW)seriously affects overall efficiency.The positive impact of organic fillers in anaerobic wastewater treatment has inspired the treatment of oily... The delayed start-up phase of anaerobic digestion(AD)of kitchen waste(KW)seriously affects overall efficiency.The positive impact of organic fillers in anaerobic wastewater treatment has inspired the treatment of oily solid waste.This study compared the impacts of four popular fillers:polypropylene(PP),high-density polyethylene(HDPE),expandable polystyrene(EPS),and polyurethane sponge(PUS)to determine the optimal filler to achieve efficient starting KW-AD.The findings demonstrated that EPS,PP and HDPE reduced cumulative methane production by 43.27%,87.64%and 89.18%;PP and HDPE increased the concentration of acetate by 42.68%and 59.90%,generated start-up failure;the three increased the abundance of Actinobacteriota by more than 15.52%,which caused sludge foaming.Conversely,PUS shortened the start-up phase of AD by 46.06%,increased the cumulative methane production by 20.99%,enhanced the abundances of hydrogen-producing bacteria(Thermotogota)and hydrogenotrophic methanogens(Methanoculleus)in the sludge by 15.73%and 33.33%.This suggested that the hydrogenotrophic methanogenesis pathway is significantly augmented.The surface of PUS mainly enriched two electrochemically active bacteria(Thiopseudomonas,19.76%;Defluviitoga,12.71%)to enhance interspecies electron transfer(IET).Further exploration revealed 2.80 g/g VS was the optimum PUS dosage for the start-up phase of KW-AD;and this threshold should not be lower than 0.93 g/g VS.This research revealed the mechanism by which the filler modulates the microbial community to enhance the degradation of organic matter,while also offering a theoretical reference for the efficient start-up of KW-AD. 展开更多
关键词 Kitchen waste Anaerobic digestion Start-up phase Polyurethane sponge Hydrogenotrophic methanogenesis
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A comparison study of the start-up of a MnO_x filter for catalytic oxidative removal of ammonium from groundwater and surface water 认领 引用 被引量：8
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作者 Ya Cheng Ye Li +3 位作者 Tinglin Huang Yuankui Sun Xinxin Shi Yuezong Shao 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2018年第3期327-334,共8页
As an efficient method for ammonium（NH4~＋）removal,contact catalytic oxidation technology has drawn much attention recently,due to its good low temperature resistance and short start-up period.Two identical filters ... As an efficient method for ammonium（NH4~＋）removal,contact catalytic oxidation technology has drawn much attention recently,due to its good low temperature resistance and short start-up period.Two identical filters were employed to compare the process for ammonium removal during the start-up period for ammonium removal in groundwater（Filter-N）and surface water（Filter-S）treatment.Two types of source water（groundwater and surface water）were used as the feed waters for the filtration trials.Although the same initiating method was used,Filter-N exhibited much better ammonium removal performance than Filter-S.The differences in catalytic activity among these two filters were probed using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,and compositional analysis.XRD results indicated that different manganese oxide species were formed in Filter-N and Filter-S.Furthermore,the Mn3p XPS spectra taken on the surface of the filter films revealed that the average manganese valence of the inactive manganese oxide film collected from Filter-S（FS-MnOx）was higher than in the film collected from Filter-N（FN-MnOx）.Mn（IV）was identified as the predominant oxidation state in FS-MnOxand Mn（III）was identified as the predominant oxidation state in FN-MnOx.The results of compositional analyses suggested that polyaluminum ferric chloride（PAFC）used during the surface water treatment was an important factor in the mineralogy and reactivity of MnOx.This study provides the theoretical basis for promoting the wide application of the technology and has great practical significance. 展开更多
关键词 Ammonium removal Surface water Underground water Start-up Catalytic oxidation Filtration
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Effects of Sub-zero Celsius Treatment and Tempering on the Stability of Retained Austenite in Bearing Steel 认领 引用 被引量：2
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作者 Xiao-Hui Lu Wei Li +2 位作者 Cheng-Lin Wang Hong-Shan Zhao Xue-Jun Jin 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2015年第6期787-792,共6页
In this work, the influence of sub-zero Celsius treatment and tempering on the mechanical and thermal stability of retained austenite in beating steel were assessed by tensile test and DSC. Compared with traditional q... In this work, the influence of sub-zero Celsius treatment and tempering on the mechanical and thermal stability of retained austenite in beating steel were assessed by tensile test and DSC. Compared with traditional quenched and tempered treatment, sub-zero Celsius treatment obviously decreases the volume fraction of retained austenite. Moreover, the mechanical stability of retained austenite was enhanced due to the accumulation of compressive stresses in retained austenite after sub-zero Celsius treatment and tempering. Meanwhile, the morphology of retained austenite changed from film-like to blocky with austenitization temperature increasing, and the mechanical stability of film-like retained austenite is higher than that of blocky one. The DSC results showed that the activation energy of retained austenite decomposition slightly increased through sub-zero Celsius treatment and tempering. This result may probably be ascribed to partitioning of carbon during tempering. However, the temperature at which retained austenite starts to decompose is unchanged. 展开更多
关键词 Bearing steel Sub-zero Celsius treatment Retained austenite Stability
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The start-up of biohydrogen-producing process by bioaugmentation in the EGSB reactor 认领 引用 被引量：5
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作者 王相晶 Ren Nanqi +1 位作者 Xiang Wensheng Guo Wanqian 《High Technology Letters》 EI CAS 2006年第3期328-332,共5页
Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 ... Expanded granular sludge bed （EGSB） reactor and bioaugmentation were employed to investigate biohydrogen production with molasses wastewater. The start-up experiments consisted of two stages. In the first stage （0 - 24d） seeded with activated sludge, the butyric acid type-fermentation formed when the initial expanding rate, organic loading rate （OLR）, the initial redox potential （ORP） and hydraulic retention time （HRT） were 10%, 10.0 kg COD/（m^3·d）, -215 mV and 6.7 h, respectively. At the beginning of the second stage on day 25, the novel hydrogen-producing fermentative bacterial strain B49 （AF481148 in EMBL） were inoculated into the reactor under the condition of OLR 16. 0 kg COD/（m^3·d）, ORP and HRT about - 139 mV and 6.7 h, respectively, and then the reaction system transformed to ethanol-type fermentation gradually with the increase in OLR. When OLR, ORP and HRT were about 94.3 kg COD/（m^3·d）, -250 mV and 1.7 h, respectively, the system achieved the maximum hydrogen-producing rate of 282.6 mL H2/L reactor·h and hydrogen percentage of 51% -53% in the biogas. 展开更多
关键词 start-up biohydrogen production bioaugmentation hydrogen-producing bacterial strain B49 EGSB reactor
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Development of anti-corrosive coating on AZ31 Mg alloy subjected to plasma electrolytic oxidation at sub-zero temperature 认领 引用 被引量：2
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作者 S.Fatimah M.P.Kamil +2 位作者 D.I.Han W.Al-Zoubi Y.G.Ko 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2022年第7期1915-1929,共15页
Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plas... Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plasma,however,inevitably generates porous structures that limit their practical performance.The present study proposes a straight-forward simple method by utilizing sub-zero electrolyte(268 K)to alter the plasma characteristics during formation of the protective coating on AZ31 Mg alloy via PEO with a comparison to the electrolyte at room temperature(298 K).In refrigerated electrolyte,the formation of micro-defects is suppressed relatively at the expense of low coating growth,which is measured to be twice lower than that at 298 K due to the temperature-dependent soft plasma discharges contributing to the development of the present coating.As a consequence,corrosion resistance of the sample processed at 268 K is superior to that of 298K,implying that the effect of coating thickness is less dominant than that of compactness.This phenomenon is interpreted in relation to the ionic movement and oxide solidification controlled by soft plasma discharges arising from the temperature gradient between electrolyte and surface of the substrate during PEO. 展开更多
关键词 AZ31 Mg alloy Plasma electrolytic oxidation Sub-zero electrolyte Anti-corrosive coating Corrosion
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Numerical study on ignition start-up process of an underwater solid rocket motor across a wide depth range 认领 引用 被引量：2
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作者 Deyou WANG Shipeng LI +3 位作者 Ge JIN Ruyao WANG Dian GUAN Ningfei WANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第10期136-157,共22页
Solid rocket motors have important applications in the propulsion of trans-media vehicles and underwater launched rockets.In this paper,the ignition start-up process of an underwater solid rocket motor across a wide d... Solid rocket motors have important applications in the propulsion of trans-media vehicles and underwater launched rockets.In this paper,the ignition start-up process of an underwater solid rocket motor across a wide depth range has been numerically studied.A novel multi-domain integrated model has been developed by combining the solid propellant ignition and combustion model with the volume of fluid multiphase model.This integrated model enables the coupled simulation of the propellant combustion and gas flow inside the motor,along with the gas jet evolution in the external water environment.The detailed flow field developments in the combustion chamber,nozzle,and wake field are carefully analyzed.The variation rules of the internal ballistics and thrust performance are also obtained.The effects of environmental medium and operating depth on the ignition start-up process are systematically discussed.The results show that the influence of the operating environment on the internal ballistic characteristics is primarily reflected in the initial period after the nozzle closure opens.The development of the gas jet in water lags significantly compared with that in air.As the water depth increases,the ignition delay time of the motor is shortened,and the morphology evolution of the gas jet is significantly compressed and accelerated.Furthermore,the necking and bulging of the jet boundary near the nozzle outlet and the consequent shock oscillations are intensified,resulting in stronger fluctuations in the wake pressure field and motor thrust. 展开更多
关键词 Underwater propulsion Solid rocket motor Ignition start-up process Underwater gas jet Thrust oscillation
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Stress-Structure Relationship of the Reversible Associating Polymer Network under Start-up Shear Flow 认领 引用 被引量：1
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作者 Ai-Qing Liu Li-Jun Liu +3 位作者 Wen-Sheng Xu Xiao-Lei Xu Ji-Zhong Chen Li-Jia An 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2021年第3期387-396,I0008,共10页
We adopt Langevin dynamics to explore the stress-structure relationship of telechelic reversible associating polymer gel during startup shear flow, with shear strengths varying from Wi=12.6 to Wi=12640. At weak shear ... We adopt Langevin dynamics to explore the stress-structure relationship of telechelic reversible associating polymer gel during startup shear flow, with shear strengths varying from Wi=12.6 to Wi=12640. At weak shear flow Wi=12.6, the shear stress proportionally increases with shear strain at short times, followed by a strain hardening behavior and then passes through a maximum(σmax, γmax) and finally decreases until it reaches the steady state. During the evolution of stress, the gel network is only slightly broken and essentially maintains its framework, and the strain hardening behavior originates from the excessive stretching of chains. On the other hand, the stress-strain curve at intermediate shear flow Wi=505.6 shows two differences from that at Wi=12.6, namely, the absence of strain hardening and a dramatic increase of stress at large strains,which is caused by the rupture of gel network at small strains and the network recovery at large strains, respectively. Finally, at very strong shear flow Wi=6319.7, the gel network is immediately broken by shear flow and the stress-strain curve exhibits similar behaviors to those of classical polymeric liquids. 展开更多
关键词 Associating polymer Start-up shear Stress-structure relationship
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The exact solution of Stokes'second problem including start-up process with fractional element 认领 引用 被引量：3
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作者 Kaixin Hu Keqin Zhu 《Acta Mechanica Sinica》 SCIE EI CAS 2009年第5期577-582,共6页
The start-up process of Stokes'second problem of a viscoelastic material with fractional element is studied.The fluid above an infinite flat plane is set in motion by a sudden acceleration of the plate to steady o... The start-up process of Stokes'second problem of a viscoelastic material with fractional element is studied.The fluid above an infinite flat plane is set in motion by a sudden acceleration of the plate to steady oscillation.Exact solutions are obtained by using Laplace transform and Fourier transform.It is found that the relationship between the first peak value and the one of equal-amplitude oscillations depends on the distance from the plate.The amplitude decreases for increasing frequency and increasing distance. 展开更多
关键词 Stokes'second problem Start-up process Fractional element Laplace transform Fourier transform
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Effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron 认领 引用 被引量：2
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作者 S. Yazdani M. Ardestani 《China Foundry》 SCIE CAS 2007年第2期120-123,共4页
The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325℃and 400℃after austenitizing at... The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325℃and 400℃after austenitizing at 875℃and 950℃. The sub-zero treatments were carried out by cooling down the samples to -30℃, -70℃and -196℃. The changes in volume fraction of austenite and mechanical properties were determined after cooling to each temperature. The austenite volume fraction of samples which were austenitized at 875℃and austempered at 325℃remained unchanged, whilst it reduced in samples austenitized at 950℃and 875℃for austempering temperature of 400℃. In these specimens, some austenite transformed to martensite after subzero cooling. Mechanical property measurements showed a slight increase in strength and hardness and decrease in elongation and toughness due to this transformation behavior. 展开更多
关键词 austempered ductile iron austenite sub-zero cooling martensitic transformation ausferrite
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Start-up and Performance of a Novel Reactor----Jet Biogas Inter-loop Anaerobic Fluidized Bed 认领 引用 被引量：2
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作者 邓志毅 韦朝海 周秀峰 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 2008年第1期143-150,共8页
A novel anaerobic reactor, jet biogas inter-loop anaerobic fluidized bed （JBILAFB）, was designed and constructed. The start-up and performance of the reactor was investigated in the Process. of .artificial glucose w... A novel anaerobic reactor, jet biogas inter-loop anaerobic fluidized bed （JBILAFB）, was designed and constructed. The start-up and performance of the reactor was investigated in the Process. of .artificial glucose wastewater treatment. With the wastewater recycle ratio of 2.5 ： 1, the recycled wastewater with biogas could mix sludge and wastewater in the JBILAFB reactor completely. The start-up of the JBILAFB reactor could be completed in less than 70 d through maintenance of hydraulic retention time （HR^I＂） and stepwise increase of feed total organic carbon （TOC） concentration. After the start-up, with the volumetric TOC loadings of 14.3 kg·m ^-3·d^-1, the TOC removal ratio, the effluent pH, and the volatile fatty acids （VFA）/alkalinity of the JBILAFB reactor were more than 80%, close to 7.0 and less than 0.4, respectively. Moreover, CH4 was produced at more than 70% of the theoretical value, The reactor exhibited high stability under the condition of high volumetric TOC loading. Sludge granules in the JBILAFB reactor were developed during the start-up and their sizes were enlarged with the stepwise increase of volumetric TOC loadings from 0.8 kg.m^-3.d ^-1 to 14.3 kg.m^-3.d^-1. Granules, an offwhite color and a similar spherical shape, were mainly comprised of global-like bacteria. These had good methanogenic activity and settleability, which were formed probably through adhesion of the bacteria. Some inorganic metal compounds such as Fe, Ca, Mg, Al, etc. were advantageous to the formation of the granules. 展开更多
关键词 anaerobic reactor jet biogas inter-loop anaerobic fluidized bed wastewater treatment start-up granule sludge
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Numerical simulation of the start-up process of a miniature ion thruster 认领 引用 被引量：1
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作者 Xinyong YANG Liqiu WEI +7 位作者 Wenjia JIANG Tianyuan JI Liwei ZHOU Hong LI Yongjie DING Jingfeng TANG Ning GUO Daren YU 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第7期63-73,共11页
A particle-in-cell Monte Carlo collision model of a discharge chamber is established to investigate the start-up process of a miniature ion thruster.We present the discharge characteristics at different stages(the ini... A particle-in-cell Monte Carlo collision model of a discharge chamber is established to investigate the start-up process of a miniature ion thruster.We present the discharge characteristics at different stages(the initial stage,development stage,and stable stage)according to the trend of the discharge current with time.The discharge current is the sum of the sidewall current and the backplate current.During the start-up process,the sidewall current lags behind the backplate current.The variation and distribution characteristics of the discharge current over time are determined by the electron density distribution and electric potential distribution. 展开更多
关键词 miniature ion thruster discharge chamber start-up process Monte Carlo collision
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Start-up and contaminants removal characteristics of aerobic granules-membrane bioreactor at low temperature 认领 引用 被引量：1
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作者 王硕 于水利 +2 位作者 时文歆 王玉兰 衣雪松 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2012年第1期67-70,共4页
In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and ope... In order to understand the effect of low temperature on the formation process of aerobic granules and contaminants removal characteristics,the aerobic granules-membrane bioreactor (AGS-MBR) has been started up and operated at low temperature using the carbon resource of sodium acetate. Aerobic granules cultivated in AGS-MBR possess smooth surface and compact structure in morphology as well as better settling property and higher biomass after 38 days. The average parameters of aerobic granules are: diameter 3. 1 mm,wet density 1. 041 g/mL,sludge volume index 42. 35 mL/g and settling velocity 20. 6 - 45. 2 cm/min. During the start-up of AGS-MBR,the respectively average contaminants removal efficiencies at low temperature are 91. 9% for chemical oxygen demand (COD) ,89. 2% for NH4 + -N and 86. 3% for PO43- -P,and the overgrowth of filamentous bacteria has been well controlled. In addition,the hollow fiber microfiltration (MF) membrane fouling is light and the regime membrane layer is capable of enhancing membrane filtration as well as the average growth of trans-membrane pressure (TMP) is 1. 07 kPa/d. Compared with the conventional cultivation of aerobic granules,the sludge granulation time significantly decreases from 73 days to 38 days by the application of microfiltration membrane at low temperature. 展开更多
关键词 Aerobic Granules-Membrane Bioreactor (AGS-MBR) Low Temperature Start-up Contaminants Removal Microfiltration (MF) Trans-Membrane Pressure (TMP)
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Quick start-up of EGSB reactor treating fresh leachate of municipal solid waste 认领 引用 被引量：1
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作者 刘建勇 边华丹 +6 位作者 曹亚丽 钟江平 胡军 刘强 钱光人 刘峰 邰俊 《Journal of Shanghai University(English Edition)》 2011年第3期212-217,共6页
An expanded granular sludge bed （EGSB） reactor inoculated with anaerobic granular sludge was started up with its COD removal performance, self-balancing of pH, biogas production rate and characteristics of the granu... An expanded granular sludge bed （EGSB） reactor inoculated with anaerobic granular sludge was started up with its COD removal performance, self-balancing of pH, biogas production rate and characteristics of the granular sludge during the start-up period being investigated. The results indicated that the EGSB reactor can be started up successfully in 27 d by increasing the organic loading rate rapidly. The removal efficiency of COD was maintained above 93% with influent COD concentration of 25 000 mg/L and OLR of 37.94 kgCOD/（m 3 ·d）. The EGSB reactor with good pH self-balancing could be fed with fresh leachate of low pH value （4 5）. The biogas production rate was closely related with OLR and COD reduction. Every gram of COD fed （consumed） to the reactor produced 0.34 L STP （0.36 L STP ） biogas with 0.21 L STP （0.23 L STP ） methane. Thus, 65% 70% of the produced biogas was methane. Sixty one percentage of COD fed to the reactor was converted to methane, another 33% was converted to biomass by metabolism, and the other 6% was left in the liquid phase. The specific methanogenic activity （SMA） of the granular sludge had increased by 92% after 27 d dynamic incubation. The granular sludge in the reactor had good settlement performance with majority diameter of 1 2 mm. 展开更多
关键词 expanded granular sludge bed （EGSB） reactor municipal solid waste fresh leachate start-up biogas
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The Realization of Low Loop Voltage Start-up of HT-7 Tokamak Discharge with the Assistance of Lower Hybrid Wave 认领 引用 被引量：1
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作者 方瑜德 罗家融 +4 位作者 匡光力 林建安 杨长春 秦品建 杨坤 《Plasma Science and Technology》 SCIE CAS 2001年第4期845-849,共5页
Low voltage start-up was realized in HT-7 discharges under the assistance of lower hybrid (LH) waves. The use of a strong LH wavet which can Change its N// spectrum in a large range of several milliseconds, made the l... Low voltage start-up was realized in HT-7 discharges under the assistance of lower hybrid (LH) waves. The use of a strong LH wavet which can Change its N// spectrum in a large range of several milliseconds, made the loop voltage for start-up reduce from around 20 V to less than 5 V. It means that the electric field for HT-7 start-up decreases from 2.5-3 V/m to 0.6 V/m. Some physical phenomena such as the consumption of magnetic flux in start-up phase and the radiation from the initial plasma were observed in this kind of low voltage start-up discharges. 展开更多
关键词 LHCD The Realization of Low Loop Voltage Start-up of HT-7 Tokamak Discharge with the Assistance of Lower Hybrid Wave HT
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Start-up phase plasma discharge design of a tokamak via control parameterization method 认领 引用
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作者 郭珊 许珂 +2 位作者 许超 任志刚 肖炳甲 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第3期248-254,共7页
The tokamak start-up is a very important phase during the process to obtain a suitable equalizing plasma, and its governing model can be described as a set of nonlinear ordinary differential equations（ODEs）. In this... The tokamak start-up is a very important phase during the process to obtain a suitable equalizing plasma, and its governing model can be described as a set of nonlinear ordinary differential equations（ODEs）. In this paper, we first estimate the parameters in the original model and set up an accurate model to express how the variables change during the start-up phase, especially how the plasma current changes with respect to time and the loop voltage. Then, we apply the control parameterization method to obtain an approximate optimal parameters selection problem for the loop voltage design to achieve a desired plasma current target. Computational optimal control techniques such as the variational method and the costate method are employed to solve the problem, respectively. Finally, numerical simulations are performed and the results obtained via different methods are compared. Our numerical parameterization method and optimization procedure turn out to be effective. 展开更多
关键词 tokamak start-up optimal control variational method
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Dynamic evaluation of a scaled-down heat pipe-cooled system during start-up/shut-down processes using a hardware-in-the-loop test approach 认领 引用
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作者 Jiao‑Long Deng Tian‑Shi Wang +3 位作者 En‑Ping Zhu Shuo Yuan Xiao‑Jing Liu Xiang Chai 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第11期174-198,共25页
Micro-mobile heat pipe-cooled nuclear power plants are promising candidates for distributed energy resource power genera-tors and can be flexibly deployed in remote places to meet increasing electric power demands.How... Micro-mobile heat pipe-cooled nuclear power plants are promising candidates for distributed energy resource power genera-tors and can be flexibly deployed in remote places to meet increasing electric power demands.However,previous steady-state simulations and experiments have deviated significantly from actual micronuclear system operations.Hence,a transient analysis is required for performance optimization and safety assessment.In this study,a hardware-in-the-loop(HIL)approach was used to investigate the dynamic behavior of scaled-down heat pipe-cooled systems.The real-time features of the HIL architecture were interpreted and validated,and an optimal time step of 500 ms was selected for the thermal transient.The power transient was modeled using point kinetic equations,and a scaled-down thermal prototype was set up to avoid mod-eling unpredictable heat transfer behaviors and feeding temperature samples into the main program running on a desktop PC.A series of dynamic test results showed significant power and temperature oscillations during the transient process,owing to the inconsistency of the rapid nuclear reaction rate and large thermal inertia.The proposed HIL approach is stable and effective for further studying of the dynamic characteristics and control optimization of solid-state small nuclear-powered systems at an early prototyping stage. 展开更多
关键词 Micro-heat pipe-cooled nuclear reactor Hardware-in-the-loop Dynamic evaluation Start-up/shut-down processes
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Research on the soft start-up performance of hydro-viscous drive 认领 引用 被引量：1
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作者 魏建华 陈宁 《Journal of Coal Science & Engineering(China)》 2004年第1期70-72,共3页
The principle and structure of hydro-viscous drive(HVD) set is introduced. Through theoretical analysis of the HVD set start-up steadiness, the conclusions were obtained that the non-linearity of the pressure performa... The principle and structure of hydro-viscous drive(HVD) set is introduced. Through theoretical analysis of the HVD set start-up steadiness, the conclusions were obtained that the non-linearity of the pressure performance curve and dynamic pressure instability of the pilot-operated electro-hydraulic pressure relief valve, which is used for the HVD speed regulating purpose and usually works within micro flow-rate and low oil pressure state, are the main causes of the poor start-up steadiness. So a special speed regulating valve for HVD set is developed, with which the start-up steadiness of HVD set is much improved. 展开更多
关键词 soft start-up steadiness HVD special speed regulating valve oil film conveyor
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START-UP AND DYNAMIC PROCESSES SIMULATION OF A DISTILLATION COLUMN 认领 引用
19
作者 宋海华 余国琮 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 1995年第3期13-23,共11页
A new dynamic non-equilibrium mixing-pool model for simulating start-up and dynamic re-sponse of a distillation column is reported.The proposed model is established on the basis ofconsidering the two dimensional flow/... A new dynamic non-equilibrium mixing-pool model for simulating start-up and dynamic re-sponse of a distillation column is reported.The proposed model is established on the basis ofconsidering the two dimensional flow/mixing behavior of actual trays in a distillation column.Com-parison is made among the computed results of the start-up time and the dynamic response time bythe proposed and five other typical models.It is found that the computed time for both dynamicprocesses is longer by the model which considers any flow/mixing pattern than by the model withoutsuch concern.The inertia effect of flow/mixing seems to be important and can not be ignored inmodeling the transient process of distillation.The proposed model,which is believed to be suitableto large column,seems somewhat useful in predicting industrial distillation dynamics. 展开更多
关键词 distillation simulation start-up dynamic process three dimensional non-equilibrium mixing-pool model
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Effects of relaxation time on start-up time for starting flow of Maxwell fluid in a pipe 认领 引用
20
作者 Zhen Li Keqin Zhu 《Acta Mechanica Sinica》 SCIE EI CAS 2010年第2期209-215,共7页
Although the analytical solution of the starting flow of Maxwell fluid in a pipe has been derived for a long time,the effect of relaxation timeλon start-up time ts of this flow is still not well understood.Especially... Although the analytical solution of the starting flow of Maxwell fluid in a pipe has been derived for a long time,the effect of relaxation timeλon start-up time ts of this flow is still not well understood.Especially,there exist a series of jumps on the ts-λ.curve.In this paper we introduce a normalized mechanical energy by mode decomposition and mathematical analogy to describe the start-up process.An improved definition of start-up time is presented based on the normalized mechanical energy.It is proved that the ts-λ.curve contains a series of jumps ifλis larger than a critical value.The exact positions of the jumps are determined and the physical reason of the jumps is discussed. 展开更多
关键词 Maxwell fluid Starting flow Relaxation time Start-up time Mechanical energy
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