Abstract:Surimi from silver carp were oxidized in a hydroxyl radicalgenerating systems (the concentration of H2O2 were 0.1,1.0,5.0,10.0 and 50.0 mmol/L,respectively),and the effects of oxidization on gel properties of surimi were investigated. The results showed that the breaking force,penetration distance,gel strength and water holding capacity of surimi gels increased firstly and decreased afterwards with the increase of H2O2 concentration. The maximum values were obtained at the H2O2 concentration of 1.0 mmol/L,indicating that moderate oxidation could improve the gel properties and the water holding capacity. At the same time,the T22 peak area in the moisture distribution also reached a maximum at the H2O2 concentration of 1.0 mmol/L. In addition,the activity of Ca2+ATPase significantly increased and followed by a decrease with the increase of H2O2 concentration. And the SEM result showed that moderate oxidation (0.1~1.0 mmol/L H2O2) could improve surimi gel network structure,whereas excessive oxidation would lead to the destruction of the network structure.

Abstract:Surimi from silver carp were oxidized in a hydroxyl radicalgenerating systems (the concentration of H2O2 were 0.1,1.0,5.0,10.0 and 50.0 mmol/L,respectively),and the effects of oxidization on gel properties of surimi were investigated. The results showed that the breaking force,penetration distance,gel strength and water holding capacity of surimi gels increased firstly and decreased afterwards with the increase of H2O2 concentration. The maximum values were obtained at the H2O2 concentration of 1.0 mmol/L,indicating that moderate oxidation could improve the gel properties and the water holding capacity. At the same time,the T22 peak area in the moisture distribution also reached a maximum at the H2O2 concentration of 1.0 mmol/L. In addition,the activity of Ca2+ATPase significantly increased and followed by a decrease with the increase of H2O2 concentration. And the SEM result showed that moderate oxidation (0.1~1.0 mmol/L H2O2) could improve surimi gel network structure,whereas excessive oxidation would lead to the destruction of the network structure.

Abstract:Myofibrillar proteins were prepared and stored at 25℃ and 4℃. The effects of alkaline protease on the degradation and gel properties of myofibrillar protein were studied using the degradation rate,sulfhydryl content,surface hydrophobicity,Ca2+ATPase activity and gel properties as indexes. For the myofibrillar proteins with alkaline protease,the degradation rate increased with prolonging storage time at different temperatures. The surface hydrophobicity,Ca2+ATPase activity,contents of total and active sulfhydryl groups increased followed by a decrease,and reached the maximum under the conditions of 25℃ and 2.0 h,or 4℃ and 2.5 h. In addition,the Ca2+ATPase activity reached the maximum at 0.5 h. As the storage time prolonged,the waterholding capacity and gel strength decreased,and the whiteness decreased followed by an increase. The SEM showed that the protease destroyed the threedimensional network structure of the gel to an extent.

Abstract:In order to study the effects of different thawing methods on the quality of Nemipterus virgatus,0 ℃ water bath,4 ℃ refrigerator defrosting,20 ℃ water soaking thawing and 0 ℃ ultrasonic thawing (160 W,280 W,400 W) were individually used to thaw Nemipterus virgatus that was stored at -20 ℃. Thawing loss rate,cooking loss rate and textural properties were determined. Meanwhile，differential scanning calorimetry (DSC) was used to study protein thermal stability. Raman spectra was used to analyse to protein secondary structure. Microstructure of muscle tissue was observed by optical microscope. The results indicated that the thawing loss rate of Nemipterus virgatus thawed in 4 ℃ refrigerator was the lowest,followed by 0 ℃ ultrasonic (280 W) thawing. After thawing in 0 ℃ ultrasonic (280 W),the microstructure of Nemipterus virgatus was greatly maintained,the protein showed good thermal stability,and the secondary structure of myofibrillar protein changed little. Although protein thermal stability and textured property of Nemipterus virgatus after the 0 ℃ ultrasonic (400 W) thawing were the best,myofibrils were severely broken and the gap of the muscle fiber bundle in microstructure became bigger due to excessively high power ultrasonic waves. Among 4 kinds of thawing methods comprehensively,0 ℃ ultrasonic (280 W) thawing could maintaine the quality of Nemipterus virgatus and exert the least damage to Nemipterus virgatus muscle. It is a recommended method for rapid thawing Nemipterus virgatus.

Abstract:The fish pastepork composite sausage with frying flavor was prepared by air frying and its formula was optimized,in which pork and fish paste were used as raw materials,soy protein isolate and potato starch were used as excipients. The results showed that fish bone in the whole fish paste formed a certain bone fragrance under the hot air. But excessive addition of fish paste caused grittiness. The gel properties of the product exhibited an increasing trend followed by declining with increasing fish paste addition. Appropriate addition of fat could significantly improve the taste of the product,and promote the formation of frying flavor of the composite sausage. Soy protein isolate and potato starch could improve the breaking force and deformation of the composite sausage,but excessive addition would reduce the sensory quality of the product. Adding compound phosphate could improve the breaking force and help to obtain a more uniform texture. Taking the gel properties and taste into consideration,water should not be added too much. The optimized formula of fish pastepork composite sausage with frying flavor was as following:20% fish paste,20% fat,10% soy protein isolate,14% potato starch,0.5% compound phosphate and 60% water.

Abstract:Fish bone soup was made from silver carp backbone sequentially by hightemperature cooking,enzymatic hydrolysis,vacuum concentration,filling and sterilization. Effects of protease type (neutral protease,alkaline protease,flavor protease and papain) on nitrogen yield,basic composition,peptide content,color,appearance and taste characteristics of the fish bone soup were investigated by atomic absorption spectrophotometer,colorimeter and Enose device,etc. The results showed that,the nitrogen yield,free amino acid content,calcium content and peptide (＜3 ku) content of fish bone soup prepared by enzymatic hydrolysis were significantly higher than those of the blank sample (without enzyme) (P＜0.05). The four indicators of the fish bone soup prepared by flavor protease were the highest,which increased by 46.61%,3 478.88%,233.40% and 56.25%,respectively,compared with the blank sample. The fish bone soup prepared by the flavor protease was deep yellow. Color parameter of b* value was the highest for the fish bone soup prepared by flavor protease (3.24),followed by the samples treated by the other three proteases (2.861.72),and then the blank sample. Principal component analysis (PCA) showed that there were significant differences in the taste characteristics of the five fish bone soups. The fish bone soup prepared by the flavor protease had the strongest umami taste and the weakest bitter taste. Overall,the fish bone soup prepared by the flavor protease has the best nutrition,appearance and taste quality.

Abstract:The knockout and overexpression mutants of OsCPK12 were constructed with reverse genetics. The plant height,root length and leaf phenotype of the overexpressed lines was much better than that of the wild type under the 150 mmol/L NaCl treatment. The plant height of knockout mutants was shorter,the root development were affected,and the leaves were withered and yellow compared with the wild type,indicating that OsCPK12 had positive regulation effect on rice salt tolerance. The results of the expression level of hormone signal transduction pathway genes in different tissues of mutant lines analyzed by realtime PCR showed that expression of multiple hormone receptor coding genes and downstream regulatory genes in the overexpression lines were significantly upregulated compared with the wildtype. It is indicated that OsCPK12 was involved in signal transduction of hormones,which affected rice stress response. Subcellular localization of OsCPK12 was done by fusion expression of target protein with fluorescent protein to further characterize the gene function of OsCPK12 and explain the mechanism. OsCPK12 was proved to be mostly located in the plasma membrane,laying the foundation for further research. Two water channel proteins,OsPIP11 and OsPIP27 were screened from Zhonghua 11’s membrane protein library and its interaction with OsCPK12 was further confirmed with yeast twohybrid test. Results indicated that OsCPK12 may interact with OsPIP11 and OsPIP27 and regulate the entry and exit of water molecules which improve the rice salt tolerance.

Abstract:Genetic linkage map based on classical molecular marker platforms with low density cannot meet the requirements for wheat functional genomics studies due to its huge and complex genome. 148 recombinant inbred lines (RILs) derived from the crossing Sujata (Indian wheat variety) with Avocet (Australia wheat variety) were used to construct the highdensity genetic linkage map with 6 397 genotypingbyseqencing(GBS) markers,705 DArTarray markers and 164 simple sequence repeat (SSR) markers. 21 chromosomes were covered by 25 linkage groups with a total length of 6 104.4 cM. It will provide an important resource for QTL mapping,mapbased cloning and marker assisted selection in wheat breeding.

Abstract:A new technology called sugarfree tissue culture technology was used to increase the quality of potato testtube seedlings and optimize the production,and to improve the technical system of virusfree seed potato breeding. The virusfree testtube seedlings of earlymaturing potato cultivar “Huashu 1” and the traditional MS medium with 4% sucrose was used as the test and control (CK) to compare two different culture methods. The effects of different media,supports and inoculation methods on the growth and development of potato plants in sugarfree tissue culture were studied. The results showed that the testtube seedlings under sugarfree tissue culture grew faster and were more robust,and had more advantages in the production of virusfree potato seedlings compared with the traditional tissue culture. Under sugarfree tissue culture conditions,further removal of organic components from MS medium,only containing inorganic components,had no significant impact on the growth of virusfree seedlings,but more effective in reducing pollution. The results of using vermiculite as support instead of agar showed that the virusfree seedlings supported by vermiculite grew faster,had longer internodes and showed signs of “elongation”. The results under the condition of vermiculite as support culture showed that the seedling growth of doublesegment cutting was significantly better than that of singlesegment cutting. The survival rate of doublesegment cutting was higher,and the segment was larger and easy to operate. The testtube seedlings under sugarfree tissue culture were further cutting into the net room to produce minitubers,of which the number and size had no significant changes compared with that from testtube seedlings under the traditional sugar culture. The new sugarfree tissue culture technology shortens the cultivation period of potato seedlings,reduces the production cost,simplifies the cutting propagation procedure of minituber production. It will lay a foundation for the realization of mechanized cutting of potato seedlings.

Abstract:Trifoliate orange and Carrizo citrange are two rootstocks with different zinc (Zn) absorption potential.Newhall navel oranges (N)/Carrizo citrange orange (C,Citrus sinensis Osb.×Poncirus trifoliata Raf.) grafted seedlings (N/C) and N/C inarched with trifoliate orange (P.trifoliata (L.) Raf.,N/Ct) cultivated in Zn deficient condition for 12 months before treatments,and then resupplied with 0.001 mg/L (deficient,control) and 0.05 mg/L (Zn resupply,adequate) Zn in sand culture for 5 months were used to study the effects of Zn resupply on the growth and Zn nutrient absorption of Zn deficient Newhall navel orange inarched with trifoliate orange.The results showed that the dry weight of new leaves and scion stems of inarched plants was higher than that of noninarched plants either with Zn resupply or Zn deficient treatment.The Zn concentration and content of leaves were not higher in the inarched plants compared with the noninarched plants under Zn deficient condition.However,the Zn concentration of the old leaves and roots of inarched plants was significantly higher than that of the noninarched plants,and the Zn accumulation of new leaves of inarched plants was significantly higher than that of noninarched plants under Zn resupply condition.Zn resupply significantly increased the Zn concentration and content of inarched plants,and significantly increased the Zn content of noninarched plants.The potassium concentration in new leaves of inarched plants was significantly higher than that of the noninarched plants,and the calcium concentration in the roots of the original rootstock was significantly higher than that of the noninarched plants under Zn deficient condition.The potassium concentration of the new leaves was not significantly different between inarched plants and noninarched plants under Zn resupply condition.The calcium concentration of the new leaves of inarched plants was significantly lower than that of noninarched plants,but there was no significant difference in the calcium concentration of the original rootstocks between inarched plants and noninarched plants.Zn resupply significantly reduced the boron concentration in the new leaves and roots of the plants.

Abstract:A onfarm experiment of potassium (K) fertilizer oneoff application was conducted in Jingzhou City,Hubei Province from 2017 to 2018. The aim was to assess the K rate on yield,K apparent balance,K efficiency of ricerapeseed rotation in Jianghan Plain,and combined with the fertilizer efficiency model to clarify the appropriate amount of K fertilizer. The results showed that the application of K fertilizer could significantly increase the yield of rice and rapeseed,the dry matter amount and K uptake of the aboveground,where the increasement came from the density,number of kernels,seed setting rate of rice and density,number of 1st branches and pods of rapeseed. When the K fertilizer input (K2O) reached 360 kg/hm2 per year,the K apparent balance in the rotation was still negative,and the deficit was 85.4 kg/hm2 without straw returning. On the contrary,the annual K balance of farmland could be achieved positively by inputting 90 kg/hm2 K fertilizer with straw incorporation. Compared with no K fertilizer application,the agronomic K fertilizer efficiency (KfAE) of rice and rapeseed applied with K fertilizer were 10.6 kg/kg and 2.9 kg/kg,where the K fertilizer recovery efficiency (KfRE) of those were 45.5% and 54.1%,respectively,indicating that the yield production of K fertilizer applied to direct seeding rice was significantly higher than that of rapeseed,and it also reflected from the side that rapeseed was more dependent on external K fertilizer than rice. Considering the input of straw K,the K efficiency (KAE and KRE) in rice season was consistent with that of KfAE and KfRE,while the KAE and KRE in rape season were 2.1 kg/kg and 38.5%,which were significantly lower than that of KfAE and KfRE. The comprehensive linear plus platform model and the K apparent balance of farmland showed that the suitable K fertilizer rate for direct seeding rice and rapeseed were 62.31 kg/hm2,70.18 kg/hm2 and yield for 10 066 kg/hm2,2 182 kg/hm2 under straw returning,respectively,which was lower than the recommended K fertilizer amount of 90 kg/hm2 at an average of 44.4% and 28.2%. The result indicated that direct seeding rapeseed required more K fertilizer to support population growth. Therefore,in view of the differences in crop growth and nutrient requirements under direct seeding and transplanting methods,the management of direct seeding nutrients should be lightly simplified according to agricultural production to improve crop yield,nutrient utilization and economic benefits.

Abstract:The active endophytic fungi from the mangrove Bruguiera sexangula were screened with secondary combination screening model combining chemical and biological activities. The Pestalotiopsis sp. was obtained,from which four steroids were isolated and identified. The four compounds were identified as 3βEferuloyllupeol,stigmastan3one,βsitosterol,sitost5en3βol acetate based on spectral data and literature comparison. Among them,3β(E)feruloyllupeol was first isolated from the mangrove endophytic fungus. The four compounds were tested for DPPH,ABTS free radical and antibacterial activity. The results showed that all compounds had no antibacterial and antioxidant activities.

Abstract:Postharvest diseases of citrus caused by pathogenic fungi make great losses to citrus industry. Dynamics of postharvest diseases of nine different kinds of citrus fruit from 14 areas during storage were investigated and the pathogens were identified. The results showed that green/blue mold,sour rot,stemend rot,anthracnose and black rot were observed. The green/blue mold was the main disease. Green/blue mold is dominant on mandarins and sour rot is common on sweet oranges. The incidence of postharvest disease after 60 days’ storage is closely correlated with the rainy day during the one week before harvest. Therefore,harvesting on sunny days is beneficial to reduce the incidence of postharvest diseases. It is indicated that more targeted postharvest treatments can be taken according to different types of citrus varieties based on their main disease types.

Abstract:In this paper,the parasitoid of Bactrocera minax was first recorded in China. Morphological and molecular identification and biological characterization were carried out. The results showed that the chest and the abdomen of the parasitoid of Bactrocera minax were mostly black. Vein mcu of fore wing juse postfurcal,and the antennae were 6367 knots. The the middle tibia and tarsus were orangeyellow,the hind leg was black,and the mesothorax had obvious “V” pattern. Results of further analyzing the NJ phylogenetic tree of COI gene and 28sRNA gene revealed that the parasitic wasp was closely related to Diachasmimorpha longicaudata,Diachasmimorpha kraussii,Diachasmimorpha tryoni. Under natural conditions,the emergence period of parasitoid was significantly longer than that of B. minax. The proportion of emerged females increased with the rise of temperatures. Combined with its morphological characteristics,it was named as Chinese citrus fly cocoon wasp (Diachasmimorpha feijeni).

Abstract:Microsatellites were firstly screened in the Siniperca chuatsi gonadal transcriptome obtained by highthroughput sequencing. A total of 4 986 sequences,which contained microsatellites and could be designed with primers were obtained. Twenty seven (11.30%) out of 239 microsatellite loci were proved to be polymorphic in 12 S. chuatsi populations. The number of alleles per locus ranged from 2 to 8 (5.63±1.84),the effective number of alleles per locus ranged from 1.86 to 6.80 (3.99±1.56),the observed heterozygosity per locus ranged from 0.21 to 0.78 (0.49±0.16),the expected heterozygosity per locus ranged from 0.46 to 0.85 (0.71±0.12),the polymorphic information content per locus ranged from 0.37 to 0.84 (0.66±0.15),and the gene flow per locus ranged from 0.11 to 2.14 (0.67±0.45). The number of alleles and the effective number of alleles per locus in the Jiayu population were the highest among 12 populations. The observed heterozygosity and the expected heterozygosity per locus in the Wuhan population were the highest. The Nei’s genetic distance ranged from 0.103 0 to 1.511 7,the Nei’s genetic identity ranged from 0.220 5 to 0.902 2. The maximum Nei’s genetic distance (1.511 7) and the minimum Nei’s genetic identity (0.220 5) were between the Fuyuan population and Shunde population. The minimum Nei’s genetic distance (0.103 0) and the maximum Nei’s genetic identity (0.902 2) were between the Fuyuan population and Shunde population. UPGMA cluster analysis showed that one branch of the Pearl River system and the other branch of the Yangtze River system gathered firstly and then converged with the branch of the Heilongjiang River. The genetic differentiation coefficient FST among the 12 groups was 0.041 80.611 0,and the genetic differentiation among the groups reached the significant level (P＜0.05).The minimum FST (0.041 8) was between the Liangzihu population and Wuhan population,and the maximum FST (0.611 0) between the Shunde population and Fuyuan population. AMOVA analysis showed that the genetic variation among populations accounted for 33.14%,and the genetic variation within populations was 66.86%. Structure analysis showed that 12 populations were divided into 5 subpopulations. This study could provide useful basic data for protection of germplasm resources and variety breeding in S. chuatsi.

Abstract:he stress response of Pomacea canaliculata to molluscicide metaldehyde at proteomic level was analyzed in this study,which lays a foundation for future study of the molecular mechanism of resistance to drugs in snail. Proteome of the P. canaliculata liver was studied using the isobaric tags for relative and absolute quantitation (iTRAQ) technology. The results showed that 108 differentially expressed proteins (P＜0.05) with quantitative information were identified,of which 55 were significantly upregulated and 53 were downregulated. The physical and chemical properties analysis and GO (gene ontology) annotation analysis showed that these proteins could be functionally categorized into antioxidant,catalytic and antibacterial functions,affecting the cellular structure composition,muscle contraction,metabolic regulation and immunoregulation and causing neurotoxicity of snail. All the 57 Cytochrome P450 were found to show different expression activity,suggesting that CYP450 may contribute to metaldehyde resistance of P. canaliculata.

Abstract:In this study,the optimum fermentation strain was selected from four strains with excellent ability of fermenting soybean meal (Bacillus subtilis,Saccharomyces cerevisiae,Rhizopus oryzae,Penicillium chrysogenum),and crude protein content and soybean peptide content were taken as evaluation criteria to optimize the fermentation process conditions. The nutrient content and the changes of antinutrition factors were analyzed before and after solidstate fermentation of soybean meal. The results showed that B. subtilis B8 and R. oryzae M1 were the optimal combination of fermented strains. The optimum fermentation process conditions of compound fermentation were:B. subtilis and R. oryzae were simultaneously introduced into soybean meal,the inoculation ratio of two strains was 2∶1,the total inoculum of fermentation was 10%,the fermentation temperature was 40℃,the ratio of feed to water was 1.0∶1.4,and the fermentation time was 96 hours. After compound fermentation of soybean meal,the content of soybean peptide,crude protein,crude ash and crude fat in the fermentation product was significantly higher than that before fermentation (P＜0.05)，the moisture content decreased significantly (P＜0.05),the macromolecular protein was basically degraded below 10 ku,and glycinin,βconglycinin and trypsin inhibitor was significantly lower than that of unfermented soybean meal (P＜0.05). The above results indicated that the nutrient composition of soybean meal increased significantly and the antinutritional factors decreased significantly after the compound fermentation，which means that the nutritional quality of soybean meal was improved a lot.

Abstract:In response to the mechanized sowing of winter rapeseed,the seedbed was soiled with soil,and the design and test of seedbed subsoiling and rotating device for rapeseed combined planter was carried out.The technical scheme of combined seedbed with shallow pine and rotary tillage was put forward.In order to solve problems mentioned above,the rational cultivation of the seedbed based on vertical tillage was explored.A seedspinning device for rapeseed was designed with subsoiling rotating tillage combined operation technology and used in the combination with direct seeding machine.A subsoiling shovel for deepening the seedbed strip with deep loosening was developed according to the principle of soil sliding and seedspinning device for rapeseed.The main structural and technical parameters of the device were analyzed and determined.2BYM6/8 direct rapeseed seeder with a working width of 2 000 mm and the subsoiling shovel was used as the main working part.To improve the quality of the seedbed strip,IT245 rotary blade was used for cutting the area of seedbed strip or the area used to grow the crop while IT225 for cutting the area of nonseedbed strip.The layout of the subsoiling shovel arranged in the form of “Four in the front and two in the back”.The performance of seedbed strip was tested in the field.The results showed that the depth of the seedbed strip ranged from 229.4 mm to 239.4 mm,while the depth of the seedbed ranged from 124.8 mm to 139.2 mm.Its depth stability coefficient was more than 90%,with seedbed roughness ranging from 25.71 mm to 27.14 mm.The working effect meets the requirements of design and the sowing agronomy of rapeseed.

Abstract:In the middle and lower reaches of the Yangtze river,the soil is sticky and amount of rice straw is large,which will cause machine to be blocked by soil or entangled by straw.In order to solve this problem,a combined tillage machine composed of buckle plough,rotary tillage and parts for furrowing,which can cover the straw with the plough,break soil up with rotary tillage and ditch furrow with the plough at the back,was designed.According to the law of soil movement,the key parameters of plough surface including guide curve,straight element angle,tail length of plough surface,and the structural parameters including number and distance of plough were determined.Results of field test showed that traction resistance of machine increased by 23.7% and the power consumption increased by 57.2% when the working speed increased from 3.3 km/h to 4.2 km/h.Traction resistance and power consumption increased when speed increased.Due to the addition of plough,the total power consumption of machine increased by 12.3% and 20.7% compared with the rotary tillage when the speed of the machine was 3.3 km/h and 4.2 km/h under the same operating depth of rotary tillage.The machine worked better even though the power consumption was increased.Compared with the rotary tillage,the average soil crushing rate of the combined machine,the average surface flatness after tillage,the average straw coverage rate was 92.8%,11 mm,and 92.9%,respectively and increased by 2.6%,39.0%,and 22.2%,respectively.All performance parameters of the machine meet the agronomic requirements of rapeseed sowing.

Abstract:The automatic navigation of the combine harvester can reduce intensity of drivers and improve the quality and efficiency of harvester operation. Converting the traditional hydraulic steering system of existing combine harvester into electronic control hydraulic steering system is the prerequisite to realize the automatic navigation of combine harvester. However,after the refit of electronic control hydraulic circuit. It has the characteristic of complex structure of steering system,time delay of electronic control dynamic response and nonlinearity of control system,which is not conducive to the accurate design of followup navigation controller. In order to realize automatic navigation control and steering characteristic test of the wheeled combine harvester,an electrically controlled hydraulic steering test system has been set up in this thesis. The abovementioned system is mainly composed of electrically controlled hydraulic steering valve set,industrial control computer,control box and steering angle measuring equipment. To further obtain the steering characteristic test of the wheeled combine harvester,the static test on the concrete and curve fitting are carried out for the relation between the expansion of hydraulic cylinder and the angle of steering wheel which determined the steering control voltage range of electrically controlled hydraulic steering.The different control voltages correspond to the steering velocity of wheel and the dynamic response process of square wave control signal. The relationship between input signal amplitude and retardation time,steadystate response time,residence time is analyzed. After the combined harvesting electromechanical control hydraulic steering characteristic test,the modified combine harvester realized fast and stable electrohydraulic steering control. The electrohydraulic steering control system has an asymmetric control voltage dead zone. When the proportional valve opening amount is equal,that is,the control voltage is the same,the steering wheel has different steering speeds,and the oneway rotation speed is approximately linear with the valve opening increment. The transient response process of the electronically controlled hydraulic steering consists of a delay link,an integral link and a secondorder oscillating link. It is mainly affected by the internal friction damping of the valve core,the spool return spring and the response delay of the electrical signal,and its transient response characteristics and power. The control hydraulic steering speed relationship basically conforms to the characteristics of the electrohydraulic proportional valvecontrolled asymmetric hydraulic cylinder system. Static test on the concrete revealed：the steering angle of the steering wheel is approximately linear with the expansion of hydraulic cylinder,the regression determination coefficient is greater than 0.99 and the root mean square error is 0.25. The steering angle of the steering wheel is from -29.76 ° to 30.23°. Dynamic test in the field revealed:the dead zone voltage range accounts for 32% of the control voltage range;When the steering wheel is in steady motion,the steering rate of steering wheel is approximately linear with steering control voltage; the system has a transient state response process,and the average retardation time is 90 ms,steadystate response time is from 150 ms to 200 ms,steadystate response angle is from 0.21° to 2.77°,the residence time is from 25 ms to 77 ms,the stagnant angle is from 0.10 ° to 1.24 °. The design of the subsequent navigation controller is usually carried out by establishing the transfer function or dynamic model of the steering system. However,due to the combined operation of the combine harvester in the field,the hydraulic cylinder load force is affected by the total weight of the harvester and the relationship between the tire and the soil. The influence of spring stiffness variation and different viscous damping forces,the establishment of complex and unique system models often can not meet the actual needs,so the approximate linearization of the combined harvesting electromechanical hydraulic steering system and the test of the transient response time distribution in each period can provides practical parameter support and adaptability research basis for the design of the combine harvester navigation controller.

Abstract:In view of the complex terrain of the mountain orangery and the difficulty of working on the cutterhead,an orange garden profile mower cutter was designed. The cutter adopted a freeswinging knife design and had an obstacle avoidance function to reduce the damage which the knife is injured by the obstacle of orange garden. The logarithmic spiral function model of the file blade was established by theoretical analyses and optimization design. The multifactor test analysis of the cutter was carried out with bench test. The optimal combination of parameters including the cutter disk speed of 1 900 r/min,the blade length of 72 mm,the blades number of 4 were obtained with comprehensive scoring method. The verification test was carried out to verify the rationality and effectiveness of the test. Compared with the optimal value in the orthogonal test group,the peak torque decreased by 0.38%,and the uniformity of one cut increased by 5.43%. The test achieved the expected results and met the requirements for weeding in mountain citrus orchards.

Abstract:In order to improve the identification ability of the fish meal quality detection device,the response characteristic information (10×6) of the fish meal sample is extracted to form the original feature matrix,and the multifeature data fusion optimization of the sensor array is carried out by taking the identification accuracy of the multilayer perceptron neural network as the evaluation index. Firstly,through different normalization processing,the best normalization processing method is obtained. Secondly,1 770 characteristic distances are calculated by factor load analysis results,and 1 770 distances are sorted according to the order from small to large. According to the Euclidean distance between the eigenvalues and the origin,19 eigenvalues with smaller Euclidean distance are eliminated to obtain the highest discriminant accuracy. The original eigenvalues optimized by load analysis are correlated and sorted according to the absolute sum and size of correlation coefficients. When 8 eigenvalues are removed when the absolute sum of correlation coefficients is greater than 37.2,the recognition accuracy is 98.3%,and the feature subset is more compact. The results showed that the characterization characteristics of the sensor signals changed obviously before and after feature optimization. 33 eigenvalues were used to characterize the sensor characteristic signals of fish meal samples. At the same time,the reliability of MLP neural network identification results is explained by Mahalanobis distance,which further explains the rationality of feature optimization method.

Abstract:The CFD based droplet trajectory and deposition model were established to study the droplet deposition characteristics and the influence of air supply direction on droplet movement in the sprayer. The relevant parameters of the sprayer were measured. Twodimensional spray flow model was established and the parameters of the model were determined. The droplet deposition on vertical section at different distances from sprinkler head was simulated. Validation test was conducted under the same conditions as the simulation. The results showed that the droplet deposition characteristics fitted well with the results tested. The increase of air supply angle had little effect on droplet drift within the range of 1.0 m from the sprinkler head. With the increase of the distance from the sprinkler head,the influence of air supply angle on the drift loss of fog droplets at the bottom increased gradually. The simulation results deviated greatly from the actual test results when the range of the sprinkler head exceeded the 1.0 m,but the rule of decreasing droplet deposition gradually with the increase of distance from sprinkler head was consistent.