Load of an automatic feed mechanism is composed of the stretching force of feed belt at the entrance to lower flexible guidance and the friction force between feed belt and flexible guidance. A mathematical model for ...Load of an automatic feed mechanism is composed of the stretching force of feed belt at the entrance to lower flexible guidance and the friction force between feed belt and flexible guidance. A mathematical model for computing the load was presented. An optimization problem was formulated to determine the attitude of the flexible guidance based on the principle that the potential energy stored in the system was the minimum at the equilibrium. Then the friction force was obtained according to the attitude of guide leaves and the moving velocity of the feed belt and the friction factor. Consequently, the load of the automatic feed mechanism can be calculated. Finally, an example was given to compute the load when the horizontal and elevating firing angles of the automation were respectively 45° and 30°. The computing result can be a criterion to determine the designing parameters of automat.展开更多
A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system(CFS) of trench cutter(TC) in the presence of unknown external disturbances.The feeding pressure control of ...A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system(CFS) of trench cutter(TC) in the presence of unknown external disturbances.The feeding pressure control of CFS is subjected to unknown load characteristics of rock or soil; in addition,the geological condition is time-varying.Due to the complex load characteristics of rock or soil,the feeding velocity of TC is related to geological conditions.What is worse,its dynamic model is subjected to uncertainties and its function is unknown.To deal with the particular characteristics of CFS,a novel adaptive fuzzy integral sliding mode control(AFISMC) was designed for feeding pressure control of CFS,which combines the robust characteristics of an integral sliding mode controller and the adaptive adjusting characteristics of an adaptive fuzzy controller.The AFISMC feeding pressure controller is synthesized using the backstepping technique.The stability of the overall closed-loop system consisting of the adaptive fuzzy inference system,integral sliding mode controller and the cutter feeding system is proved using Lyapunov theory.Experiments are conducted on a TC test bench with the AFISMC under different operating conditions.The experimental results demonstrate that the proposed AFISMC feeding pressure controller for CFS gives a superior and robust pressure tracking performance with maximum pressure tracking error within ?0.3 MPa.展开更多
Feeding rhythm of common carp was investigated from 4℃ to 34℃. The results indicated that there was a diel feeding rhythm for both adult （630-850 g） and youth （61-91 g） at all tested temperatures. There were two...Feeding rhythm of common carp was investigated from 4℃ to 34℃. The results indicated that there was a diel feeding rhythm for both adult （630-850 g） and youth （61-91 g） at all tested temperatures. There were two main activity peaks at 8：00-11：00 a.m. and 19：00-23：00 p.m., during which feeding quantities were 10.68%-32.53% and 16.25%-33.41% of the daily intake, respectively. When water temperature dropped to below 10℃, the feeding peak concentrated at 8：00-11：00 a.m. and 19：00 p.m. to 4：00 a.m. At 6℃, though both adult and youth would still feed, the feeding quantities were only 0.01% and 0.35% of body mass. Daily feeding rate of adult and youth reached 1.21% and 2.63% at 14℃, respectively. Both adult and youth carps reached the maximum daily feeding rate at 28℃, being 2.84% and 12.06% of body mass, respectively. The daily feeding rate of adult and youth reduced suddenly after at 34℃, and the daily feeding rate was only 0.74% and 9.45% of body mass, respectively. There was significant difference in daily feeding rate at different water temperatures （P〈0.05）.展开更多
A method was developed for the simultaneous determination of four kinds of estrogens （hexoestrol, diethylstilbestrol, estrone, and 17-beta-estradiol） in feed by gas chromatography-mass spectrometry （GC-MS）. After ...A method was developed for the simultaneous determination of four kinds of estrogens （hexoestrol, diethylstilbestrol, estrone, and 17-beta-estradiol） in feed by gas chromatography-mass spectrometry （GC-MS）. After the sample was extracted by ethyl ether and cleaned-up on HLB phase extraction column, four kinds of estrogens were derived and quantified in gas chromatographymass spectrometry. The results showed that the linear detectable ranged from 2.5 ng· mL-1 to 250 ng· mL-1for hexoestrol and from 5 ng· mL-1 to 500 ng· mL-1 for three other estrogens with the correlation coefficients （R2） were no less than 0.990. The recoveries were in the range of 76.34%-96.33% and the relative standard deviation was no more than 22.7%. The limits of quantitation （LOQ） for all analytics were between 10 ug· kg^-1 and 20 ug· kg^-1. The method was accurate and sensitive and could meet the actual requirements for the analyses of feed samples.展开更多
In order to acquire the flow pattern and investigate the settling behavior of the red mud in the separation thickener,computational fluid dynamics(CFD),custom subroutines and agglomerates settling theory were employed...In order to acquire the flow pattern and investigate the settling behavior of the red mud in the separation thickener,computational fluid dynamics(CFD),custom subroutines and agglomerates settling theory were employed to simulate the three-dimensional flow field in an industrial scale thickener with the introduction of a self-dilute feed system.The simulation results show good agreement with the measurement onsite and the flow patterns of the thickener are presented and discussed on both velocity and concentration field.Optimization experiments on feed well and self-dilute system were also carried out,and indicate that the optimal thickener system can dilute the solid concentration in feed well from 110 g/L to 86 g/L which would help the agglomerates' formation and improve the red mud settling speed.Furthermore,the additional power of recirculation pump can be saved and flocculants dosage was reduced from 105g/t to 85g/t in the operation.展开更多
A series of studies were conducted to establish a methodology for the accurate and efficient determination of canthaxanthin in feed ingredients. Agilent ZORBAX Eclipse DB-C 18 analytical column （4.6×150 mm, 5μm...A series of studies were conducted to establish a methodology for the accurate and efficient determination of canthaxanthin in feed ingredients. Agilent ZORBAX Eclipse DB-C 18 analytical column （4.6×150 mm, 5μm） was used and kept at 25 ℃. The mobile phase was acetonitrile ： methanol （v/v）=95 ： 5, and eluted compounds were detected by DAD absorbance （470 nm）. The flow rate was maintained at 1.0 mL·min^-1. The response of the method was linear over the range 1.0-20.0 μg·mL^-1 canthaxanthin assay solution （R^2=0.9998）. Recovery assays done with standard canthaxanthin to feed ingredient resulted in an average recovery of 103%. Variation coefficient was less than 3.53%. This method is proved to be simple, precise, sensitive and reproductive.展开更多
In the paper, a method of building mathematic model employing genetic multilayer feed forward neural network is presented, and the quantitative relationship of chemical measured values and near-infrared spectral data ...In the paper, a method of building mathematic model employing genetic multilayer feed forward neural network is presented, and the quantitative relationship of chemical measured values and near-infrared spectral data is established. In the paper, quantitative mathematic model related chemical assayed values and near-infrared spectral data is established by means of genetic multilayer feed forward neural network, acquired near-infrared spectral data are taken as input of network with the content of five kinds of fat acids tested from chemical method as output, weight values of multilayer feed forward neural network are trained by genetic algorithms and detection model of neural network of soybean is built. A kind of multilayer feed forward neural network trained by genetic algorithms is designed in the paper. Through experiments, all the related coefficients of five fat acids can approach 0.9 which satisfies the preliminary test of soybean breeding.展开更多
The functionally graded thermal barrier coatings （FG-TBCs） with 80%ZrO2-13%CeO2-7%Y2O3 （C-YSZ）/NiCoCrAlY were prepared using a recently developed supersonic plasma spraying（S-PS） with dual powder feed ports syst...The functionally graded thermal barrier coatings （FG-TBCs） with 80%ZrO2-13%CeO2-7%Y2O3 （C-YSZ）/NiCoCrAlY were prepared using a recently developed supersonic plasma spraying（S-PS） with dual powder feed ports system. The thermal shock experiment of FG-TBCs specimens was carried out by means of the automatic thermal cycle device, in which the samples were heated to 1200℃ by oxygen-acetylene flame jet then water-quenched to ambient temperature. The temperature—time curves of specimens and photographs can be watched on-line and recorded by a computer during the test. The results show that the totally 1mm-thick FG-TBCs have excellent thermal shock resistance due to the fact that the coatings have no any peeling-off after 200 thermal cycles. The microstructures and morphologies of FG-TBCs were characterized and analyzed by SEM.展开更多
In many cases, the cutting method is usually adopted for the efficient machining of non-circular body of revolution and a feed drive is needed to actuate the cutting tool to and fro according to input signal wave. The...In many cases, the cutting method is usually adopted for the efficient machining of non-circular body of revolution and a feed drive is needed to actuate the cutting tool to and fro according to input signal wave. The feed drive for the purpose is required of fast response and accurate positioning. Both of these are highly dependent upon the actuating elements. Several schemes of actuation are specially interested. One is the introduction of piezoelectric actuation. However, the tiny working stroke of the piezoelectric material limits its application to a narrow range. Another is the application of electro-magnetic actuator. An innovative feed drive actuated by the stepper motor is introduced for the purpose. For a conventional step operating mode, a stepper motor can only be controlled to position at finite discrete points. Thus, when it is applied as an actuator of the feed drive, it is very difficult to maintain high accuracy and fast response. To eliminate quantitative error, the stepper motor is controlled under the continual mode. It is achieved with a micro-controller system and a built-in control algorithm program, called "tracking algorithm". Within each sampling cycle, the micro-controller will sample the input signal and the time interval will be divided into two parts according to the relative position between two adjacent stepping points. The phase coils correspondent to the two adjacent stepping points are energized respectively with calculated time duration. In the way, the motion of the tool frame smoothly tracks the input signal. This paper presents modeling and identification of frequency response of the proposed drive. The dynamic response of the feed drive is manly decided by the natural frequency of the stepper motor. For the conventional small-size stepper motors, the natural frequency is within the range 200～400 Hz. Experimental results show that the stepper motor actuated tool frame can smoothly keep in track of the input signal wave under "tracking control". The bandwidth of frequency of the feed drive exceeds 310 Hz.展开更多
Optimal glucose feed strategy for glycerol fed-batch fermentation was investigated by Pontryagin’s maximum principle to maximize the final glycerol yield. The problem was solved by a nonsingular control approach by s...Optimal glucose feed strategy for glycerol fed-batch fermentation was investigated by Pontryagin’s maximum principle to maximize the final glycerol yield. The problem was solved by a nonsingular control approach by selecting the culture volume as the control variable, then the general optimal feed profile was numerically determined.展开更多
Blaptostethus pallescens Poppius (Heteroptera:Anthocoridae),which is amenable to mass rearing,has proved to be a potential predator of sucking pests like mites and thrips.Recently,the cotton mealybug Phenacoccus solen...Blaptostethus pallescens Poppius (Heteroptera:Anthocoridae),which is amenable to mass rearing,has proved to be a potential predator of sucking pests like mites and thrips.Recently,the cotton mealybug Phenacoccus solenopsis Tinsley emerged as a serious pest on cotton in India.Laboratory studies indicated that B.pallescens could feed on the cotton mealybug.Hence,further investigations were conducted to understand the stage of the predator which is most potential and the pest stage preferred by the predator.Mature nymphs and adults of B.pallescens could predate equally well on the neonates of cotton mealybug.Young (three to four-day-old) nymphs of the predator could not feed on any stage of the cotton mealybug.Mature nymphs (seven-day-old and above) and adults could effectively predate on both young and mature cotton mealybug crawlers,though preference was more for the younger crawlers.However,nymphs and adults of B.pallescens could not predate on the adult stage of the mealybug.Different predator:pest ratios were tested in cage studies and it emerged that B.pallescens adults released against the mealybug crawlers at a ratio of 1:5 and nymphal release at 1:10 caused maximum mortality of the mealybug crawlers.Considering the fast multiplication rate of cotton mealybug and the large number of predators which have to be released to manage them,further detailed studies are necessary on utilizing B.pallescens to target the neonates and younger stages of the cotton mealybug in field conditions.展开更多
Mortality is normal and natural in aquaculture experiments. However, it becomes a problem when measuring feed intake as a component of nutrient utilization parameters such as： feed conversion ratio, feed conversion e...Mortality is normal and natural in aquaculture experiments. However, it becomes a problem when measuring feed intake as a component of nutrient utilization parameters such as： feed conversion ratio, feed conversion efficiency, apparent net protein utilization, protein efficiency ratio and protein productive value. In order to accurately evaluate feed intake with due consideration of mortality encountered, a formulae was developed using empirical data obtained from an experiement that had mortality. The formulae Fwas： total feed consumed by numbers of survived fishes=DL∑i=1n（Fi/Ni）N. Where, D=Numbers of days fishes were fed within each period ibefore it was adjusted（e.g fortnight）, it was constant throught period of experiment; F=Uantity of feed fed per day for a fortnight before the quantity was adjusted, it changed every fortnight; L=Numbers of living fishes at the end of experimental period; N=Numbers of fishes at each weighing period, it might change every fortnight or might be constant if no mortality occurred; while n=Numbers of times fishes were weighed and quantity of feed was adjusted but this did not include the final weighing at the termination of experiment. However, if the fishes were weighed weekly, then D=6.展开更多
Four-factor and three-level orthogonal experimental design(L9(34))was used in the experiment.The effects of three genotypes:Germany SAB three-bred-cross rabbits(S2),New Zealand purebred(N),and crossbred rabbits(ON);th...Four-factor and three-level orthogonal experimental design(L9(34))was used in the experiment.The effects of three genotypes:Germany SAB three-bred-cross rabbits(S2),New Zealand purebred(N),and crossbred rabbits(ON);three levels of Clenbuterol treatment: 1 ng.g-1,2 ng.g-1and 3 ng.g-1,and three feeding methods:5-day,7-day and 10-day withdrawal period after two weeks of feeding Clenbuterol(CL)on bodyweight gain were evaluated.CL apparently improved average daily gain(ADG)of rabbits.70-day ADG of 5-day and 10-day withdrawal were higher than that of 7-day withdrawal,70-day ADG of S2 genotype was significantly higher than that of the control and N genotype was significant.Genotype,additive dose and feeding method had significant effects on overall-stage ADG.ON genotype,2 ng.g-1 dose and 5-day withdrawal feeding method was the best.Responses of different genotype to Clenbuterol appeared different at experimental prophase or whole experimental period.展开更多
On the basis of regressional relationship between nutritional indexes and technological conditions,when confronted with feed quality that contains multiple nutritional indexes,a comprehensive equation of evaluating fe...On the basis of regressional relationship between nutritional indexes and technological conditions,when confronted with feed quality that contains multiple nutritional indexes,a comprehensive equation of evaluating feed quality was developed by using fuzzy mathematical method at first in this study,and then the optimum technological conditions were established by introduction of statistical frequency analysis method pursuant to the comprehensive evaluating equation mentioned above compared with conventional multi-aim nonlinear programming,this method can lead to easy solutions,and also can make adjustment of the importance of nutritional indexes to feed quality according to practical considerations.An example was given of soybean extruding to show how the method worked.展开更多
The Wesel-Xanten stretch of the fiver Rhine between km-812.5 and km-821.5 is one of the reaches where strong erosion leads to high maintenance efforts conceming navigability.In order to improve the naviga- tion condit...The Wesel-Xanten stretch of the fiver Rhine between km-812.5 and km-821.5 is one of the reaches where strong erosion leads to high maintenance efforts conceming navigability.In order to improve the naviga- tion conditions without aggravating the flood protection,but also ensuring that the ecological system of the river is not damaged,investigations of the morphodynamical processes in connection with artificial grain feeding ac- tivities have to be carried out by Federal Waterways Engineering and Research...展开更多
基金Project supported by the Seventh Research Institute of China State Shipbuilding Corporation
文摘Load of an automatic feed mechanism is composed of the stretching force of feed belt at the entrance to lower flexible guidance and the friction force between feed belt and flexible guidance. A mathematical model for computing the load was presented. An optimization problem was formulated to determine the attitude of the flexible guidance based on the principle that the potential energy stored in the system was the minimum at the equilibrium. Then the friction force was obtained according to the attitude of guide leaves and the moving velocity of the feed belt and the friction factor. Consequently, the load of the automatic feed mechanism can be calculated. Finally, an example was given to compute the load when the horizontal and elevating firing angles of the automation were respectively 45° and 30°. The computing result can be a criterion to determine the designing parameters of automat.
基金Project(2012AA041801)supported by the High-tech Research and Development Program of China
文摘A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system(CFS) of trench cutter(TC) in the presence of unknown external disturbances.The feeding pressure control of CFS is subjected to unknown load characteristics of rock or soil; in addition,the geological condition is time-varying.Due to the complex load characteristics of rock or soil,the feeding velocity of TC is related to geological conditions.What is worse,its dynamic model is subjected to uncertainties and its function is unknown.To deal with the particular characteristics of CFS,a novel adaptive fuzzy integral sliding mode control(AFISMC) was designed for feeding pressure control of CFS,which combines the robust characteristics of an integral sliding mode controller and the adaptive adjusting characteristics of an adaptive fuzzy controller.The AFISMC feeding pressure controller is synthesized using the backstepping technique.The stability of the overall closed-loop system consisting of the adaptive fuzzy inference system,integral sliding mode controller and the cutter feeding system is proved using Lyapunov theory.Experiments are conducted on a TC test bench with the AFISMC under different operating conditions.The experimental results demonstrate that the proposed AFISMC feeding pressure controller for CFS gives a superior and robust pressure tracking performance with maximum pressure tracking error within ?0.3 MPa.
文摘Feeding rhythm of common carp was investigated from 4℃ to 34℃. The results indicated that there was a diel feeding rhythm for both adult （630-850 g） and youth （61-91 g） at all tested temperatures. There were two main activity peaks at 8：00-11：00 a.m. and 19：00-23：00 p.m., during which feeding quantities were 10.68%-32.53% and 16.25%-33.41% of the daily intake, respectively. When water temperature dropped to below 10℃, the feeding peak concentrated at 8：00-11：00 a.m. and 19：00 p.m. to 4：00 a.m. At 6℃, though both adult and youth would still feed, the feeding quantities were only 0.01% and 0.35% of body mass. Daily feeding rate of adult and youth reached 1.21% and 2.63% at 14℃, respectively. Both adult and youth carps reached the maximum daily feeding rate at 28℃, being 2.84% and 12.06% of body mass, respectively. The daily feeding rate of adult and youth reduced suddenly after at 34℃, and the daily feeding rate was only 0.74% and 9.45% of body mass, respectively. There was significant difference in daily feeding rate at different water temperatures （P〈0.05）.
基金Supported by Fund of Harbin Provincial Education Department(2014AB3BN041)
文摘A method was developed for the simultaneous determination of four kinds of estrogens （hexoestrol, diethylstilbestrol, estrone, and 17-beta-estradiol） in feed by gas chromatography-mass spectrometry （GC-MS）. After the sample was extracted by ethyl ether and cleaned-up on HLB phase extraction column, four kinds of estrogens were derived and quantified in gas chromatographymass spectrometry. The results showed that the linear detectable ranged from 2.5 ng· mL-1 to 250 ng· mL-1for hexoestrol and from 5 ng· mL-1 to 500 ng· mL-1 for three other estrogens with the correlation coefficients （R2） were no less than 0.990. The recoveries were in the range of 76.34%-96.33% and the relative standard deviation was no more than 22.7%. The limits of quantitation （LOQ） for all analytics were between 10 ug· kg^-1 and 20 ug· kg^-1. The method was accurate and sensitive and could meet the actual requirements for the analyses of feed samples.
基金Project(50876116)supported by the National Natural Science Foundation of China
文摘In order to acquire the flow pattern and investigate the settling behavior of the red mud in the separation thickener,computational fluid dynamics(CFD),custom subroutines and agglomerates settling theory were employed to simulate the three-dimensional flow field in an industrial scale thickener with the introduction of a self-dilute feed system.The simulation results show good agreement with the measurement onsite and the flow patterns of the thickener are presented and discussed on both velocity and concentration field.Optimization experiments on feed well and self-dilute system were also carried out,and indicate that the optimal thickener system can dilute the solid concentration in feed well from 110 g/L to 86 g/L which would help the agglomerates' formation and improve the red mud settling speed.Furthermore,the additional power of recirculation pump can be saved and flocculants dosage was reduced from 105g/t to 85g/t in the operation.
文摘A series of studies were conducted to establish a methodology for the accurate and efficient determination of canthaxanthin in feed ingredients. Agilent ZORBAX Eclipse DB-C 18 analytical column （4.6×150 mm, 5μm） was used and kept at 25 ℃. The mobile phase was acetonitrile ： methanol （v/v）=95 ： 5, and eluted compounds were detected by DAD absorbance （470 nm）. The flow rate was maintained at 1.0 mL·min^-1. The response of the method was linear over the range 1.0-20.0 μg·mL^-1 canthaxanthin assay solution （R^2=0.9998）. Recovery assays done with standard canthaxanthin to feed ingredient resulted in an average recovery of 103%. Variation coefficient was less than 3.53%. This method is proved to be simple, precise, sensitive and reproductive.
基金Heilongjiang Natural Science Foundation (F0318).
文摘In the paper, a method of building mathematic model employing genetic multilayer feed forward neural network is presented, and the quantitative relationship of chemical measured values and near-infrared spectral data is established. In the paper, quantitative mathematic model related chemical assayed values and near-infrared spectral data is established by means of genetic multilayer feed forward neural network, acquired near-infrared spectral data are taken as input of network with the content of five kinds of fat acids tested from chemical method as output, weight values of multilayer feed forward neural network are trained by genetic algorithms and detection model of neural network of soybean is built. A kind of multilayer feed forward neural network trained by genetic algorithms is designed in the paper. Through experiments, all the related coefficients of five fat acids can approach 0.9 which satisfies the preliminary test of soybean breeding.
文摘The functionally graded thermal barrier coatings （FG-TBCs） with 80%ZrO2-13%CeO2-7%Y2O3 （C-YSZ）/NiCoCrAlY were prepared using a recently developed supersonic plasma spraying（S-PS） with dual powder feed ports system. The thermal shock experiment of FG-TBCs specimens was carried out by means of the automatic thermal cycle device, in which the samples were heated to 1200℃ by oxygen-acetylene flame jet then water-quenched to ambient temperature. The temperature—time curves of specimens and photographs can be watched on-line and recorded by a computer during the test. The results show that the totally 1mm-thick FG-TBCs have excellent thermal shock resistance due to the fact that the coatings have no any peeling-off after 200 thermal cycles. The microstructures and morphologies of FG-TBCs were characterized and analyzed by SEM.
文摘In many cases, the cutting method is usually adopted for the efficient machining of non-circular body of revolution and a feed drive is needed to actuate the cutting tool to and fro according to input signal wave. The feed drive for the purpose is required of fast response and accurate positioning. Both of these are highly dependent upon the actuating elements. Several schemes of actuation are specially interested. One is the introduction of piezoelectric actuation. However, the tiny working stroke of the piezoelectric material limits its application to a narrow range. Another is the application of electro-magnetic actuator. An innovative feed drive actuated by the stepper motor is introduced for the purpose. For a conventional step operating mode, a stepper motor can only be controlled to position at finite discrete points. Thus, when it is applied as an actuator of the feed drive, it is very difficult to maintain high accuracy and fast response. To eliminate quantitative error, the stepper motor is controlled under the continual mode. It is achieved with a micro-controller system and a built-in control algorithm program, called "tracking algorithm". Within each sampling cycle, the micro-controller will sample the input signal and the time interval will be divided into two parts according to the relative position between two adjacent stepping points. The phase coils correspondent to the two adjacent stepping points are energized respectively with calculated time duration. In the way, the motion of the tool frame smoothly tracks the input signal. This paper presents modeling and identification of frequency response of the proposed drive. The dynamic response of the feed drive is manly decided by the natural frequency of the stepper motor. For the conventional small-size stepper motors, the natural frequency is within the range 200～400 Hz. Experimental results show that the stepper motor actuated tool frame can smoothly keep in track of the input signal wave under "tracking control". The bandwidth of frequency of the feed drive exceeds 310 Hz.
基金From National Ninth Five Years Project (NO. 96-03-03-03A).
文摘Optimal glucose feed strategy for glycerol fed-batch fermentation was investigated by Pontryagin’s maximum principle to maximize the final glycerol yield. The problem was solved by a nonsingular control approach by selecting the culture volume as the control variable, then the general optimal feed profile was numerically determined.
基金financial support extended by the Cotton Mission Mode project TMC MM1 3. 3
文摘Blaptostethus pallescens Poppius (Heteroptera:Anthocoridae),which is amenable to mass rearing,has proved to be a potential predator of sucking pests like mites and thrips.Recently,the cotton mealybug Phenacoccus solenopsis Tinsley emerged as a serious pest on cotton in India.Laboratory studies indicated that B.pallescens could feed on the cotton mealybug.Hence,further investigations were conducted to understand the stage of the predator which is most potential and the pest stage preferred by the predator.Mature nymphs and adults of B.pallescens could predate equally well on the neonates of cotton mealybug.Young (three to four-day-old) nymphs of the predator could not feed on any stage of the cotton mealybug.Mature nymphs (seven-day-old and above) and adults could effectively predate on both young and mature cotton mealybug crawlers,though preference was more for the younger crawlers.However,nymphs and adults of B.pallescens could not predate on the adult stage of the mealybug.Different predator:pest ratios were tested in cage studies and it emerged that B.pallescens adults released against the mealybug crawlers at a ratio of 1:5 and nymphal release at 1:10 caused maximum mortality of the mealybug crawlers.Considering the fast multiplication rate of cotton mealybug and the large number of predators which have to be released to manage them,further detailed studies are necessary on utilizing B.pallescens to target the neonates and younger stages of the cotton mealybug in field conditions.
文摘Mortality is normal and natural in aquaculture experiments. However, it becomes a problem when measuring feed intake as a component of nutrient utilization parameters such as： feed conversion ratio, feed conversion efficiency, apparent net protein utilization, protein efficiency ratio and protein productive value. In order to accurately evaluate feed intake with due consideration of mortality encountered, a formulae was developed using empirical data obtained from an experiement that had mortality. The formulae Fwas： total feed consumed by numbers of survived fishes=DL∑i=1n（Fi/Ni）N. Where, D=Numbers of days fishes were fed within each period ibefore it was adjusted（e.g fortnight）, it was constant throught period of experiment; F=Uantity of feed fed per day for a fortnight before the quantity was adjusted, it changed every fortnight; L=Numbers of living fishes at the end of experimental period; N=Numbers of fishes at each weighing period, it might change every fortnight or might be constant if no mortality occurred; while n=Numbers of times fishes were weighed and quantity of feed was adjusted but this did not include the final weighing at the termination of experiment. However, if the fishes were weighed weekly, then D=6.
文摘Four-factor and three-level orthogonal experimental design(L9(34))was used in the experiment.The effects of three genotypes:Germany SAB three-bred-cross rabbits(S2),New Zealand purebred(N),and crossbred rabbits(ON);three levels of Clenbuterol treatment: 1 ng.g-1,2 ng.g-1and 3 ng.g-1,and three feeding methods:5-day,7-day and 10-day withdrawal period after two weeks of feeding Clenbuterol(CL)on bodyweight gain were evaluated.CL apparently improved average daily gain(ADG)of rabbits.70-day ADG of 5-day and 10-day withdrawal were higher than that of 7-day withdrawal,70-day ADG of S2 genotype was significantly higher than that of the control and N genotype was significant.Genotype,additive dose and feeding method had significant effects on overall-stage ADG.ON genotype,2 ng.g-1 dose and 5-day withdrawal feeding method was the best.Responses of different genotype to Clenbuterol appeared different at experimental prophase or whole experimental period.
文摘On the basis of regressional relationship between nutritional indexes and technological conditions,when confronted with feed quality that contains multiple nutritional indexes,a comprehensive equation of evaluating feed quality was developed by using fuzzy mathematical method at first in this study,and then the optimum technological conditions were established by introduction of statistical frequency analysis method pursuant to the comprehensive evaluating equation mentioned above compared with conventional multi-aim nonlinear programming,this method can lead to easy solutions,and also can make adjustment of the importance of nutritional indexes to feed quality according to practical considerations.An example was given of soybean extruding to show how the method worked.
文摘The Wesel-Xanten stretch of the fiver Rhine between km-812.5 and km-821.5 is one of the reaches where strong erosion leads to high maintenance efforts conceming navigability.In order to improve the naviga- tion conditions without aggravating the flood protection,but also ensuring that the ecological system of the river is not damaged,investigations of the morphodynamical processes in connection with artificial grain feeding ac- tivities have to be carried out by Federal Waterways Engineering and Research...
