Search

Agricultural machinery and equipment are indispensable to realize resource utilization for high efficiency in sustainable production. It is also required for the efficient, intelligent, and environmentally friendly agricultural power machinery, due to the greenhouse gas emissions and the drastic reduction in the extraction of non-renewable resources. Fuel cell distributed drive electric tractors (FCDET) can provide a new approach to developing green agricultural machinery. However, the great challenge has posed on the traction efficiency, short range, and high hydrogen consumption. A reasonable and effective power allocation can be expected to reduce energy consumption for the high efficiency of the fuel cell system. In this study, an allocation strategy of plowing drive power was proposed for FCDET using adaptive multi-resolution analysis (AMRA). The effective decoupling between the various energy sources was also realized to reduce the frequent start-stop and the large power fluctuations of the hydrogen fuel cell. Firstly, two models were established for the fuel cell system and the total efficiency solver. The first-time reconstruction was to obtain the subsequence that effectively responded to the oscillation characteristics of the power signal using the tunable Q-factor wavelet transform (TQWT). The second reconstruction was to decompose the low-frequency subseries into several discrete sub-signals with special sparse properties using variational mode decomposition (VMD). Then, the sparrow search algorithm (SSA) was used to obtain the optimal combination of modal decomposition layers and quadratic penalty factors for VMD in real time. Finally, the second-time decomposed subsequence and sub-signals were reconstructed, according to the frequency characteristics. The reconstructed power signal was redistributed among the various energy sources. A test was carried out to verify the power allocation. The power demand information of the drive motor was acquired for FCDET plowing conditions at the China YTO Mengjin test base, taking the ET504-H prototype as the object. The plowing condition included a 0-8.7 s starting stage and an 8.7-18.0 s stable plowing stage. The demand power signal shared a large rate of change in the starting stage and a large high-frequency characteristic in the stable plowing stage. In addition, another experiment was carried out on the transmission bench in the New Energy Key Laboratory of Henan Province, in order to test the cooperative operation of permanent magnet synchronous motors (PMSM) under three power allocations. The results showed that the FCDET drive power allocation using AMRA effectively improved the energy utilization of the fuel cell system and the economy of the whole vehicle in plowing condition. The fuel cell system efficiency was improved by 8.30% and 1.82%, respectively, compared with the power-following and the first-time reconstruction. The equivalent hydrogen consumption was reduced by 35.60% and 11.86%, respectively. Meanwhile, the drive motor efficiency was improved by 2.06% and 1.27% on average; the energy consumption was reduced by 3.73% and 2.60%, respectively. This finding can provide a novel theoretical and technical approach for the development of the FCDET control system. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high efficiency in removing nitrogen salt is the key to insure the operation of recirculating aquacultural systems. The current study focused on the efficiency and the characteristic of Chaetomorpha maxima clones (hereinafter referred to as Chaetomorpha maxima) to remove the ammonia, the nitrite and the nitrate in seawater. The absorption efficiency of Chaetomorpha maxima to nutrients is mainly affected by the enzyme activity of algae and the concentration of nutrients in water. The absorption of NO3--N and NO2--N by Chaetomorpha maxima is more limited to its enzyme activity. The absorption of NH4+-N depends on the concentration of NH4+-N in water. Within a certain concentration (NH4+-N: 0-15 mg/L, NO2--N: 0-3 mg/L, NO3--N: 0-15 mg/L), the absorption rate of Chaetomorpha maxima on nitrogen salt suppressed with the reduction of nitrogen concentration in the water. The absorption rate of ammonia nitrogen by algae changed greatly. The final absorption rate of the 5, 10 mg/L group was close to 0, and that of the 15 mg/L group was 20×10³ mg/(g·h). While the absorption rate of nitrite and nitrate is relatively stable. The final absorption rate of three groups of NO3--N is 20-30 mg/(g·h), and that of NO2--N was 2-4 mg/L. When the concentrations of three nitrogen salts were same (3 mg/L), Chaetomorpha maxima first absorbed NH4+-N, and the absorption rate on NH4+-N was notably higher than on NO2--N and NO3--N. There was no significant difference between NO2--N and NO3--N. However, when the NO2--N content was too low, the algae will preferentially absorb NO3--N. When ratio (g/L) of the fresh weight of Chaetomorpha maxima to water volume was 10∶1, the removal rates on NH4+-N, NO2--N and NO3--N of Chaetomorpha maxima in the artificial aquacultural wastewater (NH4+-N: 3.0±0.5 mg/L, NO2--N: 0.1±0.05 mg/L, NO3--N: 3.0±0.5 mg/L, PO43--P: 0.2±0.5 mg/L）were 94.3%, 100% and 82.2% in 15 hours. Although the removal rate of NH4+-N by Chaetomorpha maxima was high, it could not replace microorganism as the main unit of NH4+-N removal completely. In order to obtain sufficient ammonia NH4+-N as electron acceptor for microbial, the algae unit was suggested to be located behind the microbial unit. The practical application of algae treatment unit should consider comprehensively both the algae treatment efficiency and water renewal rate. In the actual production, the ratio between the fresh algae quality and the water volume can be adjusted according to the concentration of NO3--N in the water, so as to improve the removal rate of nitrate. The mass concentrations of NO3--N, NH4+-N, NO2--N in recirculating aquacultural systems were generally at 0-10, 0-5, 0-2 mg/L. Within the range of nitrogen salt concentration in circulating water system, three kinds of nitrogen salts will not cause adverse effects on algae. This study could provide data for the application of Chaetomorpha maxima clones in the treatment of aquacultural wastewater and promoted the utilization of aquaculture wastewater as a resource. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Atlantic salmon Salmo salar L. juveniles with various initial body weight of (30.25±2.12) g (SW1 group), (24.27g±1.59)g (SW2 group), (18.05±2.46)g (SW3 group) were reared in a recirculating system under a photoperiod of 12:12 light: dark in 1-42 days and 24 light: 00 dark in 43-84 days to evaluate the effects of size on growth performance and mechanism of physiological response during smoltification. The results showed that the maximal condition factor, daily weight gain, food conversion efficiency, and net yield were found in SW2, with significant difference in different experimental groups (P<0.05). There were significantly higher special growth rate in body length and body weight in SW2 than in other groups (P<0.05); and there were significant differences in coefficient of body length and body weight variation among the three groups (P<0.05). The CV of body length of S. salar in the different groups did not significantly change in the first 6 weeks of the study. But when the condition was changed to full light the coefficient of variation of body length significantly increased in the SW1 and SW2 groups, and the change was more significant in group SW1 compared to the other groups (P<0.05). The CV of body weight of S. salar in group SW3 varied greatly over the course of the experiment. Within the first 6-week light cycle (12L:12D), the coefficient of variation of body weight in SW1, SW2 showed insignificant difference (P>0.05). After the condition was changed to full light in the last 6 weeks, the coefficient of variation of body weight in 3 groups was narrowly varied. At 84 d, the value in the SW3 group was significantly higher than that in any other group (P<0.05). The hemoglobin concentration and the number of red blood cell (RBC) were found to be increased with the increase in size, indicating that the increase demand of oxygen for fish. The maximal white blood cell (WBC), lymphocyte, neutrophils was found in SW3 group, which showed that enhanced their disease-resistant capability. The number of red blood cells did not differ significantly between groups SW1 and SW2 (P>0.05), but the value was significantly higher than that in group SW3 (P<0.05). The number of thrombocytes fell with the increase of culture size, and the three groups differed significantly (P<0.05).The number of neutrophil was close among these groups, and no significant difference was identified (P>0.05). The highest values of total protein (TP) and albumin (ALB) appeared in SW2 group, and the difference of three groups were marked (P<0.05). The concentration of total cholesterol (TC) and triglycerides (TG) increased with the increase in size (P<0.05), which suggested that the enhancement of energy utilization in the blood and body. The concentration of uric acid and carbamide in metabolites was highest in group SW2. Their concentrations in groups SW1 and SW2 did not differ significantly (P>0.05), and they were significantly higher than those in group SW3 (P<0.05). The concentration of T-Bil in group SW3 was significantly higher than those in the other two groups (P<0.05).The concentration of glucose were no significant difference (P>0.05), which suggests that utilization rate of glucose by Salmo salar L. is lower. The concentration of CK was highest in group SW3, but no significant difference was identified among the three groups (P>0.05). So Salmo salar L. in 24.27±1.59g should be selected for the smoltification, thereby optimizing the culture condition and increasing the culture yield per water body at lower cost, which can theoretically referenced for the scale aquaculture of Salmo salar L. seeds. [ABSTRACT FROM AUTHOR]