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针对居民小区内自行车停放占地面积大,摆放不规则,空间利用率低,影响正常交通。在取样地区进行访问与调查后,设计一种空间利用高、稳定性高、存取方便的自行车停车装置,为解决停车难、摆车乱的问题提供一种理论的方法。 相似文献
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随着环境问题的日益严重,国际原油价格不断上涨,外出使用汽车作为交通工具的成本上涨,自行车作为低碳环保交通工具愈来愈受人们欢迎,而大量自行车的停放就成为了首要问题。针对这一问题,将自行车的停放架进行改造,使自行车的停放趋于自动化、立体化、智能化和美观化。双层自行车能节省大量的可使用空间,提供更多的汽车停车位,并且它还有着使用价格低廉、人性化设计、操作轻便等优点,可使其空间资源利用最大化。停放架分为底层与高层两部分,通过动力系统、传动装置、滑槽、滚轮、钢索实现自行车高层的停放;利用自行车固定架固定座、前后挡架、停车槽腔对停放好的自行车进行限位固定;采用基于GSM的防盗报警系统及时发送报警信息。 相似文献
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拖拉机停车制动装置的型式及要求拖拉机的停车制动装置是保证停车制动安全必不可少的安全装置。在拖拉机停放、坡上起步时对驾驶员和拖拉机的 相似文献
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拖拉机停车制动装置的型式及要求
拖拉机的停车制动装置是保证停车制动安全必不可少的安全装置。在拖拉机停放、坡上起步时对驾驶员和拖拉机的安全至关重要,防止溜车造成追尾或顶撞候车的严重后果。我国现在拖拉机保有量约2000多万台。就停车制动装置而言,存在着严重的安全隐患。 相似文献
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Increasing water productivity of irrigated crops under limited water supply at field scale 总被引:1,自引:0,他引:1
Borkhar district is located in an arid to semi-arid region in Iran and regularly faces widespread drought. Given current water scarcity, the limited available water should be used as efficient and productive as possible. To explore on-farm strategies which result in higher economic gains and water productivity (WP), a physically based agrohydrological model, Soil Water Atmosphere Plant (SWAP), was calibrated and validated using intensive measured data at eight selected farmer fields (wheat, fodder maize, sunflower and sugar beet) in the Borkhar district, Iran during the agricultural year 2004-2005. The WP values for the main crops were computed using the SWAP simulated water balance components, i.e. transpiration T, evapotranspiration ET, irrigation I, and the marketable yield YM in terms in terms of YMT−1, YM ET−1 and YM I−1.The average WP, expressed as $ T−1 (US $ m−3) was 0.19 for wheat, 0.5 for fodder maize, 0.06 for sunflower and 0.38 for sugar beet. This indicated that fodder maize provides the highest economic benefit in the Borkhar irrigation district. Soil evaporation caused the average WP values, expressed as YM ET−1 (kg m−3), to be significantly lower than the average WP, expressed as YMT−1, i.e. about 27% for wheat, 11% for fodder maize, 12% for sunflower and 0.18 for sugar beet. Furthermore, due to percolation from root zone and stored moisture content in the root zone, the average WP values, expressed as YMI−1 (kg m−3), had a 24-42% reduction as compared with WP, expressed as YM ET−1.The results indicated that during the limited water supply period, on-farm strategies like deficit irrigation scheduling and reduction of the cultivated area can result in higher economic gains. Improved irrigation practices in terms of irrigation timing and amount, increased WP in terms of YMI−1 (kg m−3) by a factor of 1.5 for wheat and maize, 1.3 for sunflower and 1.1 for sugar beet. Under water shortage conditions, reduction of the cultivated area yielded higher water productivity values as compared to deficit irrigation. 相似文献
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B. Rivera-Hernández J.J. Obrador-Olán L.A. Aceves-Navarro 《Agricultural Water Management》2010,97(9):1365-5774
In Mexico, corn production, part of which is sweet corn, is mainly destined for human consumption. In the present work, the morphological quality of sweet corn ears was assessed in response to four levels of soil moisture tension indicating irrigation start (−5, −30, −55, and −80 kPa) and three levels of phosphate fertilization (60, 80 and 100 kg ha−1) in carstic soils in the south-east of Mexico. A factorial experimental design with three replicates was used. The following variables were determined: fresh weight (SCFWh), dry weight (SCDWh), diameter (SCDh), and length (SCLh) of sweet corn ears, all without husk, as well as number of kernels (NKxE), number of unfilled kernels (NUK), number of rows (NRxE), and dry kernel weight per ear (DKW). Yield of fresh (YFSCh) and dry (YDSCh) sweet corn ears, both without husk, and the harvest index (HI) were also determined. HI did not show significant statistical differences among irrigation or fertilization treatments. Regarding the other variables, the effect of the more humid treatments (−5 and −30 kPa) and the effect of the higher phosphorus doses (80 and 100 kg ha−1) were statistically equal (P ≤ 0.01) with the lowest NUK and the highest values of all other variables; therefore, irrigation start at soil moisture tension of −30 kPa and phosphate fertilization application of 80 kg ha−1 are recommended. At this level of soil moisture, the mean values over the three fertilization levels and all the replicates, obtained for SCFWh, SCDh, SCLh and NKxE were 198.5 g, 4.39 cm, 26.72 cm and 467 grains, respectively. According to the regression models, moisture tensions from −11.8 to −24.0 kPa, and phosphate fertilization doses from 87.7 to 102.2 kg ha−1 minimize NUK and maximize the values of the rest of the variables. The highest irrigation water use efficiency was found in the moisture tension treatment of −30 kPa with an increase of 27 kg ha−1 ears for each millimeter of applied irrigation water. 相似文献
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Grapevines are extensively grown in the semiarid and arid regions, but little information is available on the variability of energy partitioning and resistance parameters for the vineyard. To address this question, an eddy covariance system was applied to measure energy balance over a vineyard in northwest China during 2005-2006. Result indicated that 2-year average Bowen ratio (β) of vineyard was 1.0, canopy resistance (rc) 289.3 s m−1, aerodynamic resistance (ra) 9.7 s m−1 and climatological resistance (ri) 117 s m−1. This implied that the annual energy was split almost equally between sensible heat and latent heat. Compared to the corresponding values in other ecosystems reported by Wilson et al. [Wilson, K.B., Baldocchi, D.D., Aubinet, M., Berbigier, P., Bernhofer, C., Dolman, H., Falge, E., Field, C., Goldstein, A., Granier, A., Grelle, A., Halldor, T., Hollinger, D., Katul, G., Law, B.E., Lindroth, A., Meyers, T., Moncrieff, J., Monson, R., Oechel, W., Tenhunen, J., Valentini, R., Verma, S., Vesala, T., Wofsy, S., 2002. Energy partitioning between latent and sensible heat flux during the warm season at FLUXNET sites. Water Resource Research 38, 1294-1305.], the vineyard had a higher β, rc and ri than deciduous forests, corn and soybean, and grassland. Such difference was mainly attributed to (1) serious water stress in 2005, which resulted in a greater rc up to 364.4 s m−1; (2) sparse canopy with row spacing of 2.9 m and plant spacing of 1.8 m; (3) warm-dry climate and high attitude (1581 m) along with higher ri and lower psychrometer (54 Pa K−1) in the arid region of northwest China. These characters of vineyard revealed varying process of energy partitioning and surface resistance, and provided a scientific basis in understanding and modeling water and energy balance for the vineyard in the semiarid and arid regions. 相似文献
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Irrigation rate and plant density effects on yield and water use efficiency of drip-irrigated corn 总被引:3,自引:0,他引:3
Salah E. El-Hendawy Essam A. Abd El-Lattief Mohamed S. Ahmed Urs Schmidhalter 《Agricultural Water Management》2008,95(7):836-844
The efficient use of water by modern irrigation systems is becoming increasingly important in arid and semi-arid regions with limited water resources. This study was conducted for 2 years (2005 and 2006) to establish optimal irrigation rates and plant population densities for corn (Zea mays L.) in sandy soils using drip irrigation system. The study aimed at achieving high yield and efficient irrigation water use (IWUE) simultaneously. A field experiment was conducted using a randomized complete block split plot design with three drip irrigation rates (I1: 1.00, I2: 0.80, and I3: 0.60 of the estimated evapotranspiration), and three plant population densities (D1: 48,000, D2: 71,000 and D3: 95,000 plants ha−1) as the main plot and split plot, respectively. Irrigation water applied at I1, I2 and I3 were 5955, 4762 and 3572 m3 ha−1, respectively. A 3-day irrigation interval and three-way cross 310 hybrid corn were used. Results indicated that corn yield, yield components, and IWUE increased with increasing irrigation rates and decreasing plant population densities. Significant interaction effects between irrigation rate and plant population density were detected in both seasons for yield, selected yield components, and IWUE. The highest grain yield, yield components, and IWUE were found for I1D1, I1D2, or I2D1, while the lowest were found for I3D2 or I3D3. Thus, a high irrigation rate with low or medium plant population densities or a medium irrigation rate with a low plant population density are recommended for drip-irrigated corn in sandy soil. Crop production functions with respect to irrigation rates, determined for grain yield and different yield components, enable the results from this study to be extrapolated to similar agro-climatic conditions. 相似文献
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Expected yield losses as a function of quality and quantity of water applied for irrigation are required to formulate guidelines for the effective utilisation of marginal quality waters. In an experiment conducted during 2004-2006, double-line source sprinklers were used to determine the separate and interactive effects of saline and alkali irrigation waters on wheat (Triticum aestivum L.). The study included three water qualities: groundwater (GW; electrical conductivity of water, ECw 3.5 dS m−1; sodium adsorption ratio, SAR 9.8 mmol L−1; residual sodium carbonate, RSC, nil) available at the site, and two synthesized waters, saline (SW; ECw 9.4 dS m−1, SAR 10.3 mmol L−1; RSC nil) and alkali (AW; ECw 3.7 dS m−1, SAR 15.1 mmol L−1; RSC 9.6 meq. L−1). The depths of applied SW, AW, and GW per irrigation ranged from 0.7 to 3.5 cm; the depths of applied mixtures of GW with either SW (MSW) or AW (MAW) ranged from 3.2 to 5 cm. Thereby, the water applied for post-plant irrigations using either of GW, SW or AW ranged between 15.2 and 34.6 cm and 17.1 and 48.1 cm during 2004-2005 and 2005-2006, respectively and the range was 32.1-37.0 and 53.1-60.0 cm for MSW or MAW. Grain yields, when averaged for two years, ranged between 3.08 and 4.36 Mg ha−1, 2.57 and 3.70 Mg ha−1 and 2.73 and 3.74 Mg ha−1 with various quantities of water applied using GW, SW and AW, respectively, and between 3.47 and 3.75 Mg ha−1 and 3.63 and 3.77 Mg ha−1 for MSW and MAW, respectively. The water production functions developed for the two sets of water quality treatments could be represented as: RY = 0.528 + 0.843(WA/OPE) − 0.359(WA/OPE)2 − 0.027ECw + 0.44 × 10−2(WA/OPE) × ECw for SW (R2 = 0.63); RY = 0.446 + 0.816(OPE/WA) − 0.326(WA/OPE)2 − 0.0124RSC − 0.55 × 10−4(WA/OPE) × RSC for AW (R2 = 0.56). Here, RY, WA and OPE are the relative yields in reference to the maximum yield obtained with GW, water applied for pre- and post-plant irrigations (cm), and open pan evaporation, respectively. Crop yield increased with increasing amount of applied water for all of the irrigation waters but the maximum yields as obtained with GW, could not be attained even with increased quantities of SW and AW. Increased frequency of irrigation with sprinklers reduced the rate of yield decline with increasing salinity in irrigation water. The sodium contents of plants increased with salinity/alkalinity of sprinkled waters as also with their quantities. Simultaneous decrease in potassium contents resulted in remarkable increase in Na:K ratio. 相似文献
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L.G. Hou H.L. Xiao J.H. Si S.C. Xiao M.X. Zhou Y.G. Yang 《Agricultural Water Management》2010,97(2):351-356
Based on successive observation, fifteen-day evapotranspiration (ETc) of Populus euphratica Oliv forest, in the extreme arid region northwest China, was estimated by application of Bowen ratio-energy balance method (BREB) during the growing season in 2005. During the growing season in 2005, total ETc was 446.96 mm. From the beginning of growing season, the ETc increased gradually, and reached its maximum value of 6.724 mm d−1 in the last fifteen days of June. Hereafter the ETc dropped rapidly, and reached its minimum value of 1.215 mm d−1 at the end of growing season. The variation pattern of crop coefficient (Kc) was similar to that of ETc. From the beginning of growing season, the Kc value increased rapidly, and reached its maximum value of 0.623 in the last fifteen days of June. Afterward, with slowing growth of P. euphratica, the value dropped rapidly to the end of growing season. According to this study, the ETc of P. euphratica forest is affected not only by meteorological factors, but by water content in soil. 相似文献
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Grass reference evapotranspiration (ETo) is an important agrometeorological parameter for climatological and hydrological studies, as well as for irrigation planning and management. There are several methods to estimate ETo, but their performance in different environments is diverse, since all of them have some empirical background. The FAO Penman-Monteith (FAO PM) method has been considered as a universal standard to estimate ETo for more than a decade. This method considers many parameters related to the evapotranspiration process; net radiation (Rn), air temperature (T), vapor pressure deficit (Δe), and wind speed (U); and has presented very good results when compared to data from lysimeters populated with short grass or alfalfa. In some conditions, the use of the FAO PM method is restricted by the lack of input variables. In these cases, when data are missing, the option is to calculate ETo by the FAO PM method using estimated input variables, as recommended by FAO Irrigation and Drainage Paper 56. Based on that, the objective of this study was to evaluate the performance of the FAO PM method to estimate ETo when Rn, Δe, and U data are missing, in Southern Ontario, Canada. Other alternative methods were also tested for the region: Priestley-Taylor, Hargreaves, and Thornthwaite. Data from 12 locations across Southern Ontario, Canada, were used to compare ETo estimated by the FAO PM method with a complete data set and with missing data. The alternative ETo equations were also tested and calibrated for each location. When relative humidity (RH) and U data were missing, the FAO PM method was still a very good option for estimating ETo for Southern Ontario, with RMSE smaller than 0.53 mm day−1. For these cases, U data were replaced by the normal values for the region and Δe was estimated from temperature data. The Priestley-Taylor method was also a good option for estimating ETo when U and Δe data were missing, mainly when calibrated locally (RMSE = 0.40 mm day−1). When Rn was missing, the FAO PM method was not good enough for estimating ETo, with RMSE increasing to 0.79 mm day−1. When only T data were available, adjusted Hargreaves and modified Thornthwaite methods were better options to estimate ETo than the FAO PM method, since RMSEs from these methods, respectively 0.79 and 0.83 mm day−1, were significantly smaller than that obtained by FAO PM (RMSE = 1.12 mm day−1). 相似文献
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Relationship between stable carbon isotope discrimination and water use efficiency under regulated deficit irrigation of pear-jujube tree 总被引:2,自引:0,他引:2
Ningbo Cui Taisheng Du Shaozhong Kang Fusheng Li Xiaotao Hu Mixia Wang Zhijun Li 《Agricultural Water Management》2009,96(11):1615-1622
To investigate the relationship between stable carbon isotope discrimination (Δ) of different organs and water use efficiency (WUE) under different water deficit levels, severe, moderate and low water deficit levels were treated at bud burst to leafing, flowering to fruit set, fruit growth and fruit maturation stages of field grown pear-jujube tree, and leaf stable carbon isotope discrimination (ΔL) at different growth stages and fruit stable carbon isotope discrimination (ΔF) at fruit maturation stage were measured. The results indicated that water deficit had significant effect on ΔL at different growth stages and ΔF at fruit maturation stage. As compared with full irrigation, the average ΔL at different growth stages and ΔF at fruit maturation stage were decreased by 1.23% and 2.67% for different water deficit levels, respectively. ΔL and ΔF among different water deficit treatments had significant difference at the same growth stage (P < 0.05). Under different water deficit conditions, significant relationships between the ΔL and WUEi (photosynthesis rate/transpiration rate, Pn/Tr), WUEn (photosynthesis rate/stomatal conductance of CO2, Pn/gs), WUEy (yield/crop water consumption, Y/ETc) and yield, or between the ΔF and WUEy and yield were found, respectively. There were significantly negative correlations of ΔL with WUEi, WUEn, WUEy and yield (P < 0.01) at the fruit maturation stage, or ΔL with WUEi and WUEn (P < 0.01) over whole growth stage, respectively. ΔF was negatively correlated with WUEy, WUEn and yield (P < 0.05), but positively correlated with ETc (P < 0.01) over the whole growth stage. Thus ΔL or ΔF can compare WUEn and WUEy, so the stable carbon isotope discrimination method can be applied to evaluate the water use efficiency of pear-jujube tree under the regulated deficit irrigation. 相似文献
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Optimal coupling combinations between irrigation frequency and rate for drip-irrigated maize grown on sandy soil 总被引:1,自引:0,他引:1
This study was conducted over 2 years (2007 and 2008) to establish the optimal combinations between irrigation frequency and rate for drip-irrigated maize using water production functions and water use-yield relationships. A field experiment was conducted using a randomized complete block split plot design with four irrigation frequencies (F1, F2, F3 and F4, irrigation events once every 1, 2, 3 or 4 days, respectively) and three drip irrigation rates (I1: 1.00, I2: 0.80, and I3: 0.60 of the estimated evapotranspiration, ET) as the main and split plots, respectively. Our results show that yield variables and water use efficiencies (WUEs) increased with increasing irrigation frequency and rate, with non-significant differences between F1 and F2 in yield variables and between I1 and I2 in WUEs. Moreover, the combination between various irrigation frequencies and rates had an important effect on yield variables and WUEs, with the highest values being found for F1I2 and F2I1 and the lowest for F3I3 and F4I3. The F1I3 treatment had grain yield and yield components values similar to those obtained for the F3I2 and F4I1 treatments and WUEs values similar to those obtained for the F2I1 and F2I2 treatments. Seasonal yield response factors (ky) were 1.81 and 1.86 in 2007 and 2008, respectively. Production functions of yield versus seasonal crop ET were linear for all combinations of irrigation frequency and rate and for all irrigation frequency treatments with the exception of the F1 treatment, which instead showed a second order relationship. The relationship between WUE and grain yield was best represented by a power equation. In conclusion, we identified the optimal coupling combinations between irrigation frequency and water application rate to achieve the maximum yield and WUEs under either sufficient (F2I1) or limited irrigation (F1I3) water supplies. 相似文献