共查询到18条相似文献，搜索用时 468 毫秒
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指出了餐饮行业产生的废水（泔水）可以作为一种资源被回收利用,探讨了通过工艺上的改进,采用卧螺离心机对泔水进行规模化分离处理,达到高效分离的目的,从而使泔水得到＂资源化＂的分类处理。 相似文献
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崔凤桐 《林业机械与木工设备》1997,25(6):38-39,33
牙嵌式自由轮差速器的性能检测收稿日期：１９９６－０６－２８（１５００７６）哈尔滨拖拉机厂崔凤桐１差速器的结构及性能牙嵌式自由轮差速器是一种可以替代行星轮式简单差速器的防滑差速器。目前在国外林业拖拉机、工程机械、越野汽车上都得到了广泛应用。近年来，我国... 相似文献
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洪大森 《林业机械与木工设备》1987,(2)
差速器的种类很多,下面对常用的几种差速器的性能,以及它们对拖拉机的适应性作一简要论述。 1.摩擦片式差速器这种差速器,实际上是普通差速器的变型。它可以利用普通锥齿轮差速器的许多标准零件。在差速器壳与半轴锥齿轮之间装有摩擦片6与压盘2,行星齿轮十字轴的端部做成V形面,与之相配的差速器壳上的轴承孔也为V形面。压盘和从动摩擦片用内花键与半轴齿轮上的花键连接,主动摩擦片上的外花键与差速器壳连接。 相似文献
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差速器是汽车、拖拉机的一个重要部件。为了满足汽车,拖拉机行驶运动学的要求,在汽车、拖拉机的左右驱动轮间必须安装差速器。绥化林机厂生产的ＣＪ－４０营林集材机是采用目前国际上较为先进的自锁式差速器－牙嵌式自由轮差速器,从而提高了ＣＪ－４０集材机的通过性能。 在通用设备上制造牙嵌式自由轮差速器,其加工工艺难度是比较大的。为加工出合格产品,达到设计上的技术要求,我们在加工工艺、刀具和工装设计上都下了很大功夫。从认识到实践,从手工操作到机械加工都取得了一定的经验和成果。１牙嵌式自由轮差速器的结构 牙嵌式差速… 相似文献
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从离心机工作原理出发，根据工业污水处理的实际情况，对污水处理中离心机的种类、筛选原则及应用等进行了分析和探讨，以期提供参考。 相似文献
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Hydraulic redistribution of soil water during summer drought in two contrasting Pacific Northwest coniferous forests 总被引：1，自引：0，他引：1
The magnitude of hydraulic redistribution of soil water by roots and its impact on soil water balance were estimated by monitoring time courses of soil water status at multiple depths and root sap flow under drought conditions in a dry ponderosa pine (Pinus ponderosa Dougl. ex Laws) ecosystem and in a moist Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) ecosystem. The fate of deuterated water applied to small plots to create a strong horizontal soil water potential gradient was also monitored to assess the potential for horizontal redistribution of water and utilization of redistributed water by co-occurring shallow-rooted plants. In a 20-year-old Douglas-fir stand, approximately 28% of the water removed daily from the upper 2 m of soil was replaced by nocturnal hydraulic redistribution during late August. In an old-growth ponderosa pine stand, approximately 35% of the total daily water utilization from the upper 2 m of soil appeared to be replaced by hydraulic redistribution during July and August. By late September, hydraulic redistribution in the ponderosa pine stand was no longer apparent, even though total water use from the upper 2 m of soil was nearly identical to that observed earlier. Based on these results, hydraulic redistribution would allow 21 and 16 additional days of stored water to remain in the upper soil horizons in the ponderosa pine and Douglas-fir stands, respectively, after a 60-day drought. At both sites, localized applications of deuterated water induced strong reversal of root sap flow and caused soil water content to cease declining or even temporarily increase at locations too distant from the site of water application to have been influenced by movement of water through the soil without facilitation by roots. Xylem water deuterium values of ponderosa pine seedlings suggested utilization of redistributed water. Therefore, hydraulic redistribution may enhance seedling survival and maintain overstory transpiration during summer drought. These first approximations of the extent of hydraulic redistribution in these ecosystems suggest that it is likely to be an important process in both wet and dry forests of the Pacific Northwest. 相似文献
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二次调节静液储能拖拉机传动系统 总被引：1，自引：0，他引：1
二次调节静液储能拖拉机传动系统是由柴油机，液压蓄能器，液压泵/马达（二次元件），差动变速器和驱动轴等组成，该系统充分利用了液压蓄能功率密度大，二次元件具有较高的控制质量，可实现四象限工作等特点；实现了柴油机和拖拉机行驶载荷的分离，工作过程中当外负载扭矩发生变化时，将引起二次元件的转速变化，从而引起二次元件排量的变化，通过调节液压马达的变量机构使其与工作负载所需转速相适应。 相似文献
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大棚切花月季平面微灌技术的研究 总被引：1，自引：1，他引：0
土壤的供氧状况明显影响切花月季的产量和质量．在大棚土壤常规栽培条件下，为了使生长基质保持长期稳定的供氧能力，解决灌溉水的定量化和均匀化，我们在改良土壤的同时，设计了切花月季平面微灌栽培系统，并对其水力学特性、微灌喷头的有效性、根系垂直分布、微灌区内温度与湿度的动态变化等进行了研究。结果表明，微灌系统中流量与压力的水力学方程为ｑ＝２０．８６Ｈ０．６９，有效半径Ｒ＝８０ｃｍ，覆盖死角α＝１０°。与对照相比，微灌区１０～３０ｃｍ基质层内的有效根量大而分布均匀；切花月季不同群体层高内的温度相对较低、湿度较大；平均年产花量高于对照４８％，增益效果显著。 相似文献
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The objective of this study is to clarify the performance of the Global Positioning System (GPS) in forested areas after selective availability (SA) was turned off. In this study, we conducted a field test on horizontal and vertical positional errors of GPS positioning at different points in forested areas. The precision and accuracy of GPS positioning at different points were then calculated and compared. Furthermore, the effect of differential GPS (DGPS) on precision and accuracy was analyzed using analysis of variance (ANOVA), and the necessity for DGPS after SA was turned off was discussed. As a result, the largest horizontal precision errors were found to be in the plantation forest, followed by the natural forest and forest road. On the other hand, precision errors were smallest at the landing, around which there were no obstacles. Horizontal accuracy errors were greatly improved by using the DGPS. Large vertical precision errors were produced in the plantation forest, on the forest road, and in the natural forest, while those at the landing were much smaller. Vertical accuracy errors were also relatively small at the landing. In conclusion, tree canopies greatly affected precision errors, and the DGPS improved not horizontal precision but horizontal accuracy. The autonomous GPS is sufficiently useful for purposes in which horizontal positional errors of a maximum of 10m are allowable. However, the DGPS should be used for surveying and mapping, for which higher accuracy is necessary. 相似文献
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建立了静液压储能传动汽车能量再生系统各分立元件及系统的分析模型,采用4阶Rugge-K u tta算法求解分析模型,获得了蓄能器内气体的压力和温度、泵/马达的扭矩和效率、液压回路的压力损失和飞轮的转速等参数,利用这些参数计算了能量再生系统系统的能量损耗和循环效率.计算结果表明,能量损耗主要产生于液压泵/马达,约占总损失的24%,当蓄能器的热时间常数为60s时,蓄能器基本处于绝热状态,热能损失很少;系统循环效率在50%~75%,与计算时飞轮的初速度和转动惯量有关. 相似文献
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The hydraulic limitation hypothesis (Ryan and Yoder 1997) proposes that leaf-specific hydraulic conductance (kl) and stomatal conductance (gs) decline as trees grow taller, resulting in decreased carbon assimilation. We tested the hydraulic limitation hypothesis by comparison of canopy-dominant Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) trees in stands that were approximately 15 m (20 years old), 32 m (40 years old) and 60 m (> 450 years old) tall in Wind River, Washington, USA. Carbon isotope discrimination (Delta) declined with tree height (18.6, 17.6 and 15.9 per thousand for stands 15, 32 and 60 m tall, respectively) indicating that gs may have declined proportionally with tree height in the spring months, when carbon used in the construction of new foliage is assimilated. Hydraulic conductance decreased by 44% as tree height increased from 15 to > 32 m, and showed a further decline of 6% with increasing height. The general nonlinear pattern of kl versus height was predicted by a model based on Darcy's Law. Stemwood growth efficiency also declined nonlinearly with height (60, 35 and 28 g C m-2 leaf area for the 15-, 32- and 60-m stands, respectively). Unlike kl and growth efficiency, gs and photosynthesis (A) during summer drought did not decrease with height. The lack of decline in cuvette-based A indicates that reduced A, at least during summer months, is not responsible for the decline in growth efficiency. The difference between the trend in gs and A and that in kl and D may indicate temporal changes (spring versus summer) in the response of gas exchange to height-related changes in kl or it may be a result of measurement inadequacies. The formal hydraulic limitation hypothesis was not supported by our mid-summer gs and A data. Future tests of the hydraulic limitation hypothesis in this forest should be conducted in the spring months, when carbon uptake is greatest. We used a model based on Darcy's Law to quantify the extent to which compensating mechanisms buffer hydraulic limitations to gas exchange. Sensitivity analyses indicated that without the observed increases in the soil-to-leaf water potential differential (DeltaPsi) and decreases in the leaf area/sapwood area ratio, kl would have been reduced by more than 70% in the 60-m trees compared with the 15-m trees, instead of the observed decrease of 44%. However, compensation may have a cost; for example, the greater DeltaPsi of the largest trees was associated with smaller tracheid diameters and increased sapwood cavitation, which may have a negative feedback on kl and gs. 相似文献
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Drought-induced tree mortality has increased over the last decades in forests around the globe. Our objective was to investigate under controlled conditions the hydraulic adjustments underlying the observed ability of Pinus halepensis to survive seasonal drought under semi-arid conditions. One hundred 18-month saplings were exposed in the greenhouse to 10 different drought treatments, simulating combinations of intensities (fraction of water supply relative to control) and durations (period with no water supply) for 30 weeks. Stomata closed at a leaf water potential (Ψ(l)) of -2.8 MPa, suggesting isohydric stomatal regulation. In trees under extreme drought treatments, stomatal closure reduced CO(2) uptake to -1 μmol m(-2) s(-1), indicating the development of carbon starvation. A narrow hydraulic safety margin of 0.3 MPa (from stomatal closure to 50% loss of hydraulic conductivity) was observed, indicating a strategy of maximization of CO2 uptake in trees otherwise adapted to water stress. A differential effect of drought intensity and duration was observed, and was explained by a strong dependence of the water stress effect on the ratio of transpiration to evapotranspiration T/ET and the larger partitioning to transpiration associated with larger irrigation doses. Under intense or prolonged drought, the root system became the main target for biomass accumulation, taking up to 100% of the added biomass, while the stem tissue biomass decreased, associated with up to 60% reduction in xylem volume. 相似文献