石墨烯对低密度聚乙烯拉伸性能的影响

从改善低密度聚乙烯(LDPE)材料力学性能和抗老化性能出发,探讨了加入石墨烯对LDPE拉伸强度、断裂伸长、回弹性等拉伸性能和氙灯人工加速老化后拉伸性能的影响。结果表明:石墨烯能明显改善LDPE材料的拉伸性能和抗老化能力:拉伸性能的改善程度随石墨烯的添加而呈先增后减趋势,当石墨烯添加量为0.02wt%时,LDPE表现出最优的拉伸性能;较不含石墨烯的LDPE,石墨烯添加量为0.02wt%改性LDPE,加速老化后其抗拉强度、断裂伸长率和断后回弹率等拉伸性能均出现较低下降,但均优于未改性LDPE老化前的拉伸性能。     

填充母料改性再生料在单翼迷宫式滴灌带中的应用研究

以滴灌带再生料、纳米碳酸钙母料、色母、抗氧剂为主要原料,研究了纳米碳酸钙母料改性滴灌带再生料对单翼迷宫式滴灌带性能影响的研究。结果表明:随着纳米碳酸钙填充母料的增加,单翼迷宫式滴灌带强度、刚度都有较大的提高,当填充母料质量份数在15份时,拉伸强度达到最大,加工性能良好,产品外观光滑,同时,随着纳米碳酸钙填充母料的增加,单翼迷宫式滴灌带热氧稳定性及耐热性都得了明显提高。     

旧滴灌带耐拉拔试验研究

为了给旧滴灌带回收机提供设计依据,测量了4种旧滴灌带的拉断载荷及在定载荷下的伸长率。试验测得各组样品最大拉断载荷均值分别为333.82、208.81、219.65、204.27N,定载荷下的伸长率分别为0、7.5%、2.5%、12.5%。根据试验数据得出结论:回收已达使用年限的旧滴灌带时,带的最大载荷应不超过200N,以避免带回收过程中断裂;回收未达到使用年限的旧滴灌带时,带的最大载荷应不超过100N,以避免带产生严重变形。     

HDPE板衬砌渠道可行性初探

为了分析高密度聚乙烯(HDPE)板衬砌技术在渠道工程中的可行性,使用改性后的HDPE原料或废旧PE滴灌带作为渠道的衬砌板,结合施工方案设计、水力学分析以及冻胀数值模拟对其展开研究.HDPE板采用热熔连接和在渠段连接处设置伸缩孔的施工方案,保证了整体的防渗性能.水力学分析表明:相较于混凝土衬砌渠道,低糙率的HDPE板衬砌...     

PTN封闭材料在灌区工程应用中的固化性能试验研究

为减少水资源的浪费,灌区混凝土工程表面裂缝需要固化性能好的封闭材料。通过三种不同的固化剂对PTN封闭材料进行改性,选出较优的固化剂C;试验结果表明:改性后封闭材料表干和实干时间分别比空白组缩短3 h和5 h;拉伸强度达到2.62 MPa,高于空白组1.91 MPa;断裂伸长率1112%,高于空白组761%;拉伸黏结强度达到1.59 MPa,拉伸断裂伸长率达到586%;建立材料硬度与拉伸性能的相关关系式,可以无损检测预测PTN封闭材料的拉伸性能;研究结果对灌区工程混凝土表面裂缝封闭达到节水灌溉的要求具有一定的工程意义。     

射流三通连接滴灌带的水力性能沿程变化规律

为了探究滴灌带沿程水力性能的变化规律,在射流三通进口流量为0.1~1.2 m³/h的范围内,开展射流三通进口流量与出口水头振幅的水力性能试验,发现射流三通连接脉冲滴灌系统的流量阈值为0.2~0.8 m³/h;在脉冲滴灌系统流量阈值的范围内,开展射流三通连接滴灌带沿程脉冲参数试验,研究射流三通连接60 m滴灌带沿程脉冲性能的变化规律,发现当滴灌带进口水头振幅大于1 m时,沿程水头振幅的衰减速率存在突变点,沿程脉冲频率先增大后减小,射流三通在整条滴灌带上均能产生脉冲水流的进口流量设计范围是0.5~0.8 m³/h.在射流三通进口流量的设计范围内,开展稳压滴灌和脉冲滴灌的同台对比试验,结果表明,射流三通连接滴灌带内的水头损失比普通三通连接滴灌带内的降低62.5%~83.3%,灌水均匀系数提高了0.6%~0.9%,流量偏差率降低了1.2%~4.1%;进口流量为0.7 m³/h时,射流三通连接滴灌带灌水均匀度最高.     

含水率对竹材开纤影响的研究

为研究含水率对改性竹片机械开纤效果的影响,文章对软化处理后的竹片在不同含水率进行机械开纤,根据竹片分离情况,得到竹片在含水率43%~115%能够开纤。在此含水率范围内进行竹片开纤,对获得的竹纤维进行相关的性能测试,并在此基础上采用回归算法对试验数据进行分析。结果表明:纤维得率随含水率的降低而降低;由含水率74%的改性竹片制取的纤维细度最均匀;改性竹片的含水率为85%时,纤维的断裂强力到达峰值;改性竹片的绝对含水率与制得纤维的断裂伸长率大体上呈反比;与弹性模量大体上呈正比。因此,改性竹片在绝对含水率为74%时,开纤得到的纤维综合性能最好。     

超声波处理玉米磷酸酯淀粉膜液对膜性能的影响

对玉米磷酸酯淀粉基可食膜液进行超声波处理,并对所成膜的抗拉强度、断裂伸长率、透氧率及膜表面微观结构进行了分析。结果表明:超声波处理使膜的抗拉强度、断裂伸长率及阻氧性能提高,膜面均一性也有了一定的改善。在试验范围内,当超声波功率为80W时,对膜液处理50min,膜的性能较佳:抗拉强度为25.53MPa,断裂伸长率为29.07%,透氧率为5.8×10-6cm3/(m2.d.Pa)。     

新型混凝土渠道接缝材料抗冻性能研究

对一种新型混凝土渠道接缝材料的抗冻性能进行了研究。经过200次冻融循环,发现不同处理的材料拉伸强度均有下降趋势,添加0%,10%,35%,55%粉煤灰的材料拉伸强度与对照比较分别下降了29%,5%,30%,25%,在材料中添加适量填料可改善材料性能,拉伸强度下降最小的材料与对照比较只下降了5%;同时材料的断裂拉伸率也有下降趋势;冻融处理后材料表面的孔隙明显变大、增多。该材料的抗冻性能优良,在我国北方地区推广应用尤为适宜。     

不同滴灌灌水处理对南疆沙区红枣产量及品质的影响

以新疆第一师沙区骏枣为试验材料,考虑滴灌方式、灌水量和灌水次数3个因素,设置9个不同的滴灌灌水处理和1个漫灌对照处理进行大田试验,研究不同滴灌灌水方式下,不同灌水量和灌水次数对南疆沙区成龄红枣产量和品质的影响。结果表明:点源滴灌方式和线源滴灌方式在果形指数、可食率和总糖含量方面规律性一致,中水滴灌可以降低果形指数,低水滴灌可食率均显著低于中高水滴灌处理,总糖含量均随着灌水量的增加呈现出先减少后增大的趋势。灌溉定额1 050mm条件下,滴灌灌水次数18次相比14次、10次分别增加产量8.2%、11.4%,但会相对降低果实品质。所有滴灌处理中灌溉定额1 050mm、灌水次数10次和灌溉定额1 050mm、灌水次数18次处理的产量和品质综合效果较优,比漫灌节约灌溉水量30%。     

基于Matlab GUI的滴灌毛管优化设计程序研究

滴灌工程设计中,科学合理布设滴灌带对节水成效和工程投资都具有十分重要的影响。为提高滴灌规划设计的效率及优化效果,最大限度增大毛管铺设长度、减少滴灌工程建设单位投资,在现有滴灌水力模型的基础上,采用Matlab GUI和遗传算法工具箱相结合的方法,对毛管优化设计过程进行模块化程序设计。经验证,该优化程序界面友好,计算可靠,不仅大大减少了人工计算量,对当前滴灌工程规划设计和推广也有重要帮助。     

3种滴灌带流道滴头抗堵塞性能对比试验

对3种不同灌水器流道抗堵塞性能进行了测试,试验结果表明,新流道结构内镶贴片式滴灌带的抗堵塞性能比边缝式滴灌带提高了30%以上,比常规内镶贴片式滴灌带提高1倍以上。新流道结构的贴片式滴灌带既解决了边缝式滴灌带灌水均匀性差,又弥补了常规内镶贴片式滴灌带容易堵塞的缺点,推广应用前景广阔。      

Crop establishment using subsurface drip irrigation: a comparison of point and area sources

One of the greatest challenges faced by irrigators using subsurface drip irrigation (SDI) is crop establishment. Establishment with SDI relies on unsaturated water movement from the buried source to the seed or seedling. Establishment is therefore affected by distance to source, soil texture, structure, and antecedent water content. Two products were compared (drip tape and CRZI – Capillary Root Zone Irrigation) in a field trial designed to address the establishment issue. To measure the widest establishment extent, a crop was sown perpendicular to the drip laterals. The CRZI system comprises a combination of both impermeable and highly conductive materials designed to produce a wider lateral wetting pattern, while reducing drainage and surface tunnelling. The hypothesis being tested was that the CRZI concept would offer some advantage over drip tape for addressing the establishment issue. Results showed that for the soil at the experimental site (Hanwood loam), installation depth of either product should be no greater than 0.2 m. If attempting to establish a broadsown crop such as lucerne or pasture, lateral spacing should be no greater than 1.0 m. With this configuration, an application depth of 120 mm should still be expected for total surface coverage. CRZI did not produce any establishment advantage over drip tape. Two explanations are given for this result. Firstly, the soil in which the trial was performed has excellent capillary properties and has a natural clay pan which would serve to even out results. Secondly, the two products exploited very different wetting methods to produce similar surface wetting efficiency (ratio of surface wetted width to applied irrigation volume). The drip tape quickly saturated the surface and wet outwards through surface flow. As CRZI did not utilise the surface to aid with distribution, it produced a slower, more even, wetting pattern.Communicated by P. Thorburn     

痕灌带地埋下水力特性

为了获得痕灌带在田间应用的设计参数及其水力性能,通过室内与室外试验相结合的方法,针对流量规格为900 mL/h的痕灌带在自由出流时的制造偏差系数、流量与压力关系及其地埋后的水力特性以及痕灌毛管的地埋极限铺设距离进行了计算与评估.试验结果表明,试验痕灌带制造偏差系数为0.04,制造精度较高,且痕量灌水器压力-流量关系符合微灌灌水器幂函数关系式;痕量灌水器在地埋条件下,流量对压力变化的敏感性要高于自由出流.痕灌带(900 mL/h)在地埋后其流量减小幅度不明显,与室内自由出流相比,在额定工作压力条件下(10 m),地埋后痕量灌水器平均流量减少3%~8%;此外,在满足系统流量偏差系数(q_v)不大于20%条件下,并结合田间土壤含水率空间变异性的研究验证,试验痕灌带(900 mL/h)在平坡铺设、砂壤土中的地埋铺设极限距离为150 m左右.     

Subsurface drip irrigation of onions: Effects of drip tape emitter spacing on yield and quality

Improved irrigation water use efficiency is an important component of sustainable agricultural production. Efficient water delivery systems such as subsurface drip irrigation (SDI) can contribute immensely towards improving crop water use efficiency and conserving water. However, critical management considerations such as choice of SDI tube, emitter spacing and installation depth are necessary to attain improved irrigation efficiencies and production benefits. In this study, we evaluated the effects of subsurface drip tape emitter spacing (15, 20 and 30 cm) on yield and quality of sweet onions grown at two locations in South Texas—Weslaco and Los Ebanos. Season-long cumulative crop evapotranspiration (ETc) was 513 mm in Weslaco and 407 mm at Los Ebanos. Total crop water input (rain + irrigation) at Weslaco was roughly equal to ETc (92% ETc) whereas at Los Ebanos, water inputs exceeded ETc by about 35%. Onion yields ranged from 58.5 to 70.3 t ha⁻¹ but were not affected by drip tube emitter spacing. Onion pungency (pyruvic acid development) and soluble solids concentration were also not significantly influenced by treatments. Crop water use efficiency was slightly higher at Weslaco (13.7 kg/m³) than at Los Ebanos (11.7 kg/m³) partly because of differences in total water inputs resulting from differences in irrigation management. The absence of any significant effects of drip tape emitter spacing on onion yield may be due to the fact that irrigation was managed to provide roughly similar irrigation amounts and optimum soil moisture conditions in all treatments.     

毛乌素沙地地埋滴灌对紫花苜蓿生长指标的影响

通过研究毛乌素沙地地埋滴灌不同参数对紫花苜蓿生长指标的影响,确定最优的滴灌带埋深和灌水定额,进行了不同滴灌带埋深、不同的灌水定额对紫花苜蓿株高和产量的影响试验,得出滴灌带埋深20cm时相同灌水定额的紫花苜蓿的株高高于埋深10和30cm;灌水定额30mm滴灌带相同埋深处株高高于灌水定额15和22.5mm时的株高。滴灌带的埋深对紫花苜蓿的产量影响不大,埋深20cm处最高比10cm最低仅高产5.8%;灌水定额对产量影响较大,22.5比15mm增产30.4%,30比22.5mm增产18.4%。由此建议毛乌素沙地地埋滴灌滴灌带埋深应为20cm,灌水定额为22.5mm,在节水的同时达到增产的效果,有助于该地区水资源可持续利用。     

无机吸附剂处理黄河水滴灌抗堵塞试验研究

为了解决黄河水滴灌中泥沙处理的问题,利用黄河泥沙配置出高、中、低3种含沙量水质的试验组,采用“水梦”无机吸附剂泥沙分离装置过滤3种水质进行滴灌堵塞模拟试验,监测水质变化情况并进行滴灌的抗堵性试验;观测2种滴灌带沿程流量变化规律、滴灌系统均匀度以及系统相对平均流量变化规律.结果表明:经“水梦”无机吸附剂泥沙分离装置处理后,不同含沙量下水体中的浊度及各类污染物指标得到明显降低,其中总氮、总磷、COD,BOD、浊度平均降低了23.9%,40.3%,47.0%,38.3%,97.8%.模拟大田滴灌进行8次灌水试验,依据2种滴灌带试验过程中灌水均匀度及灌水相对平均流量的变化情况可知,在实际使用过程中应采用流量更大、滴头类型为内镶贴片式的滴灌带.     

渠道防渗防冻胀复合型保温塑料板的试验研究

提出了一种填充玉米秆碎粉的复合型聚氨酯泡沫保温塑料板,初步确定了其配方和制备工艺,通过试验研究了不同玉米秆碎粉粒径（0〈D≤0．45mm,0．45mm〈D≤1.50mm,1．50mm〈D≤4．00mm等3种规格）和填充量对聚氨酯泡沫塑料的密度、压缩强度和导热性能的影响,以及不同的填充量及粒径对聚氨酯泡沫塑料的发泡时间、发泡成型效果的影响．结果表明,当玉米秸秆碎粉粒径一定时,随着填充量的增加,填充玉米秸秆碎粉的聚氨酯泡沫保温材料的密度增大,但压缩强度下降;当玉米秆碎粉粒径为0．45mm〈D≤1．50mm．填充量为30％时,制备的复合型聚氨酯泡沫塑料板的压缩强度（10％压缩变形）为85kPa,导热系数为0．038W／（m·K）,尺寸变化率（-40～＋70℃）为±1％,能够满足渠道衬砌防渗工程中防冻胀破坏的性能要求．经测算,与不填充玉米秆碎粉的聚氨酯泡沫塑料板相比,复合型泡沫塑料保温板的成本可降低约25％,而且能够充分利用农业生产的废弃物,减少丢弃或焚烧这些废弃物对环境造成的污染．     

地下滴灌系统设计应用相关问题探讨

通过近年来国内外试验、示范、推广应用地下滴灌技术的实践经验,对地下滴灌系统规划设计、运行管理有关问题进行了总结和阐述,对滴灌管线的选取、适宜埋设深度的确定、灌水小区的冲洗、真空阀的设置、水质处理等地下滴灌系统设计应用常见问题逐一进行了说明,可为地下滴灌技术在我国的进一步推广应用提供参考。     

Water temperature and system pressure effect on drip lateral properties

A study was conducted at the department of Agricultural Structure and Irrigation, Harran University, Sanliurfa, Turkey, to determine the effect of increased irrigation water temperature at various irrigation system pressures on emitter flow rate, lateral elongation, and Standard Flow Rate Index for six different brands of drip laterals. Test materials consisted of seven pressure and seven non-pressure compensating irrigation laterals from different manufacturers. Tests results showed that (a) tensile resistance stress tests indicated that 25% elongation levels were reached at about 40 kg of load. On average, pressure compensating laterals reached 25% elongation at 38 kg, while non-pressure compensating laterals reached 25% elongation at 32-kg load. There was no clear indication of the tested brands’ lateral wall thickness on the measurement, (b) pressure-regulated drip emitters had no or limited flow rate change due to increased irrigation water temperature, whereas non-pressure compensating emitters had significantly (P < 0.05) increased flow rates, and (c) finally, increased irrigation water temperature resulted in decreased flow rate variations that had a positive effect on standard deviation. Standard uniformity values improved with decreased flow rate variations in drip emitter flow rates.