以氧化诱导期为性能变化指标推算三元乙丙橡胶O型密封圈的贮存寿命

商品化的橡胶制品常常由于尺寸小、异形等原因难以使用传统的力学性能作为寿命推算的性能指标,为了解决这一问题,文中首次提出将氧化诱导期(OIT)作为性能变化指标来推算三元乙丙橡胶O型密封圈的贮存寿命.分别在80℃,100℃,120℃,140℃和160℃对EPDM O型圈进行数小时至2年的热空气加速老化,测试老化前后样品的拉伸强度、断裂伸长率及氧化诱导时间.研究结果表明,随着老化时间的延长和老化温度的升高,OIT的变化趋势与拉伸强度和断裂伸长率一致;使用OIT作为性能变化指标计算出的EPDM O型圈的贮存寿命为28.6年,与以拉伸强度为性能变化指标时基本一致,充分证明了以OIT作为寿命推算指标的可行性,解决了微小或异形制品的寿命估算难的问题.     

药用低密度聚乙烯膜拉伸性能测试的不确定度评定

目的 对药用低密度聚乙烯膜的拉伸强度和断裂伸长率的测试结果进行不确定度评定。方法 依据JF1059.1-2012《测量不确定度评定与表示》,分析测量拉伸性能方法的不确定度来源,建立数学模型量化不确定度分量,计算合成标准不确定度。结果 拉伸强度的测量不确定度,纵向为（17±1）MPa,k=2;横向为（38±2）MPa,k=2。断裂伸长率的测量不确定,纵向为（181±5）%,k=2;横向为（470±23）%,k=2。结论在温湿度等条件不变的情况下,重复性测量对于不确定度结果的影响最大。     

氧化石墨烯/炭纤维复合增强体的制备及对环氧树脂复合材料界面性能影响

为了改善炭纤维/环氧树脂复合材料的界面性能,以对硝基苯胺为原料,通过两步重氮化还原反应,在炭纤维表面共价接枝氧化石墨烯,制备出氧化石墨烯/炭纤维(GO/CF)复合增强体。研究了反应机理,并对改性前后炭纤维表面的化学结构、微观形貌、表面粗糙度、单丝拉伸强度和炭纤维/环氧树脂复合材料的界面性能等进行了测试分析。结果表明,接枝GO后,炭纤维表面粗糙度增加了188%,单丝拉伸强度提高了13. 2%,断裂伸长率增加12. 1%,界面黏结强度提高了80. 2%。     

淀粉氧化改性对可剥离去污膜的性能影响研究

通过对淀粉进行氧化改性,研究了氧化淀粉对以聚乙烯醇为基体的去污膜相关性能的影响。红外光谱分析表明,氧化淀粉在1733cm-1处有羧基吸收峰产生,10%氧化淀粉制备的去污液稳定时间可达到1673h,去污膜拉伸强度为29.32MPa,断裂伸长率为238%,在400~800nm波长范围内透光率可达到85%以上,对不同材质样片的平均去污率可达80%以上。     

交联聚四氟乙烯的拉伸性能及结构研究

在温度为335℃±5℃氮气气氛条件下,利用电子束辐照制备交联的聚四氟乙烯(XPTFE)。利用拉伸试验机研究XPTFE的拉伸性能,并通过多种技术手段研究其结构变化。结果表明:与PTFE相比,XPTFE的透明度及屈服强度增加,拉伸强度和断裂伸长率降低。随吸收剂量的增加,XPTFE的拉伸强度及屈服强度逐渐增加,断裂伸长率、熔点及结晶焓降低。XPTFE具有交联的网状结构。     

PVA胶带的制备及力学性能研究

目的用水溶PVA薄膜代替不可降解BOPP薄膜作为胶带基材。方法试验分别测试PVA和BOPP薄膜(未涂布)的拉伸强度和断裂伸长率,涂布水性压敏胶的PVA和BOPP薄膜以及涂布热熔胶的PVA薄膜的拉伸强度、断裂伸长率、初粘性和180°剥离强度。结果 BOPP薄膜的拉伸强度为34.32 N/cm,略高于PVA薄膜,但是BOPP薄膜的断裂伸长率低于PVA薄膜;BOPP胶带、PVA热熔胶带、PVA水性胶带的拉伸强度分别为48.38,63.68,32.94 N/cm,BOPP胶带的断裂伸长率同时低于PVA热熔胶带和PVA水性胶带;BOPP胶带的初粘性略高于PVA水性胶带;BOPP胶带、PVA热熔胶带、PVA水性胶带的180°剥离强度分别为1.58,6.48,2.63 N/cm。结论与BOPP胶带相比,PVA胶带的拉伸强度、断裂伸长率、初粘性和180°剥离强度均可满足封箱胶带对力学性能的要求。     

氧化石墨烯改性环氧树脂的制备及性能研究

以环氧树脂、二乙醇胺为原料制备阳离子型环氧乳液,然后与氧化石墨烯充分混合形成共混分散液,加热固化得氧化石墨烯改性环氧树脂(GO/EP)涂层。其表面官能团结构、表面形貌分别通过傅里叶红外光谱仪(FT-IR)和扫描显微镜(SEM)进行表征,湿润性、热稳定性、力学性能分别通过接触角测试仪、热失重仪(TGA)和微机电子万能试验机进行测试。结果表明,氧化石墨烯加入环氧树脂基体中后涂层材料的力学性能较纯环氧树脂明显提高,其拉伸强度、断裂伸长率以及弹性模量最大提高率分别为69.2%,62.8%和22.8%。     

硅胶胰肠吻合器的制备及性能研究

以甲基乙烯基硅橡胶为基体材料,植入钛钉,一次设计成型胰肠吻合器。通过红外光谱(FT-IR)对其结构进行表征;通过力学性能实验对其拉伸强度和断裂伸长率进行测试;通过耐介质性测试观察其接触到水、酒精及双氧水的性能变化;通过环氧乙烷灭菌测试其灭菌前后力学性能的变化。结果表明:吻合器断裂伸长率和拉伸强度达282.6%和2.17MPa,经过蒸馏水、75%酒精、3%双氧水,NaOH(pH=9)和HCl(pH=0.8)浸泡的吻合器表观无变化,质量损失最大值仅为5.63%;且可经受环氧乙烷灭菌测试。硅橡胶因其生理无毒性可以用来制作吻合器,并能满足各指标要求。     

累托石/海藻酸钠插层纳米复合膜的制备与性能

采用水溶液法制备了钠化累托石(Na+REC)与海藻酸钠(SA)插层纳米复合膜(Na+REC/SA)。以红外光谱(IR)、X射线衍射(XRD)分析了复合膜的分子结构,通过电镜扫描(SEM)及原子力显微镜(AFM)观察了复合膜的相貌结构,研究了复合膜的热性能及力学性能。结果表明,Na+REC在添加量较少时可与SA形成插层型纳米复合膜,该复合膜与纯SA膜相比,具有较高的拉伸强度、断裂伸长率及热稳定性。在Na+REC添加2%时,复合膜的拉伸强度、断裂伸长率及热稳定性最高,与纯SA膜相比,拉伸强度提高58.7%,断裂伸长率提高100%,10%失重率时对应的热分解温度提高了115℃,40%失重率时提高了185℃。     

密胺树脂包覆氢氧化镁及其阻燃硅橡胶的研究

通过采用原位聚合法以密胺树脂为囊材包覆于Mg(OH)_2表面,形成微胶囊化Mg(OH)_2阻燃剂,将阻燃剂以不同组分添加至硅橡胶中,并与纯硅橡胶试样进行对比测试。通过傅里叶红外测试、氧指数、拉伸、断面扫描对其进行测试,研究发现,傅里叶红外测试得到阻燃剂中含有密胺树脂,氧指数提高27%,随着阻燃剂的加入会使材料的拉伸强度下降,添加40份时断裂伸长率提高49%,对比硅橡胶中添加40份未经过改性的Mg(OH)_2样条,氧指数提高23%,拉伸强度提高16.3%,断裂伸长率提高21%,扫描电镜观察脆断断面可看出经过微胶囊化处理的阻燃剂具有更好的分散性和与基体的相容性。     

Waterlogging in irrigation projects

Waterlogging is a complex environmental management problem in irrigation projects. Using two irrigation projects as examples the factors contributing to waterlogging have been identified. Policy interventions needed for reducing waterlogging in irrigation projects are identified, such as promoting conjunctive use of surface and ground water, and public demonstration programmes.     

An irrigation scheduling algorithm for sustainable energy consumption in pressurised irrigation networks supplied by photovoltaic modules

To meet water demands, pressurised irrigation networks often need pumping devices, whose power demand varies with the pump head, the flow rate delivered and the pump efficiency. To satisfy the energy demand of pumps, solar photovoltaic panels can be used as a renewable energy source. Since the electricity supply of a solar photovoltaics plant depends on irradiance, the energy that powers the pump varies with the time of the day. This study presents a strategy for scheduling water delivery by irrigation pumps, synchronising energy production in solar photovoltaic modules and minimising the installation size. An optimisation algorithm is proposed, which changes the energy required by pumping devices and adjusts them to the available solar energy supply, minimising the number of panels required. This problem applies to a pressurised irrigation network, where the utility manager may irrigate crops at all hours of the day. By adopting the proposed algorithm, irrigation will follow a rigid rotation schedule to follow the new irrigation plan. This approach improves earlier studies by employing a least-square scheduling algorithm with little computing time. This results in a tool for managers and decision-makers when evaluating the possibility of converting their irrigation network into a stand-alone system supplied by photovoltaic panels. A case study handling this issue in the University of Alicante’s pressurised irrigation network in Spain is proposed to find potential energy savings by connecting the recommended scheduling irrigating plan to the present operation.

Graphical abstract

     

Nonlinear water transport in intrasoil irrigation

Solutions have been obtained for nonlinear capillary diffusion from instantaneous planar, line, and point sources with allowance for plant root uptake.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 6, pp. 982–988, June, 1988.     

Steady flow simulation in irrigation canals

A mathematical model is developed for the analysis of spatially varied steady flow in irrigation canals. The model accounts for canal seepage and effect of control structures at the upstream and downstream ends of the canal. Two computational methods developed to solve the spatially varied steady flow equations for the irrigation canals are presented here. The governing differential equations are solved iteratively using fourth order explicit Runge-Kutta method. The model results are verified with experimentally observed water surface profiles available in literature. The effects of bed seepage, canal condition and backwater curves on the discharge carrying capacity and variation of flow depth are studied through model application on a canal reach. It is found, that in most of the situations the backwater curves spread sufficiently upstream and significantly affect the performance of the control structure at the upstream end. In many situations, it may not even be possible to operate the canal at design discharges.     

Minimum irrigation density of vartical film apparatus

The minimum irrigation density of a film heat exchanger is studied in relation to the temperature regime, the roughness of the wall surface, its material, and certain structural features of the distributor.     

A horizontal axis sail windmill for use in irrigation

This paper describes some basic considerations in the design and development of a horizontal axis windmill intended primarily for irrigation in small farms from shallow open wells. This windmill has six triangular sails sweeping a circle of 10 m diameter and is an adaptation from Greek sail windmills. For the construction of this windmill all efforts were made to use materials and parts readily available in the hardware market except for the gear boxes. The cost of material and the parts is Rs. 7,000/- excluding the cost of machining and fabrication. Preliminary performance tests have indicated a pumping rate of 6000–11000 litres/hr over a head of 6.85 m in wind speeds of 10–16 km/hr.     

精量灌溉中的植物水分精密诊断技术

针对目前我国水资源短缺的现状,提出基于植物水分诊断检测技术的闭环反馈控制节水灌溉系统.该系统的关键技术是研究可同时精确测量叶片厚度和温度的双参数融合式传感器,厚度测量的传感器原理实验已经完成.