Surface runoff and soil erosion estimation using the SWAT model in the Keleta Watershed,Ethiopia     

D. Tibebe  W. Bewket 《Land Degradation \u0026amp; Development》2011,22(6):551-564

This study evaluates surface runoff generation and soil erosion rates for a small watershed (the Keleta Watershed) in the Awash River basin of Ethiopia by using the Soil and Water Assessment Tool (SWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. The simulated surface runoff closely matched with observed data (derived by hydrograph separation). Surface runoff generation was generally high in parts of the watershed characterized by heavy clay soils with low infiltration capacity, agricultural land use and slope gradients of over 25 per cent. The estimated soil loss rates were also realistic compared to what can be observed in the field and results from previous studies. The long‐term average soil loss was estimated at 4·3 t ha⁻¹ y⁻¹; most of the area of the watershed (∼80 per cent) was predicted to suffer from a low or moderate erosion risk (<8 t ha⁻¹ y⁻¹), and only in ∼1·2 per cent of the watershed was soil erosion estimated to exceed 12 t ha⁻¹ y⁻¹. Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the watershed was divided into four priority categories for conservation intervention. The study demonstrates that the SWAT model provides a useful tool for soil erosion assessment from watersheds and facilitates planning for a sustainable land management in Ethiopia. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

响应面试验优化霍山石斛原球茎增殖培养基     

郭慧慧  林丛发  蒋元斌  李志刚 《中国农业科技导报》2020,22(3):173-180

为可持续开发霍山石斛资源，采用响应面法优化霍山石斛原球茎增殖培养基。在单因素试验基础上，根据Box Behnken试验设计原理，采用三因素三水平的响应面分析法，以增殖率为响应值进行回归分析。结果表明，萘乙酸（简称NAA）及6 苄氨基嘌呤（简称6 BA）浓度对增殖率影响最为显著，6 BA与马铃薯两者间交互作用显著，适宜的NAA、6 BA及马铃薯浓度分别为0.05 mg·L-1、0.70 mg·L-1和185 g·L-1，此时增殖率为2 989.82%±205.55%，与模型预测值基本符合。响应面法优化霍山石斛原球茎增殖培养基切实可行。  相似文献   

朝鲜蓟发酵茶泡制工艺研究     

张婷  邓爱华  易梦媛  易明霞  李林峰  李青洋 《农产品加工．学刊》2020,(4):26-29

以感官评价为指标,通过单因素试验和响应面试验设计优化朝鲜蓟发酵茶泡制工艺。结果表明,朝鲜蓟发酵茶的最佳泡制工艺为冲泡时间22 min,加水量243 mL,冲泡水温86℃,粉碎度40目,在此条件下感官评分为90分。通过ABTS法和DPPH法检测表明,朝鲜蓟袋泡茶具有明显的抗氧化能力。  相似文献   

毛竹销（钉）的高速旋转摩擦焊接性能研究     

李素瑕    张海洋  程良松  鞠泽辉  卢晓宁 《西北林学院学报》2021,36(4):225-232

选取毛竹销钉替代木榫在1 500 r/min的情况下与榉木基材进行旋转摩擦焊接，对其抗拉强度和焊接机理进行研究。重点研究不同形状的预钻孔和不同榫径与孔径比值下的竹销钉焊接抗拉拔强度，并将其与木榫焊接和PVAc胶接的抗拉强度进行对比。结果表明:1）当采用恒定直径孔10/9、10/8、10/7、10/6 4种榫径/孔径比的焊接强度均高于PVAc胶接强度，但低于木荷榫和榉木榫的焊接强度，其中10/8的榫径/孔径比的焊接强度相对最高，达到了5.54 MPa；2）当采用渐变直径孔，竹销钉的焊接强度得到明显提高。其中10/8-6的榫径/渐变孔径比值取得了最高的焊接强度，达到6.42 MPa，比10/8比值的强度提高了15.6%，超过了木荷榫的焊接强度，但不及榉木榫的焊接强度；通过对竹销钉的焊接界面温度进行监测，发现焊接界面能在2 s内达到300℃以上的峰值高温，且维持了一定的高温时间（通常约2～3 s），随后随着竹销停止旋转摩擦，温度逐步下降；不同的榫径与孔径比值下，焊接界面的升温速率、峰值温度和高温持续的时间不同，它们是产生强度差异的主要原因；SEM观察结果显示，竹销旋转摩擦焊接界面由竹销或基材中的胞间层物质软化、熔化和流动并与作为增强材料的竹纤维包裹，形成了犹如“钢筋水泥土”结构般的致密、连续和坚固的焊接界面；FTIR分析结果表明，摩擦产生的高温会导致竹销中半纤维素发生一定程度的降解，纤维素的降级十分有限，木质素发生一定程度的缩合反应，木质素的含量相对提高。试验结果表明，将竹销钉代替木榫用于木材的旋转摩擦焊接是可行的。  相似文献   

政策认知、执行力度与资源化利用满意度——基于河北省380家生猪养殖主体调研数据(上)     

张明达  董璠  路怡宁  刘振涛 《猪业科学》2021,38(11):72-75

参与主体对于政策的评价是衡量政策实施效果的重要指标，探明政策参与主体满意度影响因素有助于了解主体自身需求，从而提高政策实施水平。文章基于对河北省380家生猪养殖主体调研数据，运用多元有序Logistic回归方法，分析生猪养殖主体自身政策认知以及相关政策执行力度对畜禽养殖主体废弃物资源化利用满意度的影响。结果表明：养殖主体资源化利用政策了解程度能够显著提升其资源化利用政策满意度；仅考虑养殖主体政策参与力度，随着参与力度增加，满意度亦会显著提升。但综合考虑其他因素，参与力度对于满意度提升效果则不再显著；养殖主体感知政策执行力度增加不利于政策满意度提升。此外，生猪养殖主体废弃物资源化利用政策了解程度增加，可以显著提升其报告资源化利用政策“满意”可能性。而单纯提高资源化利用政策执行力度并不能显著提高养殖主体资源化利用政策满意度。因此，要提高养殖主体政策满意度，应多渠道提升宣传力度，鼓励养殖主体积极参与，提高其参与意识，不断改善现有政策执行方式。  相似文献   

长江下游农区金花菜叶蛋白提取工艺优化及关键参数特征     

徐卓  陈震  吴桂成  杭杰  管永祥  孙政国 《草业科学》2020,(5):993-1001

为改进和优化金花菜(Medicago polymorpha)叶蛋白提取的工艺环节,并提高叶蛋白提取率及提取物纯度等参数指标,本研究选择长江下游农区广泛种植的金花菜为原料,通过设置较为合理科学的料液比、提取温度、加热时间、pH以及提取剂(酸)种类进行叶蛋白提取单因素试验。结果表明:各单因素试验最佳参数分别为料液比1∶3、提取温度70℃、加热时间15 min、pH 4、提取剂(酸)为盐酸。基于清洁安全生产角度,选择了单因素试验中提取指标同样较高的柠檬酸作为提取剂,设置了料液比、pH及提取温度的3因素3水平响应面试验,发现影响叶蛋白提取率的因素依次为pH、提取温度、料液比。得到最佳提取工艺:料液比1∶3、pH 4.1、提取温度72℃,相应的叶蛋白提取率为49.63%,提取物纯度为56.87%。本研究优化的技术工艺及相关参数指标可为农区豆科草类植物多元化利用及叶蛋白工业化生产提供一定的技术支撑和相关借鉴。  相似文献   

The use of the hand-held infrared thermometer as an early detection tool for exertional heat illness in Thoroughbred racehorses: A study at racetracks in eastern Australia     

M. Brownlow  T. Smith 《Equine Veterinary Education》2021,33(6):296-305

Thoroughbred racehorses perform exercise at maximal intensities and typically display a hyperthermic exercise response, which can drive core body temperature to critical levels. Despite extremely efficient thermoregulatory mechanisms, certain weather conditions may affect the horse’s ability to cool and result in a syndrome referred to as exertional heat illness (EHI). This is characterised by central nervous system dysfunction, as well as cytotoxic effects of heat on cells, which can produce deleterious consequences. Early detection of exertional heat illness (EHI) in Thoroughbred racehorses can be difficult because signs are often vague and the measurement of rectal temperature as an indicator of hyperthermia is not practical. Best practice in the treatment of EHI in horses, as in human subjects, centres on early detection, rapid assessment and aggressive cooling. Research in human subjects has shown that EHI is manageable when recognised early and appropriate treatment provided. The aim of this study was to investigate the measurement of skin surface temperature (SST) by an infrared thermometer as an aid in the early detection of EHI. A skin surface temperature ≥39°C in the immediate postrace period is considered to be hot. It reflects the interaction of exercise-related metabolic heat production, physiological adjustments to the skin surface such as vasodilation and sweating, together with the effect of high ambient temperature. Most importantly, high SST is associated with a reduced core-to-skin temperature difference, which retards heat transfer from the deep body tissues to the skin and can hinder heat dissipation. Identification of horses with high SSTs can prioritise them for rapid cooling and curtail possible progression to EHI.  相似文献   

Dough and bread made from high- and low-protein flours by vacuum mixing: Part 1: Gluten network formation     

《Journal of Cereal Science》2017

The effects of reduced headspace pressure on the development of gluten network in doughs made from both high-protein flour (HPF) and low-protein flour (LPF) were investigated. The effect of vacuum mixing was found to be dependent on both flour-type and mixing-time. A significant increase in dough extensibility was observed when the HPF dough was mixed under moderate vacuum of −0.04 MPa for 3 min as compared to the one mixed under atmospheric pressure for the same duration. This was attributed to the formation of a more extensive gluten network associated with an increased disulphide bond density and a significantly higher β-sheet to β-turn ratio. On the other hand, over-mixing was observed in the LPF dough that was mixed for 5 min under atmospheric pressure. Applying moderate vacuum of −0.04 MPa allowed the LPF dough to withstand longer mixing time, as indicated by its increased disulphide bond density and biaxial extensibility compared to the control dough mixed under atmospheric pressure. Results of this study suggest the potential of applying vacuum to reduce the mixing time required for high protein flour and to prevent the over-mixing of low protein flour.  相似文献   

甘蓝型油菜DH群体抗倒伏相关性状遗传分析     

黄文辉  王会  蔡鑫  汪文祥  付丽  胡琼  成洪涛  梅德圣 《中国油料作物学报》2018,40(1):18

为明确油菜抗倒伏性的遗传规律，本文利用抗倒伏性差异显著的2个甘蓝型油菜品系配制杂交组合，构建含280个株系的DH群体，采用作物茎秆强度抗倒测量仪等考种工具对该群体进行连续两年的抗倒伏性鉴定，并利用植物数量性状的主基因 + 多基因混合遗传模型及偏度和峰度分析对抗倒伏性进行遗传分析。结果表明，茎秆抗折力和茎秆抗折强度都受到0对主基因 + 9对微效多基因控制，茎秆抗折力和单株生物量的基因间无互作，茎秆抗折强度的基因间有互补作用，茎秆抗折力和茎秆抗折强度两年的平均遗传率在50%左右，而茎秆直径两年的平均遗传率为69.338 %，单株生物量两年的遗传率分别为52.198%和69.284%，遗传率都较低，性状受环境影响都较大，因此对于茎秆抗折力、茎秆抗折强度、茎秆直径和单株生物量，在育种选择的早期阶段都不宜太严格。同时茎秆抗折强度相比茎秆抗折力更能说明作物的抗倒伏能力，因而在抗倒伏选择育种时应更加关注。  相似文献   

苎麻单纤维断裂强力统计特征研究     

冷鹃  肖爱平  杨喜爱  程毅  廖丽萍  聂晴岚 《中国麻业》2014,(3):151-155

为了研究苎麻单纤维断裂强力的全貌与分布规律,通过采用等速伸长法测得其断裂强力,根据断裂强力的频数直方图的分布趋势,用正态分布的偏度、峰度等参数对其进行分析,用Q-Q图与Kolmogorov-Smirnov（以下简称K-S）检验法检验苎麻单纤维强力的正态性,总体上服从正态分布规律,但有一定偏差,不对称,为右偏尖峰态。同时提出了建立在统计基础上的苎麻单纤维断裂强力指标体系,即运用主体断裂强力、品质断裂强力、平均断裂强力、弱强纤维断裂强力和超强纤维强断裂力五个指标来表征单纤维断裂强力。  相似文献