基于Copula 函数的边坡可靠度高效分析方法

将Copula函数与高效蒙特卡洛方法结合,提出了含相关随机变量的边坡可靠度高效分析方法。以两个岩质边坡稳定性问题为例验证了所提方法的有效性。结果表明,该方法相比于直接蒙特卡洛方法在保证边坡失效概率的准确性的同时计算效率更高。Copula函数可以构造出具有不同相关结构的岩土体参数的联合概率分布,与高效蒙特卡洛方法(即蒙特卡洛重要抽样方法和子集模拟)结合能高效地处理含多种相关随机变量的边坡可靠度计算问题,相比于现行的Nataf变换方法结果更能体现岩土边坡真实稳定性。此外,该方法也能高效地计算含有复杂的隐式功能函数的边坡可靠度,研究成果拓展了高效蒙特卡洛方法在边坡可靠度分析中的应用。     

Effect of microwave pre-treatment on physical quality,bioactive compounds,safety risk factor,and storage stability of peanut butter

Microwave, as a new heat treatment technology, has the characteristics of uniform and fast heating speed. It is an energy-saving technology known for improving oilseed product quality. Its efficiency mainly depends on the roasting power and time. However, the production of high-quality peanut butter using short-time roasting conditions are limited. Herein, we determined an appropriate microwave roasting power and time for peanuts and evaluated its impacts on the quality of peanut butter. Different roasting powers (400 ​W, 800 ​W and 1200 ​W) and times (4, 4.5, 5, and 5.5 ​min) were preliminarily tested. Among them, 800 ​W at 5 ​min was the most suitable. The roasting efficiency was further evaluated using color, sensory, bioactive compounds, storage stability, and safety risk factors of peanut butter produced from four peanut cultivars (Silihong, Baisha-1016, Yuanza-9102, and Yuhua-9414). The pre-treated butter obtained from three cultivars (Silihong, Yuanza-9102, and Yuhua-9414) with moisture content between 5% and 7.2% had a similar sensory score (6–7) as the commercial on a 9-point hedonic scale compare to the other. The color of the pre-treated peanut butter varies statistically with the commercial but remained in the recommended range of Hunter L1 values of 51–52, respectively, for high initial moisture peanut cultivars. The total polyphenol (35.20-31.59 ​± ​0.59 ​μmol GAE/g) and tocopherol (19.05 ​± ​0.35 ​mg/100 ​g) content in the butter obtained from three cultivars (Yuahua-9102, Yuhua, and Baisha-1016) and Silihong respectively, were significantly (P ​< ​0.05) higher than those in the commercial butter. The induction times of all pre-treated butter (19.80 ​± ​0.99–7.84 ​± ​0.07 ​h) were significantly (P ​< ​0.05) longer during storage at accelerated temperature than commercial samples. In addition, no benzo[a]pyrene was found in the pre-treated samples. Collectively, the microwave pretreated peanut butter was superior to the commercial one. These findings provided data support and a reference basis to promote microwave use for peanut butter production.     

乡土物种补播对青藏高原高寒草甸群落稳定性的影响

为了探究高寒草甸天然草地补播乡土物种对草地群落稳定性的影响，本试验以垂穗披碱草（Elymus nutans）、异针茅（Stipa aliena）、中华羊茅（Festuca sinensis）、溚草（Koeleria cristata）、星星草（Puccinellia tenuiflora）、扁蓿豆（Melissitus rutenica）、冷地早熟禾（Poa crymophila）为试验材料，设置5种混播组合，于2017年在青海省贵南县天然草地上进行补播。试验采用方差比率法（Variance ratio，VR）、M.Godron贡献定率法（Contribution law）以及生物量稳定性分析方法，结果表明：5种组合补播后使得群落联结性降低、生物量稳定性增大，群落整体稳定性增强，正向着稳定方向发展；5种组合中，组合D （扁蓿豆+星星草+垂穗披碱草+异针茅+溚草）的生物量稳定性最大，是对草地恢复最有效的物种组合。本试验筛选出了对草地生态修复最有效的物种组合，为草地保护及利用提供了科学依据。     

基于粗糙遗传算法在打捆机齿轮箱故障诊断中的应用*

自走式连续作业打捆机是一款实现不停机连续打捆作业的新型秸秆收集装备,其关键功能部件齿轮箱发生故障会严重影响正常打捆工作。针对齿轮箱故障的防控和监测,提出一种结合粗糙集和遗传算法的故障诊断方法。该方法使用时域频域分析得到的多项故障特征参数作为条件属性,故障类型作为决策属性,并利用自适应遗传算法得到决策规则表,实现无需先验信息的属性约简和故障诊断。在齿轮箱故障诊断试验中,分别对不同故障类型进行信号采集和诊断分析,结果显示:该方法在无先验信息的条件下将12项故障特征参量约简为3项,根据决策规则表进行故障诊断的准确率为100%,结果表明该方法能准确判断故障的发生和故障类型,对实现故障监测和防控具有重要意义。     

Effect of farm management on topsoil organic carbon and aggregate stability in water: A case study from Southwest England,UK

There are few reliable data sets to inspire confidence in policymakers that soil organic carbon (SOC) can be measured on farms. We worked with farmers in the Tamar Valley region of southwest England to select sampling sites under similar conditions (soil type, aspect and slope) and management types. Topsoils (2–15 cm) were sampled in autumn 2015, and percentage soil organic matter (%SOM) was determined by loss on ignition and used to calculate %SOC. We also used the stability of macroaggregates in cold water (WSA) (‘soil slaking’) as a measure of ‘soil health’ and investigated its relationship with SOC in the clay‐rich soils. %SOM was significantly different between management types in the order woodland (11.1%) = permanent pasture (9.5%) > ley‐arable rotation (7.7%) = arable (7.3%). This related directly to SOC stocks that were larger in fields under permanent pasture and woodland compared with those under arable or ley‐arable rotation whether corrected for clay content (F = 8.500, p < .0001) or not (F = 8.516, p < .0001). WSA scores were strongly correlated with SOC content whether corrected for clay content (SOC_adj R² = .571, p < .0001) or not (SOC_unadj R² = 0.490, p = .002). Time since tillage controlled SOC stocks and WSA scores, accounting for 75.5% and 51.3% of the total variation, respectively. We conclude that (1) SOC can be reliably measured in farmed soils using accepted protocols and related to land management and (2) WSA scores can be rapidly measured in clay soils and related to SOC stocks and soil management.     

小球藻遗传转化技术研究进展

小球藻( Chlorella )是一种单细胞真核藻类,属绿藻门、绿藻纲、绿球藻目、小球藻科、小球藻属 [1] 。作为最早开发的真核微藻之一,具有高营养价值、生长快速、结构简单、易工业化集成等显著优点。其细胞形态为球形或椭圆形,直径3~12 μm,呈单生或聚集成群状生长 [2] ,分布广泛,多见于淡水、咸水和土壤中。作为地球上最早的生命之一,小球藻基因比较稳定,至今未见有关其基因自发突变的报道。因其富含蛋白质、脂质、维生素、活性代谢产物等多种营养物质而被公认为具有高附加值和医疗保健作用,已经被广泛应用于保健食品 [3] 、水产养殖 [4] 、生物能源 [5] 等方面,关于小球藻生物技术的研究主要集中在基因组学 [6] 、分子遗传学 [7] 、代谢机理 [8] 、大规模培养 [9] 等方向。     

考虑水头损失的管道灌溉分水口轮灌分组优化模型

【目的】优化灌溉系统中分水口轮灌分组的灌溉制度,在满足流量要求的条件下节约电能。【方法】提出了在考虑水头损失时不同分水口状态与管道进口压力的关系模型,该模型利用分水口开关0,1状态作为自变量,从管道末端起利用推导的递推公式求出管道进水口的等效水头损失系数。依据该模型,在定流量分组轮灌优化中得到为使分组轮灌功率最小的目标函数。利用遗传算法对上述问题进行了优化求解,并给出了编码方案。【结果】在分水口等间隔布置时,轮灌分组按轮灌分组数等间隔安排所需功率最小,优化后的水头损失系数可以减小到没有优化前的0.772倍。【结论】本研究模型不仅适用于恒定流量的组合优化,也可应用于不同分水口的所需水量不同的随机灌溉以及恒压供水的优化中。     

小麦山农4143抗黑胚病遗传分析及抗性遗传位点检测

 黑胚病是小麦生产的重要籽粒病害,麦根腐平脐蠕孢(Bipolaris sorokiniana)是黑胚病的主要致病菌。为分析小麦抗黑胚病遗传规律并检测抗性位点,本研究以抗黑胚病小麦品系山农4143与感病品系宛原白1号的F₇代重组自交系(RIL)群体为材料,于2018~2019年在3个试验点种植,采用“孢子液喷洒、套袋保湿”的方法进行接菌鉴定,用“主基因＋多基因混合遗传模型”进行遗传分析,并挑选极端抗、感自交系构建混池、结合小麦660K SNP芯片进行混合分组分析(BSA)。研究结果显示小麦品系山农4143对黑胚病抗性符合“4对主基因加性-上位性遗传模型”,主基因遗传力为0.88~0.95;通过BSA检测到黑胚病抗性位点36个,分别位于1A、2B(6)、2D(2)、3A、3B(2)、3D、4A(6)、4D、5A(4)、5B(6)、5D(3)、7A、7B和7D共14条染色体上,A、B、D染色组上分别为13、 15和8个,36个位点中有18个为抗黑胚病新鉴定位点。本研究结果为小麦抗黑胚病位点的精细定位和抗性育种中分子标记的开发奠定了基础。     

Genetic variation of seedling traits responded to brassinosteroid and gibberellin inhibitors in maize (Zea mays) doubled haploid lines

The purpose of this study was to examine the genotypic variation in maize doubled haploid (DH) lines response to brassinosteroid and gibberellin inhibitors. Plant responses to hormone inhibitors were determined in growth chamber experiments using germination paper for three different seedling treatments: application of propiconazole (Pcz), uniconazole (Ucz) or water (control). Mesocotyl length (ML) was more sensitive to hormone inhibitors, especially to the Ucz treatment, than other seedling traits. ML was significantly correlated with other traits in the Ucz treatment. All the seedling traits showed moderate-to-high broad sense heritability values, ranging from 0.39 to 0.82. The Euclidian genetic distances of inbred line pairs ranged from 1.27 to 19.94, indicating there was a high level of variability across the maize DH lines used in this study. DH lines with extreme MLs were identified, which can provide valuable breeding resources for improving abiotic stress tolerance, and for further genetic studies.