高超声速风洞进气道流量系数测量精度影响因素研究

进气道是飞行器动力装置的重要组成部分,准确测量进气道流量系数是进气道风洞试验的重要内容。对来流马赫数Ma=4.5,5.0和6.0状态下皮托管进气道开展流量系数测量研究,通过对比理论值和实测值,获取各状态流量系数修正系数。试验结果表明,随着来流马赫数增加,进气道流量系数与理论值偏差较明显,并逐渐增大。超声速风洞试验通常认为测量截面总温与来流总温相等,通过对测量截面总温与来流总温偏差以及测量截面流场畸变情况的分析,判断测量偏差主要是由测量截面总温等于来流总温的假设导致的。在高超声速风洞试验中,由于模型壁面热交换的存在,测量截面总温低于来流总温,进气道流量系数测量时需要进行总温修正,以提高流量测量精度。      

燃烧加热污染空气对超燃冲压发动机性能影响研究

针对燃烧加热地面试验设备存在的工质污染问题,采用数值模拟方法研究了燃烧加热污染空气对氢燃料超燃冲压发动机性能的影响。以飞行马赫数Ma=6.5,当量油气比ER=0.6为计算基准状态,分别对纯净空气和污染空气来流下氢燃料超燃冲压发动机的整机流场和性能进行了对比计算分析。燃烧化学反应模拟采用了改进的H₂/O₂七组分八方程模型,湍流模型为标准的 k-ε模型,并采用直连式燃烧室试验数据进行了数值方法的验证。研究结果表明:(1)相对于纯净空气来流,污染空气来流下的超燃冲压发动机推力和比冲均有所下降。(2)采用酒精燃烧加热器的前提下,来流参数匹配静温、静压、马赫数时,发动机性能与纯净空气来流下的结果最为接近,而匹配总温、总压、马赫数时相差最大。(3)来流参数匹配总焓、静压、马赫数的前提下,采用氢燃烧加热器时发动机性能与纯净空气来流下的结果最为接近,而采用甲烷燃烧加热器时相差最大。      

壁面马赫数分布规律可控的新型内收缩基准流场设计方法

根据有旋特征线理论,设计出了沿程马赫数下降规律可控的轴对称基准流场,分析了基准流场的几何参数(前缘压缩角及中心体半径)的影响规律,发现选取较小的前缘压缩角和中心体半径有利于得到性能优良的基准流场;然后在设计状态Ma=6时研究了三种典型的马赫数下降规律对这种轴对称流场性能的影响。最后考虑了粘性的影响,并进行了粘性修正探索,结果表明,采用附面层位移厚度修正方法后,基准流场的壁面压力分布和无粘情况吻合良好。      

单层柱面网壳抗连续倒塌性能

研究了不同荷载布置形式、支承方式条件下,单层柱面网壳的抗连续倒塌性能和倒塌破坏模式,采用基于构件承载能力的敏感性评价指标,分析了初始缺陷、压杆失稳等因素对杆件、节点敏感性指标的影响。结果表明,当采用四边支承时,满跨均布荷载起控制作用,跨中节点为敏感构件,与之相邻斜杆为关键构件;当采用纵向两边支承时,半跨均布荷载起控制作用,杆件和节点的敏感性指标在1/3跨处最大,支座处最小。当考虑初始缺陷时,杆件、节点重要性系数分别增大了41%和53%;当考虑压杆失稳时,杆件和节点重要性系数分别增大了45%和62%。通过对关键构件进行加强,可以优化该类结构的抗连续倒塌性能。     

刚性陶瓷瓦热防护系统概率设计分析方法

针对高超声速飞行器中广泛应用的陶瓷瓦热防护系统,结合有限元法和蒙特卡洛模拟建立了其概率热分析系统,提出了刚性陶瓷瓦热防护系统尺寸概率设计方法。建立了刚性陶瓷瓦热防护系统的二维有限元模型,考虑了热传导系数、比热容和表面辐射率等材料属性参数以及热防护系统各层厚度的不确定性,得到系统温度场的概率分布特性和系统热防护性能对各参数的灵敏度,并对系统的热可靠性进行了评估。算例表明：文中提出的方法对热防护系统设计过程中合理确定陶瓷瓦厚度和在保证系统性能的前提下有效减轻重量具有指导价值。     

不同浓度营养液对烤烟漂浮育苗烟苗生长及生理特性的影响

试验采用漂浮育苗方式对K326包衣种子进行了不同浓度营养液对烤烟烟苗生长及生理特性的影响进行了研究。试验设8个处理（以氮含量计算）0,50,75,100,125,150,175,200mg／L。结果表明,播种后30d和35d,随着营养液浓度的增加,烟苗的株高、叶数、一级侧根、二级侧根、根体积和干物质重依次增加;播种后45d和50d,在100—150mg／L范围内烟苗的各生物学性状表现较好。播种后46d,随营养液浓度的增加,NR活性逐渐下降,除此以外,在0～125mg／L范围内可溶性蛋白质含量和NR活性在整个苗期随营养液浓度的增加逐渐上升,超过125mg／L又呈下降趋势;INV活性在整个苗期都呈先降后增趋势,在150mg／L时活性最弱。     

大豆生育期间抗倒伏性状变化规律的研究

抗倒伏性是大豆高产稳产研究的重要内容。选用黑农37和黑农42两个大豆品种为试验材料,在25万和35万株/hm ²密度条件下,对不同生育时期大豆茎秆的形态指标、茎秆基部挫折力等力学特性进行测定,较系统地研究了大豆生育期间抗倒伏性状变化规律。结果表明,大豆生育期间,随着株高和单株鲜重的变化,植株重力力矩呈单峰曲线变化,R₅-R₆期达到峰值,茎粗和茎秆基部挫折力也呈现相同的变化规律;而抗倒伏系数是大豆茎秆力学特性的综合表现,呈现U型变化,在R₅-R₆期最小,表明该期间最易倒伏;大豆株高、单株鲜重、植株重力力矩与抗倒伏系数呈极显著负相关,大豆茎粗、基部茎秆挫折力、弹性模量与抗倒伏系数呈极显著正相关,表明大豆株高越低、单株鲜重越小、重力力矩越小、茎粗越粗、茎秆挫折力及弹性模量越大,大豆抗倒伏性越强。供试的两种密度条件下,大豆单株鲜重、茎粗、茎秆基部挫折力、重力力矩、抗倒伏系数等性状,35万株/hm ²处理明显低于25万株/hm ²处理,表明随种植密度增加,大豆倒伏风险增大。     

能见度对飞机低空飞行及作业的影响

低空飞行是指在100-1 000 m范围内的飞行活动,超低空飞行是指在100 m以下的飞行活动,在低空飞行中,能否看清地物,直接影响着飞行安全。新疆通用航空公司由于执行兵团范围的通用航空任务多集中在超低空,因此,能见度对完成作业飞行任务至关重要。本文从两个方面加以阐述,并提出了低能见度条件下保证安全飞行的建议。     

重庆村镇空气源热泵供暖系统夜间性能实测分析

针对重庆山地村镇迫切的供暖需求,选取该地区典型村镇搭建了空气源热泵供暖系统实验平台,分析了空气源热泵系统性能影响因素,并从供回水温度、系统耗电量、供热量、性能系数COP等角度对运行过程中的阶段特性(启动、稳定运行及全阶段)进行阐述,发现系统在3个阶段特点差异很大：启动阶段初始温度对COP影响较为明显,除霜时系统性能下降25%;稳定阶段特性与初始温度无关,室外条件较好时,降低设定温度,COP提高明显;总体来看,启动阶段COP最高,全阶段次之,稳定阶段COP最低。     

飞行救生饮用水包装材料加速老化试验及其寿命预测

以飞行救生饮用水的包装材料为研究对象,进行包装材料加速老化试验,根据阿列纽斯反应速率函数预测包装材料的寿命,在55℃下恒温存放飞行救生饮用水,并定期抽样测定其包装材料的相关性能指标(氧气透过率、水蒸气透过率、拉伸强度、断裂伸长率、剥离强度、封合强度、残留溶剂)。研究结果表明,飞行救生饮用水在55℃存放39周,其相关性能均符合规定指标。推算出飞行救生饮用水包装材料在常温下的寿命相当于6年。     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

Optimization of Extraction Technology and Determination of Content of Total Phenols of Leaves in Acanthopanax giraldii Harms

[Objectives] To determine the optimum extraction technology for total phenols of leaves in Acanthopanax giraldii Harms.[Methods]The single factor test and ortho...     

Cytoplasmic male sterility,resistance to gall mite and mildew,and season of leafing out in black currants

Summary Cytoplasmic male sterility (cms) is described in the F₁ hybrids Ribes × carrierei (R. glutinosum albidum × R. nigrum) and R. sanguineum × R. nigrum. In backcrosses to R. nigrum, progenies with R. glutinosum cytoplasm were either all male sterile, or segregated for full male fertility (F) and complete (S) and partial (I) male sterility. Ratios of F:I+S suggested that two linked genes controlled cms, F plants being dominant for one (Rf ₁) and recessive for the other (Rf ₂).Segregation for cms in relation to three linded genes, Ce (resistance to the gall mite, Cecidophyopsis ribes), Sph ₃(resistance to American gooseberry mildew, Sphaerotheca mors-uvae) and Lf ₁(one of two dominant additive genes controlling early season leafing out) indicated that Rf ₁and Rf ₂were in this linkage group. The gene order and approximate crossover values appeared to be: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqef0uAJj3BZ9Mz0bYu% H52CGmvzYLMzaerbd9wDYLwzYbItLDharqqr1ngBPrgifHhDYfgasa% acOqpw0xe9v8qqaqFD0xXdHaVhbbf9v8qqaqFr0xc9pk0xbba9q8Wq% Ffea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dme% aabaqaciGacaGaamqadaabaeaafaaakeaacaWGdbGaamyzamaamaaa% baGaaiiiaiaacccacaGGWaGaaiOlaiaacgdacaGG0aGaaiiiaiaacc% caaaGaaiiiaiaacccacaGGGaGaamOuaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaaccdacaGGUaGaaiOmaiaacs% dacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaaaacaWGsbGaamOzaSGa% aGOmaOWaaWaaaeaacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccaaaGaamitaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccacaGGGaaaaiaadofacaWGWbGaamiAaSGa% aG4maaaa!6E4D!\[Ce\underline { 0.14 } Rf1\underline { 0.24 } Rf2\underline { } Lf1\underline { } Sph3\]. Crossover values of 0.36 for Ce-Lf ₁, and 0.15 for Lf ₁-Sph ₃were estimated from the relative mean differences in season of leafing out between seedlings dominant and recessive for Ce and Sph ₃.It is suggested that competitive disadvantage of lf ₁-carrying gametes and/or zygotes at low temperatures may be implicated in the almost invariable deficit of plants dominant for the closely linked mildew resistance allele Sph ₃. Poor performance of lf ₁- (and possibly lf ₂-) carrying gametes and young zygotes during periods of low temperature at flowering might also account for the liability of some late season cultivars and selections to premature fruit drop (running off).     

Screening techniques and sources of resistance to parasitic angiosperms

Parasitic angiosperms cause great losses in many important crops under different climatic conditions and soil types. The most widespread and important parasitic angiosperms belong to the genera Orobanche, Striga, and Cuscuta. The most important economical hosts belong to the Poaceae, Asteraceae, Solanaceae, Cucurbitaceae, and Fabaceae. Although some resistant cultivars have been identified in several crops, great gaps exist in our knowledge of the parasites and the genetic basis of the resistance, as well as the availability of in vitro screening techniques. Screening techniques are based on reactions of the host root or foliage. In vitro or greenhouse screening methods based on the reaction of root and/or foliar tissues are usually superior to field screenings and can be used with many species. To utilize them in plant breeding, it is necessary to demonstrate a strong correlation between in vitro and field data. The correlation should be calculated for every environment in which selection is practiced. Using biochemical analysis as a screening technique has had limited success. The reason seems to be the complex host-parasite interactions which lead to germination, rhizotropism, infection, and growth of the parasite. Germination results from chemicals produced by the host. Resistance is only available in a small group of crops. Resistance has been found in cultivated, primitive and wild forms, depending on the specific host-parasite system. An additional problem is the existence of pathotypes in the parasites. Inheritance of host resistance is usually polygenic and its transfer is slow and tedious. Molecular techniques have yet to be used to locate resistance to parasitic angiosperms. While intensifying the search for genes that control resistance to specific parasitic angiosperms, the best strategy to screen for resistance is to improve the already existing in vitro or greenhouse screening techniques.