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1.
池塘氮、磷浓度及藻相水色的研究 总被引：3，自引：0，他引：3
对池塘氮、磷浓度及藻相水色进行研究．水质培育实验结果表明,氮、磷储存量接近的池塘,由于所处生物、化学动态循环阶段不同,水中铵态氮、磷酸盐磷浓度差异甚大．池塘藻相水色与水中铵态氮、磷酸盐磷浓度及浓度比值有关．养殖池塘平均铵态氮／磷酸盐磷（７０８）比ＴＮ／ＴＰ（２２９）更接近比值约为７的淡水藻类氮、磷重量比的平均组成（８）． 相似文献
2.
设计了4种不同水胶比(0.52、0.48、0.44、0.40)自密实混凝土试件(N1、N2、N3、N4),分别在不同养护龄期(7、14、28、56、84、112 d)时进行超声波速与抗压强度的测试,得出强度与波速随龄期增长的变化规律,并根据其变化规律作回归分析,获得合适龄期内两者的函数关系。结果表明:试件抗压强度随养护龄期延长而增加,增长速率逐渐下降;在一定龄期内,强度与波速存在密切的内在联系,又因不同水胶比的试件波速增长速率不同,故回归方程不同;水胶比为0.52的自密实混凝土以幂函数拟合性最好,水胶比为0.48、0.40自密实混凝土则以指数函数最优,而对于水胶比为0.44的自密实混凝土,线性函数最佳;建立无损模拟曲线方程,可为预测适用本地区低水胶比自密实混凝土强度提供理论支持,也为检测加固工程中自密实混凝土质量问题提供了数据支撑。 相似文献
3.
Qi-fa Zhou Zhan-yu Liu Jing-feng Huang 《Journal of Zhejiang University. Science. B》2010,11(6):465-470
The main objective of this work was to compare the applicability of the single leaf (the uppermost leaf L1 and the third uppermost
leaf L3) modified simple ratio (mSR705 index) and the leaf positional difference in the vegetation index between L1 and L3 (mSR705L1-mSR705L3) in detecting nitrogen (N)-overfertilized rice plants. A field experiment consisting of three rice genotypes and five N fertilization
levels (0, 75, 180, 285, and 390 kg N/ha) was conducted at Xiaoshan, Hangzhou, Zhejiang Province, China in 2008. The hyperspectral
reflectance (350–2500 nm) and the chlorophyll concentration (ChlC) of L1 and L3 were measured at different stages. The mSR705L1 and mSR705L3 indices appeared not to be highly sensitive to the N rates, especially when the N rate was high (above 180 kg N/ha). The
mean mSR705L1-mSR705L3 across the genotypes increased significantly (P<0.05) or considerably from 180 to 285 kg N/ha treatment and from 285 to 390 kg N/ha treatment at all the stages. Also, use
of the difference (mSR705L1-mSR705L3) greatly reduced the influence of the stages and genotypes in assessing the N status with reflectance data. The results of
this study show that the N-overfertilized rice plants can be effectively detected with the leaf positional difference in the
mSR705 index. 相似文献
4.
薄片漏斗试样的应变等效换算与Zr-4合金疲劳寿命估算 总被引：1，自引：0，他引：1
完成了Zr-4合金薄片漏斗小试样的横向等幅应变疲劳试验;提出了薄片漏斗试样细腰部与薄片等直试样疲劳损伤等效的局部损伤等效假设;基于弹塑性有限元分析,建立了Zr-4合金薄片漏斗小试样横向测试应变向轴向应变转换的应变等效转换模型,该模型考虑了几何效应和泊松效应;结合实验结果,提出了用于Zr-4合金应变疲劳寿命估算的Manson-Coffin(M-C)模型。研究表明:薄片漏斗小试样及其应变等效转换模型可以有效应用于薄片金属材料的低周疲劳试验和寿命估算;国标推荐的应变换算公式应用于薄片漏斗小试样的Zr-4合金疲劳寿命估算会带来很大安全余量。 相似文献
5.
Giant magnetostrictive actuators （GMAs） often work in a close-loop feedback system. This system needs independent sensors which may be difficult to be fixed, besides, excessive sensors may cause more unpredicted problems in a large system. This paper aims to develop a self-sensing GMA. An observer based on piezomagnetic equations is constructed to estimate the stress and strain of the magnetostrictive material. The observer based self-sensing approach depends on the facts that the magnetic field is controllable and that the magnetic induction is measurable. Aiming at the nonlinear hysteresis in magnetization, a hysteresis compensation observer based on Preisach model is developed. Experiment verified the availability of the observer approach, and the hysteresis compensation observer has higher tracking precision than linear observer for dynamic force sensing. 相似文献
6.
辉县市玉米“3414”肥料效应研究 总被引：2，自引：0，他引：2
根据玉米氮、磷、钾＂3414＂回归设计田间试验测得的数据,分别建立以玉米产量为目标函数的NPK、NP、NK、PK、N、P、K 3类7种肥力效应模型,求出每种肥效模型的高产最优施肥量,在此基础上,进一步对各种施肥模型提供的施肥量及产量期望的经济效益分析,决选出辉县市玉米生产的推荐施肥量为：施纯N 252.54 kg/hm2、P2O5 184.25 kg/hm2、K2O 150.63 kg/hm2,产量期望10 437.64 kg/hm2,产投比6.32. 相似文献
7.
复杂飞机结构裂纹萌生寿命确定的工程方法 总被引：1，自引：0，他引：1
采用静拉伸应变测量试验的方法,确定了典型飞机复杂结构在载荷作用下的应变分布,并准确判断出其疲劳危险部位。对典型飞机复杂结构模拟件进行了等幅加载疲劳试验,并在疲劳试验过程中采用着色探伤方法测得了疲劳裂纹扩展数据。在此基础上,提出并建立了一种适用于确定复杂结构疲劳裂纹萌生寿命的工程方法,包括疲劳裂纹萌生寿命反推法和含有不确定寿命样本的统计推断方法。根据该方法对试验样本疲劳数据进行处理得出了裂纹萌生中值寿命及其在95%置信水平下的单侧置信下限。 相似文献
8.
植物释放N2O的研究进展 总被引：1，自引：0，他引：1
N2O是一种重要的温室效应气体。目前全球的N2O源／汇估算不平衡，源大于汇，可能存在重要的未知源。过去一直认为生物源N2O仅由土壤中的微生物过程所产生，但近年来研究表明微生物之外的其它生物，如植物，也参与N2O的排放或吸收过程。大量的研究结果显示：植物释放N2O的速率不仅与植物的种类、器官及所处的生理阶段有关，而且与其自身的NO3^-含量和所处的环境中的二氧化碳浓度、光照强度、温度等有关。本文综合报道了植物排放N2O研究的主要进展。 相似文献
9.
襄阳区水稻测土配方施肥“3414”试验初报 总被引：1，自引：0，他引：1
通过“3414”试验,确定了襄阳区水稻主推品种华两优1206,在有机质含量为2．11％,碱解氮为79．97mg／kg,有效磷为13．34mg／kg,速效钾为74．20mg／kg,pH为7．1的淹育型水稻土田块上种植,氮、磷、钾肥的施肥量分别为N13．3kg／666．7m2、P2O5 4．0kg／666．7m2,K205．9kg／666．7m2时,水稻可获得最高产量,分别为450．9kg／666．7m2,445．6kg／666．7m2、443．9kg/666．7m2;氮、磷、钾肥的施肥量分别为N9．6kg／666．7m2,P2052．7kg/666．7m2、K204．1kg/666．7m2时,水稻可获得经济最佳产量,分别为446．7kg/666．7m2．443．7kg／666．7m2,441．6kg/666．7m2。 相似文献
10.
王再军 《天津工程师范学院学报》2013,23(2):1-4
用相对论平均场理论计算了Ar同位素链丰中子偶偶核的单质子能级、质子填充概率和电荷密度分布。结果显示:当中子数N<18时,质子的2s1/2态能级低于1d3/2态能级;而当中子数N≥18时,质子的2s1/2态能级高于1d3/2态能级。这意味着在Ar同位素中可能存在质子2s1/2和1d3/2态能级反转。对电荷分布的计算进一步发现,质子2s1/2和1d3/2态能级反转会导致在Ar同位素中可能有质子半泡核的存在。 相似文献
11.
采用周期浸润加速腐蚀试验的方法,对某型飞机42框横梁模拟件分组进行了不同时间的加速预腐蚀试验,并通过随机载荷谱下的疲劳试验获得了预腐蚀后模拟件的疲劳寿命。结果表明,在加速腐蚀时间不大于300小时的情况下,预腐蚀对42框横梁结构模拟件疲劳寿命的影响不明显。 相似文献
12.
WENG Yong-gang 《实验室研究与探索》2007,(10)
应用软件FCG(MTS Fatigue Crack Growth TestW are)采用七点递增多项式局部拟合的方法,计算疲劳裂纹扩展速率da/dN,导致计算值分散度很大。经过详细分析,提出采用正交多项式的线性组合作为疲劳裂纹长度a与载荷循环数N之间关系的拟合目标函数,再用直接求导的方法计算da/dN。这样减小了da/dN的分散度,提高了Paris公式参数拟合和门槛值计算的精度。 相似文献
13.
A pseudo-dynamic testing program was generated on a fabricated composite frame with steel plate shear walls (SPSWs) to study its seismic performance. The specimen was a three-storey single-bay frame, which was composed of H-section steel columns and composite beams, and was assembled by bolted height-adjustable steel beam-to-column connections (BHA connections). Beam-only-connected SPSWs were selected as lateral load resisting members. The specimen was subjected to four ground motions of progressively increasing intensity. The results showed that: (1) beam-only-connected SPSWs provided sufficient lateral load resistance, lateral stiffness, and energy dissipation capacity to the fabricated frame via the tension field action developed in their infill panels; (2) the fabricated frame, assembled by BHA connections, exhibited substantial redundancy and good ductility; (3) an undesirable failure mode of the fabricated frame, in huge earthquakes, included severe cracking in composite beams and block shear failure in SPSWs’ connections; (4) the inter-storey shear force distribution determined by ASCE/SEI 7-10 was verified with experimental data. 相似文献
14.
楚雄州野生杜鹃资源及其开发利用探讨 总被引：1，自引：0，他引：1
应用野外调查、标本采集整理及数据搜集等研究得出楚雄州10县市有野生杜鹃资源共39种,并对境内野生杜鹃植物资源种类、分布特点进行分析,提出楚雄州野生杜鹃资源保护、种质资源收集与引种驯化、良种选育和开发利用的建议。 相似文献
15.
A newly developed pure rolling fatigue test rig with three contact points for bearing balls was used to perform rolling contact fatigue (RCF) tests. The fatigue properties of GCr15 steel balls and two kinds of Si3N4 ceramic balls (GSN-200 and NBD-200) produced with different technologies were compared. Ball surfaces were examined after failure with optical microscope and scanning electron microscope (SEM). It was identified by tests that the failure mode of ceramic balls was surface spall. The main factor of ceramic ball failure was principal tensile stress. Life tests data, summarized in accordance with the Weibull theory, showed that the life of GSN-200 balls was close to that of GCr15 balls, whereas the life of NBD-200balls was much longer than those of GSN-200 and GCr15. Under the same working condition, the temperature rise of all ceramic balls was lower than that of steel balls, and their crack propagation rates were slower than that of steel balls. 相似文献
16.
发现了具有逆光致变色性质的螺吡喃类化合物的结构特点,即在吲哚啉氮上连有极性基团,同时和吡喃环并连的芳环上具有强的吸电子基团.设计并合成了逆光致变色化合物1’-(2-羟乙基)-3’,3’-二甲基-6-硝基螺[吲哚啉-2,2’[2H-1]苯并吡喃].实验表明,用它配制成的逆光致变色油墨显示有很好的色度和耐疲劳度. 相似文献
17.
王再军 《天津职业技术师范学院学报》2014,(1):1-4
用相对论平均场模型结合NL3、TM2和NL-SH参数对P的奇A核同位素的2s1/2和1d3/2单质子能级变化趋势以及自旋和宇称进行了理论计算.发现丰中子同位素37-47P,尤其是47P中可能存在2s1/2和1d3/2单质子能级反转.对于37P和39P,TM2和NL-SH参数给出的自旋和宇称是（3/2）＋,NL3给出的是（1/2）＋;对于41-47P,NL3、TM2和NL-SH给出的自旋和宇称都是（3/2）＋.自旋和宇称的结果只有部分和NUBASE2012中的估计值是一致的. 相似文献
18.
The aim of this research is to characterize the development of fatigue damage by means of stress-strain hysteresis. Experiments were conducted on 14 specimens made of cold-finished unannealed AISI 1018 steel. Results demonstrate that the mechanical hysteresis loop areas, when plotted as a function of the number of loading cycles, show significant variations and demonstrate the three principal stages concerning the progress of the fatigue failure--initial accommodation, accretion of damage and terminal failure. These three stages of fatigue are marked by the transitions at cycles N2 and N3. Experimental results show that although fatigue life Nf ranges from 2644 cycles to 108 992 cycles, the ratios of N2/Nf and N3/Nf tend to be stable： N2/Nf=I 0.7%, N3/Nf=91.3%. 相似文献
19.
利用改进的固结渗透仪,通过对天然沉积软黏土原状样及重塑样进行固结渗透试验,对比分析了压缩过程中天然沉积土原状样与重塑样在同一孔隙比和同一应力水平下的渗透性状。研究结果表明,天然沉积土原状样e-log kv曲线位于重塑样的右边,但是两者差别不大;原状样的log kv-logσ’v关系曲线位于重塑样的上方,天然沉积土原状样与重塑样同一应力水平下的渗透系数的比值随着应力水平的增大而先增大后减小,在原状样固结屈服压力时达到最大值。 相似文献
20.
在田间试验条件下研究了施肥对“秦油二号”杂交油菜氮、磷、钾营养及其产量的影响,结果表明:单施氮肥,增加植株氮、磷、钾吸收强度和植株含氮浓度,但对植株磷、钾浓度无明显影响。氮磷配施既能显著提高植株氮、磷、钾吸收强度,也能增加植株氮、磷、钾浓度。在施用氮、磷肥料基础上配施氯化钾肥,降低了植株氮、磷吸收强度和氮浓度。施肥使油菜氮,磷营养吸收高峰推迟。吸氮高峰期在油菜苔期,吸磷高峰期在油菜花角期。在本试验条件下,氮肥与磷肥配合施用油菜产量和经济效益最高,比单施氮肥增产23.2％,比氮磷钾配施增产11.4％,每亩增收三十无以上。 相似文献