共查询到20条相似文献，搜索用时 15 毫秒
1.
Chen Xiangming 《保鲜与加工》1993,(1)
This paper discusses that the conditions are satistiel by parameters in the Richardson two-stage iterative method when it converges and the optimum of parameters makes this iterative converge more 相似文献
2.
In this paper, a domain decomposition method for the exterior Helmholtz problem is investigated. The unboundary domain is divided into some non overlapping subdomains. The natural integral operator is used as the artificial boundary conditions on the exterior boundary of the computational domains. The convergence of the algorithm is given in the sense of energy norm. Finally, the discrete problem is discussed and some numerical examples are presented. 相似文献
3.
作物高产群体LAI动态模拟模型的建立与检验 总被引：37，自引：7，他引：30
针对目前已有群体叶面积指数（LAI）模拟模型形式多样、参数较多以及应用性不强等问题,对春玉米、水稻和冬小麦的LAI及出苗至成熟天数进行归一化处理,分别将最大LAI和出苗至成熟天数定为1,以相对LAI (0~1)和相对时间(0~1)为参数进行LAI动态模拟,筛选、建立了一个适用于这3种作物的相对化LAI动态模拟模型y= (a+bx) / (1+cx+dx2)。其中,春玉米y= (0.0134+0.3234x) / (1－2.774x+2.4178x2),r=0.9859**;水稻y= (0.0777+0.0205x) / (1－2.73744x+2.0484x2),r=0.9865**;冬小麦y= (0.0131+0.0035x) / (1－2.4515x+1.5273x2),r=0.9719**。利用该模型,自拔节期起就能够较准确地进行LAI的动态预测,其在春玉米、水稻和冬小麦上的准确度（以k表示）分别为1.050、1.0357和1.1168,精确度（以R2表示）分别为0.8728、0.9270和0.9254。3种作物整个生育期内模型的模拟值与测量值的精确度均在0.98以上,准确度达0.86以上,表明相对化LAI动态模型能够准确地反映作物群体动态变化。不仅可以计算出作物生育期间的平均LAI、总光合势,还能计算任一时刻的LAI以及任一时段的光合势。结合田间调查还可得到作物生长期间的平均净同化率和平均作物生长率等产量相关的重要生理参数。根据作物群体中各光合生理参数与产量的关系,提出了3种作物进一步增产的可能途径。 相似文献
4.
Branch -like pipeline is a common structure in gas transmission pipeline. In the light of the constituent properties of natural gas branch - like pipeline system, the system can be divided into fundamental constituent units. This paper presents a realistic unsteady flow model consisting of simple models of pipeline units and connecting conditions, boundary conditions and initial condition associated with units by using system analysis method. The solutions in wide sense are obtained by theory of functional analysis and operator series method, Such a method has the properties of both analytical solution and numerical solution methods. When the divided pipeline unit is larger, an intuitive approximate analytical solution may be obtained; while the one is smaller, a more accurate numerical solution may be acquired. Based on this, a general computer program has been developed for this model and solutions have been used successfully in a local natural gas transmission network in Sichuan. It is proved that the model and algorithm proposed in this paper are of the advantages of convenient calculation, high precision, time saving and wide application range by way of analysis and application. 相似文献
5.
遥感信息应用于水分胁迫条件下的华北冬小麦生长模拟研究 总被引：7，自引：0，他引：7
由于初始土壤水分、灌溉量等变量的空间分布不易获得,区域尺度水分胁迫条件下作物生长模拟存在一定难度。本文在WOFOST模型本地化和区域化的基础上,采用调控型方法,重点探讨了利用MODIS数据反演的地表蒸散在大范围内估算土壤水分平衡过程中的参数或变量初始值,以实现水分胁迫条件下作物模型区域模拟的可行性。2002年模拟结果显示,引入遥感信息优化获得初始土壤有效含水量、返青期生物量及抽穗期灌溉量后,土壤水分的模拟效果得到改善;32个农业气象试验站点模拟产量的相对均方根误差（RRMSE）由0.63降至0.20;华北冬小麦模拟产量的空间分布与实际产量分布更加接近,产量低估的情况得到较好改善;河北、河南、山东3省平均产量的模拟误差分别为－4.9%、4.3%和8.6%。初步结果表明,结合卫星遥感信息通过优化方法在大范围内估算作物模型的相关参变量,以实现水分胁迫条件下作物模型的区域应用是行之有效的。 相似文献
6.
Summary Genotype x year (G x Y) and genotype x crop (G x C) interactions may be confounded in sugar cane when data is obtained from the plant crop and/or from ratoon crops in successive years. A technique to minimise the effects of confounding of the G x C interaction with the G x Y interaction is presented. The mean yield of cane from neighbouring farms was used as an indicator of the year (environment) effect. It was used to re-analyse yields from three experiments comparing six genotypes grown over a plant crop and three ratoons. Two experiments were grown under rainfed conditions and one experiment was irrigated. The confounded interactions were partitioned into a linear contrast on the farm yields (a year effect) and a crop effect that was the remainder. When the yields adjusted for the farm yield effects were compared with original yields of cane, yields of plant and first ratoon were reduced and those of third ratoon were increased. There were only minor changes in the ranking of genotypes on yield. It was concluded that the re-analysis using farm yield showed that the confounding effect of years on the interpretation of genotype x crop effects was samll. 相似文献
7.
8.
After the evaluation of numerous accessions of primitive wheats for yield components and morphophysiological traits related
to drought tolerance (e.g., maintenance of high relative water content, RWC; photochemical quenching of chlorophyll fluorescence,
qQ; and chlorophyll loss, chl, under moisture stress conditions), several accessions belonging to three species (Triticum
dicoccum, T. polonicum, and T. carthlicum) were crossed with the improved durum wheat varieties Cham 1 and Om Rabi 5. A direct
selection (F2 progeny) for yield and an indirect physiological trait were applied on interspecific T. durum x T. dicoccum, T. durum x T.
polonicum, and T. durum x T. carthlicum populations. Divergent selection was applied to validate the possible use of morphophysiological
traits (root parameters, RWC, photochemical quenching, proline content, and carbon isotope discrimination) in selection, and
to evaluate the resulting effects on yield. Heritability and selection response of these traits has been evaluated, and the
impact of divergent selection for morphological and agronomic characters was studied under field conditions. The divergent
populations were evaluated under different environmental conditions in France, Syria, and Yemen. Selection for morphophysiological
traits related to moisture stress, such as root parameters, RWC and carbon isotope discrimination was possible due to high
h2 values and effective, resulting in high genetic gains. However, the effect of selection for these traits on yield stability
needs to be further studied. Furthermore, a modified bulk method (F2 'progeny method') was developed. Direct selection for grain yield per plant in F2 was carried out and yield per line in F3 was evaluated under contrasting environmental conditions in France, Syria, and Tunisia. Results revealed that some F3 lines were higher yielding than the improved durum wheat varieties Cham 1 and Om Rabi 5 under both stressed (Aleppo) and
favourable (Montpellier) environmental conditions. Lines were evaluated in preliminary yield trials at Montpellier (France),
Aleppo (Syria), and Constantine (Algeria). Results indicated that the use of related species combined with the use of the
modified bulk breeding method is promising not only for increasing durum wheat yield in drought prone environments, but also
for improving durum wheat yield stability across contrasting environments. Results of both breeding strategies are presented,
and the potential advantages of using related tetraploid species in durum wheat breeding for drought tolerance are discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Mi Linshu Liu Fangning Chen Gang 《保鲜与加工》1992,(1):70-76
This paper presents a new method for digital simulation of equivalent circuit parameters and port currents of the short circuit fault port for each sequence networks in power systems with variable configuration and parameters. If the electric values for single-line-to-ground short ciruit are calculated in detail,the other faults at the same location can be rapidly obtained by using the proportional coefficients of the same sequence port current. In this method,the modifications of Z-bus or Y-bus matrices for each sequence network, and the repeated of calculations of the short circuit calculation have been completly avoided. 相似文献
10.
The degree of heterosis for total tuber yield (TTY) and total solids (TS) in 4x‐2x crosses was estimated by comparing the performance of 12 families with their respective parents in two locations in Wisconsin (USA). The parental 2x clones were Phureja‐haploid Tuberosum hybrids with 2n‐pollen production by first‐division restitution. The general combining ability (GCA) and specific combining ability (SCA) were estimated for TTY, TS, vine maturity (VM), length of tuber sprout dormancy (LD), and tuber eye depth (ED). Family performance for TTY ranged from 74 to 146% at Hancock (E#1) and from 77 to 287 at Rhinelander (E#2) when compared with that of the 4x parent group. For VM, the families were late maturing, but a few precocious ones were identified. For TS, the families had heterosis of 5.1% over the 4x parent group. The families had slightly higher ED values than the 4x parents, but families with values within the commercial range were identified. The family average for LD (54 days) was closer to the 2x group (51 days) than to the 4x group (88 days). The direction and magnitude of the parent‐family relationships were variable. The 4x parent TTY was correlated with progeny in E#1 but not E#2. The 2x parent VM had correlation with the offspring at E#2 but not at E#1. The type of gene action had a trait‐specific expression. Significant SCA and GCA variances were observed, suggesting that additive as well as non‐additive genetic effects were operating. The 4x‐2x crosses were able to generate heterotic families for TTY and TS in combination with other useful traits. However, no promising results were found for LD because of the apparent dominance of the short‐dormancy phenotype. This result indicates the need of additional selection and breeding efforts for some specific traits when using S. phureja‐derived germplasm. 相似文献
11.
Experimental Study about Activated Water Produced by the Method of Electro-hydraulic Impulse Improving the Mechanical Performance of Mortar 总被引：1，自引：0，他引：1
图１微型库平面示意射阳地区气候湿润、四季多雨，蒜薹味甜微辣、脆嫩、鲜绿、耐贮，主要分布在藕耕、千秋、临海、六垛等地区。种植面积达１．３万ｈｍ２，总贮量达４０００～８０００万ｔ，已成为当地蒜农的经济支柱和政府产业结构调整的重点方向。但蒜薹采收期一般在５月１０日左右，正值高温季节，采收时间仅４～５天，常因销售不及时而造成大量损失。为此蒜农和地方政府极为重视蒜薹采后贮藏保鲜、减损、保值、增值工作。当地政府于２０００～２００１年先后引进３５座微型节能冷库简称微型库，使以前只有依靠国家经费或贷款才能建造的… 相似文献
12.
The relative value of haploid Tuberosum-Solanum chacoense (TCH) vs. Solanum phureja-haploid Tuberosum (PTH) hybrids as male parents in 4x–2x crosses was estimated under two distinct crop management systems.
The first experiment (E#1) was carried out with supplementary irrigation (three times a week) at Hancock-Wisconsin (WI) with
27 families derived from a sub-set of crosses involving 11 tetraploid (4x) cultivars and 10 diploid (2x) clones (3 TCH; 6
PTH; and one TCH-PTH hybrid clone). A second experiment (E#2) was conducted at Rhinelander-WI with the same group of families
but it was only rainfed with no supplementary irrigation being provided during the entire course of the assay. For comparison,
a complete set of 4x and 2x clones (used as parents) was also planted in each location. Three traits were evaluated in both
locations: total tuber yield (TTY), haulm maturity (HM), and plant vigor (PV). Altogether, 18 out of 27 and 10 out of 27 families
outyielded the corresponding 4x parents at E#1 and E#2, respectively. Significant differences among all 4x–2x families and
among families of the TCH group were observed for TTY at both locations. No difference was found for TTY among families of
PTH and [TCH–PTH] groups at each location. A total of 75% and 50% of the TCH families outyielded their 4x parents at E#1 and
E#2, respectively. The percentage of families from the PTH group that outyielded their 4x parents at E#1 and E#2 was 83.3%
and 25%, respectively. The TCH group had on average lower HM scores than PTH (at both locations) indicating some segregation
for earliness. However, the HM values of the 4x–2x families were, in general, higher than those observed for the 4x parents.
For PV, the PTH group mean was significantly higher than TCH group only in E#1. The PV values of the 4x–2x families were higher
than the 4x-parent group at both locations. Our results indicated that TCH hybrids might be as good parents as PTH to increase
the TTY of 4x–2x progenies. In addition, the TCH families displayed a slight higher level of performance under more stressful
growing conditions than PTH hybrids as indicated by the assay at Rhinelander. Therefore, selection of genetic materials with
potential broad range of adaptation seems to be feasible with both hybrids via the 4x–2x breeding scheme.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
Physiological Response of Multiple Contrasting Rice (Oryza sativa L.) Cultivars to Suboptimal Temperatures 
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下载免费PDF全文 M. M. Rachoski A. Vidal O. A. Ruiz A. B. Menéndez A. A. Rodríguez 《Journal of Agronomy and Crop Science》2015,201(2):117-127
The physiological response of multiple rice cultivars, eighteen initially and eight cultivars later on, to suboptimal temperatures (ST) conditions was investigated in laboratory and outdoor experimental conditions. Treatment with ST decreased growth in different extents according to the cultivar and affected the PSII performance, determined by chlorophyll fluorescence fast‐transient test, and stomatal conductance, regardless the experimental condition. Two groups of cultivars could be distinguished on the base of their growth and physiological parameters. The group of cultivars presenting higher growths displayed optimal JIP values, and higher instantaneous water use efficiency (WUEi), due to a lower Gs under ST, unlike cultivars showing lower growth values, which presented worse JIP values and could not adjust their Gs and hence their WUEi. In this work, we detected at least two cultivars with superior tolerance to ST than the cold tolerant referent Koshihikari. These cultivars could be used as parents or tolerance donors in breeding for new crop varieties. On other hand, positive and significant correlations between data obtained from laboratory and outdoor experiments suggest that laboratory measurements of most of the above mentioned parameters would be useful to predict the response of rice cultivars to ST outdoor. 相似文献
14.
Huang Zongqing Xie Shangfen Zhang Shengtao 《保鲜与加工》1990,(5):91-97
This paper describes the initial idea of building up a new approach of spectroscopic ellipsometry for studying electrochemieal reaction from some of the author's experimental results on ellipsometry. The results which have proved the possibility of this idea is also presented. The study on an odic oxidation of iron and the oxidation and reduction processes of polyaililine film by ellipsometry with different wavelength show that the ellipsometric spectroscopy might be a new method for analyzing electrochemical reactions. 相似文献
15.
以木糖、丙氨酸、半胱氨酸和硫胺素为变量,以反应液的吸光度和感官评定结果为考察指标,采用响应曲面法优化得到了一种新型的烤鸡上色增香液配方。其最佳配方参数为:木糖3.7%,丙氨酸2.6%,半胱氨酸1.8%和硫胺素2.6%,在此条件下,烤鸡上色增香液具有最佳的色泽和香味。 相似文献
16.
澳洲野生棉种子叶色素腺体延缓形成的组织结构观察 总被引：3，自引：2，他引：3
对５个澳洲野生棉种休眠种子、种子发育过程中的子叶和种子萌发过程中的子叶进行连续切片观察,并以比克氏棉为例进行透视电镜观察。结果表明,具有子叶色素腺体延缓形成性状的澳洲野生棉种及其杂交后代的休眠种子,虽肉眼看不到色素腺体,但具有一群不同于其它细胞的特殊细胞群,其整体结构类似色素腺体的雏形。因此,提出了“色素腺体原”的新概念。澳洲野生棉种在开花后的幼胚器官形态建成期均先出现色素腺体细胞,然后经数次分裂形成一团色素腺体细胞群,挤压周围细胞而形成为色素腺体原,并保持该结构至种子成熟。当种子萌发１６ｈ后,色素腺体细胞解体,形成色素腺体。此外,本研究对澳洲野生棉种子叶色素腺体延缓形成性状的遗传调控等问题进行了讨论。 相似文献
17.
Unilateral problems is a kind of important partial differential problems. It can be solved by treating it as a complementary problem. As the complementary conditions lie in the boundary of the region,it is suitable for BEM. This paper is based on the switching algorithm,which is first used by J. M. Aitchison for the Signorini Problems of Laplace operator,then extends it to the elliptic operator,and conjunct it with the BEM. At last the detail of the algorithm is given. The new algorithm is easy to be implied effectively and quickly. It only needs the minimal change of the BEM programming. The numerical tests show the algorithm is effective and conventional. 相似文献
18.
GONG Xian sheng 《保鲜与加工》1999,(3):15-23
A method which is used for calculating steady vibration response of shipping propulsion shafting connecting with a coupling with nonlinear hysteresis characteristics are studied. On condition that the nonlinear dynamic stiffness and hysteresis damping of the coupling be considered, on the basis of GLM(Galerki Levenberg Marquard) method, a method called SSGILM(Separate System Galerkin and Improved Levenberg-Marquardt)to be used for calculating steady vibration response of propulsion shafting with local nonlinear dynamic stiffness and hysteresis damping, is proposed. A simple example is given out and the analyses show that it is effective to calculate steady vibration response of the shafting with local nonlinear dynamic stiffness and hysteresis damping by SSGILM method. From initial response values given arbitrarily, the automatic search algorithm in SSGILM method can converge the given initial response values to the response values accorded with required accuracy quickly; nonlinear dynamic stiffness and hysteresis damping of the coupling have different effect on vibration response of the shafting at different range of frequency. At the area of close nature frequency of the shafting ,displacement amplitude of the shafting is bigger. Beyond the range, the characteristics of the coupling have restraint effect on vibration of the shafting. 相似文献
19.
Huang Decai 《保鲜与加工》1993,(2):107-112
A necessary and sufficient condition and some sufficient conditions concerning the convergence of a 2-block AOR method for large-scaled least-square problems are given. It is shown that, by appropriately selecting parameters, the 2-block AOR method is always convergent and the theorem in [3] is only a corollary of this paper. 相似文献
20.
It is a significative attempt in medical diagnosis that Electrical Impedance Tomography is used to hematoma monitoring. Since there is great difference in physiological parameters among different persons, among varieties of ill cases, and different tissues, it is important to loosen the limits of initial values of reconstruction algorithm. A new approach named Continuation method is proposed in Electrical Impedance Tomography. In addition, simulating calculation results are given to validate the approach effective. 相似文献