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1.
Extensive research has investigated the bearing capacity of footings placed on leveled ground improved by deep mixed (DM) columns. However, few studies have focused on the effects of the embedment on the bearing capacity of footings on ground reinforced with DM columns. In geotechnical engineering practice underestimation of the limit load has occurred in China because of the increased use of conventional design methods for reinforced ground with embedment. In this investigation, a numerical model using a rigorous limit analysis tool, known as discontinuity layout optimization (DLO), is established. An equivalent area model is employed with an appropriate stress concentration ratio. Subsequently, a set of design charts of bearing capacity coefficients is produced with a special focus on the bearing capacity coefficient Nq and the failure mechanism. The results show that three failure patterns exist in the composite ground reinforced by DM columns. For cases without embedment, the bearing capacity coefficient Nc increases with the area replacement ratio to a certain value due to the occurrence of general shear failure mechanism. The bearing capacity coefficient Nγ decreases with the area replacement ratio, as the equivalent frictional strength of the reinforced region is reduced. When the embedment is considered, the failure mechanism of composite foundation has a significant influence on the coefficient Nq. Specifically, increase of column length leads to a larger value of Nq when block failure is observed. When a general shear failure pattern occurs, the effect of additional column lengths on the coefficient Nq can be neglected. 相似文献
2.
1 Introduction AmatrixA∈Cn×missaidtobecentrohermitianifA =Jn AJm,andskewcentrohermitianifA =-Jn AJm,where Adenotetheconjugateofthema trixAandJlisthepermutationmatrixoforderlwithonesonthecrossdiagonal(bottomlefttotopright)andzeroselsewhere .ThehermitianToeplitzmatricesformanimportantsubclassofcentrohermi tianmatriceswhichoccurnaturallyindigitalsignalprocessingandotherareas ,seeforinstance[1] andreferencetherein .Thecentrohermitianandrelatedmatricesrecentlyplayanimportantroleinthesolu… 相似文献
3.
Bai-kui Wang Yu-long Mao Li Gong Xin Xu Shou-qun Jiang Yi-bing Wang Wei-fen Li 《Journal of Zhejiang University. Science. B》2018,19(10):785-795
Objective
Salmonella enterica remains a major cause of food-borne disease in humans, and Salmonella Typhimurium (ST) contamination of poultry products is a worldwide problem. Since macrophages play an essential role in controlling Salmonella infection, the aim of this study was to evaluate the effect of glycyrrhizic acid (GA) on immune function of chicken HD11 macrophages.Methods
Chicken HD11 macrophages were treated with GA (0, 12.5, 25, 50, 100, 200, 400, or 800 μg/ml) and lipopolysaccharide (LPS, 500 ng/ml) for 3, 6, 12, 24, or 48 h. Evaluated responses included phagocytosis, bacteria-killing, gene expression of cell surface molecules (cluster of differentiation 40 (CD40), CD80, CD83, and CD197) and antimicrobial effectors (inducible nitric oxide synthase (iNOS), NADPH oxidase-1 (NOX-1), interferon-γ (IFN-γ), LPS-induced tumor necrosis factor (TNF)-α factor (LITAF), interleukin-6 (IL-6), and IL-10), and production of nitric oxide (NO) and hydrogen peroxide (H2O2).Results
GA increased the internalization of both fluorescein isothiocyanate (FITC)-dextran and ST by HD11 cells and markedly decreased the intracellular survival of ST. We found that the messenger RNA (mRNA) expression of cell surface molecules (CD40, CD80, CD83, and CD197) and cytokines (IFN-γ, IL-6, and IL-10) of HD11 cells was up-regulated following GA exposure. The expression of iNOS and NOX-1 was induced by GA and thereby the productions of NO and H2O2 in HD11 cells were enhanced. Notably, it was verified that nuclear factor-κB (NF-κB) and c-Jun N-terminal kinase (JNK) pathways were responsible for GA-induced synthesis of NO and IFN-γ gene expression.Conclusions
Taken together, these results suggested that GA exhibits a potent immune regulatory effect to activate chicken macrophages and enhances Salmonella-killing capacity.4.
Chen Zhi-guo 《浙江大学学报(A卷英文版)》2006,7(2):198-202
In this paper we give a short survey on a problem on extremal quasiconformal extensions. It had been a conjecture for a long time that the dilatations K0(h) and K1(h) are equal before Anderson and Hinkkanen disproved this by constructing concrete examples of a family of affine mappings of some parallelograms. The problem also engendered many interesting results. At the end of the current paper, we discuss relationships among K0(h), H(h) and K1(h) as a concluding remark. 相似文献
5.
Li-jun Ju Chong Zhang Jing-jing Liao Yue-peng Li Hong-yan Qi 《Journal of Zhejiang University. Science. B》2018,19(8):596-609
In plants, lipoxygenases (LOXs) play a crucial role in biotic and abiotic stresses. In our previous study, five 13-LOX genes of oriental melon were regulated by abiotic stress but it is unclear whether the 9-LOX is involved in biotic and abiotic stresses. The promoter analysis revealed that CmLOX09 (type of 9-LOX) has hormone elements, signal substances, and stress elements. We analyzed the expression of CmLOX09 and its downstream genes—CmHPL and CmAOS—in the leaves of four-leaf stage seedlings of the oriental melon cultivar “Yumeiren” under wound, hormone, and signal substances. CmLOX09, CmHPL, and CmAOS were all induced by wounding. CmLOX09 was induced by auxin (indole acetic acid, IAA) and gibberellins (GA3); however, CmHPL and CmAOS showed differential responses to IAA and GA3. CmLOX09, CmHPL, and CmAOS were all induced by hydrogen peroxide (H2O2) and methyl jasmonate (MeJA), while being inhibited by abscisic acid (ABA) and salicylic acid (SA). CmLOX09, CmHPL, and CmAOS were all induced by the powdery mildew pathogen Podosphaera xanthii. The content of 2-hexynol and 2-hexenal in leaves after MeJA treatment was significantly higher than that in the control. After infection with P. xanthii, the diseased leaves of the oriental melon were divided into four levels—levels 1, 2, 3, and 4. The content of jasmonic acid (JA) in the leaves of levels 1 and 3 was significantly higher than that in the level 0 leaves. In summary, the results suggested that CmLOX09 might play a positive role in the response to MeJA through the hydroperoxide lyase (HPL) pathway to produce C6 alcohols and aldehydes, and in the response to P. xanthii through the allene oxide synthase (AOS) pathway to form JA. 相似文献
6.
Zhengchang Wu 《浙江大学学报(A卷英文版)》2002,3(3):332-338
In this paper we will first prove that the nontrivial L p solutions of the vector refinement e-quation exist if and only if the corresponding subdivision scheme with a suitable initial function converges in L p without assumption of the stability of the solutions. Then we obtain a characterization of the convergence of the subdivision scheme in terms of the mask. This gives a complete answer to the existence of L p solutions of the refinement equation and the convergence of the corresponding subdivision schemes. 相似文献
7.
Yue-lan Wang Zeng-yi Ma Hai-hui You Yi-jun Tang Yue-liang Shen Ming-jiang Ni Yong Chi Jian-hua Yan 《浙江大学学报(A卷英文版)》2018,19(4):315-328
Optimizing the operation of coal-fired power plants to reduce nitrogen oxide (NO x ) emissions requires accurate modeling of the NO x emission process. The careful selection of input parameters not only forms the basis of accurate modeling, but can also be used to reduce the complexity of the model. The present study employs the least squares support vector machine-supervised learning method to model NO x emissions based on historical real time data obtained from a 1000-MW once-through boiler. The initial input parameters are determined by expert knowledge and operational experience, while the final input parameters are obtained by sensitivity analysis, where the variation in model accuracy for a given set of data is analyzed as one or several input parameters are successively omitted from the calculations, while retaining all other parameters. Here, model accuracy is evaluated according to the mean relative error (MRE). This process reduces the parameters required for NO x emission modeling from an initial number of 33 to 7, while the corresponding MRE is reduced from 3.09% to 2.23%. Moreover, a correlation of 0.9566 between predicted and measured values was obtained by applying the model with just these seven input parameters to a validation dataset. As such, the proposed method for selecting input parameters serves as a reference for related studies. 相似文献
8.
Considering the great importance of the elastic shear modulus G0 of unsaturated soils to the serviceability of many geo-structures in geo-energy and geo-environmental engineering, some semi-empirical models have been reported for the G0 of unsaturated soils. Existing models require at least three parameters and the calibration of the model parameters requires extensive time-consuming unsaturated soil tests. In this study, a simple semi-empirical model is proposed for the hysteretic G0 of unsaturated soils, requiring only two parameters. The constitutive variables of the mean Bishop’s stress and a bonding variable are adopted for considering the average stress between soil particles and the additional normal forces between soil particles provided by water menisci. The derived equation is applied to simulate the G0 of unsaturated silts and sands. Comparisons between the measured and calculated results demonstrate that the proposed equation is able to describe the influences of various factors on G0, including mean net stress, suction, wetting-drying, and void ratio. 相似文献
9.
Tao Lu Jie-wei Shi Zhou-ping Sun Ming-fang Qi Yu-feng Liu Tian-lai Li 《Journal of Zhejiang University. Science. B》2017,18(7):635-648
Objectives
To evaluate the possible photoprotection mechanisms of cyclic and linear electron flux (CEF and LEF) under specific high temperature and high light (HH) stress.Methods
Six-leaf-stage tomato seedlings (“Liaoyuanduoli”, n=160) were divided into four parts: Part 1, served as control under 25 °C, 500 μmol/(m2·s); Part 2, spayed with distilled water (H2O) under 35 °C, 1000 μmol/(m2·s) (HH); Part 3, spayed with 100 μmol/L diuron (DCMU, CEF inhibitor) under HH; Part 4, spayed with 60 μmol/L methyl viologen (MV, LEF inhibitor) under HH. Energy conversion, photosystem I (PSI), and PSII activity, and trans-thylakoid membrane proton motive force were monitored during the treatment of 5 d and of the recovering 10 d.Results
HH decreased photochemical reaction dissipation (P) and the maximal photochemical efficiency of PSII (F v/F m), and increased the excitation energy distribution coefficient of PSII (β); DCMU and MV aggravated the partition imbalance of the excitation energy (γ) and the photoinhibition degree. With prolonged DCMU treatment time, electron transport rate and quantum efficiency of PSI (ETRI and Y I) significantly decreased whereas acceptor and donor side limitation of PSI (Y NA and Y ND) increased. MV led to a significant decline and accession of yield of regulated and non-regulated energy Y NPQ and Y NO, respectively. Membrane integrity and ATPase activity were reduced by HH stress, and DCMU and MV enhanced inhibitory actions.Conclusion
The protective effects of CEF and LEF were mediated to a certain degree by meliorations in energy absorption and distribution as well as by maintenance of thylakoid membrane integrity and ATPase activity.10.
In three experiments, we compared the effectiveness of rainbow writing and retrieval practice, two common methods of spelling instruction. In experiment 1 (n?=?14), second graders completed 2 days of spelling practice, followed by spelling tests 1 day and 5 weeks later. A repeated measures analysis of variance demonstrated that spelling accuracy for words trained with retrieval practice was higher than for words trained with rainbow writing on both tests (η p 2 ?=?.49). In experiments 2 (second graders, n?=?16) and 3 (first graders, n?=?12), students completed 2 days of spelling practice followed by a spelling test 1 day later. Results replicated experiment 1; spelling accuracy was higher for words trained with retrieval practice compared with rainbow writing (η p 2 ?=?.42 and .64, respectively). Furthermore, students endorsed both liking and learning from retrieval practice at least as much as (and sometimes more than) rainbow writing. Results demonstrate that retrieval practice is a more useful (and as engaging) training method than is rainbow writing and extend the well-established testing effect to beginning spellers. 相似文献
11.
In iron ore sintering, the granulation process is the first and an important step. As the fine particles adhere to the coarse coke particles, the NO x emission generated from coke combustion may be expected to be influenced by that adhering layer. In this study, the granule size distributions and adhering ratios were evaluated by a granulation model. Granulation experiments were also carried out to obtain the granule size distribution and adhering ratio. The influence of the adhering layer on NO x emissions from the combustion of S type granules was studied by tube furnace experiments. Conclusions include: (1) The adhering ratio predicted from the granulation model can be used as a qualitative index for the evaluation of NO x emission from coke combustion. (2) The influence of the adhering layer on NO x emissions was enhanced with increasing adhering layer thickness of S type granules, and the NO x reduction was enhanced at higher temperatures (around 1373 K), but weakened at lower temperatures (around 1173 K). 相似文献
12.
Alloying is an effective way to manipulate the composition and physico-chemical properties of functional materials. We demonstrated the syntheses of alloyed Co x Ni1?x O nanocrystals using a nonaqueous approach, with x continuously tuned from 0 to 1 by varying the molar ratios of the cobalt precursor in the reagents. The morphological, structural, and compositional properties of the alloyed Co x Ni1?x O nanocrystals were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and energy dispersive X-ray spectroscopy (EDS). The results showed that the cobalt and nickel atoms were homogeneously distributed in the alloyed nanocrystals. The as-prepared Co x Ni1?x O nanocrystals can be applied as the hole-transporting layers in polymer light emitting diodes (PLEDs). Our study provides a good example for the syntheses of alloyed oxide nanocrystals with continuously tunable composition. 相似文献
13.
Stress equilibrium equations, boundary-and continuity-conditions were used to establish a theoretical model of progressive debonding with friction at the debonded interface. On a basis of the minimum complementary energy principle, an expression for the energy release rateG was derived to explore the interfacial fracture properties. An interfacial debonding criterionG≥Γ i was introduced to determine the critical debond length and the bridging law. Numerical calculation results for fiber-reinforced composite SCS-6/Ti-6A1-4V were compared with those obtained by using the shear-lag models. 相似文献
14.
Parth Prashant Karnawat 《Resonance》2018,23(5):591-596
As an easy application of the intermediate value theorem, one can show that for any continuous function f: [0, 1] → ? with f (0) = f (1), there are points a, a + 1/2 both in [0, 1] such that f (a) = f (a + 1/2). In this note, we show that this property holds with 1/2 replaced by any number of the form 1/n for a positive integer n. More interestingly, we show that this is false for every number not of the form 1/n. 相似文献
15.
A circular jet has broad and important applications in practical engineering. Most research in this area has focused on a free jet, a wall jet or a vertical jet in a bounded domain. In this study, the mean velocities of circular offset jets were studied for four jet exit Froude numbers (Fr), three offset heights (S) (S/d=1, 2, 3) and three submergence ratios (ht/S) (surface jet, mixed jet, and submerged jet) in a bounded basin. Based on the results, we propose a velocity decay formula for a circular jet. The lateral velocity spread was more consistent with Gaussian and Cauchy–Lorentz distributions than the vertical velocity. Moreover, Fr had little effect on the decay of the mean velocity for a circular jet when Re>1×104. The lateral and vertical spreads showed a quadratic relationship with the streamwise distance for different values of Fr at X/d<10. The positions of maximum mean velocity decay were independent of Fr and S/d when X/d<10. The spread rate was more uniform in the lateral direction than that in the vertical direction in a certain region for different S/d and ht/S. Therefore, the decay, spread, and maximum velocity position of the mean velocity for a circular offset jet can remain stable under different values of Fr, offset height, and submergence ratio. 相似文献
16.
A k-ε-kp multi-fluid model was used to simulate confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. After considering the drag force between the two phases and gravity, a series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles were performed on a x×r＝50×50 mesh grid respectively. The results showed that the k-ε-kp multi-fluid model can be applied to predict moderate swirling multi-phase flow. When the particle diameter is large, the collision of the particles with the wall will influence the prediction accuracy. The bigger the diameter of the particles, the stronger the collision with the wall, and the more obvious the difference between measured and calculated results. 相似文献
17.
Silvia Wen-Yu Lee 《International Journal of Science and Mathematics Education》2018,16(8):1409-1430
The purpose of this study was, first, to understand the item hierarchy regarding students’ understanding of scientific models and modeling (USM). Secondly, this study investigated Taiwanese students’ USM progression from 7th to 12th grade, and after participating in a model-based curriculum. The questionnaire items were developed based on 6 aspects of USM, namely, model type, model content, constructed nature of models, multiple models, change of models, and purpose of models. Moreover, 10 representations of models were included for surveying what a model is. Results show that the purpose of models and model type items covered a wide range of item difficulties. At the one end, items for the purpose of models are most likely to be endorsed by the students, except for the item “models are used to predict.” At the other end, the “model type” items tended to be difficult. The students were least likely to agree that models can be text, mathematical, or dynamic. The items of the constructed nature of models were consistently located above the average, while the change of models items were consistently located around the mean level of difficulty. In terms of the natural progression of USM, the results show significant differences between 7th grade and all grades above 10th, and between 8th grade and 12th grade. The students in the 7th grade intervention group performed better than the students in the 7th and 8th grades who received no special instruction on models. 相似文献
18.
This key paper is intended to produce a comparison of Bildung and globalization, acknowledging that Bildung and globalization are both fuzzy concepts. Our comparison of globalization and Bildung therefore is to be seen as a construction. To reach this objective, we start with the identification of dimensions of the concept of globalization based predominantly on sociological research. This analysis is followed by explication of dimensions of the concept of Bildung as they can be identified before a frame of globalization. We want to find out whether it makes sense to see globalization as one part of a new model of Bildung. In the conclusion, we demonstrate the normativity of each and any theory of Bildung in globalizing times, and we explain why it is necessary to reflect on the normativity of the different concepts. We indicate where we see connections with the other papers of this special issue of “Zeitschrift für Erziehungswissenschaft”. 相似文献
19.
Numerical study on performance of perforated plate applied to cryogenic fluid flowmeter 总被引：1，自引：0，他引：1
The perforated plate is one of the effective devices for measuring flow rate accurately. In this study, a perforated plate is investigated for its characteristics, mainly including discharge coefficient C and pressure loss coefficient ζ, when applied to cryogenic fluids with the help of ANSYS Fluent. Three cryogenic fluids are studied, including liquid nitrogen (LN2), liquid oxygen (LO2), and liquid hydrogen (LH2). For comparison, two states of water are also investigated. The realizable κ-ε model with standard wall function is used to describe the turbulence and simulate the near-wall flow. The Schnerr-Sauer cavitation model is used to investigate the effect of cavitation on the performance of the perforated plate. Simulation results indicate that the upper limit of Reynolds number of the perforated plate is significantly dependent on the properties of the measured fluid when the temperatures of the fluids are set as the normal boiling point temperatures and the outlet pressures are 0.2 MPa. 相似文献
20.
Xiao-yan Nie Jun-lei Li Yong Zhang Yang Xu Xue-li Yang Yu Fu Guang-kai Liang Yun Lu Jian Liu Lu-wen Shi 《Journal of Zhejiang University. Science. B》2017,18(1):37-47