共查询到20条相似文献，搜索用时 30 毫秒
1.
Jeong Wan Ko 《Journal of The Franklin Institute》2011,348(9):2674-2688
This paper discretizes the states, a method introduced in [18] for constant delayed systems, not only in constructing the Lyapunov-Krasovskii (L-K) functional but also in designing the integral inequality technique [17] and [19] for time-varying delayed systems, which increase the order of uncorrelated augmentation [5], [21] and [22]. Based on the discretized state, [10] and [27]'s piecewise analysis method is applied to confirm the system stability in whole delay bound. Asymmetric variation of the delay derivative is assumed so that direct extension to all constraints of the delay derivative can be achieved. Examples show the resulting criteria improve the allowable delay bounds over all existing ones in the literature. 相似文献
2.
Beth Adelson 《Journal of The Franklin Institute》2011,348(3):439-445
In the early 1980s there was a large base of well-regarded cognitive theory—explaining human cognition. Additionally, personal technology was increasingly a factor in the workplace, but it was notoriously hard to use, leading to frustration rather than increased satisfaction and productivity [1], [2] and [3]. In 1974 Stuart Card accompanied Allen Newell from Carnegie Mellon University to Xerox’s Palo Alto Research Center (PARC) to work on the problem of human-computer interaction. Newell returned to CMU, but Card remained to become the founding manager of the User Interface Research group.Card’s first major work The Psychology of Human-Computer Interaction, was published in 1983. It was undertaken to address the problems of usability by closing the gap between theory and technology. It did this by providing a methodology for bringing theory to bear on application. The work served as a foundation for research and development in human-computer interaction for the following 15 years. 相似文献
3.
Despite the large volume of literature on racial differences in academic performance between African Americans and Caucasian Americans at various educational levels, there has been a dearth of research examining whether the academic library experience is an important variable that helps explain the racial differences observed in educational outcomes. To date, only one empirical study has examined the racial differences in library anxiety among college students. Specifically, Jiao et al. [Jiao, Q. G., Onwuegbuzie, A. J., & Bostick, S. L. (2004). Racial differences in library anxiety among graduate students. Library Review, 53(4), 228–235] found that African-American graduate students reported statistically significantly lower levels of library anxiety associated with three library anxiety dimensions than did their Caucasian-American counterparts. However, because the two racial groups selected for the study differed in the types of institution they attended, the researchers were unable to conclude whether the differences found in the library anxiety levels were the result of race or the groups’ educational experience/aptitude. Therefore, the present study replicated Jiao et al.’s earlier research while addressing this concern. Findings revealed that the African-American graduate students (n = 25) reported consistently lower levels across all five dimensions of library anxiety than did the Caucasian-American graduate students (n = 155). These two studies suggest that racial differences in library anxiety exist in the college student population. 相似文献
4.
The parametric H∞ loop shaping technique explores more design flexibility by introducing a free parameter that ensures robust stabilization with regard to normalized coprime factor uncertainty of the shaped plant. This paper addresses a design framework for parametric H∞ loop shaping control using linear matrix inequality (LMI) approach that provides a new set of solvability condition along with the larger feasibility region of solution space over the work of Gu et al. (1999) [6]. An equivalence between the Riccati equation based state-space approach and the proposed LMI framework is established and subsequently, an observer-based structure for parametric H∞ loop shaping controller has been realized. A numerical example is considered to demonstrate the effectiveness of the proposed method and the results therein are compared with the work of Gu et al. (1999) [6]. 相似文献
5.
In nonlinear parameter estimation local sensitivity assessment; conventionally measured by the first-order derivative of the predicted response with respect to a parameter of interest fails to provide a representative picture of the prediction sensitivity in the presence of significant parameter co-dependencies and/or nonlinearities. In this article we derive the profile-based sensitivity measure developed by Sulieman et al. (2001, 2004) [1] and [2] in the context of model re-parameterization. In particular, the so-called predicted response re-parameterization is shown to ultimately lead to the profile-based sensitivity coefficient defined by the total derivative of the model predicted response with respect to a parameter. Although inherently local, the profile-based measure is shown to handle simultaneous perturbations in parameter values while accounting for their co-dependencies. Thus the proposed measure possesses a central property of a global sensitivity measure and so it is considered hybrid local-global measure.The global Fourier amplitude sensitivity test (FAST) is added to the analysis and compared with both marginal and profile-based sensitivity methods. The Fourier sine amplitude is utilized here as a first-order sensitivity measure and shown to be directly linked to the local sensitivity coefficient averaged over all ranges of parameter uncertainties and so it is also considered hybrid local-global measure. The comparisons are explained by three compelling model cases with different degrees of parameter co-dependencies and nonlinearities. 相似文献
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7.
Molybdenum dinitrogen complexes supported by monodentate arylsilylamido ligand, [Ar(Me3Si)N]3MoN2Mg(THF)2[N(SiMe3)Ar] (5) and [Ar(Me3Si)N]3MoN2SiMe3 (6) (Ar = 3,5-Me2C6H3) were synthesized and structurally characterized, and proved to be effective catalysts for the disproportionation of cyclohexadienes and isomerization of terminal alkenes. The 1H NMR spectrum suggested that the bridging nitrogen ligand remains intact during the catalytic reaction, indicating possible catalytic ability of the Mo-N=N motif. 相似文献
8.
陈先军 《中国科技期刊研究》2015,26(11):1156-1160
[目的]根据论文的特点,从信息质量理论中提炼出有助于提高编辑初审工作质量的有效方法。[方法]根据Strong D M等人提出的信息质量定义,演绎推理论文信息质量的定义;根据信息质量的PSP/IQ模型,结合论文的特点和初审实践,从中归纳概括论文信息质量的维度,从而形成编辑初审的"论文信息质量5维法"。[结果]提出了学术期刊论文信息质量的概念,并探究了它的5个维度,形成了相应的论文信息质量5维法作为编辑初审的一种新方法。[结论]论文信息质量5维法在事实上和理论上都为编辑初审工作提供了一种可资借鉴的新思路和新方法。 相似文献
9.
Using data generated by progressive nucleation mechanism on the cumulative fraction of citations of individual papers published successively by a hypothetical author, an expression for the time dependence of the cumulative number Lsum(t) of citations of progressively published papers is proposed. It was found that, for all nonzero values of constant publication rate ΔN, the cumulative citations Lsum(t) of the cumulative N papers published by an author in his/her entire publication career spanning over T years may be represented in distinct regions: (1) in the region 0 < t < Θ0 (where Θ0 ≈ T/3), Lsum(t) slowly increases proportionally to the square of the citation time t, and (2) in the region t > Θ0, Lsum(t) approaches a constant Lsum(max) at T. In the former region, the time dependence of Lsum(t) of an author is associated with three parameters, viz. the citability parameter λ0, the publication rate ΔN and his/her publication career t. Based on the predicted dependence of Lsum(t) on t, a useful scientometric age-independent measure, defined as citation acceleration a = Lsum(t)/t2, is suggested to analyze and compare the scientific activities of different authors. Confrontation of the time dependence of cumulative number Lsum(t) of citations of papers with the theoretical equation reveals one or more citation periods during the publication careers of different authors. 相似文献
10.
Masuda and Konno [14] first formulated a two-stage contact process on complex networks with heterogeneous degree distribution, and they derived a critical birth or infection rate βc, above which there exists a unique positive equilibrium. The global behavior of this model is not well understood, and the authors have not given a rigorous mathematical analysis of their model. In this paper, we investigate the global behavior in detail and show that the global behavior is completely determined by a threshold R0. In particular, by comparison arguments, we establish the global asymptotic stability of the trivial equilibrium E0 for R0?<?1; by constructing a bounded function, we show that the system is uniformly persistent for R0?>?1. Furthermore, by means of a monotone iterative approach, we obtain a sufficient condition for the global asymptotic stability of the positive equilibrium E*. 相似文献
11.
BackgroundMethanol can be effectively removed from air by biofiltration (Shareefdeen et al., 1993; Babbitt et al., 2009 [1,2]). However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms (Negruţa et al., 2010 [3]), and it can be released out of the cell constituting a secondary emission.ResultsThe total removal of methanol was achieved up to input loads of 263 g m−3 h−1 and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m−3 h−1 at an input methanol load of 414 g m−3 h−1 and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m−3 h−1. Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m−3 when the methanol load was 672 g m−3 h−1 in an empty bed residence times of 60 s.ConclusionsFormaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.How to cite: Guerrero K, Arancibia A, Caceres M, et al. Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.04.003. 相似文献
12.
Confirmatory composite analysis (CCA) is a structural equation modeling (SEM) technique that specifies and assesses composite models. In a composite model, the construct emerges as a linear combination of observed variables. CCA was invented by Jörg Henseler and Theo K. Dijkstra in 2014, was subsequently fully elaborated by Schuberth et al. (2018), and was then introduced into business research by Henseler and Schuberth (2020b). Inspired by Hair et al. (2020), a recent article in the International Journal of Information Management (Motamarri et al., 2020) used the same term ‘confirmatory composite analysis’ as a technique for confirming measurement quality in partial least squares structural equation modeling (PLS-SEM) specifically. However, the original CCA (Henseler et al., 2014; Schuberth et al., 2018) and the Hair et al. (2020) technique are very different methods, used for entirely different purposes and objectives. So as to not confuse researchers, we advocate that the later-published Hair et al. (2020) method of confirming measurement quality in PLS-SEM be termed ‘method of confirming measurement quality’ (MCMQ) or ‘partial least squares confirmatory composite analysis’ (PLS-CCA). We write this research note to clarify the differences between CCA and PLS-CCA. 相似文献
13.
Shih-Feng YangChyi Hwang 《Journal of The Franklin Institute》2002,339(2):129-144
In this paper we present a method for testing the Hurwitz property of a segment of polynomials (1−λ)p0(s)+λp1(s), where λ∈[0,1] and p0(s) and p1(s) are nth-degree polynomials with complex coefficients. The method consists in constructing a parametric Routh-like array with polynomial entries and generating Sturm sequences for checking the absence of zeros of two real λ-polynomials of degrees 2 and 2n in the interval (0,1). The presented method is easy to implement. Moreover, it accomplishes the test in a finite number of arithmetic operations because it does not invoke any numerical root-finding procedure. 相似文献
14.
Fault detection and diagnosis are important issues in process engineering. Hence, considerable interest is growing in this field from industrial practitioners as well as academic researchers, as opposed to 30 years ago. This paper focusses on a model-based approach for fault detection. This approach is based on Finite Memory Observers (FMO), properties of this observer are presented in the first part of our work (Graton et al., 2014 [1]), the main results of this paper are recalled at the beginning of this paper and constitute the basis of this second part. Properties of the Finite Memory Observer (FMO) are studied from a global point of view for the class of linear time-varying (LTV) systems with stochastic noises. FMO performances take their framework from the study of their properties, and from the study of their influences on diagnosis results. Fundamentally, the generation of residuals is essential in a diagnosis procedure. In Graton et al. (2014) [1], the design for the finite memory observer is shown, the determination of its optimal window length is solved, and the generation of residuals for diagnosis is completed. This paper is the second part of this work and is devoted to the study of the observer and residual sensitivity towards model parameter variations and noises. 相似文献
15.
Understanding the biological feeding strategy and characteristics of a microorganism as an actuator requires the detailed and quantitative measurement of flow velocity and flow rate induced by the microorganism. Although some velocimetry methods have been applied to examine the flow, the measured dimensions were limited to at most two-dimensional two-component measurements. Here we have developed a method to measure three-dimensional two-component flow velocity fields generated by the microorganism Vorticella picta using a piezoscanner and a confocal microscope. We obtained the two-component velocities of the flow field in a two-dimensional plane denoted as the XY plane, with an observation area of 455×341 μm2 and the resolution of 9.09 μm per each velocity vector by a confocal microparticle image velocimetry technique. The measurement of the flow field at each height took 37.5 ms, and it was repeated in 16 planes with a 2.50 μm separation in the Z direction. We reconstructed the three-dimensional two-component flow velocity field. From the reconstructed data, the flow velocity field [u(x,y,z),v(x,y,z)] in an arbitrary plane can be visualized. The flow rates through YZ and ZX planes were also calculated. During feeding, we examined a suction flow to the mouth of the Vorticella picta and measured it to be to 300 pl∕s. 相似文献
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18.
Chang-Zheng Yuan 《国家科学评论(英文版)》2021,8(11)
Charmonium is a bound state of a charmed quark and a charmed antiquark, and a charmoniumlike state is a resonant structure that contains a charmed quark and antiquark pair but has properties that are incompatible with a conventional charmonium state. While operating at center-of-mass energies from 2 to 5 GeV, the BESIII experiment can access a wide mass range of charmonium and charmoniumlike states, and has contributed significantly in this field. We review BESIII results involving conventional charmonium states, including the first observation of the M1 transition ψ(2S) → γηc(2S) and the discovery of the ψ2(3823) state; and report on studies of charmoniumlike states, including the discoveries of the Zc(3900) and Zc(4020) tetraquark candidates, the resolution of the fine structure of the Y(4260) state, the discovery of the new production process e+e− → γX(3872) and the uncovering of strong evidence for the commonality among the X(3872), Y(4260) and Zc(3900) states. The prospects for further research at BESIII and proposed future facilities are also presented. 相似文献
19.
Using a mapping between a Rouse dumbbell model and fine-grained Monte Carlo simulations, we have computed the relaxation time of λ-DNA in a high ionic strength buffer confined in a nanochannel. The relaxation time thus obtained agrees quantitatively with experimental data [Reisner et al., Phys. Rev. Lett. 94, 196101 (2005)] using only a single O(1) fitting parameter to account for the uncertainty in model parameters. In addition to validating our mapping, this agreement supports our previous estimates of the friction coefficient of DNA confined in a nanochannel [Tree et al., Phys. Rev. Lett. 108, 228105 (2012)], which have been difficult to validate due to the lack of direct experimental data. Furthermore, the model calculation shows that as the channel size passes below approximately 100 nm (or roughly the Kuhn length of DNA) there is a dramatic drop in the relaxation time. Inasmuch as the chain friction rises with decreasing channel size, the reduction in the relaxation time can be solely attributed to the sharp decline in the fluctuations of the chain extension. Practically, the low variance in the observed DNA extension in such small channels has important implications for genome mapping. 相似文献
20.
BackgroundEndometritis is the most common disease of dairy cows and traditionally treated with antibiotics. Lactic acid bacteria can inhibit the growth of pathogens and also have potential for treatment of endometritis. Using PacBio single-molecule real-time sequencing technology, we sequenced the full-length l6S rRNA of the microbiota in uterine mucus samples from 31 cows with endometritis, treated with lactic acid bacteria (experimental [E] group) and antibiotics (control [C] group) separately. Microbiota profiles taken before and after treatment were compared.ResultsAfter both treatments, bacterial species richness was significantly higher than before, but there was no significant difference in bacterial diversity. Abundance of some bacteria increased after both lactic acid bacteria and antibiotic treatment: Lactobacillus helveticus, Lactococcus lactis, Lactococcus raffinolactis, Pseudomonas alcaligenes and Pseudomonas veronii. The bacterial species that significantly decreased in abundance varied depending on whether the cows had been treated with lactic acid bacteria or antibiotics. Abundance of Staphylococcus equorum and Treponema brennaborense increased after lactic acid bacteria treatment but decreased after antibiotic treatment. According to COG-based functional metagenomic predictions, 384 functional proteins were significantly differently expressed after treatment. E and C group protein expression pathways were significantly higher than before treatment (p < 0.05).ConclusionsIn this study, we found that lactic acid bacteria could cure endometritis and restore a normal physiological state, while avoiding the disadvantages of antibiotic treatment, such as the reductions in abundance of beneficial microbiota. This suggests that lactic acid bacteria treatment has potential as an alternative to antibiotics in the treatment of endometritis in cattle.How to cite: Yang L, Huang W, Yang C, et al. Using PacBio sequencing to investigate the effects of treatment with lactic acid bacteria or antibiotics on cow endometritis. Electron J Biotechnol 2021:51. https://doi.org/10.1016/j.ejbt.2021.02.004 相似文献