disturbances

干扰
  • 文章类型: Journal Article
    本研究讨论了具有数据丢失和干扰的布尔网络(BNs)的鲁棒稳定性问题,其中数据丢失由随机伯努利分布序列适当地描述。首先,通过半张量积(STP)技术将具有数据丢失和干扰的BN转换为代数形式。因此,原始系统被构造为概率增强系统,基于此,原始系统的概率为1的稳定性问题成为增广系统的概率为1的集合稳定性。随后,提出了系统鲁棒稳定性的若干准则。此外,提出了一种基于真值矩阵的增广系统的鲁棒集稳定性验证算法。最后,通过一个说明性的例子证明了所得结果的有效性。
    This study discusses the robust stability problem of Boolean networks (BNs) with data loss and disturbances, where data loss is appropriately described by random Bernoulli distribution sequences. Firstly, a BN with data loss and disturbances is converted into an algebraic form via the semi-tensor product (STP) technique. Accordingly, the original system is constructed as a probabilistic augmented system, based on which the problem of stability with probability one for the original system becomes a set stability with probability one for the augmented system. Subsequently, certain criteria are proposed for the robust stability of the systems. Moreover, an algorithm is developed to verify the robust set stability of the augmented system based on truth matrices. Finally, the validity of the obtained results is demonstrated by an illustrative example.
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  • 文章类型: Journal Article
    目的:保护区外保护是中国生物多样性保护工作的主要贡献者,在支离破碎的景观中,在植树造林和低强度农业中实现了生物多样性保护。与分类多样性相比,功能性状与生态过程的关系更为紧密,并且反映了生态系统功能和物种对环境变化的反应。在这项研究中,我们选择了5个不同干扰程度的栖息地来探索土地利用对蚂蚁群落组成的影响,性状分布和功能多样性变化。我们评估了栖息地干扰如何影响蚂蚁群落组成和性状分布,并询问蚂蚁功能多样性是否对当地尺度的干扰作出反应?地点:吕春县,云南省,中国西南。方法:使用陷阱对蚂蚁群落进行调查。此外,我们测量了蚂蚁的四个形态特征(眼睛直径,眼睛之间的距离,后腿的股骨长度和韦伯的长度)以评估功能性状的分布和功能多样性。蚂蚁相对丰度的阴影图用于探索不同栖息地之间的物种分布。核密度图用于探索不同栖息地之间的蚂蚁性状分布模式。非度量多维缩放排序,根据蚂蚁韦伯的长度,用于探索不同栖息地之间的蚂蚁性状组成。第四角模型用于评估蚂蚁性状与环境变量之间的关联。Fric,选择RaoQ和FEve指数作为不同生境的多元功能性状空间和功能冗余的三个互补指标。结果:我们收集了14258只蚂蚁,代表89个物种,40属和七个亚科。Aphaenogasterschurri和Tetramoriumciumciatus是次生林的常见物种;P.sagei,P.Pieli,心脏condylawroughtonii,经常性的risnuwa,Tapinnomamelanocephalum,Monomoriumpharaonis和M.orientale是人工林中的常见物种;Iridomyrmexanceps和Cardiodylanuda是管理农场中的常见物种。蚂蚁的眼睛直径中等,眼睛之间的距离很窄,中等腿的长度和较小的身体尺寸在严重干扰的栖息地;和蚂蚁有一个增加的眼睛直径和眼睛之间的空间缩小,而在中度扰动的栖息地,腿长和韦伯的长度变得更短。蚂蚁性状组成,根据韦伯的长度,在五个栖息地之间显示出显着差异。第四角分析表明,蚂蚁物种性状与环境变量显着相关。次生林的功能多样性,紫胶种植和紫胶种植-玉米农林高于旱地农场和稻田。功能多样性与裸露地面覆盖呈显著负相关,与凋落叶覆盖呈显著正相关,落叶厚度和植物覆盖率。主要结论:我们的结果表明,蚂蚁性状的分布格局受到土地利用变化的影响,其次是局部尺度的人为干扰压力。受干扰较大的栖息地中的蚂蚁性状组成也与受干扰较小的栖息地不同。在更开放的栖息地中,人为干扰更大,这不利于大型蚂蚁的生存。与次生林相比,旱地农场和稻田的抵抗力较低,更脆弱,紫胶种植园具有蚂蚁群落的功能多样性,这表明紫胶人工林作为次生林可能对物种丧失具有抵抗力。
    Aim: Off-reserve conservation is a major contributor to China biodiversity conservation efforts, biodiversity conservation being achieved within afforestation and low-intensity agriculture in fragmented landscapes. Functional trait is more strongly related to ecological processes than taxonomic diversity and reflects ecosystem functioning and species responses to environmental changes. In this study, we selected five habitats that differ in degree of disturbance to explore the effects of land use on ant community compositions, traits distributions and functional diversity change. We assessed how habitat disturbance affects the ant community compositions and traits distributions and asked if ant functional diversity respond to disturbance at the local scale? Location: Lüchun County, Yunnan Province, southwest China. Methods: Pitfall traps were used to survey ant communities. Additionally, we measured four ant morphological traits (eyes diameter, distance between eyes, femur length of the hind-leg and Weber\'s length) to assess the functional traits distributions and functional diversity. Shade plot of ant relative abundance was used to explore species distribution amongst different habitats. Kernel density plot was used to explore ant traits distribution patterns amongst different habitats. Non-metric multi-dimensional scaling ordination, based on ant Weber\'s length, was used to explore the ant traits compositions amongst different habitats. The fourth corner model was used to evaluate the association between ant traits and environmental variables. The FRic, RaoQ and FEve indices were selected as three complementary measures of the multivariate functional traits space and functional redundancy of different habitats. Results: We collected 14258 ants, representing 89 species, 40 genera and seven subfamilies. Aphaenogasterschurri and Tetramoriumciliatum were the common species of secondary forest; P.sagei, P.pieli, Cardiocondylawroughtonii, Recurvidrisnuwa, Tapinnomamelanocephalum, Monomoriumpharaonis and M.orientale were the common species in plantations; and Iridomyrmexanceps and Cardiocondylanuda were the common species in managed farms. Ants had medium eye diameters, narrow distances between eyes, medium leg lengths and smaller body sizes in greatly-disturbed habitats; and ants had an increasing eye diameter and narrowing of the space between eyes, while the leg length and Weber\'s length became shorter in moderately-disturbed habitats. Ant trait composition, based on Weber\'s length, showed significantly differences amongst five habitats. The fourth corner analysis indicated that ant species traits were significantly correlated with environmental variables. The functional diversity of secondary forest, lac plantation and lac plantation-corn agroforest were higher than those in dryland farm and rice paddy. Functional diversities were significantly negatively correlated with bare ground cover and significantly positively correlated with leaf-litter cover, leaf-litter thickness and plant cover. Main conclusion: Our results indicated that ant traits distribution patterns were affected by land-use changes, followed by anthropogenic disturbance pressures at the local scale. Ant traits compositions in greatly-disturbed habitats also differed from the habitats with less disturbance. It is unfavourable for the survival of the large body-size ants in more open habitats with more anthropogenic disturbance. Compared with secondary forest, dryland farm and rice paddies were less resistant and more vulnerable and lac plantations had approximately functional diversity of ant communities, suggesting that lac plantations might be resistant as secondary forest to species loss.
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  • 文章类型: Journal Article
    慢性急性肝衰竭(ACLF)是全球肝脏相关死亡的主要原因,但其关键病理特征仍未完全定义。本研究旨在通过人肝组织转录组测序揭示乙型肝炎病毒相关ACLF(HBV-ACLF)的分子基础。从HBV相关疾病的不同阶段的患者共收集18人肝组织进行RNA测序,和来自患有ACLF的患者和小鼠模型的肝组织用于随后的验证。具体来说,与慢性乙型肝炎(CHB)和正常对照(NC)患者相比,在ACLF患者中鉴定了6,853个差异表达基因(DEGs)和5,038个差异表达转录本。通过KEGG途径富集分析进行的功能研究揭示了ACLF阶段突出的免疫和代谢失调。我们发现与免疫代谢紊乱相关的关键基因FGF19、ADCY8和KRT17,在ACLF的进展中显著上调。在人类和小鼠样本中验证了这三个关键基因,表明其在ACLF中的预后和治疗潜力。总之,我们的工作揭示免疫代谢紊乱与HBV-ACLF发病机制有关,提示FGF19,ADCY8和KRT17可能是HBV相关ACLF的敏感生物标志物.
    Acute-on-chronic liver failure (ACLF) is a major cause of liver-related death worldwide, but its key pathological features remain incompletely defined. This study aimed to reveal the molecular basis of hepatitis B virus-related ACLF (HBV-ACLF) by transcriptome sequencing of human liver tissue. A total of 18 human liver tissues from patients with different stages of HBV-related disease were collected for RNA sequencing, and liver tissues from patients and mouse models with ACLF were used for subsequent validation. Specifically, 6,853 differentially expressed genes (DEGs) and 5,038 differentially expressed transcripts were identified in patients with ACLF compared to patients with chronic hepatitis B (CHB) and normal controls (NCs). Investigation of functional by KEGG pathway enrichment analysis revealed prominent immune and metabolic dysregulation at the ACLF stage. We found that the key genes FGF19, ADCY8 and KRT17, which are related to immunometabolic disturbances, were significantly upregulated in the progression of ACLF. The three key genes were validated in human and mouse samples, indicating their prognostic and therapeutic potential in ACLF. In summary, our work reveals that immunometabolic disorder is involved in HBV-ACLF pathogenesis and indicates that FGF19, ADCY8 and KRT17 may be sensitive biomarkers for HBV-related ACLF.
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  • 文章类型: Journal Article
    背景:寻求通过森林缓解气候变化的国家需要适当的建模方法来预测森林中的碳(C)预算动态及其对干扰和管理的响应。加拿大森林部门的碳预算模型(CBM-CFS3)是一种可行且全面的工具,用于模拟广泛水平的森林C储量动态,但中国的差异仍有待解决。以贵州为例,我们根据中国的情况定制了CBM-CFS3模型,包括对地上生物量C库存算法的修改,增加竹林的C预算核算,经济林,和灌木森林,改善地下缓慢死亡有机质(DOM)池初始化的非林地,和其他模型设置。
    结果:模型验证中估计和测量的C密度之间的适当线性关系(R2=0.967,P<0.0001,斜率=0.904)证明了我们定制模型的高准确性和可靠性。我们使用我们的定制模型进一步模拟了1990-2016年期间贵州森林C种群和干扰影响的时空动态。结果表明,生态系统总的碳储量和碳密度,和生物质中的C库存,垃圾,枯木,贵州土壤持续显著增加,而土壤碳密度在整个时期都在下降,这可能归因于森林砍伐历史和气候变化。总生态系统C存量从1990年的1220TgC增加到2016年的1684TgC,速度为18TgCyr-1,大部分地区显着增强,尤其是在南部和西北部。扰动引起的生态系统C存量和C支出的总减少达到97.6TgC和120.9TgC,分别,但由于1990-2016年期间受干扰森林面积的减少,两者都表现出显着下降趋势。再生测井,为农业砍伐森林,收获伐木导致最大的C库存减少和C支出,而植树造林和森林自然扩张对碳储量的增长贡献最大。
    结论:在整个研究期间,贵州森林是大规模造林的净碳汇;我们定制的CBM-CFS3模型可以作为估算中国森林碳储量和扰动影响的更有效和准确的方法,并进一步启发其他地区的模型定制。
    BACKGROUND: Countries seeking to mitigate climate change through forests require suitable modelling approaches to predict carbon (C) budget dynamics in forests and their responses to disturbance and management. The Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) is a feasible and comprehensive tool for simulating forest C stock dynamics across broad levels, but discrepancies remain to be addressed in China. Taking Guizhou as the case study, we customised the CBM-CFS3 model according to China\'s context, including the modification of aboveground biomass C stock algorithm, addition of C budget accounting for bamboo forests, economic forests, and shrub forests, improvement of non-forest land belowground slow dead organic matter (DOM) pool initialisation, and other model settings.
    RESULTS: The adequate linear relationship between the estimated and measured C densities (R2 = 0.967, P < 0.0001, slope = 0.904) in the model validation demonstrated the high accuracy and reliability of our customised model. We further simulated the spatiotemporal dynamics of forest C stocks and disturbance impacts in Guizhou for the period 1990-2016 using our customised model. Results shows that the total ecosystem C stock and C density, and C stocks in biomass, litter, dead wood, and soil in Guizhou increased continuously and significantly, while the soil C density decreased over the whole period, which could be attributed to deforestation history and climate change. The total ecosystem C stock increased from 1220 Tg C in 1990 to 1684 Tg C in 2016 at a rate of 18 Tg C yr-1, with significant enhancement in most areas, especially in the south and northwest. The total decrease in ecosystem C stock and C expenditure caused by disturbances reached 97.6 Tg C and 120.9 Tg C, respectively, but both represented significant decreasing trends owing to the decline of disturbed forest area during 1990-2016. Regeneration logging, deforestation for agriculture, and harvest logging caused the largest C stock decrease and C expenditure, while afforestation and natural expansion of forest contributed the largest increases in C stock.
    CONCLUSIONS: The forests in Guizhou were a net carbon sink under large-scale afforestation throughout the study period; Our customised CBM-CFS3 model can serve as a more effective and accurate method for estimating forest C stock and disturbance impacts in China and further enlightens model customisation to other areas.
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  • 文章类型: Journal Article
    宝鸡是中国西北地区典型的重工业城市。它的空气质量受到工厂排放的极大影响。从人为来源大量排放的细颗粒物(PM2.5)中的元素可能会对人类造成多种健康影响。在这项研究中,由于2020年COVID-19的爆发,在城市封锁期(1月9日至23日)和封锁期(1月26日至2月9日)之前的弱和强人为干扰情景下,使用在线AMMS-100大气重金属分析仪量化PM2.5中的30种元素。在封锁期间,总量化元素的平均总浓度为3475.0ng/m3,比封锁前的一周和强烈人为干扰情景分别低28%和33%。铬(Cr)元素的减少量最大,钛(Ti),锰(Mn),和锌(Zn),与宝鸡的产业结构相一致。当政府对行业发出警告以减少运营和生产时,大多数元素的质量浓度显着降低。灰尘,交通来源,燃烧,有色金属加工,与钛相关的工业加工是封锁前阶段元素的贡献者,由正矩阵分解(PMF)模型进行分配。在封锁期间,定量元素的组成和来源发生了重大变化。进行了健康评估,并以分配的来源为特征。锌的非致癌风险(HQ)最高,展示了相关工业活动的高排放。在封锁期间,砷(As)的浓度水平超过了寿命增加的致癌风险(ILCR)。这可以归因于在封锁期内庆祝农历新年的传统烟花活动。
    Baoji is a typical heavy industrial city in northwest China. Its air quality is greatly impacted by the emission from the factories. Elements in fine particulate matter (PM2.5) that are greatly emitted from anthropogenic sources could pose diverse health impacts on humans. In this study, an online AMMS-100 atmospheric heavy metal analyzer was used to quantify 30 elements in PM2.5 under the weak and strong anthropogenic disturbance scenarios before the city lockdown period (from January 9th to 23rd) and the lockdown period (from January 26th to February 9th) due to the outbreak of COVID-19 in 2020. During the lockdown period, the average total concentration of total quantified elements was 3475.0 ng/m3, which was 28% and 33% lower than that of the week and strong anthropogenic disturbance scenarios during the pre-lockdown period. The greatest reductions were found for the elements of chromium (Cr), titanium (Ti), manganese (Mn), and Zinc (Zn), consistent with the industrial structure of Baoji. The mass concentrations of most elements showed obvious reductions when the government post-alerted the industries to reduce the operations and production. Dust, traffic sources, combustion, non-ferrous metal processing, and Ti-related industrial processing that are the contributors of the elements in the pre-lockdown period were apportioned by the positive matrix factorization (PMF) model. Substantial changes in the quantified elements\' compositions and sources were found in the lockdown period. Health assessment was conducted and characterized by apportioned sources. The highest non-carcinogenic risk (HQ) was seen for Zn, demonstrating the high emissions from the related industrial activities. The concentration level of arsenic (As) exceeded the incremental lifetime carcinogenic risk (ILCR) in the lockdown period. This could be attributed to the traditional firework activities for the celebration of the Chinese New Year within the lockdown period.
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  • 文章类型: Journal Article
    This paper is concerned with a theoretical investigation on the robust modified function projective lag synchronization (MFPLS) between two complex networks with nonlinear couplings, different-dimensional nodes, parameter disturbances and external disturbances. Some novel robust hybrid controllers are designed to address such synchronization problems for networks with and without disturbances, in which adaptive updated laws of disturbances are adopted to attenuate the disturbances occurred in networks. By utilizing Lyapunov functional method, synchronization criteria are derived by strict theoretical proof. Compared with existing jobs, the proposed model and synchronization type are more general. Two examples are presented to verify our results.
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  • 文章类型: Journal Article
    In this paper, we investigated the finite-time consensus tracking problem for multi-agent systems with external bounded disturbances and input bounded disturbances and unknown velocities. Based on the Lyapunov finite-time theorem, a novel finite-time consensus control is constructed by using the backstepping method. For unknown velocities, the high-gain observer is used to estimate the velocity information. It is proved that the consensus can be achieved in finite time. The consensus shows fast response and strong robustness to various disturbances. Finally, the effectiveness of the results is illustrated by numerical simulations.
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  • 文章类型: English Abstract
    The distribution of external phosphorus (P) in the overlying water, pore water, and sediment under different disturbances were investigated and the transformation between internal P forms was analyzed. The results show that physical disturbances can promote the migration of external P from the overlying water to the sediment. In addition, the enhancement was even higher due to the bioturbation of the combined disturbances. Noticeably, the improvement of the P migration in the control was lowest, compared with the three disturbances. This may be attributed to the penetration of dissolved oxygen. Meanwhile, the physical disturbance reduced the average content of (dissolved organic phosphorus) DIP in the pore water by 12.13% (a mean of 6d and 10d), compared with the control. However the reduction was less than that associated with the bioturbation (38.63%) and the combined disturbance (50.79%), respectively. These three disturbances may promote the formation of Fe/Al-P and Ca-P. The formation of Fe/Al-P and Ca-P was largest under the physical disturbance. However, the algal-available phosphorus (AAP) is reduced due to the physical disturbance, suggesting that physical disturbance may promote the transformation of AAP to occluded Fe/Al-P or Ca-P.
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  • 文章类型: Journal Article
    In this paper, the H∞ performance and control problems for linear systems with interval state or input delays and disturbances are investigated. In order to exploit more information on the delay range, the quadruple -integral terms and quadratic forms of triple integrals are introduced into the Lyapunov-Krasovskii functional (LKF). Particularly, an improved integral inequality is developed for estimation of the cross terms in triple-integral type, which displays significant improvement over the Wirtinger inequality. As a result, a less conservative H∞ performance criterion is derived without requiring many slack variables. Based on the criterion, the H∞ controller design approaches are obtained. Besides the numerical examples, the applications to the practical systems are also provided to illustrate the effectiveness of the proposed approaches.
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  • 文章类型: Journal Article
    Due to the nonlinearity and time variation of a two-axis inertially stabilized platform (ISP) system, the conventional feedback control cannot be utilized directly. To realize the control performance with fast dynamic response and high stabilization precision, the dynamic model of the ISP system is expected to match the ideal model which satisfies the desired control performance. Therefore, a composite control method based on the adaptive radial basis function neural network (RBFNN) feedback control and the extended state observer (ESO), is proposed for ISP. The adaptive RBFNN is proposed to generate the feedback control parameters online. Based on the state error information in the working process, the adaptive RBFNN can be constructed and optimized directly. Therefore, no priori training data is needed for the construction of the RBFNN. Furthermore, a linear second-order ESO is constructed to compensate for the composite disturbance. The asymptotic stability of the proposed control method has been proven by the Lyapunov stability theory. The applicability of the proposed method is validated by a series of simulations and flight tests.
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