This paper provides an overview and makes a deep investigation on sampled-data-based event-triggered control and filtering for networked systems. Compared with some existing event-triggered and ...self-triggered schemes, a sampled-data-based event-triggered scheme can ensure a positive minimum inter-event time and make it possible to jointly design suitable feedback controllers and event-triggered threshold parameters. Thus, more attention has been paid to the sampled-data-based event-triggered scheme. A deep investigation is first made on the sampled-data-based event-triggered scheme. Then, recent results on sampled-data-based event-triggered state feedback control, dynamic output feedback control, H ∞ filtering for networked systems are surveyed and analyzed. An overview on sampled-data-based event-triggered consensus for distributed multiagent systems is given. Finally, some challenging issues are addressed to direct the future research.
This paper is concerned with the state estimation for neural networks with two additive time-varying delay components. Three cases of these two time-varying delays are fully considered: 1) both ...delays are differentiable uniformly bounded with delay-derivative bounded by some constants; 2) one delay is continuous uniformly bounded while the other is differentiable uniformly bounded with delay-derivative bounded by certain constants; and 3) both delays are continuous uniformly bounded. First, an extended reciprocally convex inequality is introduced to bound reciprocally convex combinations appearing in the derivative of some Lyapunov-Krasovskii functional. Second, sufficient conditions are derived based on the extended inequality for three cases of time-varying delays, respectively. Third, a linear-matrix-inequality-based approach with two tuning parameters is proposed to design desired Luenberger estimators such that the error system is globally asymptotically stable. This approach is then applied to state estimation on neural networks with a single interval time-varying delay. Finally, two numerical examples are given to illustrate the effectiveness of the proposed method.
Offshore platforms are widely used to explore, drill, produce, storage, and transport ocean resources and are usually subject to environmental loading, such as waves, winds, ice, and currents, which ...may lead to failure of deck facilities, fatigue failure of platforms, inefficiency of operation, and even discomfort of crews. In order to ensure reliability and safety of offshore platforms, it is of great significance to explore a proper way of suppressing vibration of offshore platforms. There are mainly three types of control schemes, i.e., passive control schemes, semi-active control schemes, and active control schemes, to deal with vibration of offshore platforms. This paper provides an overview of these schemes. Firstly, passive control schemes and several semi-active control schemes are briefly summarized. Secondly, some classical active control approaches, such as optimal control, robust control, and intelligent control, are briefly reviewed. Thirdly, recent advances of active control schemes with delayed feedback control, sliding model control, sampled-data control, and network-based control are deeply analyzed. Finally, some challenging issues are provided to guide future research directions.
The cobalt‐catalyzed alkoxylation of C(sp2)H bonds in aromatic and olefinic carboxamides has been developed. The reaction proceeded under mild conditions in the presence of Co(OAc)2⋅4H2O as the ...catalyst and tolerates a wide range of both alcohols and benzamide substrates, including even olefinic carboxamides. In addition, this reaction is the first example of the direct alkoxylation of alkenes through CH bond activation.
Alcohols in action: A wide range of alcohols and benzamide substrates functionalized with electron‐rich or electron‐poor substituents are tolerated in the title reaction. This practical reaction occurs under mild conditions.
A highly efficient cobalt(II)‐catalyzed alkynylation/annulation of terminal alkynes assisted by an N,O‐bidentate directing group is described. This protocol is characterized by wide substrate scope ...utilizing cheap cobalt catalysts, and offers a new approach to 3‐methyleneisoindolin‐1‐one, which can be converted into an oxadiazine salt in one step. Moreover, the directing group could be removed in three steps.
This brief is concerned with consensus of hybrid behavior for graphical coordination games. We take into account a multi-agent system with two agent-unions that have various preferences. Interactions ...among agents in the multi-agent system are modelled as a hybrid graphical coordination game, in which three kinds of payoff matrices are designed. By using potential game theory, necessary and sufficient conditions are established for achieving consensus of the hybrid graphical coordination game. Finally, several numerical simulations are provided to validate the effectiveness of our theoretical results.
We report an approach for the synthesis of benzothiophene motifs under electrochemical conditions by the reaction of sulfonhydrazides with internal alkynes. Upon the formation of a quaternary ...spirocyclization intermediate by the selective
ipso
-addition instead of an
ortho
-attack, the S-migration process was rationalized to lead to the products. Computational studies revealed the selectivity and the compatibility of drug molecules showcased the potential application of the protocols.
Although numerous studies on the impacts of climate change on biodiversity have been published, only a handful are focused on the intraspecific level or consider population‐level models (separate ...models per population). We endeavored to fill this knowledge gap relative to the Qinghai‐Tibetan plateau (QTP) by combining species distribution modeling (SDMs) with population genetics (i.e., population‐level models) and phylogenetic methods (i.e., phylogenetic tree reconstruction and phylogenetic diversity analyses). We applied our models to 11 endemic and widely distributed herpetofauna species inhabiting high elevations in the QTP. We aimed to determine the influence of environmental heterogeneity on species’ responses to climate change, the magnitude of climate‐change impacts on intraspecific diversity, and the relationship between species range loss and intraspecific diversity losses under 2 shared socioeconomic pathways (SSP245 and SSP585) and 3 future periods (2050s, 2070s, and 2090s). The effects of global climatic change were more pronounced at the intraspecific level (22% of haplotypes lost and 36% of populations lost) than the morphospecies level in the SSP585 climate change scenario. Maintenance of genetic diversity was in general determined by a combination of factors including range changes, species genetic structure, and the part of the range predicted to be lost. This is owing to the fact that the loss and survival of populations were observed in species irrespective of the predicted range changes (contraction or expansion). In the southeast (mountainous regions), climate change had less of an effect on range size (>100% in 3 species) than in central and northern QTP plateau regions (range size <100% in all species). This may be attributed to environmental heterogeneity, which provided pockets of suitable climate in the southeast, whereas ecosystems in the north and central regions were homogeneous. Generally, our results imply that mountainous regions with high environmental heterogeneity and high genetic diversity may buffer the adverse impacts of climate change on species distribution and intraspecific diversity. Therefore, genetic structure and characteristics of the ecosystem may be crucial for conservation under climate change.
Impactos del cambio climático sobre la diversidad de herpetofauna en la meseta Qinghai‐Tíbet
Región
Aunque se han publicado numerosos estudios sobre los impactos del cambio climática en la biodiversidad, son muy pocos los que se enfocan en el nivel intraespecífico o que consideran modelos a nivel poblacional (modelos separados por población). Intentamos cerrar este vacío de conocimiento en relación con la meseta Qinghai‐Tíbet (MQT) con la combinación entre modelos de distribución de especies (MDE) y genética poblacional (modelos a nivel poblacional) y métodos filogenéticos (reconstrucción de árboles filogenéticos y análisis de diversidad filogenética). Aplicamos nuestros modelos a once especies endémicas de herpetofauna con distribución amplia en las elevaciones más altas de la MQT. Nos planteamos determinar la influencia de la heterogeneidad de las especies sobre la respuesta de las especies al cambio climático, la magnitud de los impactos del cambio climático sobre la diversidad intraespecífica y la relación entre la pérdida de distribución de la especie y las pérdidas de diversidad intraespecífica bajo dos vías socioeconómicas (SSP245 y SSP585) y tres periodos del futuro (2050s, 2070s y 2090s). Los efectos del cambio climático global fueron más pronunciados a nivel intraespecífico (22% de pérdida en los haplotipos y 36% en las poblaciones) que al nivel morfoespecie en el escenario de cambio climático SSP585. El mantenimiento de la diversidad genética casi siempre estuvo determinado por una combinación de factores que incluyen cambios en la distribución, estructura genética de las especies y la parte de la distribución que se pronosticó se perdería. Esto se debe a que observamos la pérdida y supervivencia de las poblaciones sin importar los cambios pronosticados en la distribución (contracción o expansión). En las regiones montañosas del sureste, el cambio climático tuvo un efecto menor sobre la distribución (>100% en tres especies) comparado con las regiones de la meseta central y del norte de la MQT (distribución <100% en todas las especies). Esto puede atribuirse a la heterogeneidad ambiental, la cual proporciona recovecos de clima adecuado en el sureste, mientras que los ecosistemas en las regiones central y norte fueron homogéneos. De manera general, nuestros resultados implican que las regiones montañosas con una elevada heterogeneidad ambiental y una gran diversidad genética podrían reducir los impactos adversos del cambio climático sobre la distribución de las especies y la diversidad intraespecífica. Por lo tanto, la estructura genética y las características del ecosistema pueden ser cruciales para conservar bajo el cambio climático.
【摘要】
尽管已有大量有关气候变化对生物多样性影响的研究发表, 但只有少数研究考虑种下或种群水平的模型。我们将物种分布模型(SDMs)与种群遗传学和系统发生学方法相结合, 填补青藏高原地区(QTP)在这一方面的研究空白。我们对11种栖息在青藏高原特有且分布广泛的两栖爬行动物进行了模型分析, 探究环境异质性对物种响应气候变化的影响、气候变化对种内多样性的影响程度、以及在SSP245和SSP585两种情景下, 未来(2050年、2070年和2090年)物种分布范围丧失与种内多样性丧失之间的关系。结果显示, 在SSP585气候变化情景中, 在种下有22%的单倍型和36%的种群将会丢失, 全球气候变化对种内多样性的影响比种间更为明显。遗传多样性是否能够维持一般由多种因素共同决定, 包括分布区的变化、物种遗传结构以及预测丢失的分布区。在青藏高原东南部山区, 气候变化对物种分布范围大小的影响(有3个物种的分布范围扩张)小于青藏高原北部和中部地区(所有物种的分布范围均缩小), 主要原因可能是东南部环境异质性更高, 物种可以选择较为合适的生境, 而北部和中部地区环境则趋于同质化。本研究结果表明, 环境异质性高、遗传多样性高的山区可以缓冲气候变化对物种分布和种内多样性的不利影响。因此, 生态系统的遗传结构和特征对于气候变化下的多样性保护至关重要。
This paper is concerned with delayed H∞ control for an offshore steel jacket platforms subject to external wave force. By artificially introducing a proper time-delay into control channel, a delayed ...H∞ controller is designed to attenuate the wave-induced vibration of the offshore platform and thereby improve the control performance of the system. The problem of the controller design is transformed into a nonlinear minimization problem. It is shown through simulation results that compared with the delay-free H∞ control scheme, the vibration amplitudes of the offshore steel jacket platform with the delayed H∞ control scheme are in the same level as the ones with the delay-free H∞ control scheme, while the required control force by the delayed H∞ control scheme is much smaller than that by the delay-free H∞ control scheme. Compared with the feedforward and feedback optimal control scheme, both the vibration amplitudes of the offshore platform and the required control force with the delayed H∞ control scheme are smaller than the ones with the feedforward and feedback optimal control scheme.
Comparative analysis of primate genomes within a phylogenetic context is essential for understanding the evolution of human genetic architecture and primate diversity. We present such a study of 50 ...primate species spanning 38 genera and 14 families, including 27 genomes first reported here, with many from previously less well represented groups, the New World monkeys and the Strepsirrhini. Our analyses reveal heterogeneous rates of genomic rearrangement and gene evolution across primate lineages. Thousands of genes under positive selection in different lineages play roles in the nervous, skeletal, and digestive systems and may have contributed to primate innovations and adaptations. Our study reveals that many key genomic innovations occurred in the Simiiformes ancestral node and may have had an impact on the adaptive radiation of the Simiiformes and human evolution.
