Finite-Time Boundedness Control of Time-Varying Descriptor Systems

This paper mainly studies a control problem of finite-time boundedness of time-varying descriptor systems. Firstly, a sufficient and necessary condition of finite-time stability is given, then a sufficient condition of finite-time boundedness for time-varying descriptor systems is given. Secondly, we analyze the finite-time boundedness control problem and design the finite-time state feedback controller; the controller is given based on LMIs for time-varying descriptor systems and time-varying uncertain descriptor systems, respectively. Finally, a numerical example is given to prove the effectiveness of the method

Influence of the counterweight location on flutter by an all-moving fin

In this study, we investigate the influence of the location of the counterweight on the flutter characteristics of an all-moving fin. The modal characteristics of the fin are obtained via the finite element method and sensitivity analysis. The supersonic unsteady aerodynamic loads are calculated by local piston theory. The flutter motion equations based on the modal coordinates are established by applying the Lagrange equation. The flutter boundary with respect to the mode characteristics, especially the nodal lines of the mode shapes, has been studied. The results show that different counterweight locations can result in different flutter boundaries. When the counterweight is located at the intersection of the leading edge and tip chord, the increase in the critical dynamic pressure is most obvious. In engineering design, the flutter suppression of an all-moving fin cannot be guided simply by the forward movement of the mass centroid or an increase in the frequency ratio of torsion relative to bending. When the counterweight is added around the leading edge of the root chord to move the mass centroid forward, the critical dynamic pressure can even decrease. The counterweight suppresses the flutter by weakening the coupling of different mode shapes. Thus, the counterweight should be placed at the location where the degree of bending-torsion coupling is reduced

Numerical investigation of FRCM-strengthened corroded RC beams under cathodic protection

Fibric reinforced cementitious matrix (FRCM) composites have been used to improve the mechanical performance of reinforced concrete beams subjected to degradation in the past decades. Recently, dual-functional carbon fibres have been explored to provide both structural strengthening to RC beams and cathodic protection to reinforcement bars. This paper investigates the loading responses and structural behaviour of RC beams subjected to different levels of corrosion, protected by impressed current cathodic protection and structurally strengthened by external bonded FRCM. A numerical model is developed for the corroded RC beams under impressed current cathodic protection and structural strengthening by the FRCM composite. Upon validation against experimental results collected from the literature, the finite element model is then used for parametric study. A number of numerical results are generated to analyse the effects of key parameters, including the corrosion rate, degradation level of interfacial bonding properties due to anode acidification, and end anchorage, followed by detailed discussions. It is found that the significance of the corrosion of steel reinforcement bars significantly affects the load-carrying capacity of the beams. Increasing the corrosion rate from 0 to 40% reduces the load-carrying capacity of un-strengthened beams to 45% of the original capacity. Therefore, the cathodic protection provided by the C-FRCM plate is important to the reinforcement bars as it can avoid the cross-section area reduction of reinforcement bars and, thus, the main loading capacities of the beams. In this study, the degradation of the bonding properties at the interface of carbon fibre and the cementitious matrix due to anode acidification during impressed current cathodic protection is also considered. It is found that the bond strength of the C-FRCM plate has a slight effect on the load-carrying capacity of the beam. In addition, the application of end anchorage can significantly enhance both the load-carrying capacity and ductility of the beams. The rates of enhancement, if compared to the beams with no end anchorage, can reach up to 60%

The Analysis of Key Issues for Virtual Reservoirs Application in Coalbed Methane Development

Based on flow state of coalbed methane (CBM) migration, coal reservoir broadly is divided into outburst and non-outburst coal. Because of strong water sensitivity and poor hydraulic fracturing effect of outburst coal, hydraulic fracturing measures to increase permeability which used to be applied in non-outburst coal do not suitable for outburst coal. Coal floor is selected as virtual reservoir for roof maintenance when mining coal, Depending on a zero radius drilling and high-energy gas loose blasting technology, the reservoir and the coal floor become transfixion, so that the CBM diffuse to the floor cracks, and then migrate into the wellbore. The "highway" of CBM migration is built through virtual reservoir, which would be expected to break through the forbidden zone of traditional CBM development, and joint two-energy exploitation of coal and CBM can achieve, so that gas disaster and greenhouse gas emission will reduce greatly. Therefore, virtual reservoir has broad application prospect.特集 : 「資源、新エネルギー、環境、防災研究国際セミナー

A novel ZRS variant causes preaxial polydactyly type I by increased sonic hedgehog expression in the developing limb bud.

PurposePreaxial polydactyly (PPD) is a common congenital hand malformation classified into four subtypes (PPD I-IV). Variants in the zone of polarizing activity regulatory sequence (ZRS) within intron 5 of the LMBR1 gene are linked to most PPD types. However, the genes responsible for PPD I and the underlying mechanisms are unknown.MethodsA rare large four-generation family with isolated PPD I was subjected to genome-wide genotyping and sequence analysis. In vitro and in vivo functional studies were performed in Caco-2 cells, 293T cells, and a knockin transgenic mouse model.ResultsA novel g.101779T>A (reference sequence: NG_009240.2; position 446 of the ZRS) variant segregates with all PPD I-affected individuals. The knockin mouse with this ZRS variant exhibited PPD I phenotype accompanying ectopic and excess expression of Shh. We confirmed that HnRNP K can bind the ZRS and SHH promoters. The ZRS mutant enhanced the binding affinity for HnRNP K and upregulated SHH expression.ConclusionOur results identify the first PPD I disease-causing variant. The variant leading to PPD I may be associated with enhancing SHH expression mediated by HnRNP K. This study adds to the ZRS-associated syndromes classification system for PPD and clarifies the underlying molecular mechanisms

Future Orientation, Social Support, and Psychological Adjustment among Left-behind Children in Rural China: A Longitudinal Study

Existing research has found that parental migration may negatively impact the psychological adjustment of left-behind children. However, limited longitudinal research has examined if and how future orientation (individual protective factor) and social support (contextual protective factor) are associated with the indicators of psychological adjustment (i.e., life satisfaction, school satisfaction, happiness, and loneliness) of left-behind children. In the current longitudinal study, we examined the differences in psychological adjustment between left-behind children and non-left behind children (comparison children) in rural areas, and explored the protective roles of future orientation and social support on the immediate (cross-sectional effects) and subsequent (lagged effects) status of psychological adjustment for both groups of children, respectively. The sample included 897 rural children (Mage = 14.09, SD = 1.40) who participated in two waves of surveys across six months. Among the participants, 227 were left-behind children with two parents migrating, 176 were with one parent migrating, and 485 were comparison children. Results showed that, (1) left-behind children reported lower levels of life satisfaction, school satisfaction, and happiness, as well as a higher level of loneliness in both waves; (2) After controlling for several demographics and characteristics of parental migration among left-behind children, future orientation significantly predicted life satisfaction, school satisfaction, and happiness in both cross-sectional and longitudinal regression models, as well as loneliness in the longitudinal regression analysis. Social support predicted immediate life satisfaction, school satisfaction, and happiness, as well as subsequent school satisfaction. Similar to left-behind children, comparison children who reported higher scores in future orientation, especially future expectation, were likely to have higher scores in most indicators of psychological adjustment measured at the same time and subsequently. However, social support seemed not exhibit as important in the immediate status of psychological adjustment of comparison children as that of left-behind children. Findings, implications, and limitations of the present study were discussed