Global Well-Posedness and Stability for a Viscoelastic Plate Equation with a Time Delay

A plate equation with a memory term and a time delay term in the internal feedback is investigated. Under suitable assumptions, we establish the global well-posedness of the initial and boundary value problem by using the Faedo-Galerkin approximations and some energy estimates. Moreover, by using energy perturbation method, we prove a general decay result of the energy provided that the weight of the delay is less than the weight of the damping

Large-time behavior of solutions for the one-dimensional infrarelativistic model of a compressible viscous gas with radiation

AbstractIn this paper, assuming suitable hypotheses on the transport coefficients, we prove the large-time behavior, as time tends to infinity, of solutions in Hi=Hi×H0i×Hi×Hi+1 (i=1,2) for the one-dimensional infrarelativistic model of a compressible viscous gas with radiation

The motion characteristics of a cylinder vehicle in the oblique water-exit process

The hydrodynamic model of a vehicle exiting the water surface obliquely has been analyzed. The analyzed object is a cylinder vehicle and its motion characteristics. Two methods have been used to simulate the water-exit process under the same conditions: Numerical Simulation Method (NSM) and Theoretical Model Solution Method (TMSM). The comparison results of the two methods can validate the hydrodynamic model founded in this paper. Different initial angles and different initial velocities have been simulated by this hydrodynamic model and the numerical simulation has been analyzed. The analysis reveals the rule of change of altitude and position of the vehicle in the water-exit process, and its motion after it exits the water surface. This paper explains why it is more difficult for the vehicle to exit the water obliquely than vertically. The results show that the hydrodynamic model of the water exiting vehicle can be used to research the exiting water motion characteristics. The models simulate the physics of motion realistically and this hydrodynamic model can be used as a foundation for the future research of the stability and control of a vehicle exiting the water

Decay rates for a coupled viscoelastic Lamé system with strong damping

In [6] Beniani, Taouaf and Benaissa studied a coupled viscoelastic Lamé system with strong dampings and established a general decay result. In this paper, we continue to study the system. Assuming gi0(t) ≤−ξi(t)Hi(gi(t)), i = 1,2, we establish an explicit and general decay result, which is optimal, to the system. This result improves earlier results in [6]

Minimum Thrust of a Morphing Unmanned Submersible Aerial Vehicle in the Water-to-Air Motion

This study proposes a new water-to-air motion pattern that combines morphing with power switch. Under the conditions of this pattern, the vehicle needs a certain thrust to avoid falling back after jumping out of the water. The minimum thrust is among the most important design parameters of a vehicle. The water-exit and take-off dynamic models of the vehicle are constructed through the force and motion analysis before and after morphing. The control model of the vehicle is created by analysing the control problem in the take-off motion. The minimum thrust at different initial water-exit angles is computed using the optimum searching algorithm. The following law is then established: the greater the initial water-exit angle, the smaller the minimum thrust required in the air. Such a relationship becomes insignificant when the initial water-exit angle exceeds 40°

Stability analysis for a Rao-Nakra sandwich beam equation with time-varying weights and frictional dampings

In this paper, we studied the asymptotic behavior of solutions for a Rao-Nakra sandwich beam equation with time-varying weights and frictional damping terms acting complementarily in the domain. We studied the effect of the three damping on the asymptotic behavior of the energy function. Under nonrestrictive on the growth assumption on the frictional damping terms, we established exponential and general energy decay rates for this system by using the multiplier approach. The results generalized some earlier decay results on the Rao-Nakra sandwich beam equation

Chromosome-level genome assembly of a high-altitude-adapted frog (Rana kukunoris) from the Tibetan plateau provides insight into amphibian genome evolution and adaptation

Background The high-altitude-adapted frog Rana kukunoris, occurring on the Tibetan plateau, is an excellent model to study life history evolution and adaptation to harsh high-altitude environments. However, genomic resources for this species are still underdeveloped constraining attempts to investigate the underpinnings of adaptation. Results The R. kukunoris genome was assembled to a size of 4.83 Gb and the contig N50 was 1.80 Mb. The 6555 contigs were clustered and ordered into 12 pseudo-chromosomes covering similar to 93.07% of the assembled genome. In total, 32,304 genes were functionally annotated. Synteny analysis between the genomes of R. kukunoris and a low latitude species Rana temporaria showed a high degree of chromosome level synteny with one fusion event between chr11 and chr13 forming pseudo-chromosome 11 in R. kukunoris. Characterization of features of the R. kukunoris genome identified that 61.5% consisted of transposable elements and expansions of gene families related to cell nucleus structure and taste sense were identified. Ninety-five single-copy orthologous genes were identified as being under positive selection and had functions associated with the positive regulation of proteins in the catabolic process and negative regulation of developmental growth. These gene family expansions and positively selected genes indicate regions for further interrogation to understand adaptation to high altitude. Conclusions Here, we reported a high-quality chromosome-level genome assembly of a high-altitude amphibian species using a combination of Illumina, PacBio and Hi-C sequencing technologies. This genome assembly provides a valuable resource for subsequent research on R. kukunoris genomics and amphibian genome evolution in general.Peer reviewe

Toxin-Encoding Genes and Drug Susceptibility of Staphylococcus aureus from Vegetables Consumed Raw

Objective: To investigate the toxin-encoding genes and antibiotic susceptibility of Staphylococcus aureus isolates from retail vegetables consumed raw. Methods: The 27 S. aureus isolates from tomato, lettuce, spinach and cabbage collected from supermarkets, farmers’ markets and vendors in Xi’an, Baoji, Hanzhong and Yan’an of Shaanxi province were identified by PCR amplification of the nuc gene, the prevalence of 19 toxin-encoding genes and 12 antibiotic resistance encoding genes in these isolates was evaluated, and the antibiotic susceptibility to 14 antibiotics was determined by the agar dilution method. Results: Seventeen of these isolates were identified as methicillin-susceptible S. aureus (MSSA) and the remaining 10 isolates were identified as oxacillin-susceptible methicillin-resistant S. aureus (OS-MRSA). A total of eight toxin-encoding genes were detected in the 27 isolates, and the detection rate (29.6%, 8/27) of sec was highest. In addition, 51.9% (14/27) of these isolates carried at least one toxin-encoding gene, and nine toxin-encoding gene profiles were totally identified. Seven antibiotic resistance genes including blaZ, mecA, ermC, tetK, dfrG, dfrK, and aac(6’)/aph(2”) were detected. The isolates were all susceptible to oxacillin, rifampicin and vancomycin. Resistance to amoxicillin/clavulanate was most commonly detected, followed by trimethoprim/sulfamethoxazole, ampicillin, erythromycin, cefoxitin, ciprofloxacin, ceftriaxone, gentamicin, amikacin, tetracycline and chloramphenicol. Twenty-four (88.9%) isolates were resistant to three or more antibiotics. Conclusion: OS-MRSA is prevalent in vegetables consumed raw in Shaanxi province, and it has multiple antibiotic resistances and carries multiple toxin-encoding gens, posing a potential food safety hazard