Effect of Fiber on Residual Strength and High Temperature Burst Performance of Ultra High Performance Concrete

In this paper, the effects of fiber on the residual strength and high temperature burst performance of ultra-high performance concrete are studied. This paper analyzes the performance change law of concrete after high temperature from three aspects: mass loss, ultrasonic wave velocity and compressive strength. The results show that with the increase of heating temperature, the mass loss increases and the ultrasonic wave velocity decreases. The compressive strength of concrete increases gradually before 300 ℃ and decreases gradually after 400 ℃. Mixing PVA fiber and steel fiber can not only improve the burst resistance of ultra-high performance concrete at high temperature, but also have high residual strength. This paper discusses the high temperature burst mechanism of ultra-high performance concrete, which is caused by the change of steam pressure and microstructure.

Weaving and mechanical properties test of polylactic acid/ramie composite fabric

In view of the weak mechanical properties of polylactic acid fiber, the excellent mechanical properties of ramie fiber are selected to enhance the performance of polylactic acid fiber, thereby forming a composite fabric, and weaving plain weave fabric, twill weave fabric, satin weave fabric and square plain fabric by weaving method., Twill change fabric and satin change fabric six kinds of fabrics. Electronic thickness meter, electronic strength meter, and electronic bursting tester were used to test the thickness, tensile fracture and burst performance of 6 kinds of fabrics, and the reasons for the differences between the fabrics were discussed. The research results show that the mechanical properties of composite fabrics are better than those of pure polylactic acid fabrics. In addition, in terms of tensile fracture performance, the satin weave fabric is the strongest, and the satin weave is the strongest in burst performance. In terms of fabric thickness, the lowest thickness value is plain weave, but the thickness value, tensile breaking and bursting properties of square flat fabrics are ranked second, so the overall performance is always the strongest.

Burst strength analysis of composite overwrapped pressure vessel using finite element method

The purpose of this numerical study was to investigate the burst performance of a type III composite overwrapped pressure vessel (COPV) using finite element methods. An Aluminum overwrapped composites pressure vessel was modeled from four layers of carbon fiber/epoxy ply with 0.762 mm and arranged in two different sequences and orientations. The overwrap composite pressure vessel burst performance was examined by applying an internal pressure of 55 MPa on a ply arrangement of [-15°/0°/+15°/90°] and other research findings on [+55°/-55°] as an optimum filament winding angle were used for comparison purpose. Moreover a ply level orientation effect analysis, which is a superior feature of ABAQUS, was used for the composite modelling. The designed ply sequence and orientation exhibit a higher burst pressure at [0°] ply and minimum at [90°] ply orientation. The vertical COPV design displays a maximum stress along the axial direction that leads to the consideration of maximum vessel thickness to be along axial direction for burst resistant design of COPV.

Transcriptomic analysis of the trade-off between endurance and burst-performance in the frog Xenopus allofraseri

Background Variation in locomotor capacity among animals often reflects adaptations to different environments. Despite evidence that physical performance is heritable, the molecular basis of locomotor performance and performance trade-offs remains poorly understood. In this study we identify the genes, signaling pathways, and regulatory processes possibly responsible for the trade-off between burst performance and endurance observed in Xenopus allofraseri, using a transcriptomic approach. Results We obtained a total of about 121 million paired-end reads from Illumina RNA sequencing and analyzed 218,541 transcripts obtained from a de novo assembly. We identified 109 transcripts with a significant differential expression between endurant and burst performant individuals (FDR ≤ 0.05 and logFC ≥2), and blast searches resulted in 103 protein-coding genes. We found major differences between endurant and burst-performant individuals in the expression of genes involved in the polymerization and ATPase activity of actin filaments, cellular trafficking, proteoglycans and extracellular proteins secreted, lipid metabolism, mitochondrial activity and regulators of signaling cascades. Remarkably, we revealed transcript isoforms of key genes with functions in metabolism, apoptosis, nuclear export and as a transcriptional corepressor, expressed in either burst-performant or endurant individuals. Lastly, we find two up-regulated transcripts in burst-performant individuals that correspond to the expression of myosin-binding protein C fast-type (mybpc2). This suggests the presence of mybpc2 homoeologs and may have been favored by selection to permit fast and powerful locomotion. Conclusion These results suggest that the differential expression of genes belonging to the pathways of calcium signaling, endoplasmic reticulum stress responses and striated muscle contraction, in addition to the use of alternative splicing and effectors of cellular activity underlie locomotor performance trade-offs. Ultimately, our transcriptomic analysis offers new perspectives for future analyses of the role of single nucleotide variants, homoeology and alternative splicing in the evolution of locomotor performance trade-offs.

Predation, metabolic priming and early life-history rearing environment affect the swimming capabilities of growth hormone transgenic rainbow trout

The period of first feeding, when young salmonid fishes emerge from natal stream beds, is one fraught with predation risk. Experiments conducted in semi-natural stream mesocosms have shown that growth hormone transgenic salmonids are at greater risk of predation than their non-transgenic siblings, due partly to the higher metabolic demands associated with transgenesis, which force risky foraging behaviours. This raises questions as to whether there are differences in the swim-performance of transgenic and non-transgenic fishes surviving predation experiments. We tested this hypothesis in wild-origin rainbow trout ( Oncorhynchus mykiss ) that were reared from first feeding in semi-natural stream mesocosms characterized by complex hydrodynamics, the presence of predators and oligotrophic conditions. Using an open-flume raceway, we swam fish and measured their capacity for burst-swimming against a sustained flow. We found a significant genotype effect on burst-performance, with transgenic fish sustaining performance longer than their wild-type siblings, both in predator and predator-free stream segments. Importantly, this effect occurred before differences in growth were discernable. We also found that mesocosm-reared fish had greater burst-performance than fish reared in the controlled hatchery environment, despite the latter being unexposed to predators and having abundant food. Our results suggest a potential interaction between predation and metabolic priming, which leads to greater burst capacity in transgenic trout.

Adaptive Interleaving Method and its Application to Free Space Optical Communications through Atmospheric Turbulence Channel

Adaptive interleaving method implemented by a hybrid system is proposed to deal with burst errors caused by long and deep channel fades in free space optical communications (FSOC) through atmospheric turbulence. Actually, considerable memory can be saved by changing the interleaving depth at transmitter and receiver according to the updated burst information from channel estimator. Combining with error correcting codes, anti-burst performance of the proposed method is evaluated by simulations based on channel state information from laser transmission experiments over an 11.8 km urban link. Simulation results show that 1~2 or even higher orders of magnitude of a memory can be saved when comparing with the maximum memory interleaving. The results have proved that the cost of anti-burst performance can be minimized to 10% or even smaller by the adaptive interleaving method when joint use with error correcting codes.