The performance degradation of rubber gaskets under vibration compression is faster than that under static load, and the degree of performance degradation will continue to increase under humidity and ...thermal environment. For rubber gaskets under a long-term service, the mechanical properties of rubber gaskets were measured after accelerated aging process with different temperature in the temperature box. The precipitates of rubber structures were detected by energy-dispersive spectroscopy and scanning electron microscopy. Molecular chain of silicon rubber gasket quickly breaks to form free radicals under high-frequency stress, which initiate oxidation chain reaction and mechanochemical process. Surface leakage of silicon (Si) and magnesium (Mg) indicates that a larger percent of macromolecular chains are broken and decomposed. High temperature activates the molecular chain cracking or cross-linking, while high-frequency stress leads to transport leakage on chain decomposition. The oxygen diffusion rate and activation oxidation reaction were accelerated by the residual stress to rubber oxidation reaction rate.
Full text
Available for:
NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
A method of calculating the outline of metallographic diagram and statistical outline shape features such as area and slenderness ratio is introduced to reflect the influence of different process ...parameters on the microstructure of metals. After binarizing the image, the model of similarity matrix is established to describe the overall similarity of the lattice growth and detect possible anomalies for the microstructures with uniform lattice growth and good connectivity. By comparing the statistical values of the outline characteristics of the crystal structure and the characteristic area of the surrounding structure, these techniques can quantitatively analyze the effect of process parameters on the crystal structure.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Barrier coverage is a critical issue in wireless sensor networks (WSNs) for security applications, which however cannot be guaranteed to be formed after initial random deployment of sensors. Existing ...work on barrier coverage mainly focus on homogeneous WSNs, while little effort has been made on exploiting barrier coverage formation in heterogeneous WSNs where different types of sensors are deployed with different sensing models and costs. In this paper, we study how to efficiently form barrier coverage by leveraging multiple types of mobile sensors to fill in gaps between pre-deployed stationary sensors in heterogeneous WSNs. The stationary sensors are grouped into clusters and a cluster-based directional barrier graph is proposed to model the barrier coverage formation problem. We prove that the minimum cost of mobile sensors required to form a barrier with stationary sensors is the length of the shortest path on the graph. Moreover, we propose a greedy movement algorithm for heterogeneous WSNs to efficiently schedule different types of mobile sensors to different gaps while minimizing the total moving cost. In particular, we formulate the movement problem for homogeneous WSNs as a minimum cost bipartite assignment problem, and solve it in polynomial time using the Hungarian algorithm. Extensively experimental results on homogeneous and heterogeneous WSNs demonstrate the effectiveness of the proposed algorithms.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Barrier coverage is a critical issue in wireless sensor networks deployed in security applications (e.g., border protection), whose performance strongly depends on the locations of sensor nodes. ...Existing works on barrier coverage typically assume that sensor nodes have accurate location information, which is not reasonable or practical for many real sensor networks. In this paper, we study the barrier coverage problem when sensor nodes have location errors and deploy mobile sensor nodes to improve barrier coverage if the network is not barrier-covered after initial deployment. We analyze the effects of location errors for barrier coverage and propose a fault-tolerant weighted barrier graph to model the barrier coverage formation problem. Based on the graph, we prove that the minimum number of mobile sensor nodes needed to achieve barrier coverage with a guarantee is the length of the shortest path on the graph. Furthermore, we improve the computational efficiency of the fault-tolerant barrier coverage formation algorithm by removing unnecessary edges on the graph. Experimental results validate the correctness of our analysis and the proposed algorithms.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Submersible underwater towed systems usually need to transition from steady-state motion to maneuvering motion during operation while dynamically adjusting the length of the towed cable. The lumped ...mass approach was employed to convert the dragged cable into a model with a concentrated mass. Analyzed utilizing a computational simulation tool, the motion response of the towed system was examined for both simple and composite maneuvering motions. By comparing the changes in tension at the end of the towed cable and the depth of the towed body motion under different motion states and cable retraction and deployment speeds, the motion response law of the system when the length of the towed cable changes during the submarine maneuver motion is obtained. The maximum tension value occurred at 1.0 m/s during the acceleration maneuver when the velocity change of the submersible ended at the same time as the cable length change. After the deployment maneuver in a circular rotating motion, the range of tension fluctuations decreased by 93%, greatly improving the stability of the towed system. An analysis was conducted to examine the impact of various motion and structural parameters on the motion response. The study revealed that the buoyancy-to-gravity ratio of the towed body, the acceleration time of the accelerated motion, and the rotational speed of the circular rotational motion had a notable influence on the outcomes. When the buoyancy-to-gravity ratio of the towed body is 1.0, the maximum tension value of the towed cable is minimized, and the depth change of the towed body is closer to 0 m.
Although gait recognition has been greatly improved by efforts from many researchers in recent years, its performance is still unsatisfactory due to the lack of gait information under the real ...scenariowhere only one or two images may be used for recognition. In this paper, a new gait recognition framework is brought about which can combine the long-short-term attention modules on silhouette images over the whole sequence and the real human physiological information calculated by a monocular image. The contributions of this work include the following: (1) Fusing the global long-term attention (GLTA) and local short-term attention (LSTA) over the whole query sequence to improve the gait recognition accuracy, where both the short-term gait feature (from two or three frames) and long-term feature (from the whole sequence) are extracted; (2) presenting a method to calculate the real personal static and dynamic physiological features through a single monocular image; (3) by efficiently applying the human physiological information, a new physiological feature extraction (PFE) network is proposed to concatenate the physiological information with silhouette for gait recognition. Through the experiments between the CASIA-B and Multi-state Gait datasets, the effectiveness and efficiency of the proposed method are proven. Under three different walking conditions of the CASIA-B dataset, the mean accuracy of rank-1 in our method is up to 89.6%, and in the Multi-state Gait dataset, wearing different clothes, the mean accuracy of rank-1 in our method is 2.4% higher than the other works.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The hydrodynamic wake generated by the underwater vehicle’s motion has a considerable impact on the movement of the towed system underwater. This paper utilizes the lumped mass method to model the ...towed cable in order to improve the accuracy of predicting its position and attitude in the wake, and to determine the suitable cable-towed position. Velocity is transferred from the flow field to the cable dynamic model in an innovative way to imitate the motion of the cable. Several iterations are conducted to enhance the dynamic reactivity of the cable system. Numerical simulations are used to model both the straight towed and turning movements. The numerical calculation provides the characteristics of vorticity in the flow field formed by the energy exchange between the vorticity and the cable, as well as the gradually dissipating vorticity and momentum exchange characteristics at the trailing edge of the enclosure. The results indicate that the best location for the cable towed is where its motion does not cause any adhesion. On the other hand, the disadvantageous scenario for cable-towed systems occurs when the cable’s movement causes substantial adhesion. This paper innovatively establishes a model of mechanical energy exchange, describes the characteristics of energy exchange between the cable and fluid dynamics, and divides the four regions of cable motion. In the manipulation state, the dynamic energy exchange between the cable and the wake results in the transient vibration response of the cable. The fluid structure coupling method can accurately determine the separation region of the towed point of the vehicle based on its compatibility (non-adhesive) and incompatibility (adhesive). The boundary of the region is defined to distinguish a free tow point from a wall-attached tow point. A transition zone has the possibility to change the pattern from a free tow to a wall-attached tow. The wake can be divided into free tow region, transition zone, and adjacent wall tow region by this fluid structure interaction assessment method.
Machine learning (ML) is a versatile technique to rapidly and efficiently generate insights from multidimensional data. It offers a much‐needed avenue to accelerate the exploration and investigation ...of new materials to address time‐sensitive global challenges such as climate change. The availability of large datasets in recent years has enabled the development of ML algorithms for various applications including experimental/device optimization and material discovery. This perspective provides a summary of the recent applications of ML in material discovery in a range of fields, from optoelectronics to batteries and electrocatalysis, as well as an overview of the methods behind these advances. The paper also attempts to summarize some key challenges and trends in current research methodologies.
This perspective provides a summary of the recent applications of machine learning in material discovery in a range of fields, from optoelectronics to batteries and electrocatalysis, as well as an overview of the methods behind these advances. The paper also summarizes some key challenges and trends in current research methodologies.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In our study, the effects of water stress on photosynthesis and photosynthetic electron transport chain (PETC) were studied through several ways including monitoring the change of gas exchange ...parameters, modulated chlorophyll fluorescence, rapid fluorescence induction kinetics, reactive oxygen species, antioxidant enzymes activities and D1 protein in apple leaves. Our results showed when the leaf water potential (
) was above -1.5MPa, the stomatal limitation should be the main reason for the drop of photosynthesis. In this period,
,
,
, and
all showed a strong positive correlation with leaf water potential. So do modulated chlorophyll fluorescence parameters related to photosynthetic biochemistry activity including F
/F
, Φ
, q
, and q
as water leaf potential gradually decreased. On the contrary, in this period, NPQ and
kept going up, which expresses an attempt to dissipate excess energy to avoid its damage to plants. When
is below -1.5MPa,
continued to decrease linearly while
increased and a 'V' model presented the correlation between
and
by polynomial regression. It implied in this period the drop in photosynthesis activity might be caused by non-stomatal limitation other than stomatal limitation. F
/F
, Φ
, qP, and qL in apple leaves treated with water stress were much lower than that in control while NPQ and
started to go down. It demonstrated the excess energy might exceed the tolerant ability of apple leaves. Consistent with changes of these parameters, excess energy led to an increase in the production of reactive oxygen species (ROS) including H
O
and O
Although the activities of antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) increased dramatically and ascorbate peroxidase (APX) decreased in apple leaves with drought stress, it was not still sufficient to scavenge ROS. Consequently, the accumulation of ROS triggered a reduction of D1 protein net content, a core protein in PSII reaction center. As D1 was responsible for the photosynthetic electron transport from Q
to Q
, the capacity of PETC between Q
to Q
was considerably down-regulated. The decline of photosynthesis and activity of PETC might result in the shortage of ATP and limitation the regeneration of RuBP (
), a key enzyme in CO
assimilation. They were all non-stomatal factors and together contributed to the decreased CO
assimilation under severe water stress.
Autophagy is a highly conserved cellular process regulating turnover of cytoplasmic proteins via a lysosome-dependent pathway. Here we show that kidneys from mice deficient in autophagic protein ...Beclin 1 exhibited profibrotic phenotype, with increased collagen deposition. Reduced Beclin 1 expression, through genetic disruption of beclin 1 or knockdown by specific siRNA in primary mouse mesangial cells (MMC), resulted in increased protein levels of type I collagen (Col-I). Inhibition of autolysosomal protein degradation by bafilomycin A1 also increased Col-I protein levels and colocalization of Col-I with LC3, an autophagy marker, or LAMP-1, a lysosome marker, whereas treatment with TFP, an inducer of autophagy, resulted in decreased Col-I protein levels induced by TGF-β1, without alterations in Col-I α1 mRNA. Heterozygous deletion of beclin 1 increased accumulation of aggregated Col-I under nonstimulated conditions, and stimulation with TGF-β1 further increased aggregated Col-I. These data indicate that Col-I and aggregated, insoluble procollagen I undergo intracellular degradation via autophagy. A cytoprotective role of autophagy is implicated in kidney injury, and we demonstrate that low-dose carbon monoxide, shown to exert cytoprotection against renal fibrosis, induces autophagy to suppress accumulation of Col-I induced by TGF-β1. We also show that TGF-β1 induces autophagy in MMC via TAK1-MKK3-p38 signaling pathway. The dual functions of TGF-β1, as both an inducer of Col-I synthesis and an inducer of autophagy and Col-I degradation, underscore the multifunctional nature of TGF-β1. Our findings suggest a novel role of autophagy as a cytoprotective mechanism to negatively regulate and prevent excess collagen accumulation in the kidney.
Background: Autophagy is a process that cells use to degrade and recycle cellular proteins, however, the role of autophagy in kidney fibrosis remains largely unknown.
Results: Autophagy is responsible for the intracellular degradation of type I collagen.
Conclusion: Autophagy negatively regulates and prevents excess collagen accumulation in the kidney.
Significance: Our findings implicate a novel role of autophagy as a cytoprotective mechanism against renal fibrosis.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
