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Graph neural network has shown impressive ability to capture relations among support(labeled) and query(unlabeled) instances in a few-shot task. It is a feasible way that features are extracted using a pre-trained backbone network, and later adjusted in a few-shot scenario with an episodic meta-trained graph network. However, these adjusted features cannot well represent the few-shot data characteristics owing to the feature distribution mis-match caused by the different optimizations between the backbone and the graph network (multi-class pre-train v.s. episodic meta-train). Additionally, learning from the limited support instances fails to depict true data distributions thus cause incorrect class allocation. In this paper, we propose to transform the features extracted by a pre-trained self-supervised feature extractor into a Gaussian-like distribution to reduce the feature distribution mis-match, which significantly benefits the later meta-training of the graph network. To tackle the incorrect class allocation, we propose to leverage support and query instances to estimate class centers by computing an optimal class allocation matrix. Extensive experiments on few-shot benchmarks demonstrate that our graph-based few-shot learning pipeline outperforms baseline by 12%, and surpasses state-of-the-art results by a large margin under both full-supervised and semi-supervised settings.

Vanadium redox flow batteries (VRFBs) are perceived as promising candidates for grid-scale energy storage systems. However, limited improvements in electrode structures restrict the operation of VRFBs at high current densities. Herein, finite element simulations are used to guide the construction direction of the electrode structure. Afterwards, a quenching-cracking strategy is ingeniously employed to successfully construct parallel-aligned micron flow channels on electrode fibers in high agreement with the model, and the consistency of the flow channel structure is verified via deep learning technique. The well-constructed flow channels achieve high specific surface areas of electrodes while enabling the smooth flow of electrolyte over the fiber surfaces. Subsequent graphitization and sulfur-doping processes yield hierarchical fibers with highly conductive cores and well-active surfaces. Benefiting from fine structural modulation, the battery equipped with the as-prepared electrodes delivers an energy efficiency of 80.44 % at an ultra-high current density of 500 mA cm−2 and achieves a peak power density of 1.68 W cm−2. Additionally, the battery is consistently cycled for 1000 cycles at 500 mA cm−2 and the average energy efficiency decay is only 0.01032 % per cycle. Notably, finite element simulations are applied to investigate the velocity distribution of electrolyte in the flow channels, and first-principle calculations are employed to reveal the cause for energy efficiency decay of the battery after long-term cycling. Most importantly, the establishment of structure-activity relationships highlights the significance of comprehensive modulation of electrode fiber structures towards enhancing the performance of VRFBs.

Suppression and modulation of the host immune response to parasitic nematodes have been extensively studied. In the present study, we cloned and produced recombinant phosphotyrosyl phosphatase activator protein from Haemonchus contortus (rHCPTPA), a parasitic nematode of small ruminants, and studied the effect of this protein on modulating the immune response of goat peripheral blood mononuclear cells. Enzymatic assays revealed that rHCPTPA enhanced the p-nitrophenylphosphate phosphatase activity of bovine PP2A1. Immunohistochemical tests verified that the HCPTPA protein was localised mainly in the bowel wall and on the body surface of worms. It was also shown that serum produced by goats artificially infected with H. contortus successfully recognised rHCPTPA, which conjugated with goat peripheral blood mononuclear cells. The rHCPTPA was then co-incubated with goat peripheral blood mononuclear cells to assess its immunomodulatory effects on proliferation, apoptosis, cytokine secretion, migration and nitric oxide production. Our results showed that rHCPTPA suppressed the proliferation of goat peripheral blood mononuclear cells stimulated by concanavalin A and induced apoptosis in goat peripheral blood mononuclear cells. After rHCPTPA exposure, IFN-γ and IL-2 expression was markedly reduced, whereas secretion of IL-10 and IL-4 was significantly elevated, in goat peripheral blood mononuclear cells. Moreover, rHCPTPA down-regulated nitric oxide production and migration of goat peripheral blood mononuclear cells in a dose-dependent manner. These results illuminate the interaction between parasites and hosts at the molecular level, suggest a possible immunomodulatory target and contribute to the search for innovative proteins that might be candidate targets for drugs and vaccines.

We have proved the polarization dependence of the fiber Bragg grating (FBG), and demonstrated an all few-mode fiber laser that can realize multi-wavelength oscillation and switchable transverse modes simultaneously based on the polarization dependence of FBG. In this fiber laser, single-, dual- and triple-wavelength oscillation can be realized by merely adjusting the polarization controller inside the cavity. Three output transverse modes including fundamental mode, second-order mode, and hybrid modes can be switched as the laser operates at three different single-wavelengths correspondingly. In addition, azimuthally and radially polarized beams can be easily generated. This all few-mode fiber laser scheme may play a more significant role in wavelength division multiplexed (WDM) systems, mode division multiplexed (MDM) systems, sensing, and so on.

The development of polymer dielectric nanocomposite with high energy density and low charge-discharge loss retains primary project of polymer capacitor for portable electronics and embedding power system. In this work, we introduced hydroxyl groups on the barium titanate (BTO), which yielded hydrogen bonds with fluorine atoms in the P(VDF-TrFE) matrix. The released energy density for 10 wt% modified BTO/P(VDF-TrFE) nanocomposite film is 4.8 J/cm3 with a charge-discharge efficiency of 74% at 150 MV/m due to transition of electroactive phase and improved interfacial polarization. This strategy provides simple approach for high electrical storage and commendable way for the commercial film capacitor.

A series of (aMnOx–CoOy)r/γ-Al2O3 catalysts with different molar ratio of metal and supports (r denotes as the molar ratio of metal and supports, r = 0.02,0.03,0.04,0.05,0.06,0.08) and varied metal molar ratio(a stands for the molar ratio of Mn:Co, r = 1/3,1/1,3/1,6/1,1/0) were fabricated through impregnation route and characterized using X-ray diffraction (XRD), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR) and Scanning emission microscope (SEM). Among the catalysts investigated, (3MnOx–CoOy)0.04/γ-Al2O3 exhibited the highest activity and stable recyclability in the selective oxidation of tetralin using oxygen as the oxidant with a tetralin conversion of 68% and α-tetralone selectivity of 75% under the optimized conditions, affording a TOF value of 6.53 h−1, where the optimal reaction temperature is 120 °C and the reaction time is 8 h.

The rapid shift to high-grain (HG) diets in ruminants can affect the function of the rumen epithelium, but the dynamic changes in the composition of the epithelium-associated (epimural) bacterial community in sheep still needs further investigation. Twenty male lambs were randomly allocated to four groups (n = 5). Animals of the first group received hay diet and represented a control group (CON). Simultaneously, animals in the other three groups (HG groups) were rapidly shifted to an HG diet (60% concentrate)which continued for 7 (HG7), 14 (HG14) and 28 (HG28) days, correspondingly. Results showed that ruminal pH dramatically decreased due to the rapid shift to the HG diet (Plt;0.001), while, the concentrations of butyrate (Plt;0.001), lactate (P = 0.001), valerate (P = 0.008) and total volatile fatty acids (P = 0.001) increased. Diversity estimators showed a dramatic decrease after the shift without recovering as the HG feeding continued. The principal coordinates analysis showed that CON group clustered separately from all HG groups with the presence of significant difference only between HG7 and HG28 (P = 0.034). The non-parametric multivariate analysis (npmv R-package) deduced that the primary significant differences in phyla and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt)-predicted Kyoto Encyclopedia of Genes and Genomes (KEGGs) was attributed mainly to the diet composition (Plt;0.001, P = 0.001) compared to its application period (P = 0.140, 0.545) which showed a significant effect only on the genus (P = 0.001) and the operational taxonomic units (OTUs) level (P = 0.011). The Kruskal-Wallis test deduced that six phyla showed a significant effect due to the shift in diet composition. At the genus level, HG feeding altered the abundance of 12 taxa, four of which showed a significant variation due to the duration of the HG diet application. Similarly, we found that 21 OTUs showed significant variations due to the duration of the HG diet application. Furthermore, the genes abundance predicted by PICRUSt revealed that the HG feeding significantly affected seven metabolic pathways identified in the KEGG. Particularly, the abundance of gene families associated with carbohydrates metabolism were significantly higher in HG feeding groups (P = 0.027). Collectively, these results revealed that the rapid transition to an HG diet causes dramatic alterations in ruminal fermentation and the composition and function of ruminal epithelium-associated microbiome in sheep, while, the duration of the HG diet application causes drastic alterations to the abundance of some species.

Haemonchus contortus (H. contortus) ADP-ribosylation factor 1 (Hc-ARF1) and Hepatocellular carcinoma-associated antigen 59 (Hc-HCA59) are recognized to largely regulate the immune responses of host cells. However, studies about the protective efficacy of the two molecules are poorly unknown. In this research, combinations of recombinant Hc-HCA59 (rHc-HCA59) and Hc-ARF1 (rHc-ARF1) proteins were amalgamated with poly (lactic-co-glycolic acid) (PLGA) nanoparticles adjuvant in order to investigate their protection potential against H. contortus in goats. The results demonstrated that the levels of IgG, IgA, IgE, and IL-4 were noticeably enhanced in the rHc-HCA59 and rHc-ARF1 (rHc-HCA59+rHc-ARF1) group before H. contortus third-stage larvae (L3) challenge. After the L3 challenge, the levels of IL-17, IL-9, and TGF-β were considerably upregulated in the rHc-HCA59+rHc-ARF1 group. In the meantime, the abomasal worm burdens and the fecal eggs were reduced by 63.2% and 69.4% respectively in the rHc-HCA59+rHc-ARF1 group. According to the studies, PLGA nanoparticles immobilized with rHc-HCA59 and rHc-ARF1 proteins conferred partial protection and were expected to be a potential candidate for developing nano vaccines to combat goat haemonchosis.

With increasing distributed energy resoures (DERs) integration, the strategic behavior of a DER aggregator in electricity markets will significantly affect the secure operation of the distribution system. In this paper, the interactions among the DER aggregator, energy and reserve markets, and distribution system are investigated through a single-leader-multi-follower Stackelberg game model with the DER aggregator as the leader and the independent system operator and distribution system operator as the followers. To guarantee the operation security of the distribution system, security check problems under three different scenarios are involved in the follower level, which is linearized using a mixed-integer linearized power flow model. Then, using the strong duality theorem, the proposed model is converted into a bi-level mixed-integer linear (BMILP) programming model with only mixed-integer linear follower-level problems. Next, an accelerated relaxation-based bi-level reformulation and decomposition algorithm is proposed to solve the BMILP problem. Finally, case studies are carried out on a constructed integrated transmission and distribution (T&D) system and a practical integrated T&D system to verify the effectiveness of the proposed model and algorithm. The simulation results indicate that the available downward reserve of the DER aggregator will decrease with the security limitation of the distribution system., 20 pages, 14 figures. This work has been submitted to Renewable Energy for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible

Based on the Joule heat effect, graphene can transfer electrical into heat energy with fast response times and high efficiencies. Despite intensive researches, facile strategies for preparing polymer-based graphene electrothermal materials remain highly desirable. We herein report a strategy for preparing poly (tetra fluoroethylene) (PTFE)-supported high-performance hybrid electrothermal films from liquid-phase exfoliated graphene by combining with multi-walled carbon nanotubes (MWCNTs). The graphene and MWCNT dispersions can be obtained by sonicating graphite and MWCNTs, respectively, in chloroform with an ultraviolet (UV) light reactive dendritic polymer, HBPE@Py@Acryl, as stabilizer. Further, a series of PTFE-supported, UV cross-linked graphene/MWCNT hybrid films were successfully prepared from the dispersions by vacuum filtration and UV irradiation. It is found that the existence of MWCNTs in the films results in porous structure, making the hybrid films denser than the single graphene system. Meanwhile, the MWCNTs can effectively bridge graphene nanosheets to form perfect hybrid networks, jointly imparting the films with significantly enhanced electrothermal performance. In addition, the UV crosslinking of the HBPE@Py@Acryl adsorbed on the graphene and MWCNT surfaces makes the films exhibit excellent service stability. As an example, after being alternately folded 1800 times or scraped for 90 cycles, the film with 20% MWCNTs remains exhibiting stable, well controllable electrothermal performance. This research provides a guideline for producing high-performance polymer-based graphene electrothermal materials, potentially useful in wearable devices and intelligent actuators, from liquid-phase exfoliated graphene through simple process.

Hydrogen energy, as an ideal renewable resource and green energy replacement, has attracted growing attention. However, constructing highly active and stable catalysts for hydrogen evolution from Formic acid (FA) is still a challenging issue for development of renewable hydrogen energy. Herein, we develop a facile defect engineering strategy to construct N-deficient ordered mesoporous graphitic carbon nitride coupled with AgPd nanoparticles (denoted as AgPd/N-ompg-C3N4). Impressively, the as-prepared Ag0.1Pd0.9/N-ompg-C3N4 catalyst exhibits remarkable activity with the Turnover frequency (TOF) value of 1588.2 h−1 and robust stability with only a slight decrease in activity after ten cycles. Such markedly enhanced catalytic performance of Ag0.1Pd0.9/N-ompg-C3N4 is mainly attributed to the unique structure of N-ompg-C3N4 with higher surface area and abundant surface defects, the strong metal − support interaction between AgPd and N-ompg-C3N4, and charge transfer from Pd to Ag. This study provides a novel and efficient strategy for designing efficient catalysts to drive the hydrogen evolution from FA.

We propose and demonstrate a mode-locked fiber laser generating cylindrical vector beams based on an all-polarization-maintaining fiber structure. The radially polarized mode (TM01 mode) with a mode purity of 92.4% has been achieved by the principle of mode superposition. And the self-starting mode-locked pulse operate at 1067.01 nm with a spectral width of 0.069 nm at 3 dB based on a semiconductor-saturable absorber mirror. Stable pluse train with a repetition rate of 40.83 MHz, signal to noise ratio of 53 dB and pulse duration of 74.82 ps has been obtained. This laser has the advantages of compact structure and high stability, which may have the potential in practical application.

We demonstrate a switchable and tunable dual-wavelength passively mode-locked fiber laser in a compact linear cavity. Two cascaded polarization-maintaining fiber Bragg gratings (PM-FBGs) are used as wavelength-selective components, and a semiconductor saturable absorber mirror (SESAM) is used as a mode-locked component. Four kinds of switchable single-wavelength and two kinds of switchable dual-wavelength mode-locked operations are achieved in 1.0-μm band under lower pump power condition. Through temperature control, we obtain the tunable single-wavelength and dual-wavelength mode-locked operations, and the tunable wavelength range is about 0.5 nm when increase the temperature from 25 °C to 80 °C.

Vermicomposting eco-friendly converts lignocellulosic wastes into bio-organic fertilizer. Cellulose is the most abundant carbohydrate in lignocellulose. Glycoside hydrolase family 6 (GH6) plays a key role in the early step of cellulose degradation, which is essential for stabilizing lignocellulose. This study intends to quantify the abundance of GH6 gene and to clarify the succession of GH6 cellulase-producing microbial communities during vermicomposting. 100% of maize stover (A) and maize stover and cow dung at 60:40 ratio (B) were used. The results showed that different native genera were observed in the starting materials. Cellulomonas and Cellulosimicrobium were dominant genera harboring GH6 gene. The peak relative abundance of Cellulomonas was 76% and 30% in B and A during vermicomposting phase, and the corresponding values of Cellulosimicrobium was 36% and 37%. Earthworms increased the abundance of GH6 gene, which reached 1.51E + 09 from 3.46E + 08 copies/g in B. The results partially interpreted promoting effect of earthworms.

Young’s modulus and friction force of the gecko-inspired materials are important parameters for the applications of climbing robots and devices. Increasing the friction force of polymer composite pillar with desirable Young’s modulus is current research focus to expand the potential applications of bio-inspired materials. Also, the stability of inspired pillar under radiated exposure is essential to be investigated to explore the irradiation effect on patterned composite array. Here the boron nitride nanosheets (BNNSs) have been exfoliated with assistance of hyperbranched polyethylene (HBPE) as polymer stabilizer via CH-π non-covalent interaction. The nanosheets were incorporated into polydimethylsiloxane (PDMS) mixture that was then utilized to prepare composite pillar via plasma etched silicon template. The electron irradiation was conducted to examine the morphology of patterned array and the mechanical property of PDMS composite. The coefficient of friction for PMDS composite decreases slightly after irradiation, and it retains high value around 1.2 for 0.2 wt% composite pillar with comparison to 1.3 for PDMS. The stress for irradiated PDMS decreases from 3.1 MPa to 1.8 MPa with the strain of 281% at accumulating dose of 5 × 1015 rad. During irradiation, the doubling terminating reaction is probably induced by the active radical sites in elastomer. The PDMS pillar exhibits large friction coefficient and high mechanical property due to new crosslinking network of elastomer during irradiation. This work develops polymer composite with pillar architecture by silicon template method, and sheds a light on the electron irradiation effect of composite pillar to pave the path for the application of gecko-inspired material in spacecraft.

Background In vitro systems allowing maintenance and experimentation on primary astrocyte cultures have been used for decades. Astrocyte cultures are most maintained in serum-containing medium which has been found to alter the morphology and gene profiles of astrocytes. New method Here, we reported a new serum-free medium for astrocyte culture, which consisted of DMEM and NB media supplemented with insulin and heparin-binding epidermal growth factor-like growth factor (HB-EGF) (SF-I-H medium). Meanwhile FBS-containing (FBS) medium composed of DMEM medium containing 10% FBS were used for comparison study. Cerebral cortex was harvested from postnatal day 1 Wistar rats and brain cells were isolated and seeded to poly- L -lysine coated culture dishes after 15 min differential velocity adherence. Results Compared with FBS medium, astrocytes in SF-I-H medium were smaller and exhibited process bearing morphologies. MTT assays showed that cell density and proliferation rate were higher in SF-I-H medium than in FBS medium all the time, and flow cytometry analysis revealed that SF-I-H medium promoted cell mitosis in a manner comparable to FBS medium. Consistently, western blot analysis further revealed that insulin and HB-EGF synergistically activated the PI3K/AKT and MAPK/ERK1/2 signaling cascades as FBS. Comparison with existing method(s) Astrocytes cultured in SF-I-H medium grew faster than FBS medium. Conclusion Taken together, our results indicated that SF-I-H medium, in which cell morphology was similar with astrocytes in brain, was more effective for astrocyte survival and proliferation than FBS medium, providing a new cell model to study astrocyte functions without the interference of serum.

The use of stabilizers in liquid-phase exfoliation of graphite can effectively promote graphite exfoliation in common solvents, and concurrently render functionalized graphene by adsorbing them on the exfoliated graphene surface. Thus, the exploration of novel stabilizers is especially important for graphene liquid-phase production and related applications. Herein, we report the successful application of a pyrene-functionalized hyperbranched polyethylene (HBPE@Py) as the stabilizer for graphite exfoliation in chloroform. The polymer has a global hyperbranched polyethylene backbone and multiple covalently bonded pyrene moieties as branch ends. It can be synthesized via ethylene copolymerization using a Pd-diimine catalyst under mild conditions, 0.1 MPa/25 °C. Due to the cooperative effect of the CH-π and π-π interactions between the HBPE@Py and graphene surface, some of the polymer is irreversibly adsorbed on the latter, thus effectively preventing their re-stacking and concurrently rendering pyrene-functionalized graphene. This allows us to obtain stable dispersions of few-layer graphene with relatively high concentrations (0.10–0.50 mg mL−1) and exfoliation efficiencies (1.6–13.0%). The resultant graphene is confirmed to be high-quality and shown to be highly stable when dispersed in chloroform, even the free polymer has been thoroughly removed. From the dispersion, a flexible, conductive graphene film and polymer-based graphene nanocomposites have been successfully prepared.

The Concentrated Photovoltaic (CPV) technology based on the use of high-efficiency multi-junction solar cells has higher power generation efficiency than other photovoltaic power generating technology. However, the cost and reliability of CPV technology are the primary reasons that restrict its progress. A truncated ball lens as a secondary optical element for CPV optical system is proposed in this paper to reduce the cost and improve the reliability. Theoretical analysis and experimental investigations were conducted on a concentrator with geometrical concentration ratio of 625×, a flat Fresnel lens as primary optical element and a truncated ball lens as secondary optical element. Test results show that the concentrator with power generation efficiency of 30.1% and acceptance angle of 0.73° can be obtained. Additionally, temperature effects of SOG lens on power generation are also studied.

E. mitis is ubiquitous in clinical coccidiosis caused by mixed infection of Eimeria species and the infection by E. mitis usually significantly impairs productivity of the infected chickens. To date, however, few protective antigens from E. mitis have been reported. In this study, the molecular characterization and protective efficacy of microneme 3 of Eimeria mitis (EmiMIC3) were analyzed. EmiMIC3 gene was cloned from sporozoites of E. mitis and its MARs (microneme adhesive repeats domain) were predicted. Recombinant EmiMIC3 (rEmiMIC3) was expressed in E. coli and purified and then was analyzed by western blot with anti-E. mitis chicken serum. Meanwhile, native EmiMIC3 from sporozoites was analyzed by anti-rEmiMIC3 rat serum. The expressions of EmiMIC3 in E. mitis sporozoites and merozoites were analyzed by immunofluorescence assay. The rEmiMIC3-induced changes of T lymphocytes subpopulation, serum cytokines and IgY levels and the protective efficacy of rEmiMIC3 were determined in animal experiments. The results showed that the deduced open reading frame (ORF) of EmiMIC3 was composed of 1145 amino acids, possessing 9 MARs. EmiMIC3 gene was submitted to GenBank (accession number: MG888670). EmiMIC3 could express in sporozoites and merozoites respectively and located at the apex of E. mitis sporozoite. Western blot assay revealed that the rEmiMIC3 could be recognized by serum of chicken infected by E. mitis and the native EmiMIC3 from sporozoites could also be recognized by rat serum against rEmiMIC3. Following vaccination with rEmiMIC3, higher levels of IL-10, IFN-γ, TGF-βand IL-17, higher proportions of CD4+/CD3+ and CD8+/CD3 + T lymphocytes and higher level of IgY antibody were induced compared to the controls. Vaccination with rEmiMIC3 prominently increased the weight gains and decreased oocyst output of the vaccinated chickens after challenge infection. Our result not only enriches protective candidate antigen of E. mitis, but also provides available protective antigen of E. mitis for the development of multivalent vaccines against infection caused by mixture of Eimeria species in clinical coccidiosis.

Micro-electromechanical system (MEMS) suspended inductors have been widely studied in recent decades because of their excellent radio frequency performance. However, few studies have been performed on the failure analysis of MEMS suspended inductors under mechanical shock. In this study, the failure of MEMS suspended inductors with a planar spiral coil is investigated through analytical and experimental methods. We present a stress and deformation analysis to study the failure mode of the suspended inductors under shock. To verify the theoretical analysis, MEMS inductors are designed and fabricated, and shock tests are carried out. The shock tests show that the failure mode of the MEMS suspended inductors is a fracture that occurs at the ends of the inductor coil, and the test results agree with the theoretical analysis.

Toxoplasma gondii and Trichinella spiralis are widely distributed in humans and animals throughout the world, but the data on prevalence of horses in China are limited. In this study, 409 equine serum samples from Xinjiang Uygur Autonomous Region (XUAR), northwestern China, were tested by enzyme linked immunosorbent assay (ELISA) to investigate the antibodies against T. gondii and T. spiralis in horses of this region. Results showed that 22 samples (5.38%) were positive for T. gondii and 14 (3.42%) for T. spiralis. Two samples (0.49%) were both positive with T. gondii and T. spiralis. It was found that the prevalence of T. gondii in older horses (>15 years) was significantly higher than that in younger animals. There was no significant difference between the prevalence and the genders of the animals. To verify the results of seroprevalence for T. gondii, 10 samples of uterine secretions from aborting mares with positive T. gondii antibody, were tested by PCR assay. The internal transcribed spacer – 1 (ITS-1) gene specific for T. gondii was amplified with a ratio of 100% (10/10), which was consistent with the result of seroprevalence. The results of the present survey indicate that infection with T. gondii and T. spiralis in horses should not be ignored in Xinjiang, northwestern China. Consumption of horse meat in this region may represent a potential source for human infection with T. gondii and T. spiralis.

Buckling failure analysis of buried subsea pipeline under reverse fault displacement was investigated by the Vector Form Intrinsic Finite Element method in this paper, considering nonlinear soil–pipeline interaction in slit with sand and the multifold nonlinearities of nonlinear material, large deformation, large displacement and self-collision/contact. Two typical conditions discussed were the operation condition and the empty waiting state during installation, maintenance, and operation. Effects of soil properties, pressure loadings, diameter–thickness ratios and dip angles on local buckling formation, tensile strain and cross-sectional distortion were investigated. The results show that subsea pipelines obtain a large deformation capacity and the flexure curve shape is usually S-shape. The external pressure is more unfavorable than the internal pressure since it aggravates the compression strains but alleviates the tension strains. A small fault dip angle results in serious axial compression and can lead to local collapse in the empty waiting states. For big diameter–thickness ratios or great pressure level, external pressure will cause local collapse and even buckle propagation along the pipeline. Seven different modes of collapse and propagation are discovered in the empty waiting state. They can be classified by the first collapse location, buckle propagation direction and further propagation sustainability. The cross-sectional shapes after collapse and during propagation are mainly determined by the compression or tension state around the circum. These results can be used for the development of performance-based design methodologies for buried subsea pipelines.

Improving system reliability and voltage profiles in distribution networks requires the simultaneous installation of distributed generations and automation devices. This paper builds a bi-level programming model for the coordinated configuration of distributed generations and automation devices. The upper-level problem is to minimize the total investment cost of distributed generations and automation devices and the penalty cost of power shortages, and the lower-level problem is to minimize the voltage deviation during typical operation mode. To explicitly represent the relationship between the penalty cost of power shortages and installation locations of distributed generations and automation devices, an analytical expression of the failure rates of load nodes with respect to installation locations of distributed generations and automation devices is derived. The bi-level model can be transformed to a mixed-integer nonlinear programming problem by applying the Karush–Kuhn–Tucker theorem because the lower-level problem is a quadratically constrained linear programming problem. Case studies on an IEEE 33-bus distribution system and a practical 110-bus distribution system in China are used to verify the effectiveness of the proposed method.

The dynamics of a steel catenary riser (SCR) are highly nonlinear and strongly affected by the interaction between riser and seabed. Possessing the advantages of robustness and high efficiency, the vector form intrinsic finite element (VFIFE) method is applied to solve this problem. The nonlinear hysteretic riser-seabed interaction is integrated into the model. Simulation results are compared to the commercial software Ocraflex, and high similarities prove the capability of VFIFE to simulate the dynamics of SCR on the nonlinear seabed. In dynamic analysis, a larger mass damping coefficient should be applied in the touchdown zone (TDZ) and flowline part to increase the stabilization. In contrast, the coefficient in the catenary part has only minor influences on the behavior of SCR. To improve the computation efficiency, the effect of using coarse meshes with different densities in the catenary part has been investigated, while the fine meshes are applied in the TDZ and flowline part. In the dynamic analysis of TDZ, the distribution of seabed reaction force and stress range are present and discussed. Furthermore, the effects of different loading parameters and hanging-off positions on the trench profiles and fatigue damage of SCR have been studied in detail.

Bimetallic AgPd nanoparticles with various molar ratios immobilized on graphitic carbon nitride (g-C 3 N 4 ) were successfully synthesized via a facile co-reduction approach. The powder XRD, XPS, TEM, EDX, ICP-AES and BET were employed to characterize the structure, size, composition and loading metal electronic states of the AgPd/g-C 3 N 4 catalysts. The catalytic property of as-prepared catalysts for the dehydrogenation of formic acid (FA) with sodium formate (SF) as the additive was investigated. The performance of these catalysts, as indicated by the turnover frequency (TOF), depended on the composition of the prepared catalysts. Among all the AgPd/g-C 3 N 4 catalysts tested, Ag 9 Pd 91 /g-C 3 N 4 was found to be an exceedingly high activity for decomposing FA into H 2 with TOF up to 480 h −1 at 323 K. The prepared catalyst is thus a potential candidate for triggering the widespread use of FA for H 2 storage.

We demonstrate an all-fiber spatiotemporal mode-locked laser based on graded-index multimode fiber. Due to the high damage threshold of graded-index multimode fiber devices, the output single-pulse energy reach up to 11.67 nJ. The beam quality at mode-locked state is significantly improved compared with continuous wave state as a result of the self-cleaning effect. By amplifying the pulse in the multimode fiber amplifier, high power pulses with high beam quality can be obtained in the all-fiber system based on graded-index MMFs., 8 pages, 5 figures

Reinforced thermoplastic pipes (RTP) are widely used in the offshore oil and gas production industry for their excellent flexibility, corrosion resistance and internal pressure resistance. RTPs inevitably experience extreme environmental loads including internal pressure and tensile load in the procedures of installation and operation, which influence the structural integrity and safety. Therefore, reinforced layers of RTP are designed to bear internal pressure and tensile load. Herein, the mechanical behavior of fiber-reinforced thermoplastic pipe that consisting of aramid fiber braid reinforced layers is investigated by combination of numerical simulation and experimental methods. The full-scale internal pressure bursting experiments of 1-inch aramid fiber RTPs were carried out to study the burst pressure and failure behavior. A finite element model of aramid fiber RTP is established using ABAQUS, which considers the material nonlinearities as well as frictional interactions between layers. Based on the finite element model which validated by the experimental results, the mechanical behavior of fiber reinforced thermoplastic pipe subjected to internal pressure and tensile load is investigated in detail. The current study compares the influence of braided angle of fiber-reinforced layers, friction coefficient between each layer and load conditions on the mechanical behavior of RTPs. The experiment results reveal that the bursting pressure of 1-inch aramid fiber RTPs is about 76.1 MPa. The failure of aramid fiber RTP under internal pressure is dictated by leakage due to the fracture of fiber-reinforced layers and the fracture of the internal layer at the end fitting. It is worth noting that the braiding angle renders an obvious influence on mechanical properties of fiber-reinforced RTPs, whereas the mechanical behavior remains insensitive to friction coefficient between layers. Moreover, the synergistic influence of internal pressure and tensile load significantly affects the mechanical behavior of fiber-reinforced RTPs. The current study shall serve as a reference for the design and application of fiber-reinforced thermoplastic pipes in marine oil and gas production.

Dielectric polymer capacitors with high power density as well as efficient charge-discharge rate are widely investigated in past decades. The development of polymer film with large electric capability has become the research topic for the energy storage of advanced power equipment. Here the tubular architecture in poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) composite film has been constructed with modified halloysite nanotubes (HNTs) to accomplish an effective diffusion of matter and energy units under high electric field. The nanotube surface was functionalized with poly(dopamine) (PDA) in tris-buffer solution to improve the compatibility with fluoropolymer. The energy capability of P(VDF-TrFE) composite film is enhanced owing to the large content of electroactive phase and interfacial polarization. The dielectric constant in 4 wt% PDA-HNTs/P(VDF-TrFE) film is 34.1 at 100 Hz, and the energy density in 2 wt% composite achieves 5.6 J/cm3 with charge-discharge efficiency of 74% at 250 MV/m based on the efficient transportation of ions within hollow nanotubular structure. This work delivers a simple method to construct the efficient diffusion route in polymer dielectrics for film capacitor with high energy density and cycle efficiency.

All-fiber wavelength-tunable fiber laser is a desirable light source architecture in many fields owing to their low cost, compactness and easy integration. However, most of them have independent filter elements and saturated absorption elements, which will undoubtedly increase the redundancy of laser. In this paper, we realize an all-fiber wavelength-tunable noise-like pulse (NLP) laser with the tunable central wavelength from 1547 nm to 1600 nm based on fiber loop mirror (FLM). The fiber loop (FLM) fused with two segments of polarization-maintaining fibers (PMF) acts as both a comb filter and a saturable absorber (SA). Such an all-fiber tunable NLP mode-locked laser wavelength at C-band (1530–1565 nm) and L-band (1565–1625 nm) is a potential choice for many practical applications.