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The rapid development of the Internet of Things has resulted in the harvesting of distributed sustainable energy receiving increasing attention. Recently, a study on triboelectric nanogenerators (TENGs) for collecting low-frequency and irregular-amplitude ocean wave energy has attracted significant interest. Herein, a self-powered seesaw-structured spherical triboelectric–electromagnetic hybrid nanogenerator (SSTE-HNG) combining various working modes is presented for harvesting wide-frequency wave energy from different directions and self-powered sea surface wireless positioning. The electrical output performances were systematically investigated and optimized via studying the effects of the configuration parameters, including the central slider mass, oscillation frequency, and swing amplitude of each module and the entire device; the instantaneous maximum output power densities of the origami zigzag-multilayer structured (OZ), freestanding layer rolling (FL), and electromagnetic generator (EMG) modules can reach 17, 4.8, and 9.8 W m−3, respectively, at an oscillation frequency of 0.7 Hz, and around 410 LEDs can be lit when operating the SSTE-HNG. Finally, the output voltage of the SSTE-HNG was stabilized using a transistor-controlled power management circuit for charging a 4.7 mF commercial capacitor in the range of 2.7 to 3.3 V; the seesaw-structured spherical buoy was used to drive a global positioning system (GPS) module for dynamic sea surface real-time wireless positioning, and our lab building on campus was successfully located upon installing the SSTE-HNG in a water tank. This study provides an ingenious design for achieving synchronized movements among hybrid effect/mode-based generators, and a self-powered buoy with a hybrid nanogenerator for sea surface wireless positioning was realized, which has the potential to be integrated with distributed electronics, such as sensors that collect sea surface meteorological information, in the future in the field of smart marine technology.

From Jan. 2013 to Nov. 2018, we carried out the investigation on vegetation studies in the ecological monitoring programs, Shenzhen and totally researched 170 plant communities of mountain areas etc., few areas of street regions and parks etc., for communities’ structural characteristics and plant diversity. We comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level and the main affected factors. We also researched and analyzed these communities’ structural characteristics and pant diversity, comparatively analyzed natural forests, semi-natural forest and artificial forest composition and structural characters and family, genus and species diversity level, the main affected factors; researched and analyzed the relationship between plant community structure characteristics with the absorbing ability to PM2.5 pollutants. The result showed that the structure and plant diversity of natural forest were obviously better than artificial disturbed forest or artificial forest, the semi-natural forest was the middle level of the forests, In the indices of height, DBH, coverage and crow width etc. of tree layer, natural forests and semi-natural forests were obvious higher than that of artificial disturbed forest or artificial forest; in some forests of artificial disturbed forest or artificial forest, though their richness indices of family and genus were a slightly higher, but this contribution was majorly due to herb layer plants, and some shrub layer plants. Analyzing three kinds of communities, the number of tree layer species of natural forest was the largest, and their every α-diversity index value was the highest; these characteristics values of semi-natural forest were second, artificial disturbed forests or artificial forests were the lowest; in shrub layer, and herb layer, few α-diversity indices of artificial disturbed forest or artificial forest were a slightly higher than that of some natural forests, but the integral values of the diversity indices of natural forest and semi-natural forest were obviously higher than the former. The research showed that in the artificial disturbed forest or artificial forest, because there have some little scale clearing areas, so some pioneer plant species could enter the community and formed a temporarily increase of species diversity, however, these species major were some shrub and herb plants; but tree layer possessed obviously more, even surpassed several ten times biomass than shrub and herb layers. Therefore, the respects of maintain ecosystem stability and other ecological efficient have major and dominated position and so on; and then this community can be natural recovery and succession, those forementioned new entire plants shall withdraw from the community and are replaced by the original plants of the community; but this process has already caused the ecological efficient loss and ecosystem unstable. Above research results are better evidence and theory reference to the argument problems on that are natural forest and natural restoration forest biodiversity higher? or is artificial forest biodiversity higher? and or is more artificial disturbed forest higher? Our researches showed that used random investigation method set quadrats, and combined typical investigation method, the structural indices in the all layer of community and all diversity indices of tree, shrub and herb layers and the integral values were similar, same or usually these indices in the community which set 600 m2, 800 m2 total quatrat area were higher (α-diversity) than that of more than 3000 m2, 4000 m2 or 7000 m2, even more than 17,000 m2 total quadrat area of communities. These lots of researches further proved that according to minimum area method for vegetation survey, in subtropical region, using random investigation method combined with typical investigation set 400 m2 or 400 m2 - 500 m2 total quad

Shale gas, a kind of natural gas from unconventional reservoirs, can be economically produced due to the application of hydraulic fracturing. This stimulation provides a technically feasible solution to improve the fracture conductivity in most shale formations. The degree of crack extension is a fundamental controlling factor in the efficient exploitation of shale gas. The shale can be treated as porous media. This paper presents a coupled thermo-hydro-mechanical (THM) model to simulate the intact rock and the cracked rock with a single joint respectively. The existence of the joint has a significant effect on the performance of hydraulic fracturing. The governing equations are derived on the basis of the momentum, mass and energy conservation after the mechanism of the three-field coupling is analyzed. The investigation is carried out for the variations of maximum principal stress, seepage pressure and temperature under the designed operational conditions. The numerical results between the intact and cracked rock are compared.

With the advanced technologies such as 5 G network and internet of things (IoT), there are incredibly increasing sensors and corresponding applications emerging to benefit our daily lives. However, the power supplies for countless sensors become a serious issue to suppress further expansion of IoT. In this work, a self-powered triboelectric sensor (CN-STS) made of electrospun composite nanofibers is developed towards smart traffic monitoring and management. To meet the requirements of fast-response and high sensitivity for the smart traffic management, transferred charge density is adopted as sensing signals compared to voltage / current outputs for it can perfectly record the subtle differences and suitable for dynamic traffic monitoring. Carbon nanotube is further doped into PVDF nanofibers to improve the electrical output performance and pressure sensitivity. A relatively high sensitivity of 0.0406 μ Cm-2kPa-1 at low pressure range (0 to 75 kPa) and a sensitivity of 0.0032 μ Cm-2kPa-1 at higher pressure range (75 to 425 kPa) can be achieved by the CN-STS, indicating that the CN-STS is more sensitive at low pressure range. Moreover, by connecting to cloud IoT services, the functions of traffic flow management, overlapping and speeding vehicle capturing, and plate number recognition are realized by the CN-STS arrays with a compensation circuit. A charge amplifier is utilized in power management to process the charge input signals for better distinguishing the signals from none-vehicles and stabilize the volage output for further reading by the A/D convertor build in Raspberry Pi. The engineered self-powered triboelectric sensors not only open a new potential area for triboelectric nanogenerators but also significantly popularize the IoT industry.

In this study, linear elastic fracture mechanic analysis for Reactor Pressure Vessel (RPV) of Westinghouse AP1000 is presented to compute stress intensity factor (SIF) of nodes on the crack front. Then crack propagation analysis is carried out under pressure loading condition and cracks are postulated in the in-let nozzle-cylinder intersection area which is also the highest stress concentration area of the RPV. The SIFs of the surface nozzle corner cracks are numerically computed under different loading conditions, and the crack shape evolving regularities under design loading condition are presented, thus providing a useful tool for fracture mechanic design of RPV. The analysis reveals that the 1/4 wall thickness corner crack of in-let nozzle do not endanger the safety of RPV under design condition. The crack has a larger propagation rate at pressure vessel shell than that at the in-let nozzle.

In this paper, a wideband high aperture efficiency transmitarray antenna (TA) with low cross polarization is proposed. The proposed TA unit cell is a triple-layer patches separated by 0.21-wavelength air gap, and this unit cell can achieve about 360o transmission phase range within -3dB transmission loss. The measured aperture efficiency, gain and -1dB gain bandwidth of the TA operating at 16 GHz are 64%, 26.9dBi and 14% from 15.2GHz to 17.5GHz, respectively. The proposed design has the advantages of the highest aperture efficiency, and lowest cross-polarization below -45dB compared with recently published related works. The developed unit cell has symmetric configuration, so it can also be applied to the design of dual-polarized TA design. The TA array has low fabrication difficulty and cost, and is suitable for high-gain and low cross-polarization application.

To facilitate marker-assisted selection for genetic improvement of the pearl oyster Pinctada fucata martensii, two novel single nucleotide polymorphism (SNP) markers (A376C and A316C) were screened from two shell matrix genes (prismalin-14 and N19 gene), and genotyped to investigate their correlations to five commercial traits, including shell width (SW), shell length (SL), shell height (SH), hinge length (HL) and total weight (TW) in 160 pearl oysters. Both of the two loci showed AC heterozygous. The highest trait values of the five commercial traits measured were the CC genotype in the A316C SNP locus and the AC genotype in the A376C SNP locus, respectively. Significant differences in the trait values were detected between AA- and AC-type individuals (P = 0.005 for SW, P = 0.037 for SH, P = 0.031 for HL and P = 0.007 for TW), but not for SL (P = 0.057) in the A376C locus. These results indicated that AC-type at locus A376C from prismalin-14 gene could be used as a preferred genotype for future selection in breeding program of pearl oyster. Keywords: SNP, Pinctada fucata martensii, Shell matrix gene, Commercial traits

Pearl sac is the tissue that secretes proteins resulting into artificial pearl formation, a highly controlled biomineralization process similar to development of inner shell regulated by the mantle. We present here the pearl sac transcriptome of Pinctada fucata martensii using massively parallel pyrosequencing. A total of 21 729 putative unique transcripts were assembled and annotated. Twenty-three candidate biomineralization genes were identified, such as calmodulin, calponin-like protein (CLP), mantle gene, pearlin, nacrein and Pif. The sequence data contained 4303 potential SNP loci and 4291 probable indels, providing a resource for molecular biomarker, population genetics and gene function. Expression levels of six potential biomineralization genes were also characterized with real-time PCR. The expression level of mantle gene 4 was the highest, followed by lysine-rich matrix protein 4. Nearly all detected genes maintained the highest expression levels in mantle edge and the lowest in pearl sac. In both tissues of mantle centre and pearl sac, the six genes had an obvious higher expression activity in host oyster producing nacre pearls than those producing plain nuclei, but the expression level of CLP was similar in the two host groups. These results will notably advance biomineralization and transcript-wide study in P. fucata martensii and other Pinctada species.