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Maintaining and restoring ecological connectivity (EC) are important measures of mitigating habitat isolation caused by urbanization. Considering the prominent contradiction of land use in highly urbanized areas, the EC protection measures proposed in the previous studies, such as expanding the ecological sources and widening the ecological corridors, are unrealistic. By using the stepping-stone and complex network theories, this paper simulated the ecological network (EN), evaluated the centrality of each ecological source and stepping-stone, and analysed the network robustness under different damage scenarios, then identified the optimal strategy and key patches for EC maintaining. Meanwhile, this paper evaluated whether the key patches are protected by China’s new policies, which are, Ecological Protection Red Line (EPRL) and the Three Lines One Permit (TLOP). The results were as follows: (1) The EN is composed of 53 ecological sources and 291 stepping-stones, with 591 links between them. (2) The network stability can be optimally maintained by prioritizing the protection of stepping-stones with high centrality. (3) The 53 ecological sources and 51 stepping-stones with the highest centrality can ensure the stable operation of the EN, that is, they are key patches for EC maintaining. (4) Compared with EPRL, the protection rate for ecological sources and stepping-stones are significantly improved by TLOP; however, stepping-stones with high centrality require stronger protection. This study enriched the research cases of complex network theory applied in landscape ecology, and provided references for the improvement of policies in the future.

Abstract This study evaluated the cardioprotective properties of Boesenbergia rotunda extract (BrE) against doxorubicin (DOX) induced cardiotoxicity. Rats received oral gavage of BrE for 28 days and DOX (5 mg/kg/week for 3 weeks). Thereafter the animals were sacrificed, blood and cardiac samples were collected for biochemical, histological and immunohistochemical analyses. The results indicated that BrE attenuated DOX triggered body and cardiac weight loss and prevented against cardiac injury by mitigating histopathological alterations in cardiac tissues as well as serum cardiac function enzymes. BrE significantly reduced serum levels of aspartate transaminase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), troponin T (TnT) and creatine kinase-MB (CK-MB) in DOX-treated rats. Furthermore, BrE alleviated cardiotoxicity by reducing DOX instigated oxidative stress and potentiating the level of glutathione, as well as the activities superoxide dismutase and catalase in cardiac tissues. In addition, BrE significantly decreased the characteristic indices of DOX-induced cardiac inflammation and apoptosis. Immuno-histochemical analysis revealed that BrE decreased the stain intensity of p53 and myeloperoxidase (MPO) proteins compared to the DXB alone group. In conclusion, our results indicated that BrE modulated oxidative stress, inflammation and apoptosis to attenuate DOX-induced cardiac damage.

Abstract The knowledge of acoustic wave propagation in a borehole embedded in gas hydrate-bearing sediments is of great significance for the exploitation of gas hydrate. A gas hydrate-bearing sediment is a typical three-phase porous medium containing two solids and one fluid. However, until now, the borehole acoustic wavefield and its component waves within such a porous medium have never been calculated. In this work, a real-axis integration method is proposed to calculate the borehole acoustic field embedded in a three-phase porous medium based on the Biot-type three-phase theory. Meanwhile, a component wave approach, combined with the branch-cut integral method and the residue theorem, including residues at leaky poles is proposed to study the borehole wave propagation of a three-phase porous medium. The branch points and poles of the potential acoustic wave function are obtained, which correspond to the normal and leaky modes on various Riemann sheets. On this basis, the excitation intensity and waveforms of each component are obtained. The result shows that the waveform summed up from all individual waves agrees well with the full waveform calculated by real-axis integration, which provides a theoretical basis for the subsequent inversion of reservoir parameters by using the information of various mode waves.

Carbon storage in terrestrial ecosystems is crucial to advance carbon neutrality and support sustainable development. Extensive studies have explored the effect of land use change on carbon storage, especially urban expansion. As one of the world’s top urban agglomerations, the Pearl River Delta Urban Agglomeration (PRDUA) is facing a dramatic loss of carbon storage along with urbanization. Coordinating economic development and ecological protection and achieving low-carbon green development are urgently needed to alleviate the decline in urban carbon storage. Here, we quantified land use change in the historical period (2000, 2010, 2020) and in 2030 and then estimated carbon storage dynamics at different scales by combining the PLUS model and the InVEST model. We found that: (1) Construction land significantly increased simultaneously with considerable losses of farmland (2273.29 km2) and forestland (949.98 km2) from 2010–2020. In 2030, construction land will expand by 997.83 km2 (12.51%), 1419.97 km2 (17.79%), and 238.60 km2 (2.99%) under the natural growth (NG), urban expansion (UE), and low carbon development (LCD) scenarios, respectively. (2) Compared to 2020, carbon storage under the LCD will reach 6.51×108 Mg, with the lowest decline rate (0.35%). (3) At the city level, Shenzhen had the highest decline rate under various scenarios, followed by Zhuhai and Guangzhou. At the county scale, carbon storage followed the order NG > UE > LCD in 2000–2030. At the grid scale, carbon storage showed a declining trend from the central PRDUA region to marginal areas. Thus, comprehensive considering the multiscale effects of land use change on carbon storage was beneficial to formulate reasonable measures for specific areas. Differentiated development categories at different scales and low-carbon industrial upgrading should be implemented to maintain ecosystem services and achieve sustainable development.

Effective land use management can better maintain ecosystem services, especially in urban agglomerations. However, rational urban scale systems and landscape patterns to maintain key ecosystem services (ESs) in highly urbanized areas remain poorly understood. Taking the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) as a study area, we quantified the spatio-temporal change of key ESs from 2000 to 2020 by the Integrated Valuation of Environmental Services and Tradeoffs (InVEST) model, and simulated land use change prior considering ES conservation priority areas under different multiple development scenarios in 2050 by adopting the future land use simulation (FLUS) model. The main findings were as follows: (1) From 2000 to 2020, natural habitat, water retention and carbon sequestration decreased by 5.5%, 7.9%, and 3.9%, respectively, while the soil conservation increased by 63.7%. (2) The proportion of different conservation priority areas ranged from 10.6% to 22.6%, which were mainly located in the mountainous region. (3) The urban land area would increase from 4286.00 km2 to 4802.25 km2 between 2020 and 2050 in the GBA, with a growth rate of 12.05%. Under the simulation scenarios, the new urban land was mainly distributed in megacities and supercities. (4) Under the integrative conservation scenario, the habitat quality index, water conservation, soil conservation and carbon sequestration would increase by 0.036, 7 × 104 t, 5.11 × 106 t and 0.93 × 106 t, respectively. To maintain the key ESs, we recommend optimizing the urban scale system, making it compact at the city scale and scattered at the regional scale, and strictly restricting the conversion of forestland and farmland adjacent to megacities into urban land. These findings were beneficial to achieve regional high-quality development and sustainable development via rational urban system and landscape management.

The Baiquan Spring in Xinxiang has many functions, such as water supply, agricultural irrigation, humanities, tourism and ecology. It is of great significance to study the dynamics of the spring flow rate and establish a dynamic prediction model for the spring water resources evaluation and protection. In order to further study the dynamic characteristics of the Baiquan Spring flow rate in Xinxiang and evaluate karst water resources in the spring area, based on the data of annually measured spring flow rate and annual average precipitation in the spring area from 1964 to 1978, the main influencing factors of the spring flow rate are determined by using the stepwise regression analysis, and a stepwise regression model is established, with remarkable regression effect. On the basis of the stepwise regression analysis, this paper establishes the GM(1, 2) model, NSGM(1, 2) model and GM(0, 2) model for the dynamic prediction of the spring flow rate. The results show that (1) from 1964 to 1978, the Baiquan spring flow rate was mainly controlled by the precipitation in the spring area, and the spring flow rate lagged behind the precipitation for one year, reflecting the dynamic characteristics of the spring water in the natural state. (2) The accuracy levels of the three grey models are the highest (excellent). (3) From 1964 to 1978, the measured discharge of the Baiquan spring ranged from 2.347 to 6.448 m3/s, with an average of 3.904 m3/s. The predicted values of the stepwise regression model range from 1.882 to 6.383 m3/s, with an average of 3.904 m3/s. The predicted value of the GM(1, 2) model varies between 2.327 and 6.448 m3/s, with an average of 3.939 m3/s. The predicted values of the NSGM(1, 2) model range from 2.133 to 6.448 m3/s, with an average of 3.927 m3/s. The predicted values of the GM(0, 2) model range from 1.787 to 6.448 m3/s, with an average of 3.907 m3/s. (4) The average relative errors of the stepwise regression model and the three grey models mentioned above are 7.794%, 7.292%, 7.122% and 7.797% respectively, all of which are less than 10%, indicating that they can be used for dynamic prediction of the spring water. Among them, the NSGM(1, 2) model has a higher accuracy and better fitting to the inflection point of the curve. (5) According to the spring flow rate from 1964 to 2030 predicted by the four models, the exploitation resources of the karst water in the Baiquan spring area should not exceed 1.69 m3/s from the angle of spring protection. The research results can not only provide scientific basis for spring flow dynamic prediction and spring area water resources evaluation, but also provide reference for the study of groundwater dynamics in similar areas.

The inversion of gas hydrate saturation is a critical procedure in the evaluation of hydrate reservoirs. In this paper, a theoretical model for a borehole acoustic wavefield excited by multipole sources is established for the first time. On this basis, the attenuation of the dipole flexural waves is obtained, and in combination with the results of sensitivity analysis, an approach for inverting natural gas hydrates using the attenuation characteristics of the dipole flexural wave is proposed. The results of the sensitivity analysis demonstrate that the attenuation of the dipole flexural wave is sensitive to gas hydrate saturation. Numerical results derived from synthetic logging data are provided to illustrate the viability of the inversion of gas hydrate saturation. Even when significant noise is introduced into the receiver signal arrays, the inversion method remains stable and accurately assesses gas hydrate saturation. The correctness and effectiveness of the proposed approach are substantiated through the processing of numerical simulation data. This work provides a potent processing approach for evaluating reservoir hydrate saturation utilizing acoustic well-logging information.

In the study of atmospheric dynamics, the vorticity equation in a rotating coordinate system plays a crucial role. However, a paradox arises when one considers the term related to spatial variations in Coriolis parameters known as the “β-term”. The β-term should not appear in the vorticity equation because the three-dimensional (3D) planetary vorticity is a constant vector. However, it is always in the vorticity equation. In this article, the source of the β-term in different rotating coordinates are investigated. The results show that in the spherical coordinate system, the β-term comes from the directions changing of one of the unit vectors (j→) with the spatial position and originates from the tilting term. By contrast, in the height coordinate system, the β-term cannot be derived from the tilting term as the individual changes of the coordinate frames with time are omitted, Instead it is proven to be related to the advection term. Although the both coordinate systems are rotating coordinate systems, the sources of their β-terms differ due to the simplification levels of the coordinate systems. Although the 3D planetary vorticity is a constant vector in the spherical coordinate system, the conversions between its components are allowable and spatial derivatives of its components can be observed, eliminating the paradox of the β-term. However, in the height coordinate system, the 3D planetary vorticity vector is not a constant vector in order to maintain the conservation of the absolute angular momentum and mechanical energy. To account for the influence of the earth’s curvature on atmospheric motion, the β-term of the Coriolis parameters varying with the latitude appears. So, the origin of the β-term paradox proposed in the height coordinate system comes from a misunderstanding of the physical constraints of the height coordinate system.

It is rather significant to reveal the real-time variation of oil sample viscosity during ultrasonic irradiation to research the mechanism of viscosity change. In this paper, we first simulate the acoustic field distribution law in the reaction chamber by using the finite element method and orthogonal experiment method, then measure the viscosity of the oil sample with temperature by vibration type viscometer and get the corresponding function equation by fitting. On this basis, we measure the viscosity of the oil sample with ultrasonic irradiation time and electric power change in real-time and in situ, and finally analyze the mechanism of oil sample viscosity variation by using a temperature recorder and cavitation noise method. The results show that the greatest influence on the acoustic pressure in the reaction chamber is the change of the transducer probe in the height Z direction, followed by the width X direction and the depth Y direction. The viscosity of the oil sample shows an exponential decay with the increase in temperature. With the increase of ultrasonic irradiation time and electric power, the viscosity of the oil sample is gradually reduced. By comparing the effect of heating and ultrasonic irradiation on viscosity, it is found that ultrasonic irradiation not only changes the viscosity through thermal effect but also the cavitation noise analysis and the phenomena observed in the experiment confirm that the cavitation effect and mechanical effect exist all the time.

Abstract Significant variability of raindrop size distributions (DSDs) has been observed in the “21·7” Henan extremely heavy rainfall event (the “21·7” Henan EHR event), while the capability of model to reproduce such complicated heavy rainfall DSDs is yet unclear. This study primarily evaluates the simulated DSDs of multiple microphysics schemes by comparing with the observations from a network of 50 disdrometers. Constrained DSD variability is identified in most schemes that the simulated raindrop mean sizes are gradually restricted around specific values as the growth of heavy rainfall intensity. The schemes are also incapable of reproducing the different raindrop mean sizes from deep convection and shallow convection. Moreover, simulations show unrealistic evolutions of raindrop mean size standard deviations as height declines. By investigating the empirical formula and performing sensitivity experiment, the constrained DSD variability in heavy rainfall is largely blamed on the insufficient parameterizations of the self‐collection (breakup) processes.

A severe convective weather event that was caused by multiple supercell storms occurred in the border area between the Hebei and Henan provinces at 16-22 Beijing Time of 31 July 2021. The two of these supercell storms (hereinafter referred to as Handan supercell and Puyang supercell, respectively) with the longest life time affected successively southern Hebei and northern Henan, resulting in five extreme downbursts. Using the observational data from regional automatic weather stations and the Doppler weather radar data, we performed the analysis of the radar early warning effect of thunderstorm gale induced by these five extreme downbursts in the border area based on the radar echo early warning index of the downbursts induced by supercell storms. The main results are as follow: (1) The radar echo characteristics such as refectivity core height, middle altitude radial convergence, and radial velocity at the lowest elevation for the supercell storms in the five extreme downbursts all meet the criterias of early warning. On average, twelve echo features related to thunderstorm gale, of which the strength reach maximum before the strongest downbursts, appeared before each extreme downburst. Among these features, the ones related to convective storm downdraft and near-surface strong wind can be used as the warning signals 10-37 minutes in advance for the downbursts. (2) The refectivity factor core, mesocyclonecore, and mesocyclone bottom height were all decreased before the first extreme downburst induced by the two supercell storms, which may be used as the warning signals 19-22 minutes in advance, respectively. (3) The Handan supercell storm is a classic isolated supercell, while the Puyang supercell storm is embeded in multicells. The former has the clearer echo structure and is easier to be identified than the latter. The relevant echo features or characteristic quantities are also better be used for early warning of downburst. (4) One supercell storm can bring several extreme downbursts during its lifetime, so it is necessary to pay attention to the changes of relevant radar echo characteristics after its occurrence, especially in its dissipating stage.

The properties and distributions of precipitation are often determined by specific synoptic patterns. Hence, the objective identification of corresponding impact patterns is an important field of research for improving rain forecasting. However, the identification of the weather patterns producing intense rainfall is much more challenging. Since they are violent and local, impact patterns tend to be meso- or smaller-scale systems and are often incompletely presented or only presented in limited regions. In this paper, a deep learning network with a feature cross-fusion module, FConvNeXt, was proposed to address this difficulty and showed great potential. Four major patterns corresponding to intense rainfall in the Beijing–Tianjing–Hebei Region were studied. Statistical testing showed that FConvNeXt performed better than ConvNeXt and ResNet and that the model could identify the weak synoptic forcing type, the subtropical high-pressure type, and the low-vortex pattern with high accuracy. Furthermore, a strictly independent 2021 dataset was tested, and FConvNeXt maintained an equal if not even slightly better performance in spite of a decrease in the subtropical high-pressure type. Meanwhile, the study showed that the accuracy in identifying the upper-level trough type is the lowest for the three deep learning methods, which may be because the northeast vortex was intercepted in the limited region, making it difficult to distinguish from the shallow upper-level trough type. This study is useful for improving the fine objective of forecasting intense rainfall.

From 17 to 22 July 2021, a series of disastrous rainstorms appeared within Henan Province and its surroundings, which rendered 398 dead/missing and a direct economic loss of up to ∼114 billion Yuan. This event was named as the “21.7” Henan torrential rainfall event (TRE), and it could be divided roughly into three stages according to the precipitation features and dominant weather systems. This study mainly focused on the development and maintenance mechanisms of a long-lived (72 h) quasi-stationary mesoscale vortex that governed the earlier stage of the “21.7” TRE. Main results are as follows: 1) the mesoscale vortex formed/maintained in a favorable environment which was characterized by the South-Asia-high associated divergence in the upper troposphere, and the relay transport of relatively cold air by the trough and high-pressure system in the middle troposphere. 2) the vertical stretching due to lower-level convergence and the upward transport of cyclonic vorticity by ascending motions served as the first and second dominant factors for the mesoscale vortex’s rapid development and long-time maintenance, whereas, the import/export transport of anticyclonic/cyclonic vorticity into/from the vortex’s central region and the tilting effects were mainly detrimental for the vortex’s development/maintenance. 3) the air particles that formed the mesoscale vortex mainly came from the levels below 1,500 m, within the regions in lower latitudes. The air particles experienced notable precipitation before the formation of the mesoscale vortex, which contributed to the vortex’s formation through latent heat release.

The use of social media is becoming a necessary daily activity in today’s society. Excessive and compulsive use of social media may lead to social media addiction (SMA). The main aim of this study was to investigate whether demographic factors (including age and gender), impulsivity, self-esteem, emotions, and attentional bias were risk factors associated with SMA. The study was conducted in a non-clinical sample of college students (N = 520), ranging in age from 16 to 23 years, including 277 females (53%) and 243 males (47%). All participants completed a survey measuring impulsivity, self-esteem, anxiety, depression, social anxiety, loneliness, and attentional bias. The final hierarchical regression model indicated significant risk factors for SMA with an accuracy of 38%. The identified set of associated risk factors included female gender (β = −0.21, t = −4.88, p < 0.001), impulsivity (β = 0.34, t = 8.50, p < 0.001), self-esteem (β = −0.20, t = −4.38, p < 0.001), anxiety (β = 0.24, t = 4.43, p < 0.001), social anxiety (β = 0.25, t = 5.79, p < 0.001), and negative attentional biases (β = 0.31, t = 8.01, p < 0.001). Finally, a discussion of the results is presented, followed by corresponding recommendations for future studies.

Abstract Background The classification of Breast Imaging Reporting and Data System 4A (BI-RADS 4A) lesions is mostly based on the personal experience of doctors and lacks specific and clear classification standards. The development of artificial intelligence (AI) provides a new method for BI-RADS categorisation. We analysed the ultrasonic morphological and texture characteristics of BI-RADS 4A benign and malignant lesions using AI, and these ultrasonic characteristics of BI-RADS 4A benign and malignant lesions were compared to examine the value of AI in the differential diagnosis of BI-RADS 4A benign and malignant lesions. Methods A total of 206 lesions of BI-RADS 4A examined using ultrasonography were analysed retrospectively, including 174 benign lesions and 32 malignant lesions. All of the lesions were contoured manually, and the ultrasonic morphological and texture features of the lesions, such as circularity, height-to-width ratio, margin spicules, margin coarseness, margin indistinctness, margin lobulation, energy, entropy, grey mean, internal calcification and angle between the long axis of the lesion and skin, were calculated using grey level gradient co-occurrence matrix analysis. Differences between benign and malignant lesions of BI-RADS 4A were analysed. Results Significant differences in margin lobulation, entropy, internal calcification and ALS were noted between the benign group and malignant group (P = 0.013, 0.045, 0.045, and 0.002, respectively). The malignant group had more margin lobulations and lower entropy compared with the benign group, and the benign group had more internal calcifications and a greater angle between the long axis of the lesion and skin compared with the malignant group. No significant differences in circularity, height-to-width ratio, margin spicules, margin coarseness, margin indistinctness, energy, and grey mean were noted between benign and malignant lesions. Conclusions Compared with the naked eye, AI can reveal more subtle differences between benign and malignant BI-RADS 4A lesions. These results remind us carefully observation of the margin and the internal echo is of great significance. With the help of morphological and texture information provided by AI, doctors can make a more accurate judgment on such atypical benign and malignant lesions.

Cavitation intensity is used to describe the activity of cavitation, and several methods are developed to identify the intensity of cavitation. This work aimed to provide an overview and discussion of the several existing characterization methods for cavitation intensity, three acoustic approaches for charactering cavitation were discussed in detail. It was showed that cavitation noise spectrum is too complex and there are some differences and disputes on the characterization of cavitation intensity by cavitation noise. In this review, we recommended a total cavitation noise intensity estimated via the integration of real cavitation noise spectrum over full frequency domain instead of artificially adding inaccurate filtering processing.

Viscosity reduction of heavy oil has economic benefits and applicational value in the field. Applying viscosity reduction technology of heavy oil with ultrasound, this paper examines the influence of ultrasonic irradiation time and the addition of tetralin and ethylene glycol on viscosity reduction of heavy oil. Fourier Transform Infrared Spectrometer (FTIR) and Gas Chromatograph (GC) were used to analyze the chemical compositions and structural changes of oil samples before and after ultrasonic irradiation, and the effects of ultrasound on viscosity changes are presented. The viscosity reduction rate (VRR) was best at an irradiation time of 6 mins under the current experimental conditions, with VRR reaching more than 80%. When the irradiation time reached 12 mins, the viscosity of oil samples increased conversely. Chemical analysis reveals that the light components in the oil samples increased after the ultrasonic irradiation, indicating that the cavitation, thermal, and mechanical effects of ultrasound could play a role in breaking long chains of carbon, thus reducing the viscosity. The increase in viscosity may have been caused by a reassociation between molecules and/or the coking of heavy oil.

The reserves of heavy oil are enormous. However, its high viscosity and other characteristics make heavy oil extraction and transportation extremely difficult. Power ultrasonic (US) reforming technology on heavy oil has the advantages of environmental protection and fast results, so it is important to understand the mechanism of ultrasonic reforming. We examine the influence law of the electric power input of the US transducer on the viscosity of heavy oil. Fourier Transform Infrared Spectrometer (FTIR) and Gas Chromatography (GC) are applied to explain the changes in different functional groups, heavy components, and carbon chains before and after US irradiation. The cavitation noise method is also used to study the influences of variance in the intensity of cavitation on the viscosity of heavy oil. The results indicate that the viscosity of heavy oil first decreases, and next increases with an increase in electric power. The functional groups and chromatographic distillation also change in different forms, and with an increase in electric power, the cavitation effect is gradually enhanced. These findings suggest that it is not that the stronger the cavitation, the greater the influence on the viscosity of heavy oil.

A knowledge of wave propagation in boreholes with gas hydrate-bearing sediments, a typical three-phase porous medium, is of great significance for better applications of acoustic logging information on the exploitation of gas hydrate. To study the wave propagation in such waveguides based on the Carcione–Leclaire three-phase theory, according to the equations of motion and constitutive relations, a staggered-grid finite-difference time-domain (FDTD) scheme and a real axis integration (RAI) algorithm in a two-dimensional (2D) cylindrical coordinate system are proposed. In the FDTD scheme, the partition method is used to solve the stiff problem, and the nonsplitting perfect matched layer (NPML) scheme is extended to solve the problem of the false reflection waves from the artificial boundaries of the computational region. In the RAI algorithm, combined with six boundary conditions, the displacement potentials of waves are studied to calculate the borehole acoustic wavefields. The effectiveness is verified by comparing the results of the two algorithms. On this basis, the acoustic logs within a gas hydrate-bearing sediment are investigated. In particular, the wave field in a borehole is analyzed and the amplitude of a Stoneley wave under different hydrate saturations is studied. The results indicate that the attenuation coefficient of the Stoneley wave increases with the increase of gas hydrate saturation. The acoustic responses in a borehole embedded in a horizontally stratified hydrate formation are also simulated by using the proposed FDTD scheme. The result shows that the amplitude of the Stoneley wave from the upper interface is smaller than that from the bottom interface.

The Ecological Protection Redline (EPR) is an innovative measure implemented in China to maintain the structural stability and functional security of the ecosystem. By prohibiting large-scale urban and industrial construction activities, EPR is regarded as the “lifeline” to ensure national ecological security. It is of great practical significance to scientifically evaluate the protection effect of EPR and identify the protection vacancies. However, current research has focused only on the protection effects of the EPR on ecosystem services (ESs), and the protection effect of the EPR on ecological connectivity remains poorly understood. Based on an evaluation of ES importance, the circuit model, and hotspot analysis, this paper identified the ecological security pattern in Guangdong–Hong Kong–Macao Greater Bay Area (GBA), analyzed the role of EPR in maintaining ES and ecological connectivity, and identified protection gaps. The results were as follows: (1) The ecological sources were mainly distributed in mountainous areas of the GBA. The ecological sources and ecological corridors constitute a circular ecological shelter surrounding the urban agglomeration of the GBA. (2) The EPR effectively protected water conservation, soil conservation, and biodiversity maintenance services, but the protection efficiency of carbon sequestration service and ecological connectivity were low. In particularly, EPR failed to continuously protect regional large-scale ecological corridors and some important stepping stones. (3) The protection gaps of carbon sequestration service and ecological connectivity in the study area reached 1099.80 km2 and 2175.77 km2, respectively, mainly distributed in Qingyuan, Yunfu, and Huizhou. In future EPR adjustments, important areas for carbon sequestration service and ecological connectivity maintenance should be included. This study provides a comprehensive understanding of the protection effects of EPR on ecological structure and function, and it has produced significant insights into improvements of the EPR policy. In addition, this paper proposes that the scope of resistance surface should be extended, which would improve the rationality of the ecological corridor simulation.

Natural gas hydrate is a new clean energy source in the 21st century, which has become a research point of the exploration and development technology. Acoustic well logs are one of the most important assets in gas hydrate studies. In this paper, an improved Carcione–Leclaire model is proposed by introducing the expressions of frame bulk modulus, shear modulus and friction coefficient between solid phases. On this basis, the sensitivities of the velocities and attenuations of the first kind of compressional (P1) and shear (S1) waves to relevant physical parameters are explored. In particular, we perform numerical modeling to investigate the effects of frequency, gas hydrate saturation and clay on the phase velocities and attenuations of the above five waves. The analyses demonstrate that, the velocities and attenuations of P1 and S1 are more sensitive to gas hydrate saturation than other parameters. The larger the gas hydrate saturation, the more reliable P1 velocity. Besides, the attenuations of P1 and S1 are more sensitive than velocity to gas hydrate saturation. Further, P1 and S1 are almost nondispersive while their phase velocities increase with the increase of gas hydrate saturation. The second compressional (P2) and shear (S2) waves and the third kind of compressional wave (P3) are dispersive in the seismic band, and the attenuations of them are significant. Moreover, in the case of clay in the solid grain frame, gas hydrate-bearing sediments exhibit lower P1 and S1 velocities. Clay decreases the attenuation of P1, and the attenuations of S1, P2, S2 and P3 exhibit little effect on clay content. We compared the velocity of P1 predicted by the model with the well log data from the Ocean Drilling Program (ODP) Leg 164 Site 995B to verify the applicability of the model. The results of the model agree well with the well log data. Finally, we estimate the hydrate layer at ODP Leg 204 Site 1247B is about 100–130 m below the seafloor, the saturation is between 0–27%, and the average saturation is 7.2%.

In this article, a novel design of a piezoelectric dipole transducer is proposed for formation acoustic velocity measurement in the vicinity of a borehole with a frequency range of 0.4–6 kHz. The transducer which actuates a cylindrical shell to generate a pure dipole mode wave by using multiple piezoelectric bender bars is analyzed theoretically and simulated numerically by using the finite element method (FEM). Moreover, the transducer is fabricated and tested to compare with the numerical simulation results, which shows that the test and simulation results are in good agreement. Finally, compared with numerical simulation results of the traditional dipole transducer, it is shown that the proposed dipole transducer has higher transmitting sensitivities than commonly used ones, especially in low frequency responses. This work lays a foundation for the new development of the transducer in borehole dipole acoustic shear wave measurements. Especially, in a slow formation where the shear wave velocity is lower than that of compressional wave in the borehole fluid, the transducer could be used for highly efficient shear wave velocity measurements.

Underground pipelines are vital means of transporting fluid resources like water, oil and gas. The process of locating buried pipelines of interest is an essential prerequisite for pipeline maintenance and repair. Acoustic pipe localization methods, as effective trenchless detection techniques, have been implemented in locating underground utilities and shown to be very promising in plastic pipeline localization. This paper presents a comprehensive review of current acoustic methods and recent advances in the localization of buried pipelines. Investigations are conducted from multiple perspectives including the wave propagation mechanism in buried pipe systems, the principles behind each method along with advantages and limitations, representative acoustic locators in commercial markets, the condition of buried pipes, as well as selection of preferred methods for locating pipelines based on the applicability of existing localization techniques. In addition, the key features of each method are summarized and suggestions for future work are proposed. Acoustic methods for locating underground pipelines have proven to be useful and effective supplements to existing localization techniques. It has been highlighted that the ability of acoustic methods to locate non-metallic objects should be of particular practical value. While this paper focuses on a specific application associated with pipeline localization, many acoustic methods are feasible across a wide range of underground infrastructures.

A hydrodynamic model of using quartz tuning forks (QTFs) for density and viscosity sensing, by measuring the resonance frequency and quality factor, has been established based on the cantilever beam theory applied to the atomic force microscope (AFM). Two examples are presented to verify the usability of this model. Then, the Sobol index method is chosen for explaining quantitatively how the resonance frequency and quality factor of the QTFs are affected by the fluid density and viscosity, respectively. The results show that the relative mean square error in viscosity of the eight solutions evaluated by the hydrodynamic model is reduced by an order of magnitude comparing with Butterworth−Van Dyke equivalent circuit method. When the measured resonance frequency and quality factor of the QTFs vary from 25,800−26,100 Hz and 28−41, the sensitivities of the quality factor affected by the fluid density increase. This model provides an idea for improving the accuracy of fluid component recognition in real time, and lays a foundation for the application of miniaturized and cost-effective downhole fluid density and viscosity sensors.

Buried pipeline systems play a vital role in energy storage and transportation, especially for fluid energies like water and gas. The ability to locate buried pipes is of great importance since it is fundamental for leakage detection, pipeline maintenance, and pipeline repair. The vibro-acoustic locating method, as one of the most effective detection technologies, has been studied by many researchers. However, previous studies have mainly focused on vibro-acoustic propagation in buried water pipes. Limited research has been conducted on buried gas pipes. In this paper, the behavior of gas-dominated wave motion will be investigated and compared against water-dominated wave motion by adapting an established analytical model of axisymmetric wave motion in buried fluid-filled pipes. Furthermore, displacement profiles in spatial domain resulting from gas-dominated wave in buried gas pipeline systems will be analyzed, and the effects of pipe material, soil property, as well as mode wave type will be discussed in detail. An effective radiation coefficient (ERC) is proposed to measure the effective radiation ability of gas-dominated wave and water-dominated wave. It is observed that the gas-dominated wave in gas pipes cannot radiate into surrounded soil as effectively as water-dominated wave in water pipes because of the weak coupling between gas and pipe-soil. In this case, gas-dominated wave may not be the best choice as the target wave for locating buried gas pipes. Therefore, the soil displacements result from the shell-dominated wave are also investigated and compared with those from gas-dominated wave. The results show that for buried gas pipes, the soil displacements due to radiation of shell-dominated wave are stronger than gas-dominated wave, which differs from buried water pipe. Hence, an effectively exciting shell-dominated wave is beneficial for generating stronger vibration signals and obtaining the location information. The findings of this study provide theoretical insight for optimizing the current vibro-acoustic method when locating buried gas pipes.

Acoustic logging while drilling (LWD) can extract P-wave and S-wave information from the formation. However, the transmission of the collar wave propagated directly from the emitter to the receiver may interfere with the P-wave and S-wave and affect the extraction of formation information. Therefore, it is necessary to design a suitable acoustic isolator between the transmitter and the receiver to attenuate the drill waves. The commonly used acoustic LWD isolator is that the outer surface of the drill collar is evenly grooved to attenuate the collar wave. However, there are still disadvantages such as the lack of mechanical strength of the evenly grooved acoustic insulators and the ability to extract clean longitudinal wave under certain circumstances. Therefore, there is an urgent requirement to design a new type of acoustic LWD isolator with sufficient strength and acoustic insulation requirements. In recent years, spoof surface acoustic waves (SSAWs) generated by periodic corrugated surface rigid plates have attracted the attention of many researchers, who can spatially separate the surface waves to attenuate acoustic waves. In this paper, a new type of acoustic LWD insulator based on SAW space separation structure is proposed. The finite element software ANSYS is used for acoustic analysis.

Multi-component fingerprinting and quantitation of the glucosinolates and nucleosides in samples of Radix Isatidis have been carried out using high-performance liquid chromatography with diode-array detection and electrospray ionization tandem mass spectrometry (HPLC–DAD–ESI/MS). Five nucleosides together with one glucosinolate were identified by comparing retention times, ultraviolet spectra, mass spectra and/or empirical molecular formulae of reference compounds. Quantitation of these six compounds was carried out simultaneously by HPLC on a Phenomenex Luna C18 column using gradient elution with methanol and water and detection at 254 nm. All calibration curves were linear (r>0.9994) within test ranges. Limits of detection and quantitation were 0.33 ng and 2.50 ng on column, respectively. Intra- and inter-day precision (as relative standard deviation) for all analytes was