Search

Nondimensionalization, a theoretical approach for establishing interconnections among parameters within a set of equations, has proven to be an effective tool for the analysis of atmospheric turbulence. By applying nondimensionalization to turbulence equations, a concise form of dimensionless turbulence functions can be obtained. This process also yields several dimensionless parameters, defined as combinations of characteristic scales. From the dimensionless tensor B and vector β θ introduced in this study, the characteristic length scale, z s , can be defined as an alternative of length scale in similarity theories. Using the data from observational station in Horqin Sandy Land, quantified verifications of similarity relationships are carried out. The dimensionless parameters derived from nondimensionalization is not only in accordance with traditional turbulence theories but also facilitate the derivation of relationships among other dimensionless parameters. This reveals new similarity relationships that supplement the Monin–Obukhov theory. Under conditions of flat terrain and steady motions, the new length scale gives rise to similarity relationships exhibiting "4/3" exponential and near-linear patterns, which are associated with turbulent transport. These results make it possible to obtain the turbulent fluxes directly from the statistics of meteorological elements, even in stable stratifications. Consequently, the method of nondimensionalization can be taken as a reference in parameterization schemes of turbulence and climate models, and is fruitful in prospect of further study on atmospheric turbulence. [ABSTRACT FROM AUTHOR]

In this paper, a new segmental blank holder technique was developed. The blank holder force (BHF) was applied on sheet metal independently and effectively by the binder which was divided into double rings. The principle of holding was derivatized by theoretical formulas, thereby proving that the BHF distribution applied by the new binder is more reasonable. Furthermore, combined with numerical simulation, it can be found that the wrinkling was better suppressed. Finally, the effectiveness of the segmental blank holder technique was proven by a series of experiments with AA5754 plate. It is verified that the flange wrinkling was demonstrated to be more eliminated than that using the single blank holder. Compared with 1:2 and 2:1, when the distribution ratio between the outer ring and the inner ring is 1:2 (the applied BHF is 6.9 kN), there has a better-forming quality. [ABSTRACT FROM AUTHOR]

Deserts play an important role in the climate system, which is closely associated with the emission and transport of dust aerosols. Based on the intensive observation experiment in the Taklimakan Desert, the potential physical processes between the deep convective boundary layer (CBL) and dust emission are revealed in this study. Deep CBL enables the formation of clouds in the late afternoon, leading to significant cooling of surface. Large‐scale buoyant coherent structures thereby transform into the mechanical coherent structures confined near the surface. The responses promote the earlier occurrence of low‐level jet (LLJ) than in cloudless conditions, which allows the downward transport of LLJ momentum and substantially increases surface wind. Therefore, dust emission is initiated by strong wind at dusk and lasts for several hours. The results are useful to predict dust emissions and improve our understanding of distinctive boundary‐layer processes in desert regions. Plain Language Summary: Desert is a key component of regional/global climate system, which is closely associated with the emission and transport of dust aerosols. A better understanding of dust emission mechanisms and their interaction with atmospheric physical processes is of great significance for improving numerical weather and climate models. This study investigates possible physical mechanisms of the dust emission related to deep atmosphere boundary layer, based on the field experiment in the Taklimakan Desert. It is found that the formation of late‐afternoon clouds and the occurrence of wind maxima at 400–600 m are crucial during the processes. Initially, the formation of clouds is enabled by deep atmosphere boundary layer that developed in the late afternoon. After cloud formation, surface becomes cooling, and then the upper part of the boundary layer is gradually released from the surface frictional restraint, which promotes the development of wind maxima at 400–600 m. As the momentum of the wind maxima is transported downwards, surface wind substantially increases, which systematically blows dust particles up. Consequently, dust emission happens at dusk in desert regions. Key Points: Deep convective boundary layer enables the lifting condensation of moisture and the formation of boundary‐layer clouds in desert regionsThe emergence of late‐afternoon clouds strengthens the surface cooling and thus advances the development of low‐level jetDownward momentum transfer from low‐level jet to near‐surface wind is crucial to initiate dust emission at dusk [ABSTRACT FROM AUTHOR]

Turbulent fluxes play a critical role in atmospheric science and are usually calculated from the eddy covariance system. However, the presence of motions of larger scale and the bias from observational instruments often affects the procurement of turbulent fluxes. Based on the Hilbert–Huang transform, the properties of transport can be defined and used to distinguish non‐turbulent motions from the observational data, and a new way of decomposing the variables is thereby put forward to reconstruct the turbulent flux series. To quantify the influence of non‐turbulent motions on the calculation of turbulent flux, the non‐turbulent motions extracted from the five‐level turbulence data of the Tianjin 255‐m meteorological tower from July 1 to August 31, 2017 are examined. The results reveal that the presence of non‐turbulent motion can lead to a universal overestimation of turbulent flux, and the degree of overestimation increases with the complexity and the intensity of non‐turbulent motion. According to the consequences above, an empirical relationship, together with the corresponding coefficients, is given to provide a guidance on the correction of turbulent fluxes in practical use, such as the simulation of atmospheric turbulence and the parameterization in meteorological and climate models. [ABSTRACT FROM AUTHOR]

The complexity of aerosol particle properties and the diversity of characterizations make aerosol vertical transport flux measurements and analysis difficult. Although there are different methods, such as aerosol particle number concentration flux and aerosol mass flux based on the eddy covariance principle as well as aerosol mass flux measurements based on the light-propagated large-aperture scintillation principle, there is a lack of mutual validation among the different methods. In this paper, a comparison of aerosol mass flux measurements based on the eddy covariance principle and aerosol mass flux measurements based on the light-propagated large-aperture scintillation principle is carried out. The key idea of aerosol mass flux measurements based on the light-propagated large-aperture scintillation principle is the determination of the imaginary part of the atmospheric equivalent refractive index structure parameter (AERISP). In this paper, we first compare the AERISPs measured by two different methods and then compare the aerosol mass vertical transport fluxes obtained by different methods. The experiments were conducted on the campus of the University of Science and Technology of China (USTC). A light propagation experiment was carried out between two tall buildings to obtain the imaginary and real parts of the AERISPs for the whole path, which in turn can be used to obtain the aerosol vertical transport flux. An updated visibility meter is installed on the meteorological tower in the middle of the light path, which is utilized to obtain the single-point visibility, which is then converted to the imaginary part of the atmospheric equivalent refractive index (AERI). The imaginary parts of the AERISP were obtained via spectral analysis with visibility data. The results show that the imaginary parts of the AERISPs obtained by different methods are in good agreement. The imaginary part of the AERI measured by the visibility meter and the vertical wind speed obtained by the ultrasonic anemometer were used for covariance calculations to obtain the aerosol vertical transport flux. The trends in aerosol vertical transport fluxes obtained by the different methods are consistent, and there are differences in some details, which may be caused by the inhomogeneity in the vertical transport of aerosol fluxes. The experimental results also showed that urban green land is a sink area for aerosol particles. [ABSTRACT FROM AUTHOR]

The Taklimakan Desert is one of key climate regions in East Asia, both highly influencing and highly sensitive to local/regional climate change. Based on a comprehensive observation experiment from 1 to 31 May 2022 in the hinterland of the Taklimakan Desert, the characteristics and mechanisms of turbulence intermittency are investigated in this study, with the purpose to correct turbulent fluxes. Using an improved algorithm to decompose turbulence and submeso motions, two intermittency regimes are recognized in the Taklimakan Desert, namely, D and T intermittency and onD intermittency. The former occurs under strongly stable conditions, characterized by the coexistence of dynamic and thermodynamic turbulence intermittency. The latter occurs under strongly unstable conditions and represents only dynamic turbulence intermittency. Physically, the D and T intermittency regime is related to submeso waves, whereas the onD regime is caused by the horizontal convergence/divergence of convective circulations. With the influence of intermittency and submeso motions, the observed turbulent statistics deviate from reality, which would mask the similarity relationships. To overcome the problem, turbulent statistics are corrected by removing submeso components from original fluctuations. The effectiveness of this method is demonstrated based on the flux–gradient relationships. It is also suggested that, for a big dataset, the impact of onD intermittency can be simply corrected by a correction factor while that of D and T intermittency cannot. The results of this study are helpful to develop the parameterization of turbulent exchange processes in the Taklimakan Desert, which is significant to improve the accuracy of weather forecasting and climate prediction. Significance Statement: The Taklimakan Desert plays an important role in the evolution of weather and climate in East Asia. With strong surface thermal forcing, turbulence often shows distinctive intermittency, which largely constrains the evaluation of land–atmosphere exchange in this key climate region. This study aims to understand the characteristics of turbulence intermittency and its physical mechanisms, and further to correct the influence of turbulence intermittency on turbulent fluxes in the Taklimakan Desert. This is significant because the results are helpful to improve the parameterization of subgrid processes in the key climate region for atmospheric models, which points the way toward enhancing the accuracy of weather forecasting and climate prediction. [ABSTRACT FROM AUTHOR]

Exact solutions of spherically symmetric black hole and gravitational wave are explored in f(R) gravity in arbitrary dimension. We find two exact solutions for the radiation and absorption of null dust. In the framework of general relativity, the Birkhoff theorem strictly forbids the existence of spherical gravitational waves in vacuum space. We find spherical non-perturbative gravitational waves, which are shear-free, twist-free, but expanding. [ABSTRACT FROM AUTHOR]

This research is aimed to adjust blank holder force (BHF) in different flange areas to eliminate wrinkles and cracks on rectangular box deep drawing products. The calculating formulas of the critical BHF in the flange area are derived by using the energy method. And a wrinkle model parameter m effect on the critical BHF is analyzed. It is shown that the critical BHF decreases with decreasing m as the same wrinkle height. A steel sheet of SPCC grade, thickness of 0.6 mm, is used in the finite element simulation study. It is shown that the segmental blank holder technique is better than the conventional one. Finally, compared to the application of the single blank holder, BHF can be quite effective for preventing the occurrence of cracking and increasing the formability of deep drawing. [ABSTRACT FROM AUTHOR]

Turbulence intermittency driven by submeso motions limits the progress of turbulence theory. Field observations from the Horqin Atmospheric Boundary‐Layer and Environment Experimental Station, China were used to investigate turbulence intermittency. An automated algorithm to Separate and reconstruct Submeso and Turbulent motions (SST) was improved for more accurately extraction and quantitative characterization of submeso motions. The existing intermittency intensity indexes, the local intermittency strength of turbulence (LIST) and intermittency strength (IS), which are based on kinetic energy only, are revised by considering the potential energy of submeso and turbulent motions to quantify intermittency intensity more comprehensively. The analysis of eight cases revealed that turbulent intermittency events are characterized by quiescent (pulsation, material, and energy transportation are weak) and burst (pulsation, material, and energy transportation fluctuate violently) periods. The conversion of both the kinetic and potential energy of submeso to turbulent motion contributes to the transition from quiescent to burst periods. The transition always occurs after ∆TE$$ \Delta \mathrm{TE} $$ <0 (the total energy difference between the submeso motion and turbulence), followed by a significant increase in ∆TE$$ \Delta \mathrm{TE} $$. Atmospheric stability decreases during the transition from quiescent to burst periods in most cases. In a totally intermittent night, the burst periods take up most of the material and energy transport, and the amount transported is not smaller than that during a totally turbulent night. The weaker the intermittency at night, the greater the capacity of turbulent transport. A comparison of five types of turbulence intermittency intensity indexes highlights the consistency and advantages between LIST (IS) and indexes in the literature. Finally, we found that turbulent intermittency events tended to occur more easily in the atmospheric boundary layer (ABL) with small winds (U < 2 m s−1) or stable stratification (Rib > 1), although they can also occur in ABL with unstable stratification and in the non‐stationary state of the day–night transition. [ABSTRACT FROM AUTHOR]

The North China Plain (NCP) is troubled by severe haze pollution and the evolution of haze pollution is closely related to the atmospheric boundary layer (ABL). However, experimental and theoretical studies on the physical-chemical processes of the ABL in the NCP are lacking, with many scientific problems to be addressed. To solve these problems, the Comprehensive Observation on the Atmospheric boundary layer Three-dimensional Structure (COATS) during haze pollution was carried out in the NCP from 2016 to 2020. The COATS experiment adopted a "point-line-surface" spatial layout, obtaining both spatial-temporal profiles of the meteorological and environmental elements in the ABL and the turbulent transport data of fine particulate matter (PM2.5) in winter and summer. The research achievements are as follows. The spatial-temporal distribution characteristics of the ABL structure and PM2.5 concentrations in the NCP were determined. The typical thermal structure of persistent heavy haze events and the pollutant removal mechanism by low-level jets were revealed. It was determined that the spatial structure of the ABL adjusted by the Taihang Mountains is responsible for the heterogeneous distribution of haze pollution in the NCP, and that mountain-induced vertical circulations can promote the formation of elevated pollution layers. The restraints of the atmospheric internal boundaries on horizontal diffusion of pollutants were emphasized. The contribution of the ABL to haze pollution in winter and summer was qualitatively compared and quantitatively estimated. The turbulent transport nature behind the relationship between the atmospheric boundary layer height (ABLH) and surface PM2.5 concentrations was analyzed. The concept of "aerosol accumulation layer" was defined, and the applicability of the material method in determining ABLH was clarified. A measurement system for obtaining the turbulent flux of PM2.5 concentrations was developed, and the turbulence characteristics of PM2.5 concentrations were demonstrated. The COATS experiment is of great theoretical significance for thoroughly understanding the physical mechanisms of the ABL during haze pollution and filling the knowledge gap on the impacts of the ABL three-dimensional structure on haze pollution. The results of this study are conducive to the improvement and development of ABL parameterization schemes and serve as a scientific basis for formulating regional pollution prevention and control measures. [ABSTRACT FROM AUTHOR]

A novel sparse LMS algorithm for the sparse system identification is proposed to reduce the complexity of the existing algorithms. The proposed algorithm discards W(n) when the value of the current weight vector is within a certain range. The algorithm also optimizes the iterative update equation by using only the product term to calculate the value of W(n+1). The hardware implementation shows that the total logic elements number of the proposed algorithm is 60.06% less than the latest l0-ILMS algorithm, while the performance is nearly the same. [ABSTRACT FROM AUTHOR]

Background: Paediatric-onset idiopathic/hereditary pulmonary arterial hypertension (IPAH/HPAH) is partially linked to genetic factors that may also affect treatment response and outcome. The relation between clinical characteristics and pathogenicity of gene variants in childhood IPAH/HPAH is still not well understood. Methods: We retrospectively analyzed IPAH/HPAH paediatric patients aged between 3 months and 18 years under follow-up at a large tertiary referral center. Whole-exome sequencing focused on PAH high-risk genes was performed in all patients. Pathogenicity grading of gene variant sites was assessed using ClinVar and population frequencies. The association between gene variants and death was studied using Cox proportional multivariate models. Results: Overall, 129 patients (54.3% females; 91.5% on PAH therapy) with a median age at diagnosis of 6.8 (IQR 3.4–10.7) years were included. A relevant PAH gene variant was detected in 95 patients (73.6%). The most common variants were in the BMPR2 (n = 43, 3%) gene. Over a median follow-up period of 27.6 months, 26 children died. The presence of a likely pathogenic genetic variant was significantly associated with survival (HR: 3.56, p = 0.005) on multivariable Cox analysis. The number of PAH-specific drugs at presentation was associated with better survival in the cohort with pathogenic variants (p = 0.02). Conclusions: Pathogenic/likely pathogenic genetic variants are prevalent in children with PAH and are related to a worse prognosis irrespective of other recognized risk factors in this population. Combination PAH therapy was associated with superior prognosis in children with pathogenic variants or BMPR2 variants. Therefore, proactive medical therapy should be employed in this population. [ABSTRACT FROM AUTHOR]

The large-aperture scintillometer (LAS) has been widely used in the estimation of sensible heat fluxes (H) on various land surfaces, but they are seldom used in deserts with dune topographies. Here, an LAS was deployed in the Taklimakan Desert for about two weeks to investigate its ability to estimate H over the dune topography in the desert and its impact on the surface energy balance. We estimated the LAS and eddy covariance (EC) fluxes using standard methods, as well as H directly calculated by the EC system via a spectral fitting method. We conducted a series of sensitivity tests to investigate the scintillometer-based heat flux estimation uncertainties by considering surface and meteorological parameters and surface-layer similarity structure functions. In addition, the imbalance problem in the surface energy budget was examined using the measurements. Desert areas are different from other land surfaces in that they are characterized by a high sensible heat flux. It was found that the LAS had good performance in the Taklimakan Desert and could capture more low-frequency turbulence. Also, the spectral fitting method used on the data obtained with the EC system could capture more low-frequency turbulence compared to the direct calculations made by the EC system. The H values obtained by the LAS (HLAS) were overestimated by about 11.6% relative to those measured by the EC system (HEC), and the HEC values obtained by the spectral fitting method were overestimated by about 12.1% relative to them being directly calculated by the EC system. Large and dispersed values of HLAS/HEC appeared with smaller values of rwT (the correlation coefficient) (i.e., 0.1–0.3), and the large ratio of HLAS/HEC might be related to a predominance of low-frequency motions in stable stratification. However, the H values estimated by the LAS had great uncertainties in the case of high wind speeds and weak winds at night. The main source of uncertainty in the estimation of H by the LAS was the use of the different surface parameters (e.g., the Bowen ratio, roughness length, and LAS effective height) and the different forms of fT(ζ) from the Monin–Obukhov similarity theory (MOST). Different from the flat surfaces in desert areas, dune topography affected the use of fT(ζ) of MOST by 37%. MOST can improve the estimation of H, and then improve the calculation of the surface energy balance ratio (EBR). [ABSTRACT FROM AUTHOR]

In this paper, a novel multi-ring blank holder technique is developed. The blank holding force (BHF) provided by each ring can be independently and effectively applied on all radial regions. The principles and advantages of the multi-ring technique are first explained and analyzed by theoretical derivation, stress analysis, and forming simulation. The results indicate that the distribution of the blank holder force per unit area (FUA) applied by the new blank holder technique is more reasonable than using the conventional single blank holder and can better suppress the wrinkles. Finally, the effectiveness of the multi-ring blank holder technique is proven by a deep drawing experiment of the 08Al plate. It was verified that due to the reasonable FUA distribution, the use of the blank holder technique can suppress the wrinkles on the flange very well. [ABSTRACT FROM AUTHOR]

Aim: To define the clinical characteristics, hemodynamics, and adverse events for pediatric patients with pulmonary arterial hypertension (PAH) undergoing right heart catheterization (RHC). Methods: The large referral single center data of 591 diagnostic RHC procedures performed between 2005 and 2020 on pediatric PAH patients was retrospectively collected and analyzed. Results: A total of 591 RHC procedures performed on 469 patients with congenital heart disease (CHD)-PAH (median age 8.8 years, 7.9% New York Heart Association (NYHA) class > II, 1.5% with syncope) and 122 patients with idiopathic PAH (median age of 9.0 years, 27.0% NYHA class > II, 27.0% with syncope) were included. Of those, 373 (63.1%) procedures were performed under general anesthesia. Eighteen patients (18/591, 3.0%) suffered adverse events (mainly pulmonary hypertensive crisis, PHC, n = 17) during the RHC procedure, including 14 idiopathic pulmonary arterial hypertension (IPAH) patients and 4 CHD-PAH patients, and one IPAH patient died in hospital 63 hours after RHC. The risk of developing PHC was significantly increased in patients with IPAH (OR = 14.02, 95%CI: 4.49–43.85, p < 0.001), atrial blood gas pH < 7.35 (OR = 12.504, 95%CI: 3.545–44.102, p < 0.001) and RAP > 14 mmHg (OR = 10.636, 95%CI: 3.668–30.847, p < 0.001). Conclusions: RHC is generally a low-risk procedure in pediatric patients with PAH. However, PHC occur in approximately 3% of patients. Therefore, RHC should be performed in a large, experienced referral pediatric cardiology center, especially in pediatric patients with IPAH requiring general anesthesia. [ABSTRACT FROM AUTHOR]

The deep convective boundary layer (CBL) in the Taklimakan Desert plays an important role in the climate system in East Asia. Based on the observation experiment and large‐eddy simulation, turbulent mechanisms for its formation were revealed in this study. This explained why the daily maximum CBL depth was independent of surface heating. In the late‐morning, there was a weak temperature inversion and a near‐neutral residual layer (RL) above the CBL. With the development of the CBL, stronger convection could penetrate the RL and even overshoot the top of the RL. The distinctive boundary‐layer process entrained free‐tropospheric air to warm the RL and then promoted the entrainment of the warmed air in the RL into the CBL. This extra energy supply effectively contributed to the growth of the CBL. With further positive feedback between the CBL and RL depths, a deeper CBL would form in consecutive fair‐weather conditions. Plain Language Summary: The atmospheric boundary layer controls the exchange of momentum, heat, and mass between the land surface and the free atmosphere. Contrary to the typical 1,000–2,000 m over land, the convective boundary layer (CBL) in the Taklimakan Desert can reach 5,000 m. By coupling with the Tibetan Plateau, the deep CBL becomes a key component of the climate system in East Asia. Traditionally, it is considered that intense surface heating is the primary reason for its formation, but our correlation analysis shows that surface heating can only maintain a CBL of ∼1,800 m. To understand the potential physical processes, we further modeled the development of the deep CBL and found that the presences of weak temperature inversion and near‐neutral residual layer (RL) above the CBL are crucial. The distinctive vertical structure leads to a unique boundary‐layer process, which entrains warm air from the higher level into the RL and further promotes the warmed air in the RL to be entrained into the CBL. The special energy supply is key to the formation of deep CBL. The results are helpful to understand the land‐atmosphere interactions under climate change and improve the numerical weather prediction in northern China and even East Asia. Key Points: The convective boundary layer (CBL) in the Taklimakan Desert commonly developed to 3,000 m and even reached over 5,000 m in summerStrongly penetrative convection could overshoot the top of near‐neutral residual layer (RL) and entrain free‐tropospheric air into the RLThe warmed RL strengthened the entrainment heating, which supplied extra energy for the further development of deep CBL [ABSTRACT FROM AUTHOR]

A new cogeneration system coupled with an absorption heat transformer (AHT) to recover condensed waste heat of a direct-air-cooling coal-fired power plant is presented to reduce the energy grade mismatch between the energy-supplying side and energy-receiving side of the existing waste heat recovery system with an absorption heat pump (AHP). Thermodynamic models of two cogeneration systems, namely, the AHP and heater of the heating network (AHP-HHN) and the absorption heat transformer and heater of the heating network (AHT-HHN), are established. The performance analysis and comparison of two cogeneration systems, focusing on a 600 MW direct air-cooling coal-fired power plant, are carried out from the aspects of energy and exergy utilization. The output power and waste heat recovery ratio are increased by 14.81 MW and 51.56% in the AHT-HHN at 75% THA (turbine heat acceptance) load with a 230,000 kW heating load. The standard coal consumption rate and total exergy loss are decreased by 8.86 g/kWh and 45.54 MW. The total energy efficiency and exergy efficiency are improved by 1.33% and 1.31%, respectively. Moreover, the larger the heating load, the greater the performance difference. The new waste heat recovery scheme can further improve the energy cascade utilization level. [ABSTRACT FROM AUTHOR]

• H 2 fumigation significantly prolong the shelf life of Lanzhou lily bulbs. • Conjoint analysis revealed that H 2 fumigation might involve antioxidant pathways. • H 2 fumigation inhibited the degradation of AsA and GSH in Lanzhou lily scales. • H 2 fumigation enhanced CAT, SOD, APX, GR and POD activities in Lanzhou lily scales. • H 2 fumigation improved both enzymatic and non-enzymatic antioxidant capacity. Molecular hydrogen (H 2), as a gas regulator, gained research momentum in agricultural sciences owing to its multiple functions in plants, including post-harvest senescence and stress tolerance. However, there are few studies on the role of H 2 fumigation on the post-harvest storage period in bulb crops. In this study, the preservation capacity of Lanzhou lily (Lilium davidii var. unicolor) scales was evaluated in the presence of H 2 fumigation, and the changes in antioxidant capacity were also explored. Bulbs of Lanzhou lily were continuously fumigated with H 2 for 3 d at room temperature, and then stored in foam box (23 ± 2 ℃) at 60 % relative humidity. The results observed that H 2 fumigation prominently extended the storge life and mitigated the water loss in Lanzhou lily scales. Joint transcriptome and metabolome revealed that differential genes (DEGs) and differential metabolites (DAMs) differently enriched in ascorbate and aldarate and glutathione metabolism pathways. Additionally, the relative conductivity and malondialdehyde (MDA)content were remarkably reduced and damage of membrane lipid peroxidation was alleviated by H 2 fumigation. Meanwhile, the catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (APX) and superoxide dismutase (SOD) were significantly enhanced and non-enzymatic antioxidants, glutathione (GSH), and ascorbic acid (AsA) content prominently accumulated by H 2 fumigation. Thus, H 2 fumigation might prolong the shelf life in Lanzhou lily by improving its antioxidant capacity. These findings provide a potential theoretical foundation for perishable vegetable storage. [ABSTRACT FROM AUTHOR]

A new electro-permanent magnet combined blank holder technique has been developed by using permanent magnetic force to supply the blank holding force (BHF) for sheet metal deep drawing. In this work, the workability of the designed magnetic circuits was simulated and tested. A series of numerical simulations and experiments have also demonstrated its ability to overcome temperature rise and provide sufficient magnetic force. The advantages and availability of the combined blank holder technique were expatiated by theoretical derivation, and analyzed by FE stress analysis. The feasibility and effectiveness of the new blank holder method have been proven by a series of experiments for deep drawing a workpiece of 08Al with a diameter of 220 mm. With the segmental blank holder, the flange wrinkling is demonstrated to be suppressed well than using the single blank holder. Also, experimental results corroborated that current is only instantaneously imposed when switching magnetic force state, and not at other times. [ABSTRACT FROM AUTHOR]

Spherical gravitational wave is strictly forbidden in vacuum space in frame of general relativity by the Birkhoff theorem. We prove that spherical gravitational waves do exist in non-linear massive gravity, and find the exact solution with a special singular reference metric. Further more, we find exact gravitational wave solution with a singular string by meticulous studies of familiar equation, in which the horizon becomes non-compact. We analyze the properties of the congruence of graviton rays of these wave solution. We clarify subtle points of dispersion relation, velocity and mass of graviton in massive gravity with linear perturbations. We find that the graviton ray can be null in massive gravity by considering full back reaction of the massive gravitational waves to the metric. We demonstrate that massive gravity has deep and fundamental discrepancy from general relativity, for whatever a tiny mass of the graviton. [ABSTRACT FROM AUTHOR]

We take the establishment of cross-border e-commerce comprehensive pilot zones as the quasi-natural experiment, based on China’s General Administration of Customs Database, China Customs Online Inquiry Platform, ‘Cross-Border E-Commerce Retail Import Commodity List’ and other data. By employing the staggered DID method, this paper systematically investigates the potential of cross-border e-commerce to enhance the quality of imported products. The research findings reveal the following: Since the introduction of the cross-border e-commerce comprehensive pilot zones, there has been a significant improvement in the quality of imported products in China. These effects, however, vary across different product types and regions, suggesting heterogeneous impacts. The cross-border e-commerce comprehensive pilot zones have facilitated the development of import trade in China through three main avenues: reducing search costs, resolving financing challenges, and lowering tariffs. These measures have collectively contributed to the reduction of trade costs. [ABSTRACT FROM AUTHOR]

Through comparing the distribution of blank holder force (BHF) and stress-strain curve along the radial direction, there has been good forming capability and adaptability in deep drawing with the electro-permanent magnetic (EPM) blank holder (EPMBH) technique. However, whether the BHF technique is applicable for non-ferromagnetic materials has yet to be researched. In the paper, taking 08-Al steel and H62 copper plates as examples, the drawability of ferromagnetic and non-ferromagnetic sheets with EPMBH is investigated. Moreover, a series of confirmatory tests were carried out based on numerical analysis. It found that similar to the deep drawing with ferromagnetic slab, there is slight attenuation on the holding effect for non-ferromagnetic sheets, and the effect of gap on the magnetic attraction caused by the magnetic properties of the plate first increases sharply and then slowly decreases, while its possible failure modes are also wrinkling and rupture due to insufficient BHF and excessive drawing height, respectively. In the experiment, flawless deep-drawing workpieces can be obtained with EPMBH, indicating that EPMBH could meet the forming requirement for ferromagnet and non-ferromagnetic plates and can be controllably adjusted through altering the excitation current of the EPMBH device. The experiment result shows that the optimal excitation current is 14 A for ferromagnetic steel plate and 13 A for non-ferromagnetic copper plate with the same diameter of 110 mm and thickness of 0.8 mm. [ABSTRACT FROM AUTHOR]

One usually defines the Brown–York energy for a 2-surface embedded in a space-like 3-slice as an integration of the mean curvature of the 2-surface isometrically embedded into the 3-slice, with a proper reference 3-space. We demonstrate that this naive definition is ill for stationary spacetimes. As an example, we investigate the Kerr–Newman spacetime in detail. We show that the naive definition of the Brown–York energy is not a component of the Brown–York boundary stress tensor, and thus deviates from the original idea of Brown and York. Furthermore, we present the exact form of the Brown–York energy for the Kerr–Newman spacetime with proper reference. [ABSTRACT FROM AUTHOR]

BACKGROUND: The authors found a striking similarity between the qi and blood theory and nerve repair of spinal cord injury in terms of improving blood-oxygen microenvironment in tissues. The hypothesis is that electroacupuncture can improve the blood-oxygen microenvironment of the spinal cord and promote nerve regeneration by regulating hypoxia-inducible factor 1 a and vascular endothelial growth factor signal transduction. OBJECTIVE: To investigate the effect of electroacupuncture intervention on the expression of hypoxia-inducible factor 1a and vascular endothelial growth factor in injured segments of spinal cord injury rats. METHODS: Totally 120 Sprague-Dawley female rats were enrolled to make spinal cord injury models by clamping the spinal cord (20 seconds) using a microvascular clamp. Rat models were then randomly divided into three groups: Ashi point group, Stomach Meridian of Foot-Yangming group and blank control group, 40 rats in each group. Electroacupuncture at two Aishi points or at both sides of Futu and Zusanli points was started on the 3rd day after modeling. Each rat was scored on the Basso, Beattie and Bresnahan locomotor rating scale at 1, 2, 3, 4, and 5 weeks after intervention. Injured spinal cord specimens ware then taken and observed histomorphologically. Hypoxia-inducible factor-1a and vascular endothelial growth factor protein and mRNA expressions were detected using immunohistochemistry staining, real-time fluorescence quantitative PCR and western blot assay. The study protocol was approved by the Animal Ethic Committee of the First Affiliated Hospital of Guangxi University of Chinese Medicine in China (approval No. 201712001). RESULTS AND CONCLUSION: The lower limb function score, hypoxia-inducible factor-1a and vascular endothelial growth factor gene and protein expression in the two electroacupuncture intervention groups were significantly higher than those of the blank control group. The number of neurons in Ashi point and Stomach Meridian of Foot-Yangming groups was significantly higher than that of the blank control group with the lapse of intervention time. Electroacupuncture intervention can effectively improve the lower limb function score of spinal cord injury rats, increase the number of neurons, and up-regulate the mRNA and protein expression of hypoxia-inducible factor-1a and vascular endothelial growth factor, thus effectively promoting the neurological recovery of the spinal cord. [ABSTRACT FROM AUTHOR]

A novel blank holder technique based on electropermanent magnet (EPM) technology is proposed, in which independent loading of blank holding force (BHF) can be realized in sheet metal forming process. The magnetic force and the resulting BHF are applied by permanent magnets rather than electromagnets, and the current is only required at the moment of loading or unloading the BHF. The BHF is convenient in control, low in energy consumption, and without overheating problem using this technique. In this paper, an experimental setup consisting of magnetic cushion, die, punch, and other components is designed based on the characteristics of EPM and requirements of deep drawing process. The magnetic cushion including blank holder and magnetic pole units is used to generate magnetic force and realize loading and unloading of BHF. Then, magnetic field analyses of a pair of magnetic pole units and the designed cushion are carried out by FEM. Also, the coupling problem involving magnetic field and stress field is further analyzed and solved by means of theoretical method and FEM, and the BHF and the blank holding pressure on the sheet using the new technique can be obtained. The deformation of the designed setup is small, and the stiffness can satisfy the requirements. The deep drawing processes of cylindrical cup of 08Al sheet with 0.98 mm thickness are simulated by using conventional blank holder and the new technique, respectively, and there are small differences of the strain distributions of the drawn parts with the two techniques. The experiments of cylindrical cup deep drawing applied four different BHFs, respectively, are carried out using EPM bank holder technique. The results indicate that the BHF applied by the designed cushion is large enough for the deep drawing process of the selected sheet. [ABSTRACT FROM AUTHOR]

Electrocardiographic left ventricular hypertrophy (LVH) has been used to predict adverse outcomes in different clinical settings. This meta-analysis aimed to compare the prognostic value of different electrocardiographic criteria of LVH at baseline in hypertensive patients. A systematic literature search was conducted in PubMed and Embase databases until December 3, 2019. Cohort studies that reported the association of baseline electrocardiographic LVH (Sokolow-Lyon voltage, Cornell voltage or Cornell product) with all-cause mortality or major cardiovascular events in hypertensive patients were included. The prognostic value of LVH was expressed by the risk ratio (RR) with 95% confidence interval (CI). Nine studies involving 41 870 hypertensive patients were identified. Comparison with those with and without LVH patients indicated that the pooled RR value of all-cause mortality was 1.30 (95% CI 1.01-1.66) for the Sokolow-Lyon voltage criteria, 1.33 (95% CI 1.20-1.47) for the Cornell voltage criteria, and 1.31 (95% CI 0.97-1.78) for the Cornell product criteria. In addition, the pooled RR of major cardiovascular events was 1.53 (95% CI 1.27-1.86) for the Sokolow-Lyon criteria and 1.46 (95% CI 1.22-1.76) for the Cornell voltage criteria, respectively. This meta-analysis suggests that different electrocardiographic criteria for detecting LVH at baseline differ in prediction of all-cause mortality in patients with hypertension. LVH detected by the Cornell voltage and Sokolow-Lyon criteria can independently predict the major cardiovascular events in hypertensive patients. [ABSTRACT FROM AUTHOR]

In this study, the characteristics of turbulence transport and intermittency and the evolutionary mechanisms were studied in different pollution stages of heavy haze weather from December 2016 to January 2017 in the Beijing area using the method developed by Ren et al. (2019) as the automatic identification of atmospheric spectral gaps and the reconstruction of atmospheric turbulence sequences. The results reveal that turbulence intermittency is the strongest in the cumulative stage (CS) of heavy haze weather, followed by in the transport stage (TS), and it is the weakest in the dissipation stage (DS). During the development and accumulation of haze pollution, buoyancy contributes negatively to turbulent kinetic energy (TKE), and horizontal wind speed is low. The classical turbulent motion is often affected by submesoscale motion. As a result, the calculation results of turbulence parameters are affected by submesoscale motion, which causes intensified turbulence intermittency. During the dissipation of pollution, the downward momentum transfer induced by low-level jets provides kinetic energy for turbulent motion in the near surface layer. The turbulent mixing effect is enhanced, and intermittency is weakened. Due to the intermittency of atmospheric turbulence, turbulence parameters calculated from the original fluctuation of meteorological elements may be overestimated. The overestimation of turbulence parameters in the CS is the strongest, followed by the TS, and the DS is the weakest. The overestimation of turbulent fluxes results in an overestimation of atmospheric dissipation capability that may cause an underestimation of pollutant concentrations in the numerical simulations of air quality. [ABSTRACT FROM AUTHOR]

Sending broadcast messages is an efficient means of communicating in emergency situations, especially during serious disasters. This paper focuses on the digital audio broadcast (DAB) system. First, several new techniques are reported to enhance the emergency warning message (EWM) receiving and display functionalities for both personal and public DAB terminals. Then, a novel bidirectional communication method between two DAB transmitters is proposed, to enable the communication to and from the disaster area and the outside. Experiments show that the EWM can be correctly sent to the intended DAB terminals within 0.2–3 s, and the existing public light emitting diode screens can be expanded as DAB EWM terminals without affecting their normal functions. The bidirectional multimedia communication between two DAB transmitters is also successfully demonstrated. The proposed techniques expand upon the DAB’s existing functionality, and can benefit more people during emergencies. [ABSTRACT FROM AUTHOR]

The understanding of mangrove forest structure and dynamics at species level is essential for mangrove conservation and management. To classify mangrove species, remote-sensing technologies provide a better way with high spatial resolution image. The spatial structure is usually viewed as effective complementary information for classification. However, it is still a challenge to design handcrafted features for mangrove species due to their non-structure texture. To leverage the advantage of convolutional neural networks (CNNs) in abstract feature exploration, a small patch-based CNN is proposed to overcome the requirement of fixed and large input which limits the applicability of CNNs to fringe mangrove forests. The function of down-sampling technology was substantially reduced to make deeper network for small input in our work. Meanwhile, the inception structure is used to exploit the multi-scale features of mangrove forests. Furthermore, the network is optimized with lesser convolution kernels and a single fully connected layer to reduce overfitting via reducing the training parameters. Compared to the features of grey level co-occurrence matrix with support vector machine, our proposed CNN shows better performance in classification accuracy. Moreover, the differences between mangrove species can be perceptive via CNN visualization, which offers better understanding of mangrove forests. [ABSTRACT FROM AUTHOR]

Abstract We find a new property in W 2 -conformal gravity in spherical symmetry. We demonstrate that the charge of the electromagnetic field varies with respect to the partial scaling symmetry (conformal transformations in subspaces of a spacetime) in the conformal gravity. We find that the electric and magnetic charges can vanish or appear via partial conformal transformations for the on-shell configurations in the conformal gravity. We find a solution of a Yang–Mills SU(2)-charged black hole in the conformal gravity, and further demonstrate that the SU(2) charge has similar properties with electromagnetic magnetic charges in the conformal gravity. We demonstrate how to imbed the electromagnetic and Yang–Mills SU(2) gauge field into the conformal gravity via such a symmetry. We make a brief discussion about the possibility to extend this argument to the Einstein gravity. [ABSTRACT FROM AUTHOR]

Highlights • Proposed a new method to achieve waste heat recovery and water saving. • Verified that waste heat recovery can offset property reduction of air-cooled mode. • Both energy and exergy analysis are conducted to identify advantages of new system. Abstract A new air-cooled gas-steam combined cycle cogeneration system with absorption heat pump for recovering waste heat from exhausted steam of the steam turbine to achieve double effects of waste heat recovery and water saving is proposed based on a conventional water-cooled gas-steam combined cycle cogeneration system in the paper. The property criteria variation is analyzed before and after modification. In addition, the exergy analyses of primary equipments are carried out based upon the exergy analysis theory. The results demonstrate that the net generating power is approximately increased by 11,082 kW, equivalent coal consumption is reduced by 2.71 g/kWh, the net overall thermal efficiency is improved by 0.91% with 334,245 kW heating load at 100% load of the gas turbine in the modified system. Besides, the overall exergy loss is decreased by 6448 kW and exergy efficiency is improved by 0.98%. The overall property of the whole system is improved. The results show that the property reduction caused by air-cooling modification can be made up by the property improvement due to waste heat recovery. Moreover, the cooling circulating water can be saved by 1196.34 kg/s. The presented measure can not only improve performance of the system but also simultaneously achieve energy and water saving on the premise of satisfying user needs, which has a wide application potential in the water-shortage regions. [ABSTRACT FROM AUTHOR]

This study derived analytical solutions for wave diffraction by a semi-infinite breakwater or collinear, symmetrical, and asymmetrical double breakwaters with partial reflection. The diagrams of the diffraction coefficient distribution for double breakwaters are presented. The analytical results of this study are compared to those of other analytical diffraction solutions in detail, and the effects of the reflection coefficient and layout of the breakwaters on the wave heights are analyzed. The results reveal that the reflection coefficient of the breakwaters mainly affects the wave heights in the reflection area in front of the breakwaters, and somewhat affects the wave heights in the shielding area behind the breakwaters. The reflection coefficients' effect on the shielding area is closely related to the breakwater layout. In addition, the layouts of asymmetrically diverging double breakwaters are closely related to their shielding effects. The main factors that affect the wave heights in the shielding area are the inclination angles of breakwaters, the ratio of gap width to wavelength and the position of right breakwater head. The impact of those factors is not independent, but interrelated; the above factors, rather than just one of them, should be considered comprehensively when the breakwater layout is designed. [ABSTRACT FROM AUTHOR]

This paper constructs a unique dataset of Chinese firm-level bilateral cross-border e-commerce exports using the back-end online logistics database of a famous Chinese logistics platform to study the impact of destination country’s institutional quality on Chinese cross-border e-commerce export. Our results show that the institutional quality of destination countries significantly boosts China’s cross-border e-commerce exports. Institutional quality has a more significant effect on the extensive margin than the intensive margin. Mechanism analysis shows that institutional quality significantly stimulates export entry, export survival, and continuous exports. Furthermore, destination country’s institutional quality has a greater impact on cross-border e-commerce export than on traditional export. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the potential roles of TG-interacting factor (TGIF) in benzo(a)pyrene (BaP)-induced migration, invasion, and metastasis of lung adenocarcinoma cells. Cells were treated with different concentrations of BaP. MTT assays were used to measure cell proliferation. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunoblots were applied to measure the TGIF expression. A dual-luciferase reporter gene assay was performed to assess the effects of BaP on TGIF promoter-driven reporter gene expression. Wound-healing, transwell, and tail vein metastasis assays were performed to evaluate migratory, invasive, and metastatic capacity. Our results showed that BaP treatment increased the expression of TGIF mRNA and protein. Additionally, BaP treatment enhanced TGIF promoter-driven reporter gene expression. We observed that BaP treatment promoted the migration, invasion, and metastasis of H157 cells, which could be blocked by silencing TGIF. The expression of TGIF mRNA was significantly higher in metastatic lung adenocarcinoma samples than in non-metastatic lung adenocarcinoma samples, and higher levels of TGIF mRNA expression were observed in metastatic lung adenocarcinoma samples from patients with a smoking history than in those from patients with a non-smoking history. Our findings suggest that BaP treatment promotes the migration, invasion, and metastasis of human lung adenocarcinoma cells by upregulating TGIF. [ABSTRACT FROM AUTHOR]

This paper identifies the determinants of China's bilateral trade balance using a new measure based on international input-output data, the so-called ‘trade in value-added’ (TiVA), which can prevent double counting in the estimation of bilateral trade balance. Our results show that using a measure based on gross exports, rather than TiVA, causes relatively large overestimation of the impact of the RMB exchange rate on China's bilateral trade balance. This overestimation is mainly because that the increasing production of exports may require increasing intermediate imports as a consequence of international fragmentation of production in global value chains. In addition, our results also show that the impact of FDI inflows on China's bilateral trade balances depends on the position and role of China and its trading partners in GVCs. [ABSTRACT FROM AUTHOR]

Human activities have transformed natural land surface to artificial constructions, which causes the urban regions increasingly expanding. Urban development can be reflected by the dynamic changes of impervious surfaces, which can be assessed using time-series satellite data. The Pearl River Delta (PRD) metropolitan has witnessed fast urban development over past decades. Even though many studied have focused on monitoring the urbanization of megacities, there is still a lack of comprehensive understanding about the long-term annual dynamics of urban impervious surfaces at city level in PRD. In this study, MOD09A1 (MODIS Surface Reflectance 8 Day L3 Global 500 m) products were chosen to assess the annual dynamics of impervious surface at city level in PRD. Temporal filtering was utilized to improve the accuracy of the impervious surface estimation. Moreover, a new index, normalized difference urban development index (NDUDI) was proposed to investigate relative development of impervious surface in PRD. Additionally, the economy factor, Gross Domestic Product (GDP) was introduced to reveal the correlation with the impervious surfaces. Results demonstrated that the overall accuracy for impervious surface extraction was about 91.00-94.00%. The impervious surfaces area in PRD dramatically increased from 6000 km2 to 115,840 km2 in the past 16 years. Guangzhou and Foshan have the fastest developing speed, while Dongguan, Shenzhen and Foshan sacrificed much more lands to the construction of PRD than other cities. Besides, areas of impervious surface per city show very good correlations with GDP in city of Guangzhou, Huizhou, Foshan, Zhongshan, Hong Kong and Zhuhai-Macau. The scatter plot between NDUDI and GDP data display different clustering pattern between different cities. [ABSTRACT FROM AUTHOR]

Urban impervious surfaces have been recognized as a significant indicator for various environmental and socio-economic studies. There is an increasingly urgent demand for timely and accurate monitoring of the impervious surfaces with satellite technology from local to global scales. In the past decades, optical remote sensing has been widely employed for this task with various techniques. However, there are still a range of challenges, e.g. handling cloud contamination on optical data. Therefore, the Synthetic Aperture Radar (SAR) was introduced for the challenging task because it is uniquely all-time- and all-weather-capable. Nevertheless, with an increasing number of SAR data applied, the methodology used for impervious surfaces classification remains unchanged from the methods used for optical datasets. This shortcoming has prevented the community from fully exploring the potential of using SAR data for impervious surfaces classification. We proposed a new scheme that is comparable to the well-known and fundamental Vegetation-Impervious surface-Soil (V-I-S) model for mapping urban impervious surfaces. Three scenes of fully polarimetric Radsarsat-2 data for the cities of Shenzhen, Hong Kong and Macau were employed to test and validate the proposed methodology. Experimental results indicated that the overall accuracy and Kappa coefficient were 96.00% and 0.8808 in Shenzhen, 93.87% and 0.8307 in Hong Kong and 97.48% and 0.9354 in Macau, indicating the applicability and great potential of the new scheme for impervious surfaces classification using polarimetric SAR data. Comparison with the traditional scheme indicated that this new scheme was able to improve the overall accuracy by up to 4.6% and Kappa coefficient by up to 0.18. [ABSTRACT FROM AUTHOR]

Classification of mangrove species using satellite images is important for investigating the spatial distribution of mangroves at community and species levels on local, regional and global scales. Hence, studies of mangrove deforestation and reforestation are imperative to support the conservation of mangrove forests. However, accurate discrimination of mangrove species remains challenging due to many factors such as data resolution, species number and spectral confusion between species. In this study, three different combinations of datasets were designed fromWorldview-3 and Radarsat-2 data to classify four mangrove species, Kandelia obovate (KO), Avicennia marina (AM), Acanthus ilicifolius (AI) and Aegiceras corniculatum (AC). Then, the Rotation Forest (RoF) method was employed to classify the four mangrove species. Results indicated the benefits of dual polarimetric SAR data with an improvement of accuracy by 2-3%, which can be useful for more accurate large-scale mapping of mangrove species. Moreover, the difficulty of classifying different mangrove species, in order of increasing difficulty, was identified as KO < AM < AI < AC. Dual polarimetric SAR data are recognized to improve the classification of AI and AC species. Although this improvement is not remarkable, it is consistent for all three methods. The improvement can be particularly important for large-scale mapping of mangrove forest at the species level. These findings also provide useful guidance for future studies using multi-source satellite data for mangrove monitoring and conservation. [ABSTRACT FROM AUTHOR]

Time-varying mesh stiffness is one of the main internal excitation sources of gear dynamics. Accurate evaluation of gear mesh stiffness is crucial for gear dynamic analysis. This study is devoted to developing new models for spur gear mesh stiffness evaluation. Three models are proposed. The proposed model 1 can give very accurate mesh stiffness result but the gear bore surface must be assumed to be rigid. Enlighted by the proposed model 1, our research discovers that the angular deflection pattern of the gear bore surface of a pair of meshing gears under a constant torque basically follows a cosine curve. Based on this finding, two other models are proposed. The proposed model 2 evaluates gear mesh stiffness by using angular deflections at different circumferential angles of an end surface circle of the gear bore. The proposed model 3 requires using only the angular deflection at an arbitrary circumferential angle of an end surface circle of the gear bore but this model can only be used for a gear with the same tooth profile among all teeth. The proposed models are accurate in gear mesh stiffness evaluation and easy to use. Finite element analysis is used to validate the accuracy of the proposed models. [ABSTRACT FROM AUTHOR]

Integrating synthetic aperture radar (SAR) and optical data to improve urban land cover classification has been identified as a promising approach. However, which integration level is the most suitable remains unclear but important to many researchers and engineers. This study aimed to compare different integration levels for providing a scientific reference for a wide range of studies using optical and SAR data. SAR data from TerraSAR-X and ENVISAT ASAR in both WSM and IMP modes were used to be combined with optical data at pixel level, feature level and decision levels using four typical machine learning methods. The experimental results indicated that: 1) feature level that used both the original images and extracted features achieved a significant improvement of up to 10% compared to that using optical data alone; 2) different levels of fusion required different suitable methods depending on the data distribution and data resolution. For instance, support vector machine was the most stable at both the feature and decision levels, while random forest was suitable at the pixel level but not suitable at the decision level. 3) By examining the distribution of SAR features, some features (e.g., homogeneity) exhibited a close-to-normal distribution, explaining the improvement from the maximum likelihood method at the feature and decision levels. This indicated the benefits of using texture features from SAR data when being combined with optical data for land cover classification. Additionally, the research also shown that combining optical and SAR data does not guarantee improvement compared with using single data source for urban land cover classification, depending on the selection of appropriate fusion levels and fusion methods. [ABSTRACT FROM AUTHOR]

The document titled "Remote Sensing of Coastal Waters, Land Use/Cover, Lakes, Rivers, and Watersheds II" explores the significance of remote sensing in monitoring and analyzing coastal regions, land masses, lakes, rivers, and watersheds. It emphasizes the advancements in remote sensing technologies that have improved data collection and understanding of environmental changes. The document includes 22 research papers covering topics such as land cover change, ecological environments, wetlands and habitats, water quality, and marine disasters and environmental impacts. These papers offer valuable insights into the interactions between human and natural factors and aim to inform sustainable resource management efforts. The integration of artificial intelligence with remote sensing data further enhances accuracy and understanding. The authors express their gratitude to the contributors and reviewers for their valuable contributions to this Special Issue. [Extracted from the article]

Background: Myocardial infarction (MI) is a leading cardiovascular disease worldwide, with high mortality. Purpose: The study aimed to observe the mechanism of catalpol inhibiting apoptosis and autophagy in H9c2 cells after ischemia/reperfusion (I/R) injury. Materials and Methods: We grouped H9c2 cells into 4 groups: control, I/R injury, catalpol (I/R injury +1 ug/mL catalpol treatment), and wortmannin (I/R injury + 1 ug/mL catalpol +150 nM wortmannin treatment) groups. Both catalpol and wortmannin group cells were given drug treatment 30 min before I/R injury. At 2h post-I/R insult, we used flow cytometry for detecting cellular apoptosis and reactive oxygen species (ROS) levels. We identified p-PI3K, p-Akt, PI3K, Akt, p53, Bcl-2, Caspase-3, Bax, beclin1, LC3II, and LC3I protein expression levels. Results: I/R significantly increased the apoptosis rate and ROS level of H9c2 cells, increased expression levels of p53, LC3II/LC3I, and Caspase-3, and decreased p-Akt/Akt, beclin1, Bcl-2/Bax, and p-PI3K/PI3K expression levels. Catalpol can reduce the expressions of p53, Caspase-3, and LC3II/LC3I (p < 0.5). Catalpol can increase the expression levels of Akt/ p-Akt, Bax/ Bcl-2, and beclin1. Also, it can inhibit apoptosis and autophagy levels of H9c2 cells (p < 0.5). Wortmannin, a PI3 K-specific inhibitor, was able partially to block the catalpol's and anti-autophagic and anti-apoptotic effects. Conclusion: Catalpol can inhibit apoptosis, reduces excessive autophagy, and alleviates the effects of myocardial ischemia-reperfusion through PI3K/Akt/p53 pathway. [ABSTRACT FROM AUTHOR]

The conformal gravity remarkably boosts our prehension of gravity theories. We find a series of dynamical solutions in the W 2 -conformal gravity, including generalized Schwarzschild–Friedmann–Robertson–Walker (GSFRW), charged generalized Schwarzschild–Friedmann–Robertson–Walker (CGSFRW), especially rotating Friedmann–Robertson–Walker (RFRW), charged rotating Friedmann–Robertson–Walker (CRFRW), and a dynamical cylindrically symmetric solutions. The RFRW, CRFRW and the dynamical cylindrically symmetric solutions are never found in the Einstein gravity and modified gravities. The GSFRW and CGSFRW solutions take different forms from the corresponding solutions in the Einstein gravity. [ABSTRACT FROM AUTHOR]

The characteristics of raindrop size distributions (DSDs) during a midlatitude continental squall line on 30 July 2014 in east China are studied, and the different life stages are observed by OTT second-generation Particle Size Velocity (Parsivel2) disdrometers at Chuzhou during the mature stage and Nanjing during the declining stage. The observed rainfall is classified into convective line, transition, and stratiform regions based on the structure of the radar reflectivity Z and rainfall intensity R. The results show that the DSD characteristics of the different precipitation types and different squall-line stages are very different. The convective center has the largest number concentration and quantity of large drops corresponding to the highest rain rate; the rain rates in the trailing edge and stratiform regions are similar, although a lower concentration of small drops is present in the latter. Between the two stages, the drop size and number concentration for the convective center decrease, although the leading edge during the declining stage has more numerous larger drops; the number concentration is similar in the stratiform rainfall, but the drops become much smaller. For the normalized distribution, the scaled spectra for the convective center are closer to an exponential distribution, and the μ value during the declining stage is larger than that during the mature stage for the stratiform region and similar during both stages for the convective center. The declining stage has a larger exponent b and smaller coefficient A in the Z- R relationship based on fits for the entire dataset. Moreover, the R( Z H, ZDR) estimator is more accurate than that when using the Z- R relation algorithm. [ABSTRACT FROM AUTHOR]

Impervious surface is an important environmental and socio-economic indicator for numerous urban studies. While a large number of researches have been conducted to estimate the area and distribution of impervious surface from satellite data, the accuracy for impervious surface estimation (ISE) is insufficient due to high diversity of urban land cover types. This study evaluated the use of panchromatic (PAN) data in very high resolution satellite image for improving the accuracy of ISE by various pan-sharpening approaches, with a further comprehensive analysis of its scale effects. Three benchmark pan-sharpening approaches, Gram-Schmidt (GS), PANSHARP and principal component analysis (PCA) were applied to WorldView-2 in three spots of Hong Kong. The on-screen digitization were carried out based on Google Map and the results were viewed as referenced impervious surfaces. The referenced impervious surfaces and the ISE results were then re-scaled to various spatial resolutions to obtain the percentage of impervious surfaces. The correlation coefficient (CC) and root mean square error (RMSE) were adopted as the quantitative indicator to assess the accuracy. The accuracy differences between three research areas were further illustrated by the average local variance (ALV) which was used for landscape pattern analysis. The experimental results suggested that 1) three research regions have various landscape patterns; 2) ISE accuracy extracted from pan-sharpened data was better than ISE from original multispectral (MS) data; and 3) this improvement has a noticeable scale effects with various resolutions. The improvement was reduced slightly as the resolution became coarser. [ABSTRACT FROM AUTHOR]

Heavy haze pollution events are closely related to the turbulent structure of the stable boundary layer (SBL). SBL can be divided into two regimes, weak(coupled) and strong(decoupled). The weak SBL conforms to the classical turbulent theory and couples with the surface and different heights, whereas the strong SBL does not conform and decouples. However, the thresholds between coupled and decoupled SBL have not been determined in haze pollution events. Five levels of turbulence observation data from two severe haze pollution cases observed at the 255 m meteorological tower in Tianjin were employed to address this dilemma. The first case was analyzed in detail, and the second case was used for verification. The occurrence frequency of SBL was approximately 50% during the two haze pollution cases. The wind speed thresholds distinguishing coupled and decoupled SBL are: 2.5 m s−1 at 40 m, 4.0 m s−1 at 80 m, and 5.0 m s−1 at 120 m. The decoupled SBLs accounted for >70% of SBLs in haze pollution events. The turbulent structures notably differed between coupled and decoupled SBL events. In a decoupled SBL, the scalar concentration at different heights was substantially higher, the strength and occurrence frequency of sub-mesoscale motion were larger, and turbulent barrier effects occurred. Moreover, there was an inverse gradient transport and a smaller spatiotemporal scale of turbulent eddies. Therefore, there was a weaker turbulent kinetic energy, flux, and turbulent correlation across the layers in the decoupled SBL. The results reveal the failure of Monin-Obukhov similarity theory and traditional turbulent energy spectrum theory in a decoupled SBL. Wind speed thresholds can be widely used in the severe haze pollution simulation. The results of this study also indicate that decoupled SBL requires further study and attention in haze pollution events to improve the accuracy of pollutant concentration forecasting. • U threshold for coupled and decoupled SBL was determined and related with height. • Decoupled SBLs account for >70% of SBLs in observed haze pollution events. • Weaker(stronger) turbulent transfer (barrier effect) occurred in decoupled SBL. • Weaker turbulent correlations across layers were observed in decoupled SBL. [ABSTRACT FROM AUTHOR]

Time-varying mesh stiffness is one of the main internal excitations of gear dynamics. With the growth of gear tooth fault, like pitting, cracking and spalling, the mesh stiffness amplitude changes and consequently the dynamic properties of the gear system change. This study is devoted to deriving equations of the mesh stiffness of a pair of external spur gears with tooth pitting. Different pitting severity levels are modeled. The influence of tooth pitting on the gear mesh stiffness is investigated. The relationship between pitting severity and mesh stiffness is established. The proposed method is validated to be effective in mesh stiffness evaluation by comparing with a finite element model. [ABSTRACT FROM AUTHOR]

A new cogeneration system which integrates a solar-assisted absorption heat pump (SAAHP) into a coal-fired power plant for waste heat recovery of exhausted steam from a steam turbine is presented to improve utilization efficiency of fossil fuels. This study compares the performances of three cogeneration systems which differ in their driving heat source of AHP in the heating system. The following cogeneration systems are considered: conventional cogeneration system (CCS), cogeneration system with AHP driven by extracted steam (CSAES) and cogeneration system with AHP driven by solar (CSAS). Compared with the CCS and CSAES, output power respectively increases by about 11.43 and 6.48 MW; coal consumption rate reduces by 26.27 and 14.29 g/kWh in the CSAS with 11529 kJ heating capacity at 100% THA (Turbine heat acceptance) condition. The integral thermal and exergy efficiency of the CSAS are 58.32% and 36.26%. Meanwhile, reduced coal consumption rate and increased power both increase with increasing heating capacity. It is found that thermal efficiency and exergy efficiency for solar energy utilization both increase with the increasing load. [ABSTRACT FROM AUTHOR]

Field observations of the atmospheric boundary layer were made over urban and suburban terrain in the Yangtze River Delta, China. A multiresolution decomposition was applied over three different types of terrain: flat homogeneous terrain, suburban terrain and urban terrain, with results indicating that, (1) the average scale contribution of u, v, w and $$T_{v}$$ had a similar variability with length scale for all these three sites respectively, and the dimensionless length scale corresponding to the maximum sensible heat flux contribution increased with the terrain complexity; (2) the length scale corresponding to the maximal average scale contribution for vertical wind velocity $$\lambda _w $$ was directly proportional to the roughness length $$z_{0}$$ in unstable conditions; and (3) the contributions of large-scale motions led to sensible heat fluxes determined with a large-aperture scintillomter being larger than those using the eddy-covariance method for the suburban case, whereas this phenomenon was not substantial for the urban case. [ABSTRACT FROM AUTHOR]