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This study used observed rainfall, ERA5 reanalysis, and CMIP6 model datasets to investigate the interdecadal variation and underlying mechanism of persistent heavy rainfall (PHR) over the Huaihe River Basin (HRB) in China during July–August, and to examine the role of the Atlantic Multidecadal Oscillation (AMO) in modulating such rainfall. The results indicate that PHR over the HRB exhibited a marked interdecadal variation. The interdecadal increase in PHR was found attributable primarily to interdecadal enhancement of ascending motion, which might have been due to external forcing by the AMO. The AMO can trigger upper-tropospheric mid–high-latitude Rossby wave trains that can lead to an upper-tropospheric anticyclone and a lower-tropospheric cyclone configuration over the HRB. Increased warm advection and greater transport of water vapor from lower latitudes, caused by enhanced southerlies in the middle–lower troposphere over the HRB, can also lead to enhanced ascending motion over the HRB. Meanwhile, an anomalous cyclone over northeastern China triggered by AMO can transport cold air from higher latitudes to the HRB, boosting convection and promoting the development and duration of PHR. By affecting sea surface temperature in the western North Pacific Ocean, the AMO can also indirectly cause a meridional teleconnection pattern in the lower troposphere, which increases the transport of water vapor to the HRB. Numerical model experiments can reproduce both the interdecadal variations in PHR and the mechanisms of the influence of the AMO on PHR, providing a reliable foundation for understanding and forecasting PHR over the HRB. [ABSTRACT FROM AUTHOR]

To improve the utilization of satellite-based data and promote their development, this analysis comprehensively evaluates the performance of GSMaP Near-real-time Gauge-adjusted Rainfall Product version 6 (GSMaP_GNRT6) data in depicting precipitation over China from 2001 to 2020 by comparing four precipitation indices—accumulated precipitation, number of rainy days and rainstorm days, and precipitation maxima—with daily precipitation data from 2419 stations across China on monthly and annual time scales. The results show that the GSMaP-GNRT6 data effectively capture the overall spatial pattern of the four precipitation indices, but biases in the spatial distribution of the number of rainy days from July to September and the precipitation maxima during the wintertime are evident. A general underestimation of GSMaP-GNRT6 data is observed in the average for China. The annual precipitation amount, the number of rainy days and rainstorm days, and the precipitation maxima based on the GSMaP-GNRT6 data are 17.6%, 35.5%, 31.6% and 11.8% below the station observations, respectively. The GSMaP-GNRT6 data better depict the precipitation in eastern China, with the errors almost halved. And obvious overestimation of the number of rainstorm days and precipitation maxima occurs in western China, reaching up to 60%. Regarding the accumulated precipitation, the number of rainstorm days and the precipitation maxima, the GSMaP-GNRT6 data show an almost consistent interannual variation and increasing trends that are consistent with the station observations. However, the magnitude of the increasing trend based on the GSMaP-GNRT6 data is larger, especially at the beginning of the 21st century. Conversely, a considerable discrepancy in the annual variation and an almost opposite trend can be observed in the number of rainy days between the GSMaP-GNRT6 data and the station observations. [ABSTRACT FROM AUTHOR]

Using the ERA5 reanalysis data and the Climate Feedback Response Analysis Method (CFRAM), we attribute the mechanism of summer upper-tropospheric temperature (UTT) variations in the South Asian summer monsoon (SASM) region to several external forcing and internal feedback processes. The summer UTT in the SASM region is dominated by two modes. The first empirical orthogonal function (EOF) mode (EOF1) is a monopolar warming pattern, and the second EOF mode (EOF2) shows a meridional dipole pattern. CFRAM results show that summer UTT anomalies are mainly attributed to cloud feedback and nonradiative processes of atmospheric dynamics (ATD) and surface-related processes. For EOF1, ocean heat storage and partial cloud feedback processes contribute most UTT anomalies over the Indian Ocean. The ATD increases the UTT over East Asia through the adiabatic warming caused by anomalous anticyclone in the upper troposphere. The formation of EOF2 is closely linked to the ATD, while the cloud process partially compensates for the excessive changes in UTT caused by the ATD. The South Asian high and its circulation in the midlatitude region are significantly enhanced. The anomalous anticyclone over northern East Asia along with the anomalous easterly wind on the south side of the South Asian high favors increased warm advection and adiabatic heating, contributing to the warming of UTT. Meanwhile, adiabatic cooling resulting from the atmospheric ascent in the middle and upper troposphere leads to UTT cooling over the Indian Ocean. The quantitative attribution of UTT has great implications for better understanding future SASM variation. Significance Statement: The purpose of this study is to understand the physical mechanisms of upper-tropospheric temperature (UTT) changes in the South Asian summer monsoon (SASM). Although previous studies have examined temperature variation from the perspective of atmospheric circulation, there has been limited investigation into the influence of various feedback processes. Our study reveals that the summer UTT in the SASM region is dominated by monopolar and meridional dipole modes. Utilizing a climate feedback–response analysis method, we attribute the UTT anomalies in the SASM region to the cloud feedback, oceanic heat storage, and atmospheric dynamics processes, and explore the physical mechanisms of their effects. These results have important implications for the better prediction of monsoon variability. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the positive influence and potential mechanism of Erianin on the recovery of brain cells following a traumatic brain injury (TBI). TBI rat models were prepared and treated with Erianin injection via tail vein. The assessment included evaluating the rats' levels of oxidative stress, inflammation, neuronal damage, mitochondrial damage, neuronal regeneration, transformation of pro-inflammatory microglial cells, activation status of the ERK signal pathway, and the functionality of their learning and memory. After administering Erianin, there was a suppression of oxidative stress, inflammation, nerve cell damage, and mitochondrial damage in the TBI rats. Additionally, there was an increase in neuronal regeneration in the cortex and hippocampus, inhibition of pro-inflammatory microglial cell transformation in the cortex, improvement in learning and memory function in TBI rats, and simultaneous inhibition of the activation of the ERK1/c-Jun signal pathway. The findings suggest that Erianin has the potential to reduce oxidative stress and inflammatory reaction in rats with TBI, safeguard nerve cells against apoptosis, stimulate the growth of new neural cells, ultimately enhancing the cognitive abilities and memory function of the rats. The inhibition of the ERK signaling pathway could be closely associated with these effects. [ABSTRACT FROM AUTHOR]

This study introduces two innovative methods in the research for use in vision-based tunnel inspection vehicles. First, the image-range stitching method is used to map the sequence images acquired by a camera onto a tunnel layout map. This method reduces the tunnel image-stitching problem to the appropriate parameters, thus solving the problem of mapping equations, ranging from camera pixels to the tunnel layout map. The parameters are obtained using a laser scanner. Secondly, traditional label-based deep learning solely perceives the consistency between pixels and semantically labeled samples, making it challenging to effectively address issues with uncertainty and multiplicity. Consequently, we introduce a method that employs a bidirectional heuristic search approach, utilizing randomly generated seed pixels as hints to locate targets that concurrently appear in both the image and the image semantic generation model. The results reveal the potential for cooperation between laser-scanning and camera-imaging technologies and point out a novel approach of crack detection that appears to be more focused on semantic understanding. [ABSTRACT FROM AUTHOR]

• A laser differential imaging measurement model for immersed tunnel alignment is proposed. • The calibration model is given,and the measurement system is designed. • An underwater laser spot center extraction method is proposed. • Precision and repeatability assessment experiments are carried out, and are far better than the requirements. The precision of underwater alignment for tunnel elements directly impacts the closure state of immersed tunnels. The current global navigation satellite system measurement tower method provides centimeter-level precision; however, this is insufficient due to the tower deformation at great water depths, which fails to meet alignment requirements. In this study, a novel immersed tunnel alignment measurement method using laser differential imaging is developed. A unique sensor layout is designed to measure the axial angle and distance between tunnel elements. The system design is implemented, and its laser data processing scheme is optimized to improve performance base on this sensor layout. The experimental results demonstrate that the accuracy of underwater laser spot extraction is better than 1.16 pixels, and the precision of axial angle and axial distance alignment measurements is better than 25″ and 1.6 mm, with repeatability precision exceeding 10.55″ and 0.53 mm. The laser-based alignment measurement method is not affected by the depth of water, satisfying the required precision of immersed tunnel alignment. These results can be applied to future immersed tunnel installations without measuring towers, providing a novel method for achieving automated and unmanned intelligent construction of immersed tunnels. [ABSTRACT FROM AUTHOR]

This study investigates dynamic and thermodynamic components of moisture flux convergence in Southwest China (SW-MFC) and their underlying physical mechanisms during early and late summer. Using precipitation observation and CRA-40 reanalysis datasets from 1979 to 2023, the results show that both dynamic and thermodynamic processes modulate the SW-MFC in early summer (May-June), with dynamics playing a pivotal role. In contrast, the precipitation anomaly in late summer (July-August) is predominantly driven by the dynamic factors. Meanwhile, the large-scale circulation over the northern Indian Peninsula significantly modulates the SW-MFC. In early summer, anomalous convection around the Maritime Continent with the tripole sea surface temperature (SST) mode in the tropical Indo-Pacific can trigger the formation of “double ring” vertical zonal circulation cells. A large-scale westerly anomaly at the lower troposphere over the northern Arabian Sea foster cyclone strengthening over the northern Indian Peninsula, enhancing southerly moisture transport and increasing precipitation over Southwest China. During the late summer, large-scale dipole SST pattern between the subtropical central-eastern Pacific and the Indo-Pacific warm pool generates significant easterly anomalies towards the Maritime Continent. The SST gradient stimulates an extensive anticyclonic shear zone over the western equatorial Pacific, with an intensified low-pressure zone to its north. This atmospheric pattern over Southwest China and Indian Peninsula can form a vertical circulation circle that largely intensifies widespread precipitation. Numerical model experiments can reproduce the mechanisms of tropical Indo-Pacific joint effects on the Southwest precipitation in both early and late summer, providing a theoretical basis for understanding and forecasting summer precipitation over Southwest China. [ABSTRACT FROM AUTHOR]

As the only natural satellite of the Earth, the Moon provides vital location resources and supportive environment for Earth observations, and the Moon-based Earth observation (MEO) has unparalleled advantages in global climate change and large-scale phenomena. The ocean plays an important role in regulating climate and global water and carbon cycle. With an attempt to explore the feasibility of MEO-based marine environment monitoring, this study aimed to investigate the observing geometry and revisiting frequency of the MEO-based ocean color remote sensing and further to explore its quantitative application potentials. Results showed that MEO-based ocean color remote sensing, capturing the Earth on an hourly basis, could observe most part of the ocean for over five times per day; however, both solar zenith angle and view zenith angle were high at high-latitude regions; atmospheric reflectance accounted for most of sensor-measured signal, especially at high solar and view zenith angle, while surface-reflected glint reflectance was also notable at low solar zenith angle; and the remote sensing reflectance retrieved from MEO-based ocean color remote sensing could be used for chlorophyll retrieval. In further studies, more efforts should be paid on how to accurately retrieve remote sensing reflectance at high solar and view zenith angle, which would improve the application capability of MEO for polar regions. Overall, this study demonstrated the great potentials of MEO-based ocean color remote sensing, and MEO would be a new observing perspective and long-term consistent data source for marine environment monitoring. [ABSTRACT FROM AUTHOR]

Extreme cold events (ECEs) on the Tibetan Plateau (TP) exert serious impacts on agriculture and animal husbandry and are important drivers of ecological and environmental changes. We investigate the temporal and spatial characteristics of the ECEs on the TP and the possible effects of Arctic sea ice. The daily observed minimum air temperature at 73 meteorological stations on the TP during 1980–2018 and the BCC_AGCM3_MR model are used. Our results show that the main mode of winter ECEs over the TP exhibits the same spatial variation and interannual variability across the whole region and is affected by two wave trains originating from the Arctic. The southern wave train is controlled by the sea ice in the Beaufort Sea. It initiates in the Norwegian Sea, and then passes through the North Atlantic Ocean, the Arabian Sea, and the Bay of Bengal along the subtropical westerly jet stream. It enters the TP from the south and brings warm, humid air from the oceans. By contrast, the northern wave train is controlled by the sea ice in the Laptev Sea. It originates from the Barents and Kara seas, passes through Lake Baikal, and enters the TP from the north, bringing dry and cold air. A decrease in the sea ice in the Beaufort Sea causes positive potential height anomalies in the Arctic. This change enhances the pressure gradient between the Artic and the mid-latitudes, leading to westerly winds in the northern TP, which block the intrusion of cold air into the south. By contrast, a decrease in the sea ice in the Laptev Sea causes negative potential height anomalies in the Artic. This change reduces the pressure gradient between the Artic and the mid-latitudes, leading to easterly winds to the north of the TP, which favors the southward intrusion of cold polar air. A continuous decrease in the amount of sea ice in the Beaufort Sea would reduce the frequency of ECEs over the TP and further aggravate TP warming in winter. [ABSTRACT FROM AUTHOR]

Flatness is an important parameter for the quality assessment of concrete floors. Traditional flatness inspection methods have problems with sparse sampling and low efficiency for large concrete floors. In this paper, a rapid flatness inspection method for large concrete floors based on a wheeled robot with an aided inertial navigation system (INS) is proposed. The robot realizes high precision relative to the three-dimensional profile measurement of concrete floors through fusion of INS, odometers and total station. The overall measurement of concrete floor flatness is realized through a certain density of profiles. The measurement performance of the proposed method has been tested in laboratory, and the effectivity is tested in the flatness inspection of the concrete base of an ice floor in the National Speed Skating Oval of 2022 Beijing Winter Olympic Games. The results demonstrate that the floor flatness inspection accuracy can meet the requirement of ±0.5 mm over 5 m and the efficiency is several times that of the traditional method. This technology is promising for high precision and rapid flatness inspection of large floors. [ABSTRACT FROM AUTHOR]

In this study, the long-term trend of water vapor over the Tibetan Plateau (TP) in boreal summer is investigated by using observation and reanalysis data from 1979 to 2019. The historical experiment simulations of 19 models that participated in the Coupled Model Intercomparison Project phase 6 (CMIP6) are evaluated, and the future variation tendency under four emission scenarios is projected. The results indicate that the water vapor content and the net water vapor budget over the TP show notable increasing trends, which are mainly manifested by a significant increase in the net water vapor import and a significant decrease in the water vapor export on the eastern boundary of the TP. This is mainly due to an anomalous anticyclone from Lake Baikal to the Mongolian Plateau. The CMIP6 multi-model ensemble can well simulate the variation characteristics of the TP net water vapor budget. The projection results indicate that by the end of the twenty-first century, the water vapor content, the net water vapor import and precipitation over the TP will increase. Under a high-emissions scenario and compared with the current period (1991–2014), these three variables will increase by 47.99%, 59.77% and 18.59% in the long term (2081–2100), respectively. The significant enhancement of meridional water vapor transport over the northern TP may be the main reason for the increase in humidity over the TP. [ABSTRACT FROM AUTHOR]

Mobile laser scanning (MLS) point cloud registration plays a critical role in mobile 3D mapping and inspection, but conventional point cloud registration methods for terrain LiDAR scanning (TLS) are not suitable for MLS. To cope with this challenge, we use inertial measurement unit (IMU) to assist registration and propose an MLS point cloud registration method based on an inertial trajectory error model. First, we propose an error model of inertial trajectory over a short time period to construct the constraints between trajectory points at different times. On this basis, a relationship between the point cloud registration error and the inertial trajectory error is established, then trajectory error parameters are estimated by minimizing the point cloud registration error using the least squares optimization. Finally, a reliable and concise inertial-assisted MLS registration algorithm is realized. We carried out experiments in three different scenarios: indoor, outdoor and integrated indoor–outdoor. We evaluated the overall performance, accuracy and efficiency of the proposed method. Compared with the ICP method, the accuracy and speed of the proposed method were improved by 2 and 2.8 times, respectively, which verified the effectiveness and reliability of the proposed method. Furthermore, experimental results show the significance of our method in constructing a reliable and scalable mobile 3D mapping system suitable for complex scenes. [ABSTRACT FROM AUTHOR]

Airborne laser bathymetry (ALB) is employed to measure shallow depth water by using a high sampling rate and point density. Thus, the problems of using traditional detection methods in inaccessible areas can be avoided. This study focuses on practical solutions for receiving echo signals, identifying target echoes, and integrating land and underwater terrain point cloud data in coastal environments. Optimization of the system design and its data processing scheme is undertaken to improve the performance of the receiving system based on a single-band ALB system developed by the authors at Shenzhen University. A flight experiment over eastern Hainan Island was conducted, during which the effectiveness of the proposed strategy was verified. Finally, the technical characteristics of the self-developed system are summarized to provide a reliable reference source for the subsequent industrialization and production of related marine light detection and ranging (LiDAR) laser systems. [ABSTRACT FROM AUTHOR]

In the peak-summer of 2022, the Yangtze–Huaihe River Basin (YHRB) in China experienced its most extreme heatwaves since 1961. Notably, a rare heatwave also occurred in the YHRB in 2013. However, the Tibetan Plateau (TP) exhibited different thermal conditions during those two years. Observational analysis indicates that the 2013 and 2022 heatwaves were closely related to the local anomalous high pressure. The synergistic effects of the East Asian subtropical jet (EASJ), South Asian high (SAH), western Pacific subtropical high (WPSH), and divergence of moisture, supported the formation and maintenance of the high pressure. Compared to 2013, under the synergistic control of these intensified circulation systems in 2022, which led a broader descending motion and stronger heatwaves prevailed over the YHRB. Also, the surface air temperature of TP reached its highest value in 2022, whereas it was not distinctly anomalous in 2013. Corresponding to the TP thermal anomaly, an abnormal high pressure appeared throughout the troposphere over the northern YHRB. The TP heating contributed to the northward strengthening of the SAH and EASJ, which enhanced the anomalous westerly winds to the north of the anticyclone. Moreover, the WPSH extends westward during strong TP heating years. With the cooperation of high pressure and moisture, there was an anomalous meridional circulation pattern with ascending motion in North China and descending motion in the YHRB, accompanied by reduced cloud cover and increased insolation in the YHRB, leading to further intensification of local heatwaves in 2022. This study demonstrates the significant role of TP thermal anomaly in YHRB heatwaves. • The YHRB experienced severe heatwaves in 2022 and 2013, with the TP exhibited different thermal conditions. • The synergistic control of SAH, EASJ, WPSH and moisture divergence makes 2022 YHRB heatwaves more extreme compared to 2013. • The 2022 TP thermal anomaly affects the key atmospheric circulation, causing stronger downdrafts and heatwaves than 2013. [ABSTRACT FROM AUTHOR]

The rainy season onset date (RSOD) in the Southwest China (SWC) has important guiding significance for agricultural planting, and the abnormal RSOD is easy to cause drought or flood disasters in late spring and early summer. However, the RSOD in SWC and its related atmospheric circulation on daily scale and large regional scale has been less explored in the past literature. Therefore, this study aims to explore the circulation characteristics of RSOD on a daily scale in the whole SWC using the long-term observation and reanalysis datasets from 1961 to 2021. Results revealed that the RSOD in SWC advances from the east toward the west, with an average RSOD of May 27 and a standard deviation of 9.19 days. It is found that from around 10 days before the RSOD, the intensity of the India-Burma Trough and the Somali cross-equatorial jet stream were enhanced; the East Asian subtropical westerly jet begin to southward shift, which bring the upward movement, water vapor accumulation and the intersection of cold and warm air in southwest China, causing an earlier onset of rainy season in SWC. Moreover, May 5–25 are crucial to the early or late onset of the rainy season in SWC. When an anomalous zonal dipole of geopotential height in the upper level and an anomalous meridional dipole of geopotential height in the lower level occurred in May 5–25, the rainy season onset earlier. The atmospheric circulation changes approximately 10 days before the RSOD, and the anomalous circulation modes revealed in this study are of great importance for the prediction of RSOD in SWC. • Atmospheric circulation obviously converts or intensifies approximately 10 days before the onset of the rainy season in Southwest China. • May 5–25 are crucial to the early or late onset of the rainy season in SWC. • The dipole modes of geopotential height anomaly in the upper and lower levels affect the early and late onset of the rainy season in SWC. [ABSTRACT FROM AUTHOR]

The thermal effect of the Tibetan Plateau (TP) on the northern hemisphere climate has long been a hot topic of scientific research. However, the global effects of the TP heat source are still unclear. We investigate the teleconnection patterns coincident with the TP heat source in boreal summer using both observational data and numerical models including a linearized baroclinic model and an atmospheric general circulation model. The western TP shows the most intense variability in atmospheric heating and the most active connection to atmospheric circulations. The surface sensible heating component of the western TP heat source is associated with a high-latitude wave train propagating from North Japan to central North America through the Bering Sea and Canada. The radiative heating component is accompanied by a wavenumber-4 wave train over Eurasia. We focus on the global zonally-oriented pattern that is connected with the latent heat release from the western TP, referred to here as the TP–circumglobal teleconnection (TP-CGT). The TP-CGT pattern is triggered by the western TP latent heating in two parts starting from the TP: an eastward-propagating wave train trapped in the westerly jet stream and a westward Rossby wave response. The TP-CGT accounts for above 18% of the total variance of the circumglobal teleconnection pattern and modulates mid-latitude precipitation by superimposition. The western TP is the key region in which diabatic heating can initiate the two atmospheric responses concurrently, and the heating over northeastern Asia or the Indian Peninsula is unable to induce the circumglobal pattern directly. The unique geographical location and strong tropospheric heating also make the western TP as a "transit area" of transferring the indirect impact of the Indian summer monsoon (ISM) to the TP-CGT. These results enhance our understanding of the relationship between the circumglobal teleconnection and the ISM and is helpful for improving the prediction of the circumglobal teleconnection variability. [ABSTRACT FROM AUTHOR]

Modular multilevel converter (MMC) based medium voltage DC (MVDC) distribution system has become a promising option in the future smart grid architecture due to many distinguishing features. However, MMC-MVDC distribution system is prone to face the short-term outage problem during bipolar DC faults, so how to implement DC fault ride-through (FRT) capability for MMC-MVDC is still a challenge. This paper intends to change the redundant half-bridge submodules (HBSMs) of the HB-MMC into the redundant full-bridge submodules (FBSMs), thus, a practical DC FRT method is proposed by using the combination of the hybrid MMC and the hybrid DC circuit breakers (CBs) for the MMC-MVDC system. Then, the DC fault current characteristics of the MMC with the proposed FRT method are discussed. Lastly, data analysis and simulations of a three-terminal MMC-MVDC system have been performed in PSCAD/EMTDC to validate the effectiveness of the proposed DC FRT method. The proposed DC FRT method is not only easy to implement, but also reduces the requirements and the investment of the DC CB. [ABSTRACT FROM AUTHOR]

• The operating conditions of modular multilevel converter with maximum submodule voltage ripple are derived and found out. • A novel design of circulating current injection is proposed, in which the boundary of operating conditions is considered. • The proposed design method can achieve the minimized submodule capacitance and decreased conducting loss of the converter. • The optimization process and controller structure for the design method are presented. For the modular multilevel converter, the submodule capacitor constitutes a considerable proportion in the footprint size and weight of the whole converter. In order to achieve the light design of the converter, the requirement of submodule capacitance should be minimized. It is widely acknowledged that the sizing of submodule capacitance can be reduced by the appropriate circulating current injection, which however leads to the increase of conducting loss. In order to improve the overall operating efficiency of the system, this paper addresses the issue of multi-objective design of circulating current injection in modular multilevel converter. Firstly, considering that the submodule capacitance is sized according to the maximum capacitor voltage ripple, the operating conditions of modular multilevel converter with maximum capacitor voltage ripple are found out. Then, a novel design of circulating current injection considering the operating conditions of the converter is proposed. Under the operating condition with significant capacitor voltage ripple, the circulating current injection is designed to minimize the capacitor voltage ripple to reduce the sizing of submodule capacitance. As for the rest operating conditions, the proposed design expects to minimize the magnitude of circulating current injection to reduce the converter conducting loss. Finally, case studies of the modular multilevel converter based offshore wind power transmission system are built on PSCAD/EMTDC to validate the effectiveness of the proposed method. It can be concluded that a reasonable setting of boundary of operating conditions is essential to achieve the minimized sizing of submodule capacitance and decreased conducting loss simultaneously. [ABSTRACT FROM AUTHOR]

A regional Climate‐Weather Research and Forecasting (CWRF) model with a 30‐km horizontal resolution was applied to simulate the East Asian summer monsoon (EASM) and climate in China from 1980 to 2016. As compared with observations and reanalysis data, the model can reasonably reproduce the spatial distributions of the climatological mean atmospheric circulation and water vapour transport in East Asia, as well as the seasonal advance and retreat of EASM and rain bands. The correlation coefficient between the EASM circulation index in the simulation and reanalysis is.97. The model can well represent the geographic distributions of summer mean temperature and precipitation over most of China. However, model biases still exist, in particular the skill in the Yangtze–Huaihe River basin is relatively low. The simulated climatological mean temperature and precipitation deviations from observations may be related to the model's systematic circulation biases, with a thicker lower troposphere (i.e., higher temperature between 500 and 1,000 hPa) over most of China (except for the south and southwest) and a thinner one over the coastal oceans in summertime. Compared with the reanalysis, the model overestimates the land‐ocean thermal contrast, which causes the South Asian High shifted to the north and east, as well as the subtropical high and tropical convective activity located further north and persisted longer. Consequently, more water vapour transports northward, leading to more precipitation over North China–Northeast China and less precipitation over the Yangtze and Huaihe River basin. Therefore, the enhanced land‐ocean thermal contrast may be a major factor for the stronger EASM in the model, and corresponding precipitation and temperature biases in China. This analysis provides important information for further improving model performance in EASM simulation. [ABSTRACT FROM AUTHOR]

For droop control in voltage source converter based multi-terminal HVDC systems, the determination of droop coefficients is a key issue, which directly affects both power distribution and DC control performances. This paper proposes a novel design of droop coefficients considering the requirements of power distribution, DC voltage control and system stability. Considering the power margins of different converters, the ratio relationship among droop coefficients is established. Converters with larger power margins take bigger portion of power mismatch to avoid overload problem. Furthermore, the integral square error of converters DC voltage is adopted as the DC voltage control performance index, and optimization of droop coefficients to achieve coordinated DC voltage control of steady-state deviation and transient variation, is derived. Finally, the constraint of droop coefficients is established to guarantee the DC system stability after power disturbance. Case studies are conducted on the Nordic 32 system with an embedded 4-terminal DC grid to demonstrate the feasibility and effectiveness of the proposed droop control scheme. [ABSTRACT FROM AUTHOR]

As one of the main threats to people’s health, especially for the elderly, falls have caused a large number of accidents. Detecting falls in time can minimize the severity of the injury and save lives. Therefore, designing fall detection algorithms to assist people’s daily life has been a hot research topic. In the last decade, different fall detection approaches based on wearable sensors have been proposed. However, since the hardware resources of wearable sensors are very limited, designing accurate but energy-efficient fall detection algorithms remains an open challenge. To deal with this, an accurate but low-cost fall detection algorithm is proposed in this paper. Particularly, a novel cascade and parallel method that efficiently employs the characteristics of human falls and the advanced modeling ability of the neural network is proposed. Also, a novel design of a lightweight convolutional neural network with self-attention is proposed to achieve the best recognition/numerical complexity tradeoff. The proposed method, namely CMFALL, is evaluated together with a multitude of state-of-the-art models on a large dataset, where it performs the best with an F1-score exceeding 99%. Meanwhile, its computational cost and model size are only a few thousandths of other models. Such low computational cost and small size not only enable to embed it in a wearable sensor but also make the system power requirements quite low, which can enhance the autonomy of the wearable fall detector. [ABSTRACT FROM AUTHOR]

The sub‐seasonal characteristics and prediction of rainfall over the South China Sea and surrounding areas during spring–summer transitional season (April–May–June) are investigated using a full set of hindcasts generated by the Dynamic Extended Range Forecast operational system version 2.0 (DERF2.0) of Beijing Climate Center, China Meteorological Administration. The onset and development of Asian summer monsoon and the seasonal migration of rain belt over East Asia can be well depicted by the model hindcasts at various leads. However, there exist considerable differences between model results and observations, and model biases depend not only on the lead time, but also on the stage of monsoon evolution. In general, forecast skill drops with increasing lead time but rises again after lead time becomes longer than 30 days, possibly associated with the effect of slowly‐varying forcing or atmospheric variability. An abrupt turning point of bias development appears around mid‐May when bias growths of wind and precipitation exhibit significant changes over the northwestern Pacific and South Asia, especially over the Bay of Bengal and the South China Sea. This abrupt bias change is reasonably captured by the first two modes of multivariate empirical orthogonal function analysis, which reveals several important features associated with the bias change. This analysis may provide useful information for further improving model performance in sub‐seasonal rainfall prediction. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) mapping is important to achieve early warning for construction safety and support the long-term safety maintenance of tunnels. However, generating 3D point cloud maps of excavation tunnels that tend to be deficient in features, have rough lining structures, and suffer from dynamic construction interference, can be a challenging task. In this paper, we propose a novel legged robot-aided 3D tunnel mapping method to address the influence of point clouds in the mapping phase. First, a method of kinematic model construction that integrates information from both the robot's motors and the inertial measurement unit (IMU) is proposed to correct the motion distortion of point clouds. Then, a residual compensation model for unreliable regions (abbreviated as the URC model) is proposed to eliminate the inherent alignment errors in the 3D structures. The structural regions of a tunnel are divided into different reliabilities using the K-means method, and an inherent alignment metric is compensated based on region residual estimation. The compensated alignment metric is then incorporated into a rotation-guided anomaly consistency detection (RAD) model. An isolation forest-based anomaly consistency indicator is designed to remove anomalous light detection and ranging (LiDAR) points and reduce sensor noise caused by ultralong distances. To verify the proposed method, we conduct numerous experiments in three tunnels, namely, a drilling and blasting tunnel, a TBM tunnel, and an underground pedestrian tunnel. According to the experimental results, the proposed method achieves 0.84 ‰, 0.40 ‰, and 0.31 ‰ closure errors (CEs) for the three tunnels, respectively, and the absolute map error (AME) and relative map error (RME) are approximately 1.45 cm and 0.57 %, respectively. The trajectory estimation and mapping errors of our method are smaller than those of existing methods, such as FAST-LIO2, Faster-LIO and LiLi-OM. In addition, ablation tests are conducted to further reveal the roles of the different models used in our method for legged robot-aided 3D mapping in tunnels. [ABSTRACT FROM AUTHOR]

• The bipolar charge transport and hydrodynamic drift-diffusion models were used. • The PD waveforms under the assessed conditions were unimodal. • Pressboard surface charge can form a shield layer that hinders streamer evolution. • The streamers have voltage-dependent shapes. • The time relationships between PD pulse and streamer evolution were found. A better understanding of the complicated characteristics and interrelationships between the charge distributions and partial discharge (PD) pulse waveforms occurring in oil-pressboard insulation can be used to characterise the PD mechanism as a basis for the optimisation of the insulation structure to minimise PD activity. These characteristics were studied by using a non-inductive resistor to measure the PD pulse waveforms produced in oil-pressboard insulation by a needle-plate at positive DC voltage and through additional simulations based on bipolar charge transport and hydrodynamic drift-diffusion models. It was found that the PD pulse waveforms are unimodal, and with increased applied voltage, their rising and falling edges and equivalent times decrease, and their apparent charge amplitudes and equivalent frequencies increase. These parameters have a saturation state at high voltages (>45 kV) and the oil streamers have voltage-dependent shapes and evolution velocities (v s); the higher the voltages, the higher the values of v s , and the wider are the streamer bodies. Accumulated charge can form a shield layer that hinders streamer evolution. Analysis of the PD mechanism in terms of the relationships between charge distribution and PD pulse waveform reveal that the rising and falling edges of a PD pulse correspond to streamer propagation in the oil gap and charge accumulation at the pressboard surface (i.e., the charging process in the pressboard), respectively. The peak value of the PD pulse waveform is shown to be related to the conduction current in the coupling loop as reflected by the current density at the streamer head. [ABSTRACT FROM AUTHOR]

Aims: Ficolin-3 is a circulating pattern recognition molecule of the lectin pathway, which participates in the host immune responses to cancer. Our study aimed to evaluate the prognostic efficacy of ficolin-3 in patients with esophageal cancer (EC). Methods: A total of 233 patients with EC were recruited for this study during a period from March 2013 to March 2016. Clinical information and pretherapeutic tumor specimens from all of the patients were analyzed. Serum ficolin-3 levels were determined by enzyme-linked immunosorbent assay. Patients were then assigned into quartiles according to their serum ficolin-3 levels. The Cox proportional hazards model was utilized to explore the correlation between ficolin-3 levels with overall survival (OS) and disease-specific survival (DSS). Results: The serum ficolin-3 level in the esophageal squamous cell carcinoma (ESCC) group was significantly higher than in the esophageal adenocarcinoma (EAC) group (19.59 ± 4.35 ng/mL vs. 18.39 ± 5.42 ng/mL, p < 0.01). There were great differences in prevalence of ESCC, tumor length, involvement of adventitia, and lymph node status among patients in different ficolin-3 groups (all p < 0.01). Both univariate analyses and further multivariate analyses revealed the close association between ficolin-3 levels and EAC (For OS and DSS, all p < 0.05). Out of 233 patients, survival information was available for 220, including 100 (45.45%) females and 120 (54.54%) males. When dividing the ficolin-3 levels into quartiles, patients with higher serum ficolin-3 levels showed a trend toward longer OS and DSS no matter whether they were diagnosed as ESCC or EAC (HR 0.21–0.55, all p < 0.05). Conclusions: Serum ficolin-3 levels were identified as an independent prognostic biomarker for DSS and OS in Chinese patients with EC, especially EAC. [ABSTRACT FROM AUTHOR]

• In this paper, the mechanism and the main suppression measures of ferroresonance were described. • A typical substation was taken as the research object, and the simulation models were established by using the electromagnetic transient analysis software ATP-EMTP. • Two measures to suppress ferromagnetic resonance are discussed, which can provide reference for the power sector to control ferromagnetic resonance. • When the neutral point of voltage transformer is grounded by resonance eliminator or the arc suppression coil, the ferroresonance of the system can be effectively suppressed. In order to monitor the three-phase voltage of the busbar to ground, the substation bus is usually connected to the electromagnetic voltage transformer by YN connection in the distribution network. Under certain conditions, the excitation characteristics are easy to saturate, and the inductance parameters match the system capacitance, excite ferromagnetic resonance, cause damage to fuses or voltage transformers, and seriously affect the safe and stable operation of the power system.By analyzing typical single-phase ground faults, this paper introduces the generation mechanism of ferromagnetic resonance and the main suppression measures at this stage. The electromagnetic transient analysis software ATP-EMTP is used to analyze the operation of a typical transformer, and the change of ferromagnetic resonance waveform after the neutral point of the voltage transformer is replaced by resonant eliminator and arc suppression coil grounding. The results show that when eliminating the single-phase ground fault, it is easy to cause the frequency division resonance of the system, and the use of these two measures can effectively suppress the ferromagnetic resonance of the system. [ABSTRACT FROM AUTHOR]

Wind power systems are a key element in sustainable development and provide a stable and secure model for communication through the power grid. The research proposes a control strategy called AGC OPI for wind power systems that focuses on frequency and inertia control. The proposed strategy employs a weighted Grey Wolf Optimization (WGWO) algorithm that is integrated with a Proportional-Integral (PI) controller to enhance the frequency response and stability of the power grid. The AGC OPI scheme uses primary frequency modulation to manage the generated power in the wind farm. The response time is computed for a specific area using a State Estimation and Measurement System (SEMS) unit for measurement. The results demonstrate that the AGC OPI model offers superior performance compared to the conventional ABC-PID controller. The primary regulation model achieves a response time of less than 2 s and maintains a control deviation in the rated capacity value of ±1%. [ABSTRACT FROM AUTHOR]

The application value of broken rice as a rich by-product in rice industry cannot be ignored. In this paper, Na 2 CO 3 was used as extraction solvent and NaOH solution was used for control treatment to obtain broken rice protein (BRP) with high yield and good functional properties. Based on single-factor experiments, Response Surface methodology was used to determine the influence of the concentration of NaOH or Na 2 CO 3 , material-liquid ratio, and extraction time on the extraction rate of BRP. The maximum protein extraction yields were reached at 78.62% and 72.26% under the best extraction conditions of NaOH (0.08 mol/L, 1:13 g/mL and 3.0 h) and Na 2 CO 3 (0.08 mol/L, 1:18 g/mL and 3.0 h). SDS-PAGE, FT-IR and DSC showed that changes in influencing factors during optimization process had different effects on BRP. There are significant differences in amino acid content of BRP, the content of essential amino acids in BRP obtained from the Na 2 CO 3 group was higher. In addition, different extraction parameters had different influences on functional properties of BRP. This study provides new technical guidance for the development and utilization of rice by-product - broken rice to improve the protein extraction rate of broken rice in the industry. [Display omitted] • Preparation of broken rice protein extracted by alkaline solutions of NaOH and Na 2 CO 3. • The extraction rate of broken rice protein was related to the concentration of extractant. • The strong alkali-NaOH extraction would reduce the essential amino acid content of the broken rice protein. • Broken rice protein extracted by alkaline solutions of Na 2 CO 3 could improve the functional properties. [ABSTRACT FROM AUTHOR]

As major urban agglomerations with strong urbanization, global bay areas are seldom detected and compared in detail regarding the spatiotemporal evolution of their urban expansion. In this work, a framework was applied for detecting and comparing the spatiotemporal evolution of urban agglomerations in four major bay areas: the San Francisco Bay Area and the New York Bay Area in the US, the Tokyo Bay Area in Japan, and the Guangdong-Hong Kong-Macau (GHM) Bay Area in China. Landsat images from 1987, 1997, 2007 and 2017 were employed to derive the four urban bay areas using the object-oriented support vector machine (O-SVM) classification method, and a multi-scale spatial analysis method was applied to detect the landscape characteristics and types of growth in the urban expansions. The results showed that: (1) the O-SVM classification method exhibited a high accuracy in urban area extraction, especially for classifying large-scale images; (2) the urban areas of the San Francisco Bay Area, the New York Bay Area, the Tokyo Bay Area and the GHM Bay Area from 1987 to 2017 expanded from 1686.82, 5315.93, 3765.09 and 605.71 km2 to 2714.7, 8359.18, 5351.06 and 7568.19 km2, respectively, with a corresponding annual average increase of 1.60%, 1.52%, 1.18% and 8.82%; (3) the GHM Bay Area had the largest expansion area and rate among the four bay areas; (4) both the San Francisco Bay Area and the New York Bay Area successively formed a multi-nuclei ribbon model, and the Tokyo Bay Area and the GHM Bay Area formed a multinuclear fan-shaped model and a triangle zonal expansion pattern, respectively; and (5) the spatial patterns of urban expansions in these bay areas shifted from outlying to edge-expansion and infilling, in which the Tokyo Bay Area and the New York Bay Area experienced the largest infilling growth, and the San Francisco Bay Area followed closely thereafter; all were ahead of the GHM Bay Area. These results will be helpful for the understanding and sustainable development of these bay areas. Unlabelled Image • Urban growth was detected and compared in four major bay areas of US, China and Japan. • Urban expansion rate showed a considerable regional disparity. • Four bay areas demonstrated different urban expansion patterns. • Extensive outlying and edge-expansion growth confirmed the suburbanization of China bay area. • Landscape responses to urban growth varied with different spatial and temporal scales. [ABSTRACT FROM AUTHOR]

People’s daily travels are structured and can be expressed as networks. Few studies explore how people organize their daily travels and which behavioral principles result in the choices of specific network types. In this study, we first reconstruct location networks and activity networks for numerous individuals from high-resolution mobile phone positioning data and define frequent networks as motifs. The results suggest that 99.9% of people’s travels can be characterized by a limited set of location-based motifs and activity-based motifs. The results further reveal that the least effort principle governs the preferred motif choices through quantifying the rank-frequency properties. The scaling properties of distance characteristically impact motifs, and their scaling differences by node numbers and motif types coincide with the popularities of motifs, verifying the self-adaptions in motif choices; that is, although individuals travel with unique propensities, they always tend to choose the motif with the lowest consumption that satisfies their demand. [ABSTRACT FROM AUTHOR]

Sampling fraction is crucial to sampling-related studies and applications, especially in the big data era when most data are neither originally designed nor controllable in the data collection process. A common concern among researchers is 'what's the modelling accuracy when using a sample?'. Taking intra-city human mobility as the study objective, this study utilizes a simple and direct method to analyse the influences of various sampling fractions on modelling accuracy. Five common intra-city human mobility indicators (travel distance, travel time, travel frequency, radius of gyration and movement entropy) are evaluated considering mean value, median and probability distribution. Experimental results demonstrate that the representativeness of each considered indicator converges to 1 in its own unique rate and variances. The minimum required sampling fractions to satisfy specific accuracies differ for various indicators and evaluation measures. To further investigate how related factors influence the modelling accuracy of sampling fractions, additional experiments are conducted considering multiple sampling methods, study scopes, and data sources. Several interesting general findings are observed. This study provides a reference for other sampling-based applications. [ABSTRACT FROM AUTHOR]

The application of droop control in the voltage‐source converter‐based multi‐terminal direct current (VSC‐MTDC) system has been previously proposed in the literature. However, how to determine the droop coefficients to stabilise the DC voltage is still the key issue to concern and research. This study presents a novel calculation methodology for droop coefficients in the case of outage or power step disturbance on any converter station. The overall design objective is to minimise the DC voltage deviation between pre‐ and post‐disturbance, depicted with a quadratic programming model. In addition, the selection method of the optimal DC voltage signal for droop controllers is developed in both cases of communication failure and communication normal. Based on the calculated droop coefficients and selected DC voltage signal, the power coordinated control among the converter stations is implemented to stabilise the DC voltage of the post‐disturbance system quickly. Case studies are conducted on the Nordic 32 and New England system, respectively. The simulation results show that the proposed methodology for droop coefficients can significantly reduce the steady‐state DC voltage deviations without the limitation of preassigning the maximum allowable DC voltage deviation, compared to the methodologies existing in the literature. [ABSTRACT FROM AUTHOR]

The DC voltage related partial discharge (PD) classification in solid dielectrics under a uniform electric field has been studied, but it is more complicated in liquid-solid composite insulation under a highly non-uniform electric field. Therefore, PD pulse waveforms and PD channel shapes in oil-pressboard insulation were investigated by simulating a needle-plate model with a positive DC voltage via pulse current method. The elements of PD can be classified in order of ionizing intensity strength as corona, tree-like PD, single-streamer PD, or multi-streamer PD according to the discharge channel shape. The corona pulses are sharply oscillating, whereas the other types of PD can generate unimodal pulses with no over-zero oscillation. A finite element analysis reveals the PD types are related to the charge quantity at the oil-pressboard interface, which influences the streamer evolution by distorting the space electric field. This study uncovers the physical process during PD in oil-pressboard insulation and provides basis for explaining the PD mechanism. [ABSTRACT FROM AUTHOR]

Abstract Tide correction is important in ship-board bathymetric data. Currently, most tide correction algorithms use a space-time interpolation method to regain the composite sea surface morphology. These interpolation algorithms are mostly based on geometric interpolation. However, when the tide stations are insufficient in the survey region, the spatial pattern of tide change may not comply with the geometric trend. Some of the algorithms use tide simulation to obtain a space-time astronomical tide model for tide correction in tide-station-insufficient regions, because the instantaneous water level changes are mainly caused by astronomical tides in normal conditions. However, in some cases, the instantaneous water level effect of the short-period stochastic meteorological factors results in short-term water level anomalies, which can be difficult to simulate using a tide simulation method. Thus, in this paper, an instantaneous water level model for tide correction in tide-station-insufficient regions is proposed. The model includes the simulation of astronomical tide and deviation-tidal components. We first simulate the astronomical tidal model using a two-dimensional MIKE21 Flow Model. Then, we propose a deviation correction method to mitigate the deviation-tidal components. Using the revised instantaneous water level model, we present the instantaneous tide correction (ITC) algorithm. Then, we compare the ITC algorithm with the two commonly used algorithms of Discrete Tidal Zoning and TCARI. The results show that the ITC algorithm is superior to the common algorithms in terms of accuracy and applicability with respect to a tide-station-insufficient survey region. Our conclusion is that ITC algorithm is a feasible tide correction algorithm when tide stations are not sufficiently measured. Highlights • Propose an instantaneous water level model for tide correction in tide-station-insufficient survey regions. • Construct the astronomical tide model using the 2D MIKE21 Flow Model for the simulation. • Propose a deviation correction method to mitigate the deviation-tidal components. [ABSTRACT FROM AUTHOR]

Observations indicate that East Asian summer precipitation exhibits significant interdecadal variability, with an alternating reverse phase distribution of rainfall from south to north, which is different from the consistent increase or decrease of precipitation in the whole region. The East Asian summer monsoon mainly affects the spatial pattern of meridional tripole precipitation on the interdecadal timescale. Moreover, the interdecadal sea surface temperature variability in the extratropical southern Indian Ocean is the most significant in the boreal summer. When there is anomalous warming in the extratropical southern Indian Ocean, the Somali cross-equatorial flow weakens and then alternating positive and negative waves propagate to central East Asia. In contrast, the New Guinea cross-equatorial flow experiences interdecadal enhancement with cyclonic circulation anomalies over the Northwest Pacific and anticyclonic circulation anomalies over the Philippines, which leads to a weakening of the South China Sea monsoon trough. On one hand, the cyclonic-anticyclonic coupling over the Philippines and Northwest Pacific results in an anomalous eastward transport of water vapor and reduced water vapor input over southern East Asia. On the other hand, the coupling strengthens the water vapor transport from the mid-latitude Northwest Pacific to central East Asia. These circulation anomalies favor the development of a meridional tripole pattern, i.e. a "negative – positive – negative" pattern of East Asian summer monsoon precipitation anomalies on the interdecadal timescale, which is specifically manifested in the abnormal increase of precipitation in central East Asia and the decrease of precipitation in northern and southern East Asia. • The EASM mainly affects the spatial pattern of meridional tripole precipitation on the interdecadal timescale. • In the boreal summer, the interdecadal variability of the ETSIO SST is the most significant in the Indian Ocean. • The interdecadal ETSIO SST influences the EASM precipitation through two cross-equatorial flows by different mechanisms. [ABSTRACT FROM AUTHOR]

In this paper, an improved method based on a mixture of Gaussian and quadrilateral functions is presented to process airborne bathymetric LiDAR waveforms. In the presented method, the LiDAR waveform is fitted to a combination of three functions: one Gaussian function for the water surface contribution, another Gaussian function for the water bottom contribution, and a new quadrilateral function to fit the water column contribution. The proposed method was tested on a simulated dataset and a real dataset, with the focus being mainly on the performance of retrieving bottom response and water depths. We also investigated the influence of the parameter settings on the accuracy of the bathymetry estimates. The results demonstrate that the improved quadrilateral fitting algorithm shows a superior performance in terms of low RMSE and a high detection rate in the water depth and magnitude retrieval. What’s more, compared with the use of a triangular function or the existing quadrilateral function to fit the water column contribution, the presented method retrieved the least noise and the least number of unidentified waveforms, showed the best performance in fitting the return waveforms, and had consistent fitting goodness for all different water depths. [ABSTRACT FROM AUTHOR]

The vehicle routing problem (VRP) is one of the most prominent problems in spatial optimization because of its broad applications in both the public and private sectors. This article presents a novel spatial parallel heuristic approach for solving large-scale VRPs with capacity constraints. A spatial partitioning strategy is devised to divide a region of interest into a set of small spatial cells to allow the use of a parallel local search with a spatial neighbor reduction strategy. An additional local search and perturbation mechanism around the border area of spatial cells is used to improve route segments across spatial cells to overcome the border effect. The results of one man-made VRP benchmark and three real-world super-large-scale VRP instances with tens of thousands of nodes verify that the presented spatial parallel heuristic approach achieves a comparable solution with much less computing time. [ABSTRACT FROM AUTHOR]

Abstract Decadal prediction experiments of Beijing Climate Center climate system model version 1.1 (BCC-CSM1.1) participated in Coupled Model Intercomparison Project Phase 5 (CMIP5) had poor skill in extratropics of the North Atlantic, the initialization of which was done by relaxing modeled ocean temperature to the Simple Ocean Data Assimilation (SODA) reanalysis data. This study aims to improve the prediction skill of this model by using the assimilation technique in the initialization. New ocean data are firstly generated by assimilating the sea surface temperature (SST) of the Hadley Centre Sea Ice and Sea Surface Temperature (HadISST) dataset to the ocean model of BCC-CSM1.1 via Ensemble Optimum Interpolation (EnOI). Then a suite of decadal re-forecasts launched annually over the period 1961–2005 is carried out with simulated ocean temperature restored to the assimilated ocean data. Comparisons between the re-forecasts and previous CMIP5 forecasts show that the re-forecasts are more skillful in mid-to-high latitude SST of the North Atlantic. Improved prediction skill is also found for the Atlantic multi-decadal oscillation (AMO), which is consistent with the better skill of Atlantic meridional overturning circulation (AMOC) predicted by the re-forecasts. We conclude that the EnOI assimilation generates better ocean data than the SODA reanalysis for initializing decadal climate prediction of BCC-CSM1.1 model. [ABSTRACT FROM AUTHOR]

Region-based hierarchical image representation is crucial in many computer vision applications. However, in practice, an image hierarchy is usually dense, and contains many less informative branches. It is expected that a hierarchy should be accurate and simplified, which is not only desirable for different applications, but also saves considerable computational load for the further analysis. To achieve this target, this paper proposes a novel approach for unsupervised simplification of region-based image hierarchies, which employs the global and local evolution analyses of a hierarchy. First, we introduce a global evolution analysis in the scale-sets framework, which provides clues for eliminating less informative branches. Moreover, a hybrid unsupervised simplification method is designed, utilizing the information from global and local evolution functions. A number of experiments on various images have shown that the proposed approach is effective and efficient in removing less informative nodes (averagely about 90% of the whole nodes), while preserving salient image details and retaining the accuracy. [ABSTRACT FROM PUBLISHER]

Fitting polarimetric synthetic aperture radar (PolSAR) data with adaptive scattering models is a promising way to mitigate the deficiencies of the model-based decomposition. Recently, Lee et al. have proposed a generalized decomposition model with several adaptive parameters, whereas the generalized model introduces too much freedom to be solved. In this paper, based on the Lee generalized decomposition model, an adaptive two-component decomposition model is proposed. The PolSAR coherency matrix is represented as the sum of two scattering mechanisms: coherent ground scattering and incoherent volume scattering. The proposed model is under three assumptions: 1) Surface and double scattering are coherent; 2) surface and double scattering are integrated as the ground scattering; and 3) the average polarimetric orientation angle (POA) of the volume (or Bragg) scattering is zero. As the proposed model is very difficult to solve directly, we adopted the exhaustion technique to find the best fit parameter set. The proposed model has three advantages: 1) It can successfully avoid the negative power problem; 2) it is considered without the assumption of reflection symmetry; and 3) the dominant scattering mechanism criterion is not needed in the process of model inversion. However, the proposed model has two disadvantages: 1) the attribution of the volume model becomes ambiguous; and 2) the assumption that sets the POA of the Bragg scattering component to zero is inconsistent with the actual scattering mechanism when there is a slope in the rough surface. The polarimetric AIRSAR L-band data of San Francisco and ESAR L-band data of Oberpfaffenhofen were used to show the efficiency of the proposed decomposition model. Statistical properties of typical areas showed that, except the sea surface and the urban area with building orientation angle about 45°, the proposed model fits the PolSAR data very well. [ABSTRACT FROM PUBLISHER]

Among the various defects of asphalt pavement distress, much attention has been paid to cracks which often cause significant engineering and economic problems. Crack detection is not an easy task since images of road pavement surface are very difficult to analyze. In this paper, a highly efficient pavement crack detection system is proposed, which has the following distinguishing features. Firstly, a new description of the cracks is proposed based on the spatially clustered pixels with similar gray levels. Secondly, an adaptive thresholding method is presented for image segmentation by comprehensively taking into account the spatial distribution, intensities and geometric features of cracks. Thirdly, a new concept termed Region of Belief (ROB) is introduced to facilitate the subsequent detection by defining some credibility factors which indicate the reliability that a region could be labeled as a distress region which contains cracks, and an algorithm to extract such ROBs is devised accordingly. Lastly, a novel region growing algorithm is propounded for crack detection, which features starting with an ROB seed, determining the searching scope with a specially devised rule, and searching and merging a ROB with different regions following a similarity criterion which synthetically takes different cues into consideration. Two different types of experiments were conducted. The first one was carried out using 10,000 of our field-captured images which were taken from different road conditions and environments. The second one was completed using a benchmark dataset for a comparison with other recent publications. The evaluation performance is satisfactory for a variety of different cracks. For our own data, the detection accuracy is over 95% and more than 90% of coherent cracks without disconnected fragments have been correctly detected as the integrated ones. For the benchmark data, our detection performance also outperforms previously published results. Currently, our approach has been widely applied in China. [ABSTRACT FROM AUTHOR]

The assumption of reflection symmetry is one of the major deficiencies for model-based decompositions. The introduction of helix scattering components can mitigate some of the impact of this assumption while simultaneously generating some new negative power problems. The helix mechanism has been developed in the Krogager coherent target decomposition where there is no negative power problem. Why do these problems happen in model-based decompositions? In this paper, we review the Krogager decomposition based on the coherency matrix form of the unified CTD model and come to the conclusion that the imaginary part of T23 is an overestimate of the helix contribution, which is the main cause of the problem. Furthermore, we review the techniques of symmetric scatterer transformation in the Cameron and Huynen decompositions and expand them to the multilook coherency matrix. Two new models of the nonlinear programming problem are proposed to get the transformed coherency matrix: 1) by subtracting the asymmetric component; and 2) by the procedure of con-diagonalization. A new parameter is established to measure the degree of reflection asymmetry of the coherency matrices. Experimental results in the L-band Airborne SAR (AIRSAR) San Francisco data show that the two new models can reduce the correlations between copolarized and cross-polarized channels significantly. In this case, the assumption of reflection symmetry is reasonable for the transformed coherency matrices, and negative power problems related to helix scattering no longer exist in the model-based decompositions; hence, the helix scattering component is not needed. Lastly, the Freeman and Durden decomposition has been applied to the transformed coherency matrices. Experimental results showed that the decomposition results can reflect the predominant characteristics of the ground objects. [ABSTRACT FROM PUBLISHER]

This paper investigates the problem of finding the K reliable shortest paths (KRSP) in stochastic networks under travel time uncertainty. The KRSP problem extends the classical K loopless shortest paths problem to the stochastic networks by explicitly considering travel time reliability. In this study, a deviation path approach is established for finding K α-reliable paths in stochastic networks. A deviation path algorithm is proposed to exactly solve the KRSP problem in large-scale networks. The A * technique is introduced to further improve the KRSP finding performance. A case study using real traffic information is performed to validate the proposed algorithm. The results indicate that the proposed algorithm can determine KRSP under various travel time reliability values within reasonable computational times. The introduced A * technique can significantly improve KRSP finding performance. [ABSTRACT FROM AUTHOR]

Sparse coding (SC) is making a significant impact in computer vision and signal processing communities, which achieves the state-of-the-art performance in a variety of applications for images, e.g., denoising, restoration, and synthesis. We propose an adaptive and robust SC algorithm exploiting the characteristics of typical laser range data and the availability of both range and reflectance data to realize range data denoising and inpainting. Specifically, our method estimates the informative level of each patch according to the variation in both range and reflectance modalities, followed by adaptive dictionary training that assigns dynamic sparsity weights to the patches with different informative levels. Furthermore, the \ell 1 -norm-based representation fidelity measure is applied to make our method robust to outliers which are common in laser range measurements. Extensive experiments on synthetic and real data demonstrate that our method works effectively, resulting in superior performance both visually and quantitatively, compared with competitive methods including the available sparse-representation-based algorithm, wavelets, partial differential equation, and non-local means. [ABSTRACT FROM AUTHOR]

Building orientation with respect to the radar look direction has a critical influence on the interpretation of multilook polarimetric synthetic aperture radar (PolSAR) data in urban areas. In this paper, its impacts on polarimetric orientation angle (POA) estimation and model-based decomposition are discussed. The discussion begins with the analysis of the general double-bounce scattering model, of which the characteristics are dependent on the electromagnetic and geometric parameters of the related dihedral structure. Then, for multilook PolSAR data, the polarimetric scattering mechanism in urban areas is modeled by two double-bounce scatterings from two orthogonal dihedral structures. From the model, the impacts of the building orientation on POA estimation can be revealed. With the increase of the building orientation, the POA difference between the two dihedral structures increases gradually, and the feasibility to estimate the building orientation via the estimated POA is reduced dramatically. Upon further analysis, we illustrate the impacts on the model-based decomposition. With the increase of the building orientation, the dominant scattering mechanism labeling technique based on the model-based decompositions will gradually become invalid. Moreover, the processing of POA compensation, which is helpful in reducing the impacts of the building orientation, also becomes invalid when the building orientation increases to a certain value. At last, three L-band data sets of San Francisco acquired by AIRSAR are used to verify the inferences. The experimental results show that, for L-band PolSAR data in urban areas, when the radar look angle is around 45, the threshold of building orientation for the validity of dominant scattering mechanism labeling is about ±3, and for the POA compensation, the threshold is about ±12. [ABSTRACT FROM AUTHOR]

• This paper proposes a novel design of circulating current control target to minimize the requirement of SM capacitance in MMC. • The phase angle of circulating current is designed to reduce the fundamental and second-harmonic capacitor voltage ripple at the same time. • The magnitude of circulating current is proposed to achieve the optimal phase angle or magnitude coordination between the components of SM capacitor voltage ripple. • Compared with the available methods, the proposed method can further reduce the requirement of SM capacitance by 16.4%, which can contribute to the lighter design of MMC on the offshore wind farm side. In an MMC station, the submodule (SM) capacitor constitutes a high proportion in both the footprint size and construction cost, which greatly limits the application of MMC in some scenarios, such as offshore wind power transmission system. Since the SM capacitor voltage ripple has a close interaction with the phase circulating current in MMC, an appropriate management of circulating current is widely acknowledged to reduce the SM capacitance. This paper proposes a novel design of circulating current control target to minimize the requirement of SM capacitance in MMC. Firstly, the phase angle of circulating current is designed to significantly reduce the fundamental and second-harmonic capacitor voltage ripple at the same time. Secondly, the magnitude of circulating current is determined to achieve the optimal phase angle or magnitude coordination between the components of SM capacitor voltage ripple. Thus, under the proposed design method, the peak-peak capacitor voltage ripple is minimized and the requirement of SM capacitance can be effectively reduced. Finally, an MMC-HVDC case system connecting to the offshore wind farm is built on PSCAD/EMTDC to validate the effectiveness of the proposed design method. [ABSTRACT FROM AUTHOR]

Vehicle electrification is a promising approach towards attaining green transportation. However, the absence of charging stations limits the penetration of electric vehicles. Current approaches for optimizing the locations of charging stations suffer from challenges associated with spatial–temporal dynamic travel demands and the lengthy period required for the charging process. The present article uses the electric taxi (ET) as an example to develop a spatial–temporal demand coverage approach for optimizing the placement of ET charging stations in the space–time context. To this end, public taxi demands with spatial and temporal attributes are extracted from massive taxi GPS data. The cyclical interactions between taxi demands, ETs, and charging stations are modeled with a spatial–temporal path tool. A location model is developed to maximize the level of ET service on the road network and the level of charging service at the stations under spatial and temporal constraints such as the ET range, the charging time, and the capacity of charging stations. The reduced carbon emission generated by used ETs with located charging stations is also evaluated. An experiment conducted in Shenzhen, China demonstrates that the proposed approach not only exhibits good performance in determining ET charging station locations by considering temporal attributes, but also achieves a high quality trade-off between the levels of ET service and charging service. The proposed approach and obtained results help the decision-making of urban ET charging station siting. [ABSTRACT FROM AUTHOR]

Turn restrictions, such as 'no left turn' or 'no U-turn', are commonly encountered in real road networks. These turn restrictions must be explicitly considered in the shortest path problem and ignoring them may lead to infeasible paths. In the present study, a hybrid link-node Dijkstra's (HLND) algorithm is proposed to exactly solve the shortest path problem in road networks with turn restrictions. A new hybrid link-node labelling approach is devised by using a link-based labelling strategy at restricted nodes with turn restrictions, and a node-based labelling strategy at unrestricted nodes without turn restrictions. Computational results for several real road networks show that the proposed HLND algorithm obtains the same optimal results as the link-based Dijkstra's algorithm, while having a similar computational performance to the classical node-based Dijkstra's algorithm. [ABSTRACT FROM AUTHOR]

How should the efficiency of searching for real objects in real scenes be measured? Traditionally, when searching for artificial targets, e.g., letters or rectangles, among distractors, efficiency is measured by a reaction time (RT) × Set Size function. However, it is not clear whether the set size of real scenes is as effective a parameter for measuring search efficiency as the set size of artificial scenes. The present study investigated search efficiency in real scenes based on a combination of low-level features, e.g., visible size and target-flanker separation factors, and high-level features, e.g., category effect and target template. Visible size refers to the pixel number of visible parts of an object in a scene, whereas separation is defined as the sum of the flank distances from a target to the nearest distractors. During the experiment, observers searched for targets in various urban scenes, using pictures as the target templates. The results indicated that the effect of the set size in real scenes decreased according to the variances of other factors, e.g., visible size and separation. Increasing visible size and separation factors increased search efficiency. Based on these results, an RT × Visible Size × Separation function was proposed. These results suggest that the proposed function is a practicable predictor of search efficiency in real scenes. [ABSTRACT FROM AUTHOR]