Fluoxetine (FLX), an emerging pollutant, has been detected in the sewage and excess sludge (ES) at substantial levels. So far, however, the impacts of FLX on the ES anaerobic digestion and the ...related mechanisms have never been investigated. In this work, the effects of FLX on the ES anaerobic digestion were explored by the batch test under moderate temperature condition. The results indicated the effect of FLX on ES digestion was dose-dependent. When FLX was at a low dose (0.1 mg/kg), FLX had no significant impact on the methane generation from the ES digestion. However，when FLX was 2.0 mg/kg, the cumulative methane production was only 91.2 ± 4.3 mL/g volatile suspended solids (VSS), which was about 59.9 ± 3.4% of the blank (without FLX). Mechanisms revealed that the presence of FLX has inhibited hydrolysis, acidification and methanogenesis. Enzyme activity analysis showed that FLX inhibited the activities of key enzymes in the process of hydrolysis, acidification and methanogenesis. The results of this work are of great significance to explain the role of FLX in the process of ES fermentation, and provide some reference for the subsequent utilization of ES.
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•The effect of FLX on ES digestion was explored for the first time.•The presence of FLX reduced methane accumulation from ES.•High content of FX inhibited ES hydrolysis and acidification process.
The detection and classification of white blood cells (WBCs, also known as Leukocytes) is a hot issue because of its important applications in disease diagnosis. Nowadays the morphological analysis ...of blood cells is operated manually by skilled operators, which results in some drawbacks such as slowness of the analysis, a non-standard accuracy, and the dependence on the operator’s skills. Although there have been many papers studying the detection of WBCs or classification of WBCs independently, few papers consider them together. This paper proposes an automatic detection and classification system for WBCs from peripheral blood images. It firstly proposes an algorithm to detect WBCs from the microscope images based on the simple relation of colors
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,
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and morphological operation. Then a granularity feature (pairwise rotation invariant co-occurrence local binary pattern, PRICoLBP feature) and SVM are applied to classify eosinophil and basophil from other WBCs firstly. Lastly, convolution neural networks are used to extract features in high level from WBCs automatically, and a random forest is applied to these features to recognize the other three kinds of WBCs: neutrophil, monocyte and lymphocyte. Some detection experiments on Cellavison database and ALL-IDB database show that our proposed detection method has better effect almost than iterative threshold method with less cost time, and some classification experiments show that our proposed classification method has better accuracy almost than some other methods.
Unmanned aerial vehicle (UAV)-satellite communication has drawn dramatic attention for its potential to build the integrated space-air-ground network and the seamless wide-area coverage. A key ...challenge to UAV-satellite communication is its unstable beam pointing due to the UAV navigation, which is a typical SatCom on-the-move scenario. In this paper, we propose a blind beam tracking approach for Ka-band UAV-satellite communication system, where UAV is equipped with a hybrid large-scale antenna array. The effects of UAV navigation are firstly released through the mechanical adjustment, which could approximately point the beam towards the target satellite through beam stabilization and dynamic isolation. Specially, the attitude information for mechanical adjustment can be realtimely derived from data fusion of low-cost sensors. Then, the precision of beam pointing is blindly refined through electrically adjusting the weight of the massive antennas, where an array structure based simultaneous perturbation algorithm is designed. Simulation results are provided to demonstrate the superiority of the proposed method over the existing ones.
The main problem with a robotic system arm is its sensitivity to time delays in the control process. Due to this problem, it is necessary to further optimize the control process of the system. One ...solution is to deal with the control accuracy and response speed issues of robotic arm joints, to improve the system's response performance and enhance the system's anti-interference ability. This paper proposes a speed feedforward and position control scheme for robotic arm joint control. The conclusion section shows that compared to traditional five-degree-of-freedom robotic arm systems, the addressed robotic arm control system has a lower tracking delay and better dynamic response performance. It can improve the system's response performance while also enhancing its anti-interference ability.
The millimeter-wave (mm-wave) massive multiple-input multiple-output (MIMO) system has gained much attention for its considerable improvement in system throughput. However, the cost of complex ...hardware, e.g., radio frequency (RF) chains, hinders it from practical deployment. In this paper, we propose an angle domain hybrid precoding and channel tracking method by exploring the spatial features of the mm-wave massive MIMO channel. The number of the effective spatial beams, or equivalently the RF chains, is enormously decreased via the operation of spatial rotation. The users are then scheduled by the angle division multiple access scheme, which groups users according to their direction of arrivals (DOAs). Meanwhile, a channel tracking method is designed for the subsequent data transmission through a small number of pilot symbols. Specifically, the channel information is divided into the DOA information and the gain information, where the DOA information is tracked by a modified unscented Kalman filter and the gain information is estimated from beam training. Numerical results are provided to corroborate our studies.
Alkaline condition (especially pH 10) has been demonstrated to be a promising method for short-chain fatty acid (SCFA) production from waste activated sludge anaerobic fermentation, because it can ...effectively inhibit the activities of methanogens. However, due to the limit of sludge solubilization rate, long fermentation time is required but SCFA yield is still limited. This paper reports a new pretreatment method for alkaline fermentation, i.e., using free nitrous acid (FNA) to pretreat sludge for 2 d, by which the fermentation time is remarkably shortened and meanwhile the SCFA production is significantly enhanced. Experimental results showed the highest SCFA production of 370.1 mg COD/g VSS (volatile suspended solids) was achieved at 1.54 mg FNA/L pretreatment integration with 2 d of pH 10 fermentation, which was 4.7- and 1.5-fold of that in the blank (uncontrolled) and sole pH 10 systems, respectively. The total time of this integration system was only 4 d, whereas the corresponding time was 15 d in the blank and 8 d in the sole pH 10 systems. The mechanism study showed that compared with pH 10, FNA pretreatment accelerated disruption of both extracellular polymeric substances and cell envelope. After FNA pretreatment, pH 10 treatment (1 d) caused 38.0% higher substrate solubilization than the sole FNA, which indicated that FNA integration with pH 10 could cause positive synergy on sludge solubilization. It was also observed that this integration method benefited hydrolysis and acidification processes. Therefore, more SCFA was produced, but less fermentation time was required in the integrated system.
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•FNA pretreatment enhanced SCFA production from WAS alkaline fermentation.•FNA pretreatment accelerated disruption of both EPS and cell envelope.•FNA + pH 10 caused positive synergies on fermentation process.
Unmanned aerial vehicle (UAV) communications could offer flexible scheduling, improved reliability, enhanced capacity over much wider range, and has become a key part of the space-air-ground ...integrated network. In this letter, we consider a communication system in millimeter wave band, where UAV serves as an airborne base station with multiple antennas, and propose a new flight control system-based channel tracking method. Specifically, the 3-D geometry channel model is formulated as a combination of the UAV movement state information and the channel gain information, where the former can be obtained by the sensor fusion of the flight control system, while the latter can be estimated through the pilot transmission. Simulation results are provided to verify the effectiveness of the proposed method.
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•The maximum P adsorption capacity of FeCl3-modified biochar was 111.0mg/g.•The P removal efficiency of Fe3+-attached biochar was better than Fe3O4.•Fe3+-modified biochar showed good ...P removal ability in wider concentration range.•P removal rate by Fe3+-modified biochar kept over 60% after 5 times reuse.
Excessive discharge of phosphate (P) into the surface water is the key factor to cause the eutrophication, so its removal has aroused much attention in recent years. In this study, different iron modification (chemical co-precipitation of Fe3+/Fe2+ or FeCl3 impregnation) was used to improve the phosphate adsorption capacity of waste activated sludge (WAS)-based biochar. Comparative tests demonstrated that the FeCl3-impregnated WAS-based biochar exhibited much superior phosphate adsorption capacity (111.0mg/g) in all as-prepared samples and performed well even under the interferences with pH and coexisting ions. X-ray diffraction (XRD) analyzes indicated that the iron in FeCl3-impregnated WAS-based biochar existed mainly in amorphous phase, as hematite and amorphous hydroxides forms, which was of great benefit to the phosphate adsorption. Besides, ligand exchange plays important role in the adsorption of phosphate. The WAS-based biochar kept over 60% phosphate removal efficiency after five recycles.
Aiming at the problems of low mapping accuracy, slow path planning efficiency, and high radar frequency requirements in the process of mobile robot mapping and navigation in an indoor environment, ...this paper proposes a four-wheel drive adaptive robot positioning and navigation system based on ROS. By comparing and analyzing the mapping effects of various 2D-SLAM algorithms (Gmapping, Karto SLAM, and Hector SLAM), the Karto SLAM algorithm is used for map building. By comparing the Dijkstra algorithm with the A* algorithm, the A* algorithm is used for heuristic searches, which improves the efficiency of path planning. The DWA algorithm is used for local path planning, and real-time path planning is carried out by combining sensor data, which have a good obstacle avoidance performance. The mathematical model of four-wheel adaptive robot sliding steering was established, and the URDF model of the mobile robot was established under a ROS system. The map environment was built in Gazebo, and the simulation experiment was carried out by integrating lidar and odometer data, so as to realize the functions of mobile robot scanning mapping and autonomous obstacle avoidance navigation. The communication between the ROS system and STM32 is realized, the packaging of the ROS chassis node is completed, and the ROS chassis node has the function of receiving speed commands and feeding back odometer data and TF transformation, and the slip rate of the four-wheel robot in situ steering is successfully measured, making the chassis pose more accurate. Simulation tests and experimental verification show that the system has a high precision in environment map building and can achieve accurate navigation tasks.
•This study estimated groundwater storage information of China.•The groundwater storage was certificated to be reliable and accurate.•The causes of groundwater storage changes in different basins ...were analyzed.
As an important freshwater resource, groundwater is of great significance to agriculture, industry, and daily life. The investigation of groundwater storage (GWS) in different regions of China is critical for water resource management and conservation. However, previous studies used different methods and data to monitor GWS in different regions of China, which made their results difficult to compare and cross validate. Here, we used a unified method by the Gravity Recovery and Climate Experiment (GRACE) satellite data and global models to study the variations of GWS in 10 major basins in China from April 2002 to December 2016. Results showed that GWS in the i) Songhua River basin (SRB), Liao River basin (LRB), Haihe River basin (HRB), Yellow River basin (YRB), Huaihe River basin (HHRB), and southeast basin (SEB) exhibited decreasing trends, ii) Yangtze River basin (YZRB) and Pearl River basin (PRB) presented increasing trends, and iii) southwest basin (SWB) and continental basin (CB) displayed both decreasing and increasing trends during the study period. These results were validated by comparing them with a large number of previous studies, which revealed that they were accurate and reliable. Comparing with the climate data and bulletin data, the analysis of causes for these trends indicated that drought and irrigation water-use led to a decline in GWS in several basins of northern China. The decreasing trend of GWS in the SEB was related to water use for production, whereas groundwater recharge from precipitation drove the increasing trends of GWS in the YZRB and PRB. In contrast, the wide geographical areas and complex factors of the SWB and CB led to the increasing–decreasing trends of GWS. This study enriches the GWS for China over the past decade, especially for SEB, PRB, and CB with rare GWS information. It will be helpful for the country’s groundwater resource management and systematic water conservation.
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