Analysis of Travel Hot Spots of Taxi Passengers Based on Community Detection

It is an important content of smart city research to study the activity track of urban residents, dig out the hot spot areas and spatial interaction patterns of different residents’ activities, and clearly understand the travel rules of urban residents' activities. This study used community detection to analyze taxi passengers’ travel hot spots based on taxi pick-up and drop-off data, combined with multisource information such as land use, in the main urban area of Nanjing. The study revealed that, for the purpose of travel, the modularity and anisotropy rate of the community where the passengers were picked up and dropped off were positively correlated during the morning and evening peak hours and negatively correlated at other times. Depending on the community structure, pick-up and drop-off points reached significant aggregation within the community, and interactions among the communities were also revealed. Based on the type of land use, as passengers' travel activity increased, travel hot spots formed clusters in urban spaces. After comparative verification, the results of this study were found to be accurate and reliable and can provide a reference for urban planning and traffic management.</jats:p

Mining Taxi Pick-Up Hotspots Based on Grid Information Entropy Clustering Algorithm

In view of the fact that the density-based clustering algorithm is sensitive to the input data, which results in the limitation of computing space and poor timeliness, a new method is proposed based on grid information entropy clustering algorithm for mining hotspots of taxi passengers. This paper selects representative geographical areas of Nanjing and Beijing as the research areas and uses information entropy and aggregation degree to analyze the distribution of passenger-carrying points. This algorithm uses a grid instead of original trajectory data to calculate and excavate taxi passenger hotspots. Through the comparison and analysis of the data of taxi loading points in Nanjing and Beijing, it is found that the experimental results are consistent with the actual urban passenger hotspots, which verifies the effectiveness of the algorithm. It overcomes the shortcomings of a density-based clustering algorithm that is limited by computing space and poor timeliness, reduces the size of data needed to be processed, and has greater flexibility to process and analyze massive data. The research results can provide an important scientific basis for urban traffic guidance and urban management

Mining Taxi Pick-Up Hotspots Based on Grid Information Entropy Clustering Algorithm

In view of the fact that the density-based clustering algorithm is sensitive to the input data, which results in the limitation of computing space and poor timeliness, a new method is proposed based on grid information entropy clustering algorithm for mining hotspots of taxi passengers. This paper selects representative geographical areas of Nanjing and Beijing as the research areas and uses information entropy and aggregation degree to analyze the distribution of passenger-carrying points. This algorithm uses a grid instead of original trajectory data to calculate and excavate taxi passenger hotspots. Through the comparison and analysis of the data of taxi loading points in Nanjing and Beijing, it is found that the experimental results are consistent with the actual urban passenger hotspots, which verifies the effectiveness of the algorithm. It overcomes the shortcomings of a density-based clustering algorithm that is limited by computing space and poor timeliness, reduces the size of data needed to be processed, and has greater flexibility to process and analyze massive data. The research results can provide an important scientific basis for urban traffic guidance and urban management.</jats:p

Analysis of Travel Hot Spots of Taxi Passengers Based on Community Detection

It is an important content of smart city research to study the activity track of urban residents, dig out the hot spot areas and spatial interaction patterns of different residents’ activities, and clearly understand the travel rules of urban residents' activities. This study used community detection to analyze taxi passengers’ travel hot spots based on taxi pick-up and drop-off data, combined with multisource information such as land use, in the main urban area of Nanjing. The study revealed that, for the purpose of travel, the modularity and anisotropy rate of the community where the passengers were picked up and dropped off were positively correlated during the morning and evening peak hours and negatively correlated at other times. Depending on the community structure, pick-up and drop-off points reached significant aggregation within the community, and interactions among the communities were also revealed. Based on the type of land use, as passengers' travel activity increased, travel hot spots formed clusters in urban spaces. After comparative verification, the results of this study were found to be accurate and reliable and can provide a reference for urban planning and traffic management

Synthesis of micron-particle-size HZSM-5 zeolite with different Si/Al ratio and its catalytic activity for toluene methanol alkylation reaction

HZSM-5 molecular sieve is one of the commonly used catalysts for the alkylation of toluene with methanol to para-xylene (PX). This study introduces a one-step method to directly prepare microscale HZSM-5 catalysts with suitable pore structure and acidity. Specifically, this paper combined crystal seed regulation of the morphology of HZSM-5 and adjusted the Si/Al ratios of the precursor solution for HZSM-5 synthesis to regulate the acidic phase of the HZSM-5. It analyzed the phase composition, pore structure parameters, microstructure, and acidity of HZSM-5 molecular sieve through X-ray diffraction, N2 adsorption desorption, SEM, NH3 temperature programmed desorption, pyridine infrared spectroscopy, etc. This study investigated the catalytic performance of HZSM-5 in the alkylation of toluene with methanol to PX, and explored the effects of pore structure and acidity on the catalytic performance. Results indicate that in the hydrothermal crystallization method, the crystal seeds and aluminum content in the synthesis solution have a significant impact on the acidity and morphology structure of the HZSM-5 molecular sieve. The HZSM-5 (150)molecular sieve catalyst with 5μm grain size exhibits 60% PX selectivity and 11% toluene conversion rate in the evaluation reaction of toluene methanol alkylation due to its longer diffusion path and more suitable acidic sites. By fine-tuning the pores and acidic sites of HZSM-5 molecular sieve, the selectivity for PX has been effectively improved, providing new methods and approaches for the design of shape-selective catalysts

Analysis of correlation between thrombelastography and severity of coronary artery lesions in patients with acute coronary syndrome

Objective To investigate the correlation between thrombelastography (TEG) and the severity of coronary artery lesions in patients with acute coronary syndrome (ACS). Methods A total of 130 patients admitted to the Department of Cardiology of our hospital who underwent coronary angiography and had positive results were consecutively recruited as the ACS group. Meanwhile, 86 patients with ACS excluded by coronary angiography during the same period were selected as the control group. TEG parameters [reaction time (R time), clotting time (K time), blood clot formation rate (Angle α), maximum amplitude (MA)], triglycerides, total cholesterol, high-density lipoprotein, low-density lipoprotein, lactate dehydrogenase, and platelet levels were measured for all subjects. The differences in TEG indicators between the ACS group and control group were compared to identify potential risk factors for ACS. In ACS patients, the correlations of TEG parame-ters with laboratory-related indicators and the severity of coronary artery lesions assessed by the Gensini score were evalua-ted and analyzed. Logistic regression analysis was employed to evaluate the influencing factors of TEG in ACS patients with different numbers of coronary artery lesions. After adjusting for confounding factors, the independent predictive effect of TEG on the risk of ACS was further evaluated. Results The TEG parameters (R time and K time) in the ACS group were lower than those in the control group, and the difference was statistically significant (P&lt;0.01). TEG parameters (R time and K time) were negatively correlated with the Gensini score (rR time=-0.302 3, rK time=-0.257 4, P&lt;0.01). Multivariate logistic regression analysis showed that after adjusting for confounding factors, when TEG (K time) was considered as a categorical variable, Q4 (K time &gt;2.10) was an independent protective factor against ACS (OR=0.34, 95% CI: 0.13-0.87, P&lt;0.05). Receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) of R time and K time for diagnosing ACS was 0.781 0 and 0.605 1, respectively. The TEG parameter (R time) showed a sensitivity of 73.26% and a specificity of 70.00% for diagnosing ACS, while the K time showed a sensitivity of 65.38% and a specificity of 60.47%. Conclusion TEG is associated with ACS and the severity of coronary artery lesions and may serve as an independent predictor of the severity of coronary artery lesions in patients with ACS, which can provide a strong basis for determining whether further invasive diagnosis is needed

Effects of Silicalite-1 Coating on the p-Xylene Selectivity and Catalytic Stability of HZSM-5 in Toluene Methylation with Methanol

The methanol&ndash;toluene alkylation process over zeolites catalysts offers a promising route for the production of p-xylene from low-cost feedstocks. Herein, we present a catalyst by preparing a core-shell aluminosilicate zeolite with an epitaxial silicalite-1 shell that passivates acid sites on the exterior surfaces. The para-selectivity was obviously increased due to the inhibition of the unselective isomerization of p-xylene over the external acid sites, and the open porous structure of the silicalite-1 shell ensured the mass transfer of reactants and products. Meanwhile, the carbon deposition was suppressed over HZSM-5@silicalite-1 catalysts, as a result of the decreased external acid sites. Furthermore, pulse chromatographic experiments revealed that the silicalite-1 coating could also improve the separation efficiency of p-xylene over o-xylene and m-xylene, due to the steric hindrance and extended diffusion path, resulting in a higher selectivity for p-xylene compared to that of the parent HZSM-5. The HZSM-5@4%S-1 catalyst showed the highest p-xylene selectivity (&gt;80%) and methanol efficiency (66%), with good catalytic stability throughout the 170 h reaction time