Current research on autonomous mobile robots focuses primarily on perceptual accuracy and autonomous performance.In commercial and domestic constructions,concrete,wood,and glass are typically used.Laser and visual map...Current research on autonomous mobile robots focuses primarily on perceptual accuracy and autonomous performance.In commercial and domestic constructions,concrete,wood,and glass are typically used.Laser and visual mapping or planning algorithms are highly accurate in mapping wood panels and concrete walls.However,indoor and outdoor glass curtain walls may fail to perceive these transparent materials.In this study,a novel indoor glass recognition and map optimization method based on boundary guidance is proposed.First,the status of glass recognition techniques is analyzed comprehensively.Next,a glass image segmentation network based on boundary data guidance and the optimization of a planning map based on depth repair are proposed.Finally,map optimization and path-planning tests are conducted and compared using different algorithms.The results confirm the favorable adaptability of the proposed method to indoor transparent plates and glass curtain walls.Using the proposed method,the recognition accuracy of a public test set increases to 94.1%.After adding the planning map,incorrect coverage redundancies for two test scenes reduce by 59.84%and 55.7%.Herein,a glass recognition and map optimization method is proposed that offers sufficient capacity in perceiving indoor glass materials and recognizing indoor no-entry regions.展开更多
Ash deposition is a form of particulate fouling, and appears usually in boiler economizers. The ash deposition increases capital expenditure, energy input and maintenance costs. An analog experiment for monitoring ash...Ash deposition is a form of particulate fouling, and appears usually in boiler economizers. The ash deposition increases capital expenditure, energy input and maintenance costs. An analog experiment for monitoring ash deposition was performed from the analogous objective of a 410 t/h boiler economizer to verify the rationality and reliability of the ash-deposition-monitoring model presented in order to increase the security and economy in economizer running. The analog experiment platform is a tube-shell exchanger that conforms well to the conditions of a self-modeling area. The analog flue gas in the shell side is the heated air mixed with ash, and in the tube side the fluid is water heated by the flue gas. The fluid state in the water side and the flue gas side follows the second self-modeling area. A 4-factor-3-level orthogonal table was used to schedule 9 operation conditions of orthogonal experiment, with the 4 factors being heat power, flue gas velocity, ashes grain diameter and adding ashes quantity while the three levels are different values due to different position classes in every factor. The ash deposition thermal resistances is calculated by the model with the measure parameters of temperature and pressure drop. It shows that the values of the ash deposition thermal resistances gradually increase up to a stable state. And the experimental results are reliable by F testing method at α= 0.001. Therefore, the model can be applied in online monitoring of ash deposition in a boiler economizers in power plants and provides scientific decision on ash deposition prediction and sootblowing.展开更多
An average failure index method based on accurate FEA was proposed for the tensile strength prediction of composite out-of-plane adhesive-bonded π joints. Based on the simple and independent maximum stress failure cr...An average failure index method based on accurate FEA was proposed for the tensile strength prediction of composite out-of-plane adhesive-bonded π joints. Based on the simple and independent maximum stress failure criterion, the failure index was introduced to characterize the degree of stress components close to their corresponding material strength. With a brief load transfer analysis, the weak fillers were prominent and further detailed discussion was performed. The maximum value among the average failure indices which were related with different stress components was filtrated to represent the failure strength of the critical surface, which is either the two curved upside surfaces or the bottom plane of the fillers for composite π joints. The tensile strength of three kinds of π joints with different material systems, configurations and lay-ups was predicted by the proposed method and corresponding experiments were conducted. Good agreements between the numerical and experimental results give evidence of the effectiveness of the proposed method. In contrast to the existed time-consuming strength prediction methods, the proposed method provides a capability of quickly assessing the failure of complex out-of-plane joints and is easy and convenient to be widely utilized in engineering.展开更多
Daqing as a great oil-producing city are probably unaware that it has developed into a booming industrial base in China.It became an industrialized city in the 1960's when the discovery of oil & gas was made i...Daqing as a great oil-producing city are probably unaware that it has developed into a booming industrial base in China.It became an industrialized city in the 1960's when the discovery of oil & gas was made in Songliao Basin.展开更多
We construct a new measure to capture corporate political connections, which is based on the amount a corporation spends on socializing with government officials. We examine the validity of this measure using the exog...We construct a new measure to capture corporate political connections, which is based on the amount a corporation spends on socializing with government officials. We examine the validity of this measure using the exogenous turnover of top local officials and find that firms increase their political networking expenditures when top local officials are replaced. Compared to state-owned enterprises(SOEs), non-state-owned enterprises(non-SOEs) react more aggressively to changes in local officials, which implies that non-SOEs have stronger incentives to build political connections with officials through social intercourse. We also find that firms located in regions with low levels of marketization react more aggressively to the turnover of local politicians. In addition, we find a positive effect of corporate political socializing expenditures on corporate performance and valuation, which suggests that political connections built through social intercourse benefit corporations.展开更多
基金Supported by National Key Research and Development Program of China(Grant No.2022YFB4700400).
文摘Current research on autonomous mobile robots focuses primarily on perceptual accuracy and autonomous performance.In commercial and domestic constructions,concrete,wood,and glass are typically used.Laser and visual mapping or planning algorithms are highly accurate in mapping wood panels and concrete walls.However,indoor and outdoor glass curtain walls may fail to perceive these transparent materials.In this study,a novel indoor glass recognition and map optimization method based on boundary guidance is proposed.First,the status of glass recognition techniques is analyzed comprehensively.Next,a glass image segmentation network based on boundary data guidance and the optimization of a planning map based on depth repair are proposed.Finally,map optimization and path-planning tests are conducted and compared using different algorithms.The results confirm the favorable adaptability of the proposed method to indoor transparent plates and glass curtain walls.Using the proposed method,the recognition accuracy of a public test set increases to 94.1%.After adding the planning map,incorrect coverage redundancies for two test scenes reduce by 59.84%and 55.7%.Herein,a glass recognition and map optimization method is proposed that offers sufficient capacity in perceiving indoor glass materials and recognizing indoor no-entry regions.
文摘Ash deposition is a form of particulate fouling, and appears usually in boiler economizers. The ash deposition increases capital expenditure, energy input and maintenance costs. An analog experiment for monitoring ash deposition was performed from the analogous objective of a 410 t/h boiler economizer to verify the rationality and reliability of the ash-deposition-monitoring model presented in order to increase the security and economy in economizer running. The analog experiment platform is a tube-shell exchanger that conforms well to the conditions of a self-modeling area. The analog flue gas in the shell side is the heated air mixed with ash, and in the tube side the fluid is water heated by the flue gas. The fluid state in the water side and the flue gas side follows the second self-modeling area. A 4-factor-3-level orthogonal table was used to schedule 9 operation conditions of orthogonal experiment, with the 4 factors being heat power, flue gas velocity, ashes grain diameter and adding ashes quantity while the three levels are different values due to different position classes in every factor. The ash deposition thermal resistances is calculated by the model with the measure parameters of temperature and pressure drop. It shows that the values of the ash deposition thermal resistances gradually increase up to a stable state. And the experimental results are reliable by F testing method at α= 0.001. Therefore, the model can be applied in online monitoring of ash deposition in a boiler economizers in power plants and provides scientific decision on ash deposition prediction and sootblowing.
基金Funded by the National Natural Science Foundation of China(Nos.11372020 and 10902004)
文摘An average failure index method based on accurate FEA was proposed for the tensile strength prediction of composite out-of-plane adhesive-bonded π joints. Based on the simple and independent maximum stress failure criterion, the failure index was introduced to characterize the degree of stress components close to their corresponding material strength. With a brief load transfer analysis, the weak fillers were prominent and further detailed discussion was performed. The maximum value among the average failure indices which were related with different stress components was filtrated to represent the failure strength of the critical surface, which is either the two curved upside surfaces or the bottom plane of the fillers for composite π joints. The tensile strength of three kinds of π joints with different material systems, configurations and lay-ups was predicted by the proposed method and corresponding experiments were conducted. Good agreements between the numerical and experimental results give evidence of the effectiveness of the proposed method. In contrast to the existed time-consuming strength prediction methods, the proposed method provides a capability of quickly assessing the failure of complex out-of-plane joints and is easy and convenient to be widely utilized in engineering.
文摘Daqing as a great oil-producing city are probably unaware that it has developed into a booming industrial base in China.It became an industrialized city in the 1960's when the discovery of oil & gas was made in Songliao Basin.
基金Founded by Sun Yat-sen University and City University of Hong Kong
文摘We construct a new measure to capture corporate political connections, which is based on the amount a corporation spends on socializing with government officials. We examine the validity of this measure using the exogenous turnover of top local officials and find that firms increase their political networking expenditures when top local officials are replaced. Compared to state-owned enterprises(SOEs), non-state-owned enterprises(non-SOEs) react more aggressively to changes in local officials, which implies that non-SOEs have stronger incentives to build political connections with officials through social intercourse. We also find that firms located in regions with low levels of marketization react more aggressively to the turnover of local politicians. In addition, we find a positive effect of corporate political socializing expenditures on corporate performance and valuation, which suggests that political connections built through social intercourse benefit corporations.
