Avoiding crystallization while maintaining the original microstructure and mechanical properties of the material are long-term goals of laser welding of Zr-based bulk metallic glass(BMG).In this paper,the effect of pu...Avoiding crystallization while maintaining the original microstructure and mechanical properties of the material are long-term goals of laser welding of Zr-based bulk metallic glass(BMG).In this paper,the effect of pulsed laser welding parameters on the microstructure,crystallization degree,and mechanical properties of Zr57Nb5Cu15.4Ni12.6Al10 BMG is investigated.Non-crystallized welding forming of a zirconium-based amorphous alloy is achieved by optimizing the process parameters of pulsed laser welding.The crystallization degree of Zr-based BMG is mainly determined by the welding speed and power.The welding depth and crystallization area fraction increase with an increase in the effective peak power density.The optimized welding process can effectively reduce the heat accumulation of the weld,thus avoiding crystallization.The flexural strength of the weld can be maintained at 96.5%of the matrix.展开更多
During the oil production, in order to monitor the working conditions of an electrical submersible pump （ESP）,an electrical current recorder is used to monitor the electric motor current of an ESP. The recorder char...During the oil production, in order to monitor the working conditions of an electrical submersible pump （ESP）,an electrical current recorder is used to monitor the electric motor current of an ESP. The recorder charts indicate various working conditions of the ESP. Subtle malfunctions or abnormal problems of the ESP can be detected and further analyzed from various features of these current curves on the recording charts. Presently, these current charts are manually read and analyzed in oil fields. In this paper, a diagnosis expert system is presented for automatically analyzing these current recording charts and identifying the working condition of the ESP. This expert system includes an open knowledge base, which can be updated or enriched according to the identified features of the current curves on the recording charts, and a condition monitoring and failure pattern recognition method, which is called ＂pick-up method of feature of the recording chart＂, and can be correctly applied in most cases. It has been shown that this expert system can effectively improve the accuracy and efficiency of failure diagnosis and working condition monitoring of ESPs.展开更多
Geminal dinitropropyl ester plasticizers(DNPEPs) possess excellent energetic performances which provide good potentials as insensitive plasticizer. In this study, we design and synthesize DNPEPs with different alkane ...Geminal dinitropropyl ester plasticizers(DNPEPs) possess excellent energetic performances which provide good potentials as insensitive plasticizer. In this study, we design and synthesize DNPEPs with different alkane chain parts, and systematically investigate their structure-property relationships.Results show that DNPEPs have impact sensitivities all higher than 25.2 J, thermal decomposition temperatures all higher than 254 ℃, and glass transition temperatures(T_(g)) lower than-90 ℃.Furthermore, the effects of DNPEPs as plasticizer are studied on hydroxyl terminated polybutadiene(HTPB) in detail, including the viscosity, glass transition temperatures and others. It is noteworthy that 2,2-dinitropropyl nonanoate(DNPNc) among these DNPEPs exhibits the most expected simultaneous tuning effects on both viscosity and T_(g) of HTPB systems, providing favorable potentials to replace the conventional plastizers as dioctyl sebacate(DOS) in the HTPB based propellants and explosives.展开更多
Lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their development.The primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid ...Lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their development.The primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid boron.In this study,we developed a novel approach for efficiently activating boron by introducing alkali metal compounds into the conventional MgO–B system.This approach can be adopted to form various low-melting-point AM–Mg–B–O growth systems.These growth systems have improved catalytic capability and reactivity even under low-temperature conditions,facilitating the synthesis of BNNTs at temperatures as low as 850℃.In addition,molecular dynamics simulations based on density functional theory theoretically demonstrate that the systems maintain a liquid state at low temperatures and interact with N atoms to form BN chains.These findings offer novel insights into the design of boron activation and are expected to facilitate research on the low-temperature synthesis of BNNTs.展开更多
<strong>Objective: </strong>This study is to analyze correlation between traditional Chinese medicine (TCM) syndrome distribution characteristics and prognosis of hypertensive intracerebral hemorrhage (HIC...<strong>Objective: </strong>This study is to analyze correlation between traditional Chinese medicine (TCM) syndrome distribution characteristics and prognosis of hypertensive intracerebral hemorrhage (HICH) operation. <strong>Methods: </strong>In this study, a total of 150 patients who had received HICH operation from April, 2017 to December, 2020 in our hospital and conformed to inclusion standards were selected. According to classification of TCM syndromes, amount of bleeding of patients was recorded through multiple radiological technologies, baseline information was collected, and prognosis was investigated. The final event was long-term follow-up visit of all-cause mortalities. Moreover, correlation between prognosis and TCM syndromes was analyzed. <strong>Results:</strong> It found through investigations that there are no statistically significant differences in composition ratio of TCM syndromes among patients with different genders and different age ranges (P > 0.05). Among so many TCM syndromes, bleeding amount of patients with declining vitality and distraction is the highest, while bleeding amount of patients with stirring wind due to yin deficiency is the lowest. With respect NIHSS scores, the patients with declining vitality and distraction show the highest NIHSS scores at admission and 10 d of the course of the disease, followed by patients with upward disturbance of wind-fire. There are statistically significant differences among these two groups (P < 0.05). In this study, follow-up visits are performed to all 150 patients and the average follow-up visit time ranges within 2 - 15 months. A total of 13 deaths are reported. Number of all-cause deaths has statistically significant differences among different syndromes (P < 0.05). <strong>Conclusions:</strong> Evolutionary characteristics of TCM syndromes of HICH are manifested by development from evidence-based symptoms to deficiency syndromes. Different syndromes are correlated with prognosis of patients. On the one hand, this can be used as an objective index for TCM syndrome classification. On the other hand, this is conducive to judge prognosis recovery of patients and to apply the corresponding symptomatic treatment.展开更多
基金Supported by Guangdong Major Project of Basic and Applied Research,China(Grant No.2019B030302010)National Natural Science Foundation of China (Grant Nos.51735003,52205456)
文摘Avoiding crystallization while maintaining the original microstructure and mechanical properties of the material are long-term goals of laser welding of Zr-based bulk metallic glass(BMG).In this paper,the effect of pulsed laser welding parameters on the microstructure,crystallization degree,and mechanical properties of Zr57Nb5Cu15.4Ni12.6Al10 BMG is investigated.Non-crystallized welding forming of a zirconium-based amorphous alloy is achieved by optimizing the process parameters of pulsed laser welding.The crystallization degree of Zr-based BMG is mainly determined by the welding speed and power.The welding depth and crystallization area fraction increase with an increase in the effective peak power density.The optimized welding process can effectively reduce the heat accumulation of the weld,thus avoiding crystallization.The flexural strength of the weld can be maintained at 96.5%of the matrix.
文摘During the oil production, in order to monitor the working conditions of an electrical submersible pump （ESP）,an electrical current recorder is used to monitor the electric motor current of an ESP. The recorder charts indicate various working conditions of the ESP. Subtle malfunctions or abnormal problems of the ESP can be detected and further analyzed from various features of these current curves on the recording charts. Presently, these current charts are manually read and analyzed in oil fields. In this paper, a diagnosis expert system is presented for automatically analyzing these current recording charts and identifying the working condition of the ESP. This expert system includes an open knowledge base, which can be updated or enriched according to the identified features of the current curves on the recording charts, and a condition monitoring and failure pattern recognition method, which is called ＂pick-up method of feature of the recording chart＂, and can be correctly applied in most cases. It has been shown that this expert system can effectively improve the accuracy and efficiency of failure diagnosis and working condition monitoring of ESPs.
基金financial support of the National Natural Science Foundation of China (21875185)。
文摘Geminal dinitropropyl ester plasticizers(DNPEPs) possess excellent energetic performances which provide good potentials as insensitive plasticizer. In this study, we design and synthesize DNPEPs with different alkane chain parts, and systematically investigate their structure-property relationships.Results show that DNPEPs have impact sensitivities all higher than 25.2 J, thermal decomposition temperatures all higher than 254 ℃, and glass transition temperatures(T_(g)) lower than-90 ℃.Furthermore, the effects of DNPEPs as plasticizer are studied on hydroxyl terminated polybutadiene(HTPB) in detail, including the viscosity, glass transition temperatures and others. It is noteworthy that 2,2-dinitropropyl nonanoate(DNPNc) among these DNPEPs exhibits the most expected simultaneous tuning effects on both viscosity and T_(g) of HTPB systems, providing favorable potentials to replace the conventional plastizers as dioctyl sebacate(DOS) in the HTPB based propellants and explosives.
基金supported by the National Natural Science Foundation of China(No.51972162)the Fundamental Research Funds for the Central Universities(No.2024300440).
文摘Lowering the synthesis temperature of boron nitride nanotubes(BNNTs)is crucial for their development.The primary reason for adopting a high temperature is to enable the effective activation of highmelting-point solid boron.In this study,we developed a novel approach for efficiently activating boron by introducing alkali metal compounds into the conventional MgO–B system.This approach can be adopted to form various low-melting-point AM–Mg–B–O growth systems.These growth systems have improved catalytic capability and reactivity even under low-temperature conditions,facilitating the synthesis of BNNTs at temperatures as low as 850℃.In addition,molecular dynamics simulations based on density functional theory theoretically demonstrate that the systems maintain a liquid state at low temperatures and interact with N atoms to form BN chains.These findings offer novel insights into the design of boron activation and are expected to facilitate research on the low-temperature synthesis of BNNTs.
文摘<strong>Objective: </strong>This study is to analyze correlation between traditional Chinese medicine (TCM) syndrome distribution characteristics and prognosis of hypertensive intracerebral hemorrhage (HICH) operation. <strong>Methods: </strong>In this study, a total of 150 patients who had received HICH operation from April, 2017 to December, 2020 in our hospital and conformed to inclusion standards were selected. According to classification of TCM syndromes, amount of bleeding of patients was recorded through multiple radiological technologies, baseline information was collected, and prognosis was investigated. The final event was long-term follow-up visit of all-cause mortalities. Moreover, correlation between prognosis and TCM syndromes was analyzed. <strong>Results:</strong> It found through investigations that there are no statistically significant differences in composition ratio of TCM syndromes among patients with different genders and different age ranges (P > 0.05). Among so many TCM syndromes, bleeding amount of patients with declining vitality and distraction is the highest, while bleeding amount of patients with stirring wind due to yin deficiency is the lowest. With respect NIHSS scores, the patients with declining vitality and distraction show the highest NIHSS scores at admission and 10 d of the course of the disease, followed by patients with upward disturbance of wind-fire. There are statistically significant differences among these two groups (P < 0.05). In this study, follow-up visits are performed to all 150 patients and the average follow-up visit time ranges within 2 - 15 months. A total of 13 deaths are reported. Number of all-cause deaths has statistically significant differences among different syndromes (P < 0.05). <strong>Conclusions:</strong> Evolutionary characteristics of TCM syndromes of HICH are manifested by development from evidence-based symptoms to deficiency syndromes. Different syndromes are correlated with prognosis of patients. On the one hand, this can be used as an objective index for TCM syndrome classification. On the other hand, this is conducive to judge prognosis recovery of patients and to apply the corresponding symptomatic treatment.
