Introduction: Voluntary assault and injuries are acts that damage the physical and psychological integrity of a human being. WHO in its global report on violence and health estimates that in 2000, 1.6 million people w...Introduction: Voluntary assault and injuries are acts that damage the physical and psychological integrity of a human being. WHO in its global report on violence and health estimates that in 2000, 1.6 million people worldwide died as a result of self-harm, interpersonal or collective violence, resulting in an overall rate adjusted by age of 28.8 per 100,000 population. Because of the seriousness of this phenomenon and the heavy socio-economic and health consequences that they generate, it seemed important to us to undertake this study, which aimed to study the deliberate injuries in the emergency unite of the Gabriel Touré Teaching Hospital in Bamako. Material and methods: This was a descriptive and cross-sectional study with a prospective study from September 1st, 2016 to August 31st, 12 months, covering 295 patients, including any patient received for voluntary injury consultation with a workable medical record and/or a full investigation record with or without requisition. Our data were collected on individual survey cards and subsequently analyzed with Word, Excel, IBM SPSS Statistics 22 software. Results: The majority of victims of assault and bodily injury were male with 83.1%;with a sex ratio of 4.9, the 18 to 28 age group was the most concerned with 163 cases of the 295 cases in our study, 55.2%. The extremes were 6 and 100 years old with an ectype at 11.08. The most affected ethnic group was Bambara with 38.6% (n = 114) followed by Fulani with 15.6% (n = 46). Students were the most affected at 24.7% (n = 73), followed by traders at 10%. The victims coming from outside Bamako are the most predominant with 22.4% (n = 66) followed by those of commune IV of Bamako 15.6% (n = 46). In 92.2% of the cases the mechanism was direct with n = 272. Of the lesions recorded in our study, wounds came first with 53.2% of cases. Radiography was the most used imaging at 44.7% (n = 89) followed by computed tomography at 34.7% (n = 69). The hemoperitoneum objectified by abdominal ultrasound represented 29.3% (n = 12). Fractures embarrure associated with bruising-hemorrhagic bruises were the most predominant with 13.4% (n = 10) objectified by brain scan. Conclusion: We note that the phenomenon of violence has reached worrying proportions, especially among young adults, particularly among students and is observed in all so-cio-professional layers. The polymorphism of these injuries caused by the predominant use of knives must draw the attention of our authorities to take measures to reduce these aggressions.展开更多
Images provided by the author unless otherwise stated■This summer the first major U.S.solo exhibition by leading Taiwan Residents artist Chen Chieh-jen took place at Manhattan's Asia Society.The exhibition 'C...Images provided by the author unless otherwise stated■This summer the first major U.S.solo exhibition by leading Taiwan Residents artist Chen Chieh-jen took place at Manhattan's Asia Society.The exhibition 'Condensation' united five silent films that address a variety of social topics into a cohesive unit. The films reflect the mind of someone who came to artistic maturity during a rapidly changing political environment in Taiwan.展开更多
Unusual head trauma is rare with various mechanisms of occurrence. The injuries can be similar to those of road accidents but sometimes with significant complexities. The objective was to determine the frequency of th...Unusual head trauma is rare with various mechanisms of occurrence. The injuries can be similar to those of road accidents but sometimes with significant complexities. The objective was to determine the frequency of this pathology in our practice, describe the different mechanisms and report the craniocerebral lesions caused by this type of trauma. Materials and Method: This was a descriptive study with retrospective collection spread over a period of 3 years. After selecting the files, the patients and/or their companions were contacted by telephone to inquire about them and then returned to the consultation for reassessment. Disease history and information were obtained from patients’ medical records. Result: The frequency of this pathology was 1.78% and his incidence was 0.4 cases per month. The average age of the patients was 13.47 years. All the victims were male. 41.17% of patients were in school. The mechanisms of trauma were the hoof blow 47.1%, the horn blow 29.4% and the stone blow 11.7% respectively. 23.5% of patients were confused and 11.7% children were in coma. One patient presented an anisocoria. The motor deficit was present in 5 cases. CT-scan made it possible to highlight a skull depressing fracture 58.8% and confirm a craniocerebral wound in 35.3%. The average time between patient admission to hospital and completion of surgery was 24.5 hours. The surgery had consisted of the trimming of cranio-cerebral wounds, exploration, duroplasty and lifting of skull depressing fracture. After 15 months of follow-up, the evolution was favorable in 53.3%, the morbidity was 33.4% and the mortality 17.6%. Conclusion: These are rare but serious conditions because they are fatal and disabling. An early and multidisciplinary management can hope to have a good favorable.展开更多
The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based ...The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in converter. A three-step method was utilized in the hybrid model. First, the oxygen consumption volume was predicted by the OBM model and DNN model, respectively. Second, a more accurate oxygen consumption volume was obtained by integrating the OBM model and DNN model. Finally, the converter oxygen blowing time was calculated according to the oxygen consumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data collected from an integrated steel plant in China, and compared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3 hidden layer layers, 32-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability compared with other models. The predicted hit ratio of oxygen consumption volume within the error±300 m^(3)is 96.67%;determination coefficient (R^(2)) and root mean square error (RMSE) are0.6984 and 150.03 m^(3), respectively. The oxygen blow time prediction hit ratio within the error±0.6 min is 89.50%;R2and RMSE are0.9486 and 0.3592 min, respectively. As a result, the proposed model can effectively predict the oxygen consumption volume and oxygen blowing time in the converter.展开更多
The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor...The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.展开更多
Cryogenic insulation material rigid polyurethane(PU)foams were developed using bio-based and recycled feedstock.Polyols obtained from tall oil fatty acids produced as a side stream of wood biomass pulping and recycled...Cryogenic insulation material rigid polyurethane(PU)foams were developed using bio-based and recycled feedstock.Polyols obtained from tall oil fatty acids produced as a side stream of wood biomass pulping and recycled polyethylene terephthalate were used to develop rigid PU foam formulations.The 4th generation physical blowing agents with low global warming potential and low ozone depletion potential were used to develop rigid PU foam cryogenic insulation with excellent mechanical and thermal properties.Obtained rigid PU foams had a thermal conductivity coefficient as low as 0.0171 W/m·K and an apparent density of 37-40 kg/m^(3).The developed rigid PU foams had anisotropic compression strength properties,which were higher parallel to the foaming direction.Moreover,the compression strength was also influenced by the type of applied bio-based polyol.The bio-based polyols with higher OH group functionality delivered higher crosslinking density of polymer matrix;thus,the mechanical properties were also higher.The mechanical strength of the foams increased when materials were tested at liquid nitrogen temperature due to the stiffening of the polymer matrix.The thermal properties of the developed materials were determined using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis methods.Lastly,the developed rigid PU foams had good adhesion to the aluminium substrate before and after applying cyroshock and an excellent safety coefficient of 4-5.Rigid PU foams developed using Solstice LBA delivered adhesion strength of~0.5 MPa and may be considered for application as cryogenic insulation in the aerospace industry.展开更多
We consider the initial-boundary value problem for finitely degenerate parabolic equation. We first give sufficient conditions for the blow-up and global existence of the parabolic equation at high initial energy leve...We consider the initial-boundary value problem for finitely degenerate parabolic equation. We first give sufficient conditions for the blow-up and global existence of the parabolic equation at high initial energy level. Then, we establish the existence of solutions blowing up in finite time with initial data at arbitrary energy level. Finally, we estimate the upper bound of the blow-up time under certain conditions.展开更多
艺术家乔希·辛普森制作玻璃球,并且他做的玻璃球会藏在地球上的任意一个地方等待人们发现。Artist Josh Simpson creates tiny glass planets that are meant to delight his audi-ence.Decades ago,he gave glassblowing demonstr...艺术家乔希·辛普森制作玻璃球,并且他做的玻璃球会藏在地球上的任意一个地方等待人们发现。Artist Josh Simpson creates tiny glass planets that are meant to delight his audi-ence.Decades ago,he gave glassblowing demonstrations to local students in his studio in Springfield,Massachusetts.Simp-son started by showing the middle-school students how to make marbles(弹子).展开更多
This article discusses and analyzes the law of nitrogen increase in liquid steel and the main factors affect-ing the nitrogen increasing of molten steel,through the way of adding nitrogen to molten steel by bottom blo...This article discusses and analyzes the law of nitrogen increase in liquid steel and the main factors affect-ing the nitrogen increasing of molten steel,through the way of adding nitrogen to molten steel by bottom blowing nitrogen gas in LF refining process.It is considered that the main factors affecting the nitrogen increasing instability of molten steel are the initial temperature of LF refining,nitrogen relative element,surface active elements[O]and[S]of steel liquid,and bottom blowing rate of ladle.The large-scale production practice shows that T[O]not more than 50×10-6 and[S]is not more than 0.020 in LF refining at the initial temperature of not less than 1570.The liquid steel nitrogen enrichment test is carried out by ladle bottom blowing nitrogen gas after 20 min of refining,the flow rate is set as(6.0~7.0)NL/min per ton,and it is turned to 2 NL/min at 6 min before the end of refining,the nitrogen increasing rate of liquid steel is basically stable at(5~6)×10-6 per minute.展开更多
The unfolding global financial crisis is arousing jitters about another round of heavy blows to the world economy, which may be intensified by the possible U.S. government takeover of Citigroup Inc. and Bank of Americ...The unfolding global financial crisis is arousing jitters about another round of heavy blows to the world economy, which may be intensified by the possible U.S. government takeover of Citigroup Inc. and Bank of America Corp. lg, Chief Economist of the Asia-Pacific region for Credit Suisse First Boston (Hong Kong ) Ltd., published an article in the Securities Market Weekly, warning about five other major crashes that might dampen global economic recovery. Edited excerpts follow.展开更多
There is a beautiful city in southwestern Germany,lying on the southern bank of the Rhine River,which has flowed quietly nearby since ancient times.The city was the hometown of Johannes Gutenberg,the inventor of moder...There is a beautiful city in southwestern Germany,lying on the southern bank of the Rhine River,which has flowed quietly nearby since ancient times.The city was the hometown of Johannes Gutenberg,the inventor of modern typography,as well as of an excellent Bundesliga soccer team.It features a combination of ancient flavor and modern fashion,with not only time-honored churches展开更多
A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a...A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.展开更多
BACKGROUND Many cases of emphysema associated with blow-out fractures occur before surgery due to trauma.However,emphysema can occur even after surgery,and most of such cases are managed conservatively and allowed to ...BACKGROUND Many cases of emphysema associated with blow-out fractures occur before surgery due to trauma.However,emphysema can occur even after surgery,and most of such cases are managed conservatively and allowed to resolve.Swelling in the periorbital area due to emphysema that occurs after surgery can make early recovery difficult.CASE SUMMARY Herein,we describe a case of postoperative subcutaneous emphysema that was treated using a simple needle aspiration method.A 48-year-old male patient visited the hospital with a blow-out fracture of the left medial orbital wall and nasal bone fracture.One day postoperatively,swelling and crepitus in the left periorbital area were observed,and follow-up computed tomography showed emphysema in the left periorbital subcutaneous area.Needle aspiration using an 18-gauge needle and syringe was used to relieve the emphysema.The symptoms of sudden swelling improved immediately,and no recurrence was observed.CONCLUSION We conclude that needle aspiration is a useful method that could help in relieving symptom,resolving discomfort,and enabling early return to daily life in patients with postoperative subcutaneous emphysema.展开更多
Through systematical experiment design, the physical blowing agent(PBA) mass loss of bio-based polyurethane rigid foam(PURF)in the foaming process was measured and calculated in this study, and different eco-friendly ...Through systematical experiment design, the physical blowing agent(PBA) mass loss of bio-based polyurethane rigid foam(PURF)in the foaming process was measured and calculated in this study, and different eco-friendly PBA mass losses were measured quantitatively for the first time. The core of the proposed method is to add water to replace the difference, and this method has a high fault tolerance rate for different foaming forms of foams. The method was proved to be stable and reliable through the standard deviations σ1and σ2for R1(ratio of the PBA mass loss to the material total mass except the PBA) and R2(ratio of the PBA mass loss to the PBA mass in the material total mass) in parallel experiments. It can be used to measure and calculate the actual PBA mass loss in the foaming process of both bio-based and petroleumbased PURF. The results show that the PBA mass loss in PURF with different PBA systems is controlled by its initial mass content of PBA in PU materials ω. The main way for PBA to dissipate into the air is evaporation/escape along the upper surface of foam. This study further reveals the mechanism of PBA mass loss: the evaporation/escape of PBA along the upper surface of foam is a typical diffusion behavior. Its spread power comes from the difference between the chemical potential of PBA in the interface layer and that in the outside air. For a certain PURF system, R1has approximately linear relationship with the initial mass content of PBA in PU materials ω, which can be expressed by the functional relationship R1= kω, where k is a variable related to PBA’s own attributes.展开更多
In this paper, we study the fifth-order Camassa-Holm equation with weakly dissipative term. We first give the local well-posedness result and the blow up criterion. Then, we establish sufficient conditions to guarante...In this paper, we study the fifth-order Camassa-Holm equation with weakly dissipative term. We first give the local well-posedness result and the blow up criterion. Then, we establish sufficient conditions to guarantee that the solution exists globally in time. Finally, the infinite propagation speed of this equation is also investigated.展开更多
Gas blowing is a valid method to remove the impurities from metallurgical grade silicon(MG-Si) melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing...Gas blowing is a valid method to remove the impurities from metallurgical grade silicon(MG-Si) melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing.The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle.It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti.The morphology of inclusions was analyzed and the phases Al3Ni,NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction.It was found that SiB4 exists in Si?B binary system.The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS.It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe,Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.展开更多
The removal of phosphorus in metallurgical grade silicon (MG-Si) by water vapor carried with high purity argon was examined. The effect of the nozzle types, refining time, refining temperature, refining gas temperat...The removal of phosphorus in metallurgical grade silicon (MG-Si) by water vapor carried with high purity argon was examined. The effect of the nozzle types, refining time, refining temperature, refining gas temperature and refining gas flow rate on the phosphorus removed was investigated by the self-designed gas blowing device. The optimal refining conditions are nozzle type of holes at bottom and side, refining time of 3 h, refining temperature of 1793 K, refining gas temperature of 373 K, refining gas flow rate of 2 L/min. Under these optimal conditions, the phosphorus content in MG-Si is reduced from 94×10^-6 initially to 11×10-6 (mass fraction), which indicates that gas blowing refining is very effective to remove phosphorus in MG-Si.展开更多
文摘Introduction: Voluntary assault and injuries are acts that damage the physical and psychological integrity of a human being. WHO in its global report on violence and health estimates that in 2000, 1.6 million people worldwide died as a result of self-harm, interpersonal or collective violence, resulting in an overall rate adjusted by age of 28.8 per 100,000 population. Because of the seriousness of this phenomenon and the heavy socio-economic and health consequences that they generate, it seemed important to us to undertake this study, which aimed to study the deliberate injuries in the emergency unite of the Gabriel Touré Teaching Hospital in Bamako. Material and methods: This was a descriptive and cross-sectional study with a prospective study from September 1st, 2016 to August 31st, 12 months, covering 295 patients, including any patient received for voluntary injury consultation with a workable medical record and/or a full investigation record with or without requisition. Our data were collected on individual survey cards and subsequently analyzed with Word, Excel, IBM SPSS Statistics 22 software. Results: The majority of victims of assault and bodily injury were male with 83.1%;with a sex ratio of 4.9, the 18 to 28 age group was the most concerned with 163 cases of the 295 cases in our study, 55.2%. The extremes were 6 and 100 years old with an ectype at 11.08. The most affected ethnic group was Bambara with 38.6% (n = 114) followed by Fulani with 15.6% (n = 46). Students were the most affected at 24.7% (n = 73), followed by traders at 10%. The victims coming from outside Bamako are the most predominant with 22.4% (n = 66) followed by those of commune IV of Bamako 15.6% (n = 46). In 92.2% of the cases the mechanism was direct with n = 272. Of the lesions recorded in our study, wounds came first with 53.2% of cases. Radiography was the most used imaging at 44.7% (n = 89) followed by computed tomography at 34.7% (n = 69). The hemoperitoneum objectified by abdominal ultrasound represented 29.3% (n = 12). Fractures embarrure associated with bruising-hemorrhagic bruises were the most predominant with 13.4% (n = 10) objectified by brain scan. Conclusion: We note that the phenomenon of violence has reached worrying proportions, especially among young adults, particularly among students and is observed in all so-cio-professional layers. The polymorphism of these injuries caused by the predominant use of knives must draw the attention of our authorities to take measures to reduce these aggressions.
文摘Images provided by the author unless otherwise stated■This summer the first major U.S.solo exhibition by leading Taiwan Residents artist Chen Chieh-jen took place at Manhattan's Asia Society.The exhibition 'Condensation' united five silent films that address a variety of social topics into a cohesive unit. The films reflect the mind of someone who came to artistic maturity during a rapidly changing political environment in Taiwan.
文摘Unusual head trauma is rare with various mechanisms of occurrence. The injuries can be similar to those of road accidents but sometimes with significant complexities. The objective was to determine the frequency of this pathology in our practice, describe the different mechanisms and report the craniocerebral lesions caused by this type of trauma. Materials and Method: This was a descriptive study with retrospective collection spread over a period of 3 years. After selecting the files, the patients and/or their companions were contacted by telephone to inquire about them and then returned to the consultation for reassessment. Disease history and information were obtained from patients’ medical records. Result: The frequency of this pathology was 1.78% and his incidence was 0.4 cases per month. The average age of the patients was 13.47 years. All the victims were male. 41.17% of patients were in school. The mechanisms of trauma were the hoof blow 47.1%, the horn blow 29.4% and the stone blow 11.7% respectively. 23.5% of patients were confused and 11.7% children were in coma. One patient presented an anisocoria. The motor deficit was present in 5 cases. CT-scan made it possible to highlight a skull depressing fracture 58.8% and confirm a craniocerebral wound in 35.3%. The average time between patient admission to hospital and completion of surgery was 24.5 hours. The surgery had consisted of the trimming of cranio-cerebral wounds, exploration, duroplasty and lifting of skull depressing fracture. After 15 months of follow-up, the evolution was favorable in 53.3%, the morbidity was 33.4% and the mortality 17.6%. Conclusion: These are rare but serious conditions because they are fatal and disabling. An early and multidisciplinary management can hope to have a good favorable.
基金financially supported by the National Natural Science Foundation of China (Nos.51974023 and52374321)the funding of State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing,China (No.41620007)。
文摘The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in converter. A three-step method was utilized in the hybrid model. First, the oxygen consumption volume was predicted by the OBM model and DNN model, respectively. Second, a more accurate oxygen consumption volume was obtained by integrating the OBM model and DNN model. Finally, the converter oxygen blowing time was calculated according to the oxygen consumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data collected from an integrated steel plant in China, and compared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3 hidden layer layers, 32-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability compared with other models. The predicted hit ratio of oxygen consumption volume within the error±300 m^(3)is 96.67%;determination coefficient (R^(2)) and root mean square error (RMSE) are0.6984 and 150.03 m^(3), respectively. The oxygen blow time prediction hit ratio within the error±0.6 min is 89.50%;R2and RMSE are0.9486 and 0.3592 min, respectively. As a result, the proposed model can effectively predict the oxygen consumption volume and oxygen blowing time in the converter.
文摘The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.
基金funded by projects“Smart Materials,Photonics,Technologies and Engineering Ecosystem(MOTE)”(Contract No.VPP-EM-FOTONIKA-2022/1-0001)“Bio-Based Cryogenic Insulation for Aerospace Application(BioSpace)”(Contract No.4000135271/21/NL/SC).
文摘Cryogenic insulation material rigid polyurethane(PU)foams were developed using bio-based and recycled feedstock.Polyols obtained from tall oil fatty acids produced as a side stream of wood biomass pulping and recycled polyethylene terephthalate were used to develop rigid PU foam formulations.The 4th generation physical blowing agents with low global warming potential and low ozone depletion potential were used to develop rigid PU foam cryogenic insulation with excellent mechanical and thermal properties.Obtained rigid PU foams had a thermal conductivity coefficient as low as 0.0171 W/m·K and an apparent density of 37-40 kg/m^(3).The developed rigid PU foams had anisotropic compression strength properties,which were higher parallel to the foaming direction.Moreover,the compression strength was also influenced by the type of applied bio-based polyol.The bio-based polyols with higher OH group functionality delivered higher crosslinking density of polymer matrix;thus,the mechanical properties were also higher.The mechanical strength of the foams increased when materials were tested at liquid nitrogen temperature due to the stiffening of the polymer matrix.The thermal properties of the developed materials were determined using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis methods.Lastly,the developed rigid PU foams had good adhesion to the aluminium substrate before and after applying cyroshock and an excellent safety coefficient of 4-5.Rigid PU foams developed using Solstice LBA delivered adhesion strength of~0.5 MPa and may be considered for application as cryogenic insulation in the aerospace industry.
基金Supported by National Natural Science Foundation of China(Grant No.11801145)the Innovative Funds Plan of Henan University of Technology(Grant No.2020ZKCJ09)。
文摘We consider the initial-boundary value problem for finitely degenerate parabolic equation. We first give sufficient conditions for the blow-up and global existence of the parabolic equation at high initial energy level. Then, we establish the existence of solutions blowing up in finite time with initial data at arbitrary energy level. Finally, we estimate the upper bound of the blow-up time under certain conditions.
文摘艺术家乔希·辛普森制作玻璃球,并且他做的玻璃球会藏在地球上的任意一个地方等待人们发现。Artist Josh Simpson creates tiny glass planets that are meant to delight his audi-ence.Decades ago,he gave glassblowing demonstrations to local students in his studio in Springfield,Massachusetts.Simp-son started by showing the middle-school students how to make marbles(弹子).
文摘This article discusses and analyzes the law of nitrogen increase in liquid steel and the main factors affect-ing the nitrogen increasing of molten steel,through the way of adding nitrogen to molten steel by bottom blowing nitrogen gas in LF refining process.It is considered that the main factors affecting the nitrogen increasing instability of molten steel are the initial temperature of LF refining,nitrogen relative element,surface active elements[O]and[S]of steel liquid,and bottom blowing rate of ladle.The large-scale production practice shows that T[O]not more than 50×10-6 and[S]is not more than 0.020 in LF refining at the initial temperature of not less than 1570.The liquid steel nitrogen enrichment test is carried out by ladle bottom blowing nitrogen gas after 20 min of refining,the flow rate is set as(6.0~7.0)NL/min per ton,and it is turned to 2 NL/min at 6 min before the end of refining,the nitrogen increasing rate of liquid steel is basically stable at(5~6)×10-6 per minute.
文摘The unfolding global financial crisis is arousing jitters about another round of heavy blows to the world economy, which may be intensified by the possible U.S. government takeover of Citigroup Inc. and Bank of America Corp. lg, Chief Economist of the Asia-Pacific region for Credit Suisse First Boston (Hong Kong ) Ltd., published an article in the Securities Market Weekly, warning about five other major crashes that might dampen global economic recovery. Edited excerpts follow.
文摘There is a beautiful city in southwestern Germany,lying on the southern bank of the Rhine River,which has flowed quietly nearby since ancient times.The city was the hometown of Johannes Gutenberg,the inventor of modern typography,as well as of an excellent Bundesliga soccer team.It features a combination of ancient flavor and modern fashion,with not only time-honored churches
基金financially supported by the National Natural Science Foundation of China(No.51704062)the Fundamental Research Funds for the Central Universities,China(No.N2025019)。
文摘A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.
基金Supported by Soonchunhyang research fund,No.2023-0024.
文摘BACKGROUND Many cases of emphysema associated with blow-out fractures occur before surgery due to trauma.However,emphysema can occur even after surgery,and most of such cases are managed conservatively and allowed to resolve.Swelling in the periorbital area due to emphysema that occurs after surgery can make early recovery difficult.CASE SUMMARY Herein,we describe a case of postoperative subcutaneous emphysema that was treated using a simple needle aspiration method.A 48-year-old male patient visited the hospital with a blow-out fracture of the left medial orbital wall and nasal bone fracture.One day postoperatively,swelling and crepitus in the left periorbital area were observed,and follow-up computed tomography showed emphysema in the left periorbital subcutaneous area.Needle aspiration using an 18-gauge needle and syringe was used to relieve the emphysema.The symptoms of sudden swelling improved immediately,and no recurrence was observed.CONCLUSION We conclude that needle aspiration is a useful method that could help in relieving symptom,resolving discomfort,and enabling early return to daily life in patients with postoperative subcutaneous emphysema.
文摘Through systematical experiment design, the physical blowing agent(PBA) mass loss of bio-based polyurethane rigid foam(PURF)in the foaming process was measured and calculated in this study, and different eco-friendly PBA mass losses were measured quantitatively for the first time. The core of the proposed method is to add water to replace the difference, and this method has a high fault tolerance rate for different foaming forms of foams. The method was proved to be stable and reliable through the standard deviations σ1and σ2for R1(ratio of the PBA mass loss to the material total mass except the PBA) and R2(ratio of the PBA mass loss to the PBA mass in the material total mass) in parallel experiments. It can be used to measure and calculate the actual PBA mass loss in the foaming process of both bio-based and petroleumbased PURF. The results show that the PBA mass loss in PURF with different PBA systems is controlled by its initial mass content of PBA in PU materials ω. The main way for PBA to dissipate into the air is evaporation/escape along the upper surface of foam. This study further reveals the mechanism of PBA mass loss: the evaporation/escape of PBA along the upper surface of foam is a typical diffusion behavior. Its spread power comes from the difference between the chemical potential of PBA in the interface layer and that in the outside air. For a certain PURF system, R1has approximately linear relationship with the initial mass content of PBA in PU materials ω, which can be expressed by the functional relationship R1= kω, where k is a variable related to PBA’s own attributes.
文摘In this paper, we study the fifth-order Camassa-Holm equation with weakly dissipative term. We first give the local well-posedness result and the blow up criterion. Then, we establish sufficient conditions to guarantee that the solution exists globally in time. Finally, the infinite propagation speed of this equation is also investigated.
基金Projects(51104080,u1137601) supported by the National Natural Science Foundation of ChinaProject(2009CD027) supported by the Natural Science Foundation of Yunnan Province,ChinaProject(14118557) supported by the Personnel Training Foundation of Kunming University of Science and Technology,China
文摘Gas blowing is a valid method to remove the impurities from metallurgical grade silicon(MG-Si) melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing.The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle.It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti.The morphology of inclusions was analyzed and the phases Al3Ni,NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction.It was found that SiB4 exists in Si?B binary system.The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS.It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe,Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.
基金Project(51074043)supported by the National Natural Science Foundation of ChinaProject(2011BAE03B01)supported by the National Key Technology R&D Program of China
文摘The removal of phosphorus in metallurgical grade silicon (MG-Si) by water vapor carried with high purity argon was examined. The effect of the nozzle types, refining time, refining temperature, refining gas temperature and refining gas flow rate on the phosphorus removed was investigated by the self-designed gas blowing device. The optimal refining conditions are nozzle type of holes at bottom and side, refining time of 3 h, refining temperature of 1793 K, refining gas temperature of 373 K, refining gas flow rate of 2 L/min. Under these optimal conditions, the phosphorus content in MG-Si is reduced from 94×10^-6 initially to 11×10-6 (mass fraction), which indicates that gas blowing refining is very effective to remove phosphorus in MG-Si.