背景:椎旁肌退变是腰痛的主要致病因素之一,而椎旁肌的改变则与其发生发展密切相关。现阶段临床工作者关注腰椎退行性疾病中椎旁肌的变化,以预防和治疗腰椎疾病,而忽略了疾病中腰椎间盘退变与椎旁肌的联系及相关机制。目的:对椎旁肌和...背景:椎旁肌退变是腰痛的主要致病因素之一,而椎旁肌的改变则与其发生发展密切相关。现阶段临床工作者关注腰椎退行性疾病中椎旁肌的变化,以预防和治疗腰椎疾病,而忽略了疾病中腰椎间盘退变与椎旁肌的联系及相关机制。目的:对椎旁肌和腰椎间盘的相互作用研究进行全面总结,从而综述腰椎间盘退变与椎旁肌的相关性及机制,旨在为临床防治提供参考。方法:使用中文关键词“腰椎间盘,椎旁肌,多裂肌,腰痛,退行性变,影像学,磁共振成像”在中国知网、维普、万方等中文数据库中检索相关文献,并使用英文关键词“lumbar disc,paraspinal muscle,multifidus muscle,low back pain,degeneration,imaging,MRI”在Medline、PubMed、Web of Science等英文数据库中检索。通过初步筛选标题和摘要,按照纳入和排除标准筛选文献,最终选取了68篇文献进行综述分析。结果与结论:①研究者们利用各种方法来评估椎旁肌的退变程度,同时按照Pfirrmann分级对腰椎间盘退变程度进行评估,发现临床诊疗中应关注性别差异,并重视肥胖等因素对腰椎间盘和肌肉退变的影响,以制定更加个体化的治疗方案。②腰椎间盘退变和椎旁肌肉脂肪浸润之间存在一定关联,但研究结果存在争议。多数研究发现,椎旁肌肉(尤其是多裂肌)的脂肪浸润与腰椎间盘退变程度呈正相关。③目前认为失用性萎缩、去神经机制及炎症因子3种机制可能相互作用,共同导致椎旁肌肉的结构和功能改变,这与腰椎间盘退变和腰痛的发生密切相关。④临床上应关注受累神经根节段以下一级肌肉的变化,有助于诊断和定位腰椎根神经病变。同时,抑制炎症因子可能成为治疗的潜在靶点。⑤临床工作中,首先应通过适当的药物或手术治疗纠正神经根压迫,以控制炎症反应和神经根疼痛,然后再进行针对性的肌肉康复训练。必要时考虑采用干扰电流电刺激等新型治疗方法来改善患者的症状和预后。展开更多
The green transition of power systems relies on the accurate measurement of the economic cost associated with the deep peak-shaving process in coal-fired power plants. To evaluate the variation in the coal consumption...The green transition of power systems relies on the accurate measurement of the economic cost associated with the deep peak-shaving process in coal-fired power plants. To evaluate the variation in the coal consumption rate during low-load operation, a model of a 300 MW coal-fired unit was established, with less than 1% deviation from the actual operation value. The results indicate that the coal consumption rate at 20% load can increase to 1.48 times the full-load value. When the excess air coefficient is reduced by 0.3 at low-load conditions, between 40% and 20% load, the exhaust gas temperature is reduced by approximately 5℃, leading to a decrease in the coal consumption rate. In addition, elevating the steam temperature to the design value can reduce the coal consumption rate by 6% to 13%, and increase the inlet temperature of Selective Catalytic Reduction (SCR) process by 10℃. Improving the turbine efficiency during peak-shaving significantly reduces the coal consumption cost, and the enhancement of the mean steam temperature is an efficient approach. This study offers a theoretical reference for the retrofitting, design and economic operation of coal-fired units in peak-shaving, thereby supporting energy system transitions.展开更多
A study of the heat transfer about the heating surface of three commercial 300 MWe CFB boilers was conducted in this work. The heat transfer coefficients of the platen heating surface, the external heat exchanger (EHE...A study of the heat transfer about the heating surface of three commercial 300 MWe CFB boilers was conducted in this work. The heat transfer coefficients of the platen heating surface, the external heat exchanger (EHE) and cyclone separator were calculated according to the relative operation data at different boiler loads. Moreover, the heat transfer coefficient of the waterwall was calculated by heat balance of the hot circuit of the CFB boiler. With the boiler capacity increasing, the heat transfer coefficients of these heating surface increases, and the heat transfer coefficient of the water wall is higher than that of the platen heating surface. The heat transfer coefficient of the EHE is the highest in high boiler load, the heat transfer coefficient of the cyclone separator is the lowest. Because the fired coal is different from the design coal in No.1 boiler, the ash content of the fired coal is much lower than that of the design coal. The heat transfer coefficients which calculated with the operation data are lower than the previous design value and that is the reason why the bed temperature is rather high during the boiler operation in No.1 boiler.展开更多
文摘背景:椎旁肌退变是腰痛的主要致病因素之一,而椎旁肌的改变则与其发生发展密切相关。现阶段临床工作者关注腰椎退行性疾病中椎旁肌的变化,以预防和治疗腰椎疾病,而忽略了疾病中腰椎间盘退变与椎旁肌的联系及相关机制。目的:对椎旁肌和腰椎间盘的相互作用研究进行全面总结,从而综述腰椎间盘退变与椎旁肌的相关性及机制,旨在为临床防治提供参考。方法:使用中文关键词“腰椎间盘,椎旁肌,多裂肌,腰痛,退行性变,影像学,磁共振成像”在中国知网、维普、万方等中文数据库中检索相关文献,并使用英文关键词“lumbar disc,paraspinal muscle,multifidus muscle,low back pain,degeneration,imaging,MRI”在Medline、PubMed、Web of Science等英文数据库中检索。通过初步筛选标题和摘要,按照纳入和排除标准筛选文献,最终选取了68篇文献进行综述分析。结果与结论:①研究者们利用各种方法来评估椎旁肌的退变程度,同时按照Pfirrmann分级对腰椎间盘退变程度进行评估,发现临床诊疗中应关注性别差异,并重视肥胖等因素对腰椎间盘和肌肉退变的影响,以制定更加个体化的治疗方案。②腰椎间盘退变和椎旁肌肉脂肪浸润之间存在一定关联,但研究结果存在争议。多数研究发现,椎旁肌肉(尤其是多裂肌)的脂肪浸润与腰椎间盘退变程度呈正相关。③目前认为失用性萎缩、去神经机制及炎症因子3种机制可能相互作用,共同导致椎旁肌肉的结构和功能改变,这与腰椎间盘退变和腰痛的发生密切相关。④临床上应关注受累神经根节段以下一级肌肉的变化,有助于诊断和定位腰椎根神经病变。同时,抑制炎症因子可能成为治疗的潜在靶点。⑤临床工作中,首先应通过适当的药物或手术治疗纠正神经根压迫,以控制炎症反应和神经根疼痛,然后再进行针对性的肌肉康复训练。必要时考虑采用干扰电流电刺激等新型治疗方法来改善患者的症状和预后。
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA 29010500)the Special Research Assistant Project of the Chinese Academy of Sciences.
文摘The green transition of power systems relies on the accurate measurement of the economic cost associated with the deep peak-shaving process in coal-fired power plants. To evaluate the variation in the coal consumption rate during low-load operation, a model of a 300 MW coal-fired unit was established, with less than 1% deviation from the actual operation value. The results indicate that the coal consumption rate at 20% load can increase to 1.48 times the full-load value. When the excess air coefficient is reduced by 0.3 at low-load conditions, between 40% and 20% load, the exhaust gas temperature is reduced by approximately 5℃, leading to a decrease in the coal consumption rate. In addition, elevating the steam temperature to the design value can reduce the coal consumption rate by 6% to 13%, and increase the inlet temperature of Selective Catalytic Reduction (SCR) process by 10℃. Improving the turbine efficiency during peak-shaving significantly reduces the coal consumption cost, and the enhancement of the mean steam temperature is an efficient approach. This study offers a theoretical reference for the retrofitting, design and economic operation of coal-fired units in peak-shaving, thereby supporting energy system transitions.
基金support from Strategic Priority Research Program of the Chinese Academy of Sciences, Grant No. XDA07030100Technology support program in the 11th Five-year Plan (2006BAA03B06)
文摘A study of the heat transfer about the heating surface of three commercial 300 MWe CFB boilers was conducted in this work. The heat transfer coefficients of the platen heating surface, the external heat exchanger (EHE) and cyclone separator were calculated according to the relative operation data at different boiler loads. Moreover, the heat transfer coefficient of the waterwall was calculated by heat balance of the hot circuit of the CFB boiler. With the boiler capacity increasing, the heat transfer coefficients of these heating surface increases, and the heat transfer coefficient of the water wall is higher than that of the platen heating surface. The heat transfer coefficient of the EHE is the highest in high boiler load, the heat transfer coefficient of the cyclone separator is the lowest. Because the fired coal is different from the design coal in No.1 boiler, the ash content of the fired coal is much lower than that of the design coal. The heat transfer coefficients which calculated with the operation data are lower than the previous design value and that is the reason why the bed temperature is rather high during the boiler operation in No.1 boiler.
