烟颗粒粒径分布和浓度变化是探测香烟阴燃火灾初期的重要参数,研究香烟阴燃过程烟颗粒粒谱分布对火灾探测具有指导意义。实验通过在室内有风条件下展开,研究风速、位置、时间、烟源等因素对烟颗粒的粒径分布和形成规律的影响。结果表明:...烟颗粒粒径分布和浓度变化是探测香烟阴燃火灾初期的重要参数,研究香烟阴燃过程烟颗粒粒谱分布对火灾探测具有指导意义。实验通过在室内有风条件下展开,研究风速、位置、时间、烟源等因素对烟颗粒的粒径分布和形成规律的影响。结果表明:1随着时间的推移,GMD(Geometric Mean Diameter,几何平均直径)变大,烟颗粒数量浓度增加,但粒谱分布逐渐趋于稳定。2风速对颗粒粒谱形成的影响较为复杂,随着风速的增加,气流扰动加剧,烟颗粒浓度增加,GMD有减小的变化趋势。3在不同的位置,有风条件下烟颗粒随着气流迁移,最终在壁面处进行积累,离烟源越远位置,沿着风速方向浓度和GMD均变大。4烟颗粒的初始浓度也影响烟颗粒粒谱分布和运动特征,烟源数量越多,初始浓度越大,形成的烟颗粒浓度和GMD越大。展开更多
Objective: The current study aimed to investigate whether the level of consciousness influenced the F wave generation, as an independent factor. Methods: Forty three patients with acute stroke were divided according t...Objective: The current study aimed to investigate whether the level of consciousness influenced the F wave generation, as an independent factor. Methods: Forty three patients with acute stroke were divided according to their level of consciousness in two groups; to those with Glasgow scale (GCS) score 3-7 indicating coma (group I) and those with GCS score 8-15 (group II). A series of 40 electrical stimuli were delivered to the ulnar nerve bilaterally in order to obtain F waves. The following variables were estimated and then compared between groups: F persistence, F wave latency, amplitude and duration. All studies were performed within 3 days from the onset of the stroke symptoms. Results: The main finding to emerge was the significantly reduced F wave persistence in the group of patients with low GCS score as opposed to patients allocated in the group with GCS score 8-15. This result is referred to F waves obtained from both the affected and unaffected limb. F wave minimum latency w as also prolonged in the group with low GCS score, whilst the comparison of all other F wave variables revealed no significant differences between groups I and II. F wave persistence measurements did not differ between the affected and unaffected sides. Stroke location and type (ischemic or hemorrhagic) were not associated with alterations of F wave measurements. Conclusions: Our results on stroke patients suggest that generation of F waves, expressed by the F wave persistence is associated with the level of consciousness. Significance: F wave study may be useful as an objective measure in documenting the severity of consciousness impairment.展开更多
文摘烟颗粒粒径分布和浓度变化是探测香烟阴燃火灾初期的重要参数,研究香烟阴燃过程烟颗粒粒谱分布对火灾探测具有指导意义。实验通过在室内有风条件下展开,研究风速、位置、时间、烟源等因素对烟颗粒的粒径分布和形成规律的影响。结果表明:1随着时间的推移,GMD(Geometric Mean Diameter,几何平均直径)变大,烟颗粒数量浓度增加,但粒谱分布逐渐趋于稳定。2风速对颗粒粒谱形成的影响较为复杂,随着风速的增加,气流扰动加剧,烟颗粒浓度增加,GMD有减小的变化趋势。3在不同的位置,有风条件下烟颗粒随着气流迁移,最终在壁面处进行积累,离烟源越远位置,沿着风速方向浓度和GMD均变大。4烟颗粒的初始浓度也影响烟颗粒粒谱分布和运动特征,烟源数量越多,初始浓度越大,形成的烟颗粒浓度和GMD越大。
文摘Objective: The current study aimed to investigate whether the level of consciousness influenced the F wave generation, as an independent factor. Methods: Forty three patients with acute stroke were divided according to their level of consciousness in two groups; to those with Glasgow scale (GCS) score 3-7 indicating coma (group I) and those with GCS score 8-15 (group II). A series of 40 electrical stimuli were delivered to the ulnar nerve bilaterally in order to obtain F waves. The following variables were estimated and then compared between groups: F persistence, F wave latency, amplitude and duration. All studies were performed within 3 days from the onset of the stroke symptoms. Results: The main finding to emerge was the significantly reduced F wave persistence in the group of patients with low GCS score as opposed to patients allocated in the group with GCS score 8-15. This result is referred to F waves obtained from both the affected and unaffected limb. F wave minimum latency w as also prolonged in the group with low GCS score, whilst the comparison of all other F wave variables revealed no significant differences between groups I and II. F wave persistence measurements did not differ between the affected and unaffected sides. Stroke location and type (ischemic or hemorrhagic) were not associated with alterations of F wave measurements. Conclusions: Our results on stroke patients suggest that generation of F waves, expressed by the F wave persistence is associated with the level of consciousness. Significance: F wave study may be useful as an objective measure in documenting the severity of consciousness impairment.
