植物根系吸水模型研究进展

根系是植物获取水分的主要器官,它直接影响整个植株的输水量以及生命活动。在水资源短缺的状况下,了解根系生长过程中的需水特性并提高农业中水资源的利用率,一直是节水灌溉技术中研究创新的热点。因此,在研究过程中需要对植物根系的吸水量进行精确估算,建立根系吸水模型是定量化研究植物根系吸水特性的重要方法。概述根系吸水的原理及其主要影响因素,对不同研究方法下的根系吸水模型进行分类研究,并阐述其适用范围及优缺点,同时介绍了水盐共同胁迫下的根系吸水模型。最后对目前的根系吸水模型进行分析,提出了今后的研究方向。研究成果为构建水稻根系三维动态吸水模型提供了基础。

含缺陷压力管道评定技术研究进展

承压容器与管道被广泛应用在能源工业、军工、科研等诸多领域,其运输介质通常伴有易燃易爆等特性,因此,确保其安全运行的重要性是不言而喻的。针对承压容器与管道的安全问题研究一直是一个重要的课题。针对含缺陷承压容器与管道的安全评定,首先介绍了中外最新基于“合于使用”为原则的常用标准规范的起源及最新成果,给出了缺陷评定采用的关键技术最新进展,以及影响评定结果的重要因素的研究现状,同时对缺陷容器管道的评定技术的应用现状做了简单的介绍。最后,提出了目前国内缺陷评定技术的存在的问题,为含缺陷承压容器与管道的安全评价的发展方向提出建议。

双金属衬里复合管内衬弹塑性失稳有限元分析

采用数值模拟的方法建立了含初始缺陷的受限衬管失稳力学模型,重点研究了受限衬管的临界失稳载荷和后屈曲构型之间的相互作用行为,并讨论了临界失稳载荷的缺陷敏感性,最后通过试验验证了仿真结果的计算精度。结果表明,相对于衬管半径1%幅度的内衬不圆度缺陷会使内衬的临界失稳载荷下降约65%;在相同的初始椭圆度缺陷δ_(0)前提下,随着内衬径厚比的增大,其临界失稳载荷不断减小;复合管内衬临界失稳载荷的有限元计算结果与试验结果的相对误差为1.82%。建立的平面应变有限元力学模型不仅可以准确求解出受限内衬的临界失稳载荷,还能够大量节约试验成本。

双金属复合管液压成形力学模型与数值模拟研究

从复合管液压成形力学模型、边界条件约束和弹塑性分析的角度,讨论了塑性成形过程力学计算模型的差异,分析了双金属复合管液压成形过程应力、应变以及残余应力的非线性分布规律,提供了准确的有限元分析模型以及胀接区间确定方法,探究了基管和衬管间初始间隙对结果的影响。结果表明:双金属复合管成形过程是一个复杂的非线性过程,传统的模型对残余接触应力的计算存在误差;建立了考虑变形协调和轴向等效应力的液压胀接过程模型,利用应力变化曲线关系准确地确定了胀接应力区间;胀接完成后基管和衬管最大应力点为衬管外壁;制管时应减小复合管初始间隙。

120调度指挥中心在疫情防控中的应用与思考

在抗击新型冠状病毒肺炎(COVID-19)疫情战役中,120调度指挥中心主要承担呼叫受理、调度派车、咨询答疑等相关工作.在应对突如其来的疫情,结合呼叫人群、疾病病种的改变、呼叫量的剧增,120指挥调度中心打破传统调度模式,因势而谋、精准施策,调整接警受理规范,制定分级分层分类调度转运方案,发挥了COVID-19转运救治的主力军作用.本文通过调度实践,总结了疫情期间的具体应用,也提出一些思考.

高温作用下液压胀接换热管蠕变性能研究

随着工业产业的飞速发展,工业中的换热器服役环境越来越苛刻,其管接头连接可靠性至关重要。以管壳式换热器的管接头为研究对象,运用ABAQUS有限元软件模拟液压胀接过程,对换热管管接头进行了蠕变分析计算,探讨了不同蠕变工况下换热管与管板接触面上残余接触压力的变化情况。研究结果表明,换热管与管板的过渡区是接头脆弱部分,接头在高温工作下随时间延长发生蠕变,残余接触压力先迅速降低然后趋于平缓,液压胀接接头性能在相对低温时受蠕变影响较大,影响程度与温度成正相关,在相对较高温度时出现蠕变饱和现象,蠕变效应不再明显增大。研究可以为管壳式换热器的设计及制造提供技术支持。

Effect of moxibustion on VEGF and EGF expressions in tumor tissues of rats with gastric tumor

Objective:To explore the inhibitory effect of moxibustion on tumor growth and metastasis, and also its possible mechanism, in gastric tumor-bearing rats by investigating the expressions of vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF). Methods:Fifty healthy Sprague-Dawley (SD) rats (half male and half female) were routinely housed for 1 week. A total of 20 rats were randomly divided into a blank group and a sham operation group, with 10 rats in each group. The remaining 30 rats were used to make gastric cancer models by implantation of ascites-type Walker-256 cancer cells. After successful modeling, rats were randomly divided into a model group, a moxibustion group and an infrared group, with 10 rats in each group. From the day of modeling, the body weight of each group was weighed every 4 days. Warm moxibustion was alternately performed at two-group acupoints [Zhongwan (CV 12), Guanyuan (CV 4) and bilateral Zusanli (ST 36) in one group, and bilateral Pishu (BL 20) and Weishu (BL 21) in another group] in the moxibustion group. The body surface projection area of the stomach was irradiated with short-wave infrared rays in the infrared group, once a day, 20 min per time for 21 d. At the end of the treatment, the gastric tumor was completely dissected, and the tumor volume and tumor growth inhibition rate were calculated. Then the gastric tumor cell metastasis was recorded. The levels of VEGF and EGF in rat gastric tumor tissues were determined by enzyme-linked immunosorbent assay (ELISA). Results:Compared with the blank group, the body weight of the model group decreased significantly after modeling (P<0.05);compared with the model group, the rats in the moxibustion group had increased body weight during the middle and late stages (bothP<0.05). The tumor volumes of rats in the moxibustion group and the infrared group were smaller than the volume in the model group (bothP<0.05). The tumor growth inhibition rate in the moxibustion group was significantly higher than that in the infrared group (P<0.05). The case number of tumor metastasis in the moxibustion group was smaller than that in the model group and the infrared group. The VEGF level in the tumor tissues of the model group was statistically significantly higher than that in the blank group (P<0.05). Compared with the model group, the VEGF levels in the moxibustion group and the infrared group were statistically significantly lower (bothP<0.05). The EGF levels in the tumor tissues of the model group was statistically significantly lower than that in the blank group (P<0.05);compared with the model group, the EGF levels in the moxibustion group and the infrared group were statistically significantly increased (bothP<0.05). Conclusion:Moxibustion can increase the body weight, inhibit the tumor growth, invasion and metastasis in gastric tumor-bearing rats, which may be related to the regulation of VEGF and EGF expressions in tumor tissues.

温针灸配合盘龙灸治疗腰椎压缩性骨折后遗症验案

介绍温针灸配合盘龙灸法治疗腰椎压缩性骨折后遗症验案1则,认为通过辨证论治寻找病变经络,并采用温针灸联合盘龙灸舒经活络,对于腰椎压缩性骨折后遗症的治疗有着良好疗效。