A novel elastic sandwich metamaterial plate with composite periodic rod core is designed,and the frequency band-gap characteristics are numerically and experimentally investigated.The finite element and spectral eleme...A novel elastic sandwich metamaterial plate with composite periodic rod core is designed,and the frequency band-gap characteristics are numerically and experimentally investigated.The finite element and spectral element hybrid method(FE-SEHM)is developed to obtain the dynamic stiffness matrix of the sandwich metamaterial plate.The frequency response curves of the plate structure under the harmonic excitation are calculated using the presented numerical method and validated by the vibration experiment.By comparing with the frequency response curves of sandwich metamaterial plate with pure elastic rod core,improved band-gap properties are achieved from the designed metamaterial plate with composite periodic rod core.The elastic metamaterial plate with composite periodic rod core can generate more band-gaps,so it can suppress the vibration and elastic wave propagation in the structure more effectively.展开更多
Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based...Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based?on their function and located at different places in the core where their feature is maximized.?Two methods of control rod calibration are the asymptotic period method and the rod-drop method, which were applied in this experiment. In the first method, the reactor is made supcritical by inserting the control rod to be calibrated a certain level. The rod drop method is to determine the subcritical;at the critical state, the rod to be calibrated is dropped into the core, and the resulting decay of neutron flux is observed and related to the reactivity. In this paper, the regulating rod will be calibrated according to the reactivity in OPR-1000 that corresponds to a certain control rod insert or withdraw, and the reactivity in power reactor depends?on the integral and differential control rod group too. The core simulator OPR1000 is used to test those methods.展开更多
[目的]比较ARCOⅠ~Ⅱ期股骨头坏死(osteonecrosis of the femoral head,ONFH)髓芯减压多孔生物活性陶瓷棒置入是否联合磷酸三钙颗粒植入的临床疗效。[方法]2021年9月—2022年9月于本院就诊的60例(87髋)ARCOⅠ~Ⅱ期ONFH患者纳入本研究,...[目的]比较ARCOⅠ~Ⅱ期股骨头坏死(osteonecrosis of the femoral head,ONFH)髓芯减压多孔生物活性陶瓷棒置入是否联合磷酸三钙颗粒植入的临床疗效。[方法]2021年9月—2022年9月于本院就诊的60例(87髋)ARCOⅠ~Ⅱ期ONFH患者纳入本研究,采用随机数字表法将患者分为两组,其中,30例在髓芯减压后联合植入磷酸三钙颗粒和陶瓷棒(复合组),另外30例在髓芯减压后单纯置入陶瓷棒(单纯组)。比较两组围手术期、随访和影像资料。[结果]两组均顺利手术,无感染等并发症。两组的手术时间、切口长度、住院天数差异无统计学意义(P>0.05),复合组的术中失血量[mL,(65.7±14.7)vs(76.6±14.7),P=0.005]、术后引流量[mL,(101.4±9.8)vs(112.6±10.4),P<0.001]显著少于单纯组,尽管复合组的平均术中透视次数显著多于单纯组(P<0.001)。两组患者术后随访24个月以上,复合组恢复完全负重时间显著早于单纯组[d,(114.8±20.4)vs(154.6±21.2),P<0.001]。两组患者的VAS评分、Harris评分、髋伸-屈ROM和髋内旋-外旋ROM均显著改善(P<0.05)。术后12、24个月时,复合组的VAS、Harris评分和内旋-外旋ROM均显著优于单纯组(P<0.05),但两组伸-屈ROM的差异没有统计学意义(P>0.05)。截至末次随访,两组均无患者接受翻修THA。影像方面,随时间推移,两组ARCO分级、病灶面积、关节积液征像、股骨头塌陷及Tönnis分期均显著改善(P<0.05)。术后24个月时复合组的ARCO分级、关节积液征像、股骨头塌陷及Tönnis分期均显著优于单纯组(P<0.05)。[结论]ARCOⅠ~Ⅱ期ONFH的治疗中磷酸三钙人工骨颗粒联合多孔生物活性陶瓷棒的临床结果优于单纯多孔生物活性陶瓷棒置入。展开更多
A single forming equipment of bimetal continuous core-filling casting was designed and manufactured for the purpose of developing copper-aluminum composite materials.The characteristics of the equipment were as follow...A single forming equipment of bimetal continuous core-filling casting was designed and manufactured for the purpose of developing copper-aluminum composite materials.The characteristics of the equipment were as follows：the crystallizer composed of water jacket copper sleeve in which graphite sleeve was set, two melting furnaces with different diameters vertically distributed, the low furnace of melting copper linked with the crystallizer, continuous casting and core-filling proceeded at the meantime.The rational processing parameters were determined through a series of experiments：contact length from down crucible to water-cooling cupreous crystallizer, 20 mm;length of recooling spray jet under crystallizer, 95 mm;temperature of copper and aluminum, 1250-1320℃ and 700℃ respectively;pulling rate, 16 mm/min.The qualified copper-clad aluminum composite rods, the external and inner diameter of which was 40 mm and 24 mm respectively, could be drawn successfully on that basis.Tested by hydrostatic extrusion and drawing process, the boss ratios of the copperclad aluminum composite rods were maintained a relatively stable scope of about 0.59-0.65, which was not obviously changed by subsequent plastic processing.展开更多
目的探讨髋关节镜直视下髋关节清理、富血小板血浆(platelet-rich plasma,PRP)精准注入联合钽棒植入术治疗早期股骨头坏死(osteonecrosis of the femoral head,ONFH)的临床疗效。方法选取2020年10月至2022年10月收治的早期ONFH患者50例...目的探讨髋关节镜直视下髋关节清理、富血小板血浆(platelet-rich plasma,PRP)精准注入联合钽棒植入术治疗早期股骨头坏死(osteonecrosis of the femoral head,ONFH)的临床疗效。方法选取2020年10月至2022年10月收治的早期ONFH患者50例(62髋),随机分为两组,其中观察组25例(32髋)采用关节镜直视下髋关节清理、PRP精准注入联合钽棒植入术治疗,对照组25例(30髋)采用单纯髓芯减压钽棒植入术治疗。术后第1、2、3、6、12个月门诊复查髋关节X线片,观察股骨头密度的变化,对髋关节Harris评分及疼痛视觉模拟评分(visual analogue scale,VAS)等指标进行评估。结果术后12个月髋关节X线片示,观察组患者股骨头外形良好,没有出现囊性变扩大或股骨头塌陷,内植物与骨整合良好,无松动移位发生;对照组有6例发生了股骨头塌陷,内植物与骨整合差,界限明显。末次随访时观察组效果明显优于对照组。观察组髋关节Harris评分由术前的(68.13±6.45)分提高到末次随访时的(89.64±7.14)分,对照组髋关节Harris评分由术前的(68.73±7.15)分提高到末次随访时的(78.64±7.14)分;观察组疼痛VAS评分由术前的(4.5±1.3)下降到末次随访时的(1.8±1.1)分,对照组疼痛VAS评分由术前的(4.3±1.2)下降到末次随访时的(2.3±1.3)分,均P<0.05。两组患者治疗后Harris和VAS评分对比差异具有统计学意义(P<0.05)。结论与单纯髓芯减压钽棒植入术相比,关节镜直视下髋关节清理、PRP精准注入联合钽棒植入术治疗早期股骨头坏死可以明显减轻患髋的疼痛症状、改善患髋的活动功能,并能促进新生骨长入,短期疗效显著,为临床治疗早期ONFH提供了一种新的方法。展开更多
基金the National Natural Science Foundation of China(No.11761131006)the Research Team Project of Heilongjiang Natural Science Foundation under Grant No.TD2020A001.
文摘A novel elastic sandwich metamaterial plate with composite periodic rod core is designed,and the frequency band-gap characteristics are numerically and experimentally investigated.The finite element and spectral element hybrid method(FE-SEHM)is developed to obtain the dynamic stiffness matrix of the sandwich metamaterial plate.The frequency response curves of the plate structure under the harmonic excitation are calculated using the presented numerical method and validated by the vibration experiment.By comparing with the frequency response curves of sandwich metamaterial plate with pure elastic rod core,improved band-gap properties are achieved from the designed metamaterial plate with composite periodic rod core.The elastic metamaterial plate with composite periodic rod core can generate more band-gaps,so it can suppress the vibration and elastic wave propagation in the structure more effectively.
文摘Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based?on their function and located at different places in the core where their feature is maximized.?Two methods of control rod calibration are the asymptotic period method and the rod-drop method, which were applied in this experiment. In the first method, the reactor is made supcritical by inserting the control rod to be calibrated a certain level. The rod drop method is to determine the subcritical;at the critical state, the rod to be calibrated is dropped into the core, and the resulting decay of neutron flux is observed and related to the reactivity. In this paper, the regulating rod will be calibrated according to the reactivity in OPR-1000 that corresponds to a certain control rod insert or withdraw, and the reactivity in power reactor depends?on the integral and differential control rod group too. The core simulator OPR1000 is used to test those methods.
文摘[目的]比较ARCOⅠ~Ⅱ期股骨头坏死(osteonecrosis of the femoral head,ONFH)髓芯减压多孔生物活性陶瓷棒置入是否联合磷酸三钙颗粒植入的临床疗效。[方法]2021年9月—2022年9月于本院就诊的60例(87髋)ARCOⅠ~Ⅱ期ONFH患者纳入本研究,采用随机数字表法将患者分为两组,其中,30例在髓芯减压后联合植入磷酸三钙颗粒和陶瓷棒(复合组),另外30例在髓芯减压后单纯置入陶瓷棒(单纯组)。比较两组围手术期、随访和影像资料。[结果]两组均顺利手术,无感染等并发症。两组的手术时间、切口长度、住院天数差异无统计学意义(P>0.05),复合组的术中失血量[mL,(65.7±14.7)vs(76.6±14.7),P=0.005]、术后引流量[mL,(101.4±9.8)vs(112.6±10.4),P<0.001]显著少于单纯组,尽管复合组的平均术中透视次数显著多于单纯组(P<0.001)。两组患者术后随访24个月以上,复合组恢复完全负重时间显著早于单纯组[d,(114.8±20.4)vs(154.6±21.2),P<0.001]。两组患者的VAS评分、Harris评分、髋伸-屈ROM和髋内旋-外旋ROM均显著改善(P<0.05)。术后12、24个月时,复合组的VAS、Harris评分和内旋-外旋ROM均显著优于单纯组(P<0.05),但两组伸-屈ROM的差异没有统计学意义(P>0.05)。截至末次随访,两组均无患者接受翻修THA。影像方面,随时间推移,两组ARCO分级、病灶面积、关节积液征像、股骨头塌陷及Tönnis分期均显著改善(P<0.05)。术后24个月时复合组的ARCO分级、关节积液征像、股骨头塌陷及Tönnis分期均显著优于单纯组(P<0.05)。[结论]ARCOⅠ~Ⅱ期ONFH的治疗中磷酸三钙人工骨颗粒联合多孔生物活性陶瓷棒的临床结果优于单纯多孔生物活性陶瓷棒置入。
基金supported by the National Natural Science Foundation of China (No.50774009)the National High Technology Research and Development Program of China (No.2009AA03Z532)
文摘A single forming equipment of bimetal continuous core-filling casting was designed and manufactured for the purpose of developing copper-aluminum composite materials.The characteristics of the equipment were as follows：the crystallizer composed of water jacket copper sleeve in which graphite sleeve was set, two melting furnaces with different diameters vertically distributed, the low furnace of melting copper linked with the crystallizer, continuous casting and core-filling proceeded at the meantime.The rational processing parameters were determined through a series of experiments：contact length from down crucible to water-cooling cupreous crystallizer, 20 mm;length of recooling spray jet under crystallizer, 95 mm;temperature of copper and aluminum, 1250-1320℃ and 700℃ respectively;pulling rate, 16 mm/min.The qualified copper-clad aluminum composite rods, the external and inner diameter of which was 40 mm and 24 mm respectively, could be drawn successfully on that basis.Tested by hydrostatic extrusion and drawing process, the boss ratios of the copperclad aluminum composite rods were maintained a relatively stable scope of about 0.59-0.65, which was not obviously changed by subsequent plastic processing.
文摘目的探讨髋关节镜直视下髋关节清理、富血小板血浆(platelet-rich plasma,PRP)精准注入联合钽棒植入术治疗早期股骨头坏死(osteonecrosis of the femoral head,ONFH)的临床疗效。方法选取2020年10月至2022年10月收治的早期ONFH患者50例(62髋),随机分为两组,其中观察组25例(32髋)采用关节镜直视下髋关节清理、PRP精准注入联合钽棒植入术治疗,对照组25例(30髋)采用单纯髓芯减压钽棒植入术治疗。术后第1、2、3、6、12个月门诊复查髋关节X线片,观察股骨头密度的变化,对髋关节Harris评分及疼痛视觉模拟评分(visual analogue scale,VAS)等指标进行评估。结果术后12个月髋关节X线片示,观察组患者股骨头外形良好,没有出现囊性变扩大或股骨头塌陷,内植物与骨整合良好,无松动移位发生;对照组有6例发生了股骨头塌陷,内植物与骨整合差,界限明显。末次随访时观察组效果明显优于对照组。观察组髋关节Harris评分由术前的(68.13±6.45)分提高到末次随访时的(89.64±7.14)分,对照组髋关节Harris评分由术前的(68.73±7.15)分提高到末次随访时的(78.64±7.14)分;观察组疼痛VAS评分由术前的(4.5±1.3)下降到末次随访时的(1.8±1.1)分,对照组疼痛VAS评分由术前的(4.3±1.2)下降到末次随访时的(2.3±1.3)分,均P<0.05。两组患者治疗后Harris和VAS评分对比差异具有统计学意义(P<0.05)。结论与单纯髓芯减压钽棒植入术相比,关节镜直视下髋关节清理、PRP精准注入联合钽棒植入术治疗早期股骨头坏死可以明显减轻患髋的疼痛症状、改善患髋的活动功能,并能促进新生骨长入,短期疗效显著,为临床治疗早期ONFH提供了一种新的方法。
