In order to analyze the hydrodynamic performance of the ducted propeller with high precision, this paper proposes a new method which combines Multi-Block Hybrid Mesh and Reynolds Stress Model (MBHM & RSM). The cal...In order to analyze the hydrodynamic performance of the ducted propeller with high precision, this paper proposes a new method which combines Multi-Block Hybrid Mesh and Reynolds Stress Model (MBHM & RSM). The calculation errors of MBHM & RSM and standard two-equation model (standard k-ε model) on the ducted propeller JD7704 +Ka4-55 are compared. The maximum error of the total thrust coefficient KT, the duct thrust coefficient KTN, the torque coefficient KQ and the open-water efficiency η0 of MBHM & RSM are 2.98%, 4.01%, 1.46%, and 0.89%, respectively, which are lower than those of standard k-ε model. Indeed, the pressure distribution on the propeller surfaces, the pressure and the velocity vector distribution of the flow field are also analyzed, which are consistent with the theory. It is demonstrated that MBHM & RSM on the thruster dynamics analysis are feasible. This paper provides reference in the thruster designing of underwater robot.展开更多
针对数模网格的手工检查及修补过于繁琐的实际问题,基于TCL/TK脚本语言,利用HyperMesh的API(Application Program Interface)接口编写代码,集成了自动划分网格、网格的检查、网格自动清理、重新划网格、网格修补等步骤,并利用跨平台窗...针对数模网格的手工检查及修补过于繁琐的实际问题,基于TCL/TK脚本语言,利用HyperMesh的API(Application Program Interface)接口编写代码,集成了自动划分网格、网格的检查、网格自动清理、重新划网格、网格修补等步骤,并利用跨平台窗体自定义界面直观显示网格修补方式,采用HyperMesh自有功能和自定义功能相结合的方式,集成了分割四边形、分割所有边、合并节点、添加Washer、Smooth、填补孔六种修补方法。并通过汽车后备箱盖实例验证,极大地提高了HyperMesh软件网格划分效率和质量,减小了人工操作出错的概率,为相关工作人员提供了便利工具,为后续企业开发工作积累经验。展开更多
In CAD/CAM, mesh rather than smooth surface is only needed sometimes. A mesh-generating method from permanence principle of Coons patch is developed. A new mesh point is defined through local small subpatch and all me...In CAD/CAM, mesh rather than smooth surface is only needed sometimes. A mesh-generating method from permanence principle of Coons patch is developed. A new mesh point is defined through local small subpatch and all mesh points are computed by a linear system with special symmetric block tridiagonal coefficient matrix. By simplification, the determinant of coefficient matrix is determined by determinants of submatrices. Condition of existence of solution is given. Whether coefficient matrix is singular can be judged by a simple polynomial function with the eigenvalue of submatrix as variable. Numerical examples demonstrate the effects of shape parameters.展开更多
Introduction:This study aimed to establish an animal model of open abdomen(OA)through temporary abdominal closure via different techniques.Methods:Adult male Sprague-Dawley rats were randomly divided into three groups...Introduction:This study aimed to establish an animal model of open abdomen(OA)through temporary abdominal closure via different techniques.Methods:Adult male Sprague-Dawley rats were randomly divided into three groups:group A(OA with polypropylene mesh alone);group B(OA with polypro-pylene mesh combined with a patch);and group C(OA with polypropylene mesh and a sutured patch).Vital signs,pathophysiological changes,and survival rates were closely monitored in the rats for 7 days after surgery.Abdominal X-rays and histopathological examinations were performed to assess abdominal organ changes and wound healing.Results:The results showed no significant difference in mortality rates among the three groups(p>0.05).However,rats in group B exhibited superior overall condi-tion,cleaner wounds,and a higher rate of wound healing compared to the other groups(p<0.05).Abdominal X-rays indicated that varying degrees of distal intestinal obstruction in all groups.Histopathological examinations revealed fibrous hyperpla-sia,inflammatory cell infiltration,neovascularization,and collagen deposition in all groups.Group B demonstrated enhanced granulation tissue generation,neovasculari-zation,and collagen deposition compared to the other groups(p<0.05).Conclusions:Polypropylene mesh combined with patches is the most suitable method for establishing an animal model of OA.This model successfully replicated the patho-logical and physiological changes in postoperative patients with OA,specifically the progress of abdominal skin wound healing.It provides a practical and reliable animal model for OA research.展开更多
提出了一种基于三角面元数据生成涂层目标时域有限差分(finite-difference time domain,FDTD)共形网格的方法。通过将原目标中各三角面元的顶点沿曲面在该点处的法线方向内移(内涂层)或外移(外涂层)所需的厚度,得到一组关于涂层的三角...提出了一种基于三角面元数据生成涂层目标时域有限差分(finite-difference time domain,FDTD)共形网格的方法。通过将原目标中各三角面元的顶点沿曲面在该点处的法线方向内移(内涂层)或外移(外涂层)所需的厚度,得到一组关于涂层的三角面元数据。其中曲面上各顶点处的法线方向近似等于包围该顶点的各三角面元的单位法向的矢量和。对于局部涂敷的情况,可根据需要只将涂敷部分所包含的三角面元顶点进行相应的移动,而其余顶点的位置保持不变。利用投影求交法,由原目标的三角面元数据和新生成的涂层三角面元数据即可得到共形FDTD计算所需要的共形网格参数。数值结果验证了方法的正确性和有效性。展开更多
目的比较聚丙烯小平片与改良Kugel补片在股疝修补术中应用的临床疗效。方法选取2012年7月至2016年12月期间郑州大学第一附属医院收治的99例原发性单侧成年股疝患者进行前瞻性研究。采用随机对照研究方法,按随机数字表法将入组患者分为...目的比较聚丙烯小平片与改良Kugel补片在股疝修补术中应用的临床疗效。方法选取2012年7月至2016年12月期间郑州大学第一附属医院收治的99例原发性单侧成年股疝患者进行前瞻性研究。采用随机对照研究方法,按随机数字表法将入组患者分为小平片组(采用聚丙烯小平片)和Kugel组(采用改良Kugel补片)。记录手术时间、术后切口疼痛评分(术后1周)、使用止痛药、术后住院时间及术后并发症(尿潴留、切口感染、血清肿、股静脉血栓形成等)情况,并在术后3个月、1年及2年对患者进行随访。随访内容包括慢性疼痛、异物感、生活质量及疝复发情况。结果 99例患者中,97例完成随访,纳入分析,其中Kugel组患者48例,小平片组49例。小平片组的手术时间短于Kugel组(P=0.030),但2组患者的止痛药使用率、术后住院时间、尿储留发生率、术后1周静息时切口疼痛视觉模拟评分(visual analog scale,VAS)及术后1周咳嗽时切口疼痛VAS评分比较差异均无统计学意义(P>0.05)。2组均无切口感染、血清肿及股静脉血栓形成发生。术后3个月、1年和2年时,2组患者的慢性疼痛发生率、异物感发生率和生活质量量表评分(36-item short-form general survey,SF-36)比较差异均无统计学意义(P>0.05)。97例患者获访,随访时间均为2年,随访期间2组均无疝复发。结论在股疝修补术中应用聚丙烯小平片同改良Kugel补片的效果近似,且手术时间一定程度缩短,具有一定的应用价值。展开更多
文摘In order to analyze the hydrodynamic performance of the ducted propeller with high precision, this paper proposes a new method which combines Multi-Block Hybrid Mesh and Reynolds Stress Model (MBHM & RSM). The calculation errors of MBHM & RSM and standard two-equation model (standard k-ε model) on the ducted propeller JD7704 +Ka4-55 are compared. The maximum error of the total thrust coefficient KT, the duct thrust coefficient KTN, the torque coefficient KQ and the open-water efficiency η0 of MBHM & RSM are 2.98%, 4.01%, 1.46%, and 0.89%, respectively, which are lower than those of standard k-ε model. Indeed, the pressure distribution on the propeller surfaces, the pressure and the velocity vector distribution of the flow field are also analyzed, which are consistent with the theory. It is demonstrated that MBHM & RSM on the thruster dynamics analysis are feasible. This paper provides reference in the thruster designing of underwater robot.
文摘针对数模网格的手工检查及修补过于繁琐的实际问题,基于TCL/TK脚本语言,利用HyperMesh的API(Application Program Interface)接口编写代码,集成了自动划分网格、网格的检查、网格自动清理、重新划网格、网格修补等步骤,并利用跨平台窗体自定义界面直观显示网格修补方式,采用HyperMesh自有功能和自定义功能相结合的方式,集成了分割四边形、分割所有边、合并节点、添加Washer、Smooth、填补孔六种修补方法。并通过汽车后备箱盖实例验证,极大地提高了HyperMesh软件网格划分效率和质量,减小了人工操作出错的概率,为相关工作人员提供了便利工具,为后续企业开发工作积累经验。
基金Supported by National Natural Science Foundation of China(No.60970097,No.11271376)
文摘In CAD/CAM, mesh rather than smooth surface is only needed sometimes. A mesh-generating method from permanence principle of Coons patch is developed. A new mesh point is defined through local small subpatch and all mesh points are computed by a linear system with special symmetric block tridiagonal coefficient matrix. By simplification, the determinant of coefficient matrix is determined by determinants of submatrices. Condition of existence of solution is given. Whether coefficient matrix is singular can be judged by a simple polynomial function with the eigenvalue of submatrix as variable. Numerical examples demonstrate the effects of shape parameters.
基金Postgraduate Research&Practice Innovation Program of Jiangsu Province,Grant/Award Number:SJCX23_0092National Natural Science Foundation of China,Grant/Award Number:82270595Jiangsu Provincial Medical Innovation Center,Grant/Award Number:CXZX202217。
文摘Introduction:This study aimed to establish an animal model of open abdomen(OA)through temporary abdominal closure via different techniques.Methods:Adult male Sprague-Dawley rats were randomly divided into three groups:group A(OA with polypropylene mesh alone);group B(OA with polypro-pylene mesh combined with a patch);and group C(OA with polypropylene mesh and a sutured patch).Vital signs,pathophysiological changes,and survival rates were closely monitored in the rats for 7 days after surgery.Abdominal X-rays and histopathological examinations were performed to assess abdominal organ changes and wound healing.Results:The results showed no significant difference in mortality rates among the three groups(p>0.05).However,rats in group B exhibited superior overall condi-tion,cleaner wounds,and a higher rate of wound healing compared to the other groups(p<0.05).Abdominal X-rays indicated that varying degrees of distal intestinal obstruction in all groups.Histopathological examinations revealed fibrous hyperpla-sia,inflammatory cell infiltration,neovascularization,and collagen deposition in all groups.Group B demonstrated enhanced granulation tissue generation,neovasculari-zation,and collagen deposition compared to the other groups(p<0.05).Conclusions:Polypropylene mesh combined with patches is the most suitable method for establishing an animal model of OA.This model successfully replicated the patho-logical and physiological changes in postoperative patients with OA,specifically the progress of abdominal skin wound healing.It provides a practical and reliable animal model for OA research.
文摘提出了一种基于三角面元数据生成涂层目标时域有限差分(finite-difference time domain,FDTD)共形网格的方法。通过将原目标中各三角面元的顶点沿曲面在该点处的法线方向内移(内涂层)或外移(外涂层)所需的厚度,得到一组关于涂层的三角面元数据。其中曲面上各顶点处的法线方向近似等于包围该顶点的各三角面元的单位法向的矢量和。对于局部涂敷的情况,可根据需要只将涂敷部分所包含的三角面元顶点进行相应的移动,而其余顶点的位置保持不变。利用投影求交法,由原目标的三角面元数据和新生成的涂层三角面元数据即可得到共形FDTD计算所需要的共形网格参数。数值结果验证了方法的正确性和有效性。
文摘目的比较聚丙烯小平片与改良Kugel补片在股疝修补术中应用的临床疗效。方法选取2012年7月至2016年12月期间郑州大学第一附属医院收治的99例原发性单侧成年股疝患者进行前瞻性研究。采用随机对照研究方法,按随机数字表法将入组患者分为小平片组(采用聚丙烯小平片)和Kugel组(采用改良Kugel补片)。记录手术时间、术后切口疼痛评分(术后1周)、使用止痛药、术后住院时间及术后并发症(尿潴留、切口感染、血清肿、股静脉血栓形成等)情况,并在术后3个月、1年及2年对患者进行随访。随访内容包括慢性疼痛、异物感、生活质量及疝复发情况。结果 99例患者中,97例完成随访,纳入分析,其中Kugel组患者48例,小平片组49例。小平片组的手术时间短于Kugel组(P=0.030),但2组患者的止痛药使用率、术后住院时间、尿储留发生率、术后1周静息时切口疼痛视觉模拟评分(visual analog scale,VAS)及术后1周咳嗽时切口疼痛VAS评分比较差异均无统计学意义(P>0.05)。2组均无切口感染、血清肿及股静脉血栓形成发生。术后3个月、1年和2年时,2组患者的慢性疼痛发生率、异物感发生率和生活质量量表评分(36-item short-form general survey,SF-36)比较差异均无统计学意义(P>0.05)。97例患者获访,随访时间均为2年,随访期间2组均无疝复发。结论在股疝修补术中应用聚丙烯小平片同改良Kugel补片的效果近似,且手术时间一定程度缩短,具有一定的应用价值。
