Modified surface tension model for free surface flow with single-phase lattice Boltzmann method

A single-phase lattice Boltzmann model with modified surface tension is developed in this paper to solve the problem of high-density-ratio free surface flow.The computational efficiency and accuracy are both enhanced.The restriction to the relaxation factor （which needs to be smaller than 1） is circumvented by the new surface tension algebra,due to its rational physical nature compared with the treatment of Xing,Buther and Yang in their paper （Comp.Mater.Sci.,2007,39（2）：282-290）.The proposed stable surface tension scheme is applied to simulate the free deformation of a square droplet with surface tension effect and the process of a droplet impinging on a liquid film.The numerical solution for free deformation of a droplet agrees well with thermodynamic principles,and also achieves high accuracy in comparison with Xing,et al.＇s model.Three typical impinging modes are successfully obtained with the new scheme,and another particular mode found by Wang and Chen is also successfully simulated.The evolutions of liquid crown agree well with the power law related to time.

定痛清浆散预防无张力疝修补术后血清肿的临床效果

目的:探究定痛清浆散预防无张力疝修补术后血清肿的临床效果。方法:以2022年1月—2023年6月新余市中医院收治的80例腹股沟疝患者为研究对象。所有患者均接受无张力疝修补术治疗,按随机数字表法,分成对照组(常规预防干预,n=40)和研究组(常规预防联合定痛清浆散干预,n=40)。比较两组临床围手术期相关指标、疼痛程度[视觉模拟评分法(VAS)]、血清肿发生率、血清肿体积、术区感染率、补片排异反应发生率、二次手术率及血清炎症因子[白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、C反应蛋白(CRP)]。结果:术后,研究组患者恢复饮食时间、下床时间均早于对照组,住院时间短于对照组(P<0.05)。两组术后7 d的VAS评分均低于术后1 d,且研究组术后7 d的VAS评分低于对照组(P<0.05)。研究组患者术后血清肿的发生率为7.50%,低于对照组的25.00%,且研究组发生血清肿的患者术后7 d血清肿体积小于对照组(P<0.05)。对照组术区感染发生率为20.00%,高于研究组的5.00%(P<0.05);两组患者补片排异反应发生率及二次手术率比较,差异均无统计学意义(P>0.05)。术后7 d,两组患者的IL-6、TNF-α、CRP水平均低于术前、术后1 d,且研究组均低于对照组(P<0.05)。结论:针对无张力疝修补术后患者,定痛清浆散预防血清肿的效果显著,可以促进患者恢复,减轻患者疼痛程度,降低术区感染率及血清炎症因子水平。

Numerical study of three-dimensional free surface dynamics

The dynamic problem of three-dimensional free surface is numerically studied in this paper. The ALE （Arbitrary Lagrange-Euler） kinematic description is introduced into the control equation system. The ALE description method is used to track free surface. Accurate formulations for calculating the normal vector on the free surface are presented. The discrete numerical equations by finite element method are developed by Galerkin weighted residual method. The boundary condition about free-surface tension is represented in the form of weak integration that can be computed by a differential geometry method derived in the present paper. The effect of contact angle is incorporated in the numerical algorithm. Furthermore, the numerical computations are performed and the comparison between computational and analytical results validated the effectiveness of the method. The results of this paper provide a fundamental understandings of the dynamics of liquid free surfaces, in which the surface tension and contact angle boundary conditions are taken into account. Finally, numerical simulation of largescale amplitude sloshing of liquid in a cylindrical container is performed and a numerical analysis of the effect of an annular ring-shaped rigid damping baffle on liquid sloshing oscillations in a cylindrical tank is also carried out.

Roughness-dependent wetting and surface tension of molten lead on alumina

Surface roughness is an important factor that affects the wetting of molten metal on ceramics.The effect of surface roughness of the alumina substrate on the contact angle,contact diameter,drop height and surface tension of molten lead was investigated in the temperature range of 923-1123 K.The microstructure of the lead/substrate interface was observed by SEM.The surface free energy of alumina substrates was calculated by the geometrical average method.When the surface roughness of the substrate increased from 0.092 to 2.23μm,the surface free energy increased gradually,ranging from 13.356 to 39.998 mJ/m^(2).The contact diameter of lead droplets decreased from 9.111 to 7.19 mm.The lead drop height increased from 3.41 to 3.85 mm.The contact angle increased from 113.05°to 137.15°.Moreover,the surface depression of the alumina substrate was filled with lead,and no obvious change was observed.The results demonstrated that the wetting of lead drop on alumina substrates was consistent with the Wenzel state.

A Surface Tension Model for Liquid Mixtures Based on NRTL Equation

A new equation for predicting surface tension is proposed based on the thermodynamic definition of surface tension and the expression of the Gibbs free energy of the system. Using the NRTL equation to represent the excess Gibbs free energy, a two-parameter surface tension equation is derived. The feasibility of the new equation has been tested in terms of 124 binary and 16 multicomponent systems(13-ternary and 3-quaternary) with absolute relative deviations of 0.59% and 1.55% respectively. This model is also predictive for the temperature dependence of surface tension of liquid mixtures. It is shown that, with good accuracy, this equation is simple and reliable for practical use.

Construction of Wave-free Potential in the Linearized Theory of Water Waves

Various water wave problems involving an infinitely long horizontal cylinder floating on the surface water were investigated in the literature of linearized theory of water waves employing a general multipole expansion for the wave potential. This expansion involves a general combination of a regular wave, a wave source, a wave dipole and a regular wave-free part. The wave-free part can be further expanded in terms of wave-free multipoles which are termed as wave-free potentials. These are singular solutions of Laplace's equation (for non-oblique waves in two dimensions) or two-dimensional Helmholz equation (for oblique waves) satisfying the free surface condition and decaying rapidly away from the point of singularity. The method of constructing these wave-free potentials is presented here in a systematic manner for a number of situations such as deep water with a free surface, neglecting or taking into account the effect of surface tension, or with an ice-cover modelled as a thin elastic plate floating on water.

Effect of Nd and La on surface tension and wettability of Sn-8Zn-3Bi solders

Maximum bubble pressure measurement was employed to evaluate surface tension of Sn-8Zn-3Bi- (00.15)Nd and Sn-8Zn-3Bi-(00.15)La solder melts. Wetting balance method was used to measure wetting force and wetting time on Cu substrate of the two group solders. The experimental results show that minute amount of Nd or La addition to Sn-8Zn-3Bi solder causes significant decrease of the surface tension of the solder melts at 200240℃ and Nd addition is more effective on reduction of surface tension than that of La. Nd or La addition has the effect on enhancing the wetting force of the solder melts on Cu substrate, which results from the decrease of interfacial tension between the solder melt and Cu substrate. The wetting force reaches the maximum when 0.1% Nd is added to the base alloy. The contact angle between Sn-8Zn-3Bi base solders and Cu substrate decreases with the addition of Nd or La and the minimum of the contact angle is obtained from the solder with 0.1% Nd addition.

Analysis of the Causes of Chronic Pain after Inguinal Hernia Repair without Tension and Its Prevention and Treatment

Purpose: Analyzing the causes of pain after tension-free repair in the inguinal hernia, and propose corresponding treatment strategies. Results: The patients in this group were followed up for 3 - 12 months. A total of 5 patients still had pain relief within 3 months after surgery. Further treatment was needed, and the incidence rate was 5%. Conclusion: Skilled surgical procedures are performed in patients with local anesthesia, and some of the absorbable repair materials can be used. The improved patch fixation and extra peritoneal repair can reduce the pain after inguinal hernia repair without tension.

Theoretical Mechanism Analysis of 3D Free Surface Electrospinning

Electrospinning is a new type of free-end spinning built on the electric field. The electric force of polyacrylonitrile( PAN)polymer solution overcomes the surface tension of the solution,and then it causes wave and forms jet flow. In the process of injection,the solution is evaporated or solidified,eventually forming a fiber on the receiving device. Different from ordinary single needle head,in the study,a new type of 3D free surface spinneret is used to produce multiple jets at the same time, and this will greatly improve production efficiency. In the paper,the model of 3D free surface is analyzed by the theory of fluid mechanics. The relationship among the wave length,surface tension and the electric field is obtained.After the mechanical analysis on the stable period of the jet,the relationship between the jet radius and the distance from the spinneret to jet is carried out. At the same time the relationship between the jet velocity and the tensile force is carried out. After mechanics analyzing on the unstable period of the jet,it can be concluded that the radius of the jet is inversely proportional to one half power of the distance from the jet to the spinneret,and the electrostatic spinning jet's velocity is directly proportional to one half power of the tensile force. After the mechanical analysis of the unstable period of the electrospinning jet,it can be concluded that the radius of the jet is inversely proportional to one fourth power of the jet intercept point distance.

A New Model for Prediction of Surface Tension of Pure Fluids

A new model based on the theoretical work of Boudh-Hir and Mansoori was developed for prediction of surface tension of pure fluids. The new model has the advantage of not requiring densities in the calculation, and the input parameters are critical temperature and connectivity indices. A total of 209 compounds covering a wide variety of substances were used to develop the model, and the overall correlative AAD is 4.21%. To test its predictive ability, the model is further used to predict the surface tension of 25 more compounds that were not included in the model development. The overall predictive AAD is 4.07%, which illustrates that the model is reliable. The model proposed is simple and easy to apply, with good predictive accuracy.

Oblique Wave-free Potentials for Water Waves in Constant Finite Depth

In this paper, a method to construct oblique wave-free potentials in the linearised theory of water waves for water with uniform finite depth is presented in a systematic manner. The water has either a free surface or an ice-cover modelled as a thin elastic plate. For the case of free surface, the effect of surface tension may be neglected or taken into account. Here, the wave-free potentials are singular solutions of the modified Helmholtz equation, having singularity at a point in the fluid region and they satisfy the conditions at the upper surface and the bottom of water region and decay rapidly away from the point of singularity. These are useful in obtaining solutions to oblique water wave problems involving bodies with circular cross-sections such as long horizontal cylinders submerged or half-immersed in water of uniform fmite depth with a free surface or an ice-cover modelled as a floating elastic plate. Finally, the forms of the upper surface related to the wave-free potentials constructed here are depicted graphically in a number of figures to visualize the wave motion. The results for non-oblique wave-free potentials and the upper surface wave-free potentials are obtained. The wave-free potentials constructed here will be useful in the mathematical study of water wave problems involving infinitely long horizontal cylinders, either half-immersed or completely immersed in water.

Tension-reduced closure of large abdominal wall defect caused by shotgun wound:A case report

BACKGROUND Large abdominal wall defect(LAWD)caused by shotgun wound is rarely reported.CASE SUMMARY Herein,we describe a case of LAWD caused by a gunshot wound in which the abdominal wall was reconstructed in stages,including debridement,tensionreduced closure(TRC),and reconstruction with mesh and a free musculocutaneous flap.During a 3-year follow-up,the patient recovered well without hernia or other problems.CONCLUSION TRC is a practical approach for the temporary closure of LAWD,particularly in cases when one-stage abdominal wall restoration is unfeasible due to significant comorbidities.

基于FreeRTOS和STM32的步进拉力仪设计与实现

以ARMCortex-M3处理器STM32F103ZET6为核心,结合步进电机和迪文DGUS触摸显示屏,设计触摸屏式拉力仪。在此硬件基础上,嵌入式软件系统采用FreeRTOS实时操作系统,充分利用FreeRTOS的多任务调度、任务通信、任务同步和软时钟等功能。以模块化思想编写系统软件,降低和功能模块之间的耦合性,使软件系统流程变得简洁流畅。以Q2HB34MA等角度恒力矩细分型驱动器与步进电机组成电机模块、以迪文DGUS屏设计出显示模块、以力值传感器及采集电路组成数据采集模块。该步进拉力仪为高精度仪器,在纸张抗张力的测量领域有着广泛的应用,在拉伸力强度大的铝箔测量行业、铝塑带行业也能精确的对测试产品进行测量。

镜疝修补术与开放式无张力疝修补术治疗腹股沟疝疗效对比研究

目的对比研究镜疝修补术治疗腹股沟疝的临床疗效。方法方便选取2019年6月—2023年10月启东市第二人民医院收治的123例腹股沟疝患者,采用密闭信封法分为对照组(n=61)、研究组(n=62)。对照组行开放式无张力疝修补术,研究组行镜疝修补术。比较两组围术期指标及并发症发生率。结果研究组手术时间长于对照组,其他指标优于对照组,差异有统计学意义(P均<0.05)。研究组并发症发生率(3.23%)低于对照组(14.75%),差异有统计学意义(χ^(2)=4.768,P<0.05)。结论镜疝修补术治疗腹股沟疝的效果优于传统术式,该手术方式具有微创性,对患者机体损伤较轻,同时,该种术式能够降低并发症风险,具有较高的安全性,有利于患者术后机体康复,从而改善患者预后。

不同术式治疗腹股沟疝患者的效果

目的:比较腹腔镜经腹腹膜前腹股沟疝修补术(TAPP)、腹腔镜全腹腹膜外腹股沟疝修补术(TEP)与传统无张力疝修补术治疗腹股沟疝患者的效果。方法:选取2021年3月至2023年1月该院收治的141例腹股沟疝患者进行前瞻性研究,依据随机数字表法将其分为传统组、腹腔镜A组、腹腔镜B组各47例。传统组行无张力疝修补术治疗,腹腔镜A组行TAPP治疗,腹腔镜B组行TEP治疗,比较三组围术期指标水平、术后疼痛程度[视觉模拟评分法(VAS)]评分、手术前后应激指标水平[皮质醇(Cor)、去甲肾上腺素(NE)、促肾上腺皮质激素(ACTH)]水平、术后1周内并发症发生率和随访3个月的复发率。结果:腹腔镜A、B组手术时间、肠道功能恢复时间均长于传统组,下床活动时间均短于传统组,术中失血量均少于传统组,差异有统计学意义(P<0.05);腹腔镜B组手术时间、下床活动时间均短于腹腔镜A组,差异有统计学意义(P<0.05);腹腔镜A、B组术中失血量、肠道功能恢复时间比较,差异均无统计学意义(P>0.05);腹腔镜A、B组术后1 d、3 d和1周VAS评分比较,差异均无统计学意义(P>0.05);术后3d,三组血清ACTH、NE、Cor水平均高于术前1 d,但腹腔镜B组<腹腔镜A组<传统组,差异有统计学意义(P<0.05);三组并发症发生率、复发率比较,差异均无统计学意义(P>0.05)。结论:TEP、TAPP治疗腹股沟疝患者下床活动时间均短于传统无张力疝修补术治疗,术中失血量均少于传统无张力疝修补术治疗;TEP治疗腹股沟疝患者的手术时间、下床活动时间均短于TAPP治疗,应激指标水平均低于TAPP治疗和传统无张力疝修补术治疗,三种术式各有利弊。

加强手术室护理干预对腹股沟斜疝患者无张力疝修补术麻醉苏醒期躁动的影响

目的:分析加强手术室护理干预对腹股沟斜疝患者无张力疝修补术麻醉苏醒期躁动的影响。方法:选取2021年3月—2023年3月滨州医学院附属医院收治的腹股沟斜疝患者78例为观察对象,按照随机数字表法分为对照组和观察组,各39例。对照组接受常规手术室护理,观察组在对照组基础上进行加强手术室护理干预。比较两组苏醒期躁动发生率、意识恢复情况以及苏醒期血压、心率。结果:观察组苏醒期躁动发生率低于对照组,差异有统计学意义(P=0.023);观察组苏醒时间、拔管时间短于对照组,差异有统计学意义(P<0.05);观察组苏醒期收缩压、舒张压、心率均低于对照组,差异有统计学意义(P<0.001)。结论:加强手术室护理干预可预防腹股沟斜疝患者无张力疝修补术苏醒期躁动的发生,缩短患者麻醉苏醒时间,维持生命体征稳定。

CFS悬吊联合提肌复合体无张力缩短术矫正中重度上睑下垂效果观察

目的:观察筋膜鞘(Conjoint fascial sheath,CFS)悬吊联合提肌复合体无张力缩短矫正术对中重度上睑下垂患者的矫治效果。方法:选取笔者医院2019年1月-2022年10月收治的中重度上睑下垂患者128例(238只眼),按手术方式不同分为两组,其中CFS悬吊组66例(122只眼,采用单纯CFS悬吊),联合组62例(116只眼,采用CFS悬吊联合提肌复合体无张力缩短矫正术)。比较两组矫正效果,眼睑状况,眼表功能指标,并发症发生情况,复发率和美学效果。结果:联合组有效矫正率(98.28%)显著高于CFS悬吊组有效矫正率(92.32%)(P<0.05);联合组术后1个月和术后3个月睑裂高度和上睑缘角膜映光距离低于CFS悬吊组(P<0.05);术后1个月,两组FL均高于术前(P<0.05);术后3个月,两组FL均低于术后1个月(P<0.05),两组术后1个月FL比较差异有统计学意义(P<0.05);两组手术前后BUT和SIt比较差异无统计学意义(P>0.05);两组并发症总发生率和复发率差异无统计学意义(P>0.05);联合组美学效果(眼睑弧度、眼睑高度对称性和双重睑)评分显著高于CFS悬吊组(P<0.05)。结论:CFS悬吊联合提肌复合体无张力缩短矫正术治疗中重度上睑下垂患者矫治效果确切,能改善患者眼睑状态,对眼表功能影响较小,并发症发生率低,值得推广应用。

4种喷雾助剂对25%噻虫嗪水分散粒剂在豇豆叶片表面润湿性能的影响

为筛选适用于豇豆的农药喷雾助剂,使药液在作物表面起到更好的铺展效果。首先用扫描电镜观察了豇豆叶片近、远轴面的叶片结构,然后通过测定接触角计算豇豆叶片的临界表面张力和表面自由能,最后测定了25%噻虫嗪水分散粒剂(thiamethoxam WG)与加入4种喷雾助剂后,不同浓度药液的表面张力以及液滴在豇豆叶片上的静态、动态接触角。结果表明:25%噻虫嗪水分散粒剂不同浓度稀释药液的表面张力均大于豇豆叶片的临界表面张力,表明该制剂本身不能在豇豆叶片上很好地润湿铺展;当药液1250倍稀释液分别加入助剂0.4%silwet stik、0.5%迈丝后,药液的表面张力分别为24.58 mN/m和31.07 mN/m,小于豇豆叶片的临界表面张力32.31 mN/m。该药液1250倍稀释液加入体积分数为0.5%助剂迈丝后,其动态接触角下降速率与其他3种助剂相比快,60 s后接触角为39.68°。因此在使用25%噻虫嗪水分散粒剂喷施豇豆叶片时,建议在稀释倍数为1250倍的药液中添加0.5%助剂迈丝,有助于药液在豇豆叶片上的润湿效果。

基于包缠结构羊毛腈纶纱的制备及性能分析

为了探索基于包缠结构羊毛混纺纱的性能,采用平行纺技术,以羊毛纤维须条为芯纱、腈纶长丝为外包纤维制备包缠结构纱线。通过优选包缠捻度,综合分析包缠结构纱线的强伸性能、毛羽、外观等质量指标。结果表明:当纺纱号数为44 tex,张力系数设置为1.1,锭速选择2000 r/min,设计牵伸为40倍时,优选出最佳包缠捻度为400捻/m。与同号数的常规环锭纺纯羊毛纱相比较,包缠结构羊毛纱不仅更柔软,条干等指标也有明显改善。

腹腔镜下经腹腹膜前间隙疝修补术治疗老年嵌顿性腹股沟疝患者的效果

目的:观察腹腔镜下经腹腹膜前间隙疝修补术治疗老年嵌顿性腹股沟疝患者的效果。方法:选取2020年1月至2022年12月该院收治的121例老年嵌顿性腹股沟疝患者进行前瞻性研究,根据随机数字表法将其分为对照组60例和观察组61例。对照组采用无张力疝修补术治疗,观察组采用腹腔镜下经腹腹膜前间隙疝修补术治疗,比较两组围手术指标水平、手术前后疼痛程度[视觉模拟评分法(VAS)]评分、创伤应激反应指标[前列腺素E_(2)(PGE_(2))、促肾上腺皮质激素释放激素(CRH)、促肾上腺皮质激素(ACTH)]水平和术后1周并发症发生率。结果:观察组手术时间长于对照组,肛门排气时间和下床活动时间均短于对照组,术中出血量少于对照组,差异有统计学意义(P<0.05);术后,观察组VAS评分低于对照组,差异有统计学意义(P<0.05);术后,两组PGE_(2)、CRH、ACTH水平均高于术前,但观察组低于对照组,差异有统计学意义(P<0.05);两组术后并发症发生率比较,差异无统计学意义(P>0.05)。结论:腹腔镜下经腹腹膜前间隙疝修补术治疗老年嵌顿性腹股沟疝患者可改善围手术指标水平,降低VAS评分和创伤应激反应指标水平,效果优于无张力疝修补术治疗。