Control of Nozzle Flow Using Rectangular Ribs at Sonic and Supersonic Mach Numbers

This study deals with base pressure management in a duct for various values of the Mach number(M),namely,Mach number corresponding to sonic and four supersonic conditions.In addition to the Mach number,the nozzle pressure ratio(NPR),the area ratio,the rib dimension,and the duct length are influential parameters.The following specific values are examined at M=1,1.36,1.64,and 2,and NPRs between 1.5 and 10.The base pressure is determined by positioning ribs of varying heights at predetermined intervals throughout the length of the square duct.When the level of expansion is varied,it is seen that the base pressure initially drops for overexpanded flows and increases for under-expanded flows.When ribs are present,the flow field in the duct and pressure inside the duct fluctuate as the base pressure rises.Under-expanded flows can achieve a base pressure value that is suitably high without experiencing excessive changes in the duct flow in terms of static pressure if a rib height around 10%of the duct height close to the nozzle exit is considered.Rectangular rib passive control does not negatively affect the duct’s flow field.

Numerical Simulation Analysis of Welded Joints in Arch Ribs of Large Span Steel Pipe Arch Bridges

In order to study the residual stress distribution law of welded joints of arch ribs of large-span steel pipe concrete arch bridges,numerical simulation of temperature,stress and strain fields based on ABAQUS for welded joints of arch-ribbed steel tubes using 7-,8-and 9-layer welds is carried out and its accuracy is demonstrated.The steel pipe welding temperature changes,residual stress distribution,different processes residual stress changes in the law,the prediction of post-weld residual stress distribution and deformation are studied in this paper.The results show that the temperature field values and test results are more consistent with the accuracy of numerical simulation of welding,the welding process is mainly in the form of heat transfer;Residual high stresses are predominantly distributed in the Fusion zone(FZ)and Heat-affected zone(HAZ),with residual stress levels tending to decrease from the center of the weld along the axial path,the maximum stress appears in the FZ and HAZ junction;The number of welding layers has an effect on the residual stress distribution,the number of welding layers increases,the residual stress tends to decrease,while the FZ and HAZ high stress area range shrinks;Increasing the number of plies will increase the amount of residual distortion.

The influence of inter-band rock on rib spalling in longwall panel with large mining height

In order to improve rib stability,failure criteria and instability mode of a thick coal seam with inter-band rock layer are analysed in this study.A three-dimensional mechanical model is established for the rib by considering the rock layer.A safety factor is defined foy the rib,and it is observed that the safety factor exhibits a positive correlation with the thickness and strength of the inter-band rock.A calculation method for determining critical parameters of the rock layer is presented to ensure the rib stability.It is revealed that incomplete propagation of the fracture at the hard rock constitutes a fundamental prerequisite for ensuring the rib stability.The influence of the position of the inter-band rock in the coal seam on failure mechanism of the rib was thoroughly investigated by developing a series of physical models for the rib at the face area.The best position for the inter-band rock in the coal seam is at a height of 1.5 m away from the roof line,which tends to provide a good stability state for the rib.For different inter-band rock positions,two ways of controlling rib by increasing supports stiffness and flexible grouting reinforcement are proposed.

Current practice in autologous rib and costal-cartilage harvest for rhinoplasty:A systematic review

Background:Autologous costal grafts are used universally in clinical practice for rhinoplasty and reconstruction.However,surgeons worldwide have not agreed on the details of graft harvesting,including rib selection,side preference,operation mode,cutting methods,and handling of the periosteum and perichondrium.This study aimed to provide an overview of the novel techniques used for auto-rib harvesting in rhinoplasty within the past 5 years and identify potential avenues for future research.Methods:We searched for related articles in PubMed,Embase,and Web of Science from 2019 to 2023,summa-rized crucial but controversial steps in recent practice,and analyzed their theoretical basis and clinical feasibility.Results:Auto-rib and cartilage open harvest is still mainstream in rhinoplasty and reconstruction,with the 5th to 8th ribs and cartilage being the most used.The laparoscopic harvest is gaining attention,being second only to the open harvest,with the 9th/10th ribs and cartilages being particularly convenient.The clinical applications of full-cut and split-cut methods differ in their advantages.Except for some special reasons,almost all studies tended to preserve the periosteum and perichondrium in situ,and few surgeons chose to harvest the grafts on the left side.Conclusion:Multiple techniques have emerged,requiring surgeons to balance the benefits and risks of various strategies at each step.New theories and techniques should be fully tested promptly and in clinical practice before wide application.Overall,a professional consensus is needed for better directivity,precision,and stability in clinical practice.

Bearing mechanism of roof and rib support structure in automatically formed roadway and its support design method

Non-pillar mining technology with automatically formed roadway is a new mining method without coal pillar reservation and roadway excavation.The stability control of automatically formed roadway is the key to the successful application of the new method.In order to realize the stability control of the roadway surrounding rock,the mechanical model of the roof and rib support structure is established,and the influence mechanism of the automatically formed roadway parameters on the compound force is revealed.On this basis,the roof and rib support structure technology of confined lightweight concrete is proposed,and its mechanical tests under different eccentricity are carried out.The results show that the bearing capacity of confined lightweight concrete specimens is basically the same as that of ordinary confined concrete specimens.The bearing capacity of confined lightweight concrete specimens under different eccentricities is 1.95 times higher than those of U-shaped steel specimens.By comparing the test results with the theoretical calculated results of the confined concrete,the calculation method of the bearing capacity for the confined lightweight concrete structure is selected.The design method of confined lightweight concrete support structure is established,and is successfully applied in the extra-large mine,Ningtiaota Coal Mine,China.

Rib Osteosynthesis for Sub-Acute Management of a Flail Chest in a Tertiary Centre in a Low-Middle Income Country of Sub-Saharan Africa: Case Report at Douala Laquintinie Hospital

Background: Costal fracture surgical is still a debate, therefore we shall select between early and delay surgical management. Case Report: We are reporting two cases of post road traffic clash delay ribs fractures osteosynthesis involving a 63-year-old man with multistage fractures on the left and pulmonary pinning of one of the costal arches, complicated by a homolateral haemothorax and a 41-year-old man with a bilateral flail chest. Conclusion: The simple postoperative course and the immediate postoperative improvement in the patient’s clinical respiratory condition enabled us to discuss the time frame for management, in this case the indication for early or later surgery.

Application of Grooved Negative Pressure Drainage Tube in Surgical Stabilization of Rib Fractures

Objective: To explore the application value of disposable grooved negative pressure drainage tubes in rib fracture incision and internal fixation. Methods: Seventy-five patients admitted to our Department of Trauma Surgery from June 2022 to April 2024 who underwent rib fracture osteotomy and internal fixation were selected. According to the types of drainage tubes left in the patients after the operation, they were divided into the observation group (35 cases who were left with disposable grooved negative pressure drainage tubes) and the control group (40 cases who were left with closed silicone thoracic drainage tubes). Comparison of chest drainage, pain, postoperative complications, secondary chest penetration rate, drain placement time, hospitalization time, and treatment costs were compared between the two groups. Results: The total postoperative chest drainage volume of the observation group was less than that of the control group (P < 0.05);the degree of pain, the incidence of postoperative complications, and the rate of secondary chest puncture in the observation group were lower than that of the control group three days after the operation (P < 0.05);and the time of drain placement in the observation group was shorter than that of the control group (P < 0.05). Conclusion: The application of disposable grooved negative pressure drainage tubes in rib fracture incision and internal fixation can significantly improve patients’ postoperative pain and discomfort, reduce complications, lower the rate of secondary chest penetration, promote patients’ postoperative recovery, decrease the amount of postoperative chest drainage, and shorten the time of drain placement, which is worthy of clinical promotion and application.

G^1端点约束的Bézier曲线曲面的Ribs和Fans

为了得到Bézier曲线曲面的更加适用于网络传输的分解和重构算法,研究了带1阶端点(角点)约束的Bézier曲线曲面的Ribs和Fans,并且得到了相应的曲线曲面的光滑部分和细节部分.反过来,给定Bézier曲线的光滑部分和细节部分,给出了重构原曲线的算法.另外,还把Ribs和Fans的概念与算法推广到三角Bézier曲面.1张n次的三角Bézier曲面能够分解为1张n-1次的Rib、1张n-3次的Fan和3条n-4次Bézier曲线(Fans).数值例子表明对曲线曲面的光滑部分和细节部分的分解是更优与更有效的.

Superplastic Microforming of Zn-A122 Alloy Ribs

Research on microforming of fine-grained superplastic Zn-AI22 alloy was carried out in this paper by means of superplastic forming. With the selected material, microformability tests have been carried out with the specially developed evaluation method by using two kinds of stainless steel dies. With these dies, micro-extrusion tests have been carried out and the characteristics of microformability of the material have been clarified. Effects of processing parameters and die structure on forming have been analyzed. SEM and metallographic microscope have been used to analyze the formed specimens. Through analysis of flow lines of the formed specimen, behavior of material could be understood well.

Influence of ribs on train aerodynamic performances

The influence of ribs on the train aerodynamic performance was computed using detached eddy simulation(DES), and the transient iteration was solved by the dual-time step lower-upper symmetric Gauss-Seidel(LU-SGS) method. The results show that the ribs installed on the roof have a great effect on the train aerodynamic performance. Compared with trains without ribs, the lift force coefficient of the train with convex ribs changes from negative to positive, while the side force coefficient increases by 110%and 88%, respectively. Due to the combined effect of the lift force and side force, the overturning moment of the train with convex ribs and cutting ribs increases by 140% and 106%, respectively. There is larger negative pressure on the roof of the train without ribs than that with ribs. The ribs on the train would disturb the flow structure and contribute to the air separation, so the separation starts from the roof, while there is no air separation on the roof of the train without ribs. The ribs can also slow down the flow speed above the roof and make the air easily sucked back to the train surface. The vortices at the leeward side of the train without ribs are small and messy compared with those of the train with convex or cutting ribs.

Chest pain caused by multiple exostoses of the ribs: A case report and a review of literature

The aim of this paper is to report an exceptional case of multiple internal exostoses of the ribs in a young patient affected by multiple hereditary exostoses(MHE) coming to our observation for chest pain as the only symptom of an intra-thoracic localization. A 16 years old patient with familiar history of MHE came to our observation complaining a left-sided chest pain. This pain had increased in the last months with no correlation to a traumatic event. The computed tomography(CT) scan revealed the presence of three exostoses located on the left third, fourth and sixth ribs, all protruding into the thoracic cavity, directly in contact with visceral pleura. Moreover, the apex of the one located on the sixth rib revealed to be only 12 mm away from pericardium. Patient underwent video-assisted thoracoscopy with an additional 4-cm mini toracotomy approach. At the last 1-year followup, patient was very satisfied and no signs of recurrence or major complication had occured. In conclusion, chest pain could be the only symptom of an intra-thoracic exostoses localization, possibly leading to serious complications. Thoracic localization in MHE must be suspected when patients complain chest pain. A chest CT scan is indicated to confirm exostoses and to clarify relationship with surrounding structures. Video-assisted thoracoscopic surgery can be considered a valuable option for exostoses removal, alone or in addiction to a mini-thoracotomy approach, in order to reduce thoracotomy morbidity.

Experimental and Numerical Study on Heat Transfer Enhancement of a Rectangular Channel with Discontinuous Crossed Ribs and Grooves

Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investigated the overall heat transfer performance and friction factor in ribbed and ribbed-grooved channels with rib angle of 30°.The experimental results show that the overall thermo-hydraulic performance for ribbed-grooved channel is increased by 10%-13.6% when compared to ribbed channel.The investigation on the effects of different rib angles and rib pitches on heat transfer characteristics and friction factor in ribbed-grooved channel was carried out using Fluent with SST(shear-stress transport) k-ω turbulence model.The numerical results indicate that the case for rib angle of 45° shows the best overall thermo-hydraulic performance,about 18%-36% higher than the case for rib angle of 0°.In addition,the flow patterns and local heat transfer characteristics for ribbed and ribbed-grooved channels based on the numerical simulation were also analyzed to reveal the mechanism of heat transfer enhancement.

Study of the temperature rise induced by a focusing transducer with a wide aperture angle on biological tissue containing ribs

We used the spheroidal beam equation to calculate the sound field created by focusing a transducer with a wide aperture angle to obtain the heat deposition, and then we used the Pennes bioheat equation to calculate the temperature field in biological tissue with ribs and to ascertain the effects of rib parameters on the temperature field. The results show that the location and the gap width between the ribs have a great influence on the axial and radial temperature rise of multilayer biological tissue. With a decreasing gap width, the location of the maximum temperature rise moves forward; as the ribs are closer to the transducer surface, the sound energy that passes through the gap between the ribs at the focus decreases, the maximum temperature rise decreases, and the location of the maximum temperature rise moves forward with the ribs.

米曲霉RIB40高效同源重组和尿苷/尿嘧啶营养缺陷型菌株的构建

目的:以米曲霉RIB40为出发菌株,构建具有高同源重组效率的营养缺陷型菌株。方法:首先通过同源重组技术和5-氟乳清酸(5-Fluoroorotic Acid,5-FOA)对尿苷/尿嘧啶营养缺陷的筛选作用,获得AopyrG基因缺失的米曲霉RIB40。然后利用烟曲霉AfpyrG基因替换Aoku70得到ΔAoku70敲除菌株,再通过5-FOA的筛选作用使得ΔAoku70菌株基因组发生自身环化,丢失AfpyrG基因。最后为了检验ΔAoku70ΔAopyrG菌株的可用性,将编码红色荧光蛋白的mCherry基因敲入至双突变菌株的组蛋白H2B基因上,并通过激光共聚焦显微镜观察红色荧光蛋白质的亚细胞定位。结果:通过AopyrG和Aoku70的双基因敲除,获得了高同源重组效率的营养缺陷型菌株ΔAoku70ΔAopyrG。用激光共聚焦观察到红色荧光蛋白定位于细胞核,表明ΔAoku70ΔAopyrG菌株可用于米曲霉的基因改造。结论:ΔAoku70ΔAopyrG菌株可作为一个高同源重组效率的营养缺陷型出发菌株用于今后米曲霉RIB40的遗传改良。

Numerical Study of Turbulent Periodic Flow and Heat Transfer in a Square Channel with Different Ribs

A numerical investigation has been carried out to examine turbulent flow and heat transfer characteristics in a three-dimensional ribbed square channels. Fluent 6.3 CFD code has been used. The governing equations are discretized by the second order upwind differencing scheme, decoupling with the SIMPLE (semi-implicit method for pressure linked equations) algorithm and are solved using a finite volume approach. The fluid flow and heat transfer characteristics are presented for the Reynolds numbers based on the channel hydraulic diameter ranging from 104 to 4 ′ 104. The effects of rib shape and orientation on heat transfer and pressure drop in the channel are investigated for six different rib configurations. Rib arrays of 45° inclined and 45° V-shaped are mounted in inline and staggered arrangements on the lower and upper walls of the channel. In addition, the performance of these ribs is also compared with the 90° transverse ribs.

Memory alloy embracing fixator in treatment of multiple fractured ribs and flail chest

BACKGROUND： With the development of internal fixation materials, simple operation with internal fixation has become a tendency. Ni-Ti shape memory alloy embracing fixator has such advantages as slight injury, easy operation, security, reliable fixation, and better histocompatibility. The present study was to explore curative effect and postoperative results of Ti-Ni shape memory alloy embracing ？ xator in patients with multiple fractured ribs and ？ ail chest.METHODS： The curative effect and long-term follow-up results were observed after internal ？ xation with a shape memory alloy embracing ？ xator in patients with multiple fractured ribs and ？ ail chest from January 2006 to December 2009.RESULTS： All patients were cured with an average hospital stay of 10.31±3.14 days. Post-operative pain was less severe than preoperative pain （P=0.02）.The rate of postoperative complications such as atelectasis, pulmonary infection, etc was 17.65%. There were fewer long-term complications and less in？ uence on daily work and life.CONCLUSIONS： It is practical to perform an operation for fracture of multiple ribs using a Ti-Ni shape memory alloy embracing ？ xator. The ？ xator, which is less traumatic, simple, safe, and reliable, has a good-histocompatibility and fewer postoperative complications.

Multi-pass spinning of thin-walled tubular part with longitudinal inner ribs

Based on the process experiments, micrography analysis was dedicated to advancing the understanding of plastic flow of the metal in backward ball spinning of thin-walled tubular part with longitudinal inner ribs. Micrography analysis reveals that severe plastic deformation leads to grain refinement, grain orientation and grain flow line of the spun part. Based on rigid-plastic finite element method, DEFORME3D finite element code was used to simulate and analyze multi-pass backward ball spinning of thin-walled tubular part with longitudinal inner ribs. Finite element simulation results involve the distributions of the strain, the shape variation of the inner ribs as well as the prediction of the spinning loading.

Preliminary rib support requirements for solid coal ribs using a coal pillar rib rating(CPRR)

Researchers from the National Institute for Occupational Safety and Health(NIOSH)are developing a coal pillar rib rating(CPRR)technique to measure the integrity of coal ribs.The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs.The CPRR utilizes four parameters:rib homogeneity,bedding condition,face cleat orientation with respect to entry direction,and rib height.All these parameters are measurable in the field.A rib data collecting procedure and a simple sheet to calculate the CPRR were developed.The developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden depth.CPRR calculations were conducted for 22 surveyed solid coal ribs,mainly composed of coal units.Based on this study,the rib performance was classified into four categories.A preliminary minimum primary rib support density(PRSD)line was obtained from these surveyed cases.Two sample cases are presented that illustrate the data collection form and CPRR calculations.

General issues of FEM in backward ball spinning of thin-walled tubular part with longitudinal inner ribs

Backward ball spinning was applied for manufacturing thin-walled tubular parts with longitudinal inner ribs. Rigid-plastic finite element method(FEM) was used for simulating the backward ball spinning process in order to calculate the height of the inner ribs. With a view to guarantee a better simulation accuracy, it is essential to enhance and improve some general problems of FEM, such as generation of initial velocity field, choice of penalty factor, determination of boundary conditions, treatment of rigid region and description of convergence criteria. It is evident that whether the problems with respect to FEM are dealt with appropriately or not, they have a significant influence on the modeling accuracy and efficiency. By reasonable solving the general problems, rigid-plastic FEM can successfully simulate the height of the inner ribs and the calculated values are in good agreement with the measured values.

Fabrication of Barrier Ribs for PDP by Capillary Infiltration Process and Their Sintering Behavior

Closed-cell type barrier ribs such as meander, honeycomb, SDR, and waffle types were produced using capillary molding process. Sintering of the ribs revealed that the ribs with asymmetric geometry such as meander and SDR type became distorted severely by the sintering process, but the ribs with symmetric geometry such as honeycomb and waffle type maintained their green state morphology. After sintering, the ribs were coated with green phosphor using osmosis coating process and its luminance characteristics were evaluated. The results indicated that the luminance and its efficiency is improved by using closed-cell type ribs with the new phosphor forming technology.