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.

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.

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.

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.

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.

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.

Life Time Attributable Cancer Risk Estimated Using Scanner Reported Dose Length Product during Chest Computed Tomography Imaging in Young Children

This study aims to estimate the lifetime attributable cancer risk (LAR) for pediatric chest computed tomography (CT) examinations in five age groups using recently published age and region-specific conversion coefficients multiplying the widely available scanner registered dose length products (DLP) displayed on the CT console and hence calculating the Effective Dose (ED). The ED is then multiplied by the International Commission on Radiological Protection (ICRP) published risk factor for LAR. The obtained LAR values are compared with the international literature. Factors that may affect the LAR value are reported and discussed. The study included one hundred twenty five chest CT examinations for both males and females aged from less than one year to fifteen years. The patients reported data are from one single medical institution and using two CT scanners from June 2022 to December 2023. The results of this study may serve as benchmark for institutional radiation dose reference levels and risk estimation.

RIBLL束流诊断与鉴别

概述了ＲＩＢＬＬ的结构，束流诊断元件原理和作用。

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。

抗dsDNA抗体阴性的系统性红斑狼疮患者抗Sm抗体、抗Rib⁃P抗体水平及临床意义

目的探讨抗Sm抗体、抗Rib-P抗体对抗双链DNA(dsDNA)抗体阴性的系统性红斑狼疮的诊断价值。方法选择2020年8月—2021年8月收治的抗dsDNA抗体阴性的系统性红斑狼疮68例作为研究组,同期72例非系统性红斑狼疮的自身免疫性疾病患者作为对照组,同期体检健康者78例作为健康组。采用化学发光法检测3组抗Sm抗体、抗Rib-P抗体,随后采用受试者工作特征(ROC)曲线分析抗Sm抗体、抗Rib-P抗体对抗dsDNA抗体阴性的系统性红斑狼疮的诊断价值,以及研究组抗Sm抗体、抗Rib-P抗体与临床表现、实验室指标的关系。结果研究组抗Sm抗体、抗Rib-P抗体阳性率均高于对照组、健康组(P<0.05)。ROC曲线分析结果显示,抗Sm抗体联合抗Rib-P抗体诊断抗dsDNA抗体阴性的系统性红斑狼疮的曲线下面积及敏感度均高于单一指标诊断。研究组抗Sm抗体、抗Rib-P抗体阳性者蛋白尿发生率及C3阳性率明显高于抗Sm抗体、抗Rib-P抗体阴性者(P<0.05)。结论抗Sm抗体、抗Rib-P抗体对抗dsDNA抗体阴性的系统性红斑狼疮具有一定的诊断价值,且二者联合诊断价值更佳,有望作为诊断抗dsDNA抗体阴性的系统性红斑狼疮的有效指标。

A coal rib monitoring study in a room-and-pillar retreat mine

The National Institute for Occupational Safety and Health(NIOSH)conducted a comprehensive monitoring program in a room-and-pillar mine located in Southern Virginia.The deformation and the stress change in an instrumented pillar were monitored during the progress of pillar retreat mining at two sites of different geological conditions and depths of cover.The main objectives of the monitoring program were to better understand the stress transfer and load shedding on coal pillars and to quantify the rib deformation due to pillar retreat mining;and to examine the effect of rib geology and overburden depth on coal rib performance.The instrumentation at both sites included pull-out tests to measure the anchorage capacity of rib bolts,load cells mounted on rib bolts to monitor the induced loads in the bolts,borehole pressure cells(BPCs)installed at various depths in the study pillar to measure the change in vertical pressure within the pillar,and roof and rib extensometers installed to quantify the vertical displacement of the roof and the horizontal displacement of the rib that would occur during the retreat mining process.The outcome from the monitoring program provides insight into coal pillar rib support optimization at various depths and geological conditions.Also,this study contributes to the NIOSH rib support database in U.S coal mines and provides essential data for rib support design.

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.

Comparison and Selection of Arch-Rib Construction Schemes for Continuous Beam arch Composite Bridge of High Speed Railway

The paper summarizes the four different construction schemes based on engineering cases for the arch rib construction of continuous beam-arch composite bridges for high-speed railways.These methods include in-situ assembly,segmental lifting,incremental launching and longitudinal moving,and vertical rotation.The temporary structural designs,process methods,and technological equipment for each construction scheme are described in detail.The advantages and disadvantages of each scheme and its application scope under various conditions are analyzed,and opinions and suggestions for guiding the application of each scheme are proposed.The comparison and selection analyses show that the four arch rib construction schemes have certain applicability under different conditions such as bridge site status,bridge span,and construction environment.With the continuous increase of bridge span and progress of construction technological equipment,the arch rib construction technology is developing towards the overall erection direction.This leads to more obvious technical advantages of the segmental lifting method,incremental launching and longitudinal moving method,and vertical rotation method.Therefore,it is necessary to select the best construction scheme according to the construction status and technical conditions during application.

Rib stability: A way forward for safe coal extraction in India

Ensuring rib stability during pillar extraction is of prime importance in bord and pillar(B&P) method of underground coal mining with caving. Rib stability has been assessed here by way of assessing factor of safety(FOS), a ratio of the strength of rib to stress on it. Earlier formulations for rib stability when applied to case studies gave very low FOS value suggesting significant ground control problems, which were contrary to the field observations. This has necessitated the need to revisit the concept of rib stability. The stress coming on the rib is estimated with the use of numerical modeling technique using the FLAC^(3D) software. The methodology of assessing rib-stability with the help of suggested rib-strength formulation has been validated at eight Indian coal mines. The outcome of this study finds relevance and importance in ensuring underground coal liquidation with improved safety and conservation.

低盐固态工艺条件下米曲霉3.042和米曲霉RIB40酿造酱油发酵性能的比较

探讨了在低盐固态酱油酿造工艺下,我国广泛应用的米曲霉3.042和日本的米曲霉RIB40在发酵性能方面的差异。对比了两株米曲霉种曲孢子数、大曲制备工艺、发酵过程中理化指标、有机酸含量以及酱油风味物质方面的不同。研究发现米曲霉3.042具有产孢快、生长迅速的特点。通过跟踪测定蛋白酶活、纤维素酶活和糖化酶活,确定了两株米曲霉的最佳收曲时间均为36h。同时发现米曲霉RIB40的糖化酶活很高(3208.939U/g干基,36h)。理化指标的变化情况表明:采用两株米曲霉制曲酿造酱油均达到了特级酱油标准。在有机酸方面,米曲霉RIB40酱醅的乳酸和乙酸的含量具有一定优势,这有利于酱油良好口感的形成。风味物质的检测结果表明:米曲霉RIB40酿造酱油中醇类物质具有优势,而米曲霉3.042在酯类物质方面具有优势。在实际生产中,可以根据产品需要选择合适的菌株。

放射性核束(RIB)的物理前沿

介绍了世界上主要的放射性核束装置，并对当前放射性核束物理研究的前沿方向作了评述．同时，也展望了放射性核束装置的发展趋势．

RIB测井技术在昆北油田的应用

RIB测井技术有效包含了声幅密度测井的所有信息,如声幅、变密度等,能够识别窜槽和孔洞,能够准确反映第一界面水泥环全方位胶结情况。RIB测井技术不同于以往的其它水泥胶结评价方式,它能有效评价水泥胶结的周向固井质量,能测量井周八个扇区水泥胶结曲线、VDL变密度地层胶结波列、升幅衰减曲线。

RIB仪器配接爬行器在水平井中的应用

介绍了八扇区水泥胶结测井仪RIB(RADIUS INCREMENTED BOND)和SONDEX水平井爬行器的基本结构、功能及参数;介绍了RIB仪器配接爬行器进行水平井测井工艺过程;对在青海油田水平井测井的实际应用情况进行了分析。

Fabrication and Evaluation of Bragg Gratings on Optimally Designed Silicon-on-Insulator Rib Waveguides Using Electron-Beam Lithography

The fabrication of Bragg gratings on silicon-on-insulator （SOI） rib waveguides using electron-beam lithography is presented. The grating waveguide is optimally designed for actual photonic integration. Experimental and theoretical evaluations of the Bragg grating are demonstrated. By thinning the SOl device layer and deeply etching the Bragg grating, a large grating coupling coefficient of 30cm^-1 is obtained.