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简介：Thephysicalmechanismforgenerationofstreamwisevortices(orribvortices)inthecylinderwakeisnumericallyinvestigatedwithafinite-differencescheme.Rayleigh’stheoryofcentrifugalinstabilityforinviscidaxisymmetricflowisextendedtoanalyzethe2-Dprimaryflows.Accordingly,ananalyticaldimensionlessgroupRay=-(r/vθ)■vθ/■r-1isderived,wherevθrepresentsthevelocityofafluidelementrelativetotheoncomingflow,risthelocalcurvatureradiusoftheelementpathline.CentrifugalinstabilityoccurswhenRay>0.StabilityanalysesarecarriedoutwiththisdiscriminantforprimaryflowsatdifferenttimelevelsinahalfsheddingperiodofthevonKarman(orvK)vortices.UnstableareasareidentifiedandthelocationsofribvorticesarecoincidentwellwiththeunstableareaswithinthefirstwavelengthofvKvorticesbehindthecylinder.Thenumericalresultsalsoshowthatribvorticesexperienceamplificationinthisregion.Itisapparentthatcentrifugalinstabilityplaysanimportantroleinthegenerationofribvorticesinthecylinderwake.

简介：Amethodologyisimplementedtofindtheoptimumreducedweightconfigurationdesignofanoperatingstructureofacivilaircraftverticaltailfin.FE(finiteelement)basedtopologyoptimizationisexecutedtofindtheoptimummaterialdistributionofinitialdesignspaceofribbymaximizingthestiffness.Loadspertinenttotheoperatingandgroundconditionsareestimatedandapplied,consideringtheorientationofstructuralassemblymembersandbuilt-insupportsofferedinthemainstructure.Manufacturingconstraintsareincorporatedintotheoptimizationlooptogeneratepragmaticandmanufacturabledesignconfiguration.ThetopologicallyoptimizedconfigurationisthenconvertedtoCADviabledesignthroughdatareductionandsmoothingbyconvertingtoISO-surfaces.Amethodologyisalsodevisedtomodifythetopologicaloptimizedvoidsandmateriallayoutpreciselywithsplinesandfilletstoconstructmanufacturablefeaturesandavoidstressconcentrations.Theresultingnoveldesignproposalisthenanalyzedandvalidatedagainststipulatedloads,constraintsandotherdesignneeds.Resultsvalidatethenewdesignproposalasmorereliable,havingreducedweightandenhancedstructuralperformance.

简介：聚合Mach-Zehnder肋骨波导的系统的分析基于计算和优化被介绍。模拟与有效索引方法(EIM)被执行并且二维(2-D)有限差别横梁繁殖方法(FD-BPM)。在连续聚合物层之间的大折射索引步被使用EIM减少，因此，计算的精确被保证。象Y连接角度和分离差距那样的波导的重要参数被讨论，他们与光力量繁殖和损失特征的关系在这篇论文被调查。优化结构的全部的损失是0.258dB。CLC数字TN252这个工程被基础为武器设备的进展研究节目支持，中国(资助No.02040105DZ02)。

简介：AbstractPurpose:Rib fractures are one of the most common causes of morbidity and mortality and are associated with abdominal solid organ injury (ASOI). The purpose of this study was to investigate the correlation of ASOI with the number, location, and involved segments of rib fracture(s) in blunt chest trauma.Methods:This retrospective cohort study was conducted on patients with blunt chest trauma over the age of 15 years, who were hospitalized with the diagnosis of rib fractures from July 2015 to September 2020. After ethic committee approval, a retrospective chart review was designed and patients with a diagnosis of rib fractures were selected. Patients who had chest and abdominopelvic CT scan were included in the study and additional data including age, gender, injury severity score, trauma mechanism, number and sides of the fractured ribs (left/right/bilateral), rib fracture segments (upper, middle, lower zone) and results of chest and abdominal spiral CT scan were recorded. The correlation between ASOI and the sides, segments and number of rib fracture(s) was assessed by Pearson's correlation coefficient.Results:Altogether 1056 patients with rib fracture(s) were included. The mean age was (42.76 ± 13.35) years and 85.4% were male. The most common mechanism of trauma was car accident (34.6%). Most fractures occurred in the middle rib zone (60.44%) and the most commonly involved ribs were the 6th and 7th ones (15.7% and 16.4%, respectively). Concurrent abdominal injuries were observed in 103 patients (34.91%) and were significantly associated with middle zone rib fractures.Conclusion:There is a significant relationship between middle zone rib fractures and ASOI. Intra-abdominal injuries are not restricted to fractures of the lower ribs and thus should always be kept in mind during management of blunt trauma patients with rib fractures.

简介：AbstractRib fracture is the most common injury in chest trauma. Most of patients with rib fractures were treated conservatively, but up to 50% of patients, especially those with combined injury such as flail chest, presented chronic pain or chest wall deformities, and more than 30% had long-term disabilities, unable to retain a full-time job. In the past two decades, surgery for rib fractures has achieving good outcomes. However, in clinic, there are still some problems including inconsistency in surgical indications and quality control in medical services. Before the year of 2018, there were 3 guidelines on the management of regional traumatic rib fractures were published at home and abroad, focusing on the guidance of the overall treatment decisions and plans; another clinical guideline about the surgical treatment of rib fractures lacks recent related progress in surgical treatment of rib fractures. The Chinese Society of Traumatology, Chinese Medical Association, and the Chinese College of Trauma Surgeons, Chinese Medical Doctor Association organized experts from cardiothoracic surgery, trauma surgery, acute care surgery, orthopedics and other disciplines to participate together, following the principle of evidence-based medicine and in line with the scientific nature and practicality, formulated the Chinese consensus for surgical treatment of traumatic rib fractures (STTRF 2021). This expert consensus put forward some clear, applicable, and graded recommendations from seven aspects: preoperative imaging evaluation, surgical indications, timing of surgery, surgical methods, rib fracture sites for surgical fixation, internal fixation method and material selection, treatment of combined injuries in rib fractures, in order to provide guidance and reference for surgical treatment of traumatic rib fractures.

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简介：Spatio-temporalcharacteristicsofthewall-boundedturbulentmixinglayerflowoveranopenstepandasquare-edgedribwereextensivelystudiedinalow-speedwindtunnel.Simultaneousmeasurementsofwall-pressurefluctuationsandvelocitymeasurementswereperformedbyusingmicrophonearrayandX-wire/splitfim,respectively.