347 research outputs found
Setting up a numerical flume using a hybrid particle-mesh method
No full textA literature survey which concerns a variety of wave generation and absorption methods was accomplished. The survey deals with the methods used for the experiment wave tank and numerical wave tank. Their implementations are also described very briefly. The numerical wave tank (NWT) was set up using the hybrid particle-mesh method with the emphasis on the wave generation of solitary wave and linear progressive wave, and passive absorption at the far side of the wave tank. The Discontinuous Galerkin method was applied to solve the Navier-Stokes equations on the background mesh while the particles are used for solving the non-linear advection term. The waves are generated by using a piston-type wavemaker with the use of first-order linear wavemaker theory. For the absorption of reflected waves at the termination end, the sponge layer approach was implemented making use of viscous damping or internal friction among water particles. The hyperbolic tangent function is found to be applicable for smoothly increasing viscosity in the damping zone, which is also be able to prevent the formation of rigid body at the transition point. The drawbacks of the passive absorption technique are not only the extra cost of computational power and domain size, but also the rising slope of average water surface elevation induced by the accumulation of water particles near the end of the wave tank. The solitary waves of small amplitude could be simulated with reliable accuracy and also did the linear progressive waves in the intermediate water. The short waves and the long waves need to paid more attention for the wave generation boundary condition. Regarding the passive absorption for both of solitary waves and progressive waves, the same hyperbolic tangent function was used for viscosity functions which increases spatially. The solitary wave can be damped out using this function while the latter one cannot be damped, leading to the instability of the computation induced by the loss of the particles in the mesh system.Civil Engineering and GeosciencesHydraulic Engineerin
Investigation of the reliability deterioration of ageing marine structures
No full textIn the present work, an investigation of the fatigue life benefits emerging from
fillet weld geometries optimization has been carried out.
At first, an introduction to ageing mechanisms, corrosion and especially fatigue,
acting on operating marine structures has been made. Residual stresses at
weld toes, stress modes, and types, geometrical factors (weld angle, toe radius,
leg length), welding techniques selected, post-welding treatment and plate‟s
material are some of the principal factors affecting the fatigue life of a fillet weld
joint.
Especially, the accuracy of various approaches in fatigue life estimation of
specific geometries under pre-set types and levels of stress is studied. It is
evident so far that even the notch stress concept is the most accurate method
based on S-N curves, the Fracture Mechanics approach can offer more
accurate solutions of a crack development through the material. Towards this, a
literature review on crack evolution aspects in welded and non-welded plates
under bending and tension was performed; substantial parameters were
determined and finally implemented in the LEFM model which was used for the
simulation purposes of Chapter 6.
As far as the crack aspect ratio evolution is concerned, an extensive reference
is available in literature since many researchers have investigated its
contribution to the determination of geometrical paths, commonly known as
“Preferred Propagation Paths”. Their significance is related with our ability to
determine accurate SIF solutions leading to precise fatigue life estimations.
A typical fillet weld joint 2-D model has been developed in CAE Abaqus
software and a Finite Element Analysis of subject T-profile has been carried out.
Through this analysis, the fillet weld angle, the weld leg length, the weld toe
curvature radio ρ and the carrying load plate thickness are examined for their
impacts on the maximum surface stress. Finally, a number of stress mitigating
measures are proposed and their effects are analyzed.
Undoubtedly, the notch stress concept today is gradually gaining more and
more acceptance among other fatigue analysis practices, hence the need for an
estimation of the actual surface stresses along fillet weld toes, has become
imperative. Towards this, different 2-D geometries are tested against stress
concentration factors developed at weld toes, which are calculated on the basis
of maximum in-plane principal stresses over nominal stresses in mode I pure
bending and pure tension respectively. Moreover, validation with corresponding
results from literature is provided. Finally, three different concepts for reducing
the maximum surface stresses are presented. The first one proposes grinding
of the weld toe area and formulation of an artificial U-notch or a part- circular
profile. The second one applies to non-penetrating welds and assumes the
existence of a root gap of a specific geometry which is related to the fatigue life
and stress concentration factor of the fillet weld joint. Last but not least, the
relatively recent concept of the variable radius notch is discussed, even though
it is applicable mostly to notched bodies, not weld joints.
Afterwards, a Linear Elastic Fracture Mechanics analysis of reference 2D fillet
weld model is demonstrated. A number of geometrical parameters considered
at previous stage for their impact on surface Stress Concentration levels at the
weld toe region, have been correlated to fatigue life benefits in terms of
increased number of stress cycles till failure.
An extensive analysis of 9 different T-butt weld joint geometries has been
provided in order to investigate how positively a possible SCF reduction can
affect the fatigue life of a weld joint. Essential geometric variations (weld angle,
length, toe radius, root slot) were considered in the 2D model. All calculated
benefits both in pure bending and pure tension cases have been reported
accordingly.
Based on a linear interpolation of the points scatter (SCF, N-cycles) both in
banding and tension, it was observed that a surface stress mitigation of 1%
could lead to 1,33 up to 2,5% fatigue life benefit in the range of SCF=2 – 2,5. It
is evident so far that the geometrical optimization of a weld joint in respect of
notch stress mitigation can be a powerful tool both in shipbuilding and
maintenance practice in the future. However, technically wise their application
may incur high initial costs of improved tools of welding and post welding
treatment and robots even though it would consist a cost effective solution in a
medium/long term basis.
Finally, the above process is followed by a reliability analysis of the most critical
geometrical parameters affecting the fatigue life of a fillet weld joint. Reliability
assessment results concerning medium, high and low cycle fatigue are provided
and a comparative analysis of each factor‟s impact on fatigue life has been
carried out
Assessment of pile driving refusal using the standard test (SPT)
No full textThe design of driven pile foundations involves an iterative process requiring an initial estimate of the refusal level to determine the depth of boreholes for subsequent analyses.\ud
Current procedures for determining borehole depths incorporate parameters typically unknown at the investigation stage. Thus, a quantifiable procedure more applicable at this preliminary stage would provide greater confidence in estimating the founding level of driven piles. This paper examines the effectiveness of the Standard Penetration Test (SPT) in directly estimating\ud
driven pile refusal levels. A number of significant correlations were obtained between SPT information\ud
and pile penetration records demonstrating the potential application of the SPT. Results indicated pile penetration was generally best described as a function of both the pile toe and cumulative shaft SPT values. The influence of the toe SPT increased when piles penetrated rock. A refusal criteria was established from the results to guide both the estimation of borehole depths and likely pile lengths during the design stage.\u
Effectiveness of dry needling in patients with knee pain: a systematic review and meta-analysis
No full textAuthors: Mr. Johnson C.Y. Pang, Professor Amy S.N. Fu, Dr. Ryan K.L. Lee, Dr. Allan C.L. Fu
Corresponding author: Mr. Johnson C.Y. Pang and contact email: jpang@cihe,edu.hk
Abstract
Objectives
To assess the effectiveness of various approaches of dry needling (DN) for patients with knee pain and dysfunction
Search strategy
Six electronic databases: CINAHL Complete, Cochrane Library, EMBASE, Medline, PubMed, and PsycINFO were searched in November 2020 (registration number: CRD42021221419).
Screening
Risk of bias assessment and qualitative analysis were conducted by two independent reviewers using the PEDro scale.
Data management and reporting
Eight of 14 articles that met the inclusion criteria were high-quality manuscripts based on the PEDro scale. DN demonstrated positive short-term effects (from immediately after DN to <3 months) in pain reduction for both knee osteoarthritis (KOA) and patellofemoral pain syndrome (PFPS) (overall standardized mean difference [SMD]=-1.549, P=0.002). Subgroup analysis, however, revealed only significant improvement in PFPS (SMD=-3.435, P<0.001). At three months post-intervention, DN induced significant pain reduction in both KOA and PFPS (overall SMD=-0.916, P=0.022). Moreover, DN resulted in significant short-term improvement in function (overall SMD=6.069, P<0.001) in both KOA and PFPS. However, only PFPS showed a significant functional improvement in the subgroup analysis (SMD=6.089, P<0.001). At three months post-intervention, DN-induced functional improvement was significant in both groups (overall SMD=5.840, P<0.001), although only PFPS showed a significant improvement in the sub-group analysis (SMD=5.694, P=0.002). The outcomes of ultrasound (US)-guided DN on patients with knee pain are still unknown.
Conclusion
DN provides short-term benefits with respect to reducing pain and dysfunction for patients presenting with knee pain due to PFPS, but not KOA. Future research on US-guided DN for the treatment of knee pain is highly recommended
Effectiveness of dry needling in patients with knee pain: a systematic review and meta-analysis
No full textAuthors: Mr. Johnson C.Y. Pang, Professor Amy S.N. Fu, Dr. Ryan K.L. Lee, Dr. Allan C.L. Fu
Corresponding author: Mr. Johnson C.Y. Pang and contact email: jpang@cihe,edu.hk
Abstract
Objectives
To assess the effectiveness of various approaches of dry needling (DN) for patients with knee pain and dysfunction
Search strategy
Six electronic databases: CINAHL Complete, Cochrane Library, EMBASE, Medline, PubMed, and PsycINFO were searched in November 2020 (registration number: CRD42021221419).
Screening
Risk of bias assessment and qualitative analysis were conducted by two independent reviewers using the PEDro scale.
Data management and reporting
Eight of 14 articles that met the inclusion criteria were high-quality manuscripts based on the PEDro scale. DN demonstrated positive short-term effects (from immediately after DN to <3 months) in pain reduction for both knee osteoarthritis (KOA) and patellofemoral pain syndrome (PFPS) (overall standardized mean difference [SMD]=-1.549, P=0.002). Subgroup analysis, however, revealed only significant improvement in PFPS (SMD=-3.435, P<0.001). At three months post-intervention, DN induced significant pain reduction in both KOA and PFPS (overall SMD=-0.916, P=0.022). Moreover, DN resulted in significant short-term improvement in function (overall SMD=6.069, P<0.001) in both KOA and PFPS. However, only PFPS showed a significant functional improvement in the subgroup analysis (SMD=6.089, P<0.001). At three months post-intervention, DN-induced functional improvement was significant in both groups (overall SMD=5.840, P<0.001), although only PFPS showed a significant improvement in the sub-group analysis (SMD=5.694, P=0.002). The outcomes of ultrasound (US)-guided DN on patients with knee pain are still unknown.
Conclusion
DN provides short-term benefits with respect to reducing pain and dysfunction for patients presenting with knee pain due to PFPS, but not KOA. Future research on US-guided DN for the treatment of knee pain is highly recommended
Effectiveness of dry needling in patients with knee pain: a systematic review and meta-analysis
No full textAuthors: Mr. Johnson C.Y. Pang, Professor Amy S.N. Fu, Dr. Ryan K.L. Lee, Dr. Allan C.L. Fu
Corresponding author: Mr. Johnson C.Y. Pang and contact email: jpang@cihe,edu.hk
Abstract
Objectives
To assess the effectiveness of various approaches of dry needling (DN) for patients with knee pain and dysfunction
Search strategy
Six electronic databases: CINAHL Complete, Cochrane Library, EMBASE, Medline, PubMed, and PsycINFO were searched in November 2020 (registration number: CRD42021221419).
Screening
Risk of bias assessment and qualitative analysis were conducted by two independent reviewers using the PEDro scale.
Data management and reporting
Eight of 14 articles that met the inclusion criteria were high-quality manuscripts based on the PEDro scale. DN demonstrated positive short-term effects (from immediately after DN to <3 months) in pain reduction for both knee osteoarthritis (KOA) and patellofemoral pain syndrome (PFPS) (overall standardized mean difference [SMD]=-1.549, P=0.002). Subgroup analysis, however, revealed only significant improvement in PFPS (SMD=-3.435, P<0.001). At three months post-intervention, DN induced significant pain reduction in both KOA and PFPS (overall SMD=-0.916, P=0.022). Moreover, DN resulted in significant short-term improvement in function (overall SMD=6.069, P<0.001) in both KOA and PFPS. However, only PFPS showed a significant functional improvement in the subgroup analysis (SMD=6.089, P<0.001). At three months post-intervention, DN-induced functional improvement was significant in both groups (overall SMD=5.840, P<0.001), although only PFPS showed a significant improvement in the sub-group analysis (SMD=5.694, P=0.002). The outcomes of ultrasound (US)-guided DN on patients with knee pain are still unknown.
Conclusion
DN provides short-term benefits with respect to reducing pain and dysfunction for patients presenting with knee pain due to PFPS, but not KOA. Future research on US-guided DN for the treatment of knee pain is highly recommended
A Study on Ueda-akinari's Adapting Technique and Discriminatory Attitude Against Confucianism-Buddhism in Siramine
No full text日本志怪小說的傑作《雨月物語》，為江戶文?巨擎上田秋成以「翻案」(仿作)中日古典文學的手法寫成。本論文是以《雨月物語》的首篇作品〈白峰〉為探討對象。
〈白峰〉的內容是描述被迫遜位的悲劇天子崇德上黃化為厲鬼出現於原本武士後來出家的西行法師面前，為了將自己生前發動的叛亂事件正當化，針對儒家的禪讓‧篡位思想，和西行法師在黑夜的深山裏進行辯論的故事。根據兩人辯論的內容，學者之間傾向於將本篇視為日本「國學者」上田秋成的排儒黜佛論。
本論文首先比較〈白峰〉及其典據，繼之闡述作品主題，探討了一般所謂的秋成的排儒黜佛論，並提示不同的觀點。This dissertation is to discuss the first chapter of Ugetsu-monogatari, one of Ueda-akinari’s outstanding collections of eweird and mysterious stories in japan.
Ugetsu-monogatari consists of nine stories, and the first story is Siramine. It tells the tragic story of Sutokku- joko, an emperor forced to abdicate, whose malicious spirit argues with Saigyo-hosi about “usurping the thoughts of Confucianism, in order to legitimate the rebellion he arose when alive. According to the content of their debate, most scholars tend to regard this story as Ueda-akinari’s discriminatory attitude against Confucianism-Buddhism; the author will discuss this unfriendly criticism in this chapter.
In this dissertation , the author first compares Siramine with its originals, discusses its main points, the so-called discriminatory attitude against Confucianism-Buddhism, and gives hints of opposite viewpoints
Crossing between the Immortal World and the Mortal World in the Strange Stories from a Chinese Studio: Reflection on the Return of Liu Chen and Ruan Zhao and Investigation into Sentiments and the Dao
No full text《聊齋誌異》多篇揭現對仙境的營塑及探求，雜糅神話思維、宗教情操、故實承衍、倫理關懷、生命叩問及美學呈現，在在展呈蒲松齡對超拔凡俗、修行得道的壯闊想像及深切嚮往，也揭現蒲松齡對生命歸趨的多向探索，涵括情緣繫念、事親盡孝、宗嗣傳承、功名舉業及仙凡兩難的價值抉擇。本文析論《聊齋》所揭仙鄉∕人境流轉往復的動態進程，除了提挈六朝「劉、阮模式」的多樣演繹，更進而探究情緣、道念如何相持與相拒？如何超越世網纏縛，思辨功名的執守與捨離？乃至生命如何流通、重探自我？藉由仙凡兩端的迂迴辯證及仙凡異境的互融互攝，以彰明其周折婉曲之處所寄寓的人性底蘊及多重啟悟。Many tales in the Strange Stories from a Chinese Studio involve portraits and explorations of the immortal world, where myths, religions, legends, ethics, self-reflections and aesthetics are neatly interwoven. All these themes reveal the author Pu Song-Ling’s imagination, his craving for immortality and the Dao, and his multi-faceted inquiries of life, including love, filial piety, succession of heirs, pursuit of fame and honor, and the dilemma of choosing between immortality and mortality. The present paper is intended to analyze the incessant journeys between the immortal world and the mortal world in the Strange Stories. Employing the Liu-Ruan model of the Six Dynasties, the paper investigates how one deals with his/her sentiments and thoughts of the Dao, how he/she transcends the boundary of the mundane life and contemplates whether to grasp or abandon fame and honor, and how his/her life evolves and explores itself. Through the reciprocal relationship between the immortal world and the mortal world, the Strange Stories sheds light on human nature and realization
Characteristics and trends of orthopedic publications between 2000 and 2009
No full textBackground: This study was undertaken to investigate the trends of orthopedic publications during the last decade, and to document the country of origin, journal, funding source, and language of contribution using PubMed. Methods: Orthopedic articles published between 2000 and 2009 were retrieved from PubMed using the following search terms: orthopaedic[Affiliation] AND (2000/1/1[PDAT]: 2009/12/31[PDAT]) and orthopedic[Affiliation] AND (2000/1/1[PDAT]: 2009/12/31[PDAT]). The articles were downloaded in XML file format, which contained the following information: article title, author names, journal names, publication dates, article types, languages, authors' affiliations and funding sources. These information was extracted, sorted, and rearranged using the database's management software. We investigated the annual number of published orthopedic articles worldwide and the annual rate of increase. Furthermore, the country of publication origin, journal, funding source, and language of contribution were also investigated. Results: A total of 46,322 orthopedic articles were published and registered in PubMed in the last 10 years. The worldwide number of published orthopedic articles increased from 2,889 in 2000 to 6,909 in 2009, showing an annual increase of 384.6 articles, or an annualized compound rate of 10.2%. The United States ranked highest in the number of published orthopedic articles, followed by Japan, the United Kingdom, Germany, and the Republic of Korea. Among the orthopedic articles published worldwide during the last 10 years, 37.9% pertained studies performed in the United States. Fifty-seven point three percent (57.3%) of articles were published in journals established in the United States. Among the published orthopaedic articles, 4,747 articles (10.2%) disclosed financial support by research funds, of which 4,688 (98.8%) articles utilized research funds from the United States. Most articles were published in English (97.2%, 45,030 articles). Conclusions: The number of published orthopedic articles has been increasing over the last decade. The number of orthopedic articles, journals publication, and funding sources were dominated by research conducted in the United States, while share and growth of Asian countries including Japan, the Republic of Korea, and China were notable. © 2011 by The Korean Orthopaedic Association.Y
Applying adaptive design for the replacement of a weir in the Meuse River – a case study
No full textThe nature of the Meuse River is more than any other major river in the Netherlands formed by the presence of weirs. These were constructed almost one century ago to enable transport of coal; nowadays, the boundary conditions have changed and will continue to change in the future. The weirs reach the end of their lifetime around 2030; during their replacement, the uncertain future has to be considered. This paper presents an adaptive river design, which is able to adapt to the changing requirements. Special attention is given to the design of an adaptive weir in the Meuse River to replace the present weir at Belfeld. A new design methodology has been developed and applied. The methodology results shown in an adaptation scheme, give an overview of the required regional and weir adaptations. These adaptations are required to serve the scenario-dependent purposes in the future.Accepted Author ManuscriptHydraulic Structures and Flood Ris
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