Time-Variant Reliability Assessment of FPSO Hull Girder With Long Cracks

2005 ◽  
Author(s):  
Efre´n Ayala-Uraga ◽  
Torgeir Moan
Keyword(s):  
Fatigue Cracking ◽  
Stress Effect ◽  
Water Load ◽  
Stiffened Panels ◽  
Hull Girder ◽  
Fracture Failure ◽  
Hull Structure ◽  
Load Effects ◽  
The Mean

An efficient time-variant reliability formulation for the safety assessment of an aging Floating Production Storage and Offloading (FPSO) vessels with the presence of through-thickness cracks (i.e. long cracks), is presented in this paper. Often in ship structures, cracks are detected by means of close visual inspection when they have already propagated through the thickness. The propagation of long cracks in stiffened panels is therefore considered, as they may be present in critical details of the deck and/or bottom plating of the vessel. The mean stress effect due to the continuously varying still-water loading as well as residual stresses is explicitly accounted for in the crack growth calculation. An analytical model is established for determining the equivalent long-term stress range. Although it has been found that stiffened panels are tolerant to fatigue cracking, the probability of brittle fracture of an aging hull structure becomes more relevant with the presence of long cracks. The continuously varying still-water load effects due to the operational nature of FPSOs introduce additional uncertainties in the estimation of fatigue damage as well as in the likelihood of fracture failure mode. These uncertainties are accordingly considered in the analyses.

Time-Variant Reliability Assessment of FPSO Hull Girder With Long Cracks

2006 ◽  
Vol 129 (2) ◽  
pp. 81-89 ◽  
Author(s):  
Efrén Ayala-Uraga ◽  
Torgeir Moan
Keyword(s):  
Brittle Fracture ◽  
Fatigue Cracking ◽  
Stiffened Panel ◽  
Stress Effect ◽  
Mean Stress ◽  
Stiffened Panels ◽  
Hull Girder ◽  
Mean Stress Effect ◽  
Hull Structure ◽  
The Mean

An efficient time-variant reliability formulation for the safety assessment of an aging floating production storage and offloading (FPSO) vessels with the presence of through-thickness cracks (i.e., long cracks), is presented in this paper. Often in ship structures, cracks are detected by means of close visual inspection when they have already propagated through the thickness. The propagation of long cracks in stiffened panels is therefore considered, as they may be present in critical details of the deck and/or bottom plating of the vessel. Although it has been found that stiffened panels are tolerant to fatigue cracking, the safety of such structural components with the presence of long cracks may be threatened when exposed to overload extreme conditions, i.e., brittle or ductile fracture may occur. The probability of brittle fracture of an aging hull structure, i.e., a stiffened panel at the bottom plating with the presence of long cracks is studied in this paper. The mean stress effect due to the continuously varying still-water loading as well as residual stresses is explicitly accounted for in the crack growth calculation procedure presented herein. An analytical model is established for determining the equivalent long-term stress range including the mean stress effect. The continuously varying still-water load effects due to the operational nature of FPSOs introduce additional uncertainties in the estimation of fatigue damage as well as in the likelihood of fracture failure mode. In the present case study it is found that the time-invariant approach is a good approximation when dealing with the time-variant reliability problem. One of the main conclusions drawn from this study is that the still-water mean stress has a significant effect on the failure probabilities of stiffened panels with long cracks under brittle fracture mode.

Ultimate Limit State Assessment of the M.V. Derbyshire Hull Structure

2006 ◽  
Author(s):  
Jeom Kee Paik ◽  
Jung Kwan Seo ◽  
Jae Myung Lee ◽  
Jae Hyung Park
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Stiffened Panels ◽  
Hull Girder ◽  
North West ◽  
Water Ingress ◽  
The North ◽  
Formal Safety Assessment ◽  
Hull Structure ◽  
Ultimate Limit

The Capesize bulk carrier, M.V. Derbyshire, sank in the North West Pacific during typhoon Orchid in September 1980 when she was on a voyage from Canada to Japan carrying fine iron ore concentrates. Since then, extensive investigations of the vessel sinking have previously been made in the literature primarily by the formal safety assessment (FSA) technique to explore the loss causes, but serious speculation on the failure of hull structures has been lacking in such investigations. The present paper investigates the possibility of the vessel sinking initiated by the failure of hull structures rather than by other loss scenarios such as hatch cover failure subsequent to water ingress into the cargo holds. Ultimate limit state assessments of individual stiffened panels and hulls of the M.V. Derbyshire under extreme bending moments during the last voyage in storm are made using ALPS/ULSAP and ALPS/HULL computer programs. It is concluded that the M.V. Derbyshire could have sunk by hull girder collapse with or even without unintended water ingress into cargo holds. Important insights and findings developed from the present study are summarized.

Ultimate Limit State Assessment of the M.V. Derbyshire Hull Structure

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Jeom Kee Paik ◽  
Jung Kwan Seo ◽  
Bong Ju Kim
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Stiffened Panels ◽  
Hull Girder ◽  
North West ◽  
Water Ingress ◽  
The North ◽  
Formal Safety Assessment ◽  
Hull Structure ◽  
Ultimate Limit

The Capesize bulk carrier, M.V. Derbyshire, sank in the North West Pacific during typhoon Orchid in September 1980 when she was on a voyage from Canada to Japan carrying fine iron ore concentrates. Since then, extensive investigations of the vessel sinking have previously been made in the literature primarily by the formal safety assessment technique to explore the loss causes, but serious speculation on the failure of hull structures has been lacking in such investigations. The present paper investigates the possibility of the vessel sinking initiated by the failure of hull structures rather than by other loss scenarios, such as hatch cover failure subsequent to water ingress into the cargo holds. Ultimate limit state assessments of individual stiffened panels and hulls of the M.V. Derbyshire under extreme bending moments during the last voyage in storm are made using ALPS/ULSAP and ALPS/HULL computer programs. It is concluded that the M.V. Derbyshire could have sunk by hull girder collapse with or even without unintended water ingress into cargo holds. Important insights and findings developed from the present study are summarized.

Acute and Chronic Changes in Platelet Volume and Count After Cardiopulmonary Bypass Induced Thrombocytopenia in Man

1987 ◽  
Vol 57 (01) ◽  
pp. 55-58 ◽  
Author(s):  
J F Martin ◽  
T D Daniel ◽  
E A Trowbridge
Keyword(s):  
Platelet Count ◽  
Mean Platelet Volume ◽  
Artery Bypass ◽  
Bypass Graft ◽  
Control Group ◽  
Artery Bypass Graft ◽  
Platelet Volume ◽  
Young Males ◽  
The Mean

SummaryPatients undergoing surgery for coronary artery bypass graft or heart valve replacement had their platelet count and mean volume measured pre-operatively, immediately post-operatively and serially for up to 48 days after the surgical procedure. The mean pre-operative platelet count of 1.95 ± 0.11 × 1011/1 (n = 26) fell significantly to 1.35 ± 0.09 × 1011/1 immediately post-operatively (p <0.001) (n = 22), without a significant alteration in the mean platelet volume. The average platelet count rose to a maximum of 5.07 ± 0.66 × 1011/1 between days 14 and 17 after surgery while the average mean platelet volume fell from preparative and post-operative values of 7.25 ± 0.14 and 7.20 ± 0.14 fl respectively to a minimum of 6.16 ± 0.16 fl by day 20. Seven patients were followed for 32 days or longer after the operation. By this time they had achieved steady state thrombopoiesis and their average platelet count was 2.44 ± 0.33 × 1011/1, significantly higher than the pre-operative value (p <0.05), while their average mean platelet volume was 6.63 ± 0.21 fl, significantly lower than before surgery (p <0.001). The pre-operative values for the platelet volume and counts of these patients were significantly different from a control group of 32 young males, while the chronic post-operative values were not. These long term changes in platelet volume and count may reflect changes in the thrombopoietic control system secondary to the corrective surgery.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

Comparative Study of effectiveness of mobilization with movement (MWM) and End range mobilization (ERM) techniques in frozen shoulder

2018 ◽  
Vol 4 (4) ◽  
pp. 519-522
Author(s):  
Jeyakumar S ◽  
Jagatheesan Alagesan ◽  
T.S. Muthukumar
Keyword(s):  
Range Of Motion ◽  
Frozen Shoulder ◽  
Type I ◽  
Mean Values ◽  
Functional Activities ◽  
Group A ◽  
The Mean ◽  
Group B

Background: Frozen shoulder is disorder of the connective tissue that limits the normal Range of motion of the shoulder in diabetes, frozen shoulder is thought to be caused by changes to the collagen in the shoulder joint as a result of long term Hypoglycemia. Mobilization is a therapeutic movement of the joint. The goal is to restore normal joint motion and rhythm. The use of mobilization with movement for peripheral joints was developed by mulligan. This technique combines a sustained application of manual technique “gliding” force to the joint with concurrent physiologic motion of joint, either actively or passively. This study aims to find out the effects of mobilization with movement and end range mobilization in frozen shoulder in Type I diabetics. Materials and Methods: 30 subjects both male and female, suffering with shoulder pain and clinically diagnosed with frozen shoulder was recruited for the study and divided into two groups with 15 patients each based on convenient sampling method. Group A patients received mobilization with movement and Group B patients received end range mobilization for three weeks. The outcome measurements were SPADI, Functional hand to back scale, abduction range of motion using goniometer and VAS. Results: The mean values of all parameters showed significant differences in group A as compared to group B in terms of decreased pain, increased abduction range and other outcome measures. Conclusion: Based on the results it has been concluded that treating the type 1 diabetic patient with frozen shoulder, mobilization with movement exercise shows better results than end range mobilization in reducing pain and increase functional activities and mobility in frozen shoulder.

PITUITARY-ADRENAL RECOVERY FOLLOWING LONG-TERM CORTICOSTEROID THERAPY

1966 ◽  
Vol 51 (1) ◽  
pp. 63-70 ◽  
Author(s):  
P. F. Roe ◽  
D. M. Mitchell ◽  
G. W. Pennington
Keyword(s):  
Corticosteroid Therapy ◽  
Adrenocortical Function ◽  
Endocrine Disorders ◽  
Marked Rise ◽  
Underlying Condition ◽  
Normal Limits ◽  
Small Rise ◽  
The Mean ◽  
Corticosteroid Drugs

ABSTRACT Adrenocortical function was assessed in 20 patients receiving long-term corticosteroid drugs for a variety of non-endocrine disorders. In all cases plasma 17-hydroxycorticosteroids (17-OHCS) levels were within or above normal limits 48 hours after abruptly stopping their drugs and a further marked rise occurred in 7 patients given metyrapone for 24 h. Urinary 17-OHCS excretion did not show a parallel rise. Taking the group as a whole, a small rise in the mean output occurred 48 hours after stopping therapy, and a further slightly greater rise followed metyrapone. 3 patients had a relapse of their underlying condition during the test in spite of normal plasma and urinary 17-OHCS levels.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Long-term outcomes of lumbar microdiscectomy in the pediatric population: a large single-institution case series

2019 ◽  
Vol 24 (5) ◽  
pp. 549-557
Author(s):  
Malia McAvoy ◽  
Heather J. McCrea ◽  
Vamsidhar Chavakula ◽  
Hoon Choi ◽  
Wenya Linda Bi ◽  
...  
Keyword(s):  
Conservative Management ◽  
Functional Outcomes ◽  
Pediatric Patients ◽  
Clinical Presentation ◽  
Case Series ◽  
Csf Leak ◽  
Single Institution ◽  
The Mean

OBJECTIVEFew studies describe long-term functional outcomes of pediatric patients who have undergone lumbar microdiscectomy (LMD) because of the rarity of pediatric disc herniation and the short follow-up periods. The authors analyzed risk factors, clinical presentation, complications, and functional outcomes of a single-institution series of LMD patients over a 19-year period.METHODSA retrospective case series was conducted of pediatric LMD patients at a large pediatric academic hospital from 1998 to 2017. The authors examined premorbid risk factors, clinical presentation, physical examination findings, type and duration of conservative management, indications for surgical intervention, complications, and postoperative outcomes.RESULTSOver the 19-year study period, 199 patients underwent LMD at the authors’ institution. The mean age at presentation was 16.0 years (range 12–18 years), and 55.8% were female. Of these patients, 70.9% participated in competitive sports, and among those who did not play sports, 65.0% had a body mass index greater than 25 kg/m2. Prior to surgery, conservative management had failed in 98.0% of the patients. Only 3 patients (1.5%) presented with cauda equina syndrome requiring emergent microdiscectomy. Complications included 4 cases of postoperative CSF leak (2.0%), 1 case of a noted intraoperative CSF leak, and 3 cases of wound infection (1.5%). At the first postoperative follow-up appointment, minimal or no pain was reported by 93.3% of patients. The mean time to return to sports was 9.8 weeks. During a mean follow-up duration of 8.2 years, 72.9% of patients did not present again after routine postoperative appointments. The total risk of reoperation was a rate of 7.5% (3.5% of patients underwent reoperation for the same level; 4.5% underwent adjacent-level decompression, and one patient [0.5%] ultimately underwent a fusion).CONCLUSIONSMicrodiscectomy is a safe and effective treatment for long-term relief of pain and return to daily activities among pediatric patients with symptomatic lumbar disc disease in whom conservative management has failed.

Deep brain stimulation of the posterior limb of the internal capsule in the treatment of central poststroke neuropathic pain of the lower limb: case series with long-term follow-up and literature review

2020 ◽  
Vol 133 (3) ◽  
pp. 830-838 ◽  
Author(s):  
Andrea Franzini ◽  
Giuseppe Messina ◽  
Vincenzo Levi ◽  
Antonio D’Ammando ◽  
Roberto Cordella ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Lower Limb ◽  
Internal Capsule ◽  
Posterior Limb ◽  
Vas Score ◽  
The Mean ◽  
Deep Brain ◽  
Stimulation Of

OBJECTIVECentral poststroke neuropathic pain is a debilitating syndrome that is often resistant to medical therapies. Surgical measures include motor cortex stimulation and deep brain stimulation (DBS), which have been used to relieve pain. The aim of this study was to retrospectively assess the safety and long-term efficacy of DBS of the posterior limb of the internal capsule for relieving central poststroke neuropathic pain and associated spasticity affecting the lower limb.METHODSClinical and surgical data were retrospectively collected and analyzed in all patients who had undergone DBS of the posterior limb of the internal capsule to address central poststroke neuropathic pain refractory to conservative measures. In addition, long-term pain intensity and level of satisfaction gained from stimulation were assessed. Pain was evaluated using the visual analog scale (VAS). Information on gait improvement was obtained from medical records, neurological examination, and interview.RESULTSFour patients have undergone the procedure since 2001. No mortality or morbidity related to the surgery was recorded. In three patients, stimulation of the posterior limb of the internal capsule resulted in long-term pain relief; in a fourth patient, the procedure failed to produce any long-lasting positive effect. Two patients obtained a reduction in spasticity and improved motor capability. Before surgery, the mean VAS score was 9 (range 8–10). In the immediate postoperative period and within 1 week after the DBS system had been turned on, the mean VAS score was significantly lower at a mean of 3 (range 0–6). After a mean follow-up of 5.88 years, the mean VAS score was still reduced at 5.5 (range 3–8). The mean percentage of long-term pain reduction was 38.13%.CONCLUSIONSThis series suggests that stimulation of the posterior limb of the internal capsule is safe and effective in treating patients with chronic neuropathic pain affecting the lower limb. The procedure may be a more targeted treatment method than motor cortex stimulation or other neuromodulation techniques in the subset of patients whose pain and spasticity are referred to the lower limbs.

Sign in / Sign up

Export Citation Format

Share Document