Longitudinal Stent Deformation in Undeployed Stents: A Case Series

Longitudinal stent deformation (LSD) is a recently reported problem with newer generation stents. The modification of stent materials and designs to make them more deliverable and conformable, as well as a focused approach in retaining their radial strength, has compromised longitudinal strength in currently available stents. Additionally, enhanced stent radiopacity, improved fluoroscopy, and heightened awareness have led to an increased incidence rate of the potentially under-recognized problem of LSD. Although originally described in deployed stents, LSD is being recognized in undeployed stents too. With available data to suggest an increased rate of adverse cardiac events like stent thrombosis and in-stent restenosis with LSD in deployed stents, an attempt to retrieve an undeployed deformed stent appears justified. We report 3 cases of LSD in undeployed stents and discuss its recognition. We also discuss the retrieval and visual inspection of retrieved stents and the simultaneous completion of coronary interventions via a double guide technique.

A NEW METHOD FOR ASSESSING THE SAFETY OF SHIPS DAMAGED BY GROUNDING

The primary aim of the present study is to propose an innovative method for assessing the safety of ships which have suffered accidental or in-service damages. Only a small number of probable scenarios for accidental or in-service damage representing all possible damage scenarios are selected using a sampling technique in which the random variables affecting the damage are probabilistically characterized. A damage index for the corresponding damage scenario is defined as a function of damage characteristics such as location and extent of the damage. The residual strength performance of a ship with the corresponding damage scenario can then be calculated by analytical or numerical methods. Once this process has been carried out for each of the damage scenarios selected, a diagram relating the residual strength performance to the damage index (abbreviated as the R-D diagram) can be established. This diagram will be very useful for a first-cut assessment of a ship’s safety immediately after it has suffered structural damage. The diagram can also be used to determine acceptance criteria for a ship’s safety against accidental or in-service damage. An applied example is shown to demonstrate the applicability of the proposed method in terms of developing a diagram between the ultimate longitudinal strength versus grounding damage index for four types of double-hull oil tankers – VLCC, Suezmax, Aframax, and Panamax.

An Advanced Salvage Method for Damaged Ship Structures

An advanced salvage method is proposed for damaged ships to ensure a short-term decision-making process for a safe ocean towage to the repair yard. The residual longitudinal strength must be greater than the sum of the still water and the maximum vertical wave bending moment. The ultimate bending moment is determined numerically for a container vessel by using an incremental iterative approach (Smith method) and wave-induced loads are predicted by means of hydrodynamic analyses. Successful applicability of the advanced salvage method is demonstrated for a damaged container vessel, which was towed from La Libertad, Ecuador, via Panama to the repair yard in Zhoushan, China, in restricted environmental conditions.

Collapse Strength of Intact Ship Structures

Ship structures are subjected to complex sea loading conditions, leading to a sophisticated structural design to withstand and avoid structural failure. Structural capacity assessment, particularly of the longitudinal strength, is crucial to ensure the safety of ships, crews, the marine environment, and the cargoes carried. This work aims to overview the ultimate strength assessment of intact ship structures in recent decades. Particular attention is paid to the ultimate strength of plates, stiffened panels, box girders, and entire ship hull structures. A discussion about numerical and experimental analyses is also provided. Finally, some conclusions and suggestions about potential future work are noted.

Comparison the Strength of Midship Structures With Margin Plate and Without Margin Plate

Margin plate is a part of bottom construction that joint the floor and frame construction of the ship, so the inner bottom plate will be installed cut off on the margin plate. Lately the bottom construction of the ship tends not to use the margin plate. The ship is currently built with an inner bottom plate continuously from the left side to the right side of the ship.This study aims to determine the transversal and longitudinal strength ratio of ships with and without margin plate. The analysis was carried out by using Finite Element Method so-called ANSYSTM. The result shows if the loadvariatied 0.2 x maximum load on the calculation of the transverse strength of the ship, the stress value on the ship model with a margin plate was 9.6242 (N/mm2) and on the ship model without margin plate was 8.4739 (N/mm2) under conditions 100%. The results of the comparison due to bottom load averaged 15.82%. The difference in stress due to the effect of deck loads was an average of 13.49% while the effect of side loads was on average 8.74%. The longitudinal strength of the ship was also a varied of every increase of 0.2 x maximum moment with a review point of meeting between bottom plate and bilga plate for the ship model without margin plates using the Multi Point Constraint (MPC) method looking for results in sagging conditions of 12,443 (N / mm2) and the hogging condition was -11.045 (N / mm2) at 100% x maximum moment load conditions. So that the ship model with a margin plate sagging condition was 23,189 (N / mm2) and hagging condition was -20,585 (N / mm2). The results showed the stress that occurred in the ship model without using margin plate was better to withstand the transverse and longitudinal strength of the ship compared to the ship model with the margin plate.

The Reliability Of Watertight Longitudinal Girders Of Fuel Tanks On Aging Bulk Carriers

During the exploitation of bulk carriers, the condition of structural elements and areas depends on the type of the cargo transported, operational conditions and maintenance systems. Corrosion significantly accelerates the aging of metal plates and girders thus causing the deterioration of steel surfaces, which consequently reduces the reliability of structural elements, areas and ships in general. The damage to metal structures can impair the stability of a ship, reduce longitudinal strength, cause the ingress of water into the hull as well as environmental pollution through fuel spills from the tanks. Therefore, the paper analyzes a part of a double bottom structure based on the available wear data on watertight longitudinal girders of fuel tanks. The research included 25 bulk carriers aged between 5 and 25 with the total of 110 fuel tanks. The reliability analysis of steel plates included the total of 1920 data measured. The allowable wear of structural plate thickness that equals 20% of the original thickness value was determined by the application of the acceptance criteria that were prescribed by classification societies. The calculations of the function of failure density, failure intensity and reliability determined the time when the condition of structural elements deteriorates due to corrosion up to the levels that require extensive maintenance services.

ANALYSIS OF PRINCIPLE DIMENSION AND SHAPE OF PURSE SEINERS IN AMBON ISLAND

Abstrak Purse seiners as a ship's main small pelagic fish Catcher is increasingly growing in number and size. In the last 5 years has been an increase in purse seine boats in Maluku by 20% and 15% of the overall operating in waters around the island of Ambon. Purse seiners tend to be made traditionally based on experience and not in accordance with the criteria of size comparison of a fish boat. It is very technical and operational feasibility of affect in this speed, stability and longitudinal strength . This research aims to calculate speed, tonnage (GT), the size of the principal as well as set the geometric shapes of purse seiners on the island of Ambon. The methods used in this research is a survey method by gathering primary and secondary data by making observations and measurements directly against the 32 purse seiners in Ambon island. Analysis and discussion is done through estimation the ship's speed by using the formula of Nomura, estimated tonnage (GT) using the Standard Fish Vessel Regulations by the Director-General of Fisheries Catch of Indonesia in 2004, the determination of the optimal size of the principal ship in the empirical formula by numerical – Traung and geometric forms of purse seiner . Estimation against speed (V) and the tonnage (GT) shows that the speed average (Vaverage) = 7.1 knots and tonnage average(GTaverage) = 22.4 tons. The calculation of the size of the principal ship by using empirical methods-numerical based on Traung equation with input of Vaverage and GTaverageindicates that the principal dimension is as follows: LBP = 15.8 meters; B = 4.8 meters; D = 2.2 meters and d = 1.9 meters and form coefficient as follows : CB = 0,6 ; CW = 0,7 ; CM = 0,97 ; CP = 0,62

Longitudinal Strength, Power, and Push-Start Performance Changes in a Skeleton Athlete: Case Study

Objectives: The purpose of this study was to document the longitudinal strength and power characteristic changes and race performance changes of a skeleton athlete. Method: Longitudinal strength and power changes were assessed with strength and power diagnostic testing over a 9-year period. Trends over 9 years for relative strength were analyzed using a linear model. Push-start time was recorded across multiple tracks. Trends over 9 years for start performance at each track were assessed using a mixed-effects linear model to account for the impact of different tracks. Lower-body strength and power changes were assessed via a 1-repetition-maximum squat and a body-weight countermovement jump. The relationship between strength and power changes was assessed over time. The relationship between strength changes and start performance was determined by assessing the fixed effect of relative strength changes on push-start time. Results: Relative lower-body strength ranged from 1.6 kg per body weight to 1.9 kg per body weight and showed a significant mean improvement of 0.05 kg per body weight per year (R2 = .71, P < .01). A negative correlation (R2 = .79) between relative strength changes and push-start performance across multiple tracks was found. The mixed-effects model indicated that push-start time improved significantly year to year (0.02 s; P < .001; R2 = .74) when controlling for the effect of track. Conclusions: The longitudinal analysis of push-start time and the associations with changes in strength suggest that training this quality can have a positive effect on push-start performance.