همایش ملی صنایع دریایی ایران
سال:1385 | دوره:9 |تعداد مقالات:5

A STUDY IS PERFORMED ON THE ULTIMATE STRENGTH OF A TANKER. THE TANKER IS SUBJECTED TO DIFFERENT COMBINATIONS OF VERTICAL AND HORIZONTAL BENDING MOMENTS. DIFFERENT RATIOS OF THE HORIZONTAL BENDING MOMENT/VERTICAL BENDING MOMENT IN EITHER SAGGING OR HOGGING CONDITIONS ARE ASSUMED. MOMENT-CURVATURE RELATIONSHIPS OF THE SHIP ARE DERIVED APPLYING THE SMITH’S ALGORITHM.

HEALTH, SAFETY, ENVIRONMENT, AND QUALITY ASSURANCE (HSE-Q) IS VERY PIVOTAL IN ALL PHASES OF A PROJECT REGARDLESS OF THE PROJECT'S SIZE OR TYPE. HOWEVER, IT BECOMES EVEN MORE IMPORTANT IF A PROJECT IS EITHER STRATEGIC OR IT HAS SIGNIFICANT ECONOMIC DIMENSIONS. HSE-Q MANAGEMENT SYSTEM IS THE MANAGEMENT SYSTEM OF CHOICE IN ALL OF THE HUGE AND SUCCESSFUL FORTUNE 500 CORPORATIONS OF THE WORLD. IT BASICALLY GOVERNS EVERY SINGLE PROJECT OF THESE CORPORATIONS FROM THE POINT OF INCEPTION TO THE DECOMMISSIONING PHASE. IT IS IN THE FRAMEWORK OF THIS STRATEGIC MANAGEMENT SYSTEM WHICH THE SUSTAINABLE DEVELOPMENT OF A CORPORATION AND ITS LOSSES DUE TO UNDESIRED LIABILITIES CAN BE PLANNED, MANAGED AND CONTROLLED. THIS IS A VERY WIDE MULTIDISCIPLINARY TOOL OF INTERDISCIPLINARY SUBJECTS APPLICABLE TO A VERY WIDE FIELD OF ACTIVITIES. EACH SUBJECT WILL REQUIRE ITS OWN DETAILED STUDY AND ANALYSIS. THE FOCAL POINT OF THIS PAPER, HOWEVER DEALS WITH CONSTRUCTION PHASE IN LARGE CONSTRUCTION PROJECTS, MARINE AND OFFSHORE STRUCTURES OR DAM CONSTRUCTION ON RIVERS. THESE PROJECTS ABSORB HUGE AMOUNT OF INVESTMENTS AND HUMAN RESOURCES, AND ARE ALWAYS FACED WITH VARIOUS TYPES OF RISKS; WHICH LEAD TO LOSS OR DAMAGE. RISK ANALYSIS ASSISTS US TO EVALUATE THE NEEDS FOR SAFETY IMPROVEMENT, SELECTING AND PRIORITIZING REMEDIAL AND CORRECTIVE ACTIONS, AND IMPROVING THE CONSTRUCTION QUALITY PROCEDURE. THIS RESEARCH DEALS WITH IDENTIFICATION OF TRANSFERABLE RISKS TO INSURANCE COMPANIES WHILE THE CONSTRUCTION IS ONGOING. FOR THIS PURPOSE, THE MAJOR RISKS DURING THE CONSTRUCTION OF OFFSHORE STRUCTURES AND DAMS HAVE BEEN STUDIED FROM TWO DIFFERENT ASPECTS, ONE WITH REGARD TO THE TYPE OF STRUCTURE AND SECOND WITH REGARD TO DIFFERENT CONSTRUCTIONAL AND OPERATIONAL COMPONENTS OF THE STRUCTURE. THEN, THE CURRENT MAJOR RISKS HAVE BEEN REVIEWED APART FROM THEIR TYPES DURING THE CONSTRUCTION, WHICH HAVE BEEN REVIEWED. SINCE THE INSURANCE IS ONE OF THE RISK TRANSFERRING METHODS WHICH IS A RECOMMENDED RESPONSE TO IDENTIFIED RISKS, THE VARIOUS TYPES OF RISKS WHICH ARE TRANSFERABLE TO INSURANCE COMPANIES HAVE BEEN DISCUSSED. ALSO, SOME OF THE EXCLUSIONS IN THE INSURANCE COVERAGE HAVE BEEN INTRODUCED. FINALLY, BY COMPARING THE IDENTIFIED MAJOR RISKS DURING THE CONSTRUCTION AND CURRENT INSURANCE ENGINEERING PRACTICE IN THE WORLD, TRANSFERABLE RISKS WHICH COULD BE COVERED WITH INSURANCES ARE CATEGORIZED. AWARENESS OF INSURANCE DEFINITION METHODS, TERMS AND CONDITIONS ENABLES THE CONTRACTORS TO TRANSFER SOME RISKS TO INSURANCE COMPANIES AND STRENGTHEN THEMSELVES IN ACCEPTANCE AND MITIGATION OF RESIDUAL RISKS. INTRODUCTION OF INSURANCE COVERAGE OF RISKS WILL SATISFY HSE-MS REQUIREMENTS AND IN LINE WITH RISK PREMIUM REDUCTION WILL SATISFY MORE SAFETY CRITERIA FOR THE PROJECT.

UNDERWATER TRAVEL IS GREATLY LIMITED BY THE SPEED THAT CAN BE ATTAINED BY THE VEHICLES. USUALLY, THE MAXIMUM SPEED ACHIEVED BY UNDERWATER VEHICLES IS ABOUT 40 M/S. SUPERCAVITATION CAN BE VIEWED AS A PHENOMENON THAT WOULD HELP US TO BREAK THE SPEED BARRIER IN UNDERWATER VEHICLES. THE IDEA IS TO MAKE THE VEHICLE SURROUNDED BY WATER VAPOR WHILE IT IS TRAVELING UNDERWATER. THUS, THE VEHICLE ACTUALLY TRAVELS IN AIR AND HAS VERY SMALL SKIN FRICTION DRAG. THIS ALLOWS IT TO ATTAIN HIGH SPEEDS UNDERWATER. IT IS REALLY HARD TO CONTROL AND MANEUVER A SUPERCAVITATING VEHICLE. THE FIRST PART OF THIS PAPER DEALS WITH MODELING OF A SUPERCAVITATING TORPEDO. NONLINEAR EQUATIONS OF MOTION ARE PRESENTED IN DETAIL. THE LATTER PART OF THE WORK DEALS WITH FINDING A CONTROLLER TO MANEUVER THE TORPEDO. A CONTROLLER IS OBTAINED BY LQR SYNTHESIS. FOR THE SYNTHESIS, IT IS ASSUMED THAT THE CAVITY IS FIXED AND THE TORPEDO IS SITUATED SYMMETRICALLY IN THE CAVITY. THE ROBUSTNESS ANALYSIS OF THE LQR CONTROLLERS IS CARRIED OUT BY CALCULATING THE GAIN AND PHASE MARGINS. SIMULATIONS OF THE RESPONSE FOR A PERTURBED SYSTEM ALSO HAVE BEEN STUDIED.

OIL SPILL POLLUTIONS, A SEVERE ENVIRONMENTAL PROBLEM WHICH PERSISTS IN MARINE ENVIRONMENT OR INLAND WATER ACROSS THE WORLD HAS GROWN TO AN ALARMING MAGNITUDE INCREASED LEVELS OF OIL PRODUCTION AND TRANSPORTATION. CRUDE OIL RELEASED TO THE MARINE ENVIRONMENT THROUGH ACCIDENTAL SPILLAGE OR DRAINAGE FROM LAND CAUSES SERIOUS DAMAGE TO THE ENVIRONMENT AND MARINE LIFE TREATMENT OF OIL SPILLS REMAINS A CHALLENGE TO ENVIRONMENTAL SCIENTISTS AND TECHNOLOGIST. SORPTION IS A POPULAR TECHNIQUE APPLIED FOR TREATMENT OF OIL SPILLAGE. IN THIS WORK, THE PERFORMANCES OF THREE DIFFERENT SORBENTS, NAMELY, TIRE POWDERS, POLYPROPYLENE FIBERS AND TIRE COMPOSITES, ARE COMPARED IN TERMS OF OIL SORPTION CAPACITY AND OIL RECOVERY EFFICIENCY SCRAP TIRE COMPOSITES ACT AS SORBENT OF OIL SPILLS CONTAMINATION WITH REGARD TO THE IMPORTANCE OF RECYCLING WORN-OUT TIRES AND ENVIRONMENTAL PROBLEMS ACCOMPANYING THE WORN-OUT TIRES AND ALSO BECAUSE OF HYDROPHOBIC SURFACE PROPERTY OF RUBBER SORBENTS, THEY COULD BE REGARDED AMONG THE CHEAP AND ACCESSIBLE SORBENTS FOR ELIMINATING OF OIL SPILLS CONTAMINATION IN MARINE ENVIRONMENT. OIL SPILLS ON THE SEA SURFACE AND FREE WATERS INCUR MANY DAMAGES TO THE ENVIRONMENT. EACH YEAR MORE THAN 500 OIL SPILLS CAUSE ENTRANCE OF EQUIVALENT TO 2.5 MILLION TONS OF OIL INTO FREE WATERS. WHEREAS IRAN HAS GOT THE LENGTHIEST BANK AMONG PERSIAN GULF STATES, THEREFORE, OIL POLLUTION HAS ALWAYS IMPOSED MANY PROBLEMS FOR PERSIAN GULF RELATED MARINE ECONOMY.

IN THIS PAPER, BASED ON FEM SIMULATION, THE ULTIMATE STRENGTH OF DAMAGED CONTINUOUS PLATE IS STUDIED CONSIDERING THE COMBINED EFFECT OF INITIAL DEFLECTIONS AND RESIDUAL STRESSES. FIRSTLY, DAMAGE IS SIMULATED RESULTING TO RESIDUAL DEFLECTION IN SOME PRESCRIBED SHAPE AND MAGNITUDE ACCOMPANIED BY RESIDUAL STRESSES. THEN COMPRESSIVE LOADING IS APPLIED AND THE EFFECT OF SIMULTANEOUS PRESENCE OF BOTH RESIDUAL DEFLECTIONS AND RESIDUAL STRESSES ON THE PLATE ULTIMATE STRENGTH IS STUDIED. IT WAS FOUND THAT:1) THE COMPRESSIVE STRENGTH MAY BE SIGNIFICANTLY OVERESTIMATED WHEN THE DAMAGE RELATED RESIDUAL STRESSES ARE NOT CONSIDERED,2) A LARGER MAGNITUDE OF INITIAL DISHING DOES NOT NECESSARY RESULT TO A LOWER ULTIMATE STRENGTH.