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Ships are complex structures composed of various components with exclusive dynamic behaviors and natural frequencies, so assessing their vibration behavior is essential. Some situations in practical applications could alter the ship's dynamic characteristics and cause significant changes in its vibration behavior. Since the ship's mass is one of the most important dynamic parameters in determining vibration behavior, local mass change can lead to changes in its dynamic characteristics and must be considered. This study aims to develop a method to predict the effect of the location and magnitude of mass change on the ship hull's vibration behavior. It would be feasible to enhance the dynamic behavior and reduce undesirable noises by locating the mass change on the ship hull. In this regard, experimental and numerical modal analysis is performed on a scaled model of a naval ship hull. The baseline FE model is used to calculate the variation in frequencies of the model caused by different local mass change scenarios. Using these measurements a fuzzy system is generated and optimized by Genetic and Particle Swarm Optimization algorithms. Finally, the efficiency of the fuzzy-PSO is validated by different mass change scenarios foreseen on the physical model of the ship hull. • Experimental and numerical study on the vibration behavior of naval ship hull in the case of local mass change. • Combine fuzzy logic and meta-heuristic algorithms to predict the location and magnitude of local mass change. • Validate the efficiency of the fuzzy meta-heuristic algorithms through experimental tests. • The proposed method is successful in identifying the location and magnitude of local mass change. [ABSTRACT FROM AUTHOR]

In present study, the sensitivity of WAVEWATCH-III model to different wind sources, formulations for wind input, whitecap dissipation and quadruplet wave-wave interaction was investigated during both fair weather and extreme condition of Hurricane Sandy in Lake Michigan. Wind data sets with finer spatial resolution (GLERL and GEM) led to better agreement with in-situ data, while ERA5 with coarser spatial resolution underestimated wind speed both in deep and shallow waters. Preparatory evaluation of model skill in reproducing wave bulk parameters indicated that the highest error was obtained when ST4 package and ERA5 wind data were employed in model. The calibration procedure was conducted by employing a combined error index. Simulated wave bulk parameters with optimum tuning values for GLERL and GEM wind data were in well agreement with in-situ data; however, GEM outperformed GLERL during extreme values of H s and T m in deep water buoys. Moreover, GLERL wind data slightly improved model skill in H s and T p estimation in shallow water buoys. Although more advanced methods were considered for quadruplet wave-wave interaction, DIA could be sufficiently reliable method for hindcasting wave bulk parameters. The DIA method systematically overestimated wave energy at low frequencies which was alleviated when GMD or GQM method was employed. Obtained directional wave spectra by using ST1 and ST6 packages combined with DIA were directionally broad as well as less energetic in peak frequency; however, GMD, GQM and WRT methods were led to more concentrated high energy content. In general, the quality and quantity of modeled wave spectra were in a reasonable agreement with observed one after model calibration. • ERA5 underestimates wind speed at buoys, while GLERL and GEM are in more agreement with in-situ data in Lake Michigan • High error indices for H s , T p and T m hindcast were obtained when ST4 package and ERA5 were applied in WWIII model. • ST6 was calibrated against observed H s and T m at deep water buoys during fair weather as well as extreme Hurricane Sandy. • GLERL outperformed GEM in H s simulation at shallow buoys; but GEM better estimated H s and T m at deep buoys. • DIA is a reliable method in wave bulk parameters prediction S n l [ABSTRACT FROM AUTHOR]

Face stability is a critical issue in the stability analysis of tunnels, especially in soft soils and crushed rock masses. In this paper, considering two three-dimensional collapse mechanisms, upper-bound solutions are presented for determining the face pressure of deep and shallow tunnels excavated in rock masses. The Hoek–Brown failure criterion was considered for the rock mass surrounding the tunnel. The proposed upper-bound formulations were compared with three-dimensional finite-element simulations and also with centrifuge test results available in the literature. The obtained results showed that the face pressure decreases with increasing σci, mi, and geological strength index. Besides, increasing the tunnel diameter and the rock mass density led to an increase in the face pressure, where for larger tunnels, the effect of the density became more pronounced. Finally, some charts were presented to specify the range of applicability of the concepts of deep and shallow tunnels. The results obtained from these charts demonstrated that the reduction in the Hoek–Brown parameters of the rock mass results in spreading the collapse mechanism from the tunnel face to the ground surface. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the diagnostic accuracy of split-bolus single-scan computed tomography angiography (CTA) protocol for evaluation of acute mesenteric ischemia and alternate diagnoses.Materials and Methods: In this IRB-approved, HIPAA-compliant retrospective study, consecutive patients from 21 October 2016 to 6 May 2018 evaluated for mesenteric ischemia with split-bolus CTA (a single scan in concurrent arterial and portal venous phase) in a single tertiary academic institution were included. Intravenous contrast was administered on weight-based basis. Quantitative and qualitative assessments of superior mesenteric artery (SMA) and superior mesenteric vein (SMV) attenuation and patency were performed by two independent reviewers. CT imaging findings were correlated with clinical reference outcomes.Results: One hundred fifty-four patients (age 66.3 ± 14.1 years, BMI 27.3 ± 6, 86 (56%) female) were included. CTA studies were performed with a volumetric CT dose index of 15.9 ± 5.5 mSv and dose length product of 1042.9 ± 389.4 mGy cm. Average intravenous contrast volume administered was 164.3 ± 12.1 cc. SMA attenuation was 263.6 ± 92.4HU, SMV was 190 ± 50.2HU. Qualitative assessment of SMA and SMV showed good opacification in all patients. 17/154 (11%) patients were diagnosed on CT with mesenteric ischemia; in 6/154 (4%), CTA studies were indeterminate; in 131/154 (85%), CTA confidently ruled out mesenteric ischemia. Alternate diagnoses were made in 38/154 (25%) patients. Using composite clinical outcomes as a reference standard, sensitivity of split-bolus CTA protocol for diagnosis of mesenteric ischemia is 100% (95% CI 79-100%), and specificity is 99% (95% CI 96-100%).Conclusions: Split-bolus CTA has high sensitivity and specificity for diagnosis of acute mesenteric ischemia.Key Points: • Split-bolus CTA protocol for mesenteric ischemia has great diagnostic accuracy with lower radiation exposure and fewer images to interpret compared with standard multiphasic CTA. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of the collar plate size and the joint geometry on the static behavior of the collar plate reinforced X-joints under tensile load at elevated temperatures. At the first step, a finite element model was developed and validated by results of the experimental tests. At the next step, extensive numerical simulations were carried out on the collar plate strengthened X-joints considering a wide range of geometrical parameter. Using these numerical simulations, the structural behavior under different high temperatures (200 °C, 400 °C, 600 °C, and 800 °C) was investigated and compared to the behavior at ambient temperature (20 °C). Results showed that the ratio of joint strength at elevated temperature to that at ambient temperature increases with the decrease in the ratio of chord diameter to twice the chord wall thickness (γ). Also, for the joints at elevated temperatures, the increase of the collar plate length and thickness remarkably leads to the increase of both the initial stiffness and the ultimate strength. Moreover, the use of the collar plate with big sizes can significantly improve the failure mechanisms of the joints. Also, it was found that for the collar plate reinforced X-joints under tensile load, the joint strength reduction at increasing temperatures follows closely the reduction in the elastic modulus of steel at elevated temperatures. Hence, in the proposed design method for determining the ultimate strength of the collar plate reinforced X-joints under tensile load at elevated temperatures, the Young's modulus reduction factor is used as a modification factor. • The effect of the joint geometry and collar plate size were investigated. • The initial stiffness, ultimate capacity, and failure mechanisms of the reinforced joints at high temperatures were investigated. • A new design method was proposed to determine the ultimate capacity of collar plate reinforced X-joints subjected to axially tensile load at elevated temperatures. [ABSTRACT FROM AUTHOR]

Offshore jacket platforms have been widely developed and their damage detection is of great importance to ensure their safe operation. Structural health monitoring method (SHM) has been used to decline the effect of the damages caused by marine environmental conditions. Global SHM methods are considered as efficient methods which include both economic and safety issues, and use modal characters of the structure. Major parts of offshore structures which are not available for diagnosing change the monitoring process to a big challenge. Different procedures have been used for diagnosing process, where simulating the structure as a finite element (FE) model is the most common one. Comparison between defected structures FE model and the intact model of the structure is the fundamental concept of SHM diagnostic. Mathematical models are used to develop limited measured data for health monitoring. An important step in SHM process includes FE model updating which is applicable using similar algorithms with diagnosing process. Some algorithms, such as neural network, have been used to detect the damage patterns, where their developing complication is their most important challenge. In this study, a new Fuzzy–Krill Herd algorithm is used to perform structural health monitoring process in a fixed jacket platform and compared with common fuzzy–genetic method. For this purpose, an experimental fixed platform model (SPD9 located in Persian Gulf) is prepared to obtain modal parameters using vibration behavior. Structural FE model is built and numerical model updating is performed on the results of the physical model. Moreover, the effects of uncertainty in damages and health monitoring in experimental and numerical models are considered for detecting damages and monitoring the structure. Using a combination of smart algorithms and fuzzy logic, a complicated and efficient system for structural health monitoring process is introduced. The suggested Fuzzy–Krill Herd method is shown to be applicable and appropriate in SHM process and also for handling noisy data. [ABSTRACT FROM AUTHOR]

Present research investigates the initial stiffness, ultimate strength, and failure modes of the X-joints reinforced with collar plates under axially tensile load. At the first stage, a finite element (FE) model was developed and verified against the test results obtained from an experimental study. After that, 136 FE models were created and analyzed. Results showed that the ultimate strength of an X-joint reinforced with collar plates can be up to 325% of the strength of the corresponding un-reinforced joint. Furthermore, the increase of the collar plate length leads to the remarkable increase of the initial stiffness and ultimate tensile strength. Also, in the same applied load, the deformation in the reinforced joints is significantly smaller than the deformation in the corresponding un-reinforced joint. In spite of remarkable difference between the static strength of the un-reinforced and the collar plate reinforced X-joints under tensile load, no study is available on this topic. In addition, no design equation is available to determine the ultimate strength of the reinforced X-joints subjected to tensile load. Therefore, after the parametric investigation, a new theoretical formula is proposed for the static design of the X-joints with collar plates subjected to axially tensile load. [ABSTRACT FROM AUTHOR]

Bullet embolization to the right heart through the vasculature is seen infrequently in cases presenting with penetrating trauma. Patients with unstable hemodynamic status are managed operatively. For a patient with stable hemodynamic parameters, diagnostic evaluation such as computed tomography angiogram, echocardiogram, or angiography could be performed to select the best treatment option. Endovascular treatment is employed infrequently in these cases but can be a viable option for select patients. We present a case of a bullet embolus to the right ventricle treated successfully with endovascular approach and discuss the technical aspects of this approach. [ABSTRACT FROM AUTHOR]

Lack of data of the jacket structures may result in a high uncertainty about the structures ability to endure harsh marine environmental conditions. An experimental measurement from structural behavior under harsh marine environmental conditions is necessary to reduce this uncertainty in practical structural monitoring process of jacket structures. As an alternative, a novel and robust simplified methodology based on the empirical investigation could be a practical approach of better understanding the structures integrity. Hence, these methodologies are often termed as model reduction schemes. In this article, model reduction schemes include simplified platform model and static reduction. This work introduces a structural integrity assessment strategy for jacket structures based on the finite element (FE) model updating and a novel simplified method. Hereof, model reducing and model updating procedure is established based on a novel optimization technique. Since the number of measured degrees of freedom is most of the time restricted in practice, this paper represents a methodology using the cross model cross mode (CMCM) method in combination with an iterative procedure which uses limited, spatially incomplete modal information. One of the important advantages associated with the proposed method is that measuring the rotational degrees of freedoms, which is most of the time very expensive and inaccurate, is not needed. This research is an empirical study on a laboratory model of a jacket structure with the aim of establishing Refined Simplified FE Model (i.e. RSM) to conduct damage detection. The studied jacket structure is a reduced scale 2D frame fabricated and tested at the Laboratory of Modal Analysis of the Tabriz University, Iran. Hereof, experimental vibration tests are accomplished on a physical 2D platform model to record dynamic responses and acquire dynamic features of damaged structure. In addition to eliminate the uncertainty effects in the damage detection results, RSM technique is employed because of practical considerations and also this technique provides a fast damage zone diagnosis procedure. Also, improved reduction scheme is utilized based on static reduction scheme to carry out damage detection in jacket structure. Improved reduction technique eliminates the bad influence of model reduction procedure on the proposed new methodology. The results demonstrate that the presented new technique is completely successful in conducing damage identification in jacket structures. [ABSTRACT FROM AUTHOR]

A new fault classification/diagnosis method based on artificial immune system (AIS) algorithms for the structural systems is proposed. In order to improve the accuracy of the proposed method, i.e., higher success rate, Gaussian and non-Gaussian noise generating models are applied to simulate environmental noise. The identification of noise model, known as training process, is based on the estimation of the noise model parameters by genetic algorithms (GA) utilizing real experimental features. The proposed fault classification/diagnosis algorithm is applied to the noise contaminated features. Then, the results are compared to that obtained without noise modeling. The performance of the proposed method is examined using three laboratory case studies in two healthy and damaged conditions. Finally three different types of noise models are studied and it is shown experimentally that the proposed algorithm with non-Gaussian noise modeling leads to more accurate clustering of memory cells as the major part of the fault classification procedure. [ABSTRACT FROM AUTHOR]

A non-destructive method is proposed in this study for damage detection of a composite panel using random decrement (RD) signature technique and artificial neural network (ANN) algorithm. For this purpose, a 10-layer rectangular composite panel is built and the experimental test is carried out employing contact and non-contact sensing equipment to capture the vibration characteristics of the system. The experimental scenarios are defined using both intact and damaged models in two pinned and fixed supporting condition. The free damping response of the structure is extracted by RD method and employed for training the ANN neurons. The proposed ANN-RDT method is compared with the multimode random decrement technique (MRDT) and analytical mode decomposition- random decrement technique (AMD-RDT) method in damage detection process considering two error indexes. It is shown that the present method performs better than the MRDT and AMD-RDT. According to the results, the proposed approach is shown to be effective for diagnosing the presence of damage in both specified supporting systems. The trained algorithm performed more successful in the scenarios with pinned conditions with a damage closer to the supports. As indicated, the efficiency of the method is highly sensitive to location of the damage and sensors along with the type of the support. The experimental non-contact data is also shown to be significantly beneficial to utilize a simpler linear equation and also to gain the system dynamic characteristics. [ABSTRACT FROM AUTHOR]

A developed tuned liquid multiple columns gas damper, introduced as a TLMCGD damper, is proposed in this study and its capability is assessed on an offshore jacket platform under regular and irregular waves and also earthquake incidence. The proposed damping system includes a combination of performance of both tuned liquid multiple columns damper (TLMCD) and tuned liquid column gas damper (TLCGD). The number of multiple columns and gas pressure are defined as of the main parameters of the damper and their performance are investigated through various values under earthquake. According to the results, a passive optimum TLMCGD system can decrease the structural response of the system up to 22, 60, and 55 percent under regular wave, irregular wave, and earthquake, respectively. The whole structural response of the system reduces as the number of columns and the value of gas pressure increases up to a certain amount. To investigate the effectiveness of gas pressure in performance of the damper, various gas pressure values are considered for different 4 to 10-column TLMCGD dampers. By increasing the value of the gas, the displacement RMS reduces significantly. The highest decrement occurs as 50 to 100 bar gas pressure is specified for the gas springs of the dampers. Still more investigation is required to evaluate other key parameter of the system within an experimental study which is left for future studies. [ABSTRACT FROM AUTHOR]

Abstract The discrepancy between the theoretical and experimental results is defined as one of the main reasons for updating the analytical models of the structures based on experimental data sets. Although various updating methods have been proposed in the literature, the capability of the approaches on controlled systems is yet to be investigated. In this paper, a numerical model updating method is proposed considering both parametric and structural uncertainties on a passive controlled complex structural system. The method is applied on a three-dimensional offshore jacket platform model including an attached Tuned Liquid Column Gas Damper (TLCGD) damping system. The effect of the damper parameters on updating the numerical model is investigated for the first time using a Laser Doppler Vibrometer (LDV) as a non-contact measuring system. The maximum decrement is occurred using a sine function which seems to be because of the sinusoidal nature of the experimental data. According to the results, the discrepancy between the numerical and experimental data can be decreased by 75 percent utilizing non-contact measurements and discrepancy functions. The results also indicate that by calibrating the gas pressure and the total liquid column length of the TLCGD damping system, as the most important parameters of the damper, the discrepancy is decreased almost 66 percent. The proposed method of updating the FE model for the controlled systems is beneficial for the old sophisticated controlled practical systems that increasing their life time span is essential. • The capability of a model updating approach is investigated on a controlled system. • The updating method is proposed considering both parametric and structural uncertainties. • The efficiency of the method is studied using a non-contact measuring system. • Based on the results the highest decrement is occurred as the most important parameters of the damper are taken into account in the tenth scenario. • Calibration of the gas pressure and the total liquid column length of the TLCGD have significant roles in updating the controlled system. [ABSTRACT FROM AUTHOR]

In this paper, a type of pile breakwater is studied in a configuration that can provide an effective shore protection structure. While, the rubble mound breakwaters are the most common type, but they suffer from a number of shortcomings including the interruption of water that may lead to deterioration of water quality and corresponding environmental problems. The breakwater of this study with rows of piles can be used against sea waves, as an alternative. Its hydraulic performance, including wave reflection and transmission, shear stresses, pressure measurements, drag and inertia coefficients are investigated. In the first step, the hydrodynamics around the mono-piles with square cross-sections are inspected. The parametric equations are developed to measure the optimal orientation of the piles. As evidenced in the literature, relatively limited works have been carried out on this kind of piles. Also, the performance of the considered pile breakwaters are evaluated. To do this, the numerical results are calibrated and validated by experimentation. It is observed that the group piles with the square cross-section in optimum conditions, could have a higher value of reflection almost between 7 even to almost 30 percent, than other considered conditions with mild and short waves. It can be related to the effect of the square piles edges on the separation process of the flow. • A pile breakwater studied in a configuration as an environmentally friendly structure. • The research is an experimental study on a laboratory model of a pile breakwater. • The optimal orientations were estimated for the mono-piles with the square cross-section. • The parametric equations were estimated to measure the wave reflection coefficients. • Nine-pile breakwater was considered to investigate the best performances. [ABSTRACT FROM AUTHOR]

To investigate the dynamic behavior of a complex system, an accurate updated finite element (FE) model is essentially required. Numerical model updating, which is performed based on valid experimental data, is imprecise without taking the related uncertainties into account. In this study, both structural and parametric uncertainties are considered within model updating of an offshore jacket platform through time history analysis for the first time. The experimental test is implemented employing a shake table and a scaled hydro-elastic model of the case study. For updating the FE model, a three-step updating procedure is implemented through eight distinct scenarios. In the first step, three unknown structural parameters are calibrated over ten distinct groups of elements in the FE model by using particle swarm optimization algorithm (PSO). In the second step, the damping matrix coefficients are also updated through the optimization process. In the third step, the model form error is considered utilizing four mathematical functions to decrease the parametric uncertainty and improve the FE model accuracy. Based on the results, by employing the proposed methodology, approximately 98 percent fitness is observed between the experimental and updated numerical model. According to the results, not only reducing both structural and parametric uncertainties is essential, but also calibrating the damping matrix for updating a numerical model and improving the FE model accuracy is of great importance. The developed methodology, which is applied to a sophisticated structural system, is strongly recommended for updating the systems that existence of an accurate updated numerical model is vital. • A developed model updating methodology considering both parametric and structural uncertainties is introduced. • The model form error term is employed as a discrepancy term through four different mathematical functions for the first time. • Based on the results, damping matrix calibration and discrepancy functions consideration have key roles in numerical model updating procedure. • The developed methodology is recommended to be applied for updating the structural systems that existence of an accurate updated numerical model is vital. [ABSTRACT FROM AUTHOR]

Numerous constructed jacket platforms in the Persian Gulf require continuous monitoring due to aging which poses a significant hazard to the environment. The main aim of this study is to sketch a health monitoring system to address the problem of limitations and shortcomings of sensor networks and also to solve the localization problem. In order to achieve this goal, experimental modal analysis (EMA) is performed on a physical model of an offshore jacket platform to develop a numerically updated finite element model. Both traditional and improved Cross-Model Cross-Mode (CMCM) iteration algorithms are employed for this purpose and different model order reduction methods are compared in terms of their effects on the structural dynamic behavior of the case-study (SPD8 jacket platform). A new formulation is also proposed for the first time to compare the results of damage scenarios using both iteration algorithms. The effectiveness of the methodology in practical cases is also assessed by considering various numbers of sensors. According to the results, the improved iteration technique eliminates the detrimental impacts of the model reduction procedure on the proposed methodology, and physical parameters such as length, type, and location of a member play significant roles in the success of a damage detection scenario. • A monitoring approach is studied to address the problem of limitations of sensor networks. • The frame of proposed method adjusted considering the concept of reduced eigenvalue problem. • The research is an experimental study on a laboratory model of a jacket platform. • The improved technique eliminates the detrimental impacts of the model reduction procedure. • The method is more successful in diagnosing the lack of the bracing members. [ABSTRACT FROM AUTHOR]

Nowadays, due to the global warming crisis caused by the emission of greenhouse gases, researchers prioritize renewable energy. Combining energy converters with structures can be a solution to reduce the high costs of renewable energy production. This paper investigated the hydrodynamic characteristics of a sloping floating breakwater (FB) that can operate as a wave energy converter. The sloping FB was designed with a reservoir between two floating parts to collect water. The structure harnesses the power of wave energy by directing overtopping water into a reservoir that is located at a higher level than the average water level. The potential energy generated by the overtopping water is then converted into electrical energy by directing the water from the reservoir back to the sea through a low-head turbine. This research investigated the performance of hybrid sloping FBs with various slope angles. The FBs with 40° and 60° slope angles were studied experimentally in both regular and irregular waves with different heights and periods. Also, the Flow-3D software was utilized to study FBs with other slope angles. The overall results highlight the model's potential for power generation and efficiency as a breakwater, providing valuable insights into its feasibility as a sustainable wave energy conversion solution. • An innovative sloping floating breakwater system designed as an overtopping wave energy converter. • The system consists of two sloping floating parts with a reservoir for collecting the wave overtopping. • The performance of the system with various slope angles is investigated experimentally and numerically. • The hydraulic power and efficiency of the system are investigated for various conditions. • The system showcases significant capabilities in both power generation and coastal protection. [ABSTRACT FROM AUTHOR]

Natural frequencies and critical velocities are the basic dynamic characteristics of fluid conveying pipes. Investigation of vibrations of fluid conveying pipes to control their dynamic behavior is one of the main topics of these structures. This paper presents a simplified approach to determine the natural frequencies and critical velocities of fluid conveying pipes with different typical boundary conditions under the mean internal pressure due to the fluid flow. The approach is suggested by reducing the order of mass, damping, and stiffness based on the concepts of the Galerkin method. The results of the method are validated by experimental results and compared with various numerical methods reported in the literature. The effects of mean internal pressure on the natural frequencies of fluid conveying pipes are assessed, and critical pressure values are calculated for the different mode shapes of the pipes. The method presents significantly better results in all the velocities in a range less than the critical flow velocity. Also, the natural frequencies of fluid conveying pipes in the presence and absence of mean internal pressure are calculated by the explicit formulas obtained by the simplified approach. The method has a lower computational cost than other more complex techniques, and its relative errors are less than 5%. [ABSTRACT FROM AUTHOR]

Structural control of a system can be achieved by employing different control methods. The effectiveness of a control technique straightly depends on the performance of the control device. Among control devices, the tuned liquid column gas damper (TLCGD) has shown high vibration control capabilities. In this study, a newly developed damping system as a tuned liquid column ball gas damper (TLCBGD) system is introduced. The developed system is a combined version of a tuned liquid column ball damper (TLCBD) and a TLCGD system. The new damper is utilized on an offshore jacket platform and its qualification is studied under both regular and irregular wave incidences. The efficiency of the TLCBGD system is investigated numerically by implementing ball-tube ratio and gas pressure parameters. The effects of the ball-tube ratios and the gas pressure values on the vibration suppression capacity of the system are assessed through a parametric study. In comparison to a passive TLCGD system, the results revealed that the utilizing a TLCBGD system in the jacket platform improves the structural vibration suppression capability. • A novel developed Tuned Liquid Column Ball Gas Damper (TLCBGD) damping system is introduced for the first time • The damping system is placed on a jacket platform numerically and the combined system is investigated under incidence of wave loads. • The efficiency of the TLCBGD system is investigated by implementing two important ball-tube ratio and gas pressure parameters. • Using a TLCBGD system in the jacket platform improves the structural vibration suppression capability. • Considering an appropriate value for both ball ratio and gas pressure values is of great importance. [ABSTRACT FROM AUTHOR]

In this paper, a novel version of orthonormal polynomial series expansion method is developed to analyze vibrations of bottom hull panels due to moving impacting fluid loads. The initial phase of slamming is considered in the presented mathematical model, wherein, an elastic linear Euler-Bernoulli beam of uniform thickness mimics the bottom panel structural behaviour. The framework developed, suppresses the Gibbs phenomenon, and captures the beam deflection, flexural moment, and shear force by direct integration. The proposed solution exhibits a higher convergence rate, compared to the conventional method, in terms of the number of involved shape functions. • A new method is developed to capture response of boat bottom panels under slamming. • Gibbs phenomenon in conventional OPSEM is highlighted. • The new method exhibits faster rate of convergence rather than the old one. • Convergence is examined for deflection, rotation, flexural moment, and shearing force. [ABSTRACT FROM AUTHOR]

Structural vibration is one of the main engineering concerns in recent decades especially in offshore structures due to the dynamic environment and accessibility. Among different methods, applying a device within the primary system for mitigating the vibration through system damping increment is one of the most promising methods. In this study, a combined novel Magneto-Rheological Tuned Liquid Column Gas Damper (MR-TLCGD) as a damping system is introduced for the first time in structural control field and the efficiency of the system is investigated on a three dimensional fixed offshore jacket platform under both wave and earthquake excitation. The performance of the system is studied through considering different values of yield stress and gas pressure as of the main parameters of MR fluid and gas damper. The results are compared to a previously studied Tuned Liquid Column Gas Damper (TLCGD) system. Based on the results, utilizing an MR-TLCGD system in an offshore structure can be defined as a proper choice for reducing structural vibration. It can be concluded that considering an appropriate value for yield stress and gas pressure, regardless of the results limitation for this case study, is of great importance in practical cases. • A combined novel Magneto-Rheological Tuned Liquid Column Gas Damper (MR-TLCGD) damping system is introduced for the first time. • The efficiency of the damping system, MR fluid's yield stress and gas pressure are investigated under wave and earthquake incidence. • Utilizing an MR-TLCGD in an offshore platform causes more reduction in structural vibration in comparison with TLCGD damping system. • Considering an appropriate value is of great importance for both yield stress and gas pressure values. [ABSTRACT FROM AUTHOR]

Structural health monitoring (SHM) is essential for ensuring the structural safety performance during the service life. The process is of paramount importance in the case of the floating wind turbine (FWT) due to the structural parts, subjected to the marine environmental risky conditions. In this paper a fuzzy-based damage detection method, using dynamic response of the FWT structure, is proposed. In the first step, the nonlinear motion equations of the FWT system are derived using the theorem of angular momentum and Newton's second law. Then the variation values of the mean amplitude of dynamic response and frequency characteristics of the structure due to stiffness changes of mooring lines (simulated damage) are considered as input features to the fuzzy system. Also the fuzzy system is trained based on calibrating of the membership functions by defining the damage classes properly. The proposed method is applied on two types of the FWT, Tension Leg Platform (TLP) and Spar. The simulation results show that the proposed method is able to identify the damage classes with acceptable success rate (SR). [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to examine how type 1 diabetic patients have altered levels of lipid peroxidation, antioxidant defense, NO and EGF in their plasma and saliva. We tested the differences in lipid peroxidation level, antioxidant power, and concentrations of epidermal growth factor (EGF) and nitric oxide (NO) in saliva and blood of type 1 diabetic subjects in comparison to healthy control subjects. Methods: Nineteen subjects with type 1 diabetes mellitus and 19 healthy age- and sex-matched control subjects were included in the study. Blood and saliva samples were obtained and analyzed for thiobarbituric reactive substances (TBARS) as a marker of lipid peroxidation, ferric reducing ability (total antioxidant power), EGF and NO levels. Results: TBARS levels did not show a significant difference between the two groups. Analysis of antioxidant power revealed that saliva and plasma of diabetic patients had more antioxidant power (p <0.01) than the healthy control population (107 ± 10.35 vs. 11.14 ± 4.66 and 192 ± 12.3 vs. 142 ± 15.2 mmol/L, respectively). Concentration of EGF was increased (p <0.01) in saliva whereas it was reduced (p <0.01) in plasma of diabetic patients in comparison to those of healthy subjects (2423 ± 322 vs. 1513 ± 341 and 125 ± 14 vs. 346 ± 60 pg/mL, respectively). NO level increased in both saliva and plasma of diabetic patients in comparison to those of healthy subjects (46.61 ± 7 vs. 72.89 ± 13 and 62.11 ± 4.6 vs. 76.25 ± 5 μmol/L, respectively). Blood HbA1c (%) of patients was significantly higher than that of controls (8.3 ± 0.32 vs. 5.4 ± 0.24, p <0.01). Conclusions: Existence of increased total antioxidant power in the presence of normal lipid peroxidation in plasma and saliva of type 1 diabetic patients indicates the existence of oxidative stress. Increased salivary EGF and NO levels in association with elevated TAOP is interesting and should be further studied. [Copyright &y& Elsevier]

Background: Osteoporosis is a major problem and is a hidden epidemic disease in the world. Early diagnosis by measurement of Bone Mineral Density (BMD) and treatment can prevent and reduce disease complications, especially fractures. As there is no comprehensive study in Iran, this study designed to assess BMD discrepancy in 20-69 yr Tehran population as well as prevalence of osteoporosis and osteopenia. Methods: 553 people (34% men, 66%women) from 50 Blocks in Tehran randomly selected. The assessment of BMD in spine and femur region performed through DXA method. All subjects clinically examined and their BMIs determined. Results: The average spinal BMD score in men were more than in women. The peak bone mass of spine bone both in men and women occurred during 20-29 yr and reduction began from the age of 40. At the age of 60 to 69, loose of bone density was 19.6% in lumbar spine and 18.5% in femur of women and also 7.9% in lumbar spine and 14.6% in femur of men. Prevalence of osteoporosis in this age group in lumbar spine and femur was 32.4% and 5.9% in women and 9.4% and 3.1% in men respectively. Conclusion: In all age groups, peak bone mass was lower than European or American population, whereas the rate of bone loss was as much as the some population and actually this process justifies the prevalence of osteoporosis and osteopenia in Tehran population. [ABSTRACT FROM AUTHOR]

The present study evaluated the numerical analysis of liquefaction and consequent high seepage flow velocity through a nonlinear flow law of porous media. To this end, finite element method, as well as a generalized Newmark scheme was applied to the spatial discretization of nonlinear governing equations and the time integration, respectively. In addition, a generalized plasticity theory was employed to simulate the elasto-plastic behavior of the soil under seismic loading, followed by validating the developed numerical model using physical experiments of centrifuge model test. Then, the Darcy and non-Darcy flow models were compared through the dynamic analysis of the failure of lower San Fernando dam under 1971 earthquake and the effect of non-Darcy flow on the evaluated liquefaction potential and dynamic response of dam was investigated accordingly. [ABSTRACT FROM AUTHOR]

Introduction 68Ga-DOTATATE is a radiolabeled peptide-based agonist that targets somatostatin receptors overexpressed in neuroendocrine tumors. Here, we present our results on validation of organic matrix 68Ge/68Ga generators (ITG GmbH) applied for radiosynthesis of the clinical doses of 68Ga-DOTATATE (GalioMedixTM). Methods The clinical grade of DOTATATE (25 μg ± 5 μg) compounded in 1 M NaOAc at pH = 5.5 was labeled manually with 514 ± 218 MBq (13.89 ± 5.9 mCi) of 68Ga eluate in 0.05 N HCl at 95 °C for 10 min. The radiochemical purity of the final dose was validated using radio-TLC. The quality control of clinical doses included tests of their osmolarity, endotoxin level, radionuclide identity, filter integrity, pH, sterility and 68Ge breakthrough. Results The final dose of 272 ± 126 MBq (7.35 ± 3.4 mCi) of 68Ga-DOTATATE was produced with a radiochemical yield (RCY) of 99% ± 1%. The total time required for completion of radiolabeling and quality control averaged approximately 35 min. This resulted in delivery of 50% ± 7% of 68Ga-DOTATATE at the time of calibration (not decay corrected). Conclusions 68Ga eluted from the generator was directly applied for labeling of DOTA-peptide with no additional pre-concentration or pre-purification of isotope. The low acidity of 68Ga eluate allows for facile synthesis of clinical doses with radiochemical and radionuclide purity higher than 98% and average activity of 272 ± 126 MBq (7.3 ± 3 mCi). There is no need for post-labeling C18 Sep-Pak purification of final doses of radiotracer. Advances in knowledge and implications for patient care. The clinical interest in validation of 68Galabeled agents has increased in the past years due to availability of generators from different vendors (Eckert-Ziegler, ITG, iThemba), favorable approach of U.S. FDA agency to initiate clinical trials, and collaboration of U.S. centers with leading EU clinical sites. The list of 68Ga-labeled tracers evaluated in clinical studies should growth because of the sensitivity of PET technique, the simplicity of the shakebake approach for the dose preparation and reliability of 68Ge/68Ga generators. Our studies have confirmed the reproducible elution profile, and high reliability of ITG GmbH generators required for routine doses preparation according to FDA recommendations. [ABSTRACT FROM AUTHOR]

Pendred syndrome, defined as the constellation of goiter, sensori-neural hearing loss, and positive perchlorate discharge test, is the most frequent cause of congenital deafness. Newly introduced diagnostic approaches to the disease are rather expensive and complicated, therefore we evaluated the value of MRI as the sole, or adjunctive diagnostic approach, and compared it with the traditional ones. Presuming the classic triad as the gold standard, we compared MRI findings in six such defined patients with six cases having goiter, hearing loss, and normal perchlorate discharge test. Our results indicated that MRI was 83.6% sensitive and 66.7% specific in patients fulfilling all three criteria (complete), while in the 'partial' group the sensitivity and specificity were 66.7% and 100% respectively. In conclusion, MRI, although impressive as an adjunctive diagnostic tool, may not replace the holistic approach, and the latter may be more convenient, cheaper, and still more accurate. However in 'partial' cases with equivocal findings, and in relatives of the patients, MRI may be a valuable diagnostic adjunct. [ABSTRACT FROM AUTHOR]

Objective: This study aimed at comparing the urinary protein levels in calcium stone formers with those of healthy individuals. Patients and Methods: From January 2002 until June 2004, 100 calcium stone formers (mean age 38.6 ± 10.3 years), who had at least two episodes of calcium stone formation, were compared with 100 healthy individuals (mean age 33.8 ± 9.7 years). Their 24-hour urinary protein levels, using SDS-PAGE, were measured. Results: The mean 24-hour urinary Tamm-Horsfall protein (THP) levels were 3.3 ± 0.8 mg in the case group and 4.6 ± 1.9 mg in the controls, and the difference was not statistically significant (p = 0.53). However, the THP levels in individuals with and without bacteriuria were significantly different (15.8 ± 3.3 mg vs. 2.6 ± 1.0 mg, p = 0.0001). The mean 24-hour urinary albumin concentrations were 163.31 ± 15.1 mg in the case group and 74.26 ± 4.6 mg in the controls. The mean 24-hour urinary transferrin levels were 8.09 ± 2.7 mg in the case group and 0.40 ± 0.3 mg in the controls. The differences were statistically significant for both albumin and transferrin (p < 0.0001 and p = 0.0063, respectively). There were no significant differences in any other mean urinary protein concentrations between cases and controls. Conclusions: The THP level in the urine of stone formers is not quantitatively different from that of healthy individuals, but it increases in association with bacteriuria. Albumin and transferrin may play a presumptive role in stone formation. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: The objective of this randomized, double-blind placebo-controlled clinical trial was to evaluate the value of allopurinol treatment on reduction of oxidative stress in patients with diabetes type II patients. Forty-one diabetic type II subjects were randomly assigned to two groups. One group (n = 20) received 100 mg allopurinol three times a day for 14 days and the other group (n = 21) received a placebo. Blood and saliva samples were collected before and after intervention for analysis of lipid peroxidation level and total antioxidant power as indices of oxidative stress. At the beginning of the study, the groups were similar based upon age, duration of diabetes, fasting glucose, and HbA1c. Both allopurinol and placebo were effective in reduction of lipid peroxidation and total antioxidant power whether in saliva or plasma in a similar extent. HbA1c and FBS levels did not change through the study neither in case or placebo group. It is concluded that allopurinol therapy is not more effective than placebo in reduction of oxidative stress in diabetic patients. The same trend of changes in blood and saliva shown for oxidative stress indices was interesting and suggests a chance for saliva to be valuable in diagnosis of oxidative stress. However, to elaborate the exact role of allopurinol in diabetes, further large randomized clinical trials are needed. [Copyright &y& Elsevier]

Structural integrity monitoring of jacket structures is an attractive challenge faced by researchers worldwide. Because of numerous uncertainties in marine environments, using statistical methods to reduce the detrimental impacts of uncertainties on model updating and damage detection results are unavoidable. In this study, a new Bayesian model updating framework is proposed using incomplete Frequency Response Function (FRF) data. In this methodology, the incomplete measurements issue is not dealt with the model reduction or data expansion method and the number of data in the objective function is increased using FRF at different excitation frequencies. The experimental verification of a scale 2D fixed platform is implemented to reveal the validity of the proposed methodology. Several numerical damage scenarios are simulated to investigate the effect of noisy data, FE model uncertainties, incomplete measurement, and added mass in the damage detection procedure. According to the results, the introduced method is entirely successful in the model updating and damage detection of the jacket platform. The results also indicate the lower effects of uncertainties and noise levels in damage detection outcomes. • A new model updating and damage detection Bayesian framework using the incomplete noisy data was proposed. • The model reduction or data expansion methods do not need to solve the incomplete measurement problems. • The Bayesian method was used for the damage identification of the marine structures for the first time. • The experimental verification of a scaled 2D fixed platform was operated to validate the proposed methodology. • The effects of noisy data, FE model uncertainties, incomplete measurement and added mass on the results were investigated. [ABSTRACT FROM AUTHOR]