International Journal of Coastal, Offshore and Environmental Engineering
Volume:6 Issue: 4, Autumn 2021

The focus of heuristics is on the content of decisions; however, the contexts are equally important; that is, where and how heuristics are used will often have a great influence on the outcome. Engineers need a lot of specialized skills, hard as well as soft, to successfully apply heuristics, i.e., to identify the heuristic that best fits the environment. Heuristics can help to lessen (not eliminate) the cognitive burden. This part of the four-part paper discusses how heuristics are created, improved, and refuted, and describes what judgment errors they might cause. In using heuristics, engineers must be aware of biases, which is examined in this part. The context of decision-making is also considered, and finally, the paper shows how heuristics should be used.In engineering, heuristics are experience-based methods used to reduce the need for calculations such as equipment size, performance, or operating conditions. Heuristics are fallible and do not guarantee an optimal solution. It is important to understand their limitations when applying them to a different context. Heuristics work well in a stable environment, but if the environment is complex and changing, heuristics may lose their relevance and require updating. Though the applicability of heuristics is conditional, they can be of value when used expertly

The growth and evolution of mangrove forests are affected by various factors such as pollution, light penetration, depth, water flow, and water quality. The effects of sea surface temperature and salinity on vegetation changes in the Khor-e-khoran protected area was been investigated in two distinct time periods (1986-1999 & 2001-2015) which were used as recorded data in the department of environment of Iran, as well as satellite imagery, drawing profiles and charts by standard models, ECMWF and Giovanni. The results clarified that Sea Surface Temperature and Salinity increased by about 0.2°C and 0.5 ppt respectively. On the other hand, the area of Khor-e-khoran protected area was decreased from about 6800 hectares in 2003 to 6350 hectares in 2015 which was more than 1.5%. Additionally, it is suggested sewages and wastewaters delivered from shrimp farming pools as well as fuel and crude oil leakage caused salinity and pollution anomalies.

One of the new sources of renewable energy, is salinity gradient power (SGP) being described as; the entropy energy of mixing the two solutions with different salt concentrations. The extraction of this energy is possible through SGP; the function of this system is based on membrane processes. A system of reverse electrodialysis (RED) was used in this study. Power density (W/m2) and energy efficiency of the system were evaluated due to the impact of nanotechnology on the use of membranes. The analyses showed that when the concentration of silica nanoparticles in the matrix membrane used in the system is 20 percent and when ion concentration in the solution is 0.055mol/lit, the selectivity of the membrane for ions will be Na+, 98.4 percent. However, the selectivity of matrix membrane without the presence of nanoparticles is 82 percent. Also compared to non-nanoscale membranes, the efficiency is increased about 11 percent due to the use of the particles on the anionic membrane as well as their appropriate structure design.

Displacement of coastlines under the influence of hydrodynamic factors and rising sea levels cause serious damage to economic, social and environmental infrastructure, and rapid fluctuations in the Caspian Sea water level since the twentieth century have created adverse conditions for the coastal environment. The main objective is to assess the severity of changes in the shores of Gorgan Bay and Miankaleh coast as protected environmental areas of wildlife sanctuaries and biosphere reserves during a period coinciding with the decrease of the Caspian Sea water level during the years 1995-2019. The morphological conditions of the coastlines of Gorgan Bay and Miankaleh coast were investigated by field observations and analysis of satellite images. A total of 10 study axes were selected around Gorgan Bay and Miankaleh and the intensity of shoreline movement by processing multi-time satellite images belonging to the years (1995-2019) in the GIS environment and with the help of digital software for coastal line analysis (DSAS), was calculated. Based on the shoreline movement, the study area was classified into three groups with shoreline changes (high, medium and low). The results show that the northeastern extremities of Miankaleh and the western extremity of Gorgan Bay have the highest coastline displacement and the central areas south of Gorgan Bay and the north-central part to the western part of Miankaleh coast have very little displacement. For comprehensive management of coastlines in the study area, focus on areas with high physical vulnerability is necessary and continuous control of quantitative and qualitative changes in coastal habitats affected by fluctuations in the water level of the Caspian Sea can reduce the existing challenges.

The purpose of risk management is managing the uncertainties by considering activities for identifying, assessing, monitoring, and reducing the impact of risks. Three strategies may be used to deal with the kind of risks that exist in projects: risk acceptance, risk transfer, and risk reduction. Events that can affect the economical goals of a project must be identified and evaluated so that they can be appropriately managed. Fixed jacket-type offshore platform (JTOP) as an expensive and necessary structure in energy facilities. in this research, the effect of knowledge increasing on the risk reduction and cost optimization for  JTOP is studying. This paper focuses on optimizing the pile length of the fixed jacket-type offshore platforms and reducing the conservative design by using the risk reduction approach. Fixed offshore platform in South Pars Gas Fields of Iran as a case study.Increasing the Geotechnical knowledge and reducing the pile lengths is performed as considering similar geotechnical study at this regions and pile dynamic driving test (PDA), updating the pile bearing capacity base on increased knowledge for geotechnical data, and finally assessing the result based on inplace analyzing Pile driving result shows increasing the longterm soil bearing capacity, So first of all the required strength and parameters extracted from the existing data with analyzing and comparing where to adjust and matches with the lower limit of the theoretical equations. Finally, this new assumption is used for optimizing the pile length design.  This research shows that that the numerical analysis and assumptions that have been used in the design procedure are conservative and a proper risk management program with the knowledge increasing could have resulted in risk reduction. The analysis process that has been used in the present research leads to the pile cost reduction by 11% that is considerable for stakeholders in such an expensive structure. The most important innovation in this paper is the use of the results of pile driving operation for optimal pile design because, in pile driving operation, piles with design diameter are used.

The present paper aims to study the lift forces acting on a cylinder oscillating in still water from spectral point of view. In the previous researches, vortex shedding frequency has been related to the fundamental lift frequency. Here, the wavelet analysis is used as a relatively new concept in spectral analyses. The simultaneous time-frequency representations of the lift forces are investigated to localize the flow induced transitory characteristics. The peaks in the wavelet coefficients attributed to vortex shedding are studied. The abrupt changes in the lift forces have also been studied by discrete wavelet decomposition. Small spikes have been observed in the results due to vortex shedding. Wavelet analysis is considered as an efficient alternative method to predict vortex shedding for larger Keulegan-Carpenter numbers (KC). Two different gap-to-diameter ratios, 0.1 and 1.0, are considered to account for the effect of bed proximity. Regular vortex shedding is suppressed for lower gap ratios; this fact is confirmed by wavelet analysis as well. The KC numbers in the present study are in the range of 15 to 40. The flow is in the subcritical regime with Reynolds number in the range of 9500-26000. The cylinder and the plane bed are both smooth.