Numerical Study of Oxidation in Stainless Steel Alloy Ep-823 by Liquid Lead-Bismuth Eutectic

The oxidation of stainless steel is influenced by the presence of oxygen in the surrounding medium; the oxygen reacts with the alloy to form an oxide. In certain environments, such as nuclear reactor coolant systems, minimal oxidation of the stainless steel containment functions as a protective shield from corrosive coolants such as liquid lead-bismuth eutectic. In the current study, this minimal oxidation is evaluated for a system in which corrosion-resistant stainless steel alloy EP-823 is subject to an environment of flowing oxygenated liquid lead-bismuth eutectic at a temperature of 743 K, whereby the thickness of the forming oxide layer is attributed to diffusion of oxygen within a plane comprised of the alloy. Fick’s second law of diffusion and the advection-diffusion equation in one spatial dimension are utilized as the mathematical model. The diffusion problem attributed to the oxidation of metal alloys introduces complications in the domain due to: the change in density as the oxide is formed, the discontinuity in diffusion coefficients between the oxide and metal phases, and the occurrence of two moving boundaries – one separating the oxide and metal phase and the other, the interior unexposed boundary. These complications are resolved by transformations of: the space coordinate of the interface boundary, the calculating space coordinate, and the space coordinate of interior moving boundary. Hereby, the domain of the mathematical model is fixed. The discontinuity of the diffusion coefficients at the phase boundary is resolved by a final transformation. The implicit numerical scheme applied to the mathematical model is described. This method, termed the ‘enthalpy method’, is typically used for moving boundary phase change problems. The implemented Newton-Raphson iterative technique for this finite difference method and the solution by a tri-diagonal matrix algorithm are also described. Input parameters for the numerical simulation are derived both from physical assumptions and from controlled experiments of the oxidation of EP-823 alloy, which had been previously determined an optimal corrosion-resistant steel [1]. Such parameters include the concentration of oxygen at interface, which is determined by considering the solubility of oxygen in EP-823 alloy. The effective oxidation of the alloy is studied by assessing the oxidation of the alloys component metals. The plausible oxidation reactions and resulting oxides are compiled based on partial pressure of oxygen in lead-bismuth eutectic, temperature, and free energy of formation of the relevant oxides. Hereby, input parameters such as mass fraction of the metal in its component oxide and density of the metal were obtained. The experimentally determined scale removal rate was also used as an input. The diffusivity of oxygen in the oxide and metal phases was estimated based on the physical assumptions of higher porosity in the oxide phase. The numerical results, which are in the form of the oxygen concentration profiles as a function distance from the calculating space coordinate at varying time intervals, contain the the calculated corresponding oxide layer thicknesses. The results are fit to a parabolic growth rate law, whereby the the growth rate, kp, of each relevant oxide is determined. The growth of copper (I) oxide, aluminum (III) oxide, niobium (II) oxide, and tungsten (IV) oxide demonstrate good adherence to the parabolic rate law. The numerical kp values are benchmarked with the experimental effective kp value for EP-823. It is determined that the experimental kp value is closest to the numerically determined kp values of aluminum (III) oxide and niobium (II) oxide. From the kp values, the steady state thickness of each oxide, δs, is derived by the Tedmon model for oxidation-ablation. These values are benchmarked with the semi-empirically determined steady state thickness from the mentioned controlled experiments, which is 35.8 µm, and which is found to be closest to the numerically determined δs value for niobium (II) oxide, at 20.1 µm. In order to ascertain the numerically determined kp and δs values, further work in assessing and optimizing stability and convergence criteria must be done. The Pilling-Bedworth ratio for the alloying metal oxides is also calculated. The ratios suggest that aluminum (III) oxide and niobium (II) oxide, for which the respective ratios are 1.27 and 1.37, are the most stable relative to the oxides of the other alloying metals. Furthermore, by considering selective oxidation of alloying metals, co-precipitation, oxidation states of the metals, crystal structure, and ionic radii, the likelihood of the participation of certain alloying elements in the effective oxide layer can be gauged. Thus, it is determined that the one-dimensional planar oxidation model can be effective as a preliminary tool in assessing the oxidation of the alloy in terms of participation of its component metals. Hereby, the objectives of the study are met

A suggested plan for development of marine fisheries sector of Andhra Pradesh

A suggested plan for the development of marine fisheries sector of Andhra Pradesh Is presented here. The condition of the state fisheries shows stagnation of overall productivity of the waters. Andhra Pradesh contributed on an average 1.47 lakh tonnes, forming around 9% of the total fish catches of India (in 1984). The following are major areas to be considered for proper planning and development. Several of the stocks are being fished In a narrow coastal belt and there is thus concern on the depletion of these resources; secondly, there Is the threat of Increasing Incursion of foreign fishing vessels; thirdly, the increasingly fast degradation of coastal waters by multiple users on the one hand and multiplication of traditional users on the other; lastly, the potential of aquaculture is yet to be fully assessed. The plan hence recommends four major but broad thrusts for the overall development which Includes management and conservation of marine fisheries; prevention of pollution and degradation of wetlands as pertaining to fish habitats: strengthening the commercial fishing Industry, particularly of the 200 miles EEZ; and aquaculture as an additional technology

Survey on Social Networking Site for Engineering Management Program

Social Networking Sites (SNSs) such as Facebook, LinkedIn and Twitter have gained much popularity as Web 2.0 technologies and have been widely adopted by different age groups from teenagers to students to working professionals. Consequently, social networking (SN) has potential to become useful tools for students in professional education for information sharing, communication and collaboration. Such a SNS, if designed for EMGT program, might lead to greater interaction among the students who are mostly full-time employees. A secondary research was conducted which included background on Web 2.0 technologies and literature review on SNS in professional education to understand how a SNS for academic programs could be beneficial. This helped in creation of a survey to capture students’ perceptions about EMGT SNS and the student responses to the survey are analyzed and discussed. The survey had a total response rate of 49% with survey results indicating 45% of respondents recommending EMGT SNS. The survey was evaluated based on important factors like level of exposure and potential benefits as these could influence students’ opinions about EMGT SNS. Findings of the survey are summarized in this report to understand the possibility for a dedicated SNS for the EMGT graduate program

An Optimized Node Level Lightweight Security Algorithm for Cloud Assisted-IoT

The fastest-evolving technology, the Internet of Things (IoT), will advance the fields of agriculture, defense, and medical electronics. IoT is focused on giving every object a purpose. IoT with cloud assistance offers a potential remedy for the issue of data expansion for individual objects with restricted capabilities. With the increasing use of cloud technology, the Internet of Things (IoT) has encountered additional security hurdles when it comes to exchanging data between two parties. To address this issue, a thorough investigation was conducted into a secure cloud-assisted strategy for managing IoT data, which ensures the safety of data during its collection, storage, and retrieval via the cloud, while also considering the growing number of users. To achieve this, a lightweight security mechanism that is optimized at the node level is implemented in the proposed system. By utilizing our technology, a secure IoT infrastructure can be established to prevent the majority of data confidentiality threats posed by both insiders and outsiders. Using a heartbeat sensor and a node MCU, we create a heartbeat monitoring system. At the node MCU level, giving security to the patient's health data and preventing unauthorized users from attacking it. Smaller key sizes and lightweight security techniques for IoT devices with minimal power, lower power and memory consumption and Execution time, transmission capacity reserve is used to achieve security. In order to achieve this. The performance of the RSA and ECC algorithms in terms of execution time, power consumption, and memory use have been tabulated for this experimental arrangement. The ECC method occurs to produce the best results in tiny devices

Aligning an ISO/EIC 42010 System Architecture Model and Agile Practice

The ISO/EIC 42010 system architecture description standard evolved over a number of years with substantial practitioner inputs. It presents a high level, top-down view of requirements that may be interpreted as needed for different applications. Agile system development methods have proved effective in practice, but represent a bottom up view drawing on user stories. The question considered in this paper is how they might be harmonised. Experience from using these tools over several years in practical masters degree student projects has been used to explore this question. We suggest a logical compatibility lies in their core themes: stakeholder needs (who) frame architecture descriptions (what) and the associated rationale (why). A particular interpretation of ISO/EIC 42010 and a model outlining the evolution of architecture in an agile environment are presented. Several suggestions for future research are made

A comparative study of safety and efficacy of tiotropium bromide with salbutamol in moderate persistent bronchial asthma in a tertiary care hospital

Background: The objective of this study was to compare the safety and efficacy of tiotropium bromide with salbutamol in moderate persistent cases of bronchial asthma at tertiary care hospital. Methods: This was an open label, randomized parallel group study done in Government General Hospital, Srikakulam for a period of 12 weeks. Group-1 was given tiotropium bromide metered dose inhalational therapy 18mcg once daily in 50 patients. Group-2 was given salbutamol metered dose inhalational therapy 100mcg thrice daily in 30 patients. Results: Symptomatic improvement was observed in l two groups. At end point, mean FEV1 in tiotropium bromide treatment group improved by 149.96% compared with 135.16% salbutamol treatment group. At end point, mean FVC value in tiotropium bromide treatment group improved by 145.71% compared with 122.34% in salbutamol group. Mean FEV1 / FVC also improved by 155.41% in tiotropium bromide group compared with 105.41 % in salbutamol group.Conclusion: The present study proved tiotropium provide superior safety and efficacy relative to control drug in bronchial asthma patients in both clinical assessment score and spirometrically.

Study on Mangrove Ecology and Impact in Kakinada Bay

The southern fringes of the Kakinada Bay are predominantly mud-flats interrupted by creeks/rivers which traverse, at the hayw ard end , through dense forests of mangrove as mentioned by Ramasarma and Ganapathi (1968) in their study on the Bay hydrography. The larger trees are located at a height of 03 m in relation to creek river low water level but in high tide and spring tides major parts are innundated. A part of the system forms a fringe along the eroding creek/river banks with roots in the water but on the bay-ward side the trees are succeeded by vascular plants, the shrubs and grasses on the mudflats due, probably, to show encroachment and reclamation for human habitation and paddyfields. especially in Matlapalem creek (Rajyalakshmi. 1975). However, the creeks are highly saline in non-monsoonal seasons, deep with a directional flow towards the Bay

A study on awareness and acceptance of contraceptive methods in postpartum women in a tertiary care institute

Background: Contraception is an important tool to reduce unwanted pregnancy and promote healthy living. The benefits of family planning program are recognized worldwide to improve health, social and economic status of families. The objective of the study is to estimate the prevalence of awareness for various contraceptive methods among postpartum women, to find the acceptance of different contraceptive methods and evaluate the factors affecting the same.Methods: The study is a cross-sectional observational study conducted among postpartum women who delivered in Narayana medical college hospital over a period of 1 year. The awareness, acceptance and reason or refusal for contraception was assessed. The data obtained was analyzed to generate graphs and tables.Results: A total of 61% women were aware of at least one method of contraception. 74% were using a contraceptive at the time of study. 39% were unaware of any contraceptive method. 49% preferred intrauterine contraceptive device. Main reason for non-acceptance of contraceptive was couple’s desire for a male child. Health professionals were the main source of imparting the knowledge of birth spacing.Conclusions: Regular antenatal counselling to all pregnant women must be done in every hospital in a village to tertiary care centres. Information should be provided about various contraceptive methods and patient should be able to choose a method of her own choice. A strong motivation is required to adopt a suitable method individualised to each woman

Modelling Ground-Foundation Interactions

Geotechnical practice deals with designing foundations and earth structures. Structure – Foundation –\ud Grou nd interaction is a unique field or topic that concerns both structural and geotechnical engineers. Most geotechnical problems are very sensitive to foundation geometry (length, diameter, spacing), flexural stiffness etc. Even basic parameters such as bearing capacity of shallow foundations, ultimate axial and lateral load capacities of deep/pile foundations, are influenced by the foundation characteristics. More importantly, the serviceability criterion can be satisfied only by proper and rational estimates of structure – found ation – ground interactions. The paper summarizes modelling approaches for foundation – ground interactions, a leaning instability approach for tall structures, and analysis of geosynthetic-reinforced foundation beds