A literature survey on electrical-current-assisted friction stir welding

Electrical-current-assisted friction stir welding (EA-FSW) is a procedure developed for the joining of similar and dissimilar materials. EA-FSW is a newly invented solid-state process to increase welded components’ efficacy in various applications, such as marine structures. EA-FSW joints have investigated the dissimilar joints on aluminum–magnesium, aluminum–steel, and polymer-to-steel. Similar joints have been performed on aluminum, magnesium, and steel. The main parameters that affect the temperature of the nugget in EA-FSW are electrical current and tool rotational velocity. This review paper presents the fundamental principle of EA-FSW, its processes mechanism, and various types of tools, and discusses the different joints that EA-FSW welded. The effect of electrical current on the quality of similar and dissimilar joints is discussed. The simulation process and detailed modeling of the EA-FSW process are discussed in the last section

Influence of relative humidity and temperature on cultivation of pleurotus species

Fungi exhibit different behavior under different conditions and react to light, temperature, moisture content etc. The objective of  this study was to evaluate the degradation capability of three common white rot fungi, namely: Pleurotus ostreatus, P. pulmonarius, and Lentinus sajor-caju. The respective fungi were cultivated on rice straw under three different environmental conditions for 90 days. The fungi were collected, pure cultured, DNA extracted, and sequenced by ITS regions. The highest consumption of substrate occurred under the Cellar (dark) exposure condition with P. pulmonarius producing the least mass loss. The least amount of degradation occurred under the Air (daylight) condition for all of the fungi with the exception of P. pulmonarius. Exposure to light promoted the formation of fruiting bodies

Analytical and computational indoor shelter models for infiltration of carbon dioxide into buildings : comparison with experimental data

This paper describes two indoor shelter models – an analytical model and a Computational Fluid Dynamics (CFD) model - that can be used to predict the level of infiltration of carbon dioxide (CO2) into a building following a release from an onshore CO2 pipeline. The motivation behind the development of these models was to demonstrate that the effects of shelter should be considered as part of a Quantitative Risk Assessment (QRA) for CO2 pipeline infrastructure and to provide a methodology for considering the impact of a CO2 release on building occupants.A key component in the consequence modelling of a release from a CO2 pipeline is an infiltration model for CO2 into buildings which can describe the impact on people inside buildings during a release event. This paper describes the development of an analytical shelter model and a CFD model which are capable of predicting the change in internal concentration, temperature and toxic load within a single roomed building that is totally engulfed by a transient cloud of gaseous CO2. Application of the models is demonstrated by comparison with experimental measurements of CO2 accumulation in a building placed in the path of a drifting cloud of CO2. The analytical and CFD models are shown to make good predictions of the average change in internal concentration. Furthermore, it is demonstrated that the effects of shelter should be taken into account when conducting QRA assessments on CO2 pipelines. Document type: Articl

Considerations in the Development of Flexible CCS Networks

This paper discusses considerations for the design of flexibly operated Carbon Capture and Storage (CCS) pipeline networks and is based on the findings of the Flexible CCS Network Development project (FleCCSnet), funded by the UK CCS Research Centre. The project considered the impact of flexibility across the whole CCS chain, as well as studying the interfaces between each element of the system; e.g. at the entry to the pipeline system from the capture plant and at the exit from the pipeline to the storage site. The factors identified are intended to allow CCS network designers to determine the degree of flexibility in the system, allowing them to react effectively to short, medium and long term variations in the availability and flow of CO2 from capture plants and the constraints imposed on the system by CO2 storage sites. The work of the project is reviewed in this paper which explores the flexibility of power plants operating with post combustion capture systems; quantifies the available time to store (line pack) liquid CO2 in the pipeline as a function of pipeline size, the inlet mass flow rate and operating pressure; and explores the influence that uncertainty in storage parameters have on the design of the pipeline. In addition, parameters influencing short and longer term network designs are discussed in terms of varying flow rates. Two workshops contributed to the direction of the project. The first workshop identified and confirmed key questions to be considered in order to understand the most likely impacts of variability in the CO2 sources and variability in CO2 sinks on CO2 transport system design and operation. The second workshop focused on transient issues in the pipeline and storage site. Although the case studies in the work are UK based, this work is applicable to other situations where large and small sources of CO2 feed into a transportation system. The work is expected to inform a broad range of stakeholders and allow network designers to anticipate potential problems associated with the operation of a CCS network. For an effective design of CCS infrastructure, all of the factors that will have a substantial impact on CO2 flow will have to be analysed at an early stage to prevent possible bottle necks in the whole chain

Impacts of geological store uncertainties on the design and operation of flexible CCS offshore pipeline infrastructure

Planning for Carbon Capture and Storage (CCS) infrastructure needs to address the impact of store uncertainties and store flow variability on infrastructure costs and availability. Key geological storage properties (pressure, temperature, depth and permeability) can affect injectivity and lead to variations in CO2 flow, which feed back into the pipeline transportation system. In previous storage models, the interface between the reservoir performance and the transportation infrastructure is unclear and the models are unable to provide details for flow and pressure management within a transportation network in response to changes in the operation of storage sites. Variation in storage demand due to daily and seasonal variations of fossil fuels uses and by extension CO2 flow is also likely to influence transportation infrastructure availability and the capacity to deliver. This work examines, at the level of infrastructure planning, the impact of store properties on CCS transportation and injection infrastructure in the context of flow variability. Different off-shore transportation scenarios, relevant to CCS in the UK, are evaluated using rigorous process modelling tools. Considering flow variations of ±50% of a given baseline flow, the results of the analysis indicate that enabling store flexibility is simpler in reservoirs with an initial pressure above 20 MPa. Wellhead conditions are influenced significantly by subsurface conditions. The operational envelope of the storage site is limited by the proximity of wellhead conditions to the CO2 phase equilibrium line and the maximum fluid velocities inside the well. Given reductions in reservoir permeability, the requirements for pressure delivery are strongly dependent on the reservoir temperature. This work provides detailed insight on the expected impacts of store properties on transportation infrastructure design and operation

Modelling the initial spray characteristics of fire sprinklers

Sprinklers are automatically activated fixed installation suppression devices. They have found extensive applications due to minimum protection they provide for a wide range of applications including residential and warehouses. Modelling sprinkler atomization is a challenging task, due to the stochastic nature in impingement of water jets and the added complexity of sprinkler configuration. In the literature, a spray initiation framework has been developed to address the multidimensional stochastic complexity associated with fire sprinklers. The initial sprinkler spray is completely characterized in terms of the following main parameters: droplet spatial location (radius, elevation angle and azimuthal angle), droplet velocity, droplet diameter and the spatial volume flux. The present thesis aims to improve the prediction of the initial sprinkler spray characteristics through exploring different physics based modelling approaches. The sub-models for film flow and sheet trajectory adopted in the development of the fire sprinkler spray models are reviewed. Three new deterministic approaches for sprinkler atomization have been proposed by employing an existing film submodel and a detailed water sheet trajectory sub-model which has never been used for fire sprinkler applications. The developed methods simulate the orthogonal impingement of water jet to a deflecting disk, with the potential to be adapted for tilted deflectors. A comparative analysis is carried out between the three introduced methods and a reference model in terms of their predictions for droplet median diameter and initial droplet location for a range of ambient temperatures and water injection pressures. The developed methodologies have been further expanded by incorporating random behaviour to the spray formation procedure. The stochastically predicted mean velocity and volume median diameter have been compared against robust experimental data and empirical correlations. The improvements obtained by the developed methodologies are promising. In further steps, a dimensionless formulation for predicting spray characteristics, sheet breakup distance and droplet sizes, in impinging atomizers have been developed. The developed formulation is validated for impingements led the spray to occur in the rim breakup mode. Building on the proposed methodologies, a semi empirical model has been developed capable of predicting the near field spray characteristics such as spatial distribution of droplet sizes, velocities and spray volume flux from local volume fraction measurements. The research outcome would benefit the computation fluid dynamic packages to initialize the spray in a more realistic manner. The study undertaken would lead to more efficient fire suppression and/or water and fire interaction studies. In addition to this, the methodology could reduce the cost of experiments in order to quantify new sprinkler sprays

Modelling of Sprinkler Sprays using Deterministic and Stochastic Approaches

Modelling sprinkler atomization is a challenging task, due to the stochastic nature of the liquid sheet breakup process. The present study aims to improve prediction of the initial sprinkler spray characteristics through exploring different physics based modelling approaches. The sub-models for film flow and sheet trajectory adopted in the development of the fire sprinkler spray models are reviewed. Three new deterministic approaches for sprinkler atomization have been proposed by employing an existing film sub-model and a detailed water sheet trajectory sub-model which has never been used for fire sprinkler applications. The numerical integration of the sub-models with sheet instability theory has been explained in detail. The developed methods simulate the orthogonal impingement of water jet to a deflecting disk, with the potential to be adapted for tilted deflectors. A comparative analysis is carried out between the three introduced methods and a reference model in terms of their predictions for droplet median diameter and initial droplet location for a range of ambient temperatures and water injection pressures. The developed methodologies have been further expanded by incorporating random behaviour to the spray formation procedure. The stochastically predicted mean velocity and volume median diameter have been compared against robust experimental data and empirical correlations. The improvements obtained by the developed methodologies have been promising

Analysis of a semi-empirical sprinkler spray model

Modelling the atomization process in fire sprinklers has remained a challenge mainly due to the complexity of sprinkler geometry. A review of existing fire sprinkler spray modelling approaches, including film flow and sheet tracking models, showed that they mainly assumed a constant sheet velocity and linear attenuation of the sheet thickness before its disintegration. In the present study, a liquid sheet trajectory sub-model based on the solution of stream-wise conservation equations has been used to predict both sheet thickness and velocity as it radially expands. This will also help to investigate the extent to which a change in the release angle can affect the sheet characteristics. The analysis carried out shows that the proposed approach improves the predictions of mean droplet diameter and initial droplet speed. A semi-empirical approach is further introduced in the study by using experimental volume fraction measurements to characterize sprinkler sprays in the near field. For a given direction predictions have been conducted for droplet volume median diameter, water volume flux and droplet average velocity at different elevation and azimuthal locations. A reasonably good agreement is found for the near field measurements

Dog Footprint in the Heart

Cardiac manifestations of the hydatid cyst are relatively uncommon. Cardiac involvement may lead to the compression of vital organs, pulmonary hypertension, pericardial effusion, and even anaphylaxis. A 45-year-old woman presented to the Emergency Department of Tehran Heart Center with chest pain. Cardiac examination revealed relatively muffled heart sounds. Echocardiography demonstrated a round echolucent well-defined mass (47 × 25 mm) on the base and the mid lateral wall of the left ventricle (LV) without septation. Computed tomography angiography and cardiac magnetic resonance imaging revealed a large (52 mm) exophytic mass originating from the lateral wall of the LV with upward growth between the left anterior descending artery (LAD) and the left circumflex artery with no LV cavity obliteration. Coronary angiography showed upward displacement in the LAD with significant compressive narrowing. The patient underwent mass resection and grafting of the LAD. During surgery after the incision of the pericardium, the hydatid cyst entity of the mass was revealed. Hydatid cysts covered the anterolateral surface of the LV with adhesion to the pericardium. The patient recovered from the surgery uneventfully. Pathology report and immunological assays confirmed the diagnosis. During a 6-month postoperative follow-up period, she remained asymptomatic with complete recovery and no recurrence