scholarly journals Compartment Model of Mixing in a Bubble Trap and Its Impact on Chromatographic Separations

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 780
Author(s):  
Jürgen Beck ◽  
William Heymann ◽  
Eric von Lieres ◽  
Rainer Hahn
Keyword(s):  
Compartment Model ◽  
Packed Bed ◽  
Pilot Scale ◽  
Band Broadening ◽  
Case Scenario ◽  
Chromatographic Separations ◽  
Worst Case ◽  
Wide Range ◽  
Mixing Behavior ◽  
Bubble Trap

Chromatography equipment includes hold-up volumes that are external to the packed bed and usually not considered in the development of chromatography models. These volumes can substantially contribute to band-broadening in the system and deteriorate the predicted performance. We selected a bubble trap of a pilot scale chromatography system as an example for a hold-up volume with a non-standard mixing behavior. In a worst-case scenario, the bubble trap is not properly flushed before elution, thus causing the significant band-broadening of the elution peak. We showed that the mixing of buffers with different densities in the bubble trap device can be accurately modeled using a simple compartment model. The model was calibrated at a wide range of flow rates and salt concentrations. The simulations were performed using the open-source software CADET, and all scripts and data are published with this manuscript. The results illustrate the importance of including external holdup volumes in chromatography modeling. The band-broadening effect of tubing, pumps, valves, detectors, frits, or any other zones with non-standard mixing behavior can be considered in very similar ways.

South Africa at a Turning Point?

2015 ◽  
Vol 53 (3) ◽  
pp. 477-486 ◽  
Author(s):  
Elke Zuern
Keyword(s):  
South Africa ◽  
Turning Point ◽  
Case Scenario ◽  
State Collapse ◽  
Worst Case ◽  
South Africans ◽  
Nelson Mandela ◽  
Wide Range ◽  
Electricity Provision

South Africa is at a crossroads. The state has not adequately addressed dire human development needs, often failing to provide the services it constitutionally guarantees. As a result, citizens are expressing their frustrations in a variety of ways, at times including violence. These serious challenges are most readily apparent in poverty, inequality and unemployment statistics, but also in electricity provision, billing and affordability as well as a recent spate of racially motivated attacks which highlight the tension both among South Africans and between South Africans and darker skinned foreigners. The country has, however, been on the brink before and avoided the worst-case scenario of full-scale civil war and state collapse. Far too often South Africa's past successes have been attributed to the role of one man, Nelson Mandela. While Mandela was indeed an extraordinary human being who rightly deserved the international awards and accolades as well as the deep admiration of so many, South Africa's triumphs as a society and a state are the product of both cooperative and conflicting contributions by a wide range of actors. A central question at the present juncture is how well equipped domestic actors and institutions are to address the crisis. The following pages seek to provide some insights and through the perspectives of three authors to consider causes and possible responses.

scholarly journals Landscape structure and management alter the outcome of a pesticide ERA: evaluating impacts of endocrine disruption using the ALMaSS European Brown Hare model

2015 ◽  
Author(s):  
Chris J. Topping ◽  
Lars Dalby ◽  
Flemming Skov
Keyword(s):  
Risk Assessment ◽  
Landscape Management ◽  
Emergent Properties ◽  
Gradual Change ◽  
Case Scenario ◽  
European Brown Hare ◽  
Worst Case ◽  
Wide Range ◽  
Negative Impacts ◽  
Map Data

There is a gradual change towards explicitly considering landscapes in regulatory risk assessment. To realise the objective of developing representative scenarios for risk assessment it is necessary to know how detailed a landscape representation is needed to generate a realistic risk assessment, and indeed how to generate such landscapes. This paper evaluates the contribution of landscape and farming components to a model based risk assessment of a fictitious endocrine disruptor on hares. In addition, we present methods and code examples for generation of landscape structures and farming simulation from data collected primarily for EU agricultural subsidy support and GIS map data. Ten different Danish landscapes were generated and the ERA carried out for each landscape using two different assumed toxicities. The results showed negative impacts in all cases, but the extent and form in terms of impacts on abundance or occupancy differed greatly between landscapes. A meta-model was created, predicting impact from landscape and farming characteristics. Scenarios based on all combinations of farming and landscape for five landscapes representing extreme and middle impacts were created. The meta-models developed from the 10 real landscapes failed to predict impacts for these 25 scenarios. Landscape, farming, and the emergent density of hares all influenced the results of the risk assessment considerably. The study indicates that prediction of a reasonable worst case scenario is difficult from structural, farming or population metrics; rather the emergent properties generated from interactions between landscape, management and ecology are needed. Meta-modelling may also fail to predict impacts, even when restricting inputs to combinations of those used to create the model. Future ERA may therefore need to make use of multiple scenarios representing a wide range of conditions to avoid locally unacceptable risks. This approach could now be feasible Europe wide given the landscape generation methods presented.

Membrane bioreactors as core technology for water loop closure in a maltery

2008 ◽  
Vol 57 (11) ◽  
pp. 1805-1808
Author(s):  
Heleen De Wever ◽  
Wesley Boënne ◽  
Michel Danau ◽  
N. Vanderspiegel ◽  
Kris Lambert ◽  
...  
Keyword(s):  
Water Reuse ◽  
Pilot Scale ◽  
Membrane Bioreactors ◽  
Second Step ◽  
Case Scenario ◽  
Worst Case ◽  
Malt Quality ◽  
Core Technology ◽  
Treatment Train ◽  
Closed Water

This paper reports on the potential for water reuse in the malting sector. Core unit of a treatment train to close the water loop was a membrane bioreactor (MBR). Three different commercial submerged membranes were compared in terms of their fouling potential in this application. In a second step, MBR permeate was subjected to reverse osmosis (RO) and several oxidation processes. Neither the MBR permeate nor the RO permeate or oxidized water streams showed an adverse effect on malt quality. The worst case scenario was then tested in a closed water loop over several malting cycles at pilot scale and the effect on water and malt quality investigated.

Reliability Assessment Approach for DCV Aegir Pipeline Installation Analyses

2014 ◽  
Author(s):  
Erwan Karjadi ◽  
Henk Smienk
Keyword(s):  
Reliability Assessment ◽  
Case Scenario ◽  
Worst Case ◽  
New Era ◽  
Wide Range ◽  
Reliability Method ◽  
Assessment Approach ◽  
Preparation Phase ◽  
Safe Approach ◽  
Scenario Approach

Heerema Marine Contractors (HMC) is entering a new era of pipe laying with the new Deepwater Construction Vessel (DCV) Aegir. This vessel is designed to be able to reel/J-lay pipelines for a wide range of pipe dimension and water depth combinations. To define the limit of installation workability windows, the pipeline installation analyses (reeling or J-lay method) during the project engineering preparation phase are normally performed based on the consideration that a combination of several “worst case” scenarios will occur at the same time during the installation event. The worst case scenarios are assumed in terms of pipe resistance (geometry/property), positioning of the vessel/equipment, environmental loads, etc. This method of calculations can be considered as the most practical and safe approach. However, as an accumulation of conservative assumptions is inherently being made within this approach, it can lead to a situation that the pipeline cannot be installed or lead to insufficient workability window for pipeline installation operation. Another shortcoming of this worst case scenario approach is that we are not able to quantify the probability of failure for a certain pipeline installation scenario. The reliability analyses and assessment for pipeline construction/installation as described in the DNV-OS-F101 code [1] can be used as an alternative. The assessment can lead to some relaxations of the pipeline installation workability in a safe manner whilst accepting some level of the risks. The purpose of this paper is to present the development of reliability assessment approach for pipeline installation analyses for the DCV Aegir. One of the important steps of the development is the setup of a pipeline database based on the as-built pipeline data from HMC’s past projects. The database can be used to estimate the typical distributions of the pipe dimension and properties as input for the reliability analyses. Three examples are given in this paper, two are related to the reeling pipeline analysis with standard pipe ends and counterbored pipe ends (First Order Reliability Method FORM and Monte Carlo approach) and another example is related to J-lay pipeline installation analysis. The results of the assessments are correlated with the DNV guideline for the acceptance of nominal target probability of failures against the safety classes.

Stakeholder Management (Donald Getz)

2021 ◽  
Author(s):  
Donald Getz
Keyword(s):  
Crisis Management ◽  
Case Studies ◽  
Stakeholder Management ◽  
Political Support ◽  
Case Scenario ◽  
Worst Case ◽  
Key Stakeholders ◽  
Wide Range ◽  
Privately Owned

This chapter presents concepts and principles for stakeholder manage- ment in a time of crisis, and how stakeholder management is an essential part of recovery and resilience. Definitions, stakeholder theory, case studies and practical advice for event stakeholder management has been provided in the book Event Stakeholders by Mathilda van Niekerk and Donald Getz (2019). However, it was written before the 2020 pandemic and did not specifically address crisis management. A number of interviews and case studies have been incorporated in this book, reflecting the views of experts in a wide range of event settings and types. The interviewees were asked to comment on the impacts of the Covid-19 pandemic on the events sector, from their perspectives, on actions taken and plans for recovery, and on the key stakeholders for recovery and building resilience. A summary of the interviews and case studies is contained in the final chapter. While not all crises are as serious as the pandemic, 2020 generally being seen as a worst-case scenario, this material is valuable in shedding light on any form of crisis facing events, and in particular on the vital roles played by internal and external stakeholders. Who or what is a stakeholder? For a privately owned event, owners and direct investors are the shareholders, while stakeholders can broadly be defined as persons or organizations that have something to gain or lose by the actions of the event. They might have an investment in an event, or a perceived interest. An investment can be tangible or intangible. For example, tangible investments can be in the form of being a marketing or logistical partner, supplier, volunteer, paid employee, sponsor or other type of participant. Communities, cities and destinations invest in events and consider themselves to be important stakeholders, their investments being both tangible (e.g., money, venues, marketing, other services) or intangible (e.g., moral and political support, attendance, or – at a minimum – tolerance).

scholarly journals Cerebral Venous Sinus Thrombosis (CVST) in a Young Female with COVID-19 Infection and Oral Contraceptive Pill Ingestion Double Hit? – A Case Report

2021 ◽  
pp. 3060-3062
Author(s):  
Apurva Dubey ◽  
Sourya Acharya ◽  
Samarth Shukla ◽  
Sunil Kumar
Keyword(s):  
Venous Thrombosis ◽  
Virus Disease ◽  
Sinus Thrombosis ◽  
Oral Contraceptive Pill ◽  
Signs And Symptoms ◽  
Nasopharyngeal Swab ◽  
Atypical Pneumonia ◽  
Case Scenario ◽  
Worst Case ◽  
Wide Range

The Chinese centre for disease control and prevention detected a novel severe acute respiratory syndrome - coronavirus 2 (SARS - CoV2) from a nasopharyngeal swab in a patient with atypical pneumonia in Wuhan, Hubei province, China on January, 2020.1 Corona virus disease-19 (COVID-19) has a high mortality rate in critically ill patients. Acute heart injury, acute kidney injury and sudden thromboembolic events are becoming more common and they can occur regardless of pulmonary or respiratory symptoms.1-5 COVID-19 has been shown to have the ability to create a hypercoagulable state in recent studies.2,3,6,7 Viral infections can cause endothelial cell dysfunction, resulting in excessive throbbing production and fibrinolysis inhibition.8- 10 Hypoxia is also linked to an increase in blood viscosity and the activation of hypoxia-related genes that regulate coagulation and fibrinolysis making thrombotic events more likely.11,12 This septic-like coagulopathy can also lead to venous thrombosis, pulmonary embolism, and, in the worst-case scenario, disseminated intravascular coagulation.3,4 Cerebral venous thrombosis, in particular, can manifest itself in a wide range of neurologic signs and symptoms.13,14 and had consistently fatal results.

Reducing Probabilistic Weather Forecasts to the Worst Case Scenario: Anchoring Effects

2008 ◽  
Author(s):  
Sonia Savelli ◽  
Susan Joslyn ◽  
Limor Nadav-Greenberg ◽  
Queena Chen
Keyword(s):  
Case Scenario ◽  
Worst Case ◽  
Weather Forecasts ◽  
Worst Case Scenario ◽  
Anchoring Effects

EXPEDITION TO MALI, 2020

2020 ◽  
pp. 12-28
Author(s):  
D. V. Vaniukova ◽  
◽  
P. A. Kutsenkov ◽  
Keyword(s):  
Mass Murder ◽  
The State ◽  
Case Scenario ◽  
Worst Case ◽  
Traditional Art ◽  
Peter The Great ◽  
State Museum ◽  
Bobo Dioulasso ◽  
Oriental Studies ◽  
The Village

The research expedition of the Institute of Oriental studies of the Russian Academy of Sciences has been working in Mali since 2015. Since 2017, it has been attended by employees of the State Museum of the East. The task of the expedition is to study the transformation of traditional Dogon culture in the context of globalization, as well as to collect ethnographic information (life, customs, features of the traditional social and political structure); to collect oral historical legends; to study the history, existence, and transformation of artistic tradition in the villages of the Dogon Country in modern conditions; collecting items of Ethnography and art to add to the collection of the African collection of the. Peter the Great Museum (Kunstkamera, Saint Petersburg) and the State Museum of Oriental Arts (Moscow). The plan of the expedition in January 2020 included additional items, namely, the study of the functioning of the antique market in Mali (the “path” of things from villages to cities, which is important for attributing works of traditional art). The geography of our research was significantly expanded to the regions of Sikasso and Koulikoro in Mali, as well as to the city of Bobo-Dioulasso and its surroundings in Burkina Faso, which is related to the study of migrations to the Bandiagara Highlands. In addition, the plan of the expedition included organization of a photo exhibition in the Museum of the village of Endé and some educational projects. Unfortunately, after the mass murder in March 2019 in the village of Ogossogou-Pel, where more than one hundred and seventy people were killed, events in the Dogon Country began to develop in the worst-case scenario: The incessant provocations after that revived the old feud between the Pel (Fulbe) pastoralists and the Dogon farmers. So far, this hostility and mutual distrust has not yet developed into a full-scale ethnic conflict, but, unfortunately, such a development now seems quite likely.

Risk-Based Robust Bidding Strategies for EVs’ Aggregators in Day-ahead Markets with Uncertainty

2020 ◽  
Author(s):  
Ahmed Abdelmoaty ◽  
Wessam Mesbah ◽  
Mohammad A. M. Abdel-Aal ◽  
Ali T. Alawami
Keyword(s):  
Robust Optimization ◽  
Electricity Market ◽  
Real Life ◽  
Optimization Approach ◽  
Case Scenario ◽  
Worst Case ◽  
Bidding Strategies ◽  
Wind Generators ◽  
Proposed Model ◽  
Optimal Bidding

In the recent electricity market framework, the profit of the generation companies depends on the decision of the operator on the schedule of its units, the energy price, and the optimal bidding strategies. Due to the expanded integration of uncertain renewable generators which is highly intermittent such as wind plants, the coordination with other facilities to mitigate the risks of imbalances is mandatory. Accordingly, coordination of wind generators with the evolutionary Electric Vehicles (EVs) is expected to boost the performance of the grid. In this paper, we propose a robust optimization approach for the coordination between the wind-thermal generators and the EVs in a virtual<br>power plant (VPP) environment. The objective of maximizing the profit of the VPP Operator (VPPO) is studied. The optimal bidding strategy of the VPPO in the day-ahead market under uncertainties of wind power, energy<br>prices, imbalance prices, and demand is obtained for the worst case scenario. A case study is conducted to assess the e?effectiveness of the proposed model in terms of the VPPO's profit. A comparison between the proposed model and the scenario-based optimization was introduced. Our results confirmed that, although the conservative behavior of the worst-case robust optimization model, it helps the decision maker from the fluctuations of the uncertain parameters involved in the production and bidding processes. In addition, robust optimization is a more tractable problem and does not suffer from<br>the high computation burden associated with scenario-based stochastic programming. This makes it more practical for real-life scenarios.<br>

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