scholarly journals The simplex algorithm for the rapid identification of operating conditions during early bioprocess development: Case studies in FAb' precipitation and multimodal chromatography

2011 ◽  
Vol 108 (9) ◽  
pp. 2162-2170 ◽  
Author(s):  
Sunil Chhatre ◽  
Spyridon Konstantinidis ◽  
Yu Ji ◽  
Simon Edwards-Parton ◽  
Yuhong Zhou ◽  
...  
Keyword(s):  
Case Studies ◽  
Simplex Algorithm ◽  
Rapid Identification ◽  
Operating Conditions ◽  
Bioprocess Development ◽  
Multimodal Chromatography

scholarly journals Simplex-based optimization of numerical and categorical inputs in early bioprocess development: Case studies in HT chromatography

2017 ◽  
Vol 12 (8) ◽  
pp. 1700174 ◽  
Author(s):  
Spyridon Konstantinidis ◽  
Nigel Titchener-Hooker ◽  
Ajoy Velayudhan
Keyword(s):  
Case Studies ◽  
Bioprocess Development

scholarly journals Case Studies for Non-Detection of Islanding by Grid-Connected In-Parallel Photovoltaic and Electrical Energy Storage Systems Inverters

2019 ◽  
Vol 9 (5) ◽  
pp. 817
Author(s):  
Jong Lim ◽  
Hye Hwang ◽  
Woo Shin ◽  
Hyung-Jun Song ◽  
Young-Chul Ju ◽  
...  
Keyword(s):  
Energy Storage ◽  
Case Studies ◽  
Storage Systems ◽  
Electrical Energy ◽  
Operating Conditions ◽  
Islanding Detection ◽  
Energy Storage Systems ◽  
Pv System ◽  
Electrical Energy Storage ◽  
Grid Connection

In Korea, there is a rule for Renewable Energy Certification with weighting 5.0, to expand grid linkage capacity and to improve the stability of the grid to accommodate photovoltaic (PV) systems in a distributed power system. Due to this rule, many power companies and operators are trying to install electrical energy storage systems that are able to operate in conjunction with PV system power. These systems operate in parallel at the same grid connection point. This paper presents the results of case studies on the failure to detect islanding operation. Test evaluation devices that could be bi-directionally charged and discharged were implemented for an islanding detection test. Testing was conducted under a variety of operating conditions. When a single inverter was operated under the islanding condition, it was stably stopped within 0.5 s using the Korean grid-code standard. However, when two inverters were operated at the same time under the islanding condition, islanding detection failed and the two inverters continued to feed the connected RLC (resistor, inductor, capacitor) loads in the isolated section known as an island. Different algorithms used by PCS (power conversion system) manufacturers to detect islanding might cause this phenomenon. Therefore, it is necessary for a new PCS test standard to detect islanding.

scholarly journals Analysis of Control Valves Stiction Quantification Tool

2017 ◽  
Vol 16 (2) ◽  
pp. 70
Author(s):  
H. Zabiri ◽  
M Gaberalla M K Elarafi
Keyword(s):  
Case Studies ◽  
Process Model ◽  
Control Valve ◽  
Operating Conditions ◽  
Optimal Conditions ◽  
Model Accuracy ◽  
Control Loops ◽  
Wide Range ◽  
Valve Stiction ◽  
The Impact

Control valve stiction is considered as one of the main sources of control loops nonlinearities which impacts plants profitability. In turn, this phenomenon hinders the plant from being operated at optimal conditions. Therefore, an efficient and accurate stiction quantification algorithm is required for accurate stiction compensation and timely scheduling of control valve maintenance. This research investigates the robustness and recommends improvements to the previously developed stiction quantification approach by Zabiri et al. The approach was tested under several operating conditions which were simulated in five case studies by using MATLAB software. The case studies investigated the impact of a wide range of stiction values, controller tuning, disturbance, time delay and noise on the quantification approach. The algorithm was found to be robust since it quantified the correct values of stiction regardless of the operating conditions. It was found that the accuracy of the quantification results depends on the process model accuracy, number of data samples and the search resolution. A number of improvements were recommended and validated by simulation in order to further enhance the current quantification approach. As conclusion, the algorithm can be applied on any type of process due to its robustness.

Case Studies of Fatigue Failures in Defence Aircraft Components

2014 ◽  
Vol 891-892 ◽  
pp. 81-86 ◽  
Author(s):  
Cathy Smith ◽  
Drew Donnelly
Keyword(s):  
Case Studies ◽  
Failure Modes ◽  
Correct Diagnosis ◽  
Cost Savings ◽  
Operating Conditions ◽  
Driving Mechanisms ◽  
Wide Range ◽  
Australian Defence Force ◽  
Remedial Actions ◽  
Fatigue Failures

Components and systems of military aircraft are regularly subjected to severe operating conditions, which lead to the development of a wide range of failure modes. The Defence Science and Technology Organisations (DSTO) Forensic Engineering and Accident Investigation group investigates such failures for the Australian Defence Force (ADF). Correct diagnosis of these failures has provided the ADF with immediate advice that has contributed to increased aircraft safety, improved operational availability, and significant cost savings. This paper presents a number of case studies of recent fatigue failures which have occurred in Australian Defence aircraft. The case studies include examples of failures which occurred via differing fatigue initiating and driving mechanisms. Details of the forensic investigations relating to each case study are provided and the ensuing remedial actions discussed.

scholarly journals Emissions from urban bus fleets running on biodiesel blends under real-world operating conditions: Implications for designing future case studies

2019 ◽  
Vol 111 ◽  
pp. 276-292 ◽  
Author(s):  
Mohammad Ali Rajaeifar ◽  
Meisam Tabatabaei ◽  
Mortaza Aghbashlo ◽  
Abdul-Sattar Nizami ◽  
Oliver Heidrich
Keyword(s):  
Case Studies ◽  
Real World ◽  
Operating Conditions ◽  
Biodiesel Blends ◽  
Urban Bus ◽  
Future Case

Active Control of Combustion for Optimal Performance

1999 ◽  
Vol 121 (3) ◽  
pp. 437-443 ◽  
Author(s):  
M. D. Jackson ◽  
A. K. Agrawal
Keyword(s):  
Cost Function ◽  
Simplex Algorithm ◽  
Operating Conditions ◽  
Variable Speed ◽  
Fuel Flow ◽  
Loop Feedback ◽  
Closed Loop Feedback ◽  
Downhill Simplex ◽  
The Cost ◽  
And Diffusion

Combustion-zone stoichiometry and fuel-air premixing were actively controlled to optimize the combustor performance over a range of operating conditions. The objective was to maximize the combustion temperature, while maintaining NOx within a specified limit. The combustion system consisted of a premixer located coaxially near the inlet of a water-cooled shroud. The equivalence ratio was controlled by a variable-speed suction fan located downstream. The split between the premixing air and diffusion air was governed by the distance between the premixer and shroud. The combustor performance was characterized by a cost function evaluated from time-averaged measurements of NOx and oxygen concentrations in products. The cost function was minimized by the downhill simplex algorithm employing closed-loop feedback. Experiments were conducted at different fuel flow rates to demonstrate that the controller optimized the performance without prior knowledge of the combustor behavior.

Drilling Riser Case Studies Comparing the Drag Performance of LGS Technology to Conventional Buoyancy Units and Fairings

2017 ◽  
Author(s):  
Daniel R. Johnstone ◽  
Andrew E. Potts ◽  
Hayden Marcollo ◽  
Phillip Kurts
Keyword(s):  
Case Studies ◽  
Drag Force ◽  
Bluff Body ◽  
Circular Cross Section ◽  
Operating Conditions ◽  
The North ◽  
Damage Rate ◽  
Readiness Level ◽  
Drilling Operations ◽  
The North Sea

Deepwater drilling risers have a substantial portion (>70%) of buoyancy modules covering their entire length. The circular cross-section of these modules acts as a bluff body exhibiting significant Vortex-Induced Vibration (VIV) response, resulting in fatigue in the riser/wellhead and drag force amplification of the riser. Drilling operations can be suspended when the drag force on the riser adversely affects the top and bottom angles, a response which is exacerbated by drag force amplification due to VIV. In 2015 and 2016, Longitudinally Grooved Suppression (LGS)1 technology was developed to field qualified Technology Readiness Level (TRL of 6) [1] offering a technical advantage to drilling operators over existing options. In order to investigate the relative performance and quantify the benefits of LGS over conventional cylindrical Drilling Riser Buoyancy Modules (DRBMs) with and without fairings, a series of case studies encompassing typical operating conditions at drilling locations in several regions around the world (including the Gulf of Mexico, Brazil, the North Sea, and Australia) have been carried out to examine the performance in terms of drag (affecting operability due to top angle) and fatigue damage rate of the riser. The results indicate that LGS outperforms conventional buoyancy risers and fairings-equipped risers with regard to riser operability limits and fatigue.

A Numerical Thermal-Hydraulic Model to Simulate the Fast Transients in a Supercritical Water Channel Subjected to Sharp Pressure Variations

2016 ◽  
Vol 19 (5) ◽  
pp. 1529-1541 ◽  
Author(s):  
Goutam Dutta ◽  
Jin Jiang ◽  
Rohit Maitri ◽  
Chao Zhang
Keyword(s):  
Case Studies ◽  
Cross Section ◽  
Supercritical Water ◽  
Water Channel ◽  
Circular Cross Section ◽  
Hydraulic Model ◽  
Operating Conditions ◽  
Exit Pressure ◽  
Fast Transient

AbstractThe present work demonstrates the extension of a thermal-hydraulic model, THRUST, with an objective to simulate the fast transient flow dynamics in a supercritical water channel of circular cross section. THRUST is a 1-D model which solves the nonlinearly coupled mass, axial momentum and energy conservation equations in time domain based on a characteristics-dependent fully implicit finite difference scheme using an Eulerian approach. The model developed accounts for the compressibility of the supercritical flow by considering the finite value of acoustic speed in the solution algorithm and treats the boundary conditions naturally. A supercritical water channel of circular cross section, for which the experimental data is available at steady state operating conditions, is chosen for the transient simulations to start with. Two different case studies are undertaken with a purpose to assess the capability of the model to analyze the fast transient processes caused by the large reduction in system pressure. The first transient case study is where the initial exit pressure is reduced by 1MPaexponentially in a time span of 5s. In the second case study, the transient is initiated with a sudden step decrease in the exit pressure by the same amount. Results obtained for both the case studies show the desired performance from the model developed.

Modeling Effects of Two-Phase Transport in Cathode Gas Flow Channel on PEM Fuel Cell Performance

2011 ◽  
Author(s):  
Yun Wang ◽  
Ken S. Chen
Keyword(s):  
Fuel Cell ◽  
Case Studies ◽  
Liquid Water ◽  
Gas Flow ◽  
Pem Fuel Cell ◽  
Operating Conditions ◽  
Cell Performance ◽  
Two Phase ◽  
Fuel Cell Performance ◽  
Flow Channels

The objective of this study is to make an attempt at developing a sub-model that can account for the presence of liquid water in the cathode channel and couple it with other key phenomena occurring in a PEM fuel cell, including those in the anode side. The two-phase sub-model in cathode gas flow channels is based on the two-phase mixture formula. Numerical results from case studies are presented in comparison with those predicted by the single-phase channel flow sub-model. Our preliminary results indicate that liquid water accumulates along the flow channels and builds up quickly once it emerges. For the operating conditions and cell geometry chosen for the case study present in the present work, our results show that the liquid water in the channel only slightly affects the fuel cell performance. More extensive case studies are needed.

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