A Computational Study on the Impact of Cycle-to-Cycle Combustion Fluctuations on Fuel Consumption and Knock in Steady-State and Drivecycle Operation

2013 ◽  
Author(s):  
Christoph Poetsch ◽  
Henrik Schuemie ◽  
Herwig Ofner ◽  
Reinhard Tatschl ◽  
Oldrich Vitek
Keyword(s):  
Steady State ◽  
Fuel Consumption ◽  
Computational Study ◽  
The Impact

Should the Lopot-Plot Be Used in Daily Practice to Optimise Hemodialysis Treatment?

2012 ◽  
Vol 8 (4) ◽  
pp. 417-423
Author(s):  
Przemysław Korohoda ◽  
Przemysław Sypka ◽  
Jacek A. Pietrzyk
Keyword(s):  
Steady State ◽  
Planning Process ◽  
Computational Study ◽  
Daily Practice ◽  
Urea Concentration ◽  
Hemodialysis Treatment

ABSTRACT The paper presents an application of the Lopot-plot, which compares the timeaveraged concentration (TAC) and the time-averaged deviation (TAD) of the weekly dialysis cycle, to comprise the results of intensive computational study. The presented case is based on 420 one-week-cycle simulations to verify the consequences implied by the change of the treatments schedule from nonuniformly to uniformly distributed over the week. The concept of steady state is explained and utilized to obtain periodical runs of the urea concentration. The presented graphs encouragingly indicate the potential of such plots in presenting results of multivariable intensive computations that should be advisably performed during the planning process of hemodialysis treatment.

scholarly journals Advanced Constitutive Modeling of the Thixotropic Elasto-Visco-Plastic Behavior of Blood: Steady-State Blood Flow in Microtubes

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 367
Author(s):  
Konstantinos Giannokostas ◽  
Yannis Dimakopoulos ◽  
Andreas Anayiotos ◽  
John Tsamopoulos
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Constitutive Model ◽  
Blood Plasma ◽  
Constitutive Modeling ◽  
Flow Direction ◽  
Momentum Balance ◽  
Plastic Behavior ◽  
Flow Investigation ◽  
The Impact

The present work focuses on the in-silico investigation of the steady-state blood flow in straight microtubes, incorporating advanced constitutive modeling for human blood and blood plasma. The blood constitutive model accounts for the interplay between thixotropy and elasto-visco-plasticity via a scalar variable that describes the level of the local blood structure at any instance. The constitutive model is enhanced by the non-Newtonian modeling of the plasma phase, which features bulk viscoelasticity. Incorporating microcirculation phenomena such as the cell-free layer (CFL) formation or the Fåhraeus and the Fåhraeus-Lindqvist effects is an indispensable part of the blood flow investigation. The coupling between them and the momentum balance is achieved through correlations based on experimental observations. Notably, we propose a new simplified form for the dependence of the apparent viscosity on the hematocrit that predicts the CFL thickness correctly. Our investigation focuses on the impact of the microtube diameter and the pressure-gradient on velocity profiles, normal and shear viscoelastic stresses, and thixotropic properties. We demonstrate the microstructural configuration of blood in steady-state conditions, revealing that blood is highly aggregated in narrow tubes, promoting a flat velocity profile. Additionally, the proper accounting of the CFL thickness shows that for narrow microtubes, the reduction of discharged hematocrit is significant, which in some cases is up to 70%. At high pressure-gradients, the plasmatic proteins in both regions are extended in the flow direction, developing large axial normal stresses, which are more significant in the core region. We also provide normal stress predictions at both the blood/plasma interface (INS) and the tube wall (WNS), which are difficult to measure experimentally. Both decrease with the tube radius; however, they exhibit significant differences in magnitude and type of variation. INS varies linearly from 4.5 to 2 Pa, while WNS exhibits an exponential decrease taking values from 50 mPa to zero.

scholarly journals The Prisoners’ Dilemma in collaborative carriers’ request selection

2021 ◽  
Vol 29 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Margaretha Gansterer ◽  
Richard F. Hartl
Keyword(s):  
Computational Study ◽  
Logistics Industry ◽  
Individual Outcomes ◽  
Selection Strategies ◽  
Prisoners Dilemma ◽  
Trading Mechanisms ◽  
And Behavior ◽  
The Impact ◽  
Idle Capacity

AbstractLogistics providers have to utilize available capacities efficiently in order to cope with increasing competition and desired quality of service. One possibility to reduce idle capacity is to build coalitions with other players on the market. While the willingness to enter such coalitions does exist in the logistics industry, the success of collaborations strongly depends on mutual trust and behavior of participants. Hence, a proper mechanism design, where carriers do not have incentives to deviate from jointly established rules, is needed. We propose to use a combinatorial auction system, for which several properties are already well researched but little is known about the auction’s first phase, where carriers have to decide on the set of requests offered to the auction. Profitable selection strategies, aiming at maximization of total collaboration gains, do exist. However, the impact on individual outcomes, if one or more players deviate from jointly agreed selection rules is yet to be researched. We analyze whether participants in an auction-based transport collaboration face a Prisoners’ Dilemma. While it is possible to construct such a setting, our computational study reveals that carriers do not profit from declining the cooperative strategy. This is an important and insightful finding, since it further strengthens the practical applicability of auction-based trading mechanisms in collaborative transportation.

scholarly journals Management of Chipping Operations in Polish Forests

2020 ◽  
Vol 3 (1) ◽  
pp. 56
Author(s):  
Arkadiusz Gendek ◽  
Monika Aniszewska ◽  
Witold Zychowicz ◽  
Tadeusz Moskalik ◽  
Jan Malaťák ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Travel Distance ◽  
Operating Efficiency ◽  
Site Location ◽  
Work Shift ◽  
Work Site ◽  
The Mean ◽  
The Impact ◽  
Machine Base

The aim of the research was to verify the impact of selected parameters on the efficiency and organization of chipper operations. The paper analyzes chipping operations in Polish forests with a focus on work site location, overnight chipper location, chipper workload per site, fuel consumption, and work shift duration, as all of these factors may affect operating efficiency. The mean chipper travel distance between sites during a shift ranged from 4.74 km to 9.5 km (chippers moved on average every other day). The mean work shift duration was 12.4 h. At the end of a shift, the chippers traveled on average from 4.2 km to 6.3 km to an overnight location. At the beginning of a workday, the chippers were dispatched to sites at a distance of 2.5 km to 4.0 km. The average fuel consumption of the forwarder-mounted chippers was 16 L/h and that of the truck-mounted chipper was 7.7 L/h. It was found that the following actions have a decisive influence on the effectiveness of the operation of the chippers: determination of the size of individual tasks and the deployment of successive forest areas, indication of the proper location of the machine base, and the method of accessing the forest area.

The impact of replenishment parameters and information sharing on the bullwhip effect: A computational study

2008 ◽  
Vol 35 (11) ◽  
pp. 3657-3670 ◽  
Author(s):  
Thomas Kelepouris ◽  
Panayiotis Miliotis ◽  
Katerina Pramatari
Keyword(s):  
Information Sharing ◽  
Computational Study ◽  
Bullwhip Effect ◽  
The Impact

scholarly journals Research on Cooperative Innovation Behavior of Industrial Cluster Based on Subject Adaptability

2016 ◽  
Vol 2016 ◽  
pp. 1-19 ◽  
Author(s):  
Xiaohui Jia ◽  
Minghui Jiang ◽  
Lei Shi
Keyword(s):  
Steady State ◽  
Evolutionary Game ◽  
Industrial Cluster ◽  
Industrial Clusters ◽  
Government Support ◽  
Correlated Equilibrium ◽  
Game Model ◽  
Cooperative Innovation ◽  
The Cost ◽  
The Impact

From the perspective of the interactive cooperation among subjects, this paper portrays the process of cooperative innovation in industrial cluster, in order to capture the correlated equilibrium relationship among them. Through the utilization of two key tools, evolutionary stable strategy and replicator dynamics equations, this paper considers the cost and gains of cooperative innovation and the amount of government support as well as other factors to build and analyze a classic evolutionary game model. On this basis, the subject’s own adaptability is introduced, which is regarded as the system noise in the stochastic evolutionary game model so as to analyze the impact of adaptability on the game strategy selection. The results show that, in the first place, without considering subjects’ adaptability, their cooperation in industrial clusters depends on the cost and gains of innovative cooperation, the amount of government support, and some conditions that can promote cooperation, namely, game steady state. In the second place after the introduction of subjects’ adaptability, it will affect both game theory selection process and time, which means that the process becomes more complex, presents the nonlinear characteristics, and helps them to make faster decisions in their favor, but the final steady state remains unchanged.

Life Prediction of Power Turbine Components for High Exhaust Back Pressure Applications: Part I — Disks

2015 ◽  
Author(s):  
Dipankar Dua ◽  
Brahmaji Vasantharao
Keyword(s):  
Steady State ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Life Prediction ◽  
Creep Damage ◽  
Back Pressure ◽  
System Level ◽  
Cyclic Life ◽  
Power Turbine ◽  
The Impact

Industrial and aeroderivative gas turbines when used in CHP and CCPP applications typically experience an increased exhaust back pressure due to pressure losses from the downstream balance-of-plant systems. This increased back pressure on the power turbine results not only in decreased thermodynamic performance but also changes power turbine secondary flow characteristics thus impacting lives of rotating and stationary components of the power turbine. This Paper discusses the Impact to Fatigue and Creep life of free power turbine disks subjected to high back pressure applications using Siemens Energy approach. Steady State and Transient stress fields have been calculated using finite element method. New Lifing Correlation [1] Criteria has been used to estimate Predicted Safe Cyclic Life (PSCL) of the disks. Walker Strain Initiation model [1] is utilized to predict cycles to crack initiation and a fracture mechanics based approach is used to estimate propagation life. Hyperbolic Tangent Model [2] has been used to estimate creep damage of the disks. Steady state and transient temperature fields in the disks are highly dependent on the secondary air flows and cavity dynamics thus directly impacting the Predicted Safe Cyclic Life and Overall Creep Damage. A System-level power turbine secondary flow analyses was carried out with and without high back pressure. In addition, numerical simulations were performed to understand the cavity flow dynamics. These results have been used to perform a sensitivity study on disk temperature distribution and understand the impact of various back pressure levels on turbine disk lives. The Steady Sate and Transient Thermal predictions were validated using full-scale engine test and have been found to correlate well with the test results. The Life Prediction Study shows that the impact on PSCL and Overall Creep damage for high back pressure applications meets the product design standards.

Driving forces and structural changes of China as a market provider for Korea

2018 ◽  
Vol 22 (3) ◽  
pp. 194-211 ◽  
Author(s):  
Yongqi Feng ◽  
Tianshu Zhang
Keyword(s):  
Steady State ◽  
Driving Force ◽  
Design Methodology ◽  
Structural Changes ◽  
Driving Forces ◽  
Consumption Expenditure ◽  
Input Output ◽  
Content Type ◽  
Fixed Capital Formation ◽  
The Impact

Purpose The purpose of this paper is to provide a better understanding of the driving forces and structural changes of China as a market provider for Korea. This paper gives the answers for the following questions: How do China’s final demands trigger the growth of its imports from Korea? And what’s the impact of China’s final demands on the import in different industries? Design/methodology/approach Based on the Multi-Regional Input-Output model and World Input-Output Table database, this paper constructs the non-competitive imports input-output (IO) table of China to Korea. According to this table, we can calculate the induced imports coefficient and comprehensive induced import coefficients of China’s four final demands for imports from Korea in the 56 industries in China. Findings Among the four driving forces, the strongest one is changes in inventories and valuables. The impact of final consumption expenditure and fixed capital formation is much lower than that of changes in inventories and valuables, but they have a broader impact for the 56 industries. This paper finds out the China’s import induction of the final demands to Korea peaked in 2005 and 2010 and decreased greatly in 2014, so the position of China as market provider for Korea will no longer rise substantially, contrarily it will be in a steady state. Originality/value First, this paper constructs the non-competitive IO table to analyze the market provider issues between two countries and provides practical ways and methods for studies on the issues of imports and market provider. Second, this paper investigates the different roles of four final demands on driving force of China as market provider for Korea and the structural changes of China as a market provider for Korea among 56 industries from 2000 to 2014.

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