103 research outputs found
"Asset Poverty in The United States: Its Persistence in an Expansionary Economy"
No full textFrom this paper's Preface, by Dr. Dimitri B. Papadimitriou, President: Economic growth and a rising stock market in the 1990s gave the impression that everyone was accumulating wealth and asset poverty rates were declining. The impression was supported by the official, income-based poverty measure, which exhibited a sharp decline. According to Senior Scholar Edward N. Wolff and Research Scholar Asena Caner, poverty measures should include wealth as well as income. Their study of asset poverty in the United States between 1984 and 1999 focuses on the lower end of the wealth distribution and shows that asset poverty rates did not decline during the period studied, and that the severity of poverty increased. It also shows that asset poverty is much more persistent than income poverty.
Process length variation in cysts of a dinoflagellate, Lingulodinium machaerophorum, in surface sediments: Investigating its potential as salinity proxy
No full text“Many authors have contributed to writing this paper. Those listed in the metadata are: the main/contact author, the first listed author and Brunel University author(s). For a full list of the authors, please see the PDF version.”A biometrical analysis of the dinoflagellate cyst Lingulodinium machaerophorum (Deflandre and Cookson 1955) Wall, 1967 in 144 globally distributed surface sediment samples revealed that the average process length is related to summer salinity and temperature at a water depth of 30 m by the equation (salinity/temperature) = (0.078*average process length + 0.534) with R² = 0.69. This relationship can be used to reconstruct palaeosalinities, albeit with caution. The particular ecological window can be associated with known distributions of the corresponding motile stage Lingulodinium polyedrum (Stein) Dodge, 1989. Confocal laser microscopy showed that the average process length is positively related to the average distance between process bases (R²=0.78), and negatively related to the number of processes (R²=0.65). These results document the existence of two end members in cyst formation: one with many short, densely distributed processes and one with a few, long, widely spaced processes, which can be respectively related to low and high salinity/temperature ratios. Obstruction during formation of the cysts causes anomalous distributions of the processes. From a biological perspective, processes function to facilitate sinking of the cysts through clustering
Low volume store planning for workload balancing and truckload
No full textOkutkan, Caner (Dogus Author) -- Çelepçıkay, Ömer (Dogus Author) -- Çimen, Egemen Berki (Dogus Author)In this study, it is aimed to decrease the number of days planned to be shipped in stores with low sales volume, to create a balanced work load and to increase vehicle occupancy capacity . Particularly, Less than Truckload problem is analyzed and model in this study. The techniques used in this study showed that adaptability can be achieved with shipment and store planning as well as green supply chain environment to minimize Less than Truckload (LTL) as well as gas consumption. A mathematical model was created in the direction of multi objective problem and solved in the GAMS environment. Moreover, scenario analyzes were made and the study was tested on five specially identified regions on Turkey
Investigating Hidden Flexibilities Provided by Power-to-X Considering Grid Support Strategies
No full textHighly volatile nature of renewable energy sources (RES) has increased the demand for flexibility in electrical power systems. Electrification of the industry with power-to-X (PtX) technologies is one of the most promising ways to increase energy system flexibility since industry accounts for the largest share of the world’s total energy demand. However, flexibilities provided by power-to-X models can be concealed in the simulation results due to modelling approximations. Therefore, PtX modelling must be analyzed with respect to the requirements of flexibility analysis. Additionally, the planning and operation of such multi-energy system (MES) needs to be coordinated to use the available resources (RES & PtX) optimally. Thus, a comprehensive energy management approach must be provided for MES.This study investigates the impact of model fidelity of PtX devices in flexibility analysis. Additionally, impact of hierarchical energy management system to optimally control the flexibility dispatch is investigated. First, a realistic case study is developed for multi-energy system to investigate energy system flexibility. Secondly, power-to-gas and power-to-heat models are developed in OpenModelica, and the effect of operational temperature simplifications of PtX models on flexibility analysis is investigated. Lastly, using co-simulation, PtX models are combined with Pandapower optimal power flow solver for the optimal deployment of flexibility.The findings of this study have provided a deeper insight into multi-energy system flexibility. The investigation of hidden flexibility has revealed that precision of flexibility analysis is bounded by the efficiency characterization of PtX, and correct efficiency characterization of PtX highly depends on operating temperature conditions. The study also shown that, a comprehensive control approach can be achieved by agent-based hierarchical energy management system and this new understanding may help to improve predictions for the optimum operation point of MES.Electrical Engineering | Electrical Power Engineerin
Synthesis and characterization of gamma-Bi2O3 based solid electrolyte doped with Nb2O5
No full textgamma-phase bismuth oxide is a well known high oxygen ion conductor and can be used as an electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). This study aims to determine new phases of Bi2O3-Nb2O5 binary system and the temperature dependence of the electrical transport properties. The reaction products obtained in open air atmosphere were characterized by X-ray powder diffractions (XRD). The unit cell parameters were defined from the indexes of the powder diffraction patterns. The gamma-Bi2O3 crystal system were obtained by doping 0.01 < mole% Nb2O5 < 0.04 at 750 degrees C for 48 and 96 h. Thermal behaviour and thermal stability of the phases were investigated by thermal analysis techniques. Surface and grain properties of the related phases were determined by SEM analysis. The temperature dependence of the electrical properties of gamma-Bi2O3 solid solution was measured by four-point probe d.c. conductivity method. In the investigated system, the highest value of conductivity was observed for sigma(T)=0.016 ohm(-1) cm(-1) at 650 degrees C on 4 mole% Nb2O5 addition. The electrical conductivity curves of studied materials revealed regular increase with temperature in the form of the Arrhenius type conductivity behaviour.Scientific and Technical Research Council of Turkey (TUBITAK) [108T377]The authors would like to thank the Scientific and Technical Research Council of Turkey (TUBITAK) for financial help (Grant no. 108T377)
Importance of Model Fidelity of Power to X Devices in Energy System Analysis
No full textPower-to-X (PtX) technologies are accelerating the energy transition. Increasingly, these technologies are also being leveraged as flexible energy resources to support the electrical grid. PtX models are often represented using a constant efficiency term as a linear relation between the power input and energy output. However, the operational performance of any PtX device such as an electrolyser or an electric heat pump can depend on factors such as operational temperature. In this paper, we have developed and analyzed two levels of model fidelity of the most widely assessed PtX technologies: electrolyser and heat pump systems. We assess the impact of detailed models on operation of PtX within simulation-based energy system analysis. Our results show that for electrolyser systems, the efficiency errors can be almost 0.6%. With heat pump systems, the difference in COP can be as high as 1.4.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Electrical Power Grid
An Allegory of Unthinking Slave
No full textOne of the main characters of Chinghiz Aitmatov’s novel The Day Lasts More Than a Hundred Years, Mankurt, is a Kyrgyz who is captured by the enemy, who thereafter erases his memory as a means of enslavement. Aitmatov portrays Mankurt as the embodiment of the effects of Soviet cultural dominance over Eurasian communities. Subsequently, the word mankurt entered the terminology of psychology and became tantamount to the word “assimilated.” Therefore, Aitmatov’s allegory should not be considered as a quilted point of an ideology for the sustenance of a certain identity; rather, it should be treated as the potential for the rejection of learning to live for the other; and the author must not be underrated and underappreciated by degrading this universal message. It should not be forgotten that the possessiveness of a certain group towards an author brings along the distance that others will keep, which renders him the other for them
The impact of diabetes on the association between epicardial fat thickness and extent and complexity of coronary artery disease in patients with non-ST elevation myocardial infarction
No full textSynthesis and characterization of gamma-Bi2O3 based solid electrolyte doped with Nb2O5
No full textgamma-phase bismuth oxide is a well known high oxygen ion conductor and can be used as an electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). This study aims to determine new phases of Bi2O3-Nb2O5 binary system and the temperature dependence of the electrical transport properties. The reaction products obtained in open air atmosphere were characterized by X-ray powder diffractions (XRD). The unit cell parameters were defined from the indexes of the powder diffraction patterns. The gamma-Bi2O3 crystal system were obtained by doping 0.01 < mole% Nb2O5 < 0.04 at 750 degrees C for 48 and 96 h. Thermal behaviour and thermal stability of the phases were investigated by thermal analysis techniques. Surface and grain properties of the related phases were determined by SEM analysis. The temperature dependence of the electrical properties of gamma-Bi2O3 solid solution was measured by four-point probe d.c. conductivity method. In the investigated system, the highest value of conductivity was observed for sigma(T)=0.016 ohm(-1) cm(-1) at 650 degrees C on 4 mole% Nb2O5 addition. The electrical conductivity curves of studied materials revealed regular increase with temperature in the form of the Arrhenius type conductivity behaviour
- …
