Design of Energy Management System of a PEMFC–Battery– Supercapacitor Hybrid Tramway

In this chapter, a hybrid power system that consists of multiple proton exchange membrane fuel cell (PEMFC) systems, batteries, and supercapacitors (SCs) is developed for a hybrid tramway. Three energy management strategies that included a fuzzy logic control (FLC), an equivalent consumption minimization strategy (ECMS), and a state machine strategy based on droop control (SMS-DC) are utilized to coordinate multiple power sources, avoid the transients and rapid changes of power demand, and achieve high efficiency without degrading the mechanism performance for an energy management system of hybrid tramway. A hybrid system model of tramway is established with commercially available devices, and then the different energy management strategies are evaluated with a real driving cycle of tramway from Turkey. The results compared with these strategies demonstrate that the higher average efficiencies of the tramway, the lower tramway-equivalent hydrogen consumptions, and more efficient use of the batteries and SCs energy are achieved by the SMS-DC. Therefore, the appropriate energy management system for high-power hybrid tramway will improve the hydrogen consumptions of overall hybrid system and the efficiencies of each power source

Using Polymer to Maximize CO2 Flooding Performance in Light Oils

Carbon dioxide has been used to recover oil for more than 40 years. Currently, about 43% of EOR production in U.S. is from CO2 flooding. Although CO2 flooding is a well-established EOR technique, its density and viscosity nature is a challenge for CO2 projects. Low density (0.5 to 0.8 g/cm3) causes gas to rise upward in reservoirs and bypass many lower portions of the reservoir. Low viscosity (0.02 to 0.08 cp) leads to poor volumetric sweep efficiency. In heterogeneous reservoirs with high-permeability zones and natural fractures, the condition is even worse. Two methods related to polymers are studied to improve CO2 flooding performance. One is adding polymers to water to increase water viscosity during the water-alternating-gas (WAG) process, named polymer-alternating-gas (PAG) flooding. The other one is adding polymers with cosolvent to CO2, named CO2 viscosifier, to increase CO2 viscosity. To analyze the feasibility of PAG, couples model considering both miscible and polymer flooding processes are built to study the performance of PAG. Polymer adsorption and concentration, reservoir permeability, permeability variation and fluid viscosity are studied. Results show that PAG process could get higher recovery than WAG if not injectivity problem occurs. The Upper Ness formation in Spe10 model is used to study the PAG performance in a reservoir with channels. Oil recovery from PAG with a polymer concentration of 0.20 lb/stb is 6% higher than WAG process in this model. To analyze the impact of CO2 flooding in the North Burbank Unit, five sections that best represent the characteristics of the field were selected for reservoir modeling. Based on simulation results, the conventional WAG process increased average oil recovery in the North Burbank Unit by 10-13%, PAG are forecasted to increase average oil recovery 4-7% more than conventional WAG flooding in the North Burbank Unit. Based on assumptions, PAG could get positive NPV when oil price higher than $40/bbl while PAG could also obtain higher NPV than WAG in all these five sections, which indicates that PAG is both technically and economically feasible in the North Burbank unit. A black-oil pseudo-miscible model is used for study CO2 viscosifier performance in synthetic model, SPE10 model and Section TR78 in the North Burbank Unit. Results show that higher cumulative oil recovery and better sweep efficiency was observed for viscosified CO2 case in homogeneous, heterogeneous and channels reservoirs

Reconciling periodic rhythms of large-scale biological networks by optimal control

Periodic rhythms are ubiquitous phenomena that illuminate the underlying mechanism of cyclic activities in biological systems, which can be represented by cyclic attractors of the related biological network. Disorders of periodic rhythms are detrimental to the natural behaviours of living organisms. Previous studies have shown that the state transition from one to another attractor can be accomplished by regulating external signals. However, most of these studies until now have mainly focused on point attractors while ignoring cyclic ones. The aim of this study is to investigate an approach for reconciling abnormal periodic rhythms, such as diminished circadian amplitude and phase delay, to the regular rhythms of complex biological networks. For this purpose, we formulate and solve a mixed-integer nonlinear dynamic optimization problem simultaneously to identify regulation variables and to determine optimal control strategies for state transition and adjustment of periodic rhythms. Numerical experiments are implemented in three examples including a chaotic system, a mammalian circadian rhythm system and a gastric cancer gene regulatory network. The results show that regulating a small number of biochemical molecules in the network is sufficient to successfully drive the system to the target cyclic attractor by implementing an optimal control strategy

AN ANALYSIS OF AFFECTION ON THE WATER TRANSPARENCY FACTOR OF WEST LAKE

This paper is a special topic study on affecting the water transparency factor and supervising the water transparency of West Lake, 10 years in succession, and expounds the present situation variable, regularity variable, reasons and improvement methods to the water transparency of West Lake systematically and thoroughly. It gains the conclusion that the water transparency of West Lake bears less relationship with the dissolved substance, and the water transparency is mainly affected by the suspended substance. Because the nutrient substance from the base sludge dissolves out and takes place biological transformation very quick, the phosphorus density has a certain drop, however not affecting the growth and propagation of the algae, and not presenting the phenomena of the phosphorus inhibition. We regard the phosphorus isn't the nutrient element inhibiting the algae growth.Article信州大学理学部附属諏訪臨湖実験所報告 11: 3-12(1999)departmental bulletin pape

ADMINISTRATION OF THE WEST LAKE WATER AREA, HANGZHOU

The comparison test of the function of aquatic biology, such as Viviparidae, Hyriopsis Cvmingiilleal, water spinach and underwater plants on the purification of the water body, has been made in the test area of West Lake. The result shows that the spiral is the test one to improve the transparency of the water body, then the Hyriopsis Cvmingiilleal, water spinach and underwater plant in succession. At the same time planting method, raising density, purification function of water body, and the possibility of planting, have been studied.Article信州大学理学部附属諏訪臨湖実験所報告 11: 13-20(1999)departmental bulletin pape

Effect of Parents’ Encouragement on Reading Motivation: The Mediating Effect of Reading Self-Concept and the Moderating Effect of Gender

Previous research has found that parental encouragement is associated with children’s motivation to read. However, little is known about the underlying mechanisms of this association or factors that might strengthen or weaken these processes. The current research scrutinized a moderated mediation model that comprised of parental encouragement (predictor variable), reading self-concept (mediator), gender (moderator), and reading motivation (outcome variable) simultaneously. A total of 254 Chinese students (Mage = 11.35 years, SDage = 0.87) completed the Parents’ Encouragement of Extracurricular Reading Questionnaire, Reading Self-Concept Scale, and Pupil Reading Motivation Scale. Path analysis revealed that parents’ encouragement was associated with children’s reading motivation both directly and indirectly via reading self-concept, and the effect of parents’ encouragement on children’s motivation was more positive for boys than girls, while the effect of reading self-concept on children’s motivation was more positive for girls than boys. Our results highlight the importance of parental encouragement in improving children’s reading motivation, and the findings and their implications are discussed