Dynamical changes from harmonic vibrations of a limited power supply driving a Duffing oscillator

The harmonic oscillations of a Duffing oscillator driven by a limited power supply are investigated as a function of the alternative strength of the rotor. The semi-trivial and non-trivial solutions are derived. We examine the stability of these solutions and then explore the complex behaviors associated with the bifurcations sequences. Interestingly, a 3D diagram provides a global view of the effects of alternate strength on the appearance of chaos and hyperchaos on the system.

Comparison of lactated Ringer's, gelatine and blood resuscitation on intestinal oxygen supply and mucosal tissue oxygen tension in haemorrhagic shock

OBJECTIVES: To evaluate the effects on intestinal oxygen supply, and mucosal tissue oxygen tension during haemorrhage and after fluid resuscitation with either blood (B; n=7), gelatine (G; n=8), or lactated Ringer's solution (R; n=8) in an autoperfused, innervated jejunal segment in anaesthetized pigs. METHODS: To induce haemorrhagic shock, 50% of calculated blood volume was withdrawn. Systemic haemodynamics, mesenteric venous and systemic acid-base and blood gas variables, and lactate measurements were recorded. A flowmeter was used for measuring mesenteric arterial blood flow. Mucosal tissue oxygen tension (PO(2)muc), jejunal microvascular haemoglobin oxygen saturation (HbO(2)) and microvascular blood flow were measured. Measurements were performed at baseline, after haemorrhage and at four 20 min intervals after fluid resuscitation. After haemorrhage, animals were retransfused with blood, gelatine or lactated Ringer's solution until baseline pulmonary capillary wedge pressure was reached. RESULTS: After resuscitation, no significant differences in macrohaemodynamic parameters were observed between groups. Systemic and intestinal lactate concentration was significantly increased in animals receiving lactated Ringer's solution [5.6 (1.1) vs 3.3 (1.1) mmol litre(-1); 5.6 (1.1) vs 3.3 (1.2) mmol litre(-1)]. Oxygen supply to the intestine was impaired in animals receiving lactated Ringer's solution when compared with animals receiving blood. Blood and gelatine resuscitation resulted in higher HbO(2) than with lactated Ringer's resuscitation after haemorrhagic shock [B, 43.8 (10.4)%; G, 34.6 (9.4)%; R, 28.0 (9.3)%]. PO(2)muc was better preserved with gelatine resuscitation when compared with lactated Ringer's or blood resuscitation [20.0 (8.8) vs 13.8 (7.1) mm Hg, 15.2 (7.2) mm Hg, respectively]. CONCLUSION: Blood or gelatine infusion improves mucosal tissue oxygenation of the porcine jejunum after severe haemorrhage when compared with lactated Ringer's solution.

Analysis of spring break-up and its effects on a biomass feedstock supply chain in northern Michigan

Demand for bio-fuels is expected to increase, due to rising prices of fossil fuels and concerns over greenhouse gas emissions and energy security. The overall cost of biomass energy generation is primarily related to biomass harvesting activity, transportation, and storage. With a commercial-scale cellulosic ethanol processing facility in Kinross Township of Chippewa County, Michigan about to be built, models including a simulation model and an optimization model have been developed to provide decision support for the facility. Both models track cost, emissions and energy consumption. While the optimization model provides guidance for a long-term strategic plan, the simulation model aims to present detailed output for specified operational scenarios over an annual period. Most importantly, the simulation model considers the uncertainty of spring break-up timing, i.e., seasonal road restrictions. Spring break-up timing is important because it will impact the feasibility of harvesting activity and the time duration of transportation restrictions, which significantly changes the availability of feedstock for the processing facility. This thesis focuses on the statistical model of spring break-up used in the simulation model. Spring break-up timing depends on various factors, including temperature, road conditions and soil type, as well as individual decision making processes at the county level. The spring break-up model, based on the historical spring break-up data from 27 counties over the period of 2002-2010, starts by specifying the probability distribution of a particular county’s spring break-up start day and end day, and then relates the spring break-up timing of the other counties in the harvesting zone to the first county. In order to estimate the dependence relationship between counties, regression analyses, including standard linear regression and reduced major axis regression, are conducted. Using realizations (scenarios) of spring break-up generated by the statistical spring breakup model, the simulation model is able to probabilistically evaluate different harvesting and transportation plans to help the bio-fuel facility select the most effective strategy. For early spring break-up, which usually indicates a longer than average break-up period, more log storage is required, total cost increases, and the probability of plant closure increases. The risk of plant closure may be partially offset through increased use of rail transportation, which is not subject to spring break-up restrictions. However, rail availability and rail yard storage may then become limiting factors in the supply chain. Rail use will impact total cost, energy consumption, system-wide CO2 emissions, and the reliability of providing feedstock to the bio-fuel processing facility.

Development of an optimization model for biofuel facility size and location and a simulation model for design of a biofuel supply chain

To mitigate greenhouse gas (GHG) emissions and reduce U.S. dependence on imported oil, the United States (U.S.) is pursuing several options to create biofuels from renewable woody biomass (hereafter referred to as “biomass”). Because of the distributed nature of biomass feedstock, the cost and complexity of biomass recovery operations has significant challenges that hinder increased biomass utilization for energy production. To facilitate the exploration of a wide variety of conditions that promise profitable biomass utilization and tapping unused forest residues, it is proposed to develop biofuel supply chain models based on optimization and simulation approaches. The biofuel supply chain is structured around four components: biofuel facility locations and sizes, biomass harvesting/forwarding, transportation, and storage. A Geographic Information System (GIS) based approach is proposed as a first step for selecting potential facility locations for biofuel production from forest biomass based on a set of evaluation criteria, such as accessibility to biomass, railway/road transportation network, water body and workforce. The development of optimization and simulation models is also proposed. The results of the models will be used to determine (1) the number, location, and size of the biofuel facilities, and (2) the amounts of biomass to be transported between the harvesting areas and the biofuel facilities over a 20-year timeframe. The multi-criteria objective is to minimize the weighted sum of the delivered feedstock cost, energy consumption, and GHG emissions simultaneously. Finally, a series of sensitivity analyses will be conducted to identify the sensitivity of the decisions, such as the optimal site selected for the biofuel facility, to changes in influential parameters, such as biomass availability and transportation fuel price. Intellectual Merit The proposed research will facilitate the exploration of a wide variety of conditions that promise profitable biomass utilization in the renewable biofuel industry. The GIS-based facility location analysis considers a series of factors which have not been considered simultaneously in previous research. Location analysis is critical to the financial success of producing biofuel. The modeling of woody biomass supply chains using both optimization and simulation, combing with the GIS-based approach as a precursor, have not been done to date. The optimization and simulation models can help to ensure the economic and environmental viability and sustainability of the entire biofuel supply chain at both the strategic design level and the operational planning level. Broader Impacts The proposed models for biorefineries can be applied to other types of manufacturing or processing operations using biomass. This is because the biomass feedstock supply chain is similar, if not the same, for biorefineries, biomass fired or co-fired power plants, or torrefaction/pelletization operations. Additionally, the research results of this research will continue to be disseminated internationally through publications in journals, such as Biomass and Bioenergy, and Renewable Energy, and presentations at conferences, such as the 2011 Industrial Engineering Research Conference. For example, part of the research work related to biofuel facility identification has been published: Zhang, Johnson and Sutherland [2011] (see Appendix A). There will also be opportunities for the Michigan Tech campus community to learn about the research through the Sustainable Future Institute.

SIZE OPTIMIZATION OF A BIOMASS TO LIQUID FUEL CONVERSION FACILITY WITHIN A BIOMASS SUPPLY CHAIN

Bioenergy and biobased products offer new opportunities for strengthening rural economies, enhancing environmental health, and providing a secure energy future. Realizing these benefits will require the development of many different biobased products and biobased production systems. The biomass feedstocks that will enable such development must be sustainable, widely available across many different regions, and compatible with industry requirements. The purpose of this research is to develop an economic model that will help decision makers identify the optimal size of a forest resource based biofuel production facility. The model must be applicable to decision makers anywhere, though the modeled case analysis will focus on a specific region; the Upper Peninsula (U.P.) of Michigan. This work will illustrate that several factors influence the optimal facility size. Further, this effort will reveal that the location of the facility does affect size. The results of the research show that an optimal facility size can be determined for a given location and are based on variables including forest biomass availability, transportation cost rate, and economy of scale factors. These variables acting alone and interacting together can influence the optimal size and the decision of where to locate the biofuel production facility. Further, adjustments to model variables like biomass resource and storage costs have no effect on facility size, but do affect the unit cost of the biofuel produced.

The Domestic Natural Gas Shortage in China

This thesis analyzes the domestic shortage in the Chinese natural gas market. Both the domestic supply and demand of natural gas are growing fast in China. However, the supply cannot catch up with the demand. Under the present pricing mechanism, the Chinese natural gas market cannot get the equilibrium by itself. Expensive imports are inadequate to fill the increasing gap between the domestic demand and supply. Therefore, the shortage problem occurs. Since the energy gap can result in the arrested development of economics, the shortage problem need to be solved. This thesis gives three suggestions to solve the problem: the use of Unconventional Gas, Natural Gas Storage and Pricing Reform.

Sedimentology and gas hydrates of IODP Expedition 311 samples

Expedition 311 of the Integrated Ocean Drilling Program (IODP) to northern Cascadia recovered gas-hydrate bearing sediments along a SW-NE transect from the first ridge of the accretionary margin to the eastward limit of gas-hydrate stability. In this study we contrast the gas gas-hydrate distribution from two sites drilled ~ 8 km apart in different tectonic settings. At Site U1325, drilled on a depositional basin with nearly horizontal sedimentary sequences, the gas-hydrate distribution shows a trend of increasing saturation toward the base of gas-hydrate stability, consistent with several model simulations in the literature. Site U1326 was drilled on an uplifted ridge characterized by faulting, which has likely experienced some mass wasting events. Here the gas hydrate does not show a clear depth-distribution trend, the highest gas-hydrate saturation occurs well within the gas-hydrate stability zone at the shallow depth of ~ 49 mbsf. Sediments at both sites are characterized by abundant coarse-grained (sand) layers up to 23 cm in thickness, and are interspaced within fine-grained (clay and silty clay) detrital sediments. The gas-hydrate distribution is punctuated by localized depth intervals of high gas-hydrate saturation, which preferentially occur in the coarse-grained horizons and occupy up to 60% of the pore space at Site U1325 and > 80% at Site U1326. Detailed analyses of contiguous samples of different lithologies show that when enough methane is present, about 90% of the variance in gas-hydrate saturation can be explained by the sand (> 63 µm) content of the sediments. The variability in gas-hydrate occupancy of sandy horizons at Site U1326 reflects an insufficient methane supply to the sediment section between 190 and 245 mbsf.

Modeling for the world crude oil and natural gas markets

Crude oil and natural gas have been essential energy sources and play a crucial role in the world economy. Changes in energy prices significantly impact economic growth. This study builds an econometric model to illustrate the substitute relation between crude oil and natural gas markets. Additionally, the determination of the oil and natural gas prices are endogenized, assuming imperfect competition to reflect a real market strategy. Our empirical results show that the overall performance of this system is acceptable, and the model can be applied to policy analysis for determining monetary or energy policy by introducing this model to the more comprehensive system.

Evaluación ambiental de las tecnologías de recuperación de gas en formaciones no convencionales

Este proyecto pretende ofrecer una visión general de una de las tecnologías más actuales de recuperación de gas en formaciones no convencionales: fracturación hidráulica o “fracking”. El proyecto está motivado por la necesidad de responder a diferentes cuestiones sobre los efectos ambientales, sociales y en la salud humana derivados de la utilización de esa tecnología. Ofrece, además, una descripción del proceso y utilización de la tecnología haciendo especial mención de los riesgos inherentes de su uso, aunque también se intenta establecer una vía de aceptación para su desarrollo cuyo fin último, a parte de los beneficios económicos de quienes la usan, es el de posibilitar la transición hacia el uso de unos recursos (energías fósiles de extracción no convencional) que requieren de dichas técnicas para mantener, a lo largo del tiempo, el suministro de una energía que se supone más respetuosa con el medio ambiente: el gas natural. En primer lugar se expone, a modo introductorio, la necesidad de utilización de nuevas técnicas de estimulación de pozos y su utilización para satisfacer las necesidades energéticas mundiales en los próximos años. A continuación se hace una revisión del marco regulatorio aplicable al gas no convencional. Seguidamente, se hace una descripción de los recursos y fuentes no convencionales de gas y la descripción del proceso de fracturación hidráulica. Se analizan los incidentes relacionados con su desarrollo y las posibilidades y mecanismos que pueden adoptarse para reducirlos. Finalmente, se proponen vías alternativas basadas en las mejores técnicas aplicables al uso de la tecnología, cuya finalidad sea la mayor consideración ambiental posible y el menor riesgo posible en la salud de las personas. ABSTRACT This project aims to provide an overview of the latest technologies in gas recovery unconventional formations: hydraulic fracturing or "fracking". The project is motivated by the need to respond to various questions on the environmental, social and human health arising from the use of this technology. It also offers a description of the process and use of technology with special mention of the inherent risks of their use, but also tries to establish a path of acceptance for development whose ultimate goal, apart from the economic benefits of those who use is of enabling the transition to the use of certain resources (fossil energy extraction unconventional) which require such techniques to maintain, over time, of an energy supply which is more environmentally friendly: natural gas. First discussed the need to use new well stimulation techniques and their use to meet the world's energy needs in the coming years. Below is a review of the regulatory framework applicable to unconventional gas. Next, there is a description of resources and unconventional sources of gas, and the description of the process of hydraulic fracturing. We analyze the incidents related to its development and the possibilities and mechanisms that can be taken to reduce them. Finally, we suggest alternative routes based on the best techniques applicable to the use of technology, aiming at the highest possible environmental consideration and the least possible risk to the health of people.

Mapping Intercellular CO2 Mole Fraction (Ci) in Rosa rubiginosa Leaves Fed with Abscisic Acid by Using Chlorophyll Fluorescence Imaging1 : Significance of Ci Estimated from Leaf Gas Exchange

Imaging of photochemical yield of photosystem II (PSII) computed from leaf chlorophyll fluorescence images and gas-exchange measurements were performed on Rosa rubiginosa leaflets during abscisic acid (ABA) addition. In air ABA induced a decrease of both the net CO2 assimilation (An) and the stomatal water vapor conductance (gs). After ABA treatment, imaging in transient nonphotorespiratory conditions (0.1% O2) revealed a heterogeneous decrease of PSII photochemical yield. This decline was fully reversed by a transient high CO2 concentration (7400 μmol mol−1) in the leaf atmosphere. It was concluded that ABA primarily affected An by decreasing the CO2 supply at ribulose-1,5-bisphosphate carboxylase/oxygenase. Therefore, the An versus intercellular mole fraction (Ci) relationship was assumed not to be affected by ABA, and images of Ci and gs were constructed from images of PSII photochemical yield under nonphotorespiratory conditions. The distribution of gs remained unimodal following ABA treatment. A comparison of calculations of Ci from images and gas exchange in ABA-treated leaves showed that the overestimation of Ci estimated from gas exchange was only partly due to heterogeneity. This overestimation was also attributed to the cuticular transpiration, which largely affects the calculation of the leaf conductance to CO2, when leaf conductance to water is low.

New data on the Vrancea Nappe (Moldavidian Basin, Outer Carpathian Domain, Romania): paleogeographic and geodynamic reconstructions

A study has been performed on the Cretaceous to Early Miocene succession of the Vrancea Nappe (Outer Carpathians, Romania), based on field reconstruction of the stratigraphic record, mineralogical-petrographic and geochemical analyses. Extra-basinal clastic supply and intra-basinal autochthonous deposits have been differentiated, appearing laterally inter-fingered and/or interbedded. The main clastic petrofacies consist of calcarenites, sub-litharenites, quartzarenites, sub-arkoses, and polygenic conglomerates derived from extra-basinal margins. An alternate internal and external provenance of the different supplies is the result of the paleogeographic re-organization of the basin/margins system due to tectonic activation and exhumation of rising areas. The intra-basinal deposits consist of black shales and siliceous sediments (silexites and cherty beds), evidencing major environmental changes in the Moldavidian Basin. Organic-matter-rich black shales were deposited during anoxic episodes related to sediment starvation and high nutrient influx due to paleogeographic isolation of the basin caused by plate drifting. The black shales display relatively high contents in sub-mature to mature, Type II lipidic organic matter (good oil and gas-prone source rocks) constituting a potentially active petroleum system. The intra-basinal siliceous sediments are related to oxic pelagic or hemipelagic environments under tectonic quiescence conditions although its increase in the Oligocene part of the succession can be correlated with volcanic supplies. The integration of all the data in the “progressive reorientation of convergence direction” Carpathian model, and their consideration in the framework of a foreland basin, led to propose some constrains on the paleogeographic-geodynamic evolutionary model of the Moldavidian Basin from the Late Cretaceous to the Burdigalian.

On Ukrainian Gas Transit and South Stream. There may be more than meets the eye. CEPS Commentaries, 21 March 2014

The EU relies to a considerable degree on imports to meet its demand for natural gas. Whereas Norwegian export pipelines are directly connected to the EU gas system, a major share of Russian gas flows through the Ukrainian territory before reaching consumers located other consumers located down in the supply chain (e.g. Slovakia, Hungary or Italy). But is the Ukrainian gas transit route still a risk? Will the construction of the South Stream pipeline further reduce the importance of Ukraine as a transit country? Or is there more at stake here than meets the eye?

The gas target model for the Visegard 4 Region: conceptual analysis. OSW Report, May 2013

The similarity of issues and geographical proximity have led the Visegrad 4 countries (V4) to undertake closer collaboration in natural gas policy, notably by agreeing on a common security of supply strategy, including regional emergency planning, and a common implementation of the Gas Target Model (GTM) that European regulators have proposed for the medium-long term design of the EU gas market, and which has been endorsed by the Madrid Regulatory Forum. As a contribution to this collaboration, the present paper will analyse how the GTM may be implemented in the V4 region, with a view to maximize the benefits that arise from joint implementation. A most relevant conclusion of the GTM is that markets should be large enough to attract market players and investments, so that sufficient diversity of sources may be reached and market power indicators are kept below dangerous levels. In most cases, this requires physical and/or virtual interconnection of present markets, which is also useful to achieve the required security of supply standards, as envisaged in the Regulation 994/2010/EC.

Energy Union: Can Europe learn from Japan’s joint gas purchasing? CEPS Commentary, 11 December 2014

Japan’s two major electricity producing companies reached a preliminary agreement recently to establish a joint venture for the procurement of fossil fuel resources, primarily liquefied natural gas (LNG). The authors of this commentary ask whether this commercial initiative could serve as an example to Europe of how to increase the negotiating power of individual EU member states. They conclude that a private joint gas procurement company may indeed offer a solution for EU member states in Central and Eastern Europe, instead of yet another source of confrontation. Given the political volatility in the region, it could well be the key to balancing out the need for security of supply with an offer to guarantee security of demand, thereby creating the climate for stable commercial relations.

Europe's LNG Strategy in the Wider EU Gas Market. CEPS Policy Brief No. 333, October 2015

In its Communication on an Energy Union published in February 2015, the European Commission committed itself to “explore the full potential of liquefied natural gas (LNG), including as a back-up in crisis situations when insufficient gas is coming into Europe through the existing pipeline system” and to address the potential of gas storage in Europe by developing a comprehensive LNG and storage strategy by the end of 2015 or early in 2016. This is a comprehensible move in the current context. Geopolitical tensions between the EU and Russia explain the EU’s willingness to further diversify its supply sources of natural gas to reinforce its long-term energy security on the one hand, and to strengthen its ability to solve future crises on the other hand. Moreover, the current market dynamics could support diversification towards LNG. Increasing the flexibility of LNG trade, decreasing LNG prices and LNG charter rates and an apparent price convergence between the European and the Asia-Pacific LNG imports would all reinforce the economic viability of such a strategy. This Policy Brief makes three main points: • For the LNG and gas storage strategy to work, it needs to be embedded in the realities of the natural gas market. • The key to a successful LNG strategy is to develop sufficient infrastructure. • The LNG strategy needs an innovation component.