Simulating potential growth and yield of oil palm (Elaeis guineensis) with PALMSIM: Model description, evaluation and application.

Reducing the gap between water-limited potential yield and actual yield in oil palm production systems through intensification is seen as an important option for sustainably increasing palm oil production. Simulation models can play an important role in quantifying water-limited potential yield, and therefore the scope for intensification, but no oil palm model exists that is both simple enough and at the same time incorporates sufficient plant physiological knowledge to be generally applicable across sites with different growing conditions. The objectives of this study therefore were to develop a model (PALMSIM) that simulates, on a monthly time step, the potential growth of oil palm as determined by solar radiation and to evaluate model performance against measured oil palm yields under optimal water and nutrient management for a range of sites across Indonesia and Malaysia. The maximum observed yield in the field matches the corresponding simulated yield for dry bunch weight with a RMSE of 1.7 Mg ha?1 year?1 against an observed yield of 18.8 Mg ha?1. Sensitivity analysis showed that PALMSIM is robust: simulated changes in yield caused by modifying the parameters by 10% are comparable to other tree crop model evaluations. While we acknowledge that, depending on the soils and climatic environment, yields may be often water limited, we suggest a relatively simple physiological approach to simulate potential yield, which can be usefully applied to high rainfall environments and is considered as a first step in developing an oil palm model that also simulates water-limited potential yield. To illustrate the application possibil- ities of the model, PALMSIM was used to create a potential yield map for Indonesia and Malaysia by sim- ulating the growth and yield at a resolution of 0.1?. This map of potential yield is considered as a first step towards a decision support tool that can identify potentially productive, but at the moment degraded sites in Indonesia and Malaysia. ?

Bare-tape scaling laws for de-orbit missions in a space debris environment

El entorno espacial actual hay un gran numero de micro-meteoritos y basura espacial generada por el hombre, lo cual plantea un riesgo para la seguridad de las operaciones en el espacio. La situación se agrava continuamente a causa de las colisiones de basura espacial en órbita, y los nuevos lanzamientos de satélites. Una parte significativa de esta basura son satélites muertos, y fragmentos de satélites resultantes de explosiones y colisiones de objetos en órbita. La mitigación de este problema se ha convertido en un tema de preocupación prioritario para todas las instituciones que participan en operaciones espaciales. Entre las soluciones existentes, las amarras electrodinámicas (EDT) proporcionan un eficiente dispositivo para el rápido de-orbitado de los satélites en órbita terrestre baja (LEO), al final de su vida útil. El campo de investigación de las amarras electrodinámicas (EDT) ha sido muy fructífero desde los años 70. Gracias a estudios teóricos, y a misiones para la demostración del funcionamiento de las amarras en órbita, esta tecnología se ha desarrollado muy rápidamente en las últimas décadas. Durante este período de investigación, se han identificado y superado múltiples problemas técnicos de diversa índole. Gran parte del funcionamiento básico del sistema EDT depende de su capacidad de supervivencia ante los micro-meteoritos y la basura espacial. Una amarra puede ser cortada completamente por una partícula cuando ésta tiene un diámetro mínimo. En caso de corte debido al impacto de partículas, una amarra en sí misma, podría ser un riesgo para otros satélites en funcionamiento. Por desgracia, tras varias demostraciones en órbita, no se ha podido concluir que este problema sea importante para el funcionamiento del sistema. En esta tesis, se presenta un análisis teórico de la capacidad de supervivencia de las amarras en el espacio. Este estudio demuestra las ventajas de las amarras de sección rectangular (cinta), en cuanto a la probabilidad de supervivencia durante la misión, frente a las amarras convencionales (cables de sección circular). Debido a su particular geometría (longitud mucho mayor que la sección transversal), una amarra puede tener un riesgo relativamente alto de ser cortado por un único impacto con una partícula de pequeñas dimensiones. Un cálculo analítico de la tasa de impactos fatales para una amarra cilindrica y de tipo cinta de igual longitud y masa, considerando el flujo de partículas de basura espacial del modelo ORDEM2000 de la NASA, muestra mayor probabilidad de supervivencia para las cintas. Dicho análisis ha sido comparado con un cálculo numérico empleando los modelos de flujo el ORDEM2000 y el MASTER2005 de ESA. Además se muestra que, para igual tiempo en órbita, una cinta tiene una probabilidad de supervivencia un orden y medio de magnitud mayor que una amarra cilindrica con igual masa y longitud. Por otra parte, de-orbitar una cinta desde una cierta altitud, es mucho más rápido, debido a su mayor perímetro que le permite capturar más corriente. Este es un factor adicional que incrementa la probabilidad de supervivencia de la cinta, al estar menos tiempo expuesta a los posibles impactos de basura espacial. Por este motivo, se puede afirmar finalmente y en sentido práctico, que la capacidad de supervivencia de la cinta es bastante alta, en comparación con la de la amarra cilindrica. El segundo objetivo de este trabajo, consiste en la elaboración de un modelo analítico, mejorando la aproximación del flujo de ORDEM2000 y MASTER2009, que permite calcular con precisión, la tasa de impacto fatal al año para una cinta en un rango de altitudes e inclinaciones, en lugar de unas condiciones particulares. Se obtiene el numero de corte por un cierto tiempo en función de la geometría de la cinta y propiedades de la órbita. Para las mismas condiciones, el modelo analítico, se compara con los resultados obtenidos del análisis numérico. Este modelo escalable ha sido esencial para la optimización del diseño de la amarra para las misiones de de-orbitado de los satélites, variando la masa del satélite y la altitud inicial de la órbita. El modelo de supervivencia se ha utilizado para construir una función objetivo con el fin de optimizar el diseño de amarras. La función objectivo es el producto del cociente entre la masa de la amarra y la del satélite y el numero de corte por un cierto tiempo. Combinando el modelo de supervivencia con una ecuación dinámica de la amarra donde aparece la fuerza de Lorentz, se elimina el tiempo y se escribe la función objetivo como función de la geometría de la cinta y las propietades de la órbita. Este modelo de optimización, condujo al desarrollo de un software, que esta en proceso de registro por parte de la UPM. La etapa final de este estudio, consiste en la estimación del número de impactos fatales, en una cinta, utilizando por primera vez una ecuación de límite balístico experimental. Esta ecuación ha sido desarollada para cintas, y permite representar los efectos tanto de la velocidad de impacto como el ángulo de impacto. Los resultados obtenidos demuestran que la cinta es altamente resistente a los impactos de basura espacial, y para una cinta con una sección transversal definida, el número de impactos críticos debidos a partículas no rastreables es significativamente menor. ABSTRACT The current space environment, consisting of man-made debris and tiny meteoroids, poses a risk to safe operations in space, and the situation is continuously deteriorating due to in-orbit debris collisions and to new satellite launches. Among these debris a significant portion is due to dead satellites and fragments of satellites resulted from explosions and in-orbit collisions. Mitigation of space debris has become an issue of first concern for all the institutions involved in space operations. Bare electrodynamic tethers (EDT) can provide an efficient mechanism for rapid de-orbiting of defunct satellites from low Earth orbit (LEO) at end of life. The research on EDT has been a fruitful field since the 70’s. Thanks to both theoretical studies and in orbit demonstration missions, this technology has been developed very fast in the following decades. During this period, several technical issues were identified and overcome. The core functionality of EDT system greatly depends on their survivability to the micrometeoroids and orbital debris, and a tether can become itself a kind of debris for other operating satellites in case of cutoff due to particle impact; however, this very issue is still inconclusive and conflicting after having a number of space demonstrations. A tether can be completely cut by debris having some minimal diameter. This thesis presents a theoretical analysis of the survivability of tethers in space. The study demonstrates the advantages of tape tethers over conventional round wires particularly on the survivability during the mission. Because of its particular geometry (length very much larger than cross-sectional dimensions), a tether may have a relatively high risk of being severed by the single impact of small debris. As a first approach to the problem, survival probability has been compared for a round and a tape tether of equal mass and length. The rates of fatal impact of orbital debris on round and tape tether, evaluated with an analytical approximation to debris flux modeled by NASA’s ORDEM2000, shows much higher survival probability for tapes. A comparative numerical analysis using debris flux model ORDEM2000 and ESA’s MASTER2005 shows good agreement with the analytical result. It also shows that, for a given time in orbit, a tape has a probability of survival of about one and a half orders of magnitude higher than a round tether of equal mass and length. Because de-orbiting from a given altitude is much faster for the tape due to its larger perimeter, its probability of survival in a practical sense is quite high. As the next step, an analytical model derived in this work allows to calculate accurately the fatal impact rate per year for a tape tether. The model uses power laws for debris-size ranges, in both ORDEM2000 and MASTER2009 debris flux models, to calculate tape tether survivability at different LEO altitudes. The analytical model, which depends on tape dimensions (width, thickness) and orbital parameters (inclinations, altitudes) is then compared with fully numerical results for different orbit inclinations, altitudes and tape width for both ORDEM2000 and MASTER2009 flux data. This scalable model not only estimates the fatal impact count but has proved essential in optimizing tether design for satellite de-orbit missions varying satellite mass and initial orbital altitude and inclination. Within the frame of this dissertation, a simple analysis has been finally presented, showing the scalable property of tape tether, thanks to the survivability model developed, that allows analyze and compare de-orbit performance for a large range of satellite mass and orbit properties. The work explicitly shows the product of tether-to-satellite mass-ratio and fatal impact count as a function of tether geometry and orbital parameters. Combining the tether dynamic equation involving Lorentz drag with space debris impact survivability model, eliminates time from the expression. Hence the product, is independent of tether de-orbit history and just depends on mission constraints and tether length, width and thickness. This optimization model finally led to the development of a friendly software tool named BETsMA, currently in process of registration by UPM. For the final step, an estimation of fatal impact rate on a tape tether has been done, using for the first time an experimental ballistic limit equation that was derived for tapes and accounts for the effects of both the impact velocity and impact angle. It is shown that tape tethers are highly resistant to space debris impacts and considering a tape tether with a defined cross section, the number of critical events due to impact with non-trackable debris is always significantly low.

Environmental analysis of a Concentrated Solar Power (CSP) plant hybridised with different fossil and renewable fuels

The environmental performance of a 50 MW parabolic trough Concentrated Solar Power (CSP) plant hybridised with different fuels was determined using a Life Cycle Assessment methodology. Six different scenarios were investigated, half of which involved hybridisation with fossil fuels (natural gas, coal and fuel oil), and the other three involved hybridisation with renewable fuels (wheat straw, wood pellets and biogas). Each scenario was compared to a solar-only operation. Nine different environmental categories as well as the Cumulative Energy Demand and the Energy Payback Time (EPT) were evaluated using Simapro software for 1 MWh of electricity produced. The results indicate a worse environmental performance for a CSP plant producing 12% of the electricity from fuel than in a solar-only operation for every indicator, except for the eutrophication and toxicity categories, whose results for the natural gas scenario are slightly better. In the climate change category, the results ranged between 26.9 and 187 kg CO2 eq/MWh, where a solar-only operation had the best results and coal hybridisation had the worst. Considering a weighted single score indicator, the environmental impact of the renewable fuels scenarios is approximately half of those considered in fossil fuels, with the straw scenario showing the best results, and the coal scenario the worstones. EPT for solar-only mode is 1.44 years, while hybridisation scenarios EPT vary in a range of 1.72 -1.83 years for straw and pellets respectively. The fuels with more embodied energy are biomethane and wood pellets.

Analysis and optimization of trajectories for Ballistic Missiles Interception

Intercontinental Ballistic Missiles are capable of placing a nuclear warhead at more than 5,000 km away from its launching base. With the lethal power of a nuclear warhead a whole city could be wiped out by a single weapon causing millions of deaths. This means that the threat posed to any country from a single ICBM captured by a terrorist group or launched by a 'rogue' state is huge. This threat is increasing as more countries are achieving nuclear and advanced launcher capabilities. In order to suppress or at least reduce this threat the United States created the National Missile Defense System which involved, among other systems, the development of long-range interceptors whose aim is to destroy incoming ballistic missiles in their midcourse phase. The Ballistic Missile Defense is a high-profile topic that has been the focus of political controversy lately when the U.S. decided to expand the Ballistic Missile system to Europe, with the opposition of Russia. However the technical characteristics of this system are mostly unknown by the general public. The Interception of an ICBM using a long range Interceptor Missile as intended within the Ground-Based Missile Defense System by the American National Missile Defense (NMD) implies a series of problems of incredible complexity: - The incoming missile has to be detected almost immediately after launch. - The incoming missile has to be tracked along its trajectory with a great accuracy. - The Interceptor Missile has to implement a fast and accurate guidance algorithm in order to reach the incoming missile as soon as possible. - The Kinetic Kill Vehicle deployed by the interceptor boost vehicle has to be able to detect the reentry vehicle once it has been deployed by ICBM, when it offers a very low infrared signature, in order to perform a final rendezvous manoeuvre. - The Kinetic Kill Vehicle has to be able to discriminate the reentry vehicle from the surrounding debris and decoys. - The Kinetic Kill Vehicle has to be able to implement an accurate guidance algorithm in order to perform a kinetic interception (direct collision) of the reentry vehicle, at relative speeds of more than 10 km/s. All these problems are being dealt simultaneously by the Ground-Based Missile Defense System that is developing very complex and expensive sensors, communications and control centers and long-range interceptors (Ground-Based Interceptor Missile) including a Kinetic Kill Vehicle. Among all the technical challenges involved in this interception scenario, this thesis focuses on the algorithms required for the guidance of the Interceptor Missile and the Kinetic Kill Vehicle in order to perform the direct collision with the ICBM. The involved guidance algorithms are deeply analysed in this thesis in part III where conventional guidance strategies are reviewed and optimal guidance algorithms are developed for this interception problem. The generation of a realistic simulation of the interception scenario between an ICBM and a Ground Based Interceptor designed to destroy it was considered as necessary in order to be able to compare different guidance strategies with meaningful results. As a consequence, a highly representative simulator for an ICBM and a Kill Vehicle has been implemented, as detailed in part II, and the generation of these simulators has also become one of the purposes of this thesis. In summary, the main purposes of this thesis are: - To develop a highly representative simulator of an interception scenario between an ICBM and a Kill Vehicle launched from a Ground Based Interceptor. -To analyse the main existing guidance algorithms both for the ascent phase and the terminal phase of the missiles. Novel conclusions of these analyses are obtained. - To develop original optimal guidance algorithms for the interception problem. - To compare the results obtained using the different guidance strategies, assess the behaviour of the optimal guidance algorithms, and analyse the feasibility of the Ballistic Missile Defense system in terms of guidance (part IV). As a secondary objective, a general overview of the state of the art in terms of ballistic missiles and anti-ballistic missile defence is provided (part I).

Metabolic engineering of essential oil yield and composition in mint by altering expression of deoxyxylulose phosphate reductoisomerase and menthofuran synthase

Peppermint (Mentha × piperita L.) was independently transformed with a homologous sense version of the 1-deoxy-d-xylulose-5-phosphate reductoisomerase cDNA and with a homologous antisense version of the menthofuran synthase cDNA, both driven by the CaMV 35S promoter. Two groups of transgenic plants were regenerated in the reductoisomerase experiments, one of which remained normal in appearance and development; another was deficient in chlorophyll production and grew slowly. Transgenic plants of normal appearance and growth habit expressed the reductoisomerase transgene strongly and constitutively, as determined by RNA blot analysis and direct enzyme assay, and these plants accumulated substantially more essential oil (about 50% yield increase) without change in monoterpene composition compared with wild-type. Chlorophyll-deficient plants did not afford detectable reductoisomerase mRNA or enzyme activity and yielded less essential oil than did wild-type plants, indicating cosuppression of the reductoisomerase gene. Plants transformed with the antisense version of the menthofuran synthase cDNA were normal in appearance but produced less than half of this undesirable monoterpene oil component than did wild-type mint grown under unstressed or stressed conditions. These experiments demonstrate that essential oil quantity and quality can be regulated by metabolic engineering. Thus, alteration of the committed step of the mevalonate-independent pathway for supply of terpenoid precursors improves flux through the pathway that leads to increased monoterpene production, and antisense manipulation of a selected downstream monoterpene biosynthetic step leads to improved oil composition.

Modelling and testing volatility spillovers in oil and financial markets for USA, UK and China

The primary purpose of the paper is to analyze the conditional correlations, conditional covariances, and co-volatility spillovers between international crude oil and associated financial markets. The paper investigates co-volatility spillovers (namely, the delayed effect of a returns shock in one physical or financial asset on the subsequent volatility or co-volatility in another physical or financial asset) between the oil and financial markets. The oil industry has four major regions, namely North Sea, USA, Middle East, and South-East Asia. Associated with these regions are two major financial centers, namely UK and USA. For these reasons, the data to be used are the returns on alternative crude oil markets, returns on crude oil derivatives, specifically futures, and stock index returns in UK and USA. The paper will also analyze the Chinese financial markets, where the data are more recent. The empirical analysis will be based on the diagonal BEKK model, from which the conditional covariances will be used for testing co-volatility spillovers, and policy recommendations. Based on these results, dynamic hedging strategies will be suggested to analyze market fluctuations in crude oil prices and associated financial markets.

Thermogravimetric monitoring of oil refinery sludge

The present work has two dimensions: analytical and environmental. On the one hand we proved that thermogravimetric analysis can be used to perform fast characterization of oil refinery sludge. To this end, thermogravimetric curves were deconvoluted by using autocatalytic kinetics to take into account acceleratory phases in a thermal degradation performed in oxygen-containing atmosphere or at high heating rates. Based on thermogravimetric results, oil refinery sludge was modeled in terms of various fractions (pseudo-components) which degrade as major oil cuts. On the other hand, as an alternative to landfill, we have seen that Soxhlet extraction allows recovery almost half of the weight of sludge as a mixture of hydrocarbons, similar to gas–oil, which burns without residue. This ensures both, waste inerting and significant reduction in sludge volume.

Refinery Nonconventional Feedstocks: Influence of the Coprocessing of Vacuum Gas Oil and Low Density Polyethylene in Fluid Catalytic Cracking Unit on Full Range Gasoline Composition

Gasoline coming from refinery fluid catalytic cracking (FCC) unit is a major contributor to the total commercial grade gasoline pool. The contents of the FCC gasoline are primarily paraffins, naphthenes, olefins, aromatics, and undesirables such as sulfur and sulfur containing compounds in low quantities. The proportions of these components in the FCC gasoline invariable determine its quality as well as the performance of the associated downstream units. The increasing demand for cleaner and lighter fuels significantly influences the need not only for novel processing technologies but also for alternative refinery and petrochemical feedstocks. Current and future clean gasoline requirements include increased isoparaffins contents, reduced olefin contents, reduced aromatics, reduced benzene, and reduced sulfur contents. The present study is aimed at investigating the effect of processing an unconventional refinery feedstock, composed of blend of vacuum gas oil (VGO) and low density polyethylene (LDPE) on FCC full range gasoline yields and compositional spectrum including its paraffins, isoparaffins, olefins, napthenes, and aromatics contents distribution within a range of operating variables of temperature (500–700 °C) and catalyst-feed oil ratio (CFR 5–10) using spent equilibrium FCC Y-zeolite based catalyst in a FCC pilot plant operated at the University of Alicante’s Research Institute of Chemical Process Engineering (RICPE). The coprocessing of the oil-polymer blend led to the production of gasoline with very similar yields and compositions as those obtained from the base oil, albeit, in some cases, the contribution of the feed polymer content as well as the processing variables on the gasoline compositional spectrum were appreciated. Carbon content analysis showed a higher fraction of the C9–C12 compounds at all catalyst rates employed and for both feedstocks. The gasoline’s paraffinicity, olefinicity, and degrees of branching of the paraffins and olefins were also affected in various degrees by the scale of operating severity. In the majority of the cases, the gasoline aromatics tended toward the decrease as the reactor temperature was increased. While the paraffins and iso-paraffins gasoline contents were relatively stable at around 5 % wt, the olefin contents on the other hand generally increased with increase in the FCC reactor temperature.

Conversion of low density polyethylene into fuel through co-processing with vacuum gas oil in a fluid catalytic cracking riser reactor

In this work, mixtures of vacuum gas oil and low density polyethylene, a major component of common industrial and consumer household plastics, were pyrolytically co-processed in a fluid catalytic cracking (FCC) riser reactor as a viable alternative for the energy and petrochemical revalorisation of plastic wastes into valuable petrochemical feedstocks and fuel within an existing industrial technology. Using equilibrium FCC catalyst, the oil–polymer blends were catalytically cracked at different processing conditions of temperatures between 773 K and 973 K and catalyst feed ratios of 5:1, 7:1 and 10:1. The influence of each of these processing parameters on the cracking gas and liquid yield patterns were studied and presented. Further analysed and presented are the different compositional distributions of the obtained liquids and gaseous products. The analysis of the results obtained revealed that with very little modifications to existing process superstructure, yields and compositional distributions of products from the fluid catalytic cracking of the oil–polymer blend in many cases were very similar to those of the processed oil feedstock, bringing to manifest the viability of the feedstock co-processing without significant detriments to FCC product yields and quality.

Analysis of Hyporheic Flow Induced by a Bar in a Gravel Stream: an Experimental Study

Thesis (Master, Civil Engineering) -- Queen's University, 2016-06-01 00:03:02.939

The Price of Oil and Soviet/Russian Aggressiveness. CEPS Commentary, 16 January 2015

A decade-long period of a steadily rising oil prices (and that of other raw materials) has given Russia a feeling of strength, bordering on invulnerability, which has made the country more assertive, and ready to use any opportunity to deploy its military power. Based on his analysis of Russian behaviour over the past 50 years, Daniel Gros finds that the abrupt reversal of this trend since the summer of 2014 portends a much less aggressive Russian stance as long as the price of oil remains at present levels.

Total organic carbon, delta13C, biomarker, gas compilations and hopanoids analysis from IODP Sites 307-U1317 and 307-U1318

During the Integrated Ocean Drilling Program (IODP) Expedition 307 for the first time a cold-water coral carbonate mound was drilled down through its base into the underlying sediments. In the current study, sample material from within and below Challenger Mound, located in the Belgica carbonate mound province in the Porcupine Basin offshore Ireland, was investigated for its distribution of microbial communities and gas composition using biogeochemical and geochemical approaches to elucidate the question on the initiation of carbonate mounds. Past and living microbial populations are lower in the mound section compared to the underlying sediments or sediments of an upslope reference site. A reason for this might be a reduced substrate feedstock, reflected by low total organic carbon (TOC) contents, in the once coral dominated mound sequence. In contrast, in the reference site a lithostratigraphic sequence with comparatively high TOC contents shows higher abundances of both past and present microbial communities, indicating favourable living conditions from time of sedimentation until today. Composition and isotopic values of gases below the mound base seem to point to a mixed gas of biogenic and thermogenic origin with a higher proportion of biogenic gas. Oil-derived hydrocarbons were not detected at the mound site. This suggests that at least in the investigated part of the mound base the upward flow of fossil hydrocarbons, being one hypothesis for the initiation of the formation of carbonate mounds, seems to be only of minor significance.

(Table T1) Ice rafted debris characteristics of ODP Site 177-1092

We have carried out a multiphase analysis of samples from ODP Site 177-1092, Meteor Rise, subantarctic South Atlantic. Samples were analyzed for ice-rafted debris (IRD [see Table T1]) and stable isotopes from benthic foraminifera [see Murphy et al., 2002, doi:10.1016/S0031-0182(01)00495-3]. Both analyses were performed on the same samples. Additional work was performed to identify the paleomagnetic stratigraphy. The analyzed samples range in age from about 2.6(?) Ma to 4.6 Ma, a time span that saw considerable global warmth, but witnessed overall global refrigeration and the transition to truly bipolar glaciations. IRD arrived frequently during the Early and early Late Pliocene, but only as 'background rafting' (occasional grains per sample). The first identifiable IRD above background rafting is associated with marine isotope stage (MIS) KM4 (~3.18 Ma). Successive IRD peaks become larger, the same pattern as noted at nearby Site 114-704. A very large peak near the top of the record, approximately 2.8 Ma, is considered to represent a hiatus. Peaks below 51.3 meters composite depth (mcd) coincide with positive excursions of the oxygen isotopic record, and with negative excursions of the carbon isotopic curve, a pattern also noted at Site 114-704. However, the reasonably large IRD peak at 51 mcd (tentatively identified with MIS G11) coincides with a positive excursion on the carbon isotopic curve and negative excursion on the oxygen isotopic curve. This relationship suggests a northern hemisphere interglacial, rising sea level, destabilization of the Antarctic margin, and delivery of Antarctic icebergs to the Southern Ocean. Such a mechanism has recently been suggested by Kanfoush et al. (2000, doi:10.1126/science.288.5472.1815) for latest Pleistocene stadial/interstadial oscillations. Here we suggest that such a mechanism may have been in place on glacial/interglacial time scales as early as the Late Pliocene.