Economical Analysis of Financial Supports for Large-Scale Photovoltaic PV plants in Eastern Europeen Union Countries

Today, photovoltaic (PV) attracts considerable interest among renewable energy sources (RES), because of its potential to significantly contribute to the future of clean energies. However, PV development is strongly related to the support policies introduced by national governments. The modification or fading out of such support schemes can strongly influence the development of the PV market in any given country. Although the PV market in European developing countries is still quite small, it has been growing rapidly in recent years. Until 2006, the installation of small off-grid PV plants prevailed in eastern EU countries. Starting from 2008, large-scale on-grid PV plants have been put into effect. Today on-grid installations constitute more than 95% of the total installed PV plants. The large increase of PV market in the last two years is a consequence of the enormous development of PV sector in the Czech market, stimulated by effective support mechanisms. Other developing member states, such as Slovakia and Bulgaria, have adequate PV support schemes including, in particular, effective Feed-in Tariff (FIT) systems. Other support mechanisms are tradable green certificates (TGCs), capital subsidies, tax credit and net metering. In this paper, after a brief review of national support policies in PV technology in the considered EU developing countries, the authors perform an economic analysis of the main support mechanisms that are implemented in these countries. The comparative analysis is based on the calculation of the cash flow, the Net Present Value (NPV) and the Internal Rate of Return (IRR) indices. The analysis shows that in some situations, support policies can be inconvenient for the owner of the PV system and that, in many cases, the differences between the implementation of the same support policy in different countries, can give rise to significantly different results. The comparative analysis carried out in this work could help: to evaluate the impact of the PV energy measures in eastern EU member states; to gain an insight into green energy companies by identifying potential PV markets and investigating the policy landscape across eastern EU countries

Human activity modeling and Barabasi's queueing systems

It has been shown by A.-L. Barabasi that the priority based scheduling rules in single stage queuing systems (QS) generates fat tail behavior for the tasks waiting time distributions (WTD). Such fat tails are due to the waiting times of very low priority tasks which stay unserved almost forever as the task priority indices (PI) are "frozen in time" (i.e. a task priority is assigned once for all to each incoming task). Relaxing the "frozen in time" assumption, this paper studies the new dynamic behavior expected when the priority of each incoming tasks is time-dependent (i.e. "aging mechanisms" are allowed). For two class of models, namely 1) a population type model with an age structure and 2) a QS with deadlines assigned to the incoming tasks which is operated under the "earliest-deadline-first" policy, we are able to analytically extract some relevant characteristics of the the tasks waiting time distribution. As the aging mechanism ultimately assign high priority to any long waiting tasks, fat tails in the WTD cannot find their origin in the scheduling rule alone thus showing a fundamental difference between the present and the A.-L. Barabasi's class of models.Comment: 16 pages, 2 figure

Dynamic scheduling for production systems operating in a random environment

Due to the steady tendency to propose highly customized products and to respond to volatile (i.e random) demands, Flexible Manufacturing Systems (FMS) are now present in most shopfloors. In this thesis, flexibility in a FMS is understood as the ability of a single production cell to deliver several different types of items, say N. The production capacity is usually limited in the sense that only one or K < N type(s) of items can be simultaneously produced. Each type of item faces a specific market demand which often shows random fluctuations. To insure a high reactivity when facing such random demands, efficient production rules for the FMS are mandatory. These rules include in particular two generic entities, namely: Finished Goods Inventories. The fluctuations of i) the production flows, (due to failure-prone machines) and ii) the demand flows, can be partly absorbed by the presence of Finished Good Inventories (FIG). Such storage zones incur costs especially when serving highly customized demands. Clearly, the balance between the advantage of high reactivity on the one hand and storage costs on the other introduces complex optimization issues. The optimal solution will generally include hybrid production rules, i.e. certain types of products optimally require FIG (we call this strategy make-to-stock production), while other types require no FIG (we call this strategy make-to-order production). Dynamic Scheduling rules. The intrinsic presence of fluctuations implies that simple deterministic scheduling rules (as for example deterministic polling rules which produce each type j of items periodically during a fixed period of time Tj) may lead to a very poor performance. Clearly, an optimal production schedule will be based on both past experience and observation of the present state of the system (i.e the populations of the FIG and the instantaneous rates of the demand and production flows). Hence, any optimal scheduling rule will necessarily present a time adaptive character (i.e. real time scheduling rules). In spite of a growing usage of FMS in industry, the general problem of determining the optimal dynamic scheduling of flexible manufacturing systems remains, in its full generality, an open issue of operations research. In order to give some answers to the question of optimal scheduling, the present thesis will discuss two mathematical models known as "Multi-Armed Bandit Problem" (MABP) and "Restless Bandit Problem" (RBP) in terms of which the FMS can be modeled. Let us briefly recall the salient features of the Bandit formalization. In its basic version, the MABP considers a series of N stochastic processes (also called projects) evolving in parallel. At each time t, a decision maker (DM) can engage at most one project (this feature reflects the limited resource property). The engaged project generates an instantaneous cost while the disengaged projects incur no cost and remain fixed ("frozen" dynamic rule of the disengaged projects). The optimal scheduling problem in the MABP consists in choosing at each time t which project to engage in order to minimize the global cost over a given time horizon. An exact solution of the basic MABP has been given in 1974 by Gittins. The solution is based on the construction of a set of N priority indices (the so-called Gittins indices) which assign to each project an "urgency function" in terms of which the optimal dynamic scheduling reads: "At each instant, engage the item exhibiting the smallest priority index value". To use the MABP formalization in the production engineering context, the basic hypothesis of the "frozen" dynamics needs to be loosened. It is indeed mandatory to allow for the following features: Disengaged projects evolve in time and do incur costs. This generalization is necessary to reflect the fact that demands for items not currently produced continue to accrue and their FGI obviously also incurs costs. The assumptions in a) lead us to study the so-called "Restless Bandit problems" for which the optimal scheduling rule is yet unknown. As it has been noted in the (scarce) literature available, a naive generalization of the priority indices will definitely not yield the optimal rule. However, close to optimal solutions can still be expressed in terms of suitably generalized priority indices. The use of such indices has the determining advantage of leading to very simple --though sub-optimal-- scheduling policies. This is indeed an essential feature of the production applications we have in mind. Hence, the construction of simple solvable models of optimal scheduling rules, will help to develop the perception needed to construct reliable heuristics applicable to the general problems. Accordingly, the general approach adopted in the present thesis is: Construct explicitly solvable classes of Bandit problems (Classical and Restless). Develop a heuristic to approach the problem of FMS and tests its validity on the basis of simulation studies. Moreover, as flexibility in a FMS generally generate setup penalties (such as the need for additional workforce incurring additional costs or cleaning operations imposing switching time delay) we will further: Construct an explicitly solvable class of MABP with setup penalties. Develop a heuristic to approach the general problem of MABP with setup costs and test its validity on the basis of the simple models introduced in iii). Our original contributions are: Explicit computation of the Gittins index for MABP (without switching penalties). We were able to compute explicitly the form of the Gittins indices when the evolution is given by a piecewise deterministic process which is intrinsically non-Markovian. This is among the few classes of non-Markovian examples in the literature for which the Gittins indices can be computed explicitly (M.-O. Hongler and F. Dusonchet, "Optimal stopping and Gittins indices for piecewise deterministic evolution process", Discrete Events Systems (2001) (11), 235--248). Explicit treatment of the Restless Multi-Armed Bandit process. We studied several underlying random dynamics relevant for the production engineering context, (e.g. diffusion processes as well as birth and death processes). We obtained explicit generalized priority indices and the resulting dynamic scheduling was compared with exact results derived numerically by A. Ha, (Oper. Res. 45, 1994, 42-53). Finally, using the RBP, we propose a sub-optimal heuristic solving the multi-items make-to-stock production problem (F. Dusonchet and M.-O. Hongler, "Continuous Time Restless Bandit and Dynamic Scheduling for Make-to-Stock Production", accepted for publication by IEEE Trans. on Robo. and Auto., (2003)). Construction of a sub-optimal heuristic for the MABP with setup penalties. Adding setup penalties to optimal control problems singularly increases the complexity of the solution. Therefore, very few results presently exist and the optimal decision problem with setups remains mostly unexplored. Our effort concentrates on the MABP with setup penalties and significant progress has been made by constructing a new class of MABP with setups for which the optimal policy can be explicitly constructed by recursion. Using this optimal derivation, we then propose a heuristic, approaching the optimal policy for general MABP with switching penalties (F. Dusonchet and M.-O. Hongler, "Optimal Policy for Deteriorating Two-Armed Bandit Problems with Switching Costs", accepted by Automatica, (2003))

Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function

Mitochondrial dysfunction and oxidative stress have been implicated in the etiology of Parkinson's disease. Therefore, pathways controlling mitochondrial activity rapidly emerge as potential therapeutic targets. Here, we explore the neuronal response to prolonged overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), a transcriptional regulator of mitochondrial function, both in vitro and in vivo. In neuronal primary cultures from the ventral midbrain, PGC-1α induces mitochondrial biogenesis and increases basal respiration. Over time, we observe an increasing proportion of the oxygen consumed by neurons which are dedicated to adenosine triphosphate production. In parallel to enhanced oxidative phosphorylation, PGC-1α progressively leads to a decrease in mitochondrial polarization. In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content. In addition, PGC-1α prevents the labeling of nigral neurons following striatal injection of the fluorogold retrograde tracer. When PGC-1α is expressed at higher levels following intranigral AAV injection, it leads to overt degeneration of dopaminergic neurons. Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression. Overall, we find that lasting overexpression of PGC-1α leads to major alterations in the metabolic activity of neuronal cells which dramatically impair dopaminergic function in vivo. These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activit

Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function

Mitochondrial dysfunction and oxidative stress have been implicated in the etiology of Parkinson's disease. Therefore, pathways controlling mitochondrial activity rapidly emerge as potential therapeutic targets. Here, we explore the neuronal response to prolonged overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), a transcriptional regulator of mitochondrial function, both in vitro and in vivo. In neuronal primary cultures from the ventral midbrain, PGC-1α induces mitochondrial biogenesis and increases basal respiration. Over time, we observe an increasing proportion of the oxygen consumed by neurons which are dedicated to adenosine triphosphate production. In parallel to enhanced oxidative phosphorylation, PGC-1α progressively leads to a decrease in mitochondrial polarization. In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content. In addition, PGC-1α prevents the labeling of nigral neurons following striatal injection of the fluorogold retrograde tracer. When PGC-1α is expressed at higher levels following intranigral AAV injection, it leads to overt degeneration of dopaminergic neurons. Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression. Overall, we find that lasting overexpression of PGC-1α leads to major alterations in the metabolic activity of neuronal cells which dramatically impair dopaminergic function in vivo. These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activity

Exogenous LRRK2G2019S induces parkinsonian-like pathology in a nonhuman primate

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease among the elderly. To understand pathogenesis and to test therapies, animal models that faithfully reproduce key pathological PD hallmarks are needed. As a prelude to developing a model of PD, we tested the tropism, efficacy, biodistribution, and transcriptional impact of canine adenovirus type 2 (CAV-2) vectors in the brain of Microcebus murinus, a nonhuman primate that naturally develops neurodegenerative lesions. We show that introducing helper-dependent (HD) CAV-2 vectors results in long-term, neuron-specific expression at the injection site and in afferent nuclei. Although HD CAV-2 vector injection induced a modest transcriptional response, no significant adaptive immune response was generated. We then generated and tested HD CAV-2 vectors expressing LRRK2 (leucine-rich repeat kinase 2) and LRRK2 carrying a G2019S mutation (LRRK2G2019S), which is linked to sporadic and familial autosomal dominant forms of PD. We show that HD-LRRK2G2019S expression induced parkinsonian-like motor symptoms and histological features in less than 4 months

The feed-in tariff in the UK : a case study focus on domestic photovoltaic systems

This paper explores the photovoltaic (PV) industry in the United Kingdom (UK) as experienced by those who are working with it directly and with consideration of current standards, module efficiencies and future environmental trends. The government's consultation on the comprehensive review for solar PV tariffs, proposes a reduction of the generation tariff for PV installations in the UK of more than 50%. The introduction of the Feed-In Tariffs scheme (FITs) has rapidly increased deployment of PV technologies at small scale since its introduction in April 2010. The central principle of FIT policies is to offer guaranteed prices for fixed periods to enable greater number of investors. A financial analysis was performed on two real-life installations in Cornwall, UK to determine the impact of proposed cuts to the FIT will make to a typical domestic PV system under 4 kW. The results show that a healthy Return on Investment (ROI) can still be made but that future installations should focus on off-setting electricity required from the national grid as a long term push for true sustainability rather than subsidised schemes. The profitability of future installations will have to be featured within in-service and end-of-service considerations such as the feed-in tariff, module efficiencies and the implications of costs associated with end-of-life disposal