70 research outputs found
Predictive maintenance for utility scale solar parks: A machine learning approach towards early fault detection for PV inverters
No full textThe growing demand and improvements in manufacturing capabilities, supported by government subsidies, has allowed the increase in the installed capacity of utility scale solar parks. Due to the remoteness in their location, the costs associated with dispatching personnel for maintenance is extremely high. A major contribution towards unscheduled downtime of these plants is due to the inverter faults. Currently, reactive and preventive maintenance are the most prevailing methods to identify and fix inverter faults. The presumption that the components will not under-performor fail until the scheduled visit, leads to a significant loss of production and revenue. To deal with the disadvantages of current maintenance methods, the solar industry is very keen on understanding the possibility of early detection of inverter faults by implementation of predictive maintenance. This research assessed the applicability of Machine Learning (ML) towards early signal detection of inverter faults in order to generate predictive maintenance alerts. The data for building the ML algorithms was acquired from a Shell owned 26.6 MWp utility scale solar park located in Moerdijk, The Netherlands. The early signal detection algorithmdeveloped, was based on the comparison between the actual and the predicted active power. The model built to predict the active power was based on two supervised learning methods;Elastic Net and Gradient BoostingMachine (GBM) with quantile regression. These models were capable of predicting the active power with a Mean Absolute Error (MAE) of 0.98kW & Root Mean Square Error (RMSE) of 1.8kW using Global Plane of Array irradiance (GPOA) and module temperaturemeasurements available from theMoerdijk data. The early signal detection relied on differentiating between prediction error and actual error. A window was created to encompass the maximum extent of prediction errors to avoid any false positive signals. This window for elastic net was found to be ¡¾ on the lower side and 2¾ on the upper side. Although when elastic net method was tested on 337 inverters- by looking at their residual variation 1-week prior to registered fault- it was found that the predictions suffered a periodic structural error. This was due to the erroneous predictions at times with extreme irradiance values. To mitigate, this the GBM with quantiles of 0.01 and 0.99 of GPOA was built to create a range of predictions giving rise to a wider range for normal operation. The results from both the algorithms indicated no early signals for inverter fault detection. This was partly due to data quality issues with fault tags in the Supervisory Control and Data Acquisition (SCADA) monitoring system; only 7 actual fault cases were identified. Additionally, the economic feasibility of implementing predictive maintenance was found to potentially reduce the current Operational Expenses (OPeX) by up to 10%. Despite the issues with data quality, an approach of using ML towards early fault detection for inverters in utility scale solar parks has been realised through this research
Vers la fin de l'exception indienne
No full textThe Aggiornamento of the Indian Policy, by Jean Alphonse Bernard
The simultaneous occurence — in 1990 — of a fiscal crisis and of the collapse of the Soviet Empire laid bare the financial, économie and diplomatie weaknesses of the Indian way of governing. In this article, the author expounds the three normalizations which have taken place since then in the economy, the diplomacy and society at large. Such a wide-ranging aggiornamento raises as many issues as it solves. With a Congress Party much weakened by its electoral defeats, the ruling partnership of P.V.N. Rao and Manmohan Singh stands exposed and the reform process stalle d for the time being. The next issue may well be, besides the pace of economie liberalisation, the future balance of power between the Center and the States.La crise qui a secoué le pays en 1990-1991, a sonné l'heure de vérité pour les gouvernants de l'Inde. L'auteur expose comment l'occasion a été brillamment utilisée par le tandem P.V.N. Rao-Manmohan Singh pour normaliser le " modèle " indien dans un sens conforme à l'esprit du temps. Néanmoins, l'ag-giornarnento n'a pas été sans susciter des oppositions diverses qui ont fait perdre au parti du Congrès — jusqu'alors dominant — ses positions électorales dans de nombreux Etats. L'échéance des élections législatives de 1996, si elle devait confirmer l'effacement du parti au pouvoir, constituerait une épreuve non seulement pour les réformes économiques, mais aussi pour l'avenir du fédéralisme indien.
.Bernard. Vers la fin de l'exception indienne. In: Politique étrangère, n°4 - 1995 - 60ᵉannée. pp. 993-1001
Three essays on secondary market debt prices
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Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionThe Introductory chapter briefly describes the unintended emergence of the seconday market for developing country loans after protracted and unsuccessful negotiations between lending bankers and the indebted countries. The innovative Brady plan presented the banks involved in this market with several options for the exercise of their interests. These economic developments constitute a unique area of study open to continued anaysis because of the paucity of existing work.Chapter 1, examines the determinants of Brady bond prices or prices of the consolidated par bond debt once a country finalizes a Brady agreement. The results show that liquidity variables like debt service/exports and reserve/imports are significant in the 1990s contrary to earlier studies in the 1980s (Boehmer & Megginson '90). It is also found that the fraction of private debt to total debt adversely affects the secondary market prices for Brady bonds. The study also uses the censored regression procedure (Heckman '76) to include non-Brady countries in the sample. The significant differences in the results upon analysis of the two samples reflects the credible future policy undertaken by the Brady countries.Chapter 2 is in two parts. Part 1 explores a new way to look at the secondary debt market price of non performing debt. Panama, Peru, Ecuador, Bulgaria and Poland's debt prices were being traded as junk debt. Unlike in countries that have adopted the Brady plan, in these countries economic fundamentals do not explain the movement of debt prices. This was confirmed by the results of the Seemingly Unrelated Regression estimates (SURE). Part 2 of this chapter is an application to the anomalous secondary market price of Poland after its Brady agreement. An analytical model following Froot (1989) is used to explain the decline in Poland's debt price. The increasing role of traders as found in Part 1 is apparent in Poland's case as is an asymmetry of interests between the traders and the bankers.Chapter 3 is on the foreign debt and secondary market price of Hungary. A case is made for debt relief for Hungary following Krugman's (1988) debt relief Laffer curve model. Shadow prices were constructed for Hungary's secondary market debt prices following inconsistency of such data on Hungary. Although Hungary was found to be on the wrong side of the laffer curve, the composition of debt is largely bonds historical the last debt instrument a country wants to default upon.Made available in DSpace on 2011-05-07T13:34:50Z (GMT). No. of bitstreams: 2
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What macroeconomic policies are"sound?"
No full textMost people agree that the soundness of macroeconomic policies should be judged by their efficacy in meeting the objectives of steady growth, full employment, stable prices, and a viable external payments situation. What people debate about are the links between macroeconomics and economic structure--and in the current environment, the openness to foreign capital flows. As developing countries become more integrated into international financial markets, volatility may become an increasing fact of life. Faced with such volatility, how should these countries frame their macroeconomic policies? What broad principles should guide their macroeconomic management? In many developing countries, the openness of the capital account has been significant. Many countries have made the transition toward an open-economic paradigm. As a result, fluctuations in international capital and currency markets, as well as shifts in foreign investors'attitudes and confidence, have greatly affected local stock market prices, the level of foreign exchange reserves, and the scope for monetary and interest rate policy. Capital controls and foreign exchange restrictions have been significantly dismantled in a number of developing and transition economies. In 1970, only 34 countries--or 30 percent of the International Monetary Fund's membership-had assumed Article VIII of the IMF Articles of Agreement, declaring their currency convertible on current account transactions. By 1997, this figure had increased to 77 percent. Does financial integration make it more difficult to achieve macroeconomic stability? Apparently not, on the whole, although at times large short-term capital flows can lead to misaligned asset prices, including exchange rates. What financial integration does do is limit how far countries can pursue policies incompatible with medium-term financial stability. The disciplining effect of global financial and product markets applies not only to policymakers-through pressures on financial markets-but also to the private sector. Rather than constrain the pursuit of appropriate policies, globalization may add leverage and flexibility to such policies, easing financing constraints and extending the time during which countries can make adjustments. But markets will provide this leeway only if they perceive that countries are undertaking adjustments that address fundamental choices.Economic Theory&Research,Fiscal&Monetary Policy,Payment Systems&Infrastructure,Banks&Banking Reform,Environmental Economics&Policies,Banks&Banking Reform,Environmental Economics&Policies,Financial Intermediation,Economic Theory&Research,Macroeconomic Management
Early Ambulation in Pelvic Surgery for Cancer Leads to Fast Recovery—A Single Institute Studies
No full textObjective: Early ambulation leads to a fast recovery and reduces the incidence of postoperative complications. This study is carried out to evaluate the role of early ambulation in pelvic surgery patients. Material and Methods: In this study, total of fifty patients who have undergone pelvic surgery were included. Early ambulation within 24 hours was encouraged. Twenty patients were taken as controls in which early ambulation was not done due to patient resistance. The parameters to be studied were the duration of hospital stay, the time required for enteral feeding, respiratory complications, and generalized well-being. These parameters were evaluated in both groups. Results: The hospital stay was shortened and complications were less among patients who ambulated early. The stay was prolonged to 8 days in control patients. Conclusion: Early ambulation leads to fast recovery. It is safe, cost-effective and should be practiced by every surgeon
The involvement of surface sugars of mammalian spermatozoa in epididymal maturation and in vitro sperm-zona recognition: Die Beteiligung von Oberflächen-Zuckern von Säuger-Spermatozoen auf die Nebenhodenreifung und die in vitro Spermatozoen-Zona-Erkennung
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Rehypothecation
No full textHow would you feel if even though you were making regular monthly payments, your mortgage bank sold your house? This may seem like an odd question, but this type of situation happens every day in financial markets in a practice known as rehypothecation. Although such practices may be hard for nontraders to understand, rehypothecation is widespread in financial markets. Following the crisis of 2007-2009, the Dodd-Frank Act put restrictions on rehypothecation for derivatives. To understand the scope of these restrictions, we need to understand the role of rehypothecation in financial trades. In this article, Cyril Monnet discusses questions such as: Which party to a financial trade does rehypothecation benefit? Are there limits to its advantages? And how should it be regulated? There are no hard and fast answers to the last question, but the author notes that we can make a more informed decision about the pros and cons of various forms of regulation if we understand the underlying economics.Financial markets ; Financial Regulatory Reform (Dodd-Frank Act)
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