Lessons from the submission and approval process of energy-efficiency CDM baseline and monitoring methodologies

Energy efficiency is a CDM project type that suffers from high methodology rejection rates. 43 baseline and monitoring methodologies for CDM energy efficiency projects are analyzed with respect to reasons for approval / rejection by the CDM Executive Board. Most methodologies have been rejected because they did not comply with implicit quality standards regarding presentation and conservativeness. Also, tools to select the baseline scenario and to prove additionality were frequently lacking. If the level or the quality of production in the baseline or the project scenario changes, a simple before-after-comparison is not valid. Black box models are not accepted and methodologies should be sufficiently differentiated to account for specific (technical) circumstances. The remaining lifetime of equipment has to be taken into account. Often, elements of small-scale methodologies have been retained in approvals of large-scale methodologies. --

Linear Precoding Based on Polynomial Expansion: Large-Scale Multi-Cell MIMO Systems

Large-scale MIMO systems can yield a substantial improvement in spectral efficiency for future communication systems. Due to the finer spatial resolution achieved by a huge number of antennas at the base stations, these systems have shown to be robust to inter-user interference and the use of linear precoding is asymptotically optimal. However, most precoding schemes exhibit high computational complexity as the system dimensions increase. For example, the near-optimal RZF requires the inversion of a large matrix. This motivated our companion paper, where we proposed to solve the issue in single-cell multi-user systems by approximating the matrix inverse by a truncated polynomial expansion (TPE), where the polynomial coefficients are optimized to maximize the system performance. We have shown that the proposed TPE precoding with a small number of coefficients reaches almost the performance of RZF but never exceeds it. In a realistic multi-cell scenario involving large-scale multi-user MIMO systems, the optimization of RZF precoding has thus far not been feasible. This is mainly attributed to the high complexity of the scenario and the non-linear impact of the necessary regularizing parameters. On the other hand, the scalar weights in TPE precoding give hope for possible throughput optimization. Following the same methodology as in the companion paper, we exploit random matrix theory to derive a deterministic expression for the asymptotic SINR for each user. We also provide an optimization algorithm to approximate the weights that maximize the network-wide weighted max-min fairness. The optimization weights can be used to mimic the user throughput distribution of RZF precoding. Using simulations, we compare the network throughput of the TPE precoding with that of the suboptimal RZF scheme and show that our scheme can achieve higher throughput using a TPE order of only 3

La contribución del daño por fuego en restringir los bosques montanos de Polylepis australis a las quebradas: aportes de una comparación sin réplicas

Con frecuencia los bosques de altura están restringidos a quebradas y existe controversia sobre los motivos de esta distribución, con un rango de argumentos que van desde los que afirman que en las quebradas existen mejores condiciones abióticas, hay menos herbivoría, la frecuencia de fuegos es menor o que allí los fuegos hacen menos daño. Nos propusimos entender la contribución del daño por fuego y proveemos datos para poner a prueba la hipótesis de que los fuegos hacen menos daño en las quebradas en comparación con los filos. Evaluamos el daño por fuego, la supervivencia post-fuego, la regeneración por rebrote y por semilla y el ramoneo entre árboles quemado y controles no quemados situados en una quebrada y en un filo de la ladera occidental de las Sierras Grandes de Córdoba, Argentina. El daño a las copas fue 28 % mayor en filo que en quebrada (94,3 ± 1,9 % y 66,1 ± 4,5 %, respectivamente) y estaba negativamente relacionada con la altura de los árboles, que además era menor en filo. La supervivencia postfuego no fue afectada diferencialmente por la topografía, pero el crecimiento de rebrotes y el establecimiento por semilla fue menor en filo que en quebrada. El ramoneo por animales domésticos fue dos veces más frecuente en el filo que en quebrada y mayor en los árboles quemados que en los árboles no quemados. Nuestro estudio aporta evidencias de que los bosques de Polylepis están en parte restringidos a quebradas debido a que allí los efectos de los fuegos son menos severos, lo cual se agrega a otras posibles causas como un uso más reducido por ganado, mayor crecimiento de los rebrotes y regeneración por semillas, las cuales seguramente están mediadas por condiciones abióticas.High mountain forests are often restricted to ravines and much debate has existed on the explanations of this distribution, with arguments ranging from abiotic site conditions being more favorable in ravines to there being reduced herbivory or reduced fire frequency and damage in ravines. We aim at understanding the contribution of fire damage and provide data to help test the hypothesis that fires are less damaging and that trees recover faster in ravines as compared to ridge sites. We evaluated crown damage, post-fire survival, regeneration by resprouts and seeds, and browsed stems in burned and unburned control Polylepis australis trees situated in a ravine and in a ridge forest in the west slope of the mountains of Central Argentina. The proportion of the tree crown scorched by fire was 28 % higher on the ridge than in the ravine (94.3 ± 1.9 % and 66.1 ± 4.5 %, respectively) and was negatively related to tree height which was lower on the ridge. Survival was not differentially affected, but post-fire re-growth and establishment through seeds was lower in the ridge as compared to the ravine. Browsed stems were about twice as frequent in the ridge as in the ravine, more so in the resprouting burned trees. Our study provides evidence that forests are restricted to ravines in part because the effects of fires are less severe at these sites than in ridges, which adds to other possible causes like reduced livestock use of ravines, enhanced regeneration by seed and faster tree growth within ravines all of which are probably mediated by abiotic factors.Fil: Alinari, María Julieta. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Von Müller, Axel Ricardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Sur. Estación Experimental Agropecuaria Esquel; ArgentinaFil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentin

The impact of delivery risk on optimal production and futures hedging

Multiple delivery specifications exist on nearly all commodity futures contracts. Sellers are typically allowed to choose among several grades of the underlying commodity. On the delivery day, the futures price converges to the spot price of the cheapest-to-deliver grade rather than to that of the par-delivery grade of the commodity. This imposes an additional delivery risk on hedgers. This paper derives the optimal production and futures hedging strategy for a risk-averse competitive firm in the presence of delivery risk. We show that, depending on its relative valuation, the delivery option may induce the firm to produce more than in the absence of delivery risk. If delivery risk is additively related to commodity price risk, the firm will under-hedge its exposure to commodity price risk. If delivery risk is multiplicatively related to commodity price risk, the firm will under- or over-hedge this exposure. For constant relative risk aversion, this is illustrated by a numerical example.delivery risk, futures, risk management, production

Restricted Export Flexibility and Risk Management with Options and Futures

This paper examines the production, export and risk management decisions of a risk-averse competitive firm under exchange rate risk. The firm is export flexible in allocating its output to either the domestic market or a foreign market after observing the exchange rate. Export flexibility is restricted by certain minimum sales requirements that are due to long-term considerations. Currency options are sufficient to derive a separation result under restricted export flexibility. Under fairly priced currency futures and options, full hedging with both instruments is optimal. Introducing fairly-priced currency options stimulates production provided that the currency futures market is unbiased.restricted export flexibility, risk management, currency futures, currency options

Interference-Aware RZF Precoding for Multi Cell Downlink Systems

Recently, a structure of an optimal linear precoder for multi cell downlink systems has been described in [1, Eq (3.33)]. Other references (e.g., [2,3]) have used simplified versions of the precoder to obtain promising performance gains. These gains have been hypothesized to stem from the additional degrees of freedom that allow for interference mitigation through interference relegation to orthogonal subspaces. However, no conclusive or rigorous understanding has yet been developed. In this paper, we build on an intuitive interference induction trade-off and the aforementioned precoding structure to propose an interference aware RZF (iaRZF) precoding scheme for multi cell downlink systems and we analyze its rate performance. Special emphasis is placed on the induced interference mitigation mechanism of iaRZF. For example, we will verify the intuitive expectation that the precoder structure can either completely remove induced inter-cell or intra-cell interference. We state new results from large-scale random matrix theory that make it possible to give more intuitive and insightful explanations of the precoder behavior, also for cases involving imperfect channel state information (CSI). We remark especially that the interference-aware precoder makes use of all available information about interfering channels to improve performance. Even very poor CSI allows for significant sum-rate gains. Our obtained insights are then used to propose heuristic precoder parameters for arbitrary systems, whose effectiveness are shown in more involved system scenarios. Furthermore, calculation and implementation of these parameters does not require explicit inter base station cooperation.Comment: Accepted for publication in IEEE Transactions on Signal Processing, 201

Phosphor-induzierte Kieferknochennekrose, eine "alte" aktuelle Berufserkrankung

Vor dem Hintergrund der kürzlich publizierten Fälle von Kieferknochennekrose in Verbindung mit einer Bisphosphonat-Therapie (sehr häufig angewandte medikamentöse Therapieform bei Osteoporose und in der Onkologie) soll ein historischer und medizinischer Überblick über die "alte" Berufserkrankung "Kieferknochennekrose durch Phosphor" gegeben werden. Die klinische Ausprägung der Berufserkrankung Phosphor-Kieferknochennekrose ähnelt dem Bild der Kieferknochennekrosen, die präsumptiv im Rahmen der Bisphosphonat-Therapie entstanden sind. Da diese Berufserkrankung in den letzten Jahrzehnten infolge industrieller Umstellungen selten geworden ist — lt. Auskunft des HVBG im Zeitraum 1998 bis 2002 keine Anzeige von Kieferknochennekrosen (BKZiffer 1109) —, soll hier ein Review zur Wissensauffrischung erfolgen. Vielleicht kann das arbeitsmedizinische Wissen zur Klärung dieser neu beobachteten Krankheitsentität in Verbindung mit Bisphosphonaten beitragen. Die ersten Beobachtungen einer Kieferknochennekrose bei Arbeitern in der Zündholzindustrie stammen aus den Jahren 1839 und 1843, die erste Publikation erfolgte in 1844, der ursächliche Zusammenhang wurde 1845 erkannt. Die phosphorinduzierte Kieferknochennekrose entsteht infolge Endothelschädigungen durch elementaren Phosphor. Gerade im Kieferknochenbereich können Bakterien via Zahnpathologien und anderen Umständen leicht in die ossären Strukturen vordringen, so dass schließlich eine Periostitis oder gar Osteomyelitis resultieren kann. Folgende Punkte werden behandelt: chemische Charakterisierung des Phosphor, historischer Abriss der Berufserkrankung Kieferknochennekrose, aktuelle Expositionsmöglichkeiten, Wirkungen des Phosphor, das klinische Bild der Kieferknochennekrose, Therapie und Prophylaxe

Diskrete dynamische Systeme: Der Einfluß perzeptueller Merkmale auf Komposition und Transfer von Bediensequenzen

Es werden zwei Experimente berichtet, in denen der Einfluß der Gruppierung von Bedienelementen auf die Organisation und Nutzung von Bedienwissen untersucht wird. In Experiment 1 wurde zunächst geprüft, in welchem Ausmaß verschiedene Arten perzeptueller Strukturierungen der Bedienoberfläche eines abstrakten Automaten bei der Reproduktion von Bediensequenzen zur Induktion von Chunks führen. Der Einfluß der Strukturierung war nicht eindeutig und hing für verschiedene Modalitäten davon ab, ob die Sequenzen vorgeführt wurden oder durch Probieren selbst herausgefunden werden mußten. In Experiment 2 wurde untersucht, inwieweit Transferleistungen bei unterschiedlichen Bedingungen der Transferierbarkeit von Bedienwissen durch die perzeptuelle Strukturierung der Bedienelemente beeinflußt werden. In der Erwerbsphase wurde die Gelegenheit zur Komposition von Wissenselementen über zwei verschiedene Lernkriterien variiert. In der anschließenden Transferphase konnten entweder (1) die gesamte Teilsequenz innerhalb eines Bereichs, (2) zwei aufeinanderfolgende Teilsequenzen benachbarter Bereiche oder (3) einzelne Komponenten übertragen werden. Für den Transfer erwiesen sich sowohl die Bereichszugehörigkeit als auch das unmittelbare Aufeinanderfolgen von Komponenten als bedeutsam. Die Ergebnisse implizieren, daß nicht die Strukturierung der Bedienoberfläche per se, sondern die sich in der Zeit daraus ergebende Abfolge der Strukturierungsbereiche für Organisation und Nutzung von Wissen über entsprechende Sequenzen entscheidend ist