True Limits Research Articles

Air flow rate thermal control system at low pressure drop

Low pressure drop thermal Mass Flow Controllers are generally thought to fulfill needs concerning the realization of a dynamic reference gas mixture generator for accurate gas analysis. A small air flow rate at low pressure drop must be controlled in a stable and precise way in the generator. True operative pressure drop limits, set point reproducibility, calibration needs and flow rate stability during operations were investigated for a low pressure drop thermal Mass Flow Controller. The flow rate bias due to late calibration and flow rate short-term stability were measured and discussed. The Allan method was used to calculate stability during operation. Calibration uncertainty, bias for late calibration, stability and set point reproducibility were composed to calculate the total uncertainty of the flow rate as a function of the operation time. Results show that it is possible to operate below the target uncertainty stated for a dynamic generator of gas mixtures down to 100Pa pressure drop. Stability gives the main contribution to total uncertainty at very short operation times, while calibration uncertainty gives the main contribution to total uncertainty at normal operation times. The calibration uncertainty at 0.1% is low enough to assure the target uncertainty for operation times over 10s. Daily verification of calibration enhances the reliability of the measurement. An accurate voltmeter is necessary for the reproducibility of the set point.

A New Algorithm for Determining Ultimate Pit Limits Based on Network Optimization

One of the main concerns of the mining industry is to determine ultimate pit limits. Final pit is a collection of blocks, which can be removed with maximum profit while following restrictions on the slope of the mine’s walls. The size, location and final shape of an open-pit are very important in designing the location of waste dumps, stockpiles, processing plants, access roads and other surface facilities as well as in developing a production program. There are numerous methods for designing ultimate pit limits. Some of these methods, such as floating cone algorithm, are heuristic and do not guarantee to generate optimum pit limits. Other methods, like Lerchs–Grossmann algorithm, are rigorous and always generate the true optimum pit limits. In this paper, a new rigorous algorithm is introduced. The main logic in this method is that only positive blocks, which can pay costs of their overlying non-positive blocks, are able to appear in the final pit. Those costs may be paid either by positive block itself or jointly with other positive blocks, which have the same overlying negative blocks. This logic is formulated using a network model as a Linear Programming (LP) problem. This algorithm can be applied to two- and three-dimension block models. Since there are many commercial programs available for solving LP problems, pit limits in large block models can be determined easily by using this method.

ESTUDO SOBRE A SAZONALIDADE DO PRODUTO MACARRÃO NO MERCADO VAREJISTA DO PARÁ

RESUMO: O produto macarrão é um importante componente da cesta básica do brasileiro, contudo, nos últimos anos, tem sofrido aumento no seu preço, em virtude da variação do preço do trigo no mercado internacional. Este aumento tem nítido efeito sobre a variação do preço do macarrão no país, considerando, principalmente, que o Brasil importa grande parte do trigo utilizado na fabricação de pães, massas, biscoitos entre outros. Dessa feita, estimaram-se os Índices Estacionais do macarrão em uma série histórica de janeiro de 2000 a junho de 2007. A análise constou do Índice Estacional Médio, Índice Estacional Verdadeiro, Limites Inferiores e Superiores dos preços do macarrão ao longo de um ano, bem como análise de Amplitude e Índice Cíclico. Este estudo pode auxiliar no planejamento e comercialização das empresas que transacionam esse produto considerando a melhor época para formação de estoque. PALAVRAS-CHAVE: comercialização, formação de estoques, planejamento.

Ambivalencia y orden colonial español en el Sahara Occidental: (1969-1973)

In this article we explore the dynamics of colonial relations in Western Sahara . The Spanish colonial penetration in Western Sahara since 1884 was partial, slow and incomplete . Only since 1958, which could be considered the beginning of a “second colonization”, substantive changes were colonial relations with the aim of developing the Spanish Sahara as a Spanish province and ensuring effective control of its borders with neighboring territories, which were formed as independent countries: Morocco, Mauritania and Algeria. The paternalistic nature of Spanish colonization and the Saharawi society participation from tribal organizational structures produced a specific type of colonial relations, different to that given in the neighboring territories. Such relationships have been considered by both parties as family and weak. However, there were moments in the history of Western Sahara where these colonial relationships acquired most dramatic dyes (particularly around the years 1930-1934/1956-1958). Since 1969 emerges the organization led by Mohamed Ould El Hadj Brahim Ould Lebsir, known for Basiri. Zemla violent repression of the June 17, 1970, which led to the disappearance of the Sahrawi leader, resulted the emergence of Polisario, 1973, which promoted the fight for the independence of Western Sahara. With the majority support of the Sahrawi population, the colonial relationships revealed their true limits. Starting from the life stories of Saharawi people lived by a series of extremes in 1970, 1974 and 1975, this 1. El gobierno espanol promovio el PUNS (Partido de Union Nacional Saharuis), en un intento de dividir a la poblacion saharaui introduciendo una organizacion afin a sus intereses. Este proyecto constituyo un fracaso, porque fue una iniciativa tardia, por la oposicion general de la poblacion saharaui movilizada en torno al Frente Polisario, y por la desercion del principal dirigente del partido, JaliHenna Rachid, que

The French School System and the Universalist Metanarrative (1880–2000s): Some Reflections about So-Called Explanatory Historical Notions Such as ‘La Forme Scolaire’

This article aims to question the relevance of notions such as ‘la forme scolaire’ in the account of the French state action in keeping up with the development of mass schooling, over a long historical process (from the late nineteenth century to the present day). Through its origin, this model is linked to a Universalist philosophical option that gives the school the responsibility to build not only the French nation, but also almost all humankind (Alfred Fouillée), in a Republican school metanarrative frame. This metanarrative and its philosophical principle entered a crisis when Universalism appeared to involve strong social segregation, and when colonialism was in a certain sense identified with Universalist philosophy. After first defining ‘la forme scolaire’ (and other closely related notions) and outlining three main French school history periods, the article questions what the forme scolaire explanatory and critical power is, its true limits, and what alternative concepts and perspectives are at our disposal. In this way, the alternatives discussed are the postmodernist positions, and that of Michel Foucault. More complex than the authors he inspired, Foucault can open the way to a perspective of school form renewal, free of the illusions of metanarrative and Universalist philosophy, based on a well-tempered multiplicity and a deliberately pluralistic but coherent philosophy (Michel Fabre).

EVSItalia Database of Evergreen Mediterranean Forests

A database of the Evergreen Mediterranean Forests of peninsular Italy is presented (EVSItalia Database of Evergreen Mediterranean Forests, GIVD ID EU-IT-014). The database stores 1,266 releves from published certified phytosociological sources, belonging to the syntaxa of Quercion ilicis. Specifically, Quercus ilex forest of Viburno-Quercetum ilicis and the cork oak forest in the syntaxa of Viburno-Quercetum ilicis suberetosum (according to a centralMediterranean classical interpretation). Q. suber stands are a variant of the Q. ilex forests, although the continued exploitation of cork and grazing activities in the cork forests, do not allow a precise analysis of the true spatial limits of the two biocoenoses. All the releves are uploaded to TURBOVEG; a related ArcGIS Database stores information about localization: Operational Geographic Units (OGU), corresponding to the quadrates of the Italian floristic grid, precise GPS or toponym information as well as descriptive records of locations extracted from geographical information systems are stored. The data-set aims to support reviews based on large data-sets for the classification of Italian vegetation types, classification of communities and their parameterization over larger areas by geostatistical analysis, the exploration geographic changes in community distribution along topographical gradients and to test changes along geographical gradients. A different insight in the patterns of synonymy and reassessment among syntaxa on the basis of a geographical approach is expected.

The Use of Probability Limits of COM–Poisson Charts and their Applications

The conventional c and u charts are based on the Poisson distribution assumption for the monitoring of count data. In practice, this assumption is not often satisfied, which requires a generalized control chart to monitor both over‐dispersed as well as under‐dispersed count data. The Conway–Maxwell–Poisson (COM–Poisson) distribution is a general count distribution that relaxes the equi‐dispersion assumption of the Poisson distribution and in fact encompasses the special cases of the Poisson, geometric, and Bernoulli distributions. In this study, the exact k‐sigma limits and true probability limits for COM–Poisson distribution chart have been proposed. The comparison between the 3‐sigma limits, the exact k‐sigma limits, and the true probability limits has been investigated, and it was found that the probability limits are more efficient than the 3‐sigma and the k‐sigma limits in terms of (i) low probability of false alarm, (ii) existence of lower control limits, and (iii) high discriminatory power of detecting a shift in the parameter (particularly downward shift). Finally, a real data set has been presented to illustrate the application of the probability limits in practice. Copyright © 2012 John Wiley & Sons, Ltd.

Analyses of dimensionless science

I read with interest the feature article “Dynamic similarity, the dimensionless science” by Diogo Bolster, Robert Hershberger, and Russell Donnelly. The authors give a simple example of dimensional analysis of the deflection of a light beam passing through a star’s gravitational field. But the example stretches the possibilities of dimensional analysis beyond its true limits. In fact, the deflection angle could be any nontrivial function of the dimensionless fraction Gm/c2r. Thus at least one more assumption outside dimensional reasoning must be made—the simplest solution, as the authors imply in the given example.A nontrivial solution may be demonstrated by performing the same exercise with the Planck law, which gives the radiation spectrum emitted by a blackbody. The relevant quantities are wavelength λ, temperature T, spectral emittance Bλ, speed of light c, Planck’s constant h, and Boltzmann’s constant k. According to the Buckingham Pi theorem, two independent dimensionless quantities can be formed using this list of quantities. An example of a solution isOne dimensionless quantity forms the left-hand side of the equation; the second, independent one occurs in the exponent of the denominator of the Planck law. Such a result could not be found by dimensional reasoning alone.© 2012 American Institute of Physics.

Optimal Power Flow with Facts Devices using Genetic Algorithm

The introduction of flexible AC transmission system (FACTS) in a power system reduces the losses, reduces the cost of generation, and improves the stability also improves the load capability of the system. In this paper, a non-traditional optimization technique, genetic algorithm is used to optimize the various process parameters involved of FACTS devices in a power system The various parameter taken into the consideration were the location of the FACTS were their types and their rated value of the device. A genetic algorithm (GA) is simultaneously is used to minimize the total generation cost, and power loss/voltage deviation with in true and reactive power generation limits, Test results on the modified IEEE 30-bus system with various types of the FACTS controller The optimization results clearly indicates that the correct location of the FACTS devices will increase the loadability of the system and GA can be effectively used for this type of optimization.

True detection limits in an experimental linearly heteroscedastic system. Part 1

Using a lab-constructed laser-excited filter fluorimeter deliberately designed to exhibit linearly heteroscedastic, additive Gaussian noise, it has been shown that accurate estimates may be made of the true theoretical Currie decision levels ( Y C and X C ) and true Currie detection limits ( Y D and X D ) for the detection of rhodamine 6 G tetrafluoroborate in ethanol. The obtained experimental values, for 5% probability of false positives and 5% probability of false negatives, were Y C = 56.1 mV, Y D = 125. mV, X C = 0.132 μg /mL and X D = 0.294 μg /mL. For 5% probability of false positives and 1% probability of false negatives, the obtained detection limits were Y D = 158. mV and X D = 0.372 μg /mL. These decision levels and corresponding detection limits were shown to pass the ultimate test: they resulted in observed probabilities of false positives and false negatives that were statistically equivalent to the a priori specified values.

True detection limits in an experimental linearly heteroscedastic system.: Part 2

Despite much different processing of the experimental fluorescence detection data presented in Part 1, essentially the same estimates were obtained for the true theoretical Currie decision levels ( Y C and X C ) and true Currie detection limits ( Y D and X D ). The obtained experimental values, for 5% probability of false positives and 5% probability of false negatives, were Y C = 56.0 mV, Y D = 125. mV, X C = 0.132 μg/mL and X D = 0.293 μg/mL. For 5% probability of false positives and 1% probability of false negatives, the obtained detection limits were Y D = 158 . mV and X D = 0.371 μg/mL. Furthermore, by using bootstrapping methodology on the experimental data for the standards and the analytical blank, it was possible to validate previously published experimental domain expressions for the decision levels ( y C and x C ) and detection limits ( y D and x D ). This was demonstrated by testing the generated decision levels and detection limits for their performance in regard to false positives and false negatives. In every case, the obtained numbers of false negatives and false positives were as specified a priori.

Ecologically relevant measures of tolerance to potentially lethal temperatures

The acute thermal tolerance of ectotherms has been measured in a variety of ways; these include assays where organisms are shifted abruptly to stressful temperatures and assays where organisms experience temperatures that are ramped more slowly to stressful levels. Ramping assays are thought to be more relevant to natural conditions where sudden abrupt shifts are unlikely to occur often, but it has been argued that thermal limits established under ramping conditions are underestimates of true thermal limits because stresses due to starvation and/or desiccation can arise under ramping. These confounding effects might also impact the variance and heritability of thermal tolerance. We argue here that ramping assays are useful in capturing aspects of ecological relevance even though there is potential for confounding effects of other stresses that can also influence thermal limits in nature. Moreover, we show that the levels of desiccation and starvation experienced by ectotherms in ramping assays will often be minor unless the assays involve small animals and last for many hours. Empirical data illustrate that the combined effects of food and humidity on thermal limits under ramping and sudden shifts to stressful conditions are unpredictable; in Drosophila melanogaster the presence of food decreased rather than increased thermal limits, whereas in Ceratitis capitata they had little impact. The literature provides examples where thermal limits are increased under ramping presumably because of the potential for physiological changes leading to acclimation. It is unclear whether heritabilities and population differentiation will necessarily be lower under ramping because of confounding effects. Although it is important to clearly define experimental methods, particularly when undertaking comparative assessments, and to understand potential confounding effects, thermotolerance assays based on ramping remain an important tool for understanding and predicting species responses to environmental change. An important area for further development is to identify the impact of rates of temperature change under field and laboratory conditions.

The rule of empires: those who built them, those who endured them, and why they always fall

In The Rule of Empires, Timothy Parsons gives a sweeping account of the evolution of empire from its origins in ancient Rome to its most recent twentieth-century embodiment. He explains what constitutes an empire and offers suggestions about what empires of the past can tell us about our own historical moment. Parsons uses imperial examples that stretch from ancient Rome, to Britain's new imperialism in Kenya, to the Third Reich to parse the features common to all empires, their evolutions and self-justifying myths, and the reasons for their inevitable decline. Parsons argues that far from confirming some sort of Darwinian hierarchy of advanced and primitive societies, conquests were simply the products of a temporary advantage in military technology, wealth, and political will. Beneath the self-justifying rhetoric of benevolent paternalism and cultural superiority lay economic exploitation and the desire for power. Yet imperial ambitions still appear viable in the twenty-first century, Parsons shows, because their defenders and detractors alike employ abstract and romanticized perspectives that fail to grasp the historical reality of subjugation. Writing from the perspective of the common subject rather than that of the imperial conquerors, Parsons offers a historically grounded cautionary tale rich with accounts of subjugated peoples throwing off the yoke of empire time and time again. In providing an accurate picture of what it is like to live as a subject, The Rule of Empires lays bare the rationalizations of imperial conquerors and their apologists and exposes the true limits of hard power.

Crystal structure of small protein crambin at 0.48 Å resolution.

With the development of highly brilliant and extremely intense synchrotron X-ray sources, extreme high-resolution limits for biological samples are now becoming attainable. Here, a study is presented that sets the record in crystallographic resolution for a biological macromolecule. The structure of the small protein crambin was determined to 0.48 Å resolution on the PETRA II ring before its conversion to a dedicated synchrotron-radiation source. The results reveal a wealth of details in electron density and demonstrate the possibilities that are potentially offered by a high-energy source. The question now arises as to what the true limits are in terms of what can be seen at such high resolution. From what can be extrapolated from the results using crystals of crambin, this limit would be at approximately 0.40 Å, which approaches that for smaller compounds.

An evaluation of text analysis technologies

A performance evaluation of 15 text-analysis systems was recently conducted to realistically assess the state of the art for detailed information extraction from unconstrained continuous text. Reports associated with terrorism were chosen as the target domain, and all systems were tested on a collection of previously unseen texts released by a government agency. Based on multiple strategies for computing each metric, the competing systems were evaluated for recall, precision, and overgeneration. The results support the claim that systems incorporating natural language-processing techniques are more effective than systems based on stochastic techniques alone. A wide range of language-processing strategies was employed by the top-scoring systems, indicating that many natural language-processing techniques provide a viable foundation for sophisticated text analysis. Further evaluation is needed to produce a more detailed assessment of the relative merits of specific technologies and establish true performance limits for automated information extraction.

Compressed Sensing: How Sharp Is the Restricted Isometry Property?

Compressed sensing (CS) seeks to recover an unknown vector with $N$ entries by making far fewer than $N$ measurements; it posits that the number of CS measurements should be comparable to the information content of the vector, not simply $N$. CS combines directly the important task of compression with the measurement task. Since its introduction in 2004 there have been hundreds of papers on CS, a large fraction of which develop algorithms to recover a signal from its compressed measurements. Because of the paradoxical nature of CS—exact reconstruction from seemingly undersampled measurements—it is crucial for acceptance of an algorithm that rigorous analyses verify the degree of undersampling the algorithm permits. The restricted isometry property (RIP) has become the dominant tool used for the analysis in such cases. We present here an asymmetric form of RIP that gives tighter bounds than the usual symmetric one. We give the best known bounds on the RIP constants for matrices from the Gaussian ensemble. Our derivations illustrate the way in which the combinatorial nature of CS is controlled. Our quantitative bounds on the RIP allow precise statements as to how aggressively a signal can be undersampled, the essential question for practitioners. We also document the extent to which RIP gives precise information about the true performance limits of CS, by comparison with approaches from high-dimensional geometry.

Financial Crisis of 2008-2009 and Other Financial Crises: How to Manage Them?

Financial Crisis of 2008-2009 and Other Financial Crises: How to Manage Them?

God Interrupted: Heresy and the European Imagination between the World Wars. By Benjamin Lazier

God Interrupted: Heresy and the European Imagination between the World Wars. By Benjamin Lazier

Stochastic mine design optimisation based on simulated annealing: pit limits, production schedules, multiple orebody scenarios and sensitivity analysis

Over recent years, new methods have been developed to integrate uncertainty into the optimisation of life-of-mine production planning. One of these methods is based on scheduling with a simulated annealing (SA) algorithm and equally probable realisations of a given mineral deposit. The latter realisations are used to generate production schedules that minimise the possibility of deviating from production targets, and result in schedules with a substantial improvement in the net present value (NPV), shown to be in the order of 25% when compared to conventional scheduling within the conventionally optimal pit limits. To facilitate the utilisation of this method, a sensitivity analysis is presented in this study. The study documents the case of a copper deposit where 10 simulated realisations are sufficient to provide stable life-of-mine optimisation results. In addition, the study shows that the selected true optimal pit limits are larger than those derived through conventional optimisation. Stochastically optimised pit limits are found to be ∼17% larger, in terms of total tonnage, than the conventional (deterministic) optimal pit limits. The difference adds one year of mining and ∼10% of additional NPV when compared to the NPV of conventional optimal pit limits and a production schedule generated stochastically with the same simulated annealing algorithm.

Modeling Non Equilibrium Potentiometry to Understand and Control Selectivity and Detection Limit

In most interpretations of ion-sensor response phase boundary potentials are used. They assume electroneutrality and equilibrium or steady-state, thus ignore electrochemical migration and time-dependent effects. It is in conflict with many experimental reports on ion-sensors, in which both kinetic (time-dependent) discrimination of ions to improve selectivity, and non-equilibrium transmembrane ion-transport for lowering detection limits, are deliberately used. The Nernst-Planck-Poisson (NPP) equations are used to model the non-equilibrium response. In the NPP model, electroneutrality and steady-state/equilibrium assumptions are abandoned and directly predicting the selectivity and the low detection limit variability over time, and the influence of other parameters, e.g. ion diffusibility, are possible. The NPP allows for solving the inverse problem i.e. to optimize sensor properties and measurement conditions via target functions and hierarchical modeling. The conditions under which experimentally measured selectivity coefficients are true (unbiased) and detection limits are optimized are demonstrated, and practical conclusions relevant to bioassays are derived.