4,061 research outputs found
Real-Time Water Vapor Maps from a GPS Surface Network: Construction, Validation, and Applications
In this paper the construction of real-time integrated water vapor (IWV) maps from a surface network of global positioning system (GPS) receivers is presented. The IWV maps are constructed using a twodimensional variational technique with a persistence background that is 15 min old. The background error covariances are determined using a novel two-step method, which is based on the Hollingsworth¿Lonnberg method. The quality of these maps is assessed by comparison with radiosonde observations and IWV maps from a numerical weather prediction (NWP) model. The analyzed GPS IWV maps have no bias against radiosonde observations and a small bias against NWP analysis and forecasts up to 9 h. The standard deviation with radiosonde observations is around 2 kg m-2, and the standard deviation with NWP increases with increasing forecast length (from 2 kg m-2 for the NWP analysis to 4 kg m-2 for a forecast length of 48 h). To illustrate the additional value of these real-time products for nowcasting, three thunderstorm cases are discussed. The constructed GPS IWV maps are combined with data from the weather radar, a lightning detection network, and surface wind observations. All cases show that the location of developing thunderstorms can be identified 2 h prior to initiation in the convergence of moist air
Exact Markovian kinetic equation for a quantum Brownian oscillator
We derive an exact Markovian kinetic equation for an oscillator linearly
coupled to a heat bath, describing quantum Brownian motion. Our work is based
on the subdynamics formulation developed by Prigogine and collaborators. The
space of distribution functions is decomposed into independent subspaces that
remain invariant under Liouville dynamics. For integrable systems in
Poincar\'e's sense the invariant subspaces follow the dynamics of uncoupled,
renormalized particles. In contrast for non-integrable systems, the invariant
subspaces follow a dynamics with broken-time symmetry, involving generalized
functions. This result indicates that irreversibility and stochasticity are
exact properties of dynamics in generalized function spaces. We comment on the
relation between our Markovian kinetic equation and the Hu-Paz-Zhang equation.Comment: A few typos in the published version are correcte
Legal and Actual Central Bank Independence: A Case Study of Bank Indonesia
Indicators of central bank independence (CBI) based on the interpretation central bank laws in place may not capture the actual independence of the central bank. This paper develops an indicator of actual independence of the Bank Indonesia (BI), the central bank of Indonesia, for the period 1953-2008 and compares it with a new legal CBI indicator based on Cukierman (1992). The indicator of actual independence captures institutional and economic factors that affect CBI. We find that before 1999, legal and actual independence of BI diverged substantially. After a new central bank law was enacted, the legal independence of BI increased and converged to actual independence.
Device, system and method for tumor detection and/or monitoring
A device, system and method for tumor detection and/or monitoring is proposed. The proposed device comprises a first analysis unit for analyzing the spatial distribution of the photoplethysmographic, PPG, amplitude of PPG signals obtained from a region of interest, a second analysis unit for analyzing the spatial distribution of arterial blood oxygen saturation obtained from said PPG signals, and an evaluation unit for detecting and/or monitoring a tumor in said region of interest based on said two analyses.</p
Distortion reduced signal detection
A device and a method for extracting information from detected characteristic signals receives a data stream derivable from electromagnetic radiation emitted or reflected by an object. The data stream comprises a continuous or discrete characteristic signal including physiological information and a disturbing signal portion. The physiological information is representative of at least one at least partially periodic vital signal. The disturbing signal portion is representative of at least one of an object motion portion and/or a non-indicative reflection portion. The characteristic signal is transferred by converting at least three absolute components of the characteristic signal related to respective additive channels to at least two difference components of the characteristic signal, wherein each of the at least two difference components can be derived through a respective arithmetic transformation considering at least two of the at least three absolute components, wherein the arithmetic transformation for each of the at least two difference components further comprises coefficients that substantially sum to zero. Consequently, the disturbing signal portion can be at least partially suppressed in the transferred signal.</p
The effects of pulse stimulation on biota - Research in relation to ICES advice - Effects on dogfish
Onderzoek naar het welzijn van hondshaaien bij de vangst. Er is onderzocht of de methode van het gebruik van stroom wel diervriendelijk is. De conclusie is dat dit geen beletsel voor de diervriendelijkheid oplever
Supply and Demand in Water Planning: Streamflow Estimation and Conservational Water Pricing
Recent studies indicated the need for development of surface water supplies in Kentucky. Rising resource costs make economically efficient reservoir designs increasingly important. This study was undertaken to provide methods in water supply reservoir design that increase system benefits.
Two major factors influencing reservoir design were studied: estimated future streamflow into the reservoir and demands placed on the reservoir. Standard reservoir sizing methods rely on historical streamflow data. This data is frequently limited and uncertainty in required storage estimates may result. To assess the reliability of a design, the use of mathematical models in simulation studies was proposed. Existing stochastic and parametric models of streamflow were reviewed and their limitations discussed. Parameters for the stochastic models must be estimated from historical streamflow data, and limited data produces unreliable estimates of the true values for these parameters. A streamflow record extended by a parametric model through simulation may provide more reliable estimates of the parameters in the stochastic streamflow model than the short historical record. A methodology was presented to evaluate the ability of a parametric model to improve the stochastic model parameter estimates in this manner. It was found that the parameter estimates of a stochastic model might be significantly improved by this process. A long historical record of rainfall may not be available to provide the necessary inputs to a parametric model. One method for providing these inputs is to model the daily rainfall process at the potential site. A modified Markov Chain model was proposed which used continuous distributions, rather than discrete transition probabilities, to represent the process when rainfall actually occurred. A two-parameter gamma distribution fit the Kentucky data. The model provided a good representation of the daily point rainfall process. 15-20 years of historical daily rainfall data were required to produce stable estimates of model parameters.
The role of the demand function in reservoir design was examined. Projected demand is commonly assumed not to depend on the concurrent water rates. Data on rural residential water demand in Kentucky has indicated that a price-demand relationship does exist for this sector. The second part of the study was undertaken to see if benefits to a hypothetical community from water supply could be increased by utilizing price-demand information in reservoir design studies. Three pricing policies were examined and their effect on reservoir design determined. The first policy assumed no price-demand relationship, and demand was based on existing community usage with a low water rate. A price-demand relationship was assumed in the second policy, and the water rate was constant. The third policy assumed the price-demand relationship, and the price charged for water during each billing period was a non-linear function which increased as the amount of water in storage at the beginning of the period decreased.
It was found that the use of the conservation pricing policies substantially reduced storage requirements while providing increased, demonstrable net benefits to the community. The conservation pricing policies substantially lowered the average price paid for water. The effect of uncertainty in consumer response to changes in price was studied by using a probabilitistic price-demand relationship. This uncertainty did not significantly reduce the effectiveness of the conservation policy. It was concluded that demand management by the use of a proper pricing policy could significantly increase water supply benefits to a community
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