Carbonate rock depositional models: A microfacies approach

Energy Technology Data Exchange (ETDEWEB)

Carozzi, A.V.

1988-01-01

Carbonate rocks contain more than 50% by weight carbonate minerals such as calcite, dolomite, and siderite. Understanding how these rocks form can lead to more efficient methods of petroleum exploration. Micofacies analysis techniques can be used as a method of predicting models of sedimentation for carbonate rocks. Micofacies in carbonate rocks can be seen clearly only in thin sections under a microscope. This section analysis of carbonate rocks is a tool that can be used to understand depositional environments, diagenetic evolution of carbonate rocks, and the formation of porosity and permeability in carbonate rocks. The use of micofacies analysis techniques is applied to understanding the origin and formation of carbonate ramps, carbonate platforms, and carbonate slopes and basins. This book will be of interest to students and professionals concerned with the disciplines of sedimentary petrology, sedimentology, petroleum geology, and palentology.

Robust stabilization of nonlinear systems: The LMI approach

Directory of Open Access Journals (Sweden)

Šiljak D. D.

2000-01-01

Full Text Available This paper presents a new approach to robust quadratic stabilization of nonlinear systems within the framework of Linear Matrix Inequalities (LMI. The systems are composed of a linear constant part perturbed by an additive nonlinearity which depends discontinuously on both time and state. The only information about the nonlinearity is that it satisfies a quadratic constraint. Our major objective is to show how linear constant feedback laws can be formulated to stabilize this type of systems and, at the same time, maximize the bounds on the nonlinearity which the system can tolerate without going unstable. We shall broaden the new setting to include design of decentralized control laws for robust stabilization of interconnected systems. Again, the LMI methods will be used to maximize the class of uncertain interconnections which leave the overall system connectively stable. It is useful to learn that the proposed LMI formulation “recognizes” the matching conditions by returning a feedback gain matrix for any prescribed bound on the interconnection terms. More importantly, the new formulation provides a suitable setting for robust stabilization of nonlinear systems where the nonlinear perturbations satisfy the generalized matching conditions.

Design optimization for cost and quality: The robust design approach

Science.gov (United States)

Unal, Resit

1990-01-01

Designing reliable, low cost, and operable space systems has become the key to future space operations. Designing high quality space systems at low cost is an economic and technological challenge to the designer. A systematic and efficient way to meet this challenge is a new method of design optimization for performance, quality, and cost, called Robust Design. Robust Design is an approach for design optimization. It consists of: making system performance insensitive to material and subsystem variation, thus allowing the use of less costly materials and components; making designs less sensitive to the variations in the operating environment, thus improving reliability and reducing operating costs; and using a new structured development process so that engineering time is used most productively. The objective in Robust Design is to select the best combination of controllable design parameters so that the system is most robust to uncontrollable noise factors. The robust design methodology uses a mathematical tool called an orthogonal array, from design of experiments theory, to study a large number of decision variables with a significantly small number of experiments. Robust design also uses a statistical measure of performance, called a signal-to-noise ratio, from electrical control theory, to evaluate the level of performance and the effect of noise factors. The purpose is to investigate the Robust Design methodology for improving quality and cost, demonstrate its application by the use of an example, and suggest its use as an integral part of space system design process.

A robust neural network-based approach for microseismic event detection

KAUST Repository

Akram, Jubran

2017-08-17

We present an artificial neural network based approach for robust event detection from low S/N waveforms. We use a feed-forward network with a single hidden layer that is tuned on a training dataset and later applied on the entire example dataset for event detection. The input features used include the average of absolute amplitudes, variance, energy-ratio and polarization rectilinearity. These features are calculated in a moving-window of same length for the entire waveform. The output is set as a user-specified relative probability curve, which provides a robust way of distinguishing between weak and strong events. An optimal network is selected by studying the weight-based saliency and effect of number of neurons on the predicted results. Using synthetic data examples, we demonstrate that this approach is effective in detecting weaker events and reduces the number of false positives.

A Multi-physics Approach to Understanding Low Porosity Soils and Reservoir Rocks

Science.gov (United States)

Prasad, M.; Mapeli, C.; Livo, K.; Hasanov, A.; Schindler, M.; Ou, L.

2017-12-01

We present recent results on our multiphysics approach to rock physics. Thus, we evaluate geophysical measurements by simultaneously measuring petrophysical properties or imaging strains. In this paper, we present simultaneously measured acoustic and electrical anisotropy data as functions of pressure. Similarly, we present strains and strain localization images simultaneously acquired with acoustic measurements as well as NMR T2 relaxations on pressurized fluids as well as rocks saturated with these pressurized fluids. Such multiphysics experiments allow us to constrain and assign appropriate causative mechanisms to development rock physics models. They also allow us to decouple various effects, for example, fluid versus pressure, on geophysical measurements. We show applications towards reservoir characterization as well as CO2 sequestration applications.

IDENTIFICATION OF A ROBUST LICHEN INDEX FOR THE DECONVOLUTION OF LICHEN AND ROCK MIXTURES USING PATTERN SEARCH ALGORITHM (CASE STUDY: GREENLAND

Directory of Open Access Journals (Sweden)

S. Salehi

2016-06-01

Full Text Available Lichens are the dominant autotrophs of polar and subpolar ecosystems commonly encrust the rock outcrops. Spectral mixing of lichens and bare rock can shift diagnostic spectral features of materials of interest thus leading to misinterpretation and false positives if mapping is done based on perfect spectral matching methodologies. Therefore, the ability to distinguish the lichen coverage from rock and decomposing a mixed pixel into a collection of pure reflectance spectra, can improve the applicability of hyperspectral methods for mineral exploration. The objective of this study is to propose a robust lichen index that can be used to estimate lichen coverage, regardless of the mineral composition of the underlying rocks. The performance of three index structures of ratio, normalized ratio and subtraction have been investigated using synthetic linear mixtures of pure rock and lichen spectra with prescribed mixing ratios. Laboratory spectroscopic data are obtained from lichen covered samples collected from Karrat, Liverpool Land, and Sisimiut regions in Greenland. The spectra are then resampled to Hyperspectral Mapper (HyMAP resolution, in order to further investigate the functionality of the indices for the airborne platform. In both resolutions, a Pattern Search (PS algorithm is used to identify the optimal band wavelengths and bandwidths for the lichen index. The results of our band optimization procedure revealed that the ratio between R894-1246 and R1110 explains most of the variability in the hyperspectral data at the original laboratory resolution (R2=0.769. However, the normalized index incorporating R1106-1121 and R904-1251 yields the best results for the HyMAP resolution (R2=0.765.

Robust design optimization using the price of robustness, robust least squares and regularization methods

Science.gov (United States)

Bukhari, Hassan J.

2017-12-01

In this paper a framework for robust optimization of mechanical design problems and process systems that have parametric uncertainty is presented using three different approaches. Robust optimization problems are formulated so that the optimal solution is robust which means it is minimally sensitive to any perturbations in parameters. The first method uses the price of robustness approach which assumes the uncertain parameters to be symmetric and bounded. The robustness for the design can be controlled by limiting the parameters that can perturb.The second method uses the robust least squares method to determine the optimal parameters when data itself is subjected to perturbations instead of the parameters. The last method manages uncertainty by restricting the perturbation on parameters to improve sensitivity similar to Tikhonov regularization. The methods are implemented on two sets of problems; one linear and the other non-linear. This methodology will be compared with a prior method using multiple Monte Carlo simulation runs which shows that the approach being presented in this paper results in better performance.

Rock mechanics site descriptive model-theoretical approach. Preliminary site description Forsmark area - version 1.2

Energy Technology Data Exchange (ETDEWEB)

Fredriksson, Anders; Olofsson, Isabelle [Golder Associates AB, Uppsala (Sweden)

2005-12-15

The present report summarises the theoretical approach to estimate the mechanical properties of the rock mass in relation to the Preliminary Site Descriptive Modelling, version 1.2 Forsmark. The theoretical approach is based on a discrete fracture network (DFN) description of the fracture system in the rock mass and on the results of mechanical testing of intact rock and on rock fractures. To estimate the mechanical properties of the rock mass a load test on a rock block with fractures is simulated with the numerical code 3DEC. The location and size of the fractures are given by DFN-realisations. The rock block was loaded in plain strain condition. From the calculated relationship between stresses and deformations the mechanical properties of the rock mass were determined. The influence of the geometrical properties of the fracture system on the mechanical properties of the rock mass was analysed by loading 20 blocks based on different DFN-realisations. The material properties of the intact rock and the fractures were kept constant. The properties are set equal to the mean value of each measured material property. The influence of the variation of the properties of the intact rock and variation of the mechanical properties of the fractures are estimated by analysing numerical load tests on one specific block (one DFN-realisation) with combinations of properties for intact rock and fractures. Each parameter varies from its lowest values to its highest values while the rest of the parameters are held constant, equal to the mean value. The resulting distribution was expressed as a variation around the value determined with mean values on all parameters. To estimate the resulting distribution of the mechanical properties of the rock mass a Monte-Carlo simulation was performed by generating values from the two distributions independent of each other. The two values were added and the statistical properties of the resulting distribution were determined.

Rock mechanics site descriptive model-theoretical approach. Preliminary site description Forsmark area - version 1.2

International Nuclear Information System (INIS)

Fredriksson, Anders; Olofsson, Isabelle

2005-12-01

The present report summarises the theoretical approach to estimate the mechanical properties of the rock mass in relation to the Preliminary Site Descriptive Modelling, version 1.2 Forsmark. The theoretical approach is based on a discrete fracture network (DFN) description of the fracture system in the rock mass and on the results of mechanical testing of intact rock and on rock fractures. To estimate the mechanical properties of the rock mass a load test on a rock block with fractures is simulated with the numerical code 3DEC. The location and size of the fractures are given by DFN-realisations. The rock block was loaded in plain strain condition. From the calculated relationship between stresses and deformations the mechanical properties of the rock mass were determined. The influence of the geometrical properties of the fracture system on the mechanical properties of the rock mass was analysed by loading 20 blocks based on different DFN-realisations. The material properties of the intact rock and the fractures were kept constant. The properties are set equal to the mean value of each measured material property. The influence of the variation of the properties of the intact rock and variation of the mechanical properties of the fractures are estimated by analysing numerical load tests on one specific block (one DFN-realisation) with combinations of properties for intact rock and fractures. Each parameter varies from its lowest values to its highest values while the rest of the parameters are held constant, equal to the mean value. The resulting distribution was expressed as a variation around the value determined with mean values on all parameters. To estimate the resulting distribution of the mechanical properties of the rock mass a Monte-Carlo simulation was performed by generating values from the two distributions independent of each other. The two values were added and the statistical properties of the resulting distribution were determined

In situ fragmentation and rock particle sorting on arid hills

Science.gov (United States)

McGrath, Gavan S.; Nie, Zhengyao; Dyskin, Arcady; Byrd, Tia; Jenner, Rowan; Holbeche, Georgina; Hinz, Christoph

2013-03-01

Transport processes are often proposed to explain the sorting of rock particles on arid hillslopes, where mean rock particle size often decreases in the downslope direction. Here we show that in situ fragmentation of rock particles can also produce similar patterns. A total of 93,414 rock particles were digitized from 880 photographs of the surface of three mesa hills in the Great Sandy Desert, Australia. Rock particles were characterized by the projected Feret's diameter and circularity. Distance from the duricrust cap was found to be a more robust explanatory variable for diameter than the local hillslope gradient. Mean diameter decreased exponentially downslope, while the fractional area covered by rock particles decreased linearly. Rock particle diameters were distributed lognormally, with both the location and scale parameters decreasing approximately linearly downslope. Rock particle circularity distributions showed little change; only a slight shift in the mode to more circular particles was noted to occur downslope. A dynamic fragmentation model was used to assess whether in situ weathering alone could reproduce the observed downslope fining of diameters. Modeled and observed size distributions agreed well and both displayed a preferential loss of relatively large rock particles and an apparent approach to a terminal size distribution of the rocks downslope. We show this is consistent with a size effect in material strength, where large rocks are more susceptible to fatigue failure under stress than smaller rocks. In situ fragmentation therefore produces qualitatively similar patterns to those that would be expected to arise from selective transport.

Robust regularized least-squares beamforming approach to signal estimation

KAUST Repository

Suliman, Mohamed Abdalla Elhag

2017-05-12

In this paper, we address the problem of robust adaptive beamforming of signals received by a linear array. The challenge associated with the beamforming problem is twofold. Firstly, the process requires the inversion of the usually ill-conditioned covariance matrix of the received signals. Secondly, the steering vector pertaining to the direction of arrival of the signal of interest is not known precisely. To tackle these two challenges, the standard capon beamformer is manipulated to a form where the beamformer output is obtained as a scaled version of the inner product of two vectors. The two vectors are linearly related to the steering vector and the received signal snapshot, respectively. The linear operator, in both cases, is the square root of the covariance matrix. A regularized least-squares (RLS) approach is proposed to estimate these two vectors and to provide robustness without exploiting prior information. Simulation results show that the RLS beamformer using the proposed regularization algorithm outperforms state-of-the-art beamforming algorithms, as well as another RLS beamformers using a standard regularization approaches.

A robust neural network-based approach for microseismic event detection

KAUST Repository

Akram, Jubran; Ovcharenko, Oleg; Peter, Daniel

2017-01-01

We present an artificial neural network based approach for robust event detection from low S/N waveforms. We use a feed-forward network with a single hidden layer that is tuned on a training dataset and later applied on the entire example dataset

A preferential design approach for energy-efficient and robust implantable neural signal processing hardware.

Science.gov (United States)

Narasimhan, Seetharam; Chiel, Hillel J; Bhunia, Swarup

2009-01-01

For implantable neural interface applications, it is important to compress data and analyze spike patterns across multiple channels in real time. Such a computational task for online neural data processing requires an innovative circuit-architecture level design approach for low-power, robust and area-efficient hardware implementation. Conventional microprocessor or Digital Signal Processing (DSP) chips would dissipate too much power and are too large in size for an implantable system. In this paper, we propose a novel hardware design approach, referred to as "Preferential Design" that exploits the nature of the neural signal processing algorithm to achieve a low-voltage, robust and area-efficient implementation using nanoscale process technology. The basic idea is to isolate the critical components with respect to system performance and design them more conservatively compared to the noncritical ones. This allows aggressive voltage scaling for low power operation while ensuring robustness and area efficiency. We have applied the proposed approach to a neural signal processing algorithm using the Discrete Wavelet Transform (DWT) and observed significant improvement in power and robustness over conventional design.

A robust fuzzy possibilistic AHP approach for partner selection in international strategic alliance

Directory of Open Access Journals (Sweden)

Vahid Reza Salamat

2018-09-01

Full Text Available The international strategic alliance is an inevitable solution for making competitive advantage and reducing the risk in today’s business environment. Partner selection is an important part in success of partnerships, and meanwhile it is a complicated decision because of various dimensions of the problem and inherent conflicts of stockholders. The purpose of this paper is to provide a practical approach to the problem of partner selection in international strategic alliances, which fulfills the gap between theories of inter-organizational relationships and quantitative models. Thus, a novel Robust Fuzzy Possibilistic AHP approach is proposed for combining the benefits of two complementary theories of inter-organizational relationships named, (1 Resource-based view, and (2 Transaction-cost theory and considering Fit theory as the perquisite of alliance success. The Robust Fuzzy Possibilistic AHP approach is a novel development of Interval-AHP technique employing robust formulation; aimed at handling the ambiguity of the problem and let the use of intervals as pairwise judgments. The proposed approach was compared with existing approaches, and the results show that it provides the best quality solutions in terms of minimum error degree. Moreover, the framework implemented in a case study and its applicability were discussed.

Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach

Science.gov (United States)

Draebing, D.; Krautblatter, M.; Dikau, R.

2014-12-01

Degradation of permafrost rock wall decreases stability and can initiate rock slope instability of all magnitudes. Rock instability is controlled by the balance of shear forces and shear resistances. The sensitivity of slope stability to warming results from a complex interplay of shear forces and resistances. Conductive, convective and advective heat transport processes act to warm, degrade and thaw permafrost in rock walls. On a seasonal scale, snow cover changes are a poorly understood key control of the timing and extent of thawing and permafrost degradation. We identified two potential critical time windows where shear forces might exceed shear resistances of the rock. In early summer combined hydrostatic and cryostatic pressure can cause a peak in shear force exceeding high frozen shear resistance and in autumn fast increasing shear forces can exceed slower increasing shear resistance. On a multiannual system scale, shear resistances change from predominantly rock-mechanically to ice-mechanically controlled. Progressive rock bridge failure results in an increase of sensitivity to warming. Climate change alters snow cover and duration and, hereby, thermal and mechanical processes in the rock wall. Amplified thawing of permafrost will result in higher rock slope instability and rock fall activity. We present a holistic conceptual approach connecting thermal and mechanical processes, validate parts of the model with geophysical and kinematic data and develop future scenarios to enhance understanding on system scale.

Solid images generated from UAVs to analyze areas affected by rock falls

Science.gov (United States)

Giordan, Daniele; Manconi, Andrea; Allasia, Paolo; Baldo, Marco

2015-04-01

The study of rock fall affected areas is usually based on the recognition of principal joints families and the localization of potential instable sectors. This requires the acquisition of field data, although as the areas are barely accessible and field inspections are often very dangerous. For this reason, remote sensing systems can be considered as suitable alternative. Recently, Unmanned Aerial Vehicles (UAVs) have been proposed as platform to acquire the necessary information. Indeed, mini UAVs (in particular in the multi-rotors configuration) provide versatility for the acquisition from different points of view a large number of high resolution optical images, which can be used to generate high resolution digital models relevant to the study area. By considering the recent development of powerful user-friendly software and algorithms to process images acquired from UAVs, there is now a need to establish robust methodologies and best-practice guidelines for correct use of 3D models generated in the context of rock fall scenarios. In this work, we show how multi-rotor UAVs can be used to survey areas by rock fall during real emergency contexts. We present two examples of application located in northwestern Italy: the San Germano rock fall (Piemonte region) and the Moneglia rock fall (Liguria region). We acquired data from both terrestrial LiDAR and UAV, in order to compare digital elevation models generated with different remote sensing approaches. We evaluate the volume of the rock falls, identify the areas potentially unstable, and recognize the main joints families. The use on is not so developed but probably this approach can be considered the better solution for a structural investigation of large rock walls. We propose a methodology that jointly considers the Structure from Motion (SfM) approach for the generation of 3D solid images, and a geotechnical analysis for the identification of joint families and potential failure planes.

Into the Past: A Step Towards a Robust Kimberley Rock Art Chronology.

Science.gov (United States)

Ross, June; Westaway, Kira; Travers, Meg; Morwood, Michael J; Hayward, John

2016-01-01

The recent establishment of a minimum age estimate of 39.9 ka for the origin of rock art in Sulawesi has challenged claims that Western Europe was the locus for the production of the world's earliest art assemblages. Tantalising excavated evidence found across northern Australian suggests that Australia too contains a wealth of ancient art. However, the dating of rock art itself remains the greatest obstacle to be addressed if the significance of Australian assemblages are to be recognised on the world stage. A recent archaeological project in the northwest Kimberley trialled three dating techniques in order to establish chronological markers for the proposed, regional, relative stylistic sequence. Applications using optically-stimulated luminescence (OSL) provided nine minimum age estimates for fossilised mudwasp nests overlying a range of rock art styles, while Accelerator Mass Spectrometry radiocarbon (AMS 14C) results provided an additional four. Results confirm that at least one phase of the northwest Kimberley rock art assemblage is Pleistocene in origin. A complete motif located on the ceiling of a rockshelter returned a minimum age estimate of 16 ± 1 ka. Further, our results demonstrate the inherent problems in relying solely on stylistic classifications to order rock art assemblages into temporal sequences. An earlier than expected minimum age estimate for one style and a maximum age estimate for another together illustrate that the Holocene Kimberley rock art sequence is likely to be far more complex than generally accepted with different styles produced contemporaneously well into the last few millennia. It is evident that reliance on techniques that produce minimum age estimates means that many more dating programs will need to be undertaken before the stylistic sequence can be securely dated.

Into the Past: A Step Towards a Robust Kimberley Rock Art Chronology.

Directory of Open Access Journals (Sweden)

June Ross

Full Text Available The recent establishment of a minimum age estimate of 39.9 ka for the origin of rock art in Sulawesi has challenged claims that Western Europe was the locus for the production of the world's earliest art assemblages. Tantalising excavated evidence found across northern Australian suggests that Australia too contains a wealth of ancient art. However, the dating of rock art itself remains the greatest obstacle to be addressed if the significance of Australian assemblages are to be recognised on the world stage. A recent archaeological project in the northwest Kimberley trialled three dating techniques in order to establish chronological markers for the proposed, regional, relative stylistic sequence. Applications using optically-stimulated luminescence (OSL provided nine minimum age estimates for fossilised mudwasp nests overlying a range of rock art styles, while Accelerator Mass Spectrometry radiocarbon (AMS 14C results provided an additional four. Results confirm that at least one phase of the northwest Kimberley rock art assemblage is Pleistocene in origin. A complete motif located on the ceiling of a rockshelter returned a minimum age estimate of 16 ± 1 ka. Further, our results demonstrate the inherent problems in relying solely on stylistic classifications to order rock art assemblages into temporal sequences. An earlier than expected minimum age estimate for one style and a maximum age estimate for another together illustrate that the Holocene Kimberley rock art sequence is likely to be far more complex than generally accepted with different styles produced contemporaneously well into the last few millennia. It is evident that reliance on techniques that produce minimum age estimates means that many more dating programs will need to be undertaken before the stylistic sequence can be securely dated.

Range sections as rock models for intensity rock scene segmentation

CSIR Research Space (South Africa)

Mkwelo, S

2007-11-01

Full Text Available This paper presents another approach to segmenting a scene of rocks on a conveyor belt for the purposes of measuring rock size. Rock size estimation instruments are used to monitor, optimize and control milling and crushing in the mining industry...

A random sampling approach for robust estimation of tissue-to-plasma ratio from extremely sparse data.

Science.gov (United States)

Chu, Hui-May; Ette, Ene I

2005-09-02

his study was performed to develop a new nonparametric approach for the estimation of robust tissue-to-plasma ratio from extremely sparsely sampled paired data (ie, one sample each from plasma and tissue per subject). Tissue-to-plasma ratio was estimated from paired/unpaired experimental data using independent time points approach, area under the curve (AUC) values calculated with the naïve data averaging approach, and AUC values calculated using sampling based approaches (eg, the pseudoprofile-based bootstrap [PpbB] approach and the random sampling approach [our proposed approach]). The random sampling approach involves the use of a 2-phase algorithm. The convergence of the sampling/resampling approaches was investigated, as well as the robustness of the estimates produced by different approaches. To evaluate the latter, new data sets were generated by introducing outlier(s) into the real data set. One to 2 concentration values were inflated by 10% to 40% from their original values to produce the outliers. Tissue-to-plasma ratios computed using the independent time points approach varied between 0 and 50 across time points. The ratio obtained from AUC values acquired using the naive data averaging approach was not associated with any measure of uncertainty or variability. Calculating the ratio without regard to pairing yielded poorer estimates. The random sampling and pseudoprofile-based bootstrap approaches yielded tissue-to-plasma ratios with uncertainty and variability. However, the random sampling approach, because of the 2-phase nature of its algorithm, yielded more robust estimates and required fewer replications. Therefore, a 2-phase random sampling approach is proposed for the robust estimation of tissue-to-plasma ratio from extremely sparsely sampled data.

Strategy for a Rock Mechanics Site Descriptive Model. Development and testing of the theoretical approach

Energy Technology Data Exchange (ETDEWEB)

Staub, Isabelle; Fredriksson, Anders; Outters, Nils [Golder Associates AB, Uppsala (Sweden)

2002-05-01

In the purpose of studying the possibilities of a Deep Repository for spent fuel, the Swedish Nuclear and Fuel Management Company (SKB) is currently planning for Site Investigations. Data collected from these Site Investigations are interpreted and analysed to achieve the full Site Description, which is built up of models from all the disciplines that are considered of importance for the Site Description. One of these models is the Rock Mechanical Descriptive Model,which would be developed for any site in hard crystalline rock, and is a combination and evaluation of the characterisation of rock mass by means of empirical relationships and a theoretical approach based on numerical modelling. The present report describes the theoretical approach. The characterisation of the mechanical properties of the rock mass, viewed as a unit consisting of intact rock and fractures, is achieved by numerical simulations with following input parameters: initial stresses, fracture geometry, distribution of rock mechanical properties, such as deformation and strength parameters, for the intact rock and for the fractures. The numerical modelling was performed with the two-dimensional code UDEC, and the rock block models were generated from 2D trace sections extracted from the 3D Discrete Fracture Network (DFN) model. Assumptions and uncertainties related to the set-up of the model are considered. The numerical model was set-up to simulate a plain strain-loading test. Different boundary conditions were applied on the model for simulating stress conditions (I) in the undisturbed rock mass, and (II) at the proximity of a tunnel. In order to assess the reliability of the model sensitivity analyses have been conducted on some rock block models for defining the dependency of mechanical properties to in situ stresses, the influence of boundary conditions, rock material and joint constitutive models used to simulate the behaviour of intact rock and fractures, domain size and anisotropy. To

Strategy for a Rock Mechanics Site Descriptive Model. Development and testing of the theoretical approach

International Nuclear Information System (INIS)

Staub, Isabelle; Fredriksson, Anders; Outters, Nils

2002-05-01

In the purpose of studying the possibilities of a Deep Repository for spent fuel, the Swedish Nuclear and Fuel Management Company (SKB) is currently planning for Site Investigations. Data collected from these Site Investigations are interpreted and analysed to achieve the full Site Description, which is built up of models from all the disciplines that are considered of importance for the Site Description. One of these models is the Rock Mechanical Descriptive Model,which would be developed for any site in hard crystalline rock, and is a combination and evaluation of the characterisation of rock mass by means of empirical relationships and a theoretical approach based on numerical modelling. The present report describes the theoretical approach. The characterisation of the mechanical properties of the rock mass, viewed as a unit consisting of intact rock and fractures, is achieved by numerical simulations with following input parameters: initial stresses, fracture geometry, distribution of rock mechanical properties, such as deformation and strength parameters, for the intact rock and for the fractures. The numerical modelling was performed with the two-dimensional code UDEC, and the rock block models were generated from 2D trace sections extracted from the 3D Discrete Fracture Network (DFN) model. Assumptions and uncertainties related to the set-up of the model are considered. The numerical model was set-up to simulate a plain strain-loading test. Different boundary conditions were applied on the model for simulating stress conditions (I) in the undisturbed rock mass, and (II) at the proximity of a tunnel. In order to assess the reliability of the model sensitivity analyses have been conducted on some rock block models for defining the dependency of mechanical properties to in situ stresses, the influence of boundary conditions, rock material and joint constitutive models used to simulate the behaviour of intact rock and fractures, domain size and anisotropy. To

Probabilistic approach to rock fall hazard assessment: potential of historical data analysis

Directory of Open Access Journals (Sweden)

C. Dussauge-Peisser

2002-01-01

Full Text Available We study the rock fall volume distribution for three rock fall inventories and we fit the observed data by a power-law distribution, which has recently been proposed to describe landslide and rock fall volume distributions, and is also observed for many other natural phenomena, such as volcanic eruptions or earthquakes. We use these statistical distributions of past events to estimate rock fall occurrence rates on the studied areas. It is an alternative to deterministic approaches, which have not proved successful in predicting individual rock falls. The first one concerns calcareous cliffs around Grenoble, French Alps, from 1935 to 1995. The second data set is gathered during the 1912–1992 time window in Yosemite Valley, USA, in granite cliffs. The third one covers the 1954–1976 period in the Arly gorges, French Alps, with metamorphic and sedimentary rocks. For the three data sets, we find a good agreement between the observed volume distributions and a fit by a power-law distribution for volumes larger than 50 m3 , or 20 m3 for the Arly gorges. We obtain similar values of the b exponent close to 0.45 for the 3 data sets. In agreement with previous studies, this suggests, that the b value is not dependant on the geological settings. Regarding the rate of rock fall activity, determined as the number of rock fall events with volume larger than 1 m3 per year, we find a large variability from one site to the other. The rock fall activity, as part of a local erosion rate, is thus spatially dependent. We discuss the implications of these observations for the rock fall hazard evaluation. First, assuming that the volume distributions are temporally stable, a complete rock fall inventory allows for the prediction of recurrence rates for future events of a given volume in the range of the observed historical data. Second, assuming that the observed volume distribution follows a power-law distribution without cutoff at small or large scales, we can

Probabilistic approach to rock fall hazard assessment: potential of historical data analysis

Science.gov (United States)

Dussauge-Peisser, C.; Helmstetter, A.; Grasso, J.-R.; Hantz, D.; Desvarreux, P.; Jeannin, M.; Giraud, A.

We study the rock fall volume distribution for three rock fall inventories and we fit the observed data by a power-law distribution, which has recently been proposed to describe landslide and rock fall volume distributions, and is also observed for many other natural phenomena, such as volcanic eruptions or earthquakes. We use these statistical distributions of past events to estimate rock fall occurrence rates on the studied areas. It is an alternative to deterministic approaches, which have not proved successful in predicting individual rock falls. The first one concerns calcareous cliffs around Grenoble, French Alps, from 1935 to 1995. The second data set is gathered during the 1912-1992 time window in Yosemite Valley, USA, in granite cliffs. The third one covers the 1954-1976 period in the Arly gorges, French Alps, with metamorphic and sedimentary rocks. For the three data sets, we find a good agreement between the observed volume distributions and a fit by a power-law distribution for volumes larger than 50 m3 , or 20 m3 for the Arly gorges. We obtain similar values of the b exponent close to 0.45 for the 3 data sets. In agreement with previous studies, this suggests, that the b value is not dependant on the geological settings. Regarding the rate of rock fall activity, determined as the number of rock fall events with volume larger than 1 m3 per year, we find a large variability from one site to the other. The rock fall activity, as part of a local erosion rate, is thus spatially dependent. We discuss the implications of these observations for the rock fall hazard evaluation. First, assuming that the volume distributions are temporally stable, a complete rock fall inventory allows for the prediction of recurrence rates for future events of a given volume in the range of the observed historical data. Second, assuming that the observed volume distribution follows a power-law distribution without cutoff at small or large scales, we can extrapolate these

S-variable approach to LMI-based robust control

CERN Document Server

Ebihara, Yoshio; Arzelier, Denis

2015-01-01

This book shows how the use of S-variables (SVs) in enhancing the range of problems that can be addressed with the already-versatile linear matrix inequality (LMI) approach to control can, in many cases, be put on a more unified, methodical footing. Beginning with the fundamentals of the SV approach, the text shows how the basic idea can be used for each problem (and when it should not be employed at all). The specific adaptations of the method necessitated by each problem are also detailed. The problems dealt with in the book have the common traits that: analytic closed-form solutions are not available; and LMIs can be applied to produce numerical solutions with a certain amount of conservatism. Typical examples are robustness analysis of linear systems affected by parametric uncertainties and the synthesis of a linear controller satisfying multiple, often  conflicting, design specifications. For problems in which LMI methods produce conservative results, the SV approach is shown to achieve greater accuracy...

A robust and hierarchical approach for the automatic co-registration of intensity and visible images

Science.gov (United States)

González-Aguilera, Diego; Rodríguez-Gonzálvez, Pablo; Hernández-López, David; Luis Lerma, José

2012-09-01

This paper presents a new robust approach to integrate intensity and visible images which have been acquired with a terrestrial laser scanner and a calibrated digital camera, respectively. In particular, an automatic and hierarchical method for the co-registration of both sensors is developed. The approach integrates several existing solutions to improve the performance of the co-registration between range-based and visible images: the Affine Scale-Invariant Feature Transform (A-SIFT), the epipolar geometry, the collinearity equations, the Groebner basis solution and the RANdom SAmple Consensus (RANSAC), integrating a voting scheme. The approach presented herein improves the existing co-registration approaches in automation, robustness, reliability and accuracy.

A review of numerical techniques approaching microstructures of crystalline rocks

Science.gov (United States)

Zhang, Yahui; Wong, Louis Ngai Yuen

2018-06-01

The macro-mechanical behavior of crystalline rocks including strength, deformability and failure pattern are dominantly influenced by their grain-scale structures. Numerical technique is commonly used to assist understanding the complicated mechanisms from a microscopic perspective. Each numerical method has its respective strengths and limitations. This review paper elucidates how numerical techniques take geometrical aspects of the grain into consideration. Four categories of numerical methods are examined: particle-based methods, block-based methods, grain-based methods, and node-based methods. Focusing on the grain-scale characters, specific relevant issues including increasing complexity of micro-structure, deformation and breakage of model elements, fracturing and fragmentation process are described in more detail. Therefore, the intrinsic capabilities and limitations of different numerical approaches in terms of accounting for the micro-mechanics of crystalline rocks and their phenomenal mechanical behavior are explicitly presented.

A New Robust Tracking Control Design for Turbofan Engines: H∞/Leitmann Approach

Directory of Open Access Journals (Sweden)

Muxuan Pan

2017-04-01

Full Text Available In this paper, a H ∞ /Leitmann approach to the robust tracking control design is presented for an uncertain dynamic system. This new method is developed in the following two steps. Firstly, a tracking dynamic system with simultaneous consideration of parameter uncertainty and noise is modeled based on a linear system and a reference model. Accordingly, a “nominal system” from the tracking system is defined and controlled by a H ∞ control to obtain the asymptotical stability and noise resistance. Secondly, by making use of a Lyapunov function and the norm boundedness, a new robust control with the “Leitmann approach” is designed to cope with the uncertainty. The two controls collaborate with each other to achieve “uniform tracking boundedness” and “uniform ultimate tracking boundedness”. The new approach is then applied to an aircraft turbofan control design, and the numerical simulation results show the prescribed performances of the closed-loop system and the advantage of the developed approach.

A Robust Bayesian Approach for Structural Equation Models with Missing Data

Science.gov (United States)

Lee, Sik-Yum; Xia, Ye-Mao

2008-01-01

In this paper, normal/independent distributions, including but not limited to the multivariate t distribution, the multivariate contaminated distribution, and the multivariate slash distribution, are used to develop a robust Bayesian approach for analyzing structural equation models with complete or missing data. In the context of a nonlinear…

Robust Stability and H∞ Stabilization of Switched Systems with Time-Varying Delays Using Delta Operator Approach

Directory of Open Access Journals (Sweden)

Chen Qin

2013-01-01

Full Text Available This paper considers the problems of the robust stability and robust H∞ controller design for time-varying delay switched systems using delta operator approach. Based on the average dwell time approach and delta operator theory, a sufficient condition of the robust exponential stability is presented by choosing an appropriate Lyapunov-Krasovskii functional candidate. Then, a state feedback controller is designed such that the resulting closed-loop system is exponentially stable with a guaranteed H∞ performance. The obtained results are formulated in the form of linear matrix inequalities (LMIs. Finally, a numerical example is provided to explicitly illustrate the feasibility and effectiveness of the proposed method.

Proceedings of the 3. Canada-US rock mechanics symposium and 20. Canadian rock mechanics symposium : rock engineering 2009 : rock engineering in difficult conditions

Energy Technology Data Exchange (ETDEWEB)

NONE

2009-07-01

This conference provided a forum for geologists, mining operators and engineers to discuss the application of rock mechanics in engineering designs. Members of the scientific and engineering communities discussed challenges and interdisciplinary elements involved in rock engineering. New geological models and methods of characterizing rock masses and ground conditions in underground engineering projects were discussed along with excavation and mining methods. Papers presented at the conference discussed the role of rock mechanics in forensic engineering. Geophysics, geomechanics, and risk-based approaches to rock engineering designs were reviewed. Issues related to high pressure and high flow water conditions were discussed, and new rock physics models designed to enhance hydrocarbon recovery were presented. The conference featured 84 presentations, of which 9 have been catalogued separately for inclusion in this database. tabs., figs.

Determination of rock depth using artificial intelligence techniques

Institute of Scientific and Technical Information of China (English)

R. Viswanathan; Pijush Samui

2016-01-01

This article adopts three artificial intelligence techniques, Gaussian Process Regression (GPR), Least Square Support Vector Machine (LSSVM) and Extreme Learning Machine (ELM), for prediction of rock depth (d) at any point in Chennai. GPR, ELM and LSSVM have been used as regression techniques. Latitude and longitude are also adopted as inputs of the GPR, ELM and LSSVM models. The performance of the ELM, GPR and LSSVM models has been compared. The developed ELM, GPR and LSSVM models produce spatial variability of rock depth and offer robust models for the prediction of rock depth.

Note: CO₂-mineral dissolution experiments using a rocking autoclave and a novel titanium reaction cell.

Science.gov (United States)

Purser, Gemma; Rochelle, Christopher A; Wallis, Humphrey C; Rosenqvist, Jörgen; Kilpatrick, Andrew D; Yardley, Bruce W D

2014-08-01

A novel titanium reaction cell has been constructed for the study of water-rock-CO2 reactions. The reaction cell has been used within a direct-sampling rocking autoclave and offers certain advantages over traditional "flexible gold/titanium cell" approaches. The main advantage is robustness, as flexible cells are prone to rupture on depressurisation during gas-rich experiments. The reaction cell was tested in experiments during an inter-laboratory comparison study, in which mineral kinetic data were determined. The cell performed well during experiments up to 130 °C and 300 bars pressure. The data obtained were similar to those of other laboratories participating in the study, and also to previously published data.

Primal and dual approaches to adjustable robust optimization

NARCIS (Netherlands)

de Ruiter, Frans

2018-01-01

Robust optimization has become an important paradigm to deal with optimization under uncertainty. Adjustable robust optimization is an extension that deals with multistage problems. This thesis starts with a short but comprehensive introduction to adjustable robust optimization. Then the two

An H(∞) control approach to robust learning of feedforward neural networks.

Science.gov (United States)

Jing, Xingjian

2011-09-01

A novel H(∞) robust control approach is proposed in this study to deal with the learning problems of feedforward neural networks (FNNs). The analysis and design of a desired weight update law for the FNN is transformed into a robust controller design problem for a discrete dynamic system in terms of the estimation error. The drawbacks of some existing learning algorithms can therefore be revealed, especially for the case that the output data is fast changing with respect to the input or the output data is corrupted by noise. Based on this approach, the optimal learning parameters can be found by utilizing the linear matrix inequality (LMI) optimization techniques to achieve a predefined H(∞) "noise" attenuation level. Several existing BP-type algorithms are shown to be special cases of the new H(∞)-learning algorithm. Theoretical analysis and several examples are provided to show the advantages of the new method. Copyright © 2011 Elsevier Ltd. All rights reserved.

Rock History and Culture

OpenAIRE

Gonzalez, Éric

2013-01-01

Two ambitious works written by French-speaking scholars tackle rock music as a research object, from different but complementary perspectives. Both are a definite must-read for anyone interested in the contextualisation of rock music in western popular culture. In Une histoire musicale du rock (i.e. A Musical History of Rock), rock music is approached from the point of view of the people – musicians and industry – behind the music. Christophe Pirenne endeavours to examine that field from a m...

Methods for robustness programming

NARCIS (Netherlands)

Olieman, N.J.

2008-01-01

Robustness of an object is defined as the probability that an object will have properties as required. Robustness Programming (RP) is a mathematical approach for Robustness estimation and Robustness optimisation. An example in the context of designing a food product, is finding the best composition

A Rock Physics Feasibility Study of the Geothermal Gassum Reservoir, Copenhagen Area, Denmark

DEFF Research Database (Denmark)

Bredesen, Kenneth; Dalgaard, Esben Borch; Mathiesen, Anders

The subsurface of Denmark stores significant amounts of renewable geothermal energy which may contribute to domestic heating for centuries. However, establishing a successful geothermal plant with robust production capacity require reservoirs with sufficient high porosity and permeability. Modern...... quantitative seismic interpretation is a good approach to de-risk prospects and gain reservoir insight, but is so far not widely used for geothermal applications. In this study we perform a rock physics feasibility study as a pre-step towards quantitative seismic interpretation of geothermal reservoirs......, primarily in areas around Copenhagen. The results argue that it may be possible to use AVO and seismic inversion data to distinguish geothermal sandstone reservoirs from surrounding shales and to estimate porosity and permeability. Moreover, this study may represent new possibilities for future rock physics...

Robustness in Railway Operations (RobustRailS)

DEFF Research Database (Denmark)

Jensen, Jens Parbo; Nielsen, Otto Anker

This study considers the problem of enhancing railway timetable robustness without adding slack time, hence increasing the travel time. The approach integrates a transit assignment model to assess how passengers adapt their behaviour whenever operations are changed. First, the approach considers...

Robust motion control of oscillatory-base manipulators h∞-control and sliding-mode-control-based approaches

CERN Document Server

Toda, Masayoshi

2016-01-01

This book provides readers with alternative robust approaches to control design for an important class of systems characteristically associated with ocean-going vessels and structures. These systems, which include crane vessels, on-board cranes, radar gimbals, and a conductivity temperature and depth winch, are modelled as manipulators with oscillating bases. One design approach is based on the H-infinity control framework exploiting an effective combination of PD control, an extended matrix polytope and a robust stability analysis method with a state-dependent coefficient form. The other is based on sliding-mode control using some novel nonlinear sliding surfaces. The model demonstrates how successful motion control can be achieved by suppressing base oscillations and in the presence of uncertainties. This is important not only for ocean engineering systems in which the problems addressed here originate but more generally as a benchmark platform for robust motion control with disturbance rejection. Researche...

Conceptual information processing: A robust approach to KBS-DBMS integration

Science.gov (United States)

Lazzara, Allen V.; Tepfenhart, William; White, Richard C.; Liuzzi, Raymond

1987-01-01

Integrating the respective functionality and architectural features of knowledge base and data base management systems is a topic of considerable interest. Several aspects of this topic and associated issues are addressed. The significance of integration and the problems associated with accomplishing that integration are discussed. The shortcomings of current approaches to integration and the need to fuse the capabilities of both knowledge base and data base management systems motivates the investigation of information processing paradigms. One such paradigm is concept based processing, i.e., processing based on concepts and conceptual relations. An approach to robust knowledge and data base system integration is discussed by addressing progress made in the development of an experimental model for conceptual information processing.

A robust quantitative near infrared modeling approach for blend monitoring.

Science.gov (United States)

Mohan, Shikhar; Momose, Wataru; Katz, Jeffrey M; Hossain, Md Nayeem; Velez, Natasha; Drennen, James K; Anderson, Carl A

2018-01-30

This study demonstrates a material sparing Near-Infrared modeling approach for powder blend monitoring. In this new approach, gram scale powder mixtures are subjected to compression loads to simulate the effect of scale using an Instron universal testing system. Models prepared by the new method development approach (small-scale method) and by a traditional method development (blender-scale method) were compared by simultaneously monitoring a 1kg batch size blend run. Both models demonstrated similar model performance. The small-scale method strategy significantly reduces the total resources expended to develop Near-Infrared calibration models for on-line blend monitoring. Further, this development approach does not require the actual equipment (i.e., blender) to which the method will be applied, only a similar optical interface. Thus, a robust on-line blend monitoring method can be fully developed before any large-scale blending experiment is viable, allowing the blend method to be used during scale-up and blend development trials. Copyright © 2017. Published by Elsevier B.V.

ARTICLE Robust Diagnosis of Mechatronics System by Bond Graph Approach

Directory of Open Access Journals (Sweden)

Abderrahmene Sellami

2018-03-01

Full Text Available This article presents design of a robust diagnostic system based on bond graph model for a mechatronic system. Mechatronics is the synergistic and systemic combination of mechanics, electronics and computer science. The design of a mechatronic system modeled by the bond graph model becomes easier and more generous. The bond graph tool is a unified graphical language for all areas of engineering sciences and confirmed as a structured approach to modeling and simulation of multidisciplinary systems.

Robust Frequency-Domain Constrained Feedback Design via a Two-Stage Heuristic Approach.

Science.gov (United States)

Li, Xianwei; Gao, Huijun

2015-10-01

Based on a two-stage heuristic method, this paper is concerned with the design of robust feedback controllers with restricted frequency-domain specifications (RFDSs) for uncertain linear discrete-time systems. Polytopic uncertainties are assumed to enter all the system matrices, while RFDSs are motivated by the fact that practical design specifications are often described in restricted finite frequency ranges. Dilated multipliers are first introduced to relax the generalized Kalman-Yakubovich-Popov lemma for output feedback controller synthesis and robust performance analysis. Then a two-stage approach to output feedback controller synthesis is proposed: at the first stage, a robust full-information (FI) controller is designed, which is used to construct a required output feedback controller at the second stage. To improve the solvability of the synthesis method, heuristic iterative algorithms are further formulated for exploring the feedback gain and optimizing the initial FI controller at the individual stage. The effectiveness of the proposed design method is finally demonstrated by the application to active control of suspension systems.

Stochastic Discount Factor Approach to International Risk-Sharing:A Robustness Check of the Bilateral Setting

NARCIS (Netherlands)

Hadzi-Vaskov, M.; Kool, C.J.M.

2007-01-01

This paper presents a robustness check of the stochastic discount factor approach to international (bilateral) risk-sharing given in Brandt, Cochrane, and Santa-Clara (2006). We demonstrate two main inherent limitations of the bilateral SDF approach to international risk-sharing. First, the discount

A Robust Obstacle Avoidance for Service Robot Using Bayesian Approach

Directory of Open Access Journals (Sweden)

Widodo Budiharto

2011-03-01

Full Text Available The objective of this paper is to propose a robust obstacle avoidance method for service robot in indoor environment. The method for obstacles avoidance uses information about static obstacles on the landmark using edge detection. Speed and direction of people that walks as moving obstacle obtained by single camera using tracking and recognition system and distance measurement using 3 ultrasonic sensors. A new geometrical model and maneuvering method for moving obstacle avoidance introduced and combined with Bayesian approach for state estimation. The obstacle avoidance problem is formulated using decision theory, prior and posterior distribution and loss function to determine an optimal response based on inaccurate sensor data. Algorithms for moving obstacles avoidance method proposed and experiment results implemented to service robot also presented. Various experiments show that our proposed method very fast, robust and successfully implemented to service robot called Srikandi II that equipped with 4 DOF arm robot developed in our laboratory.

Kinetic approach for interactive reactions of radionuclide, bacteria and granitic crushed rock

International Nuclear Information System (INIS)

Kim, Jung Woo; Baik, Min Hoon; Lee, Seung Yeop; Lee, Jae Kwang; Kim, Seung Soo; Oh, Jong Min; Lee, Tae Yup

2011-01-01

For many radionuclides, sorption is an important phenomenon as their migration rates in groundwater are reduced in both engineered barrier and fractured rock matrix. Sorption of radionuclides is strongly dependent on the chemistry of the surrounding groundwater, such as pH, Eh, ionic strength, etc., by changing their valence states (e.g.,). In addition, it is also known that some bacteria can change the mobility and speciation of a radionuclide in groundwater. Biological immobilization mechanisms of radionuclides include precipitation, transformation to less soluble forms and so on. On the other hand, bacteria can also play a role of sorbent for radionuclides. Since bacteria can not only be mobile as a colloid but also be immobile as biofilm in the rock fracture, the bacteria as the sorbents of radionuclides in the groundwater can have both positive and negative effects on the radionuclide migration. In this study, therefore, sorption of radionuclide onto rock surface in the presence of bacteria was investigated via batch experiments. Although sorption equilibrium state can be expected in the transport of weakly sorbing (distribution coefficient, K d -3 m 3 kg -1 ) or strongly adsorbing (K d > ∼4.6 m 3 kg -1 ) nuclides in fractured rock, sorption kinetics needs to be considered in the intermediate range. Therefore, the sorption of radionuclide whose valence state is expected to be changed by biological reduction was evaluated in a kinetic approach

Comparison of linear and nonlinear programming approaches for "worst case dose" and "minmax" robust optimization of intensity-modulated proton therapy dose distributions.

Science.gov (United States)

Zaghian, Maryam; Cao, Wenhua; Liu, Wei; Kardar, Laleh; Randeniya, Sharmalee; Mohan, Radhe; Lim, Gino

2017-03-01

Robust optimization of intensity-modulated proton therapy (IMPT) takes uncertainties into account during spot weight optimization and leads to dose distributions that are resilient to uncertainties. Previous studies demonstrated benefits of linear programming (LP) for IMPT in terms of delivery efficiency by considerably reducing the number of spots required for the same quality of plans. However, a reduction in the number of spots may lead to loss of robustness. The purpose of this study was to evaluate and compare the performance in terms of plan quality and robustness of two robust optimization approaches using LP and nonlinear programming (NLP) models. The so-called "worst case dose" and "minmax" robust optimization approaches and conventional planning target volume (PTV)-based optimization approach were applied to designing IMPT plans for five patients: two with prostate cancer, one with skull-based cancer, and two with head and neck cancer. For each approach, both LP and NLP models were used. Thus, for each case, six sets of IMPT plans were generated and assessed: LP-PTV-based, NLP-PTV-based, LP-worst case dose, NLP-worst case dose, LP-minmax, and NLP-minmax. The four robust optimization methods behaved differently from patient to patient, and no method emerged as superior to the others in terms of nominal plan quality and robustness against uncertainties. The plans generated using LP-based robust optimization were more robust regarding patient setup and range uncertainties than were those generated using NLP-based robust optimization for the prostate cancer patients. However, the robustness of plans generated using NLP-based methods was superior for the skull-based and head and neck cancer patients. Overall, LP-based methods were suitable for the less challenging cancer cases in which all uncertainty scenarios were able to satisfy tight dose constraints, while NLP performed better in more difficult cases in which most uncertainty scenarios were hard to meet

Frequency-Domain Robust Performance Condition for Controller Uncertainty in SISO LTI Systems: A Geometric Approach

Directory of Open Access Journals (Sweden)

Vahid Raissi Dehkordi

2009-01-01

Full Text Available This paper deals with the robust performance problem of a linear time-invariant control system in the presence of robust controller uncertainty. Assuming that plant uncertainty is modeled as an additive perturbation, a geometrical approach is followed in order to find a necessary and sufficient condition for robust performance in the form of a bound on the magnitude of controller uncertainty. This frequency domain bound is derived by converting the problem into an optimization problem, whose solution is shown to be more time-efficient than a conventional structured singular value calculation. The bound on controller uncertainty can be used in controller order reduction and implementation problems.

A PARTIAL ROBUST OPTIMIZATION APPROACH TO INVENTORY MANAGEMENT FOR THE OFFLINE-TO-ONLINE PROBLEM UNDER DIFFERENT SELLING PRICES

Institute of Scientific and Technical Information of China (English)

Hui Yu; Jie Deng

2017-01-01

This study examines an optimal inventory strategy when a retailer markets a product at different selling prices through a dual-channel supply chain,comprising an online channel and an offline channel.Using the operating pattern of the offiine-to-online (O2O) business model,we develop a partial robust optimization (PRO) model.Then,we provide a closed-form solution when only the mean and standard deviation of the online channel demand distribution is known and the offline channel demand follows a uniform distribution (partial robust).Specifically,owing to the good structural properties of the solution,we obtain a heuristic ordering formula for the general distribution case (i.e.,the offline channel demand follows a general distribution).In addition,a series of numerical experiments prove the rationality of our conjecture.Moreover,after comparing our solution with other possible policies,we conclude that the PRO approach improves the performance of incorporating the internet into an existing supply chain and,thus,is able to adjust the level of conservativeness of the solution.Finally,in a degenerated situation,we compare our PRO approach with a combination of information approach.The results show that the PRO approach has more "robust" performance.As a result,a reasonable trade-off between robustness and performance is achieved.

a Radical Collaborative Approach: Developing a Model for Learning Theory, Human-Based Computation and Participant Motivation in a Rock-Art Heritage Application

Science.gov (United States)

Haubt, R.

2016-06-01

This paper explores a Radical Collaborative Approach in the global and centralized Rock-Art Database project to find new ways to look at rock-art by making information more accessible and more visible through public contributions. It looks at rock-art through the Key Performance Indicator (KPI), identified with the latest Australian State of the Environment Reports to help develop a better understanding of rock-art within a broader Cultural and Indigenous Heritage context. Using a practice-led approach the project develops a conceptual collaborative model that is deployed within the RADB Management System. Exploring learning theory, human-based computation and participant motivation the paper develops a procedure for deploying collaborative functions within the interface design of the RADB Management System. The paper presents the results of the collaborative model implementation and discusses considerations for the next iteration of the RADB Universe within an Agile Development Approach.

A systematic approach to robust preconditioning for gradient-based inverse scattering algorithms

International Nuclear Information System (INIS)

Nordebo, Sven; Fhager, Andreas; Persson, Mikael; Gustafsson, Mats

2008-01-01

This paper presents a systematic approach to robust preconditioning for gradient-based nonlinear inverse scattering algorithms. In particular, one- and two-dimensional inverse problems are considered where the permittivity and conductivity profiles are unknown and the input data consist of the scattered field over a certain bandwidth. A time-domain least-squares formulation is employed and the inversion algorithm is based on a conjugate gradient or quasi-Newton algorithm together with an FDTD-electromagnetic solver. A Fisher information analysis is used to estimate the Hessian of the error functional. A robust preconditioner is then obtained by incorporating a parameter scaling such that the scaled Fisher information has a unit diagonal. By improving the conditioning of the Hessian, the convergence rate of the conjugate gradient or quasi-Newton methods are improved. The preconditioner is robust in the sense that the scaling, i.e. the diagonal Fisher information, is virtually invariant to the numerical resolution and the discretization model that is employed. Numerical examples of image reconstruction are included to illustrate the efficiency of the proposed technique

Robust Design of Terminal ILC with H∞ Mixed Sensitivity Approach for a Thermoforming Oven

Directory of Open Access Journals (Sweden)

Guy Gauthier

2008-01-01

Full Text Available This paper presents a robust design approach for terminal iterative learning control (TILC. This robust design uses the H∞ mixed-sensitivity technique. An industrial application is described where TILC is used to control the reheat phase of plastic sheets in a thermoforming oven. The TILC adjusts the heater temperature setpoints such that, at the end of the reheat cycle, the surface temperature map of the plastic sheet will converge to the desired one. Simulation results are included to show the effectiveness of the control law.

Perceptual Robust Design

DEFF Research Database (Denmark)

Pedersen, Søren Nygaard

The research presented in this PhD thesis has focused on a perceptual approach to robust design. The results of the research and the original contribution to knowledge is a preliminary framework for understanding, positioning, and applying perceptual robust design. Product quality is a topic...... been presented. Therefore, this study set out to contribute to the understanding and application of perceptual robust design. To achieve this, a state-of-the-art and current practice review was performed. From the review two main research problems were identified. Firstly, a lack of tools...... for perceptual robustness was found to overlap with the optimum for functional robustness and at most approximately 2.2% out of the 14.74% could be ascribed solely to the perceptual robustness optimisation. In conclusion, the thesis have offered a new perspective on robust design by merging robust design...

Robust canonical correlations: A comparative study

OpenAIRE

Branco, JA; Croux, Christophe; Filzmoser, P; Oliveira, MR

2005-01-01

Several approaches for robust canonical correlation analysis will be presented and discussed. A first method is based on the definition of canonical correlation analysis as looking for linear combinations of two sets of variables having maximal (robust) correlation. A second method is based on alternating robust regressions. These methods axe discussed in detail and compared with the more traditional approach to robust canonical correlation via covariance matrix estimates. A simulation study ...

Hydrogeomechanics for rock engineering: coupling subsurface hydrogeomechanical assessement and hydrogeotechnical mapping on fracturated rock masses

OpenAIRE

Meirinhos, João Miguel de Freitas

2015-01-01

The present work aims to achieve and further develop a hydrogeomechanical approach in Caldas da Cavaca hydromineral system rock mass (Aguiar da Beira, NW Portugal), and contribute to a better understanding of the hydrogeological conceptual site model. A collection of several data, namely geology, hydrogeology, rock and soil geotechnics, borehole hydraulics and hydrogeomechanics, was retrieved from three rock slopes (Lagoa, Amores and Cancela). To accomplish a comprehensive analysis and rock e...

An overview of a possible approach to calculate rock movements due to earthquakes at Finnish nuclear waste repository sites

International Nuclear Information System (INIS)

LaPointe, P.R.; Cladouhos, T.T.

1999-02-01

The report outlines a possible approach to estimating rock movements due to earthquakes that may diminish canister safety. The method is based upon an approach developed for studying similar problems in Sweden at three generic Swedish sites. In the first part of the report, the problem of rock movements during earthquakes is described. The second section of the report outlines the approach used to estimate rock movements in Sweden, and discusses how the approach could be adapted to evaluating movements at Finnish repositories. This section also discusses data needs and potential problems in applying the approach in Finland. The next section presents some simple earthquake calculations for the four Finnish sites. These simulations use the discrete fracture network model geometric parameters developed by VTT (Technical Research Centre of Finland) for the use in hydrological calculations. The calculations are not meant for performance assessment purposes for reasons discussed in the report, but are designed to show (1) the importance of fracture size, intensity and orientation on induced displacement magnitudes; (2) the need for additional studies with regards to fracture size and intensity; and (3) the need to resolve issues regarding the role of post-glacial faulting, glacial rebound and tectonic processes in present-day and future earthquakes. (orig.)

Rock-matrix diffusion in transport of salinity. Implementation in CONNECTFLOW

International Nuclear Information System (INIS)

Hoch, A.R.; Jackson, C.P.

2004-07-01

One of the programs used for modelling groundwater flow in Swedish rocks for SKB is CONNECTFLOW, which combines the facilities of the programs NAMMU for modelling continuum porous-medium models and NAPSAC for modelling discrete fracture-networks. The version of CONNECTFLOW current at the start of the work described here did not have a capability to model rock-matrix diffusion for saline flows in continuum porous-medium models of fractured rocks. Possible approaches for implementing such an option were evaluated and then the approach that was considered to be the most suitable was implemented and tested and then used in calculations for a realistic example. Three main approaches for representing diffusion in the rock matrix were considered: the use of a numerical finite-difference scheme, an approach based on the use of Laplace transforms, and a so-called 'hybrid' approach which combines a series solution that gives a good representation at long times with an inverse square-root form that gives a good representation at small times. The finite-difference approach is the most flexible of the approaches considered. In particular, it is the only approach that can deal with the case in which, at each location in the continuum representing the fractures, the groundwater density varies within the rock matrix. The Laplace transform approach and the hybrid approach treat the diffusion in the rock matrix exactly, whereas the finite-difference approach involves discretisation errors. In particular, the unit response function is significantly in error for the first few time steps. The method that was considered to be the most appropriate to implement initially in CONNECTFLOW for SKB was the hybrid method. The algorithm was used to carry out calculations for a large site-scale model, based on the version 1.1 model of the Forsmark site in Sweden. Calculations of the evolution of the groundwater flow system from conditions 10,000 years ago to the present were carried out. The

Robust control of uncertain dynamic systems a linear state space approach

CERN Document Server

Yedavalli, Rama K

2014-01-01

This textbook aims to provide a clear understanding of the various tools of analysis and design for robust stability and performance of uncertain dynamic systems. In model-based control design and analysis, mathematical models can never completely represent the “real world” system that is being modeled, and thus it is imperative to incorporate and accommodate a level of uncertainty into the models. This book directly addresses these issues from a deterministic uncertainty viewpoint and focuses on the interval parameter characterization of uncertain systems. Various tools of analysis and design are presented in a consolidated manner. This volume fills a current gap in published works by explicitly addressing the subject of control of dynamic systems from linear state space framework, namely using a time-domain, matrix-theory based approach. This book also: Presents and formulates the robustness problem in a linear state space model framework Illustrates various systems level methodologies with examples and...

Robust Growth Determinants

OpenAIRE

Doppelhofer, Gernot; Weeks, Melvyn

2011-01-01

This paper investigates the robustness of determinants of economic growth in the presence of model uncertainty, parameter heterogeneity and outliers. The robust model averaging approach introduced in the paper uses a flexible and parsi- monious mixture modeling that allows for fat-tailed errors compared to the normal benchmark case. Applying robust model averaging to growth determinants, the paper finds that eight out of eighteen variables found to be significantly related to economic growth ...

Robust synthetic biology design: stochastic game theory approach.

Science.gov (United States)

Chen, Bor-Sen; Chang, Chia-Hung; Lee, Hsiao-Ching

2009-07-15

Synthetic biology is to engineer artificial biological systems to investigate natural biological phenomena and for a variety of applications. However, the development of synthetic gene networks is still difficult and most newly created gene networks are non-functioning due to uncertain initial conditions and disturbances of extra-cellular environments on the host cell. At present, how to design a robust synthetic gene network to work properly under these uncertain factors is the most important topic of synthetic biology. A robust regulation design is proposed for a stochastic synthetic gene network to achieve the prescribed steady states under these uncertain factors from the minimax regulation perspective. This minimax regulation design problem can be transformed to an equivalent stochastic game problem. Since it is not easy to solve the robust regulation design problem of synthetic gene networks by non-linear stochastic game method directly, the Takagi-Sugeno (T-S) fuzzy model is proposed to approximate the non-linear synthetic gene network via the linear matrix inequality (LMI) technique through the Robust Control Toolbox in Matlab. Finally, an in silico example is given to illustrate the design procedure and to confirm the efficiency and efficacy of the proposed robust gene design method. http://www.ee.nthu.edu.tw/bschen/SyntheticBioDesign_supplement.pdf.

Robust Unit Commitment Considering the Temporal and Spatial Correlations of Wind Farms Using a Data-Adaptive Approach

DEFF Research Database (Denmark)

Zhang, Yipu; Ai, Xiaomeng; Wen, Jinyu

2018-01-01

. In this paper, a novel data-adaptive robust optimization method for the unit commitment is proposed for the power system with wind farms integrated. The extreme scenario extraction and the two stage robust optimization are combined in the proposed method. The data-adaptive set consisting of a few extreme...... scenarios is derived to reduce the conservativeness by considering the temporal and spatial correlations of multiple wind farms. Numerical results demonstrate that the proposed data-adaptive robust optimization algorithm is less conservative than the current two-stage optimization approaches while maintains...

Comparison of four approaches to a rock facies classification problem

Science.gov (United States)

Dubois, M.K.; Bohling, Geoffrey C.; Chakrabarti, S.

2007-01-01

In this study, seven classifiers based on four different approaches were tested in a rock facies classification problem: classical parametric methods using Bayes' rule, and non-parametric methods using fuzzy logic, k-nearest neighbor, and feed forward-back propagating artificial neural network. Determining the most effective classifier for geologic facies prediction in wells without cores in the Panoma gas field, in Southwest Kansas, was the objective. Study data include 3600 samples with known rock facies class (from core) with each sample having either four or five measured properties (wire-line log curves), and two derived geologic properties (geologic constraining variables). The sample set was divided into two subsets, one for training and one for testing the ability of the trained classifier to correctly assign classes. Artificial neural networks clearly outperformed all other classifiers and are effective tools for this particular classification problem. Classical parametric models were inadequate due to the nature of the predictor variables (high dimensional and not linearly correlated), and feature space of the classes (overlapping). The other non-parametric methods tested, k-nearest neighbor and fuzzy logic, would need considerable improvement to match the neural network effectiveness, but further work, possibly combining certain aspects of the three non-parametric methods, may be justified. ?? 2006 Elsevier Ltd. All rights reserved.

An integrated approach to isotopic study of crystalline rock for a high-level waste repository: Area phase

International Nuclear Information System (INIS)

Gilbert, L.A.

1986-01-01

An integrated approach to assessing isotopic systems in crystalline rock is planned for area phase studies. This approach combines radiogenic isotope systems with petrography in order to characterize potential crystalline repository media. The coeval use of selected isotope systems will minimize the limitations of each method and provide intensive parameters yielding data on alteration timing, secondary mineral formation, temperature history, and radionuclide species migration. Isotope systems will be selected in order to measure differences in sensitivity to thermal disturbances and mobility due to fluid interaction. Comparative evaluation of isotope pair behavior may be used in combination with mineral versus whole-rock dates to provide data on heating and mobilization of alkali elements, lanthanides, and gases, caused by future introduction of waste

Effects of confinement on rock mass modulus: A synthetic rock mass modelling (SRM study

Directory of Open Access Journals (Sweden)

I. Vazaios

2018-06-01

Full Text Available The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks (well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints. A synthetic rock mass modelling (SRM approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method (DEM-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the pre-existing joints is generated by employing discrete fracture network (DFN modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation (RQD, joint spacing, areal fracture intensity (P21, and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index (GSI. The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness. Keywords: Synthetic rock mass modelling (SRM, Discrete fracture network (DFN, Rock mass modulus, Geological strength index (GSI, Confinement

Proportional Transaction Costs in the Robust Control Approach to Option Pricing: The Uniqueness Theorem

Energy Technology Data Exchange (ETDEWEB)

El Farouq, Naïma, E-mail: naima.elfarouq@univ-bpclermont.fr [Université Blaise Pascal (Clermont-Ferrand II) (France); Bernhard, Pierre, E-mail: pierre.bernhard@inria.fr [INRIA Sophia Antipolis-Méditerranée (France)

2015-10-15

We prove the missing uniqueness theorem for the viscosity solution of a quasi-variational inequality related to a minimax impulse control problem modeling the option pricing with proportional transactions costs. This result makes our robust control approach of option pricing in the interval market model essentially complete.

Proportional Transaction Costs in the Robust Control Approach to Option Pricing: The Uniqueness Theorem

International Nuclear Information System (INIS)

El Farouq, Naïma; Bernhard, Pierre

2015-01-01

We prove the missing uniqueness theorem for the viscosity solution of a quasi-variational inequality related to a minimax impulse control problem modeling the option pricing with proportional transactions costs. This result makes our robust control approach of option pricing in the interval market model essentially complete

Robust bladder image registration by redefining data-term in total variational approach

Science.gov (United States)

Ali, Sharib; Daul, Christian; Galbrun, Ernest; Amouroux, Marine; Guillemin, François; Blondel, Walter

2015-03-01

Cystoscopy is the standard procedure for clinical diagnosis of bladder cancer diagnosis. Bladder carcinoma in situ are often multifocal and spread over large areas. In vivo, localization and follow-up of these tumors and their nearby sites is necessary. But, due to the small field of view (FOV) of the cystoscopic video images, urologists cannot easily interpret the scene. Bladder mosaicing using image registration facilitates this interpretation through the visualization of entire lesions with respect to anatomical landmarks. The reference white light (WL) modality is affected by a strong variability in terms of texture, illumination conditions and motion blur. Moreover, in the complementary fluorescence light (FL) modality, the texture is visually different from that of the WL. Existing algorithms were developed for a particular modality and scene conditions. This paper proposes a more general on fly image registration approach for dealing with these variability issues in cystoscopy. To do so, we present a novel, robust and accurate image registration scheme by redefining the data-term of the classical total variational (TV) approach. Quantitative results on realistic bladder phantom images are used for verifying accuracy and robustness of the proposed model. This method is also qualitatively assessed with patient data mosaicing for both WL and FL modalities.

An Information Retrieval Approach for Robust Prediction of Road Surface States.

Science.gov (United States)

Park, Jae-Hyung; Kim, Kwanho

2017-01-28

Recently, due to the increasing importance of reducing severe vehicle accidents on roads (especially on highways), the automatic identification of road surface conditions, and the provisioning of such information to drivers in advance, have recently been gaining significant momentum as a proactive solution to decrease the number of vehicle accidents. In this paper, we firstly propose an information retrieval approach that aims to identify road surface states by combining conventional machine-learning techniques and moving average methods. Specifically, when signal information is received from a radar system, our approach attempts to estimate the current state of the road surface based on the similar instances observed previously based on utilizing a given similarity function. Next, the estimated state is then calibrated by using the recently estimated states to yield both effective and robust prediction results. To validate the performances of the proposed approach, we established a real-world experimental setting on a section of actual highway in South Korea and conducted a comparison with the conventional approaches in terms of accuracy. The experimental results show that the proposed approach successfully outperforms the previously developed methods.

A Phased Array Approach to Rock Blasting

Energy Technology Data Exchange (ETDEWEB)

Leslie Gertsch; Jason Baird

2006-07-01

A series of laboratory-scale simultaneous two-hole shots was performed in a rock simulant (mortar) to record the shock wave interference patterns produced in the material. The purpose of the project as a whole was to evaluate the usefulness of phased array techniques of blast design, using new high-precision delay technology. Despite high-speed photography, however, we were unable to detect the passage of the shock waves through the samples to determine how well they matched the expected interaction geometry. The follow-up mine-scale tests were therefore not conducted. Nevertheless, pattern analysis of the vectors that would be formed by positive interference of the shockwaves from multiple charges in an ideal continuous, homogeneous, isotropic medium indicate the potential for powerful control of blast design, given precise characterization of the target rock mass.

Detection of heart beats in multimodal data: a robust beat-to-beat interval estimation approach.

Science.gov (United States)

Antink, Christoph Hoog; Brüser, Christoph; Leonhardt, Steffen

2015-08-01

The heart rate and its variability play a vital role in the continuous monitoring of patients, especially in the critical care unit. They are commonly derived automatically from the electrocardiogram as the interval between consecutive heart beat. While their identification by QRS-complexes is straightforward under ideal conditions, the exact localization can be a challenging task if the signal is severely contaminated with noise and artifacts. At the same time, other signals directly related to cardiac activity are often available. In this multi-sensor scenario, methods of multimodal sensor-fusion allow the exploitation of redundancies to increase the accuracy and robustness of beat detection.In this paper, an algorithm for the robust detection of heart beats in multimodal data is presented. Classic peak-detection is augmented by robust multi-channel, multimodal interval estimation to eliminate false detections and insert missing beats. This approach yielded a score of 90.70 and was thus ranked third place in the PhysioNet/Computing in Cardiology Challenge 2014: Robust Detection of Heart Beats in Muthmodal Data follow-up analysis.In the future, the robust beat-to-beat interval estimator may directly be used for the automated processing of multimodal patient data for applications such as diagnosis support and intelligent alarming.

Multimodel Robust Control for Hydraulic Turbine

OpenAIRE

Osuský, Jakub; Števo, Stanislav

2014-01-01

The paper deals with the multimodel and robust control system design and their combination based on M-Δ structure. Controller design will be done in the frequency domain with nominal performance specified by phase margin. Hydraulic turbine model is analyzed as system with unstructured uncertainty, and robust stability condition is included in controller design. Multimodel and robust control approaches are presented in detail on hydraulic turbine model. Control design approaches are compared a...

Non-invasive multiparametric qBOLD approach for robust mapping of the oxygen extraction fraction.

Science.gov (United States)

Domsch, Sebastian; Mie, Moritz B; Wenz, Frederik; Schad, Lothar R

2014-09-01

The quantitative blood oxygenation level-dependent (qBOLD) method has not become clinically established yet because long acquisition times are necessary to achieve an acceptable certainty of the parameter estimates. In this work, a non-invasive multiparametric (nimp) qBOLD approach based on a simple analytical model is proposed to facilitate robust oxygen extraction fraction (OEF) mapping within clinically acceptable acquisition times by using separate measurements. The protocol consisted of a gradient-echo sampled spin-echo sequence (GESSE), a T2-weighted Carr-Purcell-Meiboom-Gill (CPMG) sequence, and a T2(*)-weighted multi-slice multi-echo gradient echo (MMGE) sequence. The GESSE acquisition time was less than 5 minutes and the extra measurement time for CPMG/MMGE was below 2 minutes each. The proposed nimp-qBOLD approach was validated in healthy subjects (N = 5) and one patient. The proposed nimp-qBOLD approach facilitated more robust OEF mapping with significantly reduced inter- and intra-subject variability compared to the standard qBOLD method. Thereby, an average OEF in all subjects of 27±2% in white matter (WM) and 29±2% in gray matter (GM) using the nimp-qBOLD method was more stable compared to 41±10% (WM) and 46±10% (GM) with standard qBOLD. Moreover, the spatial variance in the image slice (i.e. standard deviation divided by mean) was on average reduced from 35% to 25%. In addition, the preliminary results of the patient are encouraging. The proposed nimp-qBOLD technique provides a promising tool for robust OEF mapping within clinically acceptable acquisition times and could therefore provide an important contribution for analyzing tumors or monitoring the success of radio and chemo therapies. Copyright © 2014. Published by Elsevier GmbH.

Non-invasive multiparametric qBOLD approach for robust mapping of the oxygen extraction fraction

Energy Technology Data Exchange (ETDEWEB)

Domsch, Sebastian; Mie, Moritz B.; Schad, Lothar R. [Heidelberg Univ., Medical Faculty Mannheim (Germany). Computer Assisted Clinical Medicine; Wenz, Frederik [Heidelberg Univ., Medical Faculty Mannheim (Germany). Dept. of Radiation Oncology

2014-10-01

Introduction: The quantitative blood oxygenation level-dependent (qBOLD) method has not become clinically established yet because long acquisition times are necessary to achieve an acceptable certainty of the parameter estimates. In this work, a non-invasive multiparametric (nimp) qBOLD approach based on a simple analytical model is proposed to facilitate robust oxygen extraction fraction (OEF) mapping within clinically acceptable acquisition times by using separate measurements. Methods: The protocol consisted of a gradient-echo sampled spin-echo sequence (GESSE), a T{sub 2}-weighted Carr-Purcell-Meiboom-Gill (CPMG) sequence, and a T{sub 2}{sup *}-weighted multi-slice multi-echo gradient echo (MMGE) sequence. The GESSE acquisition time was less than 5 minutes and the extra measurement time for CPMG / MMGE was below 2 minutes each. The proposed nimp-qBOLD approach was validated in healthy subjects (N = 5) and one patient. Results: The proposed nimp-qBOLD approach facilitated more robust OEF mapping with significantly reduced inter- and intra-subject variability compared to the standard qBOLD method. Thereby, an average OEF in all subjects of 27 ± 2 % in white matter (WM) and 29 ± 2 % in gray matter (GM) using the nimp-qBOLD method was more stable compared to 41 ± 10 % (WM) and 46 ± 10 % (GM) with standard qBOLD. Moreover, the spatial variance in the image slice (i.e. standard deviation divided by mean) was on average reduced from 35 % to 25 %. In addition, the preliminary results of the patient are encouraging. Conclusion: The proposed nimp-qBOLD technique provides a promising tool for robust OEF mapping within clinically acceptable acquisition times and could therefore provide an important contribution for analyzing tumors or monitoring the success of radio and chemo therapies. (orig.)

An intrinsic robust rank-one-approximation approach for currencyportfolio optimization

Directory of Open Access Journals (Sweden)

Hongxuan Huang

2018-03-01

Full Text Available A currency portfolio is a special kind of wealth whose value fluctuates with foreignexchange rates over time, which possesses 3Vs (volume, variety and velocity properties of big datain the currency market. In this paper, an intrinsic robust rank one approximation (ROA approachis proposed to maximize the value of currency portfolios over time. The main results of the paperinclude four parts: Firstly, under the assumptions about the currency market, the currency portfoliooptimization problem is formulated as the basic model, in which there are two types of variablesdescribing currency amounts in portfolios and the amount of each currency exchanged into another,respectively. Secondly, the rank one approximation problem and its variants are also formulated toapproximate a foreign exchange rate matrix, whose performance is measured by the Frobenius normor the 2-norm of a residual matrix. The intrinsic robustness of the rank one approximation is provedtogether with summarizing properties of the basic ROA problem and designing a modified powermethod to search for the virtual exchange rates hidden in a foreign exchange rate matrix. Thirdly,a technique for decision variables reduction is presented to attack the currency portfolio optimization.The reduced formulation is referred to as the ROA model, which keeps only variables describingcurrency amounts in portfolios. The optimal solution to the ROA model also induces a feasible solutionto the basic model of the currency portfolio problem by integrating forex operations from the ROAmodel with practical forex rates. Finally, numerical examples are presented to verify the feasibility ande ciency of the intrinsic robust rank one approximation approach. They also indicate that there existsan objective measure for evaluating and optimizing currency portfolios over time, which is related tothe virtual standard currency and independent of any real currency selected specially for measurement.

Prediction of Fracture Behavior in Rock and Rock-like Materials Using Discrete Element Models

Science.gov (United States)

Katsaga, T.; Young, P.

2009-05-01

The study of fracture initiation and propagation in heterogeneous materials such as rock and rock-like materials are of principal interest in the field of rock mechanics and rock engineering. It is crucial to study and investigate failure prediction and safety measures in civil and mining structures. Our work offers a practical approach to predict fracture behaviour using discrete element models. In this approach, the microstructures of materials are presented through the combination of clusters of bonded particles with different inter-cluster particle and bond properties, and intra-cluster bond properties. The geometry of clusters is transferred from information available from thin sections, computed tomography (CT) images and other visual presentation of the modeled material using customized AutoCAD built-in dialog- based Visual Basic Application. Exact microstructures of the tested sample, including fractures, faults, inclusions and void spaces can be duplicated in the discrete element models. Although the microstructural fabrics of rocks and rock-like structures may have different scale, fracture formation and propagation through these materials are alike and will follow similar mechanics. Synthetic material provides an excellent condition for validating the modelling approaches, as fracture behaviours are known with the well-defined composite's properties. Calibration of the macro-properties of matrix material and inclusions (aggregates), were followed with the overall mechanical material responses calibration by adjusting the interfacial properties. The discrete element model predicted similar fracture propagation features and path as that of the real sample material. The path of the fractures and matrix-inclusion interaction was compared using computed tomography images. Initiation and fracture formation in the model and real material were compared using Acoustic Emission data. Analysing the temporal and spatial evolution of AE events, collected during the

Principal coordinate analysis assisted chromatographic analysis of bacterial cell wall collection: A robust classification approach.

Science.gov (United States)

Kumar, Keshav; Cava, Felipe

2018-04-10

In the present work, Principal coordinate analysis (PCoA) is introduced to develop a robust model to classify the chromatographic data sets of peptidoglycan sample. PcoA captures the heterogeneity present in the data sets by using the dissimilarity matrix as input. Thus, in principle, it can even capture the subtle differences in the bacterial peptidoglycan composition and can provide a more robust and fast approach for classifying the bacterial collection and identifying the novel cell wall targets for further biological and clinical studies. The utility of the proposed approach is successfully demonstrated by analysing the two different kind of bacterial collections. The first set comprised of peptidoglycan sample belonging to different subclasses of Alphaproteobacteria. Whereas, the second set that is relatively more intricate for the chemometric analysis consist of different wild type Vibrio Cholerae and its mutants having subtle differences in their peptidoglycan composition. The present work clearly proposes a useful approach that can classify the chromatographic data sets of chromatographic peptidoglycan samples having subtle differences. Furthermore, present work clearly suggest that PCoA can be a method of choice in any data analysis workflow. Copyright © 2018 Elsevier Inc. All rights reserved.

The Usability of Rock-Like Materials for Numerical Studies on Rocks

Science.gov (United States)

Zengin, Enes; Abiddin Erguler, Zeynal

2017-04-01

The approaches of synthetic rock material and mass are widely used by many researchers for understanding the failure behavior of different rocks. In order to model the failure behavior of rock material, researchers take advantageous of different techniques and software. But, the majority of all these instruments are based on distinct element method (DEM). For modeling the failure behavior of rocks, and so to create a fundamental synthetic rock material model, it is required to perform related laboratory experiments for providing strength parameters. In modelling studies, model calibration processes are performed by using parameters of intact rocks such as porosity, grain size, modulus of elasticity and Poisson ratio. In some cases, it can be difficult or even impossible to acquire representative rock samples for laboratory experiments from heavily jointed rock masses and vuggy rocks. Considering this limitation, in this study, it was aimed to investigate the applicability of rock-like material (e.g. concrete) to understand and model the failure behavior of rock materials having complex inherent structures. For this purpose, concrete samples having a mixture of %65 cement dust and %35 water were utilized. Accordingly, intact concrete samples representing rocks were prepared in laboratory conditions and their physical properties such as porosity, pore size and density etc. were determined. In addition, to acquire the mechanical parameters of concrete samples, uniaxial compressive strength (UCS) tests were also performed by simultaneously measuring strain during testing. The measured physical and mechanical properties of these extracted concrete samples were used to create synthetic material and then uniaxial compressive tests were modeled and performed by using two dimensional discontinuum program known as Particle Flow Code (PFC2D). After modeling studies in PFC2D, approximately similar failure mechanism and testing results were achieved from both experimental and

Robustness Beamforming Algorithms

Directory of Open Access Journals (Sweden)

Sajad Dehghani

2014-04-01

Full Text Available Adaptive beamforming methods are known to degrade in the presence of steering vector and covariance matrix uncertinity. In this paper, a new approach is presented to robust adaptive minimum variance distortionless response beamforming make robust against both uncertainties in steering vector and covariance matrix. This method minimize a optimization problem that contains a quadratic objective function and a quadratic constraint. The optimization problem is nonconvex but is converted to a convex optimization problem in this paper. It is solved by the interior-point method and optimum weight vector to robust beamforming is achieved.

Maximum volume cuboids for arbitrarily shaped in-situ rock blocks as determined by discontinuity analysis—A genetic algorithm approach

Science.gov (United States)

Ülker, Erkan; Turanboy, Alparslan

2009-07-01

The block stone industry is one of the main commercial use of rock. The economic potential of any block quarry depends on the recovery rate, which is defined as the total volume of useful rough blocks extractable from a fixed rock volume in relation to the total volume of moved material. The natural fracture system, the rock type(s) and the extraction method used directly influence the recovery rate. The major aims of this study are to establish a theoretical framework for optimising the extraction process in marble quarries for a given fracture system, and for predicting the recovery rate of the excavated blocks. We have developed a new approach by taking into consideration only the fracture structure for maximum block recovery in block quarries. The complete model uses a linear approach based on basic geometric features of discontinuities for 3D models, a tree structure (TS) for individual investigation and finally a genetic algorithm (GA) for the obtained cuboid volume(s). We tested our new model in a selected marble quarry in the town of İscehisar (AFYONKARAHİSAR—TURKEY).

Robust Sensing of Approaching Vehicles Relying on Acoustic Cues

Directory of Open Access Journals (Sweden)

Mitsunori Mizumachi

2014-05-01

Full Text Available The latest developments in automobile design have allowed them to be equipped with various sensing devices. Multiple sensors such as cameras and radar systems can be simultaneously used for active safety systems in order to overcome blind spots of individual sensors. This paper proposes a novel sensing technique for catching up and tracking an approaching vehicle relying on an acoustic cue. First, it is necessary to extract a robust spatial feature from noisy acoustical observations. In this paper, the spatio-temporal gradient method is employed for the feature extraction. Then, the spatial feature is filtered out through sequential state estimation. A particle filter is employed to cope with a highly non-linear problem. Feasibility of the proposed method has been confirmed with real acoustical observations, which are obtained by microphones outside a cruising vehicle.

A Two-Stage DEA to Analyze the Effect of Entrance Deregulation on Iranian Insurers: A Robust Approach

OpenAIRE

Jalali Naini, Seyed Gholamreza; Nouralizadeh, Hamid Reza

2012-01-01

We use two-stage data envelopment analysis (DEA) model to analyze the effects of entrance deregulation on the efficiency in the Iranian insurance market. In the first stage, we propose a robust optimization approach in order to overcome the sensitivity of DEA results to any uncertainty in the output parameters. Hence, the efficiency of each ongoing insurer is estimated using our proposed robust DEA model. The insurers are then ranked based on their relative efficiency scores for an eight-year...

Recurrent, robust and scalable patterns underlie human approach and avoidance.

Directory of Open Access Journals (Sweden)

Byoung Woo Kim

2010-05-01

Full Text Available Approach and avoidance behavior provide a means for assessing the rewarding or aversive value of stimuli, and can be quantified by a keypress procedure whereby subjects work to increase (approach, decrease (avoid, or do nothing about time of exposure to a rewarding/aversive stimulus. To investigate whether approach/avoidance behavior might be governed by quantitative principles that meet engineering criteria for lawfulness and that encode known features of reward/aversion function, we evaluated whether keypress responses toward pictures with potential motivational value produced any regular patterns, such as a trade-off between approach and avoidance, or recurrent lawful patterns as observed with prospect theory.Three sets of experiments employed this task with beautiful face images, a standardized set of affective photographs, and pictures of food during controlled states of hunger and satiety. An iterative modeling approach to data identified multiple law-like patterns, based on variables grounded in the individual. These patterns were consistent across stimulus types, robust to noise, describable by a simple power law, and scalable between individuals and groups. Patterns included: (i a preference trade-off counterbalancing approach and avoidance, (ii a value function linking preference intensity to uncertainty about preference, and (iii a saturation function linking preference intensity to its standard deviation, thereby setting limits to both.These law-like patterns were compatible with critical features of prospect theory, the matching law, and alliesthesia. Furthermore, they appeared consistent with both mean-variance and expected utility approaches to the assessment of risk. Ordering of responses across categories of stimuli demonstrated three properties thought to be relevant for preference-based choice, suggesting these patterns might be grouped together as a relative preference theory. Since variables in these patterns have been

Range and intensity vision for rock-scene segmentation

CSIR Research Space (South Africa)

Mkwelo, SG

2007-11-01

Full Text Available This paper presents another approach to segmenting a scene of rocks on a conveyor belt for the purposes of measuring rock size. Rock size estimation instruments are used to monitor, optimize and control milling and crushing in the mining industry...

MULTI-ATTRIBUTE SEISMIC/ROCK PHYSICS APPROACH TO CHARACTERIZING FRACTURED RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

Gary Mavko

2000-10-01

This project consists of three key interrelated Phases, each focusing on the central issue of imaging and quantifying fractured reservoirs, through improved integration of the principles of rock physics, geology, and seismic wave propagation. This report summarizes the results of Phase I of the project. The key to successful development of low permeability reservoirs lies in reliably characterizing fractures. Fractures play a crucial role in controlling almost all of the fluid transport in tight reservoirs. Current seismic methods to characterize fractures depend on various anisotropic wave propagation signatures that can arise from aligned fractures. We are pursuing an integrated study that relates to high-resolution seismic images of natural fractures to the rock parameters that control the storage and mobility of fluids. Our goal is to go beyond the current state-of-the art to develop and demonstrate next generation methodologies for detecting and quantitatively characterizing fracture zones using seismic measurements. Our study incorporates 3 key elements: (1) Theoretical rock physics studies of the anisotropic viscoelastic signatures of fractured rocks, including up scaling analysis and rock-fluid interactions to define the factors relating fractures in the lab and in the field. (2) Modeling of optimal seismic attributes, including offset and azimuth dependence of travel time, amplitude, impedance and spectral signatures of anisotropic fractured rocks. We will quantify the information content of combinations of seismic attributes, and the impact of multi-attribute analyses in reducing uncertainty in fracture interpretations. (3) Integration and interpretation of seismic, well log, and laboratory data, incorporating field geologic fracture characterization and the theoretical results of items 1 and 2 above. The focal point for this project is the demonstration of these methodologies in the Marathon Oil Company Yates Field in West Texas.

Solid as a rock

International Nuclear Information System (INIS)

Pincus, H.J.

1984-01-01

Recent technologic developments have required a more comprehensive approach to the behavior of rock mass or rock substance plus discontinuities than was adequate previously. This work considers the inherent problems in such operations as the storage of hot or cold fluids in caverns and aquifers, underground storage of nuclear waste, underground recovery of heat from hydrocarbon fuels, tertiary recovery of oil by thermal methods, rapid excavation of large openings at shallow to great depths and in hostile environments, and retrofitting of large structures built on or in rock. The standardization of methods for determining rock properties is essential to all of the activities described, for use not only in design and construction but also in site selection and post-construction monitoring. Development of such standards is seen as a multidisciplinary effort

Comparison of sorption measurements on argillaceous rocks and bentonite with predictions using the SGT-E2 approach to derive sorption data bases

Energy Technology Data Exchange (ETDEWEB)

Bradbury, M. H.; Baeyens, B; Marques Fernandes, M.

2014-11-15

In Stage 1 of the Sectoral Plan for Deep Geological Repositories, four rock types have been identified as being suitable host rocks for a radioactive waste repository, namely, Opalinus Clay for a high-level (HLW) and a low- and intermediate-level (L/ILW) repository, and 'Brauner Dogger', Effingen Member and Helvetic Marls for a L/ILW repository. Sorption data bases (SDBs) for all of these host rocks are required for the provisional safety analyses, including all of the bounding porewater and mineralogical composition combinations. In addition, SDBs are needed for the rock formations lying below Opalinus Clay (lower confining units) and for the bentonite backfill in the HLW repository. A detailed procedure was developed for deriving SDBs for argillaceous rocks (and bentonite) based on sorption edge measurements on illite (and montmorillonite), the hypothesis that 2:1 clay minerals are the dominant sorbents and a series of so called conversion factors which take into account the different radionuclide speciations in the different porewaters. Since this methodology for generating SDBs is relatively new, a validation and demonstration of the robustness and reliability of the sorption values derived was required. This report describes an extensive piece of work in which blind predictions of sorption values were compared with measured ones. Sorption isotherms were measured for the following metal ions Cs(I), Co(II), Ni(II), Eu(III), Th(IV) and U(VI) in a range of realistic porewater chemistries for a range of host rock mineralogies. In the end 53 isotherm data sets were measured. For each of these isotherms a prediction was made of the sorption at trace concentrations using the SDB derivation methodology. A comparison between measured and predicted values for each case was then made. This validation study shows that the methodology used for the derivation of the sorption data bases for argillaceous rocks and bentonite produces reliable sorption values. (authors)

Modeling reactive transport processes in fractured rock using the time domain random walk approach within a dual-porosity framework

Science.gov (United States)

Roubinet, D.; Russian, A.; Dentz, M.; Gouze, P.

2017-12-01

Characterizing and modeling hydrodynamic reactive transport in fractured rock are critical challenges for various research fields and applications including environmental remediation, geological storage, and energy production. To this end, we consider a recently developed time domain random walk (TDRW) approach, which is adapted to reproduce anomalous transport behaviors and capture heterogeneous structural and physical properties. This method is also very well suited to optimize numerical simulations by memory-shared massive parallelization and provide numerical results at various scales. So far, the TDRW approach has been applied for modeling advective-diffusive transport with mass transfer between mobile and immobile regions and simple (theoretical) reactions in heterogeneous porous media represented as single continuum domains. We extend this approach to dual-continuum representations considering a highly permeable fracture network embedded into a poorly permeable rock matrix with heterogeneous geochemical reactions occurring in both geological structures. The resulting numerical model enables us to extend the range of the modeled heterogeneity scales with an accurate representation of solute transport processes and no assumption on the Fickianity of these processes. The proposed model is compared to existing particle-based methods that are usually used to model reactive transport in fractured rocks assuming a homogeneous surrounding matrix, and is used to evaluate the impact of the matrix heterogeneity on the apparent reaction rates for different 2D and 3D simple-to-complex fracture network configurations.

Experimental Rock-on-Rock Abrasive Wear Under Aqueous Conditions: its Role in Subglacial Abrasion

Science.gov (United States)

Rutter, E. H.; Lee, A. G.

2003-12-01

We have determined experimentally the rate of abrasive wear of rock on rock for a range of rock types as a function of normal stress and shear displacement. Unlike abrasive wear in fault zones, where wear products accumulate as a thickening gouge zone, in our experiments wear particles were removed by flowing water. The experiments are thus directly pertinent to one of the most important processes in subglacial erosion, and to some extent in river incision. Wear was produced between rotating discs machined from rock samples and measured from the progressive approach of the disc axes towards each other under various levels of normal load. Shear displacements of several km were produced. Optical and scanning electron microscopy were used to study the worn rock surfaces, and particle size distributions in wear products were characterized using a laser particle size analyzer. Rock types studied were sandstones of various porosities and cement characteristics, schists and a granite. In all cases abrasion rate decreased logarithmically with displacement by up to 2 orders of magnitude until a steady state was approached, but only after at least 1 km displacement. The more porous, less-well cemented rocks wore fastest. Amount of abrasion could be characterized quantitatively using an exponentially decaying plus a steady-state term. Wear rate increased non-linearly with normal contact stress, apparently to an asymptote defined by the unconfined compressive strength. Microstructural study showed that the well-cemented and/or lowest porosity rocks wore by progressive abrasion of grains without plucking, whereas whole grains were plucked out of weakly-cemented and/or more porous rocks. This difference in behavior was reflected in wear-product particle size distributions. Where whole-grain plucking was possible, wear products were dominated by particles of the original grain size rather than finer rock flour. Comparison of our results to glacier basal abrasive wear estimated

Robust Learning Control Design for Quantum Unitary Transformations.

Science.gov (United States)

Wu, Chengzhi; Qi, Bo; Chen, Chunlin; Dong, Daoyi

2017-12-01

Robust control design for quantum unitary transformations has been recognized as a fundamental and challenging task in the development of quantum information processing due to unavoidable decoherence or operational errors in the experimental implementation of quantum operations. In this paper, we extend the systematic methodology of sampling-based learning control (SLC) approach with a gradient flow algorithm for the design of robust quantum unitary transformations. The SLC approach first uses a "training" process to find an optimal control strategy robust against certain ranges of uncertainties. Then a number of randomly selected samples are tested and the performance is evaluated according to their average fidelity. The approach is applied to three typical examples of robust quantum transformation problems including robust quantum transformations in a three-level quantum system, in a superconducting quantum circuit, and in a spin chain system. Numerical results demonstrate the effectiveness of the SLC approach and show its potential applications in various implementation of quantum unitary transformations.

Self-Tuning Control Scheme Based on the Robustness σ-Modification Approach

Directory of Open Access Journals (Sweden)

Nabiha Touijer

2017-01-01

Full Text Available This paper deals with the self-tuning control problem of linear systems described by autoregressive exogenous (ARX mathematical models in the presence of unmodelled dynamics. An explicit scheme of control is described, which we use a recursive algorithm on the basis of the robustness σ-modification approach to estimate the parameters of the system, to solve the problem of regulation tracking of the system. This approach was designed with the assumptions that the norm of the vector of the parameters is well-known. A new quadratic criterion is proposed to develop a modified recursive least squares (M-RLS algorithm with σ-modification. The stability condition of the proposed estimation scheme is proved using the concepts of the small gain theorem. The effectiveness and reliability of the proposed M-RLS algorithm are shown by an illustrative simulation example. The effectiveness of the described explicit self-tuning control scheme is demonstrated by simulation results of the cruise control system for a vehicle.

Robust control of nonlinear MAGLEV suspension system with mismatched uncertainties via DOBC approach.

Science.gov (United States)

Yang, Jun; Zolotas, Argyrios; Chen, Wen-Hua; Michail, Konstantinos; Li, Shihua

2011-07-01

Robust control of a class of uncertain systems that have disturbances and uncertainties not satisfying "matching" condition is investigated in this paper via a disturbance observer based control (DOBC) approach. In the context of this paper, "matched" disturbances/uncertainties stand for the disturbances/uncertainties entering the system through the same channels as control inputs. By properly designing a disturbance compensation gain, a novel composite controller is proposed to counteract the "mismatched" lumped disturbances from the output channels. The proposed method significantly extends the applicability of the DOBC methods. Rigorous stability analysis of the closed-loop system with the proposed method is established under mild assumptions. The proposed method is applied to a nonlinear MAGnetic LEViation (MAGLEV) suspension system. Simulation shows that compared to the widely used integral control method, the proposed method provides significantly improved disturbance rejection and robustness against load variation. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Robust Spatial Approximation of Laser Scanner Point Clouds by Means of Free-form Curve Approaches in Deformation Analysis

Science.gov (United States)

Bureick, Johannes; Alkhatib, Hamza; Neumann, Ingo

2016-03-01

In many geodetic engineering applications it is necessary to solve the problem of describing a measured data point cloud, measured, e. g. by laser scanner, by means of free-form curves or surfaces, e. g., with B-Splines as basis functions. The state of the art approaches to determine B-Splines yields results which are seriously manipulated by the occurrence of data gaps and outliers. Optimal and robust B-Spline fitting depend, however, on optimal selection of the knot vector. Hence we combine in our approach Monte-Carlo methods and the location and curvature of the measured data in order to determine the knot vector of the B-Spline in such a way that no oscillating effects at the edges of data gaps occur. We introduce an optimized approach based on computed weights by means of resampling techniques. In order to minimize the effect of outliers, we apply robust M-estimators for the estimation of control points. The above mentioned approach will be applied to a multi-sensor system based on kinematic terrestrial laserscanning in the field of rail track inspection.

A Knowledge-Based Approach to Robust Parsing

NARCIS (Netherlands)

Oltmans, J.A.

2000-01-01

The research presented in this thesis describes the design, implementation and evaluation of a natural-language processing system that is used as part of an information retrieval system. Specifically, I focus on the development of a system that performs robust syntactic analysis of scientific texts

Thermally induced rock stress increment and rock reinforcement response

International Nuclear Information System (INIS)

Hakala, M.; Stroem, J.; Nujiten, G.; Uotinen, L.; Siren, T.; Suikkanen, J.

2014-07-01

This report describes a detailed study of the effect of thermal heating by the spent nuclear fuel containers on the in situ rock stress, any potential rock failure, and associated rock reinforcement strategies for the Olkiluoto underground repository. The modelling approach and input data are presented together repository layout diagrams. The numerical codes used to establish the effects of heating on the in situ stress field are outlined, together with the rock mass parameters, in situ stress values, radiogenic temperatures and reinforcement structures. This is followed by a study of the temperature and stress evolution during the repository's operational period and the effect of the heating on the reinforcement structures. It is found that, during excavation, the maximum principal stress is concentrated at the transition areas where the profile changes and that, due to the heating from the deposition of spent nuclear fuel, the maximum principal stress rises significantly in the tunnel arch area of NW/SW oriented central tunnels. However, it is predicted that the rock's crack damage (CD, short term strength) value of 99 MPa will not be exceeded anywhere within the model. Loads onto the reinforcement structures will come from damaged and loosened rock which is assumed in the modelling as a free rock wedge - but this is very much a worst case scenario because there is no guarantee that rock cracking would form a free rock block. The structural capacity of the reinforcement structures is described and it is predicted that the current quantity of the rock reinforcement is strong enough to provide a stable tunnel opening during the peak of the long term stress state, with damage predicted on the sprayed concrete liner. However, the long term stability and safety can be improved through the implementation of the principles of the Observational Method. The effect of ventilation is also considered and an additional study of the radiogenic heating effect on the brittle

Thermally induced rock stress increment and rock reinforcement response

Energy Technology Data Exchange (ETDEWEB)

Hakala, M. [KMS Hakala Oy, Nokia (Finland); Stroem, J.; Nujiten, G.; Uotinen, L. [Rockplan, Helsinki (Finland); Siren, T.; Suikkanen, J.

2014-07-15

This report describes a detailed study of the effect of thermal heating by the spent nuclear fuel containers on the in situ rock stress, any potential rock failure, and associated rock reinforcement strategies for the Olkiluoto underground repository. The modelling approach and input data are presented together repository layout diagrams. The numerical codes used to establish the effects of heating on the in situ stress field are outlined, together with the rock mass parameters, in situ stress values, radiogenic temperatures and reinforcement structures. This is followed by a study of the temperature and stress evolution during the repository's operational period and the effect of the heating on the reinforcement structures. It is found that, during excavation, the maximum principal stress is concentrated at the transition areas where the profile changes and that, due to the heating from the deposition of spent nuclear fuel, the maximum principal stress rises significantly in the tunnel arch area of NW/SW oriented central tunnels. However, it is predicted that the rock's crack damage (CD, short term strength) value of 99 MPa will not be exceeded anywhere within the model. Loads onto the reinforcement structures will come from damaged and loosened rock which is assumed in the modelling as a free rock wedge - but this is very much a worst case scenario because there is no guarantee that rock cracking would form a free rock block. The structural capacity of the reinforcement structures is described and it is predicted that the current quantity of the rock reinforcement is strong enough to provide a stable tunnel opening during the peak of the long term stress state, with damage predicted on the sprayed concrete liner. However, the long term stability and safety can be improved through the implementation of the principles of the Observational Method. The effect of ventilation is also considered and an additional study of the radiogenic heating effect on the

Robust control for spacecraft rendezvous system with actuator unsymmetrical saturation: a gain scheduling approach

Science.gov (United States)

Wang, Qian; Xue, Anke

2018-06-01

This paper has proposed a robust control for the spacecraft rendezvous system by considering the parameter uncertainties and actuator unsymmetrical saturation based on the discrete gain scheduling approach. By changing of variables, we transform the actuator unsymmetrical saturation control problem into a symmetrical one. The main advantage of the proposed method is improving the dynamic performance of the closed-loop system with a region of attraction as large as possible. By the Lyapunov approach and the scheduling technology, the existence conditions for the admissible controller are formulated in the form of linear matrix inequalities. The numerical simulation illustrates the effectiveness of the proposed method.

Recurrent, Robust and Scalable Patterns Underlie Human Approach and Avoidance

Science.gov (United States)

Kennedy, David N.; Lehár, Joseph; Lee, Myung Joo; Blood, Anne J.; Lee, Sang; Perlis, Roy H.; Smoller, Jordan W.; Morris, Robert; Fava, Maurizio

2010-01-01

Background Approach and avoidance behavior provide a means for assessing the rewarding or aversive value of stimuli, and can be quantified by a keypress procedure whereby subjects work to increase (approach), decrease (avoid), or do nothing about time of exposure to a rewarding/aversive stimulus. To investigate whether approach/avoidance behavior might be governed by quantitative principles that meet engineering criteria for lawfulness and that encode known features of reward/aversion function, we evaluated whether keypress responses toward pictures with potential motivational value produced any regular patterns, such as a trade-off between approach and avoidance, or recurrent lawful patterns as observed with prospect theory. Methodology/Principal Findings Three sets of experiments employed this task with beautiful face images, a standardized set of affective photographs, and pictures of food during controlled states of hunger and satiety. An iterative modeling approach to data identified multiple law-like patterns, based on variables grounded in the individual. These patterns were consistent across stimulus types, robust to noise, describable by a simple power law, and scalable between individuals and groups. Patterns included: (i) a preference trade-off counterbalancing approach and avoidance, (ii) a value function linking preference intensity to uncertainty about preference, and (iii) a saturation function linking preference intensity to its standard deviation, thereby setting limits to both. Conclusions/Significance These law-like patterns were compatible with critical features of prospect theory, the matching law, and alliesthesia. Furthermore, they appeared consistent with both mean-variance and expected utility approaches to the assessment of risk. Ordering of responses across categories of stimuli demonstrated three properties thought to be relevant for preference-based choice, suggesting these patterns might be grouped together as a relative preference

Robust digital controllers for uncertain chaotic systems: A digital redesign approach

Energy Technology Data Exchange (ETDEWEB)

Ababneh, Mohammad [Department of Controls, FMC Kongsberg Subsea, FMC Energy Systems, Houston, TX 77067 (United States); Barajas-Ramirez, Juan-Gonzalo [CICESE, Depto. De Electronica y Telecomunicaciones, Ensenada, BC, 22860 (Mexico); Chen Guanrong [Centre for Chaos Control and Synchronization, Department of Electronic Engineering, City University of Hong Kong (China); Shieh, Leang S. [Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77204-4005 (United States)

2007-03-15

In this paper, a new and systematic method for designing robust digital controllers for uncertain nonlinear systems with structured uncertainties is presented. In the proposed method, a controller is designed in terms of the optimal linear model representation of the nominal system around each operating point of the trajectory, while the uncertainties are decomposed such that the uncertain nonlinear system can be rewritten as a set of local linear models with disturbed inputs. Applying conventional robust control techniques, continuous-time robust controllers are first designed to eliminate the effects of the uncertainties on the underlying system. Then, a robust digital controller is obtained as the result of a digital redesign of the designed continuous-time robust controller using the state-matching technique. The effectiveness of the proposed controller design method is illustrated through some numerical examples on complex nonlinear systems--chaotic systems.

Multi-wavelength approach towards on-product overlay accuracy and robustness

Science.gov (United States)

Bhattacharyya, Kaustuve; Noot, Marc; Chang, Hammer; Liao, Sax; Chang, Ken; Gosali, Benny; Su, Eason; Wang, Cathy; den Boef, Arie; Fouquet, Christophe; Huang, Guo-Tsai; Chen, Kai-Hsiung; Cheng, Kevin; Lin, John

2018-03-01

Success of diffraction-based overlay (DBO) technique1,4,5 in the industry is not just for its good precision and low toolinduced shift, but also for the measurement accuracy2 and robustness that DBO can provide. Significant efforts are put in to capitalize on the potential that DBO has to address measurement accuracy and robustness. Introduction of many measurement wavelength choices (continuous wavelength) in DBO is one of the key new capabilities in this area. Along with the continuous choice of wavelengths, the algorithms (fueled by swing-curve physics) on how to use these wavelengths are of high importance for a robust recipe setup that can avoid the impact from process stack variations (symmetric as well as asymmetric). All these are discussed. Moreover, another aspect of boosting measurement accuracy and robustness is discussed that deploys the capability to combine overlay measurement data from multiple wavelength measurements. The goal is to provide a method to make overlay measurements immune from process stack variations and also to report health KPIs for every measurement. By combining measurements from multiple wavelengths, a final overlay measurement is generated. The results show a significant benefit in accuracy and robustness against process stack variation. These results are supported by both measurement data as well as simulation from many product stacks.

Whole-rock U-Pb dating of the Shuijingtuo formation sedimentary rocks in the Yangtze Gorge

International Nuclear Information System (INIS)

Zheng, Y.F.; Huang, B.

1990-01-01

Black shale and enclosed limestone lenticule from Lower Cambrian Shuijingtuo Formation in the Yangtze Gorge is successfully dated by whole-rock U-Pb method. The results yield a concordant age of about 573±14 Ma, in excellent agreement with both stratigraphic and palaeontologic evidence. The whole-rock U-Pb method can provide a reliable approach for age determination of sedimentary stratum. (orig.) [de

Improved RMR Rock Mass Classification Using Artificial Intelligence Algorithms

Science.gov (United States)

Gholami, Raoof; Rasouli, Vamegh; Alimoradi, Andisheh

2013-09-01

Rock mass classification systems such as rock mass rating (RMR) are very reliable means to provide information about the quality of rocks surrounding a structure as well as to propose suitable support systems for unstable regions. Many correlations have been proposed to relate measured quantities such as wave velocity to rock mass classification systems to limit the associated time and cost of conducting the sampling and mechanical tests conventionally used to calculate RMR values. However, these empirical correlations have been found to be unreliable, as they usually overestimate or underestimate the RMR value. The aim of this paper is to compare the results of RMR classification obtained from the use of empirical correlations versus machine-learning methodologies based on artificial intelligence algorithms. The proposed methods were verified based on two case studies located in northern Iran. Relevance vector regression (RVR) and support vector regression (SVR), as two robust machine-learning methodologies, were used to predict the RMR for tunnel host rocks. RMR values already obtained by sampling and site investigation at one tunnel were taken into account as the output of the artificial networks during training and testing phases. The results reveal that use of empirical correlations overestimates the predicted RMR values. RVR and SVR, however, showed more reliable results, and are therefore suggested for use in RMR classification for design purposes of rock structures.

Reactive Robustness and Integrated Approaches for Railway Optimization Problems

DEFF Research Database (Denmark)

Haahr, Jørgen Thorlund

journeys helps the driver to drive efficiently and enhances robustness in a realistic (dynamic) environment. Four international scientific prizes have been awarded for distinct parts of the research during the course of this PhD project. The first prize was awarded for work during the \\2014 RAS Problem...... to absorb or withstand unexpected events such as delays. Making robust plans is central in order to maintain a safe and timely railway operation. This thesis focuses on reactive robustness, i.e., the ability to react once a plan is rendered infeasible in operation due to disruptions. In such time...... Solving Competition", where a freight yard optimization problem was considered. The second junior (PhD) prize was awared for the work performed in the \\ROADEF/EURO Challenge 2014: Trains don't vanish!", where the planning of rolling stock movements at a large station was considered. An honorable mention...

A Probabilistic Approach for Robustness Evaluation of Timber Structures

DEFF Research Database (Denmark)

Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

of Structures and a probabilistic modelling of the timber material proposed in the Probabilistic Model Code (PMC) of the Joint Committee on Structural Safety (JCSS). Due to the framework in the Danish Code the timber structure has to be evaluated with respect to the following criteria where at least one shall...... to criteria a) and b) the timber frame structure has one column with a reliability index a bit lower than an assumed target level. By removal three columns one by one no significant extensive failure of the entire structure or significant parts of it are obatined. Therefore the structure can be considered......A probabilistic based robustness analysis has been performed for a glulam frame structure supporting the roof over the main court in a Norwegian sports centre. The robustness analysis is based on the framework for robustness analysis introduced in the Danish Code of Practice for the Safety...

Robust plasmonic substrates

DEFF Research Database (Denmark)

Kostiučenko, Oksana; Fiutowski, Jacek; Tamulevicius, Tomas

2014-01-01

Robustness is a key issue for the applications of plasmonic substrates such as tip-enhanced Raman spectroscopy, surface-enhanced spectroscopies, enhanced optical biosensing, optical and optoelectronic plasmonic nanosensors and others. A novel approach for the fabrication of robust plasmonic...... substrates is presented, which relies on the coverage of gold nanostructures with diamond-like carbon (DLC) thin films of thicknesses 25, 55 and 105 nm. DLC thin films were grown by direct hydrocarbon ion beam deposition. In order to find the optimum balance between optical and mechanical properties...

A robust optimization approach for energy generation scheduling in microgrids

International Nuclear Information System (INIS)

Wang, Ran; Wang, Ping; Xiao, Gaoxi

2015-01-01

Highlights: • A new uncertainty model is proposed for better describing unstable energy demands. • An optimization problem is formulated to minimize the cost of microgrid operations. • Robust optimization algorithms are developed to transform and solve the problem. • The proposed scheme can prominently reduce energy expenses. • Numerical results provide useful insights for future investment policy making. - Abstract: In this paper, a cost minimization problem is formulated to intelligently schedule energy generations for microgrids equipped with unstable renewable sources and combined heat and power (CHP) generators. In such systems, the fluctuant net demands (i.e., the electricity demands not balanced by renewable energies) and heat demands impose unprecedented challenges. To cope with the uncertainty nature of net demand and heat demand, a new flexible uncertainty model is developed. Specifically, we introduce reference distributions according to predictions and field measurements and then define uncertainty sets to confine net and heat demands. The model allows the net demand and heat demand distributions to fluctuate around their reference distributions. Another difficulty existing in this problem is the indeterminate electricity market prices. We develop chance constraint approximations and robust optimization approaches to firstly transform and then solve the prime problem. Numerical results based on real-world data evaluate the impacts of different parameters. It is shown that our energy generation scheduling strategy performs well and the integration of combined heat and power (CHP) generators effectively reduces the system expenditure. Our research also helps shed some illuminations on the investment policy making for microgrids.

Robust Fault-Tolerant Control for Satellite Attitude Stabilization Based on Active Disturbance Rejection Approach with Artificial Bee Colony Algorithm

Directory of Open Access Journals (Sweden)

Fei Song

2014-01-01

Full Text Available This paper proposed a robust fault-tolerant control algorithm for satellite stabilization based on active disturbance rejection approach with artificial bee colony algorithm. The actuating mechanism of attitude control system consists of three working reaction flywheels and one spare reaction flywheel. The speed measurement of reaction flywheel is adopted for fault detection. If any reaction flywheel fault is detected, the corresponding fault flywheel is isolated and the spare reaction flywheel is activated to counteract the fault effect and ensure that the satellite is working safely and reliably. The active disturbance rejection approach is employed to design the controller, which handles input information with tracking differentiator, estimates system uncertainties with extended state observer, and generates control variables by state feedback and compensation. The designed active disturbance rejection controller is robust to both internal dynamics and external disturbances. The bandwidth parameter of extended state observer is optimized by the artificial bee colony algorithm so as to improve the performance of attitude control system. A series of simulation experiment results demonstrate the performance superiorities of the proposed robust fault-tolerant control algorithm.

Tectonic constraints on a deep-seated rock slide in weathered crystalline rocks

Science.gov (United States)

Borrelli, Luigi; Gullà, Giovanni

2017-08-01

Deep-seated rock slides (DSRSs), recognised as one of the most important mass wasting processes worldwide, involve large areas and cause several consequences in terms of environmental and economic damage; they result from a complex of controlling features and processes. DSRSs are common in Calabria (southern Italy) where the complex geo-structural setting plays a key role in controlling the geometry of the failure surface and its development. This paper describes an integrated multi-disciplinary approach to investigate a DSRS in Palaeozoic high-grade metamorphic rocks of the Sila Massif; it focuses on the definition of the internal structure and the predisposing factors of the Serra di Buda landslide near the town of Acri, which is a paradigm for numerous landslides in this area. An integrated interdisciplinary study based on geological, structural, and geomorphological investigations-including field observations of weathering grade of rocks, minero-petrographic characterisations, geotechnical investigations and, in particular, fifteen years of displacement monitoring-is presented. Stereoscopic analysis of aerial photographs and field observations indicate that the Serra di Buda landslide consists of two distinct compounded bodies: (i) an older and dormant body ( 7 ha) and (ii) a more recent and active body ( 13 ha) that overlies the previous one. The active landslide shows movement linked to a deep-seated translational rock slide (block slide); the velocity scale ranges from slow (1.6 m/year during paroxysmal stages) to extremely slow (affected by weathering processes that significantly reduce the rock strength and facilitate the extensive failure of the Serra di Buda landslide. Finally, the landslide's internal structure, according to geotechnical investigations and displacement monitoring, is proposed. The proposed approach and the obtained results can be generalised to typify other deep landslides in similar geological settings.

Determination of rock fragmentation based on a photographic technique

International Nuclear Information System (INIS)

Dehgan Banadaki, M.M.; Majdi, A.; Raessi Gahrooei, D.

2002-01-01

The paper represents a physical blasting model in laboratory scale along with a photographic approach to describe the distribution of blasted rock materials. For this purpose, based on wobble probability distribution function, eight samples each weighted 100 kg,were obtained. Four pictures from four different section of each sample were taken. Then, pictures were converted into graphic files with characterizing boundary of each piece of rocks in the samples. Error caused due to perspective were eliminated. Volume of each piece of the blasted rock materials and hence the required sieve size, each piece of rock to pass through, were calculated. Finally, original blasted rock size distribution was compared with that obtained from the photographic method. The paper concludes with presenting an approach to convert the results of photographic technique into size distribution obtained by seine analysis with sufficient verification

A Robust and Multi-Weighted Approach to Estimating Topographically Correlated Tropospheric Delays in Radar Interferograms

Directory of Open Access Journals (Sweden)

Bangyan Zhu

2016-07-01

Full Text Available Spatial and temporal variations in the vertical stratification of the troposphere introduce significant propagation delays in interferometric synthetic aperture radar (InSAR observations. Observations of small amplitude surface deformations and regional subsidence rates are plagued by tropospheric delays, and strongly correlated with topographic height variations. Phase-based tropospheric correction techniques assuming a linear relationship between interferometric phase and topography have been exploited and developed, with mixed success. Producing robust estimates of tropospheric phase delay however plays a critical role in increasing the accuracy of InSAR measurements. Meanwhile, few phase-based correction methods account for the spatially variable tropospheric delay over lager study regions. Here, we present a robust and multi-weighted approach to estimate the correlation between phase and topography that is relatively insensitive to confounding processes such as regional subsidence over larger regions as well as under varying tropospheric conditions. An expanded form of robust least squares is introduced to estimate the spatially variable correlation between phase and topography by splitting the interferograms into multiple blocks. Within each block, correlation is robustly estimated from the band-filtered phase and topography. Phase-elevation ratios are multiply- weighted and extrapolated to each persistent scatter (PS pixel. We applied the proposed method to Envisat ASAR images over the Southern California area, USA, and found that our method mitigated the atmospheric noise better than the conventional phase-based method. The corrected ground surface deformation agreed better with those measured from GPS.

A Robust Vehicle Localization Approach Based on GNSS/IMU/DMI/LiDAR Sensor Fusion for Autonomous Vehicles

Directory of Open Access Journals (Sweden)

Xiaoli Meng

2017-09-01

Full Text Available Precise and robust localization in a large-scale outdoor environment is essential for an autonomous vehicle. In order to improve the performance of the fusion of GNSS (Global Navigation Satellite System/IMU (Inertial Measurement Unit/DMI (Distance-Measuring Instruments, a multi-constraint fault detection approach is proposed to smooth the vehicle locations in spite of GNSS jumps. Furthermore, the lateral localization error is compensated by the point cloud-based lateral localization method proposed in this paper. Experiment results have verified the algorithms proposed in this paper, which shows that the algorithms proposed in this paper are capable of providing precise and robust vehicle localization.

A Robust Vehicle Localization Approach Based on GNSS/IMU/DMI/LiDAR Sensor Fusion for Autonomous Vehicles.

Science.gov (United States)

Meng, Xiaoli; Wang, Heng; Liu, Bingbing

2017-09-18

Precise and robust localization in a large-scale outdoor environment is essential for an autonomous vehicle. In order to improve the performance of the fusion of GNSS (Global Navigation Satellite System)/IMU (Inertial Measurement Unit)/DMI (Distance-Measuring Instruments), a multi-constraint fault detection approach is proposed to smooth the vehicle locations in spite of GNSS jumps. Furthermore, the lateral localization error is compensated by the point cloud-based lateral localization method proposed in this paper. Experiment results have verified the algorithms proposed in this paper, which shows that the algorithms proposed in this paper are capable of providing precise and robust vehicle localization.

The typology of Irish hard-rock aquifers based on an integrated hydrogeological and geophysical approach

Science.gov (United States)

Comte, Jean-Christophe; Cassidy, Rachel; Nitsche, Janka; Ofterdinger, Ulrich; Pilatova, Katarina; Flynn, Raymond

2012-12-01

Groundwater flow in hard-rock aquifers is strongly controlled by the characteristics and distribution of structural heterogeneity. A methodology for catchment-scale characterisation is presented, based on the integration of complementary, multi-scale hydrogeological, geophysical and geological approaches. This was applied to three contrasting catchments underlain by metamorphic rocks in the northern parts of Ireland (Republic of Ireland and Northern Ireland, UK). Cross-validated surface and borehole geophysical investigations confirm the discontinuous overburden, lithological compartmentalisation of the bedrock and important spatial variations of the weathered bedrock profiles at macro-scale. Fracture analysis suggests that the recent (Alpine) tectonic fabric exerts strong control on the internal aquifer structure at meso-scale, which is likely to impact on the anisotropy of aquifer properties. The combination of the interpretation of depth-specific hydraulic-test data with the structural information provided by geophysical tests allows characterisation of the hydrodynamic properties of the identified aquifer units. Regionally, the distribution of hydraulic conductivities can be described by inverse power laws specific to the aquifer litho-type. Observed groundwater flow directions reflect this multi-scale structure. The proposed integrated approach applies widely available investigative tools to identify key dominant structures controlling groundwater flow, characterising the aquifer type for each catchment and resolving the spatial distribution of relevant aquifer units and associated hydrodynamic parameters.

The participatory archive of the sites of Danish rock music culture

DEFF Research Database (Denmark)

Knudsen, Line Vestergaard

History” as an example of such a digital participatory archive. This digital online project is initiated by the Danish Rock Music Museum and intends to gather material that portray the sites’ and meeting places’ (such as venues, festivals, youth clubs etc.) of Danish rock music culture. Danish rock music......When setting out to tell the story of rock music culture, one approach is a focus at the “meeting places” where bands, fans and those behind the scenes have gathered. With this approach the cultural heritage of rock music becomes situated and site-specific, and it is nearby to think of ways...... to engage those who “inhabited” these specific sites of the previous 60 years of rock music culture. This paper will discuss how the issues of locality and rock music culture can be gathered and researched by a participatory (web 2.0) archive. The research is empirically focused at “The Map of Danish Rock...

Toward Environmentally Robust Organic Electronics: Approaches and Applications.

Science.gov (United States)

Lee, Eun Kwang; Lee, Moo Yeol; Park, Cheol Hee; Lee, Hae Rang; Oh, Joon Hak

2017-11-01

Recent interest in flexible electronics has led to a paradigm shift in consumer electronics, and the emergent development of stretchable and wearable electronics is opening a new spectrum of ubiquitous applications for electronics. Organic electronic materials, such as π-conjugated small molecules and polymers, are highly suitable for use in low-cost wearable electronic devices, and their charge-carrier mobilities have now exceeded that of amorphous silicon. However, their commercialization is minimal, mainly because of weaknesses in terms of operational stability, long-term stability under ambient conditions, and chemical stability related to fabrication processes. Recently, however, many attempts have been made to overcome such instabilities of organic electronic materials. Here, an overview is provided of the strategies developed for environmentally robust organic electronics to overcome the detrimental effects of various critical factors such as oxygen, water, chemicals, heat, and light. Additionally, molecular design approaches to π-conjugated small molecules and polymers that are highly stable under ambient and harsh conditions are explored; such materials will circumvent the need for encapsulation and provide a greater degree of freedom using simple solution-based device-fabrication techniques. Applications that are made possible through these strategies are highlighted. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rock engineering applications, 1991

International Nuclear Information System (INIS)

Franklin, J.A.; Dusseault, M.B.

1991-01-01

This book demonstrates how to apply the theories and principles of rock engineering to actual engineering and construction tasks. It features insights on geology for mining and tunnelling applications. It is practical resource that focuses on the latest technological innovation and examines up-to-date procedures used by engineers for coping with complex rock conditions. The authors also discuss question related to underground space, from design approaches to underground housing and storage. And they cover the monitoring of storage caverns for liquid and gaseous products or toxic and radioactive wastes

Strategy for a numerical Rock Mechanics Site Descriptive Model. Further development of the theoretical/numerical approach

International Nuclear Information System (INIS)

Olofsson, Isabelle; Fredriksson, Anders

2005-05-01

The Swedish Nuclear and Fuel Management Company (SKB) is conducting Preliminary Site Investigations at two different locations in Sweden in order to study the possibility of a Deep Repository for spent fuel. In the frame of these Site Investigations, Site Descriptive Models are achieved. These products are the result of an interaction of several disciplines such as geology, hydrogeology, and meteorology. The Rock Mechanics Site Descriptive Model constitutes one of these models. Before the start of the Site Investigations a numerical method using Discrete Fracture Network (DFN) models and the 2D numerical software UDEC was developed. Numerical simulations were the tool chosen for applying the theoretical approach for characterising the mechanical rock mass properties. Some shortcomings were identified when developing the methodology. Their impacts on the modelling (in term of time and quality assurance of results) were estimated to be so important that the improvement of the methodology with another numerical tool was investigated. The theoretical approach is still based on DFN models but the numerical software used is 3DEC. The main assets of the programme compared to UDEC are an optimised algorithm for the generation of fractures in the model and for the assignment of mechanical fracture properties. Due to some numerical constraints the test conditions were set-up in order to simulate 2D plane strain tests. Numerical simulations were conducted on the same data set as used previously for the UDEC modelling in order to estimate and validate the results from the new methodology. A real 3D simulation was also conducted in order to assess the effect of the '2D' conditions in the 3DEC model. Based on the quality of the results it was decided to update the theoretical model and introduce the new methodology based on DFN models and 3DEC simulations for the establishment of the Rock Mechanics Site Descriptive Model. By separating the spatial variability into two parts, one

Robust output-feedback control to eliminate stick-slip oscillations in drill-string systems

NARCIS (Netherlands)

Vromen, T.G.M.; Dai, C.H.; van de Wouw, N.; Oomen, T.A.E.; Astrid, P.; Nijmeijer, H.

2015-01-01

The aim of this paper is to design a robust output-feedback controller to eliminate torsional stick-slip vibrations. A multi-modal model of the torsional dynamics with a nonlinear bit-rock interaction model is used. The controller design is based on skewed-μ DK-iteration and the stability of the

Photogrammetric Methodology for the Production of Geomorphologic Maps: Application to the Veleta Rock Glacier (Sierra Nevada, Granada, Spain

Directory of Open Access Journals (Sweden)

José Jesús Guerrero

2009-10-01

Full Text Available In this paper we present a stereo feature-based method using SIFT (Scale-invariant feature transform descriptors. We use automatic feature extractors, matching algorithms between images and techniques of robust estimation to produce a DTM (Digital Terrain Model using convergent shots of a rock glacier.The geomorphologic structure observed in this study is the Veleta rock glacier (Sierra Nevada, Granada, Spain. This rock glacier is of high scientific interest because it is the southernmost active rock glacier in Europe and it has been analyzed every year since 2001. The research on the Veleta rock glacier is devoted to the study of its displacement and cartography through geodetic and photogrammetric techniques.

Robust Optimization Approach for Design for a Dynamic Cell Formation Considering Labor Utilization: Bi-objective Mathematical Mode

Directory of Open Access Journals (Sweden)

Hiwa Farughi

2016-05-01

Full Text Available In this paper, robust optimization of a bi-objective mathematical model in a dynamic cell formation problem considering labor utilization with uncertain data is carried out. The robust approach is used to reduce the effects of fluctuations of the uncertain parameters with regards to all the possible future scenarios. In this research, cost parameters of the cell formation and demand fluctuations are subject to uncertainty and a mixed-integer programming (MIP model is developed to formulate the related robust dynamic cell formation problem. Then the problem is transformed into a bi-objective linear one. The first objective function seeks to minimize relevant costs of the problem including machine procurement and relocation costs, machine variable cost, inter-cell movement and intra-cell movement costs, overtime cost and labor shifting cost between cells, machine maintenance cost, inventory, holding part cost. The second objective function seeks to minimize total man-hour deviations between cells or indeed labor utilization of the modeled.

Digital Rock Studies of Tight Porous Media

Energy Technology Data Exchange (ETDEWEB)

Silin, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-08-07

This technical report summarizes some recently developed approaches to studies of rock properties at a pore scale. Digital rock approach is complementary to laboratory and field studies. It can be especially helpful in situations where experimental data are uncertain, or are difficult or impossible to obtain. Digitized binary images of the pore geometries of natural rocks obtained by different imaging techniques are the input data. Computer-generated models of natural rocks can be used instead of images in a case where microtomography data are unavailable, or the resolution of the tools is insufficient to adequately characterize the features of interest. Simulations of creeping viscous flow in pores produce estimates of Darcy permeability. Maximal Inscribed Spheres calculations estimate two-phase fluid distribution in capillary equilibrium. A combination of both produce relative permeability curves. Computer-generated rock models were employed to study two-phase properties of fractured rocks, or tight sands with slit-like pores, too narrow to be characterized with micro-tomography. Various scenarios can simulate different fluid displacement mechanisms, from piston-like drainage to liquid dropout at the dew point. A finite differences discretization of Stokes equation is developed to simulate flow in the pore space of natural rocks. The numerical schemes are capable to handle both no-slip and slippage flows. An upscaling procedure estimates the permeability by subsampling a large data set. Capillary equilibrium and capillary pressure curves are efficiently estimated with the method of maximal inscribed spheres both an arbitrary contact angle. The algorithms can handle gigobytes of data on a desktop workstation. Customized QuickHull algorithms model natural rocks. Capillary pressure curves evaluated from computer-generated images mimic those obtained for microtomography data.

Statistical fracture mechanics approach to the strength of brittle rock

International Nuclear Information System (INIS)

Ratigan, J.L.

1981-06-01

Statistical fracture mechanics concepts used in the past for rock are critically reviewed and modifications are proposed which are warranted by (1) increased understanding of fracture provided by modern fracture mechanics and (2) laboratory test data both from the literature and from this research. Over 600 direct and indirect tension tests have been performed on three different rock types; Stripa Granite, Sierra White Granite and Carrara Marble. In several instances assumptions which are common in the literature were found to be invalid. A three parameter statistical fracture mechanics model with Mode I critical strain energy release rate as the variant is presented. Methodologies for evaluating the parameters in this model as well as the more commonly employed two parameter models are discussed. The experimental results and analysis of this research indicate that surfacially distributed flaws, rather than volumetrically distributed flaws are responsible for rupture in many testing situations. For several of the rock types tested, anisotropy (both in apparent tensile strength and size effect) precludes the use of contemporary statistical fracture mechanics models

Robust statistical methods with R

CERN Document Server

Jureckova, Jana

2005-01-01

Robust statistical methods were developed to supplement the classical procedures when the data violate classical assumptions. They are ideally suited to applied research across a broad spectrum of study, yet most books on the subject are narrowly focused, overly theoretical, or simply outdated. Robust Statistical Methods with R provides a systematic treatment of robust procedures with an emphasis on practical application.The authors work from underlying mathematical tools to implementation, paying special attention to the computational aspects. They cover the whole range of robust methods, including differentiable statistical functions, distance of measures, influence functions, and asymptotic distributions, in a rigorous yet approachable manner. Highlighting hands-on problem solving, many examples and computational algorithms using the R software supplement the discussion. The book examines the characteristics of robustness, estimators of real parameter, large sample properties, and goodness-of-fit tests. It...

Uncertainty Modeling and Robust Output Feedback Control of Nonlinear Discrete Systems: A Mathematical Programming Approach

Directory of Open Access Journals (Sweden)

Olav Slupphaug

2001-01-01

Full Text Available We present a mathematical programming approach to robust control of nonlinear systems with uncertain, possibly time-varying, parameters. The uncertain system is given by different local affine parameter dependent models in different parts of the state space. It is shown how this representation can be obtained from a nonlinear uncertain system by solving a set of continuous linear semi-infinite programming problems, and how each of these problems can be solved as a (finite series of ordinary linear programs. Additionally, the system representation includes control- and state constraints. The controller design method is derived from Lyapunov stability arguments and utilizes an affine parameter dependent quadratic Lyapunov function. The controller has a piecewise affine output feedback structure, and the design amounts to finding a feasible solution to a set of linear matrix inequalities combined with one spectral radius constraint on the product of two positive definite matrices. A local solution approach to this nonconvex feasibility problem is proposed. Complexity of the design method and some special cases such as state- feedback are discussed. Finally, an application of the results is given by proposing an on-line computationally feasible algorithm for constrained nonlinear state- feedback model predictive control with robust stability.

Robust Manufacturing Control

CERN Document Server

2013-01-01

This contributed volume collects research papers, presented at the CIRP Sponsored Conference Robust Manufacturing Control: Innovative and Interdisciplinary Approaches for Global Networks (RoMaC 2012, Jacobs University, Bremen, Germany, June 18th-20th 2012). These research papers present the latest developments and new ideas focusing on robust manufacturing control for global networks. Today, Global Production Networks (i.e. the nexus of interconnected material and information flows through which products and services are manufactured, assembled and distributed) are confronted with and expected to adapt to: sudden and unpredictable large-scale changes of important parameters which are occurring more and more frequently, event propagation in networks with high degree of interconnectivity which leads to unforeseen fluctuations, and non-equilibrium states which increasingly characterize daily business. These multi-scale changes deeply influence logistic target achievement and call for robust planning and control ...

Improved characterization, monitoring and instability assessment of high rock faces by integrating TLS and GB-InSAR

Science.gov (United States)

Bianchetti, Matteo; Agliardi, Federico; Villa, Alberto; Battista Crosta, Giovanni; Rivolta, Carlo

2015-04-01

spots spread over the cliff, with cm-scale cumulative displacements in the observation period. To support the interpretation and analysis of these data, we carried out multitemporal TLS surveys (5 sessions between September 2012 and October 2014) using a Riegl VZ-1000 long-range laser scanner. We performed rock mass structural analyses on dense TLS point clouds using two different approaches: 1) manual discontinuity orientation and intensity measurement from digital outcrops; 2) automatic feature extraction and intensity evaluation through the development of an original Matlab tool, suited for multi-scale applications and optimized for parallel computing. Results were validated using field discontinuity measurements and compared to evaluate advantages and limitations of different approaches, and allowed: 1) outlining the precise location, geometry and kinematics of unstable blocks and block clusters corresponding to radar moving spots; 2) performing stability analyses; 3) quantifying rockwall changes over the observation period. Our analysis provided a robust spatial characterization of rockfall sources, block size distribution and onset susceptibility as input for 3D runout modelling and quantitative risk analysis.

Water - rock interaction in different rock environments

International Nuclear Information System (INIS)

Lamminen, S.

1995-01-01

The study assesses the groundwater geochemistry and geological environment of 44 study sites for radioactive waste disposal. Initially, the study sites were divided by rock type into 5 groups: (1) acid - intermediate rocks, (2) mafic - ultramafic rocks, (3) gabbros, amphibolites and gneisses that contain calc-silicate (skarn) rocks, (4) carbonates and (5) sandstones. Separate assessments are made of acid - intermediate plutonic rocks and of a subgroup that comprises migmatites, granite and mica gneiss. These all belong to the group of acid - intermediate rocks. Within the mafic -ultramafic rock group, a subgroup that comprises mafic - ultramafic plutonic rocks, serpentinites, mafic - ultramafic volcanic rocks and volcanic - sedimentary schists is also evaluated separately. Bedrock groundwaters are classified by their concentration of total dissolved solids as fresh, brackish, saline, strongly saline and brine-class groundwaters. (75 refs., 24 figs., 3 tabs.)

Feedforward/feedback control synthesis for performance and robustness

Science.gov (United States)

Wie, Bong; Liu, Qiang

1990-01-01

Both feedforward and feedback control approaches for uncertain dynamical systems are investigated. The control design objective is to achieve a fast settling time (high performance) and robustness (insensitivity) to plant modeling uncertainty. Preshapong of an ideal, time-optimal control input using a 'tapped-delay' filter is shown to provide a rapid maneuver with robust performance. A robust, non-minimum-phase feedback controller is synthesized with particular emphasis on its proper implementation for a non-zero set-point control problem. The proposed feedforward/feedback control approach is robust for a certain class of uncertain dynamical systems, since the control input command computed for a given desired output does not depend on the plant parameters.

Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Gary Mavko

2004-11-30

Most current seismic methods to seismically characterize fractures in tight reservoirs depend on a few anisotropic wave propagation signatures that can arise from aligned fractures. While seismic anisotropy can be a powerful fracture diagnostic, a number of situations can lessen its usefulness or introduce interpretation ambiguities. Fortunately, laboratory and theoretical work in rock physics indicates that a much broader spectrum of fracture seismic signatures can occur, including a decrease in P- and S-wave velocities, a change in Poisson's ratio, an increase in velocity dispersion and wave attenuation, as well as well as indirect images of structural features that can control fracture occurrence. The goal of this project was to demonstrate a practical interpretation and integration strategy for detecting and characterizing natural fractures in rocks. The approach was to exploit as many sources of information as possible, and to use the principles of rock physics as the link among seismic, geologic, and log data. Since no single seismic attribute is a reliable fracture indicator in all situations, the focus was to develop a quantitative scheme for integrating the diverse sources of information. The integrated study incorporated three key elements: The first element was establishing prior constraints on fracture occurrence, based on laboratory data, previous field observations, and geologic patterns of fracturing. The geologic aspects include analysis of the stratigraphic, structural, and tectonic environments of the field sites. Field observations and geomechanical analysis indicates that fractures tend to occur in the more brittle facies, for example, in tight sands and carbonates. In contrast, strain in shale is more likely to be accommodated by ductile flow. Hence, prior knowledge of bed thickness and facies architecture, calibrated to outcrops, are powerful constraints on the interpreted fracture distribution. Another important constraint is that

A robust optimisation approach to the problem of supplier selection and allocation in outsourcing

Science.gov (United States)

Fu, Yelin; Keung Lai, Kin; Liang, Liang

2016-03-01

We formulate the supplier selection and allocation problem in outsourcing under an uncertain environment as a stochastic programming problem. Both the decision-maker's attitude towards risk and the penalty parameters for demand deviation are considered in the objective function. A service level agreement, upper bound for each selected supplier's allocation and the number of selected suppliers are considered as constraints. A novel robust optimisation approach is employed to solve this problem under different economic situations. Illustrative examples are presented with managerial implications highlighted to support decision-making.

Geochemical modelling of grout-groundwater-rock interactions at the seal-rock interface

International Nuclear Information System (INIS)

Alcorn, S.; Christian-Frear, T.

1992-02-01

Theoretical investigations into the longevity of repository seals have dealt primarily with the development of a methodology to evaluate interactions between portland cement-based grout and groundwater. Evaluation of chemical thermodynamic equilibria among grout, groundwater, and granitic host rock phases using the geochemical codes EQ3NR/EQ6 suggests that a fracture filled with grout and saturated with groundwater will tend to fill and 'tighten' with time. These calculations predict that some grout and rock phases will dissolve, and that there will be precipitation of secondary phases which collectively have a larger overall volume than that of the material dissolved. Model assumptions include sealing of the fracture in a sluggish hydrologic regime (low gradient) characterized by a saline groundwater environment. The results of the calculations suggest that buffering of the fracture seals chemical system by the granitic rock may be important in determining the long-term fate of grout seals and the resulting phase assemblage in the fracture. The similarity of the predicted reaction product phases to those observed in naturally filled fractures suggests that with time equilibrium will be approached and grouted fractures subject to low hydrologic gradients will continue to seal. If grout injected into fractures materially reduces groundwater flux, the approach to chemical equilibrium will likely be accelerated. In light of this, even very thin or imperfectly grouted fractures would tighten in suitable hydrogeologic environments. In order to determine the period of time necessary to approach equilibrium, data on reaction rates are required. (au)

A robust anti-windup design procedure for SISO systems

Science.gov (United States)

Kerr, Murray; Turner, Matthew C.; Villota, Elizabeth; Jayasuriya, Suhada; Postlethwaite, Ian

2011-02-01

A model-based anti-windup (AW) controller design approach for constrained uncertain linear single-input-single-output (SISO) systems is proposed based on quantitative feedback theory (QFT) loopshaping. The design approach explicitly incorporates uncertainty, is suitable for the solution of both the magnitude and rate saturation problems, and provides for the design of low-order AW controllers satisfying robust stability and robust performance objectives. Robust stability is enforced using absolute stability theory and generic multipliers (i.e. circle, Popov, Zames-Falb), and robust performance is enforced using linear lower-bounds on the input-output maps capturing the effects of saturation as a metric. Two detailed design examples are presented. These show that even for simple systems, certain popular AW techniques lead to compensators that may fail to ensure robust stability and performance when saturation is encountered, but that the proposed QFT design approach is able to handle both saturation and uncertainty effectively.

Reactive solute transport in an asymmetrical fracture-rock matrix system

Science.gov (United States)

Zhou, Renjie; Zhan, Hongbin

2018-02-01

The understanding of reactive solute transport in a single fracture-rock matrix system is the foundation of studying transport behavior in the complex fractured porous media. When transport properties are asymmetrically distributed in the adjacent rock matrixes, reactive solute transport has to be considered as a coupled three-domain problem, which is more complex than the symmetric case with identical transport properties in the adjacent rock matrixes. This study deals with the transport problem in a single fracture-rock matrix system with asymmetrical distribution of transport properties in the rock matrixes. Mathematical models are developed for such a problem under the first-type and the third-type boundary conditions to analyze the spatio-temporal concentration and mass distribution in the fracture and rock matrix with the help of Laplace transform technique and de Hoog numerical inverse Laplace algorithm. The newly acquired solutions are then tested extensively against previous analytical and numerical solutions and are proven to be robust and accurate. Furthermore, a water flushing phase is imposed on the left boundary of system after a certain time. The diffusive mass exchange along the fracture/rock matrixes interfaces and the relative masses stored in each of three domains (fracture, upper rock matrix, and lower rock matrix) after the water flushing provide great insights of transport with asymmetric distribution of transport properties. This study has the following findings: 1) Asymmetric distribution of transport properties imposes greater controls on solute transport in the rock matrixes. However, transport in the fracture is mildly influenced. 2) The mass stored in the fracture responses quickly to water flushing, while the mass stored in the rock matrix is much less sensitive to the water flushing. 3) The diffusive mass exchange during the water flushing phase has similar patterns under symmetric and asymmetric cases. 4) The characteristic distance

Design of Rock Slope Reinforcement: An Himalayan Case Study

Science.gov (United States)

Tiwari, Gaurav; Latha, Gali Madhavi

2016-06-01

The stability analysis of the two abutment slopes of a railway bridge proposed at about 359 m above the ground level, crossing a river and connecting two hill faces in the Himalayas, India, is presented. The bridge is located in a zone of high seismic activity. The rock slopes are composed of a heavily jointed rock mass and the spacing, dip and dip direction of joint sets are varying at different locations. Geological mapping was carried out to characterize all discontinuities present along the slopes. Laboratory and field investigations were conducted to assess the geotechnical properties of the intact rock, rock mass and joint infill. Stability analyses of these rock slopes were carried out using numerical programmes. Loads from the foundations resting on the slopes and seismic accelerations estimated from site-specific ground response analysis were considered. The proposed slope profile with several berms between successive foundations was simulated in the numerical model. An equivalent continuum approach with Hoek and Brown failure criterion was initially used in a finite element model to assess the global stability of the slope abutments. In the second stage, finite element analysis of rock slopes with all joint sets with their orientations, spacing and properties explicitly incorporated into the numerical model was taken up using continuum with joints approach. It was observed that the continuum with joints approach was able to capture the local failures in some of the slope sections, which were verified using wedge failure analysis and stereographic projections. Based on the slope deformations and failure patterns observed from the numerical analyses, rock anchors were designed to achieve the target factors of safety against failure while keeping the deformations within the permissible limits. Detailed design of rock anchors and comparison of the stability of slopes with and without reinforcement are presented.

Gas migration in argillaceous rock

International Nuclear Information System (INIS)

Alonso, E. E.; Olivella, S.

2007-01-01

The intrinsic gas permeability of fractured argillaceous rocks depends on the current structure of micro-cracks and fissures of the rock. They are a consequence of the initial state and the subsequent deformations induced by stress and gas pressure changes. Stresses are also coupled with fluid pressures and, therefore, gas flow and mechanical behaviour are intensely coupled. Laboratory experiments, aimed at determining intrinsic permeability, show the relevant effect of volumetric deformations induced by isotropic, as well as deviatoric stress changes. The relevance, in practice, of the flow-mechanical coupling is illustrated by means of some results obtained during the performance of the drift scale test (DST) in fractured tuff in the Yucca Mountain facility. The technique of embedding discontinuities in continuum thermo-hydro-mechanical elements is capable of reproducing observed features of gas flow migration in clayey rocks. An example is described. It is believed that the developed approach provides a powerful computational procedure to handle complex gas phenomena in clayey rocks. (author)

Robust facility location: Hedging against failures

International Nuclear Information System (INIS)

Hernandez, Ivan; Emmanuel Ramirez-Marquez, Jose; Rainwater, Chase; Pohl, Edward; Medal, Hugh

2014-01-01

While few companies would be willing to sacrifice day-to-day operations to hedge against disruptions, designing for robustness can yield solutions that perform well before and after failures have occurred. Through a multi-objective optimization approach this paper provides decision makers the option to trade-off total weighted distance before and after disruptions in the Facility Location Problem. Additionally, this approach allows decision makers to understand the impact on the opening of facilities on total distance and on system robustness (considering the system as the set of located facilities). This approach differs from previous studies in that hedging against failures is done without having to elicit facility failure probabilities concurrently without requiring the allocation of additional hardening/protections resources. The approach is applied to two datasets from the literature

The Variation Management Framework (VMF) for Robust Design

DEFF Research Database (Denmark)

Howard, Thomas J.; Ebro, Martin; Eifler, Tobias

2014-01-01

Robust Design is an approach to reduce the effects of variation. There are numerous tools,methods and models associated with robust design, however, there is both a lack of a processmodel formalising the step of a robust design process and a framework tying the models together.In this paper we pr...... in the market place and identifies areaswhere action can be taken against variation. An additional benefit of the framework is that itmakes the link between visual/sensory/perceptual robustness, product robustness, and productionvariation (Six Sigma)....

Geological and rock mechanics aspects of the long-term evolution of a crystalline rock site

International Nuclear Information System (INIS)

Cosgrove, J.W.; Hudson, J.A.

2009-01-01

We consider the stability of a crystalline rock mass and hence the integrity of a radioactive waste repository contained therein by, firstly, identifying the geological evolution of such a site and, secondly, by assessing the likely rock mechanics consequences of the natural perturbations to the repository. In this way, the potency of an integrated geological-rock mechanics approach is demonstrated. The factors considered are the pre-repository geological evolution, the period of repository excavation, emplacement and closure, and the subsequent degradation and natural geological perturbations introduced by glacial loading. It is found that the additional rock stresses associated with glacial advance and retreat have a first order effect on the stress magnitudes and are likely to cause a radical change in the stress regime. There are many factors involved in the related geosphere stability and so the paper concludes with a systems diagram of the total evolutionary considerations before, during and after repository construction. (authors)

A Rock Mechanics and Coupled Hydro mechanical Analysis of Geological Repository of High Level Nuclear Waste in Fractured Rocks

International Nuclear Information System (INIS)

Min, Kibok

2011-01-01

This paper introduces a few case studies on fractured hard rock based on geological data from Sweden, Korea is one of a few countries where crystalline rock is the most promising rock formation as a candidate site of geological repository of high level nuclear waste. Despite the progress made in the area of rock mechanics and coupled hydro mechanics, extensive site specific study on multiple candidate sites is essential in order to choose the optimal site. For many countries concerned about the safe isolation of nuclear wastes from the biosphere, disposal in a deep geological formation is considered an attractive option. In geological repository, thermal loading continuously disturbs the repository system in addition to disturbances a recent development in rock mechanics and coupled hydro mechanical study using DFN(Discrete Fracture Network) - DEM(Discrete Element Method) approach mainly applied in hard, crystalline rock containing numerous fracture which are main sources of deformation and groundwater flow

Real-time control systems: feedback, scheduling and robustness

Science.gov (United States)

Simon, Daniel; Seuret, Alexandre; Sename, Olivier

2017-08-01

The efficient control of real-time distributed systems, where continuous components are governed through digital devices and communication networks, needs a careful examination of the constraints arising from the different involved domains inside co-design approaches. Thanks to the robustness of feedback control, both new control methodologies and slackened real-time scheduling schemes are proposed beyond the frontiers between these traditionally separated fields. A methodology to design robust aperiodic controllers is provided, where the sampling interval is considered as a control variable of the system. Promising experimental results are provided to show the feasibility and robustness of the approach.

Interval Analysis Approach to Prototype the Robust Control of the Laboratory Overhead Crane

Science.gov (United States)

Smoczek, J.; Szpytko, J.; Hyla, P.

2014-07-01

The paper describes the software-hardware equipment and control-measurement solutions elaborated to prototype the laboratory scaled overhead crane control system. The novelty approach to crane dynamic system modelling and fuzzy robust control scheme design is presented. The iterative procedure for designing a fuzzy scheduling control scheme is developed based on the interval analysis of discrete-time closed-loop system characteristic polynomial coefficients in the presence of rope length and mass of a payload variation to select the minimum set of operating points corresponding to the midpoints of membership functions at which the linear controllers are determined through desired poles assignment. The experimental results obtained on the laboratory stand are presented.

Interval Analysis Approach to Prototype the Robust Control of the Laboratory Overhead Crane

International Nuclear Information System (INIS)

Smoczek, J; Szpytko, J; Hyla, P

2014-01-01

The paper describes the software-hardware equipment and control-measurement solutions elaborated to prototype the laboratory scaled overhead crane control system. The novelty approach to crane dynamic system modelling and fuzzy robust control scheme design is presented. The iterative procedure for designing a fuzzy scheduling control scheme is developed based on the interval analysis of discrete-time closed-loop system characteristic polynomial coefficients in the presence of rope length and mass of a payload variation to select the minimum set of operating points corresponding to the midpoints of membership functions at which the linear controllers are determined through desired poles assignment. The experimental results obtained on the laboratory stand are presented

Efficient reanalysis techniques for robust topology optimization

DEFF Research Database (Denmark)

Amir, Oded; Sigmund, Ole; Lazarov, Boyan Stefanov

2012-01-01

efficient robust topology optimization procedures based on reanalysis techniques. The approach is demonstrated on two compliant mechanism design problems where robust design is achieved by employing either a worst case formulation or a stochastic formulation. It is shown that the time spent on finite...

Quasipolynomial Approach to Simultaneous Robust Control of Time-Delay Systems

Directory of Open Access Journals (Sweden)

Nikolaj Semenič

2014-01-01

Full Text Available A control law for retarded time-delay systems is considered, concerning infinite closed-loop spectrum assignment. An algebraic method for spectrum assignment is presented with a unique optimization algorithm for minimization of spectral abscissa and effective shaping of the chains of infinitely many closed-loop poles. Uncertainty of plant delays of a certain structure is considered in a sense of a robust simultaneous stabilization. Robust performance is achieved using mixed sensitivity design, which is incorporated into the addressed control law.

A microfluidic approach to water-rock interactions using thin rock sections: Pb and U sorption onto thin shale and granite sections

Energy Technology Data Exchange (ETDEWEB)

Oh, Youn Soo [Institute of Mine Reclamation Technology, Mine Reclamation Corp., 2 Segye-ro, Wonju-si, Gangwon-do, 26464 (Korea, Republic of); Jo, Ho Young, E-mail: hyjo@korea.ac.kr [Department of Earth and Environmental Sciences, Korea University, Anam-dong, Seongbuk-gu, Seoul, 02841 (Korea, Republic of); Ryu, Ji-Hun; Kim, Geon-Young [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon, 34057 (Korea, Republic of)

2017-02-15

Highlights: • Microfluidic tests was used to investigate water-rock (mineral) interactions. • Pb and U sorption onto thin shale and granite sections was evaluated. • Pb removal by thin shale section is related primarily to Fe-containing minerals. • A slightly larger amount of U was removed onto the thin granite section with Fe-containing minerals. - Abstract: The feasibility of using microfluidic tests to investigate water-rock (mineral) interactions in fractures regarding sorption onto thin rock sections (i.e., shale and granite) of lead (Pb) and uranium (U) was evaluated using a synthetic PbCl{sub 2} solution and uranium-containing natural groundwater as fluids. Effluent composition and element distribution on the thin rock sections before and after microfluidic testing were analyzed. Most Pb removal (9.8 mg/cm{sup 2}) occurred within 3.5 h (140 PVF), which was 74% of the total Pb removal (13.2 mg/cm{sup 2}) at the end of testing (14.5 h, 560 PVF). Element composition on the thin shale sections determined by μ-XRF analysis indicated that Pb removal was related primarily to Fe-containing minerals (e.g., pyrite). Two thin granite sections (biotite rich, Bt-R and biotite poor, Bt-P) exhibited no marked difference in uranium removal capacity, but a slightly higher amount of uranium was removed onto the thin Bt-R section (266 μg/cm{sup 2}) than the thin Bt-P section (240 μg/cm{sup 2}) within 120 h (4800 PVF). However, uranium could not be detected by micro X-ray fluorescence (μ-XRF) analysis, likely due to the detection limit. These results suggest that microfluidic testing on thin rock sections enables quantitative evaluation of rock (mineral)-water interactions at the micro-fracture or pore scale.

Thermal Inertia of Rocks and Rock Populations

Science.gov (United States)

Golombek, M. P.; Jakosky, B. M.; Mellon, M. T.

2001-01-01

The effective thermal inertia of rock populations on Mars and Earth is derived from a model of effective inertia versus rock diameter. Results allow a parameterization of the effective rock inertia versus rock abundance and bulk and fine component inertia. Additional information is contained in the original extended abstract.

Using a Robust Design Approach to Optimize Chair Set-up in Wheelchair Sport

Directory of Open Access Journals (Sweden)

David S. Haydon

2018-02-01

Full Text Available Optimisation of wheelchairs for court sports is currently a difficult and time-consuming process due to the broad range of impairments across athletes, difficulties in monitoring on-court performance, and the trade-off set-up that parameters have on key performance variables. A robust design approach to this problem can potentially reduce the amount of testing required, and therefore allow for individual on-court assessments. This study used orthogonal design with four set-up factors (seat height, depth, and angle, as well as tyre pressure at three levels (current, decreased, and increased for three elite wheelchair rugby players. Each player performed two maximal effort sprints from a stationary position in nine different set-ups, with this allowing for detailed analysis of each factor and level. Whilst statistical significance is difficult to obtain due to the small sample size, meaningful difference results aligning with previous research findings were identified and provide support for the use of this approach.

The robust corrective action priority-an improved approach for selecting competing corrective actions in FMEA based on principle of robust design

Science.gov (United States)

Sutrisno, Agung; Gunawan, Indra; Vanany, Iwan

2017-11-01

In spite of being integral part in risk - based quality improvement effort, studies improving quality of selection of corrective action priority using FMEA technique are still limited in literature. If any, none is considering robustness and risk in selecting competing improvement initiatives. This study proposed a theoretical model to select risk - based competing corrective action by considering robustness and risk of competing corrective actions. We incorporated the principle of robust design in counting the preference score among corrective action candidates. Along with considering cost and benefit of competing corrective actions, we also incorporate the risk and robustness of corrective actions. An example is provided to represent the applicability of the proposed model.

Simulation of fluid flow in fractured rock: a probabilistic approach

International Nuclear Information System (INIS)

Samaniego, J.A.; Priest, S.D.

1985-02-01

This report describes the results of a research project designed to investigate the influence of discontinuities on fluid flow through fractured rock masses. The aim has been to provide a rational basis for the assessment of prospective intermediate level radioactive waste repository sites. The results of this work are presented in the form of two groups of FORTRAN computer programs. The first of these is designed to process data obtained from exposed rock faces and thereby provide an unbiased estimate of discontinuity characteristics. The resulting data are input to the second group of programs which generate a two-dimensional random realisation of discontinuity geometry. When appropriate boundary conditions have been specified, the resulting network of channels is solved numerically to determine nodal potentials, flow quantities and equivalent permeabilities. A number of validation runs are presented, together with some parametric studies, to investigate the influence of excavation size and discontinuity geometry on fluid flow. A practical application is given in the form of a case study involving the prediction of fluid flow into a 2.8 m diameter tunnel in water bearing, fractured rock. Finally, the applications and limitations of the programs in site assessment for radioactive waste repositories are discussed. (author)

Integration of rock typing methods for carbonate reservoir characterization

International Nuclear Information System (INIS)

Aliakbardoust, E; Rahimpour-Bonab, H

2013-01-01

Reservoir rock typing is the most important part of all reservoir modelling. For integrated reservoir rock typing, static and dynamic properties need to be combined, but sometimes these two are incompatible. The failure is due to the misunderstanding of the crucial parameters that control the dynamic behaviour of the reservoir rock and thus selecting inappropriate methods for defining static rock types. In this study, rock types were defined by combining the SCAL data with the rock properties, particularly rock fabric and pore types. First, air-displacing-water capillary pressure curues were classified because they are representative of fluid saturation and behaviour under capillary forces. Next the most important rock properties which control the fluid flow and saturation behaviour (rock fabric and pore types) were combined with defined classes. Corresponding petrophysical properties were also attributed to reservoir rock types and eventually, defined rock types were compared with relative permeability curves. This study focused on representing the importance of the pore system, specifically pore types in fluid saturation and entrapment in the reservoir rock. The most common tests in static rock typing, such as electrofacies analysis and porosity–permeability correlation, were carried out and the results indicate that these are not appropriate approaches for reservoir rock typing in carbonate reservoirs with a complicated pore system. (paper)

Robust-mode analysis of hydrodynamic flows

Science.gov (United States)

Roy, Sukesh; Gord, James R.; Hua, Jia-Chen; Gunaratne, Gemunu H.

2017-04-01

The emergence of techniques to extract high-frequency high-resolution data introduces a new avenue for modal decomposition to assess the underlying dynamics, especially of complex flows. However, this task requires the differentiation of robust, repeatable flow constituents from noise and other irregular features of a flow. Traditional approaches involving low-pass filtering and principle components analysis have shortcomings. The approach outlined here, referred to as robust-mode analysis, is based on Koopman decomposition. Three applications to (a) a counter-rotating cellular flame state, (b) variations in financial markets, and (c) turbulent injector flows are provided.

Stabilization and regulation of nonlinear systems a robust and adaptive approach

CERN Document Server

Chen, Zhiyong

2015-01-01

The core of this textbook is a systematic and self-contained treatment of the nonlinear stabilization and output regulation problems. Its coverage embraces both fundamental concepts and advanced research outcomes and includes many numerical and practical examples. Several classes of important uncertain nonlinear systems are discussed. The state-of-the art solution presented uses robust and adaptive control design ideas in an integrated approach which demonstrates connections between global stabilization and global output regulation allowing both to be treated as stabilization problems. Stabilization and Regulation of Nonlinear Systems takes advantage of rich new results to give students up-to-date instruction in the central design problems of nonlinear control, problems which are a driving force behind the furtherance of modern control theory and its application. The diversity of systems in which stabilization and output regulation become significant concerns in the mathematical formulation of practical contr...

Biologically inspired control of humanoid robot arms robust and adaptive approaches

CERN Document Server

Spiers, Adam; Herrmann, Guido

2016-01-01

This book investigates a biologically inspired method of robot arm control, developed with the objective of synthesising human-like motion dynamically, using nonlinear, robust and adaptive control techniques in practical robot systems. The control method caters to a rising interest in humanoid robots and the need for appropriate control schemes to match these systems. Unlike the classic kinematic schemes used in industrial manipulators, the dynamic approaches proposed here promote human-like motion with better exploitation of the robot’s physical structure. This also benefits human-robot interaction. The control schemes proposed in this book are inspired by a wealth of human-motion literature that indicates the drivers of motion to be dynamic, model-based and optimal. Such considerations lend themselves nicely to achievement via nonlinear control techniques without the necessity for extensive and complex biological models. The operational-space method of robot control forms the basis of many of the techniqu...

Neural networks, cellular automata, and robust approach applications for vertex localization in the opera target tracker detector

International Nuclear Information System (INIS)

Dmitrievskij, S.G.; Gornushkin, Yu.A.; Ososkov, G.A.

2005-01-01

A neural-network (NN) approach for neutrino interaction vertex reconstruction in the OPERA experiment with the help of the Target Tracker (TT) detector is described. A feed-forward NN with the standard back propagation option is used. The energy functional minimization of the network is performed by the method of conjugate gradients. Data preprocessing by means of cellular automaton algorithm is performed. The Hough transform is applied for muon track determination and the robust fitting method is used for shower axis reconstruction. A comparison of the proposed approach with earlier studies, based on the use of the neural network package SNNS, shows their similar performance. The further development of the approach is underway

A robust approach based on Weibull distribution for clustering gene expression data

Directory of Open Access Journals (Sweden)

Gong Binsheng

2011-05-01

Full Text Available Abstract Background Clustering is a widely used technique for analysis of gene expression data. Most clustering methods group genes based on the distances, while few methods group genes according to the similarities of the distributions of the gene expression levels. Furthermore, as the biological annotation resources accumulated, an increasing number of genes have been annotated into functional categories. As a result, evaluating the performance of clustering methods in terms of the functional consistency of the resulting clusters is of great interest. Results In this paper, we proposed the WDCM (Weibull Distribution-based Clustering Method, a robust approach for clustering gene expression data, in which the gene expressions of individual genes are considered as the random variables following unique Weibull distributions. Our WDCM is based on the concept that the genes with similar expression profiles have similar distribution parameters, and thus the genes are clustered via the Weibull distribution parameters. We used the WDCM to cluster three cancer gene expression data sets from the lung cancer, B-cell follicular lymphoma and bladder carcinoma and obtained well-clustered results. We compared the performance of WDCM with k-means and Self Organizing Map (SOM using functional annotation information given by the Gene Ontology (GO. The results showed that the functional annotation ratios of WDCM are higher than those of the other methods. We also utilized the external measure Adjusted Rand Index to validate the performance of the WDCM. The comparative results demonstrate that the WDCM provides the better clustering performance compared to k-means and SOM algorithms. The merit of the proposed WDCM is that it can be applied to cluster incomplete gene expression data without imputing the missing values. Moreover, the robustness of WDCM is also evaluated on the incomplete data sets. Conclusions The results demonstrate that our WDCM produces clusters

Prediction of thermal conductivity of sedimentary rocks from well logs

DEFF Research Database (Denmark)

Fuchs, Sven; Förster, Andrea

2014-01-01

The calculation of heat-flow density in boreholes requires reliable values for the change of temperature and rock thermal conductivity with depth. As rock samples for laboratory measurements of thermal conductivity (TC) are usually rare geophysical well logs are used alternatively to determine TC...... parameters (i.e. thermal conductivity, density, hydrogen index, sonic interval transit time, gamma-ray response, photoelectric factor) of artificial mineral assemblages consisting 15 rock-forming minerals that are used in different combinations to typify sedimentary rocks. The predictive capacity of the new...... equations is evaluated on subsurface data from four boreholes drilled into the Mesozoic sequence of the North German Basin, including more than 1700 laboratory-measured thermal-conductivity values. Results are compared with those from other approaches published in the past. The new approach predicts TC...

Deformation mechanisms in a coal mine roadway in extremely swelling soft rock.

Science.gov (United States)

Li, Qinghai; Shi, Weiping; Yang, Renshu

2016-01-01

The problem of roadway support in swelling soft rock was one of the challenging problems during mining. For most geological conditions, combinations of two or more supporting approaches could meet the requirements of most roadways; however, in extremely swelling soft rock, combined approaches even could not control large deformations. The purpose of this work was to probe the roadway deformation mechanisms in extremely swelling soft rock. Based on the main return air-way in a coal mine, deformation monitoring and geomechanical analysis were conducted, as well as plastic zone mechanical model was analysed. Results indicated that this soft rock was potentially very swelling. When the ground stress acted alone, the support strength needed in situ was not too large and combined supporting approaches could meet this requirement; however, when this potential released, the roadway would undergo permanent deformation. When the loose zone reached 3 m within surrounding rock, remote stress p ∞ and supporting stress P presented a linear relationship. Namely, the greater the swelling stress, the more difficult it would be in roadway supporting. So in this extremely swelling soft rock, a better way to control roadway deformation was to control the releasing of surrounding rock's swelling potential.

Towards a realistic approach to validation of reactive transport models for performance assessment

International Nuclear Information System (INIS)

Siegel, M.D.

1993-01-01

Performance assessment calculations are based on geochemical models that assume that interactions among radionuclides, rocks and groundwaters under natural conditions, can be estimated or bound by data obtained from laboratory-scale studies. The data include radionuclide distribution coefficients, measured in saturated batch systems of powdered rocks, and retardation factors measured in short-term column experiments. Traditional approaches to model validation cannot be applied in a straightforward manner to the simple reactive transport models that use these data. An approach to model validation in support of performance assessment is described in this paper. It is based on a recognition of different levels of model validity and is compatible with the requirements of current regulations for high-level waste disposal. Activities that are being carried out in support of this approach include (1) laboratory and numerical experiments to test the validity of important assumptions inherent in current performance assessment methodologies,(2) integrated transport experiments, and (3) development of a robust coupled reaction/transport code for sensitivity analyses using massively parallel computers

A robust and efficient approach to detect 3D rectal tubes from CT colonography

Energy Technology Data Exchange (ETDEWEB)

Yang Xiaoyun; Slabaugh, Greg [Medicsight PLC, Kensington Centre, 66 Hammersmith Road, London (United Kingdom)

2011-11-15

Purpose: The rectal tube (RT) is a common source of false positives (FPs) in computer-aided detection (CAD) systems for CT colonography. A robust and efficient detection of RT can improve CAD performance by eliminating such ''obvious'' FPs and increase radiologists' confidence in CAD. Methods: In this paper, we present a novel and robust bottom-up approach to detect the RT. Probabilistic models, trained using kernel density estimation on simple low-level features, are employed to rank and select the most likely RT tube candidate on each axial slice. Then, a shape model, robustly estimated using random sample consensus (RANSAC), infers the global RT path from the selected local detections. Subimages around the RT path are projected into a subspace formed from training subimages of the RT. A quadratic discriminant analysis (QDA) provides a classification of a subimage as RT or non-RT based on the projection. Finally, a bottom-top clustering method is proposed to merge the classification predictions together to locate the tip position of the RT. Results: Our method is validated using a diverse database, including data from five hospitals. On a testing data with 21 patients (42 volumes), 99.5% of annotated RT paths have been successfully detected. Evaluated with CAD, 98.4% of FPs caused by the RT have been detected and removed without any loss of sensitivity. Conclusions: The proposed method demonstrates a high detection rate of the RT path, and when tested in a CAD system, reduces FPs caused by the RT without the loss of sensitivity.

A robust and efficient approach to detect 3D rectal tubes from CT colonography

International Nuclear Information System (INIS)

Yang Xiaoyun; Slabaugh, Greg

2011-01-01

Purpose: The rectal tube (RT) is a common source of false positives (FPs) in computer-aided detection (CAD) systems for CT colonography. A robust and efficient detection of RT can improve CAD performance by eliminating such ''obvious'' FPs and increase radiologists' confidence in CAD. Methods: In this paper, we present a novel and robust bottom-up approach to detect the RT. Probabilistic models, trained using kernel density estimation on simple low-level features, are employed to rank and select the most likely RT tube candidate on each axial slice. Then, a shape model, robustly estimated using random sample consensus (RANSAC), infers the global RT path from the selected local detections. Subimages around the RT path are projected into a subspace formed from training subimages of the RT. A quadratic discriminant analysis (QDA) provides a classification of a subimage as RT or non-RT based on the projection. Finally, a bottom-top clustering method is proposed to merge the classification predictions together to locate the tip position of the RT. Results: Our method is validated using a diverse database, including data from five hospitals. On a testing data with 21 patients (42 volumes), 99.5% of annotated RT paths have been successfully detected. Evaluated with CAD, 98.4% of FPs caused by the RT have been detected and removed without any loss of sensitivity. Conclusions: The proposed method demonstrates a high detection rate of the RT path, and when tested in a CAD system, reduces FPs caused by the RT without the loss of sensitivity.

Big rock point restoration project BWR major component removal, packaging and shipping - planning and experience

International Nuclear Information System (INIS)

Milner, T.; Dam, S.; Papp, M.; Slade, J.; Slimp, B.; Nurden, P.

2001-01-01

The Big Rock Point boiling water reactor (BWR) at Charlevoix, MI was permanently shut down on August 29th 1997. In 1999 BNFL Inc.'s Reactor Decommissioning Group (RDG) was awarded a contract by Consumers Energy (CECo) for the Big Rock Point (BRP) Major Component Removal (MCR) project. BNFL Inc. RDG has teamed with MOTA, Sargent and Lundy and MDM Services to plan and execute MCR in support of the facility restoration project. The facility restoration project will be completed by 2005. Key to the success of the project has been the integration of best available demonstrated technology into a robust and responsive project management approach, which places emphasis on safety and quality assurance in achieving project milestones linked to time and cost. To support decommissioning of the BRP MCR activities, a reactor vessel (RV) shipping container is required. Discussed in this paper is the design and fabrication of a 10 CFR Part 71 Type B container necessary to ship the BRP RV. The container to be used for transportation of the RV to the burial site was designed as an Exclusive Use Type B package for shipment and burial at the Barnwell, South Carolina (SC) disposal facility. (author)

Heavy-tailed distributions and robustness in economics and finance

CERN Document Server

Ibragimov, Marat; Walden, Johan

2015-01-01

This book focuses on general frameworks for modeling heavy-tailed distributions in economics, finance, econometrics, statistics, risk management and insurance. A central theme is that of (non-)robustness, i.e., the fact that the presence of heavy tails can either reinforce or reverse the implications of a number of models in these fields, depending on the degree of heavy-tailedness. These results motivate the development and applications of robust inference approaches under heavy tails, heterogeneity and dependence in observations. Several recently developed robust inference approaches are discussed and illustrated, together with applications.

Application of the robust design concept for fuel loading pattern

International Nuclear Information System (INIS)

Endo, Tomohiro; Ohori, Kazuma; Yamamoto, Akio

2011-01-01

Application of the robust design concept for fuel loading pattern design is proposed as a new approach to improve the prediction accuracy of core characteristics. The robust design is a design concept that establishes a resistant (robust) system for perturbations or noises, by properly setting design variables. In order to apply the concept of robust design to fuel loading pattern design, we focus on a theoretical approach based on the higher order perturbation method. This approach indicates that the eigenvalue separation is one of the effective indices to measure the robustness of a designed fuel loading pattern. In order to verify the effectiveness of the eigenvalue separation as an index of robustness, numerical analysis is carried out for typical 3-loop PWR cores, and we evaluated the correlation between the eigenvalue separation and the variation of relative assembly power due to the perturbation of the cross section. The numerical results show that the variation of relative power decreases as the eigenvalue separation increases; thus, it is confirmed that the eigenvalue separation is an effective index of robustness. Based on the eigenvalue separation of a fuel loading pattern, we discuss design guidelines of a fuel loading pattern to improve the robustness. For example, if each fuel assembly has independent uncertainty on its cross section, the robustness of the core can be enhanced by increasing the relative power at the center of the core. The proposed guidelines will be useful to design a loading pattern that has robustness for uncertainties due to cross section, calculation method, and so on. (author)

Robust Pedestrian Tracking and Recognition from FLIR Video: A Unified Approach via Sparse Coding

Directory of Open Access Journals (Sweden)

Xin Li

2014-06-01

Full Text Available Sparse coding is an emerging method that has been successfully applied to both robust object tracking and recognition in the vision literature. In this paper, we propose to explore a sparse coding-based approach toward joint object tracking-and-recognition and explore its potential in the analysis of forward-looking infrared (FLIR video to support nighttime machine vision systems. A key technical contribution of this work is to unify existing sparse coding-based approaches toward tracking and recognition under the same framework, so that they can benefit from each other in a closed-loop. On the one hand, tracking the same object through temporal frames allows us to achieve improved recognition performance through dynamical updating of template/dictionary and combining multiple recognition results; on the other hand, the recognition of individual objects facilitates the tracking of multiple objects (i.e., walking pedestrians, especially in the presence of occlusion within a crowded environment. We report experimental results on both the CASIAPedestrian Database and our own collected FLIR video database to demonstrate the effectiveness of the proposed joint tracking-and-recognition approach.

Robust Stabilization of Discrete-Time Systems with Time-Varying Delay: An LMI Approach

Directory of Open Access Journals (Sweden)

Valter J. S. Leite

2008-01-01

Full Text Available Sufficient linear matrix inequality (LMI conditions to verify the robust stability and to design robust state feedback gains for the class of linear discrete-time systems with time-varying delay and polytopic uncertainties are presented. The conditions are obtained through parameter-dependent Lyapunov-Krasovskii functionals and use some extra variables, which yield less conservative LMI conditions. Both problems, robust stability analysis and robust synthesis, are formulated as convex problems where all system matrices can be affected by uncertainty. Some numerical examples are presented to illustrate the advantages of the proposed LMI conditions.

Rock pushing and sampling under rocks on Mars

Science.gov (United States)

Moore, H.J.; Liebes, S.; Crouch, D.S.; Clark, L.V.

1978-01-01

Viking Lander 2 acquired samples on Mars from beneath two rocks, where living organisms and organic molecules would be protected from ultraviolet radiation. Selection of rocks to be moved was based on scientific and engineering considerations, including rock size, rock shape, burial depth, and location in a sample field. Rock locations and topography were established using the computerized interactive video-stereophotogrammetric system and plotted on vertical profiles and in plan view. Sampler commands were developed and tested on Earth using a full-size lander and surface mock-up. The use of power by the sampler motor correlates with rock movements, which were by plowing, skidding, and rolling. Provenance of the samples was determined by measurements and interpretation of pictures and positions of the sampler arm. Analytical results demonstrate that the samples were, in fact, from beneath the rocks. Results from the Gas Chromatograph-Mass Spectrometer of the Molecular Analysis experiment and the Gas Exchange instrument of the Biology experiment indicate that more adsorbed(?) water occurs in samples under rocks than in samples exposed to the sun. This is consistent with terrestrial arid environments, where more moisture occurs in near-surface soil un- der rocks than in surrounding soil because the net heat flow is toward the soil beneath the rock and the rock cap inhibits evaporation. Inorganic analyses show that samples of soil from under the rocks have significantly less iron than soil exposed to the sun. The scientific significance of analyses of samples under the rocks is only partly evaluated, but some facts are clear. Detectable quantities of martian organic molecules were not found in the sample from under a rock by the Molecular Analysis experiment. The Biology experiments did not find definitive evidence for Earth-like living organisms in their sample. Significant amounts of adsorbed water may be present in the martian regolith. The response of the soil

Site investigations: Strategy for rock mechanics site descriptive model

International Nuclear Information System (INIS)

Andersson, Johan; Christiansson, Rolf; Hudson, John

2002-05-01

As a part of the planning work for the Site Investigations, SKB has developed a Rock Mechanics Site Descriptive Modelling Strategy. Similar strategies are being developed for other disciplines. The objective of the strategy is that it should guide the practical implementation of evaluating site specific data during the Site Investigations. It is also understood that further development may be needed. This methodology enables the crystalline rock mass to be characterised in terms of the quality at different sites, for considering rock engineering constructability, and for providing the input to numerical models and performance assessment calculations. The model describes the initial stresses and the distribution of deformation and strength properties of the intact rock, of fractures and fracture zones, and of the rock mass. The rock mass mechanical properties are estimated by empirical relations and by numerical simulations. The methodology is based on estimation of mechanical properties using both empirical and heroretical/numerical approaches; and estimation of in situ rock stress using judgement and numerical modelling, including the influence of fracture zones. These approaches are initially used separately, and then combined to produce the required characterisation estimates. The methodology was evaluated with a Test Case at the Aespoe Hard Rock Laboratory in Sweden. The quality control aspects are an important feature of the methodology: these include Protocols to ensure the structure and coherence of the procedures used, regular meetings to enhance communication, feedback from internal and external reviewing, plus the recording of an audit trail of the development steps and decisions made. The strategy will be reviewed and, if required, updated as appropriate

Site investigations: Strategy for rock mechanics site descriptive model

Energy Technology Data Exchange (ETDEWEB)

Andersson, Johan [JA Streamflow AB, Aelvsjoe (Sweden); Christiansson, Rolf [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Hudson, John [Rock Engineering Consultants, Welwyn Garden City (United Kingdom)

2002-05-01

As a part of the planning work for the Site Investigations, SKB has developed a Rock Mechanics Site Descriptive Modelling Strategy. Similar strategies are being developed for other disciplines. The objective of the strategy is that it should guide the practical implementation of evaluating site specific data during the Site Investigations. It is also understood that further development may be needed. This methodology enables the crystalline rock mass to be characterised in terms of the quality at different sites, for considering rock engineering constructability, and for providing the input to numerical models and performance assessment calculations. The model describes the initial stresses and the distribution of deformation and strength properties of the intact rock, of fractures and fracture zones, and of the rock mass. The rock mass mechanical properties are estimated by empirical relations and by numerical simulations. The methodology is based on estimation of mechanical properties using both empirical and heroretical/numerical approaches; and estimation of in situ rock stress using judgement and numerical modelling, including the influence of fracture zones. These approaches are initially used separately, and then combined to produce the required characterisation estimates. The methodology was evaluated with a Test Case at the Aespoe Hard Rock Laboratory in Sweden. The quality control aspects are an important feature of the methodology: these include Protocols to ensure the structure and coherence of the procedures used, regular meetings to enhance communication, feedback from internal and external reviewing, plus the recording of an audit trail of the development steps and decisions made. The strategy will be reviewed and, if required, updated as appropriate.

A Hybrid One-Way ANOVA Approach for the Robust and Efficient Estimation of Differential Gene Expression with Multiple Patterns.

Directory of Open Access Journals (Sweden)

Mohammad Manir Hossain Mollah

Full Text Available Identifying genes that are differentially expressed (DE between two or more conditions with multiple patterns of expression is one of the primary objectives of gene expression data analysis. Several statistical approaches, including one-way analysis of variance (ANOVA, are used to identify DE genes. However, most of these methods provide misleading results for two or more conditions with multiple patterns of expression in the presence of outlying genes. In this paper, an attempt is made to develop a hybrid one-way ANOVA approach that unifies the robustness and efficiency of estimation using the minimum β-divergence method to overcome some problems that arise in the existing robust methods for both small- and large-sample cases with multiple patterns of expression.The proposed method relies on a β-weight function, which produces values between 0 and 1. The β-weight function with β = 0.2 is used as a measure of outlier detection. It assigns smaller weights (≥ 0 to outlying expressions and larger weights (≤ 1 to typical expressions. The distribution of the β-weights is used to calculate the cut-off point, which is compared to the observed β-weight of an expression to determine whether that gene expression is an outlier. This weight function plays a key role in unifying the robustness and efficiency of estimation in one-way ANOVA.Analyses of simulated gene expression profiles revealed that all eight methods (ANOVA, SAM, LIMMA, EBarrays, eLNN, KW, robust BetaEB and proposed perform almost identically for m = 2 conditions in the absence of outliers. However, the robust BetaEB method and the proposed method exhibited considerably better performance than the other six methods in the presence of outliers. In this case, the BetaEB method exhibited slightly better performance than the proposed method for the small-sample cases, but the the proposed method exhibited much better performance than the BetaEB method for both the small- and large

Robust mode space approach for atomistic modeling of realistically large nanowire transistors

Science.gov (United States)

Huang, Jun Z.; Ilatikhameneh, Hesameddin; Povolotskyi, Michael; Klimeck, Gerhard

2018-01-01

Nanoelectronic transistors have reached 3D length scales in which the number of atoms is countable. Truly atomistic device representations are needed to capture the essential functionalities of the devices. Atomistic quantum transport simulations of realistically extended devices are, however, computationally very demanding. The widely used mode space (MS) approach can significantly reduce the numerical cost, but a good MS basis is usually very hard to obtain for atomistic full-band models. In this work, a robust and parallel algorithm is developed to optimize the MS basis for atomistic nanowires. This enables engineering-level, reliable tight binding non-equilibrium Green's function simulation of nanowire metal-oxide-semiconductor field-effect transistor (MOSFET) with a realistic cross section of 10 nm × 10 nm using a small computer cluster. This approach is applied to compare the performance of InGaAs and Si nanowire n-type MOSFETs (nMOSFETs) with various channel lengths and cross sections. Simulation results with full-band accuracy indicate that InGaAs nanowire nMOSFETs have no drive current advantage over their Si counterparts for cross sections up to about 10 nm × 10 nm.

Research of compression strength of fissured rock mass

Directory of Open Access Journals (Sweden)

А. Г. Протосеня

2017-03-01

Full Text Available The article examines a method of forecasting strength properties and their scale effect in fissured rock mass using computational modelling with final elements method in ABAQUS software. It shows advantages of this approach for solving tasks of determining mechanical properties of fissured rock mass, main stages of creating computational geomechanic model of rock mass and conducting a numerical experiment. The article presents connections between deformation during loading of numerical model, inclination angle of main fracture system from uniaxial and biaxial compression strength value, size of the sample of fissured rock mass and biaxial compression strength value under conditions of apatite-nepheline rock deposit at Plateau Rasvumchorr OAO «Apatit» in Kirovsky region of Murmanskaya oblast. We have conducted computational modelling of rock mass blocks testing in discontinuities based on real experiment using non-linear shear strength criterion of Barton – Bandis and compared results of computational experiments with data from field studies and laboratory tests. The calculation results have a high-quality match to laboratory results when testing fissured rock mass samples.

Numerical probabilistic analysis for slope stability in fractured rock masses using DFN-DEM approach

Directory of Open Access Journals (Sweden)

Alireza Baghbanan

2017-06-01

Full Text Available Due to existence of uncertainties in input geometrical properties of fractures, there is not any unique solution for assessing the stability of slopes in jointed rock masses. Therefore, the necessity of applying probabilistic analysis in these cases is inevitable. In this study a probabilistic analysis procedure together with relevant algorithms are developed using Discrete Fracture Network-Distinct Element Method (DFN-DEM approach. In the right abutment of Karun 4 dam and downstream of the dam body, five joint sets and one major joint have been identified. According to the geometrical properties of fractures in Karun river valley, instability situations are probable in this abutment. In order to evaluate the stability of the rock slope, different combinations of joint set geometrical parameters are selected, and a series of numerical DEM simulations are performed on generated and validated DFN models in DFN-DEM approach to measure minimum required support patterns in dry and saturated conditions. Results indicate that the distribution of required bolt length is well fitted with a lognormal distribution in both circumstances. In dry conditions, the calculated mean value is 1125.3 m, and more than 80 percent of models need only 1614.99 m of bolts which is a bolt pattern with 2 m spacing and 12 m length. However, as for the slopes with saturated condition, the calculated mean value is 1821.8 m, and more than 80 percent of models need only 2653.49 m of bolts which is equivalent to a bolt pattern with 15 m length and 1.5 m spacing. Comparison between obtained results with numerical and empirical method show that investigation of a slope stability with different DFN realizations which conducted in different block patterns is more efficient than the empirical methods.

Application of stakeholder-based and modelling approaches for supporting robust adaptation decision making under future climatic uncertainty and changing urban-agricultural water demand

Science.gov (United States)

Bhave, Ajay; Dessai, Suraje; Conway, Declan; Stainforth, David

2016-04-01

Deep uncertainty in future climate change and socio-economic conditions necessitates the use of assess-risk-of-policy approaches over predict-then-act approaches for adaptation decision making. Robust Decision Making (RDM) approaches embody this principle and help evaluate the ability of adaptation options to satisfy stakeholder preferences under wide-ranging future conditions. This study involves the simultaneous application of two RDM approaches; qualitative and quantitative, in the Cauvery River Basin in Karnataka (population ~23 million), India. The study aims to (a) determine robust water resources adaptation options for the 2030s and 2050s and (b) compare the usefulness of a qualitative stakeholder-driven approach with a quantitative modelling approach. For developing a large set of future scenarios a combination of climate narratives and socio-economic narratives was used. Using structured expert elicitation with a group of climate experts in the Indian Summer Monsoon, climatic narratives were developed. Socio-economic narratives were developed to reflect potential future urban and agricultural water demand. In the qualitative RDM approach, a stakeholder workshop helped elicit key vulnerabilities, water resources adaptation options and performance criteria for evaluating options. During a second workshop, stakeholders discussed and evaluated adaptation options against the performance criteria for a large number of scenarios of climatic and socio-economic change in the basin. In the quantitative RDM approach, a Water Evaluation And Planning (WEAP) model was forced by precipitation and evapotranspiration data, coherent with the climatic narratives, together with water demand data based on socio-economic narratives. We find that compared to business-as-usual conditions options addressing urban water demand satisfy performance criteria across scenarios and provide co-benefits like energy savings and reduction in groundwater depletion, while options reducing

A Robust Approach for Clock Offset Estimation in Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Kim Jang-Sub

2010-01-01

Full Text Available The maximum likelihood estimators (MLEs for the clock phase offset assuming a two-way message exchange mechanism between the nodes of a wireless sensor network were recently derived assuming Gaussian and exponential network delays. However, the MLE performs poorly in the presence of non-Gaussian or nonexponential network delay distributions. Currently, there is a need to develop clock synchronization algorithms that are robust to the distribution of network delays. This paper proposes a clock offset estimator based on the composite particle filter (CPF to cope with the possible asymmetries and non-Gaussianity of the network delay distributions. Also, a variant of the CPF approach based on the bootstrap sampling (BS is shown to exhibit good performance in the presence of reduced number of observations. Computer simulations illustrate that the basic CPF and its BS-based variant present superior performance than MLE under general random network delay distributions such as asymmetric Gaussian, exponential, Gamma, Weibull as well as various mixtures.

Towards distortion-free robust image authentication

International Nuclear Information System (INIS)

Coltuc, D

2007-01-01

This paper investigates a general framework for distortion-free robust image authentication by multiple marking. First, by robust watermarking a subsampled version of image edges is embedded. Then, by reversible watermarking the information needed to recover the original image is inserted, too. The hiding capacity of the reversible watermarking is the essential requirement for this approach. Thus in case of no attacks not only image is authenticated but also the original is exactly recovered. In case of attacks, reversibility is lost, but image can still be authenticated. Preliminary results providing very good robustness against JPEG compression are presented

Robust regularized least-squares beamforming approach to signal estimation

KAUST Repository

Suliman, Mohamed Abdalla Elhag; Ballal, Tarig; Al-Naffouri, Tareq Y.

2017-01-01

In this paper, we address the problem of robust adaptive beamforming of signals received by a linear array. The challenge associated with the beamforming problem is twofold. Firstly, the process requires the inversion of the usually ill

Remarks on some rock neutron parameters

International Nuclear Information System (INIS)

Czubek, J.A.

1984-01-01

A method to calculate the thermal neutron parameters of rocks is given in the paper. It is based on a proper energy averaging of cross-sections for all rock matrix and rock saturating liquid constituents. The diffusion lengths in different lithologies in function of the variable rock porosity have been calculated. An influence of the thermal neutron spectrum on the shape of the porosity calibration curves for the dual spacing neutron method is shown. Magmatic rocks as a possible source of geothermal energy are now becoming a target of neutron loggings for the porosity determination. Here the knowledge of the slowing-down lengths is of great importance in the problem of the estimation of the calibration curves. A semi-analytical approach to get this parameter is given in the paper. It was found, as far as concerns the slowing-down of fast neutrons, that all magmatic rocks behave as sandstone with, however, different content of bound water in the rock matrix and different rock matrix density. Some neutron methods are based on the detection of epithermal neutrons. For theoretical considerations it is important to know the physical meaning of the registered signal. From the discussion of experimental data reported in the literature it seems that it is the slowing-down density that is the physical quantity being measured. This conclusion has a very important practical implication - the porosity calibration curves depend upon the slowing-down length alone and are independent of the slowing-down cross-section for epithermal neutrons

Computational Models of Rock Failure

Science.gov (United States)

May, Dave A.; Spiegelman, Marc

2017-04-01

Practitioners in computational geodynamics, as per many other branches of applied science, typically do not analyse the underlying PDE's being solved in order to establish the existence or uniqueness of solutions. Rather, such proofs are left to the mathematicians, and all too frequently these results lag far behind (in time) the applied research being conducted, are often unintelligible to the non-specialist, are buried in journals applied scientists simply do not read, or simply have not been proven. As practitioners, we are by definition pragmatic. Thus, rather than first analysing our PDE's, we first attempt to find approximate solutions by throwing all our computational methods and machinery at the given problem and hoping for the best. Typically this approach leads to a satisfactory outcome. Usually it is only if the numerical solutions "look odd" that we start delving deeper into the math. In this presentation I summarise our findings in relation to using pressure dependent (Drucker-Prager type) flow laws in a simplified model of continental extension in which the material is assumed to be an incompressible, highly viscous fluid. Such assumptions represent the current mainstream adopted in computational studies of mantle and lithosphere deformation within our community. In short, we conclude that for the parameter range of cohesion and friction angle relevant to studying rocks, the incompressibility constraint combined with a Drucker-Prager flow law can result in problems which have no solution. This is proven by a 1D analytic model and convincingly demonstrated by 2D numerical simulations. To date, we do not have a robust "fix" for this fundamental problem. The intent of this submission is to highlight the importance of simple analytic models, highlight some of the dangers / risks of interpreting numerical solutions without understanding the properties of the PDE we solved, and lastly to stimulate discussions to develop an improved computational model of

Permanganate diffusion and reaction in sedimentary rocks.

Science.gov (United States)

Huang, Qiuyuan; Dong, Hailiang; Towne, Rachael M; Fischer, Timothy B; Schaefer, Charles E

2014-04-01

In situ chemical oxidation using permanganate has frequently been used to treat chlorinated solvents in fractured bedrock aquifers. However, in systems where matrix back-diffusion is an important process, the ability of the oxidant to migrate and treat target contaminants within the rock matrix will likely determine the overall effectiveness of this remedial approach. In this study, a series of diffusion experiments were performed to measure the permanganate diffusion and reaction in four different types of sedimentary rocks (dark gray mudstone, light gray mudstone, red sandstone, and tan sandstone). Results showed that, within the experimental time frame (~2 months), oxidant migration into the rock was limited to distances less than 500 μm. The observed diffusivities for permanganate into the rock matrices ranged from 5.3 × 10(-13) to 1.3 × 10(-11) cm(2)/s. These values were reasonably predicted by accounting for both the rock oxidant demand and the effective diffusivity of the rock. Various Mn minerals formed as surface coatings from reduction of permanganate coupled with oxidation of total organic carbon (TOC), and the nature of the formed Mn minerals was dependent upon the rock type. Post-treatment tracer testing showed that these Mn mineral coatings had a negligible impact on diffusion through the rock. Overall, our results showed that the extent of permanganate diffusion and reaction depended on rock properties, including porosity, mineralogy, and organic carbon. These results have important implications for our understanding of long-term organic contaminant remediation in sedimentary rocks using permanganate. Copyright © 2014 Elsevier B.V. All rights reserved.

Fragment Size Distribution of Blasted Rock Mass

Science.gov (United States)

Jug, Jasmin; Strelec, Stjepan; Gazdek, Mario; Kavur, Boris

2017-12-01

Rock mass is a heterogeneous material, and the heterogeneity of rock causes sizes distribution of fragmented rocks in blasting. Prediction of blasted rock mass fragmentation has a significant role in the overall economics of opencast mines. Blasting as primary fragmentation can significantly decrease the cost of loading, transport, crushing and milling operations. Blast fragmentation chiefly depends on the specific blast design (geometry of blast holes drilling, the quantity and class of explosive, the blasting form, the timing and partition, etc.) and on the properties of the rock mass (including the uniaxial compressive strength, the rock mass elastic Young modulus, the rock discontinuity characteristics and the rock density). Prediction and processing of blasting results researchers can accomplish by a variety of existing software’s and models, one of them is the Kuz-Ram model, which is possibly the most widely used approach to estimating fragmentation from blasting. This paper shows the estimation of fragmentation using the "SB" program, which was created by the authors. Mentioned program includes the Kuz-Ram model. Models of fragmentation are confirmed and calibrated by comparing the estimated fragmentation with actual post-blast fragmentation from image processing techniques. In this study, the Kuz-Ram fragmentation model has been used for an open-pit limestone quarry in Dalmatia, southern Croatia. The resulting calibrated value of the rock factor enables the quality prognosis of fragmentation in further blasting works, with changed drilling geometry and blast design parameters. It also facilitates simulation in the program to optimize blasting works and get the desired fragmentations of the blasted rock mass.

Recent advances in analysis and prediction of Rock Falls, Rock Slides, and Rock Avalanches using 3D point clouds

Science.gov (United States)

Abellan, A.; Carrea, D.; Jaboyedoff, M.; Riquelme, A.; Tomas, R.; Royan, M. J.; Vilaplana, J. M.; Gauvin, N.

2014-12-01

The acquisition of dense terrain information using well-established 3D techniques (e.g. LiDAR, photogrammetry) and the use of new mobile platforms (e.g. Unmanned Aerial Vehicles) together with the increasingly efficient post-processing workflows for image treatment (e.g. Structure From Motion) are opening up new possibilities for analysing, modeling and predicting rock slope failures. Examples of applications at different scales ranging from the monitoring of small changes at unprecedented level of detail (e.g. sub millimeter-scale deformation under lab-scale conditions) to the detection of slope deformation at regional scale. In this communication we will show the main accomplishments of the Swiss National Foundation project "Characterizing and analysing 3D temporal slope evolution" carried out at Risk Analysis group (Univ. of Lausanne) in close collaboration with the RISKNAT and INTERES groups (Univ. of Barcelona and Univ. of Alicante, respectively). We have recently developed a series of innovative approaches for rock slope analysis using 3D point clouds, some examples include: the development of semi-automatic methodologies for the identification and extraction of rock-slope features such as discontinuities, type of material, rockfalls occurrence and deformation. Moreover, we have been improving our knowledge in progressive rupture characterization thanks to several algorithms, some examples include the computing of 3D deformation, the use of filtering techniques on permanently based TLS, the use of rock slope failure analogies at different scales (laboratory simulations, monitoring at glacier's front, etc.), the modelling of the influence of external forces such as precipitation on the acceleration of the deformation rate, etc. We have also been interested on the analysis of rock slope deformation prior to the occurrence of fragmental rockfalls and the interaction of this deformation with the spatial location of future events. In spite of these recent advances

Strategy for a Rock Mechanics Site Descriptive Model. A test case based on data from the Aespoe HRL

International Nuclear Information System (INIS)

Hudson, John A

2002-06-01

In anticipation of the SKB Site Investigations for radioactive waste disposal, an approach has been developed for the Rock Mechanics Site Descriptive Model. This approach was tested by predicting the rock mechanics properties of a 600 m x 180 m x 120 m rock volume at the Aespoe Hard Rock Laboratory (HRL) using limited borehole data of the type typically obtained during a site investigation. These predicted properties were then compared with 'best estimate' properties obtained from a study of the test rock volume using additional information, mainly tunnel data. The exercise was known as the Test Case, and is the subject of this Report. Three modelling techniques were used to predict the rock properties: the 'empirical approach' - the rock properties were estimated using rock mass classification schemes and empirical correlation formulae; the 'theoretical approach' - the rock properties were estimated using numerical modelling techniques; and the 'stress approach' - the rock stress state was estimated using primary data and numerical modelling. These approaches are described separately and respectively. Following an explanation of the context for the Test Case within the strategy for developing the Rock Mechanics Site Descriptive Model, conditions at the Aespoe HRL are described in Chapter 2. The Test Case organization and the suite of nine Protocols used to ensure that the work was appropriately guided and co-ordinated are described in Chapter 3. The methods for predicting the rock properties and the rock stress, and comparisons with the 'best estimate' properties of the actual conditions, are presented in Chapters 4 and 5. Finally, the conclusions from this Test Case exercise are given in Chapter 6. General recommendations for the management of this type of Test Case are also included

Strategy for a Rock Mechanics Site Descriptive Model. A test case based on data from the Aespoe HRL

Energy Technology Data Exchange (ETDEWEB)

Hudson, John A (ed.) [Rock Engineering Consultants, Welwyn Garden City (United Kingdom)

2002-06-01

In anticipation of the SKB Site Investigations for radioactive waste disposal, an approach has been developed for the Rock Mechanics Site Descriptive Model. This approach was tested by predicting the rock mechanics properties of a 600 m x 180 m x 120 m rock volume at the Aespoe Hard Rock Laboratory (HRL) using limited borehole data of the type typically obtained during a site investigation. These predicted properties were then compared with 'best estimate' properties obtained from a study of the test rock volume using additional information, mainly tunnel data. The exercise was known as the Test Case, and is the subject of this Report. Three modelling techniques were used to predict the rock properties: the 'empirical approach' - the rock properties were estimated using rock mass classification schemes and empirical correlation formulae; the 'theoretical approach' - the rock properties were estimated using numerical modelling techniques; and the 'stress approach' - the rock stress state was estimated using primary data and numerical modelling. These approaches are described separately and respectively. Following an explanation of the context for the Test Case within the strategy for developing the Rock Mechanics Site Descriptive Model, conditions at the Aespoe HRL are described in Chapter 2. The Test Case organization and the suite of nine Protocols used to ensure that the work was appropriately guided and co-ordinated are described in Chapter 3. The methods for predicting the rock properties and the rock stress, and comparisons with the 'best estimate' properties of the actual conditions, are presented in Chapters 4 and 5. Finally, the conclusions from this Test Case exercise are given in Chapter 6. General recommendations for the management of this type of Test Case are also included.

Analyzing Unsaturated Flow Patterns in Fractured Rock Using an Integrated Modeling Approach

International Nuclear Information System (INIS)

Y.S. Wu; G. Lu; K. Zhang; L. Pan; G.S. Bodvarsson

2006-01-01

Characterizing percolation patterns in unsaturated fractured rock has posed a greater challenge to modeling investigations than comparable saturated zone studies, because of the heterogeneous nature of unsaturated media and the great number of variables impacting unsaturated flow. This paper presents an integrated modeling methodology for quantitatively characterizing percolation patterns in the unsaturated zone of Yucca Mountain, Nevada, a proposed underground repository site for storing high-level radioactive waste. The modeling approach integrates a wide variety of moisture, pneumatic, thermal, and isotopic geochemical field data into a comprehensive three-dimensional numerical model for modeling analyses. It takes into account the coupled processes of fluid and heat flow and chemical isotopic transport in Yucca Mountain's highly heterogeneous, unsaturated fractured tuffs. Modeling results are examined against different types of field-measured data and then used to evaluate different hydrogeological conceptualizations and their results of flow patterns in the unsaturated zone. In particular, this model provides a much clearer understanding of percolation patterns and flow behavior through the unsaturated zone, both crucial issues in assessing repository performance. The integrated approach for quantifying Yucca Mountain's flow system is demonstrated to provide a practical modeling tool for characterizing flow and transport processes in complex subsurface systems

Robustness Analysis of a Timber Structure with Ductile Behaviour in Compression

DEFF Research Database (Denmark)

Čizmar, Dean; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning

2011-01-01

This paper presents a probabilistic approach for structural robustness assessment for a timber structure built a few years ago. The robustness analysis is based on a structural reliability based framework for robustness assessment. The complex timber structure with a large number of failure modes...... material ductility of timber is taken into account. The robustness is expressed and evaluated by a robustness index....

Robust Portfolio Optimization Using Pseudodistances

Science.gov (United States)

2015-01-01

The presence of outliers in financial asset returns is a frequently occurring phenomenon which may lead to unreliable mean-variance optimized portfolios. This fact is due to the unbounded influence that outliers can have on the mean returns and covariance estimators that are inputs in the optimization procedure. In this paper we present robust estimators of mean and covariance matrix obtained by minimizing an empirical version of a pseudodistance between the assumed model and the true model underlying the data. We prove and discuss theoretical properties of these estimators, such as affine equivariance, B-robustness, asymptotic normality and asymptotic relative efficiency. These estimators can be easily used in place of the classical estimators, thereby providing robust optimized portfolios. A Monte Carlo simulation study and applications to real data show the advantages of the proposed approach. We study both in-sample and out-of-sample performance of the proposed robust portfolios comparing them with some other portfolios known in literature. PMID:26468948

Robust Portfolio Optimization Using Pseudodistances.

Science.gov (United States)

Toma, Aida; Leoni-Aubin, Samuela

2015-01-01

The presence of outliers in financial asset returns is a frequently occurring phenomenon which may lead to unreliable mean-variance optimized portfolios. This fact is due to the unbounded influence that outliers can have on the mean returns and covariance estimators that are inputs in the optimization procedure. In this paper we present robust estimators of mean and covariance matrix obtained by minimizing an empirical version of a pseudodistance between the assumed model and the true model underlying the data. We prove and discuss theoretical properties of these estimators, such as affine equivariance, B-robustness, asymptotic normality and asymptotic relative efficiency. These estimators can be easily used in place of the classical estimators, thereby providing robust optimized portfolios. A Monte Carlo simulation study and applications to real data show the advantages of the proposed approach. We study both in-sample and out-of-sample performance of the proposed robust portfolios comparing them with some other portfolios known in literature.

Robustness Envelopes of Networks

NARCIS (Netherlands)

Trajanovski, S.; Martín-Hernández, J.; Winterbach, W.; Van Mieghem, P.

2013-01-01

We study the robustness of networks under node removal, considering random node failure, as well as targeted node attacks based on network centrality measures. Whilst both of these have been studied in the literature, existing approaches tend to study random failure in terms of average-case

How Robust is Your System Resilience?

Science.gov (United States)

Homayounfar, M.; Muneepeerakul, R.

2017-12-01

Robustness and resilience are concepts in system thinking that have grown in importance and popularity. For many complex social-ecological systems, however, robustness and resilience are difficult to quantify and the connections and trade-offs between them difficult to study. Most studies have either focused on qualitative approaches to discuss their connections or considered only one of them under particular classes of disturbances. In this study, we present an analytical framework to address the linkage between robustness and resilience more systematically. Our analysis is based on a stylized dynamical model that operationalizes a widely used concept framework for social-ecological systems. The model enables us to rigorously define robustness and resilience and consequently investigate their connections. The results reveal the tradeoffs among performance, robustness, and resilience. They also show how the nature of the such tradeoffs varies with the choices of certain policies (e.g., taxation and investment in public infrastructure), internal stresses and external disturbances.

A Distributed Robust Dispatch Approach for Interconnected Systems with a High Proportion of Wind Power Penetration

Directory of Open Access Journals (Sweden)

Jianwen Ren

2018-04-01

Full Text Available This paper proposes a distributed robust dispatch approach to solve the economic dispatch problem of the interconnected systems with a high proportion of wind power penetration. First of all, the basic principle of synchronous alternating direction method of multipliers (SADMM is introduced to solve the economic dispatch problem of the two interconnected regions. Next, the polyhedron set of the robust optimization method is utilized to describe the wind power output. To adjust the conservativeness of the polyhedron set, an adjustment factor of robust conservativeness is introduced. Subsequently, considering the operation characteristics of the DC tie line between the interconnected regions, an economic dispatch model with a high proportion of wind power penetration is established and parallel iteration based on SADMM is used to solve the model. In each iteration, the optimized power of DC tie lines is exchanged between the regions without requiring the participation of the superior dispatch center. Finally, the validity of the proposed model is verified by the examples of the 2-area 6-node interconnected system and the interconnection of several modified New England 39-node systems. The results show that the proposed model can meet the needs of the independent dispatch of regional power grids, effectively deal with the uncertainty of wind power output, and maximize the wind power consumption under the condition of ensuring the safe operation of the interconnected systems.

A scoring mechanism for the rank aggregation of network robustness

Science.gov (United States)

Yazdani, Alireza; Dueñas-Osorio, Leonardo; Li, Qilin

2013-10-01

To date, a number of metrics have been proposed to quantify inherent robustness of network topology against failures. However, each single metric usually only offers a limited view of network vulnerability to different types of random failures and targeted attacks. When applied to certain network configurations, different metrics rank network topology robustness in different orders which is rather inconsistent, and no single metric fully characterizes network robustness against different modes of failure. To overcome such inconsistency, this work proposes a multi-metric approach as the basis of evaluating aggregate ranking of network topology robustness. This is based on simultaneous utilization of a minimal set of distinct robustness metrics that are standardized so to give way to a direct comparison of vulnerability across networks with different sizes and configurations, hence leading to an initial scoring of inherent topology robustness. Subsequently, based on the inputs of initial scoring a rank aggregation method is employed to allocate an overall ranking of robustness to each network topology. A discussion is presented in support of the presented multi-metric approach and its applications to more realistically assess and rank network topology robustness.

Estimating the Wet-Rock P-Wave Velocity from the Dry-Rock P-Wave Velocity for Pyroclastic Rocks

Science.gov (United States)

Kahraman, Sair; Fener, Mustafa; Kilic, Cumhur Ozcan

2017-07-01

Seismic methods are widely used for the geotechnical investigations in volcanic areas or for the determination of the engineering properties of pyroclastic rocks in laboratory. Therefore, developing a relation between the wet- and dry-rock P-wave velocities will be helpful for engineers when evaluating the formation characteristics of pyroclastic rocks. To investigate the predictability of the wet-rock P-wave velocity from the dry-rock P-wave velocity for pyroclastic rocks P-wave velocity measurements were conducted on 27 different pyroclastic rocks. In addition, dry-rock S-wave velocity measurements were conducted. The test results were modeled using Gassmann's and Wood's theories and it was seen that estimates for saturated P-wave velocity from the theories fit well measured data. For samples having values of less and greater than 20%, practical equations were derived for reliably estimating wet-rock P-wave velocity as function of dry-rock P-wave velocity.

Robust small area prediction for counts.

Science.gov (United States)

Tzavidis, Nikos; Ranalli, M Giovanna; Salvati, Nicola; Dreassi, Emanuela; Chambers, Ray

2015-06-01

A new semiparametric approach to model-based small area prediction for counts is proposed and used for estimating the average number of visits to physicians for Health Districts in Central Italy. The proposed small area predictor can be viewed as an outlier robust alternative to the more commonly used empirical plug-in predictor that is based on a Poisson generalized linear mixed model with Gaussian random effects. Results from the real data application and from a simulation experiment confirm that the proposed small area predictor has good robustness properties and in some cases can be more efficient than alternative small area approaches. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

'Escher' Rock

Science.gov (United States)

2004-01-01

[figure removed for brevity, see original site] Chemical Changes in 'Endurance' Rocks [figure removed for brevity, see original site] Figure 1 This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a rock dubbed 'Escher' on the southwestern slopes of 'Endurance Crater.' Scientists believe the rock's fractures, which divide the surface into polygons, may have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the rock's formation dried up. A third possibility is that much later, after the rock was formed, and after the crater was created, the rock became wet once again, then dried up and developed cracks. Opportunity has spent the last 14 sols investigating Escher, specifically the target dubbed 'Kirchner,' and other similar rocks with its scientific instruments. This image was taken on sol 208 (Aug. 24, 2004) by the rover's panoramic camera, using the 750-, 530- and 430-nanometer filters. The graph above shows that rocks located deeper into 'Endurance Crater' are chemically altered to a greater degree than rocks located higher up. This chemical alteration is believed to result from exposure to water. Specifically, the graph compares ratios of chemicals between the deep rock dubbed 'Escher,' and the more shallow rock called 'Virginia,' before (red and blue lines) and after (green line) the Mars Exploration Rover Opportunity drilled into the rocks. As the red and blue lines indicate, Escher's levels of chlorine relative to Virginia's went up, and sulfur down, before the rover dug a hole into the rocks. This implies that the surface of Escher has been chemically altered to a greater extent than the surface of Virginia. Scientists are still investigating the role water played in influencing this trend. These data were taken by the rover's alpha particle X-ray spectrometer.

Robust Path Planning and Feedback Design Under Stochastic Uncertainty

Science.gov (United States)

Blackmore, Lars

2008-01-01

Autonomous vehicles require optimal path planning algorithms to achieve mission goals while avoiding obstacles and being robust to uncertainties. The uncertainties arise from exogenous disturbances, modeling errors, and sensor noise, which can be characterized via stochastic models. Previous work defined a notion of robustness in a stochastic setting by using the concept of chance constraints. This requires that mission constraint violation can occur with a probability less than a prescribed value.In this paper we describe a novel method for optimal chance constrained path planning with feedback design. The approach optimizes both the reference trajectory to be followed and the feedback controller used to reject uncertainty. Our method extends recent results in constrained control synthesis based on convex optimization to solve control problems with nonconvex constraints. This extension is essential for path planning problems, which inherently have nonconvex obstacle avoidance constraints. Unlike previous approaches to chance constrained path planning, the new approach optimizes the feedback gain as wellas the reference trajectory.The key idea is to couple a fast, nonconvex solver that does not take into account uncertainty, with existing robust approaches that apply only to convex feasible regions. By alternating between robust and nonrobust solutions, the new algorithm guarantees convergence to a global optimum. We apply the new method to an unmanned aircraft and show simulation results that demonstrate the efficacy of the approach.

A constrained robust least squares approach for contaminant release history identification

Science.gov (United States)

Sun, Alexander Y.; Painter, Scott L.; Wittmeyer, Gordon W.

2006-04-01

Contaminant source identification is an important type of inverse problem in groundwater modeling and is subject to both data and model uncertainty. Model uncertainty was rarely considered in the previous studies. In this work, a robust framework for solving contaminant source recovery problems is introduced. The contaminant source identification problem is first cast into one of solving uncertain linear equations, where the response matrix is constructed using a superposition technique. The formulation presented here is general and is applicable to any porous media flow and transport solvers. The robust least squares (RLS) estimator, which originated in the field of robust identification, directly accounts for errors arising from model uncertainty and has been shown to significantly reduce the sensitivity of the optimal solution to perturbations in model and data. In this work, a new variant of RLS, the constrained robust least squares (CRLS), is formulated for solving uncertain linear equations. CRLS allows for additional constraints, such as nonnegativity, to be imposed. The performance of CRLS is demonstrated through one- and two-dimensional test problems. When the system is ill-conditioned and uncertain, it is found that CRLS gave much better performance than its classical counterpart, the nonnegative least squares. The source identification framework developed in this work thus constitutes a reliable tool for recovering source release histories in real applications.

Relative Permeability of Fractured Rock

Energy Technology Data Exchange (ETDEWEB)

Mark D. Habana

2002-06-30

Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

Rock-fall Hazard In The Yosemite Valley, California

Science.gov (United States)

Guzzetti, F.; Reichenbach, P.; Wieczorek, G. F.

Rock slides and rock falls are the most frequent slope movements in Yosemite Na- tional Park, California. In historical time (1851-2001), more than 400 rock falls and rock slides have been documented in the valley, and some of them have been mapped in detail. We present the preliminary results of an attempt to assess rockfall hazard in the Yosemite Valley using STONE, a 3-dimensional rock-fall simulation computer program. The software computes 3-dimensional rock-fall trajectories starting from a digital terrain model (DTM), the location of rock-fall release points (source areas), and maps of the dynamic rolling coefficient and of the coefficients of normal and tan- gential energy restitution. For each DTM cell the software also calculates the number of rock falls passing through the cell, the maximum rock-fall velocity and the maxi- mum flying height. For the Yosemite Valley, a DTM with a ground resolution of 10 x 10 m was prepared using topographic contour lines from USGS 1:24,000-scale maps. Rock-fall release points were identified as DTM cells having a slope steeper than 60 degrees, an assumption based on the location of historical rock falls. Maps of the nor- mal and tangential energy restitution coefficients and of the rolling friction coefficient were produced from a surficial geologic map. The availability of historical rock falls mapped in detail allowed us to check the computer program performance and to cali- brate the model parameters. Visual and statistical comparison of the model results with the mapped rock falls confirmed the accuracy of the model. The model results are also compared with a geomorphic assessment of rock-fall hazard based on potential energy referred to as a "shadow angle" approach, recently completed for the Yosemite Valley.

Rock coasts and seabird breeding sites : a common optimization

Science.gov (United States)

Marie, Eveillard-Buchoux

2014-05-01

The North-West coasts of Europe support a lot of part of Northern hemisphere breeding seabirds. In that context, Scotland has a preponderant place and Brittany has southernmost limit of these species areas, for most of them. Outside the breeding season these species live mainly on the open sea and when they do visit the land to breed, they nest on a specific sites : almost all the time they breed on the rock coasts, often on seacliffs. This specific habitat are defines by geomorphological characteristics which offer special forms of the coast. The forms of rock coasts are originally and different because of several proprieties of geology, of lithology, of structures. Breeding seabird, occupying these sites, reveals, in a new light, the richness of these forms and the originals geographic location of the coastline : seabirds prefer nest in exposed coastline like rock caps, rocky points or islands. Seabirds and rock coasts are research topics in environmental geography since several years. However, these combination studies is a new approach in this field and enlargement in the heritage field allows supplement scientific approach. For example, it show that in most important touristic sites, environmental protection measures focused on landscape, habitat or bird, but much more rarely on rock coasts for these intrinsic values. Indeed, in Brittany or in Scotland, seabirds are often stars species in lot of coastal nature reserves, where they're considered like greater ecological heritage. We could see it in touristic promotion field : bird is everywhere, cliff is mostly kept in the dark, as well in leaflets as in speech visitor's guides - without, for example, as a part of this landscape. In all cases, combination of these two heritages is extremely rare. Yet, this current research illustrates the interest and the issue of development of this comparative approach seabirds / rock coasts for optimization of nature tourism and geotourism.

One Song, Many Works: A Pluralist Ontology of Rock

Directory of Open Access Journals (Sweden)

Dan Burkett

2016-01-01

Full Text Available A number of attempts have been made to construct a plausible ontology of rock music. Each of these ontologies identifies a single type of ontological entity as the “work” in rock music. Yet, all the suggestions advanced to date fail to capture some important considerations about how we engage with music of this tradition. This prompted Lee Brown to advocate a healthy skepticism of higher-order musical ontologies. I argue here that we should instead embrace a pluralist ontology of rock, an ontology that recognizes more than one kind of entity as “the work” in rock music. I contend that this approach has a number of advantages over other ontologies of rock, including that of allowing us to make some comparisons across ontological kinds.

Reliability-Based Robustness Analysis for a Croatian Sports Hall

DEFF Research Database (Denmark)

Čizmar, Dean; Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

2011-01-01

This paper presents a probabilistic approach for structural robustness assessment for a timber structure built a few years ago. The robustness analysis is based on a structural reliability based framework for robustness and a simplified mechanical system modelling of a timber truss system....... A complex timber structure with a large number of failure modes is modelled with only a few dominant failure modes. First, a component based robustness analysis is performed based on the reliability indices of the remaining elements after the removal of selected critical elements. The robustness...... is expressed and evaluated by a robustness index. Next, the robustness is assessed using system reliability indices where the probabilistic failure model is modelled by a series system of parallel systems....

Impact of ocean acidification and warming on the productivity of a rock pool community.

Science.gov (United States)

Legrand, Erwann; Riera, Pascal; Bohner, Olivier; Coudret, Jérôme; Schlicklin, Ferdinand; Derrien, Marie; Martin, Sophie

2018-05-01

This study examined experimentally the combined effect of ocean acidification and warming on the productivity of rock pool multi-specific assemblages, composed of coralline algae, fleshy algae, and grazers. Natural rock pool communities experience high environmental fluctuations. This may confer physiological advantage to rock pool communities when facing predicted acidification and warming. The effect of ocean acidification and warming have been assessed at both individual and assemblage level to examine the importance of species interactions in the response of assemblages. We hypothesized that rock pool assemblages have physiological advantage when facing predicted ocean acidification and warming. Species exhibited species-specific responses to increased temperature and pCO 2 . Increased temperature and pCO 2 have no effect on assemblage photosynthesis, which was mostly influenced by fleshy algal primary production. The response of coralline algae to ocean acidification and warming depended on the season, which evidenced the importance of physiological adaptations to their environment in their response to climate change. We suggest that rock pool assemblages are relatively robust to changes in temperature and pCO 2 , in terms of primary production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Exploring the Impact of Network Structure and Demand Collaboration on the Dynamics of a Supply Chain Network Using a Robust Control Approach

Directory of Open Access Journals (Sweden)

Yongchang Wei

2015-01-01

uncertain environment. The impact of network structure and collaboration on the dynamics and robustness of supply chain network, however, remains to be explored. In this paper, a unified state space model for a two-layer supply chain network composed of multiple distributors and multiple retailers is developed. A robust control algorithm is advocated to reduce both order and demand fluctuations for unknown demand. Numerical simulations demonstrate that the robust control approach has the advantage to reduce both inventory and order fluctuations. In the simulation experiment, it is interesting to notice that complex network structure and collaborations might contribute to the reduction of inventory and order oscillations. This paper yields new insights into the overestimated bullwhip effect problem and helps us understand the complexities of supply chain networks.

Handling Occlusions for Robust Augmented Reality Systems

Directory of Open Access Journals (Sweden)

Maidi Madjid

2010-01-01

Full Text Available Abstract In Augmented Reality applications, the human perception is enhanced with computer-generated graphics. These graphics must be exactly registered to real objects in the scene and this requires an effective Augmented Reality system to track the user's viewpoint. In this paper, a robust tracking algorithm based on coded fiducials is presented. Square targets are identified and pose parameters are computed using a hybrid approach based on a direct method combined with the Kalman filter. An important factor for providing a robust Augmented Reality system is the correct handling of targets occlusions by real scene elements. To overcome tracking failure due to occlusions, we extend our method using an optical flow approach to track visible points and maintain virtual graphics overlaying when targets are not identified. Our proposed real-time algorithm is tested with different camera viewpoints under various image conditions and shows to be accurate and robust.

Robust Mediation Analysis Based on Median Regression

Science.gov (United States)

Yuan, Ying; MacKinnon, David P.

2014-01-01

Mediation analysis has many applications in psychology and the social sciences. The most prevalent methods typically assume that the error distribution is normal and homoscedastic. However, this assumption may rarely be met in practice, which can affect the validity of the mediation analysis. To address this problem, we propose robust mediation analysis based on median regression. Our approach is robust to various departures from the assumption of homoscedasticity and normality, including heavy-tailed, skewed, contaminated, and heteroscedastic distributions. Simulation studies show that under these circumstances, the proposed method is more efficient and powerful than standard mediation analysis. We further extend the proposed robust method to multilevel mediation analysis, and demonstrate through simulation studies that the new approach outperforms the standard multilevel mediation analysis. We illustrate the proposed method using data from a program designed to increase reemployment and enhance mental health of job seekers. PMID:24079925

Modelling Geomechanical Heterogeneity of Rock Masses Using Direct and Indirect Geostatistical Conditional Simulation Methods

Science.gov (United States)

Eivazy, Hesameddin; Esmaieli, Kamran; Jean, Raynald

2017-12-01

An accurate characterization and modelling of rock mass geomechanical heterogeneity can lead to more efficient mine planning and design. Using deterministic approaches and random field methods for modelling rock mass heterogeneity is known to be limited in simulating the spatial variation and spatial pattern of the geomechanical properties. Although the applications of geostatistical techniques have demonstrated improvements in modelling the heterogeneity of geomechanical properties, geostatistical estimation methods such as Kriging result in estimates of geomechanical variables that are not fully representative of field observations. This paper reports on the development of 3D models for spatial variability of rock mass geomechanical properties using geostatistical conditional simulation method based on sequential Gaussian simulation. A methodology to simulate the heterogeneity of rock mass quality based on the rock mass rating is proposed and applied to a large open-pit mine in Canada. Using geomechanical core logging data collected from the mine site, a direct and an indirect approach were used to model the spatial variability of rock mass quality. The results of the two modelling approaches were validated against collected field data. The study aims to quantify the risks of pit slope failure and provides a measure of uncertainties in spatial variability of rock mass properties in different areas of the pit.

Robust optimization for load scheduling of a smart home with photovoltaic system

International Nuclear Information System (INIS)

Wang, Chengshan; Zhou, Yue; Jiao, Bingqi; Wang, Yamin; Liu, Wenjian; Wang, Dan

2015-01-01

Highlights: • Robust household load scheduling is presented for smart homes with PV system. • A robust counterpart is formulated to deal with PV output uncertainty. • The robust counterpart is finally transformed to a quadratic programming problem. • Load schedules with different robustness can be made by the proposed method. • Feed-in tariff and PV output would affect the significance of the proposed method. - Abstract: In this paper, a robust approach is developed to tackle the uncertainty of PV power output for load scheduling of smart homes integrated with household PV system. Specifically, a robust formulation is proposed and further transformed to an equivalent quadratic programming problem. Day-ahead load schedules with different robustness can be generated by solving the proposed robust formulation with different predefined parameters. The validity and advantage of the proposed approach has been verified by simulation results. Also, the effects of feed-in tariff and PV output have been evaluated

THM-issues in repository rock. Thermal, mechanical, thermo-mechanical and hydro-mechanical evolution of the rock at the Forsmark and Laxemar sites

Energy Technology Data Exchange (ETDEWEB)

Hoekmark, Harald; Loennqvist, Margareta; Faelth, Billy (Clay Technology AB, Lund (Sweden))

2010-05-15

even in the hottest ones. To account for uncertainties in the thermal calculations, the layout is established with a margin of about 5 deg C to the 100 deg C limit. It is demonstrated here that the spatial variability of rock heat transport properties means that there is considerable robustness in the design approach. An underestimate of the uncertainty margin by a few degrees appears to impact on very few canisters, even under the conservative assumption that all deposition holes are completely dry. Spalling after excavation of a deposition hole excavation is not likely unless the major horizontal stress is aligned off the orientation of the tunnel axis by the largest angle given within the uncertainty range of the Forsmark in situ stress model. In case it happens, the spalling will be limited to the top 1 m of the deposition hole for the most likely Forsmark major stress magnitude and to the top 3 m for the upper bound stress magnitude. Thermally-induced spalling is almost certain to occur after some time of heating, i.e. also for the most favourable conditions regarding stress orientation and magnitude. However, for the most favourable conditions the spalling will occur late and be limited to the top 5 m of the deposition hole. All spalling risk estimates are based on the assumption that the spalling strength varies between 52% and 62% of the uniaxial compressive strength of the intact rock, as suggested by field experiments performed in the Aespoe Hard Rock Laboratory. It is also assumed that the deposition holes are completely dry, i.e. without any swelling pressure to support and stabilize the walls. These assumptions are all claimed to be conservative. The stress path for rock in the walls of KBS-3 deposition holes will be different from corresponding stress paths in the field experiments and a small support pressure, possibly sufficient to limit the extent of the spalling, will be found also in dry deposition holes. Transmissivity effects on rock fractures are

Rock fragmentation

Energy Technology Data Exchange (ETDEWEB)

Brown, W.S.; Green, S.J.; Hakala, W.W.; Hustrulid, W.A.; Maurer, W.C. (eds.)

1976-01-01

Experts in rock mechanics, mining, excavation, drilling, tunneling and use of underground space met to discuss the relative merits of a wide variety of rock fragmentation schemes. Information is presented on novel rock fracturing techniques; tunneling using electron beams, thermocorer, electric spark drills, water jets, and diamond drills; and rock fracturing research needs for mining and underground construction. (LCL)

Robust input design for nonlinear dynamic modeling of AUV.

Science.gov (United States)

Nouri, Nowrouz Mohammad; Valadi, Mehrdad

2017-09-01

Input design has a dominant role in developing the dynamic model of autonomous underwater vehicles (AUVs) through system identification. Optimal input design is the process of generating informative inputs that can be used to generate the good quality dynamic model of AUVs. In a problem with optimal input design, the desired input signal depends on the unknown system which is intended to be identified. In this paper, the input design approach which is robust to uncertainties in model parameters is used. The Bayesian robust design strategy is applied to design input signals for dynamic modeling of AUVs. The employed approach can design multiple inputs and apply constraints on an AUV system's inputs and outputs. Particle swarm optimization (PSO) is employed to solve the constraint robust optimization problem. The presented algorithm is used for designing the input signals for an AUV, and the estimate obtained by robust input design is compared with that of the optimal input design. According to the results, proposed input design can satisfy both robustness of constraints and optimality. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Comparison of HMM experts with MLP experts in the Full Combination Multi-Band Approach to Robust ASR

OpenAIRE

Hagen, Astrid; Morris, Andrew

2000-01-01

In this paper we apply the Full Combination (FC) multi-band approach, which has originally been introduced in the framework of posterior-based HMM/ANN (Hidden Markov Model/Artificial Neural Network) hybrid systems, to systems in which the ANN (or Multilayer Perceptron (MLP)) is itself replaced by a Multi Gaussian HMM (MGM). Both systems represent the most widely used statistical models for robust ASR (automatic speech recognition). It is shown how the FC formula for the likelihood--based MGMs...

Nonlinear robust hierarchical control for nonlinear uncertain systems

Directory of Open Access Journals (Sweden)

Leonessa Alexander

1999-01-01

Full Text Available A nonlinear robust control-system design framework predicated on a hierarchical switching controller architecture parameterized over a set of moving nominal system equilibria is developed. Specifically, using equilibria-dependent Lyapunov functions, a hierarchical nonlinear robust control strategy is developed that robustly stabilizes a given nonlinear system over a prescribed range of system uncertainty by robustly stabilizing a collection of nonlinear controlled uncertain subsystems. The robust switching nonlinear controller architecture is designed based on a generalized (lower semicontinuous Lyapunov function obtained by minimizing a potential function over a given switching set induced by the parameterized nominal system equilibria. The proposed framework robustly stabilizes a compact positively invariant set of a given nonlinear uncertain dynamical system with structured parametric uncertainty. Finally, the efficacy of the proposed approach is demonstrated on a jet engine propulsion control problem with uncertain pressure-flow map data.

Uranium endowments in phosphate rock

Energy Technology Data Exchange (ETDEWEB)

Ulrich, Andrea E., E-mail: andrea.ulrich@env.ethz.ch [Institute for Environmental Decisions (IED), Natural and Social Science Interface, ETH Zurich Universitässtrasse 22, 8092 Zurich (Switzerland); Institute for Agricultural Sciences, Plant Nutrition, ETH Zurich, Eschikon 33, 8315 Lindau (Switzerland); Schnug, Ewald, E-mail: e.schnug@tu-braunschweig.de [Department of Life Sciences, Technical University of Braunschweig, Pockelsstraße 14, D-38106 Braunschweig (Germany); Prasser, Horst-Michael, E-mail: prasser@lke.mavt.ethz.ch [Institute of Energy Technology, Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8092 Zurich (Switzerland); Frossard, Emmanuel, E-mail: emmanuel.frossard@usys.ethz.ch [Institute for Agricultural Sciences, Plant Nutrition, ETH Zurich, Eschikon 33, 8315 Lindau (Switzerland)

2014-04-01

This study seeks to identify and specify the components that make up the prospects of U recovery from phosphate rock. A systems approach is taken. The assessment includes i) reviewing past recovery experience and lessons learned; ii) identifying factors that determine recovery; and iii) establishing a contemporary evaluation of U endowments in phosphate rock reserves, as well as the available and recoverable amounts from phosphate rock and phosphoric acid production. We find that in the past, recovery did not fulfill its potential and that the breakup of the Soviet Union worsened then-favorable recovery market conditions in the 1990s. We find that an estimated 5.7 million tU may be recoverable from phosphate rock reserves. In 2010, the recoverable tU from phosphate rock and phosphoric acid production may have been 15,000 tU and 11,000 tU, respectively. This could have filled the world U supply-demand gap for nuclear energy production. The results suggest that the U.S., Morocco, Tunisia, and Russia would be particularly well-suited to recover U, taking infrastructural considerations into account. We demonstrate future research needs, as well as sustainability orientations. We conclude that in order to promote investment and production, it seems necessary to establish long-term contracts at guaranteed prices, ensuring profitability for phosphoric acid producers. - Highlights: • We identify components that underlie the recovery of uranium from phosphate rock. • We estimate that 11,000 tU may have been recoverable from phosphoric acid in 2010. • Recovery is a resource conservation and environmental pollution control strategy. • To ensure investment in recovery technology, profitability needs to be secured.

Uranium endowments in phosphate rock

International Nuclear Information System (INIS)

Ulrich, Andrea E.; Schnug, Ewald; Prasser, Horst-Michael; Frossard, Emmanuel

2014-01-01

This study seeks to identify and specify the components that make up the prospects of U recovery from phosphate rock. A systems approach is taken. The assessment includes i) reviewing past recovery experience and lessons learned; ii) identifying factors that determine recovery; and iii) establishing a contemporary evaluation of U endowments in phosphate rock reserves, as well as the available and recoverable amounts from phosphate rock and phosphoric acid production. We find that in the past, recovery did not fulfill its potential and that the breakup of the Soviet Union worsened then-favorable recovery market conditions in the 1990s. We find that an estimated 5.7 million tU may be recoverable from phosphate rock reserves. In 2010, the recoverable tU from phosphate rock and phosphoric acid production may have been 15,000 tU and 11,000 tU, respectively. This could have filled the world U supply-demand gap for nuclear energy production. The results suggest that the U.S., Morocco, Tunisia, and Russia would be particularly well-suited to recover U, taking infrastructural considerations into account. We demonstrate future research needs, as well as sustainability orientations. We conclude that in order to promote investment and production, it seems necessary to establish long-term contracts at guaranteed prices, ensuring profitability for phosphoric acid producers. - Highlights: • We identify components that underlie the recovery of uranium from phosphate rock. • We estimate that 11,000 tU may have been recoverable from phosphoric acid in 2010. • Recovery is a resource conservation and environmental pollution control strategy. • To ensure investment in recovery technology, profitability needs to be secured

Rock mechanics for hard rock nuclear waste repositories

International Nuclear Information System (INIS)

Heuze, F.E.

1981-09-01

The mined geologic burial of high level nuclear waste is now the favored option for disposal. The US National Waste Terminal Storage Program designed to achieve this disposal includes an extensive rock mechanics component related to the design of the wastes repositories. The plan currently considers five candidate rock types. This paper deals with the three hard rocks among them: basalt, granite, and tuff. Their behavior is governed by geological discontinuities. Salt and shale, which exhibit behavior closer to that of a continuum, are not considered here. This paper discusses both the generic rock mechanics R and D, which are required for repository design, as well as examples of projects related to hard rock waste storage. The examples include programs in basalt (Hanford/Washington), in granitic rocks (Climax/Nevada Test Site, Idaho Springs/Colorado, Pinawa/Canada, Oracle/Arizona, and Stripa/Sweden), and in tuff

Elastic Rock Heterogeneity Controls Brittle Rock Failure during Hydraulic Fracturing

Science.gov (United States)

Langenbruch, C.; Shapiro, S. A.

2014-12-01

For interpretation and inversion of microseismic data it is important to understand, which properties of the reservoir rock control the occurrence probability of brittle rock failure and associated seismicity during hydraulic stimulation. This is especially important, when inverting for key properties like permeability and fracture conductivity. Although it became accepted that seismic events are triggered by fluid flow and the resulting perturbation of the stress field in the reservoir rock, the magnitude of stress perturbations, capable of triggering failure in rocks, can be highly variable. The controlling physical mechanism of this variability is still under discussion. We compare the occurrence of microseismic events at the Cotton Valley gas field to elastic rock heterogeneity, obtained from measurements along the treatment wells. The heterogeneity is characterized by scale invariant fluctuations of elastic properties. We observe that the elastic heterogeneity of the rock formation controls the occurrence of brittle failure. In particular, we find that the density of events is increasing with the Brittleness Index (BI) of the rock, which is defined as a combination of Young's modulus and Poisson's ratio. We evaluate the physical meaning of the BI. By applying geomechanical investigations we characterize the influence of fluctuating elastic properties in rocks on the probability of brittle rock failure. Our analysis is based on the computation of stress fluctuations caused by elastic heterogeneity of rocks. We find that elastic rock heterogeneity causes stress fluctuations of significant magnitude. Moreover, the stress changes necessary to open and reactivate fractures in rocks are strongly related to fluctuations of elastic moduli. Our analysis gives a physical explanation to the observed relation between elastic heterogeneity of the rock formation and the occurrence of brittle failure during hydraulic reservoir stimulations. A crucial factor for understanding

Combination of minimum enclosing balls classifier with SVM in coal-rock recognition

Science.gov (United States)

Song, QingJun; Jiang, HaiYan; Song, Qinghui; Zhao, XieGuang; Wu, Xiaoxuan

2017-01-01

Top-coal caving technology is a productive and efficient method in modern mechanized coal mining, the study of coal-rock recognition is key to realizing automation in comprehensive mechanized coal mining. In this paper we propose a new discriminant analysis framework for coal-rock recognition. In the framework, a data acquisition model with vibration and acoustic signals is designed and the caving dataset with 10 feature variables and three classes is got. And the perfect combination of feature variables can be automatically decided by using the multi-class F-score (MF-Score) feature selection. In terms of nonlinear mapping in real-world optimization problem, an effective minimum enclosing ball (MEB) algorithm plus Support vector machine (SVM) is proposed for rapid detection of coal-rock in the caving process. In particular, we illustrate how to construct MEB-SVM classifier in coal-rock recognition which exhibit inherently complex distribution data. The proposed method is examined on UCI data sets and the caving dataset, and compared with some new excellent SVM classifiers. We conduct experiments with accuracy and Friedman test for comparison of more classifiers over multiple on the UCI data sets. Experimental results demonstrate that the proposed algorithm has good robustness and generalization ability. The results of experiments on the caving dataset show the better performance which leads to a promising feature selection and multi-class recognition in coal-rock recognition. PMID:28937987

Combination of minimum enclosing balls classifier with SVM in coal-rock recognition.

Science.gov (United States)

Song, QingJun; Jiang, HaiYan; Song, Qinghui; Zhao, XieGuang; Wu, Xiaoxuan

2017-01-01

Top-coal caving technology is a productive and efficient method in modern mechanized coal mining, the study of coal-rock recognition is key to realizing automation in comprehensive mechanized coal mining. In this paper we propose a new discriminant analysis framework for coal-rock recognition. In the framework, a data acquisition model with vibration and acoustic signals is designed and the caving dataset with 10 feature variables and three classes is got. And the perfect combination of feature variables can be automatically decided by using the multi-class F-score (MF-Score) feature selection. In terms of nonlinear mapping in real-world optimization problem, an effective minimum enclosing ball (MEB) algorithm plus Support vector machine (SVM) is proposed for rapid detection of coal-rock in the caving process. In particular, we illustrate how to construct MEB-SVM classifier in coal-rock recognition which exhibit inherently complex distribution data. The proposed method is examined on UCI data sets and the caving dataset, and compared with some new excellent SVM classifiers. We conduct experiments with accuracy and Friedman test for comparison of more classifiers over multiple on the UCI data sets. Experimental results demonstrate that the proposed algorithm has good robustness and generalization ability. The results of experiments on the caving dataset show the better performance which leads to a promising feature selection and multi-class recognition in coal-rock recognition.

Rock.XML - Towards a library of rock physics models

Science.gov (United States)

Jensen, Erling Hugo; Hauge, Ragnar; Ulvmoen, Marit; Johansen, Tor Arne; Drottning, Åsmund

2016-08-01

Rock physics modelling provides tools for correlating physical properties of rocks and their constituents to the geophysical observations we measure on a larger scale. Many different theoretical and empirical models exist, to cover the range of different types of rocks. However, upon reviewing these, we see that they are all built around a few main concepts. Based on this observation, we propose a format for digitally storing the specifications for rock physics models which we have named Rock.XML. It does not only contain data about the various constituents, but also the theories and how they are used to combine these building blocks to make a representative model for a particular rock. The format is based on the Extensible Markup Language XML, making it flexible enough to handle complex models as well as scalable towards extending it with new theories and models. This technology has great advantages as far as documenting and exchanging models in an unambiguous way between people and between software. Rock.XML can become a platform for creating a library of rock physics models; making them more accessible to everyone.

An Overview of the Adaptive Robust DFT

Directory of Open Access Journals (Sweden)

Djurović Igor

2010-01-01

Full Text Available Abstract This paper overviews basic principles and applications of the robust DFT (RDFT approach, which is used for robust processing of frequency-modulated (FM signals embedded in non-Gaussian heavy-tailed noise. In particular, we concentrate on the spectral analysis and filtering of signals corrupted by impulsive distortions using adaptive and nonadaptive robust estimators. Several adaptive estimators of location parameter are considered, and it is shown that their application is preferable with respect to non-adaptive counterparts. This fact is demonstrated by efficiency comparison of adaptive and nonadaptive RDFT methods for different noise environments.

Continuum model for water movement in an unsaturated fractured rock mass

International Nuclear Information System (INIS)

Peters, R.R.; Klavetter, E.A.

1988-01-01

The movement of fluids in a fractured, porous medium has been the subject of considerable study. This paper presents a continuum model that may be used to evaluate the isothermal movement of water in an unsaturated, fractured, porous medium under slowly changing conditions. This continuum model was developed for use in evaluating the unsaturated zone at the Yucca Mountain site as a potential repository for high-level nuclear waste. Thus its development has been influenced by the conditions thought to be present at Yucca Mountain. A macroscopic approach and a microscopic approach are used to develop a continuum model to evaluate water movement in a fractured rock mass. Both approaches assume that the pressure head in the fractures and the matrix are identical in a plane perpendicular to flow. Both approaches lead to a single-flow equation for a fractured rock mass. The two approaches are used to calculate unsaturated hydrologic properties, i.e., relative permeability and saturation as a function of pressure head, for several types of tuff underlying Yucca Mountain, using the best available hydrologic data for the matrix and the fractures. Rock mass properties calculated by both approaches are similar

A Novel Evolutionary Algorithm for Designing Robust Analog Filters

Directory of Open Access Journals (Sweden)

Shaobo Li

2018-03-01

Full Text Available Designing robust circuits that withstand environmental perturbation and device degradation is critical for many applications. Traditional robust circuit design is mainly done by tuning parameters to improve system robustness. However, the topological structure of a system may set a limit on the robustness achievable through parameter tuning. This paper proposes a new evolutionary algorithm for robust design that exploits the open-ended topological search capability of genetic programming (GP coupled with bond graph modeling. We applied our GP-based robust design (GPRD algorithm to evolve robust lowpass and highpass analog filters. Compared with a traditional robust design approach based on a state-of-the-art real-parameter genetic algorithm (GA, our GPRD algorithm with a fitness criterion rewarding robustness, with respect to parameter perturbations, can evolve more robust filters than what was achieved through parameter tuning alone. We also find that inappropriate GA tuning may mislead the search process and that multiple-simulation and perturbed fitness evaluation methods for evolving robustness have complementary behaviors with no absolute advantage of one over the other.

ROCK inhibition in models of neurodegeneration and its potential for clinical translation.

Science.gov (United States)

Koch, Jan Christoph; Tatenhorst, Lars; Roser, Anna-Elisa; Saal, Kim-Ann; Tönges, Lars; Lingor, Paul

2018-04-03

Neurodegenerative disorders like Parkinson's disease, Alzheimer's disease, or amyotrophic lateral sclerosis are affecting a rapidly increasing population worldwide. While common pathomechanisms such as protein aggregation, axonal degeneration, dysfunction of protein clearing and an altered immune response have been characterized, no disease-modifying therapies have been developed so far. Interestingly, a significant involvement of the Rho kinase (ROCK) signaling pathway has been described in all of these mechanisms making it a promising target for new therapeutic approaches. In this article, we first review current knowledge of the involvement of ROCK in neurodegenerative disorders and the utility of its inhibition as a disease-modifying therapy in different neurodegenerative disorders. After a detailed description of the biochemical characteristics of ROCK and its molecular interactors, differences of ROCK-expression under physiological and pathological conditions are compared. Next, different pharmacological and molecular-genetic strategies to inhibit ROCK-function are discussed, focusing on pharmacological ROCK-inhibitors. The role of the ROCK-pathway in cellular processes that are central in neurodegenerative disorders pathology like axonal degeneration, autophagy, synaptic and glial function is explained in detail. Finally, all available data on ROCK-inhibition in different animal models of neurodegenerative disorders is reviewed and first approaches for translation into human patients are discussed. Taken together, there is now extensive evidence from preclinical studies in several neurodegenerative disorders that characterize ROCK as a promising drug target for further translational research in neurodegenerative disorders. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

A Two-Stage DEA to Analyze the Effect of Entrance Deregulation on Iranian Insurers: A Robust Approach

Directory of Open Access Journals (Sweden)

Seyed Gholamreza Jalali Naini

2012-01-01

Full Text Available We use two-stage data envelopment analysis (DEA model to analyze the effects of entrance deregulation on the efficiency in the Iranian insurance market. In the first stage, we propose a robust optimization approach in order to overcome the sensitivity of DEA results to any uncertainty in the output parameters. Hence, the efficiency of each ongoing insurer is estimated using our proposed robust DEA model. The insurers are then ranked based on their relative efficiency scores for an eight-year period from 2003 to 2010. In the second stage, a comprehensive statistical analysis using generalized estimating equations (GEE is conducted to analyze some other factors which could possibly affect the efficiency scores. The first results from DEA model indicate a decline in efficiency over the entrance deregulation period while further statistical analysis confirms that the solvency ignorance which is a widespread paradigm among state owned companies is one of the main drivers of efficiency in the Iranian insurance market.

Robustness of digital artist authentication

DEFF Research Database (Denmark)

Jacobsen, Robert; Nielsen, Morten

In many cases it is possible to determine the authenticity of a painting from digital reproductions of the paintings; this has been demonstrated for a variety of artists and with different approaches. Common to all these methods in digital artist authentication is that the potential of the method...... is in focus, while the robustness has not been considered, i.e. the degree to which the data collection process influences the decision of the method. However, in order for an authentication method to be successful in practice, it needs to be robust to plausible error sources from the data collection....... In this paper we investigate the robustness of the newly proposed authenticity method introduced by the authors based on second generation multiresolution analysis. This is done by modelling a number of realistic factors that can occur in the data collection....

Robust Methods for Moderation Analysis with a Two-Level Regression Model.

Science.gov (United States)

Yang, Miao; Yuan, Ke-Hai

2016-01-01

Moderation analysis has many applications in social sciences. Most widely used estimation methods for moderation analysis assume that errors are normally distributed and homoscedastic. When these assumptions are not met, the results from a classical moderation analysis can be misleading. For more reliable moderation analysis, this article proposes two robust methods with a two-level regression model when the predictors do not contain measurement error. One method is based on maximum likelihood with Student's t distribution and the other is based on M-estimators with Huber-type weights. An algorithm for obtaining the robust estimators is developed. Consistent estimates of standard errors of the robust estimators are provided. The robust approaches are compared against normal-distribution-based maximum likelihood (NML) with respect to power and accuracy of parameter estimates through a simulation study. Results show that the robust approaches outperform NML under various distributional conditions. Application of the robust methods is illustrated through a real data example. An R program is developed and documented to facilitate the application of the robust methods.

Seismic stability analysis of rock slopes by yield design theory using the generalized Hoek-Brown criterion

Directory of Open Access Journals (Sweden)

Belghali Mounir

2018-01-01

Full Text Available The stability of rock slope is studied using the kinematic approach of yield design theory, under the condition of plane strain and by considering the last version of the Hoek-Brown failure criterion. This criterion, which is suitable to intact rock or rock mass highly fractured regarded as isotropic and homogeneous, is widely accepted by the rock mechanics community and has been applied in numerous projects around the world. The failure mechanism used to implement the kinematic approach is a log-spiral rotational mechanism. The stability analysis is carried out under the effects of gravity forces and a surcharge applied along the upper plateau of the slope. To take account of the effects of forces developed in the rock mass during the passage of a seismic wave, the conventional pseudo-static method is adopted. This method is often used in slope stability study for its simplicity and efficiency to simulate the seismic forces. The results found are compared with published numerical solutions obtained from other approaches. The comparison showed that the results are almost equal. The maximum error found is less than 1%, indicating that this approach is effective for analyzing the stability of rock slopes. The relevance of the approach demonstrated, investigations are undertaken to study the influence of some parameters on the stability of the slope. These parameters relate to the mechanical strength of the rock, slope geometry and loading.

A Discrete Element Method Approach to Progressive Localization of Damage in Granular Rocks and Associated Seismicity

Science.gov (United States)

Vora, H.; Morgan, J.

2017-12-01

Brittle failure in rock under confined biaxial conditions is accompanied by release of seismic energy, known as acoustic emissions (AE). The objective our study is to understand the influence of elastic properties of rock and its stress state on deformation patterns, and associated seismicity in granular rocks. Discrete Element Modeling is used to simulate biaxial tests on granular rocks of defined grain size distribution. Acoustic Energy and seismic moments are calculated from microfracture events as rock is taken to conditions of failure under different confining pressure states. Dimensionless parameters such as seismic b-value and fractal parameter for deformation, D-value, are used to quantify seismic character and distribution of damage in rock. Initial results suggest that confining pressure has the largest control on distribution of induced microfracturing, while fracture energy and seismic magnitudes are highly sensitive to elastic properties of rock. At low confining pressures, localized deformation (low D-values) and high seismic b-values are observed. Deformation at high confining pressures is distributed in nature (high D-values) and exhibit low seismic b-values as shearing becomes the dominant mode of microfracturing. Seismic b-values and fractal D-values obtained from microfracturing exhibit a linear inverse relationship, similar to trends observed in earthquakes. Mode of microfracturing in our simulations of biaxial compression tests show mechanistic similarities to propagation of fractures and faults in nature.

Penalobo "Castle Rocks" - First approach to valuing this geoforms.

Science.gov (United States)

Pinharandas, Carlos; Nobre, José; Gomes, Ana

2013-04-01

The village of Penalobo, located in the municipality of Sabugal (Portugal) is characterized by hercynian granites with interesting geological features, including pegmatite veins and quartz crystals with exotic forms, and presents some steep slopes and plateaus. From the mountainous configuration highlight some more pronounced elevations called "Castle Rocks". Such structures are composed by granites, which present greater fracturing at the top, which leads to the formation of large granite blocks. In less fractured zones it is possible to observe small folds. An excavation existing in one of those elevations allows us to observe a basic rock outcropping with clusters of crystals mottled with circular shape, which are indicative of the presence of late fluid during crystallization. In the zone of contact with the enclosing granite, there are small folds caused by magma intrusion. Those evidences led us to hypothesize that the peaks observed in the area of Penalobo village were due to the intrusion on basic magma. All this framework and geological environment becomes an asset for the scientific, educational and economic development of the region. On the other hand, it has a vital importance in the context of a strategy of forming a geological park, in the point of view of tourism, research and interpretation.

Rock burst governance of working face under igneous rock

Science.gov (United States)

Chang, Zhenxing; Yu, Yue

2017-01-01

As a typical failure phenomenon, rock burst occurs in many mines. It can not only cause the working face to cease production, but also cause serious damage to production equipment, and even result in casualties. To explore how to govern rock burst of working face under igneous rock, the 10416 working face in some mine is taken as engineering background. The supports damaged extensively and rock burst took place when the working face advanced. This paper establishes the mechanical model and conducts theoretical analysis and calculation to predict the fracture and migration mechanism and energy release of the thick hard igneous rock above the working face, and to obtain the advancing distance of the working face when the igneous rock fractures and critical value of the energy when rock burst occurs. Based on the specific conditions of the mine, this paper put forward three kinds of governance measures, which are borehole pressure relief, coal seam water injection and blasting pressure relief.

Robust PLS approach for KPI-related prediction and diagnosis against outliers and missing data

Science.gov (United States)

Yin, Shen; Wang, Guang; Yang, Xu

2014-07-01

In practical industrial applications, the key performance indicator (KPI)-related prediction and diagnosis are quite important for the product quality and economic benefits. To meet these requirements, many advanced prediction and monitoring approaches have been developed which can be classified into model-based or data-driven techniques. Among these approaches, partial least squares (PLS) is one of the most popular data-driven methods due to its simplicity and easy implementation in large-scale industrial process. As PLS is totally based on the measured process data, the characteristics of the process data are critical for the success of PLS. Outliers and missing values are two common characteristics of the measured data which can severely affect the effectiveness of PLS. To ensure the applicability of PLS in practical industrial applications, this paper introduces a robust version of PLS to deal with outliers and missing values, simultaneously. The effectiveness of the proposed method is finally demonstrated by the application results of the KPI-related prediction and diagnosis on an industrial benchmark of Tennessee Eastman process.

A bio-economic application to the Cape Rock Lobster resource using a delay difference modelling approach

Directory of Open Access Journals (Sweden)

E Roos

2004-06-01

Full Text Available In many species, like the Cape Rock Lobster (Jasus lalandii, the life cycles of males and females differ. This may motivate the use of two-sex models in a stock-assessment analysis. It is also true for this resource, that juveniles do not reach sexual maturity immediately. Therefore a delay-difference model is appropriate. In this study we follow a bio-economic approach and use a two-sex delay-difference model to determine a maximum economic yield strategy. Thus we determine an economic optimum steady state solution at which to harvest this resource subject to the biological constraints of the species.

Classification and Distribution of Mars Pathfinder Rocks Using Quantitative Morphologic Indices

Science.gov (United States)

Yingst, R. A.; Biederman, K. L.; Monhead, A. M.; Haldemann, A. F. C.; Kowalczyk, M. R.

2004-01-01

The Mars Pathfinder (MPF) landing site was predicted to contain a broad sampling of rock types varying in mineralogical, physical, mechanical and geochemical characteristics. Although rocks have been divided into several spectral categories based on Imager for Mars Pathfinder visible/near-infrared spectra, it has not been fully determined which of these stem from intrinsic mineralogical differences between rocks or rock surfaces, and which result from factors such as physical or chemical weathering. This has made isolation of unique mineralogy's difficult. Efforts in isolating and classifying spectral units among MPF rocks and soils have met with varying degrees of success, and the current understanding is such that many factors influencing spectral signatures cannot be quantified to a sufficient level so they may be removed. The result is that fundamental questions regarding information needed to reveal the present and past interactions between the rocks and rock surfaces and the Martian environment remain unanswered. But it is possible to approach the issue of identifying distinct rock and rock surface types from a different angle.

Segmentation-less Digital Rock Physics

Science.gov (United States)

Tisato, N.; Ikeda, K.; Goldfarb, E. J.; Spikes, K. T.

2017-12-01

In the last decade, Digital Rock Physics (DRP) has become an avenue to investigate physical and mechanical properties of geomaterials. DRP offers the advantage of simulating laboratory experiments on numerical samples that are obtained from analytical methods. Potentially, DRP could allow sparing part of the time and resources that are allocated to perform complicated laboratory tests. Like classic laboratory tests, the goal of DRP is to estimate accurately physical properties of rocks like hydraulic permeability or elastic moduli. Nevertheless, the physical properties of samples imaged using micro-computed tomography (μCT) are estimated through segmentation of the μCT dataset. Segmentation proves to be a challenging and arbitrary procedure that typically leads to inaccurate estimates of physical properties. Here we present a novel technique to extract physical properties from a μCT dataset without the use of segmentation. We show examples in which we use segmentation-less method to simulate elastic wave propagation and pressure wave diffusion to estimate elastic properties and permeability, respectively. The proposed method takes advantage of effective medium theories and uses the density and the porosity that are measured in the laboratory to constrain the results. We discuss the results and highlight that segmentation-less DRP is more accurate than segmentation based DRP approaches and theoretical modeling for the studied rock. In conclusion, the segmentation-less approach here presented seems to be a promising method to improve accuracy and to ease the overall workflow of DRP.

Using CTX Image Features to Predict HiRISE-Equivalent Rock Density

Science.gov (United States)

Serrano, Navid; Huertas, Andres; McGuire, Patrick; Mayer, David; Ardvidson, Raymond

2010-01-01

Methods have been developed to quantitatively assess rock hazards at candidate landing sites with the aid of images from the HiRISE camera onboard NASA s Mars Reconnaissance Orbiter. HiRISE is able to resolve rocks as small as 1-m in diameter. Some sites of interest do not have adequate coverage with the highest resolution sensors and there is a need to infer relevant information (like site safety or underlying geomorphology). The proposed approach would make it possible to obtain rock density estimates at a level close to or equal to those obtained from high-resolution sensors where individual rocks are discernable.

For Those About to Rock : Naislaulajat rock-genressä

OpenAIRE

Herranen, Linda

2015-01-01

For those about to rock – naislaulajat rock-genressä antaa lukijalleen kokonaisvaltaisen käsityksen naisista rock-genressä: rockin historiasta, sukupuolittuneisuudesta, seksismistä, suomalaisten naislaulajien menestyksestä. Työn aineisto on koottu aihepiirin kirjallisuudesta ja alalla toimiville naislaulajille teetettyjen kyselyiden tuloksista. Lisäksi avaan omia kokemuksiani ja ajatuksiani, jotta näkökulma naisista rock-genressä tulisi esille mahdollisimman monipuolisesti. Ajatus aihees...

Robust Topology Optimization Based on Stochastic Collocation Methods under Loading Uncertainties

Directory of Open Access Journals (Sweden)

Qinghai Zhao

2015-01-01

Full Text Available A robust topology optimization (RTO approach with consideration of loading uncertainties is developed in this paper. The stochastic collocation method combined with full tensor product grid and Smolyak sparse grid transforms the robust formulation into a weighted multiple loading deterministic problem at the collocation points. The proposed approach is amenable to implementation in existing commercial topology optimization software package and thus feasible to practical engineering problems. Numerical examples of two- and three-dimensional topology optimization problems are provided to demonstrate the proposed RTO approach and its applications. The optimal topologies obtained from deterministic and robust topology optimization designs under tensor product grid and sparse grid with different levels are compared with one another to investigate the pros and cons of optimization algorithm on final topologies, and an extensive Monte Carlo simulation is also performed to verify the proposed approach.

Robust and scalable optical one-way quantum computation

International Nuclear Information System (INIS)

Wang Hefeng; Yang Chuiping; Nori, Franco

2010-01-01

We propose an efficient approach for deterministically generating scalable cluster states with photons. This approach involves unitary transformations performed on atoms coupled to optical cavities. Its operation cost scales linearly with the number of qubits in the cluster state, and photon qubits are encoded such that single-qubit operations can be easily implemented by using linear optics. Robust optical one-way quantum computation can be performed since cluster states can be stored in atoms and then transferred to photons that can be easily operated and measured. Therefore, this proposal could help in performing robust large-scale optical one-way quantum computation.

PARAMETER COORDINATION AND ROBUST OPTIMIZATION FOR MULTIDISCIPLINARY DESIGN

Institute of Scientific and Technical Information of China (English)

HU Jie; PENG Yinghong; XIONG Guangleng

2006-01-01

A new parameter coordination and robust optimization approach for multidisciplinary design is presented. Firstly, the constraints network model is established to support engineering change, coordination and optimization. In this model, interval boxes are adopted to describe the uncertainty of design parameters quantitatively to enhance the design robustness. Secondly, the parameter coordination method is presented to solve the constraints network model, monitor the potential conflicts due to engineering changes, and obtain the consistency solution space corresponding to the given product specifications. Finally, the robust parameter optimization model is established, and genetic arithmetic is used to obtain the robust optimization parameter. An example of bogie design is analyzed to show the scheme to be effective.

Advances in robust fractional control

CERN Document Server

Padula, Fabrizio

2015-01-01

This monograph presents design methodologies for (robust) fractional control systems. It shows the reader how to take advantage of the superior flexibility of fractional control systems compared with integer-order systems in achieving more challenging control requirements. There is a high degree of current interest in fractional systems and fractional control arising from both academia and industry and readers from both milieux are catered to in the text. Different design approaches having in common a trade-off between robustness and performance of the control system are considered explicitly. The text generalizes methodologies, techniques and theoretical results that have been successfully applied in classical (integer) control to the fractional case. The first part of Advances in Robust Fractional Control is the more industrially-oriented. It focuses on the design of fractional controllers for integer processes. In particular, it considers fractional-order proportional-integral-derivative controllers, becau...

Art Rocks with Rock Art!

Science.gov (United States)

Bickett, Marianne

2011-01-01

This article discusses rock art which was the very first "art." Rock art, such as the images created on the stone surfaces of the caves of Lascaux and Altimira, is the true origin of the canvas, paintbrush, and painting media. For there, within caverns deep in the earth, the first artists mixed animal fat, urine, and saliva with powdered minerals…

Sinkhole susceptibility in carbonate rocks of the Apulian karst (southern Italy)

Science.gov (United States)

Di Santo, Antonio; Fazio, Nunzio L.; Fiore, Antonio; Lollino, Piernicola; Luisi, Michele; Miccoli, Maria N.; Pagliarulo, Rosa; Parise, Mario; Perrotti, Michele; Pisano, Luca; Spalluto, Luigi; Vennari, Carmela; Vessia, Giovanna

2016-04-01

modelling the instability processes, and the development of charts for a preliminary evaluation of the stability of underground caves. Two distinct approaches were established to take into account the different petrographic, structural and geotechnical features of both the hard and soft carbonate rocks. The approach dealing with hard carbonate rocks (where natural karst caves develop) is based on speleological and geometrical surveys of the caves and on an integrated geological and geomechanical characterization of the carbonate rock mass, aimed at individuating the main critical aspects of the karst caves in terms of likely effects on the society. On the other hand, the approach to verify the stability of soft rocks where artificial cavities have been excavated is mostly dependent upon the peculiar petrographic and geomechanical characteristics of the calcarenite rock mass, typically massive and unaffected by tectonic discontinuities. As a consequence, the traditional analytical methods of rock mass classification fail in these materials, since the rock strength of soft calcarenites is mostly dependent upon sediment texture, porosity type and distribution and degree of cementation. The fluid circulation into the rock mass is also important because the removal of the rock matrix may induce a rapid deterioration of the mechanical behaviour of the rock mass. The approach to the calcarenite is mostly based on the characterization of petrographic and geotechnical parameters by means of direct sampling from the rock walls and in situ surveys (wells, trenches, etc.). Through implementation of the two approaches, our goal is to reconstruct accurate geometrical, geological and geotechnical models for both natural caves and artificial cavities. These models will be useful also to plan specific monitoring activities in order to understand the development of underground instability, and the related evolution through the rock mass, possibly threatening the urban areas and

Antecedents and Dimensions of Supply Chain Robustness

OpenAIRE

Durach, Christian F.; Wieland, Andreas; Machuca, Jose A.D.

2015-01-01

Purpose – The purpose of this paper is to provide groundwork for an emerging theory of supply chain robustness – which has been conceptualized as a dimension of supply chain resilience – through reviewing and synthesizing related yet disconnected studies. The paper develops a formal definition of supply chain robustness to build a framework that captures the dimensions, antecedents and moderators of the construct as discussed in the literature. Design/methodology/approach – The...

An Integrated Approach to Single-Leg Airline Revenue Management: The Role of Robust Optimization

OpenAIRE

Birbil, S.I.; Frenk, J.B.G.; Gromicho, J.A.S.; Zhang, S.

2006-01-01

textabstractIn this paper we introduce robust versions of the classical static and dynamic single leg seat allocation models as analyzed by Wollmer, and Lautenbacher and Stidham, respectively. These robust models take into account the inaccurate estimates of the underlying probability distributions. As observed by simulation experiments it turns out that for these robust versions the variability compared to their classical counter parts is considerably reduced with a negligible decrease of av...

A novel non-probabilistic approach using interval analysis for robust design optimization

International Nuclear Information System (INIS)

Sun, Wei; Dong, Rongmei; Xu, Huanwei

2009-01-01

A technique for formulation of the objective and constraint functions with uncertainty plays a crucial role in robust design optimization. This paper presents the first application of interval methods for reformulating the robust optimization problem. Based on interval mathematics, the original real-valued objective and constraint functions are replaced with the interval-valued functions, which directly represent the upper and lower bounds of the new functions under uncertainty. The single objective function is converted into two objective functions for minimizing the mean value and the variation, and the constraint functions are reformulated with the acceptable robustness level, resulting in a bi-level mathematical model. Compared with other methods, this method is efficient and does not require presumed probability distribution of uncertain factors or gradient or continuous information of constraints. Two numerical examples are used to illustrate the validity and feasibility of the presented method

Robust structural optimization using Gauss-type quadrature formula

International Nuclear Information System (INIS)

Lee, Sang Hoon; Seo, Ki Seog; Chen, Shikui; Chen, Wei

2009-01-01

In robust design, the mean and variance of design performance are frequently used to measure the design performance and its robustness under uncertainties. In this paper, we present the Gauss-type quadrature formula as a rigorous method for mean and variance estimation involving arbitrary input distributions and further extend its use to robust design optimization. One dimensional Gauss-type quadrature formula are constructed from the input probability distributions and utilized in the construction of multidimensional quadrature formula such as the Tensor Product Quadrature (TPQ) formula and the Univariate Dimension Reduction (UDR) method. To improve the efficiency of using it for robust design optimization, a semi-analytic design sensitivity analysis with respect to the statistical moments is proposed. The proposed approach is applied to a simple bench mark problems and robust topology optimization of structures considering various types of uncertainty.

Robust structural optimization using Gauss-type quadrature formula

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang Hoon; Seo, Ki Seog [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Chen, Shikui; Chen, Wei [Northwestern University, Illinois (United States)

2009-07-01

In robust design, the mean and variance of design performance are frequently used to measure the design performance and its robustness under uncertainties. In this paper, we present the Gauss-type quadrature formula as a rigorous method for mean and variance estimation involving arbitrary input distributions and further extend its use to robust design optimization. One dimensional Gauss-type quadrature formula are constructed from the input probability distributions and utilized in the construction of multidimensional quadrature formula such as the Tensor Product Quadrature (TPQ) formula and the Univariate Dimension Reduction (UDR) method. To improve the efficiency of using it for robust design optimization, a semi-analytic design sensitivity analysis with respect to the statistical moments is proposed. The proposed approach is applied to a simple bench mark problems and robust topology optimization of structures considering various types of uncertainty.

Robust Structural Optimization Using Gauss-type Quadrature Formula

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang Hoon; Seo, Ki Seog; Chen, Shikui; Chen, Wei [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-08-15

In robust design, the mean and variance of design performance are frequently used to measure the design performance and its robustness under uncertainties. In this paper, we present the Gauss-type quadrature formula as a rigorous method for mean and variance estimation involving arbitrary input distributions and further extend its use to robust design optimization. One dimensional Gauss-type quadrature formula are constructed from the input probability distributions and utilized in the construction of multidimensional quadrature formula such as the tensor product quadrature (TPQ) formula and the univariate dimension reduction (UDR) method. To improve the efficiency of using it for robust design optimization, a semi-analytic design sensitivity analysis with respect to the statistical moments is proposed. The proposed approach is applied to a simple bench mark problems and robust topology optimization of structures considering various types of uncertainty.

Robust Structural Optimization Using Gauss-type Quadrature Formula

International Nuclear Information System (INIS)

Lee, Sang Hoon; Seo, Ki Seog; Chen, Shikui; Chen, Wei

2009-01-01

In robust design, the mean and variance of design performance are frequently used to measure the design performance and its robustness under uncertainties. In this paper, we present the Gauss-type quadrature formula as a rigorous method for mean and variance estimation involving arbitrary input distributions and further extend its use to robust design optimization. One dimensional Gauss-type quadrature formula are constructed from the input probability distributions and utilized in the construction of multidimensional quadrature formula such as the tensor product quadrature (TPQ) formula and the univariate dimension reduction (UDR) method. To improve the efficiency of using it for robust design optimization, a semi-analytic design sensitivity analysis with respect to the statistical moments is proposed. The proposed approach is applied to a simple bench mark problems and robust topology optimization of structures considering various types of uncertainty

Robust image authentication in the presence of noise

CERN Document Server

2015-01-01

This book addresses the problems that hinder image authentication in the presence of noise. It considers the advantages and disadvantages of existing algorithms for image authentication and shows new approaches and solutions for robust image authentication. The state of the art algorithms are compared and, furthermore, innovative approaches and algorithms are introduced. The introduced algorithms are applied to improve image authentication, watermarking and biometry.    Aside from presenting new directions and algorithms for robust image authentication in the presence of noise, as well as image correction, this book also:   Provides an overview of the state of the art algorithms for image authentication in the presence of noise and modifications, as well as a comparison of these algorithms, Presents novel algorithms for robust image authentication, whereby the image is tried to be corrected and authenticated, Examines different views for the solution of problems connected to image authentication in the pre...

Robust and Efficient Parametric Face Alignment

NARCIS (Netherlands)

Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja

2011-01-01

We propose a correlation-based approach to parametric object alignment particularly suitable for face analysis applications which require efficiency and robustness against occlusions and illumination changes. Our algorithm registers two images by iteratively maximizing their correlation coefficient

Processes, mechanisms, parameters, and modeling approaches for partially saturated flow in soil and rock media

International Nuclear Information System (INIS)

Wang, J.S.Y.; Narasimhan, T.N.

1993-06-01

This report discusses conceptual models and mathematical equations, analyzes distributions and correlations among hydrological parameters of soils and tuff, introduces new path integration approaches, and outlines scaling procedures to model potential-driven fluid flow in heterogeneous media. To properly model the transition from fracture-dominated flow under saturated conditions to matrix-dominated flow under partially saturated conditions, characteristic curves and permeability functions for fractures and matrix need to be improved and validated. Couplings from two-phase flow, heat transfer, solute transport, and rock deformation to liquid flow are also important. For stochastic modeling of alternating units of welded and nonwelded tuff or formations bounded by fault zones, correlations and constraints on average values of saturated permeability and air entry scaling factor between different units need to be imposed to avoid unlikely combinations of parameters and predictions. Large-scale simulations require efficient and verifiable numerical algorithms. New path integration approaches based on postulates of minimum work and mass conservation to solve flow geometry and potential distribution simultaneously are introduced. This verifiable integral approach, together with fractal scaling procedures to generate statistical realizations with parameter distribution, correlation, and scaling taken into account, can be used to quantify uncertainties and generate the cumulative distribution function for groundwater travel times

Combination of minimum enclosing balls classifier with SVM in coal-rock recognition.

Directory of Open Access Journals (Sweden)

QingJun Song

Full Text Available Top-coal caving technology is a productive and efficient method in modern mechanized coal mining, the study of coal-rock recognition is key to realizing automation in comprehensive mechanized coal mining. In this paper we propose a new discriminant analysis framework for coal-rock recognition. In the framework, a data acquisition model with vibration and acoustic signals is designed and the caving dataset with 10 feature variables and three classes is got. And the perfect combination of feature variables can be automatically decided by using the multi-class F-score (MF-Score feature selection. In terms of nonlinear mapping in real-world optimization problem, an effective minimum enclosing ball (MEB algorithm plus Support vector machine (SVM is proposed for rapid detection of coal-rock in the caving process. In particular, we illustrate how to construct MEB-SVM classifier in coal-rock recognition which exhibit inherently complex distribution data. The proposed method is examined on UCI data sets and the caving dataset, and compared with some new excellent SVM classifiers. We conduct experiments with accuracy and Friedman test for comparison of more classifiers over multiple on the UCI data sets. Experimental results demonstrate that the proposed algorithm has good robustness and generalization ability. The results of experiments on the caving dataset show the better performance which leads to a promising feature selection and multi-class recognition in coal-rock recognition.

Geological constraints for muon tomography: The world beyond standard rock

Science.gov (United States)

Lechmann, Alessandro; Mair, David; Ariga, Akitaka; Ariga, Tomoko; Ereditato, Antonio; Käser, Samuel; Nishiyama, Ryuichi; Scampoli, Paola; Vladymyrov, Mykhailo; Schlunegger, Fritz

2017-04-01

In present day muon tomography practice, one often encounters an experimental setup in which muons propagate several tens to a few hundreds of meters through a material to the detector. The goal of such an undertaking is usually centred on an attempt to make inferences from the measured muon flux to an anticipated subsurface structure. This can either be an underground interface geometry or a spatial material distribution. Inferences in this direction have until now mostly been done, thereby using the so called "standard rock" approximation. This includes a set of empirically determined parameters from several rocks found in the vicinity of physicist's laboratories. While this approach is reasonable to account for the effects of the tens of meters of soil/rock around a particle accelerator, we show, that for material thicknesses beyond that dimension, the elementary composition of the material (average atomic weight and atomic number) has a noticeable effect on the measured muon flux. Accordingly, the consecutive use of this approximation could potentially lead into a serious model bias, which in turn, might invalidate any tomographic inference, that base on this standard rock approximation. The parameters for standard rock are naturally close to a granitic (SiO2-rich) composition and thus can be safely used in such environments. As geophysical surveys are not restricted to any particular lithology, we investigated the effect of alternative rock compositions (carbonatic, basaltic and even ultramafic) and consequentially prefer to replace the standard rock approach with a dedicated geological investigation. Structural field data and laboratory measurements of density (He-Pycnometer) and composition (XRD) can be merged into an integrative geological model that can be used as an a priori constraint for the rock parameters of interest (density & composition) in the geophysical inversion. Modelling results show that when facing a non-granitic lithology the measured muon

Depositional environment and source rock potential of Cenomanian and Turonian sedimentary rocks of the Tarfaya Basin, Southwest Morocco

Energy Technology Data Exchange (ETDEWEB)

Ghassal, B.I.; Littke, R.; Sachse, V.; Sindern, S.; Schwarzbauer, J.

2016-07-01

from bituminite-fair to bituminite-rich and to higher percentages of visible organic matter towards the younger interval. These differences in the organic matter type are attributed to i) early diagenetic kerogen sulfurization and ii) the upwelling depositional environment. Moreover, kerogen sulfurization was controlled by the relationship between carbonate, iron and sulfur as well as the organic matter. Thus, the organic carbon-rich deposits can be grouped into: i) low Sorg and moderately organic matter-rich oil prone source rocks, ii) moderate Sorg and organic-carbon-rich oil prone source rocks, iii) high Sorg and organic carbon-rich oil prone source rocks and iv) very high Sorg and organic carbon-rich oil prone source rocks, the latter representing the CTBE interval. Types 2 to 4 will generate sulfur-rich petroleum upon maturation or artificial oil shale retorting. This integrated organic and inorganic approach sheds light on the various processes leading to the development of the world-class oil shales deposited through the Cenomanian to Turonian. In addition, this study shows how the changes in the depositional environment might have controlled kerogen sulfurization and organic matter preservation and structure. This detailed approach provides a better understanding on source rock development during the Cenomanian to Turonian in a global context, as many of the geochemical features were identified worldwide for deposits related to OAE2. (Author)

Imaging and computational considerations for image computed permeability: Operating envelope of Digital Rock Physics

Science.gov (United States)

Saxena, Nishank; Hows, Amie; Hofmann, Ronny; Alpak, Faruk O.; Freeman, Justin; Hunter, Sander; Appel, Matthias

2018-06-01

This study defines the optimal operating envelope of the Digital Rock technology from the perspective of imaging and numerical simulations of transport properties. Imaging larger volumes of rocks for Digital Rock Physics (DRP) analysis improves the chances of achieving a Representative Elementary Volume (REV) at which flow-based simulations (1) do not vary with change in rock volume, and (2) is insensitive to the choice of boundary conditions. However, this often comes at the expense of image resolution. This trade-off exists due to the finiteness of current state-of-the-art imaging detectors. Imaging and analyzing digital rocks that sample the REV and still sufficiently resolve pore throats is critical to ensure simulation quality and robustness of rock property trends for further analysis. We find that at least 10 voxels are needed to sufficiently resolve pore throats for single phase fluid flow simulations. If this condition is not met, additional analyses and corrections may allow for meaningful comparisons between simulation results and laboratory measurements of permeability, but some cases may fall outside the current technical feasibility of DRP. On the other hand, we find that the ratio of field of view and effective grain size provides a reliable measure of the REV for siliciclastic rocks. If this ratio is greater than 5, the coefficient of variation for single-phase permeability simulations drops below 15%. These imaging considerations are crucial when comparing digitally computed rock flow properties with those measured in the laboratory. We find that the current imaging methods are sufficient to achieve both REV (with respect to numerical boundary conditions) and required image resolution to perform digital core analysis for coarse to fine-grained sandstones.

ROBUST CONTROL OF END-TIDAL CO2 USING THE H∞ LOOP-SHAPING APPROACH

Directory of Open Access Journals (Sweden)

Anake Pomprapa

2013-12-01

Full Text Available Mechanically ventilated patients require appropriate settings of respiratory control variables to maintain acceptable gas exchange. To control the carbon dioxide (CO2 level effectively and automatically, system identification based on a human subject was performed using a linear affine model and a nonlinear Hammerstein structure. Subsequently, a robust controller was designed using the H∞ loop-shaping approach, which synthesizes the optimal controller based on a specific objective by achieving stability with guaranteed performance. For demonstration purposes, the closed-loop control ventilation system was successfully tested in a human volunteer. The experimental results indicate that the blood CO2 level may indeed be controlled noninvasively by measuring end-tidal CO2 from expired air. Keeping the limited amount of experimental data in mind, we conclude that H∞ loop-shaping may be a promising technique for control of mechanical ventilation in patients with respiratory insufficiency.

TAO-robust backpropagation learning algorithm.

Science.gov (United States)

Pernía-Espinoza, Alpha V; Ordieres-Meré, Joaquín B; Martínez-de-Pisón, Francisco J; González-Marcos, Ana

2005-03-01

In several fields, as industrial modelling, multilayer feedforward neural networks are often used as universal function approximations. These supervised neural networks are commonly trained by a traditional backpropagation learning format, which minimises the mean squared error (mse) of the training data. However, in the presence of corrupted data (outliers) this training scheme may produce wrong models. We combine the benefits of the non-linear regression model tau-estimates [introduced by Tabatabai, M. A. Argyros, I. K. Robust Estimation and testing for general nonlinear regression models. Applied Mathematics and Computation. 58 (1993) 85-101] with the backpropagation algorithm to produce the TAO-robust learning algorithm, in order to deal with the problems of modelling with outliers. The cost function of this approach has a bounded influence function given by the weighted average of two psi functions, one corresponding to a very robust estimate and the other to a highly efficient estimate. The advantages of the proposed algorithm are studied with an example.

A kriging metamodel-assisted robust optimization method based on a reverse model

Science.gov (United States)

Zhou, Hui; Zhou, Qi; Liu, Congwei; Zhou, Taotao

2018-02-01

The goal of robust optimization methods is to obtain a solution that is both optimum and relatively insensitive to uncertainty factors. Most existing robust optimization approaches use outer-inner nested optimization structures where a large amount of computational effort is required because the robustness of each candidate solution delivered from the outer level should be evaluated in the inner level. In this article, a kriging metamodel-assisted robust optimization method based on a reverse model (K-RMRO) is first proposed, in which the nested optimization structure is reduced into a single-loop optimization structure to ease the computational burden. Ignoring the interpolation uncertainties from kriging, K-RMRO may yield non-robust optima. Hence, an improved kriging-assisted robust optimization method based on a reverse model (IK-RMRO) is presented to take the interpolation uncertainty of kriging metamodel into consideration. In IK-RMRO, an objective switching criterion is introduced to determine whether the inner level robust optimization or the kriging metamodel replacement should be used to evaluate the robustness of design alternatives. The proposed criterion is developed according to whether or not the robust status of the individual can be changed because of the interpolation uncertainties from the kriging metamodel. Numerical and engineering cases are used to demonstrate the applicability and efficiency of the proposed approach.

Rock Art

Science.gov (United States)

Henn, Cynthia A.

2004-01-01

There are many interpretations for the symbols that are seen in rock art, but no decoding key has ever been discovered. This article describes one classroom's experiences with a lesson on rock art--making their rock art and developing their own personal symbols. This lesson allowed for creativity, while giving an opportunity for integration…

Musical Structure as Narrative in Rock

Directory of Open Access Journals (Sweden)

John Fernando Encarnacao

2011-09-01

Full Text Available In an attempt to take a fresh look at the analysis of form in rock music, this paper uses Susan McClary’s (2000 idea of ‘quest narrative’ in Western art music as a starting point. While much pop and rock adheres to the basic structure of the establishment of a home territory, episodes or adventures away, and then a return, my study suggests three categories of rock music form that provide alternatives to common combinations of verses, choruses and bridges through which the quest narrative is delivered. Labyrinth forms present more than the usual number of sections to confound our sense of ‘home’, and consequently of ‘quest’. Single-cell forms use repetition to suggest either a kind of stasis or to disrupt our expectations of beginning, middle and end. Immersive forms blur sectional divisions and invite more sensual and participatory responses to the recorded text. With regard to all of these alternative approaches to structure, Judy Lochhead’s (1992 concept of ‘forming’ is called upon to underline rock music forms that unfold as process, rather than map received formal constructs. Central to the argument are a couple of crucial definitions. Following Theodore Gracyk (1996, it is not songs, as such, but particular recordings that constitute rock music texts. Additionally, narrative is understood not in (direct relation to the lyrics of a song, nor in terms of artists’ biographies or the trajectories of musical styles, but considered in terms of musical structure. It is hoped that this outline of non-narrative musical structures in rock may have applications not only to other types of music, but to other time-based art forms.

Geomechanical characterization of volcanic rocks using empirical systems and data mining techniques

Directory of Open Access Journals (Sweden)

T. Miranda

2018-02-01

Full Text Available This paper tries to characterize volcanic rocks through the development and application of an empirical geomechanical system. Geotechnical information was collected from the samples from several Atlantic Ocean islands including Madeira, Azores and Canarias archipelagos. An empirical rock classification system termed as the volcanic rock system (VRS is developed and presented in detail. Results using the VRS are compared with those obtained using the traditional rock mass rating (RMR system. Data mining (DM techniques are applied to a database of volcanic rock geomechanical information from the islands. Different algorithms were developed and consequently approaches were followed for predicting rock mass classes using the VRS and RMR classification systems. Finally, some conclusions are drawn with emphasis on the fact that a better performance was achieved using attributes from VRS.

Controlled grafting of vinylic monomers on polyolefins: a robust mathematical modeling approach.

Science.gov (United States)

Saeb, Mohammad Reza; Rezaee, Babak; Shadman, Alireza; Formela, Krzysztof; Ahmadi, Zahed; Hemmati, Farkhondeh; Kermaniyan, Tayebeh Sadat; Mohammadi, Yousef

2017-01-01

Experimental and mathematical modeling analyses were used for controlling melt free-radical grafting of vinylic monomers on polyolefins and, thereby, reducing the disturbance of undesired cross-linking of polyolefins. Response surface, desirability function, and artificial intelligence methodologies were blended to modeling/optimization of grafting reaction in terms of vinylic monomer content, peroxide initiator concentration, and melt-processing time. An in-house code was developed based on artificial neural network that learns and mimics processing torque and grafting of glycidyl methacrylate (GMA) typical vinylic monomer on high-density polyethylene (HDPE). Application of response surface and desirability function enabled concurrent optimization of processing torque and GMA grafting on HDPE, through which we quantified for the first time competition between parallel reactions taking place during melt processing: (i) desirable grafting of GMA on HDPE; (ii) undesirable cross-linking of HDPE. The proposed robust mathematical modeling approach can precisely learn the behavior of grafting reaction of vinylic monomers on polyolefins and be placed into practice in finding exact operating condition needed for efficient grafting of reactive monomers on polyolefins.

Creating geometrically robust designs for highly sensitive problems using topology optimization: Acoustic cavity design

DEFF Research Database (Denmark)

Christiansen, Rasmus E.; Lazarov, Boyan S.; Jensen, Jakob S.

2015-01-01

Resonance and wave-propagation problems are known to be highly sensitive towards parameter variations. This paper discusses topology optimization formulations for creating designs that perform robustly under spatial variations for acoustic cavity problems. For several structural problems, robust...... and limitations are discussed. In addition, a known explicit penalization approach is considered for comparison. For near-uniform spatial variations it is shown that highly robust designs can be obtained using the double filter approach. It is finally demonstrated that taking non-uniform variations into account...... further improves the robustness of the designs....

Estimation of hydrologic properties of an unsaturated, fractured rock mass

International Nuclear Information System (INIS)

Klavetter, E.A.; Peters, R.R.

1986-07-01

In this document, two distinctly different approaches are used to develop continuum models to evaluate water movement in a fractured rock mass. Both models provide methods for estimating rock-mass hydrologic properties. Comparisons made over a range of different tuff properties show good qualitative and quantitative agreement between estimates of rock-mass hydrologic properties made by the two models. This document presents a general discussion of: (1) the hydrology of Yucca Mountain, and the conceptual hydrological model currently being used for the Yucca Mountain site, (2) the development of two models that may be used to estimate the hydrologic properties of a fractured, porous rock mass, and (3) a comparison of the hydrologic properties estimated by these two models. Although the models were developed in response to hydrologic characterization requirements at Yucca Mountain, they can be applied to water movement in any fractured rock mass that satisfies the given assumptions

Geohydromechanical Processes in the Excavation Damaged Zone in Crystalline Rock, Rock Salt, and Indurated and Plastic Clays

International Nuclear Information System (INIS)

Tsang, Chin-Fu; Bernier, Frederic; Davies, Christophe

2004-01-01

The creation of an excavation disturbed zone or excavation damaged zone is expected around all man-made openings in geologic formations. Macro- and micro-fracturing, and in general a redistribution of in situ stresses and rearrangement of rock structures, will occur in this zone, resulting in drastic changes of permeability to flow, mainly through the fractures and cracks induced by excavation. Such an EDZ may have significant implications for the operation and long-term performance of an underground nuclear waste repository. Various issues of concern need to be evaluated, such as processes creating fractures in the excavation damaged zone, the degree of permeability increase, and the potential for sealing or healing (with permeability reduction) in the zone. In recent years, efforts along these lines have been made for a potential repository in four rock types-crystalline rock, salt, indurated clay, and plastic clay-and these efforts have involved field, laboratory, and theoretical studies. The present work involves a synthesis of the ideas and issues that emerged from presentations and discussions on EDZ in these four rock types at a CLUSTER Conference and Workshop held in Luxembourg in November, 2003. First, definitions of excavation disturbed and excavation damaged zones are proposed. Then, an approach is suggested for the synthesis and intercomparison of geohydromechanical processes in the EDZ for the four rock types (crystalline rock, salt, indurated clay, and plastic clay). Comparison tables of relevant processes, associated factors, and modeling and testing techniques are developed. A discussion of the general state-of-the-art and outstanding issues are also presented. A substantial bibliography of relevant papers on the subject is supplied at the end of the paper

Proceedings of the First International Symposium on Robust Design 2014

DEFF Research Database (Denmark)

The symposium concerns the topic of robust design from a practical and industry orientated perspective. During the 2 day symposium we will share our understanding of the need of industry with respect to the control of variance, reliability issues and approaches to robust design. The target audience...

LMI-based Gain Scheduled Robust Flux Observer for Induction Motors

DEFF Research Database (Denmark)

Trangbæk, Klaus

2000-01-01

In this paper a robust flux observer for an induction motor is developed through an LMI approach. The observer is robust to changes in rotational speed and in rotor and stator resistances. The problem is formulated as complex-valued rank constrained LMIs and solved through alternating projections...

Risk, Robustness and Water Resources Planning Under Uncertainty

Science.gov (United States)

Borgomeo, Edoardo; Mortazavi-Naeini, Mohammad; Hall, Jim W.; Guillod, Benoit P.

2018-03-01

Risk-based water resources planning is based on the premise that water managers should invest up to the point where the marginal benefit of risk reduction equals the marginal cost of achieving that benefit. However, this cost-benefit approach may not guarantee robustness under uncertain future conditions, for instance under climatic changes. In this paper, we expand risk-based decision analysis to explore possible ways of enhancing robustness in engineered water resources systems under different risk attitudes. Risk is measured as the expected annual cost of water use restrictions, while robustness is interpreted in the decision-theoretic sense as the ability of a water resource system to maintain performance—expressed as a tolerable risk of water use restrictions—under a wide range of possible future conditions. Linking risk attitudes with robustness allows stakeholders to explicitly trade-off incremental increases in robustness with investment costs for a given level of risk. We illustrate the framework through a case study of London's water supply system using state-of-the -art regional climate simulations to inform the estimation of risk and robustness.

Identification and robust control of an experimental servo motor.

Science.gov (United States)

Adam, E J; Guestrin, E D

2002-04-01

In this work, the design of a robust controller for an experimental laboratory-scale position control system based on a dc motor drive as well as the corresponding identification and robust stability analysis are presented. In order to carry out the robust design procedure, first, a classic closed-loop identification technique is applied and then, the parametrization by internal model control is used. The model uncertainty is evaluated under both parametric and global representation. For the latter case, an interesting discussion about the conservativeness of this description is presented by means of a comparison between the uncertainty disk and the critical perturbation radius approaches. Finally, conclusions about the performance of the experimental system with the robust controller are discussed using comparative graphics of the controlled variable and the Nyquist stability margin as a robustness measurement.

Rock Melt Borehole Sealing System, Final Technical Report for SBIR Phase I Grant No. DE-SC0011888

Energy Technology Data Exchange (ETDEWEB)

Osnes, John D. [RE/SPEC Inc., Argonne, IL (United States); Vining, Cody A. [RE/SPEC Inc., Argonne, IL (United States); Nopola, Jay R. [RE/SPEC Inc., Argonne, IL (United States); Roggenthen, William M. [South Dakota School of Mines & Technology, Rapid City, SD (United States)

2015-03-19

Purpose of Research Deep borehole disposal is one option that has received attention in recent years as a possible strategy for long-term disposal of the tens of thousands of tons of spent nuclear fuel. The feasibility of the deep borehole option relies upon designing and constructing an effective seal within the borehole to ensure that the waste package does not communicate with the shallow subsurface biosphere through the borehole itself. Some of the uncertainty associated with the long-term suitability of the deep borehole option is related to (1) the degradation of traditional sealing materials over time and (2) the inability of traditional sealing methods to adequately seal a Disturbed Rock Zone surrounding the borehole. One possible system to address these concerns consists of encapsulating the waste in a melt generated from either the waste itself or a plug above the waste. This current project expanded on previous work to further advance the deep borehole disposal concept. Research Objectives & Findings The overarching objective of the study was to evaluate the feasibility of constructing a downhole heater that is capable of meeting the technical and logistical requirements to melt rock. This ultimate objective was accomplished by two primary approaches. The first approach was to define the heater requirements and conceptually design a system that is capable of melting rock. The second approach was to determine the feasibility of conducting an in situ, field-scale melting experiment to validate the suitability of the rock melt seal concept. The evaluation and conceptual design of the heater system resulted in the following primary findings: • Borehole wall temperatures capable of producing a partial melt are achievable under most expected thermal conductivities with a 12-kilowatt heater. • Commercially available components have been identified that meet the requirements of the heater system, including resistive elements that are capable of providing the

Robust speaker recognition in noisy environments

CERN Document Server

Rao, K Sreenivasa

2014-01-01

This book discusses speaker recognition methods to deal with realistic variable noisy environments. The text covers authentication systems for; robust noisy background environments, functions in real time and incorporated in mobile devices. The book focuses on different approaches to enhance the accuracy of speaker recognition in presence of varying background environments. The authors examine: (a) Feature compensation using multiple background models, (b) Feature mapping using data-driven stochastic models, (c) Design of super vector- based GMM-SVM framework for robust speaker recognition, (d) Total variability modeling (i-vectors) in a discriminative framework and (e) Boosting method to fuse evidences from multiple SVM models.

Comparison of disposal concepts for rock salt and hard rock

International Nuclear Information System (INIS)

Papp, R.

1998-01-01

The study was carried out in the period 1994-1996. The goals were to prepare a draft on spent fuel disposal in hard rock and additionally a comparison with existing disposal concepts for rock salt. A cask for direct disposal of spent fuel and a repository for hard rock including a safeguards concept were conceptually designed. The results of the study confirm, that the early German decision to employ rock salt was reasonable. (orig.)

An integrated approach to single-leg airline revenue management: The role of robust optimization

NARCIS (Netherlands)

S.I. Birbil (Ilker); J.B.G. Frenk (Hans); J.A.S. Gromicho (Joaquim); S. Zhang (Shuzhong)

2006-01-01

textabstractIn this paper we introduce robust versions of the classical static and dynamic single leg seat allocation models as analyzed by Wollmer, and Lautenbacher and Stidham, respectively. These robust models take into account the inaccurate estimates of the underlying probability distributions.

An Integrated Approach to Single-Leg Airline Revenue Management: The Role of Robust Optimization

NARCIS (Netherlands)

S.I. Birbil (Ilker); J.B.G. Frenk (Hans); J.A.S. Gromicho (Joaquim); S. Zhang (Shuzhong)

2006-01-01

textabstractIn this paper we introduce robust versions of the classical static and dynamic single leg seat allocation models as analyzed by Wollmer, and Lautenbacher and Stidham, respectively. These robust models take into account the inaccurate estimates of the underlying probability distributions.

On the relation between flexibility analysis and robust optimization for linear systems

KAUST Repository

Zhang, Qi

2016-03-05

Flexibility analysis and robust optimization are two approaches to solving optimization problems under uncertainty that share some fundamental concepts, such as the use of polyhedral uncertainty sets and the worst-case approach to guarantee feasibility. The connection between these two approaches has not been sufficiently acknowledged and examined in the literature. In this context, the contributions of this work are fourfold: (1) a comparison between flexibility analysis and robust optimization from a historical perspective is presented; (2) for linear systems, new formulations for the three classical flexibility analysis problems—flexibility test, flexibility index, and design under uncertainty—based on duality theory and the affinely adjustable robust optimization (AARO) approach are proposed; (3) the AARO approach is shown to be generally more restrictive such that it may lead to overly conservative solutions; (4) numerical examples show the improved computational performance from the proposed formulations compared to the traditional flexibility analysis models. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3109–3123, 2016

A robust optimization model for distribution and evacuation in the disaster response phase

Science.gov (United States)

Fereiduni, Meysam; Shahanaghi, Kamran

2017-03-01

Natural disasters, such as earthquakes, affect thousands of people and can cause enormous financial loss. Therefore, an efficient response immediately following a natural disaster is vital to minimize the aforementioned negative effects. This research paper presents a network design model for humanitarian logistics which will assist in location and allocation decisions for multiple disaster periods. At first, a single-objective optimization model is presented that addresses the response phase of disaster management. This model will help the decision makers to make the most optimal choices in regard to location, allocation, and evacuation simultaneously. The proposed model also considers emergency tents as temporary medical centers. To cope with the uncertainty and dynamic nature of disasters, and their consequences, our multi-period robust model considers the values of critical input data in a set of various scenarios. Second, because of probable disruption in the distribution infrastructure (such as bridges), the Monte Carlo simulation is used for generating related random numbers and different scenarios; the p-robust approach is utilized to formulate the new network. The p-robust approach can predict possible damages along pathways and among relief bases. We render a case study of our robust optimization approach for Tehran's plausible earthquake in region 1. Sensitivity analysis' experiments are proposed to explore the effects of various problem parameters. These experiments will give managerial insights and can guide DMs under a variety of conditions. Then, the performances of the "robust optimization" approach and the "p-robust optimization" approach are evaluated. Intriguing results and practical insights are demonstrated by our analysis on this comparison.

Including robustness in multi-criteria optimization for intensity-modulated proton therapy

Science.gov (United States)

Chen, Wei; Unkelbach, Jan; Trofimov, Alexei; Madden, Thomas; Kooy, Hanne; Bortfeld, Thomas; Craft, David

2012-02-01

We present a method to include robustness in a multi-criteria optimization (MCO) framework for intensity-modulated proton therapy (IMPT). The approach allows one to simultaneously explore the trade-off between different objectives as well as the trade-off between robustness and nominal plan quality. In MCO, a database of plans each emphasizing different treatment planning objectives, is pre-computed to approximate the Pareto surface. An IMPT treatment plan that strikes the best balance between the different objectives can be selected by navigating on the Pareto surface. In our approach, robustness is integrated into MCO by adding robustified objectives and constraints to the MCO problem. Uncertainties (or errors) of the robust problem are modeled by pre-calculated dose-influence matrices for a nominal scenario and a number of pre-defined error scenarios (shifted patient positions, proton beam undershoot and overshoot). Objectives and constraints can be defined for the nominal scenario, thus characterizing nominal plan quality. A robustified objective represents the worst objective function value that can be realized for any of the error scenarios and thus provides a measure of plan robustness. The optimization method is based on a linear projection solver and is capable of handling large problem sizes resulting from a fine dose grid resolution, many scenarios, and a large number of proton pencil beams. A base-of-skull case is used to demonstrate the robust optimization method. It is demonstrated that the robust optimization method reduces the sensitivity of the treatment plan to setup and range errors to a degree that is not achieved by a safety margin approach. A chordoma case is analyzed in more detail to demonstrate the involved trade-offs between target underdose and brainstem sparing as well as robustness and nominal plan quality. The latter illustrates the advantage of MCO in the context of robust planning. For all cases examined, the robust optimization for

Mechanism of Rock Burst Occurrence in Specially Thick Coal Seam with Rock Parting

Science.gov (United States)

Wang, Jian-chao; Jiang, Fu-xing; Meng, Xiang-jun; Wang, Xu-you; Zhu, Si-tao; Feng, Yu

2016-05-01

Specially thick coal seam with complex construction, such as rock parting and alternative soft and hard coal, is called specially thick coal seam with rock parting (STCSRP), which easily leads to rock burst during mining. Based on the stress distribution of rock parting zone, this study investigated the mechanism, engineering discriminant conditions, prevention methods, and risk evaluation method of rock burst occurrence in STCSRP through setting up a mechanical model. The main conclusions of this study are as follows. (1) When the mining face moves closer to the rock parting zone, the original non-uniform stress of the rock parting zone and the advancing stress of the mining face are combined to intensify gradually the shearing action of coal near the mining face. When the shearing action reaches a certain degree, rock burst easily occurs near the mining face. (2) Rock burst occurrence in STCSRP is positively associated with mining depth, advancing stress concentration factor of the mining face, thickness of rock parting, bursting liability of coal, thickness ratio of rock parting to coal seam, and difference of elastic modulus between rock parting and coal, whereas negatively associated with shear strength. (3) Technologies of large-diameter drilling, coal seam water injection, and deep hole blasting can reduce advancing stress concentration factor, thickness of rock parting, and difference of elastic modulus between rock parting and coal to lower the risk of rock burst in STCSRP. (4) The research result was applied to evaluate and control the risk of rock burst occurrence in STCSRP.

Rollerjaw Rock Crusher

Science.gov (United States)

Peters, Gregory; Brown, Kyle; Fuerstenau, Stephen

2009-01-01

The rollerjaw rock crusher melds the concepts of jaw crushing and roll crushing long employed in the mining and rock-crushing industries. Rollerjaw rock crushers have been proposed for inclusion in geological exploration missions on Mars, where they would be used to pulverize rock samples into powders in the tens of micrometer particle size range required for analysis by scientific instruments.

Robust Design Optimization of an Aerospace Vehicle Prolusion System

Directory of Open Access Journals (Sweden)

Muhammad Aamir Raza

2011-01-01

Full Text Available This paper proposes a robust design optimization methodology under design uncertainties of an aerospace vehicle propulsion system. The approach consists of 3D geometric design coupled with complex internal ballistics, hybrid optimization, worst-case deviation, and efficient statistical approach. The uncertainties are propagated through worst-case deviation using first-order orthogonal design matrices. The robustness assessment is measured using the framework of mean-variance and percentile difference approach. A parametric sensitivity analysis is carried out to analyze the effects of design variables variation on performance parameters. A hybrid simulated annealing and pattern search approach is used as an optimizer. The results show the objective function of optimizing the mean performance and minimizing the variation of performance parameters in terms of thrust ratio and total impulse could be achieved while adhering to the system constraints.

Closed-Loop and Robust Control of Quantum Systems

Directory of Open Access Journals (Sweden)

Chunlin Chen

2013-01-01

Full Text Available For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA, and reinforcement learning (RL methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H∞ control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.

Closed-loop and robust control of quantum systems.

Science.gov (United States)

Chen, Chunlin; Wang, Lin-Cheng; Wang, Yuanlong

2013-01-01

For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H(∞) control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.

A robust approach to optimal matched filter design in ultrasonic non-destructive evaluation (NDE)

Science.gov (United States)

Li, Minghui; Hayward, Gordon

2017-02-01

The matched filter was demonstrated to be a powerful yet efficient technique to enhance defect detection and imaging in ultrasonic non-destructive evaluation (NDE) of coarse grain materials, provided that the filter was properly designed and optimized. In the literature, in order to accurately approximate the defect echoes, the design utilized the real excitation signals, which made it time consuming and less straightforward to implement in practice. In this paper, we present a more robust and flexible approach to optimal matched filter design using the simulated excitation signals, and the control parameters are chosen and optimized based on the real scenario of array transducer, transmitter-receiver system response, and the test sample, as a result, the filter response is optimized and depends on the material characteristics. Experiments on industrial samples are conducted and the results confirm the great benefits of the method.

A robust approach for analysing dispersion of elastic waves in an orthotropic cylindrical shell

Science.gov (United States)

Kaplunov, J.; Nobili, A.

2017-08-01

Dispersion of elastic waves in a thin orthotropic cylindrical shell is considered, within the framework of classical 2D Kirchhoff-Love theory. In contrast to direct multi-parametric analysis of the lowest propagating modes, an alternative robust approach is proposed that simply requires evaluation of the evanescent modes (quasi-static edge effect), which, at leading order, do not depend on vibration frequency. A shortened dispersion relation for the propagating modes is then derived by polynomial division and its accuracy is numerically tested against the full Kirchhoff-Love dispersion relation. It is shown that the same shortened relation may be also obtained from a refined dynamic version of the semi-membrane theory for cylindrical shells. The presented results may be relevant for modelling various types of nanotubes which, according to the latest experimental findings, possess strong material anisotropy.

Evidence of rock matrix back-diffusion and abiotic dechlorination using a field testing approach

Science.gov (United States)

Schaefer, Charles E.; Lippincott, David R.; Klammler, Harald; Hatfield, Kirk

2018-02-01

An in situ field demonstration was performed in fractured rock impacted with trichloroethene (TCE) and cis-1,2-dichloroethene (DCE) to assess the impacts of contaminant rebound after removing dissolved contaminants within hydraulically conductive fractures. Using a bedrock well pair spaced 2.4 m apart, TCE and DCE were first flushed with water to create a decrease in dissolved contaminant concentrations. While hydraulically isolating the well pair from upgradient contaminant impacts, contaminant rebound then was observed between the well pair over 151 days. The magnitude, but not trend, of TCE rebound was reasonably described by a matrix back-diffusion screening model that employed an effective diffusion coefficient and first-order abiotic TCE dechlorination rate constant that was based on bench-scale testing. Furthermore, a shift in the TCE:DCE ratio and carbon isotopic enrichment was observed during the rebound, suggesting that both biotic and abiotic dechlorination were occurring within the rock matrix. The isotopic data and back-diffusion model together served as a convincing argument that matrix back-diffusion was the mechanism responsible for the observed contaminant rebound. Results of this field demonstration highlight the importance and applicability of rock matrix parameters determined at the bench-scale, and suggest that carbon isotopic enrichment can be used as a line of evidence for abiotic dechlorination within rock matrices.

A robust multi-objective global supplier selection model under currency fluctuation and price discount

Science.gov (United States)

Zarindast, Atousa; Seyed Hosseini, Seyed Mohamad; Pishvaee, Mir Saman

2017-06-01

Robust supplier selection problem, in a scenario-based approach has been proposed, when the demand and exchange rates are subject to uncertainties. First, a deterministic multi-objective mixed integer linear programming is developed; then, the robust counterpart of the proposed mixed integer linear programming is presented using the recent extension in robust optimization theory. We discuss decision variables, respectively, by a two-stage stochastic planning model, a robust stochastic optimization planning model which integrates worst case scenario in modeling approach and finally by equivalent deterministic planning model. The experimental study is carried out to compare the performances of the three models. Robust model resulted in remarkable cost saving and it illustrated that to cope with such uncertainties, we should consider them in advance in our planning. In our case study different supplier were selected due to this uncertainties and since supplier selection is a strategic decision, it is crucial to consider these uncertainties in planning approach.

Robust mechanobiological behavior emerges in heterogeneous myosin systems

Science.gov (United States)

Egan, Paul F.; Moore, Jeffrey R.; Ehrlicher, Allen J.; Weitz, David A.; Schunn, Christian; Cagan, Jonathan; LeDuc, Philip

2017-09-01

Biological complexity presents challenges for understanding natural phenomenon and engineering new technologies, particularly in systems with molecular heterogeneity. Such complexity is present in myosin motor protein systems, and computational modeling is essential for determining how collective myosin interactions produce emergent system behavior. We develop a computational approach for altering myosin isoform parameters and their collective organization, and support predictions with in vitro experiments of motility assays with α-actinins as molecular force sensors. The computational approach models variations in single myosin molecular structure, system organization, and force stimuli to predict system behavior for filament velocity, energy consumption, and robustness. Robustness is the range of forces where a filament is expected to have continuous velocity and depends on used myosin system energy. Myosin systems are shown to have highly nonlinear behavior across force conditions that may be exploited at a systems level by combining slow and fast myosin isoforms heterogeneously. Results suggest some heterogeneous systems have lower energy use near stall conditions and greater energy consumption when unloaded, therefore promoting robustness. These heterogeneous system capabilities are unique in comparison with homogenous systems and potentially advantageous for high performance bionanotechnologies. Findings open doors at the intersections of mechanics and biology, particularly for understanding and treating myosin-related diseases and developing approaches for motor molecule-based technologies.

Water infiltration into exposed fractured rock surfaces

International Nuclear Information System (INIS)

Rasmussen, T.C.; Evans, D.D.

1993-01-01

Fractured rock media are present at many existing and potential waste disposal sites, yet characterization data and physical relationships are not well developed for such media. This study focused on water infiltration characteristics of an exposed fractured rock as an approach for defining the upper boundary condition for unsaturated-zone water percolation and contaminant transport modeling. Two adjacent watersheds of 0.24 and 1.73 ha with slopes up to 45% were instrumented for measuring rainfall and runoff. Fracture density was measured from readily observable fracture traces on the surface. Three methods were employed to evaluate the rainfall-runoff relationship. The first method used the annual totals and indicated that only 22.5% of rainfall occurred as runoff for the 1990-1991 water year, which demonstrates a high water intake rate by the exposed fracture system. The second method employed total rainfall and runoff for individual storms in conjunction with the commonly used USDA Soil Conservation Service curve number method developed for wide ranges of soils and vegetation. Curve numbers between 75 and 85 were observed for summer and winter storms with dry antecedent runoff conditions, while values exceeded 90 for wet conditions. The third method used a mass-balance approach for four major storms, which indicated that water intake rates ranged from 2.0 to 7.3 mm h -1 , yielding fracture intake velocities ranging from 122 to 293 m h -1 . The three analyses show the complexity of the infiltration process for fractured rock. However, they contribute to a better understanding of the upper boundary condition for predicting contaminant transport through an unsaturated fractured rock medium. 17 refs., 4 figs., 1 tab

Robust Control of a Hydraulically Actuated Manipulator Using Sliding Mode Control

DEFF Research Database (Denmark)

Hansen, Michael Rygaard; Andersen, Torben Ole; Pedersen, Henrik Clemmensen

2005-01-01

This paper presents an approach to robust control called sliding mode control (SMC) applied to the a hydraulic servo system (HSS), consisting of a servo valve controlled symmetrical cylinder. The motivation for applying sliding mode control to hydraulically actuated systems is its robustness...

Study on the Optimal Equivalent Radius in Calculating the Heat Dissipation of Surrounding Rock

Directory of Open Access Journals (Sweden)

H. T. Song

2015-11-01

Full Text Available The heat dissipation of surrounding rock of a non-circular roadway is computed using an equivalent circular roadway approach under three circumstances when the area, perimeter, or hydraulic diameter of the circular roadway is equal to the non-circular roadway to obtain the optimal equivalent radius. The differential equations of heat conduction for unstable surrounding rock are established in cylindrical and rectangular coordinate systems using dimensionless analysis method. The calculation formulas of heat dissipation capacity and heat transfer resistance are derived from differential equations. Based on the method of equivalent radius, the similarities and differences between non-circular and circular roadways in calculating the heat dissipation of surrounding rock are discussed. Using the finite volume method, the calculation models for non-circular and circular roadways in the heat dissipation of surrounding rock are also established, among the non-circular roadways including three circumstances, namely, trapezoid, rectangle, and arch. The relation errors of heat dissipation of the surrounding rock of the three equivalent circular roadway methods are investigated for the three non-circular roadways. Results show that the calculation approach with equal perimeters is the best for the heat dissipation of surrounding rock of non-circular roadways.

O rock desligado de Lóki

Directory of Open Access Journals (Sweden)

Márcia Carvalho

2012-08-01

Full Text Available This paper presents an analysis of the documentary Loki: ArnaldoBaptista (2009, direct by Paulo Henrique Fontenelle. This analysis investigates thehistorical research and biographical approach, examining in particular the enhancement oforal memory and musical performances from different sources to put into perspective thehistory of Brazilian rock on movie screens and television.

Robust power spectral estimation for EEG data.

Science.gov (United States)

Melman, Tamar; Victor, Jonathan D

2016-08-01

Typical electroencephalogram (EEG) recordings often contain substantial artifact. These artifacts, often large and intermittent, can interfere with quantification of the EEG via its power spectrum. To reduce the impact of artifact, EEG records are typically cleaned by a preprocessing stage that removes individual segments or components of the recording. However, such preprocessing can introduce bias, discard available signal, and be labor-intensive. With this motivation, we present a method that uses robust statistics to reduce dependence on preprocessing by minimizing the effect of large intermittent outliers on the spectral estimates. Using the multitaper method (Thomson, 1982) as a starting point, we replaced the final step of the standard power spectrum calculation with a quantile-based estimator, and the Jackknife approach to confidence intervals with a Bayesian approach. The method is implemented in provided MATLAB modules, which extend the widely used Chronux toolbox. Using both simulated and human data, we show that in the presence of large intermittent outliers, the robust method produces improved estimates of the power spectrum, and that the Bayesian confidence intervals yield close-to-veridical coverage factors. The robust method, as compared to the standard method, is less affected by artifact: inclusion of outliers produces fewer changes in the shape of the power spectrum as well as in the coverage factor. In the presence of large intermittent outliers, the robust method can reduce dependence on data preprocessing as compared to standard methods of spectral estimation. Copyright © 2016 Elsevier B.V. All rights reserved.

Finite Algorithms for Robust Linear Regression

DEFF Research Database (Denmark)

Madsen, Kaj; Nielsen, Hans Bruun

1990-01-01

The Huber M-estimator for robust linear regression is analyzed. Newton type methods for solution of the problem are defined and analyzed, and finite convergence is proved. Numerical experiments with a large number of test problems demonstrate efficiency and indicate that this kind of approach may...

Emergence of robustness in networks of networks

Science.gov (United States)

Roth, Kevin; Morone, Flaviano; Min, Byungjoon; Makse, Hernán A.

2017-06-01

A model of interdependent networks of networks (NONs) was introduced recently [Proc. Natl. Acad. Sci. (USA) 114, 3849 (2017), 10.1073/pnas.1620808114] in the context of brain activation to identify the neural collective influencers in the brain NON. Here we investigate the emergence of robustness in such a model, and we develop an approach to derive an exact expression for the random percolation transition in Erdös-Rényi NONs of this kind. Analytical calculations are in agreement with numerical simulations, and highlight the robustness of the NON against random node failures, which thus presents a new robust universality class of NONs. The key aspect of this robust NON model is that a node can be activated even if it does not belong to the giant mutually connected component, thus allowing the NON to be built from below the percolation threshold, which is not possible in previous models of interdependent networks. Interestingly, the phase diagram of the model unveils particular patterns of interconnectivity for which the NON is most vulnerable, thereby marking the boundary above which the robustness of the system improves with increasing dependency connections.

Service Quality Robust Design by the Integration of Taguchi Experiments and SERVQUAL Approach in a Travel Agency

Directory of Open Access Journals (Sweden)

nassibeh janatyan

2012-02-01

Full Text Available The main purpose of this research is to address how robust design of service quality dimensions can be obtained. Service Quality Robust Design has been conducted by the integration of Taguchi Design of Experiments and SERVQUAL approach in Iran Travel Agency. Five basic dimensions of service quality, i.e. reliability, responsiveness, assurance, empathy, tangibles and price have been assumed as control factors. Response factor has been defined as two alternatives i the sum of customer expectations, and ii the sum of service quality gaps. In this investigation assumed that noise factor is not existed. The advantage of this paper is to improve the average and standard deviation simultaneously. Signal to noise ratio has been computed and the desired mix of the levels of service quality dimensions has been addressed. The main findings of this research includes the desired mix of the levels of service quality dimensions based on the sum of customer expectations and the desired mix of the levels of service quality dimensions based on the sum of service quality gaps. Comparing the two sets of findings helps the agency to analyze the cost of attracting new customers or retaining regular customers.

Fluid and rock interaction in permeable volcanic rock

International Nuclear Information System (INIS)

Lindley, J.I.

1985-01-01

Four types of interrelated changes -geochemical, mineralogic, isotopic, and physical - occur in Oligocene volcanic units of the Mogollon-Datil volcanic field, New Mexico. These changes resulted from the operation of a geothermal system that, through fluid-rock interaction, affected 5 rhyolite ash-flow tuffs and an intercalated basaltic andesite lava flow causing a potassium metasomatism type of alteration. (1) Previous studies have shown enrichment of rocks in K 2 O as much as 130% of their original values at the expense of Na 2 O and CaO with an accompanying increase in Rb and decreases in MgO and Sr. (2) X-ray diffraction results of this study show that phenocrystic plagioclase and groundmass feldspar have been replaced with pure potassium feldspar and quartz in altered rock. Phenocrystic potassium feldspar, biotite, and quartz are unaffected. Pyroxene in basaltic andesite is replaced by iron oxide. (3) delta 18 O increases for rhyolitic units from values of 8-10 permil, typical of unaltered rock, to 13-15 permil, typical of altered rock. Basaltic andesite, however, shows opposite behavior with a delta 18 of 9 permil in unaltered rock and 6 permit in altered. (4) Alteration results in a density decrease. SEM revealed that replacement of plagioclase by fine-grained quartz and potassium feldspar is not a volume for volume replacement. Secondary porosity is created in the volcanics by the chaotic arrangement of secondary crystals

Historical rock falls in Yosemite National Park, California (1857-2011)

Science.gov (United States)

Stock, Greg M.; Collins, Brian D.; Santaniello, David J.; Zimmer, Valerie L.; Wieczorek, Gerald F.; Snyder, James B.

2013-01-01

Inventories of rock falls and other types of landslides are valuable tools for improving understanding of these events. For example, detailed information on rock falls is critical for identifying mechanisms that trigger rock falls, for quantifying the susceptibility of different cliffs to rock falls, and for developing magnitude-frequency relations. Further, inventories can assist in quantifying the relative hazard and risk posed by these events over both short and long time scales. This report describes and presents the accompanying rock fall inventory database for Yosemite National Park, California. The inventory database documents 925 events spanning the period 1857–2011. Rock falls, rock slides, and other forms of slope movement represent a serious natural hazard in Yosemite National Park. Rock-fall hazard and risk are particularly relevant in Yosemite Valley, where glacially steepened granitic cliffs approach 1 km in height and where the majority of the approximately 4 million yearly visitors to the park congregate. In addition to damaging roads, trails, and other facilities, rock falls and other slope movement events have killed 15 people and injured at least 85 people in the park since the first documented rock fall in 1857. The accompanying report describes each of the organizational categories in the database, including event location, type of slope movement, date, volume, relative size, probable trigger, impact to humans, narrative description, references, and environmental conditions. The inventory database itself is contained in a Microsoft Excel spreadsheet (Yosemite_rock_fall_database_1857-2011.xlsx). Narrative descriptions of events are contained in the database, but are also provided in a more readable Adobe portable document format (pdf) file (Yosemite_rock_fall_database_narratives_1857-2011.pdf) available for download separate from the database.

Measure of robustness for complex networks

Science.gov (United States)

Youssef, Mina Nabil

Critical infrastructures are repeatedly attacked by external triggers causing tremendous amount of damages. Any infrastructure can be studied using the powerful theory of complex networks. A complex network is composed of extremely large number of different elements that exchange commodities providing significant services. The main functions of complex networks can be damaged by different types of attacks and failures that degrade the network performance. These attacks and failures are considered as disturbing dynamics, such as the spread of viruses in computer networks, the spread of epidemics in social networks, and the cascading failures in power grids. Depending on the network structure and the attack strength, every network differently suffers damages and performance degradation. Hence, quantifying the robustness of complex networks becomes an essential task. In this dissertation, new metrics are introduced to measure the robustness of technological and social networks with respect to the spread of epidemics, and the robustness of power grids with respect to cascading failures. First, we introduce a new metric called the Viral Conductance (VCSIS ) to assess the robustness of networks with respect to the spread of epidemics that are modeled through the susceptible/infected/susceptible (SIS) epidemic approach. In contrast to assessing the robustness of networks based on a classical metric, the epidemic threshold, the new metric integrates the fraction of infected nodes at steady state for all possible effective infection strengths. Through examples, VCSIS provides more insights about the robustness of networks than the epidemic threshold. In addition, both the paradoxical robustness of Barabasi-Albert preferential attachment networks and the effect of the topology on the steady state infection are studied, to show the importance of quantifying the robustness of networks. Second, a new metric VCSIR is introduced to assess the robustness of networks with respect

Robust output observer-based control of neutral uncertain systems with discrete and distributed time delays: LMI optimization approach

International Nuclear Information System (INIS)

Chen, J.-D.

2007-01-01

In this paper, the robust control problem of output dynamic observer-based control for a class of uncertain neutral systems with discrete and distributed time delays is considered. Linear matrix inequality (LMI) optimization approach is used to design the new output dynamic observer-based controls. Three classes of observer-based controls are proposed and the maximal perturbed bound is given. Based on the results of this paper, the constraint of matrix equality is not necessary for designing the observer-based controls. Finally, a numerical example is given to illustrate the usefulness of the proposed method

Robust small area estimation of poverty indicators using M-quantile approach (Case study: Sub-district level in Bogor district)

Science.gov (United States)

Girinoto, Sadik, Kusman; Indahwati

2017-03-01

The National Socio-Economic Survey samples are designed to produce estimates of parameters of planned domains (provinces and districts). The estimation of unplanned domains (sub-districts and villages) has its limitation to obtain reliable direct estimates. One of the possible solutions to overcome this problem is employing small area estimation techniques. The popular choice of small area estimation is based on linear mixed models. However, such models need strong distributional assumptions and do not easy allow for outlier-robust estimation. As an alternative approach for this purpose, M-quantile regression approach to small area estimation based on modeling specific M-quantile coefficients of conditional distribution of study variable given auxiliary covariates. It obtained outlier-robust estimation from influence function of M-estimator type and also no need strong distributional assumptions. In this paper, the aim of study is to estimate the poverty indicator at sub-district level in Bogor District-West Java using M-quantile models for small area estimation. Using data taken from National Socioeconomic Survey and Villages Potential Statistics, the results provide a detailed description of pattern of incidence and intensity of poverty within Bogor district. We also compare the results with direct estimates. The results showed the framework may be preferable when direct estimate having no incidence of poverty at all in the small area.

A Unifying Mathematical Framework for Genetic Robustness, Environmental Robustness, Network Robustness and their Trade-offs on Phenotype Robustness in Biological Networks. Part III: Synthetic Gene Networks in Synthetic Biology

Science.gov (United States)

Chen, Bor-Sen; Lin, Ying-Po

2013-01-01

Robust stabilization and environmental disturbance attenuation are ubiquitous systematic properties that are observed in biological systems at many different levels. The underlying principles for robust stabilization and environmental disturbance attenuation are universal to both complex biological systems and sophisticated engineering systems. In many biological networks, network robustness should be large enough to confer: intrinsic robustness for tolerating intrinsic parameter fluctuations; genetic robustness for buffering genetic variations; and environmental robustness for resisting environmental disturbances. Network robustness is needed so phenotype stability of biological network can be maintained, guaranteeing phenotype robustness. Synthetic biology is foreseen to have important applications in biotechnology and medicine; it is expected to contribute significantly to a better understanding of functioning of complex biological systems. This paper presents a unifying mathematical framework for investigating the principles of both robust stabilization and environmental disturbance attenuation for synthetic gene networks in synthetic biology. Further, from the unifying mathematical framework, we found that the phenotype robustness criterion for synthetic gene networks is the following: if intrinsic robustness + genetic robustness + environmental robustness ≦ network robustness, then the phenotype robustness can be maintained in spite of intrinsic parameter fluctuations, genetic variations, and environmental disturbances. Therefore, the trade-offs between intrinsic robustness, genetic robustness, environmental robustness, and network robustness in synthetic biology can also be investigated through corresponding phenotype robustness criteria from the systematic point of view. Finally, a robust synthetic design that involves network evolution algorithms with desired behavior under intrinsic parameter fluctuations, genetic variations, and environmental

CAPILLARY BARRIERS IN UNSATURATED FRACTURED ROCKS OF YUCCA MOUNTAIN, NEVADA

International Nuclear Information System (INIS)

Wu, Y.S.; Zhang, W.; Pan, L.; Hinds, J.; Bodvarsson, G.

2000-01-01

This work presents modeling studies investigating the effects of capillary barriers on fluid-flow and tracer-transport processes in the unsaturated zone of Yucca Mountain, Nevada, a potential site for storing high-level radioactive waste. These studies are designed to identify factors controlling the formation of capillary barriers and to estimate their effects on the extent of possible large-scale lateral flow in unsaturated fracture rocks. The modeling approach is based on a continuum formulation of coupled multiphase fluid and tracer transport through fractured porous rock. Flow processes in fractured porous rock are described using a dual-continuum concept. In addition, approximate analytical solutions are developed and used for assessing capillary-barrier effects in fractured rocks. This study indicates that under the current hydrogeologic conceptualization of Yucca Mountain, strong capillary-barrier effects exist for significantly diverting moisture flow

A robust data-driven approach for gene ontology annotation.

Science.gov (United States)

Li, Yanpeng; Yu, Hong

2014-01-01

Gene ontology (GO) and GO annotation are important resources for biological information management and knowledge discovery, but the speed of manual annotation became a major bottleneck of database curation. BioCreative IV GO annotation task aims to evaluate the performance of system that automatically assigns GO terms to genes based on the narrative sentences in biomedical literature. This article presents our work in this task as well as the experimental results after the competition. For the evidence sentence extraction subtask, we built a binary classifier to identify evidence sentences using reference distance estimator (RDE), a recently proposed semi-supervised learning method that learns new features from around 10 million unlabeled sentences, achieving an F1 of 19.3% in exact match and 32.5% in relaxed match. In the post-submission experiment, we obtained 22.1% and 35.7% F1 performance by incorporating bigram features in RDE learning. In both development and test sets, RDE-based method achieved over 20% relative improvement on F1 and AUC performance against classical supervised learning methods, e.g. support vector machine and logistic regression. For the GO term prediction subtask, we developed an information retrieval-based method to retrieve the GO term most relevant to each evidence sentence using a ranking function that combined cosine similarity and the frequency of GO terms in documents, and a filtering method based on high-level GO classes. The best performance of our submitted runs was 7.8% F1 and 22.2% hierarchy F1. We found that the incorporation of frequency information and hierarchy filtering substantially improved the performance. In the post-submission evaluation, we obtained a 10.6% F1 using a simpler setting. Overall, the experimental analysis showed our approaches were robust in both the two tasks. © The Author(s) 2014. Published by Oxford University Press.

A robust ligand exchange approach for preparing hydrophilic, biocompatible photoluminescent quantum dots

Energy Technology Data Exchange (ETDEWEB)

Wang, Sujuan; Zhou, Changhua [Key Laboratory for Special Functional Materials of the Ministry of Education, Henan University, Kaifeng 475004 (China); Yuan, Hang [Life Science Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Shen, Huaibin [Key Laboratory for Special Functional Materials of the Ministry of Education, Henan University, Kaifeng 475004 (China); Zhao, Wenxiu [Life Science Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Ma, Lan, E-mail: malan@sz.tsinghua.edu.cn [Life Science Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Li, Lin Song, E-mail: lsli@henu.edu.cn [Key Laboratory for Special Functional Materials of the Ministry of Education, Henan University, Kaifeng 475004 (China)

2013-08-01

Graphical abstract: - Highlights: • Aqueous CdSe/ZnS QDs were prepared using polymaleic anhydrides as capping ligand. • Effect of reaction temperature and time were systematically studied in the synthesis process. • Water-soluble QDs exhibited a good stability in physiological relevant environment. • The aqueous QDs were applied as biological probe to detect human embryonic stem cell. - Abstract: This paper describes a robust ligand exchange approach for preparing biocompatible CdSe/ZnS quantum dots (QDs) to make bioprobe for effective cell imaging. In this method, polymaleic anhydride (PMA) ligand are first used to replace original hydrophobic ligand (oleic acid) and form a protection shell with multiple hydrophilic groups to coat and protect CdSe/ZnS QDs. The as-prepared aqueous QDs exhibit small particle size, good colloidal stability in aqueous solutions with a wide range of pH, salt concentrations and under thermal treatment, which are necessary for biological applications. The use of this new class of aqueous QDs for effective cell imaging shows strong fluorescence signal to human embryonic stem cell, which demonstrate that PMA coated QDs are fully satisfied with the requirements of preparing high quality biological probe.

Disc cutter wear and rock texture in hard rock TBM tunneling

International Nuclear Information System (INIS)

Koizumi, Yu; Tsusaka, Kimikazu; Tanimoto, Chikaosa; Nakagawa, Shigeo; Fujita, Naoya

2008-01-01

Disc cutter wear in TBM tunneling is caused by initial fragmentation of a solid rock face (the primary fragmentation) and fragmentation of residual rock pieces between a cutterhead and the face (the secondary fragmentation). In two projects through sedimentary and granitic rocks, the authors investigated the relationships between the rate of cutter wear caused by the primary fragmentation, point load index and the grain size and contents of abrasive minerals. As a result, it was found that the tensile strength and the mineral contents of rocks significantly influenced the cutter wear in both projects and thus it is necessary to take into account of rock type. (author)

Rocks Can Wow? Yes, Rocks Can Wow!

Science.gov (United States)

Hardman, Sally; Luke, Sue

2016-01-01

Rocks and fossils appear in the National Curriculum of England science programmes of study for children in year 3 (ages 7-8). A frequently asked question is "How do you make the classification of rocks engaging?" In response to this request from a school, a set of interactive activities was designed and organised by tutors and students…

Dynamic response of tunnels in jointed rocks

International Nuclear Information System (INIS)

Heuze, F.E.; Shaffer, R.J.; Walton, O.R.; Maddix, D.M.

1992-03-01

We describe the application of the Discrete Element Method (DEM) to the dynamic analysis of the response of tunnels in jointed rocks to earthquake loading. In situations where large motions of many blocks and collapse occur, the discontinuum-based DEM approach appears superior to other methods of analysis

Design and Validation of Optimized Feedforward with Robust Feedback Control of a Nuclear Reactor

International Nuclear Information System (INIS)

Shaffer, Roman; He Weidong; Edwards, Robert M.

2004-01-01

Design applications for robust feedback and optimized feedforward control, with confirming results from experiments conducted on the Pennsylvania State University TRIGA reactor, are presented. The combination of feedforward and feedback control techniques complement each other in that robust control offers guaranteed closed-loop stability in the presence of uncertainties, and optimized feedforward offers an approach to achieving performance that is sometimes limited by overly conservative robust feedback control. The design approach taken in this work combines these techniques by first designing robust feedback control. Alternative methods for specifying a low-order linear model and uncertainty specifications, while seeking as much performance as possible, are discussed and evaluated. To achieve desired performance characteristics, the optimized feedforward control is then computed by using the nominal nonlinear plant model that incorporates the robust feedback control

Real-time PCR Machine System Modeling and a Systematic Approach for the Robust Design of a Real-time PCR-on-a-Chip System

Directory of Open Access Journals (Sweden)

Da-Sheng Lee

2010-01-01

Full Text Available Chip-based DNA quantification systems are widespread, and used in many point-of-care applications. However, instruments for such applications may not be maintained or calibrated regularly. Since machine reliability is a key issue for normal operation, this study presents a system model of the real-time Polymerase Chain Reaction (PCR machine to analyze the instrument design through numerical experiments. Based on model analysis, a systematic approach was developed to lower the variation of DNA quantification and achieve a robust design for a real-time PCR-on-a-chip system. Accelerated lift testing was adopted to evaluate the reliability of the chip prototype. According to the life test plan, this proposed real-time PCR-on-a-chip system was simulated to work continuously for over three years with similar reproducibility in DNA quantification. This not only shows the robustness of the lab-on-a-chip system, but also verifies the effectiveness of our systematic method for achieving a robust design.

Robust hopping based on virtual pendulum posture control

International Nuclear Information System (INIS)

Sharbafi, Maziar A; Ahmadabadi, Majid Nili; Yazdanpanah, Mohammad J; Maufroy, Christophe; Seyfarth, Andre

2013-01-01

A new control approach to achieve robust hopping against perturbations in the sagittal plane is presented in this paper. In perturbed hopping, vertical body alignment has a significant role for stability. Our approach is based on the virtual pendulum concept, recently proposed, based on experimental findings in human and animal locomotion. In this concept, the ground reaction forces are pointed to a virtual support point, named virtual pivot point (VPP), during motion. This concept is employed in designing the controller to balance the trunk during the stance phase. New strategies for leg angle and length adjustment besides the virtual pendulum posture control are proposed as a unified controller. This method is investigated by applying it on an extension of the spring loaded inverted pendulum (SLIP) model. Trunk, leg mass and damping are added to the SLIP model in order to make the model more realistic. The stability is analyzed by Poincaré map analysis. With fixed VPP position, stability, disturbance rejection and moderate robustness are achieved, but with a low convergence speed. To improve the performance and attain higher robustness, an event-based control of the VPP position is introduced, using feedback of the system states at apexes. Discrete linear quartic regulator is used to design the feedback controller. Considerable enhancements with respect to stability, convergence speed and robustness against perturbations and parameter changes are achieved. (paper)

Towards a comprehensive classification of igneous rocks and magmas

Science.gov (United States)

Middlemost, Eric A. K.

1991-08-01

The IUGS Subcommission on the Systematics of Igneous Rocks has recently published an excellent book on the classification of these rocks. This event has shifted the vexed question of classification towards the top of the agenda in igneous petrology. Over the years the Subcommission has used many different criteria to establish the positions of the boundaries between the various common igneous rocks. It now has to adopt a holistic approach and develop a comprehensive, coherent classification that is purged of all the minor anomalies that arise between the various classifications that it has approved. It is appreciated that the Subcommission's classification was never intended to have any genetic implications; however, it is suggested that an ideal classification should he presented in such a way that it is able to group rocks into an order that directs attention to petrogenetic relationships between individual rocks and larger groups of rocks. Unfortunately, many of the Subcommission's definitions are Earth chauvinistic; for example, igneous rocks are defined as being those rocks that solidified from a molten state either within or on the surface of the Earth. Nowhere in the book is it acknowledged that during the past 20 years, while the Subcommission has been framing its many recommendations, a whole new science of planetary petrology has subsumed classical petrology. In any new edition of the book, the Subcommission should acknowledge that rocks are essentially the solid materials of which planets, natural satellites and other broadly similar cosmic bodies are made. The Subcommission should also explicitly recognise that igneous rocks can be divided into either a main sequence of essentially common rocks or a number of supplementary clans of special rocks that evolved outside the main sequence. It is hoped that in the near future the Subcommission will rescind its recommendation that the TAS classification should be regarded as an adjunct to its more traditional

Graphical evaluation of the ridge-type robust regression estimators in mixture experiments.

Science.gov (United States)

Erkoc, Ali; Emiroglu, Esra; Akay, Kadri Ulas

2014-01-01

In mixture experiments, estimation of the parameters is generally based on ordinary least squares (OLS). However, in the presence of multicollinearity and outliers, OLS can result in very poor estimates. In this case, effects due to the combined outlier-multicollinearity problem can be reduced to certain extent by using alternative approaches. One of these approaches is to use biased-robust regression techniques for the estimation of parameters. In this paper, we evaluate various ridge-type robust estimators in the cases where there are multicollinearity and outliers during the analysis of mixture experiments. Also, for selection of biasing parameter, we use fraction of design space plots for evaluating the effect of the ridge-type robust estimators with respect to the scaled mean squared error of prediction. The suggested graphical approach is illustrated on Hald cement data set.

An Intercompany Perspective on Biopharmaceutical Drug Product Robustness Studies.

Science.gov (United States)

Morar-Mitrica, Sorina; Adams, Monica L; Crotts, George; Wurth, Christine; Ihnat, Peter M; Tabish, Tanvir; Antochshuk, Valentyn; DiLuzio, Willow; Dix, Daniel B; Fernandez, Jason E; Gupta, Kapil; Fleming, Michael S; He, Bing; Kranz, James K; Liu, Dingjiang; Narasimhan, Chakravarthy; Routhier, Eric; Taylor, Katherine D; Truong, Nobel; Stokes, Elaine S E

2018-02-01

The Biophorum Development Group (BPDG) is an industry-wide consortium enabling networking and sharing of best practices for the development of biopharmaceuticals. To gain a better understanding of current industry approaches for establishing biopharmaceutical drug product (DP) robustness, the BPDG-Formulation Point Share group conducted an intercompany collaboration exercise, which included a bench-marking survey and extensive group discussions around the scope, design, and execution of robustness studies. The results of this industry collaboration revealed several key common themes: (1) overall DP robustness is defined by both the formulation and the manufacturing process robustness; (2) robustness integrates the principles of quality by design (QbD); (3) DP robustness is an important factor in setting critical quality attribute control strategies and commercial specifications; (4) most companies employ robustness studies, along with prior knowledge, risk assessments, and statistics, to develop the DP design space; (5) studies are tailored to commercial development needs and the practices of each company. Three case studies further illustrate how a robustness study design for a biopharmaceutical DP balances experimental complexity, statistical power, scientific understanding, and risk assessment to provide the desired product and process knowledge. The BPDG-Formulation Point Share discusses identified industry challenges with regard to biopharmaceutical DP robustness and presents some recommendations for best practices. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Rock slope instabilities in Norway: First systematic hazard and risk classification of 22 unstable rock slopes

Science.gov (United States)

Böhme, Martina; Hermanns, Reginald L.; Oppikofer, Thierry; Penna, Ivanna

2016-04-01

Unstable rock slopes that can cause large failures of the rock-avalanche type have been mapped in Norway for almost two decades. Four sites have earlier been characterized as high-risk objects based on expertise of few researchers. This resulted in installing continuous monitoring systems and set-up of an early-warning system for those four sites. Other unstable rock slopes have not been ranked related to their hazard or risk. There are ca. 300 other sites known of which 70 sites were installed for periodic deformation measurements using multiple techniques (Global Navigation Satellite Systems, extensometers, measurement bolts, and others). In 2012 a systematic hazard and risk classification system for unstable rock slopes was established in Norway and the mapping approach adapted to that in 2013. Now, the first 22 sites were classified for hazard, consequences and risk using this classification system. The selection of the first group of sites to be classified was based on an assumed high hazard or risk and importance given to the sites by Norwegian media and the public. Nine of the classified 22 unstable rock slopes are large sites that deform inhomogeneously or are strongly broken up in individual blocks. This suggests that different failure scenarios are possible that need to be analyzed individually. A total of 35 failure scenarios for those nine unstable rock slopes were considered. The hazard analyses were based on 9 geological parameters defined in the classification system. The classification system will be presented based on the Gamanjunni unstable rock slope. This slope has a well developed back scarp that exposes 150 m preceding displacement. The lateral limits of the unstable slope are clearly visible in the morphology and InSAR displacement data. There have been no single structures observed that allow sliding kinematically. The lower extend of the displacing rock mass is clearly defined in InSAR data and by a zone of higher rock fall activity. Yearly

Rock Physics

DEFF Research Database (Denmark)

Fabricius, Ida Lykke

2017-01-01

Rock physics is the discipline linking petrophysical properties as derived from borehole data to surface based geophysical exploration data. It can involve interpretation of both elastic wave propagation and electrical conductivity, but in this chapter focus is on elasticity. Rock physics is based...... on continuum mechanics, and the theory of elasticity developed for statics becomes the key to petrophysical interpretation of velocity of elastic waves. In practice, rock physics involves interpretation of well logs including vertical seismic profiling (VSP) and analysis of core samples. The results...

Mineral and rock chemistry of Mata da Corda Kamafugitic Rocks (Minas Gerais State, Brazil)

International Nuclear Information System (INIS)

Albuquerque Sgarbi, Patricia B. de; Valenca, Joel G.

1995-01-01

The volcanic rocks of the Mata da Corda Formation (Upper Cretaceous) in Minas Gerais, Brazil, are mafic potassic to ultra potassic rocks of kamafugitic affinity containing essentially clinopyroxenes, perovskite, magnetite and occasionally olivine, phlogopite, melilite pseudomorphs and apatite. The felsic phases are kalsilite and/or leucite pseudomorphs. The rocks are classified as mafitites, leucitites and kalsilitites. The analysis of the available data of the rocks studied, based on the relevant aspects of the main proposals for the classification of alkaline mafic to ultramafic potassic rocks leads to the conclusion that Sahama's (1974) proposal to divide potassium rich alkaline rocks in two large families is the one to which the Mata da Corda rocks adapt best. According to this and the data in the literature on the mineralogy and mineral and rock chemistries of the other similar occurrences, these rocks may be interpreted as alkaline potassic to ultra potassic rocks of hamafugitic affinity. 11 figs., 5 tabs

On the Interplay between the Evolvability and Network Robustness in an Evolutionary Biological Network: A Systems Biology Approach

Science.gov (United States)

Chen, Bor-Sen; Lin, Ying-Po

2011-01-01

In the evolutionary process, the random transmission and mutation of genes provide biological diversities for natural selection. In order to preserve functional phenotypes between generations, gene networks need to evolve robustly under the influence of random perturbations. Therefore, the robustness of the phenotype, in the evolutionary process, exerts a selection force on gene networks to keep network functions. However, gene networks need to adjust, by variations in genetic content, to generate phenotypes for new challenges in the network’s evolution, ie, the evolvability. Hence, there should be some interplay between the evolvability and network robustness in evolutionary gene networks. In this study, the interplay between the evolvability and network robustness of a gene network and a biochemical network is discussed from a nonlinear stochastic system point of view. It was found that if the genetic robustness plus environmental robustness is less than the network robustness, the phenotype of the biological network is robust in evolution. The tradeoff between the genetic robustness and environmental robustness in evolution is discussed from the stochastic stability robustness and sensitivity of the nonlinear stochastic biological network, which may be relevant to the statistical tradeoff between bias and variance, the so-called bias/variance dilemma. Further, the tradeoff could be considered as an antagonistic pleiotropic action of a gene network and discussed from the systems biology perspective. PMID:22084563

Hydraulic gradients in rock aquifers

International Nuclear Information System (INIS)

Dahlblom, P.

1992-05-01

This report deals with fractured rock as a host for deposits of hazardous waste. In this context the rock, with its fractures containing moving groundwater, is called the geological barrier. The desired properties of the geological barrier are low permeability to water, low hydraulic gradients and ability to retain matter dissolved in the water. The hydraulic gradient together with the permeability and the porosity determines the migration velocity. Mathematical modelling of the migration involves calculation of the water flow and the hydrodynamic dispersion of the contaminant. The porous medium approach can be used to calculate mean flow velocities and hydrodynamic dispersion of a large number of fractures are connected, which means that a large volume have to be considered. It is assumed that the porous medium approach can be applied, and a number of idealized examples are shown. It is assumed that the groundwater table is replenished by percolation at a constant rate. One-dimensional analytical calculations show that zero hydraulic gradients may exist at relatively large distance from the coast. Two-dimensional numerical calculations show that it may be possible to find areas with low hydraulic gradients and flow velocities within blocks surrounded by areas with high hydraulic conductivity. (au)

Petrophysics at the rock matrix scale: hydraulic properties and petrographic interpretation

International Nuclear Information System (INIS)

Montoto, M.

2003-01-01

The main objective of this publication is to review, summarize and make comprehensive the hydraulic properties of rocks, at the rock matrix or in tact rock scale. Also to describe how to petrographically interpret those properties. For this purpose, the procedures for the characterization and visualisation of the rock-forming components and in special the water path-ways at that scale are explained. Further more, to establish a methodological approach for an appropriate petrographic interpretation of all the mentioned properties is intended. This Technical Report is applied to the geological solution for the final disposal of high level radioactive wastes. In any case, most of the aspects covered here are of scientific and technical interest for any researcher interested in the behaviour of water in rocks and vice versa, also in the potential fluid- rock interactions. The document is divided into six Chapters, mainly theoretical and methodological, and six Appen - dixes, more focussed to practical tests and procedures for rock characterization. Two significant rock types in high level radioactive waste, HLW, granites and clays, have been used for illustrating most of the examples here included. Under a wide geological perspective, it must be stated that in any geological scenario two different systems or scales coexist; the rock massif (with fractures of about m to km) and the rock matrix (with internal discontinuities such as fissures and cracks to the order of Fm to dm). Their different behaviour is considered in Chapter 1 as well as the specific role played by the rock matrix in the long- and short-term period. General considerations about physical properties of rocks and comparative advantages and disadvantages of the main candidate rocks for radioactive repositories are also included. (Author)

Modelling of the Elasticity Modulus for Rock Using Genetic Expression Programming

Directory of Open Access Journals (Sweden)

Umit Atici

2016-01-01

Full Text Available In rock engineering projects, statically determined parameters are more reflective of actual load conditions than dynamic parameters. This study reports a new and efficient approach to the formulation of the static modulus of elasticity Es applying gene expression programming (GEP with nondestructive testing (NDT methods. The results obtained using GEP are compared with the results of multivariable linear regression analysis (MRA, univariate nonlinear regression analysis (URA, and the dynamic elasticity modulus (Ed. The GEP model was found to produce the most accurate calculation of Es. The proposed approach is a simple, nondestructive, and practical way to determine Es for anisotropic and heterogeneous rocks.

Unified pipe network method for simulation of water flow in fractured porous rock

Science.gov (United States)

Ren, Feng; Ma, Guowei; Wang, Yang; Li, Tuo; Zhu, Hehua

2017-04-01

Rock masses are often conceptualized as dual-permeability media containing fractures or fracture networks with high permeability and porous matrix that is less permeable. In order to overcome the difficulties in simulating fluid flow in a highly discontinuous dual-permeability medium, an effective unified pipe network method is developed, which discretizes the dual-permeability rock mass into a virtual pipe network system. It includes fracture pipe networks and matrix pipe networks. They are constructed separately based on equivalent flow models in a representative area or volume by taking the advantage of the orthogonality of the mesh partition. Numerical examples of fluid flow in 2-D and 3-D domain including porous media and fractured porous media are presented to demonstrate the accuracy, robustness, and effectiveness of the proposed unified pipe network method. Results show that the developed method has good performance even with highly distorted mesh. Water recharge into the fractured rock mass with complex fracture network is studied. It has been found in this case that the effect of aperture change on the water recharge rate is more significant in the early stage compared to the fracture density change.

Numerical Analyses of the Influence of Blast-Induced Damaged Rock Around Shallow Tunnels in Brittle Rock

Science.gov (United States)

Saiang, David; Nordlund, Erling

2009-06-01

Most of the railway tunnels in Sweden are shallow-seated (rock cover) and are located in hard brittle rock masses. The majority of these tunnels are excavated by drilling and blasting, which, consequently, result in the development of a blast-induced damaged zone around the tunnel boundary. Theoretically, the presence of this zone, with its reduced strength and stiffness, will affect the overall performance of the tunnel, as well as its construction and maintenance. The Swedish Railroad Administration, therefore, uses a set of guidelines based on peak particle velocity models and perimeter blasting to regulate the extent of damage due to blasting. However, the real effects of the damage caused by blasting around a shallow tunnel and their criticality to the overall performance of the tunnel are yet to be quantified and, therefore, remain the subject of research and investigation. This paper presents a numerical parametric study of blast-induced damage in rock. By varying the strength and stiffness of the blast-induced damaged zone and other relevant parameters, the near-field rock mass response was evaluated in terms of the effects on induced boundary stresses and ground deformation. The continuum method of numerical analysis was used. The input parameters, particularly those relating to strength and stiffness, were estimated using a systematic approach related to the fact that, at shallow depths, the stress and geologic conditions may be highly anisotropic. Due to the lack of data on the post-failure characteristics of the rock mass, the traditional Mohr-Coulomb yield criterion was assumed and used. The results clearly indicate that, as expected, the presence of the blast-induced damage zone does affect the behaviour of the boundary stresses and ground deformation. Potential failure types occurring around the tunnel boundary and their mechanisms have also been identified.

Data-driven quantification of the robustness and sensitivity of cell signaling networks

International Nuclear Information System (INIS)

Mukherjee, Sayak; Seok, Sang-Cheol; Vieland, Veronica J; Das, Jayajit

2013-01-01

Robustness and sensitivity of responses generated by cell signaling networks has been associated with survival and evolvability of organisms. However, existing methods analyzing robustness and sensitivity of signaling networks ignore the experimentally observed cell-to-cell variations of protein abundances and cell functions or contain ad hoc assumptions. We propose and apply a data-driven maximum entropy based method to quantify robustness and sensitivity of Escherichia coli (E. coli) chemotaxis signaling network. Our analysis correctly rank orders different models of E. coli chemotaxis based on their robustness and suggests that parameters regulating cell signaling are evolutionary selected to vary in individual cells according to their abilities to perturb cell functions. Furthermore, predictions from our approach regarding distribution of protein abundances and properties of chemotactic responses in individual cells based on cell population averaged data are in excellent agreement with their experimental counterparts. Our approach is general and can be used to evaluate robustness as well as generate predictions of single cell properties based on population averaged experimental data in a wide range of cell signaling systems. (paper)

Return Predictability, Model Uncertainty, and Robust Investment

DEFF Research Database (Denmark)

Lukas, Manuel

Stock return predictability is subject to great uncertainty. In this paper we use the model confidence set approach to quantify uncertainty about expected utility from investment, accounting for potential return predictability. For monthly US data and six representative return prediction models, we...... find that confidence sets are very wide, change significantly with the predictor variables, and frequently include expected utilities for which the investor prefers not to invest. The latter motivates a robust investment strategy maximizing the minimal element of the confidence set. The robust investor...... allocates a much lower share of wealth to stocks compared to a standard investor....

New approaches in the indirect quantification of thermal rock properties in sedimentary basins: the well-log perspective

DEFF Research Database (Denmark)

Fuchs, Sven; Balling, Niels; Förster, Andrea

Numerical temperature models generated for geodynamic studies as well as for geothermal energy solutions heavily depend on rock thermal properties. Best practice for the determination of those parameters is the measurement of rock samples in the laboratory. Given the necessity to enlarge databases...

A robust optimization model for blood supply chain in emergency situations

Directory of Open Access Journals (Sweden)

Meysam Fereiduni

2016-09-01

Full Text Available In this paper, a multi-period model for blood supply chain in emergency situation is presented to optimize decisions related to locate blood facilities and distribute blood products after natural disasters. In disastrous situations, uncertainty is an inseparable part of humanitarian logistics and blood supply chain as well. This paper proposes a robust network to capture the uncertain nature of blood supply chain during and after disasters. This study considers donor points, blood facilities, processing and testing labs, and hospitals as the components of blood supply chain. In addition, this paper makes location and allocation decisions for multiple post disaster periods through real data. The study compares the performances of “p-robust optimization” approach and “robust optimization” approach and the results are discussed.

Iconography in Bradshaw rock art: breaking the circularity.

Science.gov (United States)

Pettigrew, Jack

2011-09-01

Interpreting the symbols found in the rock art of an extinct culture is hampered by the fact that such symbols are culturally determined. How does one break the circularity inherent in the fact that the knowledge of both the symbols and the culture comes from the same source? In this study, the circularity is broken for the Bradshaw rock art of the Kimberley by seeking anchors from outside the culture. Bradshaw rock art in the Kimberley region of Australia and Sandawe rock art in the Kolo region of Eastern Tanzania were surveyed in six visits on foot, by vehicle, by helicopter and from published or shared images, as well as from the published and online images of Khoisan rock art. Uniquely shared images between Bradshaw and Sandawe art, such as the 'mushroom head' symbol of psilocybin use, link the two cultures and indicate that they were shamanistic. Therefore, many mysterious features in the art can be understood in terms of trance visualisations. A number of other features uniquely link Bradshaw and Sandawe cultures, such as a special affinity for small mammals. There are also many references to baobabs in early Bradshaw art but not later. This can be explained in the context of the Toba super-volcano, the likely human transport of baobabs to the Kimberley and the extraordinary utility of the baobab. Many more mysterious symbols in Bradshaw rock art might await interpretation using the approaches adopted here. © 2011 The Author. Clinical and Experimental Optometry © 2011 Optometrists Association Australia.

Two-level Robust Measurement Fusion Kalman Filter for Clustering Sensor Networks

Institute of Scientific and Technical Information of China (English)

ZHANG Peng; QI Wen-Juan; DENG Zi-Li

2014-01-01

This paper investigates the distributed fusion Kalman filtering over clustering sensor networks. The sensor network is partitioned as clusters by the nearest neighbor rule and each cluster consists of sensing nodes and cluster-head. Using the minimax robust estimation principle, based on the worst-case conservative system with the conservative upper bounds of noise variances, two-level robust measurement fusion Kalman filter is presented for the clustering sensor network systems with uncertain noise variances. It can significantly reduce the communication load and save energy when the number of sensors is very large. A Lyapunov equation approach for the robustness analysis is presented, by which the robustness of the local and fused Kalman filters is proved. The concept of the robust accuracy is presented, and the robust accuracy relations among the local and fused robust Kalman filters are proved. It is proved that the robust accuracy of the two-level weighted measurement fuser is equal to that of the global centralized robust fuser and is higher than those of each local robust filter and each local weighted measurement fuser. A simulation example shows the correctness and effectiveness of the proposed results.

Geomechanical Anisotropy and Rock Fabric in Shales

Science.gov (United States)

Huffman, K. A.; Connolly, P.; Thornton, D. A.

2017-12-01

Digital rock physics (DRP) is an emerging area of qualitative and quantitative scientific analysis that has been employed on a variety of rock types at various scales to characterize petrophysical, mechanical, and hydraulic rock properties. This contribution presents a generic geomechanically focused DRP workflow involving image segmentation by geomechanical constituents, generation of finite element (FE) meshes, and application of various boundary conditions (i.e. at the edge of the domain and at boundaries of various components such as edges of individual grains). The generic workflow enables use of constituent geological objects and relationships in a computational based approach to address specific questions in a variety of rock types at various scales. Two examples are 1) modeling stress dependent permeability, where it occurs and why it occurs at the grain scale; 2) simulating the path and complexity of primary fractures and matrix damage in materials with minerals or intervals of different mechanical behavior. Geomechanical properties and fabric characterization obtained from 100 micron shale SEM images using the generic DRP workflow are presented. Image segmentation and development of FE simulation composed of relatively simple components (elastic materials, frictional contacts) and boundary conditions enable the determination of bulk static elastic properties. The procedure is repeated for co-located images at pertinent orientations to determine mechanical anisotropy. The static moduli obtained are benchmarked against lab derived measurements since material properties (esp. frictional ones) are poorly constrained at the scale of investigation. Once confidence in the input material parameters is gained, the procedure can be used to characterize more samples (i.e. images) than is possible from rock samples alone. Integration of static elastic properties with grain statistics and geologic (facies) conceptual models derived from core and geophysical logs

Waste-rock interactions in the immediate repository

International Nuclear Information System (INIS)

McCarthy, G.J.

1977-01-01

The high level wastes (HLW's) to be placed underground in rock formations will contain significant amounts of radioactive decay heat for the first hundred-or-so years of isolation. Several physical-chemical changes analogous to natural geochemical processes can occur during this ''thermal period.'' The waste canister can act as a heat source and cause changes in the mineralogy and properties of the surrounding rocks. Geochemically, this is ''contact metamorphism.'' In the event that the canister is corroded and breached, chemical reactions can occur between the HLW, the surrounding rock and possibly the remains of the canister. In a dry repository which has not been backfilled (and thus pressurized) these interactions could be slow at best and with rates decreasing rapidly as the HLW cools. However, significant interactions can occur in years, months or even days under hydrothermal conditions. These conditions could be created by the combination of HLW heat, overburden pressure and water mobilized from the rocks or derived from groundwater intrusion. At the end of the thermal period these interaction products would constitute the actual HLW form (or ''source term'') subject to the low temperature leaching and migration processes under investigation in other laboratories. It is quite possible that these interaction product waste forms will have superior properties compared to the original HLW. Experimental programs initiated at Penn State during the last year aim at determining the nature of any chemical or mineralogical changes in, or interactions between, HLW solids and host rocks under various repository ambients. The accompanying figures describe the simulated HLW forms and the experimental approach and techniques. Studies with basalts as the repository rock are supported by Rockwell Hanford Operations and with shales by the Office of Waste Isolation

Doubly Robust Estimation of Optimal Dynamic Treatment Regimes

DEFF Research Database (Denmark)

Barrett, Jessica K; Henderson, Robin; Rosthøj, Susanne

2014-01-01

We compare methods for estimating optimal dynamic decision rules from observational data, with particular focus on estimating the regret functions defined by Murphy (in J. R. Stat. Soc., Ser. B, Stat. Methodol. 65:331-355, 2003). We formulate a doubly robust version of the regret-regression appro......We compare methods for estimating optimal dynamic decision rules from observational data, with particular focus on estimating the regret functions defined by Murphy (in J. R. Stat. Soc., Ser. B, Stat. Methodol. 65:331-355, 2003). We formulate a doubly robust version of the regret......-regression approach of Almirall et al. (in Biometrics 66:131-139, 2010) and Henderson et al. (in Biometrics 66:1192-1201, 2010) and demonstrate that it is equivalent to a reduced form of Robins' efficient g-estimation procedure (Robins, in Proceedings of the Second Symposium on Biostatistics. Springer, New York, pp....... 189-326, 2004). Simulation studies suggest that while the regret-regression approach is most efficient when there is no model misspecification, in the presence of misspecification the efficient g-estimation procedure is more robust. The g-estimation method can be difficult to apply in complex...

Robustizing Circuit Optimization using Huber Functions

DEFF Research Database (Denmark)

Bandler, John W.; Biernacki, Radek M.; Chen, Steve H.

1993-01-01

The authors introduce a novel approach to 'robustizing' microwave circuit optimization using Huber functions, both two-sided and one-sided. They compare Huber optimization with l/sub 1/, l/sub 2/, and minimax methods in the presence of faults, large and small measurement errors, bad starting poin......, a preliminary optimization by selecting a small number of dominant variables. It is demonstrated, through multiplexer optimization, that the one-sided Huber function can be more effective and efficient than minimax in overcoming a bad starting point.......The authors introduce a novel approach to 'robustizing' microwave circuit optimization using Huber functions, both two-sided and one-sided. They compare Huber optimization with l/sub 1/, l/sub 2/, and minimax methods in the presence of faults, large and small measurement errors, bad starting points......, and statistical uncertainties. They demonstrate FET statistical modeling, multiplexer optimization, analog fault location, and data fitting. They extend the Huber concept by introducing a 'one-sided' Huber function for large-scale optimization. For large-scale problems, the designer often attempts, by intuition...

Site-specific evaluation of safety issues for high-level waste disposal in crystalline rocks. Final report

Energy Technology Data Exchange (ETDEWEB)

Jobmann, M. (ed.) [DBE Technology GmbH, Peine (Germany)

2016-03-31

intent to assist Russian engineers and scientists in their integration into the international scientific community concerned with radioactive waste disposal and to share advanced safety approaches. The corresponding joint R and D activities were pooled in the following three R and D BMWi-funded projects: - ASTER ''Requirements for Site Investigation for a HLW Repository in hard rock Formations'' (2002 - 05), to develop a well-justified methodological approach for site investigation and selection in the Nizhnekansk granitoid formation near Krasnoyarsk, exemplarily for the disposal of conditioned HLW sludge from formerly produced weapons-grade plutonium and vitrified HLW from reprocessing - WIBASTA ''Performance investigation of engineered and geologic barriers of a HLW repository in magmatic host rocks'' (2005 - 08): performance analysis of the system of geologic and engineered barriers based on safety functions, exemplarily for the proposed HLW disposal facility at the Yeniseysky site - URSEL ''Site-specific evaluation of safety issues for HLW disposal in crystalline rocks'' (2008 - 16) Main Objective: Investigation of the robustness of the safety and of the safety assessment of e repository in crystalline rocks. In the last decade of the 20th century, site investigation activities started in various preselected regions of the Nizhnekansky granitoid formation east of Krasnoyarsk. Starting in 2003, preference was given to the Yeniseysky site, which is located several kilometres south east of the underground former production facilities for weapons-grade plutonium of the Mining Chemical Combine (MCC) at Zheleznogorsk. In the beginning, these investigations were performed for the eventual disposal of conditioned HLW sludge from weapons-grade plutonium production and vitrified HLW from reprocessing of the planned reprocessing plant RT-2 at Zheleznogorsk. Recently, priority has been given to so-called class 1 waste

Robust Approach to Verifying the Weak Form of the Efficient Market Hypothesis

Science.gov (United States)

Střelec, Luboš

2011-09-01

The weak form of the efficient markets hypothesis states that prices incorporate only past information about the asset. An implication of this form of the efficient markets hypothesis is that one cannot detect mispriced assets and consistently outperform the market through technical analysis of past prices. One of possible formulations of the efficient market hypothesis used for weak form tests is that share prices follow a random walk. It means that returns are realizations of IID sequence of random variables. Consequently, for verifying the weak form of the efficient market hypothesis, we can use distribution tests, among others, i.e. some tests of normality and/or some graphical methods. Many procedures for testing the normality of univariate samples have been proposed in the literature [7]. Today the most popular omnibus test of normality for a general use is the Shapiro-Wilk test. The Jarque-Bera test is the most widely adopted omnibus test of normality in econometrics and related fields. In particular, the Jarque-Bera test (i.e. test based on the classical measures of skewness and kurtosis) is frequently used when one is more concerned about heavy-tailed alternatives. As these measures are based on moments of the data, this test has a zero breakdown value [2]. In other words, a single outlier can make the test worthless. The reason so many classical procedures are nonrobust to outliers is that the parameters of the model are expressed in terms of moments, and their classical estimators are expressed in terms of sample moments, which are very sensitive to outliers. Another approach to robustness is to concentrate on the parameters of interest suggested by the problem under this study. Consequently, novel robust testing procedures of testing normality are presented in this paper to overcome shortcomings of classical normality tests in the field of financial data, which are typical with occurrence of remote data points and additional types of deviations from

An intrinsic robust rank-one-approximation approach for currencyportfolio optimization

OpenAIRE

Hongxuan Huang; Zhengjun Zhang

2018-01-01

A currency portfolio is a special kind of wealth whose value fluctuates with foreignexchange rates over time, which possesses 3Vs (volume, variety and velocity) properties of big datain the currency market. In this paper, an intrinsic robust rank one approximation (ROA) approachis proposed to maximize the value of currency portfolios over time. The main results of the paperinclude four parts: Firstly, under the assumptions about the currency market, the currency portfoliooptimization problem ...

Systematic and robust design of photonic crystal waveguides by topology optimization

DEFF Research Database (Denmark)

Wang, Fengwen; Jensen, Jakob Søndergaard; Sigmund, Ole

2010-01-01

on a threshold projection. The objective is formulated to minimize the maximum error between actual group indices and a prescribed group index among these three designs. Novel photonic crystal waveguide facilitating slow light with a group index of n(g) = 40 is achieved by the robust optimization approach......A robust topology optimization method is presented to consider manufacturing uncertainties in tailoring dispersion properties of photonic crystal waveguides. The under, normal and over-etching scenarios in manufacturing process are represented by dilated, intermediate and eroded designs based....... The numerical result illustrates that the robust topology optimization provides a systematic and robust design methodology for photonic crystal waveguide design....

Development of the numerical model for reactive transport of radionuclide and bacteria in the single fractured rock

International Nuclear Information System (INIS)

Kim, Jung Woo; Baik, Min Hoon

2010-12-01

On the aspects of safety case of HLW deep geological disposal system, recently, many researchers in the world have been actively studying about the bacterial effects on the radionuclide transport in the fractured rock. However, the domestic research level related on the area is still insufficient. Therefore, the objective of the research is to introduce the theory and development process of the numerical model, which was newly developed to examine the bacterial effects on the radionuclide transport in the single fractured rock, and to test the model by simulating in some imaginary conditions. From the verification by comparing the simulation results with analytical solution considering only solute transport and rock diffusion, the Pearson's correlation coefficient was greater than 0.99 which demonstrates the accuracy of the model. Since the simulation in the model domain of the single fractured core rock resulted in well-matched mass-balances for all solutes, the robustness and stability of the model could be proved again. Therefore, it is expected that the report can guide the potential model users and can be a referring material for a model developer who is trying to expand and/or update the model

A robust metric for screening outliers from analogue product manufacturing tests responses

NARCIS (Netherlands)

Krishnan, S.; Kerkhoff, H.G.

2011-01-01

Mahalanobis distance is one of the commonly used multivariate metrics for finely segregating defective devices from non-defective ones. An associated problem with this approach is the estimation of a robust mean and a covariance matrix. In the absence of such robust estimates, especially in the

A Robust Metric for Screening Outliers from Analogue Product Manufacturing Tests Responses

NARCIS (Netherlands)

Krishnan, Shaji; Krishnan, Shaji; Kerkhoff, Hans G.

2011-01-01

Mahalanobis distance is one of the commonly used multivariate metrics for finely segregating defective devices from non-defective ones. An associated problem with this approach is the estimation of a robust mean and a covariance matrix. In the absence of such robust estimates, especially in the

Rapid formation of rock armour for soil - rock fragment mixture during simulated rainfall

Science.gov (United States)

Poultney, E.; McGrath, G. S.; Hinz, C.

2009-04-01

Preventing erosion is an important issue in disturbed semi-arid and arid landscapes. This is in particular of highest importance for mining companies while undertaking land rehabilitation. An onsite investigation of the impact of surface rock fragments on erosion was conducted at Telfer goldmine in the Great Sandy Desert, Western Australia. The study site is a waste rock dump designed to mimic the concave slope of a natural mesa to both discourage erosion and blend in with its natural surroundings. Four treatments were used to construct the slope: two are topsoil mixed with rock fragments, and two are unmixed topsoil. A field study investigating erosion rills, particle size distribution, rock fragment coverage surface roughness and vegetation was carried out to determine changes down and across slope. The treatments constructed by mixing topsoil and rock fragments are more stable and show rock fragment distributions that more closely resemble patterns found on natural mesas surrounding Telfer. A controlled study using trays of topsoil mixed with rock fragment volumes of 50%, 60%, 70% and 80% were used to investigate how varying mixtures of rock fragments and topsoil erode using rainfall intensities between 20 and 100 mm h-1. Two runs of 25 minutes each were used to assess the temporal evolution of rock armouring. Surface coverage results converged for the 50%, 60% and 70% mixtures after the first run to coverage of about 90%, suggesting that fine sediment proportion does not affect rate and degree of rock armouring.

Incoherent SSI Analysis of Reactor Building using 2007 Hard-Rock Coherency Model

International Nuclear Information System (INIS)

Kang, Joo-Hyung; Lee, Sang-Hoon

2008-01-01

Many strong earthquake recordings show the response motions at building foundations to be less intense than the corresponding free-field motions. To account for these phenomena, the concept of spatial variation, or wave incoherence was introduced. Several approaches for its application to practical analysis and design as part of soil-structure interaction (SSI) effect have been developed. However, conventional wave incoherency models didn't reflect the characteristics of earthquake data from hard-rock site, and their application to the practical nuclear structures on the hard-rock sites was not justified sufficiently. This paper is focused on the response impact of hard-rock coherency model proposed in 2007 on the incoherent SSI analysis results of nuclear power plant (NPP) structure. A typical reactor building of pressurized water reactor (PWR) type NPP is modeled classified into surface and embedded foundations. The model is also assumed to be located on medium-hard rock and hard-rock sites. The SSI analysis results are obtained and compared in case of coherent and incoherent input motions. The structural responses considering rocking and torsion effects are also investigated

Robustness Analysis of Real Network Topologies Under Multiple Failure Scenarios

DEFF Research Database (Denmark)

Manzano, M.; Marzo, J. L.; Calle, E.

2012-01-01

on topological characteristics. Recently approaches also consider the services supported by such networks. In this paper we carry out a robustness analysis of five real backbone telecommunication networks under defined multiple failure scenarios, taking into account the consequences of the loss of established......Nowadays the ubiquity of telecommunication networks, which underpin and fulfill key aspects of modern day living, is taken for granted. Significant large-scale failures have occurred in the last years affecting telecommunication networks. Traditionally, network robustness analysis has been focused...... connections. Results show which networks are more robust in response to a specific type of failure....

Robust Hydrological Forecasting for High-resolution Distributed Models Using a Unified Data Assimilation Approach

Science.gov (United States)

Hernandez, F.; Liang, X.

2017-12-01

Reliable real-time hydrological forecasting, to predict important phenomena such as floods, is invaluable to the society. However, modern high-resolution distributed models have faced challenges when dealing with uncertainties that are caused by the large number of parameters and initial state estimations involved. Therefore, to rely on these high-resolution models for critical real-time forecast applications, considerable improvements on the parameter and initial state estimation techniques must be made. In this work we present a unified data assimilation algorithm called Optimized PareTo Inverse Modeling through Inverse STochastic Search (OPTIMISTS) to deal with the challenge of having robust flood forecasting for high-resolution distributed models. This new algorithm combines the advantages of particle filters and variational methods in a unique way to overcome their individual weaknesses. The analysis of candidate particles compares model results with observations in a flexible time frame, and a multi-objective approach is proposed which attempts to simultaneously minimize differences with the observations and departures from the background states by using both Bayesian sampling and non-convex evolutionary optimization. Moreover, the resulting Pareto front is given a probabilistic interpretation through kernel density estimation to create a non-Gaussian distribution of the states. OPTIMISTS was tested on a low-resolution distributed land surface model using VIC (Variable Infiltration Capacity) and on a high-resolution distributed hydrological model using the DHSVM (Distributed Hydrology Soil Vegetation Model). In the tests streamflow observations are assimilated. OPTIMISTS was also compared with a traditional particle filter and a variational method. Results show that our method can reliably produce adequate forecasts and that it is able to outperform those resulting from assimilating the observations using a particle filter or an evolutionary 4D variational

Robust H∞ output-feedback control for path following of autonomous ground vehicles

Science.gov (United States)

Hu, Chuan; Jing, Hui; Wang, Rongrong; Yan, Fengjun; Chadli, Mohammed

2016-03-01

This paper presents a robust H∞ output-feedback control strategy for the path following of autonomous ground vehicles (AGVs). Considering the vehicle lateral velocity is usually hard to measure with low cost sensor, a robust H∞ static output-feedback controller based on the mixed genetic algorithms (GA)/linear matrix inequality (LMI) approach is proposed to realize the path following without the information of the lateral velocity. The proposed controller is robust to the parametric uncertainties and external disturbances, with the parameters including the tire cornering stiffness, vehicle longitudinal velocity, yaw rate and road curvature. Simulation results based on CarSim-Simulink joint platform using a high-fidelity and full-car model have verified the effectiveness of the proposed control approach.

Development of artificial soft rock

International Nuclear Information System (INIS)

Kishi, Kiyoshi

1995-01-01

When foundation base rocks are deeper than the level of installing structures or there exist weathered rocks and crushed rocks in a part of base rocks, often sound artificial base rocks are made by substituting the part with concrete. But in the construction of Kashiwazaki Kariwa Nuclear Power Station of Tokyo Electric Power Co., Inc., the foundation base rocks consist of mudstone, and the stiffness of concrete is large as compared with the surrounding base rocks. As the quality of the substituting material, the nearly same stiffness as that of the surrounding soft rocks and long term stability are suitable, and the excellent workability and economical efficiency are required, therefore, artificial soft rocks were developed. As the substituting material, the soil mortar that can obtain the physical property values in stable form, which are similar to those of Nishiyama mudstone, was selected. The mechanism of its hardening and the long term stability, and the manufacturing plant are reported. As for its application to the base rocks of Kashiwazaki Kariwa Nuclear Power Station, the verification test at the site and the application to the base rocks for No. 7 plant reactor building and other places are described. (K.I.)

Material constitutive model for jointed rock mass behavior

International Nuclear Information System (INIS)

Thomas, R.K.

1980-11-01

A material constitutive model is presented for jointed rock masses which exhibit preferred planes of weakness. This model is intended for use in finite element computations. The immediate application is the thermomechanical modelling of a nuclear waste repository in hard rock, but the model seems appropriate for a variety of other static and dynamic geotechnical problems as well. Starting with the finite element representations of a two-dimensional elastic body, joint planes are introduced in an explicit manner by direct modification of the material stiffness matrix. A novel feature of this approach is that joint set orientations, lengths and spacings are readily assigned through the sampling of a population distribution statistically determined from field measurement data. The result is that the fracture characteristics of the formations have the same statistical distribution in the model as is observed in the field. As a demonstration of the jointed rock mass model, numerical results are presented for the example problem of stress concentration at an underground opening

An Online Social Networking Approach to Reinforce Learning of Rocks and Minerals

Science.gov (United States)

Kennelly, Patrick

2009-01-01

Numerous and varied methods are used in introductory Earth science and geology classes to help students learn about rocks and minerals, such as classroom lectures, laboratory specimen identification, and field trips. This paper reports on a method using online social networking. The choice of this forum was based on two criteria. First, many…

Robust inference in the negative binomial regression model with an application to falls data.

Science.gov (United States)

Aeberhard, William H; Cantoni, Eva; Heritier, Stephane

2014-12-01

A popular way to model overdispersed count data, such as the number of falls reported during intervention studies, is by means of the negative binomial (NB) distribution. Classical estimating methods are well-known to be sensitive to model misspecifications, taking the form of patients falling much more than expected in such intervention studies where the NB regression model is used. We extend in this article two approaches for building robust M-estimators of the regression parameters in the class of generalized linear models to the NB distribution. The first approach achieves robustness in the response by applying a bounded function on the Pearson residuals arising in the maximum likelihood estimating equations, while the second approach achieves robustness by bounding the unscaled deviance components. For both approaches, we explore different choices for the bounding functions. Through a unified notation, we show how close these approaches may actually be as long as the bounding functions are chosen and tuned appropriately, and provide the asymptotic distributions of the resulting estimators. Moreover, we introduce a robust weighted maximum likelihood estimator for the overdispersion parameter, specific to the NB distribution. Simulations under various settings show that redescending bounding functions yield estimates with smaller biases under contamination while keeping high efficiency at the assumed model, and this for both approaches. We present an application to a recent randomized controlled trial measuring the effectiveness of an exercise program at reducing the number of falls among people suffering from Parkinsons disease to illustrate the diagnostic use of such robust procedures and their need for reliable inference. © 2014, The International Biometric Society.

ROCK-CAD - computer aided geological modelling system

International Nuclear Information System (INIS)

Saksa, P.

1995-12-01

The study discusses surface and solid modelling methods, their use and interfacing with geodata. Application software named ROCK-CAD suitable for geological bedrock modelling has been developed with support from Teollisuuden Voima Oy (TVO). It has been utilized in the Finnish site characterization programme for spent nuclear fuel waste disposal during the 1980s and 1990s. The system is based on the solid modelling technique. It comprises also rich functionality for the particular geological modelling scheme. The ROCK-CAD system provides, among other things, varying graphical vertical and horizontal intersections and perspective illustrations. The specially developed features are the application of the boundary representation modelling method, parametric object generation language and the discipline approach. The ROCK-CAD system has been utilized in modelling spatial distribution of rock types and fracturing structures in TVO's site characterization. The Olkiluoto site at Eurajoki serves as an example case. The study comprises the description of the modelling process, models and illustration examples. The utilization of bedrock models in site characterization, in tentative repository siting as well as in groundwater flow simulation is depicted. The application software has improved the assessment of the sites studied, given a new basis for the documentation of interpretation and modelling work, substituted hand-drawing and enabled digital transfer to numerical analysis. Finally, aspects of presentation graphics in geological modelling are considered. (84 refs., 30 figs., 11 tabs.)

Robust Adaptive Speed Control of Induction Motor Drives

DEFF Research Database (Denmark)

Bidstrup, N.

, (LS) identification and generalized predictive control (GPC) has been implemented and tested on the CVC drive. Allthough GPC is a robust control method, it was not possible to maintain specified controller performance in the entire operating range. This was the main reason for investigating truly...... adaptive speed control of the CVC drive. A direct truly adaptive speed controller has been implemented. The adaptive controller is a moving Average Self-Tuning Regulator which is abbreviated MASTR throughout the thesis. Two practical implementations of this controller were proposed. They were denoted MASTR...... and measurement noise in general, were the major reasons for the drifting parameters. Two approaches was proposed to robustify MASTR2 against the output noise. The first approach consists of filtering the output. Output filtering had a significant effect in simulations, but the robustness against the output noise...

Robust Adaptive Speed Control of Induction Motor Drives

DEFF Research Database (Denmark)

Bidstrup, N.

This thesis concerns speed control of current vector controlled induction motor drives (CVC drives). The CVC drive is an existing prototype drive developed by Danfoss A/S, Transmission Division. Practical tests have revealed that the open loop dynamical properties of the CVC drive are highly......, (LS) identification and generalized predictive control (GPC) has been implemented and tested on the CVC drive. Allthough GPC is a robust control method, it was not possible to maintain specified controller performance in the entire operating range. This was the main reason for investigating truly...... and measurement noise in general, were the major reasons for the drifting parameters. Two approaches was proposed to robustify MASTR2 against the output noise. The first approach consists of filtering the output. Output filtering had a significant effect in simulations, but the robustness against the output noise...

Memory-Efficient Onboard Rock Segmentation

Science.gov (United States)

Burl, Michael C.; Thompson, David R.; Bornstein, Benjamin J.; deGranville, Charles K.

2013-01-01

Rockster-MER is an autonomous perception capability that was uploaded to the Mars Exploration Rover Opportunity in December 2009. This software provides the vision front end for a larger software system known as AEGIS (Autonomous Exploration for Gathering Increased Science), which was recently named 2011 NASA Software of the Year. As the first step in AEGIS, Rockster-MER analyzes an image captured by the rover, and detects and automatically identifies the boundary contours of rocks and regions of outcrop present in the scene. This initial segmentation step reduces the data volume from millions of pixels into hundreds (or fewer) of rock contours. Subsequent stages of AEGIS then prioritize the best rocks according to scientist- defined preferences and take high-resolution, follow-up observations. Rockster-MER has performed robustly from the outset on the Mars surface under challenging conditions. Rockster-MER is a specially adapted, embedded version of the original Rockster algorithm ("Rock Segmentation Through Edge Regrouping," (NPO- 44417) Software Tech Briefs, September 2008, p. 25). Although the new version performs the same basic task as the original code, the software has been (1) significantly upgraded to overcome the severe onboard re source limitations (CPU, memory, power, time) and (2) "bulletproofed" through code reviews and extensive testing and profiling to avoid the occurrence of faults. Because of the limited computational power of the RAD6000 flight processor on Opportunity (roughly two orders of magnitude slower than a modern workstation), the algorithm was heavily tuned to improve its speed. Several functional elements of the original algorithm were removed as a result of an extensive cost/benefit analysis conducted on a large set of archived rover images. The algorithm was also required to operate below a stringent 4MB high-water memory ceiling; hence, numerous tricks and strategies were introduced to reduce the memory footprint. Local filtering

Stability Constraints for Robust Model Predictive Control

Directory of Open Access Journals (Sweden)

Amanda G. S. Ottoni

2015-01-01

Full Text Available This paper proposes an approach for the robust stabilization of systems controlled by MPC strategies. Uncertain SISO linear systems with box-bounded parametric uncertainties are considered. The proposed approach delivers some constraints on the control inputs which impose sufficient conditions for the convergence of the system output. These stability constraints can be included in the set of constraints dealt with by existing MPC design strategies, in this way leading to the “robustification” of the MPC.

Robust multivariate analysis

CERN Document Server

J Olive, David

2017-01-01

This text presents methods that are robust to the assumption of a multivariate normal distribution or methods that are robust to certain types of outliers. Instead of using exact theory based on the multivariate normal distribution, the simpler and more applicable large sample theory is given.  The text develops among the first practical robust regression and robust multivariate location and dispersion estimators backed by theory.   The robust techniques  are illustrated for methods such as principal component analysis, canonical correlation analysis, and factor analysis.  A simple way to bootstrap confidence regions is also provided. Much of the research on robust multivariate analysis in this book is being published for the first time. The text is suitable for a first course in Multivariate Statistical Analysis or a first course in Robust Statistics. This graduate text is also useful for people who are familiar with the traditional multivariate topics, but want to know more about handling data sets with...

Teaching the Rock Cycle with Ease.

Science.gov (United States)

Bereki, Debra

2000-01-01

Describes a hands-on lesson for teaching high school students the concept of the rock cycle using sedimentary, metamorphic, and igneous rocks. Students use a rock cycle diagram to identify pairs of rocks. From the rock cycle, students explain on paper how their first rock became the second rock and vice versa. (PVD)

Anisotropy of strength and deformability of fractured rocks

Directory of Open Access Journals (Sweden)

Majid Noorian Bidgoli

2014-04-01

Full Text Available Anisotropy of the strength and deformation behaviors of fractured rock masses is a crucial issue for design and stability assessments of rock engineering structures, due mainly to the non-uniform and non-regular geometries of the fracture systems. However, no adequate efforts have been made to study this issue due to the current practical impossibility of laboratory tests with samples of large volumes containing many fractures, and the difficulty for controlling reliable initial and boundary conditions for large-scale in situ tests. Therefore, a reliable numerical predicting approach for evaluating anisotropy of fractured rock masses is needed. The objective of this study is to systematically investigate anisotropy of strength and deformability of fractured rocks, which has not been conducted in the past, using a numerical modeling method. A series of realistic two-dimensional (2D discrete fracture network (DFN models were established based on site investigation data, which were then loaded in different directions, using the code UDEC of discrete element method (DEM, with changing confining pressures. Numerical results show that strength envelopes and elastic deformability parameters of tested numerical models are significantly anisotropic, and vary with changing axial loading and confining pressures. The results indicate that for design and safety assessments of rock engineering projects, the directional variations of strength and deformability of the fractured rock mass concerned must be treated properly with respect to the directions of in situ stresses. Traditional practice for simply positioning axial orientation of tunnels in association with principal stress directions only may not be adequate for safety requirements. Outstanding issues of the present study and suggestions for future study are also presented.

Recreating Rocks

DEFF Research Database (Denmark)

Posth, Nicole R

2008-01-01

Nicole Posth and colleagues spent a month touring South African rock formations in their quest to understand the origin of ancient iron and silicate layers.......Nicole Posth and colleagues spent a month touring South African rock formations in their quest to understand the origin of ancient iron and silicate layers....

Robust optimization methods for cardiac sparing in tangential breast IMRT

Energy Technology Data Exchange (ETDEWEB)

Mahmoudzadeh, Houra, E-mail: houra@mie.utoronto.ca [Mechanical and Industrial Engineering Department, University of Toronto, Toronto, Ontario M5S 3G8 (Canada); Lee, Jenny [Radiation Medicine Program, UHN Princess Margaret Cancer Centre, Toronto, Ontario M5G 2M9 (Canada); Chan, Timothy C. Y. [Mechanical and Industrial Engineering Department, University of Toronto, Toronto, Ontario M5S 3G8, Canada and Techna Institute for the Advancement of Technology for Health, Toronto, Ontario M5G 1P5 (Canada); Purdie, Thomas G. [Radiation Medicine Program, UHN Princess Margaret Cancer Centre, Toronto, Ontario M5G 2M9 (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 3S2 (Canada); Techna Institute for the Advancement of Technology for Health, Toronto, Ontario M5G 1P5 (Canada)

2015-05-15

Purpose: In left-sided tangential breast intensity modulated radiation therapy (IMRT), the heart may enter the radiation field and receive excessive radiation while the patient is breathing. The patient’s breathing pattern is often irregular and unpredictable. We verify the clinical applicability of a heart-sparing robust optimization approach for breast IMRT. We compare robust optimized plans with clinical plans at free-breathing and clinical plans at deep inspiration breath-hold (DIBH) using active breathing control (ABC). Methods: Eight patients were included in the study with each patient simulated using 4D-CT. The 4D-CT image acquisition generated ten breathing phase datasets. An average scan was constructed using all the phase datasets. Two of the eight patients were also imaged at breath-hold using ABC. The 4D-CT datasets were used to calculate the accumulated dose for robust optimized and clinical plans based on deformable registration. We generated a set of simulated breathing probability mass functions, which represent the fraction of time patients spend in different breathing phases. The robust optimization method was applied to each patient using a set of dose-influence matrices extracted from the 4D-CT data and a model of the breathing motion uncertainty. The goal of the optimization models was to minimize the dose to the heart while ensuring dose constraints on the target were achieved under breathing motion uncertainty. Results: Robust optimized plans were improved or equivalent to the clinical plans in terms of heart sparing for all patients studied. The robust method reduced the accumulated heart dose (D10cc) by up to 801 cGy compared to the clinical method while also improving the coverage of the accumulated whole breast target volume. On average, the robust method reduced the heart dose (D10cc) by 364 cGy and improved the optBreast dose (D99%) by 477 cGy. In addition, the robust method had smaller deviations from the planned dose to the

Hydrological characteristics of Japanese rock

International Nuclear Information System (INIS)

Ijiri, Yuji; Sawada, Atsushi; Akahori, Kuniaki

1999-11-01

It is crucial to evaluate the hydrogeological characteristics of rock in Japan in order to assess the performance of geosphere. This report summarizes the hydrogeological characteristics of various rock types obtained from broad literature surveys and the fields experiments at the Kamaishi mine in northern Japan and at the Tono mine in central Japan. It is found that the hydraulic conductivity of rock mass ranges from 10 -9 m/s to 10 -8 m/s, whereas the hydraulic conductivity of fault zone ranges from 10 -9 m/s to 10 -3 m/s. It is also found that the hydraulic conductivity tends to decrease with depth. Therefore, the hydraulic conductivity of rock mass at the depth of a repository will be smaller than above values. From the investigations at outcrops and galleries throughout the country, fractures are observed as potential pathways in all rock types. All kinds of crystalline rocks and pre-Neogene sedimentary rocks are classified as fractured media where fracture flow is dominant. Among these rocks, granitic rock is considered the archetype fractured media. On the other hand, andesite, tuff and Neogene sedimentary rocks are considered as intermediate between fractured media and porous media where flow in fractures as well as in rock matrix are significant. (author)

Rock mechanics stability at Olkiluoto, Haestholmen, Kivetty and Romuvaara

International Nuclear Information System (INIS)

Johansson, E.; Rautakorpi, J.

2000-02-01

Posiva Oy is studying the suitability of the Finnish bedrock for the geological disposal of spent nuclear fuel at four sites, Olkiluoto in Eurajoki, Haestholmen in Loviisa, Kivetty in Aeaenekoski and Romuvaara in Kuhmo. To enable the rock properties to be specified in great detail, the site-selection research programme has included rock mechanics investigations such as the measurement of in-situ rock stress and laboratory tests on rock samples. This report presents the results of the rock mechanics analyses performed on the main rock types at the Olkiluoto, Romuvaara, Kivetty and Haestholmen sites. The objective of this study was to assess the near-field stability of the final disposal tunnels and deposition holes at each of the investigation sites. Two empirical methods and a numerical method based on three-dimensional element code (3DEC) were used the analysis tools. A statistical approach was used to select the necessary input data and to specify the cases being analysed. The stability of the KBS-3 and MLH (Medium Long Hole) repository concepts during the pre-closure and post-closure phases was analysed. The repository depths investigated lay between 300 m and 700 m. The empirical methods are based on the study of the ratios between rock strength and the in-situ stress which could result in possible fracturing of the rock mass. Interpretation of the numerical analyses is based on the assumption of an elastic distribution of stress around the disposal tunnel and the deposition hole and the brittle rock strength criterion. The results obtained in this study indicate that in general, the rock mechanics conditions during the pre-closure and post-closure phases at each of the investigated sites remain good and stable between the studied depth levels, especially when the deposition rooms are oriented in a direction parallel to the major in-situ stress. If the disposal tunnels are orientated in a direction perpendicular to the major in-situ stress, the resultant

Shape, size, and robustness: feasible regions in the parameter space of biochemical networks.

Directory of Open Access Journals (Sweden)

Adel Dayarian

2009-01-01

Full Text Available The concept of robustness of regulatory networks has received much attention in the last decade. One measure of robustness has been associated with the volume of the feasible region, namely, the region in the parameter space in which the system is functional. In this paper, we show that, in addition to volume, the geometry of this region has important consequences for the robustness and the fragility of a network. We develop an approximation within which we could algebraically specify the feasible region. We analyze the segment polarity gene network to illustrate our approach. The study of random walks in the parameter space and how they exit the feasible region provide us with a rich perspective on the different modes of failure of this network model. In particular, we found that, between two alternative ways of activating Wingless, one is more robust than the other. Our method provides a more complete measure of robustness to parameter variation. As a general modeling strategy, our approach is an interesting alternative to Boolean representation of biochemical networks.

Robustness of Structures

DEFF Research Database (Denmark)

Faber, Michael Havbro; Vrouwenvelder, A.C.W.M.; Sørensen, John Dalsgaard

2011-01-01

In 2005, the Joint Committee on Structural Safety (JCSS) together with Working Commission (WC) 1 of the International Association of Bridge and Structural Engineering (IABSE) organized a workshop on robustness of structures. Two important decisions resulted from this workshop, namely...... ‘COST TU0601: Robustness of Structures’ was initiated in February 2007, aiming to provide a platform for exchanging and promoting research in the area of structural robustness and to provide a basic framework, together with methods, strategies and guidelines enhancing robustness of structures...... the development of a joint European project on structural robustness under the COST (European Cooperation in Science and Technology) programme and the decision to develop a more elaborate document on structural robustness in collaboration between experts from the JCSS and the IABSE. Accordingly, a project titled...

Rock Goes to School on Screen: A Model for Teaching Non-"Learned" Musics Derived from the Films "School of Rock" (2003) and "Rock School" (2005)

Science.gov (United States)

Webb, Michael

2007-01-01

What can be learned from two films with "rock" and "school" in their titles, about rock in school and about music and schooling more broadly? "School of Rock" (2003), a "family comedy," and "Rock School" (2005), a documentary, provoke a range of questions, ideological and otherwise, surrounding the inclusion of rock in formal instructional…

Grinding into Soft, Powdery Rock

Science.gov (United States)

2004-01-01

This hole in a rock dubbed 'Clovis' is the deepest hole drilled so far in any rock on Mars. NASA's Mars Exploration Rover Spirit captured this view with its microscopic imager on martian sol 217 (Aug. 12, 2004) after drilling 8.9 millimeters (0.35 inch) into the rock with its rock abrasion tool. The view is a mosaic of four frames taken by the microscopic imager. The hole is 4.5 centimeters (1.8 inches) in diameter. Clovis is key to a developing story about environmental change on Mars, not only because it is among the softest rocks encountered so far in Gusev Crater, but also because it contains mineral alterations that extend relatively deep beneath its surface. In fact, as evidenced by its fairly crumbly texture, it is possibly the most highly altered volcanic rock ever studied on Mars. Scientific analysis shows that the rock contains higher levels of the elements sulfur, chlorine, and bromine than are normally encountered in basaltic rocks, such as a rock dubbed 'Humphrey' that Spirit encountered two months after arriving on Mars. Humphrey showed elevated levels of sulfur, chlorine, and bromine only in the outermost 2 millimeters (less than 0.1 inch) of its surface. Clovis shows elevated levels of the same elements along with the associated softness of the rock within a borehole that is 4 times as deep. Scientists hope to compare Clovis to other, less-altered rocks in the vicinity to assess what sort of water-based processes altered the rock. Hypotheses include transport of sulfur, chlorine, and bromine in water vapor in volcanic gases; hydrothermal circulation (flow of volcanically heated water through rock); or saturation in a briny soup containing the same elements. In this image, very fine-grained material from the rock has clumped together by electrostatic attraction and fallen into the borehole. NASA/JPL/Cornell/USGS

Robust control of an industrial boiler system; a comparison between two approaches: Sliding mode control and H∞ technique

International Nuclear Information System (INIS)

Moradi, Hamed; Bakhtiari-Nejad, Firooz; Saffar-Avval, Majid

2009-01-01

To achieve a good performance of the utility boiler, dynamic variables such as drum pressure, steam temperature and water level of drum must be controlled. In this paper, a linear time invariant (LTI) model of a boiler system is considered in which the input variables are feed-water and fuel mass rates. However this dynamic model may associate with uncertainties. With considering the uncertainties of the dynamic model, a sliding mode controller is designed. After representation of the uncertain dynamic system in general control configuration and modelling the parametric uncertainties, nominal performance, robust stability and robust performance are analyzed by the concept of structured singular value μ. Using an algorithm for μ-analysis and applying an inversed-base controller, robust stability and nominal performance are guaranteed but robust performance is not satisfied. Finally, an optimal robust controller is designed based on μ-synthesis with DK-iteration algorithm. Both optimal robust and sliding mode controllers guarantee robust performance of the system against the uncertainties and result in desired time responses of the output variables. By applying H ∞ robust control, system tracks the desire reference inputs in a less time and with smoother time responses. However, less control efforts, feedwater and fuel mass rates, are needed when the sliding mode controller is applied.

Robust Decentralized Formation Flight Control

Directory of Open Access Journals (Sweden)

Zhao Weihua

2011-01-01

Full Text Available Motivated by the idea of multiplexed model predictive control (MMPC, this paper introduces a new framework for unmanned aerial vehicles (UAVs formation flight and coordination. Formulated using MMPC approach, the whole centralized formation flight system is considered as a linear periodic system with control inputs of each UAV subsystem as its periodic inputs. Divided into decentralized subsystems, the whole formation flight system is guaranteed stable if proper terminal cost and terminal constraints are added to each decentralized MPC formulation of the UAV subsystem. The decentralized robust MPC formulation for each UAV subsystem with bounded input disturbances and model uncertainties is also presented. Furthermore, an obstacle avoidance control scheme for any shape and size of obstacles, including the nonapriorily known ones, is integrated under the unified MPC framework. The results from simulations demonstrate that the proposed framework can successfully achieve robust collision-free formation flights.

A Robust Photogrammetric Processing Method of Low-Altitude UAV Images

Directory of Open Access Journals (Sweden)

Mingyao Ai

2015-02-01

Full Text Available Low-altitude Unmanned Aerial Vehicles (UAV images which include distortion, illumination variance, and large rotation angles are facing multiple challenges of image orientation and image processing. In this paper, a robust and convenient photogrammetric approach is proposed for processing low-altitude UAV images, involving a strip management method to automatically build a standardized regional aerial triangle (AT network, a parallel inner orientation algorithm, a ground control points (GCPs predicting method, and an improved Scale Invariant Feature Transform (SIFT method to produce large number of evenly distributed reliable tie points for bundle adjustment (BA. A multi-view matching approach is improved to produce Digital Surface Models (DSM and Digital Orthophoto Maps (DOM for 3D visualization. Experimental results show that the proposed approach is robust and feasible for photogrammetric processing of low-altitude UAV images and 3D visualization of products.

THM-coupled modeling of selected processes in argillaceous rock relevant to rock mechanics

International Nuclear Information System (INIS)

Czaikowski, Oliver

2012-01-01

Scientific investigations in European countries other than Germany concentrate not only on granite formations (Switzerland, Sweden) but also on argillaceous rock formations (France, Switzerland, Belgium) to assess their suitability as host and barrier rock for the final storage of radioactive waste. In Germany, rock salt has been under thorough study as a host rock over the past few decades. According to a study by the German Federal Institute for Geosciences and Natural Resources, however, not only salt deposits but also argillaceous rock deposits are available at relevant depths and of extensions in space which make final storage of high-level radioactive waste basically possible in Germany. Equally qualified findings about the suitability/unsuitability of non-saline rock formations require fundamental studies to be conducted nationally because of the comparatively low level of knowledge. The article presents basic analyses of coupled mechanical and hydraulic properties of argillaceous rock formations as host rock for a repository. The interaction of various processes is explained on the basis of knowledge derived from laboratory studies, and open problems are deduced. For modeling coupled processes, a simplified analytical computation method is proposed and compared with the results of numerical simulations, and the limits to its application are outlined. (orig.)

Seismic response of rock joints and jointed rock mass

International Nuclear Information System (INIS)

Ghosh, A.; Hsiung, S.M.; Chowdhury, A.H.

1996-06-01

Long-term stability of emplacement drifts and potential near-field fluid flow resulting from coupled effects are among the concerns for safe disposal of high-level nuclear waste (HLW). A number of factors can induce drift instability or change the near-field flow patterns. Repetitive seismic loads from earthquakes and thermal loads generated by the decay of emplaced waste are two significant factors. One of two key technical uncertainties (KTU) that can potentially pose a high risk of noncompliance with the performance objectives of 10 CFR Part 60 is the prediction of thermal-mechanical (including repetitive seismic load) effects on stability of emplacement drifts and the engineered barrier system. The second KTU of concern is the prediction of thermal-mechanical-hydrological (including repetitive seismic load) effects on the host rock surrounding the engineered barrier system. The Rock Mechanics research project being conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) is intended to address certain specific technical issues associated with these two KTUs. This research project has two major components: (i) seismic response of rock joints and a jointed rock mass and (ii) coupled thermal-mechanical-hydrological (TMH) response of a jointed rock mass surrounding the engineered barrier system (EBS). This final report summarizes the research activities concerned with the repetitive seismic load aspect of both these KTUs

Robust Transceiver Design for Multiuser MIMO Downlink with Channel Uncertainties

Science.gov (United States)

Miao, Wei; Li, Yunzhou; Chen, Xiang; Zhou, Shidong; Wang, Jing

This letter addresses the problem of robust transceiver design for the multiuser multiple-input-multiple-output (MIMO) downlink where the channel state information at the base station (BS) is imperfect. A stochastic approach which minimizes the expectation of the total mean square error (MSE) of the downlink conditioned on the channel estimates under a total transmit power constraint is adopted. The iterative algorithm reported in [2] is improved to handle the proposed robust optimization problem. Simulation results show that our proposed robust scheme effectively reduces the performance loss due to channel uncertainties and outperforms existing methods, especially when the channel errors of the users are different.

The thin section rock physics: Modeling and measurement of seismic wave velocity on the slice of carbonates

Energy Technology Data Exchange (ETDEWEB)

Wardaya, P. D., E-mail: pongga.wardaya@utp.edu.my; Noh, K. A. B. M., E-mail: pongga.wardaya@utp.edu.my; Yusoff, W. I. B. W., E-mail: pongga.wardaya@utp.edu.my [Petroleum Geosciences Department, Universiti Teknologi PETRONAS, Tronoh, Perak, 31750 (Malaysia); Ridha, S. [Petroleum Engineering Department, Universiti Teknologi PETRONAS, Tronoh, Perak, 31750 (Malaysia); Nurhandoko, B. E. B. [Wave Inversion and Subsurface Fluid Imaging Research Laboratory (WISFIR), Dept. of Physics, Institute of Technology Bandung, Bandung, Indonesia and Rock Fluid Imaging Lab, Bandung (Indonesia)

2014-09-25

This paper discusses a new approach for investigating the seismic wave velocity of rock, specifically carbonates, as affected by their pore structures. While the conventional routine of seismic velocity measurement highly depends on the extensive laboratory experiment, the proposed approach utilizes the digital rock physics view which lies on the numerical experiment. Thus, instead of using core sample, we use the thin section image of carbonate rock to measure the effective seismic wave velocity when travelling on it. In the numerical experiment, thin section images act as the medium on which wave propagation will be simulated. For the modeling, an advanced technique based on artificial neural network was employed for building the velocity and density profile, replacing image's RGB pixel value with the seismic velocity and density of each rock constituent. Then, ultrasonic wave was simulated to propagate in the thin section image by using finite difference time domain method, based on assumption of an acoustic-isotropic medium. Effective velocities were drawn from the recorded signal and being compared to the velocity modeling from Wyllie time average model and Kuster-Toksoz rock physics model. To perform the modeling, image analysis routines were undertaken for quantifying the pore aspect ratio that is assumed to represent the rocks pore structure. In addition, porosity and mineral fraction required for velocity modeling were also quantified by using integrated neural network and image analysis technique. It was found that the Kuster-Toksoz gives the closer prediction to the measured velocity as compared to the Wyllie time average model. We also conclude that Wyllie time average that does not incorporate the pore structure parameter deviates significantly for samples having more than 40% porosity. Utilizing this approach we found a good agreement between numerical experiment and theoretically derived rock physics model for estimating the effective seismic

The thin section rock physics: Modeling and measurement of seismic wave velocity on the slice of carbonates

International Nuclear Information System (INIS)

Wardaya, P. D.; Noh, K. A. B. M.; Yusoff, W. I. B. W.; Ridha, S.; Nurhandoko, B. E. B.

2014-01-01

This paper discusses a new approach for investigating the seismic wave velocity of rock, specifically carbonates, as affected by their pore structures. While the conventional routine of seismic velocity measurement highly depends on the extensive laboratory experiment, the proposed approach utilizes the digital rock physics view which lies on the numerical experiment. Thus, instead of using core sample, we use the thin section image of carbonate rock to measure the effective seismic wave velocity when travelling on it. In the numerical experiment, thin section images act as the medium on which wave propagation will be simulated. For the modeling, an advanced technique based on artificial neural network was employed for building the velocity and density profile, replacing image's RGB pixel value with the seismic velocity and density of each rock constituent. Then, ultrasonic wave was simulated to propagate in the thin section image by using finite difference time domain method, based on assumption of an acoustic-isotropic medium. Effective velocities were drawn from the recorded signal and being compared to the velocity modeling from Wyllie time average model and Kuster-Toksoz rock physics model. To perform the modeling, image analysis routines were undertaken for quantifying the pore aspect ratio that is assumed to represent the rocks pore structure. In addition, porosity and mineral fraction required for velocity modeling were also quantified by using integrated neural network and image analysis technique. It was found that the Kuster-Toksoz gives the closer prediction to the measured velocity as compared to the Wyllie time average model. We also conclude that Wyllie time average that does not incorporate the pore structure parameter deviates significantly for samples having more than 40% porosity. Utilizing this approach we found a good agreement between numerical experiment and theoretically derived rock physics model for estimating the effective seismic wave

Robust Model Predictive Control of a Wind Turbine

DEFF Research Database (Denmark)

Mirzaei, Mahmood; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

2012-01-01

In this work the problem of robust model predictive control (robust MPC) of a wind turbine in the full load region is considered. A minimax robust MPC approach is used to tackle the problem. Nonlinear dynamics of the wind turbine are derived by combining blade element momentum (BEM) theory...... of the uncertain system is employed and a norm-bounded uncertainty model is used to formulate a minimax model predictive control. The resulting optimization problem is simplified by semidefinite relaxation and the controller obtained is applied on a full complexity, high fidelity wind turbine model. Finally...... and first principle modeling of the turbine flexible structure. Thereafter the nonlinear model is linearized using Taylor series expansion around system operating points. Operating points are determined by effective wind speed and an extended Kalman filter (EKF) is employed to estimate this. In addition...

Outlier robustness for wind turbine extrapolated extreme loads

DEFF Research Database (Denmark)

Natarajan, Anand; Verelst, David Robert

2012-01-01

. Stochastic identification of numerical artifacts in simulated loads is demonstrated using the method of principal component analysis. The extrapolation methodology is made robust to outliers through a weighted loads approach, whereby the eigenvalues of the correlation matrix obtained using the loads with its...

PET functional volume delineation: a robustness and repeatability study

International Nuclear Information System (INIS)

Hatt, Mathieu; Cheze-le Rest, Catherine; Albarghach, Nidal; Pradier, Olivier; Visvikis, Dimitris

2011-01-01

Current state-of-the-art algorithms for functional uptake volume segmentation in PET imaging consist of threshold-based approaches, whose parameters often require specific optimization for a given scanner and associated reconstruction algorithms. Different advanced image segmentation approaches previously proposed and extensively validated, such as among others fuzzy C-means (FCM) clustering, or fuzzy locally adaptive bayesian (FLAB) algorithm have the potential to improve the robustness of functional uptake volume measurements. The objective of this study was to investigate robustness and repeatability with respect to various scanner models, reconstruction algorithms and acquisition conditions. Robustness was evaluated using a series of IEC phantom acquisitions carried out on different PET/CT scanners (Philips Gemini and Gemini Time-of-Flight, Siemens Biograph and GE Discovery LS) with their associated reconstruction algorithms (RAMLA, TF MLEM, OSEM). A range of acquisition parameters (contrast, duration) and reconstruction parameters (voxel size) were considered for each scanner model, and the repeatability of each method was evaluated on simulated and clinical tumours and compared to manual delineation. For all the scanner models, acquisition parameters and reconstruction algorithms considered, the FLAB algorithm demonstrated higher robustness in delineation of the spheres with low mean errors (10%) and variability (5%), with respect to threshold-based methodologies and FCM. The repeatability provided by all segmentation algorithms considered was very high with a negligible variability of <5% in comparison to that associated with manual delineation (5-35%). The use of advanced image segmentation algorithms may not only allow high accuracy as previously demonstrated, but also provide a robust and repeatable tool to aid physicians as an initial guess in determining functional volumes in PET. (orig.)

Rock Physical Interpretation of the Relationship between Dynamic and Static Young's Moduli of Sedimentary Rocks

Science.gov (United States)

Takahashi, T.

2017-12-01

The static Young's modulus (deformability) of a rock is indispensable for designing and constructing tunnels, dams and underground caverns in civil engineering. Static Young's modulus which is an elastic modulus at large strain level is usually obtained with the laboratory tests of rock cores sampled in boreholes drilled in a rock mass. A deformability model of the entire rock mass is then built by extrapolating the measurements based on a rock mass classification obtained in geological site characterization. However, model-building using data obtained from a limited number of boreholes in the rock mass, especially a complex rock mass, may cause problems in the accuracy and reliability of the model. On the other hand, dynamic Young's modulus which is the modulus at small strain level can be obtained from seismic velocity. If dynamic Young's modulus can be rationally converted to static one, a seismic velocity model by the seismic method can be effectively used to build a deformability model of the rock mass. In this study, we have, therefore, developed a rock physics model (Mavko et al., 2009) to estimate static Young's modulus from dynamic one for sedimentary rocks. The rock physics model has been generally applied to seismic properties at small strain level. In the proposed model, however, the sandy shale model, one of rock physics models, is extended for modeling the static Young's modulus at large strain level by incorporating the mixture of frictional and frictionless grain contacts into the Hertz-Mindlin model. The proposed model is verified through its application to the dynamic Young's moduli derived from well log velocities and static Young's moduli measured in the tri-axial compression tests of rock cores sampled in the same borehole as the logs were acquired. This application proves that the proposed rock physics model can be possibly used to estimate static Young's modulus (deformability) which is required in many types of civil engineering applications

A simple and robust approach to immobilization of antibody fragments.

Science.gov (United States)

Ikonomova, Svetlana P; He, Ziming; Karlsson, Amy J

2016-08-01

Antibody fragments, such as the single-chain variable fragment (scFv), have much potential in research and diagnostics because of their antigen-binding ability similar to a full-sized antibody and their ease of production in microorganisms. Some applications of antibody fragments require immobilization on a surface, and we have established a simple immobilization method that is based on the biotin-streptavidin interaction and does not require a separate purification step. We genetically fused two biotinylation tags-the biotin carboxyl carrier protein (BCCP) or the AviTag minimal sequence-to six different scFvs (scFv13R4, scFvD10, scFv26-10, scFv3, scFv5, and scFv12) for site-specific biotinylation in vivo by endogenous biotin ligases produced by Escherichia coli. The biotinylated scFvs were immobilized onto streptavidin-coated plates directly from cell lysates, and immobilization was detected through enzyme-linked immunosorbent assays. All scFvs fusions were successfully immobilized, and scFvs biotinylated via the BCCP tag tended to immobilize better than those biotinylated via the AviTag, even when biotinylation efficiency was improved with the biotin ligase BirA. The ability of immobilized scFvs to bind antigens was confirmed using scFv13R4 and scFvD10 with their respective targets β-galactosidase and bacteriophage lambda head protein D (gpD). The immobilized scFv13R4 bound to β-galactosidase at the same level for both biotinylation tags when the surface was saturated with the scFv, and immobilized scFvs retained their functionality for at least 100days after immobilization. The simplicity and robustness of our method make it a promising approach for future applications that require antibody fragment immobilization. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of Hydrothermal Alteration on Rock Properties in Active Geothermal Setting

Science.gov (United States)

Mikisek, P.; Bignall, G.; Sepulveda, F.; Sass, I.

2012-04-01

Hydrothermal alteration records the physical-chemical changes of rock and mineral phases caused by the interaction of hot fluids and wall rock, which can impact effective permeability, porosity, thermal parameters, rock strength and other rock properties. In this project, an experimental approach has been used to investigate the effects of hydrothermal alteration on rock properties. A rock property database of contrastingly altered rock types and intensities has been established. The database details horizontal and vertical permeability, porosity, density, thermal conductivity and thermal heat capacity for ~300 drill core samples from wells THM12, THM13, THM14, THM17, THM18, THM22 and TH18 in the Wairakei-Tauhara geothermal system (New Zealand), which has been compared with observed hydrothermal alteration type, rank and intensity obtained from XRD analysis and optical microscopy. Samples were selected from clay-altered tuff and intercalated siltstones of the Huka Falls Formation, which acts as a cap rock at Wairakei-Tauhara, and tuffaceous sandstones of the Waiora Formation, which is a primary reservoir-hosting unit for lateral and vertical fluid flows in the geothermal system. The Huka Falls Formation exhibits argillic-type alteration of varying intensity, while underlying Waiora Formations exhibits argillic- and propylithic-type alteration. We plan to use a tempered triaxial test cell at hydrothermal temperatures (up to 200°C) and pressures typical of geothermal conditions, to simulate hot (thermal) fluid percolation through the rock matrix of an inferred "reservoir". Compressibility data will be obtained under a range of operating (simulation reservoir) conditions, in a series of multiple week to month-long experiments that will monitor change in permeability and rock strength accompanying advancing hydrothermal alteration intensity caused by the hot brine interacting with the rock matrix. We suggest, our work will provide new baseline information concerning

Observation Quality Control with a Robust Ensemble Kalman Filter

KAUST Repository

Roh, Soojin

2013-12-01

Current ensemble-based Kalman filter (EnKF) algorithms are not robust to gross observation errors caused by technical or human errors during the data collection process. In this paper, the authors consider two types of gross observational errors, additive statistical outliers and innovation outliers, and introduce a method to make EnKF robust to gross observation errors. Using both a one-dimensional linear system of dynamics and a 40-variable Lorenz model, the performance of the proposed robust ensemble Kalman filter (REnKF) was tested and it was found that the new approach greatly improves the performance of the filter in the presence of gross observation errors and leads to only a modest loss of accuracy with clean, outlier-free, observations.

Observation Quality Control with a Robust Ensemble Kalman Filter

KAUST Repository

Roh, Soojin; Genton, Marc G.; Jun, Mikyoung; Szunyogh, Istvan; Hoteit, Ibrahim

2013-01-01

Current ensemble-based Kalman filter (EnKF) algorithms are not robust to gross observation errors caused by technical or human errors during the data collection process. In this paper, the authors consider two types of gross observational errors, additive statistical outliers and innovation outliers, and introduce a method to make EnKF robust to gross observation errors. Using both a one-dimensional linear system of dynamics and a 40-variable Lorenz model, the performance of the proposed robust ensemble Kalman filter (REnKF) was tested and it was found that the new approach greatly improves the performance of the filter in the presence of gross observation errors and leads to only a modest loss of accuracy with clean, outlier-free, observations.

Stability, gain, and robustness in quantum feedback networks

International Nuclear Information System (INIS)

D'Helon, C.; James, M. R.

2006-01-01

In this paper we are concerned with the problem of stability for quantum feedback networks. We demonstrate in the context of quantum optics how stability of quantum feedback networks can be guaranteed using only simple gain inequalities for network components and algebraic relationships determined by the network. Quantum feedback networks are shown to be stable if the loop gain is less than one--this is an extension of the famous small gain theorem of classical control theory. We illustrate the simplicity and power of the small gain approach with applications to important problems of robust stability and robust stabilization

Sparse coding for flexible, robust 3D facial-expression synthesis.

Science.gov (United States)

Lin, Yuxu; Song, Mingli; Quynh, Dao Thi Phuong; He, Ying; Chen, Chun

2012-01-01

Computer animation researchers have been extensively investigating 3D facial-expression synthesis for decades. However, flexible, robust production of realistic 3D facial expressions is still technically challenging. A proposed modeling framework applies sparse coding to synthesize 3D expressive faces, using specified coefficients or expression examples. It also robustly recovers facial expressions from noisy and incomplete data. This approach can synthesize higher-quality expressions in less time than the state-of-the-art techniques.

Reduced conservatism in stability robustness bounds by state transformation

Science.gov (United States)

Yedavalli, R. K.; Liang, Z.

1986-01-01

This note addresses the issue of 'conservatism' in the time domain stability robustness bounds obtained by the Liapunov approach. A state transformation is employed to improve the upper bounds on the linear time-varying perturbation of an asymptotically stable linear time-invariant system for robust stability. This improvement is due to the variance of the conservatism of the Liapunov approach with respect to the basis of the vector space in which the Liapunov function is constructed. Improved bounds are obtained, using a transformation, on elemental and vector norms of perturbations (i.e., structured perturbations) as well as on a matrix norm of perturbations (i.e., unstructured perturbations). For the case of a diagonal transformation, an algorithm is proposed to find the 'optimal' transformation. Several examples are presented to illustrate the proposed analysis.

Robust Parameter Coordination for Multidisciplinary Design

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

This paper introduced a robust parameter coordination method to analyze parameter uncertainties so as to predict conflicts and coordinate parameters in multidisciplinary design. The proposed method is based on constraints network, which gives a formulated model to analyze the coupling effects between design variables and product specifications. In this model, interval boxes are adopted to describe the uncertainty of design parameters quantitatively to enhance the design robustness. To solve this constraint network model, a general consistent algorithm framework is designed and implemented with interval arithmetic and the genetic algorithm, which can deal with both algebraic and ordinary differential equations. With the help of this method, designers could infer the consistent solution space from the given specifications. A case study involving the design of a bogie dumping system demonstrates the usefulness of this approach.

On the relation between flexibility analysis and robust optimization for linear systems

KAUST Repository

Zhang, Qi; Grossmann, Ignacio E.; Lima, Ricardo

2016-01-01

Flexibility analysis and robust optimization are two approaches to solving optimization problems under uncertainty that share some fundamental concepts, such as the use of polyhedral uncertainty sets and the worst-case approach to guarantee

Robust optimal control design using a differential game approach for open-loop linear quadratic descriptor systems

NARCIS (Netherlands)

Musthofa, M.W.; Salmah, S.; Engwerda, Jacob; Suparwanto, A.

This paper studies the robust optimal control problem for descriptor systems. We applied differential game theory to solve the disturbance attenuation problem. The robust control problem was converted into a reduced ordinary zero-sum game. Within a linear quadratic setting, we solved the problem for

Model Uncertainty and Robustness: A Computational Framework for Multimodel Analysis

Science.gov (United States)

Young, Cristobal; Holsteen, Katherine

2017-01-01

Model uncertainty is pervasive in social science. A key question is how robust empirical results are to sensible changes in model specification. We present a new approach and applied statistical software for computational multimodel analysis. Our approach proceeds in two steps: First, we estimate the modeling distribution of estimates across all…

Reliability and Robustness Evaluation of Timber Structures

DEFF Research Database (Denmark)

Cizmar, Dean; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning

In the last few decades there have been intensely research concerning reliability of timber structures. This is primarily because there is an increased focus on society on sustainability and environmental aspects. Modern timber as a building material is also being competitive compared to concrete...... and steel. However, reliability models applied to timber were always related to individual components but not the systems. as any real structure is a complex system, system behaviour must be of a particular interest. In the chapter 1 of this document an overview of stochastic models for strength and loads...... (deterministic, probabilistic and risk based approaches) of the robustness are given. Chapter 3 deals more detailed with the robustness of timber structures....

The Rock Cycle

Science.gov (United States)

Singh, Raman J.; Bushee, Jonathan

1977-01-01

Presents a rock cycle diagram suitable for use at the secondary or introductory college levels which separates rocks formed on and below the surface, includes organic materials, and separates products from processes. (SL)

Water-rock interaction in a high-FeO olivine rock in nature

International Nuclear Information System (INIS)

Hellmuth, K.H.; Lindberg, A.; Tullborg, E.L.

1992-12-01

The long-term behaviour in nature of high-FeO olivine rock in contact with surface water has been studied at the Lovasjaervi instrusion, SE-Finland. The rock has been proposed as a high-capasity, higly reactive redox-buffer backfill in a repository for spent fuel. Favourable groundwater chemistry is a major parameter relevant to safety of such a repository. Reducing conditions favour the retardation of long-lived, redox-sensitive radionuclides. Weathering influences have been studied at the natural outcrop of the rock mass. The interaction of oxidizing surface waters with rock at greater depths has been studied by using fissure filling minerals. Investigation of weathered rock from the outcrop indicates that the olivine rock is highly reactive on a geological time scale and its redox capasity is available although the instrusion as a whole is surprisingly well preserved. The fissure fillings studied allow the conclusion that oxygen seems to be efficiently removed from intruding surface water. Oxidation seem to have caused visible effects only along very conducting fractures and near the contact zones of the surrounding granitic rock. Stable isotope data of fissure filling calcites indicate that the influence of surface waters can be traced clearly down to a depth of about 50 m, but also at greater depths re-equilibration has occurred. Groundwater data from the site were not available. (orig.)

Cecal bacterial communities in wild Japanese rock ptarmigans and captive Svalbard rock ptarmigans.

Science.gov (United States)

Ushida, Kazunari; Segawa, Takahiro; Tsuchida, Sayaka; Murata, Koichi

2016-02-01

Preservation of indigenous gastrointestinal microbiota is deemed to be critical for successful captive breeding of endangered wild animals, yet its biology is poorly understood. Here, we investigated cecal bacterial communities in wild Japanese rock ptarmigans (Lagopus muta japonica) and compared them with those in Svalbard rock ptarmigans (L. m. hyperborea) in captivity. Ultra-deep sequencing of 16S rRNA gene indicated that the community structure of cecal microbiota in wild rock ptarmigans was remarkably different from that in captive Svalbard rock ptarmigans. Fundamental differences between bacterial communities in the two groups of birds were detected at the phylum level. Firmicutes, Actinobacteria, Bacteroidetes and Synergistetes were the major phyla detected in wild Japanese rock ptarmigans, whereas Firmicutes alone occupied more than 80% of abundance in captive Svalbard rock ptarmigans. Furthermore, unclassified genera of Coriobacteriaceae, Synergistaceae, Bacteroidaceae, Actinomycetaceae, Veillonellaceae and Clostridiales were the major taxa detected in wild individuals, whereas in zoo-reared birds, major genera were Ruminococcus, Blautia, Faecalibacterium and Akkermansia. Zoo-reared birds seemed to lack almost all rock ptarmigan-specific bacteria in their intestine, which may explain the relatively high rate of pathogenic infections affecting them. We show evidence that preservation and reconstitution of indigenous cecal microflora are critical for successful ex situ conservation and future re-introduction plan for the Japanese rock ptarmigan.

Scale and size effects in dynamic fracture of concretes and rocks

Directory of Open Access Journals (Sweden)

Petrov Y.

2015-01-01

Full Text Available Structural-temporal approach based on the notion of incubation time is used for interpretation of strain-rate effects in the fracture process of concretes and rocks. It is established that temporal dependences of concretes and rocks are calculated by the incubation time criterion. Experimentally observed different relations between ultimate stresses of concrete and mortar in static and dynamic conditions are explained. It is obtained that compressive strength of mortar at a low strain rate is greater than that of concrete, but at a high strain rate the opposite is true. Influence of confinement pressure on the mechanism of dynamic strength for concretes and rocks is discussed. Both size effect and scale effect for concrete and rocks samples subjected to impact loading are analyzed. Statistical nature of a size effect contrasts to a scale effect that is related to the definition of a spatio-temporal representative volume determining the fracture event on the given scale level.

Rock engineering in Finland

Energy Technology Data Exchange (ETDEWEB)

1986-01-01

Contains a large collection of short articles concerned with tunnels and underground caverns and their construction and use. The articles are grouped under the following headings: use of the subsurface space; water supply; waste water services; energy management (includes articles on power stations, district heating and oil storage and an article on coal storage); multipurpose tunnels; waste disposal; transport; shelters; sporting and recreational amenities located in rock caverns; storage facilities; industrial, laboratory, and service facilities; rock foundations; tourism and culture; utilization of rock masses; research on the disposal of nuclear waste; training and research in the field of rock engineering; site investigation techniques; design of structures in rock; construction; the environment and occupational safety; modern equipment technology; underground space in Helsinki.

Digital Rock Simulation of Flow in Carbonate Samples

Science.gov (United States)

Klemin, D.; Andersen, M.

2014-12-01

Reservoir engineering has becomes more complex to deal with current challenges, so core analysts must understand and model pore geometries and fluid behaviors at pores scales more rapidly and realistically. We introduce an industry-unique direct hydrodynamic pore flow simulator that operates on pore geometries from digital rock models obtained using microCT or 3D scanning electron microscope (SEM) images. The PVT and rheological models used in the simulator represent real reservoir fluids. Fluid-solid interactions are introduced using distributed micro-scale wetting properties. The simulator uses density functional approach applied for hydrodynamics of complex systems. This talk covers selected applications of the simulator. We performed microCT scanning of six different carbonate rock samples from homogeneous limestones to vuggy carbonates. From these, we constructed digital rock models representing pore geometries for the simulator. We simulated nonreactive tracer flow in all six digital models using a digital fluid description that included a passive tracer solution. During the simulation, we evaluated the composition of the effluent. Results of tracer flow simulations corresponded well with experimental data of nonreactive tracer floods for the same carbonate rock types. This simulation data of the non-reactive tracer flow can be used to calculate the volume of the rock accessible by the fluid, which can be further used to predict response of a porous medium to a reactive fluid. The described digital core analysis workflow provides a basis for a wide variety of activities, including input to design acidizing jobs and evaluating treatment efficiency and EOR economics. Digital rock multiphase flow simulations of a scanned carbonate rock evaluated the effect of wettability on flow properties. Various wetting properties were tested: slightly oil wet, slightly water wet, and water wet. Steady-state relative permeability simulations yielded curves for all three

Robustness of public choice models of voting behavior

Directory of Open Access Journals (Sweden)

Mihai UNGUREANU

2013-05-01

Full Text Available Modern economics modeling practice involves highly unrealistic assumptions. Since testing such models is not always an easy enterprise, researchers face the problem of determining whether a result is dependent (or not on the unrealistic details of the model. A solution for this problem is conducting robustness analysis. In its classical form, robustness analysis is a non-empirical method of confirmation – it raises our trust in a given result by implying it with from several different models. In this paper I argue that robustness analysis could be thought as a method of post-empirical failure. This form of robustness analysis involves assigning guilt for the empirical failure to a certain part of the model. Starting from this notion of robustness, I analyze a case of empirical failure from public choice theory or the economic approach of politics. Using the fundamental methodological principles of neoclassical economics, the first model of voting behavior implied that almost no one would vote. This was clearly an empirical failure. Public choice scholars faced the problem of either restraining the domain of their discipline or giving up to some of their neoclassical methodological features. The second solution was chosen and several different models of voting behavior were built. I will treat these models as a case for performing robustness analysis and I will determine which assumption from the original model is guilty for the empirical failure.

Robust nonfullerene solar cells approaching unity external quantum efficiency enabled by suppression of geminate recombination.

Science.gov (United States)

Baran, Derya; Gasparini, Nicola; Wadsworth, Andrew; Tan, Ching Hong; Wehbe, Nimer; Song, Xin; Hamid, Zeinab; Zhang, Weimin; Neophytou, Marios; Kirchartz, Thomas; Brabec, Christoph J; Durrant, James R; McCulloch, Iain

2018-05-25

Nonfullerene solar cells have increased their efficiencies up to 13%, yet quantum efficiencies are still limited to 80%. Here we report efficient nonfullerene solar cells with quantum efficiencies approaching unity. This is achieved with overlapping absorption bands of donor and acceptor that increases the photon absorption strength in the range from about 570 to 700 nm, thus, almost all incident photons are absorbed in the active layer. The charges generated are found to dissociate with negligible geminate recombination losses resulting in a short-circuit current density of 20 mA cm -2 along with open-circuit voltages >1 V, which is remarkable for a 1.6 eV bandgap system. Most importantly, the unique nano-morphology of the donor:acceptor blend results in a substantially improved stability under illumination. Understanding the efficient charge separation in nonfullerene acceptors can pave the way to robust and recombination-free organic solar cells.

Robust nonfullerene solar cells approaching unity external quantum efficiency enabled by suppression of geminate recombination

KAUST Repository

Baran, Derya

2018-05-21

Nonfullerene solar cells have increased their efficiencies up to 13%, yet quantum efficiencies are still limited to 80%. Here we report efficient nonfullerene solar cells with quantum efficiencies approaching unity. This is achieved with overlapping absorption bands of donor and acceptor that increases the photon absorption strength in the range from about 570 to 700 nm, thus, almost all incident photons are absorbed in the active layer. The charges generated are found to dissociate with negligible geminate recombination losses resulting in a short-circuit current density of 20 mA cm-2 along with open-circuit voltages >1 V, which is remarkable for a 1.6 eV bandgap system. Most importantly, the unique nano-morphology of the donor:acceptor blend results in a substantially improved stability under illumination. Understanding the efficient charge separation in nonfullerene acceptors can pave the way to robust and recombination-free organic solar cells.

Robust nonfullerene solar cells approaching unity external quantum efficiency enabled by suppression of geminate recombination

KAUST Repository

Baran, Derya; Gasparini, Nicola; Wadsworth, Andrew; Tan, Ching Hong; Wehbe, Nimer; Song, Xin; Hamid, Zeinab; Zhang, Weimin; Neophytou, Marios; Kirchartz, Thomas; Brabec, Christoph J.; Durrant, James R.; McCulloch, Iain

2018-01-01

Nonfullerene solar cells have increased their efficiencies up to 13%, yet quantum efficiencies are still limited to 80%. Here we report efficient nonfullerene solar cells with quantum efficiencies approaching unity. This is achieved with overlapping absorption bands of donor and acceptor that increases the photon absorption strength in the range from about 570 to 700 nm, thus, almost all incident photons are absorbed in the active layer. The charges generated are found to dissociate with negligible geminate recombination losses resulting in a short-circuit current density of 20 mA cm-2 along with open-circuit voltages >1 V, which is remarkable for a 1.6 eV bandgap system. Most importantly, the unique nano-morphology of the donor:acceptor blend results in a substantially improved stability under illumination. Understanding the efficient charge separation in nonfullerene acceptors can pave the way to robust and recombination-free organic solar cells.

Designing Dynamic Adaptive Policy Pathways using Many-Objective Robust Decision Making

Science.gov (United States)

Kwakkel, Jan; Haasnoot, Marjolijn

2017-04-01

Dealing with climate risks in water management requires confronting a wide variety of deeply uncertain factors, while navigating a many dimensional space of trade-offs amongst objectives. There is an emerging body of literature on supporting this type of decision problem, under the label of decision making under deep uncertainty. Two approaches within this literature are Many-Objective Robust Decision Making, and Dynamic Adaptive Policy Pathways. In recent work, these approaches have been compared. One of the main conclusions of this comparison was that they are highly complementary. Many-Objective Robust Decision Making is a model based decision support approach, while Dynamic Adaptive Policy Pathways is primarily a conceptual framework for the design of flexible strategies that can be adapted over time in response to how the future is actually unfolding. In this research we explore this complementarity in more detail. Specifically, we demonstrate how Many-Objective Robust Decision Making can be used to design adaptation pathways. We demonstrate this combined approach using a water management problem, in the Netherlands. The water level of Lake IJselmeer, the main fresh water resource of the Netherlands, is currently managed through discharge by gravity. Due to climate change, this won't be possible in the future, unless water levels are changed. Changing the water level has undesirable flood risk and spatial planning consequences. The challenge is to find promising adaptation pathways that balance objectives related to fresh water supply, flood risk, and spatial issues, while accounting for uncertain climatic and land use change. We conclude that the combination of Many-Objective Robust Decision Making and Dynamic Adaptive Policy Pathways is particularly suited for dealing with deeply uncertain climate risks.

Sliding rocks on Racetrack Playa, Death Valley National Park: first observation of rocks in motion.

Directory of Open Access Journals (Sweden)

Richard D Norris

Full Text Available The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved > 60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, "windowpane" ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of -4-5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2-5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice.

New robust statistical procedures for the polytomous logistic regression models.

Science.gov (United States)

Castilla, Elena; Ghosh, Abhik; Martin, Nirian; Pardo, Leandro

2018-05-17

This article derives a new family of estimators, namely the minimum density power divergence estimators, as a robust generalization of the maximum likelihood estimator for the polytomous logistic regression model. Based on these estimators, a family of Wald-type test statistics for linear hypotheses is introduced. Robustness properties of both the proposed estimators and the test statistics are theoretically studied through the classical influence function analysis. Appropriate real life examples are presented to justify the requirement of suitable robust statistical procedures in place of the likelihood based inference for the polytomous logistic regression model. The validity of the theoretical results established in the article are further confirmed empirically through suitable simulation studies. Finally, an approach for the data-driven selection of the robustness tuning parameter is proposed with empirical justifications. © 2018, The International Biometric Society.

A Robust Planning Algorithm for Groups of Entities in Discrete Spaces

Directory of Open Access Journals (Sweden)

Igor Wojnicki

2015-07-01

Full Text Available Automated planning is a well-established field of artificial intelligence (AI, with applications in route finding, robotics and operational research, among others. The task of developing a plan is often solved by finding a path in a graph representing the search domain; a robust plan consists of numerous paths that can be chosen if the execution of the best (optimal one fails. While robust planning for a single entity is rather simple, development of a robust plan for multiple entities in a common environment can lead to combinatorial explosion. This paper proposes a novel hybrid approach, joining heuristic search and the wavefront algorithm to provide a plan featuring robustness in areas where it is needed, while maintaining a low level of computational complexity.

Defining robustness protocols: a method to include and evaluate robustness in clinical plans

International Nuclear Information System (INIS)

McGowan, S E; Albertini, F; Lomax, A J; Thomas, S J

2015-01-01

We aim to define a site-specific robustness protocol to be used during the clinical plan evaluation process. Plan robustness of 16 skull base IMPT plans to systematic range and random set-up errors have been retrospectively and systematically analysed. This was determined by calculating the error-bar dose distribution (ebDD) for all the plans and by defining some metrics used to define protocols aiding the plan assessment. Additionally, an example of how to clinically use the defined robustness database is given whereby a plan with sub-optimal brainstem robustness was identified. The advantage of using different beam arrangements to improve the plan robustness was analysed. Using the ebDD it was found range errors had a smaller effect on dose distribution than the corresponding set-up error in a single fraction, and that organs at risk were most robust to the range errors, whereas the target was more robust to set-up errors. A database was created to aid planners in terms of plan robustness aims in these volumes. This resulted in the definition of site-specific robustness protocols. The use of robustness constraints allowed for the identification of a specific patient that may have benefited from a treatment of greater individuality. A new beam arrangement showed to be preferential when balancing conformality and robustness for this case. The ebDD and error-bar volume histogram proved effective in analysing plan robustness. The process of retrospective analysis could be used to establish site-specific robustness planning protocols in proton therapy. These protocols allow the planner to determine plans that, although delivering a dosimetrically adequate dose distribution, have resulted in sub-optimal robustness to these uncertainties. For these cases the use of different beam start conditions may improve the plan robustness to set-up and range uncertainties. (paper)

Defining robustness protocols: a method to include and evaluate robustness in clinical plans

Science.gov (United States)

McGowan, S. E.; Albertini, F.; Thomas, S. J.; Lomax, A. J.

2015-04-01

We aim to define a site-specific robustness protocol to be used during the clinical plan evaluation process. Plan robustness of 16 skull base IMPT plans to systematic range and random set-up errors have been retrospectively and systematically analysed. This was determined by calculating the error-bar dose distribution (ebDD) for all the plans and by defining some metrics used to define protocols aiding the plan assessment. Additionally, an example of how to clinically use the defined robustness database is given whereby a plan with sub-optimal brainstem robustness was identified. The advantage of using different beam arrangements to improve the plan robustness was analysed. Using the ebDD it was found range errors had a smaller effect on dose distribution than the corresponding set-up error in a single fraction, and that organs at risk were most robust to the range errors, whereas the target was more robust to set-up errors. A database was created to aid planners in terms of plan robustness aims in these volumes. This resulted in the definition of site-specific robustness protocols. The use of robustness constraints allowed for the identification of a specific patient that may have benefited from a treatment of greater individuality. A new beam arrangement showed to be preferential when balancing conformality and robustness for this case. The ebDD and error-bar volume histogram proved effective in analysing plan robustness. The process of retrospective analysis could be used to establish site-specific robustness planning protocols in proton therapy. These protocols allow the planner to determine plans that, although delivering a dosimetrically adequate dose distribution, have resulted in sub-optimal robustness to these uncertainties. For these cases the use of different beam start conditions may improve the plan robustness to set-up and range uncertainties.

Rock stresses (Grimsel rock laboratory)

International Nuclear Information System (INIS)

Pahl, A.; Heusermann, S.; Braeuer, V.; Gloeggler, W.

1989-01-01

On the research and development project 'Rock Stress Measurements' the BGR has developed and tested several test devices and methods at GTS for use in boreholes at a depth of 200 m and has carried out rock mechanical and engineering geological investigations for the evaluation and interpretation of the stress measurements. The first time a computer for data processing was installed in the borehole together with the BGR-probe. Laboratory tests on hollow cylinders were made to study the stress-deformation behavior. To validate and to interprete the measurement results some test methods were modelled using the finite-element method. The dilatometer-tests yielded high values of Young's modulus, whereas laboratory tests showed lower values with a distinct deformation anisotropy. Stress measurements with the BGR-probe yielded horizontal stresses being higher than the theoretical overburden pressure and vertical stresses which agree well with the theoretical overburden pressure. These results are comparable to the results of the hydraulic fracturing tests, whereas stresses obtained with CSIR-triaxial cells are generally lower. The detailed geological mapping of the borehole indicated relationships between stress and geology. With regard to borehole depth different zones of rock structure joint frequency, joint orientation, and orientation of microfissures as well as stress magnitude, stress direction, and degree of deformation anisotropy could be distinguished. (orig./HP) [de

Robust image obfuscation for privacy protection in Web 2.0 applications

Science.gov (United States)

Poller, Andreas; Steinebach, Martin; Liu, Huajian

2012-03-01

We present two approaches to robust image obfuscation based on permutation of image regions and channel intensity modulation. The proposed concept of robust image obfuscation is a step towards end-to-end security in Web 2.0 applications. It helps to protect the privacy of the users against threats caused by internet bots and web applications that extract biometric and other features from images for data-linkage purposes. The approaches described in this paper consider that images uploaded to Web 2.0 applications pass several transformations, such as scaling and JPEG compression, until the receiver downloads them. In contrast to existing approaches, our focus is on usability, therefore the primary goal is not a maximum of security but an acceptable trade-off between security and resulting image quality.

Review on the prevailing methods for the prediction of potential rock burst / rock spalling in tunnels

OpenAIRE

Panthi, Krishna Kanta

2017-01-01

Rock burst / rock spalling is among the prevailing stability challenges, which can be met while tunneling through hard rock mass. Especially, this is very relevant for the mountainous country like Norway where hard rock is dominating and many road, railway and hydropower tunnels have to be aligned deep into the mountain with steep valley slope topography. Tunnels passing beneath deep rock cover (overburden), in general, are subjected to high in-situ stresses. If the rock mass is relatively un...

Synthetic Rock Analogue for Permeability Studies of Rock Salt with Mudstone

Directory of Open Access Journals (Sweden)

Hongwu Yin

2017-09-01

Full Text Available Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock salt is to develop a synthetic analogue to use as a permeability model. To address the permeability of a mudstone/salt layered and mixed rock mass in Jintan, Jiangsu Province, synthetic mixed and layered specimens using the mudstone and the salt were fabricated for permeability testing. Because of the gas “slippage effect”, test results are corrected by the Klinkenberg method, and the permeability of specimens is obtained by regression fitting. The results show that the permeability of synthetic pure rock salt is 6.9 × 10−20 m2, and its porosity is 3.8%. The permeability of synthetic mudstone rock is 2.97 × 10−18 m2, with a porosity 17.8%. These results are close to those obtained from intact natural specimens. We also find that with the same mudstone content, the permeability of mixed specimens is about 40% higher than for the layered specimens, and with an increase in the mudstone content, the Klinkenberg permeability increases for both types of specimens. The permeability and mudstone content have a strong exponential relationship. When the mudstone content is below 40%, the permeability increases only slightly with mudstone content, whereas above this threshold, the permeability increases rapidly with mudstone content. The results of the study are of use in the assessment of the tightness of natural gas storage facilities in mudstone-rich rock salt formations in China.