Limited Number Of Cores Research Articles

Uncertainty quantification of exchange efficiency in membrane-based air-to-air energy exchanger cores: Repetitive manufacturing and experiments

Air-to-air membrane-energy exchangers have been widely used in green buildings as passive energy-recovery technologies for energy conservation and carbon reduction. An air-to-air membrane-energy exchanger conserves building energy by forcing the indoor exhaust air and unconditioned fresh air to exchange heat and moisture. As a critical performance indicator, the energy-exchange efficiency is primarily determined by the core. To improve energy-saving performance, many studies have been conducted to analyze and enhance the efficiency of air-to-air membrane-energy exchanger cores by manufacturing, testing, modeling, and comparing different cores. However, few studies have investigated the uncertainty introduced by the manufacturing and testing processes (most related research only studied the uncertainty of the sensible efficiency), which means that some positive results of those controlled trials are possibly owing to the manufacturing tolerance or testing errors, rather than real technical progress. This study addresses this problem by quantifying the efficiency uncertainty caused by manufacturing and testing processes. Three cores were produced using the same manufacturing process and materials, followed by identical experimental tests on their sensible, latent, and enthalpy efficiencies. Comparison results suggest that even when all variables are controlled, the differential enthalpy efficiency of two “identical” cores still vary from 0 % to 2 %. Variance of repetitive testing results of a certain core can afford an enthalpy efficiency of 4 % owing to a non-ideal experimental procedure. When manufacturing tolerances and experimental errors are considered simultaneously, the differential sensible efficiency among multiple “identical” cores is within 0–5%, whereas latent efficiency data in winter shows a significant variation of 5–10 % for “identical” cores. The contributions and conclusions of this study are as follows. The efficiency uncertainty caused by manufacturing and testing processes is non-negligible, particularly in latent efficiency. This phenomenon could alert researchers and engineers in this field to conduct repetitive manufacturing and testing while trying to modify/test/compare air-to-air membrane-energy exchanger cores. Because this study is based on a limited number of cores, the quantitative results of this study should be considered a non-universal reference, and a systematic benchmark must be established in the future.

SMIwiz: An integrated toolbox for multidimensional seismic modelling and imaging

This paper contributes an open source software - SMIwiz, which integrates seismic modelling, reverse time migration (RTM), and full waveform inversion (FWI) into a unified computer implementation. SMIwiz has the machinery to do both 2D and 3D simulation in a consistent manner. The package features a number of computational recipes for efficient calculation of imaging condition and inversion gradient: a dynamic evolving computing box to limit the simulation cube and a well-designed wavefield reconstruction strategy to reduce the memory consumption when dealing with 3D problems. The modelling in SMIwiz runs independently: each shot corresponds to one processor in a bijective manner to maximize the scalability. A batchwise job scheduling strategy is designed to handle large 3D imaging tasks on computer with limited number of cores. The viability of SMIwiz is demonstrated by a number of applications on benchmark models. Program summaryProgram Title: SMIwizCPC Library link to program files:https://doi.org/10.17632/tygszns27k.1Developer's repository link:https://github.com/yangpl/SMIwizLicensing provisions: GNU General Public License v3.0Programming language: C, Shell, FortranExternal dependencies: MPI [1], FFTW [2]Nature of problem: Seismic modelling and imaging (FWI and RTM)Solution method: High-order finite-difference time-domain (FDTD) for modelling on staggered grid; Quasi-Newton LBFGS algorithm for nonlinear optimization; line search to estimate step length based on Wolfe condition References[1]https://www.mpich.org/[2]http://fftw.org/

Study Regarding the Evaluation of Prediction Models for Determining the Concrete Compressive Strength Using Non-Destructive Testing (NDT) Data: Validation Stage

In the evaluation of an existing reinforced concrete structure, a fundamental issue is determining the concrete compressive strength as accurately as possible. This process can be conducted by using destructive and non-destructive methods. The destructive method presumes a limited number of cores extracted from the concrete structure. A higher number of cores would affect the structural safety and is time and resource consuming. Therefore, the conclusions drawn using exclusively this method can also generate errors in correctly estimating the load bearing capacity of a structure, thus leading to the possibility of implementing deficient measures in order to ensure a structural safety. Data obtained via non-destructive methods are more comprehensive. Due to their non-destructive nature, there are no limitations regarding the number of elements investigated and are fast in delivering results. One of the main concerns of researchers in this field is developing a direct relationship between the measured indicators through non-destructive testing (NDT) methods and concrete compressive strength. Over the years different equations with different mathematical structure (linear, polynomial, power, exponential and logarithmic) were developed with the main purpose of delivering fast and accurate results concerning concrete compressive strength by the means of NDT. The aim of this paper is to validate some of the most important prediction models using an original set of data. The database consists in a number of 96 concrete cores that were subjected to Ultrasonic Pulse Velocity (UPV) and Schmidt Rebound Hammer (SRH) testing. The accuracy of the results was determined by using two statistical parameters the mean absolute error (MAE) and mean absolute percentage error (MAPE). The proposed equations have been analyzed in terms of prediction and dispersion of values. It was noticed that some of the formulations predict values that are higher than the ones obtained destructively, others provide a larger dissipation of values, while some equations deliver a compact distribution of results with higher rate in terms of accuracy. This study proposes a data validation of some of the most popular empirical equations, used for the estimation of the concrete compressive strength, elaborated through the years, using a new set of data.

Evaluating offshore sediment resources for non-traditional coastal restoration projects

Open coast beach-dune environments are vulnerable to erosion, due to storms, lack of sediment, or coastal squeeze; however, they serve important societal and ecological functions. Backbarrier shorelines are also susceptible to erosion, often due to tidal currents or boat wakes. Beach erosion is often mitigated using offshore, upland, or channel sediment resources for restoration projects. However, dune restorations generally use upland mine sediments and backbarrier restorations typically use sediments dredged from channels. Offshore resources are not often considered for dune or backbarrier shoreline restoration. However, because the geotechnical properties suitable for dunes and backbarriers differ from beach quality sediment, offshore sediments may provide an alternative source for restoration of lower-energy environments without adversely impacting the available volume of sediment needed for beach nourishment. This study presents an approach to evaluate sediment borrow area for suitability in non-traditional coastal restoration projects (i.e., dune and backbarrier shorelines). Kriging interpolation provided a better estimation of volume than using a linear average method based on comparison with simulated models of known volumes and should be used when a limited number of cores are available. The volume of sediment suitable for dune or backbarrier placement based on a case study in Palm Beach County, FL was much lower than the volume of beach compatible sands, suggesting that other regions require exploration for potential use in low-energy environments.

Enhancing Matrix Multiplication With a Monolithic 3-D-Based Scratchpad Memory

Convolutional neural networks (CNNs) are one of the most popular machine learning algorithms. The convolutional layers, which account for the most execution time of CNNs, are implemented with matrix multiplication because the convolution operation performs dot products between filters and local regions of the input. On the other hand, GPUs with thousands of cores were proven to significantly accelerate matrix multiplication, compared to CPUs with a limited number of cores, especially for large matrices. However, the current memory architecture allows only one row access at a time so that multiple accesses are necessary to read the column data of the second matrix, thus slowing down matrix multiplication. In this study, we adopt the monolithic 3-D integration for the GPU scratchpad memory, called monolithic 3-D integration (M3D) scratchpad memory (SPM), to enhance matrix multiplication. The M3D SPM allows one access to read the column data of the second matrix, similar to the case of the first matrix. The simulation results show that our M3D SPM improves the system performance by 46.3% for the 32×32 matrix multiplication, over the conventional 2-D SPM where the column data of the second matrix are read sequentially.

Staggered parallel short-time Fourier transform

In this paper, we present the staggered parallel short-time Fourier transform, an algorithm that uses a quasi-parallel procedure to compute exact STFT coefficients of 1D signals. The algorithm leverages parallelism with the capacity of feedforward STFT algorithms to re-use prior computations. It performs this by carefully organizing input signals and collecting past computations into 2D memory buffers. Re-using stored information in memory enables fast computation of up to N/2 FFTs in parallel. The algorithm's time complexity is at O[6T] under an abstract circuit implementation – achieving a complexity measure that is independent of sample complexity N. Its time complexity is asymptotically equivalent with the best possible exact algorithm of O[T] time complexity, with a constant efficiency at O[1] relative to the best known sequential algorithm. Its efficiency property holds whether in an abstract circuit implementation or in a CPU implementation with limited number of cores. In general, the algorithm consumes less processors than other parallel STFT algorithms but can potentially require more memory. To test the algorithm's properties, we implement several STFT algorithms in a CPU with varying numbers of cores. These algorithms use either FFT, iterative, or feedforward schemes to capture the range of existing STFT algorithms for comparison. From our experimental results, our proposed algorithm has the least running time among exact STFT algorithms, while consuming less CPU processors than other forms of parallel implementations.

Improvement of nondestructive assessment of on-site concrete strength: Influence of the selection process of cores location on the assessment quality for single and combined NDT techniques

For existing constructions, there is a need to estimate the concrete mechanical strength for a more accurate evaluation of their structural capacity. The destructive evaluation of strength by coring is expensive, sometimes technically difficult and it may be impossible in some situations and the evaluation is limited to a restricted surface of the structure. Non-destructive testing (NDT) in conjunction with destructive testing by coring (DT) offers an interesting alternative for the strength assessment of concrete in existing buildings. For a reliable assessment of concrete strength, it is necessary to fully master the calibration quality of the conversion models between DT and NDT used for strength estimation. Because of technical and economic constraints, the professional practice is frequently based on a very limited number of cores. If this optimal number is not reached, the risk is high that the resulting conversion model is not reliable. This practical context, in which the common number of cores is small, forces to review the calibration procedure in order to take care of the relevance of the identified model. The procedure using conditional coring, which is based on the selection of critical locations of cores after an analysis of NDT test results, is the subject of methodological developments presented in this paper. Our research works aims at analyzing this issue on a broad investigation program by NDT (Rebound Hammer and Ultrasonic Pulse Velocity) and coring realized on the structural elements (columns and beams) of an existing building. 205 data triplets (core strengths and NDT test results) are used to carry out this study. The thorough statistical data analysis allows quantifying the potential interest of the conditional coring compared to the random coring with two measurement strategies of NDT (by using single or combined methods).

Protocol for FWD Data Collection at Network-Level Pavement Management in Iran

The objective of this study was to develop an approach for incorporating techniques used to interpret and evaluate deflection data for network-level pavement management system applications. A national pavement management system is being developed in Iran and the use of falling weight deflectometers (FWDs) at the network level was deemed necessary to compensate for the lack of vital construction history data in the pavement inventory. Because FWD measurements disrupt traffic flow and are a potential safety hazard, it is imperative to increase the interval between FWD testing points as much as possible to allow scanning of the entire 51,000 km network of freeways, highways, and major roads in a reasonable time span with the least traffic disruption. A project-level dataset at 0.2 km intervals in different environments and diverse traffic categories was selected for analysis. In addition, data from continuous ground-penetrating radar was collected concurrently and compared with a limited number of cores. The overall analysis included evaluation of interval variation, segmentation, the structural condition index (SCI), and layer moduli calculated using the AASHTO and ELMOD methods. The analysis was done to determine the optimum interval between test points. Analysis showed that the collection intervals could be increased from 0.2 to 0.6 km. Subsequently, the applicability and time efficiency of the network-level intervals were verified by calculating overlay thickness and time required.

Prediction of concrete strength by non-destructive testing in old structures: Effect of core number on the reliability of prediction

When assessing the quality of concrete on site, it is necessary to base the interpretation on reliable and representative test results. Generally, core tests are the most reliable and effective method for assessing the quality of concrete. Unfortunately, this type of testing is expensive and time consuming and only a limited number of cores can be carried out in practice. Non-destructive tests (NDT) can be used to overcome these drawbacks. The most popular and widely used NDT methods for assessing concrete strength are rebound hammer (RH) and the ultrasonic pulse velocity (UPV). The use of these methods provide unreliable predictions unless their results are correlated to destructive tests. A sufficient number of cores is needed to accurately predict the compressive strength of concrete. Recent researches have been carried out for identifying and optimizing the number of cores able to stabilize the calibration model on data from recent structures and from synthetic data. However, more case studies are needed to draw conclusions. In addition, the effect of the degradation of reinforced concrete elements on the number of cores needed for obtaining a reliable prediction needs to be investigated. In this paper, RH and UPV in conjunction with core tests are used to evaluate the concrete compressive strength in existing structures built in the 1970s and degraded mainly by steel corrosion. More than 234 elements were tested by RH and 86 elements by UPV. Also, 36 cores were drilled and tested under compression. A regression analysis is adopted to establish the correlations between NDT and strength measurements. The accuracy of the predictive assessment was evaluated using two indicators: the root mean square error (RMSE) and the coefficient of determination (r 2 ). The results of this case study showed that seven to nine cores is the minimal number of cores that guarantees the improvement of concrete strength assessment by combined or single NDT methods.

Prediction of concrete strength by non-destructive testing in old structures: Effect of core number on the reliability of prediction

When assessing the quality of concrete on site, it is necessary to base the interpretation on reliable and representative test results. Generally, core tests are the most reliable and effective method for assessing the quality of concrete. Unfortunately, this type of testing is expensive and time consuming and only a limited number of cores can be carried out in practice. Non-destructive tests (NDT) can be used to overcome these drawbacks. The most popular and widely used NDT methods for assessing concrete strength are rebound hammer (RH) and the ultrasonic pulse velocity (UPV). The use of these methods provide unreliable predictions unless their results are correlated to destructive tests. A sufficient number of cores is needed to accurately predict the compressive strength of concrete. Recent researches have been carried out for identifying and optimizing the number of cores able to stabilize the calibration model on data from recent structures and from synthetic data. However, more case studies are needed to draw conclusions. In addition, the effect of the degradation of reinforced concrete elements on the number of cores needed for obtaining a reliable prediction needs to be investigated. In this paper, RH and UPV in conjunction with core tests are used to evaluate the concrete compressive strength in existing structures built in the 1970s and degraded mainly by steel corrosion. More than 234 elements were tested by RH and 86 elements by UPV. Also, 36 cores were drilled and tested under compression. A regression analysis is adopted to establish the correlations between NDT and strength measurements. The accuracy of the predictive assessment was evaluated using two indicators: the root mean square error (RMSE) and the coefficient of determination (r2). The results of this case study showed that seven to nine cores is the minimal number of cores that guarantees the improvement of concrete strength assessment by combined or single NDT methods.

Using sequence stratigraphic approaches in a highly tectonic area: Case study – Nubia (A) sandstone in southwestern Gulf of Suez, Egypt

West Esh El Mallaha area is located west of the Hurghada shoreline. It pertains to the southwestern province of the Gulf of Suez. Nubia (A) sandstone is one of the prolific reservoirs in the western side along the Gulf of Suez area. To enhance further oil production and to develop this reservoir, it is important to gain a clear understanding of the reservoir in terms of its depositional origin. In west Esh El Mallaha area, the understanding of the depositional setting of Nubia (A) is relatively hard due to the limited number of cores.A comprehensive workflow which integrates all geological datasets (electrical logs pattern, the high resolution biostratigraphic analysis, and previous studies) which has been performed for the Nubia (A), enables to recognize different patterns of electrical logs, which are used to define the sequence stratigraphy and systems tracts for Nubia (A). The Lower Nubia (A) is characterized by fining-upward profile and well-developed coarsening-straight profile interpreted as a braided – fluvial facies (lowstand system tract). On the other hand, the upper Nubia (A) is characterized by fining-upward, coarsening-upward, and bell profile interpreted as meandering fluvial to fluvio-dominated delta (transgressive system tract).This study is an approach to build a reliable geological model, and give wide view to evaluate and develop the reservoir in the drilled areas and predict sand distribution in the undrilled areas despite the limited number of cores.

Non-destructive strength evaluation of concrete: Analysis of some key factors using synthetic simulations

Non-destructive techniques (NDT) like rebound hammer (RH) and ultrasonic pulse velocity (UPV) are widely used in conjunction with destructive techniques (core tests) for assessing the concrete strength in existing buildings. The methodology consists in fitting regression models between NDT techniques and destructive tests on a limited number of cores. The quality of the model is affected by many influencing factors such as: the number of cores, the quality of NDT measurements, the variability in concrete strength, the existence and magnitude of possible uncontrolled factors (like saturation rate) and the combination of techniques. In this paper, the effects of these factors are studied using a synthetic simulation approach in order to well understand them and consequently to develop a methodology for improving the quality of strength assessment. In order to assess the quality of fitted model and its ability to estimate strength, RMSE and r2 errors are calculated and it is found that the calculation of r2 alone may give misleading indication since r2 is very sensitive to the scattering of the explanatory variable. Another important result of the present study is that there is a critical minimal number of cores which makes the combination efficient while for a lower number the use of single technique is preferable. This number depends on the qualities of the two techniques to be combined.

Accuracy of MRI-Targeted in-Bore Prostate Biopsy According to the Gleason Score with Postprostatectomy Histopathologic Control—a Targeted Biopsy-Only Strategy with Limited Number of Cores

Accuracy of ultrasound-guided biopsy and Gleason score is limited, and diagnosis of insignificant cancer with Gleason score ≤6 is frequent when extended biopsy schemes are used. We evaluated whether the magnetic resonance imaging (MRI)-targeted in-bore prostate biopsy correctly identifies the Gleason score of prostate cancer in histopathologic correlation after prostatectomy. Simultaneously a targeted concept is expected to keep down the rate of insignificant cancer. We compared retrospectively the Gleason score of the MRI-targeted in-bore biopsy with prostatectomy specimens in 50 men with prostate cancer. Endorectal MRI included T2-weighted imaging, diffusion-weighted imaging, dynamic contrast-enhanced imaging, and spectroscopy. Lesions with a prostate imaging-reporting and data system (PI-RADS) score ≥3 were considered. Upgrading and downgrading of tumors was evaluated, and significant upgrading was defined as a shift in Gleason score from 6 to 7 or more. Gleason score was concordant in 66% of the patients, overall upgraded in 30% of patients, and downgraded in 4% of patients. Significant upgrading of the Gleason score from 6 to 7 occurred in eight patients; upgrading did not exceed one step in the Gleason score. After prostatectomy the Gleason score 6 was found in 20% of patients. The median number of cores obtained was 4 (range 2-6), and the median number of positive cores was 2 (range 1-4). In-bore MRI-targeted biopsy offers good accuracy in the Gleason score with postprostatectomy histopathologic control when compared to the literature. A limited number of cores are sufficient to achieve these results. The fraction of insignificant cancer identified by targeted only-biopsy is low. Upgrading is restricted to one step in the Gleason score. Clinicians should be aware of positive findings in MRI and the biopsy technique used when assessing prostate biopsy results.

Erratum to: Assessing concrete strength with rebound hammer: review of key issues and ideas for more reliable conclusions

On site concrete strength assessment via non-destructive techniques (NDT) is one of the main challenges that NDT is faced with. Along the past 50 years a huge number of both laboratory and onsite experimental programs have been carried out and a variety of models have been proposed in order to correlate concrete strength with rebound hammer measurements. It is commonly agreed that none of these models is able to accurately predict the concrete strength with enough accuracy for using the assessed value for further structural computations. The large variety of concrete compositions and the fact that other influent factors may exist are the major arguments advance in order to explain the failure of modeling and assessment strategies. Based on (a) an in-depth literature review enabling a meta-analysis of existing models and, (b) Monte-Carlo simulations used to simulate what happens when rebound measurements are carried on onsite, and used to assess the concrete strength after a calibration stage, we will point first the previously unnoticed consistency between existing models. This consistency will be then explained by the trade-off which exists between the unknown model parameters that must be identified. In the context of real measurements, i.e., those concerning heterogeneous materials with uncontrolled factors and error measurements, it will be shown that this trade-off systematically exists. This fact is inherent to any inverse or identification problem. Its magnitude depends on several factors, among which the quality of the NDT measurement and the number of control cores used for model calibration play a key role. Its consequences are (a) a limited ability to assess strength and, (b) the impossibility to use the model in different context. Some proposals are finally presented in order to obtain a more robust assessment for the concrete strength. They combine guidelines about the measurement error estimation, a calibration approach which will be less dependent on the information provided by a limited number of cores, and the combination of several measurements in order to reduce the effect of uncontrolled factors.

Sedimentary architecture of a low-accumulation shelf since the Late Pleistocene (NW Iberia)

Continental shelves represent areas of highest economical and ecological importance. Nevertheless, these sedimentary systems remain poorly understood due to a complex interplay of various factors and processes which results in highly individual construction schemes. Previous studies of sedimentary shelf systems have mainly focused on a limited number of cores, retrieved from Holocene fine-grained depocentres. As such, the relation between shelf architecture and sedimentary history remains largely obscure. Here, we present new data from the NW Iberian shelf comprising shallow-seismic profiles, a large number of sediment cores, and an extended set of radiocarbon dates to reveal the Late Quaternary evolution of a low-accumulation shelf system in detail. On the NW Iberian shelf, three main seismic units are identified. These overly a prominent erosional unconformity on top of the basement. The lowermost Unit 1 is composed of maximal 75-m thick, Late Tertiary to Pleistocene deposits. The youngest sediments of this unit are related to the last glacial sea-level fall. Unit 2 was controlled by the deglacial sea-level rise and shows a maximum thickness of 15 m. Finally, Unit 3 comprises deposits related to the late stage of sea-level rise and the modern sea-level highstand with a thickness of 4 m in mid-shelf position. Two pronounced seismic reflectors separate these main units from each other. Their origin is related to (1) exposure and ravinement processes during lower sea level, and (2) to reworking and re-deposition of coarse sediments during subsequent sea-level rise. According to the sediment core ground-truthing, sediments of the Late Tertiary to Pleistocene unit predominantly display homogenous fine sands with exceptional occurrences of palaeosols that indicate an ancient exposure surface. Fine sands which were deposited in the run of the last sea-level rise show a time-transgressive retrogradational development. The seismic reflectors, bounding the individual units, appear in the cores as 0.1 to 1-m thick deposits consisting either of shell gravels or siliceous coarse sands with gravels. The modern sea-level highstand stage is characterised by zonal deposition of mud forming a mud belt in mid-shelf position, and sediment starvation on outer shelf zones. Radiocarbon ages indicate that this mud belt was the main depocentre for river-supplied fine material on the NW Iberian shelf at least over the past 5.32 ka BP. The initial onset of this depocentre is proposed to be related to a shift in the balance between rate of sea-level rise and amount of terrigenous sediment supply. Various other stratigraphical shelf reconstructions reveal analogies in architecture which indicate that timing and shaping of the individual units on low-accumulation shelves is fundamentally controlled by eustatic sea-level changes. Other factors of local importance such as differential elevation of the basement and the presence of morphological barriers formed by rocky outcrops on the seafloor have additionally modifying influence on the sedimentary processes.

Using Scanning Lasers to Determine the Thickness of Concrete Pavement

Due to limited budgets and reduced inspection staff, state departments of transportation are in need of innovative approaches for providing more efficient quality assurance on concrete paving projects. In Iowa, the current technique is to take core samples of the pavement, which is a labor intensive, destructive process. Due to these limitations, a limited number of cores are used to estimate the pavement thickness. Any method that can reduce or eliminate cores and increase the statistical accuracy of the thickness estimate will be beneficial. One method, which uses a laser to scan the surface of the base prior to paving and then to scan the surface after paving can determine the thickness at any point. Also, scanning lasers provide thorough data coverage that can be used to calculate thickness variance accurately and identify any areas where the thickness is below tolerance. The laser scanning methodology for this study involved the following: (1) investigating characteristics of the paving process; (2) using a laser scanner on three different sites; (3) processing the data to create clean surface models; (4) performing statistical analyses to determine thickness variability; and (5) summarizing the results.

Comparison of Contrast Enhanced Color Doppler Targeted Biopsy to Conventional Systematic Biopsy: Impact on Gleason Score

Prostate cancer grading with Gleason score is an important prognostic factor. This prospective randomized study compares ultrasound systematic biopsy vs contrast enhanced color Doppler targeted biopsy for the impact on Gleason score findings. We examined 690 men (mean age 56 years, range 41 to 77) with a serum total prostate specific antigen of 1.25 ng/ml or greater, a free-to-total prostate specific antigen ratio less than 18% and/or a suspicious digital rectal examination. Contrast enhanced color Doppler targeted biopsies with a limited number of cores (5 or less) were performed in hypervascular areas of the peripheral zone during administration of the ultrasound contrast agent Sonovuetrade mark (Bracco, Milano, Italy). Ten systematic biopsies were obtained in a standard spatial distribution. Cancer detection rates and Gleason score were compared. Prostate cancer was identified in 221 of 690 subjects (32%) with a mean prostate specific antigen of 4.6 ng/ml (range 1.4 to 35.0). Prostate cancer was detected in 180 of 690 subjects (26%) with contrast enhanced color Doppler targeted biopsy and in 166 of 690 patients (24%) with systematic ultrasound biopsy. The Gleason score of all 180 cancers detected on contrast enhanced color Doppler targeted biopsy was 6 or higher (mean 6.8). The Gleason score of all 166 cancers detected on systematic biopsy ranged from 4 to 6 and mean Gleason score was 5.4. Contrast enhanced color Doppler targeted biopsy detected significantly higher Gleason scores compared to systematic biopsy (Wilcoxon rank sum test p <0.003). Contrast enhanced color Doppler targeted biopsy detected cancers with higher Gleason scores and more cancer than systematic biopsy. Therefore, contrast enhanced color Doppler seems to be helpful in the grading of prostate cancer, which is important for defining prognosis and deciding treatment.

Integrated core-log petrofacies analysis in the construction of a reservoir geomodel: A case study of a mature Mississippian carbonate reservoir using limited data

Small independent operators produce most of the Mississippian carbonate fields in the United States mid-continent, where a lack of integrated characterization studies precludes maximization of hydrocarbon recovery. This study uses integrative techniques to leverage extant data in an Osagian and Meramecian (Mississippian) cherty carbonate reservoir in Kansas. Available data include petrophysical logs of varying vintages, limited number of cores, and production histories from each well. A consistent set of assumptions were used to extract well-level porosity and initial saturations, from logs of different types and vintages, to build a geomodel. Lacking regularly recorded well shut-in pressures, an iterative technique, based on material balance formulations, was used to estimate average reservoir-pressure decline that matched available drillstem test data and validated log-analysis assumptions.Core plugs representing the principal reservoir petrofacies provide critical inputs for characterization and simulation studies. However, assigning plugs among multiple reservoir petrofacies is difficult in complex (carbonate) reservoirs. In a bottom-up approach, raw capillary pressure (Pc) data were plotted on the Super-Pickett plot, and log- and core-derived saturation-height distributions were reconciled to group plugs by facies, to identify core plugs representative of the principal reservoir facies, and to discriminate facies in the logged interval. Pc data from representative core plugs were used for effective pay evaluation to estimate water cut from completions, in infill and producing wells, and guide-selective perforations for economic exploitation of mature fields.The results from this study were used to drill 22 infill wells. Techniques demonstrated here can be applied in other fields and reservoirs.

Evaluation of New Nonnuclear Pavement Density Gauges with Data from Field Projects

The introduction of new devices to measure pavement density requires an evaluation method that is both accurate and fair. Evaluations are commonly done by taking a density measurement with the gauge and comparing this density to the density obtained from a core taken at the same location. This approach must meet two requirements; first, enough cores must be taken at each location to make the comparisons meaningful, and second, evaluation of these devices must be done with as many projects in as many locations as possible to account for all materials used in pavement construction. Unfortunately, given the difficulties in obtaining field cores, large numbers of cores that can be used for evaluations are not available from all projects. Therefore, any evaluation of density gauges must balance rigor with practicality. The correlation coefficient was selected to evaluate the new nonnuclear pavement density gauge. However, because only a limited number of cores are available at each site for development of the correlation coefficient, this parameter by itself cannot be used to evaluate the new gauge. Instead, results from side-by-side comparisons with the accepted nuclear density gauge were used to aid in the evaluation of the new density-measuring device. It was concluded, on the basis of data from 76 projects in six different states, that the proposed nonnuclear density gauge must be further developed before it can be used to determine pavement density. In its current form, the densities obtained with the device do not correlate with the measured densities to the same degree that the densities measured with existing devices do. Use of this nonnuclear device will introduce more uncertainty in pavement density measurements than that which already exists.

Patterns of sedimentation from polydispersed turbidity currents

Particle-driven gravity currents, as exemplified by either turbidity currents in the ocean or ignimbrite flows in the atmosphere, are buoyancy-driven flows due to the suspension of dense particles in an ambient fluid. They are formed naturally from sediment-laden outflows from rivers into coastal waters, from submarine landslides along coastal shelves or as the result of volcanic eruptions. The porous rock and sand of both consolidated and unconsolidated oil-reservoirs are often derived from the sediment deposited from turbidity currents over geological time. A knowledge of the genesis of these reservoirs may provide better methods to estimate their porosity and permeability distribution, which would improve evaluation and management of these valuable resources. This paper presents a theoretical model for the dynamics and deposition of a two-dimensional particle-driven gravity current composed of a polydispersed suspension of dense particles and compares the theoretical predictions against data obtained from laboratory experiments. After developing a scaling anal­ysis of the governing equations, we propose a simple algebraic method to compute the areal density of deposit, or mass deposited per unit area, and the distribution of particle-sizes within deposits arising from either two-dimensional or axisymmetric currents. The resulting formulae suggest an inverse method to estimate the density of deposit and the distribution of particle sizes as a function of position in a reservoir from a limited number of cores.