bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ascertainment of the Archetype Statistical Method for Incident Rate Forecasting Through Forecast Performance Evaluations
Authors: York Jason C. , Gernand Jeremy M. 
Published: March 2016

The potential benefits of a safety program are generally, only realized after an incident has occurred. Resource allocation in an organization’s safety program has the imperative task of balancing costs and often unrealized benefits. Management can be wary to allocate additional resources to a safety program because it is difficult to estimate the return on investment, especially since the returns are a set of negative outcomes not manifested.
One way that safety professionals can provide an estimate of potential return on investment is to forecast how the organizations incident rate can be affected by implementing the different resource allocation strategies, and what the expectation for the incident rate would have been without intervention. Safety professionals often trend the performance of their organization’s safety program by benchmarking incident rates against other organizations. Previous studies have employed different statistical forecasting methods to predict how incident rates will react to changes in resource allocation.
This paper analyzes the performance of four statistical forecasting methods employed in previous resource allocation studies along another statistical forecasting method, never before used for incident rate prediction, to ascertain the method that provides the highest level of forecast accuracy. By identifying the most accurate forecasting method, the uncertainty of which method a safety professional should utilize for incident rate prediction is reduced. Incident data from the Mine Safety and Health Administration (MSHA) Part 50, was used to forecast both short and long term incident rates. The performance of each of these forecasting methods were evaluated against one another to determine which method has the highest level of accuracy, lowest bias, and best complexity-adjusted goodness-of-fit metrics.
Evaluation of the performance provides indications that the double exponential smoothing statistical forecasting method can provide the most accurate incident rate predictions. Analysis of forecast bias indicated that the error for the double exponential smoothing method is unbiased, within the acceptable range for tracking signal, and had a level of prediction accuracy above 70%. The results of this observational study indicate that the double exponential smoothing method should be the method to consider for incident rate prediction. Consistent use of the same forecasting methodology amongst safety professionals as part of their safety program’s resource allocation process, will allow for more consistent benchmarking of incident rate prediction.
Combustion-Driven Oscillation Mitigation in Large Industrial Combustors
Authors: Kashani Reza 
Published: March 2016

Thermoacoustic instability has been reported in various combustion systems including industrial combustors (heaters, boilers, etc.), propulsion systems (rockets, afterburners) and gas turbine combustors. Thermoacoustic instability can be addressed by adding acoustic damping to the combustion environment. In larger industrial applications, tonal acoustic damping solutions such as quarter wave tubes and/or Helmholtz resonators or even active acoustic damping solutions can be used to quiet this instability.
This paper discusses the numerical investigation of mitigating the 30 Hz thermoacoustic instability in a fire-tube 600 horsepower steam boiler. By conducting finite element analysis of the acoustics of the combustion chamber and all the fire-tubes, the 30 Hz mode sympathizing with the heat release dynamics of the chamber is identified. Subsequently, a number of tuned acoustic absorption solutions are experimented with, numerically (on the finite element model of the boiler’s acoustics), and the most suitable (in terms of effectiveness and ease of implementation) candidate solution is identified. Currently, work is underway to implement this solution on the boiler.
3D CFD Analysis of a Twin Screw Expander With Different Real Gas Models for R245fa
Authors: Papes Iva , Abdelli Lazhar , Degroote Joris , Vierendeels Jan 
Published: March 2016

With the increasing importance of minimizing primary energy usage and complying with emission restrictions, a significant interest has been developed towards waste heat recovery from industrial processes. A large portion of this energy is available at low temperatures (350K–400K) but it can be relatively efficiently converted into mechanical power using an Organic Rankine Cycle (ORC). Twin screw expanders can be used as an alternative to turbines with their cheap production costs and well proven efficiencies. In this paper, 3D CFD simulations of a twin screw expander using R245fa as the working fluid are performed.
Since the fluid properties show big deviations when using the ideal gas equation of state (EoS), the flow problem has been evaluated using different real gas models. Thermodynamic parameters for the ideal gas EoS, the cubic Aungier Redlich-Kwong EoS and the CoolProp fluid database (open source) were compared in a preliminary study. After that, the models have been included through user-defined functions (UDFs) in ANSYS Fluent and were tested on 3D CFD calculations of a twin screw expander and a simplified expansion model.
Several performance indicators such as mass flow rates, pressure-volume diagrams and power output are used to compare different fluid models for R245fa. From the results of this study, it can be concluded that the ideal gas EoS shows big deviations going closer to the saturation vapor line and the deviation in power comparing to the Aungier Redlich-Kwong EoS is around 8%. Conversely, the Aungier Redlich-Kwong EoS and the CoolProp database present very similar results for this case.
Numerical and Experimental Study of Flow Phenomenon Inside Gas Ejectors With Moist Gases Entrainment
Authors: Wang Yuping , Pellerin Mark , Mohanty Pravansu , Sengupta Subrata 
Published: March 2016

Gas ejectors can be found in a wide range of applications such as refrigeration and thrust augmentation. This paper focuses on the study of an ejector used in applications where moist gases are being entrained. In the first part of this work, the gas flow characteristics inside an ejector, as well as the ejector’s performance under various operating and geometric configurations, were studied with a three-dimensional computational model, which was validated against measurement data.
In the second part, focus was given to the potential condensation or de-sublimation phenomena that may occur inside an ejector when water vapor is included in the entrained stream. An experiment using light-attenuation method was performed to verify the presence of a second phase, then the onset of phase change and the phase distribution were obtained numerically. A two-dimensional axis-symmetric model was developed based on the model used in the first part. A series of simulations were performed with various amounts of water vapor added into the entrained flow. It was found that both frost particles and water condensate could form inside the mixing tube depending on the operating conditions and water vapor concentrations. When the concentration exceeds 3%, water vapor could condense throughout the mixing tube. Some preliminary results of the second phase particles formed, e.g. critical sizes and distributions, were also obtained to assist with the design and optimization of gas ejectors used in similar applications.
Sensitivity Evaluation of the AGR 3-4 Experiment Thermal Model Irradiated in the Advanced Test Reactor
Authors: Hawkes Grant L. , Sterbentz James W. , Pham Binh T. 
Published: March 2016

A temperature sensitivity evaluation has been performed on a thermal model for the AGR-3/4 fuel experiment on an individual capsule. The experiment was irradiated in the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL). Four TRISO fuel irradiation experiments are planned for the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program which supports the development of the Very High Temperature Gas-cooled Reactor under the Next-Generation Nuclear Plant project.
AGR-3/4 is the third TRISO-particle fuel test of the four planned and is intended to test tri-structural-isotropic (TRISO)-coated, low-enriched uranium oxy-carbide fuel. The AGR-3/4 test was specifically designed to assess fission product transport through various graphite materials. The AGR-3/4 irradiation test in the ATR started in December 2011 and finished in April 2014. Forty-eight (48) TRISO-particle fueled compacts were inserted into 12 separate capsules for the experiment (four compacts per capsule).
The purpose of this analysis was to assess the sensitivity of input variables for the capsule thermal model. A series of cases were compared to a base case by varying different input parameters into the ABAQUS finite element thermal model. These input parameters were varied by ±10% to show the temperature sensitivity to each parameter. The most sensitive parameter was the compact heat rates, followed by the outer control gap distance and neon gas fraction. Thermal conductivity of the compacts and thermal conductivity of the various graphite layers vary with fast neutron fluence and exhibited moderate sensitivity. The least sensitive parameters were the emissivities of the stainless steel and graphite, along with gamma heat rate in the non-fueled components. Separate sensitivity calculations were performed varying with fast neutron fluence, showing a general temperature rise with an increase in fast neutron fluence. This is a result of the control gas gap becoming larger due to the graphite shrinkage with neutron damage. A smaller sensitivity is due to the thermal conductivity of the fuel compacts with fast neutron fluence.
Heat rates and fast neutron fluence were input from a detailed physics analysis using the Monte Carlo N-Particle (MCNP) code. Individual heat rates for each non-fuel component were input as well. A steady-state thermal analysis was performed for each sensitivity calculation. ATR outer shim control cylinders and neck shim rods along with driver fuel power and fuel depletion were incorporated into the physics heat rate calculations. Surface-to-surface radiation heat transfer along with conduction heat transfer through the gas mixture of helium-neon (used for temperature control) was used in the sensitivity calculations.
Optical Flow Measurement of Cavitation in a Converging-Diverging Nozzle Using High-Speed Imagery
Authors: Duong Alan 
Published: March 2016

Cavitation is a phenomenon where liquids will vaporize when subjected to low pressures. Essentially, the pressure is reduced sufficiently such that the liquid boils at the given temperature. The highest pressure at which cavitation could occur is called the vapor pressure. However, the pressure associated with the onset of cavitation could be lower than the vapor pressure. This indicates the liquid exists under a meta-stable condition.
The current research is investigating different aspects of cavitation and cavitating flow characteristics. Particle tracking using high-speed photography provided further insight as to what the velocity profile of cavitating flow may resemble. The research has shown that the cavitation that occurred in the current nozzle appears to have a laminar velocity profile. In the experiments that were conducted, it was also observed that as the back pressure of the downstream decreased, the volumetric flow rate would increase. However, a maximum volumetric flow rate was measured once the flow had begun cavitation regardless of the back pressure. This indicated that choked flow conditions likely exist within the nozzle. Choked flow within the nozzle indicates that near the region of the throat the fluid velocity has reached the speed of sound. Using high-speed photography, visualization of flow separation and recirculation was recorded.
The information obtained from the research provides a more detailed description of the velocity profile near the onset of cavitation. The main objectives of this research were to obtain measurements of the overall flow for support of on-going research and analysis of nozzle flow cavitation. This study will provide a foundation for further and more detailed research into cavitation phenomena.
Comparison of three dimensional strain volume reconstructions using SOUPR and wobbler based acquisitions: A phantom study
Authors: Yang Wenjun , Ingle Atul , Varghese Tomy 
Published: March 2016

Purpose:Ultrasound strain imaging is a relatively low cost and portable modality for monitoring percutaneous thermal ablation of liver neoplasms. However, a 3D strain volume reconstruction from existing 2D strain images is necessary to fully delineate the thermal dose distribution. Tissue mimicking (TM) phantom experiments were performed to validate a novel volume reconstruction algorithm referred to as sheaf of ultrasound planes reconstruction (SOUPR), based on a series of 2D rotational imaging planes.Methods:Reconstruction using SOUPR was formulated as an optimization problem with constraints on data consistency with 2D strain images and data smoothness of the volume data. Reconstructed ablation inclusion dimensions, volume, and elastographic signal to noise ratio (SNRe) and contrast to noise ratio (CNRe) were compared with conventional 3D ultrasound strain imaging based on interpolating a series of quasiparallel 2D strain images with a wobbler transducer.Results:Volume estimates of the phantom inclusion were in a similar range for both acquisition approaches. SNRe and CNRe obtained with SOUPR were significantly higher on the order of 250% and 166%, respectively. The mean error of the inclusion dimension reconstructed with a wobbler transducer was on the order of 10.4%, 3.5%, and 19.0% along the X, Y, and Z axes, respectively, while the error with SOUPR was on the order of 2.6%, 2.8%, and 9.6%. A qualitative comparison of SOUPR and wobbler reconstruction was also performed using a thermally ablated region created in ex vivo bovine liver tissue.Conclusions:The authors have demonstrated using experimental evaluations with a TM phantom that the reconstruction results obtained with SOUPR were superior when compared with a conventional wobbler transducer in terms of inclusion shape preservation and detectability.
New Small Plasmid Harboring
bla
KPC-2
in Pseudomonas aeruginosa
Authors: Galetti Renata , Andrade Leonardo Neves , Chandler Michael , Varani Alessandro de Mello , Darini Ana Lúcia Costa 
Published: March 2016

ABSTRACT

The aim of this study was to characterize the genetic context of
bla
KPC-2
in
Pseudomonas aeruginosa
sequence type 244 from Brazil. The
bla
KPC-2
gene was detected in a new small plasmid, pBH6. Complete sequencing revealed that pBH6 was 3,652 bp long and included the Tn
3
resolvase and Tn
3
inverted repeat (IR), a partial copy of IS
Kpn6
, and a putative
ori
region but no
rep
genes. pBH6 replicated stably into
Escherichia coli
strain DH10B and
P. aeruginosa
strain PAO.
Distribution and Relationships of Antimicrobial Resistance Determinants among Extended-Spectrum-Cephalosporin-Resistant or Carbapenem-Resistant Escherichia coli Isolates from Rivers and Sewage Treatment Plants in India
Authors: Akiba Masato , Sekizuka Tsuyoshi , Yamashita Akifumi , Kuroda Makoto , Fujii Yuki , Murata Misato , Lee Ken-ichi , Joshua Derrick Ian , Balakrishna Keshava , Bairy Indira , Subramanian Kaushik , Krishnan Padma , Munuswamy Natesan , Sinha Ravindra K. , Iwata Taketoshi , Kusumoto Masahiro , Guruge Keerthi S. 
Published: March 2016

ABSTRACT

To determine the distribution and relationship of antimicrobial resistance determinants among extended-spectrum-cephalosporin (ESC)-resistant or carbapenem-resistant
Escherichia coli
isolates from the aquatic environment in India, water samples were collected from rivers or sewage treatment plants in five Indian states. A total of 446
E. coli
isolates were randomly obtained. Resistance to ESC and/or carbapenem was observed in 169 (37.9%)
E. coli
isolates, which were further analyzed. These isolates showed resistance to numerous antimicrobials; more than half of the isolates exhibited resistance to eight or more antimicrobials. The
bla
NDM
gene was detected in 14/21 carbapenem-resistant
E. coli
isolates:
bla
NDM-1
in 2 isolates,
bla
NDM-5
in 7 isolates, and
bla
NDM-7
in 5 isolates. The
bla
CTX-M
gene was detected in 112 isolates (66.3%):
bla
CTX-M-15
in 108 isolates and
bla
CTX-M-55
in 4 isolates. We extracted 49 plasmids from selected isolates, and their whole-genome sequences were determined. Fifty resistance genes were detected, and 11 different combinations of replicon types were observed among the 49 plasmids. The network analysis results suggested that the plasmids sharing replicon types tended to form a community, which is based on the predicted gene similarity among the plasmids. Four communities each containing from 4 to 17 plasmids were observed. Three of the four communities contained plasmids detected in different Indian states, suggesting that the interstate dissemination of ancestor plasmids has already occurred. Comparison of the DNA sequences of the
bla
NDM
-positive plasmids detected in this study with known sequences of related plasmids suggested that various mutation events facilitated the evolution of the plasmids and that plasmids with similar genetic backgrounds have widely disseminated in India.
Evaluation of Drug-Drug Interactions between Direct-Acting Anti-Hepatitis C Virus Combination Regimens and the HIV-1 Antiretroviral Agents Raltegravir, Tenofovir, Emtricitabine, Efavirenz, and Rilpivirine
Authors: Khatri Amit , Dutta Sandeep , Dunbar Martin , Podsadecki Thomas , Trinh Roger , Awni Walid , Menon Rajeev 
Published: March 2016

ABSTRACT

The three direct-acting antiviral agent (3D) regimen is a novel combination of direct-acting antiviral agents (DAAs) that has proven effective for the treatment of hepatitis C virus (HCV) infection. Given the potential for coadministration in patients with human immunodeficiency virus infection, possible drug interactions with antiretroviral drugs must be carefully considered. Four phase 1, multiple-dose pharmacokinetic studies were conducted in healthy volunteers (
n
= 66). The 3D regimen of 150/100 mg daily paritaprevir/ritonavir, 25 mg daily ombitasvir, and 400 mg twice-daily dasabuvir was administered alone or in combination with 200 mg daily of emtricitabine and 300 mg daily of tenofovir disoproxil fumarate (tenofovir DF), 25 mg daily of rilpivirine, or 400 mg of raltegravir twice daily. A 2-DAA regimen of 150/100 mg daily paritaprevir/ritonavir and 400 mg of dasabuvir twice daily was also studied in combination with efavirenz/emtricitabine/tenofovir DF at 600/200/300 mg daily, respectively (Atripla; Bristol-Myers Squibb). Pharmacokinetic parameters were determined from plasma drug concentrations. No clinically significant drug interactions were observed (≤32% change in exposure) between the 3D regimen and that of emtricitabine plus tenofovir DF. Raltegravir exposure was increased up to 134% when the drug was coadministered with the 3D regimen. Although coadministration with rilpivirine was well tolerated in healthy volunteers, observed elevations in rilpivirine exposures may increase the potential for adverse drug reactions. Concomitant use of the 2-DAA regimen and efavirenz/emtricitabine/tenofovir DF was discontinued owing to poor tolerability and adverse events. No dose adjustment is required during coadministration of raltegravir, tenofovir DF, or emtricitabine with the 3D regimen. Rilpivirine is not recommended and efavirenz is contraindicated for coadministration with the 3D regimen.
A PhoPQ-Regulated ABC Transporter System Exports Tetracycline in Pseudomonas aeruginosa
Authors: Chen Lin , Duan Kangmin 
Published: March 2016

ABSTRACT

Pseudomonas aeruginosa
is an important human pathogen whose infections are difficult to treat due to its high intrinsic resistance to many antibiotics. Here, we show that the disruption of PA4456, encoding the ATP binding component of a putative ATP-binding cassette (ABC) transporter, increased the bacterium's susceptible to tetracycline and other antibiotics or toxic chemicals. Fluorescence spectroscopy and antibiotic accumulation tests showed that the interruption of the ABC transporter caused increased intracellular accumulation of tetracycline, demonstrating a role of the ABC transporter in tetracycline expulsion. Site-directed mutagenesis proved that the conserved residues of E170 in the Walker B motif and H203 in the H-loop, which are important for ATP hydrolysis, were essential for the function of PA4456. Through a genome-wide search, the PhoPQ two-component system was identified as a regulator of the computationally predicted PA4456-4452 operon that encodes the ABC transporter system. A >5-fold increase of the expression of this operon was observed in the
phoQ
mutant. The results obtained also show that the expression of the
phzA1B1C1D1E1
operon and the production of pyocyanin were significantly higher in the ABC transporter mutant, signifying a connection between the ABC transporter and pyocyanin production. These results indicated that the PhoPQ-regulated ABC transporter is associated with intrinsic resistance to antibiotics and other adverse compounds in
P. aeruginosa
, probably by extruding them out of the cell.
Structural Basis of the Enhanced Pollutant-Degrading Capabilities of an Engineered Biphenyl Dioxygenase
Authors: Dhindwal Sonali , Gomez-Gil Leticia , Neau David B. , Pham Thi Thanh My , Sylvestre Michel , Eltis Lindsay D. , Bolin Jeffrey T. , Kumar Pravindra 
Published: March 2016

ABSTRACT

Biphenyl dioxygenase, the first enzyme of the biphenyl catabolic pathway, is a major determinant of which polychlorinated biphenyl (PCB) congeners are metabolized by a given bacterial strain. Ongoing efforts aim to engineer BphAE, the oxygenase component of the enzyme, to efficiently transform a wider range of congeners. BphAE
II9
, a variant of BphAE
LB400
in which a seven-residue segment,
335
TFNNIRI
341
, has been replaced by the corresponding segment of BphAE
B356
,
333
GINTIRT
339
, transforms a broader range of PCB congeners than does either BphAE
LB400
or BphAE
B356
, including 2,6-dichlorobiphenyl, 3,3′-dichlorobiphenyl, 4,4′-dichlorobiphenyl, and 2,3,4′-trichlorobiphenyl. To understand the structural basis of the enhanced activity of BphAE
II9
, we have determined the three-dimensional structure of this variant in substrate-free and biphenyl-bound forms. Structural comparison with BphAE
LB400
reveals a flexible active-site mouth and a relaxed substrate binding pocket in BphAE
II9
that allow it to bind different congeners and which could be responsible for the enzyme's altered specificity. Biochemical experiments revealed that BphAE
II9
transformed 2,3,4′-trichlorobiphenyl and 2,2′,5,5′-tetrachlorobiphenyl more efficiently than did BphAE
LB400
and BphAE
B356
. BphAE
II9
also transformed the insecticide dichlorodiphenyltrichloroethane (DDT) more efficiently than did either parental enzyme (apparent
k
cat
/

K
m

of 2.2 ± 0.5 mM
−1
s
−1
, versus 0.9 ± 0.5 mM
−1
s
−1
for BphAE
B356
). Studies of docking of the enzymes with these three substrates provide insight into the structural basis of the different substrate selectivities and regiospecificities of the enzymes.

IMPORTANCE
Biphenyl dioxygenase is the first enzyme of the biphenyl degradation pathway that is involved in the degradation of polychlorinated biphenyls. Attempts have been made to identify the residues that influence the enzyme activity for the range of substrates among various species. In this study, we have done a structural study of one variant of this enzyme that was produced by family shuffling of genes from two different species. Comparison of the structure of this variant with those of the parent enzymes provided an important insight into the molecular basis for the broader substrate preference of this enzyme. The structural and functional details gained in this study can be utilized to further engineer desired enzymatic activity, producing more potent enzymes.