bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Noncancer Pain on Health‐Related Quality of Life
Authors: Lapane Kate L. , Quilliam Brian J. , Benson Carmela , Chow Wing , Kim Myoung S.
Published: February 2014

Background

While the economic costs of pain have been documented, the impact of noncancer pain on quality of life has not been studied extensively.

Objective

To estimate the influence of noncancer pain on quality of life measures.

Design

Prospective, multicenter, observational nonrandomized patient pain registry.

Setting

Outpatient settings.

Participants

Patients with acute episodes of noncancer pain requiring treatment with a prescription medication containing oxycodone immediate‐release on an as‐needed basis for at least 5 days (n = 629).

Measurements

The modified Brief Pain Inventory and the 12‐item Short Form Health Survey (SF‐12) was measured at baseline when oxycodone immediate‐release began and days 7, 14, 21, and 28. Repeated measures mixed models provided estimates of impact of pain on the physical component summary score (PCS) and mental health component summary score (MCS) of the SF‐12.

Results

Patterns indicating pain oscillation over the 28‐day window were common (Range: 44.3% back/neck pain cohort to 61.2% postoperative cohort). After adjustment for sociodemographics, concomitant medications and gastrointestinal symptoms, worst pain in 24 hours was associated with a 13.9 point PCS reduction (adjusted PCS for pain = 10: 31.1; adjusted PCS for pain = 0: 45.0) and a 7.2 point MCS reduction (adjusted MCS for pain = 10: 44.1; adjusted MCS for pain = 0: 51.3). Similar clinically relevant differences were observed among patients with arthritis, back/neck pain, injury/trauma, postoperative pain, neuropathic pain and fibromyalgia, although statistical significance was not observed in the latter 2 groups.

Conclusion

Among outpatients with various underlying causes of pain, the negative impact of pain on physical and mental health‐related quality of life is significant.
Metabolic adaptation to sugar/O2 deficiency for anaerobic germination and seedling growth in rice
Authors: LEE KUO‐WEI , CHEN PENG WEN , YU SU‐MAY
Published: February 2014

Rice is characterized by a broad range of metabolic and morphological adaptations to flooding, such as germination and mobilization of stored nutrients under submergence until seedlings reach the water surface to carry out photosynthesis, and sustainable growth of mature plants for long durations under partial submergence. The underlying mechanisms of the molecular basis of adaptation to anaerobic germination and seedling growth in rice are being uncovered. Induction of an ensemble of hydrolases to mobilize endosperm nutrient reserves is one of the key factors for successful germination and coleoptile elongation in rice under submergence. To compensate for reduced efficiency of Tricarboxylic Acid cycle and oxidative respiration in mitochondria under O2 deficient conditions, α‐amylases play a central role in the hydrolysis of starch to provide sugar substrates for glycolysis and alcohol fermentation for generating ATP. We review the progress on the molecular mechanism regulating α‐amylase expression that involves the integration of signals generated by the hormone gibberellin (GA), sugar starvation and O2 deprivation that results in germination and sustainable seedling growth in rice under anaerobic conditions. Comparisons are also made between dicots and monocots for the molecular mechanism of induction of genes involved in alcohol fermentation and sugar/O2 deficiency sensing system.
Measuring Exposure to Solar Ultraviolet Radiation Using a Dosimetric Technique: Understanding Participant Compliance Issues
Authors: Sun Jiandong , Lucas Robyn M. , Harrison Simone L. , van der Mei Ingrid , Whiteman David C. , Mason Rebecca , Nowak Madeleine , Brodie Alison M. , Kimlin Michael G.
Published: February 2014

Personal ultraviolet dosimeters have been used in epidemiological studies to understand the risks and benefits of individuals' exposure to solar ultraviolet radiation (UVR). We investigated the types and determinants of noncompliance associated with a protocol for use of polysulphone UVR dosimeters. In the AusD Study, 1002 Australian adults (aged 18–75 years) were asked to wear a new dosimeter on their wrist each day for 10 consecutive days to quantify their daily exposure to solar UVR. Of the 10 020 dosimeters distributed, 296 (3%) were not returned or used (Type‐I noncompliance) and other usage errors were reported for 763 (8%) returned dosimeters (Type‐II noncompliance). Type‐I errors were more common in participants with predominantly outdoor occupations. Type‐II errors were reported more frequently on the first day of measurement; weekend days or rainy days; and among females; younger people; more educated participants or those with outdoor occupations. Half (50%) the participants reported a noncompliance error on at least 1 day during the 10‐day period. However, 92% of participants had at least 7 days of usable data without any apparent noncompliance issues. The factors identified should be considered when designing future UVR dosimetry studies.
When tonic cardiac vagal tone predicts changes in phasic vagal tone: The role of fear and perceptual load
Authors: Park Gewnhi , Vasey Michael W. , Van Bavel Jay J. , Thayer Julian F.
Published: February 2014

We examined the relationship between tonic—a correlate of self‐regulatory functioning—and phasic cardiac vagal activity (indexed by heart rate variability; HRV) during a selective attentional task with varying levels of load. Participants detected a target letter among letter strings superimposed on either fearful or neutral face distractors. Letter strings consisted of six target letters under low load and one target letter and five nontarget letters under high load. With fearful distractors, lower tonic HRV was associated with phasic HRV suppression, suggesting an autonomic stress response under both low and high load. In contrast, higher tonic HRV was associated with phasic HRV enhancement, suggesting greater self‐regulatory effort under low load and an absence of phasic HRV suppression under high load. The current research suggests that tonic cardiac vagal tone is associated with the ability to flexibly adapt autonomic responses.
Working for a Good Cause
Authors: Dur Robert , Zoutenbier Robin
Published: February 2014

A rich literature in public administration has shown that public sector employees have stronger altruistic motivations than private sector employees. Recent economic theories stress the importance of mission preferences and predict that altruistic people sort into the public sector when they subscribe to its mission. This article uses data from a representative survey of more than 30,000 employees from 50 countries to test this prediction. The authors find strong evidence of a mutually reinforcing role of altruism and mission alignment in sorting into the public sector, particularly among highly educated workers and among workers in less‐developed countries.
Separate, Unequal, and Ignored? Interjurisdictional Competition and the Budgetary Choices of Poor and Affluent Municipalities
Authors: Jimenez Benedict S.
Published: February 2014

The fundamental value underlying the design of a fragmented system of local governance is consumer sovereignty. This system functions as a market‐like arrangement providing citizen‐consumers a choice of jurisdictions that offer different bundles of public services and taxes. However, the same choice also can facilitate class‐based population sorting, creating regions where fiscally wealthy jurisdictions coexist with impoverished ones. Some argue that the public market enhances the power of all consumers, whether poor or rich. Even if the poor are concentrated in some jurisdictions, they can exercise their voice to ensure that their government responds to their service needs. But does the voice of the poor matter as much as the voice of the rich in determining service levels in the local public market? Comparing the budgetary choices in poor and affluent municipalities, this article shows that in highly fragmented regions, some municipal services are provided the least in communities where they are needed the most.
Stochastic Measures of Network Resilience: Applications to Waterway Commodity Flows
Authors: Baroud Hiba , Ramirez‐Marquez Jose E. , Barker Kash , Rocco Claudio M.
Published: February 2014

Given the ubiquitous nature of infrastructure networks in today's society, there is a global need to understand, quantify, and plan for the resilience of these networks to disruptions. This work defines network resilience along dimensions of reliability, vulnerability, survivability, and recoverability, and quantifies network resilience as a function of component and network performance. The treatment of vulnerability and recoverability as random variables leads to stochastic measures of resilience, including time to total system restoration, time to full system service resilience, and time to a specific α% resilience. Ultimately, a means to optimize network resilience strategies is discussed, primarily through an adaption of the Copeland Score for nonparametric stochastic ranking. The measures of resilience and optimization techniques are applied to inland waterway networks, an important mode in the larger multimodal transportation network upon which we rely for the flow of commodities. We provide a case study analyzing and planning for the resilience of commodity flows along the Mississippi River Navigation System to illustrate the usefulness of the proposed metrics.
Exposure Factors for Wastewater‐Irrigated Asian Vegetables and a Probabilistic Rotavirus Disease Burden Model for Their Consumption
Authors: Mok Hoi‐Fei , Hamilton Andrew J.
Published: February 2014

Many farmers in water‐scarce regions of developing countries use wastewater to irrigate vegetables and other agricultural crops, a practice that may expand with climate change. There are a number of health risks associated with wastewater irrigation for human food crops, particularly with surface irrigation techniques common in the developing world. The World Health Organization (WHO) recommends using quantitative microbial risk assessment (QMRA) to determine if the irrigation scheme meets health standards. However, only a few vegetables have been studied for wastewater risk and little information is known about the disease burden of wastewater‐irrigated vegetable consumption in China. To bridge this knowledge gap, an experiment was conducted to determine volume of water left on Asian vegetables and lettuce after irrigation. One hundred samples each of Chinese chard (Brassica rapa var. chinensis), Chinese broccoli (Brassica oleracea var. alboglabra), Chinese flowering cabbage (Brassica rapa var. parachinensis), and lettuce (Lactuca sativa) were harvested after overhead sprinkler irrigation. Chinese broccoli and flowering cabbage were found to capture the most water and lettuce the least. QMRAs were then constructed to estimate rotavirus disease burden from consumption of wastewater‐irrigated Asian vegetables in Beijing. Results indicate that estimated risks from these reuse scenarios exceed WHO guideline thresholds for acceptable disease burden for wastewater use, signifying that reduction of pathogen concentration or stricter risk management is necessary for safe reuse. Considering the widespread practice of wastewater irrigation for food production, particularly in developing countries, incorporation of water retention factors in QMRAs can reduce uncertainty regarding health risks for consumers worldwide.
Reliability and Validation of the Hebrew Version of the Reasons for Attempting Suicide Questionnaire (RASQ‐H) and its Importance for Mental Pain
Authors: Levinger Shai , Holden Ronald R.
Published: February 2014

This study evaluated the Hebrew Reasons for Attempting Suicide Questionnaire (RASQ‐H) and its application for suicidality, and mental pain and its tolerance. The sample comprised 97 participants who were inpatient suicide attempters, inpatient nonattempters, or nonpatient controls. Differentiation of the RASQ into internal perturbation‐based reasons and extrapunitive/manipulative motivations factors was confirmed, with each scale demonstrating strong internal reliability. While the internal perturbation‐based reasons factor related positively to some suicidal manifestations, to mental pain, and to lower mental pain tolerance, the extrapunitive/manipulative motivations factor mostly associated with lower suicidality and had fewer and smaller associations with mental pain and its tolerance.
Female circumcision in multicultural Singapore: The hidden cut
Authors: Marranci Gabriele
Published: February 2014

In recent years discussion about female genital mutilation (FGM) has expanded and theUNhas recently called for a universal ban of the practice. The practice in Southeast Asia is widespread among Malay Muslims and, although different styles and practices exist, procedures conducted in medical clinics are extremely minor and, according to gynaecological research, have no effect on sexuality due to the clitoris being left totally untouched. One of the states in which Malay Muslims maintain such a tradition is Singapore. Nonetheless, Singapore is rarely mentioned in academic studies or even in reports discussing the ritual. Even inside Singapore, only Malays tend to know of the tradition, while other ethnic groups remain oblivious to the fact that Singapore is among the states that allow such an operation. The present article does not discussFGMper se and avoids contributing to the diatribe about labels and values, although these are, of course, extremely relevant. Instead it focuses on the reasons for the practice remaining hidden and undiscussed in Singapore, so much so that some respondents did not know that they had been circumcised.
Economic evaluation of a hypothetical screening assay for alloimmunization risk among transfused patients with sickle cell disease
Authors: Kacker Seema , Ness Paul M. , Savage William J. , Frick Kevin D. , Shirey R. Sue , King Karen E. , Tobian Aaron A.R.
Published: February 2014

Background

Prophylactic antigen‐matching can reduce alloimmunization rates among chronically transfused patients with sickle cell disease (SCD), but this matching increases costs and may only benefit 30% of patients. We assessed the clinical and financial value of a potential assay for alloimmunization risk that would allow for targeted antigen‐matching.

Study Design and Methods

A Markov‐based model evaluated direct medical costs and alloimmunization events over 10 to 20 years among transfused (simple or exchange) patients with SCD. Four matching strategies were evaluated: prospective matching (for all patients), history‐based matching (only for patients with prior alloimmunization), perfectly informed matching (assay with 100% sensitivity, 100% specificity), and imperfectly informed matching (reduced accuracy). Under all matching protocols, matching included C, E, K, and any additional alloantibodies present. A hospital perspective was adopted, with costs (2012US$) and events discounted (3%).

Results

Perfectly informed antigen‐matching using a $1000 assay is expected to save $82,334 per patient over 10 years, compared to prospective matching. Perfectly informed antigen‐matching is more costly than history‐based matching, but reduces alloimmunization events by 45.6% over 10 years. Averting each alloimmunization event using this strategy would cost an additional $10,934 per patient. Imperfectly informed antigen‐matching using an assay with 75% specificity and 75% sensitivity is less costly than prospective matching, but increases alloimmunization events. Compared to history‐based matching, imperfectly informed matching would decrease alloimmunization events by 32.61%, at an additional cost of $147,915 per patient over 10 years. Cost‐effectiveness of informed antigen‐matching is largely driven by assay specificity.

Conclusions

A sufficiently specific assay to inform antigen‐matching may be cost‐effective in reducing alloimmunization among transfused patients with SCD.
The role of platelets in coagulation dysfunction in xenotransplantation, and therapeutic options
Authors: Iwase Hayato , Ezzelarab Mohamed B. , Ekser Burcin , Cooper David K. C.
Published: February 2014

Xenotransplantation could resolve the increasing discrepancy between the availability of deceased human donor organs and the demand for transplantation. Most advances in this field have resulted from the introduction of genetically engineered pigs, e.g., α1,3‐galactosyltransferase gene‐knockout (GTKO) pigs transgenic for one or more human complement‐regulatory proteins (e.g., CD55, CD46, CD59). Failure of these grafts has not been associated with the classical features of acute humoral xenograft rejection, but with the development of thrombotic microangiopathy in the graft and/or consumptive coagulopathy in the recipient. Although the precise mechanisms of coagulation dysregulation remain unclear, molecular incompatibilities between primate coagulation factors and pig natural anticoagulants exacerbate the thrombotic state within the xenograft vasculature. Platelets play a crucial role in thrombosis and contribute to the coagulation disorder in xenotransplantation. They are therefore important targets if this barrier is to be overcome. Further genetic manipulation of the organ‐source pigs, such as pigs that express one or more coagulation‐regulatory genes (e.g., thrombomodulin, endothelial protein C receptor, tissue factor pathway inhibitor, CD39), is anticipated to inhibit platelet activation and the generation of thrombus. In addition, adjunctive pharmacologic anti‐platelet therapy may be required. The genetic manipulations that are currently being tested are reviewed, as are the potential pharmacologic agents that may prove beneficial.
STEAM: A Mobile Hydraulic System With Engine Integration
Authors: Vukovic Milos , Sgro Sebastian , Murrenhoff Hubertus
Published: February 2014

In recent years, research institutions worldwide have developed a number of new mobile hydraulic systems. Despite their improved energy efficiency, these systems have yet to gain market acceptance due to their related increase in component costs and decrease in robustness. At the Institute for Fluid Power Drives and Controls in Aachen, a new system for mobile machines, named STEAM (Steigerung der Energieeffizienz in der Arbeitshydraulik mobiler Arbeitsmaschinen), is being developed using inexpensive off-the-shelf components. The aim is to improve the total system efficiency by considering all the subsystems in the machine. This is done by integrating the internal combustion engine (ICE) into the hydraulic design process. By using a constant pressure system in combination with a low-cost fixed displacement pump the hydraulic system is designed to ensure the ICE experiences a constantly high load in a region of high efficiency, so-called point operation. To decrease the hydraulic losses incurred when supplying the linear actuators with flow, an additional intermediate pressure rail with independent metering edges is used. This enables various energy efficient discrete operating modes, including energy regeneration and recuperation.
An Oil Stiction Model for Flat Armature Solenoid Switching Valves
Authors: Scheidl Rudolf , Gradl Christoph
Published: February 2014

Oil stiction forces significantly influence the performance of fast switching valves. These forces stem from the significant lowering of the pressures between two oil filled plates relative to the surrounding pressure when the plates are quickly separated. If the pressure in the gap stays above the vapor pressure the stiction force can be derived from a solution of the Reynolds equation.

However, for very fast motions — as occur in fast switching valves with a flat armature solenoid — cavitation is most likely to occur. The cavitation zone starts in central parts of the gap and extends as long as the gap volume increase cannot be fully compensated by the flow in the gap. Cavitation reduces the stiction force significantly. In many valves this stiction force reduction is decisive for a proper functioning of the valve.

An important measure for stiction force control are flushing channels, in particular flushing bores. In this paper analytical models and Finite Volume method models are used to study the stiction force problems with and without cavitation and design measures for their mastering.
Dynamic Force Control of Displacement Controlled Drives by Means of an Iterative Learning Algorithm
Authors: Radermacher Tobias , Weber Jürgen , Dorner Dominik
Published: February 2014

Displacement controlled drive trains are applied more and more in industry because they are an energy efficient alternative to valve control. One major burden, for the use in a wide range of application, is the lower dynamic performance, which is caused by the large inertial forces of either swash plate pumps or speed controlled constant pumps. Additional challenges are the lack of control strategies, which determine the overall system dynamic performance. Starting with a comparison of four different linear drive trains (valve control, electro-mechanic, pump control, speed control) it is shown that the potential of a speed controlled drive train can be obtained by the use of an iterative learning controller. Once the controller is parameterized it is able to improve the tracking behavior significantly without having any effect on the plants stability.
Lean Partially Premixed Combustion Investigation of Methane Direct-Injection Under Different Characteristic Parameters
Authors: Askari Omid , Metghalchi Hameed , Hannani Siamak Kazemzadeh , Hemmati Hadis , Ebrahimi Reza
Published: February 2014

The effects of hydrogen addition, diluent addition, injection pressure, chamber pressure, chamber temperature and turbulence intensity on methane–air partially premixed turbulent combustion have been studied experimentally using a constant volume combustion chamber (CVCC). The fuel–air mixture was ignited by centrally located electrodes at given spark delay times of 1, 5, 40, 75 and 110 milliseconds. Experiments were performed for a wide range of hydrogen volumetric fractions (0% to 40%), exhaust gas recirculation (EGR) volumetric fractions (0% to 25% as a diluent), injection pressures (30–90 bar), chamber pressures (1–3 bar), chamber temperatures (298–432 K) and overall equivalence ratios of 0.6, 0.8, and 1.0. Flame propagation images via the Sclieren/Shadowgraph technique, combustions characteristics via pressure derived parameters and pollutant concentrations were analyzed for each set of conditions. The results showed that peak pressure and maximum rate of pressure rise increased with the increase in chamber pressure and temperature while changing injection pressure had no considerable effect on pressure and maximum rate of pressure rise. The peak pressure and maximum rate of pressure rise increased while combustion duration decreased with simultaneous increase of hydrogen content. The lean burn limit of methane–air turbulent combustion was improved with hydrogen addition. Addition of EGR increased combustion instability and misfiring while decreasing the emission of nitrogen oxides (NOx).
Computationally Efficient Simulation of Multi-Component Fuel Combustion Using a Sparse Analytical Jacobian Chemistry Solver and High-Dimensional Clustering
Authors: Perini Federico , Krishnasamy Anand , Ra Youngchul , Reitz Rolf D.
Published: February 2014

The need for more efficient and environmentally sustainable internal combustion engines is driving research towards the need to consider more realistic models for both fuel physics and chemistry. As far as compression ignition engines are concerned, phenomenological or lumped fuel models are unreliable to capture spray and combustion strategies outside of their validation domains — typically, high-pressure injection and high-temperature combustion. Furthermore, the development of variable-reactivity combustion strategies also creates the need to model comprehensively different hydrocarbon families even in single fuel surrogates. From the computational point of view, challenges to achieving practical simulation times arise from the dimensions of the reaction mechanism, that can be of hundreds species even if hydrocarbon families are lumped into representative compounds, and thus modeled with non-elementary, skeletal reaction pathways. In this case, it is also impossible to pursue further mechanism reductions to lower dimensions. CPU times for integrating chemical kinetics in internal combustion engine simulations ultimately scale with the number of cells in the grid, and with the cube number of species in the reaction mechanism. In the present work, two approaches to reduce the demands of engine simulations with detailed chemistry are presented. The first one addresses the demands due to the solution of the chemistry ODE system, and features the adoption of SpeedCHEM, a newly developed chemistry package that solves chemical kinetics using sparse analytical Jacobians. The second one aims to reduce the number of chemistry calculations by binning the CFD cells of the engine grid into a subset of clusters, where chemistry is solved and then mapped back to the original domain. In particular, a high-dimensional representation of the chemical state space is adopted for keeping track of the different fuel components, and a newly developed bounding-box-constrained k-means algorithm is used to subdivide the cells into reactively homogeneous clusters. The approaches have been tested on a number of simulations featuring multi-component diesel fuel surrogates, and different engine grids. The results show that significant CPU time reductions, of about one order of magnitude, can be achieved without loss of accuracy in both engine performance and emissions predictions, prompting for their applicability to more refined or full-sized engine grids.
Effect of Cetane Improver on Autoignition Characteristics of Low Cetane Sasol IPK Using Ignition Quality Tester (IQT)
Authors: Zheng Ziliang , Badawy Tamer , Henein Naeim , Sattler Eric , Johnson Nicholas
Published: February 2014

This paper investigates the effect of a cetane improver on the autoignition characteristics of Sasol IPK in the combustion chamber of the Ignition Quality Tester (IQT). The fuel tested was Sasol IPK with a Derived Cetane Number (DCN) of 31, treated with different percentages of Lubrizol 8090 cetane improver ranging from 0.1% to 0.4%. Tests were conducted under steady state conditions at a constant charging pressure of 21 bar. The charge air temperature before fuel injection varied from 778 to 848 K. Accordingly, all the tests were conducted under a constant charge density. The rate of heat release was calculated and analyzed in details, particularly during the autoignition period.

In addition, the physical and chemical delay periods were determined by comparing the results of two tests. The first was conducted with fuel injection into air according to ASTM standards where combustion occurred. In the second test, the fuel was injected into the chamber charged with nitrogen. The physical delay is defined as the period of time from start of injection (SOI) to point of inflection (POI), and the chemical delay is defined as the period of time from POI to start of combustion (SOC). Both the physical and chemical delay periods were determined under different charge temperatures. The cetane improver was found to have an effect only on the chemical ID period. In addition, the effect of the cetane improver on the apparent activation energy of the global combustion reactions was determined. The results showed a linear drop in the apparent activation energy with the increase in the percentage of the cetane improver. Moreover, the low temperature (LT) regimes were investigated and found to be presented in base fuel, as well as cetane improver treated fuels.
Modeling of Ion Current Signal in Diesel Combustion
Authors: Estefanous Fadi
Published: February 2014

Ionization in internal combustion engines produces a signal indicative of in-cylinder conditions that can be used for the feedback electronic control of the engine, to meet production goals in performance, fuel economy and emissions. Most of the research has been conducted on carbureted and port injection spark ignition engines where the ionization mechanisms are well defined. A limited number of investigations have been conducted on ionization in diesel engines because of its complex combustion process.

In this study, a detailed ionization mechanism is developed and introduced in a 3-D diesel cycle simulation computational fluid dynamics (CFD) code to determine the contribution of different species in the ionization process at different engine operating conditions. The CFD code is coupled with DARS-CFD, another module used to allow chemical kinetics calculations. The three-dimensional model accounts for the heterogeneity of the charge and the resulting variations in the combustion products. Furthermore, the model shows the effects of varying fuel injection pressure and engine load on the ion current signal characteristics. Ion current traces obtained experimentally from a heavy duty diesel engine were compared to the 3-D model results. The results of the simulation indicate that some heavy hydrocarbons, soot precursors play a major role, in addition to the role of NOx in ionization in diesel combustion.
Development and Optimization of a Two-Valve Spark-Ignition Direct-Injection (SIDI) Small Block Engine
Authors: Cleary David J. , Grover Ronald O. , Sczomak David P.
Published: February 2014

A systems approach is implemented to fully optimize the overall performance of a gasoline SIDI two-valve “small block” engine. The objective is to maximize fuel economy while achieving significant improvements in idle stability, cold-start emissions, and torque and power performance relative a baseline port-fuel-injected (PFI) engine. The scope includes the optimization of the fuel injector, piston, cylinder head, cams, in-cylinder charge motion, and the intake-manifold. The results show that the SIDI engine provides the potential to achieve 6.5% better fuel economy; a result of higher efficiency when implementing a higher geometric compression ratio and significantly better combustion performance. A multiple fuel-injection strategy is examined to provide lower HC emissions at a representative cold-start operating condition. The engine’s idle stability is improved by a factor of three; the individual contributions from a better combustion system design and from multiple fuel injections are identified. The new SIDI engine concept demonstrated significantly better wide-open-throttle (WOT) performance, including up to 10% higher torque and 6% more power when using premium fuel. This document further demonstrates the performance sensitivity to engine design variables while emphasizing the importance of using a systems approach to achieve optimized performance for the direct-injection engine technology.
Advanced Technology Igniter for High Power Density Engines
Authors: Etemad Shahrokh , Baird Benjamin D.
Published: February 2014

With current DoD goals of switching to a common logistics fuel, there is a significant drive to develop technologies that allow small, high power density engines such as used in unmanned aerial, marine, and ground vehicles, typically fueled by volatile fuels such as gasoline, to operate on heavy fuels such as JP-8. In this paper, the potential of advanced catalytic glow plugs as an enabling component for the use of heavy fuels both as a retrofit to existing engines as well as new engine designs is demonstrated. Compared to standard spark igniters and non-catalytic glow plugs, the use of catalytic glow plugs will provide benefits of lower required compression ratio, improved igniter life, reduced electrical energy requirements, and overall reduction in system weight and size. The advanced catalytic glow plug was demonstrated to have a significant increase in surface temperature (180+ °C) with impingement of a fuel spray. Engine testing demonstrated that the use of catalyst allowed stable engine operation at reduced power requirements. This technology would allow high power density engines to use heavy fuels, while potentially reducing electric power supply and engine complexity and weight, both of which would allow greater range and/or payload capacity.
An Experimental Investigation of Flame Lift-Off Length and Soot Luminosity of the Emulsified Diesel Under Various Ambient Temperatures
Authors: Huo Ming , Nithyanandan Karthik , Lee Chia-fon F. , Zhou Nan , Wu Han
Published: February 2014

The emulsified fuel remains attractive due to its potential capability of reducing the NOx and particular matter (PM) at the same time. In this work, the emulsified diesel, with the amount of water quantities ranged between 10% and 20% by volume, was injected and combusted in an optical constant volume chamber. With controlled combustion of acetylene mixture prior to the fuel injection, the chamber is able to provide high ambient temperature and pressure to mimic the real engine operation. In this study, ambient temperatures ranging from 800K to 1200K were investigated. Mie scattering images, at 15000 fps, were first taken to record the evolution of the spray using a Phantom 7.1 high speed camera coupled with a copper vapor laser as the light source. The spray images revealed longer liquid penetration and wider cone angle at the beginning stage of the injection event for emulsified fuel, supporting the occurrence of micro-explosion. Ambient temperature played an important role in the dynamic behavior of soot lift-off length as low ambient temperature features a long initial soot lift-off length and sharp decrease afterwards for both fuels while high ambient temperature enables the soot lift-off to achieve quasi-steady state immediately after the onset of the fuel injection. The broadband luminosity results indicate the advantage of using emulsified fuel to suppress soot formation, and this benefit can be maximized if coupled with a low temperature combustion strategy.
Development of a Lean Burn Methane Number Measurement Technique for Alternative Gaseous Fuel Evaluation
Authors: Wise Daniel M. , Olsen Daniel B. , Kim Myoungjin
Published: February 2014

A wide range of fuels are used in industrial gas fueled engines. Fuels include well-head gas, pipeline natural gas, producer gas, coal gas, digester gas, landfill gas, and liquefied petroleum gas. Many industrial gas fueled engines operate at high power density and at ultra-lean air-fuel ratios for low NOx emissions. Engines operate in a narrow air-fuel ratio band between misfire and knock limits. To utilize this wide range of fuels effectively it is important to understand knock properties. Methane number determination for natural gas blends is traditionally performed with research engines at stoichiometric conditions where the onset of knock is identified through subjective audible indication. The objective of this paper is to develop a process to determine knock onset through direct indication from pressure transducer data at lean operating conditions characteristic of lean-burn industrial gas engines. Validation of the method is provided with methane number determination and comparison of pipeline natural gas.

A Waukesha F2 Cooperative Fuel Research (CFR) engine is modified to incorporate piezoelectric pressure transducers at the cylinder head and conversion from natural aspiration to boosted intake and variable exhaust back pressures (to simulate turbocharger operation). The new pressure sensors enable Fast Fourier Transform calculation of pressure data to calculate amplitude at characteristic knock frequency.
Study of Cylinder-Exhaust-Gas-Temperature Variations Over Inlet Air Parameters of Compression-Ignition Engines
Authors: Chen Gong
Published: February 2014

Cylinder-exhaust-gas temperature (Texh) of a turbocharged compression-ignition engine indicates the levels of engine thermal loading on cylinder and exhaust components, thermal efficiency performance, and engine exhaust emissions. In consideration that Texh is affected by engine air inlet condition that primarily includes inlet air temperature (Ti) and pressure (pi), this paper studies the variation (ΔTexh) of Texh over varying the engine inlet air parameters of compression-ignition engines. The study is to understand ΔTexh with appropriate relations between the inlet parameters and Texh identified and simply modeled. The regarded effects on Texh and ΔTexh for turbocharged engines of this type are analyzed and predicted. The results indicate that Texh generally increases as Ti increases or pi decreases. For example, Texh would increase by ∼2 °C as Ti increases by 1 °C or increase by ∼35 °C as pi decreases by 10−2 MPa, as predicted for a typical high-power turbocharged diesel engine. The design and operating parameters significant in influencing ΔTexh along with varying Ti or pi are also studied. These include the degree of engine cylinder compression, the level of intake manifold air temperature, the magnitude of intake air boost, and the quantity of cycle combustion thermal input. As those change, the rate of variation in Texh varies. For instance, the results indicate that the rate of ΔTexh versus the inlet air parameters would increase as the quantity of cycle combustion thermal input becomes higher. With the understanding of ΔTexh, the engine output performances of thermal loading, efficiency, and exhaust emissions, concerning engine operation at variable ambient temperature or pressure, can be understood and evaluated for the purpose of engine analysis, design and optimization.
Test Requirements of Locomotive Fuel Tank Blunt Impact Tests
Authors: Jacobsen Karina , Carolan Michael , Llana Patricia
Published: February 2014

The Federal Railroad Administration’s Office of Research and Development is conducting research into passenger locomotive fuel tank crashworthiness. A series of impact tests are planned to measure fuel tank deformation under two types of dynamic loading conditions. This paper describes the test requirements for the preliminary tests in this series — a blunt impact of conventional locomotive fuel tanks.

Current design practice requires that Tier 1 locomotive fuel tanks have minimum properties adequate to sustain a prescribed set of static load conditions [1]. In accidents, fuel tanks are subjected to dynamic loading, often including a blunt or raking impact from various components of the rolling stock or trackbed. Current research is intended to increase understanding of the impact response of fuel tanks under dynamic loading. Utilizing an approach that has been effective in increasing the structural crashworthiness of passenger railcars, improved strategies can be developed that will address the types of loading conditions which have been observed to occur in a collision or derailment event. The improvement strategies developed by this research program can then be applied to alternative fuel tank designs, such as diesel multiple unit (DMU) tanks.

This paper describes test requirements for conducting two preliminary tests. These tests are referred to as preliminary because they will be used to evaluate the loading setup and instrumentation planned for the larger series of tests. These preliminary tests will evaluate a blunt impact on the bottom surface of two conventional passenger locomotive fuel tanks. The test articles chosen for the preliminary tests are fuel tanks removed from two retired EMD F-40 locomotives. While these fuel tanks do not reflect the current state of locomotive fuel tank manufacturing or design, they are suitable for means of these tests.

Each fuel tank will be mounted to a crash wall and impacted on its bottom face by an impact cart with a rigid impactor at a prescribed velocity. The first set of tests is designed to measure the deformation behavior of the fuel tanks. These tests are planned to result in puncture of the bottom surface of each fuel tank. The preliminary tests are targeted for October 2013 at the Transportation Technology Center (TTC) in Pueblo, Colorado.

Following this first series of impact tests, a second set of dynamic impact tests is planned to be conducted. This second set will include both blunt and raking impact conditions on conventional fuel tanks, DMU fuel tanks and fuel tanks incorporating improved strategies for impact protection. Lessons learned during the preliminary two tests will be applied during the second set of tests to improve the performance of those tests. Fuel tank research is being performed to determine strategies for increasing the fuel tank impact resistance to mitigate the threat of a post-collision or post-derailment fire.
High Performance Coupling Systems
Authors: Sammon Devin , Carter Daniel , Jones Kerry
Published: February 2014

The freight railway industry relies on the interchangeability of coupling system parts (i.e., couplers, locks, throwers, pins, knuckles). Variability in the dimensions of the components affects the ability to change parts efficiently and the performance of the components. Because of the complex shapes and dimensions involved, it has been difficult to identify the component causing most of the problems for a combination of coupling system parts. Transportation Technology Center Inc. (TTCI) has developed a digital E-type coupler gage that can be combined with 3-dimensional scanning technologies to help railroads and manufacturers find areas that may be causing fitment problems. Physical gages are also being developed for use in production and field environments. The digital and physical gages can be used for fitment quality checks by the railroads and manufacturers. The digital gage requires a laser scanning of the coupler in question to be completed. A 3-dimensional scan of a coupler can be overlaid with the digital gage to find the dimensions causing a problem. Though it is currently a destructive method, further development of scanning technology could make the process more efficient and nondestructive. Using a combination of the digital and physical gages with the proper procedure may reduce the number of problems with properly fitting components and premature failure of couplers in service.
Seasonal Effect on the Optimization of Rail Defect Inspection Frequency
Authors: Liu Xiang , Dick C. Tyler , Lovett Alexander , Saat Mohd Rapik , Barkan Christopher P. L.
Published: February 2014

Broken rails are the most common cause of severe freight-train derailments on American railroads. Reducing the occurrence of broken-rail-caused derailments is an important safety objective for the railroad industry. The current practice is to periodically inspect rails using non-destructive technologies such as ultrasonic inspection. Determining the optimal rail defect inspection frequency is a critical decision in railway infrastructure management. There is a seasonal variation in the occurrence of broken rails that result in train derailments. This paper quantifies the effect of this seasonal variation on the risk-based optimization of rail inspection frequency. This research can be incorporated into a larger framework of broken rail risk management to improve railroad transportation safety.
On the Application of Roller Rigs for Studying Rail Vehicle Systems
Authors: Meymand Sajjad Z. , Craft Michael J. , Ahmadian Mehdi
Published: February 2014

The primary intent of this study is to highlight the advantages and disadvantages of using roller rigs for engineering issues of importance to the railroad industry. Roller rigs have been in existence for more than a century for studying railway vehicle behavior. In contrast to field testing, roller rigs offer a controlled laboratory environment that can provide a successful path for obtaining data on the mechanics and dynamics of railway systems for a variety of operating conditions. Their use, however, imposes discrepancies from the field environment due to the nature of the commonly-used roller design. This study describes different rig configurations, including scaled and full-scale rigs. It includes the potential advantages and limitations of various rigs for conducting a wide range of studies concerning the dynamic stability of railcars, wheel–rail adhesion, wear and fatigue mechanisms, braking systems, and locomotive power.
Double Rail Model and Turnout Simulation
Authors: Shu Xinggao , Wilson Nicholas , Davis David D.
Published: February 2014

Transportation Technology Center, Inc., a wholly owned subsidiary of the Association of American Railroads, has developed a double rail model for special trackwork simulation in the NUCARS® vehicle/track interaction multibody dynamic simulation program. The double rail model consists of a primary rail and a secondary rail on each side of the track. it It permits one wheel to contact two rails so that the effects of their relative movements on wheel/rail contact can be investigated. It also allows rail profile and track suspension stiffness and damping to vary on the track.

This paper presents simulation results of a freight car running on a No. 20 turnout. Simulation results showed that the double rail model improved the integration stability and simulation accuracy for high frequency wheel/rail (W/R) impacts by capturing the simultaneous multiple W/R contact point situations and transitions under various discontinuous track running surface conditions.

Parametric studies of W/R impacts on frog points showed the frog point geometry designs have conflicting requirements for dynamic performance for vehicles equipped with with new wheels and hollow-worn wheels; the NUCARS double rail model provides a useful tool for frog and switch point geometry optimization.
Transcranial phase aberration correction using beam simulations and MR‐ARFI
Authors: Vyas Urvi , Kaye Elena , Pauly Kim Butts
Published: February 2014

Purpose:

Transcranial magnetic resonance‐guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation‐MR‐ARFI technique to achieve aberration correction for transcranial MR‐guided focused ultrasound surgery. The technique uses ultrasound beam propagation simulations with MR Acoustic Radiation Force Imaging (MR‐ARFI) to correct skull‐caused phase aberrations.

Methods:

Skull‐based numerical aberrations were obtained from a MR‐guided focused ultrasound patient treatment and were added to all elements of the InSightec conformal bone focused ultrasound surgery transducer during transmission. In the first experiment, the 1024 aberrations derived from a human skull were condensed into 16 aberrations by averaging over the transducer area of 64 elements. In the second experiment, all 1024 aberrations were applied to the transducer. The aberrated MR‐ARFI images were used in the hybrid simulation‐MR‐ARFI technique to find 16 estimated aberrations. These estimated aberrations were subtracted from the original aberrations to result in the corrected images. Each aberration experiment (16‐aberration and 1024‐aberration) was repeated three times.

Results:

The corrected MR‐ARFI image was compared to the aberrated image and the ideal image (image with zero aberrations) for each experiment. The hybrid simulation‐MR‐ARFI technique resulted in an average increase in focal MR‐ARFI phase of 44% for the 16‐aberration case and 52% for the 1024‐aberration case, and recovered 83% and 39% of the ideal MR‐ARFI phase for the 16‐aberrations and 1024‐aberration case, respectively.

Conclusions:

Using one MR‐ARFI image and noa priori information about the applied phase aberrations, the hybrid simulation‐MR‐ARFI technique improved the maximum MR‐ARFI phase of the beamˈs focus.