bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Ambient Temperature and Humidity on Combustion and Emissions of a Spark Assisted Compression Ignition Engine
Authors: Chang Yan , Mendrea Brandon , Sterniak Jeff , Bohac Stanislav V. 
Published: January 2016

Spark Assisted Compression Ignition (SACI) offers more practical combustion phasing control and a softer pressure rise rate than Homogeneous Charge Compression Ignition (HCCI) combustion, and improved thermal efficiency and lower NOx emissions than Spark Ignition (SI) combustion. Any practical engine, including one that uses SACI in part of its operating range, must be robust to changes in ambient conditions.
This study investigates the effects of ambient temperature and humidity on stoichiometric SACI engine performance, combustion and emissions. It is shown that at the medium speed and load SACI test point selected for this study, increasing ambient air temperature from 20°C to 41°C advances combustion phasing, increases maximum pressure rise rate, causes a larger fraction of the charge to be consumed by auto-ignition (and a smaller fraction by flame propagation), increases NOx, and increases Brake Specific Fuel Consumption (BSFC). Increasing ambient humidity from 32% to 60% retards combustion phasing, reduces maximum pressure rise rate, causes a larger fraction of the charge to be consumed by auto-ignition and a smaller fraction by flame propagation, increases Coefficient of Variation of IMEP (COV) of IMEP, reduces NOx, and increases BSFC. These results show that successful implementation of SACI combustion in real-world driving requires a control strategy that compensates for changes in ambient temperature and humidity.
NVH of RCCI With DI ULSD and PFI With 50% N-Butanol
Authors: Soloiu Valentin , Simons Emerald , Muinos Martin , Harp Spencer 
Published: January 2016

The noise of diesel engines is dependent upon numerous factors such as: load, speed, fuel injection strategies and fuel type, design of the piston, piston-pin and cylinder and their tolerances, bearings, valves and rocker arm clearances, and designs of the manifolds.
In this study, engine sound and vibrations analysis have been conducted using two types of fueling and combustion strategies: classical ULSD combustion and the new RCCI with n-butanol injected in the intake manifold. The analyses add to the understanding of the influence of combustion characteristics’ effect on mechanical noise and vibrations throughout the engine’s operating cycle.
The sound and vibration signals were both analyzed in the frequency and angle domain spectrum. Overall NVH spectrum from ULSD combustion was compared to that of RCCI with 50% by mass PFI of n-butanol (the 50% remaining ULSD fuel was directly injected).
Frequency analyses were performed using the FFT and CPB methods with Bruel & Kjaer’s Pulse sound and vibrations analysis software. Angle domain analyses were performed, referencing 0 CAD as TDC in combustion.
The engine tests were conducted at 1500 rpm and 4 bar IMEP. The COV of IMEP for DI ULSD and RCCI were 2.4 and 2.2, respectively. The correlations between sound, three dimensional vibration levels, and timings were found for: pressure gradients from combustion process, intake and exhaust valve actuations and gas exchange, and piston slap on the cylinder liner.
The measurements were extracted and analyzed, and the results determined that virtually all the noise and vibration values pertinent to RCCI were lower than those of ULSD classical combustion.
Numerical Comparison of an Electric Turbo Compound Applied to a SI and a CI Engine
Authors: Pasini Gianluca , Frigo Stefano , Marelli Silvia 
Published: January 2016

In a medium term scenario Internal Combustion Engine (ICE) downsizing and hybrid powertrain will represent the actual trend in vehicle technology to reduce fuel consumption and CO2 emission. Concerning downsizing concept, to maintain a reasonable power level in small engines, the application of turbocharging is mandatory both for spark ignition (SI) and compression ignition (CI) engines. Following this aspect, the possibility to couple an electric machine to the turbocharger (electric turbo compound, ETC) to recover the residual energy of the exhaust gases is becoming more and more attractive, as demonstrated by several studies around the world and by the current application in the F1 Championship.
The present paper shows the first numerical results of a research program focused on the comparison of the benefits resulting from the application of an ETC to a small twin-cylinder SI engine (900 cm3) and to a four cylinders CI engine (1600 cm3), both of the same maximum power. Starting from the experimental maps of several turbines and compressors, complete model of both turbocharged engines were created using the AVL BOOST one-dimension code.
Concerning the SI engine, first numerical results show that ETC can improve the average overall efficiency at the highest engine speeds and loads. Besides, boost range extension in the lowest engine rotational speed region and a possible reduction of turbo lag represent other benefits related to ETC application.
On the other hand, the adoption of an ETC to a CI engine shows larger benefits in term energy recovery at the highest engine speeds, with consequent reduction of fuel consumption, mainly due to the absence of throttling effects in the intake manifold and related pumping losses.
Pipeline Vulnerability to Natural Hazards
Authors: Amórtegui José Vicente 
Published: January 2016

The strength and stiffness of the pipelines allow them to tolerate the effects of natural hazards for some period of time. The amount of time depends on the strength and deformability, the stress state, the age, the conditions of installation and operation of the pipeline and their geometric arrangement with regard to the hazardous process.
Accordingly, some of the hazards due to weather conditions and external forces would not be time independent. In consequence the designing of monitoring systems to predict the behavior of the pipelines against natural hazards is required in order to carry out the preventive actions which are necessary to avoid failure of the pipes due to the exposition to those hazards.
In this paper a method for assessing the transport system vulnerability is developed, a function for risk analysis is proposed (which is determined by the probability of the natural hazard, the pipeline’s vulnerability to the hazard and the consequences of the pipe rupture). The elements that are part of that evaluation are presented and illustrated by means of examples.
PVCO Pipeline Performance Under Large Ground Deformation
Authors: Wham Brad P. , Argyrou Christina , O’Rourke Thomas D. , Stewart Harry E. , Bond Timothy K. 
Published: January 2016

Technological advances have improved pipeline capacity to accommodate large ground deformation associated with earthquakes, floods, landslides, tunneling, deep excavations, mining, and subsidence. The fabrication of polyvinyl chloride (PVC) piping, for example, can be modified by expanding PVC pipe stock to approximately twice its original diameter, thus causing PVC molecular chains to realign in the circumferential direction. This process yields biaxially oriented polyvinyl chloride (PVCO) pipe with increased circumferential strength, reduced pipe wall thickness, and enhanced cross-sectional flexibility.
This paper reports on experiments performed at the Cornell University Large-Scale Lifelines Testing Facility characterizing PVCO pipeline performance in response to large ground deformation. The evaluation was performed on 150-mm (6-in.)-diameter PVCO pipelines with bell-and-spigot joints. The testing procedure included determination of fundamental PVCO material properties, axial joint tension and compression tests, four-point bending tests, and a full-scale fault rupture simulation. The test results show the performance of segmental PVCO pipelines under large ground deformation is strongly influenced by the axial pullout and compressive load capacity of the joints, as well as their ability to accommodate deflection and joint rotation. The PVCO pipeline performance is quantified in terms of its capacity to accommodate horizontal ground strain, and compared with a statistical characterization of lateral ground strains caused by soil liquefaction during the Canterbury earthquake sequence in New Zealand.
Using Tension Measurement Methods for Backfill Procedures in the Evaluation of Pipelines
Authors: Silva Sérgio P. P. , Seixas Renato , Pacheco Anderson , Amaral Claudio 
Published: January 2016

The OPASC and the OSPAR are 10″ and 30″ pipelines, respectively, which interconnect the State of Santa Catarina and Paraná, crossing the Serra do Mar, in southern Brazil. In 2003, after conducting slope stabilization works on a point of geotechnical activity, vibrating string gauges were installed to monitor the stress in these pipelines, in addition to geotechnical instruments installed to monitor the slope. These gauges were installed in seven sections, with 3 instruments per section, along a span of 180 meters.
Although the geotechnical instrumentation has shown no evidence of movement in the slope, the gauges recorded an increase in stress values in some of the sections within three months from the time of installation, however, they remained stable in their values for the next ten years. In 2013, blind hole tests were performed to determine the stresses in these sections and to verify the proper function of the gauges. The combination of these two measurement techniques, vibrating string gauges and blind hole tests, allowed for the determination of the stress state in sections, over time. From there, equivalent stress could be determined and compared with allowable stresses defined in standards.
After the completion of the blind hole test and subsequent backfill, stress rose again at the same rate, returning to the level reached after the initial installation of the strain gauges. To reduce the stress level additional excavations have been made to relieve the stress on the pipeline, followed by backfilling performed in a controlled manner in order for the soil to properly compact, which reduced the stress value over the pipes. The graphs depicting variation over time of stress showed a significant reduction in the level of stress after the backfill.
The main conclusions are listed as follows: a) the evolution of stress observed by the extensometers was primarily caused by pipeline settling; b) the vibrating string gauges are functioning properly and provide reliable readings even after ten years of service; c) the blind hole testing performed in conjunction with monitoring by vibrating string gauges can provide approximate values of the full stress state; d) after stress relief, backfilling of the trench must be carried out by compacting the soil beneath the pipe in order to reduce bending stresses due to the weight of the soil; e) backfilling of the trench, when not properly performed, can cause compressive stress in bending, reaching 390 mPa over the next few months.
Management System for the Control of Geotechnical Risk in the Camisea Pipeline Transport System
Authors: Velásquez M. Fernando Adolfo 
Published: January 2016

The Camisea Pipeline Transport System [“Sistema de Transporte por Ductos”] consists of two parallel pipelines, one of which carries natural gas (NG) over a distance of 730 km, and the other which carries liquid natural gas (LNG) over a distance of 560 km, starting in the Amazon basin in Malvinas (Cusco). The LNG pipeline ends in Playa Lobería (ICA) and the NG pipeline ends at the City Gate located in Lurín (Lima).
In terms of complexity, the geographic, geological, and climate-related characteristics of the rain-forest, mountain, and coastal regions through which the pipeline passes set it apart from the rest of the world’s pipelines. The highest point in the area is 4,860 meters above mean sea level in its mountain portion in the Peruvian Andes.
The first 200 km, which pose the greatest operational challenges, are characterized by residual soils, slopes steeper than 45°, and rainfall of more than 6,000 mm per year — in addition to the logistical difficulties presented by the lack of vehicular access for the transport of personnel, materials, and equipment, such that maintenance work must be done by helicopter.
The purpose of this article is to illustrate the diversity of geotechnical scenarios in this geographical area, and to discuss the early identification of risks through the management and control cycle for geotechnical threats, which consists of the following stages:
• The Threat Identification System: This stage includes the continuous monitoring of the right-of-way in order to detect geotechnical problems, which are triggered primarily by rainfall.
• Risk assessment: This stage involves the use of a geotechnical risk matrix that was developed in accordance with the so-called “Safety Ratio” [“Relación de Seguridad”], which assimilates the parameters for the calculation of the Safety Factor used in slope stability analysis, thereby making it possible to establish the various risk levels.
• Structure design: Depending on the risk level, the corresponding engineering tasks are developed and prioritized in order to determine the designs, through the use of geotechnical engineering processes such as subsurface exploration, laboratory tests, mathematical modeling, and instrumentation.
• Implementation of the structures: The geotechnical stabilization structures are built during the dry season, i.e., from April to October of each year.
• Monitoring and surveillance: Once the stabilization structures have been built and the dry season has ended, continuous monitoring is performed during the rainy season (November to April), through ongoing inspections, topographic monitoring, and instrumentation at sensitive sites, using inclinometers, piezometers, and strain gauges.
Thanks to these working techniques and control measures, as implemented in an area with special topographic and climate-related characteristics, it has been possible to achieve a dramatic reduction in the geotechnical risks to which the Camisea transport system is exposed.
Management Plans Formulated Based on the Verification and Validation of Information Compiled in Right-of-Way Patrols
Authors: Aristizabal Ceballos Jaime Hernan , Rodríguez Jiménez Paula Andrea 
Published: January 2016

In Ecopetrol’s Office of the Vice-president of Transportation and Logistics, one of the principal inputs for formulating plans for the management of sites with geotechnical findings is the verification and validation of the information compiled in right-of-way patrols, by a standardized database that contains the geotechnical findings according to a defined typology.
The purpose of doing this is to deal with, on a timely basis, geotechnically complex zones based on the identification and characterization of geotechnical findings (recurrence and activity, among others), and to provide feedback to the Geotechnical and Risk Zoning models, with a view toward their being much better adapted to reality and making it possible to identify the gaps that distract the analysis models from the actual condition of the asset. This document describes the experiences along this line that have been filed over the course of recent years and shows the relevance of each component to the objective of establishing management plans of a preventive nature.
On the Stability of Decentralized AVC/ASAC for Large-Scale Structures
Authors: Algermissen Stephan , Monner Hans P. 
Published: January 2016

Active Vibration Control (AVC) and Active Structural Acoustic Control (ASAC) gained much attention in all kind of industries in the past. Promising results have been achieved in controlling the vibration and the noise emission/transmission of single panel structures. Especially for aircraft applications, concepts for the reduction of the turbulent boundary layer, rotor or jet noise are presented in the literature. In most cases the contributed work is focused on a single panel or a section of the fuselage/lining. However, an AVC/ASAC system can only be effective for the passengers when it is expanded to the entire fuselage structure. This expansion inevitably leads to a large number of sensors and actuators and thus to a controlled plant of high dimensions. For model-based control approaches especially, the system identification and the proof of stability would be challenging and probably not realizable.
In this paper a strategy for such large-scale problems is investigated. A decentralized control approach with collocated actuator-sensor pairs is proposed. Since adjacent control loops are highly coupled by the underlying structure, special attention has to be given to the global stability of the entire control system. Instead of proving local stability and setting a global master gain, a method for the tuning of the single collocated control loops is developed that takes the cross-couplings into account. Based on data of DLR’s experimental aircraft Dornier 728, it can be shown that the new method increases the performance of the control system compared to the master-gain method.
Non-Linear Impedance-Based Structural Health Monitoring for Damage Detection and Identification
Authors: Albakri Mohammad I. , Malladi Sriram , Tarazaga Pablo A. 
Published: January 2016

Impedance-based structural health monitoring (SHM) is a non-destructive, active technique for real-time structural damage assessment. Conventional impedance-based SHM practices apply a sinusoidal signal of fixed amplitude to excite the piezoceramic patch and obtain the impedance signature over a certain frequency range. Damage is then detected by comparing the measured impedance signature to a baseline measurement taken at the pristine state.
In this work, the amplitude of the driving signal, which is directly related to the magnitude of the excitation force acting on the structure, is introduced as an additional variable, and sweeps over both frequencies and amplitudes are performed. Several structural defects, such as cracks and loose joints, are nonlinear in nature. Therefore, changing the excitation force will allow the detection of such damage induced nonlinearities and track their evolution.
Numerical simulations are carried out to study the effects of nonlinearities on the impedance signature using a single mode model. Several types of structural nonlinearities, such as hardening, softening, and nonlinear damping are studied with the assumption that the piezoelectric actuator stays in its linear regime. Experiments are conducted on a single beam and a lap joint, and impedance signatures in the range of 12–15 KHz are measured at different levels of excitation. Nonlinear damping and softening behavior are detected experimentally by examining the measured impedance signatures. Numerical and experimental findings suggest the possibility of detecting and tracking structural nonlinearities using impedance measurements.
Magnetically Responsive Droplet Interface Bilayer Networks
Authors: Brahmbhatt Khushboo , Zhao Wujun , Deng Zhaojie , Mao Leidong , Freeman Eric 
Published: January 2016

This work explores incorporating ferrofluids with droplet interface bilayer (DIB) membranes. Ferrofluids contain magnetic nanoparticles in solution with a stabilizing surfactant, providing a magnetically-responsive fluid. These fluids allow for remote mechanical manipulation of ferrofluid droplets through magnetic fields, and will allow for better control over the characteristics of networks of stimuli-responsive cellular membranes created through by DIB technique.
This work involves several phases. First, a suitable biocompatible ferrofluid is synthesized, containing a neutral pH and a biocompatible surfactant. Once a proper ferrofluid is identified, it is tested as the aqueous phase for the creation of DIB membranes. Interfacial membranes between ferrofluid droplets are created and compared to non-ferrofluid DIB membranes. The interfacial membrane between two ferrofluid droplets was tested for leakage and stability, and the electrical characteristics of the interfacial membrane were studied and compared to non-ferrofluid DIB membranes.
Once it is confirmed that the ferrofluid droplets do not negatively interfere with the formation of the artificial cellular membranes through the electrical measurements, the magnetically-responsive nature of the ferrofluid droplets are used to form large networks of DIB membranes through a simple magnetic field. These networks are easy to assemble and may be remotely manipulated, providing a significant step towards the rapid and simple assembly of DIB networks advancing towards the tissue scale.
Incorporating Stimuli-Responsive Bacteria in Microfluidic Droplets
Authors: Chukwurah Kengelle Q. , Yang Yaping , Wang Jian , Yan Yajun , Freeman Eric C. 
Published: January 2016

Model cellular membranes respond to chemical and electrical stimuli, regulating transport and exchange between two neighboring aqueous droplets. This regulated exchange may prove useful for controlling aqueous micro-environments for studying stimuli-responsive encapsulated bacteria. This concept is explored in this work, focusing on characterizing the bacterial response within a synthetic cellular environment.
In the droplet interface bilayer (DIB) approach, aqueous micro-droplets deposited in an oil reservoir with dissolved lipids are coated with lipid monolayers and arranged into artificial cellular networks. This approach has been explored for potential use as a biologically-inspired smart material, but new material transduction pathways are necessary. This may be accomplished by combining this bottom-up approach to synthetic biology with living organisms such as stimuli-responsive bacteria.
Bacteria encapsulation within the microfluidic droplets begins with a strain of Escherichia coli (E. coli), XL1-Blue. These flagellated bacteria naturally respond and move towards chemoattractants such as casamino acids, and their motion may be tracked through differential interference contrast (DIC) and fluorescent microscopy. Chemotaxis of XL1-Blue was assessed through low-flow perfusion of the chemoattractant (casamino acids) into a buffer solution containing the bacteria through a tailored capillary tube. Next, the response of bacteria within asymmetric DIB networks separating the bacteria and the chemoattractant were studied.
Energy Harvesting From Heartbeat Using Piezoelectric Beams With Fan-Folded Configuration and Added Tip Mass
Authors: Ansari M. H. , Karami M. Amin 
Published: January 2016

A fan-folded piezoelectric energy harvester is designed to generate electricity using heartbeat vibrations. This energy harvester consists of several bimorph beams stacked on top of each other making a fan-folded shape. Each beam has a brass substrate and two piezoelectric patches attached on both sides of it. These beams are connected to each other by rigid beams. One end of the device is clamped to the wall and the other end is free to vibrate. A tip mass is placed at the free end to enhance the output power of the device and reduce the natural frequency of the system.
High natural frequency is one major concern about the microscaled energy harvesters. The size for this energy harvester is 1 cm by 1 cm by 1 cm, which makes the natural frequency very high. By utilizing the fan-folded geometry and adding tip mass and link mass to the configuration, this natural frequency is reduced to the desired range.
The generated electricity can be used to power up a pacemaker. If enough electricity is generated, the pacemaker operates without having a battery and the patient does not need to have a surgery every seven to ten years to have the battery replaced. The power needed for a pacemaker to operate is about 1 microwatt. In this paper, the natural frequencies and mode shapes of fan-folded energy harvesters with added tip mass and link mass are analytically derived. The electro-mechanical coupling has been included in the model and the expression for the multi-mode power frequency response function is calculated.