bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technology Review in IC Engine Applications
Authors: Scheer Anthony , Etemad Shahrokh 
Published: July 2013

When a company designs an engine, mandates by the federal government regarding fuel efficiency, safety and emissions must be met. Consumers demand power, reliability, and creature comforts of the vehicles they choose to purchase. Car manufacturers must meet all of these needs and desires as well as maintain profitability.
The present paper reviews the application of recent advances in IC engines. It covers the four specific areas of (a) Electronic Applications (b) Air Flow Management (c) Fuel Injection / Combustion and (d) Loss Reduction technologies to address the needs of engine performance enhancement. Finally it provides a future direction of the technology for IC engine applications.
Meniscus Formation in the Piston Compression Ring-Cylinder Liner Inlet Zone
Authors: Rahmani Ramin , Styles Gema , Rahnejat Homer 
Published: July 2013

The piston compression ring-cylinder liner contact experiences a transient regime of lubrication. This comprises hydrodynamic, mixed (partial) or boundary interactions. The regime of lubrication is influenced by contact kinematics, loading, mechanical and topographical properties of the bounding solid surfaces, as well as lubricant rheology and its supply to feed the conjunction. Ideally, a sufficient volume of lubricant would exist at the conjunctional inlet, which acts as a meniscus, from which a film of lubricant is entrained into the contact area. However, often there is an insufficient volume at the inlet to the contact or unfavourable kinematic conditions exist, such as at the dead centre reversals in the piston system. Such conditions are generally regarded as the underlying reasons for mixed or boundary regimes of lubrication. Whilst, these are the main reasons for failure to form a coherent lubricant film at dead centre reversals, poor hydrodynamic lubrication can also occur elsewhere in the piston cycle due to the lack of an inlet meniscus. This may be as the result of poor ring-bore conformability, where a meniscus cannot be formed in an increasing clearance space. Numerical analyses reported in open literature often assume an idealised fully flooded or drowned inlet. Other analyses assume starved inlet boundaries, usually based on a lubricant availability model, which itself is based on an assumed supply of lubricant on free surfaces ahead of the contact. It is, however, important to establish the limiting clearance space which would allow the lubricant to adhere to the adjacent boundary solids and, thus form a meniscus bridge. The current study is aimed at establishing inlet meniscus conditions. This would depend on the lubricant surface tension, affected by the free surface energy of liquid-vapour interface and the contact angle made between the lubricant and the bounding solids. It also depends on the solid surfaces, any coatings and their topography.
In general, the results indicate the dependence of the meniscus force on surface material and topography, through measurement of contact angles made by the various compression rings against the various cylinder liner surfaces, using an especially developed rig and in conjunction with a goniometer. Obviously, the measurements do not exactly replicate those existing in a fired engine. Nonetheless, this initial study provides a good insight into oil-surface combination in separating gaps, which is far more representative than the usually assumed idealised inlet conditions.
Two-Dimensional Real-Time Interferometric Monitoring System for Exposure Controlled Projection Lithography
Authors: Jariwala Amit S. , Schwerzel Robert E. , Werve Michael , Rosen David W. 
Published: July 2013

Stereolithography is an additive manufacturing process in which liquid photopolymer resin is cross-linked and converted to solid polymer with an ultraviolet light source. Exposure Controlled Projection Lithography (ECPL) is a stereolithographic process in which incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure a photopolymer layer that grows progressively from the substrate surface. In contrast to existing stereolithography techniques, this technique uses a gray-scale projected image, or alternatively a series of binary bit-map images, to produce a three-dimensional polymer object with the desired shape, and it can be used on either flat or curved substrates.
Like most stereolithographic technologies, ECPL works in a unidirectional fashion. Calibration constants derived experimentally are fed to the software used to control the system. This unidirectional fabrication method does not, by itself, allow the system to compensate for minor variations, thereby limiting the overall accuracy of the process. We present here a simple, real-time monitoring system based on interferometry, which can be used to provide feedback control to the ECPL process, thus making it more robust and increasing system accuracy. The results obtained from this monitoring system provide a means to better visualize and understand the various phenomena occurring during the photopolymerization of transparent photopolymers.
A Simple Inverter-Motor System to Improve Energy Consumption and Maximum Torque
Authors: Watanabe Tohru , Fujita Yukishige , Totani Mikio 
Published: July 2013

A new inverter-AC motor system having four power source lines, which can control each coil current independently, is compared to an ordinary inverter-AC motor system using a Y-type coil connection and three power lines. In this paper, three-phase rectangular-type currents are generated by the inverter made of simple ICs.
In a previous paper[1], similar comparison experiments were executed using a high-speed DSP board. The board can calculate the three-phase currents to generate a rotating, resultant, magnetic flux with a precise constant strength and phase. It was verified by experiments that an energy consumption of 15% can be saved by using the proposed independent, motor-coil currents. However, it requires high speed and high cost DSP or CPU.
In this paper, it is verified by using a new inverter-AC motor system that an energy consumption of 15% can be saved, and also the maximum torque increases 10%.
Comparison of Inverse Algorithms for Delamination Detection in Composite Laminates
Authors: Zhang Zhifang , Ihesiulor Obinna Kenneth , Shankar Krishna , Ray Tapabrata 
Published: July 2013

Delamination is a frequent and potentially serious damage that can occur in laminated polymer composites due to the poor inter-laminar fracture toughness of the matrix. Vibration based detection methods employ changes caused by loss of stiffness in dynamic parameters such as frequencies and mode shapes to detect and assess damage. Because it is a whole field method, and can be applied instantaneously and remotely, vibration monitoring using frequency measurements offers great potential for implementation in online structural health monitoring systems. However, one of the disadvantages of using frequency measurements is that while the presence of damage is easily identified through a shift in measured frequency, the determination of the location and the severity of the damage is not easy to accomplish. To determine the location and severity of damage from measured changes in frequency, it is necessary to solve the inverse problem, which requires the solution of a set of non-linear simultaneous equations.
In this paper, we have compared the performance of three different inverse algorithms for delamination detection in the fibre-reinforced composite laminates: direct of solution using a graphical method, artificial neural network (ANN) and surrogate-based optimization. In particular, the graphical method which was earlier proposed for problems of two variables has been extended to solution of three variables, the interface, location along the beam length and size of delamination in laminated composite beams. The three inverse algorithms have been compared using numerical validation data generated from the theoretical model of delaminated beam with and without artificial errors. All three algorithms can predict the delamination parameters accurately using the validation data directly generated from theoretical model. However, if artificial errors are introduced in the numerical data to simulate uncertainties in measurement of frequencies, ANN does not fare as well as the the other two methods as it is more sensitive to the artificial discrepancies. Also, ANN requires the network to be retrained if the measured frequency modes do not match the input modes in the existing network. The graphical technique and the surrogate based optimization performed equally well in the validations. However, the graphical technique is only applicable to no more than three variables, while the surrogate-based optimization algorithm can be applied to inverse problems with several unknown parameters such as in the case of delaminations in composite plates.
A Structural Health Monitoring System for Composite Beams With Coupled Bending-Torsion
Authors: Hasan Zeaid , Atmeh Ghassan 
Published: July 2013

Structural health monitoring (SHM) is the process of damage identification in structural systems which have been an area of interest and a well-recognized field of technology in the past decade. Such systems involve the integration of smart materials, sensors and decision-making algorithms into the structure to detect damage, evaluate the structural integrity and predict the remaining life time. These systems have the potential to replace traditional non-destructive evaluation (NDE) of structures.
This study focuses on presenting an automated structural health monitoring (SHM) system based on detecting shifts in natural frequencies of the structure. The damage detection technique is implemented on a cracked composite beam vibrating in coupled bending-torsion where the crack is assumed open. Modal analysis is conducted on the composite beam in order to predict the natural frequency and the associated mode shapes. Based on this analysis, a database of information related to the specific composite beam being analyzed such as layups and natural frequencies are stored. The natural frequency will be measured and compared to that database for damage detection. A finite element model is also presented and compared with the analytical results. It is observed that the variation of natural frequencies in the presence of a crack is affected by the crack ratio, crack location and fiber orientation. In particular, the variation pattern is different as the magnitude of bending-torsion coupling changes due to different fiber angles.
A simple circuit containing a microcontroller is implemented to simulate the automated SHM concept. The microcontroller serves as the data storage device as well as the decision maker based on the instantaneous comparison between the healthy and the damaged structure. The proposed system may be implemented in many structural components such as aircraft frames and bridges. This SHM technology may help replace the current time-based maintenance scheme with a condition-based one. The condition-based maintenance scheme relies on the ability to monitor the condition of the system and supply information of damage detection to allow a corrective action to be taken.
A Fractal-Inspired Multi-Frequency Piezoelectric Energy Converter: Computational and Experimental Characterization
Authors: Castagnetti Davide 
Published: July 2013

In order to develop self-powered wireless sensor nodes, many energy harvesting devices, able to convert freely available ambient energy into electrical energy, have been proposed in the literature. A promising technique, in terms of simplicity and high conversion efficiency, is the harvesting of ambient kinetic energy through piezoelectric materials.
The aim of this work is to design and investigate the modal response and the power output of a fractal-inspired, multi-frequency, piezoelectric energy converter, previously presented by the author. Two are the steps of the work. First, a computational modal analysis of the converter is performed. Second, a physical prototype of the converter is built and its eigenfrequencies and power generation under different resistive loads are experimentally examined in the range between 0 and 120 Hz. The converter exhibits three eigenfrequencies and a good power output, in particular at the first eigenfrequency.
Investigations on the Amplitude-Dependent Damping Behavior of Superelastic Shape Memory Alloys
Authors: Böttcher Jonas , Neubauer Marcus , Wallaschek Jörg 
Published: July 2013

The nonlinear, hysteretic stress-strain characteristic of superelastic shape memory alloys (SMA) results in energy dissipation and therefore in high damping capacities. Due to the nonlinearity the damping capacity strongly depends on the amplitude of the applied excitation. In this work, a rheological non-smooth model is used to describe the principle behavior of superelastic SMA undergoing harmonic displacements. The equivalent mechanical model consists of a spring representing the elastic deformation of the superelastic SMA in austenitic and detwinned martensitic state. A friction element represents the stress plateaus for forward and backward transformation between austenitic and martensitic state. A constant force is applied to the system to generate an offset which shifts the hysteresis to positive force values. Two mechanical stops are implemented to describe the end of the stress plateaus and therefore correspond to the strain differences of the stress levels for forward and backward transformation. Thus, the system behavior is highly amplitude-dependent.
A harmonic approximation of the force generated by the superelastic SMA element during one excitation period is calculated by applying the Harmonic Balance Method to the nonlinear force signal of the rheological model. In this context the Fourier coefficients are calculated by performing a piecewise integration of the force signal. The Integrals are being calculated for each steady interval. The equivalent stiffness and damping coefficients are given for this approximation as functions of excitation amplitude and the system parameters. Based on these results, the damping capacity of a superelastic shape memory element undergoing harmonic displacements is presented using an analytical expression for the damping ratio.
Cellular Honeycomb-Like Structures With Internal Inclusions in the Unit-Cell
Authors: Pontecorvo Michael E. , Barbarino Silvestro , Gandhi Farhan S. 
Published: July 2013

Cellular structures with hexagonal unit cells show a high degree of flexibility in design. Based on the geometry of the unit cells, highly orthotropic structures, structures with negative Poisson’s ratios, structures with high strain capability in a particular direction, or other desirable characteristics may be designed. Much of the prior work on cellular structures is based on hexagonal honeycomb-like unit cells, without any inclusions. The present paper envisages extending conventional cellular honeycomb-like structures to have inclusions or internal features within the unit cells. Various types of internal features such as contact elements, buckling beams, bi-stable/snap-through elements or viscous dashpots can result in unit cells which display stiffening, softening, negative stiffness, or dissipative behavior. A structure can be assembled using a specific element type, or different types of elements in specific arrangements, to provide desired system level behavior. The ability to so optimally and flexibly design cellular structures could potentially lead to their replacing conventional structures made from bulk materials.
As a first step, this paper presents work on hexagonal unit cells with linear springs as the simplest of inclusions. The hexagonal cell itself is comprised of rigid links and pin-joints. Since such a cell has no stiffness of its own, the behavior of any internal feature is emphasized. However, for kinematic stability purposes, three springs are required, and the significance of these constraints within the cell will be discussed. For different spring arrangements, closed-form analytical expressions are derived for the in-plane modulus and Poisson’s ratio. The analytical expressions are validated using NASTRAN finite element simulations, as well as against experimental tensile/compressive tests of fabricated unit cells with internal springs. When the spring stiffness exceeds certain values, the rigid cell wall assumption is no longer valid, and these bounds are established. The validated analysis is used to conduct design studies on how the cell modulus would vary with geometric parameters such as cell angle and cell wall length ratio.
Design and Fabrication of an SMA Actuated Bat
Authors: Furst Stephen J. , Peele Bryan , Seelecke Stefan 
Published: July 2013

Shape memory alloy (SMA) actuator wires provide a natural analog for biological muscles. Additionally, SMA wires are lightweight and have an extremely high energy density, making them desirable for aerospace applications. Therefore, it is natural to consider implementing SMA actuator wires in a flapping flight platform based on the biology of an animal, such as a bat.
This work focuses on the design and fabrication of a bat with SMA-actuated elbow and shoulder joints configured to mimic the flapping pattern of a bat. The joints themselves are made from super-elastic SMA ribbons that can bend through large angles and constrain the rotation of each joint to a single degree of freedom. The design process involves careful consideration of the SMA wire placement and joint geometry such that the desired joint rotation is induced without exposing either the super-elastic joint material or actuator wires to excessive stresses. A simplified bending and force model is used to estimate the bending and stresses, and an optimization algorithm is employed to maximize bending without exceeding stress limits.
Fabrication involves carefully attaching the small, 75 μm diameter, actuator wires such that they can be guided through the natural curves of the bat’s body, and their pre-strain can be tuned after assembly. The heating power input waveforms are shaped by a custom-built power control devise for multi-functional SMA wires such that the flapping motion mimics that of the natural flyer. The prototype has been tested to 100,000 cycles and installed in an exhibit at the Raleigh Museum of Natural Science as an example of how technology often finds inspiration from nature.
Two Independent Pathways for Self-Recognition in Proteus mirabilis Are Linked by Type VI-Dependent Export
Authors: Wenren Larissa M. , Sullivan Nora L. , Cardarelli Lia , Septer Alecia N. , Gibbs Karine A. 
Published: July 2013

ABSTRACT

Swarming colonies of the bacterium
Proteus mirabilis
are capable of self-recognition and territorial behavior. Swarms of independent
P. mirabilis
isolates can recognize each other as foreign and establish a visible boundary where they meet; in contrast, genetically identical swarms merge. The
ids
genes, which encode self-identity proteins, are necessary but not sufficient for this territorial behavior. Here we have identified two new gene clusters: one (
idr
) encodes
rhs
-related products, and another (
tss
) encodes a putative type VI secretion (T6S) apparatus. The Ids and Idr proteins function independently of each other in extracellular transport and in territorial behaviors; however, these self-recognition systems are linked via this type VI secretion system. The T6S system is required for export of select Ids and Idr proteins. Our results provide a mechanistic and physiological basis for the fundamental behaviors of self-recognition and territoriality in a bacterial model system.

IMPORTANCE
Our results support a model in which self-recognition in
P. mirabilis
is achieved by the combined action of two independent pathways linked by a shared machinery for export of encoded self-recognition elements. These proteins together form a mechanistic network for self-recognition that can serve as a foundation for examining the prevalent biological phenomena of territorial behaviors and self-recognition in a simple, bacterial model system.
Interspecies Communication among Commensal and Pathogenic Streptococci
Authors: Cook Laura C. , LaSarre Breah , Federle Michael J. 
Published: July 2013

ABSTRACT

Quorum sensing (QS) regulates diverse and coordinated behaviors in bacteria, including the production of virulence factors, biofilm formation, sporulation, and competence development. It is now established that some streptococci utilize Rgg-type proteins in concert with short hydrophobic peptides (SHPs) to mediate QS, and sequence analysis reveals that several streptococcal species contain highly homologous Rgg/SHP pairs. In group A streptococcus (GAS), two SHPs (SHP2 and SHP3 [SHP2/3]) were previously identified to be important in GAS biofilm formation. SHP2/3 are detected by two antagonistic regulators, Rgg2 and Rgg3, which control expression of the
shp
genes. In group B streptococcus (GBS), RovS is a known virulence gene regulator and ortholog of Rgg2, whereas no apparent Rgg3 homolog exists. Adjacent to
rovS
is a gene (
shp1520
) encoding a peptide nearly identical to SHP2. Using isogenic mutant strains and transcriptional reporters, we confirmed that RovS/SHP1520 comprise a QS circuit in GBS. More important, we performed experiments demonstrating that production and secretion of SHP1520 by GBS can modulate Rgg2/3-regulated gene expression in GAS in
trans
; likewise, SHP2/3 production by GAS can stimulate RovS-mediated gene regulation in GBS. An isolate of
Streptococcus dysgalactiae
subsp.
equisimilis
also produced a secreted factor capable of simulating the QS circuits of both GAS and GBS, and sequencing confirms the presence of an orthologous Rgg2/SHP2 pair in this species as well. To our knowledge, this is the first documented case of bidirectional signaling between streptococcal species in coculture and suggests a role for orthologous Rgg/SHP systems in interspecies communication between important human pathogens.

IMPORTANCE
Pathogenic streptococci, such as group A (GAS) and group B (GBS) streptococcus, are able to persist in the human body without causing disease but become pathogenic under certain conditions that are not fully characterized. Environmental cues and interspecies signaling between members of the human flora likely play an important role in the transition to a disease state. Since quorum-sensing (QS) peptides have been consistently shown to regulate virulence factor production in pathogenic species, the ability of bacteria to signal via these peptides may prove to be an important link between the carrier and pathogenic states. Here we provide evidence of a bidirectional QS system between GAS, GBS, and
Streptococcus dysgalactiae
subsp.
equisimilis
, demonstrating the possibility of evolved communication systems between human pathogens.