Vibration Ring

A vibration ring is provided to remove vibratory energy from a machine driveline. The vibration ring includes a compression cage configured to generate vibratory excitation within a material. The material is configured to generate an electric charge dissipated through or harvested by an electric circuit

A Review of Noise and Vibration Control Technologies for Rotorcraft Transmissions

An expanded commercial use of rotorcraft can alleviate runway congestion and improve the accessibility of routine air travel. To date, commercial use has been hindered by excessive cabin noise. The primary noise source is structure-borne vibration originating from the main rotor gearbox. Despite significant advancements in gear design, the gear mesh tones generated often exceed 100 dB. This paper summarizes the findings of a literature survey of vibration control technologies that serve to attenuate this vibration near the source, before it spreads into the airframe and produces noise. The scope is thus limited to vibration control treatments and modifications of the gears, driveline, housing structures, and the strut connections to the airframe. The findings of the literature are summarized and persistent and unresolved issues are identified. An emphasis is placed on components and systems that have been demonstrated in flight vehicles. Then, a discussion is presented of emerging technologies that have the potential to make significant advancements over the state of the art

Code-mixing and Code Switching in Wylvera W.’s Novel Geranium Blossom: Saat Jarak Menguji Cinta: Their Types and Reasons

Code-mixing constitutes a mixing of two codes or languages which is usually without a change of topic, whereas code-switching shows a change made from one language or language variety to another one. There are three types of code-mixing including insertion, alternation, and congruent lexicalization as proposed by Muysken (2000: 3), and code-switching is of four types, that is, inter-sentential switching, intra-sentential switching, emblematic/ tag switching, and intra-word switching (Poplack, 2004: 589). The uses of code-mixing and code-switching are quite common in bilingual or multilingual communities in an informal situation. Based on these two terms (codemixing and code-switching), this paper was then made to describe the types and reasons of code-mixing and code switching in Wylvera W.’s novel Geranium Blossom: Saat Jarak Menguji Cinta written in 2015. The types of code-mixing which are used in the novel are all the three types above (i. e. insertion, alternation, and congruent lexicalization), and those of code-switching which are used are only two from the above four types (i. e. inter-sentential switching and emblematic/ tag switching). It was found that, in terms of code-mixing, insertion was used more than the other types of code-mixing, and, in terms of code-switching, it is inter-sentential switching which was used more than the other types of code-switching. This research applied a descriptive qualitative method as proposed by Creswell (2009: 4) in the analysis of the matters concerning code-mixing and code-switching in the novel.   Keywords: code-mixing, insertion, alternation, congruent lexicalization, codeswitchin

Regeneration of Woodland Vegetation after Deer Browsing in Sharon Woods Metro Park, Franklin County, Ohio

Author Institution: Dept of Evolution, Ecology & Organismal Biology, The Ohio State University, Columbus, OHOverbrowsing by deer can decrease plant abundance and change plant species composition, especially in isolated forest fragments. Sharon Woods Metro Park, Franklin County, OH is a 308 ha suburban woodland preserve that had a deer population of 347 individuals in 1992 (112 deer/km2), which was subsequently reduced to the currently maintained level of ~40 individuals (14 deer/km2). Deer exclosures (~0.4 ha) established in 1990 in three habitats were used to compare vegetation that recovered under complete protection with that which had sustained continued browsing. Tree seedlings, herbaceous and shrub species richness, diversity, and floristic quality were quantified in browsed and fenced treatments as indicators of plant diversity. Percent ground cover was assayed as a measure of plant biomass. Total percent ground cover was significantly lower in browsed treatments in two of the three habitats. Species richness and floristic quality of forest floor species were consistently, though not significantly, lowered in browsed treatments where the more disturbance-tolerant native species increased in frequency and abundance. Reduced deer browsing has allowed some plant species to regenerate but not others. For example, pawpaw (Asimina triloba), American beech (Fagus grandifolia), and jewelweed (Impatiens capensis) are disturbance tolerant and/or unpalatable species that may inhibit regeneration of more sensitive species under browsing pressure. A further reduction in deer density to ~4 deer/km2 and continued vegetation monitoring are recommended next steps for vegetation management at Sharon Woods

Design and Testing of a Dynamically-Tuned Magnetostrictive Spring with Electrically-Controlled Stiffness

This paper details the development of an electrically-controlled, variable-stiffness spring based on magnetostrictive materials. The device, termed a magnetostrictive Varispring, can be applied as a semi-active vibration isolator or switched stiffness vibration controller for reducing transmitted vibrations. The Varispring is designed using 1D linear models that consider the coupled electrical response, mechanically-induced magnetic diffusion, and the effect of internal mass on dynamic stiffness. Modeling results illustrate that a Terfenol-D-based Varispring has a rise time almost an order of magnitude smaller and a magnetic diffusion cut-off frequency over two orders of magnitude greater than a Galfenol-based Varispring. The results motivate the use of laminated Terfenol-D rods for a greater stiffness tuning range and increased bandwidth. The behavior of a prototype Varispring is examined under vibratory excitation up to 6 MPa and 25 Hz using a dynamic load frame. For this prototype, stiffness is indirectly varied by controlling the excitation current. Preliminary measurements of continuous stiffness tuning via sinusoidal currents up to 1 kHz are presented. The measurements demonstrate that the Young's modulus of the Terfenol-D rod inside the Varispring can be continuously varied by up to 21.9 GPa. The observed stiffness tuning range is relatively constant up to 500 Hz, but significantly decreases thereafter. The stiffness tuning range can be greatly increased by improving the current and force control such that a more consistent current can be applied and the Varispring can be accurately tested at a more optimal bias stress

Spring Tire

The spring tire is made from helical springs, requires no air or rubber, and consumes nearly zero energy. The tire design provides greater traction in sandy and/or rocky soil, can operate in microgravity and under harsh conditions (vastly varying temperatures), and is non-pneumatic. Like any tire, the spring tire is approximately a toroidal-shaped object intended to be mounted on a transportation wheel. Its basic function is also similar to a traditional tire, in that the spring tire contours to the surface on which it is driven to facilitate traction, and to reduce the transmission of vibration to the vehicle. The essential difference between other tires and the spring tire is the use of helical springs to support and/or distribute load. They are coiled wires that deform elastically under load with little energy loss

NASA's Magnetic Gearing Research for Electrified Aircraft Propulsion

This paper presents an overview of the magnetic gearing research being conducted at NASA. First, the research is motivated through an in-depth discussion of the Agency-level aeronautics vision, the benefit of geared drivetrains, the barriers to applying mechanical gears in future aircraft concepts with electrified aircraft propulsion, and the characteristics of magnetic gears that allow them to overcome said barriers. Next, the principles of operation and current limitations of magnetic gears are discussed in the context of future electrified aircraft. Then, the authors' vision for the magnetic gearing research that will be needed to enable the next generation of electrified aircraft is presented. Lastly, the recent and ongoing magnetic gearing research at NASA is described, with a focus on the development and capabilities of a new rotating test rig and new static measurements of an in-house prototype. Results and lessons learned thus far are summarized

Ideology in Marine Ritual Discourse of Acehnese Speech Community

This study is about what particular people belong to the particular ethnic have in mind as their ideology to see the environment, reflected from traditional fishing ritual in Acehnese speech community under the eco-linguistic perspective. In addition, with reference to social praxis, ecolinguistics recognizes three dimensions, namely ideological, sociological, and biological dimensions relating to the exploitation of the environment for fishing through ritual speech. The purpose of this study is to determine the ideology reflected in the speech. The study employed a qualitative research methodology, utilizing a phenomenological approach. The study makes use of verbal expressions expressed by naval commanders, gathered through a combination of participatory observation and comprehensive interviews at a central location of fish market and sanctuary in Banda Aceh, Aceh Indonesia. The data collected serve as the basis for the analysis and interpretation of the research findings. The respected ideology was then compared to the concept of ecosophy. The results of the analysis show that the ritual holistically contains the ideology of environmental preservation. The efforts to assist the natural, social, and spiritual preservations, specifically in marine environments, are obviously detected in the discourse. The ideology offered is in accordance with the concept of ecosophy, which includes beneficial discourse. However, part of the utterances also reflect the ambivalent discourse, but not the destructive one

Dynamic Characterization of Galfenol (Fe81.6Ga18.4)

Galfenol has the potential to transform the smart materials industry by allowing for the development of multifunctional, load-bearing devices. One of the primary technical challenges faced by this development is the very limited experimental data on Galfenol's frequency-dependent response to dynamic stress, which is critically important for the design of such devices. This report details a novel and precise characterization of the constitutive behavior of polycrystalline Galfenol (Fe81.6Ga18.4) under quasi-static (1 Hz) and dynamic (4 to 1000 Hz) stress loadings. Mechanical loads are applied using a high-frequency load frame. Quasi-static minor and major hysteresis loop measurements of magnetic flux density and strain are presented for constant electromagnet currents (0 to 1.1 A) and constant magnetic fields 0 to 14 kA/m (0 to 180 Oe). The dynamic stress amplitude for minor and major loops is 2.88 and 31.4 MPa (418 and 4550 psi), respectively. Quasi-static material properties closely match published values for similar Galfenol materials. Quasi-static actuation responses are also measured and compared to quasi-static sensing responses; the high degree of reversibility seen in the comparison is consistent with published measurements and modeling results. Dynamic major and minor loops are measured for dynamic stresses up to 31 MPa (4496 psi) and 1 kHz, and the bias condition resulting in maximum, quasi-static sensitivity. Eddy current effects are quantified by considering solid and laminated Galfenol rods. Three key sources of error in the dynamic measurements are accounted for: (1) electromagnetic noise in strain signals due to Galfenol's magnetic response, (2) error in load signals due to the inertial force of fixturing, and (3) phase misalignment between signals due to conditioning electronics. For dynamic characterization, strain error is kept below 1.2 percent of full scale by wiring two collocated gauges in series (noise cancellation) and through leadwire weaving. Inertial force error is kept below 0.41 percent by measuring the dynamic force in the specimen using a nearly collocated piezoelectric load washer. The phase response of all conditioning electronics is explicitly measured and corrected for. In general, as frequency is increased, the sensing response becomes more linear because of an increase in eddy currents. As frequency increases above approximately 100 Hz, the elbow in the strain-versus-stress response disappears as the active (soft) regime stiffens toward the passive (hard) regime. Under constant-field conditions, the loss factors of the solid rod peak between 200 and 600 Hz, rather than exhibiting a monotonic increase. Compared to the solid rod, the laminated rod exhibits much slower increases in hysteresis with frequency, and its quasi-static behavior extends to higher frequencies. The elastic modulus of the laminated rod decreases between 100 and 300 Hz; this trend is currently unexplained