International Telemetering Conference Proceedings / October 28-31, 1985 / Riviera Hotel, Las Vegas, Nevada / A novel source of noise is identified and described in this study. If a continuous recording medium is less than perfectly uniform, a given quantity may be recorded differently at different locations in the medium. Inadvertent “encoding” occurs, embedding noise in the signal. Symmetrical sideband noise power results from amplitude and phase modulation of the signal stream by the nonuniform recording medium. “Write noise”, so-called because writing is required, is correlated in amplitude with signal amplitude, and its mean frequency is the signal frequency. It is the dominant noise source for the current generation of recorders and tapes; its power spectrum is almost the same as the power spectrum of the signal. The ratio of standard deviation to mean value of the signal envelope when recording cw signals is an absolute measure of tape quality independent of record level, tape speed, and track width, and establishes an available signal-to-noise ratio which cannot be exceeded. It is assumed that the recorder output has a normal amplitude distribution about its mean value. Theory is confirmed by experiment, within experimental error, for cw and digital recording.

This study examines social factors in songwriting collaborations with the aim to understand the inner workings of co-writes. Previous research indicates significant benefits with songwriting collaborations, both related to productivity and creativity (e. g. Bennett 2012, Littleton &amp; Mercer, 2012). Nonetheless, it can be creatively frustrating to make music in a collaboration that does not work like expected. What is significant about the musical work in a fulfilling co-write? And how can you find your way out of struggle together? While there is qualitative research on musical collaborations, this study is distinguished by that the researcher is partaking in several co-writes. Six collaborations were documented with various methods, including video and audio recordings, post-hoc reflection, semi-structured interviews and communication memos. The comprised material was transcribed and analyzed in order to reveal socio-musical tendencies in the co-writes. The research suggests four socio-musical categories for explaining actions in co-writing sessions – ‘Artistic Concept’, ‘Concept’, ‘Meta’ and ‘External’. The two first categories are more artistically connoted, where the last two are more socially signified. During the study, purely artistic actions were outweighed by more socially connoted actions in the co-writes. This resulted in a fairly low generation of musical material per session. The prevalence of bonding may be seen as a way of avoiding rejection, which is a possible outcome when suggesting musical ideas (Bennett, 2012). The sessions that were most fulfilling for the researcher were characterized of nonverbal, musical means rather than linguistic ones - where the collaborators didn’t talk about the music, but connected through songwriting. High rates of fulfillment connected to musical communication was also supported by numerous co-writers in the project. / <p>Medley of songs created in the project. </p>

Preferred especially for a Last Level Cache (LLC) due to its high retention and tolerance capabilities, Spin-Transfer Torque Random Access Memory (STTRAM) is an emerging and a promising Non-Volatile Memory (NVM) technology. To switch the magnetization of a Magnetic Tunnel Junction (MTJ), the amount of current needed is very high (~100μA per bit). For a full cache line (512-bit) write, this extremely high current results in a voltage droop in the conventional cache architecture. Due to this droop, the write operation fails especially when the farthest bank of the cache is accessed. In this thesis, we perform an analysis of the voltage droop across the STTRAM Last Level cache and then propose a new cache micro-architecture to mitigate the droop problem and make the write operations successful. Instead of continuously writing the entire cache line (512-bit) in a single bank, the proposed architecture writes 64-bits in multiple physically separated locations across the cache. The voltage droop issue for crossbar memories such as Resistive RAM (ReRAM) has been pointed out but however, similar issue for STTRAM has never been investigated. In this study, we perform voltage droop analysis on the conventional STTRAM LLC while performing write/read operation with a simulation circuit model. Our investigation reveals that this problem exists for the write operation in a STTRAM LLC when we try to access the farthest bank in the cache. We propose a droop-mitigation Architecture which reduces the droop significantly. The effectiveness of this proposed architecture on the cache parameters such as latency and energy are compared with the conventional architecture for against various benchmarks. From the simulation results obtained (both circuit and micro-architectural), compared to the conventional architecture, the proposed architecture incurs 1.95% IPC and 5.21% energy for a 8MB last level cache.

Ultraviolet-Assisted Direct Ink Write (UV-DIW) is a material extrusion additive manufacturing (AM) technology in which a viscous ink, often at room temperature, is selectively extruded through a translating nozzle to selectively deposit material. The extruded ink is solidified via UV irradiation (photocuring) and three-dimensional parts are created by repeating the process in a layer-by-layer fashion. UV-DIW is an attractive AM technology due to its ability to (1) extrude highly viscous inks (i.e. >10,000 Pa·s if ink exhibits shearthinning behavior) (2) the promise of leveraging the broad photopolymer material library and chemistries established for other AM technologies capable of processing photopolymers and (3) the promise of processing a wide range of inks, which enables the fabrication of metal, ceramic, polymer, bio-based, and multi-material parts. Currently, the technology faces a few shortcomings including (1) limited material selection for UV-DIW due to requirement for inks to be photocurable and limited mechanical properties of photocurable materials (2) lack of feature resolution and topological complexity of printed parts and (3) lack of material screening models providing robust definition of the material requirements (e.g., viscosity, cure time, strength) for successful UV-DIW printing. To address these shortcomings, the goal of this work is to gain a fundamental understanding of the rheological and reactive properties required for successful Ultraviolet-Assisted Direct Ink Write (UV-DIW). The first approach to answering the fundamental research question is establishing the existing rheology experiments used to characterize DIW inks and the relationships between rheology and printability. An in-depth literature review of the techniques and relationships was compiled to better understand ink requirements for successful printing (Chapter 2). This broad survey is not limited to only UV-DIW, but includes all variations of DIW. The first part of the review provides a summary of the rheological experiments that have been used to characterize a wide variety of DIW inks. The second part of this review focuses on the connections between rheology and printability. This survey helps identify the required rheological properties for successful printing that is then used throughout the rest of this work. Additionally, this review identifies shortcomings in current work and proposes areas for future work. From this exhaustive literature review, a systematic roadmap was developed that investigators can follow to quickly characterize the printability of new inks, independent of that ink's specific attributes (Chapter 3). The roadmap simplifies the trends identified in literature into a brief and intuitive guide to the rheology experiments relevant to DIW printing and the relationship between those experiment and printing results. The roadmap was demonstrated by evaluating the printability of two inks: (1) a silicone ink with both yield-stress and reactive curing behavior and (2) urethane acrylate inks with photocuring behavior. Experimental printing studies were used to support the conclusions on printability made in the roadmap. The second main approach focuses on the development of three novel UV-DIW inks to address the current limited material selection for UV-DIW and help better understand the rheological and reactive properties required for successful printing. For the three novel UVDIW inks, the iterative process of ink synthesis, analysis of ink rheology, and printability evaluation was detailed. Data from the development process contributed to gaining a fundamental understanding of how rheology and reactivity affect printability. The three inks each had novel rheological properties that impacted their printing behavior: (1) photocuring (2) yield-stress behavior + photocuring and (3) photocuring + thermal curing. Additionally, each ink had unique properties that expands material selection for UV-DIW including (1) an all-aromatic polyimide possessing a storage modulus above 1 GP a up to 400 °C (Chapter 4), (2) a styrene butadiene rubber (SBR) nanocomposite with elongation at break exceeding 300 % (Chapter 5), and (3) a dual-cure ink enabling the printing of inks containing over 60 vol% highly opaque solids (Chapter 6). The third approach details the development of two UV-DIW process models to better understand the process physics of the UV-DIW process and give insight to the properties of a successful ink. The first process model uses data from photorheology experiments to model how a photocurable ink spreads upon deposition from the nozzle, accounting for transient UV curing behavior (Chapter 7). This model allows for the rapid evaluation of an ink's behavior during the solidification sub-function of UV-DIW solely based on its rheology, without the time-consuming process of trial-and-error printing or complex computer simulations. The second process model combines modeling with a novel experimental method that uses a UV photorheometer to accurately characterize the relationship between cure depth and UV exposure for a wide range of photopolymers (Chapter 8). This model helps understand an inks photocuring behavior and ensure a sufficient cure depth is produced to adhere to the previous layer in UV-DIW printing. Lastly, two UV-DIW process modifications are introduced to address research gaps of printing high resolution features and limited material selection. A hybrid DIW + Vat Photopolymerization system is presented to improve the feature size and topographical complexities of parts, while still retaining UV-DIW's ability to print with very high viscosity photoresins (Chapter 9). A high temperature Heated-DIW system is presented to heat inks to over 300 °C and ultimately enable printing of poly(phenylene sulfide) aerogels (Chapter 10). In enabling the DIW of poly(phenylene sulfide) aerogels, the production of ultra-lightweight thermally insulating components for applications in harsh environments is enabled. With the use of additive manufacturing, hierarchical porosity on the macroscale is enabled in addition to the meso-scale porosity inherent to the aerogels. / Doctor of Philosophy / Direct Ink Write (DIW) is a type of three-dimensional (3D) printing that is used to automatically produce a range of 3D geometries. Specifically, the DIW process selectively extrudes a viscous ink, similar in consistency to peanut butter or toothpaste, through a small moving nozzle to create the features of each layer. This process is like using a frosting bag to decorate a cake with icing. Three-dimensional parts are created by repeating this process and depositing layer on top of layer. While seemingly a straightforward process, it remains relatively unclear what properties an ink needs to produce quality parts. To produce quality parts, the ink first needs to be extruded from the nozzle to form homogenous beads with a constant width and free from breaks. Second, the extruded ink needs to retain the shape that it was deposited in. If the ink spreads excessively, the as-deposited features will be lost and a part resembling a blob will be produced. Lastly, the ink deposited on the first layers needs to have enough strength to support the weight of the part. Otherwise, the part will collapse akin to the Leaning Tower of Pisa. To achieve all three steps and produce a quality part, a successful ink needs to be able to flow through the nozzle and then solidify upon deposition. This work focuses on a specific process called Ultraviolet-Assisted Direct Ink Write (UV-DIW) where materials that solidify when exposed to UV light, called photopolymers, are printed. Currently, the properties of the inks, especially how they cure when exposed to UV light, that produce successful printing remains unclear. This work focuses on understanding how the properties of the photopolymer inks affect the printing behavior of the ink. The ultimate goal of this work is to develop guidelines for the properties of successful inks which will help others develop the next generation of materials printed via UV-DIW. Specifically, experiments are used study how inks behave when they flow through the nozzle (rheology) and then solidify when exposed to UV light (reactivity). This behavior is then connected to the inks printing behavior (printability). In working to better understand the connection between rheology, reactivity, and printability multiple approaches were used. These approaches include the development of new materials for printing via UV-DIW, development of a modified UV-DIW printing process that reduces the size of the printed features, and development of models to predict how inks will behave during printing. The new plastic materials that were developed and successfully printed via UV-DIW have outstanding properties including remaining strong up to 400 °C, being extremely flexible, and a plastic containing a large fraction of a solid filler. With each new material, the formulation was varied to change the inks rheological and reactive properties until successful UV-DIW was enabled. Each new formulation introduced material capabilities not previously available to DIW 3D printing. Then, A modified UV-DIW process was developed that takes advantage of the reactivity of the photopolymers to enable the printing of high-resolution features and shapes not previously possible via DIW 3D printing. In this novel process, a projector is used to project patterned UV light at the material and selectively cure small portions of the deposited material, instead of curing all the deposited material. After printing, the uncured ink is washed away resulting in features much smaller than what can be produced when directly extruding them. Finally, the developed process models use the relatively simple rheology and reactivity experiments, to predict how an ink behaves during the UV-DIW process. Using the results of these experiments and the developed models, the inks behavior during the printing process is predicted. These models allow for the properties of new inks to be quickly measured and their printing behavior predicted. New ink formulations can be quickly screened, and optimal process parameters predicted. Overall, this work produces guidelines for the rheological and reactive properties required of a photopolymer ink to produce successful UV-DIW printing. Future researchers can use these guidelines to develop the next generation of materials printed via UV-DIW more easily.

No description available.

The fabrication of Bit Patterned Media has become highly developed, with samples fabricated of over 1.5 Tb/in2. However, writing BPM presents significant challenges and for a system to be developed studies must be made into writing. This work has investigated a number of effects on the writing of Bit Pattterned Media (BPM). Magnetostatic interactions between islands have been used to investigate the effect of patterns of magnetisation on the write-window of a BPM system. A method of acquiring a distribution of patterns was determined and used to vary the probability of a target island switching. This showed that magnetostatic interactions between islands could be modelled as a variation in the anisotropy field. The relationship between island parameter distributions, the write-window and error rates was also explored. The effect of non-Gaussian distributions on the error in a BPM system was studied. It was concluded that tails of island parameter distributions have a significant effect on errors occurring in the write process of a BPM system. Therefore an accurate distribution of island parameters must be known and the necessary accuracy of such a distribution was established. Furthermore a model of BPM writing where the shape of the head field is approximated from the value at the maximum head field gradient will not account for switching in the tail of a real head field. This led onto a study of the ideal write point in BPM. In conventional recording theory the medium is designed to switch when the applied head field is at the position of its maximum gradient, which produces sharp transitions between magnetisation regions. A natural assumption in BPM is that the system could be optimised by setting the island switching field in a similar manner. This strategy of optimisation was investigated to see what gives the minimum error, or maximum write-window. It was concluded that optimisation could not be solely based on the maximum head field gradient, furthermore assuming the shape of the head field from this point will not produce an accurate estimation of the error in a BPM system.

A research project was undertaken to integrate Ultrasonic Consolitation (UC) and Direct-Write (DW) technologies into a single apparatus to fabricate embedded electrical systems within an ultrasonically consolidated metallic enclosure. Process and design guidelines were developed after performing fundamental research on the operational capabilities of the implemented system. In order to develop such guidelines, numerous tests were performed on both UC and DW. The results from those tests, as well as the design and process guidelines for the fabrication of an embedded touch switch, can be used as a base for future research and experimentation on the UC-DW apparatus. The successful fabrication of an embedded touch switch proves the validity of the described design and process parameters and demonstrates the usefulness of this integration.

An informational source where teachers and teacher-candidates could gain a functional knowledge of contingency management techniques had not been developed. A programed text was written to provide this source. Five teachers and teacher-candidates were exposed to the text for a period of three days. As a result of this exposure, learning gains, significant at the 0.01 level, were found in the students' abilities (a) to write behavioral prescriptions and (b) to write the principles of contingency management when presented with open-ended questions pertaining to these principles.

Despite the need for accurate oil and gas reserves estimates which honor disclosure requirements of the United States Securities and Exchange Commission (SEC), a number of exploration and production companies have allegedly overstated and subsequently written down their reserves during the last 20 years. Reserves write-downs are of great interest to numerous groups involved in the reserves estimation process and outcome, including estimators, managers, investors, creditors, and regulators. Considering the magnitude and nature of some alleged overstatement cases, it appears that some of these parties may benefit from a better understanding of reserves reporting, the relative risk of overstatements, the regulatory environment and enforcement procedures, and identifying questionable reserves data. After discussing the context and importance of reserves and write-downs, there is a detailed examination of the SEC, including the agency's reserves reporting requirements, and their enforcement methods. A number of alleged overstatement and write-down "case studies" are presented, with details on the specific Federal Laws alleged to have been violated by corporations or individuals and then cited by the SEC and shareholder lawsuits. We also conclude that there may be greater write-down potential due to the updated SEC reserves reporting guidelines. A comprehensive series of systematic questions have been compiled and quick-look graphical techniques have been developed that may be used to gain insight into -and potentially raise questions about- an operator's reserves data.

This study examines the timeliness of write-downs taken by U.S. financial institutions during the financial crisis of 2007-2008. The timeliness of write-downs is measured by benchmarking the quarterly accounting write-down schedule with the devaluation schedule implied by credit indices such as the ABX. The results show that accounting write-downs are less timely than the devaluations implied by credit indices. In a cross-sectional analysis of the determinants of the timeliness of write-downs, I document that higher corporate governance quality is positively related to timelier write-downs. Furthermore, I observe that regulatory investigations and litigation pressure are positively related to the timeliness of write-downs, whereas the write-downs by firms with more complex exposures, higher financial leverage, and tighter regulatory constraints are less timely. In addition, I control for numerous exposure-specific characteristics and document that less risky exposures, and exposures that were affected later during the financial crisis, were written down later. Regarding the consequences of timeliness, this study finds that the exposure to risky assets is reflected faster in stock returns for firms with timelier write-downs.