A Study of the Use of Borates in Semi-Chemical Pulping

The purpose of this project was to identify sodium metaborate as a pulping chemical in semi-chemical pulping with soda ash. The experimental design included four digester cooks with 0%, 10%, 20%, and 40% addition of.the borate compound. The resulting yields were 81. 3 %, 79. 2%, 77.4 %, and 7 4. 5% respectively. Therefore, under the definition of pulping, sodium metaborate was considered a pulping chemical. The pulps were mechanically refined. The resulting screened rejects increased with increasing borate addition. Handsheets were made and tested for strength and optical properties. The tensile and mull en strengths of the handsheets increased with addition of borates up to 20%, but degradation of the bonding properties occurred at high addition levels (40%). The tear strength increased dramatically (up to 24.1%) with the addition of borates to the pulping liquor. Brightness and visual color were slightly improved. The results indicate that the sodium metaborate was an effective pulping chemical with a tendency to be selective in delignification. Further work should be performed to compare the effect of substitution against conventional non-borate pulping, and possible changes in bleached pulp quality

Frequency dependence of partial discharge initiation voltages with embedded electrodes

Partial discharge initiation voltages of a dielectric insulation material exposed to ac voltages show little dependence on frequency in the power frequency range. This results after significant voltage conditioning at the measured frequencies with samples configured for embedded electrodes. Comparison to previously published results is made.Center for Electromechanic

Intelligent Microgrids

Center for Electromechanic

Photoionization of photoexcited cesium

A new method for obtaining the cross section for photoionization of photoexcited cesium is presented. The salient feature of this experiment is to use three crossed beams, i.e., two light beams intersecting a beam of cesium atoms. The cross section is determined by counting the ions produced by the two step process: Cs (6S) + h[upsilon]₁ --\u3e Cs (6P) ; Cs (6P) + [upsilon]₂ --\u3e Cs⁺ + e⁻ The relative cross section for the second step has been obtained from threshold (5060 Å) to 2500 Å. The excitation light source used in obtaining this cross section was a rf resonance lamp, but the possibility of using a GaAs laser as this light source was also investigated. A GaAs laser was thermally tuned to the 6S - 6P transition wavelength in cesium, 8521 Å, and it was found that in this way the hyperfine levels of the ground state of cesium could be selectively depopulated. Although excellent results were obtained in this portion of the study, the low duty cycle of the lasers that we had available made them unsuitable for the photoionization experiment --Abstract, page i

Experimental Test bed to De-Risk the Navy Advanced Development Model

This paper presents a reduced scale demonstration test-bed at the University of Texas’ Center for Electromechanics (UT-CEM) which is well equipped to support the development and assessment of the anticipated Navy Advanced Development Model (ADM). The subscale ADM test bed builds on collaborative power management experiments conducted as part of the Swampworks Program under the US/UK Project Arrangement as well as non-military applications. The system includes the required variety of sources, loads, and controllers as well as an Opal-RT digital simulator. The test bed architecture is described and the range of investigations that can be carried out on it is highlighted; results of preliminary system simulations and some initial tests are also provided. Subscale ADM experiments conducted on the UT-CEM microgrid can be an important step in the realization of a full-voltage, full-power ADM three-zone demonstrator, providing a test-bed for components, subsystems, controls, and the overall performance of the Medium Voltage Direct Current (MVDC) ship architecture.Center for Electromechanic

Factors Contributing to Streamer Morphology

Recent work shows that the range of morphology of anode streamers in liquid dielectric breakdown is predicted when it is represented as stochastic growth of a branching fractal tree. This model may be analogous to the critical volume model of breakdown used in gases. Assuming there is a relationship, leads to a concept of how affecting the electron production and recombination rates in a fluid can affect streamer behavior. These concepts were tested by measuring the effect on streamer behavior due to adding a commercial antistatic additive to toluene. The results were consistent with the concepts of the model but insufficient to define the limits of the model's applicability.Center for Electromechanic

Dynamic Load and Storage Integration

Modern technology combined with the desire to minimize the size and weight of a ship’s power system are leading to renewed interest in more electric or all electric ships. An important characteristic of the emerging ship power system is an increasing level of load variability, with some future pulsed loads requiring peak power in excess of the available steady– state power. This inevitably leads to the need for some additional energy storage beyond that inherent in the fuel. With the current and evolving technology, it appears that storage will be in the form of batteries, rotating machines, and capacitors. All of these are in use on ships today and all have enjoyed significant technological improvements over the last decade. Moreover all are expected to be further enhanced by today’s materials research. A key benefit of storage is that, when it can be justified for a given load, it can have additional beneficial uses such as ride-through capability to restart a gas turbine if there is an unanticipated power loss; alternatively, storage can be used to stabilize the power grid when switching large loads. Knowing when to stage gas turbine utilization versus energy storage is a key subject in this paper. The clear need for storage has raised the opportunity to design a comprehensive storage system, sometimes called an energy magazine, that can combine intermittent generation as well as any or all of the other storage technologies to provide a smaller, lighter and better performing system than would individual storage solutions for each potential application.Center for Electromechanic

Cross-platform validation of notional baseline architecture models of naval electric ship power systems

To support efforts in assessing the relative merit of alternative power system architectures for future naval combatants, the Electric Ship Research and Development Consortium (ESRDC) has developed notional baseline models for each of the primary candidate architectures currently considered, medium-voltage DC (MVDC), conventional 60 Hz medium-voltage (MVAC), and high-frequency medium-voltage (HFAC). Initial efforts have focused on the development of a consistent set of component models, of which the system models can be comprised, and the basic definition of the system models. The broader objectives of the consortium, however, go beyond the definition of the baseline models. The focus is on the process by which the models are implemented in software and validated, the process by which the performance of the disparate system models are objectively and quantitatively assessed and compared, and, ultimately, the process by which the relative merits of the architectures may be assessed. This paper focuses specifically on cross-platform component validation.Center for Electromechanic

Cortical Activity Associated With Changes in Sensory Contributions During Standing Balance Control

Maintenance of safe upright static stance regardless of sensory input is imperative for completing activities of daily living required for high quality of life. The current body of work aims to the potential involvement of the cortex in standing balance by examining the frequency of cortical activity associated with manipulation of task challenge and sensory contributions. The current study is focused manipulating sensory input (haptic touch, and vision) to explore if there was evidence of changes at the level fo cortex that may implicate cortical contributions in sensory processing during the control of stationary standing. Since altering sensory inputs will alter challenge it was necessary to determine the impact of changes in cortical activity related to changes in balance challenge independent of sensory status. It was hypothesized that increasing task challenge, by altering base of support, would result in an increase in theta frequency power ratio and a decrease in alpha frequency power ratio, specifically at frontocentral regions of the cortex. It was predicted that by including haptic touch there would be an increase in theta frequency power ratio and a decrease in alpha frequency power ratio, with accompanying increase in power in beta, delta, and gamma frequency bands around the Pz electrode. Finally, it was hypothesized that increasing visual availability would result in an increase in theta frequency power ratio and a decrease in alpha frequency power ratio, with accompanying increase in power in beta, delta, and gamma frequency bands around the Oz electrode. The study tested 12 healthy young subjects who performed 7 different tasks: 1) Tandem stance with eyes closed, 2) Narrow stance with eyes closed, 3) Standard stance with eyes closed, 4) Tandem stance with restricted visual field, 5) Tandem stance with eyes open but vision occluded, 6) Tandem stance eyes open, 7) Tandem stance with haptic touch. Cortical activity was measured using a 32 channel electroencephalography (EEG) system and balance control was measured from ground reaction forces used to calculate centre of pressure (COP). Frequency analysis was conducted and plotted topographically for qualitative evaluation. Mean power, within each band (delta, theta, alpha, beta, gamma) was calculated for specific electrode sites (Fz, Pz, Oz) and compared across task conditions. Mean ML (mediolateral) and AP (anteroposterior) COP and velocity was compared across task conditions. Overall, the manipulation of task challenge did result in significant changes in COP as a measure of task challenge, but there were only modest changes in cortical excitation that were largely characterized by an increase power of theta and alpha frequency. The main effect seen in frontocentral increase in power was observed for manipulation of task challenge (altered based of support) and changes in sensory inputs. With respect to changes in sensory information, the availability of haptic information was used to determine evidence of unilateral parietal cortical involvement that would have been consistent with the spatial specificity of the sensory input. Results supported the hypothesis of an increase in theta power and decrease in alpha power over the Pz electrode. With respect to visual inputs there was an expectation of varying activity in occipital power of theta and alpha frequency; when vision is available it was expected that theta power would increase and alpha power would decrease in the posterior regions of the cortex. Overall the current study confirms the expected impact of BOS and sensory input changes in on COP sway. However, the changes in cortical activity were more modest. Common across tasks of varying challenge (BOS or sensory) was increase in theta power in frontocentral region which may be associated with the N1 responses that are associated with reactive control. For sensory conditions there was some modest difference frequency of activity for haptic (Pz) and visual (Oz) though these were not statistically significant. The current study reinforces the involvement of the cortex in the control of reactive balance control but does not confirm a potential role for sensory processing. Future studies investigating delta, beta, and gamma frequency bands and sensory manipulation during standard stance should be undertaken to improve statistical power and reduction of potential confounding influence of differences associated with task challenge

Electrical Insulation Challenges for Rotating Machines Used on Future Electric Ships

The electrification of ships coupled with a demand for very high power and energy density raises challenges for insulation system designers for this market. The physical reason the design is challenging is that the electrical, mechanical, and thermal environment on a ship is sufficiently far from the land-based environment that key parts of the data and experience base needed for insulation system design do not exist.Center for Electromechanic