Increased capabilities of the 30-cm diameter Hg ion thruster

Some space flight missions require advanced ion thrusters which operate at conditions much different than those for which the baseline 30-cm Hg thruster was developed. Results of initial tests of a 30-cm Hg thruster with two and three grid ion accelerating systems, operated at higher values of both thrust and power and over a greater range of specific impulse than the baseline conditions are presented. Thruster lifetime at increased input power was evaluated both by extended tests and real time spectroscopic measurements

The solar gravitational figure: J2 and J4

The theory of the solar gravitational figure is derived including the effects of differential rotation. It is shown that J sub 4 is smaller than J sub 2 by a factor of about 10 rather than being of order J sub 2 squared as would be expected for rigid rotation. The dependence of both J sub 2 and J sub 4 on envelope mass is given. High order p-mode oscillation frequencies provide a constraint on solar structure which limits the range in envelope mass to the range 0.01 M sub E/solar mass 0.04. For an assumed rotation law in which the surface pattern of differential rotation extends uniformly throughout the convective envelope, this structural constraint limits the ranges of J sub 2 and J sub 4 in units of 10 to the -8th power to 10 J sub 2 15 and 0.6 -J sub 4 1.5. Deviations from these ranges would imply that the rotation law is not constant with depth and would provide a measure of this rotation law

The Rocketdyne Multifunction Tester. Part 2: Operation of a Radial Magnetic Bearing as an Excitation Source

The operation of the magnetic bearing used as an excitation source in the Rocketdyne Multifunction Tester is described. The tester is scheduled for operation during the summer of 1990. The magnetic bearing can be used in two control modes: (1) open loop mode, in which the magnetic bearing operates as a force actuator; and (2) closed loop mode, in which the magnetic bearing provides shaft support. Either control mode can be used to excite the shaft; however, response of the shaft in the two control modes is different due to the alteration of the eigenvalues by closed loop mode operation. A rotordynamic model is developed to predict the frequency response of the tester due to excitation in either control mode. Closed loop mode excitation is shown to be similar to the excitation produced by a rotating eccentricity in a conventional bearing. Predicted frequency response of the tester in the two control modes is compared, and the maximum response is shown to be the same for the two control modes when synchronous unbalance loading is not considered. The analysis shows that the response of this tester is adequate for the extraction of rotordynamic stiffness, damping, and inertia coefficients over a wide range of test article stiffnesses

Conference on Automated Decision-Making and Problem Solving, the Third Day: Issues Discussed

A conference held at Langley Research Center in May of 1980 brought together university experts from the fields of Control Theory, Operations Research, and Artificial Intelligence to explore current research in automation from both the perspective of their own particular disciplines and from that of interdisciplinary considerations. Informal discussions from the final day of the those day conference are summarized

The Effect of Individualized Nurse Report Cards and Unit Case Reports on the Awareness and Attitudes of Nurses towards CLABSI Contributing Factors

This DNP project examined the effect of unit case reports and individualized nurse report cards on nurses’ awareness of and attitudes toward central line-associated bloodstream infection (CLABSI) contributing factors. This project also sought to determine whether CLABSI incidences differed across units and if that was affected by nurses’ awareness of and attitudes toward CLABSI contributing factors. A convenience sample of registered nurses (RNs) across four medical units was included in this project. Of the 79 RNs who participated in providing feedback on this project, 48 RNs completed pre-implementation surveys, resulting in a response rate of 61%, and 53 completed post-implementation surveys resulting in a response rate of 67%. CLABSI RN Awareness and Attitudes pre- and post-implementation survey responses were compared using descriptive and inferential statistics. The analysis found no significant differences between pre-implementation and post-implementation survey responses and no significant differences between post-implementation responses across units. Included is a discussion on notable findings related to staff perceived readiness and receptiveness to the project intervention and implications for future study

Writing Conference Purpose and How It Positions Primary-Grade Children as Authoritative Agents or Passive Observers

A common practice in today’s primary-grade classrooms, teacher-student writing conferences are considered a vital component of instruction by accomplished writing teachers and advocates of process writing. Moreover, what teachers say and how they say it shapes those opportunities for student learning that are possible in classrooms. As such, building an understanding of the talk that ensues during primary-grade writing conferences, those purposes that such talk serves overall, and the significance of its pedagogical appropriateness is essential. Findings from a multiple-case study of conference enactment in both a kindergarten and a first-grade classroom illuminate the varying degrees of authoritative and dialogic discourses made available to child participants during conference interactions. These findings range from enactments that empower students to co-construct ideas and meaning with their teachers as dialogic partners (e.g., conferencing as verbal rehearsal, conferencing as criterion-specific collaboration), to those more indicative of traditional recitation patterns in which students are given little space to contribute to the conversation (e.g., conferencing as transcription activity, conferencing as find-and-fix correction). Findings also suggest the importance of conference purpose and writing-process phase in determining the role child writers are invited to assume within a given conference interaction

Suppression of Subsynchronous Vibration in the SSME HPFTP

Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump (HPFTP) hot-fire dynamic data evaluation and rotordynamic analysis both confirm that two of the most significant turbopump attributes in determining susceptibility to subsynchronous vibration are impeller interstage seal configuration and rotor sideload resulting from turbine turnaround duct configuration and hot gas manifold. Recent hot-fire testing has provided promising indications that the incorporation of roughened damping seals at the impeller interstages may further increase the stability margin of this machine. A summary of the analysis which led to the conclusion that roughened seals would enhance the stability margin is presented along with a correlation of the analysis with recent test data

The Iron Age I Structure on Mount Ebal: Excavation and Interpretation

Problem. The Iron Age I site on Mt. Ebal, discovered in 1980 by Adam Zertal and excavated between 1982 and 1989, has remained largely unknown by both the scholarly community and the public. No scholarly congress or colloquium has ever been held regarding the Mt. Ebal excavations. The Mt. Ebal excavations, however, may have important implications for reconstructing Israelite origins. This present study investigates the Mt. Ebal excavationand its results. Method. My study uses the comparative method and is divided into six chapters. Chapter 1 serves as in introduction, giving an overview of the investigation to be carried out in subsequent chapters. Chapter 2 analyzes the archaeological data from the Mt. Ebal site and compares it with both cultic and non-cultic materials in order to assess the nature of the site. Chapter 3 considers physical parallels for the Ebal site. Chapter 4 compares each of the physical elements of the Ebal site with biblical and other literary data relevant to a cultic interpretation. Chapter 5 examines the site in its historical and sociological position among the new settlement sites of the central hill-country in Iron Age I. Chapter 6 provides a summary and draws conclusions based on the overall study. Results. The Mt. Ebal site appears to fit the criteria for a cultic site from archaeological remains and also the general picture in terms of the biblical accounts. When the Ebal site is set on the larger stage of the Israelite settlement, its origin seems to be consistent with the dramatic settlement activity in the central hill-country during the transition from the Late Bronze Age to the Iron Age I. Conclusions. The Mt. Ebal site may have served an important role in the early religious life of the central hill-country settlers. Altars played an important role in centralizing peoples in the ancient world. In light of the claim of the biblical tradition that a cultic site located on Mt. Ebal played a centralizing role in the process of the Israelite sedentarization, it does not seem unreasonable to suppose that a single site may have functioned in a central capacity

A Review of Late Twentieth-Century Findings on Adolescent Development in Low-Income Single-Parent Households

It is generally understood that healthy adolescent development is influenced by a variety of factors. Current research on the effects of family structure on adolescent development have largely grown from data collected in the late twentieth century showing that when children grew up in a two-parent household they experienced significant advantages. According to Amato (2005), these advantages included experiencing a higher standard of living, more effective parenting, more cooperative co-parenting, and closer emotional relationships with both parents. Those who grew up in two-parent households demonstrated superior academic performance (Amato et al., 2015; Amato 2005), suggesting that children from single-parent environments may have faced comparative disadvantage. Data show that the number of single-parent households increased from 9% in the 1960s to 28% by 2012 (Amato et al., 2015). This paper discusses findings in the late twentieth century on the effects of growing up in a single-parent household on adolescent development and education and the overall impact of family structure on children’s lives

Preliminary Canopy Removal Experiments in Algal Dominated Communities Low on the Shore and in the Shallow Subtidal on the Isle of Man

The algal dominated communities immediately above and below the low-water spring level on a moderately exposed Manx shore were investigated by canopy removal experiments. Fucus serratus, Laminaria digitata and L. hyperborea were removed. Competition was shown to be important in determining the zonation of L. digitata and the distribution along the wave exposure gradient of other species such as Alaria esculenta, Desmarestia aculeata and D. viridis, and L. saccharina. Many species of algal epiphytes were early colonizers of canopy removal areas suggesting that competition from canopy algae usually restricts them to an epiphytic habit. The results indicate that interactions between macrophytes are much more important than grazing in structuring these communities