Measurements of the dielectric constants for planetary volatiles

The model of Titan at present has the surface temperature, pressure, and composition such that there is a possibility of a binary ethane-methane ocean. Proposed experiments for future Titan flybys include microwave mappers. Very little has been measured of the dielectric properties of the small hydrocarbons at these radar frequencies. An experiment was conducted utilizing a slotted line to measure the dielectric properties of the hydrocarbons, methane to heptane, from room temperature to -180 C. Measurements of the real part of the dielectric constants are accurate to + or - 0.006 and the imaginary part (the loss tangent) of the liquids studied is less than or equal to 0.001. In order to verify this low loss tangent, the real part of the dielectric constant of hexane at 25 C was studied as a function of the frequency range of the slotted line system used. The dielectric constant of hexane at room temperature, between 500 MHz and 3 MHz, is constant within experimental error

Computer Network Security- The Challenges of Securing a Computer Network

This article is intended to give the reader an overall perspective on what it takes to design, implement, enforce and secure a computer network in the federal and corporate world to insure the confidentiality, integrity and availability of information. While we will be giving you an overview of network design and security, this article will concentrate on the technology and human factors of securing a network and the challenges faced by those doing so. It will cover the large number of policies and the limits of technology and physical efforts to enforce such policies

The Relationship Between Student Engagement And ACT Aspire Reading Scores Among Ninth-Grade Students In One Northwest Arkansas Junior High School

The purpose of this study was to examine the relationship between academic achievement and attendance. Reading proficiency is foundational to overall academic success. In this study, reading proficiency served as the operational definition for the level of student academic success. Out-of-school suspension is a disciplinary consequence as a result of student behavior and correlates to student attendance. This quantitative, correlational study examined the relationship between student engagement, as defined by student attendance and discipline, and reading proficiency, as measured by the 2021-22 ACT Aspire Reading scores for ninth-grade students in one northwest Arkansas junior high school. Descriptive data analysis was conducted to show the demographic makeup of the school and the frequencies and means of attendance and discipline data. Raw scores for the ACT Aspire Reading Assessment were used as a measure of student academic success. Using Spearman Rho and multiple linear regression analysis, the results of this study revealed the effect of chronic absenteeism on the reading proficiency of these ninth-grade students in one Northwest Arkansas junior high school. Three regression models were formulated using student attendance, gender, and ethnicity as predictor variables, with a combined 11.6% explanation for the variance in the reading scores. While the analysis indicated that attendance, gender, and ethnicity predicted reading scores, student discipline was removed from the regression analysis as a predictor variable. Conclusions from the research include that out-of-school suspensions have a negative effect on reading proficiency due to their increasing student attendance. Discipline alone did not appear to affect reading proficiency and academic achievement significantly. The results support previous research in this field, indicating that students with higher attendance tend to have better reading proficiency. This research suggests that school leaders must provide alternatives to out-of-school suspensions and find solutions to negative student behavior to increase instructional time. This research contributes to the ongoing dialogue surrounding the negative academic impact of low attendance, exacerbated by out-of-school suspensions and academic achievement

Direct Simulation of Hypersonic Transitional Flows Over Blunt Slender Bodies

Hypersonic transitional flow has been studied using the Direct Simulation Monte Carlo method. The cylindrically blunted wedge and spherically blunted cone were examined for body half angles of 0°, 5° and 10°, at a flight velocity of 7.5 km/s, zero angle of incidence and altitudes of 70 to 100 km. Those geometries and flow conditions are important considerations for hypersonic vehicles currently under design. Surface chemistry was examined for diffuse, finite-catalytic surfaces. Nonequilibrium chemistry and nonequilibrium thermodynamics were considered for both configurations at all altitudes. Numerical simulations showed that rarefied gas effects, such as surface temperature jump and velocity slip, exist. Slip conditions were more significant for the axisymmetric cases and the onset of chemical dissociation occurred first for the two-dimensional configuration at 96 km. Comparisons between the numerical simulation and viscous shock-layer calculations at the higher altitudes show significant differences in the calculated heat-transfer rate, body drag and flowfield structure. A comparison with hypersonic wind tunnel heat-transfer rate data showed good agreement

Multiple IMU system test plan, volume 4

Operating procedures for this redundant system are described. A test plan is developed with two objectives. First, performance of the hardware and software delivered is demonstrated. Second, applicability of multiple IMU systems to the space shuttle mission is shown through detailed experiments with FDI algorithms and other multiple IMU software: gyrocompassing, calibration, and navigation. Gimbal flip is examined in light of its possible detrimental effects on FDI and navigation. For Vol. 3, see N74-10296