The Dependency of Penetration on the Momentum Per Unit Area of the Impacting Projectile and the Resistance of Materials to Penetration

The results of this investigation indicate that the penetration of projectiles into quasi-infinite targets can be correlated as a function of the maximum momentum per unit area possessed by the projectiles. The penetration of projectiles into aluminum, copper, and steel targets was found to be a linear function while the penetration into lead targets was a nonlinear function of the momentum per unit area of the impacting projectiles. Penetration varied inversely as the projectile density and the elastic modulus of the target material for a given projectile momentum per unit area. Crater volumes were found to be a linear function of the kinetic energy of the projectile, the greater volumes being obtained in the target materials which had the lowest yield strength and the lowest speed of sound

Synthesis of Rating Methodologies for Concrete Bridges without Plans

In response to Federal Highway Administration requirements, many states are confronted with assigning load ratings to large numbers of concrete bridges that do not have plans. The AASHTO Manual for Bridge Evaluation does not specify which methodologies should be used to establish load ratings for concrete bridges without plans, nor does it clearly state how extensive the evaluation of such structures should be. To inform engineers responsible for load rating structures without plans, this report highlights available non-destructive evaluation methods that are able, to varying extents, to locate and determine the size of concrete reinforcing bars. It also provides a survey of current and emergent methodologies for establishing load ratings for concrete bridges without plans. Finally, to characterize the state-of-the-practice, results are reported from a survey distributed to state bridge engineers. There are large differences among states in terms of the specificity of established procedures and overall methodologies employed to assign load ratings to the more than 25,000 bridges without plans located in the 24 states that responded to the survey. Recommendations for approaching this problem in a rational and cost-effective manner are made after considering both published evidence and ease of implementation across large inventories of structures

Load Rating Reinforced Concrete Bridges without Plans: State-of-the-Practice

In response to Federal Highway Administration requirements, several states are in the process of ensuring all bridges within their inventories are load rated. A challenging aspect of this effort is load rating reinforced concrete bridges that have no structural plans when there are thousands of such structures within a state inventory. To inform these efforts, the literature was reviewed to identify existing methodologies and a survey was distributed to engineers at state departments of transportation throughout the United States to understand how practicing engineers approach this problem. The survey responses show there are numerous bridges in the U.S. without plans; over 25000 bridges without plans are located in the 18 states that provided responses. Concrete structures comprise 70% of such bridges. To load rate concrete bridges without plans, most responding states report primarily using engineering judgement, which may include reference to performance under existing traffic, era-specific design traffic loads, assumed material properties and reinforcement quantities, or data collected using load tests or non-destructive evaluation. Several methodologies are described and advantages/limitations of each are discussed

Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures

Family Business CEO Succession: Examining Personal Retirement Expectations

Retirement well-being expectations of incumbent family owned business CEOs is a critical precursor to successful succession events. The significant antecedents to retirement well-being expectation are family relationships, wealth management and transfer, leadership succession and development, and continuity and viability of the firm. Using data from a survey of 256 family firm CEOs we demonstrate those relationships and show a very strong connection between retirement well-being expectation and firm performance. Study results further our premise that antecedents to retirement well-being expectation are indirectly tied to the overall health and performance of the family firm

Robotic-Movement Payload Lifter and Manipulator

A payload lifter/manipulator module includes a rotatable joint supporting spreader arms angularly spaced with respect to one another. A rigid arm is fixedly coupled to the joint and extends out therefrom to a tip. A tension arm has a first end and a second end with the first end being fixedly coupled to the tip of the rigid arm. The tension arm incorporates pivots along the length thereof. Each pivot can be engaged by or disengaged from the outboard end of a spreader arm based on a position of the spreader arm. A hoist, positioned remotely with respect to the module and coupled to the second end of the tension arm, controls the position of the spreader arms to thereby control the position of the rigid arm's tip. Payload lifter/manipulator assemblies can be constructed with one or more of the modules

Deletion of the trpc4 gene and its role in simple and complex strategic learning

The TRPC4 ion channel is expressed extensively in corticolimbic and a subpopulation of midbrain dopamine neurons. While TRPC4 knockout (KO) rats exhibit reduced sociability and social exploration, little is known about the role of TRPC4 in motivation and learning. To identify a function for TRPC4 channels in learning processes  we tested TRPC4 KO and normal wild type (WT) rats. TRPC4 KO and WT rats exhibited no differences in Y-­maze learning or simple discrimination learning. Furthermore, on a more complex serial reversal shift task designed  to assess strategic learning where the reward and non-­reward cues were repeatedly reversed between training sessions both TRPC4 KO and WT rats   performed equally well. Finally, we found no   performance differences when using a conditional reversal shift task where a tone signals the reversal of reward and non-reward cues within sessions. These data suggest that although TRPC4 channels may play a role in social interaction/anxiety  they exert a minimal role in simple and complex strategic learning

Detected changes in precipitation extremes at their native scales derived from in situ measurements

The gridding of daily accumulated precipitation -- especially extremes -- from ground-based station observations is problematic due to the fractal nature of precipitation, and therefore estimates of long period return values and their changes based on such gridded daily data sets are generally underestimated. In this paper, we characterize high-resolution changes in observed extreme precipitation from 1950 to 2017 for the contiguous United States (CONUS) based on in situ measurements only. Our analysis utilizes spatial statistical methods that allow us to derive gridded estimates that do not smooth extreme daily measurements and are consistent with statistics from the original station data while increasing the resulting signal to noise ratio. Furthermore, we use a robust statistical technique to identify significant pointwise changes in the climatology of extreme precipitation while carefully controlling the rate of false positives. We present and discuss seasonal changes in the statistics of extreme precipitation: the largest and most spatially-coherent pointwise changes are in fall (SON), with approximately 33% of CONUS exhibiting significant changes (in an absolute sense). Other seasons display very few meaningful pointwise changes (in either a relative or absolute sense), illustrating the difficulty in detecting pointwise changes in extreme precipitation based on in situ measurements. While our main result involves seasonal changes, we also present and discuss annual changes in the statistics of extreme precipitation. In this paper we only seek to detect changes over time and leave attribution of the underlying causes of these changes for future work

Interlaboratory study of standard methods for testing multiwire steel prestressing strand

An interlaboratory study involving 19 laboratories was conducted to quantify the precision of ASTM A1061-16, Standard Test Methods for Testing Multi-Wire Steel Prestressing Strand, which describes methods for measuring yield strength, elastic modulus, elongation, breaking strength, and relaxation. Relaxation measurements were outside the project scope. Yield strength, elastic modulus, and breaking strength results showed low variability, with reproducibility limits less than 4%, 10%, and 3% of the mean reported values, respectively. Elongation results exhibited high variability, resulting in a reproducibility limit close to 50% of the mean reported value. Compliance with the requirements of the standard was an issue, with 74%, 82%, 32%, and 100% of laboratories submitting valid results for yield strength, elastic modulus, elongation, and breaking strength, respectively. Strand fracture location was sensitive to the type of grips used for testing. Several changes to ASTM A1061 are proposed to improve clarity and precision