The synthesis of high-performance electrochromic polymers remains a key research highlight in the field of electrochromism. Herein, a series of new solution-processable electrochromic polymers are designed and synthesized via direct arylation polymerization (DArP) of 4,9-dihydro-s-indaceno[1,2-b:5,6-b]dithiophene (IDT, M1) or tri(thienothiophene) (TTT, M2) and 3,4-bis(cycloalkoxyl)thiophene. All of these copolymers demonstrate outstanding electrochromic properties, such as high optical contrast, good switching stability, etc. The IDT-based copolymers present a red color in the neutral state and a highly transmissive oxidized state. Due to the stronger electron-rich character of TTT, the TTT-based copolymers can change from purple to highly transmissive. Additionally, due to the existence of methylene or ethylene units between the cycloalkyl and thiophene units, the different cycloalkoxyl side chains exhibit minor effects on the electrochromic properties of the copolymers. Finally, the fascinating properties of the electrochromic devices assembled based on these ECPs confirm their broad application potential in smart windows and as a color palette for color mixing.
During a pitch-over event, the forward momentum of the combined bicycle and rider is suddenly arrested causing the rider and bicycle to rotate about the front wheel and also possibly propelling the rider forward. This paper examines the pitch-over of a bicycle and rider using two methods different from previous approaches. One method uses Newton’s 2nd Law directly and the other method uses the principle of impulse and momentum, the integrated form of Newton’s 2nd Law. The two methods provide useful equations, contributing to current literature on the topic of reconstructing and analyzing bicycle pitch-over incidents. The analysis is supplemented with Madymo simulations to evaluate the kinematics and kinetics of the bicycle and rider interacting with front wheel obstructions of different heights. The effect of variables such as rider weight, rider coupling to the bicycle, bicycle speed, and obstruction height on resulting kinematics were evaluated. The analysis shows that a larger momentum requires a higher obstruction to arrest that momentum and results in a pitch-over event. The Madymo findings are correlated to the predicted kinematics from the two numerical methods. These analytical models provide tools when Madymo software is not available. Validation of these models is explored using Madymo.
This paper is a continuation of a previous effort to evaluate the post-impact motion of vehicles with high rotational velocity within various vehicle dynamic simulation softwares. To complete this goal, this paper utilizes a design of experiments (DOE) method. The previous papers analyzed four vehicle dynamic simulation software programs; HVE (SIMON and EDSMAC4), PC-Crash and VCRware, and applied the DOE to determine the most sensitive factors present in each simulation software. This paper will include Virtual Crash into this methodology to better understand the significant variables present within this simulation model. This paper will follow a similar DOE to that which was conducted in the previous paper. A total of 32 trials were conducted which analyzed ten factors. Aerodynamics, a factor included in the previous DOE, was not included within this DOE because it does not exist within Virtual Crash. The same three response variables from the previous DOE were measured to determine the effect of the various factors. These response variables are the x-coordinate, y-coordinate and total rotational displacement of the vehicle at rest. The results show that, consistent with the previously tested vehicle dynamic simulation software programs, roadway drag was a significant factor in predicting all three response variables. There is also a sensitivity to the longitudinal speed, as well as multiple factor interactions in determining the y-coordinate. Multiple factors – weight, yaw inertia, CG height, roadway drag, longitudinal speed, and angular speed – were important for rotational displacement. Along with the DOE from the previous papers, this paper conducted a separate DOE analysis to evaluate two additional factors; roll inertia and pitch inertia. Five trials were run to evaluate the effect of these factors on the same three response variables from the previous DOE. The results show that the only significant factor was the pitch inertia in determining rotational displacement. It’s noted that pitch inertia was nearly significant in determining the y-coordinate but fell marginally short of the statistical threshold (0.005) used by the authors.
Electromagnetic induction (EMI) technique has been used in the large-scale geological mapping investigation; however, few studies have associated small-scale EMI responses and soil pore characteristics. We developed a simple theoretical framework to interpret EMI responses of geomaterials and used a parametric study to show the dependency of high-frequency electromagnetic induction (HFEMI) signals on the electrical conductivity and the associated soil pore characteristics. A series of EMI tests were performed on geomaterials with varying water contents, void ratios, and porewater salinities. Results showed the salient dependence of HFEMI signals on the frequency, water content, void ratio, and porewater salinity. Additionally, it was found that the low-frequency noise might affect the data interpretation of frequency-dependent EMI signals, and the log-log plotting could identify the actual materials' responses in the high-frequency domain. The association between EMI responses and soil properties was explained by the underlying soil electrical conduction phenomenon. A semiempirical equation was derived to interpret soil electrical conductivity from the EMI spectrum, and a good correlation was found between frequency-dependent EMI quadrature signals and soil properties. This study highlights the considerable potential of adopting the HFEMI technique for nonintrusive geomaterials characterization and proposes a systematic methodology for performing EMI screening to obtain reliable EMI signals for geotechnical evaluation.
