22,767 research outputs found

    Stability of the holographic description of the Universe

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    We investigate the stability of the holographic description of the universe. By treating the perturbation globally, we discover that this description is stable, which is support for the holographic description of the universe.Comment: 11 page

    Exact eigenvalue assignment of linear scalar systems with single delay using Lambert W function

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    Eigenvalue assignment problem of a linear scalar system with a single discrete delay is analytically and exactly solved. The existence condition of the desired eigenvalue is established when the current and delay states are present in the feedback loop. Design of the feedback controller is then followed. Furthermore, eigenvalue assignment for the input-delay system is also obtained as well. Numerical examples illustrate the procedure of assigning the desired eigenvalue

    Driver Responses to Graphic-Aided Portable Changeable Message Signs in Highway Work Zones

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    Portable changeable message signs (PCMSs) have been employed in highway work zones as temporary traffic control devices. Various studies showed that adding graphics to PCMS messages can provide advantages to traditional text messages, such as increasing legibility and improving the understanding of elderly drivers. This article synthesizes the findings of a two-phase research project aimed to investigate driver responses to graphic-aided PCMSs. Different text and graphic-aided PCMSs representing roadwork and flagger were set up in the upstream of highway work zones, and speed data of more than 2,700 vehicles were collected with a series of five speed sensors to determine vehicle speed reduction. Nearly 1,000 onsite driver surveys were performed to identify driver preference on the added graphics. The results discovered that graphic-aided PCMSs reduced mean vehicle speed between 13% and 17% and reduced the speed of passenger cars and trucks significantly differently depending on their locations in work zone. The results indicated that all drivers correctly interpreted the flagger graphic and two work-zone graphics, and suggested that 52% to 71% of drivers preferred to see graphics in PCMS messages. The findings also revealed that driver age did not have a significant impact on driver preference on PCMS message format
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