7 research outputs found
Technology Enabling Near-Term Nationwide Implementation of Distance Based Road User Fees
No full textThis report describes a system meant for near-term deployment that directly determines the distance traveled by a vehicle and uses this as a basis for charging a fee that reflects road use. An in-vehicle device with access to the vehicle data bus and power through a single standard connector available on all passenger vehicles since 1996, electronically calculates the distance and then securely communicates relevant information to a “back office” for processing and transferring accumulated fees from the user to the appropriate government jurisdiction. Also described are means for providing payment (and receiving credit for motor fuel use taxes paid at the pump) while also ensuring compliance, enforcement, transparency and privacy. Communication is via text messaging, available wherever cellular service is accessible. No new wireless infrastructure is needed. The in-vehicle device distinguishes distance traveled by state or by other regions of interest e.g., rural vs. urban areas, using the same cellular technology that is used for communications. Aggregating distance based on rural vs. urban travel can facilitate different pricing policies for these different road users. Neither a GPS receiver nor longitude/latitude position data is necessary. However, higher resolution position sensing can be added to the core platform as needed based on policy objectives, e.g., to consider alternate pricing for specific road facilities.Donath, Max; Gorjestani, Alec; Shankwitz, Craig; Hoglund, Richard; Arpin, Eddie; Cheng, PiMing; Menon, Arvind; Newstrom, Bryan. (2009). Technology Enabling Near-Term Nationwide Implementation of Distance Based Road User Fees. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/97660
Fair energy-efficient resource allocation for spectrum leasing in cognitive radio networks
No full textJoint resource allocation with statistical delay QoS guarantees for spectrum leasing CR networks
No full textRobust MISO Beamforming With Cooperative Jamming for Secure Transmission From Perspectives of QoS and Secrecy Rate
No full textAbove-Curie-temperature ultrafast terahertz emission and spin current generation in a 2D superlattice (Fe3GeTe2/CrSb)3
No full textThe increasing demand for denser information storage and faster data processing has fueled a keen interest in exploring spin currents up to terahertz (THz) frequencies. Emergent 2D intrinsic magnetic materials constitute a novel and highly controllable platform to access such femtosecond spin dynamics at atomic layer thickness. However, the function of 2D van der Waals magnets are limited by their Curie temperatures, which are usually low. Here, in a 2D superlattice (Fe3GeTe2/CrSb)3, we demonstrate ultrafast laser-induced spin current generation and THz radiation at room temperature, overcoming the challenge of the Curie temperature of Fe3GeTe2 being only 206 K. In tandem with time-resolved magneto-optical Kerr effect measurements and first-principles calculations, we further elucidate the origin of the spin currents—a laser-enhanced proximity effect manifested as a laser-induced reduction of interlayer distance and enhanced electron exchange interactions, which causes transient spin polarization in the heterostructure. Our findings present an innovative, magnetic-element-free route for generating ultrafast spin currents within the 2D limit, underscoring the significant potential of laser THz emission spectroscopy in investigating laser-induced extraordinary spin dynamics
Antiferromagnet-topological insulator heterostructure for polarization-controllable terahertz generation
No full textAntiferromagnets (AFMs) are more advantageous in realizing ultrafast spin-based processes, but remain challenging to manipulate. The lack of proper knobs in AFM-based ultrafast devices greatly hampers their applications. Here, we innovate an antiferromagnet/topological insulator (AFM/TI) heterostructure MnSe/(Bi,Sb)2Te3 to realize laser-induced transient magnetic moment, and further demonstrate optically controllable circularly polarized ultrafast terahertz (THz) pulse generation, under zero external magnetic field. Intriguingly, we find two mechanisms underlying the ultrafast THz pulse generation: direct magnetic dipole radiation and spin-charge conversion resulted electric dipole radiation. Our findings provide a suitable platform for efficient and polarization-controllable ultrafast THz devices via optical means
Trifluoromethyl-Functionalized 2D Covalent Organic Framework for High-Resolution Separation of Isomers
No full textDevelopment of novel functional materials for effective
isomer
separation is of great significance in environmental science, chemical
industry, and life science due to the different functions of isomers.
However, the similar physicochemical properties of isomers make their
separation greatly challenging. Here, we report the fabrication of
trifluoromethyl-functionalized 2D covalent organic framework (COF)
TpTFMB with 2,2′-bis(trifluoromethyl)benzidine (TFMB) and 1,3,5-triformylphloroglucinol
(Tp) for the separation of isomers. TpTFMB was in situ-grown on the
inner surface of a capillary for the high-resolution separation of
isomers. The introduction of hydroxyl and trifluoromethyl functional
groups with uniform distribution in 2D COFs is a powerful tactic to
endow TpTFMB with various functions such as hydrogen bonding, dipole
interaction, and steric effect. The prepared TpTFMB capillary column
enabled the baseline separation of positional isomers such as ethylbenzene
and xylene, chlorotoluene, carbon chain isomers such as butylbenzene
and ethyl butanoate, and cis–trans isomers 1,3-dichloropropene.
The hydrogen-bonding, dipole, and π–π interactions
as well as the structure of COF significantly contribute to the isomer
separation. This work provides a new strategy for designing functional
2D COFs for the efficient separation of isomers
