Pricing strategies for a taxi-hailing platform Wang, Xiaolei; He, Fang; Yang, Hai ...
Transportation research. Part E, Logistics and transportation review,
09/2016, Letnik:
93
Journal Article
Recenzirano
•Aggregate taxi market equilibrium under hybrid modes is modeled.•Existence and stability of taxi market equilibrium are examined.•Impacts of platform’s pricing strategies on taxi market performance ...are revealed.•Properties of desirable price perturbations are characterized.
Taxi hailing apps that facilitate taxi-customer matching quickly become popular in recent years. By combining the theories of two-sided market and taxi market, this paper models the taxi market in the presence of a single taxi hailing app through an aggregate and static approach. Based on the equilibrium model, the existence and stability of equilibria are examined, and a partial-derivative-based sensitivity analysis is conducted to quantitatively evaluate the impacts of the platform’s pricing strategies to the taxi market performance. The features of desirable price perturbations that improve social welfare and/or the platform’s profitability are also characterized.
Two-dimensional (2D) materials have been studied extensively as monolayers, vertical or lateral heterostructures. To achieve functionalization, monolayers are often patterned using soft lithography ...and selectively decorated with molecules. Here we demonstrate the growth of a family of 2D materials that are intrinsically patterned. We demonstrate that a monolayer of PtSe
can be grown on a Pt substrate in the form of a triangular pattern of alternating 1T and 1H phases. Moreover, we show that, in a monolayer of CuSe grown on a Cu substrate, strain relaxation leads to periodic patterns of triangular nanopores with uniform size. Adsorption of different species at preferred pattern sites is also achieved, demonstrating that these materials can serve as templates for selective self-assembly of molecules or nanoclusters, as well as for the functionalization of the same substrate with two different species.
The proton charge radius Gao, H.; Vanderhaeghen, M.
Reviews of modern physics,
01/2022, Letnik:
94, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Nucleons (protons and neutrons) are the building blocks of atomic nuclei and are responsible for more than 99% of the visible matter in the Universe. Despite decades of efforts in studying its ...internal structure, there are still a number of puzzles surrounding the proton such as its spin and charge radius. Accurate knowledge about the proton charge radius is not only essential for understanding how QCD works in the nonperturbative region but also important for bound state QED calculations of atomic energy levels. It also has an impact on the Rydberg constant, one of the most precisely measured fundamental constants in nature. This review examines the latest situation concerning the proton charge radius in light of the new experimental results from both atomic hydrogen spectroscopy and electron-scattering measurements, with particular focus on the latter. Theoretical backgrounds and recent developments concerning the determination of the proton charge radius using different experimental techniques are also presented. Upcoming experiments are discussed, and the deuteron charge radius puzzle is mentioned at the end.
We predict theoretical existence of intrinsic two-dimensional organic topological insulator (OTI) states in Cu–dicyanoanthracene (DCA) lattice, a system that has also been grown experimentally on Cu ...substrate, based on first-principle density functional theory calculations. The p z -orbital Kagome bands having a Dirac point lying exactly at the Fermi level are found in the freestanding Cu–DCA lattice. The tight-binding model analysis, the calculated Chern numbers, and the semi-infinite Dirac edge states within the spin–orbit coupling gaps all confirm its intrinsic topological properties. The intrinsic TI states are found to originate from a proper number of electrons filling of the hybridized bands from Cu atomic and DCA molecular orbitals based on which similar lattices containing noble metal atoms (Au and Cu) and those molecules with two CN groups (DCA and cyanogens) are all predicted to be intrinsic OTIs.
Self-assembly of various phthalocyanine (Pc) molecules and a derivative on an epitaxial graphene monolayer (MG) has been investigated by means of in situ ultrahigh vacuum scanning tunneling ...microscopy. The formation of regular Kagome lattices that duplicate the lattice of the moiré pattern of MG was observed, demonstrating that MG can act as a wonderful template for the fabrication of unique nanoarchitectures with remarkable properties. Varying the central metal ion of the Pc molecule affords Kagome lattices with tunable molecular spins, providing ideal two-dimensional model systems for studying frustration physics.
We predict a family of 2D carbon (C) allotropes, square graphynes (S-graphynes) that exhibit highly anisotropic Dirac fermions, using first-principle calculations within density functional theory. ...They have a square unit-cell containing two sizes of square C rings. The equal-energy contour of their 3D band structure shows a crescent shape, and the Dirac crescent has varying Fermi velocities from 0.6 × 105 to 7.2 × 105 m/s along different k directions. Near the Fermi level, the Dirac crescent can be nicely expressed by an extended 2D Dirac model Hamiltonian. Furthermore, tight-binding band fitting reveals that the Dirac crescent originates from the next-nearest-neighbor interactions between C atoms. S-graphynes may be used to build new 2D electronic devices taking advantages of their highly directional charge transport.
•We design an optimal lane management strategy for a heterogeneous traffic condition.•We dynamically control the network inflow by optimizing the size of the CAV platoons.•The multiple lane type ...corridors are modeled as sets of parallel bottlenecks.•The dynamics of the congestion in the network is modeled using the MNFD.•We solve the optimization problem for the city of San Francisco, CA.
The advent of autonomous driving technologies has created a crucial need for upgrading conventional traffic control and lane management strategies in large cities. In this research, we design an optimal lane management strategy for corridors with a heterogeneous demand of human-driven, autonomous, and communicant autonomous vehicles (HVs, AVs, and CAVs). In a monocentric city setting, we dynamically control the inflow of the network by optimizing the size of CAV platoons in the corridors based on the instantaneous condition of the integrated system. These corridors can potentially have three types of lanes for vehicles with different levels of automation technology. We model the multiple lane type corridors as sets of parallel bottlenecks with general distributions of multiclass demand. The dynamics of the congestion in the network is also modeled using the macroscopic network fundamental diagram (MNFD). To study the impacts of the rise in the penetration rate of AVs and CAVs on the performance of the system, we derive a closed-form representation of the model. We show that the increase of the delay in the network with the rise in the penetration rate of AVs and CAVs can have a stable, an unstable, or a hybrid pattern. To optimize the system, we minimize a weighted summation of the experienced delay in the corridors and the total travel time in the urban network by optimizing the number of lanes of each type and the dynamic size of the CAV platoons. The results of the San Francisco case study show that implementing an optimal lane management strategy can reduce the experienced delay in the corridors up to 78% with a rise in the AV/CAV penetration rate. By dynamically controlling the size of the CAV platoons in the automated highway of the Bay Bridge, we limit the increase of the travel time in the downtown network as low as 5%.
Topological Dirac and Weyl semimetals not only host quasiparticles analogous to the elementary fermionic particles in high-energy physics, but also have a non-trivial band topology manifested by ...gapless surface states, which induce exotic surface Fermi arcs1,2. Recent advances suggest new types of topological semimetal, in which spatial symmetries protect gapless electronic excitations without high-energy analogues3–11. Here, using angle-resolved photoemission spectroscopy, we observe triply degenerate nodal points near the Fermi level of tungsten carbide with space group \P\bar{6}m2\ (no. 187), in which the low-energy quasiparticles are described as three-component fermions distinct from Dirac and Weyl fermions. We further observe topological surface states, whose constant-energy contours constitute pairs of ‘Fermi arcs’ connecting to the surface projections of the triply degenerate nodal points, proving the non-trivial topology of the newly identified semimetal state.
•China’s logistics industry enjoyed fast growth at an annual growth rate of 9.65% from 1980 to 2010.•Logistics energy consumption increased by 22.91 times, averaging at 11.9% growth per year, driven ...mainly by highway transportation.•Energy efficiency gains showed slight but promising effect of curbing the energy rise in China’s logistics industry.
The logistics industry plays a critical role in boosting China’s economic development, although at significant externality costs. Using the 1980–2010 data, we examine the historical evolution of energy consumption in China’s logistics industry. The logarithmic mean Divisia index (LMDI) method was used to analyze the key factors that drove the chronicle changes in logistics energy consumption in China. Changes in energy consumption of China’s logistics industry are attributed to growth in logistics activity, modal shift in freight transportation, increases in transport intensity, and overall improvements in energy intensity: (1) China’s logistics industry enjoyed fast growth with an average annual growth rate of 9.65% from 1980 to 2010. Increase in logistics activity has been the major force driving up logistics energy consumption (accounting for 48.8% of logistics energy increase); (2) Logistics energy consumption increased by 22.91 times, averaging at 11.9% growth per year. Fuel consumption in highway transportation has become more dominant in logistics energy consumption; (3) While changes in logistics activities, transportation modes and transport intensity pushed up logistics energy consumptions, improvements in energy intensity helped significantly to curb the energy rise in China’s logistics industry.
•An MPC framework for space heating system with PCM-based active latent heat storage.•A linear, high-fidelity active latent heat storage model for fast building control.•Highly dynamic electricity ...prices considered for demand-responsive building control.•The MPC approach reduces electricity costs for space heating by 53.2% to 122.7%•A good synergy between the MPC approach and active latent heat storage is observed.
Active latent heat storage (ALHS) involving phase-change materials constitutes a promising energy-efficient solution for building energy management (BEM) by reshaping building energy demands without occupant comfort degradation. Current BEM systems based on conventional reactive control lack the level of control delicacy required to exploit the full potential of ALHS for BEM under certain conditions, such as highly dynamic electricity prices. This study proposes a smart model predictive control (MPC) approach for BEM to minimize the energy cost while maintaining the indoor climate by fully applying ALHS. More specifically, a reduced-order, high-fidelity state-space model (SSM) of ALHS is proposed for fast building control. An MPC framework considering highly dynamic electricity prices and ALHS dynamics is developed based on the proposed ALHS SSM integrated with a building SSM. A case study entailing a set of simulations is designed based on a single-family house with a space heating system, including an ALHS, ground source heat pump, and radiator. The proposed MPC approach, compared to conventional reactive control, enables substantial reductions in the electricity cost (ranging from 53.2% to 122.7% depending on the MPC settings and ALHS capacity), even financial gains under certain scenarios. Further analysis reveals that coupling ALHS with MPC is critical to ensure that ALHS adoption is economically convincing: while conventional reactive control of an ALHS-equipped building increases the electricity cost, an MPC-enabled building could reduce the electricity cost by 45.1% due to ALHS adoption. The proposed MPC approach also exhibits promising feasibility for real-world BEM applications.
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