Research on Building Information Model (BIM) Technology

All above this paper is to give the BIM scientific definition, describes the BIM six technical characteristics and points out the essence of BIM Technology, creatively put forward the mature styling BIM seven technical standards, depicting the BIM Technology Development Tools, and other technical fusion development realize the feasibility of the technical route, show the BIM building life cycle management strategies and methods based on, from the two dimensions of qualitative and quantitative, symbiosis is the example of the fused BIM Technology and energy consumption analysis tool. In the realization of green, smart and sustainable design BIM technology advantages to focus attention, the article finally, the BIM technology in China's engineering practice in the application of the prospects for the future

Phonon-limited carrier mobilities and Hall factors in 4H-SiC from first principles

Charge carrier mobility is at the core of semiconductor materials and devices optimization, and Hall measurement is one of the most important techniques for its characterization. The Hall factor, defined as the ratio between Hall and drift mobilities, is of particular importance. Here we study the effect of anisotropy by computing the drift and Hall mobility tensors of a technologically important wide-band-gap semiconductor, 4H-silicon carbide (4H-SiC) from first principles. With $GW$ electronic structure and \textit{ab initio} electron-phonon interactions, we solve the Boltzmann transport equation without fitting parameters. The calculated electron and hole mobilities agree with experimental data. The electron Hall factor strongly depends on the direction of external magnetic field $\mathbf{B}$, and the hole Hall factor exhibits different temperature dependency for $\mathbf{B}\parallel c$ and $\mathbf{B}\perp c$. We explain this by the different equienergy surface shape arising from the anisotropic and non-parabolic band structure, together with the energy-dependent electron-phonon scattering.Comment: 24 pages, 8 figure

Detection of Ship Wakes in SAR Imagery Using Cauchy Regularisation

Ship wake detection is of great importance in the characterisation of synthetic aperture radar (SAR) images of the ocean surface since wakes usually carry essential information about vessels. Most detection methods exploit the linear characteristics of the ship wakes and transform the lines in the spatial domain into bright or dark points in a transform domain, such as the Radon or Hough transforms. This paper proposes an innovative ship wake detection method based on sparse regularisation to obtain the Radon transform of the SAR image, in which the linear features are enhanced. The corresponding cost function utilizes the Cauchy prior, and on this basis, the Cauchy proximal operator is proposed. A Bayesian method, the Moreau-Yoshida unadjusted Langevin algorithm (MYULA), which is computationally efficient and robust is used to estimate the image in the transform domain by minimizing the negative log-posterior distribution. The detection accuracy of the Cauchy prior based approach is 86.7%, which is demonstrated by experiments over six COSMO-SkyMed images.Comment: 9 pages, 2 Figures and 2 Table

Black-Box Constructive Proofs Are Unavoidable

Following Razborov and Rudich, a "natural property" for proving a circuit lower bound satisfies three axioms: constructivity, largeness, and usefulness. In 2013, Williams proved that for any reasonable circuit class C, NEXP ? C is equivalent to the existence of a constructive property useful against C. Here, a property is constructive if it can be decided in poly(N) time, where N = 2? is the length of the truth-table of the given n-input function. Recently, Fan, Li, and Yang initiated the study of black-box natural properties, which require a much stronger notion of constructivity, called black-box constructivity: the property should be decidable in randomized polylog(N) time, given oracle access to the n-input function. They showed that most proofs based on random restrictions yield black-box natural properties, and demonstrated limitations on what black-box natural properties can prove. In this paper, perhaps surprisingly, we prove that the equivalence of Williams holds even with this stronger notion of black-box constructivity: for any reasonable circuit class C, NEXP ? C is equivalent to the existence of a black-box constructive property useful against C. The main technical ingredient in proving this equivalence is a smooth, strong, and locally-decodable probabilistically checkable proof (PCP), which we construct based on a recent work by Paradise. As a by-product, we show that average-case witness lower bounds for PCP verifiers follow from NEXP lower bounds. We also show that randomness is essential in the definition of black-box constructivity: we unconditionally prove that there is no deterministic polylog(N)-time constructive property that is useful against even polynomial-size AC? circuits

Tracking Control of Autonomous Vehicles

This thesis intends to design new tracking schemes to enhance the performance and stability of general autonomous vehicles (AVs). Three main types of controllers used for tracking control are investigated. The geometric controller cannot meet high tracking requirements, and control parameters significantly affect its performance. Therefore, an observer-based nonlinear control combined with a particle swarm optimization (PSO) algorithm is developed for low-speed vehicles to track the pre-determined trajectory accurately. A control law featured with self-tuning gains is designed using the backstepping control technique, for which global asymptotic stability is validated. The PSO evaluates tracking performance through the proposed fitness function and generates optimized tuning parameters with fewer iterations, reducing tuning efforts. Velocity and steering tracking could also be rapidly realized by modifying the error weights of the performance evaluation criterion. Based on the proposed yaw error observer (YEO), the problem of the angle measurements being temporarily inaccurate or unavailable is tackled effectively with the given information. Further, existing methods can suffer from complex control algorithms and a lack of tracking stability at high speed. The vehicle's motion is decoupled by considering the Frenet frame. A lateral control law based on the linear-quadratic-regulator (LQR) imposes the tracking errors to converge to zero stably and quickly, providing the optimal solution in real-time due to adaptive gains. Regarding the steady-state errors, they are eliminated through the correction of the feedforward term. Besides, the designed double proportional-integral-derivative (PID) controller realizes not only the longitudinal control but also the velocity tracking

Thermoelastic properties of bridgmanite using Deep Potential Molecular Dynamics

MgSiO_3-perovskite (MgPv) plays a crucial role in the Earth's lower mantle. This study combines deep-learning potential (DP) with density functional theory (DFT) to investigate the structural and elastic properties of MgPv under lower mantle conditions. To simulate complex systems, we developed a series of potentials capable of faithfully reproducing DFT calculations using different functionals, such as LDA, PBE, PBEsol, and SCAN meta-GGA functionals. The obtained predictions exhibit remarkable reliability and consistency, closely resembling experimental measurements. Our results highlight the superior performance of the DP-SCAN and DP-LDA in accurately predicting high-temperature equations of states and elastic properties. This hybrid computational approach offers a solution to the accuracy-efficiency dilemma in obtaining precise elastic properties at high pressure and temperature conditions for minerals like MgPv, which opens a new way to study the Earth's interior state and related processes