579 research outputs found

    FrameNet: Learning Local Canonical Frames of 3D Surfaces from a Single RGB Image

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    In this work, we introduce the novel problem of identifying dense canonical 3D coordinate frames from a single RGB image. We observe that each pixel in an image corresponds to a surface in the underlying 3D geometry, where a canonical frame can be identified as represented by three orthogonal axes, one along its normal direction and two in its tangent plane. We propose an algorithm to predict these axes from RGB. Our first insight is that canonical frames computed automatically with recently introduced direction field synthesis methods can provide training data for the task. Our second insight is that networks designed for surface normal prediction provide better results when trained jointly to predict canonical frames, and even better when trained to also predict 2D projections of canonical frames. We conjecture this is because projections of canonical tangent directions often align with local gradients in images, and because those directions are tightly linked to 3D canonical frames through projective geometry and orthogonality constraints. In our experiments, we find that our method predicts 3D canonical frames that can be used in applications ranging from surface normal estimation, feature matching, and augmented reality

    Paths for New Urbanization in Chongqing, China: Study on Overall Design and Strategic Framework

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    Based on introspection about disadvantages of the traditional urbanization, the new urbanization is on the transformation and innovation of strategies with reference to the relevant successful experience all over the world. Through analyses on the consequent strategic opportunity of Chongqing pilot zone for overall reform to balance the urban and rural development, the paper expounds an overall idea on paths for new urbanization in Chongqing. And then the paper constructs a strategic framework of the paths aiming to provide a scientific and clear direction to the choice of paths for new urbanization in Chongqing.

    RF system for mmWave massive MIMO

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    Due to rapid developments in communication technology, it is likely that 5G networks will be rolled out in 2019. To adapt to 5G, hardware will have to develop to meet the requirements of this new technology. The mmWave communication is one of the main elements of 5G technology. The mmWave frequency bandwidth is used to carry the data links and can achieve a higher transmission data rate than the current LTE system. There are few continuous frequency resources under 3GHz that can be allocated. As such, the International Telecommunication Union (ITU) and the 3GPP organization mutually agree that the mmWave is the most suitable option for exploring new frequency resources. However, the mmWave has the one key weakness: high path loss for short transmission range. To compensate for this negative effect, a massive MIMO system can be used to have spatial multiplexing gains and array an-tenna gains. This article seeks a method that can acknowledge the funda-mental concepts and requirements of the mmWave massive MIMO system, from both theoretical and practical perspectives. In order to find proof of the concepts, the practical limitations, and the guild of the real design, a prototype of the system has been built. The current industry standard when creating a prototype is to use PCB. We will develop our system proposals from the prototype. To do so we use the evaluation boards to test system level performances such as link budget and identifying the most suitable components etc. Then in the PCB design, we integrate the radio frequency of the mmWave system. This has the scalability to collaborate with massive MIMO system test-bed to observe the system level performance. Finally, to verify our methods, we carry out experiments on both component level and system level in order to identify the feasibility of the prototype system. The performance of each individual component is tested using an evaluation board. Separate tests are performed for both transmitting (Tx) and receiving (Rx) chains. Finally, over-air-tests are conducted at the sys-tem level to evaluate the performance of our design5G communication system is the next milestone that will soon approach our lives. The first specification of 5G is called Release 15 and the system struc-tures and requirements of it have been identified. Compared to the LTE system, it can deliver an even higher data rate and adapt more transmission situations in the future. 5G consists of five essential technologies, mmWave, massive MIMO, the advanced channel coding, scalable OFDM and self-contained slot structure. The first two technologies, the mmWave and massive MIMO, are indispensable in this thesis. As the fre-quency resources scarcely go below 3GHz, they are retrieving the mmWave spectrum to allocate more accessible bandwidth. Nevertheless, the mmWave has high free space path loss, and the signal will be harshly weakened before it reaches the receiver. The massive MIMO is an extension of the MIMO system with massive antenna elements in the antenna array This sound solution can contradict the high free space path loss, achieve high throughput and serve tens of users simultaneously. This thesis concentrates on building a radio frequency system PCB prototype based on mmWave and massive MIMO. Now, the existing hardware devices will not placate the 5G system necessi-ties. The new system structure must be developed, and the performance will be evaluated. Prototype is a realization method to transition from theory to practice which can help the engineers comprehend the theoretical and prac-tical perspectives. In electronic industry, PCB is the correct way of building the radio frequency prototype, in which the system schematic is construct-ed in a dense area with mass circuit distribution. All electronic components are surfaced and then mounted on it and connected by conductive wires through the various layers. A flawless PCB needs to be shaped with full operational functions before the final products. To do this, the perfor-mance will be evaluated when we are building the PCB prototype and im-provements will be analysed, and additional developments will be encom-passed in the future version of PCB. In this thesis, the PCB performance is evaluated individually for different transmission chains, and then the over air test is assessed

    Singlino-dominated dark matter in general NMSSM

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    The general Next-to-Minimal Supersymmetric Standard Model (NMSSM) describes the singlino-dominated dark-matter (DM) property by four independent parameters: singlet-doublet Higgs coupling coefficient λ\lambda, Higgsino mass μtot\mu_{tot}, DM mass mχ~10m_{\tilde{\chi}_1^0}, and singlet Higgs self-coupling coefficient κ\kappa. The first three parameters strongly influence the DM-nucleon scattering rate, while κ\kappa usually affects the scattering only slightly. This characteristic implies that singlet-dominated particles may form a secluded DM sector. Under such a theoretical structure, the DM achieves the correct abundance by annihilating into a pair of singlet-dominated Higgs bosons by adjusting κ\kappa's value. Its scattering with nucleons is suppressed when λv/μtot\lambda v/\mu_{tot} is small. This speculation is verified by sophisticated scanning of the theory's parameter space with various experiment constraints considered. In addition, the Bayesian evidence of the general NMSSM and that of Z3Z_3-NMSSM is computed. It is found that, at the cost of introducing one additional parameter, the former is approximately 3.3×1033.3 \times 10^3 times the latter. This result corresponds to Jeffrey's scale of 8.05 and implies that the considered experiments strongly prefer the general NMSSM to the Z3Z_3-NMSSM.Comment: 29 pages, 9 figure

    A High-Efficiency Broadband Rectenna for Ambient Wireless Energy Harvesting

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    This paper presents a novel broadband rectenna for ambient wireless energy harvesting over the frequency band from 1.8 to 2.5 GHz. First of all, the characteristics of the ambient radio-frequency energy are studied. The results are then used to aid the design of a new rectenna. A novel two-branch impedance matching circuit is introduced to enhance the performance and efficiency of the rectenna at a relatively low ambient input power level. A novel broadband dual-polarized cross-dipole antenna is proposed which has embedded harmonic rejection property and can reject the second and third harmonics to further improve the rectenna efficiency. The measured power sensitivity of this design is down to -35 dBm and the conversion efficiency reaches 55% when the input power to the rectifier is -10 dBm. It is demonstrated that the output power from the proposed rectenna is higher than the other published designs with a similar antenna size under the same ambient condition. The proposed broadband rectenna could be used to power many low-power electronic devices and sensors and found a range of potential applications
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