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Scannerless time-of-flight three-dimensional imaging, the successor to raster scanning three-dimensional imaging, relies on large-scale detector arrays to obtain high pixel resolution; however, manufacturing limitations lead to a bottleneck in imaging resolution. Here, we report a methodology for laser imaging using code division multiple access, which involves three key steps. Optical encoding is carried out for a pulsed laser to generate space-time encoded beams for projection. Optical multiplexing subdivides the backscattered light signals and multiplexes them to a downscaled avalanche-photodiode array. Subpixel decoding decodes the digitized encoded full waveforms and decomposes the features of all subpixels. Accordingly, we design a prototype based on a 64-order encoder and a 4-element avalanche-photodiode array and conduct an outdoor experiment. We demonstrate that the system is capable of obtaining 256 pixels per frame in push-broom mode and reconstruct a three-dimensional image with centimetre-level lateral resolution and range precision at a distance of ∼112 m. Scannerless time of flight three-dimensional devices can produce high-quality images from the ground or in space and provide information on light detection and ranging. The authors design and demonstrate a downscaled subpixel 3D laser imaging device which uses pulse-encoded illumination to encode the pixels.

In this paper, the influence by the pixel shape to crosstalk in autostereoscopic display is analyzed. The diffraction is greatly influenced by the shape of pixels and structure of multi-view autostereoscopic display. It diffracts at sides of sub-pixels, which is more serious at the shorter side. By simulating the light intensity distribution of viewing zones at best viewing distance, we calculate the crosstalk caused by diffraction. The simulation results show that the ratio of the horizontal and vertical spacing of the pixel which is equal to the ratio of the vertical and horizontal spacing of the central bright fringe, which means that the shorter sides are, the worse influence it has on quality of exit pupils. The influence makes exit pupils wider than it should be, and increases crosstalk, leading to viewing discomfort. We propose a solution by horizontal sub-pixels. It indicates that crosstalk by diffraction can reduce to 3.13% in simulation.

A Correction to this paper has been published: https://doi.org/10.1038/s42005-021-00520-8.

Wartsila RT-flex 60C diesel engine is selected as the object to research pressure control of fuel common rail system, building the system simulation model, and analyzing main factors influencing rail pressure in the system. it was concluded that they were diesel engine speed, load. In the process of MATLAB/Simulink simulation, the rail pressure control logic was designed by adopting maps with the two factors as independent variables to get theory feedforward quantity of fuel rack, feedback quantity of fuel rack is obtained by fuzzy PID control. The simulation experiments show that the improved control method reduces the rail pressure fluctuation, at the same time the overshoot volume of dynamic rail pressure control is greatly reduced, response velocity quickened. The control method has been used in a Marine simulator.

A switchable autostereoscopic 3-dimensional (3D) display device with wide color gamut is introduced in this paper. In conjunction with a novel directional quantum-dot (QD) backlight, the precise scanning control strategy, and the eye-tracking system, this spatial-sequential solution enables our autostereoscopic display to combine all the advantages of full resolution, wide color gamut, low crosstalk, and switchable 2D/3D. And also, we fabricated an autostereoscopic display prototype and demonstrated its performances effectively. The results indicate that our system can both break the limitation of viewing position and provide high-quality 3D images. We present two working modes in this system. In the spatial-sequential mode, the crosstalk is about 6%. In the time-multiplexed mode, the viewer should wear auxiliary and the crosstalk is about 1%, just next to that of a commercial 3D display (BENQ XL2707-B and View Sonic VX2268WM). Additionally, our system is also completely compatible with active shutter glasses and its 3D resolution is same as its 2D resolution. Because of the excellent properties of the QD material, the color gamut can be widely extended to 77.98% according to the ITU-R recommendation BT.2020 (Rec.2020).

Facing to the problem of hierarchical structure decision analysis which is made of scheme level + factor level + target level, the analytic hierarchy process gives a whole set of solution and process. This method is used to evaluate diesel engine simulation model. Evaluate original mean value model of large-scale low-speed marine diesel engine and the new one by this method. Calculated results prove this method is applicable.

The combined connection with welds and bolds can be widely used in reinforcing the joint in steel structure. In this paper, proposed design method of combined connection with bolts and longitudinal welds was given based on the tests and finite element analysis (FEA). The method considers the effect of the strength ratio between bolts and welds. The safety and reliability of the method were verified by FEA and comparison with other design method. The design method can contribute to the promotion of the application of the combined connections.

The combined connection with welds and bolds has advantages of both welds and bolts connections, and can be widely used in reinforcing the joint in steel structure. In this paper, the Finite Element Method (FEM) was taken to analyze the carrying capacity of the combined connection with bolts and welds, and the results ware compared with those come from experimental investigation. Further analysis based on FEM ware performed to research the failure mode and bearing performance of the combined connection and the contribution of bolts and welds .Advice was provided for related design.

Highway bridges played an important role in lifeline systems. Their seismic damage status made a direct influence on the implement plan of the earthquake relief work and the life and property security of the people. Therefore, accurate assessment and prediction for the seismic damage of highway bridges were of vital significance, based on which reasonable earthquake fortification could be implemented. This paper summarized and classified the existing seismic damage assessment methods for highway bridges, including certain index evaluation methods based on statistical results, vulnerability index evaluation methods based on probability theory and vulnerability index evaluation methods based on aggregation model. Then the capacity-spectrum method which could be used for calculating the fragility curve and the seismic assessment model of highway bridges used in HAZUS were specially explained. At last, the proposal for the development of seismic assessment systems related with highway bridges in China was put forward. Considering HAZUS’s good performance in seismic assessment, a similar assessment system should be built in China as soon as possible. The first step should be classifying highway bridges in China based on their current situation and obtaining their seismic assessment model parameters roughly, which tend to be safe. The second step should be carrying out sufficient experiments and numerical analysis and revising the model parameters obtained in the first step.

The quality of virtual view based on multi-view video (MVD) plus depth format is often evaluated by PSNR or subjectively judged. However, due to synthesizing arbitrary view images, the virtual view images mostly have no reference images and are only assessed using non-reference. Virtual view images synthesized by depth estimation reference software (DERS) and view synthesis reference software (VSRS) often accompanied with blockiness and other distortions on the edge. In addition, matching level for the depth map and the corresponding texture maps of left and right views also affects the quality of the virtual view. This paper compares the edge similarity of the depth and the corresponding texture maps which generate the intermediate virtual view and combined with the virtual view’s blockiness which causing blur to evaluate the quality of the virtual view. Experiment results show that the proposed method can reflect the quality of the virtual view better.

Depth maps are used for synthesis virtual view in free-viewpoint television (FTV) systems. When depth maps are derived using existing depth estimation methods, the depth distortions will cause undesirable artifacts in the synthesized views. To solve this problem, a 3D video quality model base depth maps (D-3DV) for virtual view synthesis and depth map coding in the FTV applications is proposed. First, the relationships between distortions in coded depth map and rendered view are derived. Then, a precisely 3DV quality model based depth characteristics is develop for the synthesized virtual views. Finally, based on D-3DV model, a multilateral filtering is applied as a pre-processed filter to reduce rendering artifacts. The experimental results evaluated by objective and subjective methods indicate that the proposed D-3DV model can reduce bit-rate of depth coding and achieve better rendering quality.

A typical three-story unstiffened Steel Plate Shear Wall (SPSW) finite element model was established. Systematic parameters analysis of the development and changing process of the lateral stiffness and shear capacity was mainly carried on the middle standard layer. The result shows that the lateral stiffness of thin SPSW has been always in decline and has a higher shear capacity after buckling. According to lots of analysis data and different stages of lateral control targets in the new revised seismic design code for performance designing, the lateral limits of the SPSW were respectively qualified under wind loads and frequent earthquake.The test verification was also proposed to verify the restrictive lateral limits so as to supply a scientific basis for the preparation of SPSW design method.

Composite slab with steel sheeting deck is considered a continuous slab when it is under a constructional situation. Nevertheless, many recent researches are focused on simply supported slab. In order to determine the load carrying capacity regarding various rebar ratio on negative moment region, a numerical analysis was carried out by using finite element analysis. The result of analysis shows that the reinforced steel rebar increases load carrying capacity. Moreover, it has shown that the reinforced length of steel rebar also affect the load carrying capacity.

The section of the column under axial compression used in a certain electrostatic precipitator is composed of double H shaped steel limbs and the stiffened connecting web by weld. As the width of connecting web usually exceeds 3 times of the section height of H shaped steel, the axis which connecting web lies in is the weaker axis for the stiffness of column section, while the midperpendicular of connecting web is the stronger axis. In consideration of initial geometrical imperfections and weld residual stresses, the study on stability round the stronger axis of column subjected to axial compression by nonlinear finite element method is conducted. The research results indicate that the column doesn’t present the flexural buckling round the stronger axis, but present the elasto-plastic flexural-torsional buckling. A buckling factor is produced to measure the stability performance of column round stronger axis. When the connecting channel shaped steels between two limbs and the stiffeners located on connecting web are strengthened, the buckling factor increases slightly. When the width-thickness ratio of connecting web increases, the buckling factor decreases significantly. When the slenderness of H shaped steel round the stronger axis is kept constant and the height-thickness ratio of H-shaped steel web increases, the buckling factor increases. Based on a great many computation results, the regressed recommendation is proposed how to evaluate the design buckling bearing capacity of column under axial compression round stronger axis.

This project discovers the key determinants of CO 2 emissions associated with urban households in Xi'an (China) and Bangalore (India). Data was collected through household surveys in both cities. Descriptive statistics and multiple linear regression analysis were used to test the hypothesis that household CO 2 emission is a function of household attributes and the urban built environment. The findings show that ownership of motor vehicles and the use of electricity as well as income levels positively influence the level of household CO 2 emis- sions. The mix of job opportunities in a neighbourhood space has shown an inverse relationship with the level of household CO 2 emissions. The research calls for policy innovations in land-use and transportation planning for building low carbon cities.

This paper analyses the exsiting planning theory of rural roads in china. Through analysis into the background of rural roads development in the country, the paper puts forward a new planning method for rural roads based on the stakeholder theory; it also discusses the focus of rural road planning and the relevant institutional arrangement. Finally, exemplification is applied to prove the rationality and feasibility of this planning method.

With the change of macroeconomic and the acceleration of urbanization, the building of rail transit has been in the stage of high-speed development in China. How to make the great amending and compiling of the urban rail transit network based on the original would be a new problem. On the amending and compiling of the urban rail transit network, the paper indicates the key issues and main problems with systematic analytical method, analyses the principles with an empirical research method, and builds the general idea and key points with an important scientific thinking method.

Location and tracking the human faces is one of the critical technologies in free stereoscopic display system. But because of illumination variation or facial expression, it is difficult to detect human faces accurately and fast. In this paper, an infrared face detection based on real Adaboost algorithm and Cascade structure is implemented. With active infrared illumination, the problem caused by variation of illumination is almost solved, which makes the detection system more robust. Meanwhile, the combination of real Adaboost and Cascade structure pays more attention to the human faces which is more difficult to identify, making the detection quicker a lot. In the detection of video sequence, all human faces can be detected, and misdetection rarely appears. The average processing time on a windows XP, PIV 2.4GHz PC is about 40 ms for a 640*480-pixel image.So the improved detection is real-time. In addition, experiment proves that the improved detection behaves better when there is variation of facial expression or a little degree leaning of human face. Obviously, the improved detection is more efficient and could be used widely.

This paper presents a novel approach for depth recov- ery based on bifocus imaging. The imaging system with bifocus lenses may focus at different focal lengths of the same scene to produce bifocus images. Depth information can be extracted from the disparities between the image pair. This paper has given the detailed analysis of the system parameters and their approp- riate values in long range detection. According to the influences on depth resolution by system parameters, matching precision of image points plays an important role in depth measurement. An efficient method is proposed to calculate the locations of image points accurately. And a rotating imaging device is applied to improve depth resolution in the center region of field of view. Experimental results of sub-pixel registration, close and long range detection have demonstrated the depth measurement proposed of high precision. The relative error of recovered depth can be less than 0.4% when the photography distance is less than 800m and rotating angle is about o 40 .

A novel three-dimensional (3D) imaging lidar system which is based on a virtual instrument technique is introduced in this paper. The main characteristics of the system include: the capability of modeling a 3D object in accordance with the actual one by connecting to a geographic information system (GIS), and building the scene for the lidar experiment including the simulation environment. The simulation environment consists of four parts: laser pulse, atmospheric transport, target interaction, and receiving unit. Besides, the system provides an interface for the on-site experiment. In order to process the full waveform, we adopt the combination of pulse accumulation and wavelet denoising for signal enhancement. We also propose an optimized algorithm for data decomposition: the V–L decomposition method, which combines Vondrak smoothing and laser-template based fitting. Compared with conventional Gaussian decomposition, the new method brings an improvement in both precision and resolution of data decomposition. After applying V–L decomposition to the lidar system, we present the 3D reconstructed model to demonstrate the decomposition method.