Search

RGB-based methods have certain disadvantages because they lack 3D information and cannot cope with the pose estimation problem in cluttered scenes. Therefore, we propose a region-level pose estimation network that uses RGB-D images. We first extracted the objects’ color features and geometric features by convolutional neural networks (CNN) and PointNet, respectively, and then performed feature fusion. The fused features were fed into a region-level feature extraction network to obtain the region-level features, which extracted the local geometry features from the point cloud and learned the point set’s semantic information. We used the output of the region-level feature extraction network to perform region-level pose estimation, then selected the pose with the highest confidence level as the output and iteratively optimized the pose to obtain the final results. The experimental results showed that the proposed solution performed well on the LINEMOD data set, which verified the effectiveness of the proposed method in the pose estimation problem and the algorithm’s robustness in severely cluttered scenes.

By using a high-intensity flying focus laser, the dephasingless [Phys. Rev. Lett. 124 134802 (2020)] or phase-locked [Nat. Photon. 14 475 (2020)] laser wakefield acceleration (LWFA) can be realized, which may overcome issues of laser diffraction, pump depletion, and electron dephasing which are always suffered in usual LWFA. The scheme thus has the potentiality to accelerate electrons to TeV energy in a single acceleration stage. However, the controlled electron injection has not been self-consistently included in such schemes. Only external injection was suggested in previous theoretical studies, which requires other accelerators and is relatively difficulty to operate. Here, we numerically study the actively controlled density transition injection in phase-locked LWFA to get appropriate density profiles for amount of electron injection. The study shows that compared with LWFA driven by lasers with fixed focus, a larger plasma density gradient is necessary. Electrons experience both transverse and longitudinal loss during acceleration due to the superluminal group velocity of the driver and the variation of the wakefield structure. Furthermore, the periodic deformation and fracture of the flying focus laser in the high-density plasma plateau make the final injected charge also depend on the beginning position of the density downramp. Our studies show a possible way for amount of electron injection in LWFA driven by flying focus lasers.

The optimal parameters of the resistance spot welding process are discussed, combined with the development and practice of the automobile manufacturing industry. The value, significance, and basic theory of the resistance spot welding process orthogonal test are summarized, and the importance of the orthogonal test is recognized. Then summarize the orthogonal test specimen and equipment preparation, test design, and finally analyze the orthogonal test to conclude that the optimal parameters of the resistance spot welding process are optimized, that is, the welding time is 9cyc, the electrode pressure is 1600N, and the optimal welding current is It is 11.5kA, which provides a reference for future manufacturing.

Near-zero carbon emissions are the further deepening and implementation of low-carbon emissions and a dynamic process constantly moving towards zero carbon emissions. With the carbon formation life cycle as the core, the low-carbon park is divided into smart parks and ecological parks. They are starting from the four elements of planning, near-zero carbon technology, carbon emission management, and environmental health, and forming an index system architecture according to the park’s carbon emission traceability tracking system. When the park is in different stages of near-zero carbon development, the internal differences of evaluation indicators are also different. The constant weight evaluation method cannot reflect the impact of each indicator on the development of near-zero carbon, which will affect the accuracy of the evaluation results. By introducing variable weight theory, a penalty variable weight model is constructed, and the model is applied to the case park. Comparing the results of the constant-weight evaluation and variable-weight evaluation, it can be seen that the evaluation results of the variable-weight evaluation model are easier to distinguish the development level. The verification results show that the variable weight evaluation method is more suitable for the dynamic characteristics of near-zero carbon development.

An integrated energy system can improve the reliability and flexibility of the energy supply, and has good economic and environmental benefits. Integrated energy system evaluation is of great significance to the implementation of an integrated energy system project. The integrated energy system evaluation method is presented based on the minimum cross-entropy model and the prospect theory. Firstly, the minimum cross-entropy model is used to obtain the comprehensive column vector of each evaluation index. Secondly, the index weight is determined according to the different weight methods. Finally, through the establishment of positive and negative prospect value matrices, according to the comprehensive prospect value, the advantages and disadvantages of integrated energy system schemes are sorted. The effectiveness of the proposed method is verified by hotel-integrated energy system data.

We report an experimental demonstration of geopotential difference measurement using a pair of transportable 40Ca+ optical clocks (TOC-729-1 and TOC-729-3) in the laboratory, each of them has an uncertainty of 1.3 × 10−17 and an instability of 4.8 × 10 − 15 / τ . Referenced to a stationary clock of TOC-729-1, the geopotential difference measurements are realized by moving TOC-729-3 to three different locations and the relevant altitude differences are measured with uncertainties at the level of 20 cm. After correcting the systematic shifts (including gravitational red shift), the two-clock frequency difference is measured to be –0.7(2.2) × 10−17, considering both the statistic (1.0 × 10−17) and the systematic (1.9 × 10−17) uncertainties. The frequency difference between these two clocks is within their respective uncertainties, verifying the reliability of transportable 40Ca+ optical clocks at the low level of 10−17.

Endoscopic image has complex backgrounds and spatially different noise, bringing mainstream denoising methods to the problem of incomplete noise removal and the loss of image detail. Thus, an endoscopic image denoising algorithm based on spatial attention UNet network is proposed in this paper. UNet based on residual learning is utilized as the backbone network. Spatial attention modules based on noise intensity estimation and edge feature extraction modules are used to remove noise better while preserving the image details and improving generalization ability. We take endoscopic images of real scenes using gastroscopy and compare our method with mainstream methods. Experimental results show that our approach improves PSNR by 3.51 or 2.93 and SSIM by 0.03 or 0.015 compared with CBDNet or EDCNN, respectively. Our method can effectively improve the impact of noise on the image quality of endoscopic images, thus better assisting doctors in diagnosis and treatment.

In view of the lack of systematic investigation on the evaluation indexes of user-side integrated energy systems, a scientific and systematic evaluation index system is proposed from four aspects: energy efficiency, cost-effectiveness, energy supply quality and environmental protection, and the calculation methods of each index are given based on time-series simulation and sequential Monte Carlo simulation. The results indicate that the proposed evaluation index system can provide a foundation for the decision-making of the user-side integrated energy system planning scheme.

The Stellar Abundances and Galactic Evolution Survey (SAGES) is a multi-band photometric survey focused on estimation of stellar atmospheric parameters and interstellar extinction. In this paper we have derived photonic passbands for the intermediate-band u and v filters of the SAGES photometric system. The derived photonic passbands have been compared with those of the u and v filters of the Strömgren and SkyMapper systems. Synthetic photometry based on the derived photonic passbands could reproduce the observations very well. We have also derived observed, model-free extinction coefficients for the SAGES u and v bands (as well as the Pan-STARRS grizy bands) using the “standard pair” method. The derived reddening coefficients have been compared with those predicted by the extinction laws. Variations of reddening coefficients with effective temperatures and color excesses of B–V given by Schlegel et al. (E(B−V)SFD) have been investigated. No obvious trends or significant variations with effective temperatures have been found, but reddening coefficients for all the colors exhibit declining trends with increasing E(B−V)SFD, with typical relative variations of twenty-some percent from E(B − V)SFD ∼ 0 to 1.

Space radiation with inherently broadband spectral flux poses a huge danger to astronauts and electronics on aircraft, but it is hard to simulate such feature with conventional radiation sources. Using a tabletop laser-plasma accelerator, we can reproduce exponential energy particle beams as similar as possible to these in space radiation. We used such an electron beam to study the electron radiation effects on the surface structure and performance of two-dimensional material (FePS3). Energetic electron beam led to bulk sample cleavage and damage between areas of uneven thickness. For the FePS3 sheet sample, electron radiation transformed it from crystalline state to amorphous state, causing the sample surface to rough. The full widths at the half maximum of characteristic Raman peaks became larger, and the intensities of characteristic Raman peaks became weak or even disappeared dramatically under electron radiation. This trend became more obvious for thinner samples, and this phenomenon was attributed to the cleavage of P–P and P–S bonds, destabilizing the bipyramid structure of [P2S6]4– unit. The results are of great significance for testing the maximum allowable radiation dose for the two-dimensional material, implying that FePS3 cannot withstand such energetic electron radiation without an essential shield.

Fiber scaffolds prepared by electrospinning method can be used for the repairing of soft tissues such as skin, and have been widely used in biomedical field. The mechanical properties of scaffolds needed to be considered in the process of preparing scaffolds. Based on the principle of statistics and the method of micromechanics, a mechanical model for calculating the elastic characteristics of fiber scaffolds with spatial random distribution characteristics was established. The model comprehensively considered the parameters such as mechanical properties of constituent units of fiber scaffolds, fiber diameter and fiber density. The quantitative relationship between the elastic mechanical properties of fiber scaffolds and their tissue unit parameters can be calculated, which provided a research basis for further research and improvement of the mechanical properties of three-dimensional fiber scaffolds.

The traditional monitoring methods can only give warnings for the bolts with severe looseness. However, it is essential for the safety of bolted joints to detect the looseness of bolts at the very early stage. To this end, in this paper, coda wave interferometry (CWI)-based high-resolution bolt preload monitoring using a single piezoceramic transducer is proposed. According to the CWI and acoustoelastic theories, a theoretical model is established and the linear relationship between the time shifts of coda waves and the preload variations of the bolt is derived. An experiment, in which a piezoceramic transducer simultaneously functions as the actuator and sensor, was carried out to verify the effectiveness of the proposed method. Three lead zirconium titanate transducers at different locations of a bolted specimen are tested. The experimental results show that the time shifts of coda waves increase linearly with the decrease of bolt preload and the detectable resolution of bolt preload (DRBP) is up to 0.326%. The DRBP value proves that the proposed technique can successfully monitor bolt looseness at the very early stage. In addition, a comparison study is carried out between the CWI-based method and the energy-based wavelet packet decomposition (WPD) method, and the result shows that the preload sensitivity of the CWI-based method is about six times higher than that of the WPD approach. Therefore, the CWI-based method is an effective way for the in situ monitoring of bolt looseness, especially in the embryonic stage.

The “carbon double” goal calls for a further increase in the proportion of installed renewable energy capacity in China. The need to further expand the share of installed renewable energy capacity in China is increasing the need for ancillary peaking of the grid. There is also an ever-increasing need for peaking. The configuration of the energy storage system is one of the effective ways to reduce the peak load of each unit and increase the receiving space for renewable energy. Taking wind power generation as an example, the optimization model of thermal energy storage system is studied, the charging and discharging control strategy of energy storage system is designed, the integrated load impact on the grid due to wind power generation variation is considered, and the optimal economics and wind power generation are sought to maximize the comprehensive benefits.

Despite the rapid development of the green energy industry represented by solar photovoltaic, its ecological and environmental effects cannot be ignored. There were few reports on the impact of photovoltaic power station construction on soil bacterial community variation. In this study, the community abundance, diversity, structure, and distribution characteristics of soil bacterial in Gonghe photovoltaic power station, Qinghai Province were analyzed using quantitative Polymerase Chain Reaction techniques and Illumina MiSeq sequencing of the 16S ribosomal RNA gene. Quantitative PCR assay showed that the average16S rRNA gene copy numbers of bacteria in the soil were 8.04×109 copies per gram dry soil, which was significantly affected by the physicochemical properties of the soil. Illumina MiSeq sequencing illustrated that Actinobacteria (30.04%), Proteobacteria (29.38%), Firmicutes (2.69%), Bacteroidetes (1.51%), and Chloroflexi (1.07%) were the major phylum of soil bacterial communities, while Rubrobacter (2.51%) and Streptomyces (2.38%) was the main genera. The beta diversity indices of samples assessed via non-metric multidimensional scaling and cluster analysis indicated that the construction of a photovoltaic power station had no significant impact on the soil bacterial community structure. In addition, statistical product and service solutions and redundancy analysis demonstrated that the bacterial abundance and diversity were mainly regulated by soil water content, electrical conductivity, and other environmental factors. This study was the first time to analyze the spatial change of soil bacterial community in the desert under a photovoltaic field, which was of positive significance for the future assessment of how human disturbance affects the plant-bacteria-soil relationship in the desert ecosystem.

The contact joint in mechanical system will bring uncertainty, which leads to the uncertainty of dynamic response. Identification of interface stiffness is particularly important in the assembly process, such as bolt connection and rivet connection. In this paper, the contact joint can be regarded as a kind of structural discontinuity, and the contact joint in two beams is modeling with shear stiffness and bending stiffness. The wave theory is integrated into the Euler-Bernoulli beam theory to establish the relationship between the power reflection coefficient and the interface stiffness. The proposed method is verified by establishing a finite element model. The results show that the interface stiffness is accurately identified. In addition, the influence of interface stiffness on power reflection coefficient is discussed. This method has better local characteristics and avoids the disadvantages of identification by natural frequency method.

The existing assembly precision design mainly uses the tolerance and fit to control the geometric accuracy, and does not accurately grasp the influence of part deformation on assembly performance. In this study, a design theory and method for flexible body assembly is proposed, which considers the factors of tolerance and deformation. Firstly, based on the spatial multi-body kinematics, a reasonable modeling method of 3D tolerance of part surface suitable for product design process are given; Secondly, the deformation geometric features are calculated, and the 3D tolerance mathematical model including the part deformation is obtained by combining with the 3D tolerance modeling method; Finally, taking an engineering example as the research object, a 3D assembly deviation mathematical model including part deformation is constructed. The analysis results show that the cumulative deviation at the end of the system has a great influence on the z-direction precision in the system space, and the error is -0.028 mm. Therefore, the influence of part deformation deviation on assembly performance should be fully considered in the process of mechanical system assembly design. This research provides a theoretical basis for further research on precision prediction, simulation and control methods of mechanical system.

In order to achieve high assembly accuracy on the basis of low manufacturing accuracy and low cost, a method of deviation factor matching and optimization based on Taguchi theory is proposed. Firstly, the specific process of multi factor matching and optimization is given based on Taguchi theory. Secondly, the orthogonal experiments were set from the aspects of performance index, influencing factors determination, orthogonal table selection and so on, and the best level combination of each deviation was selected to form the factor matching and optimization experiment scheme based on Taguchi method. Finally, taking the horizontal machining center as the object, the Taguchi method is used to match the deviation factors of each mating surface, and the best parameter combination of control factors is A1B2C2D1E1, which verifies the effectiveness and practicability of Taguchi method. The research method in this study provides a strong support for the realization of high assembly accuracy and performance without increasing cost.

Dry-type transformer had the advantages of simple structure, easy maintenance, small environmental pollution, safe and reliable operation. It was widely used in power system distribution network. With the increase of urban power load year by year, large capacity dry type transformer had been highly concerned by the power industry. In this paper, the fluid-solid coupling calculation equation of a large capacity epoxy casting dry-type transformer was expounded, and a two-dimensional axisymmetric model of the transformer was established. The finite element method was used to calculate the temperature distribution and hot spot temperature with different wind speed and load rate. The results showed that when the wind speed at the transformer inlet was 0.7m/s and the load exceeded 120%, the temperature rise of the low-voltage winding reached 136.41°C, which had exceeded the temperature limit of the material. Therefore, the ventilation volume needed to be increased and the running time needed to be reduced. The research results could provide technical support for the design and safe operation of large capacity epoxy casting dry type transformer.

In the case of multi-sensors weighted data fusion with unknown prior knowledge, a weighted data fusion method based on measurement traversal correction is proposed. The fusion accuracy of multi-sensors data fusion is influenced by both the measurement data accuracy and the data fusion weights of sensors. The measurement data of sensors is corrected through analyzing the reliability of different time data measured by sensors. The fusion weights of multi-sensors data fusion are optimal through depply analyzing the influence of weight distribution on multi-sensors data fusion accuracy. Typical examples are used to validate the proposed fusion algorithm, and the result shows that the fusion result is satisfying, and the algorithm is theoretical and practical.

In the embedded system environment, both large amount of face image data and the slow recognition process speed are the main problem facing face recognition of end devices. This paper proposes a face recognition algorithm based on dual-channel images and adopts a cropped VGG-like model referred as VGG-cut model for predicting. The training set uses the same single-layer images of the same person combined into dual channels as a positive example, and single-layer images of different people are combined into dual channels as a negative example. After model training, the trained face verification model is used as the basis of face recognition, and the final recognition result can be obtained through loop matching and similarity ranking. The experimental results on a RISC-V embedded FPGA platform show that compared with the ResNet model called in Dlib, the VGG-like model and MobileFaceNet trained by Keras, our algorithm is increased by 240×, 88×, and 19× in recognition speed, respectively without significant accuracy reduction.

In order to find the influential manufacturing resources in a complex assembly system, a topology model of a complex assembly system was constructed based on the complex network theory. Complex network evaluation indicators with different attributes were used to evaluate the network, and AHP subjective weight method was used to determine the subjective weights between different evaluation indicators. Then the CRITIC weighting method was used to give the objective weights of each evaluation index, and perform subjective evaluation. The combination was modified to obtain the final combination weight, and the importance of key manufacturing resources was ranked by the TOPSIS comprehensive decision method. Based on the simulation calculation of the automobile assembly line network, the analysis and comparison of the ranking results were performed. The analysis results show that the comprehensive evaluation and comparison method has the comparative advantage of identifying key resources.

It is not conducive to green low-carbon development to pursuit very low wind power accommodation rate regardless of cost. In order to improve the efficiency of wind accommodation and realize the coordinated development of wind power and power grid, a “rational curtailment rate” of wind power should be studied and evaluated. This work proposes that the “rational curtailment rate” of wind power should be defined as a curtailment rate when the marginal wind power accommodation cost equals to the marginal wind power accommodation benefits at given level of installed wind capacity. The rational curtailment rate is related to the system peak shaving capacity and installed wind capacity. According to the rational curtailment rate, three development strategies are proposed to guide the improvement of wind power accommodation level and energy supply efficiency: First, calculate rational curtailment rate separately in every provinces, and establishing early warning standards for wind power construction differently. Second, the idea of wind power development should be adjusted to “adjust resources flexibly first”. Third, set up different wind power investment guidance for in different areas, indicated by rational curtailment rate.

A major issue in the successful realization of energy transformation in the 14th Five-Year Plan period is to solve the problem of optimizing the allocation and coordinated development of new energy and flexibly adjusting resources. During the 14th Five-Year Plan period, if the current new energy installation distribution ratio of the eastern and western regions is still maintained, it will be very difficult to control the overall curtailment rate of the new energy in the State Grid Management area below 5%. Another development option is to further tilt the installation of new energy towards the central and eastern regions, make full use of the local accommodation space in the central and Eastern regions. It is easier to achieve the total curtailment rate of new energy within 5%, and at the same time, the total installed capacities of new energy in the whole country can be further increased. It is also suggested that during the 14th Five-Year Plan period, the curtailment rate restriction should be relaxed to 8% moderately, which not only has better overall system economy, but is conducive to supporting a larger scale of new energy development and increase the proportion of new energy generation in total power generation.

Space-based resources play an important role in the observation and handling of emergency events, and are widely used in national economic activities. In recent years, the large increase in the number of orbital spacecraft and the strategic transformation of the aerospace equipment application model have made the practical task planning for multi-type satellites of practical significance. The research and application of space-based regional reconnaissance algorithms are of great significance for improving the comprehensive application efficiency of spacecraft, forming uniform coverage of key areas, and improving the uniformity of satellite resource utilization and situational awareness. Based on the actual background of engineering application, this paper describes the scheduling problem of Earth observation satellites. Under the constraints of satellite resource capability, observable time, conversion time between reconnaissance missions, energy, etc., a multi-satellite multi-target reconnaissance mission is established. Planning model. With the most resource-saving and high situational awareness uniformity as the optimization index, the optimized satellite reconnaissance mission planning scheme is obtained based on genetic algorithm.

During the past few years, signs of lepton flavor universality (LFU) violation have been observed in and transitions. Recently, the and polarization fractions and in decay were likewise measured by the Belle collaboration. Motivated by these intriguing results, we revisit the and anomalies in a scalar leptoquark (LQ) model, where two scalar LQs, one of which is a singlet and the other a triplet, are introduced simultaneously. We consider five mediated decays, , , , and , and focus on the LQ effects on the distributions of the branching fractions, LFU ratios, and various angular observables in these decays. Under the combined constraints of the available data on , , , and , we perform scans for the LQ couplings and make predictions for a number of observables. Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects, with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.

In past years, several hints of lepton flavor universality (LFU) violation have emerged from the and data. More recently, the Belle Collaboration has reported the first measurement of the longitudinal polarization fraction in the decay. Motivated by this intriguing result, along with the recent measurements of and polarization, we present the study of decays in supersymmetry (SUSY) with -parity violation (RPV). We consider , , and modes and focus on the branching ratios, LFU ratios, forward-backward asymmetries, polarizations of daughter hadrons, and the lepton. The RPV SUSY was capable of explaining the anomalies at the level, after taking into account various flavor constraints. In the allowed parameter space, the differential branching fractions and LFU ratios are largely enhanced by the SUSY effects, especially in the large dilepton invariant mass region. Moreover, a lower bound 10−6 is obtained. These observables could provide testable signatures at the high-luminosity LHC and SuperKEKB, and correlate with direct searches for SUSY.

Pumped-Storage Hydro (PSH) power units, especially variable speed units, have great roles in guaranteeing power system operation safety, stability and efficiency. As the investment cost of pumped-storage variable speed unit is higher than fixed speed unit, it is necessary to study its optimal scale. This paper used a scale optimization model for variable speed units based on power system security constrained unit combination model, which can demonstrate the most economic scale of variable speed units in all new pumped-storage power units under a given power supply planning. And then, calculation examples of multi-category regions in China were done, which shows that in a given power plan, demand on pumped storage variable speed units in the peak shaving and valley filling category region is the highest, followed by safety guarantee category, and demand on pumped storage variable speed units in feed end areas in proportioned new energy absorption category is relatively low.

Precise measurement of bolt preload force is particularly important in the assembly process of aviation equipment, which is directly related to the normal working performance and indicators of the equipment. According to the acoustoelastic effect, a model considering theoretical error and measurement error is proposed. The relationship between the change of time-of-flight (CTOF) and the bolt preload is established by the model. With the increase of the preload, the CTOF approximately increases linearly. Therefore, a smart piezoelectric bolt was developed. Piezoceramic transducer is embedded in the bolt head at pre-determined spatial locations. Experimental results show that the relative error of the smart bolt is about 1%. In addition, the influence of contact pressure and contact phase is discussed. The results show that the characteristic of smart piezoelectric bolt eliminates the effect of the couplant and makes the measurement more precise than the measurement performed using the ultrasonic probe. This method provides a promising way to measure the bolt preload.

In this paper, we present the dc and high-frequency characteristics of trigate polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) for RF applications. Trigate TFTs were fabricated using a 3D-IC process and designed with a multi-finger gate and multi-channel configuration. To obtain an optimal device design guideline, different source/drain (S/D) extension dimensions and channel layouts are investigated. We find that devices with a shorter or wider extension have higher cutoff frequencies (f T) and maximum oscillation frequencies (f max) owing to their lower S/D resistances. In addition, the high-frequency performance can be further improved by adopting the tapered channel structure, where the channel width increases gradually from the source to the drain. For the optimal device designs, the values of f T and f max are around 25 GHz and 30 GHz, respectively. The high f T and f max as well as excellent gate controllability in our devices indicate the trigate poly-Si TFT could be a suitable candidate for low-cost RFIC applications.