Pedestrian recognition has great practical value and is a vital step toward applying path planning and intelligent obstacle avoidance in autonomous driving. In recent years, laser radar has played an ...essential role in pedestrian detection and recognition in unmanned driving. More accurate high spatial dimension and high-resolution data could be obtained by building a three-dimensional point cloud. However, the point cloud data collected by laser radar is often massive and contains a lot of redundancy, which is not conducive to transmission and storage. So, the processing speed grows slow when the original point cloud data is used for recognition. On the other hand, the compression processing of many laser radar point clouds could save computing power and speed up the recognition processing.
The article utilizes the fusion point cloud data from laser radar to investigate the fast pedestrian recognition algorithm. The focus is to compress the collected point cloud data based on the boundary and feature value extraction and then use the point cloud pedestrian recognition algorithm based on image mapping to detect pedestrians. This article proposes a point cloud data compression method based on feature point extraction and reduced voxel grid.
The Karlsruhe Institute of Technology and Toyota Technological Institute data set is used to investigate the proposed algorithm experimentally. The outcomes indicate that the peak signal-to-noise ratio of the compression algorithm is improved by 6.02%. The recognition accuracy is improved by 16.93%, 17.2%, and 16.12%, corresponding to simple, medium, and difficult scenes, respectively, when compared with the point cloud pedestrian recognition method based on image mapping, which uses the random sampling method to compress the point cloud data.
The proposed method could achieve data compression better and ensure that many feature points are retained in the compressed Point Cloud Data (PCD). Thus, the compressed PCD achieves pedestrian recognition through an image-based mapping recognition algorithm.
In this work, BiOBr and BiOBr/ZnO were produced by using a simple hydrothermal method, and then were modified by a short-time low temperature plasma treatment using the gas of argon mixed with 3% ...hydrogen in pulsed mode with the fixed cycle discharge times. The related morphological, crystal, chemical, optical and photocatalytic properties were investigated. A three-dimensional flower-like structure of pure BiOBr and layered ultrathin nanosheets structure of BiOBr/ZnO can be observed. And the plasma treatment process at the discharge power of 100 W would not affect their basic morphologies. However, the changes in the surface chemical bonding has been identified, which indicates the presence of strong electronic interactions and strong chemical bonds caused by the plasma modification. The photodegradation rate has been greatly improved by mixing BiOBr with ZnO since the heterojunction structure was built during the hydrothermal process. Moreover, the photocatalytic activity can be further improved after the plasma treatment, it is attributed to the higher photogenerated carrier separation rate and narrow band gap due to the defects generated by the surface plasma effects.
•3D flower-like structure of BiOBr and layered ultrathin nanosheets of BiOBr/ZnO were obtained.•BiOBr-ZnO heterojunction structure was built by a simple hydrothermal method.•Surface defects were generated by the short time plasma process.•Photocatalytic activity was obviously improved by the heterojunction structure and plasma modification.
As the key for haze control, atmospheric fine particulate matter with aerodynamic diameter <2.5μm (or PM2.5) is of great concern lately in China. It is closely linked to fast pace of urbanization, ...industrialization and economic development, especially in eastern China. A good understanding of its sources is required for effective pollution abatement. Receptor models are one of the major methods for source apportionment used in China. The major objective of this study is to understand sources that contribute to fine particulate matter in China and key challenges in this area. Spatial distribution of fine particulate matter concentration, chemical composition and dominant sources in North and South China are summarized. Based on chemical speciation results from 31 cities and source apportionment results from 21 cities, it is found that secondary sources and traffic emission have higher contribution in South China while the percentage of coal combustion, dust and biomass burning to total PM2.5 are higher in North China. Source profiles established in China from 44 cities and areas are also summarized as references for future source apportionment studies. Suggestions for future research are also provided including methods for evaluating source apportionment results, ways for integrating multiple source apportionment methods, the need for standardizing protocols and developing tools for high-time resolution source apportionment.
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•Spatial distribution of chemical speciation, sources and source profiles in China are summarized.•In the south, contributions of secondary and traffic sources are higher while coal and dust are lower.•Future research needs for source apportionment in China are proposed.
As a peer-to-peer “P2P” distributed ledger, the blockchain has the advantages of decentralization, no trust, open autonomy, and nontampering. Therefore, many users are willing to conduct transactions ...in blockchain cryptocurrency systems such as Bitcoin and Ethereum. However, the throughput of traditional blockchain is extremely low, and the transaction is so delayed. The payment channel network is the most promising solution to expand the blockchain for widespread use. Achieving secure instant payment on the payment channel can significantly increase transaction throughput and reduce transaction delays. When the payment channel is closed, the balance in the channel will be returned to an account on the blockchain. In this paper, we discuss the design and the implementation of a multiparty payment channel network based on smart contracts. Where a two-party payment channel is designed based on blockchain and smart contracts, a new multiparty payment channel is established on the basis of the payment channel. A detailed definition and description are given, and the creation, update, and closing functions of the multiparty payment channel are designed. Moreover, we design a multiparty payment channel smart contract, deploy it to the local private blockchain, and conduct simulation and testing. The delay time of different transaction methods is counted, and the network topology type, transaction amount, and other factors are studied. The impact of transaction success rate and the gas consumption of different transaction methods are analyzed through multiple sets of experimental statistics.
•Drying process effects on roasted coffee bean quality properties were measured.•Volatile and taste components were profiled by E-nose, E-tongue, and HS-SPME-GC-MS.•Three dimensional datasets plus ...statistical modelling clearly discriminated samples.•Heat pump drying best preserved volatiles, producing high quality dried coffee.
In this study, room-temperature drying, solar drying, heat pump drying (HPD), hot-air drying, and freeze drying were applied to investigate the volatile profiles and taste properties of roasted coffee beans by using electronic nose, electronic tongue, and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Results indicated that the drying process markedly affected pH, total titratable acidity, total solids, and total soluble solids. Significant differences existed among all samples based on drying method; and the HPD method was superior for preserving ketones, phenols, and esters. Principal component analysis (PCA) combined with E-nose and E-tongue radar charts as well as the fingerprint of HS-SPME-GC-MS could clearly discriminate samples from different drying methods, with results obtained from hierarchical cluster analysis (the Euclidean distance is 0.75) being in agreement with those of PCA. These findings may provide a theoretical basis for the dehydration of coffee beans and other similar thermo-sensitive agricultural products.
Fringe projection profilometry (FPP) has been widely used for 3D reconstruction, surface measurement, and reverse engineering. However, if the surface of an object has a high reflectivity, ...overexposure can easily occur. Image saturation caused by overexposure can lead to an incorrect intensity of the captured pattern images, resulting in phase and measurement errors of FPP. To address this issue, we propose a phase retrieval method for the 3D shape measurement of high-reflectivity surfaces based on π phase-shifting fringes. Our method only requires eight images to be projected, including three single-frequency three-step phase-shifting patterns and one pattern used to provide phase unwrapping constraints, called conventional patterns, as well as the π phase-shifting patterns corresponding to the four conventional patterns, called supplemental patterns. Saturated pixels of conventional fringes are replaced by unsaturated pixels in supplemental fringes to suppress phase retrieval errors. We analyzed all 16 replacement cases of fringe patterns and provided calculation methods for unwrapped phases. The main advantages of our method are as follows: (1) By combining the advantages of the stereo phase unwrapping (SPU) algorithm, the number of projected fringes is reduced. (2) By utilizing the phase unwrapping constraint provided by the fourth fringe pattern, the accuracy of SPU is improved. For highly reflective surfaces, the experimental results demonstrate the performance of the proposed method.
Fast permeation and effective solute-solute separation provide the opportunities for sustainable water treatment, but they are hindered by ineffective membranes. We present here the construction of a ...nanofiltration membrane with fast permeation, high rejection, and precise Cl
/SO
separation by spatial and temporal control of interfacial polymerization via graphitic carbon nitride (g-C
N
). The g-C
N
nanosheet binds preferentially with piperazine and tiles the water-hexane interface as revealed by molecular dynamics studies, thus lowering the diffusion rate of PIP by one order of magnitude and restricting its diffusion pathways towards the hexane phase. As a result, membranes with nanoscale ordered hollow structure are created. Transport mechanism across the structure is clarified using computational fluid dynamics simulation. Increased surface area, lower thickness, and a hollow ordered structure are identified as the key contributors to the water permeance of 105 L m
·h
·bar
with a Na
SO
rejection of 99.4% and a Cl
/SO
selectivity of 130, which is superior to state-of-the-art NF membranes. Our approach for tuning the membrane microstructure enables the development of ultra-permeability and excellent selectivity for ion-ion separation, water purification, desalination, and organics removal.
Summary Background Human infection with avian influenza A H7N9 virus emerged in eastern China in February, 2013, and has been associated with exposure to poultry. We report the clinical and ...microbiological features of patients infected with influenza A H7N9 virus and compare genomic features of the human virus with those of the virus in market poultry in Zhejiang, China. Methods Between March 7 and April 8, 2013, we included hospital inpatients if they had new-onset respiratory symptoms, unexplained radiographic infiltrate, and laboratory-confirmed H7N9 virus infection. We recorded histories and results of haematological, biochemical, radiological, and microbiological investigations. We took throat and sputum samples, used RT-PCR to detect M, H7, and N9 genes, and cultured samples in Madin-Darby canine kidney cells. We tested for co-infections and monitored serum concentrations of six cytokines and chemokines. We collected cloacal swabs from 86 birds from epidemiologically linked wet markets and inoculated embryonated chicken eggs with the samples. We identified and subtyped isolates by RT-PCR sequencing. RNA extraction, complementary DNA synthesis, and PCR sequencing were done for one human and one chicken isolate. We characterised and phylogenetically analysed the eight gene segments of the viruses in the patient's and the chicken's isolates, and constructed phylogenetic trees of H, N, PB2, and NS genes. Findings We identified four patients (mean age 56 years), all of whom had contact with poultry 3–8 days before disease onset. They presented with fever and rapidly progressive pneumonia that did not respond to antibiotics. Patients were leucopenic and lymphopenic, and had impaired liver or renal function, substantially increased serum cytokine or chemokine concentrations, and disseminated intravascular coagulation with disease progression. Two patients died. Sputum specimens were more likely to test positive for the H7N9 virus than were samples from throat swabs. The viral isolate from the patient was closely similar to that from an epidemiologically linked market chicken. All viral gene segments were of avian origin. The H7 of the isolated viruses was closest to that of the H7N3 virus from domestic ducks in Zhejiang, whereas the N9 was closest to that of the wild bird H7N9 virus in South Korea. We noted Gln226Leu and Gly186Val substitutions in human virus H7 (associated with increased affinity for α-2,6-linked sialic acid receptors) and the PB2 Asp701Asn mutation (associated with mammalian adaptation). Ser31Asn mutation, which is associated with adamantane resistance, was noted in viral M2. Interpretation Cross species poultry-to-person transmission of this new reassortant H7N9 virus is associated with severe pneumonia and multiorgan dysfunction in human beings. Monitoring of the viral evolution and further study of disease pathogenesis will improve disease management, epidemic control, and pandemic preparedness. Funding Larry Chi-Kin Yung, National Key Program for Infectious Diseases of China.
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented public health crisis. Because of the novelty ...of the virus, there are currently no SARS-CoV-2-specific treatments or vaccines available. Therefore, rapid development of effective vaccines against SARS-CoV-2 are urgently needed. Here, we developed a pilot-scale production of PiCoVacc, a purified inactivated SARS-CoV-2 virus vaccine candidate, which induced SARS-CoV-2-specific neutralizing antibodies in mice, rats, and nonhuman primates. These antibodies neutralized 10 representative SARS-CoV-2 strains, suggesting a possible broader neutralizing ability against other strains. Three immunizations using two different doses, 3 or 6 micrograms per dose, provided partial or complete protection in macaques against SARS-CoV-2 challenge, respectively, without observable antibody-dependent enhancement of infection. These data support the clinical development and testing of PiCoVacc for use in humans.
This study aimed to investigate the impact of perceived social support on the depression of postpartum women, and mainly focuses on confirming the mediator role of self-efficacy. A total of 427 new ...mothers from two general hospitals in Beijing accomplished the Multidimensional Scale of Perceived Social Support, General Self-efficacy Scale, and Edinburgh Postnatal Depression Scale. The results revealed that both social support and self-efficacy significantly correlate with postpartum depression. Structural equation modeling indicated that self-efficacy partially mediates the relationship between social support and postpartum depression.
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