Pulsars in FIRST Observations

We identified 16 pulsars from the Faint Images of the Radio Sky at Twenty-cm (FIRST) at 1.4 GHz. Their positions and total flux densities are extracted from the FIRST catalog. Comparing the source positions with those in the PSRcatalog, we obtained better determined positions of PSRs J1022+1001, J1518+4904, J1652+2651, and proper motion upper limits of another three pulsars PSRs J0751+1807, J1012+5307, J1640+2224. Proper motions of the other 10 pulsars are consistent with the values in the catalog.Comment: 6 pages, 2 figures, 3 tables, submited to CJA

How are typical urban sewage treatment technologies going in China: from the perspective of life cycle environmental and economic coupled assessment

Sewage treatment is an important public service, but it consumes a lot of energy and chemicals in the process of removing wastewater pollutants, which may cause the risk of pollution transfer. To find the corresponding hot issues, this paper took the lead in integrating life cycle assessment (LCA) with life cycle costing (LCC) to evaluate four most typical sewage treatment technologies with more than 85% share in China. It is found that anaerobic/anoxic/oxic (AAO) was the optimal treatment scheme with relatively small potential environmental impact and economic load. The normalized results show that the trends of the four technologies on eleven environmental impact categories were basically the same. Marine aquatic ecotoxicity potential accounted for more than 70% of the overall environmental impact. Contribution analysis indicates that electricity and flocculant consumption were the main processes responsible for the environmental and economic burden. Overall, electricity consumption was the biggest hot spot. Sensitivity analysis verifies that a 10% reduction in electricity could bring high benefits to both the economy and the environment. These findings are expected to provide effective feedback on the operation and improvement of sewage treatment

Efficiency assessment of rural domestic sewage treatment facilities by a slacked-based DEA model

In the context of sustainable development, a number of rural domestic sewage treatment facilities had been built in China to solve the problem of rural domestic sewage pollution. The comprehensive, quantitative and objective efficiency assessment of facilities is urgent. This study used a non-radial slacked-based data envelopment analysis model combined with cluster analysis to construct an index system covering multiple aspects, including three inputs and four outputs to assess 681 facilities. These samples selected from the biggest demonstration area are the most representative for and exceed 2/5 of the running facilities all over the country. The average efficiency score of samples was 0.496 meaning the improvement potential was about 50.4%. Only 27 samples were relatively effective, scoring 1. The remaining 654 facilities had different levels of input excesses or output shortfalls, which should be the key objects to improve overall performance. In addition, there was evidence that output indicators had more room for improvement than input indicators. The analysis of sensitivity on inputs and outputs confirmed that the idleness and poor treatment effects of rural sewage treatment facilities should be concerned. Finally, Kruskal–Wallis non-parametric test verified that technology and load rate of facilities have significant impacts on efficiency. The performance evaluation results could not only provide guidance for the local government to strengthen the supervision and operation of facilities, but also potentially provide reference for the construction, operation and management of rural sewage treatment facilities in China

Electronic structure of chromium oxides, CrOn- and CrOn (n=1-5) from photoelectron spectroscopy and density functional theory calculations

The electronic structure of CrO−n and CrOn (n=1–5) was investigated using anion photoelectron spectroscopy and density functional theory. Photoelectron spectra of CrO−n were obtained at several photon energies and yielded electron affinities, vibrational and electronic structure information about the neutral CrOn species. Density functional theory calculations were carried out for both the neutrals and anions and were used to interpret the experimental spectra. Several low-lying electronic states of CrO were observed and assigned from photodetachment of the CrO− ground state(6∑+) and an excited state (4∏), which is only 0.1 eV higher. The main spectral features of CrO−2 were interpreted based on a C2v CrO−2 (4B1). A very weak Cr(O2)− isomer was also observed with lower electron binding energies. Relatively simple and vibrationally resolved spectra were observed for CrO−3, which was determined to be D3h. The CrO3 neutral was calculated to be C3v with the Cr atom slightly out of the plane of the three O atoms. The spectrum of CrO−4 revealed a very high electron binding energy. Several isomers of CrO−4 were predicted and the ground state has a distorted tetrahedral structure (C2) without any O–O bonding. Only one stable structure was predicted forCrO−5 with a superoxo O2 bonded to a C3v CrO3

A Survey and Experimental Study on Privacy-Preserving Trajectory Data Publishing

Trajectory data has become ubiquitous nowadays, which can benefit various real-world applications such as traffic management and location-based services. However, trajectories may disclose highly sensitive information of an individual including mobility patterns, personal profiles and gazetteers, social relationships, etc, making it indispensable to consider privacy protection when releasing trajectory data. Ensuring privacy on trajectories demands more than hiding single locations, since trajectories are intrinsically sparse and high-dimensional, and require to protect multi-scale correlations. To this end, extensive research has been conducted to design effective techniques for privacy-preserving trajectory data publishing. Furthermore, protecting privacy requires carefully balance two metrics: privacy and utility. In other words, it needs to protect as much privacy as possible and meanwhile guarantee the usefulness of the released trajectories for data analysis. In this survey, we provide a comprehensive study and a systematic summarization of existing protection models, privacy and utility metrics for trajectories developed in the literature. We also conduct extensive experiments on two real-life public trajectory datasets to evaluate the performance of several representative privacy protection models, demonstrate the trade-off between privacy and utility, and guide the choice of the right privacy model for trajectory publishing given certain privacy and utility desiderata

Eocene–early Oligocene climate and vegetation change in southern China: Evidence from the Maoming Basin

Although the Eocene-Oligocene climate transition marks a critical point in the development of the ‘icehouse’ global climate of the present little is known about this important change in the terrestrial realm at low latitudes. Our palynological study of the Shangcun Formation shows it to be early Oligocene in age: palyno-assemblages in the lower part of the formation indicate a cool interval dominated by conifer pollen in the earliest Oligocene followed by a warmer regime in the second half of the early Oligocene. To quantify middle Eocene to late early Oligocene climate conditions at low (~ 20°N) palaeolatitudes in southern Asia several thousand leaf fossil specimens from the Maoming Basin, southern China, were subjected to a multivariate (CLAMP) analysis of leaf form. For terrestrial palaeoclimate comparisons to be valid the palaeoaltitude at which the proxy data are obtained must be known. We find that leaves preserved in the Youganwo (middle Eocene), Huangniuling (late Eocene) and Shangcun (early Oligocene) formations were likely to have been deposited well above sea level at different palaeoelevations. In the Youganwo Formation fine-grained sediments were deposited at an altitude of ~ 1.5 km, after which the basin dropped to ~ 0.5 km by the time the upper Huangniuling sediments were deposited. The basin floor then rose again by 0.5 km reaching an altitude of approximately 1 km in which the Shangcun Formation fine-grained sediments were accumulated. Within the context of these elevation changes the prevailing climates experienced by the Youganwo, Lower Huangniuling, Upper Huangniuling and Shangcun fossil floras were humid subtropical with hot summers and warm winters, but witnessed a progressive increase in rainfall seasonality. By the early Oligocene rainfall seasonality was similar to that of the modern monsoonal climate of Guangdong Province, southern China. All floras show leaf physiognomic spectra most similar to those growing under the influence of the modern Indonesia-Australia Monsoon, but with no evidence of any adaptation to today's South or East Asia Monsoon regimes. The Upper Huangniuling Flora, rich in dipterocarp plant megafossils, grew in the warmest conditions with the highest cold month mean temperature and at the lowest altitude

Sustainability efficiency assessment of wastewater treatment plants in China: A data envelopment analysis based on cluster benchmarking

Quantitative evaluation on the efficiency of wastewater treatment plants (WWTPs) is a key issue that needs to be solved. For this purpose, data envelopment analysis (DEA) was employed to establish a comprehensive efficiency evaluation system on WWTPs, including three inputs of operating cost, electricity consumption and labor, three desirable outputs of chemical oxygen demand (COD) removal rate, ammonia nitrogen (NH3–N) removal rate and reclaimed water yield, and one undesirable output of dry sludge yield. 861 WWTPs in China were assessed by a slacked-based DEA model based on cluster benchmarking. The technology gap ratio (TGR) confirmed that large WWTPs operated more efficiently than small ones. The WWTPs had an average efficiency score of 0.611. Among them, 170 samples were relatively efficient with a score of 1, which means these samples could be a benchmark for other inefficient samples. Different degrees of input excesses or output shortfalls existed in 691 inefficient samples and these samples should be the key objects to improve the operational efficiency. Furthermore, through the Kruskal-Wallis test, the influent COD concentration and capacity load rate showed significant effects on the WWTP performance. These findings, derived from a simple but effective framework, have potential value for managers to make decisions

Competition between linear and cyclic structures in monochromium carbide clusters CrCn- and CrCn (n=2-8): A photoelectron spectroscopy and density functional study

Photoelectron spectroscopy (PES) is combined with density functional theory (DFT) to study the monochromium carbide clusters CrC−n and CrCn (n=2–8). Well-resolved PES spectra were obtained, yielding structural, electronic, and vibrational information about both the anionic and neutral clusters. Experimental evidence was observed for the coexistence of two isomers for CrC−2, CrC−3, CrC−4, and CrC−6. Sharp and well-resolved PES spectra were observed for CrC−n (n=4,6,8), whereas broad spectra were observed for CrC−5 and CrC−7. Extensive DFT calculations using the generalized gradient approximation were carried out for the ground and low-lying excited states of all the CrC−n and CrCn species, as well as coupled-cluster calculations for CrC−2 and CrC2. Theoretical electron affinities and vertical detachment energies were calculated and compared with the experimental data to help the assignment of the ground states and obtain structural information. We found that CrC−2 and CrC−3 each possess a close-lying cyclic and linear structure, which were both populated experimentally. For the larger CrC−n clusters with n=4, 6, 8, linear structures are the overwhelming favorite, giving rise to the sharp PES spectral features. CrC−7 was found to have a cyclic structure. The broad PES spectra of CrC−5 suggested a cyclic structure, whereas the DFT results predicted a linear one

Interfacial microstructure and strengthening mechanism of dissimilar laser al/steel joint via a porous high entropy alloy coating

Publisher Copyright: © 2023 The Authors This work was supported by the National Natural Science Foundation of China (No. 52275155) and Class III Peak Discipline of Shanghai-Materials Science and Engineering. JPO acknowledges funding by national funds from FCT-Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nano-modelling and Nanofabrication-i3N.A porous high entropy alloy (HEA) coating was prepared on a steel surface by vacuum sintering. The coating was then used as a transition layer during dissimilar laser joining of Al to steel. Compared with the uncoated laser joints, the liquid alloy spread and infiltrated into the porous structure, the contact angle of the weld reduced from 65.8° to 56.7°, and the brazed width increased from 5.1 mm to 5.9 mm, which improved the wettability and spreadability of the molten filler wire on the substrate. In the case of the uncoated steel, the fusion zone/steel interfacial microstructure consisted of laminated Al7·2Fe1·8Si and Fe(Al,Si)3, while it changed to a composite-like structure containing a soft HEA skeleton and hard IMCs which included Al7·2Fe1·8Si, Al3Ni, and (Al,Si)2Cr. In addition, due to the sluggish diffusion effect of HEAs, a layer of gradient nanocrystalline composed of Al7·2Fe1·8Si was generated, which significantly strengthened the dissimilar laser joints with improvements in both the fracture load (∼26.5%) and the displacement (∼101.8%). The fracture mode changed from brittle to ductile failure when the porous HEA coating was applied, with fracture propagating through the HEA skeleton. This work provides a novel solution for the strengthening of hard-to-join dissimilar combinations.publishersversionpublishe

Persistence, extinction and spatio-temporal synchronization of SIRS cellular automata models

Spatially explicit models have been widely used in today's mathematical ecology and epidemiology to study persistence and extinction of populations as well as their spatial patterns. Here we extend the earlier work--static dispersal between neighbouring individuals to mobility of individuals as well as multi-patches environment. As is commonly found, the basic reproductive ratio is maximized for the evolutionary stable strategy (ESS) on diseases' persistence in mean-field theory. This has important implications, as it implies that for a wide range of parameters that infection rate will tend maximum. This is opposite with present results obtained in spatial explicit models that infection rate is limited by upper bound. We observe the emergence of trade-offs of extinction and persistence on the parameters of the infection period and infection rate and show the extinction time having a linear relationship with respect to system size. We further find that the higher mobility can pronouncedly promote the persistence of spread of epidemics, i.e., the phase transition occurs from extinction domain to persistence domain, and the spirals' wavelength increases as the mobility increasing and ultimately, it will saturate at a certain value. Furthermore, for multi-patches case, we find that the lower coupling strength leads to anti-phase oscillation of infected fraction, while higher coupling strength corresponds to in-phase oscillation.Comment: 12page