Comparative sorption kinetic studies of ammonium onto zeolite

Abstract The sorption kinetics of ammonium onto three types of zeolite, natural zeolite, natural zeolite covered by biofilm and ammonium-bearing zeolite covered by biofilm, at two particle sizes were studied. The pseudo-first order and pseudo-second order models were fitted to the results by a non-linear method. The batch sorption model, based on a pseudo-second order mechanism, was applied to predict the rate constant of sorption, the equilibrium capacity and the initial sorption rate. Ion exchange between NH 4 + and cations in the zeolite increased with decreasing particle size of the zeolite. Biofilm covered on the zeolite did not affect the ion exchange for the smaller particle size but decreased the ion exchange capacity by 22% for the larger particle size. In addition, bioregeneration should be considered for the recovery of ion exchange capacity of the bio-zeolite made from ammonium-bearing zeolite by the microorganisms in the biofilm, 78.0 and 63.9% regeneration for the smaller and larger particle size of zeolite, respectively

Discovery of Charge Order in the Transition Metal Dichalcogenide Fex_{x}NbS2_2

The Fe intercalated transition metal dichalcogenide (TMD), Fe$_{1/3}$NbS$_2$, exhibits remarkable resistance switching properties and highly tunable spin ordering phases due to magnetic defects. We conduct synchrotron X-ray scattering measurements on both under-intercalated ($x$ = 0.32) and over-intercalated ($x$ = 0.35) samples. We discover a new charge order phase in the over-intercalated sample, where the excess Fe atoms lead to a zigzag antiferromagnetic order. The agreement between the charge and magnetic ordering temperatures, as well as their intensity relationship, suggests a strong magnetoelastic coupling as the mechanism for the charge ordering. Our results reveal the first example of a charge order phase among the intercalated TMD family and demonstrate the ability to stabilize charge modulation by introducing electronic correlations, where the charge order is absent in bulk 2H-NbS$_2$ compared to other pristine TMDs

Extracting Key Traffic Parameters from UAV Video with On-Board Vehicle Data Validation

The advantages of UAV video in flexibility, traceability, easy-operation, and abundant information make it a popular and powerful aerial tool applied in traffic monitoring in recent years. This paper proposed a systematic approach to detect and track vehicles based on the YOLO v3 model and the deep SORT algorithm for further extracting key traffic parameters. A field experiment was implemented to provide data for model training and validation to ensure the accuracy of the proposed approach. In the experiment, 5400 frame images and 1192 speed points were collected from two test vehicles equipped with high-precision GNSS-RTK and onboard OBD after completion of seven experimental groups with a different height (150 m to 500 m) and operating speed (40 km/h to 90 km/h). The results indicate that the proposed approach exhibits strong robustness and reliability, due to the 90.88% accuracy of object detection and 98.9% precision of tracking vehicle. Moreover, the absolute and relative error of extracted speed falls within ±3 km/h and 2%, respectively. The overall accuracy of the extracted parameters reaches up to 98%

On spatial-range closest-pair query

Abstract. An important query for spatial database research is to find the closest pair of objects in a given space. Existing work assumes two objects of the closest pair come from two different data sets indexed by R-trees. The closest pair in the whole space will be found via an optimzed R-tree join technique. However, this technique doesn’t perform well when the two data sets are identical. And it doesn’t work when the search range is some area other than the whole space. In this paper, we address the closest pair problem within the same data set. Further more, we propose a practical extension to the closest pair problem to involve a query range. The problem now becomes finding the closest pair of objects among those inside a given range. After extending the existing techniques to solve the new problem, we proposed two index structures based on augmenting the R-tree and we also give algorithms for maintaining these structrures. Experimental results show that our structures are more robust than earlier approaches.

Optimization of Scanning and Counting Sensor Layout for Full Route Observability with a Bi-Level Programming Model

Utilizing the data obtained from both scanning and counting sensors is critical for efficiently managing traffic flow on roadways. Past studies mainly focused on the optimal layout of one type of sensor, and how to optimize the arrangement of more than one type of sensor has not been fully researched. This paper develops a methodology that optimizes the deployment of different types of sensors to solve the well-recognized network sensors location problem (NSLP). To answer the questions of how many, where and what types of sensors should be deployed on each particular link of the network, a novel bi-level programming model for full route observability is presented to strategically locate scanning and counting sensors in a network. The methodology works in two steps. First, a mathematical program is formulated to determine the minimum number of scanning sensors. To solve this program, a new ‘differentiating matrix’ is introduced and the corresponding greedy algorithm of ‘differentiating first’ is put forward. In the second step, a scanning map and an incidence matrix are incorporated into the program, which extends the theoretical model for multiple sensors’ deployment and provides the replacement method to reduce total cost of sensors without loss of observability. The algorithm developed at the second step involved in two coefficient matrixes from scanning map and incidence parameter enumerate all possibilities of replacement schemes so that cost of different combination schemes can be compared. Finally, the proposed approach is demonstrated by comparison of Nguyen-Dupuis network and real network, which indicates the proposed method is capable to evaluate the trade-off between cost and all routes observability

Analysis of System Reliability for Cache Coherence Scheme in Multi-Processor

Abstract-In this paper, a cache coherence scheme in multiprocessor is introduced. There is a specific model in each kind of software; cache coherence can be solved in AHB bus by these models. First, we use dynamic address mapping policy to realize data cache. Second, according to the randomness of application environment that set up shared cache adaptive configuration and management mechanism in the finite state machine timing sequence model of each kind of software, to ensure the system reliability. In order to support multi-tasking and multi-user operator system -Linux, the multi-processor must use shared memory technology, so this paper also introduced the memory management unit, and base on these, it focuses on how multi-processor and the AHB bus cooperate to ensure cache coherence of the whole system. We can use software execution model and hardware design to achieve instruction or data coherence between each cache and main memory

Polymorphisms of the DNA methyltransferase 1 associated with reduced risks of Helicobacter pylori infection and increased risks of gastric atrophy.

INTRODUCTION: DNA methyltransferase-1(DNMT1) is an important enzyme in determining genomic methylation patterns in mammalian cells. We investigated the associations between SNPs in the DNMT1 gene and risks of developing H. pylori seropositivity, gastric atrophy and gastric cancer in the Chinese population. METHODS: The study consisted of 447 patients with gastric cancer; 111 patients with gastric atrophy; and 961 healthy controls. Five SNPs, rs10420321, rs16999593, rs8101866, rs8111085 and rs2288349 of the DNMT1 gene were genotyped. Anti-H.pylori IgG was detected by ELISA. Gastric atrophy was screened by the level of serum pepsinogen Ι and II and then confirmed by endoscopy and histopatholgical examinations. RESULTS: The age- and sex-adjusted OR of H. pylori seropositivity was 0.67 (95%CI: 0.51-0.87) for rs8111085 TC/CC genotypes, significantly lower than the TT genotype in healthy controls. The adjusted OR of H.pylori seropositivity was 0.68 (95%CI: 0.52-0.89) for rs10420321 AG/GG genotypes. In addition, patients carrying rs2228349 AA genotype have a significantly increased risk for H.pylori seropositivity (OR=1.67; 95%CI: 1.02-2.75). Further haplotype analyses also showed that the ATTTG and ATCTA are significantly associated with increased risks in H.pylori infection compared to the GTCCG haplotype (OR=1.38, 95%CI: 1.08-1.77; OR=1.40, 95% CI: 1.09-1.80). The adjusted ORs of gastric atrophy were 1.66 (95%CI: 1.06-2.61) for rs10420321 GG genotype, and 1.67 (95%CI 1.06-2.63, P=0.03) for rs8111085 CC genotype, but no association was found between SNPs in the DNMT1 gene and risk of developing gastric cancer. CONCLUSIONS: Individuals with rs10420321 GG and rs8111085 CC genotype of the DNMT1 gene were associated with reduced risks for H.pylori infection. On the other hand, higher risks of gastric atrophy were found in the carriers with these two genotypes compared to other genotypes. Our results suggested that SNPs of DNMT1 could be used as genotypic markers for predicting genetic susceptibilities to H.pylori infection and risks in gastric atrophy

Magnetic‐Dielectric Complementary Fe‐Co‐Ni Alloy/Carbon Composites for High‐Attenuation C‐Band Microwave Absorption via Carbothermal Reduction of Solid‐Solution Precursor

Abstract Ferromagnetic alloys/carbon composites with excellent electrical and magnetic properties are highly desirable as electromagnetic wave absorption materials, but achieving high‐attenuation performance in C‐band (4–8 GHz) remains a challenge. Herein, a direct carbothermal reduction of organic gluconate solid‐solution precursor method is developed to synthesize ferromagnetic Fe‐Co‐Ni alloy/carbon composites, which realize high‐attenuation electromagnetic wave absorption in C‐band. By virtue of Fe, Co, and Ni elements homogeneously dispersing at the molecular level in the solid‐solution precursor with the regulated mole ratio, serial FeCo2Ni/C, Co7Fe3/C, FeNi3/C, and Co3Ni/C composites can be deliberately prepared. First‐principles calculations and off‐axis electron holograms can clearly unravel that these Fe‐Co‐Ni alloys could perform as excellent dielectric‐magnetic complementary loss units to trigger synergistic electronic dipole polarization oscillation, magnetic moment resonance, and magnetic coupling interaction. Meanwhile, the rich alloy–carbon interfaces and conductive carbon skeleton can facilitate delightful interfacial polarization and conductive loss. Combining these positive electromagnetic energy dissipation characteristics, FeCo2Ni/C with strengthened dipole polarization oscillation and outstanding impedance matching realizes an extremely high‐attenuation absorption performance with a minimum reflection loss of −82.2 dB at 5.21 GHz. This work provides a feasible and flexible insight into producing magnetic‐dielectric complementary Fe‐Co‐Ni alloys/carbon composites with various alloy compositions as excellent electromagnetic wave absorbers

Atmospheric Concentrations and Air-Soil Exchange of Polycyclic Aromatic Hydrocarbons (PAHs) in Typical Urban-Rural Fringe of Wuhan-Ezhou Region, Central China

During the summer of 2015, polycyclic aromatic hydrocarbons (PAHs) in the atmosphere were collected by passive air samplers in typical urban-rural fringe of Wuhan-Ezhou region, Central China. The results showed that 16 kinds of PAHs were ubiquitous with the concentrations of n-ary sumation 16PAHs from 14.69 to 136.30 ng center dot m(-3) and the mean concentration of 43.03 ng center dot m(-3). Phenanthrene (Phe), fluoranthene (Fla) and pyrene (Pyr) were major components, which accounted for 81% of n-ary sumation 16PAHs. PAHs atmospheric concentrations presented obvious spatial variation, being significantly related to geographical environment and influenced by anthropogenic activity. Air-soil exchange status of PAHs was discussed according to the fugacity fraction (ff). The results showed that HMW-PAHs behaved as net deposition, while LMW-PAHs were more likely to establish dynamic equilibrium between atmosphere and soil than MMW-PAHs and HMW-PAHs. For some PAHs, such as acenaphthylene (Acy) and anthracene (Ant), the soil acted as second sources of them