Online Ridesharing with Meeting Points [Technical Report]

Nowadays, ridesharing becomes a popular commuting mode. Dynamically arriving riders post their origins and destinations, then the platform assigns drivers to serve them. In ridesharing, different groups of riders can be served by one driver if their trips can share common routes. Recently, many ridesharing companies (e.g., Didi and Uber) further propose a new mode, namely "ridesharing with meeting points". Specifically, with a short walking distance but less payment, riders can be picked up and dropped off around their origins and destinations, respectively. In addition, meeting points enables more flexible routing for drivers, which can potentially improve the global profit of the system. In this paper, we first formally define the Meeting-Point-based Online Ridesharing Problem (MORP). We prove that MORP is NP-hard and there is no polynomial-time deterministic algorithm with a constant competitive ratio for it. We notice that a structure of vertex set, $k$-skip cover, fits well to the MORP. $k$-skip cover tends to find the vertices (meeting points) that are convenient for riders and drivers to come and go. With meeting points, MORP tends to serve more riders with these convenient vertices. Based on the idea, we introduce a convenience-based meeting point candidates selection algorithm. We further propose a hierarchical meeting-point oriented graph (HMPO graph), which ranks vertices for assignment effectiveness and constructs $k$-skip cover to accelerate the whole assignment process. Finally, we utilize the merits of $k$-skip cover points for ridesharing and propose a novel algorithm, namely SMDB, to solve MORP. Extensive experiments on real and synthetic datasets validate the effectiveness and efficiency of our algorithms.Comment: 18 page

EFFECTS OF ENZYME PRETREATMENT ON THE BEATABILITY OF FAST-GROWING POPLAR APMP PULP

Effects of enzyme pretreatment on the properties of fast-growing poplar APMP pulp were evaluated. Compared with the unpretreated pulp, the beatabilities of the pulp that had been pretreated by enzymes were improved significantly, such as a decrease of Canadian Standard Freeness (CSF) in the range of 25 mL to 55 mL, a decrease of PFI mill revolutions from 1000r to 5500r, and a decrease of beating energy consumption from 12.5% to 22.0%. The values of brightness, breaking length, tearing index, bursting index, and folding number of the pulp pretreated by cellulase were improved by 1.2%ISO, 23.7%, 14.8%, 14.6%, and 50% respectively, while that of the pulp pretreated by xylanase were respectively improved by 2.1%ISO, 16.8%, 8.8%, 8.9%, and 25%. The optimal enzyme dosages were 25 IU•g-1 and 25IU•g-1 for cellulase and xylanase, respectively. Fibre quality analysis results showed that the fibre length of pretreated pulp increased partly, fibre width and fines content decreased, fibres torsion increased, and fibre bonding got stronger. X-ray diffractometer analysis indicated that the degree of crystallinity of fibres increased after the enzyme pretreatment

The Sloan Digital Sky Survey Reverberation Mapping Project: Key Results

We present the final data from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project, a precursor to the SDSS-V Black Hole Mapper Reverberation Mapping program. This data set includes 11-year photometric and 7-year spectroscopic light curves for 849 broad-line quasars over a redshift range of 0.1<z<4.5 and a luminosity range of Lbol=1E44-47.5 erg/s, along with spectral and variability measurements. We report 23, 81, 125, and 110 reverberation mapping lags (relative to optical continuum variability) for broad Halpha, Hbeta, MgII and CIV using the SDSS-RM sample, spanning much of the luminosity and redshift ranges of the sample. Using 30 low-redshift RM AGNs with dynamical-modeling black hole masses, we derive a new estimate of the average virial factor of =0.62+-0.07 for the line dispersion measured from the RMS spectrum. The intrinsic scatter of individual virial factors is 0.31+-0.07 dex, indicating a factor of two systematic uncertainty in RM black hole masses. Our lag measurements reveal significant R-L relations for Hbeta and MgII at high redshift, consistent with the latest measurements based on heterogeneous samples. While we are unable to robustly constrain the slope of the R-L relation for CIV given the limited dynamical range in luminosity, we found substantially larger scatter in CIV lags at fixed L1350. Using the SDSS-RM lag sample, we derive improved single-epoch (SE) mass recipes for Hbeta, MgII and CIV, which are consistent with their respective RM masses as well as between the SE recipes from two different lines, over the luminosity range probed by our sample. The new Hbeta and MgII recipes are approximately unbiased estimators at given RM masses, but there are systematic biases in the CIV recipe. The intrinsic scatter of SE masses around RM masses is ~0.45 dex for Hbeta and MgII, increasing to ~0.58 dex for CIV.Comment: 33 pages. Data products available at ftp://quasar.astro.illinois.edu/public/sdssrm/final_result

Production of Flocculants, Adsorbents, and Dispersants from Lignin

Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed

Green Synthesis and Characterization of Gold Nanoparticles Using Lignin Nanoparticles

With the development of nanotechnology, gold nanoparticles (Au NPs) have attracted enormous attention due to their special properties. The green synthesis of Au NPs from lignin would inspire the utilization of lignin and its related functional materials. In this study, a rapid preparation process of Au NPs was investigated by utilizing lignin nanoparticles (LNPs) under room temperature without chemical addition. The LNPs acted as a reducing agent, stabilizing agent, and template for the preparation of LNPs@AuNPs. The obtained LNPs@AuNPs were characterized by UV-Vis spectrum, Transmission Electron Microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The possible mechanism was illustrated by Fourier Transform Infrared Spectroscopy (FT-IR), 31P, XPS, and UV analyses. The abundant hydroxyl groups (24.96 mmol/g) favored the preparation of Au NPs. Au NPs diameters of 10&ndash;30 nm were well dispersed in the LNPs. The optimal reaction conditions were a ratio of 10 mg of LNPs to 0.05 mmol HAuCl4, room temperature, and a reaction time of 30 min. The LNPs@AuNPs exhibited excellent stability in the suspension for more than seven days. The reduction process could be related to the disruption of side chains of lignin, hydroxyl group oxidation, and hydroquinones and quinones from the comproportionation reaction. The LNPs@AuNPs would open a door for the design of Au NP/lignin-derived novel functional materials

Sodium Hydrogen Sulfite Pretreatment of Wood Pulp Waste for Enhancement of Enzymatic Efficiency

Wood pulp waste is a type of industrial waste that has an enormous potential for fermentable sugar production. Efficient pretreatment is the key for enhancing the enzymatic efficiency. In this paper, sodium hydrogen sulfite pretreatment was performed on wood pulp waste to improve enzyme performance through sulfonation and hydrolysis reactions. Results showed that the enzymatic efficiency was greatly enhanced from 5.12 to 41.6% in terms of reducing sugar yield (RSY) under the optimum conditions: 6% NaHSO3, 2500 P-factor, 3/1 liquid to solid ratio, and cellulase charge of 35 FPU/g substrate. Mass balance showed that approximately 73% of glucose was recovered. The mechanism of sulfonation and hydrolysis of sodium hydrogen sulfite pretreatment were confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (X-RD), and scanning electron microscopy (SEM)

Effect of Cellulase and Protease Pretreatment on Dewaterability of Waste Activated Sludge from Paper Mill

The feasibility of cellulase and protease pretreatment to improve the dewaterability of waste activated sludge from papermaking (WASP) was evaluated. Dewatering properties such as capillary suction time (CST), dry solids content of the sludge cakes from the specific resistance of filtration (SRF), and compression were measured to quantify the effects of cellulase and protease in sludge dewatering. The changes in the amounts of proteins (PN) and polysaccharides (PS) in tightly bound extracellular polymeric substances (TB-EPS) was found to be the most important parameter with respect to sludge dewatering. Further study, through nitrogen adsorption, verified the large change in the average pore width and surface area. Therefore, the disruption of TB-EPS and the change in the inner structure of WASP granules are the fundamental reasons for the enhanced dewaterability

Characterization and Hydrothermal Conversion of Lignin Produced from Corncob Acid Hydrolysis Residue

Lignin is one of the main components of corncob acid hydrolysis residue (CAHR). It can be used as a feedstock for biomaterial and biochemical production via biorefining. In this study, CAHR lignin was extracted, and enzymatic/mild acidolysis lignin (EMAL) was produced to ensure efficient lignin recovery. Next, hydrothermal conversion of the EMAL was carried out. The influences of process conditions including the temperature, time, and mass ratio of deionized water to EMAL on the hydrothermal conversion were thoroughly investigated to quantify analysis of the aromatics. EMAL produced from CAHR had a structure of the G-S-H type, in which the p-hydroxyphenyl unit was the primary structural unit, followed by the guaiacyl structural unit. The syringyl structural unit was less common. The yields (wt. %) of phenol, guaiacol, and 4-ethyl-phenol reached maxima of 1.26%, 0.75%, and 1.16%, respectively, at a reaction temperature of 310 °C and time of 30 min with a mass ratio of 80:1