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Closed-Form Models of Accuracy Loss due to Subsampling in SVD Collaborative Filtering

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Big Data Mining and Analytics 2023年第1期6卷 72-84页

作者： Samin poudel Marwan Bikdash Department of Computational Data Science and Engineering North Carolina A&T State UniversityGreensboroNC 27401USA

We postulate and analyze a nonlinear subsampling accuracy loss(SSAL)model based on the root mean square error(RMSE)and two SSAL models based on the mean square error(MSE),suggested by extensive preliminary *** SSAL models predict accuracy loss in terms of subsampling parameters like the fraction of users dropped(FUD)and the fraction of items dropped(FID).We seek to investigate whether the models depend on the characteristics of the dataset in a constant way across datasets when using the SVD collaborative filtering(CF)*** dataset characteristics considered include various densities of the rating matrix and the numbers of users and *** simulations and rigorous regression analysis led to empirical symmetrical SSAL models in terms of FID and FUD whose coefficients depend only on the data *** SSAL models came out to be multi-linear in terms of odds ratios of dropping a user(or an item)*** dropping ***,one MSE deterioration model turned out to be linear in the FID and FUD odds where their interaction term has a zero *** importantly,the models are constant in the sense that they are written in closed-form using the considered data characteristics(densities and numbers of users and items).The models are validated through extensive simulations based on 850 synthetically generated primary(pre-subsampling)matrices derived from the 25M MovieLens *** 460000 subsampled rating matrices were then simulated and subjected to the singular value decomposition(SVD)CF *** validation was conducted using the 1M MovieLens and the Yahoo!Music Rating *** models were constant and significant across all 3 datasets.

关键词： collaborative filtering subsampling accuracy loss models performance loss recommendation system simulation rating matrix root mean square error

Synthesis of high-performance nickel hydroxide nanosheets/gadolinium doped-α-MnO_(2) composite nanorods as cathode and Fe_(3)O_(4)/GO nanospheres as anode for an all-solid-state asymmetric supercapacitor

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Journal of Energy Chemistry 2022年第1期31卷 475-484,I0013页

作者： Milan Babu poudel Han Joo Kim Department of Convergence Engineering Technology Jeonbuk National UniversityJeonju Jeollabuk-do 54896Republic of Korea

The wide use of manganese dioxide(MnO_(2))as an electrode in all-solid-state asymmetric supercapacitors(ASCs)remains challenging because of its low electrical *** complication can be circumvented by introducing trivalent gadolinium(Gd)ions into the MnO_(2).Herein,we describe the successful hydrothermal synthesis of crystalline Gd-doped MnO_(2) nanorods with Ni(OH)_(2) nanosheets as cathode,which we combined with Fe_(3)O_(4)/GO nanospheres as anode for all-solid-state *** tests dem on strate that Gd dopi ng sign ifica ntly affected the electrochemical activities of the MnO_(2),which was further enhanced by introducing Ni(OH)_(2).The GdMnO_(2)/Ni(OH)_(2) electrode offers sufficient surface electrochemical activity and exhibits excellent specific capacity of 121.8 mA h g^(-1),at 1A g^(-1),appealing rate performance,and ultralong lifetime stability(99.3%retention after 10,000 discharge tests).Furthermore,the GdMnO_(2)/Ni(OH)_(2)//PVA/KOH//Fe_(3)O_(4)/GO solid-state ASC device offers an impressive specific energy density(60.25 W h kg^(-1))at a high power density(2332 W kg^(-1)).This investigation thus shows its large potential in developing novel approaches to energy storage devices.

关键词： Solid-state supercapacitor Manganese dioxide Gadolinium doping Nickel hydroxide nanosheets

Adsorption kinetics of the herbicide safeners,benoxacor and furilazole,to activated carbon and agricultural soils

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Journal of Environmental Sciences 2020年第3期32卷 23-34页

作者： Saraswati poudel Acharya Jacob Johnson Jennifer Weidhaas Civil and Environmental Engineering University of UtahSalt Lake CityUTUSA Center for Science and Mathematics Education University of Utah155 South 1452 EastSalt Lake CityUT 84112USA

Chloroacetamide herbicides,namely acetochlor and metolachlor,are common herbicides used on corn and soybean *** safeners,namely benoxacor and furilazole,are commonly used in formulations containing chloroacetamide *** reports on adsorption of chloroacetamide herbicides are available,yet little information exists regarding adsorption potential of co-applied ***,the adsorption and desorption characteristics of selected herbicide safeners to granular activated carbon(GAC) and in agricultural soils are ***,soil column studies were performed to understand the leaching behaviour of the herbicide Dual II *** sorption experiments of safeners to three agricultural soils and one GAC showed that adsorption was best fitted by the Freundlich *** Freundlich adsorption constant,Kf,for benoxacor and furilazole sorption onto three agricultural soils ranged from0.1 to 0.27 and 0.1 to 0.13(mg/g) x(mg/L)(1/n),*** Kf for benoxacor and furilazole to GAC was 6.4 and 3.4(mg/g) x(mg/L)(1/n),respectively,suggesting more favorable sorption of benoxacor to GAC than furilazole to *** sorption to soils was reversible as almost 40%-90% of both safeners was desorbed from three *** results were validated in four replicated soil column studies,where S-metolachlor was shown to leach similarly to the safener benoxacor,originating from the herbicide *** leaching of S-metolachlor and benoxacor was influenced by soil ***,these results show that safeners will move through the environment to surface waters similarly to the active ingredients in herbicides,but may be removed during drinking water treatment via GAC.

关键词： Herbicide safener Dual Ⅱ magnum Adsorption Granular activated carbon Soil column transport

Optimal Dependence of Performance and Efficiency of Collaborative Filtering on Random Stratified Subsampling

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Big Data Mining and Analytics 2022年第3期5卷 192-205页

作者： Samin poudel Marwan Bikdash Department of Computational Data Science and Engineering North Carolina A&T State UniversityGreensboroNC 27401USA

Dropping fractions of users or items judiciously can reduce the computational cost of Collaborative Filtering(CF)*** effect of this subsampling on the computing time and accuracy of CF is not fully understood,and clear guidelines for selecting optimal or even appropriate subsampling levels are not *** this paper,we present a Density-based Random Stratified Subsampling using Clustering(DRSC)algorithm in which the desired Fraction of Users Dropped(FUD)and Fraction of Items Dropped(FID)are specified,and the overall density during subsampling is ***,we develop simple models of the Training Time Improvement(TTI)and the Accuracy Loss(AL)as functions of FUD and FID,based on extensive simulations of seven standard CF algorithms as applied to various primary matrices from MovieLens,Yahoo Music Rating,and Amazon Automotive *** show that both TTI and a scaled AL are bi-linear in FID and FUD for all seven *** TTI linear regression of a CF method appears to be same for all *** simulations illustrate that TTI can be estimated reliably with FUD and FID only,but AL requires considering additional dataset *** derived models are then used to optimize the levels of subsampling addressing the tradeoff between TTI and AL.A simple sub-optimal approximation was found,in which the optimal AL is proportional to the optimal Training Time Reduction Factor(TTRF)for higher values of TTRF,and the optimal subsampling levels,like optimal FID/(1-FID),are proportional to the square root of TTRF.

关键词： Collaborative Filtering(CF) subsampling Training Time Improvement(TTI) performance loss Recommendation System(RS) collaborative filtering optimal solutions rating matrix

Evaluation of sampling strategies to estimate crown biomass

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Forest Ecosystems 2015年第1期2卷 20-30页

作者： Krishna P poudel Hailemariam Temesgen Andrew N Gray Department of Forest Engineering Resources and Management College of Forestry Oregon State University USDA Forest Service PNW Research Station3200 SW Jefferson WayCorvallis OR 97331 USA

Background：Depending on tree and site characteristics crown biomass accounts for a significant portion of the total aboveground biomass in the *** biomass estimation is useful for different purposes including evaluating the economic feasibility of crown utilization for energy production or forest products,fuel load assessments and fire management strategies,and wildfire ***,crown biomass is difficult to predict because of the variability within and among species and *** the allometric equations used for predicting crown biomass should be based on data collected with precise and unbiased sampling *** this study,we evaluate the performance different sampling strategies to estimate crown biomass and to evaluate the effect of sample size in estimating crown ***：Using data collected from 20 destructively sampled trees,we evaluated 11 different sampling strategies using six evaluation statistics：bias,relative bias,root mean square error（RMSE）,relative RMSE,amount of biomass sampled,and relative biomass *** also evaluated the performance of the selected sampling strategies when different numbers of branches（3,6,9,and 12）are selected from each *** specific log linear model with branch diameter and branch length as covariates was used to obtain individual branch ***：Compared to all other methods stratified sampling with probability proportional to size estimation technique produced better results when three or six branches per tree were ***,the systematic sampling with ratio estimation technique was the best when at least nine branches per tree were *** the stratified sampling strategy,selecting unequal number of branches per stratum produced approximately similar results to simple random sampling,but it further decreased RMSE when information on branch diameter is used in the design and estimation ***：Use of auxiliary information in design or estimation phase reduc

关键词： Aboveground biomass Crown Sampling strategies Pacific Northwest

Investigating the effects of peptide-based,MOS and protease feed additives on the growth performance and fecal microbial composition of weaned pigs

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Journal of Animal Science and Biotechnology 2022年第5期13卷 1469-1482页

作者： Prakash poudel Ryan Samuel Crystal Levesque Benoit St-Pierre Himalayan Pet Foods MukilteoWashington 98275USA Department of Animal Science South Dakota State UniversityAnimal Science ComplexBox 2170BrookingsSD 57007USA

Background:Digestive disorders in weaning pigs remain a major challenge for swine *** types of commercial feed additives have been developed to promote gut health and development in young pigs,but their effects on resident gut microbial communities remain largely *** aim of this study was to investigate the impact of a peptide-based product(Peptiva)in combination with mannose oligosaccharides(MOS)and an exogenous protease on the performance and fecal microbiome of nursery ***:A total of 1097 weaned pigs were divided into 44 pens(24-26 pigs/pen)with each pen randomly assigned to one of four experimental diets as part of Phase Ⅱ and Phase Ⅲ of a standard nursery phase feeding *** samples collected from representative control and treatment pigs were used to investigate bacterial composition profiles by high throughput sequencing of PCR-generated amplicons targeting the V1-V3 region of the 16S rRNA ***:Higher gain:feed was observed for pigs fed Peptiva and MOS compared to Controls during the period when experimental diets were fed,but the benefits of supplementation were not maintained after pigs were transitioned to a non-supplemented *** candidate bacterial species,identified as Operational Taxonomic Units(OTUs),were found to have significantly different abundances between control samples and treatment samples during the same *** Phase Ⅲ samples,SD_Ssd-00039,predicted to be a strain of Streptococcus alactolyticus based on nucleotide sequence identity,was the most highly represented of these OTUs with an average abundance in pigs fed Peptiva,MOS and protease that was 3.9 times higher than in *** report also presents evidence of microbial succession that occurred during the trial,with 16 of the 32 most abundant OTUs found to vary between Phase Ⅱ and Phase Ⅲ samples for the same dietary ***:Dietary supplementation with a combination of a peptide-based product,MOS,and protease in

关键词： Bacteria Gut Microbiome MOS Peptide Protease Swine Weaning

Tribological properties of Al-GNP composites at elevated temperature

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Friction 2024年第5期12卷 1028-1041页

作者： Sunil poudel Rizwan BAJWA Yongde XIA Zakir KHAN Yi ZHANG Yanqiu ZHU College of Engineering Mathematics and Physical SciencesUniversity of ExeterExeterEX44QFUK European Technical Centre Daido Metal Co.Ltd.Iliminster SomersetTA199PHUK

Lighter and more powerful next generation vehicles and other rotary machinery demand bearings to operate in harsher conditions for higher efficiency,and the continuous development of advanced low-wear and friction materials is thus becoming even more important to meet these *** aluminium composites reinforced with high performance lubricate phases such as graphene nanoplatelets(GNPs)are very promising and have been vigorously *** maintaining a low coefficient of friction(COF)and offering great strength against wear due to their self-lubricating capability,the solid lubricant like GNPs protect the bearing surface from wear damage and prevent change in metallurgical properties during temperature *** paper first studies the high-temperature tribological performance of aluminium matrix composites reinforced with GNP,consolidated via powder metallurgy,then elucidates their tribological *** report that the best tribological performance is achieved by the composite containing 2.0 wt%GNP,with an extraordinarily low COF of 0.09 and a specific wear rate of 3.5×10^(−2)mm^(3)·N^(−1)·m^(−1),which represent 75%and 40%reduction respectively,against the plain aluminium consolidated under identical *** in-track and out-of-track Raman analysis have confirmed the role of GNPs in creating a tribofilm on the counterpart surface which contributed to the excellent performance.

关键词： nanocomposite graphene nanoplatelet(GNP) tribology powder metallurgy

Estimating upper stem diameters and volume of Douglas-fir and Western hemlock trees in the Pacific northwest

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Forest Ecosystems 2018年第3期5卷 199-210页

作者： Krishna P.poudel Hailemariam Temesgen Andrew N.Gray Department of Forest Engineering Resources and Management College of Forestry Oregon State University USDA Forest Service PNW Research Station

Background: Volume and taper equations are essential for obtaining estimates of total and merchantable stem volume. Taper functions provide advantages to merchantable volume equations because they estimate diameter inside or outside bark at specific heights on the stem, enabling the estimation of total and merchantable stem volume, volume of individual logs, and a height at a given ***: Using data collected from 1218 trees(1093 Douglas-fir(Pseudotsuga menziesii(Mirbel) Franco) and 125 western hemlock(Tsuga heterophylla)), we evaluated the performance of one simple polynomial function and four variable-exponent taper functions in predicting upper stem diameter. Sample trees were collected from different parts of the states of Oregon, Washington, and California. We compared inside-bark volume estimates obtained from the selected taper equation with estimates obtained from a simple logarithmic volume equation for the data obtained in this study and the equations used by the Forest Inventory and Analysis program in the Pacific Northwest(FIA-PNW) in the state of California and western half of the states of Oregon and ***: Variable exponent taper equations were generally better than the simple polynomial taper *** FIA-PNW volume equations performed fairly well but volume equations with fewer parameters fitted in this study provided comparable results. The RMSE obtained from taper-based volume estimates were also comparable with the RMSE of the FIA-PNW volume equations for Douglas-fir and western hemlock trees ***: The taper equations fitted in this study provide added benefit to the users over the FIA-PNW volume equations by enabling the users to predict diameter at any height, height to a given diameter, and merchantable volume in addition to cubic volume including top and stump(CVTS) of Douglas-fir and western hemlock trees in the Pacific Northwest. The findings of this study also give more confidence to the use

关键词： Pacific northwest Biomass equations Utilization standards Diameter inside bark

Enhancement of MTBE Biodegradation by Fe3O4 Magnetic Particles

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Enhancement of MTBE Biodegradation by Fe3O4 Magnetic Particl...

作者： Rabin poudel 浙江工业大学

学位级别：硕士

Magnetic particles（MPs）have been rapidly applied to bioremediation of environmental *** the promising performance,magnetic particles are getting attention to enhancing biodegradation activity to treat the volatile organic compounds（VOCs）from contaminated *** reusability,reactivity,and biocompatibility properties of the magnetic particles reduce the current environmental *** particles（MPs）can enhance the biodegradation of the methyl tert-butyl ether（MTBE）in the batch *** effect of Fe

关键词： Volatile organic compound biodegradation methyl tert-butyl ether magnetic nanoparticles enhancement