One of the main benefits of unsupervised learning is that there is no need for labelled data. As a method of this category, latent Dirichlet allocation (LDA) estimates the semantic relations between the words of the text effectively and can play an important role in solving various issues, including emotional analysis in combination with other parameters. In this study, three novel topic models called date sentiment LDA (DSLDA), author–date sentiment LDA (ADSLDA), and pack–author–date sentiment LDA (PADSLDA) are proposed. The proposed models extend LDA through some extra parameters such as date, author, helpfulness, sentiment, and subtopic. The proposed models use helpfulness in the Gibbs sampling algorithm. Helpfulness is a part of readers who found the review helpful. The proposed models divide the words into two categories: the words more affected by the distribution of subtopic and the words more affected by the main topic. In this study, a new concept called pack is introduced, and a new model called PADSLDA is proposed for sentiment analysis at pack level. The proposed models outperformed the baseline models because according to evaluations results, the extra parameters can appropriately affect the generating process of words in a review. Sentiment analysis at the document level, perplexity, and topic coherence are the main parameters used in the evaluations. 相似文献
The objective of this article is to study the physics of slip effect at the boundary of a vertical plate in starting the flow of Casson fluid with the combined effect of radiative heat and mass transfer in the presence of first-order chemical reaction. The problem has been modeled in terms of partial differential equations along with appropriate initial and boundary conditions. The dimensionless governing equations have been solved by means of the Laplace transform technique. Exact solutions have been obtained for velocity, temperature and concentration profiles. The obtained velocity has been computed in tabular form for steady and transient velocities. The physics of velocity profile has been studied for various physical parameters through numerical computation and displayed in graphs. From obtained solutions, the well-known published results in the open literature have been recovered and displayed in graphs and tables.
Estimation of seismic vulnerability of existing equipment in petroleum complexes, traditionally has been done by using general fragility curves which have been developed for a group of equipment without considering their physical specifications. Although these kinds of fragility are suitable for preparing emergency plans and governmental decision making, for the sake of seismic upgrading of existing facilities, specific equipment fragilities are needed. In this paper un-anchored steel storage tanks, which is among the most vulnerable equipment in petroleum facilities, are selected for a case study. Probabilistic demand models for Elephant Foot Buckling (EFB) and welding failure at the connection between the bottom plate and shell are developed based on FEM analytical data, and a Bayesian updating rule is used to assess the unknown demand model parameters. The approach properly accounts for both aleatory and epistemic uncertainties. Developed probabilistic demand models are used to estimate the fragility of critical failure modes of selected tanks and real world data. The approach can be applied for other failure modes and other equipment, as well. 相似文献
In order to determine the amount of caffeine and theobromine, spectrophotometry was used as a simple, rapid and economical method. Because of severe overlapping between these components, artificial neural network was used. The 230–300 nm spectral window with 1 nm interval was used for data acquisition. An artificial neural network (5-5-3) with linear transfer function between input-hidden and hidden-output layers was trained and applied for prediction of concentration of these methylxanthines in four Iranian tea samples. The model was compared with PLS modeling method. HPLC technique was used as a standard method. 相似文献
Besides a stable phase, shape-memory polymers require an additional switchable moiety. In addition to thermal transitions and supramolecular interactions, these units can also be based on covalent bonds. Herein, the use of the reversible thiol-ene reaction as reversible cross-linker for the design of shape-memory polymers is demonstrated. A facile route to polymer networks with a thiol-ene acceptor and a comonomer (butyl methacrylate or 2-ethylhexyl methacrylate) cross-linked by dithiols is introduced. The thermal and mechanical properties of the resulting polymers are characterized in detail. Hereby, the polymers feature excellent shape-memory behavior with fixity and recovery rates above 90%. This study shows that the thiol-ene cross-linker can function as both, the stable and the switchable structural moiety rendering the usage of a covalent cross-linker unnecessary. This partial reversibility can also be proven by temperature-depending Raman spectroscopy. 相似文献
The performance of three solid oxide fuel cell (SOFC) systems, fuelled by biogas produced through anaerobic digestion (AD) process, for heat and electricity generation in wastewater treatment plants (WWTPs) is studied. Each system has a different fuel processing method to prevent carbon deposition over the anode catalyst under biogas fuelling. Anode gas recirculation (AGR), steam reforming (SR), and partial oxidation (POX) are the methods employed in systems I-III, respectively. A planar SOFC stack used in these systems is based on the anode-supported cells with Ni-YSZ anode, YSZ electrolyte and YSZ-LSM cathode, operated at 800 °C. A computer code has been developed for the simulation of the planar SOFC in cell, stack and system levels and applied for the performance prediction of the SOFC systems. The key operational parameters affecting the performance of the SOFC systems are identified. The effect of these parameters on the electrical and CHP efficiencies, the generated electricity and heat, the total exergy destruction, and the number of cells in SOFC stack of the systems are studied. The results show that among the SOFC systems investigated in this study, the AGR and SR fuel processor-based systems with electrical efficiency of 45.1% and 43%, respectively, are suitable to be applied in WWTPs. If the entire biogas produced in a WWTP is used in the AGR or SR fuel processor-based SOFC system, the electricity and heat required to operate the WWTP can be completely self-supplied and the extra electricity generated can be sold to the electrical grid. 相似文献
Hashimoto thyroiditis (HT) is a common autoimmune disorder with a strong genetic background. Several genetic factors have been suggested, yet numerous genetic contributors remain to be fully understood in HT pathogenesis. MicroRNAs (miRs) are gene expression regulators critically involved in biological processes, of which polymorphisms can alter their function, leading to pathologic conditions, including autoimmune diseases. We examined whether miR-499 rs3746444 polymorphism is associated with susceptibility to HT in an Iranian subpopulation. Furthermore, we investigated the potential interacting regulatory network of the miR-499. This case-control study included 150 HT patients and 152 healthy subjects. Genotyping of rs3746444 was performed by the PCR-RFLP method. Also, target genomic sites of the polymorphism were predicted using bioinformatics. Our results showed that miR-499 rs3746444 was positively associated with HT risk in heterozygous (OR = 3.32, 95%CI = 2.00–5.53, p < 0.001, CT vs. TT), homozygous (OR = 2.81, 95%CI = 1.30–6.10, p = 0.014, CC vs. TT), dominant (OR = 3.22, 95%CI = 1.97–5.25, p < 0.001, CT + CC vs. TT), overdominant (OR = 2.57, 95%CI = 1.62–4.09, p < 0.001, CC + TT vs. CT), and allelic (OR = 1.92, 95%CI = 1.37–2.69, p < 0.001, C vs. T) models. Mapping predicted target genes of miR-499 on tissue-specific-, co-expression-, and miR-TF networks indicated that main hub-driver nodes are implicated in regulating immune system functions, including immunorecognition and complement activity. We demonstrated that miR-499 rs3746444 is linked to HT susceptibility in our population. However, predicted regulatory networks revealed that this polymorphism is contributing to the regulation of immune system pathways. 相似文献
A thermodynamic model is developed to determine the fuels that would yield an identical maximum cell voltage (MCV) for solid oxide fuel cells (SOFCs) at a given operating condition. These fuels make a continuous curve in the ternary coordinate system. A fuel map is established by developing the continuous fuel curves for different MCVs at the same operating condition and representing them in the carbon-hydrogen-oxygen (C-H-O) ternary diagram. Using the fuel map, the effect of the composition of a fuel containing carbon, hydrogen, oxygen, and inert gas atoms on the MCV of SOFCs can be easily studied. In addition to the effect of the fuel composition, the graphical representation of fuel maps can be applied to study the effect of the fuel processors on the MCV of SOFCs. As a general result, among fuels that can be directly utilized in SOFCs, at the same temperature and pressure, the one located at the intersection of the H-C axis and the carbon deposition boundary (CDB) curve in the C-H-O ternary diagram, provides the highest MCV for SOFCs. The results also show that for the fuels that cannot be directly utilized in SOFC, the steam reforming fuel processor always yields a higher MCV than the autothermal reforming or the partial oxidation fuel processors at the same inlet fuel temperature. 相似文献