Using function approximation for personalized point-of-interest recommendation

Point-of-interest (POI) recommender system encourages users to share their locations and social experience through check-ins in online location-based social networks. A most recent algorithm for POI recommendation takes into account both the location relevance and diversity. The relevance measures users’ personal preference while the diversity considers location categories. There exists a dilemma of weighting these two factors in the recommendation. The location diversity is weighted more when a user is new to a city and expects to explore the city in the new visit. In this paper, we propose a method to automatically adjust the weights according to user’s personal preference. We focus on investigating a function between the number of location categories and a weight value for each user, where the Chebyshev polynomial approximation method using binary values is applied. We further improve the approximation by exploring similar behavior of users within a location category. We conduct experiments on five real-world datasets, and show that the new approach can make a good balance of weighting the two factors therefore providing better recommendation

A Connected Components Based Layout Analysis Approach for Educational Documents

Layout analysis, which aims to detect and categorize areas of interest on document images, is an increasingly important part in document image processing. Existing researches have conducted layout analysis on various documents, but none has been proposed for documents yielded from teaching, i.e. exam papers and workbooks, which are worth studying. In this paper, we propose a novel layout analysis system to achieve two tasks for workbook pages and exam papers respectively. On one hand, we segment text and non-text areas of workbook pages. On the other hand, we extract regions of interest on exam papers. Our system is based on connected component (CC) analysis, specifically, it extracts geometric features and spatial information of CCs to recognize page elements. We carried out experiments on images collected from real-world scenarios, and promising results confirmed the applicability and effectiveness of our system

Efficient Er/O‐Doped Silicon Light‐Emitting Diodes at Communication Wavelength by Deep Cooling

A silicon light source at the communication wavelength is the bottleneck for developing monolithically integrated silicon photonics. Doping silicon with erbium and oxygen ions is considered one of the most promising approaches to produce silicon light sources. However, this method suffers from a high concentration of defects in the form of nonradiative recombination centers at the interface between the crystalline silicon and large Er2O3/ErSi1.7 precipitates during the standard rapid thermal treatment. Here, a deep cooling process is applied to suppress the growth of these precipitates by flushing the high‐temperature Er/O‐doped silicon substrates with helium gas cooled in liquid nitrogen. The resultant light‐emitting efficiency at room temperature is enhanced by two orders of magnitude in comparison with that of the sample treated via standard rapid thermal annealing. The deep‐cooling‐processed Si samples are further processed into light‐emitting diodes. Bright electroluminescence with a main spectral peak at 1536 nm is also observed from the silicon‐based diodes with the external quantum efficiency reaching ≈0.8% at room temperature. Based on these results, the development of electrically driven silicon optical amplifiers or even lasers at communication wavelengths is promising for monolithically integrated silicon photonics.A deep cooling technique is developed for silicon light sources by suppressing the growth of Er/O‐related precipitates. The resultant near‐infrared emission shows efficiency enhancement by two orders of magnitude. Bright electroluminescence with a main spectral peak at 1536 nm is also observed. The external quantum efficiency can reach 0.8% at room temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162702/3/adom202000720.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162702/2/adom202000720-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162702/1/adom202000720_am.pd

Enhanced nucleation and precipitation hardening in Al-Mg-Si(-Cu) alloys with minor Cd additions

This work reports a novel effect of impurity element Cd on enhancing the precipitation kinetics and increasing the peak hardness of Al–Mg–Si(–Cu) alloys during artificial ageing. It is found that the number density of age hardening Mg–Si(–Cu) precipitates is greatly increased by Cd addition (~0.06 at.%) at both the under-aged and peak-aged stages. A systematic study on the precipitation behaviour by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) shows that most Mg–Si(–Cu) precipitates in the Cd-containing Al–Mg–Si alloys are associated with Cd-rich precipitates and have highly disordered structures. It is also found that the formation of Q'/C-like sub-units in Mg–Si(–Cu) precipitates is significantly promoted by Cd additions. To explore the nucleation mechanism under the influence of Cd addition, atom probe tomography (APT) is applied to study the solute clustering behaviour in the early stages of artificial ageing, and density functional theory (DFT) calculations are used to evaluate the binding energies of different solute-vacancy complexes and therefore the formation kinetics of Mg–Si–Cd clusters.acceptedVersio

An Explanation of the Underlying Mechanisms for the In Vitro and In Vivo Antiurolithic Activity of Glechoma longituba

Purpose. To use in vitro and in vivo models to evaluate Glechoma longituba extract to provide scientific evidence for this extract’s antiurolithic activity. Materials and Methods. Potassium citrate was used as a positive control group. Oxidative stress (OS) markers and the expression of osteopontin (OPN) and kidney injury molecule-1 (KIM-1) were measured to assess the protective effects of Glechoma longituba. Multiple urolithiasis-related biochemical parameters were evaluated in urine and serum. Kidneys were harvested for histological examination and the assessment of crystal deposits. Results. In vitro and in vivo experiments demonstrated that treatment with Glechoma longituba extract significantly decreased calcium oxalate- (CaOx-) induced OPN expression, KIM-1 expression, and OS compared with the positive control group (P<0.05). Additionally, in vivo rats that received Glechoma longituba extract exhibited significantly decreased CaOx deposits and pathological alterations (P<0.05) compared with urolithic rats. Significantly lower levels of oxalate, creatinine, and urea and increased citrate levels were observed among rats that received Glechoma longituba (P<0.05) compared with urolithic rats. Conclusion. Glechoma longituba has antiurolithic effects due to its possible combined effects of increasing antioxidant levels, decreasing urinary stone-forming constituents and urolithiasis-related protein expression, and elevating urinary citrate levels

Formation of Σ3{110} incoherent twin boundaries through geometrically necessary boundaries in an Al-8Zn alloy subjected to one pass of equal channel angular pressing

For coarse grained (CG) alloys with high stacking fault energies (SFEs), like aluminum, deformation twins can rarely form. Here, we report that Σ3{110} incoherent twin boundaries (ITBs) could be generated in a CG Al-8Zn alloy by one pass of ECAP. A systematic investigation shows that the Σ3{110} ITBs are formed by gradual evolution from geometrically necessary boundaries (GNBs) delineating deformation bands (DBs) by lattice rotation via -twist CSL boundaries. This is a new deformation mechanism in Al alloys, which has never been reported

Self-propagating high-temperature synthesis of nano-TiC<it>_x</it>particles with different shapes by using carbon nano-tube as C source

<p>Abstract</p> <p>With using the carbon nano-tube (CNT) of high chemical activity, nano-TiC<it>_x</it>particles with different growth shapes were synthesized through the self-propagating high temperature in the 80 wt.% metal (Cu, Al, and Fe)-Ti-CNT systems. The growth shapes of the TiC<it>_x</it>particles are mainly octahedron in the Cu- and Al-Ti-CNT systems, while mainly cube- and sphere-like in the Fe-Ti-CNT system.</p

Atom Probe Tomography Analysis of TiCx Powders Synthesized by SHS in Al/Fe/Cu–Ti–C Systems

The stoichiometry of titanium carbide (TiCx) particles is important in determining particle properties. Spherical TiCx powders with particle sizes of 1&ndash;5 &mu;m were produced by self-propagating high-temperature synthesis (SHS) in 30 wt.% Al&ndash;, 30 wt.% Cu&ndash;, and 30 wt.% Fe&ndash;Ti&ndash;C systems, respectively. To measure the compositions of the carbide powders, atom probe tomography (APT) tip specimens were carefully prepared by using a focus ion-beam milling method. APT analysis revealed that the TiCx particles formed in Al&ndash;, Cu&ndash;, and Fe&ndash;Ti&ndash;C systems are highly substoichiometric. The results are consistent with observations of the TiCx particles with a high content of oxygen and a certain amount of secondary metallic elements (Al, Cu, and Fe)

Formation of {11-21} twin boundaries in titanium by kinking mechanism through accumulative dislocation slip

The twinning behavior and kinking behavior of a commercial purity Ti subjected to room temperature dynamic plastic deformation (DPD) has been studied. Three types of deformation twins, {1012}, {1122} and {1121}, have been observed. It is found that a considerable fraction of the {1121} twin crystals were encompassed by the twin boundary segments in connection with kink band boundaries with much lower misorientation angles. A close investigation on the crystallographic nature of these deformation twins revealed that the {1121} twin boundaries have evolved from deformation kink band boundaries through accumulative slip of single basal-⟨a⟩ dislocations. This mechanism for the formation of twin boundaries is different from the known mechanisms through deformation twinning in metals, for which the twin orientation relationship has been achieved once the twin embryo is nucleated. The mechanism for the formation of kink band, the transformation from kink band boundary to deformation twin boundary and the further evolution of twin boundaries during DPD have been discussed in terms of Schmid factors of various dislocation slip systems

Deformation of an Al-7Mg alloy with extensive structural micro-segregations during dynamic plastic deformation

The microstructure evolution and deformation behavior of an as-cast Al–7Mg alloy with severe Mg segregation zones distributed on grain boundaries and in interdendrite regions subjected to dynamic plastic deformation (DPD) at both room and liquid nitrogen temperatures have been studied. At low strains, the deformation of the material is found to be mainly through the formation of deformation bands. At high strains, globular ultrafine grains form in the materials due to continuous dynamic recrystallization, which is also the dominant grain refinement mechanism. After deformation to strain of 1.0, the Mg segregation zones are deformed into fine parallel bands distributing along the deformation bands. Moreover, it is revealed that Al8Mg5 particles and the Mg segregation can enhance the formation of deformation bands even in grains with a stable orientation, namely those with one of the {101} planes perpendicular to the compression direction, which can reduce the inhomogeneity of the deformation structure