"Add to Favorites" is a popular function in online shopping sites which helps users to make a record of potentially interesting items for future purchases. It is usually regarded as a type of explicit feedback signal for item popularity and therefore also adopted as a ranking signal by many shopping search engines. With the increasing usage of crowdsourcing platforms, some malicious online sellers also organize crowdturfing activities to increase the numbers of "Add to Favorites" for their items. By this means, they expect the items to gain higher positions in search ranking lists and therefore boost sales. This kind of newly-appeared malicious activity proposes challenges to traditional search spam detection efforts because it involves the participation of many crowd workers who are normal online shopping users in most of the times, and these activities are composed of a series of behaviors including search, browse, click and add to favorites. To shed light on this research question, we are among the first to investigate this particular spamming activity by looking into both the task organization information in crowdsourcing platforms and the user behavior information from online shopping sites. With a comprehensive analysis of some ground truth spamming activities from the perspective of behavior, user and item, we propose a factor graph based model to identify this kind of spamming activity. Experimental results based on data collected in practical shopping search environment show that our model helps detect malicious "Add to Favorites" activities effectively.

As online shopping becomes increasingly popular, users perform more product search to purchase items. Previous studies have investigated people's online shopping behaviours and ways to predict online purchases. However, from a user perspective, there still lacks an in-depth understanding of why users search, how they interact with, and perceive the product search results. In this paper, we conduct both a user study and a log analysis to we address the following three questions: (1) what are the intents of users underlying their search activities? (2) do users behave differently under different search intents? and (3) how does user perceived satisfaction relate to their search behaviour as well as search intents, and can we predict product search satisfaction with interaction signals? Based on an online survey and search logs collected from a major commercial product search engine, we show that user intents in product search fall into three categories: Target Finding (TF), Decision Making (DM) and Exploration (EP). Through a log analysis and a user study, we observe different user interaction patterns as well as perceived satisfaction under these three intents. Using a series of user interaction features, we demonstrate that we can effectively predict user satisfaction, especially for TF and DM intents.

With the rapid growth of mobile web search, it is necessary and important to understand user's examination behavior on mobile devices in the absence of clicks. Previous studies used viewport metrics to estimate user's attention. However, there still lacks an in-depth understanding of how search users examine and interact with the mobile SERP. In this work, based on the large-scale real search log collected from a popular commercial mobile search engine, we present a comprehensive analysis of examination behavior. Specifically, we analyze the position bias, the relationship with click behavior, and examination's change as the session continues. The findings shed new light on the understanding of user's examination behavior, and also provide some implication for the improvement and evaluation of mobile search engine.

Search users rely on result captions including titles, snippets and URLs to decide whether they should click a particular result.Snippets usually serve as a query-dependent summary of its corresponding landing page and are, therefore, one of the most important factors in the search interaction process.At present, commercial search engines use query bolding strategies, but these have various problems and lack useful information.This paper presents a bolding strategy that improves user search efficiency.The method includes three bolding strategies based on crowd sourcing results which differ from the query terms strategy.Tests show that the search behavior is affected by the term bolding strategies without changes in the snippet contents.The tests also show that the responses to the three bolding strategies are better than responses to the query terms bolding strategy to produce a better bolding strategy.The appropriate bolding numbers, bolding ratio, and targeted information have a very positive impact on the user's search behavior.

Electrodermal activity (EDA) delineates positive and negative emotions, especially in the lower arousal range, which reflects small variations. This study derived formulas to extract features from the EDA graph and found they are effective to predict search satisfaction and explain mobile shopping behaviors including add to cart, purchase , and abandonment (added to cart without purchase). The best features found in the generalized linear mixed model with the binomial family agree with known physiological results. To the best of our knowledge, this study is the first to use physiological methods to study satisfaction and user behavior.

This paper considers numerical solutions to magneto hydrodynamics convective heat transfer over a permeable stretching wedge with thermal radiation and ohmic heating. Both the viscosity and thermal conductivity are assumed to vary as a linear function of the temperature, and dynamic viscosity is considered in a new form. Using an appropriate transformation, the governing partial differential equations are transformed into ordinary differential equations. Numerical solutions to these equations subject to corresponding boundary conditions are obtained by efficient numerical shooting technique coupled with Runge–Kutta–Fehlberg scheme. The effects of pertinent parameters are shown through tables and graphs, and meanwhile the associated transfer characteristics are analyzed in detail. The results show that: with the increase of viscosity variation parameter or the thermal conductivity, the local skin-friction coefficient increases but the local Nusselt number decreases. The increasing in viscosity variation parameter is to increase the velocity boundary layer thickness and decrease in the magnitude of the velocity gradient. Furthermore, thermal conductivity parameter has the same effect on the thermal boundary layer thickness and the temperature gradient.

In this article, we consider the exterior problem for the nonlinear degenerate parabolic equationu(t) - Delta b(u) + del.Phi(u) = F(u), (t, x) epsilon (0,T) x Omega,Omega is the exterior domain of Omega(0) (a closed bounded domain in R-N with its boundary Gamma epsilon C-1,C-1), b is non-decreasing and Lipschitz continuous, Phi = (phi(1), ...,phi N) is vectorial continuous, and F is Lipschitz continuous. In the nonhomogeneous boundary condition where b(u) = b(a) on (0, T) x Gamma, we establish the comparison and uniqueness, the existence using penalized method.

In this paper, we present entropy satisfying schemes for solving an integro-differential equation that describes the evolution of a population structured with respect to a continuous trait. In [P.-E. Jabin and G. Raoul, J. Math. Biol., 63 (2011), pp. 493-517] solutions are shown to converge toward the so-called evolutionary stable distribution (ESD) as time becomes large, using the relative entropy. At the discrete level, the ESD is shown to be the solution to a quadratic programming problem and can be computed by any well-established nonlinear programing algorithm. The schemes are then shown to satisfy the entropy dissipation inequality on the set where initial data are positive and the numerical solutions tend toward the discrete ESD in time. An alternative algorithm is presented to capture the global ESD for nonnegative initial data, which is made possible due to the mutation mechanism built into the modified scheme. A series of numerical tests are given to confirm both accuracy and the entropy satisfying property and to underline the efficiency of capturing the large time asymptotic behavior of numerical solutions in various settings.

This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient.

In this work we study single balance law ut+∇⋅Φ(u)=f(u) with bounded initial value, and find that there may exist maximal and minimal solutions, if f(u) is not Lipschitz continuous at u=0. We also show that comparison principle is valid for such solutions, and the solutions may blow up or not under certain conditions. It is determined by the strength of source supply, as well as the competition between the source and flux.

We consider the nonlinear degenerate elliptic-parabolic-hyperbolic equationpartial derivative(t)g(u) - Delta b(u) - div Phi(u) = f(g(u)) in (0,T) x Omegawhere g and b are nondecreasing continuous functions, Phi is vectorial and continuous, and f is Lipschitz continuous. We prove the existence, comparison and uniqueness of entropy solutions for the associated initial-boundary-value problem where Omega is a bounded domain in R-N. For the associated initial-value problem where Omega = R-N, N >= 3, the existence of entropy solutions is proved. Moreover, for the case when Phi o g(-1) is locally Holder continuous of order 1 - 1/N, and vertical bar b(u)vertical bar <= omega(vertical bar g(u)vertical bar), where omega is nondecreasing continuous with omega(0) = 0, we can prove the L-1-contraction principle, and hence the uniqueness.

We consider an abstract Cauchy problem for a doubly nonlinear evolution equation of the form d/dt𝒜u+ℬu∋ft in V′, t∈0, T, where V is a real reflexive Banach space, 𝒜 and ℬ are maximal monotone operators (possibly multivalued) from V to its dual V′. In view of some practical applications, we assume that 𝒜 and ℬ are subdifferentials. By using the back difference approximation, existence is established, and our proof relies on the continuity of 𝒜 and the coerciveness of ℬ. As an application, we give the existence for a nonlinear degenerate parabolic equation.

This paper studies an initial-boundary value problem (IBV) of the wave equation, in which time derivative of second order appears in the boundary condition. This results in study of new Sturm–Liouville problem. The solution of IBV is then constructed in terms of the family of eigenfunctions of the S-L problem. Uniqueness and stability are proved via energy inequality method. Some extension is explained. A parabolic variant is also illustrated.

The void defect in solid insulation can be considered as one of the important defects which will induce partial discharges (PD) and insulation degradation. In this paper, the relations between the cylindrical void size and PD characteristics are presented and summarized particularly. The PD inceptive electrical field (PDIE), the maximal PD magnitude and the impulse waveforms are especially studied with different void defects' depths and diameters. These PD characteristics, especially for PD impulse waveforms, changed dramatically with the increase of void size, which imply the various ionization states in PD process. The results show that large size voids always induce low PDIE and large maximal PD magnitude, which confirm the certain relations between insulation degradation degree and PD characteristics. Some of the results show that the PD with more residual ions may cause much serious degradation of solid insulations. The floating electrode defect test has been designed as a proving trial lastly.

The formulation and existence theory is presented for a system modelingdiffusion of a slightly compressible fluid through a partially saturated poroelasticmedium. Nonlinear effects of density, saturation, porosity and permeabilityvariations with pressure are included, and the seepage surface is determined by avariational inequality on the boundary.

The time-dependent Ginzburg-Landau equations of superconductivity in three spatial dimensions are investigated in this paper. We establish the existence of global weak solutions for this model with any L p ( p ≧ 3) initial data. This work generalizes the results of Wang and Zhan.

The time-dependent Ginzburg-Landau equations of superconductivity in three spatial dimensions are investigated in this paper. We establish the existence of global weak solutions for this model with any Lp (p ≥ 3) initial data. This work generalizes the results in [1].