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This paper aims to improve the recommendations performance for cold-start users and controversial items. Collaborative filtering (CF) generates recommendations on the basis of similarity between users. It uses the opinions of similar users to generate the recommendation for an active user. As a similarity model or a neighbor selection function is the key element for effectiveness of CF, many variations of CF are proposed. However, these methods are not very effective, especially for users who provide few ratings (i.e. cold-start users).

A new user similarity model is proposed that focuses on improving recommendations performance for cold-start users and controversial items. To show the validity of the authors’ similarity model, they conducted some experiments and showed the effectiveness of this model in calculating similarity values between users even when only few ratings are available. In addition, the authors applied their user similarity model to a recommender system and analyzed its results.

Experiments on two real-world data sets are implemented and compared with some other CF techniques. The results show that the authors’ approach outperforms previous CF techniques in coverage metric while preserves accuracy for cold-start users and controversial items.

In the proposed approach, the conditions in which CF is unable to generate accurate recommendations are addressed. These conditions affect CF performance adversely, especially in the cold-start users’ condition. The authors show that their similarity model overcomes CF weaknesses effectively and improve its performance even in the cold users’ condition.

This paper aims to propose a comprehensive model to find out the most preventive subset of security controls against potential security attacks inside the limited budget. Deploying the appropriate collection of information security controls, especially in information system-dependent organizations, ensures their businesses' continuity alongside with their effectiveness and efficiency.

Impacts of security attacks are measured based on interdependent asset structure. Regarding this objective, the asset operational dependency graph is mapped to the security attack graph to assess the risks of attacks. This mapping enables us to measure the effectiveness of security controls against attacks. The most effective subset is found by mapping its features (cost and effectiveness) to items’ features in a binary knapsack problem, and then solving the problem by a modified version of the classic dynamic programming algorithm.

Exact solutions are achieved using the dynamic programming algorithm approach in the proposed model. Optimal security control subset is selected based on its implementation cost, its effectiveness and the limited budget.

Estimation of control effectiveness is the most significant limitation of the proposed model utilization. This is caused by lack of experience in risk management in organizations, which forces them to rely on reports and simulation results.

So far, cost-benefit approaches in security investments are followed only based on vulnerability assessment results. Moreover, dependency weights and types in interdependent structure of assets have been taken into account by a limited number of models. In the proposed model, a three-dimensional graph is used to capture the dependencies in risk assessment and optimal control subset selection, through a holistic approach.

The purpose of this research is to extract the natural frequencies of a circular plate containing a central hole reinforced with boron nitride nanotubes (BNNTs) and containing piezoelectric layers.

A unit cell shall be taken into account for the simulation of BNNT's volume fraction. A rectangular micromechanical model is used to obtain the mechanical properties of unit cell of piezoelectric fiber-reinforced composite (PFRC). The three-dimensional (3D) elasticity method is presented to provide the relationship between displacements and stresses. The one-dimensional differential quadrature method (1D-DQM) and the state-space methodology are combined to create the semi-analytical technique. The state-space approach is utilized to implement an analytical resolution in the thickness direction, and 1D-DQM is used to implement an approximation solution in the radial direction. The composite consists of a polyvinylidene fluoride (PVDF) matrix and BNNTs as reinforcement.

A study on the PFRC is carried, likewise, the coefficients of its properties are obtained using a micro-electromechanical model known as the rectangular model. To implement the DQM, the plate was radially divided into sample points, each with eight state variables. The boundary situation and DQM are used to discretize the state-space equations, and the top and bottom application surface conditions are used to determine the natural frequencies of the plate. The model's convergence is assessed. Additionally, the dimensionless frequency is compared to earlier works and ABAQUS simulation in order to validate the model. Finally, the effects of the thickness, lateral wavenumber, boundary conditions and BNNT volume fraction on the annular plate's free vibration are investigated. The important achievements are that increasing the volume fraction of BNNTs increases the natural frequency.

The micromechanical “XY rectangle” model in PFRC along with the three-dimensional elasticity model is used in this literature to assess how the piezoelectric capabilities of BNNTs affect the free vibration of polymer-based composite annular plates under various boundary conditions.