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In the past decades, Vehicular Ad hoc Networks (VANETs) have been increasingly developed. Providing secure and efficient communication is essential in VANETs. One of most important challeng...

Cloud Manufacturing (CMfg) is a new popular and centralised management and service-oriented business model that enables on-demand access to a shared collection of diversified and distribute...

Detecting spatio-temporal patterns as an interesting topic from different perspectives like detecting anomalies, unexpected and high-risk areas is a powerful means to manage future events by describing the current state and giving the possibility to predict the future. Criminology theories explain that the distribution of crime is not random. Although various specifications of crime are necessary for crime analysis, three types of most important information are location, time and environment data. Therefore, spatio-temporal crime patterns recognition plays an important role in crime analysis. This paper presents a new approach to detect the space and time areas which the crimes are most likely to happen. For this aim, a genetic-fuzzy system is developed to generate an interpretable fuzzy knowledge base that encompasses patterns for predicting future spatio-temporal crimes. It composed of three steps: fuzzy partitioning of the problem space, selecting meaningful features, and constructing the fuzzy knowledge base. We evaluate our proposed system using both a simulated dataset and a real-world dataset from Tehran, Iran. The results show that the proposed system is a suitable tool to find patterns and predict future crimes for environments with clustered crimes in space and time.

Vehicular Ad-hoc Networks (VANETs) are growing in recent decades providing real-time communication between vehicles for a safer and more comfortable driving. The main idea of VANET is the fact that vehicles can broadcast ad-hoc messages such as traffic incidents and emergency events. The security of such networks is quite critical. This paper firstly reviews and analyzes the main authentication schemes in VANET to compare their pros and cons. We then propose a new authentication scheme which provides secure communications in VANET. Our proposed scheme is a combination of Road Side Unit Based (RSUB) and Tamper Proof Device Based (TPDB) schemes. A novel idea in NECPPA is to let the keys and the main parameters of the system be stored in the Tamper Proof Device (TPD) of Road Side Units (RSUs). Since, there is always a secure and fast communicational link between TA and RSU, inserting TPD in RSUs is much more efficient than inserting them in OBUs. It also should be noted that due to the fact that in NECPPA scheme, the main key of TA (master secret key) is not stored in all OBUs, the compromise or hacking a single OBU does not threaten the whole network despite what happens in TPDB scheme which makes the whole vehicles re-register and change their secret keys. In addition, our proposed scheme is much more cost efficient compare to other on-line RSUB schemes, as it does not need the establishment of on-line RSUs in the whole roads. We also prove the security of our scheme with formal proof and ProVerif automatic analysis tool. The simulation results show that the efficiency and performance of our proposed scheme in VANETs have improved compare to other schemes.

Water scarcity invariably poses a threat to the sustainability of cities and rural areas with limited resources, especially in developing countries. This paper presents a new hydro-economic model based on system dynamics and agent-based simulation to enhance the sustainability of urban groundwater. Dynamic pricing was performed based on several parameters, such as resource conditions, price elasticity, consumption history and climate change, to improve the sustainability of groundwater and cover the costs of implementing strategies. Different scenarios based on pricing, rationing, culturalizing, and non-revenue water control strategies were applied in the village of Dehno in Yazd Province as the case study with an arid climate. The results showed that several scenarios can achieve the goal, but, in drought conditions, only a combination of all the strategies will work.

Insufficient clean freshwater has become a growing concern for sustainable development in countries with arid and semi-arid regions. Co-production of knowledge through active communication of experts, government, and local stakeholders can serve as a strategy to cope with water scarcity. Water consumption behavior is a key component of water resource management. This study aims to understand water consumption factors and behavior in a rural area with arid conditions. The study is a mixed-method one conducted through fuzzy decision analysis (i.e., selecting criteria with Fuzzy Delphi and rating them with Fuzzy Analytic Network Process). An empirical case study was conducted on the Akramieh rural area located in Yazd Province, Iran. The results indicate that a change in consumers' culture can have a significant effect in reducing water consumption. Recommendations have been made to encourage the adaptation of farming families to water scarcity. Through public schools and mosques, people can become aware of the conditions and consequences of drought as a crisis, and alternative methods of irrigation can be taught to farmers.

BACKGROUND In order to evaluate occupational disorders and ergonomic problems in a workplace, Multiple Criteria Decision Making (MCDM) problem solving methods such as Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) can be utilized. OBJECTIVE In this paper, Musculoskeletal Disorder (MSD) risk factors were evaluated in a manufacturing company in Iran by a method called Assessment of Repetitive Tasks (ART) of the upper limbs integrated with Fuzzy TOPSIS in order to prioritize the corrective actions. METHODS This study was done with a descriptive-analytical approach. The company under study had 240 employees who were working in seven different shops. Out of all tasks, 13 tasks were included in the study. Required information was gathered by a demographic questionnaire and ART method. Also, Fuzzy TOPSIS was utilized for the prioritization of the company shops based on the ergonomic control needs. RESULTS Data analysis from ART indicated that 74.6% of the reviewed tasks were high risk. Based on the F- TOPSIS-ART results, Production shop prioritized as the highest need for MSD control. CONCLUSIONS Because there is time and financial resources limit in ergonomic control activities, a fuzzy prioritization approach such as Fuzzy TOPSIS ART can be used to take advantage of the available resources and control risks to as low as reasonably practicable (ALARP) level.

Trust brings a novel means to improve the security of entities. Entities potentially initiate interactions with each other without having prior contacts. These interactions can either be formed directly between two entities or indirect through the recommendation of their acquaintances or third parties. In this paper, we present a novel trust model according to historical interaction between entities so that, the relations between entities are modeled based on four types (i.e. completely successful, completely unsuccessful, relatively successful and relatively unsuccessful) of their prior interactions. We also consider the reward and penalty for encouraging honest behaviors and preventing malicious behaviors, respectively. Unlike other proposed models, instead of taking into account the fixed amount of interactions for the experience level, in this paper, to calculate more accurate we have used the confidence interval to determine the level of experience. Also, to resist selfish and malicious behavior, the recommendation trust value for an entity computed by calculating the similarity-weighted recommendations of the entities that have interacted with him according to adjusted cosine similar function. In addition, we have developed the Petri Net model for design, analysis, and performance evaluation of the proposed model. By performing empirical evaluations, we have demonstrated that various scenarios can be better explained by our proposed reward and penalty trust model based on the confidence interval (RTMC) rather than the commonly used classical models. Simulation results and theoretical analysis proved that the RTMC promotes interaction between entities with containment capability in synergies cheating.

The thermal mechanism of acoustic modulation of the reversible electrical activities of peripheral nerves is investigated using the soliton model, and a numerical solution is presented for its non-homogenous version. Our results indicate that heating a small segment of the nerve will increase the action potential conduction velocity and decrease its amplitude. Moreover, cooling the nerve will have the reverse effects, and cooling to temperatures below the nerve melting point can reflect back a significant portion of the action potentials. These results are consistent with the theory of the soliton model, as well as with the experimental findings. Although there exists a discrepancy between the results of the soliton model and experimental pulse amplitude data, from the free energy point of view, the experiments are compatible with Heimburg and Jackson theory. We conclude that the presented model accompanied by the free energy view is capable of simulating the effects of thermal energy on nerve function. One potential application of the developed theoretical model will be investigation of the reversible and irreversible effects of thermal energy induced by various energy modalities, including therapeutic ultrasound, on nerve function.

Approximate solutions for vibrations of flexible beam-type appendages subjected to tip mass are studied while uniform and exponential profiles for arm deployment are simulated. Applying an equivalent dynamical system and following Lagrangian approach, the equations of motion of the system are derived as nonlinear ordinary differential equations (ODEs) (with time-varying coefficients), in which the effect of the tip mass can be considered as some nonlinearity added to the ‘no tip mass’ case dynamics. The approximate closed-form solutions are obtained through a novel methodology using a computer algorithm, in which the solutions of the ‘no tip mass’ case are expanded by imposing quadratic perturbations on the independent variable. The mean square of errors (MSEs) for the obtained approximate analytical solution is computed. Using this method, the amplitude and frequency of the arm response are presented by the algebraic equations, which help the parametric design of such systems. In addition, effects of tip mass as an indicator of nonlinearities added to the system dynamics, on the amplitude and frequency of the beam response, are investigated during arm deployment.

The family of four-parameter generalized lambda distributions (GLD) is known for its high flexibility. It provides an approximation of most of the usual statistical distributions (e.g., normal, uniform, lognormal, Weibull, etc.). Although GLD is used in many fields where precise data modeling is required, there are some statistical distributions that could not be estimated with high precision. The main objective of this article is to present an extension of generalized lambda distributions (XGLD) model for estimating statistical distributions. This new method has a considerable precision and high flexibility to fit more probability distribution functions with higher accuracy. Using the existing methods for calculation of GLD parameters, it provides methodology of calculating XGLD parameter measurement algorithmically. The XGLD estimations are computed for some well-known distributions and precision of estimations is compared with that of GLD.

The upper and lower bound principals of limit analysis are employed to determine the critical loading on solid circular plate with simply supported boundary conditions and subjected to any distributed loading with rotational symmetry. In this study, material behavior follows a rigid perfectly plastic model and yielding obeys the von-Mises criterion. Homotopy analysis method is employed to achieve the analytical solution to the high nonlinear ordinary differential equations governing the problem. This analytic solution has been obtained in terms of convergent series with easily computable terms. The results are verified with the Tresca yield criterion and presented as plots to show the reliability and simplicity of the method.

The existence of structure for ionizing fast-strong and fast-weak detonation waves in magnetohydrodynamics are proved. The reactions are assumed to be one step exothermic reactions with a natural discontinuous reaction rate function. The problem is studied for a general gas, considering some general thermodynamics rules which described by a fairly mild set of hypotheses. The uniqueness and nonuniqueness of structure are also considered.

Let q be a power of the prime p. The general and special linear groups in dimension n over the Galois field F q is denoted by GL n (q) and SL n (q) respectively and the projective versions of these groups are indicated by PGL n (q) and PSL n (q). Using polynomials of degree n over F q we show how it is possible to find the set of orders of elements in the above groups. This is achieved by writing computer programs whose details will be given in the text.

The non-rigid molecule group theory (NRG) in which the dynamical symmetry operations are defined as physical operations is a new field in chemistry. Smeyers and Villa computed the r-NRG of the triple equivalent methyl rotation in pyramidal trimethylamine with inversion and proved that the r-NRG of this molecule is a group of order 648, containing a subgroup of order 324 without inversions (see J. Math. Chem. 28(4) (2000) 377–388). In this work, a computational method is described, by means of which it is possible to calculate the symmetry group of molecules. We study the full non-rigid group (f-NRG) of Sponge and Pina molecules with C 2 and C i point groups, respectively. It proved that these are groups of order 162 and 13122 with 54 and 3240 conjugacy classes, respectively. The character tables of these groups are also computed.

A non-rigid molecule group theory (NRG) in which the dynamical symmetry operations are defined as physical operations is a new field of chemistry. Balasubramanian, Smeyers, and Villa in a series of...

The mathematical question of the existence of structure for shock waves in planar motion of plasma is reduced to finding heteroclinic orbits of a system of five ordinary differential equations, which depend on five viscosity parameters. It is shown that the system is gradient-like and has four rest points. An explicit bound is obtained for the set of the bounded complete solutions, and an isolating neighbourhood for this system is constructed. Then using Conley theory we prove that the fast and slow shock waves, of arbitrary strength, always possess structure. Using a limiting technique, the switch-on and switch-off shock structures are obtained as a topological limit of the fast and slow shock structures, respectively. Furthermore, we show that most of the intermediate shocks, in the absence of the electric field, admit structure. The stability of all of these structures is also shown.

Various numerical algorithms have been developed to solve the Khokhlov–Kuznetsov–Zabolotskaya (KZK) parabolic nonlinear wave equation. In this work, a generalized time-domain numerical algorithm is proposed to solve the diffraction term of the KZK equation. This algorithm solves the transverse Laplacian operator of the KZK equation in three-dimensional (3D) Cartesian coordinates using a finite-difference method based on the five-point implicit backward finite difference and the five-point Crank–Nicolson finite difference discretization techniques. This leads to a more uniform discretization of the Laplacian operator which in turn results in fewer calculation gridding nodes without compromising accuracy in the diffraction term. In addition, a new empirical algorithm based on the LU decomposition technique is proposed to solve the system of linear equations obtained from this discretization. The proposed empirical algorithm improves the calculation speed and memory usage, while the order of computational complexity remains linear in calculation of the diffraction term in the KZK equation. For evaluating the accuracy of the proposed algorithm, two previously published algorithms are used as comparison references: the conventional 2D Texas code and its generalization for 3D geometries. The results show that the accuracy/efficiency performance of the proposed algorithm is comparable with the established time-domain methods.

Nonlinear ultrasound modeling is finding an increasing number of applications in both medical and industrial areas where due to high pressure amplitudes the effects of nonlinear propagation are no longer negligible. Taking nonlinear effects into account makes the ultrasound beam analysis more accurate in these applications. One of the most widely used nonlinear models for propagation of 3D diffractive sound beams in dissipative media is the KZK (Khokhlov, Kuznetsov, Zabolotskaya) parabolic nonlinear wave equation. Various numerical algorithms have been developed to solve the KZK equation. Generally, these algorithms fall into one of three main categories: frequency domain, time domain and combined time-frequency domain. The intrinsic parabolic approximation in the KZK equation imposes a limiting accuracy on the solution to the diffraction term of the KZK equation, particularly for field points in near field or in far off-axis regions. In this work we developed a novel generalized time domain numerical algorithm to solve the diffraction term of the KZK equation. The algorithm solves the Laplacian operator of the KZK equation in 3D Cartesian coordinates using a novel finite difference technique. This leads to a more accurate solution to the diffraction term in the KZK equation without compromising calculational efficiency. The outcome is a new numerical algorithm to solve the KZK equation with higher accuracy and increased efficiency compared to current algorithms.

Magnetic flux leakage technique is used extensively to detect and characterize defects in natural gas and oil transmission pipelines. The amount of magnetic flux introduced into the test sample is an important factor in the resolution of flaw detection. It depends on the power of permanent magnets and the geometrical design of the magnetic yoke. Finite element method (FEM) is the most widely used method of analyzing magnetic yoke due to its power, accuracy and straightforwardness. On the other hand its calculations are so complicated and time consuming, and every single modification in the parameters of the problem requires a new run. In this paper, we present an innovative method to overcome the problem of heavy calculations. In this method an adaptive fractional model (AFM) is fitted, to the calculated values of FEM, to simulate the behavior of the magnetic yoke for different design parameters with an acceptable error. Tolerating an acceptable amount of error, AFM can be replaced by FEM. This replacement brings about flexibility besides reducing the heavy calculations considerably. Finally, setting the parameters of the model according to the nature of data, the FEM results can be reproduced.

Since Markowitz's substantial work, the mean-variance model has revolutionized the way people think about portfolio of assets. According to the modern portfolio theory, the fundamental principle of financial investments is a diversification where investors diversify their investments into different types of assets. Constructing an optimal risky portfolio is a high-dimensional constrained optimization problem where financial investors look for an optimal combination of their investments among different financial assets with the aim of achieving a maximum reward-to-variability ratio. Among the various methodologies suggested, the most popular one is based on maximizing the well-known Sharpe ratio. In this study, we apply particle swarm optimization (PSO) for constructing optimal risky portfolios based on Sharpe ratio for financial investments. A particle swarm solver is developed and tested on a risky investment portfolio. The method is applied to a sample of stocks in Tehran Stock Exchange. Experimental results reveal that the proposed PSO algorithm provides a very feasible and useful tool to assist the investors in planning their investment strategy and constructing their portfolio.

This paper presents the homotopy series solution of the Navier–Stokes and energy equations for non-Newtonian flows. Three different problems, Couette flow, Poiseuille flow and Couette–Poiseuille flow have been investigated. For all three cases, the nonlinear momentum and energy equations have been solved using the homotopy method and analytical approximations for the velocity and the temperature distribution have been obtained. The current results agree well with those obtained by the homotopy perturbation method derived by Siddiqui et al (2008 Chaos Solitons Fractals 36 182–92). In addition to providing analytical solutions, this paper draws attention to interesting physical phenomena observed in non-Newtonian channel flows. For example, it is observed that the velocity profile of non-Newtonian Couette flow is indistinctive from the velocity profile of the Newtonian one. Additionally, we observe flow separation in non-Newtonian Couette–Poiseuille flow even though the pressure gradient is negative (favorable). We provide physical reasoning for these unique phenomena.