Sharif Digital Repository

Nowadays communication and monitoring systems play an important role in power systems security. However, these systems are exposed to bad data injection through attackers. This paper is aimed to propose a priority order list of attacked buses in order to be fully informed about the attacker decision. To do so, system security is evaluated through two well-known risk indices including under voltage risk index and overloading risk index. A genetic algorithm (GA) is employed to determine the most severe attack for each of the security indices. The effectiveness and accuracy of the proposed model are scrutinized through simulations on the IEEE 30-bus network. The paper reveals that knowing the... 

Historically, the general target of affecting demand via voltage regulation was conservation, i.e., reducing peak demand and/or accumulated energy. In private environments however, profit maximization may take place of conservation, regardless of the social welfare and consumers' costs. This letter aims at highlighting the effectiveness of voltage regulation as a measure to maximize utilities' profit. The new strategy can indeliberately cause more payments for customers. The letter simulates different cases which reveal importance of the role regulatory bodies have to play to prevent unethical actions in private environments. IEEE  

In this paper, an adaptive FE analysis is presented based on error estimation, adaptive mesh refinement and data transfer for enriched plasticity continua in the modelling of strain localization. As the classical continuum models suffer from pathological mesh-dependence in the strain softening models, the governing equations are regularized by adding rotational degrees-of-freedom to the conventional degrees-of-freedom. Adaptive strategy using element elongation is applied to compute the distribution of required element size using the estimated error distribution. Once a new mesh is generated, state variables and history-dependent variables are mapped from the old finite element mesh to the... 

Distribution networks are designed in loop structure, while they are operated as radial networks. In this regard, the location of normally open (NO) switches is usually determined by either minimizing real power losses or maximizing the reliability level. However, considering both losses and reliability in the decision making procedure may lead to a better solution. To do so, this paper proposes a mathematical model to find the optimal configuration of NO switches such that losses and reliability are optimized. The multi-objective model is scrutinized via weighted sum approach to achieve a single-objective model. The model is formulated in mixed integer quadratically constrained programming... 

The standard power flow (PF) equations are nonlinear, and their integration in the optimal PF (OPF) problem leads to a nonconvex hard-to-solve model. To attack the issue, this paper presents a linear PF model wherein real and imaginary parts of nodal voltages are variables. In the model, loads are interpreted via ZIP model including constant impedance, constant current, and constant power components. To preserve linearity of the model, the complex power is represented via a quadratic function of the hosting node voltage. The function coefficients are derived via curve fitting approaches. Since the model is linear, its solution does not need repetition and can be effectively integrated in the... 

Self-Compacting concrete (SCC) is identified as a high performance concrete with the ability of self compaction, using its own weight without any external vibration. SCC is able to fill congested area and voids, even in highly reinforced concrete members whilst it flows without segregation. The fresh properties of SCC such as workability can be determined using different tests including slump-flow, J ring, V-funnel, U box, L box, GTM and column technique. In this paper the effect of different amount of cementitious material, silica fume and W/C ratios on workability and compressive strength of SCC are investigated. The results indicate that the workability of mixtures is reduced by... 

Learning a foreign language encompasses a process of trial and error that can lead to the progression of the learner's interlanguage, meaning that the learners make use of their language knowledge that receives feedback and brings about progress through diagnosis of the problems and being corrected by the teacher. Therefore, there exists a need to analyze the underlying reasons causing the students to remain taciturn with a low willingness to communicate (WTC) during a language class. There has been much work done investigating the role of the learner's stable personal characteristics (traits) along with their situational changes at a specific time (states) that influence the student's... 

Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images... 

In this paper, we try to recognize and distinguish different groups of arrhythmia using novel features which have been obtained from the heart rate's phase space in recent years. For this purpose, we used Triangular Phase Space Mapping (TPSM) and Parabolic Phase Space Mapping (PPSM). For recognition, we used three groups of 15 subjects using the Physionet database (Arrhythmia, Congestive Heart Failure (CHF), and Atrial Fibrillation (AF)) with Normal Sinus Rhythm (NSR). The obtained features discriminate arrhythmia from NSR by p