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匹配条件: “Farid Radmanesh” ,找到相关结果约923条。
Congenital spinal tumor in a patient with encephalocele and hydrocephalus: a case report
Farid Radmanesh, Farideh Nejat, Fatemeh Mahjoub, Mostafa El Khashab
Journal of Medical Case Reports , 2011, DOI: 10.1186/1752-1947-5-9
Abstract: We report the case of an Iranian girl with a history of encephalocele surgery, who, at the age of four years, developed an intramedullary spinal teratoma, and discuss the pathogenesis of this association.To the best of our knowledge, this is the first report of an association between encephalocele and spinal teratoma.Encephalocele refers to a group of rare congenital anomalies of the central nervous system (CNS), where brain tissue protrudes from a defect in the skull [1]. Its prevalence has been estimated to be 0.8 to four in every 10,000 live births [2].Teratomas are tumors derived from all three germ layers [3]. In children, teratomas are more commonly found in the sacrococcygeal region than in the spinal cord [4], which occurs in one of 38,500 viable births. Intramedullary spinal teratomas are rare tumors [5]. In 41.7% of teratomas, a concomitant anomaly of the vertebral canal is found, most commonly a diastematomyelia, [4]. However to the best of our knowledge, there is nor repot of an association with encephalocele in the English literature.We report a case of encephalocele and lumbar intramedullary teratoma and discuss the possible etiology.A four-year old Iranian girl was referred to the neurosurgical department with severe back pain and motor regression. She was the second child of nonconsanguineous parents, and was delivered by elective Cesarean section due to being repeat. She had a history of occipital encephalocele, which was treated surgically during the neonatal period and she later received a shunt to treat progressive hydrocephalus. She could sit at nine month of age and stand at two years, but was unable to walk. Six months before her referral, she had developed back pain, which was particularly severe at night, and after three months, she was unable to stand.On physical examination, our patient was found to be generally normal, with good mental performance, and normal results from a neurological examination of the arms. She had a head circumferenc
Effects of Laser Pulse Numbers on Surface Biocompatibility of Titanium for Implant Fabrication  [PDF]
Mitra Radmanesh, Amirkianoosh Kiani
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2015, DOI: 10.4236/jbnb.2015.63017
Abstract: Generally, materials with high biocompatibility are more appropriate for bone and tissue transplant applications, due to their higher effectiveness in the healing process and infection problems. This study presents the effects of laser surface texturing on the surface topography properties, roughness, and wettability of thin titanium sheets, which consequently enhance the biocompatibility of this material. Creating line patterns across the surfaces, the titanium samples are prepared using variety of laser parameters. The apatite inducing ability of each sample is tested through the use of simulated body fluid (SBF). The final biocompatibility level of titanium samples is analyzed through wettability, surface angle measurements, and average surface temperature profile. Overall, the effects of laser parameter, pulse numbers, upon the biocompatibility of titanium are thoroughly examined, with results indicating that a scanning speed of 100 μm/ms results in desirable bone type apatite inducing abilities across the surface of treated titanium sheets.
ND:YAG Laser Pulses Ablation Threshold of Stainless Steel 304  [PDF]
Mitra Radmanesh, Amirkianoosh Kiani
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.67065
Abstract: Laser processing and laser surface texturing in multiple fields have become a popular topic of study in recent decades. Understanding the principles behind the laser irradiation mechanism is an essential step in choosing the most effective process parameters. Through this study, the effects of power and pulse duration on the structure and surface pattern of stainless steel type 304 were examined, and optimized laser parameters were introduced for desired laser penetration and heat-affected areas on the surface. The analyzed sample was prepared by using variations of pulse durations and different pulsed energies. Looking at the trend of change of non-dimensional temperature along the surface, thickness, and center of the sample, the effects of pulse duration and intensity (corresponding to energy) were observed. Upon considering all the aspects of the irradiated spots, such as heat-affected area diameter, surface patterns, and penetration depth, the advantages and disadvantages of short and long pulse durations are mapped out clearly. Also, a new method to obtain the ablation threshold of stainless steel is introduced, and a thorough analytical solution is obtained.
Effect of Circuit Breaker Shunt Resistance on Chaotic Ferroresonance in Voltage Transformer
Advances in Electrical and Computer Engineering , 2010, DOI: 10.4316/aece.2010.03012
Abstract: Ferroresonance or nonlinear resonance is a complex electrical phenomenon, which may cause over voltages and over currents in the electrical power system which endangers the system reliability and continuous safe operating. This paper studies the effect of circuit breaker shunt resistance on the control of chaotic ferroresonance in a voltage transformer. It is expected that this resistance generally can cause ferroresonance dropout. For confirmation this aspect Simulation has been done on a one phase voltage transformer rated 100VA, 275kV. The magnetization characteristic of the transformer is modeled by a single-value two-term polynomial with q=7. The simulation results reveal that considering the shunt resistance on the circuit breaker, exhibits a great mitigating effect on ferroresonance over voltages. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance voltages has been obtained and presented.
Studying Voltage Transformer Ferroresonance
Hamid Radmanesh,Hamid Fathi
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: This study studies the effect of Circuit Breaker Shunt Resistance (CBSR), Metal Oxide Vaistor (MOV) and Neutral earth Resistance (NR) on the control of ferroresonance in the voltage transformer. It is expected that NR can controlled ferroresonance better than MOV and CBSR. Study has been done on a one phase voltage transformer rated 100 VA, 275 kV. The simulation results reveal that considering the CBSR and MOV exhibits a great mitigating effect on ferroresonance overvoltages, but these resistances cannot control these phenomena for all range of parameters. By applying NR to the system structure, ferroresonance has been controlled and its amplitude has been damped for all parameters values.
Analyzing Ferroresonance Phenomena in Power Transformers Including Zinc Oxide Arrester and Neutral Resistance Effect
Hamid Radmanesh,Fathi Seyed Hamid
Applied Computational Intelligence and Soft Computing , 2012, DOI: 10.1155/2012/525494
Abstract: This paper studies the effect of zinc oxide arrester (ZnO) and neutral earth resistance on controlling nonconventional oscillations of the unloaded power transformer. At first, ferroresonance overvoltage in the power system including ZnO is investigated. It is shown this nonlinear resistance can limit the ferroresonance oscillations but it cannot successfully control these phenomena. Because of the temperature dissipation of ZnO, it can withstand against overvoltage in a short period and after that ferroresonance causes ZnO failure. By applying neutral earth resistance to the system configuration, mitigating ferroresonance has been increased and chaotic overvoltage has been changed to the smoother behavior such as fundamental resonance and periodic oscillation. The simulation results show that connecting the neutral resistance exhibits a great mitigating effect on nonlinear overvoltage. 1. Introduction Ferroresonance is a complex electromagnetic phenomenon which may be neglected in power system studies which is carried out for routine designs, planning, and operations [1]. A stability domain calculation of period-1 ferroresonance in nonlinear resonant circuit power system elements is given in [2]. In this case, quasistatic analytical approaches can be used to give a quick indication of the locations of domains of different ferroresonant states as a function of a set of parameters. Fast ferroresonance suppression of coupling capacitor voltage transformers (CCVT) is studied in [3]. This paper describes a procedure for fast suppression of the phenomenon of ferroresonance in CCVT without major change in the design. The design of a hall effect current transformer and examination of the linearity with real time parameter estimation is given in [4]. The aim of “blind source separation” (BSS) is to recover mutually independent unknown source signals only from observations obtained through an unknown linear mixture system [5]. Sensitivity studies on power transformer ferroresonance of a 400?kV double circuit are given in [6]. Novel analytical solution to fundamental ferroresonance in [7] investigated a major problem with the traditional excitation characteristic of nonlinear inductors. Application of wavelet transform and MLP neural network for ferroresonance identification was done in [8]. Impacts of transformer core hysteresis formation on stability domain of ferroresonance modes were done in [9]. The principle of AC current transformers (CT) based on the magnetic coupling principle is given in [10]. Current paper studies the effect of neutral resistance on
Stabilizing Ferroresonance Oscillations in Voltage Transformers Using Limiter Circuit
Hamid Radmanesh,Seyed Hamid Fathi
Electronics , 2012,
Abstract: This paper employs the multiple scales method and chaos theory for analyzing chaotic behavior of the voltage transformer (VT) with linear core loss model. It is shown that ferroresonance phenomenon in VTs can be classified as chaotic dynamics, including a sequence of bifurcations such as period doubling bifurcation (PDB), saddle node bifurcation (SNB), Hopf Bifurcation (HB) and chaos. Bifurcation diagrams and phase plane diagrams are drawn using a continuation method for linear core loss model and lyapunov exponents are obtained using the multiple scales method. At first an overview of the subject in the literature is provided. Then, ferroresonance phenomenon is introduced and its various types in a VT are simulated. Finally the effects of ferroresonance suppression circuit on stabilizing these oscillations are studied. The proposed approach is implemented using MATLAB, and simulation results are presented. The results show connecting the ferroresonance suppression circuit to the system configuration, causes great controlling effect on ferroresonance overvoltage.
Taxpayers Fraudulent Behavior Modeling The Use of Datamining in Fiscal Fraud Detecting Moroccan Case  [PDF]
Farid Ameur, Mohamed Tkiouat
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.310176
Abstract: The fraudulent behavior of taxpayers impacts negatively the resources available to finance public services. It creates distortions of competition and inequality, harming honest taxpayers. Such behavior requires the government intervention to bring order and establish a fiscal justice. This study emphasizes the determination of the interactions linking taxpayers with tax authorities. We try to see how fiscal audit can influence taxpayers’ fraudulent behavior. First of all, we present a theoretical study of a model pre established by other authors. We have released some conditions of this model and we have introduced a new parameter reflecting the efficiency of tax control; we found that the efficiency of a fiscal control have an important effect on these interactions. Basing on the fact that the detection of fraudulent taxpayers is the most difficult step in fiscal control, We established a new approach using DATA MINING process in order to improve fiscal control efficiency. We found results that reflect fairly the conduct of taxpayers that we have tested based on actual statistics. The results are reliable.
Using a GIS to Assessment the Load-Carrying Capacity of Soil Case of Berhoum Area, Hodna Basin, (Eastern Algeria)  [PDF]
Amar Guettouche, Farid Kaoua
Journal of Geographic Information System (JGIS) , 2013, DOI: 10.4236/jgis.2013.55046
Abstract: The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth; and therefore, running it begins its assessment that allows an outline of exploitation. Nevertheless, the assessment of the load-carrying capacity made the object of several works of research and many models, based on the multi-criteria analysis, have been established. This work examines the contribution of GIS approach to assessment load-carrying capacity of the soil. This one has been finished in two practicums: 1) Assessment of the capacity of soil by a multi-criteria approach, using the Weighted Sum Model (WSM); 2) It brought to use the GIS approach to evaluate and spatialize degree of soil bearing stresses resulting from the buildings, as well as load distribution. The method has been applied to the Berhoum area of Hodna Basin, in eastern Algeria, where each is characterized by its various natural properties and density of equipment. Final results are better in the classification of the degree of load-carrying capacity possible in each site. This results in allowing exploiters to program their optimal designs for the rational management of the area.
Characterization and Valorization of Two Algerian Bentonites in the Waterproofing Systems  [PDF]
Messaouda Debieche, Farid Kaoua
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.55040

The interest in environment has recently considerably grown, and its protection is now included in the continuous action of the governments and the industries. In Algeria, the different types of waste are currently produced in almost 3.000 illegal dumps, occupying approximately 150.000 hectares. To overcome this problem, waterproofing sites prove the most appropriate solution. It is a geotechnical method to guard against the action of water by narrowing the flow of water through a surface in a given time. The site’s waterproofing technique, in the landfills sites, is nowadays a very necessary condition to protect the environment, which requires the use of appropriate materials. This work deals within the valorization of local materials (sand and bentonite), in the waterproofing technique of the technical landfills site “TLS”. To this end, two types of bentonites from the west of Algeria are used. In order to achieve an optimal mixture, ensuring good performance in terms of hydraulic conductivity, durability and shear strength, mixtures based of sand at different concentrations of bentonite, at compact state are prepared and studied. This study showed that a low permeability of mixture (sand/bentonite) can be achieved with introducing 8% of a calcium bentonite, against 6% of a sodium bentonite. The latter presents a great adsorption capacity and a self healing ability, compared to calcium bentonite. This gives a good sustainability against climate variations of mixture based on sodium bentonite. This mixture has also confered a good mechanical behavior, expressed by the recorded, reduction of the friction angle (Φ) and the increase of the cohesion (C). Therefore it represents an optimal mixture for waterproofing systems, due to its economical and ecological advantages.


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