Ali Rostami

Assessment of elemental concentrations in the urban air (case study: Tehran city)

Tehran is one of the megacities of the world with a population of over eight million. Its air is highly polluted mainly due to the suspended particulate matters, which encompasses a wide spectrum of chemical elements. These elements based on their type, size, and impact on the life cycle have various environmental and heath risks. In this research, the neutron activation method is used to determine the concentration levels of Al, Ba, Fe, Mg, and V in the urban air. Thus, two districts of Tehran with different characteristics are selected. District 21 includes much of the industries located in Tehran metropolitan and is considered as an industrial area. In contrast, district 22 lacks any significant industrial activity. It is a newly established and expanding district adjacent to district 21 with a great deal of constructional activities. For the measurement of the suspended particulate matters in the air, the various sections of the aforesaid districts with industrial, residential, heavily congested traffic, residential/commercial, residential/heavily congested traffic, and residential/industrial classifications were identified. Subsequently, 24 sampling stations were selected. The sampling of the suspended particulate matters was conducted with the aid of a high volume pump containing 125xa0mm cellulose filters in two different time intervals. After completion of the sampling process, the samples were prepared and sent to the research reactor of the Iran Nuclear Energy Organization for Neutron Activation. During the next steps, the radiations emitted from the samples were registered, the radiation curves were plotted, and the amounts of the trace elements were determined. As a result, the average concentration levels of Al, Ba, Fe, Mg, and V were identified to be 3.301140, 2.273658xa0×xa010, 4.0681696xa0×xa010u2009−u20091, 3.5525475xa0×xa010u2009−u20091, and 3.04075xa0×xa010u2009−u20092xa0μg/m3, respectively. Moreover, the emission sources of the aforesaid elements into the air were identified. The concentration levels of these elements in the industrial and heavily congested traffic sections were higher. Finally, it was concluded that the statistical analysis of these elements presents a meaningful correlation among them.

Comparison of Trace Element Concentrations in Ambient Air of Industrial and Residential Areas in Tehran City

Tehran is densely populated possessing unhealthy and polluted air. There are 22 municipality districts in Tehran, and considerable numbers of industries are located within each district. Due to adverse environmental and health effects of trace elements in urban air, this study has been carried out to measure and compare concentration of trace elements including Ag, As, Br, Ce, Co, Cr, Cs, Cu, Mn, Hf, La, Sb, Sc, Sm, Th, and Zn in industrial (district 21) and residential (district 22) areas. For this purpose, total suspended particles were collected in two different time intervals in the year 2008. As a result, maximum and minimum concentrations in residential area associated with Mn (2.9xa0μg/m3) and Hf (2.92u2009×u200910−4xa0μg/m3), respectively. Also, in industrial sites, these concentrations are higher for Mn (4.79u2009×u200910−1xa0μg/m3) and Hf (6.65u2009×u200910−4xa0μg/m3). The concentrations of Mn (2.07xa0μg/m3) and Hf (7.46u2009×u200910−4xa0μg/m3) in traffic zone are close to residential values. General, concentrations of Ce, Co, Cs, La, Sc, Sm, Th, Br, and Hf in industrial area were higher than in residential area. The source of these elements in Tehrans air is mainly anthropogenic. According to the achieved results, the concentration levels of As, Cr, and Zn were close together in both residential and industrial zones. Therefore, these elements could have been originated from natural sources. Also, results show that levels of Ag, Mn, Sb, and Cu in residential area were higher than in industrial area. Finally, obtained data indicated that the trends of average concentration of trace elements in industrial area (from low to high) follow as Hf

Designing a random number generator with novel parallel LFSR substructure for key stream ciphers

Todays demand of secure data exchange and manipulation rely mostly on the use of cryptography. The most important and difficult part of any cryptographic system is to generate secret keys of high randomness quality. Therefore the generation process of random bits is becoming increasingly important. Since the use of a truly random generator is very difficult as they are generally slow and may consist of special hardware, the importance of designing efficient pseudo-random generators arises. A large number of stream ciphers, act based on linear feedback shift registers (LFSRs) and since a feedback shift register (FSR) is included memory bits and a serious of feedback and applicable with a number of XORs can be gained noticeable security to a few gates. So we designed a new random number generator (RNG) with novel PS-LFSR substructure with very good random characteristics that has many applications in stream ciphers.

A flexible sample and hold circuit for data converter applications

The sample and hold circuit is perhaps the most important building block in most data acquisition systems such as data converter. Flexibility of this block can be used to improve the whole performance of the system. In this work a flexible structure with variable gain is presented. The circuit is used to calibrate a typical time interleaved analog to digital converter. Simulation results indicated that modified circuit is superior in some aspects to the commonly used architectures. Designed circuit is simulated in a standard 0.35 mum CMOS technology, the SHA achieves 87 dB SFDR for 2 Vpp input at 200 MHz sampling rate. The performance is not degraded for inputpsilas frequency up to the Nyquist frequency.

A Private Secure Communication Scheme Using UKF - based Chaos Synchronization

This paper presents a novel chaotic communication method using an Unscented Kalman Filter (UKF). Applying UKF, the method proposes the estimation of the state variables of the chaotic dynamical system and synchronization. The proposed method is then applied to new private secure communication. The chaotic synchronization is implemented by the UKF in the presence of processing noise and measurement noise. The main highlighted advantages of using UKF are increasing accuracy, efficiency and improvement of synchronization’s time. Encoding chaotic communication achieves a satisfactory, typical secure communication scheme. To illustrate the effectiveness of the proposed scheme, a numerical example based on the Lorenz dynamical system and Rössler dynamical system is presented and the results are compared to the Extended Kalman Filter (EKF). The results of simulation have shown the improvement of the function in the case of increasing the accuracy and efficiency of the synchronization, and decreasing its time.

Novel Algorithm of Energy-Aware in Asymmetric Wireless Sensor Networks Routing for In-Point Coverage

since we are not able to replace the battery in a wireless sensor network, energy and lifetime are the most important parameters. Common sensors are not able to connect directly with the central station due to their limited ranges in asymmetrical wireless networks, therefore, we utilize super nodes. A super node has more energy, processing power and a wider range of communication. It does connectivity and transmits data to the base station, nevertheless, it is not possible for all simple nodes to connect to the super nodes directly and they transmit data through other nodes. Optimal selection and considering the energy of relay nodes are the most important sections of designing a wireless network to choose and transmit data and increase the lifetime of the network. In this paper, an energy-aware routing algorithm is presented for sensor networks.

Unscented Kalman Filter Applied to noisy synchronization of Rossler chaotic system

Extended Kalman Filter (EKF) has been widely used as an important tool in practical applications to estimate states of nonlinear systems. There are a number of deficiencies in EKF such as biased estimation, complexity in calculation and inefficacity in not being able to compute analytical derivatives affect its application in many fields. In this paper, Unscented Kalman Filter (UKF) is employed for estimation of the state variables of the chaotic dynamical system. The chaotic synchronization is implemented by the UKF in the presence of processing noise and measurement noise. The results of the simulation on the Rossler chaotic system by UKF and its comparison with EKF show that the UKF has more accuracy and efficiency than EKF.

Optimizing the parameters of active sensor selection and using GA to decrease energy consumption in point coverage wireless sensor networks

Energy and lifetime are the most important design objectives in many wireless sensor network applications. In asymmetrical sensor networks, different sensors with various abilities are used. It is crucial to select the parameters of fit function and monitoring sensors optimally in a point coverage network. In this paper, our approach uses genetic algorithm to optimize the parameters of monitoring sensor selection for each round in a point coverage network. Optimal selection of covering nodes for point coverage is done by effective deletion of redundant nodes, considering data transmission cost and heeding the energy of relay nodes for the whole previous lifetime of the network. Reducing the number of active sensors, in a covering set, saves more energy and consequently increases lifetime. Simulation results demonstrate that our algorithm to optimize selection parameters is effective in lifetime prolonging and energy consumption reduction for each round or the whole time of network activity.