MIMO Underwater Visible Light Communications: Comprehensive Channel Study, Performance Analysis, and Multiple-Symbol Detection

In this paper, we analytically study the bit error rate (BER) performance of underwater visible light communication (UVLC) systems with binary pulse position modulation (BPPM). We simulate the channel fading-free impulse response (FFIR) based on Monte Carlo numerical method to take into account the absorption and scattering effects. Additionally, to characterize turbulence effects, we multiply the aforementioned FFIR by a fading coefficient which for weak oceanic turbulence can be modeled as a lognormal random variable (RV). Moreover, to mitigate turbulence effects, we employ multiple transmitters and/or receivers, i.e., spatial diversity technique over UVLC links. Closed-form expressions for the system BER are provided, when equal gain combiner (EGC) is employed at the receiver side, thanks to Gauss-Hermite quadrature formula and approximation to the sum of lognormal RVs. We further apply saddle-point approximation, an accurate photon-counting-based method, to evaluate the system BER in the presence of shot noise. Both laser-based collimated and light emitting diode (LED)-based diffusive links are investigated. Since multiple-scattering effect of UVLC channels on the propagating photons causes considerable inter-symbol interference (ISI), especially for diffusive channels, we also obtain the optimum multiple-symbol detection (MSD) algorithm to significantly alleviate ISI effects and improve the system performance. Our numerical analysis indicates good matches between the analytical and photon-counting results implying the negligibility of signal-dependent shot noise, and also between analytical results and numerical simulations confirming the accuracy of our derived closed-form expressions for the system BER. Besides, our results show that spatial diversity significantly mitigates fading impairments while MSD considerably alleviates ISI deteriorations

Realization of peace from the perspective of the role of higher education in the field of diplomacy: experience of academic diplomacy in Iran

New diplomacy with a focus on new actors is a ground for removal of misconceptions and solution of conflicts through communication, dialogue and reach of consensus. Higher education institution, especially universities, can be referred as new actors in the field of diplomacy. They can play an important role in communicating mutually and symmetrically. According to the authors, universities can provide the ground for removal of misunderstanding which is the root of violence at the level of communication within universities, both in a form of diplomacy Track II and also, through playing role in the science and technology diplomacy framework and they can be effective in promoting the culture of peace while they present positive image and enhance the country’s position in the international arena. So, in present study, it was tried to analyze the promotion of culture of peace in terms of the effectiveness of higher education on diplomacy institution and also, the position of higher education institution in the diplomacy of the Islamic Republic of Iran by descriptive-analytical method and relying on the Habermas’s communicative action theory.  The results showed that the universities can contribute to the realization and promotion of peace through affecting diplomacy and relying on science and knowledge which are international language; also provided that there is purposeful policy-making to maximum use of the potential of higher education institutions in general, and specifically universities. Especially in Iran, despite negative beliefs, universities can provide positive images in international arena.Keywords: higher education, university, peace, science diplomacy, diplomacy Track I

Ecological quality of Bahrekan coast, by using biotic indices and benthic communities

1 - The aim of this study was identifying macrobenthos biodiversity and an assessment of the ecological quality status of Bahrekan coast in Persian Gulf, using AMBI, Bentix indices according to softbottom marine benthic communities. Other ecological indices, such as theShannon diversity index (H`) and the species richness ( S ) were also applied and evaluated comparatively. 2 - In total, 111 genus/species were recognized, divided into 17 groups with gastropodas always dominant and the substrate in all of the stations was characterized as muddy bottom. 3 - The macrobenthic animals according to their sensitivity to an increasing stress gradient, were classified in 5 ecological groups. 4 - Due to the high dominance of species such as Pyrgohydrobia sp., Tornatina sp., Melinna sp., Cossura sp. and Sternaspis sp, diversity values were reduced. 5 - According to the results of AMBI, BI, Bentix, and H`indices Bahrekan coast is classified in slightly to moderate pollution status

Statistical Studies of Fading in Underwater Wireless Optical Channels in the Presence of Air Bubble, Temperature, and Salinity Random Variations (Long Version)

Optical signal propagation through underwater channels is affected by three main degrading phenomena, namely absorption, scattering, and fading. In this paper, we experimentally study the statistical distribution of intensity fluctuations in underwater wireless optical channels with random temperature and salinity variations as well as the presence of air bubbles. In particular, we define different scenarios to produce random fluctuations on the water refractive index across the propagation path, and then examine the accuracy of various statistical distributions in terms of their goodness of fit to the experimental data. We also obtain the channel coherence time to address the average period of fading temporal variations. The scenarios under consideration cover a wide range of scintillation index from weak to strong turbulence. Moreover, the effects of beam-collimator at the transmitter side and aperture averaging lens at the receiver side are experimentally investigated. We show that the use of a transmitter beam-collimator and/or a receiver aperture averaging lens suits single-lobe distributions such that the generalized Gamma and exponential Weibull distributions can excellently match the histograms of the acquired data. Our experimental results further reveal that the channel coherence time is on the order of $10^{-3}$ seconds and larger which implies to the slow fading turbulent channels

Effect of plant cover on presence of Black Francolin (Francolinus francolinus) in Khouzestan Province, Southwestern Iran

Three of 6 subspecies of black francolins (Francolinus francolinus), are found throughout Iran. Habitat destruction and indiscriminate hunting as well as agricultural pesticides are among the most crucial factors threatening the populations of these birds in Khouzestan Province, southwestern Iran. Using plot sampling, this study aims to investigate different vegetative factors including plant species, percentage of species presence and dominant plant cover height on francolin presence. Sampling was carried out throughout 5 presence areas of black francolin and 2 areas lacking francolins (control areas). Results showed that frequency of Camels thorn (Alhagi cameloram), Cashew (Prosopis farcta) and African Salsola (Suaeda fruticosa) were higher in presence areas compared with other plant species. Using One Way ANOVA, it was determined that there was no significant difference between plant cover percent (P = 0.279) and dominant plant cover height (P = 0.316). However, difference of these two mentioned factors were significant in 4 seasons (P = 000 for cover height and P = 0.001 for cover percent). In fact, the highest black francolin presence was recorded at 15 – 67 and 4 – 48 for cover percent and cover height classes respectively

Lateral stress evolution in chromium sulfide cermets with varying excess chromium

The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a onedimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium content

Development of a New Kinetic Model for Methanol to Propylene Process on Mn/H-ZSM-5 Catalyst

The activity of the H-ZSM-5 was modified by the addition of Ca, Mn, Cr, Fe, Ni, Ag, Ce and P. The highest selectivity of propylene was obtained over the Mn/H-ZSM-5 catalyst. The Mn modified catalyst was selected as the optimal catalyst and the kinetic study was carried out on it. All of the experiments were carried out in an isothermal fixed bed and plug flow reactor with the mixture of methanol and water. The temperature range was 400–550 °C and the weight hourly space velocities (WHSV) of methanol were: 2.51, 5.42, and 8.17 h–1. A reaction mechanism based on the theory of hydrocarbon pool and conjugate methylation/cracking mechanisms was proposed. The behavior of the reactor was mathematically modeled and the hybrid genetic algorithm was applied to estimate kinetic parameters. Good agreement was observed between the experimental and the calculated data. Effect of temperature on propylene selectivity was also investigated. It was found that the propylene selectivity steadily increases with temperature

Evaluation of Benzimidazole Resistance in Haemonchus contortus Using Comparative PCR-RFLP Methods

Background: In order to deworm the ruminants especially of sheep in Iran, consumption of benzimi­dazoles has more than 2 decades history and today farmers are using imidazothiazoles, macrocyclic lactones and mostly benzimidazole compounds (BZs) to treat infected farm animals. It has been demonstrated that the most common molecular mechanism leading to BZsresistance in Haemonchus contortus is a single mutation at amino acid 200 (phenylalanine to tyrosine) of the isotype 1 of beta tubulin gene. According to the report of such mutations in Iranian Telador­sagia circumcincta isolates with Restriction Site Created PCR-RFLP, we decided to evaluate the frequency of such mutations in H. contortus in three different geographical areas of Iran.Methodes: A total of 102 collected adult male H. contortus were evaluated with PCR-RFLP (us­ing PSP1406I as restriction enzyme). By means of a second step to compare function of different methods and to increase sensitivity of detection mechanism, a third of samples were examined by another PCR-RFLP method (using TaaI as restriction enzyme) and finally beta tubulin gene of two samples was sequenced.Results: All of samples were detected as BZss homozygote. Finally, beta tubulin gene sequenc­ing of two samples showed no point mutation at codon 200.Conclusion: It seems that BZresistance of H. contortus in Iran is not a serious problem as antici­pated before

A review of developments in carbon dioxide storage

Carbon capture and storage (CCS) has been identified as an urgent, strategic and essential approach to reduce anthropogenic CO2 emissions, and mitigate the severe consequences of climate change. CO2 storage is the last step in the CCS chain and can be implemented mainly through oceanic and underground geological sequestration, and mineral carbonation. This review paper aims to provide state-of-the-art developments in CO2 storage. The review initially discussed the potential options for CO2 storage by highlighting the present status, current challenges and uncertainties associated with further deployment of established approaches (such as storage in saline aquifers and depleted oil and gas reservoirs) and feasibility demonstration of relatively newer storage concepts (such as hydrate storage and CO2-based enhanced geothermal systems). The second part of the review outlined the critical criteria that are necessary for storage site selection, including geological, geothermal, geohazards, hydrodynamic, basin maturity, and economic, societal and environmental factors. In the third section, the focus was on identification of CO2 behaviour within the reservoir during and after injection, namely injection-induced seismicity, potential leakage pathways, and long-term containment complexities associated with CO2-brine-rock interaction. In addition, a detailed review on storage capacity estimation methods based on different geological media and trapping mechanisms was provided. Finally, an overview of major CO2 storage projects, including their overall outcomes, were outlined. This review indicates that although CO2 storage is a technically proven strategy, the discussed challenges need to be addressed in order to accelerate the deployment of the technology. In addition, beside the necessity of techno-economic aspects, public acceptance of CO2 storage plays a central role in technology deployment, and the current ethical mechanisms need to be further improved

Switching off malignant mesothelioma : exploiting the hypoxic microenvironment

Malignant mesotheliomas are aggressive, asbestos-related cancers with poor patient prognosis, typically arising in the mesothelial surfaces of tissues in pleural and peritoneal cavity. The relative unspecific symptoms of mesotheliomas, misdiagnoses, and lack of precise targeted therapies call for a more critical assessment of this disease. In the present review, we categorize commonly identified genomic aberrations of mesotheliomas into their canonical pathways and discuss targeting these pathways in the context of tumor hypoxia, a hallmark of cancer known to render solid tumors more resistant to radiation and most chemo-therapy. We then explore the concept that the intrinsic hypoxic microenvironment of mesotheliomas can be Achilles’ heel for targeted, multimodal therapeutic intervention