276 research outputs found
Tunability of terahertz random lasers with temperature based on superconducting materials
We theoretically demonstrate the tunabiltiy of terahertz random lasers composed of high temperature superconductorYBCO and ruby layers as active medium. The considered system is a one-dimensional disordered medium made of ruby grain and YBCO. Finite-difference time domain method is used to calculate the emission spectrum and spatial distribution of electric field at different temperatures. Our numerical results reveal that the superconductor based random lasers exhibit large temperature tunability in the terahertz domain. The emission spectrum is significantly temperature dependent, the number of lasing modes and their intensities increase with decreasing temperature. Also, we make some discussion to explain the reason for the observed tunability and the effect of temperature variation on the spatial distribution of the electric field in the disordered active medium
Damage detection in concrete gravity dams using signal processing algorithms based on earthquake vibrations
In structural engineering, damage detection in concrete gravity dams (CGDS) is a practical problem. Dam destruction can have severe financial consequences and may even lead to fatalities. Therefore, structural health monitoring in advance is crucial. In this regard, a well-known CGD, namely the Pine Flat Dam, has been chosen for the Finite Element Modeling. In this paper, damage is induced in the dam neck through elasticity modulus reduction by 40Â % and 80Â %. In addition, after applying Northridge earthquake, the acceleration in structure nodes for intact and damaged cases are recorded in vector formats. Using various methods, such as Discrete-time Fourier Transform (DTFT), Wavelet transform and Wiener transform, the differences between these two signals are investigated. The standard deviation (S.D.) of variations is chosen as the performance metric and is applied to the signal amplitude between intact and damage observations/signals. The reason why several signal processing algorithms are used is finding an approach which shows more clearly the differences caused by the destruction. This is evaluated via S.D. values for different algorithms. The results confirm the superiority of DTFT over other given algorithms. DTFT has a negligible outperformance (approximately zero dB) with respect to the Wavelet transform in both the crest and the lower nodes of the dam. This rate for DTFT and Wavelet is 10dB higher than that of Wiener and 35Â dB in comparison with the simple amplitude difference. Moreover, the detection thresholds for the given methods are compared, and it is verified that the DTFT and Wavelet indicate the best performance
Designing Alternative Housing in an Old Context: Zargandeparsh, Tehran
Today, poor performance in old residential contexts in terms of memorable visual elements reduce the residents’ sense of belonging. The study used a combination of qualitative and quantitative research methods. To meet the needs of residents, a questionnaire was distributed among twenty-five experts. Data analysis was performed using fuzzy logic to calculate the weight of each criterion of hierarchical fuzzy (FAHP). According to the findings, the largest weight belonged to social interaction (0.288), physical (0.205) and dependence (0.179). The results showed that social interaction is imperative in increasing the residents’ sense of attachment.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies, Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Keywords: Housing; old texture; place; sense of attachment
The Qualitative Interrelation between Open Spaces and Living Standards in a Residential Complex
From the early 50s onwards the major Iranian cities were subject to a massive immigration. The immediate solution to this crisis was residential complex in the less populated areas. After few decades of accommodating a large number of new citizens in these residential complexes, while having a limited open space, created physical, functional, semantic, environmental, and social problems. Today, the new challenge that confronted the designers and architectures of this field is therefore how to improve the quality of both open spaces and the living condition of the inhabitances and at the same time being able to compete in the housing market with budgetary restrictions on their expenditures.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies, Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Keywords: Residential complex open space; open space factors; FAN
Investigation of the effective factors on branding in cosmetic and hygienic products (Case study: Ladies consuming cosmetic and hygienic products with local brands)
Despite the long history of brands, this concept has been considered in marketing literature for a long time such that it has attracted many experts' attention to this field as one of the most important concepts of modern marketing literature. This concept has become so important that wherever loyalty is mentioned, brand is undoubtedly considered too. This research aims to investigate the effect of marketing mixture (7Ps) on making brands of local hygienic and cosmetic products whose statistical society is ladies consuming hygienic and cosmetic products in Mashhad. The sample under analysis of this research consists of 381 people. It was identified after the analysis of their data using SPSS software and testing the research's assumptions that marketing mixture's factors are effective on making brands. In addition, the severity of the effect of each factor was identified
Investigation of the effective factors on branding in cosmetic and hygienic products (Case study: Ladies consuming cosmetic and hygienic products with local brands)
Despite the long history of brands, this concept has been considered in marketing literature for a long time such that it has attracted many experts' attention to this field as one of the most important concepts of modern marketing literature. This concept has become so important that wherever loyalty is mentioned, brand is undoubtedly considered too. This research aims to investigate the effect of marketing mixture (7Ps) on making brands of local hygienic and cosmetic products whose statistical society is ladies consuming hygienic and cosmetic products in Mashhad. The sample under analysis of this research consists of 381 people. It was identified after the analysis of their data using SPSS software and testing the research's assumptions that marketing mixture's factors are effective on making brands. In addition, the severity of the effect of each factor was identified
Interpreting biomass and catch per unit area (CPUA) to assess the status of demersal fishes in Oman Sea
This study aimed to assess the biomass and catch per unit area (CPUA) of demersal fish resources in the northern part of the Oman Sea based on trawl survey. The study area was stratified into five stratum (I, II, III, IV and V) covering the depth layers of 10-20, 20-30, 30-50 and 50-100 m. A total number of 68 stations were monitored during the study period. The highest values of biomass were belong to stratum V and IV in the east coast of the Oman Sea and the highest species biomass was belong to batoid fishes (8054.4 tons). The lowest CPUA was recorded in the central region of the study area (stratum III, approximately 8212 kg/nm2) and the highest CPUA was on both sides of the study area (the east and west coast). Moreover, the highest CPUA (2031 kg/nm2) was observed in 20-30 m depth layer. The results showed the changes in biomass and CPUA based on different depths and the most abundant species groups were Trichiurus lepturus (50-100 meter), Sphyraena jello (30-50 meters), Caranx ignobilis (20-30 meters), and Pomadasys kaakan (10-20 meters)
Benthic community structure in the Gorgan Bay (Southeast of the Caspian Sea, Iran): Correlation to water physiochemical factors and heavy metal concentration of sediment
Macrobentos frequency and biomass was investigated in the Gorgan Bay in 2011. Five sampling sites were chosen to collect benthos and sediment from the Bay using a Van Veen grab sampler. Samples were collected seasonally. Macrobenthos were indentified and their biomass was recorded. Sediment heavy metals concentration were measured using Atomic Absorption Spectroscopy. A total of 11 families belonging to three phyla of invertebrates were found. The phyla were Annelids (Nereidae, Naididae, Ampharetidae, Lumbriculidae, Tubificidae and Amphiporidae), Arthropods (Pontogammaridae, Balanidae and Chironomidae) and Mollusks (Cardiidae and Scrobicularidae). Lumbriculidae (413 individuals m-2, corresponding to 18.7%) and Cardiidae (55.2 g m-2, corresponding to 82.4%) had the highest frequency and biomass, respectively. Annelids with an average of 1557 individuals m-2 was the most frequent groups, while, mollusks with the average of 141 g per m2 had the highest biomass. Results showed that macrobenthos frequency in summer was significantly higher than those of the other seasons, however, in the case of biomass, there was a significantly higher biomass in the spring than the other seasons. The maximum metal concentration was related to Zn and Pb, whereas, Cr and Cd had the lowest values. There was no significant difference in Zn and Cr concentrations among the sampling seasons. Pb concentration in winter was significantly lower than the other seasons, whereas, Cd concentrations in the spring and summer were significantly lower than the autumn and winter. There were some correlations between benthos frequency and water physiochemical characteristics and sediment heavy metal levels. This study indicated that benthic fauna of the Gorgan Bay and the Caspian Sea are not similar. Also, results showed that benthic fauna communities are affected by sediment heavy metal concentrations and water physiochemical characteristics, however, different benthos groups show unsimilar relationship with heavy metal concentration
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