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匹配条件: “M Rahimi” ,找到相关结果约400653条。
Delocalization of elastic waves in disorder harmonic chain with random distribution of force constants
M. Rahimi,F. Shahbazi
Iranian Journal of Physics Research , 2007,
Abstract: Using inverse participation ratio and level statistics analysis, we investigate the localization of the natural modes of a disordered harmonic chain in which the force constants are distributed randomly without correlation as well as with long-range power-law (c ( l ) ~ l-y ) correlation. We find that for a specific value of correlation exponent the localized modes turn to be extended.
Effects of Different Protein and Energy Contents of the Diet on Growth Performance and Hormonal Parameters in Two Commercial Broiler Strains
G. Rahimi,M. Hassanzadeh
International Journal of Poultry Science , 2007,
Abstract: The present study was carried out to investigate the influence of energy and protein contents of the diet on growth performance and to evaluate further interactions of dietary manipulation and genotype on endocrine parameters in broiler chickens. 1200 day-old male and female broiler chicks from 2 commercial broiler strains (Hybro and Ross) were fed ad libitum from day 1 onwards by 4 different diets either with a high or low energy combined with a high or low crude protein content. Body weight and feed intake were measured weekly. Venous blood samples were taken (10 birds/sex /line/diet group) weekly from day 14 on, for plasma Growth Hormone (GH), Triiodotyronine (T3) and Thyroxin (T4) content. Relative growth rate was higher in broiler chickens which fed the low energy diet compared to high energy diet during the first week of age, while from week 1 on, a reverse effect of energy on relative growth rate was found. The effect of energy and protein on feed intake was significant (p<0.05), while no interaction between energy and protein was found. Within high energy diet, birds fed low protein diet showed a tendency for higher T3 levels, while on low energy diet, broiler chicks fed high protein level showed a tendency for higher plasma T3 concentrations, probably explaining the presence of a significant energy×protein interaction. Protein content of the diet, significantly (p<0.05) affected plasma T4 levels while energy content had no effect. The higher GH as well as T3 levels in the younger chicks may be an indicator of higher requirement of these hormones for protein synthesis during the fast growth phase. It can be concluded that higher protein content of the feed could result in lower T3, higher T4 and higher plasma GH levels. Possible causal mechanisms underlying this phenomenon are discussed.
Effects of Shaking Amplitude and Frequency on Nut and Cluster Detachment of Two Varieties of Pistachio
M. Loghavi,H. Rahimi
Journal of Science and Technology of Agriculture and Natural Resources , 2007,
Abstract: A 4x4 factorial experiment with a completely randomized design with three replications was conducted separately on two major pistachio varieties, Ohady and Kaleghoochy, to investigate the effects of shaking amplitude and frequency on pistachio nut and cluster detachment. Four levels of shaking frequencies used for Ohady were 5, 7.5, 10 and 12.5 Hz, while those of Kaleghoochy were 7.5, 10, 12.5 and 15 Hz. Four levels of shaking amplitude for Ohady were 20, 40, 60 and 80 mm, while those of the Kaleghoochy were 40, 60, 80 and 100 mm. Analysis of variance and mean comparison showed that the effects of shaking amplitude and frequency on pistachio nut and cluster detachment were significant on both varieties. It was found that in Ohady, at frequency of 12.5 Hz and amplitude of 80 mm, the maximum effective nut detachment occurred. But considering the need to limit both yield loss and limb damage to 5% and minimizing the power requirement of the limb shaker, applying shaking amplitude of 60 mm and frequency of 10 Hz, which detaches 95% of the nuts, is considered as the most suitable combination of shaking amplitude and frequency. Also, at amplitude of 80 mm and frequency of 12.5 Hz, the highest percentage of cluster detachment occurred. Here again, by considering limb damage and power requirement, applying shaking frequency of 12.5 Hz at 60 mm amplitude with 69% cluster detachment was selected as the most suitable combination. In Kaleghoochi, at amplitude of 100 mm and frequency of 15 Hz, nut detachment was 100%, while the need to limit limb damage and power consumption, the combination of 60 mm amplitude and 15 Hz frequency with 97.2% nut detachment was selected as the most suitable one. For cluster harvesting of Kaleghoochy, shaking amplitudes of 60 and 40 mm and frequency of 12.5 Hz with cluster detachment of 75 and 69 percent, respectively were selected as the most suitable ones. The average ratio of tensile force required for removing pistachio nut to its weight (F/W), and the ratio of tensile force required for removing pistachio cluster to its weight (V/W), which could be considered as an index of ease of detachment, were measured 6.2 and 37 for Ohady and 9 and 37.8 for Kaleghoochy, respectively. Finally, we may conclude that by applying the suitable combination of shaking amplitude and frequency, shake harvesting of pistachio could be practiced successfully.
Evaluation of Different Grouping Methods of Rapeseed Genotypes Using Fisher’s Linear Discrimination Function Analysis
B Rabiei,M Rahimi
Journal of Science and Technology of Agriculture and Natural Resources , 2009,
Abstract: Discrimination function analysis is a method of multivariate analysis that can be used for determination of validity in cluster analysis. In this study, Fisher’s linear discrimination function analysis was used to evaluate the results from different methods of cluster analysis (i.e. different distance criteria, different cluster procedures, standardized and un-standardized data). Furthermore, Hotelling T2, CCC plot and multivariate analysis of variance were used to support the results. To achieve the goals, 8 rapeseed genotypes were planted in a randomized complete block design with three replications in Rice Research Institute of Iran, Rasht, durin 2005-2006, and 14 characteristics were measured. Analysis of variance based on the randomized complete block design showed significant differences between genotypes for all the studied traits. Comparison of means between genotypes indicated that the genotype Hyola401 for grain yield and most of the measured characteristics was better than the other genotypes. Evaluation of phenotypic and genotypic coefficient of variations showed that most of the traits had high variability in the population. Discrimination function analysis showed that the Euclidean distance criterion was better than others and a desirable clustering was obtained by this criterion. Also, all of the data standardization methods produced similar clusters and were better than un-standardized data. Based on evaluation of dendrograms derived from different methods of cluster analysis determined that the UPGMA, complete linkage and Ward’s minimum variance methods were better than the other methods, and grouped the genotypes into three clusters. Fisher’s linear discrimination function analysis showed that UPGMA and Ward's minimum variance methods with clustering validity of 87.5 percent, was more suitable than other cluster analysis methods; however, discrimination analysis grouped genotypes into two clusters. Tests of Hotelling T2, CCC plot and multivariate analysis of variance supported the results from the discrimination function analysis. It seems that the UPGMA and Ward's minimum variance procedures based on Euclidean distance criterion of standardized data function better in grouping genotypes, yet, the use of discrimination function analysis is recommended to confirm the results and determine the actual groups.
The Instanton Solution of Forced Burgers Equation in Polyakov's Approach
M. R. Rahimi Tabar
Physics , 1997,
Abstract: We calculate the coefficients of the operator product expansion (OPE), in Polyakov's approach for Burgers turbulence. We show that the OPE has to be generalized and it is shown that the extra term gives us the instanton solution (shock solution) of Burgers equation. We consider the effect of the new-term in the OPE, on the right and left-tail of probability distribution function (PDF). It is shown that the left-tail of PDF, where is dominated by the well-separated shocks behaves as $ W(u)\sim u^{-7/2}$. Finally we calculate the assymptotic behaviour of the N-point generating function of the velocity field, using the new OPE.
Quenched Averaged Correlation Functions of the Random Magnets
M. Reza Rahimi Tabar
Physics , 2000, DOI: 10.1016/S0550-3213(00)00474-0
Abstract: It is shown that the ratios of the quenched averaged three and four-point correlation functions of the local energy density operator to the connected ones in the random-bond Ising model approach asymptotically to some $universal$ functions. We derive the explicit expressions of these universal functions. Moreover it is shown that the individual logarithmic operators have not any contribution to the connected correlation functions of the disordered Ising model.
Disordered Systems and Logarithmic Conformal Field Theory
M. Reza Rahimi Tabar
Physics , 2001, DOI: 10.1142/S0217751X03016902
Abstract: We review a recent development in theoretical understanding of the quenched averaged correlation functions of disordered systems and the logarithmic conformal field theory (LCFT) in d-dimensions. The logarithmic conformal field theory is the generalization of the conformal field theory when the dilatation operator is not diagonal and has the Jordan form. It is discussed that at the random fixed point the disordered systems such as random-bond Ising model, Polymer chain, etc. are described by LCFT and their correlation functions have logarithmic singularities. As an example we will discuss in detail the application of LCFT to the problem of random-bond Ising model in $ 2 \leq d \leq 4$.
The -Zero-Divisor Hypergraph of a Commutative Ring
Ch. Eslahchi,A. M. Rahimi
International Journal of Mathematics and Mathematical Sciences , 2007, DOI: 10.1155/2007/50875
Abstract: The concept of the zero-divisor graph of a commutative ring has been studied by many authors, and the k-zero-divisor hypergraph of a commutative ring is a nice abstraction of this concept. Though some of the proofs in this paper are long and detailed, any reader familiar with zero-divisors will be able to read through the exposition and find many of the results quite interesting. Let R be a commutative ring and k an integer strictly larger than 2. A k-uniform hypergraph Hk(R) with the vertex set Z(R,k), the set of all k-zero-divisors in R, is associated to R, where each k-subset of Z(R,k) that satisfies the k-zero-divisor condition is an edge in Hk(R). It is shown that if R has two prime ideals P1 and P2 with zero their only common point, then Hk(R) is a bipartite (2-colorable) hypergraph with partition sets P1−Z′ and P2−Z′, where Z′ is the set of all zero divisors of R which are not k-zero-divisors in R . If R has a nonzero nilpotent element, then a lower bound for the clique number of H3(R) is found. Also, we have shown that H3(R) is connected with diameter at most 4 whenever x2≠0 for all 3-zero-divisors x of R. Finally, it is shown that for any finite nonlocal ring R, the hypergraph H3(R) is complete if and only if R is isomorphic to Z2×Z2×Z2.
Estimating mean arterial pressure during invasive monitoring using manometer
Gholam Alemohammad M,Rahimi E
Tehran University Medical Journal , 2009,
Abstract: "nBackground: Direct monitoring of arterial pressure using a transducer system is not affordable in most operating rooms and ICU wards in Iran. It is, however, possible to use an aneroid manometer instead, but it is not standardized yet, nor studied enough; and its measurements may not be interpretable. "nMethods: To study the correlation of the arterial pressure readings between a manometer and a transducer system, systolic and diastolic arterial pressure was measured 105 times using both systems via arterial cannulation in seven patients during surgery. Mean arterial pressure was directly recorded in the transducer system, while it was calculated in the manometer system. In the manometer system, the extension tube was filled with saline halfway from the patient and the other empty end was connected to a manometer. The transducer and the air-fluid interface in the extension tube were positioned at same level. Correlation of the arterial pressures between the systems was tested using linear regression and Pearson correlation. "nResults: Mean arterial pressure differed by 2 (1-3) mmHg [mean (CI 95%)] between the systems, however, pulse pressure was lower in the manometer system by 37 (33-41) mmHg. The mean arterial pressure in the transducer system (MAPT) correlated well and linearly with the systolic arterial pressure in the manometer system (SAPM) by R=0.966. Therefore, MAPT can be regarded as a function of SAPM through the following formula: MAPT = (1.03 ′ SAPM) - 7.34. "nConclusion: The mean arterial pressure in the transducer system can be reliably estimated by monitoring the systolic arterial pressure in the manometer system.
Prioritization of Eco-tourism Attractions (The target villages of Charmahal O Bakhtiar province)
D. Rahimi,M. Ranjbar Dashtestani
Regional and Urban Studies and Research , 2012,
Abstract: Extended abstract1-IntroductionIn today’s world tourism is one of the essential revenue generating industries that serves as a means for cultural exchange among nation as well. Rural-tourism is a branch of tourism that is limited to the rural environment with respect to the culture and traditional customs that include their hand-craft, behavior, hospitality, green-tours, farm-tours, hunting, their cooking manners etc. Any country that intends to attract tourists in this field should be equipped with the following two characteristics: the potential that is the natural resources and the ability to provide services and facilities for rural-tourism that is the accommodation.2- Theoretical basesThis idea was first established during the 19th century in the western civilization when due to industrialization and urban-dwelling, transportation and welfare; people had more leisure time to visit rural areas in vast numbers.In the 20 year forecast program of development in the realm of tourism a national approach is adopted to promote the deprived regions’ potentials through manipulation of their natural/rural capacities and abilities. In order to finance the fundamental aspects of such programs, the authorities would face numerous problems.One of the measures that could overcome these problems to a certain degree is to prioritize the villages in a province based on their potentials then categorizes them as the village-tourism centers. For this purpose, an attempt is made to prioritize the potential villages by applying AHP, which is to validate them for investment, which will include all that is needed for Village Tourism. This issue has been of concern in different countries where putting the available natural resources at the National Tourist Industry’s services would be beneficial.- The study zoneCharmahal o Bakhtiar is a province with an area of 16,532 Km2. The geographic and demographic features of this province are presented in Table 1: RowTarget villageTourist attractionClosest cityClosest townshipClimate1HoreHistoric NaturalShahrekordSamanModerate2Yase chahNaturalShahrekordSamanModerate3ChalvanNaturalShahrekordSamanModerate4SavadjanNaturalShahrekordSamanModerate5Dastgerd ImamzadehHistoricKiarShalumzarMediterranean6DezakHistoricKiarShalumzarMediterranean7DimeNaturalKohrangCholgerdCold & Humid8Sheikh AlikhanNaturalKohrangCholgerdCold & Humid9Sar Agha SeyedNaturalKohrangCholgerdCold & Humid10AvreganNaturalBoroojenBoldajiMediterranean11DehcheshmeNaturalFarsanFarsanMediterranean12AtishgahNaturalLordeganFarsanHot & Humid - MethodologyWith respect to the componen

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