Introduction Prediction of thunderstorm is one of the most difficult issues in weather forecasting. Deep convective clouds develop at small spatial and temporal dimensions about 1-10 km and 1-12 h. Various Thermodynamic parameters have been discovered over the past 40 years, according to data obtained by radiosounds. The capability of these indices in forecasting instability varies over time and location. The performance of instability indices obtained from radiosound to predict thunderstorm have been examined. by Schultz (1989), Lee and Passner (1993), Huntrieser et al. (1996). Haklander and Van Delden (2003) have also studies the accuracy of 32 instability indices in the Netherlands. They provided estimations for the optimal thresholds and relative forecast skills of all these thunderstorm predictors employing skill score parameters such as True Skill Statistic (TSS) and Heidke Skill Score (HSS). When comparing forecast skills in a dichotomous forecasting scheme, the lowest 100 hPa Lifted Index scores the best, although other versions of the Lifted Index have relatively good performance (Haklander and Van Delden, 2003, 273). Kunz (2007) studied the preconvective environment on days with ordinary, widespread, and severe thunderstorms in Southwest Germany. Various thermodynamic and kinetic parameters calculated from radiosoundings at 12UTC were verified against subsequent thunderstorm observations derived from SYNOP station data, radar data, and damage reports of a building insurance company. For the ordinary decision whether a thunderstorm day was expected or not, the best results were obtained by the original Lifted Index, the Showalter Index, and the Modified K- Index (Kunz, 2007, 327). Rasooli et al. (2007) studied the changes in the temporal and spatial distribution of thunderstorms in the Northwest of Iran and concluded that the likelihood of thunderstorms precipitation is higher in spring and summer. Therefore, we have selected the spring and summer seasons for this study. Due to the low number and sparse spatial distribution of radiosound network and the high cost of lunching, a prediction based only on radiosound network will suffer from data deficiency. Considering the fact that the Terra and Aqua satellites can cover a very broad area by passing over a region, using MODIS sensor data can improve lack of upper level station observations. MODIS Profiles have been used and verified in some studies. Chryoulakis et al. (2003) used 3 instability indices extracted from MODIS and radiosound for assessing atmospheric instability and have shown that the three satellite derived instability indices are well correlated with those derived from radiosound. Halimi et al. (2011) studied the verification of MODIS temperature and dew point temperature profiles versus radiosonde’s temperature profiles at Mehrabad station. In that study, the MODIS temperature profiles showed acceptable conformity with the radiosound’s temperature profiles. The whole Bias of 1.95 and RMSE 2.41°K for above 780 mbar level were obtained. Jafari (2012) compared 3 instability indices TT, L and K obtained from MODIS device with radiosound at Tabriz station. It was observed that the TT, L and K indices show good correlation coefficients of 0.50, 0.58 and 0.63 in spring and 0.77, 0.75 and 0.72 in summer, respectively. The aim of this study is to evaluate the performance of instability indices derived from vertical profiles of MODIS in predicting instability at Urmia Station. Methodology The instability indices of TT, L and K obtained from satellite have been compared with the 3-hour-daily synoptic reports in Urmia station. The World Meteorological Organization has defined some codes to determine the current and past weather conditions, marked by double digits (00-99). In this study, the codes 13, 14, 15, 17, 18, 19, 25, 26, 27, 29 and 80-99 related to thunderstorm activities are used. If any of these numbers is recorded at the station, the day is considered a thunderstorm day. Detecting the number of thunderstorm days in spring and summer 2008 from synoptic station reports, we selected the month May and July as the representatives of spring and summer. The Terra and Aqua satellite images were extracted from LAADS website during these two months. The MODIS atmospheric profile product (MOD-07) consists of several parameters: total ozone burden, atmospheric stability, temperature and moisture profiles, and atmospheric water vapor. All of these parameters are produced day and night for level 2 at 5*5 km pixel resolution when at least 9 FOVs are cloud free. With writing a program in IDL environment the desired pixel values have been extracted from the images. By comparing the instability indices derived from MODIS images and 3-hourly synoptic reporting, the validity of these results in forecasting the probability of occurrence of thunderstorms and weather instability was assessed. Results and discussion In this study up to 83 images are studied for month May, in which 14 images are related to the days that phenomenon of shower and storm was reported. For month July we examined 98 images in which 12 images were related to the stormy days. Examining the table of contingency the highest HSS rating is for LI with the score of 0.30. After LI, TT with 0.24 and K with 0.21 were in the next rating. The results of this study for the heist HSS are consistent with results of Haklander and Van delden (2003) and Kunz, (2007). In this way, the potential of thunderstorm based on instability indices are more depended on hidden instability like L and then on potential instability and at the end conditional instability. It can be inferred that using MODIS instability indices can be a good replacement of radisound observations. Conclusion In conclusion we have studied the potential of MODIS atmospheric profiles in predicting instability of the north west of Iran. By comparing the contingency tables for both spring and summer we have concluded that the better results and higher HSS scores goes for L (indicates hidden instability) instability index and then TT and K (indicating potential instability and conditional instability) indices.

This paper describes an investigation of combustion instability mechanism in premixed gas turbines. First, the preliminary concept of combustion instability is reviewed and then all types of frequency modes of combustion instability are studied. The results show that combustion instability is excited at first longitudinal mode; therefore the first mode or probably the second mode of longitudinal wave are the most important modes. Consequently, in this investigation only first longitudinal mode is considered. This simulation is based on equivalence ratio oscillations, which is an important mechanism for gas turbine combustion instability. The results are validated according to previons analytical and experimental results and show good agreements.

The purpose of this study was to predict marital instability based on the variables of emotional intelligence and spiritual intelligence. The research method was descriptive correlational and the statistical population consisted of all married Married female kindergarten trainer in district 3 of Tehran, that 93 person were selected by convenient sampling method, In order to measure the variables of the research, Bar-on Emotional intelligence questionnaire, king spiritual intelligence questionnaire (2008) and Edwards et al. (1987) marriage Instability index marital instability indices were used.Pearson correlation and regression analysis were used to analyze the data using SPSS software. The findings of the research showed that there is a significant and inverse relationship between dimensions of emotional intelligence and marital instability, and there is a significant and inverse relationship between the dimensions of spiritual intelligence and marital instability Also, the results of regression analysis showed that emotional intelligence and spiritual intelligence can predict marital instability. The findings of this research support the importance of emotional intelligence and spiritual intelligence variables in predicting marital instability, That is, high emotional intelligence and spiritual intelligence, the marital instability decreases.

In this paper, the role of effective factors on the instability of tunnels and underground excavations was explored through statistical analysis. To reach this goal, the effective factors (including 25 different factors) on the tunnel instability were recognized based on the deep literature survey and expert judgment. Then, a database of previous tunnel instabilities was established based on the type of tunnels and the main factor of instabilities. The effective factors were classified into six main groups and utilized for statistical analysis based on the relative frequency of tunnel instability. The results of this paper show that the geomechanical factors, design-investigation issues, and geological-geographic conditions of the site are the main three reasons for tunnel instability, where these main factors control more than 70% of civil-utility tunnels through all case studies. In addition, the design-investigation issues and geological-geographic conditions show the lowest and highest dependency on the tunnel utility, respectively. The “weak zones”, “inadequate redesign during construction”, and “the groundwater level and conditions” are the main three effective factors in tunnel instability, where the relative frequency of instability due to these factors reaches up to 40% for most of the case studies. Based on the main effective factors of instability, the freeway and highway tunnels show the highest consistency with all other utilities for tunnels in the statistical population. Therefore, freeway and highway tunnels can be considered as the most representative of overall utilities. The outcome of this paper can be applied to risk assessment of tunnel instabilities and technical management.

The polymorphic variants at codon 72 of the p53 gene, encoding proline or arginine at residue 72, produce marked changes in the p53 structure. From the evidence that the DNA mismatch repair system and p53 interact to maintain genomic integrity, we hypothesized that codon 72 variations may influence the prevalence of microsatellite instability (MSI), a feature of malignancies associated with mismatch repair deficiency in sporadic colorectal cancer. We investigated the frequency of MSI in three P53 codon 72 genotypes using genomic DNAs from 144 paraffin blocks of sporadic colorectal adenocarcinomas by testing the BAT-26 poly(A) marker. We used PCR-SSCP analysis to detect tumor sample MSI for the nonisotopic detection of deletions in the BAT- 26 poly (A) mononucleotide repeat. Associations between qualitative variables were evaluated using the χ2-test. Statistical significance level was set to p ≤ 0.05. MSI analysis revealed that 24.3% of the tumors (n=35) were MSI-positive and 75.7% (n=109) were MSI-negative. The frequency of microsatellite instability in the arginine/arginine, arginine/proline and proline/proline genotypes were 11 (16.9%), 22 (36.1%) and 2 (11.1%) respectively. A significant difference in distribution of MSI was found for the arginine/proline genotype compared with the grouped arginine/arginine and proline/proline genotypes (p=0.05). Our findings suggested that colorectal adenocarcinomas arising in individuals with the p53 codon 72 arginine/proline heterozygosity are more prone to microsatellite instability than those with other p53 genotypes. In our study, MSI was important in the carcinogenesis of sporadic colorectal cancer arising in pro/arg heterozygotes.

Space structures are economical and aesthetic in appearance. They provide a unique solution to cover large column free areas. Sports stadia, industrial buildings, exhibition halls, cinema theatres, swimming pools, airport hangars, conference halls, etc, can be economically covered with the use of space structures. Space grids are characterized as two-way or three-way, depending on whether the members intersecting at a node run in two or three directions. Three-way grids are very extremely strong and lead to a very uniform stress distribution. Barrel vault is one of the oldest architectural forms, used since antiquity. The popularity of barrel vaults derived partly from the economy of these structures, as all arches could be constructed as identical members. Braced barrel vaults are developable surfaces of zero Gauss curvature generated by the movement of a curve, known as the. directrix., over a generator straight line. The directrix may be a circular arc, an ellipse, a catenary, a parabola or a cycloid. Single-layer barrel vaults show a range of different instability modes, namely, member instability, node instability, line instability and overall instability, normally each occurring under different loading and boundary conditions. There are two important types of instability, namely: limit point instability and bifurcation point instability. In limit point instability, a structure with nonlinear un-stiffening characteristics loses its stability by a sudden buckling into a mode of deformation which is in accordance with the initial mode of deformation. However, in the bifurcation point instability, a structure with nonlinear softening characteristics may lose its stability by a sudden buckling into a mode of deformation which is quite distinct from the initial unstiffening mode. There are three types of bifurcation point instability, namely: asymmetric bifurcation, stablesymmetric bifurcation and unstable-symmetric bifurcation. However, in most cases, space structures show limit point instability and unstable-symmetric bifurcation point instability. In single-layer braced barrel vaults, the effect of geometric nonlinearity is very important. In fact, due to small angles between the members, deflections and member forces are large and thus significant changes in structural geometry occur. Also, in these structures the possibility of plasticity occurring in the members causes a reduction in their load carrying capacity. Plasticity can occur before the first limit point load in single-layer braced barrel vaults, so despite the fact that the main source of nonlinearity in these structures is geometric, the inclusion of plasticity in the analysis is necessary to safely predict their true collapse load and post-collapse behavior. Therefore, geometric and material nonlinearities should be considered in the analysis of these structures. In the present study, the stability of singlelayer barrel vaults with three-way triangular configuration is investigated by carrying out nonlinear collapse analysis using finite element method. The effects of different parameters, such as initial geometric imperfections, load on a single node, loads on some nodes, unsymmetrical load distribution with different intensities, length to span ratio, height to span ratio, boundary conditions and material yield stress are considered on the stability behavior of single-layer barrel vaults. According to static collapse analyses of studied models, three collapse mechanisms were determined as overall collapse, local collapse with snap-through and localcollapse without snap-through. In the case of local collapse with snap-through, it has been indicated that to evaluate realistic response of the structure, the static collapse analysis is not adequate by itself, and a dynamic snap-through analysis must be performed, as well.

In this paper, nonlinear simulation of viscous fingering instability of miscible displacement involving nanofluid is investigated. Using vorticity and stream functions and the spectral method governing equations are obtained. Due to the fractality of fluid-fluid interface in instability phenomena, by using box counting method, its fractal dimension is calculated in different parameters such as deposition rate, mobility ratio and diffusion rates. The results show that increasing the deposition rate reduces the complexity of finger patterns and the diffusion rate of nanofluid has no effect on complexity of finger patterns while increasing the diffusion rate of displaced fluid has significant effect on patterns and makes it more complicated. The fractal analysis also shows that the effect of mobility ratio depends on the deposition rate.  By considering deposition rate, although the mobility ratio has no effect on fractal dimension and effective time is constant and equal to 275, start time of instability is delayed by 25 units. It can be concluded that fractal analysis of viscous fingering phenomena can be considered as one of the instability characteristics.

The main purpose of this study is to study and zoning of geomorphological instabilities resulting from seismic earthquakes in Ilam and Kermanshah using Vickor multi-criteria decision making method. The region affected by this earthquake is very prone to various movements and geomorphological instabilities. The reasons for this are the existence of young Zagros folds along with the operation of their cutting faults, which have caused severe fractures in the region. To conduct this research, using topographic maps, geology, satellite images and field operations, geomorphological instabilities that were effective in aggravating earthquake damage were identified and positioned. The most important of these instabilities include landslides, rock falls and avalanches, currents, hilltop ruptures and landslides that lead to road blockages, destruction of residential houses, pollution of water and soil resources, destruction of agricultural lands, Gardens and ... has been. Then, using VIKOR multi-criteria decision making method, instabilities were zoned into 5 categories. In order to validate, the zoning map was adapted to the distribution map of seismic index geomorphological instabilities. The results showed that the two classes of high and very high instability and high risk class with a total area of ​​6558 square kilometers, ie more than 28% of the study area and among the factors affecting the occurrence of instability, factors Geology, distance from the fault and slope with 0.23, 0.22 and 0.15 points, respectively, have the greatest impact on creating instabilities in the region. The result of the adaptation of the zoning map to the distribution map of instabilities indicates the adaptation of most instabilities, including landslides, rock falls and subsidence with high risk classes.

In this paper, the static behavior, instability and buckling in porous micro plates under electrostatic field are investigated based on the modified couple stress theory and with regard to modeling, determining equations and solution methods. The plate is considered to be porous and the porosity distribution is considered to be non-uniform. The equations are obtained considering the distributed support load. By using the definition of dimensionless parameters such as load, voltage and length scale, the equations of motion become dimensionless. It can be seen that in the special case, by removing the dimensionless non-classical parameters, the equation of the classical plate under the electrostatic field is obtained. Galerkin mode summation and numerical methods are utilized to solve the static deformation equation and assess the pull-in instability voltages and buckling loads. Convergence analysis is done and the number of approximation functions and elements required for both methods are calculated and the compatibility of the results obtained from the two methods is examined. In the results section, the difference between classical and non-classical theories is examined and the effect of dimensionless parameters of length scale and porosity ratio on maximum displacement, pull-in instability voltages and buckling load is studied. The results show that the use of modified stress couple theory leads to a very large stiffness prediction compared to classical theory. This result highlights the necessity of using the modified couple stress couple theory for the micro-scale. It is observed that the length scale parameter plays the role of stiffening. The change of porosity ratios also shows that as this ratio increases, the displacement increases and the stable areas decrease. Variations in this ratio lead to uniform changes in buckling load and pull-in instability voltage, and linear relationships are obtained to calculate buckling load and pull-in instability voltage versus porosity ratio. Also, in small values of support load, it is shown that the relationship between the instability voltage and the compressive load of the support is linear, but in the buckling range, this relationship is not linear.