One of the new challenges in structural engineering is the mitigation of seismic hazards from structures using flexibility and energy dissipation approaches. This is in contrast with the typical seismic design methodologies in which strength and ductility resources of structural members are tapped to tackle earthquake demands. In this approach, adding to the flexibility of the structure should be in accordance with the energy dissipation potential in the system. In this case, earthquake demands for lateral strength in structures reduces, but energy dissipation devices are needed to subside the lateral deformation of such flexible structural systems.To meet the huge demand for energy dissipation potential in these structural systems, large scale damping devices are required. Such equipment, to mention a few, comes in the form of metallic, frictional, viscoelastic, memory shaped alloys and viscous DASHPOTs. Among the others, viscous DASHPOTs are considered the most favorite ones to use in large structural systems due to their sizable capacity and impartiality to ambient vibration and temperature loads. Moreover, since these devices are velocity dependent energy dissipaters, they are capable of reducing both deformation and acceleration responses of the structural systems more effectively.Viscous DASHPOTs are typically made from a metallic cylinder, a piston, a shaft, cylinder caps and elastomeric seals (to provide confinement on the liquid inside of the cylinder). The existence of elastomeric seals in configuration assembly of these devices is considered a weak point in mechanical design of such DASHPOTs considering maintenance issues. To address this problem, a contractible viscous DASHPOT was introduced earlier in which there was no need for elastomeric seals. In this work, a new version of this DASHPOT with variable damping constant have been tested for determination of its functionality and CHARACTERISTICS.Contractible viscous DASHPOTs are made from two flexible chambers that axially contract or expand to accommodate liquid movement between the two. In this mechanism all parts of the device are made of steel and there is no relative movement between cylinder caps and the main shaft. Therefore, there is no need for elastomeric seals to confine the liquid inside of cylinders at cylinder caps.The DASHPOT was designed for load capacity of and the maximum stroke of. In the test procedure, however, due to some limitations in the test setup, the attainable load was around 310 KN. The test results show stable hysteretic loops under sinusoidal excitations with the amplitude of in the frequency range of 0.1-0.25 Hz. The hysteresis loops resemble a viscous device with viscoelastic behavior that can be roughly represented by Kelvin model. As expected, damping constant of the DASHPOT reduces by an increase in excitation frequency. The capability of change in damping CHARACTERISTICS of the DASHPOT was embedded in the device. This ability was shown in the experiments where damping constant of the device became almost tripled during the test process by adjusting the embedded mechanism in the device.The contractible DASHPOT used in this study has shown an initial frictional behavior due to imperfection in its manufacturing process. Increase in the internal liquid pressure in the device expands this frictional behavior to about 10% of total capacity of the DASHPOT. The initial frictional force in the device can be easily improved to help the functionality of the DASHPOT.This DASHPOT has shown acceptable performances in all the experimental investigations carried out in the course of this study. Considering its simplicity and practicality (low maintenance costs), there would be a good chance for such devices to be used in large structures in near future.

Bistable composites have gained increased attention in the industry, especially in aerospace, due to their unique feature of shape-changing without any need for continuous energy. The advantage of using these structures is their ability to package in small size, whilst deploying in long lengths and high stiffness ratio along the length. This unique feature, along with the advantages of other fiber-reinforced composites such as high strength, lightweight, and high rigidity, has made them a good choice for applications such as deployable booms and antennas for satellites. In this paper, the bistability of shell structures at different timetemperature conditions is investigated. To explain the mechanical behavior of the Bistable Tape Springs (BiTSs) in different conditions, an analogous 2D-model consist of rigid linkages, elastic springs and viscous dampers is proposed. As a case study, four BiTSs are fabricated and subjected to a particular thermo-viscoelastic condition to verify all stability behaviors of the 2D link-spring-DASHPOT (LSD) model. It was also shown that the non-dimensional strain energy plot of the 2D-LSD model through the transition path is similar to the minimum strain energy path from the 3D classical-laminate-theory (CLT) shell model for a BiTS. The 2D-LSD model could simulate the elastic and viscoelastic behavior of the BiTS at three critical points of the minimum strain energy path with a negligible discrepancy. In addition, the results of the 2D-LSD model are in good agreement with the experimental results obtained from the four fabricated specimens in terms of bistability under the particular thermo-viscoelastic condition.

Improving participation in voluntary activities in Iran is important because increasing productivity among young people, given the country's young population, contributes to community sustainability. Therefore, a better understanding of volunteer motivation in Iranian youth is needed. The Volunteer Functions Inventory (VFI) for assessing volunteer motivations has good psychometric properties and is adapted to several languages, but no validated Iranian translation yet exists. The purpose of this study was to investigate the psychometric CHARACTERISTICS of voluntary functions inventory in members of Iranian Red Crescent Society. Sample size was 595 members of Youth Organization of Iranian Red Crescent Society from 31 provinces and 175 cities of Iran that were selected by multi-stage cluster sampling method and responded to voluntary functions inventory. Data were collected using a demographic sample and voluntary functions inventory (VFI). Confirmatory factor analysis using principal components method was used for data analysis. The results of the present study showed that the voluntary functions inventory had validity and reliability. Also, the factor structure showed that 29 items and 6 factors well assess people's attitudes to volunteering, and the structure of this inventory was well-fitted and confirmed all goodness of fit models. The present study provides the use of the Iranian translation of the Voluntary Functions Inventory (6 scales and 29 items) to assess volunteer motivation among young Iranian volunteers.

Background and Aim: Job enrichment is a method that has been used to increase employee satisfaction and work motivation. The Hackman and Oldham job CHARACTERISTICS model (1976) has served as the foundation for many job enrichment efforts. In particular, a considerable amount of research has been devoted to the study of the job CHARACTERISTICS-job satisfaction relations. Te purpose of this study was to statistically determine the relation between job CHARACTERISTICS and job satisfaction among employees of hospitals affiliated to Tehran University of Medical Sciences (TUMS) in 2007. Materials and Methods: This study was a cross-sectional one, including 6 TUMS-affiliated hospitals-Emam, Shariati, Baharlo, Ziaeian, Madaen and Azadi. The sample size was 400, consisting of 200 administrative employees (50%), 151 nurses (38%) and 49 physicians (12%). The random sampling and stratified proportional sampling methods were used to select the hospitals and interviewees, respectively. Two questionnaires were developed and used to identify job CHARACTERISTICS and job satisfaction: 1) job diagnostics surveys (JDS) and 2) Hertzberg's job satisfaction questionnaire. The reliability of the questionnaires was ascertained by test-retest using the Pearson correlation coefficient (r = 0.88). Linear-by-linear association and ordinal logistics regression analysis were used for analyzing the data gathered.Results:The relations between the Motivational Potential Score (MPS) and job CHARACTERISTICS (except for feedback) with job satisfaction were statistically significant (p<0.05). Task identity was the most effective determinant of job satisfaction. Conclusion: It appears that all the job CHARACTERISTICS (except feedback) are important determinants of job satisfaction of the hospital employees. Although the work environment is in need of restructuring, it is important to note, from a positive perspective, that the job CHARACTERISTICS discussed in this study are readily amenable to change job satisfaction at the organizational level.

Evaluating the cutting rate (CR) of stones is important in the cost estimation and the planning of the stone processing plants. This research used regression models to estimate the stones’ CR based on their physico-mechanical CHARACTERISTICS. Stone processing factories in Mahallat City (Markazi province, Iran) were visited, and the CR of diamond circular saws was recorded on six different travertine stones. Next, the stone block samples were collected from the quarries for laboratory tests. Stones’ porosity (n), uniaxial compressive strength (UCS), and Schmidt hammer hardness (SH) were determined in the laboratory as their physico-mechanical CHARACTERISTICS. Correlation relationships of CR with physico-mechanical CHARACTERISTICS were evaluated using simple and multiple regression analyses, and estimator models were developed. Results showed that multiple regression models are more reliable than simple regression for estimating the stones’ CR. The validity of the developed multiple regression models was verified with the published data of one researcher. The findings indicated that these models are accurate enough for estimating the CR of stones. Consequently, the multiple regression models provide practical advantages for estimating the CR and save time and cost during the planning and design of the stone processing factories.

Viscous dampers are parts of energy dissipation devices which have received considerable attention in modern seismic design approaches. One of the most important challenges of them is fluid seals which needs maintenance. Considering technologies in Iran and idea of removing seals and so the need of maintenance, a DASHPOT using some parts of expansion joints was designed. The manufactured DASHPOT is a practical one, which has appropriate stroke, 65 mm, and efficient capacity, 224 kN, and also displays nonlinear damping behavior.Constitutive law CHARACTERISTICS of the DASHPOT using Kelvin Model is determined, and also Equivalent Linear Damping is calculated.

The aim of this study was to investigate the effect of using portulaca oleracea as a source of plant antioxidants for feeding fattening male lambs, on carcass traits, meat quality, and oxidative stability. Twenty-one male lambs with an average weight of 24±1.5 kg and 150±15 days old were fed with one of the experimental rations included a diet without portulaca oleracea as control, a diet containing 7.5%, and a diet containing 15% portulaca oleracea, for 84 days. The muscle (Longissimus dorsi) samplewas used to determine pH, chemical composition, colorimetric properties, and oxidative stability of meat. Meat lipid oxidation was determined after 1, 7, and 30 days of refrigerated storage using thiobarbituric acid (TBARS). The use of portulaca oleracea in diets improved meat color CHARACTERISTICS such as L, chroma, and Hue. The highest ash concentration and the lowest meat moisture were observed in the treatment of 15% portulaca oleracea (P<0.05). Meat pH was the lowest in the first hour after slaughter but did not differ at 24 h. Compared to the control, in both treatment groups feeding the lambs with portulaca significantly reduced the concentration of Malondialdehyde in the meat of the lambs and increased the meat oxidative stability (P<0.05). The results of this experiment showed that feeding portulaca oleracea by improving properties such as color and increasing the meat oxidative stability improves meat quality, which may have lead to an increase in its nutritional value in terms of human health.

The aim of the current research was to identify the CHARACTERISTICS of the four elements in order to provide a problem-oriented curriculum model in the elementary school mathematics course. There were 19 participants and the sampling was done purposefully. The data collection tools are semi-structured interviews and questionnaires. The problem-oriented curriculum template was designed using the CHARACTERISTICS of the elements and with the method of qualitative content analysis in the elementary school mathematics course. The identified features were validated by fuzzy Delphi method and Shannon's entropy method was used for data processing. Based on the results of the analysis, 7 main categories including the CHARACTERISTICS of goals at three levels of cognitive, attitudinal, skill, content, evaluation, teaching-learning strategy and 46 sub-categories were identified.                                                                                                                                                                In the fuzzy Delphi section, all features were confirmed by obtaining a de-fuzzified value greater than 0.7. The results of Shannon's entropy determined that the CHARACTERISTICS of starting teaching with a challenging question, creating a suitable educational environment, continuously monitoring the quality of learning strategies and communicating with students' talents have attracted the most attention and obtained the highest ranks and had a higher importance factor than other CHARACTERISTICS

In this study, chemical compositions of black seed meals samples were determined. 18 male weaning Zandi lambs with an average body weight of 23.5 ±1.5 kg were used in a completely randomized design in three groups of six in individual pens. Experimental treatments were: 1) control (basal diet with 12% soybean meal and without black seed meal), 2) diet containing 6% soybean meal and 9% black seed meal and 3) diet containing 18% black seed meal and without soybean meal. The concentration of dry matter, crude protein, crude fat, NDF, ADF, ADIN, and crude ash of black seed meal samples were 97.53±0.58, 31.26±0.99, 15.16 ± 0.61, 25.95 ± 1.34, 14.2±0.80, 0.69±0.04 and 5.07 ± 0.24, respectively. Replacement of soybean meal with black seed meal in the diet of experimental lambs had no effect on final body weight, daily weight gain, feed conversion ratio, dry matter intake, dressing percentage, tail and total body fat deposition. Albumin and total protein were higher for lambs fed by diet containing 18 % black seed meal compared to other treatments (P <0.05). However, the concentration of blood triglyceride, cholesterol and urea nitrogen were not differed between experimental groups. The digestibility of dry matter, organic matter, crude fat and protein were not affect by feeding of experimental diets. It seems that black seed meal can be used in the diet of fattening lambs up to 18% without adverse effect on performance and nutrients digestibility of growing lambs.

In this paper, static indentation and low velocity impact responses of a fully backed composite sandwich plate subjected to a rigid flat-ended cylindrical indenter/impactor are analytically investigated. The analysis is nonlinear due to nonlinear strain-displacement relation. In contrast to the existed analytical models for the indentation of composite sandwich plates, the stacking sequence of the face sheets can be completely arbitrary in the present model. Furthermore, the effects of the initial in-plane normal and shear forces on the edges of the sandwich plate are also considered. Based on these modifications, an improved contact law (contact force – indentation relation) is derived. The low velocity impact analysis of the problem is performed using a discrete system of spring-mass-DASHPOT model. The CHARACTERISTICS of the equivalent spring and DASHPOT are identified from the derived contact law and by incorporating the effect of the dynamic material properties of the sandwich plate. Analytical predictions of the load-indentation response as well as the impact force history are compared well with the experimental results in the literature. The effects of various parameters on both indentation and impact responses of the sandwich plates are qualitatively and quantitatively investigated.