---

Language is a medium of communication and the important goal of conveying a message is made possible through its channel. Modern life style has imposed some new diverse functions on this device. Modern written Persian alongside other languages embraces different varieties that include media and formal correspondence registers. These particular versions demand precise writing that follow high standards and norms of Persian. Furthermore, due to their wide use, these types can be considered standard language learning tools for the addresses. Consequently, taking benefit of accurate standard patterns in the use of these versions leads to boosting the use of standard Persian among the users and addresses alike. Formal correspondence is a type of register that is used to convey messages through letters, circulars, notices, and other similar platforms. Despite the fact that formal correspondence enjoys its own particular features including specific terminology, it is expected to follow standard Persian in many aspects of wording and structure. Research findings indicate otherwise. In this study, 152 letters and circulars all in the domain of formal correspondence in the Ministry of Science, Research, and Technology that mounted to a corpus of 1000 sentences were scrutinized focusing on the analysis of  nonstandard patterns through a three-level editing process including technical, linguistic, and rhetorical aspects. The standard forms were provided along with some suggestions for improving the quality of formal correspondence. Based on the findings of this research endeavor, the order of highest frequency for nonstandard uses were in the linguistic, technical, and rhetorical domains respectively. This implies the need for a more focused approach on these features in education and research areas.

---

The purpose of this study is to explain the ability of the simulation methodology to consider uncertainty of the multi criteria decisions making. The rank order of decision alternatives depends on two types of uncertainty:(1) uncertainty associated with the decision making judgment regarding each element of decision matrix described by distribution function, and (2) uncertainty regarding the future characteristics of the decision making environment described by a set of scenarios. Scenario is description of the decision making environment into some separate situations . Researchers concentrate on this type of uncertainty less than other types. Both types of uncertainty are capable to opposite the rank of alternatives and decline the certainty of decision maker to the rank order of alternatives. In The present research, a simulation approach for handling both types of related uncertainty was described. The final conclusions showed that when uncertainty associated with the decision making judgment regarding each element of decision matrix increases, the probability of rank reversion and rank uncertainty increases too. Under these situations, the final ranking of the alternatives is probabilistic.

---

The purpose of this study is to explain the ability of the computer simulation methodology to improve productivity of a production system. At the beginning, it demonstrates how simulation can be employed in productivity analysis. In this regard, a case study approach was used and the proposal methodology was implemented to represent the simulation capability to enhance the productivity in the case study. An explanation of the existing system was presented and the corresponding model called AS-IS model was designed, then the model was runned and the output was analyzed. The results of the study showed the bottlenecks and performance measures of the existing system and the initiated two models according to the simulation output, called TO-BE models. The results obtained from the simulation experiment showed the performance measure in the TO-BE models. The manager of the company, has selected the TO-BE2 model as the best alternative based on the economical and others measure.

---

In this research We introduce a new distribution center (DC) location model that incorporates working inventory and safety stock inventory costs at the distribution centers. In addition, the model incorporates transport costs from the suppliers to the DCs that explicitly reflect economies of scale through the use of a fixed cost term. The model was formulated as a non-linear integer-programming problem. The algorithms were tested on the problems with 15 retailers and 5 distribution centers. We uses SOLVER of Excel for modeling, solution and sensitivity analysis of the results. Finally, the sensitivity of the results to changes in key parameters including the fixed cost of placing orders was discussed. Significant reductions in these costs might be expected from e-commerce technologies. The model suggests that as these costs decrease, it is optimal to locate additional facilities.

---

One of the most important permanence factors in today’s competition environment is decreasing of the cost of the products. Selecting the appropriate suppliers can significantly reduce the purchasing cost and increase organization competitiveness. It is due to the fact that in most industries, the cost of raw material and component parts includes the main cost of a product. The aim of this paper was to introduce a fuzzy decision making approach for supplier selection problems in supply chain. Most of such decisions are unstructured and many of the performance criteria such as quality, cost, flexibility and delivery time to determine the best supplier should be considered. In this paper, verbal variables were used for evaluation and determination of the performance of supplier under each criterion and determination of the weight of the criteria. Verbal variables were described by means of the triangular and trapezoid fuzzy numbers. Furthermore, the priority and the rank of suppliers by fuzzy multi-criteria decision making were determined. Finally, an example was presented to the process of decision making.

---

In this research, the plunging motion of an airfoil by a numerical method based on finite volume in different Reynolds numbers is simulated and the thickness effect, amplitude and reduced frequency on the aerodynamic coefficients are investigated. In this process, SIMPLEC algorithm, implicit solver, high order scheme and dynamic mesh method is used in unsteady simulation and the flow is supposed viscous, incompressible and laminar. Simulations are in three Reynolds 1000, 11000 and 50000, respectively, in accordance with the flight of the insects, small birds and pigeons are done in two amplitudes and three reduced frequencies. The simulation results are compared with published data to confirm the validity of research. This comparison shows comprisable agreement. Pressure distribution and Vortex shedding around airfoils show that the thickness of the airfoils delays vortex shedding and changes time-averaged thrust coefficient. Reduced frequency and amplitude of oscillation are two important parameters in this simulation, but the reduce frequency is more effective than amplitude. The response surface methodology (RSM) was used to optimize the plunging airfoil. Optimization shows that airfoil with 0.29% thickness, 3.08 reduced frequency and 0.5 dimensionless oscillating amplitude produce maximum trust coefficient.

---

The purpose of preventive maintenance management is to perform a series of tasks that prevents or minimizes production breakdowns and improves the reliability of production facilities. The inspection, repair, and replacement of production equipment are tasks that are central to preventive maintenance management. An important objective of preventive maintenance management is to minimize the downtime of production facilities. In order to accomplish this objective, management personnel has to efficiently allocate resources and determine an effective maintenance schedule. Mathematical models have been developed to solve the preventive maintenance-scheduling problem of assigning skilled personnel to work with tasks that require a set of corresponding skills. However, there are several limitations in the prior work in this area of research. The craft-combination problem has not been solved because the craft-combinations is assumed to be given. The craft-combination problem concerns the computation of all combinations of assigning multi-skilled workers to accomplishing a particular task. In fact, determining craft-combinations is difficult because of the exponential number of craft-combinations that are possible. This research provides an integrated solution for the preventive maintenance-scheduling problem with multi-skilled workforce constraints. Two novel preventive maintenance-scheduling model is formulated to automatically produce the optimal solution and craft combination.

---

In this research, a new numerical approach which is capable of modifying the shape of three dimensional massive bodies like tall buildings respect to aerodynamic loads is presented; therefore, the aerodynamic forces are improved; consequently, the comfortability of the buildings is increased. This method is drawn into 2 parts; a numerical simulation of fluid flow and Adjoint method. As a result of it, some modifications are performed in the different parts of the building. In the primarily step, the building shape and its setting position are investigated in different flow conditions as effective parameters on the aerodynamic of buildings. Subsequently, the sensitivity level of each variable is studied on aerodynamic loads. The results illustrate that the building pattern has the highest impressments (76%) on the excited forces. In the next step, the amount of sensitivity of the fluid flow on the various areas of the tower is assessed by solving Adjoint equation in the whole fluid domain. As a result of that, some aerodynamic modifications are performed and it has been proved that the imposed loads on the tower have been declined around 31% whereas this amount of improvement is interested for designing of tall buildings.