Sound is one of the forms of mechanical energy and the two main characteristics of sound are intensity or power and frequency or wavelength of sound.their performance against the incoming sound wave, industrial silencers can be divided into two general groups of resonating and absorption silencers, the main difference between these silencers is the release of sound energy from the channeling system, which is one of the common examples of the use of resonating type silencers, their use in It is the internal combustion engines that distinguish absorption silencers from the resonator type based on the fact that the main and visible part of the act of muting the sound is achieved by changing sound energy to heat energy.The goal of this article is to design a muffler based on the breaking of sound frequencies resulting from the movement of fluid in the exhaust output of vehicles, which leads to a reduction of at least 50 db of sound and gives the operator enough peace and concentration. In this article, after examining three types of mufflers, absorbent mufflers that use the properties of porous absorbent material to absorb passing sound and are the simplest form of mufflers, have been selected, analyzed and reviewed and are suitable for the OM457 engine of Idem Industrial Company. It designed for maximum inlet exhaust temperature is 520 and for the maximum kW power is 315 with the maximum discharge relative pressure of 185 mbar for homogenization with the standard atmosphere.

In the present era of technology, organizations with the creation of new knowledge will have a greater chance for survival.These organizations should greater use the knowledge in the organization, knowledge gained from experience of other organizations and knowledge providing human resources, and ultimately create new knowledge with existing knowledge to cause competitive advantage for them. The study measures the impact of internal marketing variables consist of "Top management support", "Business process support" and "Cross-functional coordination" as independent variables, on the implementation of knowledge management with emphasis on knowledge creation as the dependent variable.The main three variables and a total of 10 sub-variables were considered for internal marketing, and the impact of each one was evaluated on knowledge creation. This research is practical from target view, and descriptive-survival from method view.Statistic society of research select from IPCO.co includes 214 persons that with use of Kokran function distribute and muster 123 questionnaires. Ultimately with use of Pearson correlation test, the correlation coefficient of dependent and independent variables were gained.Analyzing of data show that internal marketing variables have positive and meaningful impacts on implementation of knowledge management with emphasis on knowledge creation. Meanwhile finding of “Analysis of Variance” test shows that descriptive variables of this research have no impact on correlation of dependent and independent variables.

Competitiveness is the central subject matter. It is as a tool to achieve economic growth and sustainable development. Competitiveness means possible to achieve a proper and stable position in global markets. The population of this study for examining the model is 108 Yazd manufacturers. The hypotheses of research were analyzed with Smart Pls software. The data of research was collected with questionnaire. The results showed that knowledge management and internal status of enterprises were recognized as affecting factors on enterprises competitiveness. Also internal status of enterprises influences on knowledge management.

Today, organizational knowledge is recognized as a very valuable intangible resource for gaining a competitive advantage. Managing such intangible assets is essential for maintaining and gaining a competitive advantage for organizations, especially knowledge-based companies whose survival and success are tied to knowledge. Knowledge can improve and enhance the performance of organizations when shared across the organization. Despite the vital role of internal knowledge sharing, little research has been done on the factors affecting knowledge internal knowledge sharing in knowledge-based companies. For this purpose, in the present article, first, by reviewing the background, the factors affecting the internal organizational knowledge sharing in organizations were extracted, and then, using the DEMATEL method, the relationships of these factors and their prioritization have been studied. The present study is a descriptive and survey research and is a tool for collecting secondary data (library studies) and primary data (questionnaire). After designing the questionnaire and confirming its validity by experts, the questionnaire was distributed and filled by 30 experts and managers of knowledge-based companies located in S&T Parks of Shahid Beheshti University, University of Tehran, and Tarbiat Modares University. The research results show that formal and informal procedures, open-door policy, and knowledge sharing strategy are the most influential factors and in contrast to communication and network, people's knowledge and interactive memory system are the most influential factors.

Purpose: To compare the anatomical and functional results of deep vitrectomy with and without ILM peeling for full thickness macular hole.Materials & Methods: 37 eyes of 37 patients with full thickness macular hole (FTMH), confirmed by clinical examination and optical coherence tomography (OCT), enrolled in this clinical trial. Based on the stage of FTMH (stage 2, 3, 4) as described by Gass and the techniques of surgery (with or without ILM peeling) the patients were randomized into two different groups. All patients underwent preoperative Act and at least one OCT image was obtained during the postoperative follow up.After obtaining informed consent, deep vitrectomy and 20% SF6 injection was performed. The patients were unaware of their allocation status. Patients data & surgical outcome were collected and statistically analyzed. Anatomical success was defined as hole closure at postoperative OCT and functional success was referred to any improvement in visual acuity. Macular hole index (MHI) was defined as a ratio of the greatest height to the base diameter of the hole on cross-sectional OCT images.Results: 37 eyes of 37 patients (15 men & 22 women) were enrolled. The mean age of the patients was 56.4±21.94 years and FTMH were traumatic in 13 cases (35%) and Idiopathic in 24 (65%) cases. Twenty cases underwent deep vitrectomy with ILM peeling (ILM group) and the remaining cases underwent vitrectomy without ILM peeling (no ILM group).The mean preoperative 10gMAR visual acuity was 1.38±1 in the ILM group and 1.22±0.13 in the no ILM group, these improved to 0.95±1 and 0.77±0.31 postoperatively in the ILM and no ILM group, respectively (P=0.871). The overall anatomical success rate was 64%. The hole was closed in 70% of ILM peeling and 47% in the no ILM group (Chi-square test, P=0.15). In anatomically successful cases the mean of postoperative VA was significantly improved (P=0.001).In traumatic subgroup, ILM peeling seems did not affect the anatomical (P=0.2) and visual Success rates (P=0.5). There was no significant differences in hole closure rates between the traumatic and idiopathic FTMH (P=0.968). Visual acuity significantly improved after operation In MHI ³ 0.5 group compared with the MHk 0.5 group. The stage of the hole did not affect the anatomical success rate (P=0.52) or visual acuity improvement (P=0.741). Macular hole index ³ 0.5 had a prognostic value for postoperative visual acuity improvement. The hole duration was not related to anatomical success rate but there is an inverse relation between duration of the symptoms and improvement in VA.Conclusion: Deep vitrectomy and SF6 injection was a safe & effective surgical technique for full thickness macular hole and peeling of the ILM seems did not affect the anatomical or functional success rates. The hole duration, stage and origin of the hole (traumatic or idiopathic) does not related to the anatomical success or visual acuity improvement. MHI  ³ 0.5 seems to be a prognostic factor for postoperative visual improvement but not for closure rate.

The focus of this study is primarily on “the discrepancy in mentality as an important factor affecting family problems and divorce”. For this purpose, some minor studies were conducted each of which experimentally examined different aspects of mental discrepancy in Iranian families. Almost all of these studies showed that permanent disputes and divorces resulted from the differences in their world-views, thinkings, and impressions in their mutual affairs. At last, the theory of Homogamy with two major revisions were used to explain the reasons and causes of family problems and divorce which were confirmed in minor studies and cases.

The purpose of this study was to provide an optimal model for choosing knowledge management strategies to monitor internal processes using Diemel's combined model and fuzzy network analysis in one of the military organizations. This research has been conducted in two field phases. The statistical population of first phase was 44 of experts who were selected through targeted sampling including the professors of the universities of Tehran, Shahid Beheshti and Supreme National Defense university in the fields of industrial management and engineering, along with the managers and vice ministers of the military organization, and in the second phase, there were 310 staff members of the organization. Out of this 201 people were selected as sample through random sampling method. Data have been gathered using a researcher-made questionnaire, a comparison of couples in the first phase and a standard questionnaire (Bahiraeil et al., 1393) in the second phase to monitor the internal data processes and have been analyzed with the help of SPSS and Super Decision software. After determining the objective, the indicator level (three coding, personalization and combination strategies (Schickerz et al., 2004)) and then sub-indicators influencing the selection of strategies (such as formalities (Shami, 2009 and Boh, 2006), geographic dispersion (Schicheirs et al. 2004 and Boh, 2006 and Sami & Mehregan, 2008), the size of the organization (Schicheirs et al., 2004 and Boh, 2006 and Sami and Mehregan, 2008), conservatism of the managers (Shami, 2009), the nature of the organization's work (Shami, 2009 and Hansen Et al., 1999) have been determined by studying the literature. In order to determine the reliability of the first phase questionnaire, the incompatibility rate was considered to be less than 0. 1 and for validity of the five-choice Likert scale spectrum questionnaire of the second phase, exploratory and confirmatory factor analysis has been used and the number of all items was more than 0. 4. The results of the first phase of the selection of the strategy, documentation was recognized as the best strategy for monitoring organizational processes, as well as the factors of formalization, size and geographical distribution, the nature of work and conservatism of managers as sub-indicators. The findings of the second phase showed that management strategy was effective in monitoring the process and knowledge management through effective indicators including cost reduction, time reduction, deregulation, reduced risk of losing knowledge due to the absence of organization by individuals, reduction of Knowledge dependence to individuals and the speed of access to knowledge have been effective in monitoring internal processes. The organization is recommended to use technological tools such as DSS and groupware such as document repositories, knowledge maps, workflows and shared databases.