Sharif Digital Repository

In Iran, the technical issues are not considered when changing or replacing the bed of filter. In this regard, less attention is paid for the properties of the materials (e.g. shape, aggregation, effective size and uniform coefficient of grains, etc.) used in the replaced bed of filter. Therefore, the performance of the replaced filter is not good from treated water quality, water production, and backwash interval points of view. In this project, Light Expanded Clay Aggregate, LECA, was chosen as a suitable material to be used in the bed of filter because of its favorable grain shape. The performance of LECA has been examined in both “Single- Media Filter” and “Dual-Media Filter” for... 

In this project, function of anaerobic digestion of organic waste in liquid phase and treating the following sewage in biologic tower(trickling filter) has been investigated in an experimental process. Solid waste were supplied from sharif university restaurant and after weighting and classification is added to tanks which filled by 40% sludge and 60% water. For controlling the function of biologic tower, a control reactor were used. Retention time for digestion of solid waste is 40 day. First solid loading was 500g and 75g organic waste in main & control reactor equal to 5(kg solid waste)/( m^3.reactor.day) 1.3(kg TS)/( m^3.reactor.day) and were doubled in second loading. It seems that... 

It is well known that the most rigorous method to assess the performance and to predict the seismic demands of a structure subjected to earthquake is nonlinear time history analysis. However, this technique is accompanied by complexities and difficulties in evaluating the seismic demands of structures and requires superior knowledge and skill. As a result, in recent years, nonlinear static analysis has been proposed in performance based design procedures. One of the primary assumptions of nonlinear static procedures is that the behavior of a structure with multiple degrees of freedom (MDOF) subjected to seismic ground motion can be estimated from the response of an oscillator with a single... 

The practice of river restoration has grown exponentially over the last several decades. There has been little empirical evaluation of whether restoration projects individually or cumulatively achieve the legally mandated goals of improving the structure and function of rivers. Nutrient reduction through simple methods is the most critical factor. The simplest method, which has minimal financial burden as well as preventing, and reducing the entrance of pollutants into the Chalus River (Mazandaran, in north of Iran), has been selected. The origins of rivers start at a high point and move with a steep. ... 

In this study, we will examine persistence of various kinds of seasonally forced epidemiological models and seasonally varying predator-prey models. The results of our study regarding persistence of the models will be shown via basic reproduction number. We will show that, in the framework of our study and under some conditions, persistence is obtained as long as the basic reproduction number is bigger than one. We will also prove that, in the framework of our study and under sufficient conditions, if the basic reproduction number is smaller than one, the species under discussion won’t survive in the predator-prey models, and the disease(s) would go extinct in the epidemiological... 

Rail transport system plays an important role in the development of the economies of the countries. This system is worn out over time by operating and weather conditions and requires maintenance and repair. One of the objectives of maintenance operations is to maintain tracks in an acceptable level and prevent their excessive deviation from the optimal situation. This deviation is called geometric irregular deviation. If these irregularities go away, they can cause traffic accidents and derailment in addition to losing travel convenience. So avoiding the deviation of the tracks is a very important. Maintenance management systems in the past few decades have been considered by the experts in... 

Time delay systems may arise in practice for a variety of reasons, such as autonomous systems (without feedback control), and the delay is the result of an intrinsic property of the system. Sometimes the delay results from feedback control action, instead from the system itself; that is, due to the nature of the system, the feedback is delayed. Another type of delays of similar effects may be incurred due to delayed measurements. In both delayed control and delayed measurement, the delay is usually considered undesirable, which has the tendency to deteriorate the system performance or even destabilize the system.

In this thesis, three types of adaptive controller are proposed for... 

Vulnerability of water and sewage infrastructure in Kish Island survey versus natural and unnatural threats. It is important to know what to do when crisis or unpredicted event occurs in the Island. Decision makers and master managers of the Island, as the main custodians make suitable and effective reactions and decisions so that the impact of threats is reduced to minimum. According to the threats, there are short term and long term solutions. These solutions can be applied when the Island is encountered with crisis  

Constructed wetlands are natural systems for wastewater treatment that Proper functionality of these systems to remove organic matter, pathogens, micro pollutants and etc., Are considered as environmental friendly systems. Proper capabilities of pollution removal and inexpensive cost of construction, commissioning and maintenance of these systems compared to engineering WWTPs in the world is leading to growing constructed wetlands. Due to the increasing use of artificial wetlands in the world for post treatment wastewater, because of right capabilities of this systems, and the absence of any natural wastewater treatment systems on Kish Island, this study investigates the possibility of... 

Environmental pollution and depleting the resources of energy are two significant crises which has been caused by excessive Energy consumption in all over the world. One of the most appropriate and reproducible energies is the Biogas energy. Huge amount of sewages and dry wastes are produced in cities every day can causes devastated damages to environment. All types organic matter extracted from different processes of treating sewages are influenced by germ activities and will be transformed to mineral structures and the final product of these reactions would be gases which can be used as enormous sources of fuel and energy. There are different devices made all over the world to be utilized... 

A major environmental challenge for wastewater treatment in Iran and other countries is the disposal of excess sludge produced during the biological process. This project has been developing and testing a technology that will help to overcome this challenge in Kish Island wastewater plant. Results demonstrate it can perform highly effective treatment of municipal wastewater while producing low levels of sludge.Applicationofvermifiltrationfor treatment of wastewater sludge using the Eiseniafetida earthworm species. The earthworms’ gut acted as a biofilter whereby there was reduction in the sewage wastewater’s solid and liquid organic and inorganic wastes through ingestion and expelling these... 

Reproducing kernel particle method (RKPM) is a meshfree method for solving various differential equations. RKPM is based on pure mathematics; therefore, it is in the center of attention of many scientists. One major problem in RKPM is satisfying the essential boundary conditions (EBCs) involving the derivative of the field function. This problem is considered herein and its solution is proposed. To this end, two actions should be undertaken. First, the concept of Hermitian interpolation is employed to add the derivative term to the reproducing equation of RKPM and a new meshless method called gradient RKPM (GRKPM) is introduced. Second, the corrected collocation method is modified so... 

Deficiency of water leads to extensive researches on alternative water resources. recycling of wastewater for non-drinking purposes such as irrigation, industrial, green belts, forestry and streets and drainage channels washing is One of the existing methods. Therefore, sewage treatment with the purpose of reducing its electrical conductivity has been done in the current research using a real scale vermifilter. Hence, the effluent from a septic tank with a daily loading of 2 (m3/day) was pumped into the vermifilter during 45 days through a pumping system.Then, the effluent from the vermifilter by another pump entered on the surface of the substrate. The results showed that electrical... 

Over the past few decades, with the exponential increase in data volume, scientists and researchers have tried to discover relationships and algorithms for productivity and find useful information from this amount of data in various fields. Their efforts in data analysis have led to the development of algorithms in the big data field. The result of researchers' working in multiple fields has come to aid the people of science and technology. Among the most important of these areas, we can mention the health and medical sectors, financial sectors, services, manufacturing sectors, etc. The purpose of this study is to enter the financial industry and use data mining tools. One of the newest and... 

Tehran air quality is facing a real crisis. Reports of pertinent organizations show air quality is deteriorating in recent years and unhealthy days are increasing. As a result, study and planning in order to change this trend and moving toward improving air quality is a necessity. On the other hand, in order to make proper decisions and choosing effective approaches considering cost-effective attribute and legal, temporal and budget restrictions, selecting the right tool is essential. Air quality models are the tools which in a cost saving manner and reasonable time can provide the required results for researchers, decision makers and legislators. An applicable model correspondent with urban... 

From the main factors causing an unpleasant odor can refer to indoles, askatels, mercaptans, some volatile organic compounds, sulfide hydrogen, ammonia, and the number of odor-causing compounds, which are also found in the wastewater facilities and sometimes produce unpleasant odors. Meanwhile, ammonia (Pungent and irritating odor) and sulfide hydrogen (colorless poisonous gas with the odor of rotten eggs) can be presented as major factors in sewage odor.
Several factors are involved in the foul-smelling hydrogen sulfide gas collection system and wastewater treatment. A few of them include numerous sewage pumping stations, selected the appropriate gradient in the collection system,...