Data-Flow Based Model Analysis

The concept of (meta) modeling combines an intuitive way of formalizing the structure of an application domain with a high expressiveness that makes it suitable for a wide variety of use cases and has therefore become an integral part of many areas in computer science. While the definition of modeling languages through the use of meta models, e.g. in Unified Modeling Language (UML), is a well-understood process, their validation and the extraction of behavioral information is still a challenge. In this paper we present a novel approach for dynamic model analysis along with several fields of application. Examining the propagation of information along the edges and nodes of the model graph allows to extend and simplify the definition of semantic constraints in comparison to the capabilities offered by e.g. the Object Constraint Language. Performing a flow-based analysis also enables the simulation of dynamic behavior, thus providing an "abstract interpretation"-like analysis method for the modeling domain

Thermolysis of plastic waste: Reactor comparison

Plastic waste offers an attractive business opportunity if treated intelligently. Presently, owing to the lack of economically viable recycling solutions and political interest, this valuable feedstock is bound for an ill-fated destiny i.e. landfills and inefficient incineration. Landfilling plastic waste is rather a storage mechanism than a prevention mechanism. Plastics can stay in ground and in oceans for hundreds of years without decomposing, posing serious environmental hazards. Given the complexity of the plastic waste mixture and heterogeneity of waste streams, a single recycling solution is improbable; however, the current environmental situation demands an urgent need to find ways to tackle this ever-growing waste problem. Thermolysis (pyrolysis) of non-recyclable plastic waste allows the waste to be converted to a valuable hydrocarbon rich petrochemical-based feedstock. This feedstock i.e. composed of oil, wax and gas, has great potential to be used in multiple applications, one of the most attractive ones is co-feeding in a refinery. The gas and char generated in the process can be used to provide the energy needed for thermolysis. Thermolysis of plastic waste has to offer many benefits over other recycling techniques such as the recycling of feedstock contaminated with dirt and organics, recycling of problematic waste such as laminates, multilayer plastic and even hazardous plastics such as those found in electrical or demolition waste. Furthermore, it converts the solid waste that is difficult to store, transport and dispose, into liquid and wax product that is easily transportable. However, like other recycling technologies, it also suffers from some technical challenges, which should be scrutinized before choosing the recycling technology. From the practical aspects, the choice and availability of feedstock, reactor type and investments, use of a catalyst, products needed, availability of standards, REACH, and established markets etc. all these factors come into play and should be evaluated thoroughly. This presentation targets the role of thermolysis in managing global plastic waste. Technological challenges associated with reactor types used for thermolysis and the quality and upgrading of products will be discussed, i.e. comparison of the slow vs. fast thermolysis. Furthermore, the results of a national ‘Waste to Products’ project will be presented including the learnings from thermolysis experiments

Towards anode with low indium content as effective anode in organic solar cells

In2O3 thin films (100 nm thick) have been deposited by reactive evaporation of indium, in an oxygen partial atmosphere. Conductive (σ = 3.5×103 S/cm) and transparent films are obtained using the following experimental conditions: oxygen partial pressure = 1×10−1 Pa, substrate temperature = 300 ◦C and deposition rate = 0.02 nm/s. Layers of this In2O3 thick of 5 nm have been introduced in AZO/In2O3 and FTO/In2O3 multilayer anode structures. The performances of organic photovoltaic cells, based on the couple CuPc/C60, are studied using the anode as parameter. In addition to these bilayers, other structures have been used as anode: AZO, FTO, AZO/In2O3/MoO3, FTO/In2O3/MoO3 and FTO/MoO3. It is shown that the use of the In2O3 film in the bilayer structures improves significantly the cell performances. However the open circuit voltage is quite small while better efficiencies are achieved when MoO3 is present. These results are discussed in the light of surface roughness and surface work function of the different anodes

Integrated approach for the analysis and management of urban relocation and infrastructure development projects : the case of the southwestern suburbs of Beirut, Lebanon

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Includes bibliographical references (leaves 206-209).Relocation of inhabitants and infrastructure development for urban renewal is a main problem facing major cities and their suburbs. It is always subject to economic, political, social, cultural, religious, and environmental constraints. Urban renewal had been adopted by governments and international development agencies for years, and was subject to failure when the solution implemented did not fully account for the unique circumstances on hand. This thesis, by using a case study in Beirut, Lebanon, aims at providing a framework that integrates construction management, decision-analysis, and urban planning tools, and that offers a stronger and robust platform for solving urban relocation and infrastructure development projects. The project of Elyssar, which aims at planning, developing, and revitalizing the southwestern suburbs of Beirut, Lebanon, is chosen as a case study to investigate the economic/financial component of the overall multiobjective-multicriterion decision analysis problem and to suggest ways for the public sector to increase the project's revenue stream, decrease its large cost components which dominate the cash flow, and determine the cost that will need to be subsidized. This is done using the net present value and sensitivity analysis method of assessment. The results conclude that no direct benefits are encountered. The public sector will have to subsidize the project by buying upfront the social welfare and the economic improvements that are to materialize in the future. The involvement of the private sector in project implementation is also tested and the feasibility of a public-private partnership is evaluated. The outcome concludes that if the public sector shows commitment to the project, it would be attractive to procure the project through the public-private partnership format. Finally recommendations are provided to the Elyssar management as to what critical urban relocation elements and policies need to be addressed more closely to ensure the success of the project. It also encourages further research along this line to allow future integration of related factors that are social, political, and anthropological in nature.by Christian A. Saad.S.M

Development of Novel Experimental Infrastructure for Collecting High-Fidelity Experimental Data for Refrigerant to Air Heat Exchangers

Manufactures of fin-and-tube heat exchangers often employ predictive modelling tools in order to reduce development cost and time. These tools require high-fidelity experimental data to validate the accuracy of their predictions. To that end, this paper presents the design and development of a custom-designed pumped refrigerant loop to collect high-fidelity experimental data for fin-and-tube heat exchangers in three operating modes: (1) single-phase refrigerant, (2) evaporator, and (3) condenser mode. It is combined with a small-scale wind tunnel installed in a psychrometric chamber facility for the purpose of validating the recently developed discretized fin-and-tube heat exchanger models (Sarfraz et al., 2019a and 2019b). The pumped refrigerant loop is able to precisely control desired refrigerant test conditions, flowrate to each individual heat exchanger circuit, and has been sized in order to test heat exchanger coils up to a capacity of 5 tons (17.5 kW). A preliminary test plan and uncertainty analysis is presented for the first heat exchanger coil to be tested. The uncertainty analysis showed that the experiment will have the capability of measuring overall coil capacity within ±2%. A design of experiments is also presented, which suggests that 9 tests per coil is an adequate number for minimizing experimental effort. A preliminary experiment was performed which showed that the average air and refrigerant side capacities match to within 1.1% of each other. This provides evidence that the experimental setup has the capability to far exceed the 5% threshold set by ASHRAE Standard 33 (2016)

First substantiated record of mediterranean spearfish Tetrapturus belone (Istiophoridae) from the Syrian Coast

Investigations conducted off the coast of Syria (eastern Mediterranean Sea) allowed capturing on 6 November 2022 of a specimen of Mediterranean spearfish Tetrapturus belone Rafinesque, 1810, constituting the first record of the species in the area. The studied specimen measured 1100 mm in total length (TL), its total body weight was 2015 g. It is described in the present paper including morphometric measurements and meristic counts. Its distribution in the Syrian marine waters and in the Mediterranean Sea is discussed and commented

First substantiated record of Dory snapper Lutjanus fulviflamma (Lutjanidae) from the eastern Mediterranean Sea

The authors report on the capture of a medium sized specimen of Dory snapper Lutjanus fulviflamma (Forsskål, 1775) from the Syrian coast but also for the eastern Mediterranean Sea. It was a medium sized specimen which measured as 245 mm total length (TL), 195 mm standard length (SL) and weighed 208 g. The specimen was described including some morphometric measurements and meristic counts. This Syrian L. fulviflamma could be considered as a Lessepsian migrant due to the vicinity of Suez Canal, incoming from the Red Sea

Experimental investigation of cavitation-induced erosion around a surface-mounted bluff body

The objective of this study is to investigate the collapsing behavior of cavitation, which leads to the erosion of material. An experimental examination was conducted in a channel with a semi-circular cylinder obstacle, which serves as a “vortex cavity” generator. Cavitation was achieved by employing a range of pressure differences over the test section and a high-speed camera was used to observe the cavitation behavior. The flow field behind the semi-circular cylinder was investigated as a characteristic example of bluff bodies that exhibit a distinct, separated vortex flowin their wake. The cases with the bluff body were also compared to the ones without the bluff body. Erosion tests were performed using paint (stencil ink). The intensity of cavitation is characterized by the cavitation number (σ); the lower the cavitation number, the higher the cavitation intensity. The erosion (removal of paint) after 40\ua0min of operation revealed distinct and repeatable results. For a high cavitation number, a large number of von Karman-vortex-like cavities are shed downstream of the obstacle. This results in a higher number of collapse events and, ultimately, more erosion. On the other hand, at lower cavitation numbers, the erosion took place at the cavity\u27s closure line. It was seen that with the increase in cavitation intensity, the erosion area increases. Moreover, the bluff body obstacle promotes and localizes cavitation-induced erosion on the sample plate compared to the cases without the bluff body. This ultimately means that in the cases with the bluff body, less power is required in the system to cause erosion. The erosion patterns caused by the bluff body cavitation are more repeatable compared to the cases without the bluff body due to the localized cavitation load. The erosion pattern from the paint test is also compared with a material loss test (30\ua0h of operation). A very good qualitative agreement is found between the two tests, with the paint test requiring approximately two orders of magnitude less running time of the facility. We demonstrate that paint tests, combined with this geometry, provide an efficient and economical way to investigate erosion patterns compared to expensive material loss tests