Managing municipal solid waste correctly is critical to the success of a society. Many regions and countries in the world are behind others in the context of solid waste management. In order to compare three such regions within this context, a meta-analysis was conducted in order to develop a decision matrix. Within this decision matrix, the United States, Europe, and Asia were compared to determine which region is managing municipal solid waste the best. This research design allowed for compiling information from many sources to increase the accuracy of data used in the justifications for the decision matrix. Purposive sampling was used to select and evaluate sources that discuss solid waste management to discern which region’s processes are most favorable in many parameters. The decision matrix consists of nine parameters: main management techniques; finances; landfill taxes; jobs created; waste generation; waste composition; waste storage, collection, and transportation; energy recovery; and environmental health. Each was scored on a scale from zero to ten, ten being the best score and zero being the worst. The final score from the decision matrix suggested that Europe had the most favorable municipal solid waste management (MSWM) system, and the United States had a notably close yet lower score. Asia had the lowest score that was hardly comparable to the other two regions.

A laboratory investigation was carried out to determine the optimum soil to fly ash mix ratio to enhance the engineering properties of clayey sand that can potentially be used as a road subgrade. Grain size distribution and Atterberg limits tests were conducted to classify the soil and to study the effects of the fly ash on the soil plasticity. The Proctor test was conducted to determine the optimum moisture content and maximum dry density of soil-fly-ash mixtures with arbitrarily selected 0%, 40%, 50%, and 60% fly ash content. A higher percentage was selected to find the highest optimum fly ash content to maximize the beneficial use. Unconfined compression and consolidation tests were conducted with air-dry arbitrarily selected curing periods of 0, 2, 8, and 28 days to determine the strength and to predict the settlement and the volume change behavior. It can be concluded from the trend analysis that a fly ash content range of 32–50% appeared to be optimum that is expected to perform better as subgrade materials for a curing period range of 16–19 days. However, experimental data showed a fly ash content of 50% was the optimum for a curing period of 8 days. The settlement and the volume change behavior improved at least 44% with increased fly ash content.

The polarization-encoded optical shadow casting (POSC) scheme is used to design a 2-digit by 2-digit trinary multiplier. Three design algorithms for identifying the appropriate source patterns, input patterns, and output mask for both serial and parallel operations are presented. The inclusion of analyzer pattern reduces the number of pixel subcells for the POSC inputs.

This study is a preliminary investigation of the independent utilization of two types of fly ash (FA)–FA Type C and FA Type F-as partial replacement of fine aggregate (sand) and cement in Portland cement concrete (PCC) mixes. The main objective was to determine an optimum substitution range for each type of FA that would offer well-performing concrete in terms of workability, compressive strength, and durability. To this end, multiple concrete batches were prepared, incorporating each type of FA at four different levels: 5%, 10%, 15%, and 20% by weight of fine aggregate replacement and 10%, 20%, 30%, and 40% by weight for cement replacement. Then, concrete samples (100 mm diameter × 200 mm tall cylinders) were cast from each batch and were moisture-cured for 7, 14, and 28 days prior to testing. The addition of FA contributed positively to the strength development at specific replacement levels: all percentages for both FA Type C and Type F for fine aggregate replacement and up to 30% FA content for both Type C and F for cement replacement, 10% for both FA Type C and Type F provided the higher strength for aggregate replacement, and 10–20% for both types of FA provided the higher strength for cement replacement. Furthermore, these additions of FA exhibited comparable workability and durability except for FA Type F, which did not exhibit comparable workability for aggregate replacement. FA Type C can be recommended for both early and long-term strength for fine aggregate replacement, whereas FA Type C is suggested to be used for early strength and Type F provides for long-term strength for cement replacement. Type C provides better durability and Type F provides better workability for cement replacement.

Hybrid and online synchronous delivery of courses is a time-demanding approach to teaching and learning systems that is designed to engage students in investigations of authentic concepts or problems without coming to the pre-assigned classrooms two or three times a week. This study presents perceptions and attitudes of students that attended a hybrid course in environmental engineering that suddenly converted to an online synchronous delivery due to COVID-19. It also presents an assessment of the hybrid and online synchronous delivery approach on the final exam scores as well as the final grades of the same course. The course, ‘Introduction to Environmental Engineering’, was developed as an online course for Civil and Environmental Engineering program students and delivered with hybrid and online synchronous options due to COVID-19 pandemic for several semesters to test the concept. In the hybrid delivery set up, all the quizzes and homework assignments were online while the midterm and final exams were in-class. For spring 2020 the final exam was online and for summer 2020 both the midterm and final exams were online due to COVID-19 adjustment. At the very end of the semesters, an online anonymous survey was conducted with five questions to understand the students’ perception and attitude on exam taking options and learning environment. Students’ perceptions and attitudes about online synchronous delivery approach compared to hybrid delivery approach, as well as the learning outcomes, appeared at face value not to be favorable. However, statistical analysis revealed that differences between online synchronous delivery and the Pre-COVID-19 hybrid delivery were not significant, indicating that, at least for these engineering students, online synchronous delivery is a justifiable option.