A decision support system for assessing landfill performance

Designing environmentally sound landfills is a challenging engineering task due to complex interactions of numerous design variables; such as landfill size, waste characteristics, and site hydrogeology. Decision support systems (DSS) can be utilized to handle these complex interactions and to aid in a performance-based landfill design by coupling system simulation models (SSM). The aim of this paper is to present a decision support system developed for a performance-based landfill design. The developed DSS is called Landfill Design Decision Support System – LFDSS. A two-step DSS framework, composed of preliminary design and detailed design phases, is set to effectively couple and run the SSMs and calculation modules. In preliminary design phase, preliminary design alternatives are proposed using general site data. In detailed design phase, proposed design alternatives are further simulated under site-specific data using SSMs for performance evaluation. LFDSS calculates the required landfill volume, performs landfill base contour design, proposes preliminary design alternatives based on general site conditions, evaluates the performance of the proposed designs, calculates the factor of safety values for slope stability analyses, and performs major cost calculations. The DSS evaluates the results of all landfill design alternatives, and determines whether the design satisfies the predefined performance criteria. The DSS ultimately enables comparisons among different landfill designs based on their performances (i.e. leachate head stability, and groundwater contamination), constructional stability and costs. The developed DSS was applied to a real site, and the results demonstrated the strengths of the developed system on designing environmentally sound and feasible landfills.     

Debriefing with teachers after the Marmara earthquake: an evaluation study1

The aim of this study was to evaluate the effectiveness of the debriefing meetings conducted after the 1999 earthquakes in Marmara, Turkey. The sample consisted of 265 teachers, 223 of whom attended the debriefing meetings. The personal satisfaction ratings of the teachers who attended the meetings revealed that they found the sessions satisfactory. The results of the comparison between those who reported that they benefited from the meetings and those who felt they did not indicated that the first group had lower scores on all of the psychopathology measures. A comparison between 42 teachers who did not attend the meetings and a randomly chosen group of 45 teachers who did attend revealed that the two groups differed significantly in terms of their post‐traumatic stress symptom scores. The findings of the study suggest that, in general, the teachers' debriefing sessions were satisfactory.     

Influence of different processing techniques on the mechanical properties of used tires in embankment construction

Use of the processed used tires in embankment construction is becoming an accepted way of beneficially recycling scrap tires due to shortages of natural mineral resources and increasing waste disposal costs. Using these used tires in construction requires an awareness of the properties and the limitations associated with their use. The main objective of this paper is to assess the different processing techniques on the mechanical properties of used tires–sand mixtures to improve the engineering properties of the available soil. In the first part, a literature study on the mechanical properties of the processed used tires such as tire shreds, tire chips, tire buffings and their mixtures with sand are summarized. In the second part, large-scale direct shear tests are performed to evaluate shear strength of tire crumb–sand mixtures where information is not readily available in the literature. The test results with tire crumb were compared with the other processed used tire–sand mixtures. Sand–used tire mixtures have higher shear strength than that of the sand alone and the shear strength parameters depend on the processing conditions of used tires. Three factors are found to significantly affect the mechanical properties: normal stress, processing techniques, and the used tire content.     

A Comparison of Volunteer,BioRID P3 and Hybrid III Performance in Rear Impacts

The most important tool for testing seat-systems in rear impacts is a crash test dummy. However, investigators have noted limitations of the most commonly used dummy, the Hybrid III. The BioRID I is a step closer to a biofidelic crash test dummy, but it is not user-friendly and the straightening of the thoracic spine kyphosis is smaller than that 220of humans. To reduce these problems, a new BioRID prototype was developed, the P3. It has new neck muscle substitutes, a softer thoracic spine and a softer rubber torso than does the BioRID I.

The BioRID P3 was compared with volunteer test data in a rigid and a standard seal without head restraints. The dummy kinematic performance, pressure distribution between subject and seatback, neck loads and accelerations were compared with those of ten volunteers and a Hybrid III. The BioRID P3 provided repeatable test results and its response was very similar to that of the average volunteer in rear impacts at Δv = 9 km/h.     

Engine Performance and Emission Characteristics of Plastic Oil Produced from Waste Polyethylene and Its Blends with Diesel Fuel

The overall objective of this study was to explore the utility of waste plastics as a potential source of diesel fuel. An experimental study was conducted to evaluate the use of various blends of plastic oil produced from waste polyethylene (WPE) with diesel fuel (D). WPE was degraded thermally and catalytically using sodium aluminum silicate as a catalyst. The oil collected at optimum conditions (414°C–480°C range and 1 h reaction time) was fractionated at different temperatures and fuel properties of the fractions were measured. Plastic oil was blended with diesel fuel at the volumetric ratios of 5%, 10%, 15%, 20%, and 100%. Fuel properties of blends are found comparable with those of diesel fuel within the EN 590 Diesel Fuel standard and they can also be used as fuel in compression ignition engines without any modification. Engine performance and exhaust emission studies of 5% WPE-D (WPE5) blend were performed. Experimental results showed that carbon monoxide (CO) emission is decreased by 20.63%, carbon dioxide (CO₂) emission is increased by 3.34%, and oxides of nitrogen (NO_x) emission is increased by 9.17% with WPE-D (WPE5) blend compared to diesel fuel.     

Sex ratio estimations of loggerhead sea turtle hatchlings by histological examination and nest temperatures at Fethiye beach, Turkey

Hatchling sex ratios in the loggerhead turtle (Caretta caretta) were estimated by placing electronic temperature recorders in 21 nests at Fethiye beach during 2000–2002. Over the seasons, the mean temperature in the middle third of the incubation period ranged from 26.7 to 32.1°C, and incubation periods ranged from 49 to 67 days. Based on the mean temperatures during the middle third of the incubation period, and on histologically sexed dead hatchlings, the sex ratios of hatchlings at Fethiye beach were roughly equal, i.e. 60–65% of the hatchlings were females. This contrasts with the highly female-skewed sex ratios in loggerhead turtles elsewhere; Fethiye has a relatively high proportion of male hatchlings. For endangered sea turtles, the knowledge of hatchling sex ratios at different beaches, coupled with appropriate conservation measures, can make an important contribution to their survival.     

Treatment of Basic Red 29 dye solution using iron-aluminum electrode pairs by electrocoagulation and electro-Fenton methods

The aim of this study is the treatment of Basic Red 29 (BR29) dye solution using hybrid iron-aluminum electrodes by electrocoagulation and electro-Fenton methods. The effect of current density, initial pH, supporting electrolyte, H₂O₂, and initial dye concentration on dye removal efficiency was investigated, and the best experimental conditions were obtained. Time-coarse variation of UV-Vis spectra and toxicity and chemical oxygen demand (COD) removal were also examined at the best experimental conditions. Both systems were found very successful for the removal of BR29 dye. The removal efficiency of >95 % for BR29 dye solution was reached easily in a short time. At the best experimental conditions, for the initial BR29 concentration of 100 mg/L, >95 % BR29 dye and 71.43 % COD removal were obtained after 20 and 40 min of electrolysis, respectively. Additionally, toxicity results for electro-Fenton treatment of 100 mg/L BR29 were also very promising. According to the results obtained, although electro-Fenton is more effective, both systems can be used successfully to treat textile wastewater including dyes.     

Performance Enhancement of a Beta Type Rhombic Drive Stirling engine

ABSTRACT

Stirling engines maintain attraction because of their high energy conversion efficiencies. In this study, experimental comparison of a beta-type Stirling engine for two different rhombic-drive mechanisms was presented. In one of the rhombic mechanisms, spur gears were used and the gear shaft was supported in bearings from one side. In the other mechanism, two helical gears were placed on crankshafts and the crankshafts were supported in bearings from both sides. Rhombus lengths of the mechanisms were determined as 66 mm and 80 mm to provide same constant compression ratio of 2.5 for both configurations. Both mechanisms were used in the same beta-type Stirling engine having same cylinder, piston and displacer dimensions. Performance parameters of the engines were evaluated at different helium charge pressures (2–4 bar) and hot-end temperatures (400–600°C). The hot-end of the displacer cylinder was heated by a liquefied petroleum gas (LPG) burner. The engine power increased by 132%, friction losses and gear noses were reduced by supporting the rhombic-drive mechanism from both side and using helical gears. The maximum output torque and power of the engine were obtained as 13.14 Nm at 428 rpm engine speed and 663 W at 800 rpm engine speed, respectively, at 600°C hot-end temperature and 4 bar charge pressure.