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This paper presents a model using fuzzy synthetic evaluation to estimate the methane generation rate constant, k, for landfills. Four major parameters, precipitation, temperature, waste composition and landfill depth were used as inputs to the model. Whereas, these parameters are known to impact the methane generation, mathematical relationships between them and the methane generation rate constant required to estimate methane generation in landfills, are not known. In addition, the spatial variations of k within a landfill combined with the necessity of site-specific information to estimate its value, makes k one of the most elusive parameters in the accurate prediction of methane generation within a landfill. In this paper, a fuzzy technique was used to develop a model to predict the methane generation rate constant. The model was calibrated and verified using k values from 42 locations. Data from 10 sites were used to calibrate the model and the rest were used to verify it. The model predictions are reasonably accurate. A sensitivity analysis was also conducted to investigate the effect of uncertainty in the input parameters on the generation rate constant.

In this paper, we present a scheme, called Cluster Cooperative (CC) for caching in mobile ad hoc networks. In CC scheme, the network topology is partitioned into non-overlapping clusters based on the physical network proximity. For a local cache miss, each client looks for data item in the cluster. If no client inside the cluster has cached the requested item, the request is forwarded to the next client on the routing path towards server. A cache replacement policy, called Least Utility Value with Migration (LUV-Mi) is developed. The LUV-Mi policy is suitable for cooperation in clustered ad hoc environment because it considers the performance of an entire cluster along with the performance of local client. Simulation experiments show that CC caching mechanism achieves significant improvements in cache hit ratio and average query latency in comparison with other caching strategies.

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The upstream oil and gas industry has used flare pits (FPs) for decades to store and/or burn produced fluids generated at well sites, compressor stations, and batteries. Since produced fluids contain liquid hydrocarbons, process chemicals, crude bitumen, or salt water, FPs usually contain high levels of hydrocarbons, metals, and salts. At present, bioremediation by land application is the most common method practiced by the oil and gas industry to treat FP waste. High rate slurry-phase and solid-phase biotreatment methods are viable alternatives to the low cost, yet inefficient, land application option. The use of slurry-phase and solid-phase biotreatment in the overall strategy for FP waste remediation is reported in this paper. A laboratory solid-phase bioremediation study was conducted over a period of 270 days to investigate the effects of nitrogen, phosphorus, salinity levels, and incubation temperature on the biodegradation of hydrocarbons in FP pit waste employing a statistical partial factorial experimental design. A soil contaminated with flare pit hydrocarbons was treated with nitrogen (500, 1,250, or 2,000 mg/kg of soil), phosphorus (100, 250, or 400 mg/kg of soil), and salt (yielding electrical conductivities of 0, 20, or 40 dS/m), and incubated at three temperatures (20 °, 30 °, and 40 °C). The highest oil and grease (O&G) reduction of 34% was observed in the soils incubated at 30 °C. Soil temperature had more influence on bioremediation rates than did N or P. The high P levels, up to 400 mg P/kg soil, had no detrimental effect on hydrocarbon biodegradation. High salinity levels reduced the rate of hydrocarbon biodegradation. The slurry-phase biotreatment of flare pit waste using 2 L slurry reactors showed an initial rapid decrease in hydrocarbon concentrations. However, biodegradation decreased with time and eventually ceased, leaving recalcitrant compounds. The nutrient concentrations (above 350 mg N/L, as ammonium nitrogen) did not exhibit statistically significant effects on hydrocarbon degradation. The primary effect of waste composition was highly significant, with higher soil clay content resulting in lower biodegradation. Introduction The produced fluids generated at oil and gas well sites, compressor stations, and batteries contain a variety of liquid hydrocarbons, process chemicals, crude bitumen, and salt water. Until recently, the industry practice was to store and intermittently burn these produced fluids in earthen pits called "flare pits." According to recent estimates, Alberta is home to about 30,000 flare pit (FP) sites(1). In 1996, the provincial government of Alberta banned the disposal of produced fluids in FPs, and requested the oil and gas industry to remediate former FP sites that are posing significant risks to human health and the surrounding environment. Because of the highly complex and variable nature of the waste, remediation of FP waste presents a serious challenge. At present, the most common technique used for remediation of FP sites is bioremediation by land application. Land application is relatively low-tech and less expensive (compared with competing techniques such as incineration). Furthermore, land application is popular in locations such as rural Alberta, because of the nature of the spatial distribution of FP sites.