Although septic tanks are amply used for on site sewage treatment, these units have serious drawbacks: the removal efficiency of organic material and suspended solids is low, the units are costly and occupy a large area and operational cost is high due to the need for periodic desludging. In this paper an innovative variant of the UASB reactor is proposed as an alternative for the septic tank. This alternative has several important advantages in comparison with the conventional septic tank: (1) Although the volume of the UASB reactor was about 4 times smaller than the septic tank, its effluent quality was superior, even though small sludge particles were present, (2) desludging of the UASB reactor is unnecessary and even counterproductive, as the sludge mass guarantees proper performance, (3) the UASB reactor is easily transportable (compact and light) and therefore can be produced in series, strongly reducing construction costs and (4) since the concentration of colloids in the UASB effluent is much smaller than in the ST effluent, it is expected that the infiltration of the effluent will be much less problematic.

With the emergence of utility computing and the continuous search for reducing the cost of running Information Technology (IT) infrastructures, we will soon experience an important change on the way these infrastructures are assembled, configured and managed. In this paper we consider the problem of managing a hybrid high-performance computing infrastructure whose processing elements comprise in-house dedicated machines, a utility computing service provider, and idle machines from a best-effort peer-to-peer grid. This infrastructure supports the execution of both best-effort and real-time applications. Realtime applications use primarily computing power from the inhouse machines and any processing power that can be attained from the best-effort grid. Extra capacity required to meet deadlines is purchased from the utility computing service provider. This extra capacity is reserved for future use through short term contracts which are negotiated with no human intervention. We take a business-driven approach for the management of this hybrid infrastructure and propose heuristics that can be used by a contract planner agent to reduce the cost of running the applications at the same time that guarantees that deadlines are met. In particular, we show that constructing an estimation for the behavior of the grid is essential for making contracts that lead to high efficiency in the use of the hybrid infrastructure.

In this paper we consider a peer-to-peer grid system which provides multiple services to its users. In this system, an incentive mechanism promotes collaboration among peers. It has been shown that the use of a reciprocation mechanism in such a system is able to prevent free riding and, at the same time, promotes the clustering of peers that have mutually profitable interactions. However, when peers are subject to a budget limitation, each peer must select a subset of all services that can possibly be offered. In this work we show that the received utility is strongly dependent of the offered services. The main contributions of this work are a methodology to evaluate the impact of service changes in the obtained utility and how much different sets of offered services impact in the peer's utility. These results indicate that further research is needed, particularly for the development of heuristics to choose the best services to offer.

Abstract-In this paper we consider a peer-to-peer grid system which provides multiple services to its users. An incentive mechanism promotes collaboration among peers. It has been shown that the use of a reciprocation-based incentive mechanism in such a system prevents free-riding and, at the same time, promotes the clustering of peers that have mutually profitable interactions. On the other hand, an issue that has not been sufficiently studied in this context is that of service portfolio selection. Normally, peers are subject to resource limitations, which force them to provide only a subset of all services that can be possibly provided. Clearly, the subset of selected services impacts the profit that the grid yields to the peers, since each service will have a different cost and will return a different utility. Moreover, the utility generated by a service is strongly influenced by the behavior of the other peers, which in turn may change over time. In this paper we explore the use of heuristics to select the portfolio of services to be offered by peers in such a grid. The main contributions of this work are the use of heuristics to improve the average profit of peers and a study on the impact of some system characteristics on the heuristics behavior.

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