A dynamic mathematical model for sequential leach bed anaerobic digestion of organic fraction of municipal solid waste

A mathematical model that describes the operation of a sequential leach bed process for anaerobic digestion of organic fraction of municipal solid waste (MSW) is developed and validated. This model assumes that ultimate mineralisation of the organic component of the waste occurs in three steps, namely solubilisation of particulate matter, fermentation to volatile organic acids (modelled as acetic acid) along with liberation of carbon dioxide and hydrogen, and methanogenesis from acetate and hydrogen. The model incorporates the ionic equilibrium equations arising due to dissolution of carbon dioxide, generation of alkalinity from breakdown of solids and dissociation of acetic acid. Rather than a charge balance, a mass balance on the hydronium and hydroxide ions is used to calculate pH. The flow of liquid through the bed is modelled as occurring through two zones-a permeable zone with high flushing rates and the other more stagnant. Some of the kinetic parameters for the biological processes were obtained from batch MSW digestion experiments. The parameters for flow model were obtained from residence time distribution studies conducted using tritium as a tracer. The model was validated using data from leach bed digestion experiments in which a leachate volume equal to 10% of the fresh waste bed volume was sequenced. The model was then tested, without altering any kinetic or flow parameters, by varying volume of leachate that is sequenced between the beds. Simulations for sequencing/recirculating 5 and 30% of the bed volume are presented and compared with experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.

Reconciliation through communication in intercultural encounters: potential or peril?

As we reflect on the events of September 11th and their aftermath, there is strong motivation in many places to improve intercultural and international relations through communication. This laudable aim implicates the long history of research into intercultural encounters, which has always bad this goal. To achieve it, researchers and trainers must go beyond conceptualizing intercultural encounters as like interpersonal ones, except that participants have different and sometimes conflicting cultural rules and values. We must develop programs to train metaskills in analyzing miscommunication and its negative consequences. This requires the recognition that, in many interethnic and intercultural contexts, participants are not. motivated to communicate well. In such cases, the larger sociopolitical situation must be addressed, or skills training may even exacerbate the conflict. It is also crucial to understand intercultural communication as simultaneously intergroup and interpersonal, to incorporate both aspects into interventions, and to advocate for such training to improve intercultural relations.

Jung and the dreaming: Analytical psychology's encounters with Aboriginal culture

This article reviews some contributions of the Jungian analytic tradition to indigenous ethnopsychiatric thought in Australia. The authors review Jung's writings on Aboriginal culture, then describe some of their own fieldwork findings. Acknowledging that the contemporary post-Jungian tradition is pluralist, they propose a notion of 'Jungian sensibility.' They discuss some of the ways in which the Jungian sensibility might contribute positively to Aboriginal mental health, with especial reference to theories of subjectivity, and note that some Aboriginal people find the Jungian world-view very compatible with the Aboriginal one.

Alternatives to peace keeping in Korea: the role of non-state actors and face-to-face encounters

Korea is one of the world's most volatile areas, not least because traditional UN mediation and peacekeeping missions are impossible. Having intervened in the Korean War on behalf of the southern side, the UN is a party to the conflict, rather than a neutral arbiter. The situation is particularly problematic because political interactions are characterized by a high degree of state-control over security policy. In both parts of the peninsula the state has, at least until recently, exercised the exclusive right to deal with the opponent on the other side of the hermetically divided peninsula. Given these domestic and international constrains, alternative approaches to conflict resolution are urgently needed. The recently proliferating literature on human security offers possible solutions, for it urges policy makers to view security beyond the conventional military-based defence of the state and its territory. Using such a conceptual framework, the essay assesses the potential significance non-state interactions between North and South, particularly those that promote communication, information exchange and face-to-face encounters. Even though these interactions remain limited, they are of crucial importance, for they provide an opportunity to reduce the stereotypical threat images that continue to fuel conflict on the peninsula.

Robust stability of sequential multi-input multi-output quantitative feedback theory designs

This paper re-examines the stability of multi-input multi-output (MIMO) control systems designed using sequential MIMO quantitative feedback theory (QFT). In order to establish the results, recursive design equations for the SISO equivalent plants employed in a sequential MIMO QFT design are established. The equations apply to sequential MIMO QFT designs in both the direct plant domain, which employs the elements of plant in the design, and the inverse plant domain, which employs the elements of the plant inverse in the design. Stability theorems that employ necessary and sufficient conditions for robust closed-loop internal stability are developed for sequential MIMO QFT designs in both domains. The theorems and design equations facilitate less conservative designs and improved design transparency.

An optimal sequential procedure for a buying-selling problem with independent observations

We consider a buying-selling problem when two stops of a sequence of independent random variables are required. An optimal stopping rule and the value of a game are obtained.