Beplanning en die soeke na 'n nuwe ideaal

With the changing political dispensa­tion in South Africa, the ideological background of the profession (and therefore its legitimacy) was ques­tioned. The answer to the question why we plan, changed fundamentally with the advent of the ideal of an integrated new South Africa. Changing thinking about planning to accommo­date the dominant political ideology in South Africa, seems not to be in accordance with the world-wide trend to a more Small-scale Post-Modernistic society. The crisis in which planning thought finds itself world-wide, due to the detrimental effects of Large-scale Modernism, can and must be seen as an opportunity to re-evaluate the ideals of planning and to establish a small-scale alternative for the way in which man involves himself with his natural and cultural environment. Only if we succeed in this venture, will the planning profession be able to plan, in a sustainable way, the long-term future of our country and its people. Plan­ning will also be safeguarded against accusations of serving the ideal of a single political ideology.*This article is written in Afrikaans

A green open access optical distribution network with incremental deployment support

This paper proposes an optical distribution network (ODN) architecture for open access networks. The proposed scheme ensures co-existence of multiple business partners (BPs) e.g., service, network equipment, and infrastructure providers at different levels of the distribution network, along with physicallayer security. Further, physical-layer isolation is provided to each subscriber, preventing network disruption by malicious subscribers. The proposed open access ODN supports BPs with different granularities (sizes) and discourages monopoly; thus, allowing multiple BPs to co-exist. It also supports incremental deployability (ID) which allows the BPs to cope with an expanding user base. Thus, small BPs can take up a market share with reasonable initial investment and grow with differential expenditures. ID further allows us to incrementally scale up the power consumption as a function of the network load, making the architecture green. The proposed ODN is based on a passive optical network (PON) architecture resulting in low operational expenditures (OpEx) and high availability. Besides a new ODN architecture, a novel architecture for the optical line terminal (OLT), based on hybrid time and wavelength-division multiplexing (TWDM), is proposed. The BPs can adopt typical TWDM, wavelength division multiplexing, or the TWDM-based OLT architecture (introduced in this paper) over the proposed ODN

Entanglement between charge qubits induced by a common dissipative environment

We study entanglement generation between two charge qubits due to the strong coupling with a common bosonic environment (Ohmic bath). The coupling to the boson bath is a source of both quantum noise (leading to decoherence) and an indirect interaction between qubits. As a result, two effects compete as a function of the coupling strength with the bath: entanglement generation and charge localization induced by the bath. These two competing effects lead to a non-monotonic behavior of the concurrence as a function of the coupling strength with the bath. As an application, we present results for charge qubits based on double quantum dots.Comment: 9 pages, 7 figure

Participatory Experimentation with Energy Law:Digging in a ‘Regulatory Sandbox’ for Local Energy Initiatives in the Netherlands

To facilitate energy transition, regulators have devised ‘regulatory sandboxes’ to create a participatory experimentation environment for exploring revision of energy law in several countries. These sandboxes allow for a two-way regulatory dialogue between an experimenter and an approachable regulator to innovate regulation and enable new socio-technical arrangements. However, these experiments do not take place in a vacuum but need to be formulated and implemented in a multi-actor, polycentric decision-making system through collaboration with the regulator but also energy sector incumbents, such as the distribution system operator. Therefore, we are exploring new roles and power division changes in the energy sector as a result of such a regulatory sandbox. We researched the Dutch executive order ‘experiments decentralized, sustainable electricity production’ (EDSEP) that invites homeowners’ associations and energy cooperatives to propose projects that are prohibited by extant regulation. Local experimenters can, for instance, organise peer-to-peer supply and determine their own tariffs for energy transport in order to localize, democratize, and decentralize energy provision. Theoretically, we rely on Ostrom’s concept of polycentricity to study the dynamics between actors that are involved in and engaging with the participatory experiments. Empirically, we examine four approved EDSEP experiments through interviews and document analysis. Our conclusions focus on the potential and limitations of bottom-up, participatory innovation in a polycentric system. The most important lessons are that a more holistic approach to experimentation, inter-actor alignment, providing more incentives, and expert and financial support would benefit bottom-up participatory innovation

Intuitionistic Gödel-Löb Logic, à la Simpson:Labelled Systems and Birelational Semantics

We derive an intuitionistic version of Gödel-Löb modal logic (GL) in the style of Simpson, via proof theoretic techniques. We recover a labelled system, ℓIGL, by restricting a non-wellfounded labelled system for GL to have only one formula on the right. The latter is obtained using techniques from cyclic proof theory, sidestepping the barrier that GL’s usual frame condition (converse well-foundedness) is not first-order definable. While existing intuitionistic versions of GL are typically defined over only the box (and not the diamond), our presentation includes both modalities. Our main result is that ℓIGL coincides with a corresponding semantic condition in birelational semantics: the composition of the modal relation and the intuitionistic relation is conversely well-founded. We call the resulting logic IGL. While the soundness direction is proved using standard ideas, the completeness direction is more complex and necessitates a detour through several intermediate characterisations of IGL

Intuitionistic G\"odel-L\"ob logic, \`a la Simpson: labelled systems and birelational semantics

We derive an intuitionistic version of G\"odel-L\"ob modal logic ($\sf{GL}$) in the style of Simpson, via proof theoretic techniques. We recover a labelled system, $\sf{\ell IGL}$, by restricting a non-wellfounded labelled system for $\sf{GL}$ to have only one formula on the right. The latter is obtained using techniques from cyclic proof theory, sidestepping the barrier that $\sf{GL}$'s usual frame condition (converse well-foundedness) is not first-order definable. While existing intuitionistic versions of $\sf{GL}$ are typically defined over only the box (and not the diamond), our presentation includes both modalities. Our main result is that $\sf{\ell IGL}$ coincides with a corresponding semantic condition in birelational semantics: the composition of the modal relation and the intuitionistic relation is conversely well-founded. We call the resulting logic $\sf{IGL}$. While the soundness direction is proved using standard ideas, the completeness direction is more complex and necessitates a detour through several intermediate characterisations of $\sf{IGL}$.Comment: 25 pages including 8 pages appendix, 4 figure

Structure and dynamics of giant low surface brightness galaxies

Giant low surface brightness (GLSB) galaxies are commonly thought to be massive, dark matter dominated systems. However, this conclusion is based on highly uncertain rotation curves. We present here a new study of two prototypical GLSB galaxies: Malin 1 and NGC 7589. We re-analysed existing HI observations and derived new rotation curves, which were used to investigate the distributions of luminous and dark matter in these galaxies. In contrast to previous findings, the rotation curves of both galaxies show a steep rise in the central parts, typical of high surface brightness (HSB) systems. Mass decompositions with a dark matter halo show that baryons may dominate the dynamics of the inner regions. Indeed, a "maximum disk" fit gives stellar mass-to-light ratios in the range of values typically found for HSB galaxies. These results, together with other recent studies, suggest that GLSB galaxies are systems with a double structure: an inner HSB early-type spiral galaxy and an outer extended LSB disk. We also tested the predictions of MOND: the rotation curve of NGC 7589 is reproduced well, whereas Malin 1 represents a challenging test for the theory.Comment: 12 pages, 9 figures, accepted for publication in A&