Road planning with slime mould: If Physarum built motorways it would route M6/M74 through Newcastle

Plasmodium of Physarum polycephalum is a single cell visible by unaided eye. During its foraging behaviour the cell spans spatially distributed sources of nutrients with a protoplasmic network. Geometrical structure of the protoplasmic networks allows the plasmodium to optimize transfer of nutrients between remote parts of its body, to distributively sense its environment, and make a decentralized decision about further routes of migration. We consider the ten most populated urban areas in United Kingdom and study what would be an optimal layout of transport links between these urban areas from the "plasmodium's point of view". We represent geographical locations of urban areas by oat flakes, inoculate the plasmodium in Greater London area and analyse the plasmodium's foraging behaviour. We simulate the behaviour of the plasmodium using a particle collective which responds to the environmental conditions to construct and minimise transport networks. Results of our scoping experiments show that during its colonization of the experimental space the plasmodium forms a protoplasmic network isomorphic to a network of major motorways except the motorway linking England with Scotland. We also imitate the reaction of transport network to disastrous events and show how the transport network can be reconfigured during natural or artificial cataclysms. The results of the present research lay a basis for future science of bio-inspired urban and road planning.Comment: Submitted November (2009

Star Formation triggered by cloud-cloud collisions

We present the results of SPH simulations in which two clouds, each having mass $M_{_{\rm{o}}}\!=\!500\,{\rm M}_{_\odot}$ and radius $R_{_{\rm{o}}}\!=\!2\,{\rm pc}$, collide head-on at relative velocities of $\Delta v_{_{\rm{o}}} =2.4,\;2.8,\;3.2,\;3.6\;{\rm and}\;4.0\,{\rm km}\,{\rm s}^{-1}$. There is a clear trend with increasing $\Delta v_{_{\rm{o}}}$. At low $\Delta v_{_{\rm{o}}}$, star formation starts later, and the shock-compressed layer breaks up into an array of predominantly radial filaments; stars condense out of these filaments and fall, together with residual gas, towards the centre of the layer, to form a single large-$N$ cluster, which then evolves by competitive accretion, producing one or two very massive protostars and a diaspora of ejected (mainly low-mass) protostars; the pattern of filaments is reminiscent of the hub and spokes systems identified recently by observers. At high $\Delta v_{_{\rm{o}}}$, star formation occurs sooner and the shock-compressed layer breaks up into a network of filaments; the pattern of filaments here is more like a spider's web, with several small-$N$ clusters forming independently of one another, in cores at the intersections of filaments, and since each core only spawns a small number of protostars, there are fewer ejections of protostars. As the relative velocity is increased, the {\it mean} protostellar mass increases, but the {\it maximum} protostellar mass and the width of the mass function both decrease. We use a Minimal Spanning Tree to analyse the spatial distributions of protostars formed at different relative velocities.Comment: 10 pages, 11 figure

Extended mixed integer quadratic programming for simultaneous distributed generation location and network reconfiguration

Introduction. To minimise power loss, maintain the voltage within the acceptable range, and improve power quality in power distribution networks, reconfiguration and optimal distributed generation placement are presented. Power flow analysis and advanced optimization techniques that can handle significant combinatorial problems must be used in distribution network reconfiguration investigations. The optimization approach to be used depends on the size of the distribution network. Our methodology simultaneously addresses two nonlinear discrete optimization problems to construct an intelligent algorithm to identify the best solution. The proposed work is novel in that it the Extended Mixed-Integer Quadratic Programming (EMIQP) technique, a deterministic approach for determining the topology that will effectively minimize power losses in the distribution system by strategically sizing and positioning Distributed Generation (DG) while taking network reconfiguration into account. Using an efficient Quadratic Mixed Integer Programming (QMIP) solver (IBM ®), the resulting optimization problem has a quadratic form. To ascertain the range and impact of various variables, our methodology outperforms cutting-edge algorithms described in the literature in terms of the obtained power loss reduction, according to extensive numerical validation carried out on typical IEEE 33- and 69-bus systems at three different load factors. Practical value. Examining the effectiveness of concurrent reconfiguration and DG allocation versus sole reconfiguration is done using test cases. According to the findings, network reconfiguration along with the installation of a distributed generator in the proper location, at the proper size, with the proper loss level, and with a higher profile, is effective.  Вступ. Для мінімізації втрат потужності, підтримки напруги в допустимому діапазоні та покращення якості електроенергії у розподільчих мережах представлена реконфігурація та оптимальне розміщення розподіленої генерації. При дослідженнях реконфігурації розподільної мережі необхідно використовувати аналіз потоку потужності та передові методи оптимізації, які можуть вирішувати серйозні комбінаторні проблеми. Підхід до оптимізації, що використовується, залежить від розміру розподільної мережі. Наша методологія одночасно вирішує дві задачі нелінійної дискретної оптимізації, щоби побудувати інтелектуальний алгоритм для визначення найкращого рішення. Пропонована робота є новою, оскільки вона використовує метод розширеного змішано-цілочисельного квадратичного програмування (EMIQP), детермінований підхід до визначення топології, що ефективно мінімізує втрати потужності в системі розподілу за рахунок стратегічного визначення розмірів та позиціонування розподіленої генерації (DG) з урахуванням реконфігурації мережі. При використанні ефективного солвера Quadratic Mixed Integer Programming (QMIP) (IBM®) результуюча задача оптимізації має квадратичну форму. Щоб з'ясувати діапазон та вплив різних змінних, наша методологія перевершує передові алгоритми, описані в літературі, з точки зору одержаного зниження втрат потужності, згідно з великою числовою перевіркою, проведеною на типових системах з шинами IEEE 33 і 69 при трьох різних коефіцієнтах навантаження. Практична цінність. Вивчення ефективності одночасної реконфігурації та розподілу DG у порівнянні з єдиною реконфігурацією проводиться з використанням тестових прикладів. Відповідно до результатів, реконфігурація мережі разом із установкою розподіленого генератора в потрібному місці, належного розміру, з належним рівнем втрат і з більш високим профілем є ефективною

The Reliability and Power Quality Performance of Overhead Lines - with Reference to the Electrical Properties of Wood and Covered Conductors

In the information technology age, users of electricity services require both better reliability (fewer interruptions of supply) and better power quality (fewer disturbances, particularly voltage sags). The paper shows that the best way to reduce the frequency of interruptions and voltage sags is to reduce the number of faults on the distribution utility's low voltage and high voltage lines. Most utilities already use lines with wood poles and crossarms with the wood's electrical properties used to good effect. But a trend to 'maintenance-free' designs will inevitably increase the frequency of faults, particularly those caused by direct and nearby lightning and by wind-effects. The most effective way to reduce the frequency of faults on existing overhead lines would be to develop an acceptable technology for cost-effective retro-fitting of insulating covers on those spans of existing lines near trees

Feeder Reconfiguration in Distribution Networks Based on Convex Relaxation of OPF

The feeder reconfiguration problem chooses the on/off status of the switches in a distribution network in order to minimize a certain cost such as power loss. It is a mixed-integer nonlinear program and, hence, hard to solve. In this paper, we propose a heuristic algorithm that is based on the recently developed convex relaxation of the ac optimal power flow problem. The algorithm is computationally efficient and scales linearly with the number of redundant lines. It requires neither parameter tuning nor initialization for different networks. It successfully computes an optimal configuration on all four networks we have tested. Moreover, we have proved that the algorithm solves the feeder reconfiguration problem optimally under certain conditions for the case where only a single redundant line needs to be opened. We also propose a more computationally efficient algorithm and show that it incurs a loss in optimality of less than 3% on the four test networks

Livable neighborhoods for sustainable cities: Insights from Barcelona

The paper proposes a reflection on the superblock model - or supermanzana, in its well-known Spanish application - in the context of the debate on the 15-minute city and on the functional reorganization of mobility and public space to improve the quality of life, health and accessibility in urban areas. The impacts of car traffic on the livability of cities and neighborhoods, in terms of safety, air pollution, noise, but also in terms of consumption and quality of public space, are widely acknowledged. These issues are not new to the debate: since the first decades of the 20th century, with the advent and rapid diffusion of the automobile, concerns on the impacts of vehicular traffic and issues of urban livability and traffic separation have been raised by urban and transport planners. As a consequence, various models of neighborhood planning emerged, proposing solutions to limit these impacts. The supermanzana model takes up the principles of neighborhood planning by identifying a main road network and setting up a system of superblocks within the meshes of this network, in order to improve accessibility, equity, health and livability; it aims on the one hand to transform public spaces at the neighborhood level and on the other hand to reorganize the existing urban structure. The application of the supermanzana model in Barcelona offers an interesting contribution to the debate on the 15-minute city, showing how the principle of traffic separation can be applied to existing, dense urban contexts, reclaiming public space to more livable neighborhoods and sustainable cities. The analysis of the case study of Barcelona can contribute to research and policy, learning from this experience and especially from the critical issues that emerged

Process mapping and optimization of the process flows of a furniture manufacturing company in Zimbabwe using machine distance matrices

Abstract: Appropriate arrangement of machinery in a manufacturing environment can have a positive impact on the productivity of a company. A detailed work study carried out at a furniture manufacturing company revealed that parts travelled long distances before the final product is produced owing to the positions of machinery and crisscrossing process flows. This paper looks at how the plant layout was re-organized by mapping process flows and regrouping of the machinery according to their functions and products using machine distance matrices. Challenges relating to the plant layout, process flows, materials handling and transportation as well as assembly procedures were established, coupled with grouping machines according to functions and the least distance between interacting workstations. Using the machine distance matrices, processes were mapped and equipment reorganized to allow for continuous flow of production, resulting in significant reductions in transportation distances among interacting workstations and elimination of crisscrossing process paths