Nowadays, new approaches to fabricate high-performance electrode materials are of vital importance in the renewable energy field. Here, we present a facile synthesis procedure of 3D Ni(OH)2/graphene hybrids for supercapacitors via synchronous electrochemical-assisted exfoliation and assembly of graphene on 3D Ni(OH)2 networks. With the assistance of an electric field, the electrochemically exfoliated high-quality graphene can be readily, uniformly assembled on the surfaces of 3D Ni(OH)2. When serving as electrode materials for supercapacitors, the resulting 3D Ni(OH)2/graphene composites exhibited excellent specific capacitance (263 mF cm−2 at 2 mA cm−2), remarkable rate capability and super-long cycle life (retention of 94.1% even after 10 000 continuous charge–discharge cycles), which may be attributed to their highly porous, stable 3D architecture as well as uniform, firm anchoring of ultrathin graphene on their surfaces. Therefore, our approach provides a facile strategy for the large-scale synthesis of high-quality graphene based composites towards various applications.

Thesis (Ph.D. (Statistics)) -- University of Limpopo, 2017 / Operations Research (OR) is a scientific method for developing quantitatively well-grounded recommendations for decision making. While it is true that it uses a variety of mathematical techniques, OR has a much broader scope. It is in fact a systematic approach to solving problems, which uses one or more analytical tools in the process of analysis. Over the years, OR has evolved through different stages. This study is motivated by new real-world challenges needed for efficiency and innovation in line with the aims and objectives of OR – the science of better, as classified by the OR Society of the United Kingdom. New real-world challenges are encountered on a daily basis from problems arising in the fields of water, energy, agriculture, mining, tourism, IT development, natural phenomena, transport, climate change, economic and other societal requirements. To counter all these challenges, new techniques ought to be developed. The growth of global markets and the resulting increase in competition have highlighted the need for OR techniques to be improved. These developments, among other reasons, are an indication that new techniques are needed to improve the day-to-day running of organisations, regardless of size, type and location. The principal aim of this study is to modify and develop new OR techniques that can be used to solve emerging problems encountered in the areas of linear programming, integer programming, mixed integer programming, network routing and travelling salesman problems. Distribution models, resource allocation models, travelling salesman problem, general linear mixed integer ii programming and other network problems that occur in real life, have been modelled mathematically in this thesis. Most of these models belong to the NP-hard (non-deterministic polynomial) class of difficult problems. In other words, these types of problems cannot be solved in polynomial time (P). No general purpose algorithm for these problems is known. The thesis is divided into two major areas namely: (1) network models and (2) resource allocation and distribution models. Under network models, five new techniques have been developed: the minimum weight algorithm for a non-directed network, maximum reliability route in both non-directed and directed acyclic network, minimum spanning tree with index less than two, routing through 0k0 specified nodes, and a new heuristic to the travelling salesman problem. Under the resource allocation and distribution models section, four new models have been developed, and these are: a unified approach to solve transportation and assignment problems, a transportation branch and bound algorithm for the generalised assignment problem, a new hybrid search method over the extreme points for solving a large-scale LP model with non-negative coefficients, and a heuristic for a mixed integer program using the characteristic equation approach. In most of the nine approaches developed in the thesis, efforts were done to compare the effectiveness of the new approaches to existing techniques. Improvements in the new techniques in solving problems were noted. However, it was difficult to compare some of the new techniques to the existing ones because computational packages of the new techniques need to be developed first. This aspect will be subject matter of future research on developing these techniques further. It was concluded with strong evidence, that development of new OR techniques is a must if we are to encounter the emerging problems faced by the world today. Key words: NP-hard problem, Network models, Reliability, Heuristic, Largescale LP, Characteristic equation, Algorithm.

Nowadays, new approaches to fabricate high-performance electrode materials are of vital importance in the renewable energy field. Here, we present a facile synthesis procedure of 3D Ni(OH)2/graphene hybrids for supercapacitors via synchronous electrochemical-assisted exfoliation and assembly of graphene on 3D Ni(OH)2 networks. With the assistance of an electric field, the electrochemically exfoliated high-quality graphene can be readily, uniformly assembled on the surfaces of 3D Ni(OH)2. When serving as electrode materials for supercapacitors, the resulting 3D Ni(OH)2/graphene composites exhibited excellent specific capacitance (263 mF cm−2 at 2 mA cm−2), remarkable rate capability and super-long cycle life (retention of 94.1% even after 10 000 continuous charge–discharge cycles), which may be attributed to their highly porous, stable 3D architecture as well as uniform, firm anchoring of ultrathin graphene on their surfaces. Therefore, our approach provides a facile strategy for the large-scale synthesis of high-quality graphene based composites towards various applications.

Large-scale and long-term planning imposes extensive requirements on governance efforts regardless of whether it involves public organisations, private organisations, or both. The proportions of such planning entangle many actors and stakeholders as system components within and around a complex system. These system components and conditions in a complex planning environment introduce a diverse variety of strategic objectives into the planning. This study investigates how strategic objectives can affect the governance of complex planning systems, particularly in the context of national critical infrastructure protection. For this purpose, this thesis concentrates on a national planning procedure, STYREL, which Sweden has recently implemented for the case of power shortages. This case involves various actors from the national, regional and local levels who act on behalf of both public and private organisations in a planning process with four-year intervals, and it thus constitutes a relevant subject for this study. The investigation entailed the collection of evidence from documents and interviews. First, publicly available Swedish documents regarding the case provided an understanding of the planning. Second, interviews with decision-makers who are entrusted with this planning at municipalities and county administrative boards as well as with a few planners from power grid providers offered a deeper comprehension of both the proceedings in practice and the strategic objectives involved in this complex system for planning of critical infrastructure protection. Particularly, the findings resulted in several conceptual models that demonstrate these understandings in more detail. A soft system model visualises the problem situation and contains several elements, such as the system components, interrelations and conditions. Moreover, a multi-level planning model specifies sources of uncertainty in the planning and decision-making process that are associated with an insufficient alignment of strategic objectives in the STYREL case. These decompositions of the Swedish planning environment – both horizontal and vertical – further enabled this study to identify significant parameters of the systemic conditions and strategic objectives involved in such complex planning environments that challenge their governance. The findings of this study suggest that the Swedish process is not yet fully developed. The investigation particularly indicates that a better alignment of strategic objectives is necessary to ensure a selection of adequate goals and means that advances the future usability of the produced plan, which in turn would legitimate and strengthen this complex planning process for critical infrastructure protection. / Storskalig och långvarig planering ställer höga krav på styrning. Detta gäller oavsett om offentliga eller privata organisationer, eller båda, är involverade. Omfattningen av en sådan planering engagerar många aktörer och intressenter som komponenter inom och omkring ett komplext system. Dessa komponenter samt deras villkor inbäddade i en komplex planeringsmiljö skapar en mångfald av strategiska målbilder som följer med in till planeringen. Denna studie undersöker därför hur strategiska målbilder kan påverka styrningen av komplexa planeringssystem, särskilt i kontexten av skyddet av kritisk infrastruktur i samhället. Undersökningen fokuserar på en nationell planeringsprocess, kallad STYREL, som avser beredskapsplanering för elbristsituationer och som implementerats i Sverige. Planeringsmiljön omkring STYREL är ett relevant studieobjekt eftersom den involverar många aktörer från nationell, regional och lokal nivå. Dessa aktörer representerar offentliga och privata organisationer i den planeringsprocess som genomförs med fyraårsintervaller. Under undersökningens gång har bevis samlats in från dokument och intervjustudier. Först har offentlig tillgängliga dokument om fallet skapat en förståelse om planeringen. Intervjuer med beslutsfattare som är ansvariga för STYREL-planeringen hos länsstyrelser, kommuner samt elnätsbolag har sedan genererat en ännu djupare förståelse. Detta gällande både förfaringssättet i praktiken och de strategiska målbilder som är involverade i detta komplexa system för planering av kritisk infrastruktur-skydd. Resultaten ledde i synnerhet till några konceptuella modeller vilka demonstrerar förståelserna på ett detaljerat sätt. En systemmodell visualiserar problemsituationen och innehåller flera element såsom systemkomponenter, relationer och villkor. En multinivå-planeringsmodell specificerar källor av osäkerhet i planerings- och beslutsprocessen vilka är associerade med en otillräcklig harmonisering av strategiska målbilder i STYREL fallet. Dekompositionerna av den svenska planeringsmiljön – både horisontellt och vertikalt – gjorde det möjligt att identifiera signifikanta parametrar av de systemiska villkor och strategiska målbilder som är involverade i dessa komplexa planeringsmiljöer och utmanar deras styrning. Resultaten av studien indikerar att den svenska processen inte är fullt utvecklat. Undersökningen visar att en bättre harmonisering av strategiska målbilder är nödvändig för att säkerställa ett urval av adekvata mål och medel som skulle utveckla den framtida användbarheten av den producerade planen. Denna skulle i sin tur legitimera och stärka den komplexa planeringsprocessen för skyddet av kritisk infrastruktur. Därtill kunde detta främja en målgruppsorienterad kommunikation om risker och relevanta åtgärder. / <p>Vid tidpunkten för framläggningen av avhandlingen var följande delarbeten opublicerade: delarbete 1 under granskning, delarbete 3 under granskning.</p><p>At the time of the defence the following papers were unpublished: paper 1 under review, paper 3 under review.</p>