Journal Staff

Additive manufacturing is a growing manufacturing technology that has lately transcended from mostly being used in prototype manufacturing to be used in conventional production. The transition has occurred with, among other technologies, Fused Deposit Modelling (FDM), developed by Stratasys for plastic manufacturing. The interest in replacing conventional methods (which for plastic is injection moulding) is increasing in Sweden and at the same time the demand for a more sustainable production increases. We have in this thesis managed to adapt a general framework for sustainability analysis with 31 indicators to a framework, for the analysis of the transition from injection moulding to FDM, with only 8 relevant indicators. This process was conduced through first establishing what sustainability is and mapped both production processes. Afterwards was the differences in the production processes analysed in regards to the general framework for sustainability analysis and a new framework, was created. Finally we analysed how firm management views frameworks for sustainability analysis, how they use them and how our framework complements the wrongful use that sometimes occur today.Adderande tillverkning är en stadigt växande tillverkningsteknik som på senare tid övergått från att huvudsakligen användas till prototyptillverkning till att användas för traditionell produktion. Övergången har bland annat skett med metoden Fused Deposit Modelling (FDM) som utvecklades av Stratasys och producerar i plast. Intresset för att ersätta traditionella metoder (vilket för plast är, bland annat, formsprutning) ökar i Sverige samtidigt som efterfrågan för en hållbar produktion ökar. Vi har i rapporten lyckats anpassa ett generellt ramverk för hållbarhetsanalys med 31 indikatorer till ett ramverk, för att analysera hållbarheten vid en övergång från formsprutning till FDM, med enbart 8 relevanta indikatorer. Denna process genomfördes genom att först etablera vad hållbarhet är och kartlagt de båda tillverkningsprocesserna. Därefter analyserades skillnaderna hos tillverkningssprocesserna utifrån de generella indikatorer för hållbarhetanalys och ett nytt ramverk skapades. Slutligen analyserades hur företagsledningar ser på ramverk för hållbarhetsanalys, hur de använder ramverken och hur vårt ramverk kompletterar det felaktiga användandet som ofta existerar idag

Schematic Maps and Indoor Wayfinding

Schematic maps are often discussed as an adequate alternative of displaying wayfinding information compared to detailed map designs. However, these depictions have not yet been compared and analyzed in-depth. In this paper, we present a user study that evaluates the wayfinding behaviour of participants either using a detailed floor plan or a schematic map that only shows the route to follow and landmarks. The study was conducted in an indoor real-world scenario. The depictions were presented with the help of a mobile navigation system. We analyzed the time it took to understand the wayfinding instruction and the workload of the users. Moreover, we examined how the depictions were visually perceived with a mobile eye tracker. Results show that wayfinders who use the detailed map spend more visual attention on the instructions. Nevertheless, the depiction does not help to solve the task: they also needed more time to orient themselves. Regarding the workload and the wayfinding errors no differences were found

Chiral spin liquid and emergent anyons in a Kagome lattice Mott insulator

Topological phases in frustrated quantum spin systems have fascinated researchers for decades. One of the earliest proposals for such a phase was the chiral spin liquid put forward by Kalmeyer and Laughlin in 1987 as the bosonic analogue of the fractional quantum Hall effect. Elusive for many years, recent times have finally seen a number of models that realize this phase. However, these models are somewhat artificial and unlikely to be found in realistic materials. Here, we take an important step towards the goal of finding a chiral spin liquid in nature by examining a physically motivated model for a Mott insulator on the Kagome lattice with broken time-reversal symmetry. We first provide a theoretical justification for the emergent chiral spin liquid phase in terms of a network model perspective. We then present an unambiguous numerical identification and characterization of the universal topological properties of the phase, including ground state degeneracy, edge physics, and anyonic bulk excitations, by using a variety of powerful numerical probes, including the entanglement spectrum and modular transformations.Comment: 9 pages, 9 figures; partially supersedes arXiv:1303.696

Analytical uncertainty propagation for multi-period stochastic optimal power flow

The increase in renewable energy sources (RESs), like wind or solar power, results in growing uncertainty also in transmission grids. This affects grid stability through fluctuating energy supply and an increased probability of overloaded lines. One key strategy to cope with this uncertainty is the use of distributed energy storage systems (ESSs). In order to securely operate power systems containing renewables and use storage, optimization models are needed that both handle uncertainty and apply ESSs. This paper introduces a compact dynamic stochastic chance-constrained DC optimal power flow (CC-OPF) model, that minimizes generation costs and includes distributed ESSs. Assuming Gaussian uncertainty, we use affine policies to obtain a tractable, analytically exact reformulation as a second-order cone problem (SOCP). We test the new model on five different IEEE networks with varying sizes of 5, 39, 57, 118 and 300 nodes and include complexity analysis. The results show that the model is computationally efficient and robust with respect to constraint violation risk. The distributed energy storage system leads to more stable operation with flattened generation profiles. Storage absorbed RES uncertainty, and reduced generation cost

Criticality and entanglement in non-unitary quantum circuits and tensor networks of non-interacting fermions

Models for non-unitary quantum dynamics, such as quantum circuits that include projective measurements, have been shown to exhibit rich quantum critical behavior. There are many complementary perspectives on this behavior. For example, there is a known correspondence between d-dimensional local non-unitary quantum circuits and tensor networks on a D=(d+1)-dimensional lattice. Here, we show that in the case of systems of non-interacting fermions, there is furthermore a full correspondence between non-unitary circuits in d spatial dimensions and unitary non-interacting fermion problems with static Hermitian Hamiltonians in D=(d+1) spatial dimensions. This provides a powerful new perspective for understanding entanglement phases and critical behavior exhibited by non-interacting circuits. Classifying the symmetries of the corresponding non-interacting Hamiltonian, we show that a large class of random circuits, including the most generic circuits with randomness in space and time, are in correspondence with Hamiltonians with static spatial disorder in the ten Altland-Zirnbauer symmetry classes. We find the criticality that is known to occur in all of these classes to be the origin of the critical entanglement properties of the corresponding random non-unitary circuit. To exemplify this, we numerically study the quantum states at the boundary of Haar-random Gaussian fermionic tensor networks of dimension D=2 and D=3. We show that the most general such tensor network ensemble corresponds to a unitary problem of non-interacting fermions with static disorder in Altland-Zirnbauer symmetry class DIII, which for both D=2 and D=3 is known to exhibit a stable critical metallic phase. Tensor networks and corresponding random non-unitary circuits in the other nine Altland-Zirnbauer symmetry classes can be obtained from the DIII case by implementing Clifford algebra extensions for classifying spaces.Comment: (25+14) pages, 19 figure

Immune Network Algorithm applied to the Optimization of Composite SaaS in Cloud Computing

Abstract-In order to serve the different application needs of the different Cloud users efficiently and effectively, a possible solution is the decomposition of the software or so-called composite SaaS (Software as a Service). A composite SaaS constitutes a group of loosely-coupled applications that communicate with each other to form higher-level functionality. The benefits to the SaaS providers are reduced delivery cost and flexible SaaS functions, and the benefit for the users is the decreased cost of subscription. For this to be achieved effectively, the optimization of the process is required in order to manage the SaaS resources in the data center efficiently. In this paper, the optimization task of composite SaaS is investigated using an Immune network optimization approach. The approach makes use of activation and suppression that are mimicked by the natural immune system triggering an immune response not only when antibodies interact with antigens but also when they interact with other antibodies. Experiments are conducted with a series of SaaS configurations and the proposed immune network algorithm is compared with a formerly proposed grouping genetic algorithm. The results show that the immune network algorithm outperforms the grouping genetic algorithm

Disrupting routines, facilitating control: exploring a change towards healthier food purchasing behaviour using a health app

Background: Unhealthier food consumption patterns constitute a leading risk factor for ill health. As an important step in the food consumption process, changing food purchasing may improve the healthfulness of dietary patterns. Changing behaviour towards healthier food purchasing may be viewed as effortful by consumers due to inadequate nutrition knowledge and skills which may inhibit their ability to make healthy choices within the supermarket. A dominance of routines and habits further impedes the use of deliberative decision-making, which makes information provision and goal-setting less effective. Behaviour change may be supported by disrupting undesirable behavioural patterns, building of personal resources, and reframing behavioural outcomes. This should prompt a greater use of reflective cognitive processes during food purchasing and aid healthier behaviour. However, there is limited evidence in relation to food purchasing. Given recent technological advances, apps offer a potential tool to facilitate such change. The high use of apps across social groups suggests that they may be appropriate for supporting behaviour change in lower socioeconomic groups. It is unclear if existing apps are appropriately designed or acceptable for use for the necessary time period, particularly for individuals from a lower socioeconomic background. Such knowledge gaps must be addressed to inform intervention design. This thesis aims to contribute to the theoretical understanding of the interplay between mobile app technology and behaviour change with food purchasing as the behaviour of interest, and a particular focus on women from a lower socioeconomic background. Methods: This thesis was grounded in a pragmatic philosophical perspective and consisted of four phases. In phase one, structural equation modelling was undertaken to examine the individual-level determinants of a healthy eating habit and the extent to which personal goals and self-control are linked to a healthy eating habit. A content analysis of existing apps was undertaken in phase two to examine their capacity to support healthier food purchasing behaviour. A structured analytical matrix was employed where relevant literature and theory was drawn upon. A phenomological methodology was used for the remaining two research phases. In phase three, the researcher explored the experience of using a health app to support healthier food purchasing behaviour. Women from a lower socioeconomic background were recruited and asked to use two, of three possible, apps over a two-week period. Subsequent semi-structured interviews explored the experience of using an app including those personal and app-related factors of importance. Inductive thematic analysis was conducted to explore common patterns across participants’ experiences. In the fourth research phase, the lived experience of changing purchasing behaviour was explored in women from a lower socioeconomic background using a health app over an 8-11 week period. Participants were asked to use one, of two possible, apps. Multiple data collection methods were employed to capture the lived experience of behaviour change and app use. At baseline, an accompanied shop, incorporating the use of think-aloud protocol and researcher observations, was conducted, followed by an in-depth interview and questionnaire completion. At the midway point, participants were asked to complete a reflective account of their experience thus far. They were also asked to share their till receipts for the study duration. At follow-up, an accompanied shop, in-depth interview, and questionnaire completion was again employed. Interpretative phenomenological analysis was conducted to gain insight into the behaviour change experience. Theoretical thematic analysis was employed to examine app use through the lens of engagement theory. Findings: Self-control and deliberative cognitive processes were central to maintaining a healthy eating habit. This challenges the current conceptualisation and suggests the need to view complex food behaviours as highly routinised; this is an important consideration for behaviour change. Food purchasing behaviour was not a primary focus of existing apps with behavioural outcomes, such as weight-loss, as their main goal. While existing apps have the potential to support healthier purchasing behaviour, there is an opportunity to broaden their capacity. Health apps, through the process of self-monitoring, problem solving, and behavioural prompts, disrupted existing purchasing patterns. This prompted the use of reflective cognitive processes such that purchasing behaviour was directed by personal resources and healthy food goals. However, the extent to which reflective cognition continued to be employed during behaviour change was influenced by the broader goal system in which healthy food goals resided. The importance of user engagement was highlighted through this exploratory research. Engagement was expressed at an intrinsic level as a sense of personal autonomy, an increased perceived capacity to change, and viewing the app as a confidential and empathetic ally. App features that facilitated their expression were considered to result in optimal engagement. Findings suggest that an individual’s involvement, in relation to healthy food, may act as a trigger for different phases of engagement as variations in goal saliency lead to flux in involvement levels. The importance of individual characteristics on app engagement was evident which emphasises the need to integrate tailored features into health apps to ensure that it is congruent with personal goals. Conclusions The present findings add to the existing understanding of the interplay between app technology and behaviour change. If appropriately designed health apps may facilitate a more conscious approach to food purchasing and support healthier purchasing behaviour. An individual’s goal system architecture may influence the extent to which the reflective cognitive system is employed during behaviour change, which progresses existing knowledge of the influence of goal systems on behaviour change. The present research contributes to the extant literature in relation to user engagement. The intrinsic expressions of engagement are proposed to result from different configurations of engagement dimensions which suggests an interaction between these dimensions rather than an isolated existence. The potential role of involvement as a trigger of engagement phases further challenges the current conceptualisation of engagement. Such findings add to the call for the use of alternative non-quantitative, context-specific means of measurement to adequately capture the engagement process. In conclusion, findings suggest the potential to expand existing behaviour change theory, to integrate components of engagement, for improved relevance in the app technology space. Future health app design must consider the individual user and incorporate tailored features to ensure user self-congruence and support continued engagement to facilitate change. Health apps may be an effective tool to support healthier food behaviours in women from a lower socioeconomic background but they may be most effective when implemented as part of a range of individual, community, and broader structural measures