Temporal variation of crustal structure is key to our understanding of Earth processes on human timescales. Often, we expect that the most significant structural variations are caused by strong ground shaking associated with large earthquakes, and recent studies seem to confirm this. Here we test the possibility of using P receiver functions (PRF) to isolate structural variations over time. Synthetic receiver function tests indicate that structural variation could produce PRF changes on the same order of magnitude as random noise or contamination by local earthquakes. Nonetheless, we find significant variability in observed receiver functions over time at several stations located in northeastern Honshu. Immediately following the Tohoku-oki earthquake, we observe high PRF variation clustering spatially, especially in two regions near the beginning and end of the rupture plane. Due to the depth sensitivity of PRF and the timescales over which this variability is observed, we infer this effect is primarily due to fluid migration in volcanic regions and shear stress/strength reorganization. While the noise levels in PRF are high for this type of analysis, by sampling small data sets, the computational cost is lower than other methods, such as ambient noise, thereby making PRF a useful tool for estimating temporal variations in crustal structure.

<p dir="ltr">The escalating frequency and impact of natural disasters have necessitated the study of Humanitarian Logistics (HL) optimization to mitigate human and financial losses. This dissertation encompasses three pivotal studies that collectively seek to address some of the numerous gaps identified in the nascent literature of HL optimization, particularly in conflict-ridden and low-security environments. The first study conducts a comprehensive survey on the application of Multi-Criteria Decision Making (MCDM) methods in HL, identifying a significant gap between academic research and practical challenges, and highlighting underexplored areas within multicriteria optimization in HL. The second study introduces innovative deterministic and possibilistic models to improve the safety and security of humanitarian personnel by developing a vehicle routing model that minimizes the predictability of trips, a novel aspect in HL research. This includes the introduction of the Humanitarian Vehicle Routing Problem with Non-Routineness of Trips (HVRPNRT), creation of a unique index to measure trip routineness and the provision of an approximate closed-form solution for the aid allocation subproblem, and introduces a novel case study from the ongoing civil unrest in South Sudan. The third study presents a novel heuristic solution algorithm for the HVRPNRT, which is the first of its kind, and outperforms the commercial solver CPLEX on some instances. This algorithm offers near-optimal solutions with reduced computational times and maintains feasibility under stringent security conditions, thereby advancing the field of security-aware HL optimization. Collectively, these studies offer significant contributions to the field of HL optimization, providing a recent through survey of the field, novel practical models, methodologies, and an algorithm that address both operational efficiency and security challenges, in an effort to bridge the gap between theoretical research and real-world humanitarian needs.</p>

Background: The furniture industry is described as one of Sweden’s largest industries where Make-to-order manufacturing has grown in popularity. To succeed in the market, it becomes essential for furniture companies to cooperate with suppliers. The supply chain can be associated with uncertainties and to avoid delays, lead time uncertainty becomes an important aspect to take into account. To manage lead time uncertainty, a safety lead time can be used, which ensures that material is available, however it is a costly solution. Purpose: The purpose is to, with the use of a case company, investigate lead time uncertainty in a furniture manufacturing MTO company, with the hope of finding the causes that contribute to perceived lead time uncertainty. Based on possible causes, applicable approaches will be suggested where possible effects are also investigated. Both approaches and potential effects involve the case company as well as their suppliers ́ perspectives. Method: This research is based on a qualitative method with elements of a quantitative method. The research has been carried out at a case company and empirical evidence has been collected through interviews with both the case company and their suppliers. Subsequently, the research has started from the construction of explanation and pattern comparison in order to set theory against empirical evidence and thereby analysis to make conclusions. Conclusion: Through the study ́s first research question, suppliers are found to be the cause of perceived lead time uncertainty and the use of safety lead time. This is due to the fact that deliveries are sometimes late, as well as bad long-term planning when communicating delayed deliveries to the case company. In order to handle uncertainty from suppliers, three approaches are proposed through the second research question; documentation of delivery performance, forecasting within MTO and building trust between actors. The third research question shows the effects of the approaches, where common effects are reduced lead time uncertainty and reduced safety lead time. / Bakgrund: Möbelbranschen beskrivs vara en av Sveriges största branscher där Make-to-order tillverkning har ökat i popularitet. För att lyckas på marknaden blir det väsentligt för möbelföretag att samarbeta med leverantörer. Leveranskedjan kan vara förknippad med osäkerheter och för att undvika förseningar blir ledtidsosäkerhet en aspekt viktig att ta hänsyn till. För att hantera ledtidsosäkerhet kan en säkerhetsledtid användas, som säkrar upp att material finns tillgängligt men är en kostsam lösning. Syfte: Syftet är att med hjälp av ett fallföretag undersöka upplevd ledtidsosäkerhet i ett möbeltillverkande MTO företag, med förhoppning att finna orsaker som bidrar till upplevd ledtidsosäkerhet. Baserat på möjliga orsaker kommer tillämpbara tillvägagångssätt föreslås där potentiella effekter också undersöks. Både tillvägagångssätt och potentiella effekter involverar fallföretag samt deras leverantörers perspektiv. Metod: Studien har sin utgångspunkt av en kvalitativ metod med inslag av kvantitativ metod. Studien har utförts på ett fallföretag och genom intervjuer med fallföretaget och deras leverantörer har empiri samlats in. Därefter har studien utgått från uppbyggnad av förklaring samt mönsterjämförelse för att ställa teori mot empiri och därigenom analysera fram studiens slutsatser. Slutsats: Genom studiens första forskningsfråga konstateras leverantör som orsak till upplevd ledtidsosäkerhet samt användandet av en säkerhetsledtid. Detta till följd av att leveranser emellanåt är sena, samt dålig framförhållning vid kommunikation av försenade leveranser. För hantering av osäkerhet från leverantör föreslås vid andra forskningsfrågan tre tillvägagångssätt; dokumentation av leveransprecision, prognostisering inom MTO samt tillitsskapande mellan aktörer. Tredje forskningsfrågan visar på effekterna av tillvägagångssätten, där gemensamma effekter är en reducerad upplevd ledtidsosäkerhet samt minskat användande av säkerhetsledtid därtill.