Hasil untuk "Shipment of goods. Delivery of goods"

Vangelis Tsioumas, Peter J. Stavroulakis, Dimitrios V. Lyridis et al.

Abstract The maritime industry stands on the brink of a transformative era, driven by technological innovation. This study delves into the realm of JIT policies, exploring their economic impact. According to the findings of relevant studies, there are clear economic and environmental benefits arising from the just-in-time arrival of ships. However, a comprehensive assessment of how the implementation of JIT systems affects freight rates requires additional considerations. Focusing on the economic aspect, it is well documented that speed optimization reduces fuel expenses and port congestion. However, the relevant literature has not accounted for the combined impact of lower average speeds and shorter port waiting times on the expected earnings of ship operators. The present study addresses this gap by providing a quantifiable measure of this impact. For this purpose, a Random Forest model is built, with the Capesize freight rate on a key route serving as the dependent variable. The independent variables comprise the Capesize average sailing speed and the Port Congestion Index for this type of vessel. The model also includes control variables that correspond to supply and demand factors. Within this framework, we conduct scenario analysis for different levels of sailing speeds and port congestion, stemming from the implementation of a JIT system. The results indicate that freight rates can be reduced by up to 11%, revealing a threshold effect. The findings can help ship operators and other stakeholders conduct a more comprehensive assessment of the economic impact of JIT systems, taking into consideration the interplay of all pertinent factors.

Laura N.A. Amoah, Aluta Mlonzi

Background: Port efficiency is a key determinant of competitiveness in global trade, as efficient ports enable faster cargo movement, reduced vessel turnaround times, and improved logistics performance. To maintain competitiveness, ports must continuously examine and enhance their productivity factors. Objectives: This study aimed to achieve two objectives: firstly, to explore the factors influencing port productivity at the Port of Ngqura in South Africa; and secondly, to propose strategic recommendations that could assist management in enhancing operational efficiency and overall performance. Method: A qualitative research approach was employed, using semi-structured interviews with participants from Transnet Port Terminals (TPT) and the Transnet National Ports Authority (TNPA). Guided by the principles of information power and saturation reasoning, ten participants were purposively selected to provide rich insights into productivity-related issues at the Port of Ngqura. Results: Findings revealed that port productivity is influenced by equipment reliability, technological advancement, human resource capacity and infrastructure adequacy. Shortcomings in equipment, infrastructure and workforce stability were identified as major challenges limiting operational effectiveness. Conclusion: Improving port productivity requires investment in modern equipment, technology upgrades, and infrastructure improvements. Furthermore, addressing human resource challenges related to resignations, voluntary separation plans (VSPs) and contract terminations through effective planning is essential. Contribution: The study contributes to port management and supply chain literature by providing context-specific insights into productivity determinants at the Port of Ngqura and offering evidence-based recommendations for enhancing efficiency and competitiveness within South Africa’s maritime sector.

Hiroyasu Ando, Akihiro Nishi, Mark S. Handcock

Repeated small dynamic networks are integral to studies in evolutionary game theory, where networked public goods games offer novel insights into human behaviors. Building on these findings, it is necessary to develop a statistical model that effectively captures dependencies across multiple small dynamic networks. While Separable Temporal Exponential-family Random Graph Models (STERGMs) have demonstrated success in modeling a large single dynamic network, their application to multiple small dynamic networks with less than 10 actors, remains unexplored. In this study, we extend the STERGM framework to accommodate multiple small dynamic networks, offering an approach to analyzing such systems. Taking advantage of the small network sizes, our proposed approach improves accuracy in statistical inference through direct computation, unlike conventional approaches that rely on Markov Chain Monte Carlo methods. We demonstrate the validity of this framework through the analysis of a networked public goods experiment into individual decision-making about cooperation and defection. The resulting statistical inference uncovers novel insights into the dynamics of social dilemmas, showcasing the effectiveness and robustness of this modeling and approach.

Mienke Knipe, Stephan Krygsman

Background: Transport affordability is a significant concern for South African households, who spend nearly a fifth of their budgets on transport. Contributing factors include a lack of affordable public transport options and spatial mismatch. Since 2015, stagnating national budgets and a declining share allocated to the transport portfolio have exacerbated household transport expenses, limiting economic mobility. Objectives: This article examines how changes in household transport expenses impact other essential expenses such as food, housing, clothing, recreation and education. Understanding these expenditure trade-offs provides insights for policy, especially as the National Public Transport Subsidy Policy is being prepared. Method: Using data from the Living Conditions Survey of 2014/2015, the study applies fractional logit regression models to estimate the impact of varying household transport expenses on other expenditure categories across diverse household demographics. Results: Findings indicate that increased household transport expenses significantly reduces allocations to essential items, notably food and housing, with the effects varying by income level, settlement type, and household composition. Conclusion: A core recommendation is to reduce transport expenses for low-income households through government intervention as this will increase these, mostly previously disadvantaged households’, economic mobility. Contribution: Results show that if low-income households allocate no more than 10% of their expenditure budgets to transport, they could potentially increase their expenditure share on food (+1.30%) housing (+1.18%) clothing (+0.86%) recreation (+0.31%) and education (+0.08%).

Lovemore Motsi, Baldreck Chipangura

Background: Transporting the urban population in South African cities is chaotic because of traffic congestion, and one possible solution is the adoption of transport management systems to manage the timely picking and dropping of passengers by metered taxi operators. Objectives: This study examined factors that influence the South African metered taxi entrepreneurs’ willingness to adopt transport management systems (TWTMS). Method: This is a quantitative study that collected data from 253 metered taxi entrepreneurs from Sandton in the Johannesburg metropolitan area, South Africa. This study tested 14 hypotheses using regression analysis. Results: Attitude towards use had an insignificant relation with behavioural intention (BI); however, BI had a significant relationship with TWTMS. There were four factors that directly determined BI, which are perceived usefulness, perceived safety, perceived convenience and perceived trust. Conclusion: The results of this study suggest that taxi entrepreneurs will adopt transport management systems if they find the system useful, safe to use, convenient and trustworthy. Contribution: This study uncovered factors that influence the adoption of transport management systems by metered taxi entrepreneurs. Therefore, software developers should incorporate these factors when designing transport management systems so that acceptance can be improved.

Nirbhay Patil, Jean-Philippe Bouchaud

Rising inequalities around the globe bring into question our economic systems and the origin of such inequalities. Here we propose a toy agent-based model where each entity is simultaneously producing and consuming indivisible goods. We find that the system exhibits a non-trivial phase transition beyond which a market clearing equilibrium exists but becomes dynamically unreachable. When production capacity exceeds a threshold and adapts too slowly, some agents cannot sell all their goods. This leads to global price deflation and induces strong wealth inequalities, with the spontaneous separation of the population into a rich class and a poor class. We explore ways to alleviate poverty in this model and whether they have real life significance.

Benedikt Valentin Meylahn

We study interpersonal trust by means of the all-or-nothing public goods game between agents on a network. The agents are endowed with the simple yet adaptive learning rule, exponential moving average, by which they estimate the behavior of their neighbors in the network. Theoretically we show that in the long-time limit this multi-agent reinforcement learning process always eventually results in indefinite contribution to the public good or indefinite defection (no agent contributing to the public good). However, by simulation of the pre-limit behavior, we see that on complex network structures there may be mixed states in which the process seems to stabilize before actual convergence to states in which agent beliefs and actions are all the same. In these metastable states the local network characteristics can determine whether agents have high or low trust in their neighbors. More generally it is found that more dense networks result in lower rates of contribution to the public good. This has implications for how one can spread global contribution toward a public good by enabling smaller local interactions.

Jessie R. Smith, Epaminondas Mastorakos

An energy systems comparison of grid-electricity derived liquid hydrogen (LH2) and liquid ammonia (LNH3) is conducted to assess their relative potential in a low-carbon future. Under various voyage weather conditions, their performance is analysed for use in cargo transport, energy vectors for low-carbon electricity transport, and fuel supply. The analysis relies on literature projections for technological development and grid decarbonisation towards 2050. Various voyages are investigated from regions such as North America (NA), Europe (E), and Latin America (LA), to regions projected to have a higher electricity and fuel grid carbon intensity (CI) (i.e., Asia Pacific, Africa, the Middle-East, and the CIS). In terms of reducing the CI of electricity and fuel at the destination port, use of LH2 is predicted to be favourable relative to LNH3, whereas LNH3 is favourable for low-carbon transport of cargo. As targeted by the International Maritime Organisation, journeys of LNH3 cargo ships originating in NA, E, and LA achieve a reduction in volumetric energy efficiency design index (kg-CO2/m3-km) of at least 70% relative to 2008 levels. The same targets can be met globally if LH2 is supplied to high CI regions for production of LNH3 for cargo transport. A future shipping system thus benefits from the use of both LH2 and LNH3 for different functions. However, there are additional challenges associated with the use of LH2. Relative to LNH3, 1.6 to 1.7 times the number of LH2 ships are required to deliver the same energy. Even when reliquefaction is employed, their success is reliant on the avoidance of rough sea states (i.e., Beaufort Numbers >= 6) where fuel depletion rates during a voyage are impractical.

Solon Sehn

O presente artigo estuda a responsabilidade tributária do transportador marítimo no direito brasileiro, aplicando as limitações constitucionais para a definição da responsabilidade tributária na análise da constitucionalidade do art. 32, I, do Decreto-Lei nº 37/1966.

Shaily Mishra, Manisha Padala, Sujit Gujar

Fair resource allocation is an important problem in many real-world scenarios, where resources such as goods and chores must be allocated among agents. In this survey, we delve into the intricacies of fair allocation, focusing specifically on the challenges associated with indivisible resources. We define fairness and efficiency within this context and thoroughly survey existential results, algorithms, and approximations that satisfy various fairness criteria, including envyfreeness, proportionality, MMS, and their relaxations. Additionally, we discuss algorithms that achieve fairness and efficiency, such as Pareto Optimality and Utilitarian Welfare. We also study the computational complexity of these algorithms, the likelihood of finding fair allocations, and the price of fairness for each fairness notion. We also cover mixed instances of indivisible and divisible items and investigate different valuation and allocation settings. By summarizing the state-of-the-art research, this survey provides valuable insights into fair resource allocation of indivisible goods and chores, highlighting computational complexities, fairness guarantees, and trade-offs between fairness and efficiency. It serves as a foundation for future advancements in this vital field.

Cyrus Cousins, Vignesh Viswanathan, Yair Zick

We study the problem of fairly allocating a set of indivisible goods among agents with {\em bivalued submodular valuations} -- each good provides a marginal gain of either $a$ or $b$ ($a < b$) and goods have decreasing marginal gains. This is a natural generalization of two well-studied valuation classes -- bivalued additive valuations and binary submodular valuations. We present a simple sequential algorithmic framework, based on the recently introduced Yankee Swap mechanism, that can be adapted to compute a variety of solution concepts, including max Nash welfare (MNW), leximin and $p$-mean welfare maximizing allocations when $a$ divides $b$. This result is complemented by an existing result on the computational intractability of MNW and leximin allocations when $a$ does not divide $b$. We show that MNW and leximin allocations guarantee each agent at least $\frac25$ and $\frac{a}{b+2a}$ of their maximin share, respectively, when $a$ divides $b$. We also show that neither the leximin nor the MNW allocation is guaranteed to be envy free up to one good (EF1). This is surprising since for the simpler classes of bivalued additive valuations and binary submodular valuations, MNW allocations are known to be envy free up to any good (EFX).

Mehrnaz Ashrafi, Jane Lister, David Gillen

The discussion around shipping decarbonization has accelerated rapidly in 2020 and 2021. The growing studies on alternative marine fuels based on different criteria are indicative of both the complexities involved in marine fuels evaluation and absence of a consistent framework for assessment of alternative marine fuels from a holistic perspective. There is a recent call for an integrated evaluation model for alternative marine fuels with respect to economic, environmental, and social criteria. In this study, we develop and present a comprehensive and integrated set of sustainability criteria that are relevant for evaluating alternative marine fuels. First, we provide an overview of different alternative marine fuel pathways and assess the current challenges associated with adopting alternative marine fuels. Second, we develop 18 sustainability criteria, identified through the academic and trade literature and validated through a multi-stakeholder participatory approach (based on the input from 70 maritime experts), for a systematic and consistent evaluation of marine fuels. Third, based on an in-depth survey, we evaluate maritime stakeholder perspectives on the importance of sustainability criteria. And finally, we provide a discussion of key policy implications and areas for future studies. Our analysis reveals the current degree of agreement amongst maritime stakeholders in the debate about the importance of multiple, and often conflicting, criteria for evaluating marine fuels; the top five most important criteria are regulatory compliance, life cycle GHG, fuel cost, air pollution, and occupational health and safety. The analysis also looks at the importance ranking of each criterion from the perspective of individual maritime stakeholder groups. These findings provide decision-makers with a platform to understand priorities and interests of maritime stakeholder groups for the choice of marine fuels.

Márcio Luís da Silva Carneiro

O Planejamento Espacial Marinho (PEM) pode ser entendido como um instrumento público, multissetorial, jurídico e prático que organiza o uso compartilhado, eficiente, harmônico e sustentável dos mares. A regulação de suas várias áreas de atuação: transporte marítimo, energia renovável, conservação/proteção marinha, mineração, pesca, aquicultura, exploração de óleo e gás e defesa militar, promoverá a geração de divisas e empregos no Brasil trazendo a segurança jurídica necessária aos investidores nacionais e internacionais fomentando a economia sem desrespeitar a salvaguarda de interesses estratégicos e de defesa nacional. O presente artigo tem como objetivo analisar como a regulação dessas áreas impactará positivamente na economia do país. Para chegar a esta conclusão foram feitas pesquisas junto à Comissão Interministerial para os Recursos do Mar (CIRM) além dos poucos estudos existentes sobre o tema tendo em vista o PEM ainda não ter sido aprovado.

Ioannis Caragiannis, Vasilis Gkatzelis, Alexandros Psomas et al.

The problem of fair division known as "cake cutting" has been the focus of multiple papers spanning several decades. The most prominent problem in this line of work has been to bound the query complexity of computing an envy-free outcome in the Robertson-Webb query model. However, the root of this problem's complexity is somewhat artificial: the agents' values are assumed to be additive across different pieces of the "cake" but infinitely complicated within each piece. This is unrealistic in most of the motivating examples, where the cake represents a finite collection of homogeneous goods. We address this issue by introducing a fair division model that more accurately captures these applications: the value that an agent gains from a given good depends only on the amount of the good they receive, yet it can be an arbitrary function of this amount, allowing the agents to express preferences that go beyond standard cake cutting. In this model, we study the query complexity of computing allocations that are not just envy-free, but also approximately Pareto optimal among all envy-free allocations. Using a novel flow-based approach, we show that we can encode the ex-post feasibility of randomized allocations via a polynomial number of constraints, which reduces our problem to solving a linear program.

Jose L. Tongzon, Hong-Oanh Nguyen

It is well known that the international logistics and supply chains are subject to the domination of seaports and shipping lines each with increasingly significant market power. This implies that international supply chains, which typically involves sea transport as a key chain segment, could be subject to the double marginalisation problem. This means, chain operators are likely subject to both technical and allocative efficiency issues. The former is related to the use of inputs in production and distribution, and the latter is generally related to the market structure that affects resource allocation. The current study seeks to study the simultaneous relationships between three components, namely logistics integration, technical efficiency, and allocative efficiency in international container shipping. Exploratory factor analysis and structural equation modelling are conducted using data collected from a survey of global shipping lines. The analysis results show that logistics integration comprises of two main interrelated aspects, namely relational integration, and operational integration. It has significant effects on both technical and allocative efficiency. Technical efficiency and market contestability are affected by relational integration, while allocative efficiency and infrastructure capacity are affected by operational integration. Based on the analysis results, implications for port, terminals and stakeholders are also discussed.

Victor-Alexandru Darvariu, Stephen Hailes, Mirco Musolesi

Public goods games represent insightful settings for studying incentives for individual agents to make contributions that, while costly for each of them, benefit the wider society. In this work, we adopt the perspective of a central planner with a global view of a network of self-interested agents and the goal of maximizing some desired property in the context of a best-shot public goods game. Existing algorithms for this known NP-complete problem find solutions that are sub-optimal and cannot optimize for criteria other than social welfare. In order to efficiently solve public goods games, our proposed method directly exploits the correspondence between equilibria and the Maximal Independent Set (mIS) structural property of graphs. In particular, we define a Markov Decision Process which incrementally generates an mIS, and adopt a planning method to search for equilibria, outperforming existing methods. Furthermore, we devise a graph imitation learning technique that uses demonstrations of the search to obtain a graph neural network parametrized policy which quickly generalizes to unseen game instances. Our evaluation results show that this policy is able to reach 99.5% of the performance of the planning method while being three orders of magnitude faster to evaluate on the largest graphs tested. The methods presented in this work can be applied to a large class of public goods games of potentially high societal impact and more broadly to other graph combinatorial optimization problems.

Ruslan Beysenbaev, Yuri Dus

The purpose of this study is to propose ways for improving the current Logistics Performance Index published by the World Bank. The Logistics Performance Index is based on a global survey of logistics experts, which can be biased towards a subjective view on different countries’ logistics systems, which leads to a potentially skewed rating. The authors propose a modified index that qualitatively and quantitatively represents an objective view of 159 countries’ logistics systems and subsystems, based on international statistical data, which can be used as a benchmarking tool for governments. Keywords: Logistics efficiency, Country-level logistics, Global logistics, Logistics Performance Index (LPI)

Erica Lindroth, Hà Huong, Rickard Bergqvist

Abstract Previous research have distinguished the risks of supply chain disruptions and the negative effect of supply chain disruption on operational performance in terms of sales, costs and inventory. However, few researchers have studied supply chain risk management and strategies in relation to port conflicts. The 2016 port conflict at a major logistics port in Scandinavia, the Port of Gothenburg, posed an opportunity to study risk management and strategies in the context of major port disruptions, in this case, a labour conflict. The fashion retail industry was affected especially hard due to the short product life cycles and this paper, by means of case study method and analysis, investigates five cases in order to understand how they were affected and what mitigation strategies was used. Results illustrates that during the port conflict, the percentage of increase in logistics cost ranged between 15% and 70%, greatly affected by what mitigation strategy was used by the case company.

Stephen Kruger

No abstract available.

Yong An Park, Tsz Leung Yip, Hong Gyue Park

Concerns have been raised around pilotage in Korea due to a rise in marine accidents in the 2010s. Since the late 2000s, a debate has been sparked on the most suitable age of retirement for Korean pilots. The debate has focused on the extension of retirement age of pilots from 65 to 68 and whether this will affect the probability of marine accidents. Therefore, it is crucial to calculate the probability of marine accidents in relation to different age groups of pilots. After collecting the data of marine accidents caused by pilot's negligence, the study suggests two measurements of probability of marine accidents during pilotage: on the basis of the number of pilotage services and the hours of pilotage services. The analysis finds that age is not the exclusive cause of pilotage marine accidents by the age group over 65. Keywords: Pilotage, Marine Accident, Navigation, Aging, Probability, Korea