Dynamic Scaling, Data-collapse and Self-Similarity in Mediation-Driven Attachment Networks

Recently, we have shown that if the $i$th node of the Barab\'{a}si-Albert (BA) network is characterized by the generalized degree $q_i(t)=k_i(t)t_i^\beta/m$, where $k_i(t)\sim t^\beta$ and $m$ are its degree at current time $t$ and at birth time $t_i$, then the corresponding distribution function $F(q,t)$ exhibits dynamic scaling. Applying the same idea to our recently proposed mediation-driven attachment (MDA) network, we find that it too exhibits dynamic scaling but, unlike the BA model, the exponent $\beta$ of the MDA model assumes a spectrum of value $1/2\leq \beta \leq 1$. Moreover, we find that the scaling curves for small $m$ are significantly different from those of the larger $m$ and the same is true for the BA networks albeit in a lesser extent. We use the idea of the distribution of inverse harmonic mean (IHM) of the neighbours of each node and show that the number of data points that follow the power-law degree distribution increases as the skewness of the IHM distribution decreases. Finally, we show that both MDA and BA models become almost identical for large $m$.Comment: 8 pages, 8 captioned figure

Understanding and Responding to Climate Change: An Analysis of the Sundarbans World Heritage Area

Examining the understandings of and responses to anthropogenic climate change is important to help climatically vulnerable communities enhance their resilience. Lack of climate change understanding is an obstacle to appropriate climate response. Social understandings of climate change consist of general awareness, knowledge, and risk perceptions. Responses to climate change are derived from the understandings of the members of a society about the impacts and risks of climate change. The typical strategies in response to climate change are mitigation, adaptation, and resilience building. Responding to climate change is necessary at every scale to enhance the resilience of social and ecological systems. Climate change responses driven by management agencies are often helpful for vulnerable marginal communities, but not all the management interventions contribute to resilience equally. This research addresses the highly climatically vulnerable UNESCO World Heritage Sundarbans mangrove forest area (Bangladesh and India) as the study context. The mangroves biodiversity of the Sundarbans is important for buffering climate events, as well as for forest resource collection and tourism. The existing literature about the understandings of climate change of different key stakeholder groups of the Sundarbans is very limited. The available literature informs that awareness of climate change is low in the vulnerable Sundarbans area. The effectiveness of existing response strategies, particularly for adaptation to climate change, needs to be understood in relation to the efficient use of limited resources of those developing countries. It is also unknown how the Sundarbans World Heritage helps local people to think about and act in response to climate change. To fill these knowledge gaps, the aim of this thesis is to examine the social understandings of climate change and responses of management agencies to climate change in the Bangladesh Sundarbans including how the Sundarbans World Heritage Area is managed by Bangladesh and India. In doing so, a constructivist research paradigm is adopted aligning with a relativist ontology, subjectivist epistemology and qualitative methodology to explore understandings of and responses to climate change in the Sundarbans. Semi-structured interviews were conducted with 42 stakeholders including community people, conservation and management agencies, tourism management organisations, tourism business operators, and tourists. Thematic analysis was utilised to analyse the qualitative materials of the interview programme. A range of documents including policy papers is analysed to validate and enrich the empirical materials. The findings of this research indicate that the stakeholders of the Bangladesh Sundarbans believe that climate change is anthropogenic, they have the first-hand experience of changes in the weather system. The degree of climate risk perceptions of the stakeholders can be defined by their relative vulnerabilities and adaptive capacity. The core response to climate change in the Bangladesh Sundarbans is adaptation where sustainability depends on how the adaptation interventions contribute to resilience. In the cross-border comparative analysis, this research finds that both Bangladesh and India focus on conserving the forest ecosystem in response to climate change, but legal enforcement systems, politics, and governance systems are shaping the success of conservation management. Overall, the thesis argues that the social resilience and ecological resilience of the Sundarbans are highly related, and tourism can be utilised for resilience building in the vulnerable World Heritage area. This thesis addresses several theoretical and empirical knowledge gaps in the current literature in the context of developing nations. Firstly, it expands the theoretical components (awareness, knowledge, and risk perceptions) with related attributes of the social understandings of climate change. Secondly, it examines the effectiveness of climate adaptation functions based on their relative contribution to building resilience. Thirdly, it utilises a cross-border analysis between Bangladesh and India to critically examine the climate change management actions by the management agencies of the Sundarbans in terms of local vulnerabilities, forest biodiversity, World Heritage and tourism; and proposes three dimensions – community, forest, wildlife - of biodiversity conservation for resilience. These contributions have implications beyond the Bangladesh and Indian contexts, with application to a range of scenarios where researchers are seeking greater insights into understandings of and responses to climate change

Tourist-Group Consideration in Tourism Carrying Capacity Assessment: a New Approach for Saint Martin’s Island, Bangladesh

Everything has a capacity that it can tolerate or afford, beyond which it cannot serve. Tourism development and management should also be based on the recognition of the limits of a destination. As a result, tourist destinations must have their carrying capacity assessed and managed accordingly with a view to protecting them from getting exploited. In assessing tourism carrying capacity of a particular destination, the formulae given by Cifuentes (1992) and recommended by IUCN (Ceballos-Lascuráin, 1996) are widely used around the world. The formulae recognize the ‘necessary distance between two tourists’ as a factor that affects tourist satisfaction; and thus, consider it in assessing physical carrying capacity (PCC) of a destination. But Tran Nghi et al. (2007) argue that, the necessary distance between two groups on a route, as well as distance between two people, affects tourist's comfort and should be considered when assessing tourism carrying capacity (TCC). Tran Nghi et al. (2007) tried to make some adjustments to the formulae and used some techniques to consider tourists as in separate groups- not as an individual in a mass. When it is about assessing carrying capacity of a trekking trail or walking route where tourists have to be in a line one behind another, carrying capacity can be calculated for group of tourists using this adjusted formula. But when it is about a beach or a park where tourists are not in queues or lines- rather scattered in the whole area, carrying capacity cannot be calculated based on tourist-group, -rather as a mass. To calculate TCC of such destinations (beach/park) a new technique is proposed and used on the basic formulae of Cifuentes in this study.  This new technique is applied in calculating the TCC of the Saint Martin’s Island, the only coral island of Bangladesh, as a case study. Keywords: tourism carrying capacity (TCC), Cifuentes' methodology, tourist-group, Saint Martin’s Island

Effects of Polypropylene Bag on Storage Properties of Litchi (Litchi Chinensis Sonn.)

The present study was run in the laboratory of the Department of Horticulture, Bangladesh Agricultural University, Mymensingh during the period of 15 May to September, 2016. The objectives of the study were to determine the effects of different postharvest treatments on the storage behaviour of litchi. Eight postharvest treatments viz., control, fruits stored in 50µ polypropylene bag at ambient temperature, fruits stored in 75µ polypropylene bag at ambient temperature, fruits stored in 100µ polypropylene bag at ambient temperature, fruits stored at 4ºC temperature, fruits stored in 50µ polypropylene bag at 4ºC temperature, fruits stored in 75µ polypropylene bag at 4ºC temperature, fruits stored in 100µ polypropylene bag at 4ºC temperature were assigned to the litchi fruits. The single factor experiment was laid out in a completely randomized design with three replications. 75µ polypropylene bag at low temperature (4ºC) caused minimal weight loss, whereas, the untreated fruits exhibited maximal weight loss. The pericarp turned brown within 4 days of storage in the untreated fruits, while polypropylene bags helped keep its bright red colour, but microbial decay was evident at the end of the storage period. Different postharvest treatments showed highly significant variation in the shelf life of litchi. Among the treated and untreated fruits, 75µ polypropylene bag at low temperature (4ºC) treatment exhibited better storage performance. The fruits kept in 75µ polypropylene bag at 4°C showed the highest shelf life (20.67 days) followed by 50µ polypropylene bag at 4°C (20.33 days), and it was the lowest in the untreated fruits (3 days)

Experimental Study on Prefabricated Lightweight Composite Wall Panels under Flexural Loading

 The prefabricated lightweight wall panels have been widely used instead of brick walls in the modern construction industry of building due to its many advantages. As lightweight concrete is week under flexural loading, more reinforcement bars are required to improve the flexural strength of conventional lightweight wall panel. In this paper, steel studs/angles are proposed instead of reinforcement bars because the moment of inertial of steel stud/angle is higher than reinforcement bars. Experimental study has been conducted to investigate the flexural behaviour of proposed prefabricated lightweight composite (PLC) wall panels. Three samples of PLC wall panels are fabricated using lightweight concrete materials and studs. The parameters that are changed in the test specimens are material types (cold-form steel or carbon steel) and numbers of steel studs/angles. The test results show that the material types and numbers of steel studs/angles has significant impact on the flexural strength and stiffness of PLC wall panels

Flame retardant polymer composite and recent inclusion of magnesium hydroxide filler material : a bibliometric analysis towards further study scope

Fire accidents occur frequently and pose a great threat to high-rise buildings with flammable construction materials. Recently, researchers have been doing significant work on this topic to improve the flame retardancy of composites by adding inorganic metal hydroxide, such as magnesium hydroxide (MH), due to its higher thermal decomposition temperature and low toxicity. Research on flame retardant polymer composites with magnesium hydroxide is rapidly moving toward a more sustainable and safer future. This article provides a comprehensive review of the research trend along with the most cited publications. Most cited articles were chosen to observe the developments. The data collected from the Scopus database in the second week of March 2023 were also categorised to present country-wise improvement, the subject areas involved, and the author’s contribution to the topic. Some issues and challenges have also been highlighted from the analysis. By observing the research direction and highly cited articles, some of the further study scopes are also pointed out to develop fire-rated polymer composites for use as sustainable cladding materials for high-rise buildings

Dynamic scaling and stochastic fractal in nucleation and growth processes

A class of nucleation and growth models of a stable phase (S-phase) is investigated for various different growth velocities. It is shown that for growth velocities $v\sim s(t)/t$ and $v\sim x/\tau(x)$, where $s(t)$ and $\tau$ are the mean domain size of the metastable phase (M-phase) and the mean nucleation time respectively, the M-phase decays following a power law. Furthermore, snapshots at different time $t$ are taken to collect data for the distribution function $c(x,t)$ of the domain size $x$ of M-phase are found to obey dynamic scaling. Using the idea of data-collapse we show that each snapshot is a self-similar fractal. However, for $v={\rm const.}$ like in the classical Kolmogorov-Johnson-Mehl-Avrami (KJMA) model and for $v\sim 1/t$ the decay of the M-phase are exponential and they are not accompanied by dynamic scaling. We find a perfect agreement between numerical simulation and analytical results.Comment: 10 pages, 8 captioned figure