Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the…
Abstract
Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.
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Zhuoyu Zhang, Lijia Zhong, Mingwei Lin, Ri Lin and Dejun Li
Docking technology plays a crucial role in enabling long-duration operations of autonomous underwater vehicles (AUVs). Visual positioning solutions alone are susceptible to…
Abstract
Purpose
Docking technology plays a crucial role in enabling long-duration operations of autonomous underwater vehicles (AUVs). Visual positioning solutions alone are susceptible to abnormal drift values due to the challenging underwater optical imaging environment. When an AUV approaches the docking station, the absolute positioning method fails if the AUV captures an insufficient number of tracers. This study aims to to provide a more stable absolute position visual positioning method for underwater terminal visual docking.
Design/methodology/approach
This paper presents a six-degree-of-freedom positioning method for AUV terminal visual docking, which uses lights and triangle codes. The authors use an extended Kalman filter to fuse the visual calculation results with inertial measurement unit data. Moreover, this paper proposes a triangle code recognition and positioning algorithm.
Findings
The authors conducted a simulation experiment to compare the underwater positioning performance of triangle codes, AprilTag and Aruco. The results demonstrate that the implemented triangular code reduces the running time by over 70% compared to the other two codes, and also exhibits a longer recognition distance in turbid environments. Subsequent experiments were carried out in Qingjiang Lake, Hubei Province, China, which further confirmed the effectiveness of the proposed positioning algorithm.
Originality/value
This fusion approach effectively mitigates abnormal drift errors stemming from visual positioning and cumulative errors resulting from inertial navigation. The authors also propose a triangle code recognition and positioning algorithm as a supplementary approach to overcome the limitations of tracer light positioning beacons.
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Malnutrition is widespread and affects about one-third of humanity. Increasing production and consumption of vegetables is an obvious pathway to improve dietary diversity…
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Malnutrition is widespread and affects about one-third of humanity. Increasing production and consumption of vegetables is an obvious pathway to improve dietary diversity, nutrition and health. This chapter analyses how climate change is affecting vegetable production, with a special focus on the spread of insect pests and diseases. A thorough literature review was undertaken to assess current global vegetable production, the factors that affect the spread of diseases and insect pests, the implications caused by climate change, and how some of these constraints can be overcome. This study found that climate change combined with globalization, increased human mobility, and pathogen and vector evolution has increased the spread of invasive plant pathogens and other species with high fertility and dispersal. The ability to transfer genes from wild relatives into cultivated elite varieties accelerates the development of novel vegetable varieties. World Vegetable Center breeders have embarked on breeding for multiple disease resistance against a few important pathogens of global relevance and with large evolutionary potential, such as chili anthracnose and tomato bacterial wilt. The practical implications of this are that agronomic practices that enhance microbial diversity may suppress emerging plant pathogens through biological control. Grafting can effectively control soil-borne diseases and overcome abiotic stress. Biopesticides and natural enemies either alone or in combination can play a significant role in sustainable pathogen and insect pest management in vegetable production system. This chapter highlights the importance of integrated disease and pest management and the use of diverse production systems for enhanced resilience and sustainability of highly vulnerable, uniform cropping systems.
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Shih‐Lin Wu, Jang‐Ping Sheu and Chung‐Chao Lee
This paper proposes a distributed multi‐channel MAC protocol which is an extension of our early work GRID [1]. GRID is characterized by the following features: (i) it integrates a…
Abstract
This paper proposes a distributed multi‐channel MAC protocol which is an extension of our early work GRID [1]. GRID is characterized by the following features: (i) it integrates a location‐aware channel assignment, (ii) it follows an “on‐demand” style to access the medium, (iii) the number of channels required is independent of the network topology, and (iv) no form of clock synchronization is required. The proposed protocol wants to further improve the GRID in two parts. First, we propose a fully distributed medium access mechanism without using a single control channel such that all of the network traffic can be distributed evenly over all data channels. Therefore, the network throughput will be increased significantly. Second, we can set the more suitable transmission range and GRID size by considering the factors of host density and packet arrival rate of the network within an specified area. Thus, all of channels will be reused more efficiently than GRID. Simulation results show that the throughput of our protocol is superior to GRID and IEEE 802.11.
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Abstract
Purpose
This paper seeks to present a new solution algorithm for updating of finite element models in structural dynamics. A random search method is applied to improving the correlation between the numerical simulation and the measured experimental data.
Design/methodology/approach
Dynamic finite element model updating may be considered as an optimization process. It is solved using modified accelerated random search (MARS) algorithm. The effectiveness of the approach is first tested on benchmark problems. Next, several objective function formulations for dynamic model updating in modal and frequency domains are investigated for numerically simulated vibrating beam. Finally, the algorithm is applied to a real beam‐like structure using measured modal data.
Findings
The MARS algorithm is able to provide very good results in a reduced time even for hard optimization problems. It behaves very well also for the FE dynamic model updating, highly coupled problems. The efficient updating criterion has been proposed and the approach has been validated experimentally.
Research limitations/implications
The method is supposed to be time consuming for large size or complicated objective function problems but the choice of optimization parameters can accelerate the convergence.
Practical implications
The MARS algorithm can be applied to model updating in civil and mechanical engineering.
Originality/value
This paper is the first to apply the MARS algorithm to the problem of FE model updating in dynamics and enables one to obtain very good results. Efficient criteria for model updating have been proposed.
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Sharifa Ezat Wan Puteh, Chamhuri Siwar, Rozita Hod, Azmawati Mohammed Nawi, Idayu Badilla Idris, Izzah Syazwani Ahmad, Nor Diana Mohd Idris, Nurul Ashikin Alias and Mohd Raihan Taha
River flood exposes the population to multiple attacks from the physical, mental, health risks and its related negative effects. This study focused on the Pahang River and the…
Abstract
River flood exposes the population to multiple attacks from the physical, mental, health risks and its related negative effects. This study focused on the Pahang River and the three worst-hit district population (Pekan, Kuantan and Temerloh). Tools on areas of self-perceived health symptoms, QOL, depression, PTSD and community empowerment were assessed. Semi-guided questionnaires were distributed to a total of 602 victims. Questions on health symptoms were asked to respondents (R) and household members (HM). PTSD screening, i.e., the Trauma Screening Questionnaire, was used. Depression was assessed through the Beck Depression Inventory (BDI). WHOQOL-BREF assessed four domains of QOL, i.e., physical activity, psychological, social relationships and environment. Community empowerment using the Individual Community Related Empowerment tool to assess five domains, i.e., self-efficacy, participation, motivation, intention and critical awareness. Prevalent disease showed that majority suffered from hypertension (11.0%) and diabetes (7.3%). Two main symptoms experienced were cough (R = 47.2%, HM = 43.7%) and flu (R = 42.7%, HM = 40.4). Monthly health expenditure was higher post flood. Purchase of prescription medications rose from MYR24.40 to 31.02. A total of 33 people were suspected to suffer from PTSD. Through BDI assessment, it was estimated that as many as 104 (17.3%) suffered overt (high) depression. The prevalence of QOL domains are as such: low physical activity was highest at 59%, low psychological activity at 53.3%, low social relationships at 43% and low environment at 45.2%. On community empowerment, low empowerment was seen on four domains: self-efficacy at 52%, participation at 55%, motivation at 54.2% and critical awareness at 74.4%. The domain with good intention and willing to participate was at 54%. Results indicate that the community was not adaptable to flood events. This is evident from high amount of experienced symptoms, low QOL (physical and psychological aspects) and empowerment (except intention). Proportion of PTSD and overt (high) depression was however quite low.
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The purpose of this paper is to review the study of social capital focused on the level at which it is embodied, cross-comparing two prominent camps that have emerged in the…
Abstract
Purpose
The purpose of this paper is to review the study of social capital focused on the level at which it is embodied, cross-comparing two prominent camps that have emerged in the social capital literature: a communal level and an individual level.
Design/methodology/approach
This paper reviews the intersections and departures between communal level and individual level conceptualizations of social capital according to the social dynamics of action within social exchanges that they stimulate, the processes by which social capital is activated/mobilized and the rewards they yield, and their linkages to inequality through network diversity.
Findings
This paper articulates new directions for future research in social capital: more analytical precision for studying returns to social capital; more efforts to transcend the individual-communal divide; the depreciation of social capital or tie decay; and recognizing the importance of ties whose value does not come from the ability to provide instrumental gain, but just from their very existence.
Originality/value
Social capital has informed many influential agendas in the social sciences, but the sheer volume of which has largely gone unscoped. This paper reviews this literature to provide an accessible introduction to social capital, organized by social processes foundational to sociology and a novel contribution to the literature by articulating new directions for future research in the area.
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Lu An, Chuanming Yu, Xia Lin, Tingyao Du, Liqin Zhou and Gang Li
The purpose of this paper is to identify salient topic categories and outline their evolution patterns and temporal trends in microblogs on a public health emergency across…
Abstract
Purpose
The purpose of this paper is to identify salient topic categories and outline their evolution patterns and temporal trends in microblogs on a public health emergency across different stages. Comparisons were also examined to reveal the similarities and differences between those patterns and trends on microblog platforms of different languages and from different nations.
Design/methodology/approach
A total of 459,266 microblog entries about the Ebola outbreak in West Africa in 2014 on Twitter and Weibo were collected for nine months after the inception of the outbreak. Topics were detected by the latent Dirichlet allocation model and classified into several categories. The daily tweets were analyzed with the self-organizing map technique and labeled with the most salient topics. The investigated time span was divided into three stages, and the most salient topic categories were identified for each stage.
Findings
In total, 14 salient topic categories were identified in microblogs about the Ebola outbreak and were summarized as increasing, decreasing, fluctuating or ephemeral types. The topical evolution patterns of microblogs and temporal trends for topic categories vary on different microblog platforms. Twitter users were keen on the dynamics of the Ebola outbreak, such as status description, secondary events and so forth, while Weibo users focused on background knowledge of Ebola and precautions.
Originality/value
This study revealed evolution patterns and temporal trends of microblog topics on a public health emergency. The findings can help administrators of public health emergencies and microblog communities work together to better satisfy information needs and physical demands by the public when public health emergencies are in progress.