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Juan. Flores, José Cedeño González, Héctor Rodríguez, Mario Graff, Rodrigo Lopez-Farias, Felix Calderon
Published: 16 September 2019
by MDPI
Energies, Volume 12; doi:10.3390/en12183545

Abstract: This article presents a comparison of wind speed forecasting techniques, starting with the Auto-regressive Integrated Moving Average, followed by Artificial Intelligence-based techniques. The objective of this article is to compare these methods and provide readers with an idea of what method(s) to apply to solve their forecasting needs. The Artificial Intelligence-based techniques included in the comparison are Nearest Neighbors (the original method, and a version tuned by Differential Evolution), Fuzzy Forecasting, Artificial Neural Networks (designed and tuned by Genetic Algorithms), and Genetic Programming. These techniques were tested against twenty wind speed time series, obtained from Russian and Mexican weather stations, predicting the wind speed for 10 days, one day at a time. The results show that Nearest Neighbors using Differential Evolution outperforms the other methods. An idea this article delivers to the reader is: what part of the history of the time series to use as input to a forecaster? This question is answered by the reconstruction of phase space. Reconstruction methods approximate the phase space from the available data, yielding m (the system’s dimension) and τ (the sub-sampling constant), which can be used to determine the input for the different forecasting methods.
Tam Nguyen, Xiaoli Qin, Anh Dinh, Francis Bui
Published: 16 September 2019
by MDPI
Sensors, Volume 19; doi:10.3390/s19183997

Abstract: A novel R-peak detection algorithm suitable for wearable electrocardiogram (ECG) devices is proposed with four objectives: robustness to noise, low latency processing, low resource complexity, and automatic tuning of parameters. The approach is a two-pronged algorithm comprising (1) triangle template matching to accentuate the slope information of the R-peaks and (2) a single moving average filter to define a dynamic threshold for peak detection. The proposed algorithm was validated on eight ECG public databases. The obtained results not only presented good accuracy, but also low resource complexity, all of which show great potential for detection R-peaks in ECG signals collected from wearable devices.
Xiaodong Sun, Tsz Yip, Yui-Yip Lau
Published: 16 September 2019
by MDPI
Sustainability, Volume 11; doi:10.3390/su11185056

Abstract: Starting from the late 1960s, the cruise industry has appeared in two key regions, namely Europe and North America. However, the cruise industry has undergone fundamental changes which implies that the number of frequent cruisers is growing, with western travelers supposedly travelling to diverse cultures, attractive cruising destinations and exotic experiences in Southeast Asia for western travelers, and thus cruising in the Asian region has been happening at an enormous growing rate. Among the Asian regions, China is experiencing the fastest growth rates. Both Hong Kong and Shanghai established two cruise terminals which can be described as homeport cities in the 21st centuries. However, Hong Kong and Shanghai cruise terminals need to deal with neighboring competitors like Singapore, Japan, Vietnam, just to name but a few, in a challenging and dynamic environment. In order to examine Hong Kong and Shanghai’s potential evolution into an international cruise terminal hub, we suggest Connectivity, Regional Competitiveness, Utilization, Infrastructure, Security, Environmental Management (CRUISE) framework to seize attainable prospect of the external environment and investigate locational characteristics of cruise terminals in Hong Kong and Shanghai respectively. The first mover and sustainable competitive advantage will be performed. Academic and managerial implications of the research findings for cruise terminals are elaborated.
Mengde Zhou, Wei Liu, Linlin Tang, Zhuang Yao, Zhengquan Wen, Bing Liang, Zhenyuan Jia
Published: 16 September 2019
by MDPI
Sensors, Volume 19; doi:10.3390/s19183998

Abstract: In wind tunnel tests, the low-frequency and large-amplitude vibration of the cantilever sting result in poor test data in pitch plane and yaw plane, more seriously, even threatens the safety of wind tunnel tests. To ensure the test data quality, a multidimensional vibration suppression method is proposed to withstand the vibration from any direction, which is based on a system with stackable piezoelectric actuators and velocity feedback employing accelerometers. Firstly, the motion equation of the cantilever sting system is obtained by Hamilton’s principle with the assumed mode method. Then, the multidimensional active control mechanism is qualitatively analyzed and a negative velocity feedback control algorithm combined with a root mean square (RMS) evaluation method is introduced to realize active mass and active damping effect, meanwhile, a weight modification method is performed to determine the sequence number of the stacked piezoelectric actuators and the weight of control voltages in real time. Finally, a multidimensional vibration suppression system was established and verification experiments were carried out in lab and a transonic wind tunnel. The results of lab experiments indicate that the damping ratio of the system is improved more than 4.3 times and the spectrum analyses show reductions of more than 23 dB. In addition, wind tunnel test results have shown that for the working conditions (α = −4~10° with γ = 0° or α = −4~10° with γ = 45°) respectively at 0.6 Ma and 0.7 Ma, the remainder vibration is less than 1.53 g, which proves that the multidimensional vibration suppression method has the ability to resist vibration from any direction to ensure the smooth process of wind tunnel tests.
Do-Keun Lee, Min-Hyuk Lim, Kyung-Joon Shin, Kwang-Myong Lee
Published: 16 September 2019
by MDPI
Materials, Volume 12; doi:10.3390/ma12183003

Abstract: Maintenance of structures using self-healing concrete technologies has recently been actively studied. However, unlike the technological development of self-healing concrete, research focused on evaluating the self-healing performance is insufficient. Although water permeability experiments are widely used, the reliability of the test results may be reduced due to the viscosity of water and the possibility of elution of material inside the specimen. In this study, we propose a gas diffusion test for estimating the crack width and eventually for application to evaluation of the self-healing performance. The results verified that the proposed method can be effectively applied to the estimation of crack width.
Published: 16 September 2019
Journal of Pain Research; doi:10.2147/jpr

Abstract: An international, peer reviewed, open access, online journal that welcomes laboratory and clinical findings in the fields of pain research and the prevention and management of pain. Original research, reviews, symposium reports, hypothesis formation and commentaries are all considered for publication.
Orthopedic Research and Reviews; doi:10.2147/orr

Abstract: An international, peer-reviewed, open-access journal focusing on the patho-physiology of the musculoskeletal system, trauma, surgery and other corrective interventions to restore mobility and function. Advances in new technologies, materials, techniques and pharmacological agents will be particularly welcome.Specific topics covered in the journal include:  â
Ren-Jie Mao, Jian-Xin You, Chun-Yan Duan, Lu-Ning Shao
Published: 16 September 2019
by MDPI
Sustainability, Volume 11; doi:10.3390/su11185057

Abstract: The third-party platform named ECO is used by many transnational companies to monitor the sustainability performance of their global suppliers because of its easiness and shareability. Nonetheless, methods used in this platform for evaluating and calculating the sustainability performance of the alternative suppliers are criticized for their lack of accuracy. In response to these problems, this paper presents a heterogeneous multi-criteria decision-making (MCDM) method based on interval-valued intuitionistic fuzzy--an acronym in Portuguese for interactive multi-criteria decision making (IVIF--TODIM) to improve the efficiency of the evaluation model. Considering the varying features of evaluation criteria, i.e., either quantitative or qualitative, the evaluation values under different criteria are expressed in their appropriate information types. In this paper, a general method based on the relative closeness to the technique for order preference by similarity to ideal solution (TOPSIS) method is applied for aggregating the heterogeneous assessment information, including crisp numbers, interval numbers, and triangular fuzzy numbers (TFNs), into interval-valued intuitionistic fuzzy numbers (IVIFNs). Then, the TODIM (an acronym in Portuguese for interactive multi-criteria decision making) is extended and employed to prioritize the alternative suppliers. Finally, the applicability and effectiveness of the proposed method is verified by a practical example of polymer manufacturing company and a comparison analysis with existing methods.
Vera Serrinha, Sérgio Correia, Gastão Marques
Journal of Open Innovation: Technology, Market, and Complexity, Volume 5; doi:10.3390/joitmc5030071

Abstract: Bee venom is a sub-product of the beekeeping activity, and has a wide field of applications in several pivotal markets. Nevertheless, its collection is not an activity disseminated among Portuguese beekeepers, as its production is marginal. There are limited empirical studies on the production and the technical aspects involved in this type of activity. Our study, therefore, contributes to narrowing this knowledge gap, by analyzing and comparing the productivity and profitability of two bee venom collection techniques. The first involves equipment available on the market, and the second involves a new device developed from the aim of the present work. Concerning market knowledge, a questionnaire was given to a sample of beekeepers, to understand and characterize the market’s needs and the level of information about bee venom. Because of the growing market interest in this product, a new collector is proposed, based on a set of intensive frame collectors strategically placed inside the beehives. The improvements obtained were increased production, either in terms of quantity or quality, obtaining a positive profitability. To evaluate the productivity of the proposed equipment, a comparison was performed, in an apiary, between existing state-of-the-art equipment and the proposed intensive collector. In a second stage, the profitability of the new proposed equipment was analyzed, using a comparative method between incomes and costs associated with both solutions. The results obtained showed that the new intensive collector enables a profitable collection of bee venom in Portugal, despite its higher initial investment.
Huaxiao Shen, Tian Tian, Han Zhu
Published: 16 September 2019
by MDPI
Sustainability, Volume 11; doi:10.3390/su11185059

Abstract: In this paper, we study a two-echelon inventory system with one warehouse and multiple retailers, under the setting of periodic review and infinite horizon. In each period, retailers replenish their stocks from the warehouse, and the warehouse in turn replenishes from an external supplier. Particularly, as stipulated by the supplier, there is a minimum order quantity (MOQ) requirement for the warehouse. That is, the warehouse must order either none or at least as much as the MOQ. To investigate this system analytically, we assume retailers adopt the base-stock policy, and we design for the warehouse a new heuristic ordering policy, called refined base-stock policy, which conforms to the MOQ requirement. Moreover, in the case of shortages, we assume the warehouse adopts a virtual allocation policy, and therefore the orders for individual units are filled in the same order as the original demands at the retailers. To evaluate the long-run average system cost exactly, we present a position-based cost-accounting scheme, in which the cost associated with each unit is assigned to its first position at the warehouse. We also derive lower and upper bounds of the inventory parameters, facilitating the search for the optimal policy that minimizes the long-run average system cost.
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