Simple Equations for Predicting Maximum Displacement of Isolation Systems Using Lead Rubber Bearings

Predicting maximum displacement is an important task in designing isolation systems. An effective procedure that is widely used for this task is equivalent linear force (ELF) procedure, which is allowed by many contemporary design codes. This procedure uses very basic parameters of the isolation system as well as earthquake condition of the site to analyze for the maximum displacement. However, ELF procedures are time-consuming because they require an iteration process. This study employed an ELF procedure to generate a large database and used it to develop explicit and simple equations that can directly calculate the maximum displacement of isolation systems using lead rubber bearings. The proposed equations can confidently predict the maximum displacement calculated by the ELF procedure. In addition, the investigation showed that the first to post-yield stiffness ratio of an isolation system, which is difficult to accurately determine, has neglected effect on the maximum displacement calculated by the ELF procedure. Based on this observation, a simple equation that uses only three input parameters to predict the maximum displacement was proposed. The input parameters to the simplified equation include normalized characteristic strength and post-yield period of the isolation system, and 1-s spectral acceleration of the site. These parameters are minimum to determine an isolation system and earthquake condition. The comparison between the maximum displacement predicted by the proposed equation and the maximum displacement calculated by the ELF procedure showed that the proposed equation generates slightly conservative results for common designs, therefore is suitable for practical application

Evaluating the Accuracy of an Equivalent Linear Model in Predicting Peak Displacement of Seismic Isolation Systems using Single Friction Pendulum Bearings

This study evaluates the accuracy of an equivalent linear model in predicting peak nonlinear time-history displacement of seismic isolation systems with single friction pendulum bearings. To perform this evaluation, dynamic response of numerical models of 120 isolation systems subjected to 390 strong earthquake ground motions, including motions with pulse and motions without pulse, was analyzed and statistically processed. The results show that the equivalent linear model can partly predict the peak displacement of its counterpart nonlinear model. However, the equivalent model can also underestimate or overestimate the peak displacement. On average sense, the equivalent linear model underestimates small peak displacement and overestimates large peak displacement. It is also observed that the relationship between linear and nonlinear peak displacements depends on ground motion types. Based on the analysis data, equations representing relationship between linear and nonlinear peak displacements at different reliable levels for different ground motion types were proposed. These equations can be used in practice

Aerodynamic Load Analysis of a Variable Camber Continuous Trailing Edge Flap System on a Flexible Wing Aircraft

This paper presents an investigative aerodynamic analysis conducted on the novel control surface known as a Variable Camber Continuous Trailing Edge Flap (VCCTEF). The VCCTEF is modeled as a control effector on the NASA Generic Transport Model (GTM) where wing flexibility is considered. Aerodynamic modeling of the aircraft is conducted using vortex-lattice method (VLM), and an aeroelastic model of the aircraft that utilizes a coupled finite-element analysis (FEA) vortex-lattice solution is employed. VLM solutions are used to determine quasi-steady aerodynamic loading over the aeroelastic wing structures with VCCTEF. The load data is used to calculate aerodynamic sensitivities to control surface deployment and is also integrated to determine overall hinge moments. This analysis is conducted for different flight conditions, where control sensitivities compare the VCCTEF effectiveness against conventional control surfaces. Hinge moment results provide insight into aeroelastic wing loads, and worst case hinge moments for the VCCTEF can be estimated. Results show that the VCCTEF offers greater control authority than conventional ailerons at cruise, and nominal flap settings are determined for a low-speed take-off condition where the VCCTEF maintains comparable control effectiveness. Worst case hinge moment values are presented, where for a possible VCCTEF configuration, the stiff wing model demonstrates up to a 5.90 percent increase in flap hinge moment relative to a rigid model, and a reduced stiffness model demonstrates up to an 11.42 percent increase

Diversity of bats (Mammalia: Chiroptera) from the sop cop special use forest, son la province, Vietnam

Sop Cop is one of the largest remaining forest areas in the northwestern region of Vietnam. It contains high biodiversity values with previous records of many precious animal and plant species. However, biodiversity of Sop Cop is threatened by illegal activities of local people. In fact, bats and many other animal taxa in this area were poorly studied and rarely documented in previous publications. Between June 2014 and October 2016, the author conducted a variety of field surveys on bats in the Sop Cop Special Use Forest for understanding of their diversity and conservation status. The results indicated that the study area is a home to at least 36 bat species belonging to 20 genera, 6 families. Among them, 19 species are new to the area, 3 species are listed in the 2007 Red Data Book of Vietnam which must be considered for conservation priority in the future. 

Coupled Vortex-Lattice Flight Dynamic Model with Aeroelastic Finite-Element Model of Flexible Wing Transport Aircraft with Variable Camber Continuous Trailing Edge Flap for Drag Reduction

This paper presents a coupled vortex-lattice flight dynamic model with an aeroelastic finite-element model to predict dynamic characteristics of a flexible wing transport aircraft. The aircraft model is based on NASA Generic Transport Model (GTM) with representative mass and stiffness properties to achieve a wing tip deflection about twice that of a conventional transport aircraft (10% versus 5%). This flexible wing transport aircraft is referred to as an Elastically Shaped Aircraft Concept (ESAC) which is equipped with a Variable Camber Continuous Trailing Edge Flap (VCCTEF) system for active wing shaping control for drag reduction. A vortex-lattice aerodynamic model of the ESAC is developed and is coupled with an aeroelastic finite-element model via an automated geometry modeler. This coupled model is used to compute static and dynamic aeroelastic solutions. The deflection information from the finite-element model and the vortex-lattice model is used to compute unsteady contributions to the aerodynamic force and moment coefficients. A coupled aeroelastic-longitudinal flight dynamic model is developed by coupling the finite-element model with the rigid-body flight dynamic model of the GTM

Panic Purchasing: Food Hoarding in a City under Lockdown during the COVID-19 Pandemic

This research aimed to investigate the determinants of panic purchasing to hoard food in Ho Chi Minh City during the lockdown caused by the COVID-19 pandemic. Pragmatism and the deduction approach were used for the research. During the lockdown period in Ho Chi Minh City, the purposive sampling technique was the first method used to reach the population that needed to be measured. Then, simple sampling was the second technique to collect data in the city in July and August 2021. Data were collected from 584 participants—higher than the required minimum sample size—who fulfilled the essential criteria to be included in the sample’s population. Multi-quantitative methods, including descriptive statistics, reliability tests for items, exploratory factor analysis, and linear regression analysis, were used to analyze the data obtained. The main findings are that perceived scarcity, susceptibility, severity, cues to action, and self-efficacy impacted panic purchasing to hoard foods. The results of this study are compared to the literature review in order to discuss panic buying behaviour, and recommendations are offered to policymakers and researchers in the future

New records and morphological assessments of long-nosed fruit bats (chiroptera: pteropodidae: Macroglossus spp.) from Vietnam

Long-nosed fruit bat is a common name of the genus Macroglossus which comprises two species: Dagger-toothed long-nosed fruit bat (M. minimus) and Greater long-nosed fruit bat (M. sobrinus). These two species were rarely recorded from Vietnam or neighboring countries. Within Vietnam, M. minimus has been recorded only from two localities in southern Vietnam while M. sobrinus was known from all northern, central and southern regions of the country. Morphological features of these species in Vietnam were poorly documented in previous publications. With results from a rapid examination of all specimens and recently captured individuals, we here confirm that M. sobrinus is distinctively larger than M. minimus in all external and craniodental measurements. Two species are also distinguishable by their nostril shapes and mandible symphyses. This paper provides new distributional records of both M. sobrinus and M. minimus from Vietnam with remarks on their ecology and habitats.

An Improved MobileNet for Disease Detection on Tomato Leaves

Tomatoes are widely grown vegetables, and farmers face challenges in caring for them, particularly regarding plant diseases. The MobileNet architecture is renowned for its simplicity and compatibility with mobile devices. This study introduces MobileNet as a deep learning model to enhance disease detection efficiency in tomato plants. The model is evaluated on a dataset of 2,064 tomato leaf images, encompassing early blight, leaf spot, yellow curl, and healthy leaves. Results demonstrate promising accuracy, exceeding 0.980 for disease classification and 0.975 for distinguishing between diseases and healthy cases. Moreover, the proposed model outperforms existing approaches in terms of accuracy and training time for plant leaf disease detection

ASSESSMENT OF THE POTENTIAL FOR DEVELOPMENT OF AGRITOURISM IN BINH DINH PROVINCE, VIETNAM

This study evaluates the potential for agritourism development in Binh Dinh Province, Central Vietnam. The analytical hierarchical process is used to determine the weights of four factors with 25 measurement criteria to assess agritourism potential. The research results show that Binh Dinh Province has great agritourism potential based on four evaluation factors, including (1) local agricultural tourism resources, (2) the trend for agritourism development and the agritourism market, (3) the local community’s willingness, and (4) the supporting activities of the local government. In particular, the local agricultural tourism resources factor received the highest score, followed by the local community’s willingness and the supporting activities of the local government. The trend for agritourism development and the agritourism market was rated the lowest. Therefore, Binh Dinh has viable opportunities to encourage the growth of agritourism to improve farmers’ livelihoodsDu lịch nông nghiệp đem lại nhiều cơ hội cho phát triển kinh tế cũng như đa dạng hóa các loại hình du lịch và cải thiện đời sống sinh kế của người dân. Nghiên cứu sử dụng phương pháp phân tích thứ bậc (AHP) để tính các trọng số của các tiêu chí đánh giá tiềm năng phát triển du lịch nông nghiệp tại các huyện, thị xã phía bắc tỉnh Bình Định. Tiếp theo, kết quả mô hình hóa sơ đồ mạng cho thấy cả 4 địa phương An Lão, Hoài Ân, Phù Mỹ, thị xã Hoài Nhơn đều được đánh giá ở mức điểm cao về tiềm năng phát triển du lịch nông nghiệp trên các khía cạnh tài nguyên du lịch, xu hướng phát triển du lịch, sự ủng hộ của người dân địa phương và sự quan tâm của chính quyền địa phương. Tuy nhiên, yếu tố xu hướng phát triển thị trường du lịch nông nghiệp được đánh giá ở mức điểm thấp hơn. Điều này cũng xuất phát từ việc phát triển du lịch nông nghiệp tại các huyện, thị xã phía Bắc tỉnh Bình Định cũng mới bắt đầu nhận được sự quan tâm trong vài năm gần đây, số lượt khách tham quan các huyện, thị xã phía Bắc tỉnh Bình Định còn ít so với tiềm năng du lịch của địa bàn

New records of bats (Mammalia: Chiroptera) from Cu Lao Cham and Ly Son archipelagos, central Vietnam

Cu Lao Cham and Ly Son are two well-known archipelagos of Vietnam for their specular landscapes and varied ecosystems including forest, cave, and agriculture. However, their bat fauna has received little attention. Between July 2017 and August 2018, we conducted a series of mammal surveys with emphasis on bats of the two archipelagos. Bats were captured by mist nets and harp traps. Echolocation calls of microchiropteran species were recorded using the PCTape system then analysed by Selena software. With reference to all available literatures and specimens from the recent surveys, we obtained confirmed records of 9 bat species from Cu Lao Cham and 3 species from Ly Son. Of these, Megaderma spasma and Taphozous melanopogon are new to Cu Lao Cham while Rhinolophus macrotis is new to Ly Son. These three species were rarely recorded from other islands of Vietnam and also uncommon within Cu Lao Cham and Ly Son. These new records not only expand the known distributional range, but also provide worthwhile notes on a narrow geographical variation in morphology and echolocation of each species