摘要：This study presents a numerical investigation into the equilibrium shapes and snapthrough response of an innovative bistable symmetric composite *** proposed design is a compound plate that consists of a symmetric flat platform followed by a winglet that utilizes the modified hybrid bistable symmetric laminate recently developed in the *** hybrid layup of the winglet resolves the issue of losing the bistability of the unsymmetric laminate when attached to another *** approximate analytical model based on the Rayleigh-Ritz method is developed for the compound plate that considers the geometric nonlinearity,the clamping conditions at the wing root,and the compatibility conditions at the *** static equilibrium positions predicted by the model were verified against the ABAQUS finite element(FE)results and an excellent agreement was *** influence of the geometrical and material parameters of the proposed design on the static equilibrium shapes and the snapthrough response was *** following parameters were considered:the length ratio of the flat plate to the bistable winglet,the thickness and location of the bidirectional glass epoxy layers,the load location,and the wing’s taperness and aspect *** parameters were found significant,and their effects were *** novelty of this work is that it presents the equilibrium shapes and the snapthrough response of a bistable laminate as a part of a bigger compliant structure,which mimics the scenario in real-life applications.

摘要：This study investigates the seismic design factors for three reinforced concrete （RC） framed buildings with 4, 16 and 32-stories in Dubai, UAE utilizing nonlinear analysis. The buildings are designed according to the response spectrum procedure defined in the 2009 International Building Code （IBC＇09）. Two ensembles of ground motion records with 10% and 2% probability of exceedance in 50 years （10/50 and 2/50, respectively） are used. The nonlinear dynamic resPonses to the earthquake records are computed using IDARC-2D. Key seismic design parameters are evaluated; namely, response modification factor （R）, deflection amplification factor （Cd）, system overstrength factor （Ωo）, and response modification factor for ductility （Rd） in addition to inelastic interstory drift. The evaluated seismic design factors are found to significantly depend on the considered ground motion （10/50 versus 2/50）. Consequently, resolution to the controversy of Dubai seismicity is urged. The seismic design factors for the 2/50 records show an increase over their counterparts for the 10/50 records in the range of 200%-400%, except for the D~ factor, which shows a mere 30% increase. Based on the observed trends, perioddependent R and Cd factors are recommended if consistent collapse probability （or collapse prevention performance） in moment frames with varying heights is to be expected.

摘要：The local design and construction practices in the United Arab Emirates （UAE）, together with Dubai＇s unique rate of development, warrant special attention to the selection of Lateral Force-Resisting Systems （LFRS）. This research proposes four different feasible solutions for the selection of the LFRS for tall buildings and quantifies the impact of these selections on seismic performance and cost. The systems considered are： Steel Special Moment-Resisting Frame （SMRF）, Concrete SMRF, Steel Dual System （SMRF with Special Steel Plates Shear Wall, SPSW）, and Concrete Dual System （SMRF with Special Concrete Shear Wall, SCSW）. The LFRS selection is driven by seismic setup as well as the adopted design and construction practices in Dubai. It is found that the concrete design alternatives are consistently less expensive than their steel counterparts. The steel dual system is expected to have the least damage based on its relatively lesser interstory drifts. However, this preferred performance comes at a higher initial construction cost. Conversely, the steel SMRF system is expected to have the most damage and associated repair cost due to its excessive flexibility. The two concrete alternatives are expected to have relatively moderate damage and repair costs in addition to their lesser initial construction cost.

摘要：An assessment of the human motion repeatability for three selected Activities of Daily Living(ADL)is performed in this *** exercises were prescribed by an occupational therapist for the upper limb *** movement patterns of five participants,recorded using a Qualisys motion capture system,are compared based on the Analysis of Variance(ANOVA)*** survey is motivated by the need to find the appropriate task workspace of a 6-degrees of freedom cable-driven parallel robot for upper limb rehabilitation,which is able to reproduce the three selected *** comparison is performed to justify,whether or not,there is enough similarity between the participants’gestures,and so a single reference trajectory can be adopted as the robot-prescribed *** the results of the comparative study,an optimization process of the sought robot design is carried out,where the structure size and the cable tensions simultaneously minimized.

摘要：This paper deals with a design approach of a gait training machine based on a quantitative gait analysis. The proposed training machine is composed of a body weight support device and a cable-driven parallel robot. This paper is focused on the cable-driven robot, which controls the pose of the lower limb through an orthosis placed on the patient＇s leg. The cable robot reproduces a normal gait movement through the motion of the orthosis. A motion capture system is used to perform the quantitative analysis of a normal gait, which will be used as an input to the inverse dynamic model of the cable robot. By means of an optimization algorithm, the optimal design parameters, which minimize the tensions in the cables, are determined. Two constraints are considered, i.e., a non-negative tension in the cables at all times, and a free cable/end-effector collision. Once the optimal solution is computed, a power analysis is carried out in order to size the robot actuators. The proposed approach can be easily extended for the design study of a similar type of cable robots.

摘要：In this paper, the effect of the source of recycled coarse aggregate on the properties of concrete is investigated. The tests were conducted on concrete made from three sources of recycled aggregates： （1） old concrete with unknown strength, （2） old concrete with a known compressive strength of 21 MPa, and （3） old concrete with a known strength of 42 MPa. The three sources of recycled aggregates were used to produce new concrete with a target compressive strength of 21 MPa. The first and third sources of recycled aggregates were used in producing concrete with target strength of 42 MPa. A control mix was designed with aggregates from natural sources. The research included two methods of making recycled concrete. One concrete mix was produced using the recycled aggregate and adding more water than the control mix, to reach the target slump, while the second concrete mix was produced using the same amount of water as the control mix but with additional superplasticizer to maintain the target slump. The results obtained in this research showed that the concrete compressive strength depends on the source of recycled aggregates; the stronger the source of recycled aggregate, the higher the compressive strength of the produced concrete. Furthermore, the compressive strength of the first concrete mix was about 10%-20% lower than the compressive strength of the control mix. However, when superplasticizers were used, the compressive strength was around the same value as the control mix.

摘要：This paper provides an overview of positive psychology(PP),or the study of elements that make life most worth living(Peterson,2006),and demonstrates its efficacy by detailing five intervention *** aligning PP objectives and linguistic aims in second language teaching and learning,the studies show multiplied,concurrent results,heightened teacher and learner wellbeing and improved language *** important caveat is that PP interventions work best when they cater specifically to individual learners.

摘要：Objective:The study aimed to investigate the level and factors associated with the resilience of nurses practicing at the main COVID-19 referral center in ***:The study utilized a cross-sectional survey *** were collected electronically in the spring of 2020 from 265 *** questionnaire included five sections:demographic characteristics,job satisfaction,turnover intentions,exposure to violence,and resilience *** linear regression was used to determine factors associated with ***:Results showed that the overall score of resilience among nurses was 66.91±*** nurses were satisfied with their job(67.8%),and most nurses reported that it is unlikely for them to quit their present work in the coming year(76.2%).Over the last year,three-quarters of nurses(74.7%)reported being ever exposed to a form of occupational *** resilience of nurses was directly associated with job satisfaction and male gender and inversely associated with intention-to-quit and exposure to violence(P<0.05).Conclusions:Enhancing the resilience of nurses at the frontline of the COVID-19 pandemic improves their job satisfaction and retention and would help support the effectiveness and efficiency of care *** managers can regularly investigate the resilience of nurses and offer interventions that would strengthen it,especially at times of crisis.