404 research outputs found

    A comprehensive literature classification of simulation optimisation methods

    Get PDF
    Simulation Optimization (SO) provides a structured approach to the system design and configuration when analytical expressions for input/output relationships are unavailable. Several excellent surveys have been written on this topic. Each survey concentrates on only few classification criteria. This paper presents a literature survey with all classification criteria on techniques for SO according to the problem of characteristics such as shape of the response surface (global as compared to local optimization), objective functions (single or multiple objectives) and parameter spaces (discrete or continuous parameters). The survey focuses specifically on the SO problem that involves single per-formance measureSimulation Optimization, classification methods, literature survey

    STR-938: FLEXURAL BEHAVIOUR OF RECTANGULAR FRP-TUBES FILLED WITH REINFORCED CONCRETE: EXPERIMENTAL AND ANALYTICAL INVESTIGATIONS

    Get PDF
    This paper presents experimental and analytical investigations on the flexural behaviour of rectangular concrete-filled fiber-reinforced polymer (FRP) tube (CFFT) beams with steel rebar. Eight full-scale CFFT beams and two control reinforced concrete (RC) beams were tested under a four-point bending. Several parameters as the FRP tubes thickness, fiber laminates, and steel reinforcement were studied. The experimental results indicate outstanding performance of the CFFT beams in terms of strength and ductility compared to the RC beams. Some CFFT beams attained flexural strength and ductility 540% and 1430% higher than that of the RC beams, respectively. Theoretical analysis was developed to determine the flexural capacities of the CFFT beam system through cracking, yield, and ultimate stages. A strain compatibility/equilibrium model was developed to predict the moment-curvature response of the CFFT beams addressing the issue of confinement and tension stiffening of concrete. The analytical model can predict well the flexural moments, curvature, deflection, strains, and neutral axis location

    STR-937: BEHAVIOUR OF FRP-REINFORCED CFFT COLUMNS UNDER AXIAL COMPRESSION LOADING

    Get PDF
    This paper presents the test results of an experimental study aimed at investigating the axial behaviour of CFFT columns internally reinforced with steel and FRP bars. A total of eight reinforced concrete (RC) and concrete-filled FRP tube (CFFT) columns were constructed and tested until failure. All columns had 1900-mm in height and 213-mm in diameter. The test parameters were: (1) internal reinforcement type (steel, glass FRP (GFRP), or carbon FRP (CFRP) bars) and amount, (2) GFRP tube thicknesses, and (3) nature of axial loading type (i.e. monotonic and cyclic). The experimental results revealed that the CFFT columns reinforced with GFRP bars exhibited similar responses compared to their counterparts reinforced with steel bars with no significant difference in terms of ultimate axial strength and strain capacities. Providing the GFRP tubes of the CFFT columns significantly enhanced the strength and strain capacities and attributed to change the mode of failure from axially dominated material failure (for the control columns) to instability failure (for the CFFT columns). Furthermore, the envelop curve of the CFFT reinforced column tested under axial cyclic loading is almost identical to the axial stress-strain curve of the same specimen tested under axial monotonic loading. However, the ultimate axial and hoop rupture strain was slightly larger for the specimen subjected to axial cyclic loading. Finally, using FRP bars instead of conventional steel bars in the CFFT columns can provide a step forward to develop a promising totally corrosion-free new structural system

    Investigating dynamic interdependencies between traditional and digital assets during the COVID-19 outbreak: Implications for G7 and Chinese financial investors

    Get PDF
    This paper discusses the relationship between the volatilities of traditional and digital assets before and during the COVID-19 pandemic. Using daily data relevant to the period ranging from January 4, 2016, to April 15, 2020, the results of the DCC-MVGARCH model indicate that the stock markets responded to the Coronavirus outbreak as the crypto market with worrying volatility. Before this outbreak, Bitcoin and gold are considered as a hedge for US, English, French, German, and Italian financial investors. The conditional correlation between stock indices and other assets was skyrocketing during this pandemic, except for the couple SSE-Ripple

    Unexpected stimulation of mitochondrial ADP-ribosylation by cyanide

    Get PDF
    AbstractCyanide, the classical inhibitor of the mitochondrial respiratory chain at site III, stimulates ADP-ribosylation of a number of mitochondrial proteins, the major protein being the 50–55 kDa band. Sodium azide, sharing the same inhibitory site, does not have the same effect. Rotenone or antimycin A have no influence on mitochondrial ADP-ribosylation. Data suggest that no apparent correlation exists between oxidoreductase function and protein ADP-ribosylation. Purified nuclear poly(ADP-ribose) polymerase activity was not affected by cyanide. The cyanide effect on mitochondrial ADP-ribosylation seems intriguing and may be attributed to NAD+ -CN complex formation, since NAD reacts with cyanide at pH > 8 with N-substituted nicotinamide which may prevent inhibition of ADP-ribosylation

    Permanent magnet machine design trade-offs to achieve sensorless control at high load

    Get PDF
    Purpose The purpose of this paper is to introduce a new design optimization technique for a surface mounted permanent magnet (SMPM) machine to increase sensorless performance at high loadings by compromising with torque capability. Design/methodology/approach An SMPM parametric machine model was created and analysed by finite element analysis (FEA) software by means of the Matlab environment. Eight geometric parameters of the machine were optimized using genetic algorithms (GAs). The outer volume of the machine, namely copper loss per volume, was kept constant. In order to prevent sensorless performance loss at high loading, an optimization process was realized using two loading stages: maximum torque with minimum ripple at nominal load and maximum self-sensing capability at twice load. In order to show the effectiveness of the proposed technique, the obtained results were compared with the classical one-stage optimization realized for each loading condition separately. Findings With the proposed technique, fairly good performance results of the optimization were obtained when compared with the one-stage optimizations. Using the proposed technique, sensorless performance of the motor was highly increased by compromising torque capability for high loading. Additionally, this paper shows that the self-sensing properties of a SMPM machine should be considered at the design stage of the machine. Originality/value In related literature, design optimization studies for the sensorless capability of SMPM motor are very few. By increasing optimization performance, new proposed technique provides to achieve good result at high load for sensorless performance compromising torque capability

    Atopic dermatitis in Tunisian schoolchildren

    Get PDF
    Introduction: The prevalence of atopic dermatitis (AD) is low in North Africa. We describe the epidemiology of this atopic condition among school children in Tunisia. Methods: We conducted a Cross-sectional survey study of 5 to 6-year-old schoolchildren from 21 primary schools of Sfax. The diagnosis of AD was based on the U.K. Working Party diagnostic criteria. A questionnaire including these criteria and some risk factors of AD was issued to the children. All children were examined by one dermatologist. Results: Among the 1617 examined children, ten had AD giving a oneyear prevalence of 0.65%. The overall sex ratio was 2.33. The disease occurred before the age of 2 years in 3 children. Pure AD without concomitant respiratory allergies was noted in 3 cases. One first-degree family member with atopy was at least noted in seven children. The strongest associated factor was the presence of AD in at least one parent and maternal age at the time of the child birth. Nor breast-feeding neither environmental characteristics of the house did correlate with AD. Conclusion: The prevalence of AD in Tunisian schoolchildren is low but comparable to those of other developing countries. Family history of atopy and maternal age at the birth time was the most important associated factors.Key words: Atopic dermatitis, atopy, children, epidemiology, prevalence, Tunisi

    SV MIXTURE, CLASSIFICATION USING EM ALGORITHM

    Get PDF
    ABSTRACT The present paper presents a theoretical extension of our earlier work entitled"A comparative study of two models SV with MCMC algorithm" cited, Rev Quant Finan Acc (2012
    • …
    corecore