3,692 research outputs found
Correlation between the Compressive, Tensile Strength of Old Concrete under Marine Environment and Prediction of Long-Term Strength
Compressive strength and tensile strength are important mechanical properties of concrete. The long-term strength of concrete under real service environment is an important parameter when evaluating existing buildings, which should also be properly considered in structural design. In this study, the relationship between compressive and splitting tensile strength of old concrete existing for long period under marine environment was investigated. At a deserted harbour, concrete cores samples were drilled by pairs in site. For each pair of samples, the two cores were drilled from the adjacent location and conducted to compressive, splitting tensile test, respectively. 48 compressive and splitting tensile strengths were finally obtained. From the test results, tensile strength presents general uptrend with compressive strength, and the two parameters are well positively correlated. Exponential model generally recommended by building codes or literatures is still capable of describing the relationship between compressive and tensile strength of old deteriorated concrete, when function parameters are properly determined. Based on statistical theory and the experimental result of this study, a method for predicting long-term tensile strength of concrete is developed and an example is given, which may provide a potential way to estimate long-term concrete strength under real marine environment
Finding out all locally indistinguishable sets of generalized Bell states
In general, for a bipartite quantum system
and an integer such that ,there are few necessary and sufficient conditions for local discrimination
of sets of generalized Bell states (GBSs) and it is difficult to locally
distinguish -GBS sets.The purpose of this paper is to completely solve the
problem of local discrimination of GBS sets in some bipartite quantum
systems.Firstly three practical and effective sufficient conditions are
given,Fans and Wang et al.s results [Phys Rev Lett 92, 177905
(2004); Phys Rev A 99, 022307 (2019)] can be deduced as special cases of these
conditions.Secondly in , a necessary and
sufficient condition for local discrimination of GBS sets is provided, and a
list of all locally indistinguishable 4-GBS sets is provided,and then the
problem of local discrimination of GBS sets is completely solved.In
, a concise necessary and sufficient
condition for one-way local discrimination of GBS sets is obtained,which gives
an affirmative answer to the case of the problem proposed by Wang et al.Comment: 10 pages, 2 table
Students' Intention of Visiting Urban Green Spaces after the COVID-19 Lockdown in China.
This study addresses students' perceptions of using urban green spaces (UGSs) after the easing of COVID-19 lockdown in China. We questioned whether they are still mindful of the risks from the outdoor gathering, or conversely, starting to learn the restoration benefits from the green spaces. Online self-reported surveys were distributed to the Chinese students aging from 14 to 30 who study in Hunan and Jiangsu Provinces, China. We finally obtained 608 complete and valid questionnaire forms from all participants. Their intentions of visiting UGSs were investigated based on the extended theory of planned behavior model. Structural equation modeling was employed to test the hypothesized psychological model. The results have shown good estimation performance on risk perception and perceived knowledge to explain the variances in their attitudes, social norms, and perceived behavior control. Among these three endogenous variables, the perceived behavior control owns the greatest and positive influence on the behavioral intention, inferring that controllability is crucial for students to make decisions of visiting green spaces in a post-pandemic context
Hawking radiation of black holes in the Horava-Lifshitz gravity
We investigate the Hawking radiation of 3+1 and 4+1 dimensional black holes
in the Horava-Lifshitz gravity with fermion tunnelling. It turns out
that the Hawking temperatures are recovered and are in consistence with those
obtained by calculating surface gravity of the black holes. For the 3+1
dimensional black holes, the Hawking temperatures are related to the
fundamental parameters of Horava-Lifshitz gravity.Comment: V2: references added, typo corrected, 16page
Chaos synchronization of the master-slave generalized Lorenz systems via linear state error feedback control
This paper provides a unified method for analyzing chaos synchronization of
the generalized Lorenz systems. The considered synchronization scheme consists
of identical master and slave generalized Lorenz systems coupled by linear
state error variables. A sufficient synchronization criterion for a general
linear state error feedback controller is rigorously proven by means of
linearization and Lyapunov's direct methods. When a simple linear controller is
used in the scheme, some easily implemented algebraic synchronization
conditions are derived based on the upper and lower bounds of the master
chaotic system. These criteria are further optimized to improve their
sharpness. The optimized criteria are then applied to four typical generalized
Lorenz systems, i.e. the classical Lorenz system, the Chen system, the Lv
system and a unified chaotic system, obtaining precise corresponding
synchronization conditions. The advantages of the new criteria are revealed by
analytically and numerically comparing their sharpness with that of the known
criteria existing in the literature.Comment: 61 pages, 15 figures, 1 tabl
Experimental Research on the Instantaneous and Long-Term Deflections of Pre-Cracked Concrete Beams Enhanced by Carbon Fibre Reinforced Polymer
This paper aims to disclose the influence law of cracks on instantaneous and long-term deflections of reinforced beam. For this purpose, four concrete beams were created, pre-loaded to varied degrees of cracking, and reinforced with carbon fibre reinforced polymer (CFRP). Then, a 300-day load test was carried out on these samples to measure the instantaneous and long-term deflections. The experimental results show that the pre-cracking degree has little influence on instantaneous deflection; whether a beam is pre-cracked or intact, the final deflection of the beam is mostly affected by its initial deflection before the reinforcement; the pre-cracking degree is negatively correlated to the magnitude of additional deflection under sustained load. The research findings lay the basis for judging whether a reinforced beam can be used normally in the long run
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