Experimental study on flexural behaviour of inorganic polymer concrete beams reinforced with basalt rebar

Corrosion of reinforcing steel and the severe degradation of mechanical properties with temperature and fire conditions are the weakest points of steel-reinforced concrete structures and fibre reinforced polymer (FRP) system, respectively. In this paper, the basalt reinforced inorganic polymer concrete (IPC) beam which combines the specific characteristics of IPC and basalt reinforcement such as good corrosion resistance and fire resistance was proposed. The inorganic polymer binder was made of fly ash, ground granulated blast-furnace slag and alkaline activating solution. The mechanical properties of IPC were measured and compared with those of reference ordinary Portland cement (OPC) concrete. The flexural behaviour of basalt reinforced IPC beam was investigated and compared to control steel-reinforced OPC concrete beam. The measured ultimate flexural capacity of basalt reinforced IPC beam was compared with the predicted value obtained using the guidelines for FRP-reinforced OPC concrete beam. Results indicated that the elastic modulus of IPC was very close to OPC, while the compressive strength and flexural strength of IPC were around 80% of those of OPC. The IPC beam reinforced with basalt rebar exhibited a two-stage load-midspan deflection response that was different from control concrete beam due to the different mechanical properties of basalt and steel rebars. The crack patterns in basalt reinforced IPC beam were found to be similar to control beam, however, the maximum crack width of basalt reinforced beam was approximately 2 times that of control beam. The guidelines for FRP-reinforced concrete beam were adequate for predicting the flexural strength of basalt reinforced IPC beams

Comparison of constraint-handling techniques for metaheuristic optimization

Many design problems in engineering have highly nonlinear constraints and the proper handling of such constraints can be important to ensure solution quality. There are many different ways of handling constraints and different algorithms for optimization problems, which makes it difficult to choose for users. This paper compares six different constraint-handling techniques such as penalty methods, barrier functions, epsilon-constrained method, feasibility criteria and stochastic ranking. The pressure vessel design problem is solved by the flower pollination algorithm, and results show that stochastic ranking and epsilon-constrained method are most effective for this type of design optimization

Behaviour of inorganic polymer concrete columns reinforced with basalt FRP bars under eccentric compression: An experimental study

In this paper, a new composite system for concrete structures, i.e. inorganic polymer concrete column (IPCC) reinforced with basalt FRP bars, which combines the outstanding features of inorganic polymer concrete (IPC) and basalt reinforcement such as good corrosion resistance and fire resistance was proposed. The inorganic polymer binder was made of industrial by-products including fly ash and ground granulated blast-furnace slag, and alkaline activating solution. The mechanical behaviour of short IPCC under eccentric compression was experimentally investigated and compared with control steel-reinforced ordinary Portland cement concrete columns (OPCC). The effect of eccentricity on overall failure mode and load–displacement/strain response of the specimens was studied. Results indicate that the load-carrying capacity of IPCC was approximately 30% lower than that of OPCC, while the ultimate displacements of IPCC were 65% and 15% larger than those of OPCC under large and small eccentricities, respectively. The IPCC specimens had almost similar overall load–displacement/strain response as the OPCC specimens up to the final failure. The ultimate longitudinal strains on the compression face of IPCC under large and small eccentricities were one time and 22% larger than those of OPCC respectively due to the relatively lower strength of IPC than ordinary concrete. In addition, the sine-shaped model can be used for IPCC to predict the lateral deformation along the column length at various load levels until final failure

Adventitious shoots induction and plant regeneration from cotyledons of watermelon (Citrullus lanatus L.)

A highly efficient regeneration system is a prerequisite step for successful genetic transformation ofwatermelon cultivars (Citrullus lanatus L.). The objective of this study was to establish efficient in vitro plant regeneration for three watermelon cultivars. To achieve optimal conditions for adventitious shoot induction, the 5-day-old explants (cotyledon base portion, apical portion and hypocotyl) of three cultivars were placed on MB5 media supplemented with different concentrations and combinations of growth regulators (1.0 to 10.0 mg L-1 6-benzyladenine (BA) and 0 to 1.0 mg L-1 indole acetic acid (IAA)); the explants from seedling of different development stages (0 to 10 d) were cultured on MB5 medium containing 2.0 mg L-1 BA and 0.2 mg L-1 IAA for investigating the effect of age on adventitious shoots initiation; besides, 5-day-old seedlings were grown on optimal regeneration medium supplemented with different concentrations of kanamycin for screening the lowest lethal concentration for adventitious shoots. The results show that the basal region of cotyledon showed higher frequency of shoot formation (79.17-83.33%) than the apical region (5.23-8.25%); high  percentage of shoots regeneration was induced from 5-day-old cotyledons base portion cultured on MB5 containing 1 or 2 mg L-1 BA; the 100 mg L-1 kanamycin proved to be the optimal concentration for screening the transformants. Our results provide an efficient stable regeneration system for genetic transformation of watermelon.Key words: Watermelon (Citrullus lanatus), cotyledon, growth regulator, kanamycin, regeneration

Lick Slit Spectra of Thirty-Eight Objective Prism QSO Candidates and Low Metallicity Halo Stars

We present Lick Observatory slit spectra of 38 objects which were claimed to have pronounced ultraviolet excess and emission lines by Zhan \& Chen. Most of our spectra have FWHM spectral resolutions of about 4~\AA , and relatively high S/N of about 10 -- 50, although some have FWHM $\simeq 15$~\AA ~or lower S/N. We find eleven QSOs, four galaxies at $z \simeq 0.1$, twenty-two stars and one unidentified object with a low S/N spectrum. Six of the QSOs show absorption systems, including Q0000+027A with a relatively strong associated C~IV absorption system, and Q0008+008 (V$\simeq 18.9$) with a damped Ly$\alpha$ system with an H~I column density of $10^{21}$ cm$^{-2}$. The stars include a wide variety of spectral types. There is one new DA4 white dwarf at 170~pc, one sdB at 14~kpc, and three M stars. The rest are of types F, G and K. We have measured the equivalent widths of the Ca~II~K line, the G-band and the Balmer lines in ten stars with the best spectra, and we derive metallicities. Seven of them are in the range $-2.5 \leq$~[Fe/H]~$\leq -1.7$, while the others are less metal poor. If the stars are dwarfs, then they are at distances of 1 to 7~kpc, but if they are giants, typical distances will be about 10~kpc.Comment: (Plain Tex, 21 pages, including tables. Send email to 'travell_oir%[email protected]' for 12 pages of figures) To appear in the %%Astronomical Journal, August, 199

Large magnetothermal conductivity of HoMnO_3 single crystals and its relation to the magnetic-field induced transitions of magnetic structure

We study the low-temperature heat transport of HoMnO_3 single crystals to probe the magnetic structures and their transitions induced by magnetic field. It is found that the low-T thermal conductivity (\kappa) shows very strong magnetic-field dependence, with the strongest suppression of nearly 90% and the biggest increase of 20 times of \kappa compared to its zero-field value. In particular, some ``dip"-like features show up in \kappa(H) isotherms for field along both the ab plane and the c axis. These behaviors are found to shed new light on the complex H-T phase diagram and the field-induced re-orientations of Mn^{3+} and Ho^{3+} spin structures. The results also demonstrate a significant spin-phonon coupling in this multiferroic compound.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev.