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11.
The literature on free vibration analysis of Bernoulli-Euler and Timoshenko piles embedded in elastic soil is plenty, but
that of Reddy-Bickford piles partially embedded in elastic soil with/without axial force effect is fewer. The soil that the
pile partially embedded in is idealized by Winkler model and is assumed to be two-layered. The pile part above the soil is
called the first region and the parts embedded in the soil are called the second and the third region, respectively. It is
assumed that the behaviour of the material is linear-elastic, that axial force along the pile length to be constant and the
upper end of the pile that is semi-rigid supported against rotation is modelled by an elastic spring. The governing differential
equations of motion of the rectangular pile in free vibration are derived using Hamilton’s principle and Winkler hypothesis.
The terms are found directly from the solutions of the differential equations that describe the deformations of the cross-section
according to the high-order theory. The models have six degrees of freedom at the two ends, one transverse displacement and
two rotations, and the end forces are a shear force and two end moments. Natural frequencies of the pile are calculated using
transfer matrix and the secant method for non-trivial solution of linear homogeneous system of equations obtained due to values
of axial forces acting on the pile, total and embedded lengths of the pile, the linear-elastic rotational restraining stiffness
at the upper end of the pile and to the boundary conditions of the pile. Two different boundary conditions are considered
in the study. For the first boundary condition, the pile’s end at the first region is semi-rigid connected and not restricted
for horizontal displacement and the end at the third region is free and for the second boundary condition, the pile’s end
at the first region is semi-rigid connected and restricted for horizontal displacement and the end at the third region is
fixed supported. The calculated natural frequencies of semi-rigid connected Reddy-Bickford pile embedded in elastic soil are
given in tables and compared with results of Timoshenko pile model. 相似文献
12.
Photocatalytic performance of Sn-doped and undoped TiO2 nanostructured thin films under UV and vis-lights 总被引:2,自引:0,他引:2
Arpaç E Sayilkan F Asiltürk M Tatar P Kiraz N Sayilkan H 《Journal of hazardous materials》2007,140(1-2):69-74
Sn-doped and undoped nano-TiO(2) particles have been synthesized by hydrotermal process without solvent at 200 degrees C in 1h. Nanostructure-TiO(2) based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV-vis-NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO(2) particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and, (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO(2) thin film. 相似文献
13.
Sayilkan F Asiltürk M Tatar P Kiraz N Arpaç E Sayilkan H 《Journal of hazardous materials》2007,144(1-2):140-146
Nanostructure Sn(4+)-doped TiO(2) based mono and double layer thin films, contain 50% solid ratio of TiO(2) in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn(4+)-doped nano-TiO(2) particle a doping ratio of about 5[Sn(4+)/Ti(OBu(n))(4); mol/mol%] has been synthesized by hydrotermal process at 225 degrees C. The structure, surface and optical properties of the thin films and/or the particles have been investigated by XRD, BET and UV/vis/NIR techniques. The results showed that the double layer coated glass surfaces have a very high photocatalytic performance than the other one under UV and vis lights. The results also proved that the hydrothermally synthesized nano-TiO(2) particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property. 相似文献
14.
15.
Tugdem Muslu Bala Ani Akpinar Sezgi Biyiklioglu-Kaya Meral Yuce Hikmet Budak 《International journal of molecular sciences》2021,22(22)
Food insecurity and malnutrition have reached critical levels with increased human population, climate fluctuations, water shortage; therefore, higher-yielding crops are in the spotlight of numerous studies. Abiotic factors affect the yield of staple food crops; among all, wheat stem sawfly (Cephus cinctus Norton) and orange wheat blossom midge (Sitodiplosis mosellana) are two of the most economically and agronomically harmful insect pests which cause yield loss in cereals, especially in wheat in North America. There is no effective strategy for suppressing this pest damage yet, and only the plants with intrinsic tolerance mechanisms such as solid stem phenotypes for WSS and antixenosis and/or antibiosis mechanisms for OWBM can limit damage. A major QTL and a causal gene for WSS resistance were previously identified in wheat, and 3 major QTLs and a causal gene for OWBM resistance. Here, we present a comparative analysis of coding and non-coding features of these loci of wheat across important cereal crops, barley, rye, oat, and rice. This research paves the way for our cloning and editing of additional WSS and OWBM tolerance gene(s), proteins, and metabolites. 相似文献
16.
Ferhat Bülbül Hikmet Altun ?zkan Kü?ük Vefa Ezirmik 《Metals and Materials International》2012,18(4):631-637
This study aims to evaluate the tribological and corrosion properties of the electroless Ni-B coating deposited on AISI 304 stainless steels. The microstructure of the coating was characterized using x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). XRD analysis revealed that the prepared coating possessed an amorphous character. SEM-EDS investigation also indicated that a non-stoichiometric Ni-B coating was deposited with a columnar growth mechanism on the stainless steel substrate and the morphology of the growth surface was blackberry-like. The hardness and tribological properties were characterized by microhardness and a pin-on-disc wear test. The electroless Ni-B coated sample had a higher degree of hardness, a lower friction coefficient and a lower wear rate than the uncoated substrate. The electrochemical potentiodynamic polarization method was used to evaluate the corrosion resistance of the coating. The electroless Ni-B coating offered cathodic protection on the substrate by acting as a sacrificial anode although it was electrochemically more reactive than the stainless steel substrate. 相似文献
17.
A noncontact chemical and electrical measurement X-ray photoelectron spectroscopy (XPS) technique is performed to investigate a CdS-based photoresistor during its operation. The main objective of the technique is to trace chemical- and location-specified surface potential variations as shifts of the XPS Cd 3d(5/2) peak position without and under photoillumination with four different lasers. The system is also modeled to extract electrical information. By analyzing the measured potential variations with this model, location-dependent resistance values are represented (i) two dimensionally for line scans and (ii) three dimensionally for areal measurements. In both cases, one of the dimensions is the binding energy. The main advantage of the technique is its ability to assess an element-specific surface electrical potential of a device under operation based on the energy deviation of core level peaks in surface domains. Detection of the variations in electrical potentials and especially their responses to the energy of the illuminating source in operando, is also shown to be capable of detecting, locating, and identifying the chemical nature of structural and other types of defects. 相似文献
18.
The main results of hydrocracking of goudron under reduced pressure in the presence of a suspended catalyst have beenanalyzed. It was investigate the influence of temperature to hydrocracking process of goudron. It was determined that with increasing of temperature from 400 ℃ to 440 ℃ (0.5 MPa pressure) the yield of light oil products increased from 31.39% to 61% mass. 相似文献
19.
Sayilkan F Asiltürk M Kiraz N Burunkaya E Arpaç E Sayilkan H 《Journal of hazardous materials》2009,162(2-3):1309-1316
Pure anatase, nanosized and Sn(4+) ion doped titanium dioxide (TiO(2)) particulates (TiO(2)-Sn(4+)) were synthesized by hydrothermal process. TiO(2)-Sn(4+) was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn(4+) doping to TiO(2) against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO(2)-Sn(4+) in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO(2)-Sn(4+) is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO(2)-Sn(4+) from 10 to 50% in the coating solution increased antibacterial effect. 相似文献
20.
Hikmet Çiçek 《Journal of Adhesion Science and Technology》2019,33(6):635-645
The interest in titanium-nickel (TiNi) alloys has increased with the discovery of the versatile properties of these alloys. In this study, the structural, mechanical and tribological properties of amorphous and crystalline TiNi coatings were investigated. The TiNi coatings were deposited with magnetron sputtering system. The crystallization process was conducted in a vacuum heat treatment furnace. The structural properties of the coatings were investigated with XRD, SEM and EDS analyses. Micro-hardness and pin-on-disc wear tests were used to obtain the mechanical and tribological properties of the coatings. AISI D2 steel, AISI 52100 steel, Aluminum 2024 alloy and copper were used as substrate materials, hence the effects of different substrates were also investigated. The highest coating hardness was obtained as 8.5?GPa and the lowest coefficient of friction value was obtained as 0.18. The tribological tests showed that the amorphous and crystalline TiNi coatings have different coefficient of friction and wear rate and using different substrate affects these properties. 相似文献