检索结果-南通市图书馆

Chinese Journal of Polymer Science 2011年第2期29卷 165-172页

作者： Hossein Mahdavi mahdi Mahmoudian School of Chemistry University College of ScienceUniversity of TehranTehranIran

Cross-linked poly（diallyldimethylammonium chloride） and its derivative copolymers were synthesized and used as phase transfer catalyst in the nucleophilic substitution reaction especially halogen exchange *** additi... 详细信息

关键词： Poly(diallyldimethylammonium chloride) Phase transfer catalyst Nucleophilic substitution reaction Halogen exchange reaction

Improvement of mechanical behavior of buried pipelines subjected to strike-slip faulting using textured pipeline

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2019年第5期13卷 1105-1119页

作者： mahdi IZADI Khosrow BARGI School of Civil Engineering College of EngineeringUniversity of TehranTehranIran

The present study investigates the mechanical behavior of a new generation of buried pipelines, dubbed the textured pipeline, which is subjected to strike-slip faulting. In conventional cylindrical pipelines, the axial and bending stresses brought about in their walls as a result of fault movement, lead to local buckling, which is construed as one of the major reasons contributing to pipeline failure. The present study has assessed 3-D numerical models of two kinds of buried textured pipelines, with 6 and 12 peripheral triangular facets, subjected to a strike-slip faulting normal to the axis of the pipelines, with and without internal pressure, with the two kinds of X65 and X80 steel, and with different diameter-to-thickness ratios. The results indicate that, because of specific geometry of this pipeline shell which is characterized by having lower axial stiffness and higher bending stiffness, compared to conventional cylindrical pipeline, they are considerably resistant to local (buckling. The results of this study can be conceived of as a first step toward comprehensive seismic studies on this generation of pipelines which aim at replacing the conventional cylindrical pipelines with textured ones in areas subjected to fault movement.

关键词： buried pipeline textured pipeline local buckling

Modified consecutive modal pushover procedure for seismic investigation of one-way asymmetric-plan tall buildings

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2012年第2期11卷 221-232页

作者： Faramarz Khoshnoudian mahdi Kiani Department of Civil Engineering Amirkabir University of TechnologyTehranIran

The effects of higher modes and torsion have a significant impact on the seismic responses of asymmetric-plan tall buildings. A consecutive modal pushover (CMP) procedure is one of the pushover methods that have been developed to consider these effects. The aim of this paper is to modify the (CMP) analysis procedure to estimate the seismic demands of one-way asymmetric-plan tall buildings with dual systems. An analysis of 10-, 15- and 20-story asymmetric-plan buildings is carried out, and the results from the modified consecutive modal pushover (MCMP) procedure are compared with those obtained from the modal pushover analysis (MPA) procedure and the nonlinear time history analysis (NLTHA). The MCMP estimates of the seismic demands of one-way asymmetric-plan buildings demonstrate a reasonable accuracy, compared to the results obtained from the NLTHA. Furthermore, the accuracy of the MCMP procedure in the prediction of plastic hinge rotations is better than the MPA procedure. The new pushover procedure is also more accurate than the FEMA load distribution and the MPA procedure.

关键词： modified consecutive modal pushover seismic demands nonlinear time history analysis asymmetric-plan tall buildings torsion

Robust pre-specified time synchronization of chaotic systems by employing time-varying switching surfaces in the sliding mode control scheme

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第8期25卷 86-93页

作者： Alireza Khanzadeh mahdi Pourgholi Faculty of Electrical Engineering Shahid Beheshti University

In the conventional chaos synchronization methods, the time at which two chaotic systems are synchronized, is usually unknown and depends on initial conditions. In this work based on Lyapunov stability theory a sliding mode controller with time-varying switching surfaces is proposed to achieve chaos synchronization at a pre-specified time for the first time. The proposed controller is able to synchronize chaotic systems precisely at any time when we want. Moreover, by choosing the time-varying switching surfaces in a way that the reaching phase is eliminated, the synchronization becomes robust to uncertainties and exogenous disturbances. Simulation results are presented to show the effectiveness of the proposed method of stabilizing and synchronizing chaotic systems with complete robustness to uncertainty and disturbances exactly at a pre-specified time.

关键词： chaos synchronization finite time synchronization sliding mode controller time varying switching surfaces

Biomaterials for repair and regeneration of the cartilage tissue

在线全文

学校读者我要写书评

暂无评论

Bio-Design and Manufacturing 2019年第1期2卷 41-49页

作者： Mojtaba Ansari mahdi Eshghanmalek Department of Biomedical Engineering Meybod University Meybod. Iran Department of Biomedical Engineering University of Science and Art. Yazd Iran

The repair and regeneration of the diseases and damaged cartilage tissue are one of the most challenging issues in the field of tissue engineering and regenerative medicine. As the cartilage is a non-vascularized and comparatively acellular connective tissue, its ability to the self-restoration is limited to a large extent. Although there is a countless deal of experimental documents on this field, no quantifiable cure exists to bring back the healthy organization and efficacy of the impaired articular cartilage. Tissue reformative approaches have been of excessive curiosity in restoring injured cartilage. Bioengineering of the cartilage has progressed from the cartilage focal damages treatment to bioengineering tactics progress aiming the osteoarthritis procedures. The main focus of the present study is on the diverse potential development of strategies such as various categories of biomaterials applied in the reconstruction of the cartilage tissue.

关键词： Biomaterials Cartilage Tissue engineering Repair 3D bioprinting

Nonlinear Modeling and Analysis of a Novel Robot Fish with Compliant Fluidic Actuator as a Tail

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2022年第3期19卷 629-642页

作者： Behzad Janizadeh Haji mahdi Bamdad School of Mechanical and Mechatronics Engineering Shahrood University of TechnologyShahrood***Iran

Compliant mobile robotics is a developing bioinspired concept of propulsion for *** paper studies the modeling and analysis of a compliant tail-propelled fish-like *** biomimetic design uses a fluid-filled network of channels embedded into the soft body to actuate the compliant tail and generate *** study analyzes the nonlinear dynamics of Fish Tail Fluidic Actuator(FTFA).The fluidic expansion under pressure creates a bending moment in the *** is demonstrated that the tail response follows the theoretical formulation extracted from the accurate *** this modeling,tail is assumed as a continuous Euler–Bernoulli beam considering large deflection and nonlinear ***,the implementation of Hamilton's principle and the method of calculation lead to the motion *** assumed mode method is used to achieve the mathematical model in the multi-mode system that is more similar to the soft continuous *** investigate the tendencies of the tail amplitude,swimming speed,and Strouhal number when the input driving frequency *** simulation results disclose that high swimming efficiency can be obtained at the multi-order resonances;meanwhile,the compliant fish robot is pushed at the corresponding frequency illustrating nonlinear behavior.

关键词： Compliant robotic fish Nonlinear continuous model Fluidic actuator Assume mode method Resonant effect

Theoretical Study of 13C Chemical Shifts Structures of Some ortho-Substituted 3-Anilino-2-nitrobenzo[b]thiophenes and 2-Anilino-3-nitrobenzo[b]thiophenes and Comparison with Experimental

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2011年第2期29卷 237-242页

作者： mahdi Rezaei Sameti Department of Physical Chemistry Faculty of Science Malayer University Malayer 65157 Iran

13C NMR chemical shifts have been calculated for structures of some substituted 3-anilino-2-nitrobenzo- [b]thiophenes （2o） and 2-anilino-3-nitrobenzo[b]thiophenes （3o） derivatives containing OH, NH2, OMe, Me, Et, H, F, Cl and Br. The molecular structures were fully optimized using B3LYP/6-31G（d,p）. The calculation of the 13C shielding tensors employed the GAUSSIAN 03 implementation of the gauge-including atomic orbital （GIAO） and continuous set of gauge transformations （CSGT） by using 6-311 ＋＋G（d,p） basis set at density functional levels of theories （DFT）. The isotropic and the anisotropy parameters of chemical shielding for all compounds are calculated. The predicted 13C chemical shifts are derived from equation δ=σ0＋σ where δ is the chemical shift, σ is the absolute shielding, and σ0 is the absolute shielding of the standard TMS. Excellent linear relationships have been observed between experimental and calculated 13C NMR chemical shifts for all derivatives.

关键词： DPT 13C NMR chemical shifts GIAO/CSGT

Mediterranean Sea level trends from long-period tide gauge time series

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2020年第1期39卷 157-165页

作者： Haddad mahdi Taibi Hebib Centre of Space Techniques Algerian Space Agency

The main purpose of this study is to highlight, on the basis of statistical tests, the significant long-term changes of the Mediterranean Sea level, through the analysis of historical tide gauge records. In this framework, 14 tide gauge monthly series selected from the Permanent Service of the Mean Sea Level(PSMSL) database were used. The search for the presence or not of trends within these series, that have a temporal coverage from 59 to 142 years, was carried out using the Mann-Kendall test and the Sen’s slope estimator. The obtained results show that the Split Rt Marjana series are the only ones which does not exhibit a significant trend. The other 13 series show significant increasing trends. This result seems sufficient to suppose the presence, in the past century, of a new climatic phase on the scale of the Mediterranean basin, where the rising sea level is one of the consequences.

关键词： sea level tidal heights trend analysis Mann-Kendall test Sen’s slope estimates

Kink-band Kinematic Analysis and its Implications for Late-stage Deformation in the Internal Parts of the Zagros Collision(Sanandaj–Sirjan Zone) in West Iran

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2024年第4期98卷 921-935页

作者： Maryam HEYDARI mahdi BEHYARI Department of Geology Faculty of SciencesUrmia University57153165 UrmiaIran

In the internal parts of the Zagros collision zone, several deformation phases have been superimposed. The early deformation phase caused the development of a penetrative foliation. The late-stage deformation phase was preferentially accommodated within shear zones and caused the generation of shear bands, implying a non-coaxial component of deformation, the end of this stage deformation was marked by the development of kink-bands. In the vicinity of Zagros suture zone, the kink angle increased from 40° to 60°, and the kink-bands was converted to chevron folds. In this region, the external(α) and internal(β) angular ratio is α/β ≠ 1 and kink angle increased, and deformation occurred with 10% to 30% volume loss. Farther from the suture zone in the east, α/β = 1;and total volume was constant or increased by 5% to 10%. Kink-bands kinematic analysis in the study area revealed this structures were sensitive to deformation conditions and components such that, with decreasing distance to the Zagros suture zone, shearing and rotation increased, a high kinematic vorticity dominated, and volume loss occurred during deformation.

关键词： kink-band shear zone strain vorticity Zagros Iran

Partial proportional odds model for analyzing pedestrian crashes,threshold heterogeneity by scale and proportional odds factor

在线全文

学校读者我要写书评

暂无评论

Journal of Traffic and Transportation Engineering(English Edition) 2022年第6期9卷 969-977页

作者： mahdi Rezapour Khaled Ksaibati Wyoming Technology Transfer Center University of WyomingLaramieWY 82071USA

Despite low traffic in Wyoming,pedestrian crash severity accounts for a high number of fatalities in the *** this study was conducted to highlights factors contributing to those *** results highlighted that drivers under influence,type of vehicle,location of crashes,estimated speed of vehicles,driving over the recommended speed are some of factors contributing to the severity of *** this study,we used proportional odds model which assumes that the impact of each attribute is consistent or proportional across various threshold ***,it has been argued that this assumption might be unrealistic,especially at the presence of extreme ***,the assumption was relaxed in this study by shifting the thresholds based on some explanatory attributes,or proportional odds *** addition,we accounted for the spread rate,or scale,of the model’s latent distribution of pedestrian *** results highlighted that the partial proportional odds model through proportional odds factor and scale effects result in a significant improvement in model fit compared with the standard proportional odds *** were also made across standard normal,simple partial ordinal model,and partial ordinal accounting for scale *** addition,various potential threshold structures such as symmetric and flexible were considered,but similar goodness of fits were observed across all those *** discussion has been made regarding the formulation of the implemented methodology,and its implications.

关键词： Partial proportional odds model Pedestrian crashes Scale heterogeneity Proportional odds factor Vulnerable road users Drivers’lack of attention