Buckling of imperfect functionally graded plates under in-plane compressive loading

Buckling behavior of rectangular functionally graded plates with geometrical imperfections is studied in this paper. The equilibrium, stability, and compatibility equations of an imperfect functionally graded plate are derived using the classical plate theory. It is assumed that the nonhomogeneous mechanical properties of the plate, graded through thickness, are described by a power function of the thickness variable. The plate is assumed to be under in-plane compressive loading. Simultaneous solving of the stability and compatibility equations in conjunction with the equilibrium equations leads to the buckling relation of the plate. The critical buckling load of a sample plate is obtained and compared for different geometrical ratios. The results are reduced and compared with the results of perfect functionally graded and imperfect isotropic plates.     

A new hybrid feature extraction method in a dyadic scheme for classification of hyperspectral data

The feature extraction is an important preprocessing step of the classification procedure particularly in high-dimensional data with limited number of training samples. Conventional supervised feature extraction methods, for example, linear discriminant analysis (LDA), generalized discriminant analysis, and non-parametric weighted feature extraction ones, need to calculate scatter matrices. In these methods, within-class and between-class scatter matrices are used to formulate the criterion of class separability. Because of the limited number of training samples, the accurate estimation of these matrices is not possible. So the classification accuracy of these methods falls in a small sample size situation. To cope with this problem, a new supervised feature extraction method namely, feature extraction using attraction points (FEUAP) has been recently proposed in which no statistical moments are used. Thus, it works well using limited training samples. To take advantage of this method and LDA one, this article combines them by a dyadic scheme. In the proposed scheme, the similar classes are grouped hierarchically by the k-means algorithm so that a tree with some nodes is constructed. Then the class of each pixel is determined from this scheme. To determine the class of each pixel, depending on the node of the tree, we use FEUAP or LDA for a limited or large number of training samples, respectively. The experimental results demonstrate the better performance of the proposed hybrid method in comparison with other supervised feature extraction methods in a small sample size situation.     

Semigroups of matrices with dense orbits

We give examples of n?×?n matrices A and B over the field 𝕂?=?? or ? such that for almost every column vector x?∈?𝕂 ⁿ , the orbit of x under the action of the semigroup generated by A and B is dense in 𝕂 ⁿ .     

Switch-level soft error emulation for SET-induced pulses of variable strengths

Due to the increased complexity of modern digital circuits, the use of simulation-based soft error detection methods has become cumbersome and very time-consuming. FPGA-based emulation provides an attractive alternative, as it can not only provide faster speed, but also handle highly complex circuits. In this work, a novel FPGA-based soft error detection technique is proposed, which enables detection of soft errors resulting from voltage pulses of different magnitudes induced by single-event transients (SETs). The paper analyzes the effect of transient injection location on soft error rate (SER) and applies the idea of transient equivalence to minimize resource overhead as well as speed-up emulation process. Switch-level implementations of ISCAS’85 benchmarks are designed using gate-level structures and experimental results are reported. The results show that an application of transient equivalence results in an emulation speed-up of 2.875 and reduces the memory utilization by 65%. An average soft error rate (SER) of 0.7-0.8 was achieved using the proposed strength-based detection with drain as transient injection location, showing that voltage pulses of magnitude smaller than logic threshold can eventually result in soft errors. Furthermore, the presented emulation-based soft error detection technique achieved significant speed-up of the order of 10⁶ compared to a customized simulation-based method.     

THERMAL BUCKLING OF FUNCTIONALLY GRADED PLATES BASED ON HIGHER ORDER THEORY

Equilibrium and stability equations of a rectangular plate made of functionally graded material (FGM) under thermal loads are derived, based on the higher order shear deformation plate theory. Assuming that the material properties vary as a power form of the thickness coordinate variable z and using the variational method, the system of fundamental partial differential equations is established. The derived equilibrium and stability equations for functionally graded plates (FGPs) are identical to the equations for laminated composite plates. A buckling analysis of a functionally graded plate under four types of thermal loads is carried out and results in closed-form solutions. The critical buckling temperature relations are reduced to the respective relations for functionally graded plates with a linear composition of constituent materials and homogeneous plates. The results are compared with the critical buckling temperatures obtained for functionally graded plates based on classical plate theory given in the literature. The study concludes that higher order shear deformation theory accurately predicts the behavior of functionally graded plates, whereas the classical plate theory overestimates buckling temperatures.     

Determination of Vanadyl Ions by a New PVC Membrane Sensor Based on N, N'-bis-(Salicylidene)-2,2-Dimethylpropane-1,3-Diamine

N, N'-bis-(salicylidene)-2,2-dimethylpropane-1,3-diamine (NNPD) was found to be a suitable neutral ion carrier for the construction of a highly selective and sensitive vanadyl membrane sensor. Poly(vinyl chloride) (PVC) based membranes of NNPD with potassium tetrakis (p-chlorophenyl) borate (KTpCIPB) as an anionic excluder and diethyl sebacate (DES), dibutyl phthalate (DBP), banzyl acetate (BA) and o-nitrophenyloctyl ether (NPOE) as plasticizing solvent mediators were investigated in vanadyl membrane sensors. A membrane, composed of NNPD-PVC-KTpCIPB-DES with the ratio 4.0:30.0:1.0:65.0, works well over a wide concentration range (7.0 times 10^-6 to 1.0 times 10 ^-2 M) with a Nernstian slope of 28.8plusmn0.3 mV per decade of activity between pH values of 4.0 and 5.10. The detection limit of the sensor was calculated to be 5.0 times 10^-6 M. It displays satisfactorily good discrimination toward vanadyl ions with regard to most common transitional metal ions. The proposed sensor demonstrates a short response time (-10 s). It was successfully applied for the determination of vanadyl ions in water samples     

Preparation of Fentanyl Labeled with Carbon-14

A convenient synthetic pathway for ¹⁴C labeling of fentanyl [N-(1-phenethyl-4-piperidinyl)- propionanilide], a widely used narcotic analgesic agent, with good radiochemical yield was developed.     

Synthesis of a carbon-14 analog of 8-chloro-11- (4-methyl-1-piperazinyl)-11-[<Superscript>14</Superscript>C]-5<Emphasis Type="Italic">H</Emphasis>-dibenzo[<Emphasis Type="Italic">b,e</Emphasis>][1,4]diazepine (clozapine) using microwave irradiation

8-Chloro-11-(4-methylpiperazin-1-yl)-5H-dibenzo[b,e][1,4]diazepine labeled with ¹⁴C in 11-position was synthesized in four steps from [carboxyl-¹⁴C]anthranilic acid using microwave irradiation with good overall radiochemical yield.