A novel Jacob spectral method for multi-dimensional weakly singular nonlinear Volterra integral equations with nonsmooth solutions

The main purpose of this work is to develop a spectrally accurate collocation method for solving weakly singular integral equations of the second kind with nonsmooth solutions in high dimensions. The proposed spectral collocation method is based on a multivariate Jacobi approximation in the frequency space. The essential idea is to adopt a smoothing transformation for the spectral collocation method to circumvent the curse of singularity at the beginning of time. As such, the singularity of the numerical approximation can be tailored to that of the singular solutions. A rigorous convergence analysis is provided and confirmed by numerical tests with nonsmooth solutions in two dimensions. The results in this paper seem to be the first spectral approach with a theoretical justification for high-dimensional nonlinear weakly singular Volterra type equations with nonsmooth solutions.

     

Impact of graphene oxide nanoparticles and carbon black on the gamma radiation sensitization of acrylonitrile–butadiene rubber seal materials

Seals prepared from acrylonitrile–butadiene rubber (NBR) are primarily used in nuclear services. Nevertheless, at relatively high ionizing radiation doses, NBR seal materials may undergo radiation-induced degradation processes, leading to adverse effects on the sealing ability life. Herein, to strengthen the functional characteristics of NBR seals against radiation, graphene oxide (GO) nanoparticles were prepared and characterized by transmission electron microscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR), and ultraviolet/visible spectroscopies. Various NBR/GO composites fabricated with different ratios of GO nanoparticles and in the presence or absence of carbon black (CB) were investigated via cross-linking density, scanning electron microscopy, XRD, FTIR, and mechanical and thermal stability analyses. The synergistic effect of the simultaneous presence of GO and CB on the NBR seal sensitization to gamma radiation up to a dose of 1 MGy was studied. The physicomechanical properties were enhanced by adding GO nanosheets up to 3 phr and by incorporating 35 phr of a CB with GO until 5 phr. Further, the application of γ-irradiation resulted in an overall enhancement in the mechanical, physical, and thermal stability of the prepared composites up to 0.5 and 1 MGy with GO nanosheets in the absence or presence of CB particles, respectively. The mechanical measurements indicated significant increments by loading with GO nanosheets in the absence and presence of CB as well as by irradiation. The tensile strength elevated up to about 121%, 336%, and 366% by adding 3 phr GO, 3 GO:35 CB phr, and 5 GO:35 CB phr, respectively.     

Issues in the Reconstruction of Gene Order Evolution

As genomes evolve over hundreds of millions years, the chromosomes become rearranged, with segments of some chromosomes inverted, while other chromosomes reciprocally exchange chunks from their ends. These rearrangements lead to the scrambling of the elements of one genome with respect to another descended from a common ancestor. Multidisciplinary work undertakes to mathematically model these processes and to develop statistical analyses and mathematical algorithms to understand the scrambling in the chromo...     

Detection of Fat Concentration in Milk Using Ternary Photonic Crystal

Silicon - Rapid and sensitive detection of fat concentration in milk is a necessary part for citizens in each country. Bio-photonic sensing techniques are an accurate best way to detect biosensing...     

Sre—a syntax recognizing editor

This paper presents a syntax-directed editor dubbed SRE, for syntax recognizing editor. Unlike other syntax-directed editors, SRE enables the user to edit programs with nearly the same natural and unrestrictive ease as a conventional text editor. In addition, it helps identify syntax errors and many typing errors before leaving the editor and attempting to compile a program. Programs are also formatted during entry, thereby providing immediate visual feedback of the recognized structure. The editor replaces the scanner/parser pass of a conventional compiler and thus reduces compilation time substantially.     

计算机环形局部网络的分类方法

本文提出了以时间和空间为参数对计算机环形局部网络进行分类的方法.其中时间和空 间各有三种分配方式,构成了一个既完备又互斥的系统,可以确切地对采用任何一种通讯协议 的环形局部网络进行分类. 作为例子,对迄今已报道的22个环形局部网络进行了分类.从而表明本分类方法是可行 的.     

Developing engineers-some reflections on university education indeveloping countries

The engineering needs of developing countries are quite different from those of advanced, industrial economies, requiring a completely different approach to higher education in technology. The author discusses the role a university, should play in the education of engineers. Engineering requirements and the gap between industry and universities are discussed. The reasons for the large gap in developing countries are mentioned and the choice of a suitable curriculum, taking into account such factors as social background, practical work, and the needs of industry is discussed     

Synthesis,Structure Characterization and Biological Activity of Co (II), Cu (II), and Zn (II) Complexes with (Z)‐3‐((3‐hydroxybenzylidene)amino)pyridin‐1‐ium 4‐(dodecan‐4‐yl)benzenesulfonate Surfactant

(Z)‐3‐((3‐hydroxybenzylidene)amino)pyridin‐1‐ium4‐dodecylbenzenesulfonate anionic surfactant and its cobalt, copper and zinc complexes were synthesized (I, I‐Co, I‐Cu and I‐Zn). The chemical structures of it were characterized by elemental analysis, FTIR, ¹H‐NMR, UV–Vis spectroscopy and atomic adsorption. The effects of the chemical structures of the synthesized anionic surfactant and the type of transition metals on the surface activity are presented in this paper. The thermodynamic parameters show that adsorption and micellization processes are spontaneous. The results of biological activity measurements showed that the synthesized compounds have a great efficiency against gram positive (Bacillus subtilis and Staphylococcus aureus), gram‐ negative bacteria (Pseudomonas aeruginosa and Escherichia coli) and fungi (Candida albicans and Aspergillus niger) as well as the sulfate reducing bacteria (Desulfomonas pigra). The complexation of the anionic surfactant with Co²⁺, Cu²⁺ and Zn²⁺ increase the antimicrobial activity values.     

Fast-transient susceptibility of a D-type flip-flop

Human electrostatic discharge (ESD) produces a transient current pulse with a very fast risetime, which can be a source of electromagnetic interference in digital devices. The focus of this paper is the radiated susceptibility of D-type flip-flops implemented in various CMOS and TTL logic technologies. A transient impulse was used to simulate the radiated field produced during an ESD event. A synchronized-disturbance testing methodology is developed that allows accurate control of the instant at which the disturbing signal is applied to the data input lines during an operational cycle of the circuit. The study reveals that these devices are susceptible only during certain time intervals during an operational cycle. The particular interval during which a flip-flop is susceptible is dependent on the logic state of the data input line, the implementation technology of the flip-flop, and the amplitude of the disturbing signal. The total width of the susceptibility intervals is a device parameter that can be used to determine the probability that the flip-flop will fail in the presence of random transient interference pulses