A system for the exposure of small laboratory animals to a 25-mT60-Hz alternating or traveling magnetic field

A versatile exposure system which can be used to investigate the effects of a 60-Hz alternating magnetic field or traveling magnetic field on small laboratory animals is described. Special attention was given to the design of the electric circuit to simplify the supply requirements and to keep the overall current to a minimum. A magnetic field having a flux density up to 30 mT (300 G) can be generated, and a traveling magnetic field is obtained by reconnecting the coils to a three-phase supply. The total magnetic field due to the currents in the three coils used in the exposure system is analyzed. A computer program was written to evaluate the magnetic field in the region where the animals are located. The difference observed between measured and computed values is attributed to the representation of the multiturn, multilayer coils by equivalent single-turn coils     

Existence of solitary waves in a prestressed nonlinear thermoelastic medium with dry friction

V. I. Lenin Belorussian State University, Minsk. Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 62, No. 1, pp. 140–145, January, 1992.     

弯曲受力时中空管以及混凝土填充纤维复合管的有限元模型:部分填充优化和杆设计方法

非线性有限元模型的拓展与验证在相关的论文(Son J,Fam A.中空管以及混凝土填充纤维复合管的有限元模型:第一部分——抗弯模型拓展与验证)中已被用于研究部分填充混凝土纤维增强复合材料线杆的抗弯性能。为提高抗弯强度和稳定性,建议采用部分填充厚壁管来降低造价。对不同直径与厚度比以及不同分层结构的悬臂单杆进行混凝土部分填充长度优化。研究发现,当下列任意一种情况出现时,优化长度会减少:当直径与厚度比变小时;当纤维角度相对于弯曲管纵向轴夹角增加时;当弯曲管中纵向纤维减少时;当采用侧向分布荷载代替端部集中荷载时。建立了计算中空管和混凝土填充FRP管承载力矩的简单表达式,基于同时发生在中空管和混凝土填充管处的破坏,结合简单的设计方法体系来优化混凝土填充管的长度。同时提出了计算锥形线杆的程序。     

Flexural Behavior of Concrete-Filled Fiber-Reinforced Polymer Circular Tubes

This paper presents the experimental results of large-scale concrete-filled glass fiber reinforced polymer (GFRP) circular tubes and control hollow GFRP and steel tubes tested in bending. The diameter of the beams ranged from 89 to 942 mm and the spans ranged from 1.07 to 10.4 m. The study investigated the effects of concrete filling, cross-sectional configurations including tubes with a central hole, tube-in-tube with concrete filling in between, and different laminate structures of the GFRP tubes. The study demonstrated the benefits of concrete filling, and showed that a higher strength-to-weight ratio can be achieved by providing a central hole. The results indicated that the flexural behavior is highly dependent on the stiffness and diameter-to-thickness ratio of the tube, and, to a much less extent, on the concrete strength. Test results suggest that the contribution of concrete confinement to the flexural strength is insignificant; however, the ductility of the member is improved. A strain compatibility model has been developed, verified by the experimental results, and used to provide a parametric study of the different parameters, significantly affecting the behavior. The parametric study covered a wide range of FRP sections filled with concrete, including under-reinforced, balanced, and over-reinforced sections.     

The effects of long‐term exposure of flax fiber reinforced polymer to salt solution at high temperature on tensile properties

Most research on natural fiber composites has been primarily conducted on randomly‐oriented fibers. This study is focused on the short‐ and long‐term performances of flax fiber‐reinforced polymer (Flax‐FRP) made from continuous unidirectional fiber mats, and compares it to Glass‐FRP composite. The study looked into the effect of number of layers on properties, comparing wet layup (WL) to vacuum bag (VB) molding, and aging in a 3.5% salt solution for up to 365 days at 23, 40, and 55°C. Results show that Flax‐FRP has a tensile strength and modulus of one third the values of Glass‐FRP. Using the VB process, Flax‐FRP showed a strength and modulus 18 and 36% higher, respectively, than WL specimens. As the number of layers increased from one to five, the strength and modulus also increased but stabilized at three layers. After 365 days of conditioning at 23, 40, and 55°C, WL specimens showed a strength retention of 81, 73, and 69%, respectively. Using the Arrhenius relationship, it was estimated that both WL and VB Flax‐FRP would retain 60% of their tensile strength after 100 years of saltwater exposure at an annual mean temperature of 10°C. POLYM. COMPOS., 37:3234–3244, 2016. © 2015 Society of Plastics Engineers     

Variational estimates of the effective thermal conductivities of transversely isotropic composites

A study is made of a type of composite material that is widely used in practical applications — a composite with fibers of constant cross section arranged parallel to one another in the matrix. The effective thermal conductivities of transversely Isotropie composites is estimated on the basis of dual variational principles from thermostatics. Certain geometric models that are of practical interest are examined and refined estimates of their effective conductivities are obtained. Due to mathematical equivalence, the results obtained can also be used for effective electrical conductivity, the effective diffusion coefficient, effective permittivity, and effective permeability.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 59, No. 10, pp. 562–568, October, 1990.     

Some synthetic detergents from petroleum products

Deodorized and dewaxed Egyptian petroleum fraction, boiling range 200–270 C, was subjected to liquid phase oxidation at various temperatures in the presence of Co acetate as catalyst. The synthesized naphthenic acids were then converted to naphthenic acid amides and naphthenic alcohols. These products were ethoxylated to different mole ratios of ethylene oxide. The ethoxylates with an average 5 mol ethylene oxide/mol prepared hydrophobes were sulphated and phosphated to anionics. The surface active properties of all the nonionic and anionic surfactants were evaluated.