Dynamic expansion modeling of a thick-walled cylinder under internal high strain rate loading

This article presents analysis of the dynamic behavior of a thick-walled cylinder under the assumption of nonlinear strain rate hardening behavior under high strain rate loading before any fracture on the surface. The theoretical model applies both to direct and indirect use of dynamic strength of material and instant boundary conditions to establish a differential equation for radial expansion velocity. Further, detailed discussion will be given with emphasis on the main aspects of the cylinder behavior, i.e., radial displacement, internal pressure, strain rate, flow stress, radial and tangential stress, and the influence of the different material rate sensitive exponent.     

New multi‐standard dual‐wideband and quad‐wideband asymmetric step impedance resonator filters with wide stop band restriction

New multi‐standard wide band filters with compact sizes are designed for wireless communication devices. The proposed structures realize dual‐wideband and quad‐wideband characteristics by using a new skew‐symmetrical coupled pair of asymmetric stepped impedance resonators, combined with other structures. The first and second dual‐wideband filters realize fractional bandwidths (FBW) of 43.2%/31.9% at the central frequencies (CF) of 1.875/1.63 GHz, and second bandwidths of 580 MHz/1.75 GHz at CF of 5.52/4.46 GHz, respectively. The proposed quad‐band filter realizes its first/second/third/fourth pass bands at CF 2.13/5.25/7.685/9.31 GHz with FBW of 46.0%/11.4%/4.6% and 5.4%, respectively. The wide pass bands are attributed to the mutual coupling of the modified ASIR resonators and their bandwidths are controllable by tuning relative parameters while the wide stop band performance is optimized by the novel interdigital cross coupled line structure and parallel uncoupled microstrip line structure. Moreover, the quad band is generated by introducing the novel defected rectangle structure. These multi‐standard filters are simulated, fabricated and measured, and measured results agree well with both simulated results and theory predictions. The good in‐band and out‐of‐band performances, the miniaturized sizes and simple structures of the proposed filters make them very promising for applications in future multi‐standard wireless communication.     

Synthesis of sulfur heterocycles from α,β-unsaturated carbonyl fatty acid esters

Alkyl chain substituted oxathiolanes from allylic oxo are described. Reaction of methyl 4-oxo-trans-2-hexadecenoate (1) with β-mercaptoethanol yields methyl 4-oxathiolane-trans-2-hexadecenoate (II), methyl 4-oxathiolane-2(3)-(S-β-mercaptoethyl acetate) hexadecanoate (III) and methyl 4-oxathiolane-2(3)-(S-β-mercaptoethanol)hexadecanoate (IV).     

Brackish groundwater treatment by reverse osmosis in Jordan

Jordan is characterised by an arid to semi-arid climate and its population is increasing at an annual rate of 3.6%. With such a high population growth rate and fast social-economical development, water demand and wastewater production are steeply increasing, and the gap between water supply and demand is getting wider. Furthermore, the constraints for water resources development are also rising due to high investment costs and water quality degradation due to over-exploitation of aquifers. Desalination of Red Sea water by reverse osmosis (RO) and/or brackish groundwater desalination by nanofiltration or RO might be technically and economically viable to cope with water scarcity and overcome the water deficit in Jordan. The technical-economical feasibility of brackish groundwater treatment by RO for potable water production was investigated in this work. Brackish groundwater samples were collected from the Zarqa basin, Jordan, and characterised in terms of pH, conductivity, total solids, total dissolved solids, total suspended solids, and volatile solids. The water samples were pre-treated through a microfiltration cartridge (5 μm pore diameter) in order to eliminate the suspended matter. A pilot plant equipped with a FilmTec RO membrane (SW30-2521) was operated at 20-30 bar, 40°C, natural pH and up to a water recovery ratio of 77.5%. The results showed that RO is actually efficient since it highly reduced the content of organic and inorganic matters present in raw waters (rejections >98.5%) at a relatively affordable price (0.26 €/m³). This study contributes to the development of efficient technologies to produce affordable potable water in Mediterranean countries where the threat of water shortages is a severe problem.     

Modeling of the mixing of monodisperse particles using a stationary DEM-based Markov process

This paper provides a discussion on the modeling of granular mixing using Markov chain theory. Previous papers on this topic are either based on restrictive underlying assumptions about the flow structure or are limited to a small number of states. In this paper, a generalized approach for the construction of a multidimensional state space first-order Markov chain that represents the mixing of monodisperse particles is introduced. The transition probability matrix is computed directly using results obtained from a discrete element model. This work shows that, if accurate measurements of the state of the system are available, the associated Markov operator leads to a good estimate of the particle dynamics in the system.     

CMOS photodetector systems for low-level light applications

Electron beam induced second harmonic generation (SHG) is studied in Er³⁺ doped PbO–GeO₂ glasses containing silver nanoparticles with concentrations that are controlled by the heat-treatment of the samples. The SHG is observed at T = 4.2 K using a p-polarized laser beam at 1064 nm. Enhancement of the SHG is observed in the samples that are submitted to electron beam incidence. The highest value of the nonlinear susceptibility, 2.08 pm/V, is achieved for the sample heat-treated during 72 h and submitted to an electron beam current of 15 nA. The samples that were not exposed to the electron beam present a susceptibility of ≈0.5 pm/V.     

Cover Picture: Dynamic Imaging of Functionalized Multi‐Walled Carbon Nanotube Systemic Circulation and Urinary Excretion (Adv. Mater. 2/2008)

Multiwalled carbon nanotubes (MWNTs) made highly water‐dispersible by organic functionalization and radiolabeled with Indium‐111 were shown to translocate through the kidney glomerular filter. On p. 225, multinational, multicenter research led by Kostas Kostarelos on dynamic imaging and tissue distribution of MWNTs in live animals is presented. The cover image presents a single plane single photon computed tomography whole body image of a rat following intravenous injection with the In‐111 labeled MWNTs as seen through a 3D carbon NT projection. The radioactivity from carbon NTs was mainly localized in the kidneys, and accumulated in the bladder before clearance in the urine.     

A multisampling time-domain CMOS imager with synchronous readout circuit

A novel multisampling time-domain architecture for CMOS imagers with synchronous readout and wide dynamic range is proposed. The proposed multisampling architecture requires only a single bit per pixel memory instead of 8 bits which is typical for time-domain active pixel architectures. The goal is to obtain a time-domain imager with high dynamic range that requires lower number of transistors per pixel in order to achieve higher fill-factor. The maximum frame rate is analyzed as a function of number of bits and array size. The analysis shows that it is possible to achieve high frame rates and operate in video mode having 10 bit pixel data resolution. Also, we present analysis of the impact of comparator offset voltage on the fixed pattern noise. The architecture was implemented in an imager prototype with 32 × 32 pixel array fabricated in AMS CMOS 0.35 μm and was characterized for sensitivity, noise and color response. The pixel size is 30 μm × 26 μm and it is composed of an n+/psub photodiode, a comparator and a D flip-flop with a 16% fill-factor.