Mid infrared resonant cavity detectors and lasers with epitaxial lead-chalcogenides

Wavelength tunable emitters and detectors in the mid-IR wavelength region allow applications including thermal imaging and gas spectroscopy. One way to realize such tunable devices is by using a resonant cavity. By mechanically changing the cavity length with MEMS mirror techniques, the wavelengths may be tuned over a considerable range.     

Comparison of phase error sensitivities of all-optical discrete Fourier transforms for OFDM demultiplexing

The design of three different filter structures for the separation of 8 sub-channels in an optical OFDM system are compared. They are based on serial, serial-parallel and parallel filtering and can be realized as planar lightwave circuits. We investigate the tolerance towards phase errors in these structures using a Monte-Carlo simulation.     

Reductive Coupling of Carbonyl Compounds to Pinacols with Zinc in THF-Saturated Aqueous Ammonium Chloride

Summary.  In the presence of metallic zinc, aldehydes and ketones experience reductive coupling in tetrahydrofuran-saturated aqueous ammonium chloride (5:3) to afford the corresponding pinacols in moderate to high yields. Received October 23, 2000. Accepted (revised) December 12, 2000     

Thermodynamic simulation of performance of a dual cycle with stroke length and volumetric efficiency

This article presents finite-time thermodynamics analysis of an irreversible air standard dual cycle. An irreversible dual cycle model which is more close to practice is established. In this model, the effects of stroke length and volume efficiency by considering the nonlinear relation between the specific heats of working fluid and its temperature, the frictional loss, the internal irreversibility, and heat transfer loss are analyzed. The results show that if compression ratio is less than certain value, the power output increases with increasing stroke length, while if compression ratio exceeds certain value, the power output first increases and then starts to decrease with increasing stroke length. With further increase in compression ratio, the increase of stroke length results in decreasing the power output. The results also show that, throughout the compression ratio range, the power output increases with the increasing volumetric efficiency. The results obtained in this study are of importance to provide good guidance for performance evaluation and improvement of practical internal combustion engines.     

Hybrid silica-organic material with immobilized amino groups: surface probing and use for electrochemical determination of nitrite ions

A sol–gel based hybrid process was developed by manipulating different techniques in sol–gel process to synthesize γ-alumina and (CuO, CuO + ZnO) doped γ-alumina spherical particles. Catalysts having spherical geometry have an important advantage over powders or pellets which are impervious to fluids, when packed in a reactor. Boehmite sol was used as alumina precursor for synthesizing porous γ-alumina and doped materials. γ-alumina particles having 5 wt% CuO, 4 wt% CuO + 1 wt% ZnO, 3 wt% CuO + 2 wt% ZnO and 2 wt% CuO + 3 wt% ZnO were prepared by adding required amounts of Cu(NO₃)₂ and Zn(NO₃)₂ solutions prior to gelation of the sol. Methanol dehydration studies were carried out by employing these synthesized catalysts. Hundred percent conversion of methanol to dimethyl ether was observed with (4 wt% CuO + 1 wt% ZnO)-γ-alumina and (5 wt% CuO)-γ-alumina microspheres at 325 and 350 °C, respectively.     

SYNTHESIS OF NEW BENZOSULFOXIDE MACROCYCLIC COMPOUNDS

Bis(dibenzosulfoxo)-27,30,35,38-tetramethyl-24-crown-6, bis(dibenzosulfoxo)-21,24,29,32-tetramethyl-18-crown-4, dibenzosulfoxo-15,18-dimethyl-12-crown-3 and dibenzosulfoxo-12,15-dimethyl-9-crown-2 macrocycles are synthesized by the reaction of 2,2′-sulfinyl-bis(4-methyl phenol)and 1,2-dibromoethane and diethyleneglycol di-p-toluenesulfonate.     

A hybrid proximal point algorithm for finding minimizers and fixed points in CAT(0) spaces

We introduce a hybrid proximal point algorithm and establish its strong convergence to a common solution of a proximal point of a lower semi-continuous mapping and a fixed point of a demicontractive mapping in the framework of a CAT(0) space. As applications of our new result, we solve variational inequality problems for these mappings on a Hilbert space. Illustrative example is given to validate theoretical result obtained herein.