排序方式: 共有6条查询结果,搜索用时 15 毫秒
1
1.
Laxminarayan Sahoo Anadi Singhamahapatra Katuri J.V. PaulDuraikkannu Loganathan 《Tetrahedron letters》2013
A method for the chemoselective reduction of glycopyranosyl azides using SnCl4 and tin metal as the reducing agent followed by in situ chloroacetylation of the synthesized glycopyranosyl amine was developed. This reaction is applicable to diversely functionalized glycopyranosyl azides for the synthesis of glycopyranosyl chloroacetamides. 相似文献
2.
Flow actuation by a continuous/pulsed, direct-current (DC) surface glow discharge is explored. The discharge comprises an array of pin electrode pairs flush mounted on a dielectric actuator surface that lies adjacent to stagnant air. Strong electrostatic fields produced in the cathode sheath region of the discharge provides a motive force on the ions which in turn drag the background gas resulting in directed air flow from the anode to the cathode. The induced flow velocity is estimated by particle image velocimetry (PIV) at 10 Hz with TiO2 seeding. For a pulsed DC discharge with peak power of 5 W per electrode pair, the induced flow velocity reaches peak values of about 1.7 m/s which is comparable to dielectric-barrier discharge (DBD) or corona discharge actuators. The actuation effect quantified by the magnitude of induced velocity increases as the pulse frequency increases from 0 to 1 kHz. The actuation effect decreases for further increase in frequency above 1 kHz. Decreased actuation effect at high frequency is accompanied by structural change in the discharge. At fixed frequency of 1 kHz, flow actuation effect is highest for a square wave pulse with a duty cycle of 50% indicating that pulsed DC discharges produces better actuation than continuous DC with a corresponding reduction in energy consumption. 相似文献
3.
Yashasvi Laxminarayan Peter Arendt Jensen Hao Wu Flemming Jappe Frandsen Bo Sander Peter Glarborg 《Proceedings of the Combustion Institute》2019,37(3):2689-2696
Fly ash deposition on boiler surfaces is a major operational problem encountered in biomass-fired boilers. Understanding deposit formation, and developing modelling tools, will allow improvements in boiler efficiency and availability. In this study, deposit formation of a model biomass ash species (K2Si4O9) on steel tubes, was investigated in a lab-scale Entrained Flow Reactor. K2Si4O9 was injected into the reactor, to form deposits on an air-cooled probe, simulating deposit formation on superheater tubes in boilers. The influence of flue gas temperature (589 – 968°C), probe surface temperature (300 – 550°C), flue gas velocity (0.7 – 3.5?m/s), fly ash flux (10,000 – 40,000?g/m2h), and probe residence time (up to 60?min) was investigated. The results revealed that increasing flue gas temperature and probe surface temperature increased the sticking probability of the fly ash particles, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, the deposit formation rate increased with probe residence time and fly ash flux. Inertial impaction was the primary mechanism of deposit formation, forming deposits only on the upstream side of the steel tube. A mechanistic model was developed for predicting deposit formation in the reactor. Deposit formation by thermophoresis and inertial impaction was incorporated into the model, and the sticking probability of the ash particles was estimated by accounting for energy dissipation due to particle deformation. The model reasonably predicted the influence of flue gas temperature and fly ash flux on the deposit formation rate. 相似文献
4.
Anadi Singhamahapatra Laxminarayan Sahoo Katuri J.V. Paul Babu Varghese Duraikkannu Loganathan 《Tetrahedron letters》2013
An improved method for the synthesis of per-O-acetylated C-1-hydroxyglycopyranose was developed by hydrolysis of per-O-acetylated glycopyranosyl α-chlorides derived from sugars with C-2 axial acetates for example l-rhamnose and d-mannose. 2,3,4-Tri-O-acetyl-α-l-rhamnopyranose crystallized in tetragonal space group I4, a rare phenomenon in carbohydrate literature. The three dimensional packing of the molecule with the help of regular hydrogen bond and C–H···O interactions resulted in the formation of porous framework showing channels with pore size 7 Å. 相似文献
5.
Jyotirmayee Mohanty Dipak K Palit Laxminarayan V Shastri Avinash V Sapre 《Journal of Chemical Sciences》2000,112(1):63-72
Laser flash photolysis studies were carried out on two types of silver nanoparticles prepared byγ-radiolysis of Ag+ solutions in the presence of polyphosphate as the stabiliser. Type I silver nanoparticles displayed a surface plasmon band
at 390 nm. Type II silver nanoparticles showed a 390 nm surface plasmon band with a shoulder at 550 nm. On photoexcitation
in the surface plasmon band region, using 35 picosecond laser pulses at 355 nm and 532 nm, the type II solutions showed transient
bleaching and absorption signals in the 450–900 nm region, which did not decay appreciably up to 5 nanoseconds. These transient
changes were found to get annealed in the intervalt where 5 ns<t< 100 ns. Extended photolysis of the nanoparticle solutions with repetitive laser pulses resulted in a decrease in the values
of the average particle size which were measured by employing the dynamic light scattering technique. 相似文献
6.
The purpose of this paper is to study the duality theorems in cone constrained multiobjective nonlinear programming for pseudo-invex objectives and quasi-invex constrains and the constraint cones are arbitrary closed convex ones and not necessarily the nonnegative orthants. 相似文献
1