Sharif Digital Repository

Determination of the time lag caused by utilization of different tubes to measure pressure on the surface of a wind tunnel model is an important problem in the field of aerodynamic especially for unsteady measurements where the pressure signature changes continuously with time. In this investigation the time required for the applied pressure at one end of different tubes to reach its original value (applied pressure) at the other end has been measured. Three plastic tubes and two polyethylene tubes with different lengths and different inner diameters; L=2, 5 and 10 m, d=1, 2 and 4 mm, were used to study the time lag. Experimental data show that the response time in a pressure measuring... 

The Outer Hadron Calorimeter (HCAL HO) of the CMS detector is designed to measure the energy that is not contained by the barrel (HCAL HB) and electromagnetic (ECAL EB) calorimeters. Due to space limitation the barrel calorimeters do not contain completely the hadronic shower and an outer calorimeter (HO) was designed, constructed and inserted in the muon system of CMS to measure the energy leakage. Testing and calibration of the HO was carried out in a 300 GeV/c test beam that improved the linearity and resolution. HO will provide a net improvement in missing E T measurements at LHC energies. Information from HO will also be used for the muon trigger in CMS. © 2008 Springer-Verlag / Società... 

The Compact Muon Solenoid (CMS) experiment is operating at the Large Hadron Collider (LHC) with proton-proton collisions at 13-TeV center-of-mass energy and at a bunch spacing of 25 ns. Challenging running conditions for CMS are expected after the High-Luminosity upgrade of the LHC (HL-LHC). We review the CMS ECAL crystal calorimeter upgrade and present results from the first test beam studies. Particular challenges at HL-LHC are the harsh radiation environment, the increasing data rates, and the extreme level of pile-up events, with up to 200 simultaneous proton-proton collisions. Precision timing can be exploited to reduce the effect of the pileup. We report on the timing resolution... 

In this paper a novel method, called PC-PMC, is proposed to improve the performance of automatic speech recognition systems in noisy environments. This method is based on the parallel model combination (PMC) technique and uses the Cepstral Mean Subtraction (CMS) normalization ability and Principal Component Analysis (PCA) compression and decorrelation capabilities. It takes the advantages of both additive noise compensation of PMC and convolutive noise removal ability of CMS and PCA. The first problem to be solved in the realizing of PC-PMC is that PMC algorithm requires invertible modules in the front-end of the system while CMS normalization is not an invertible process. Also, it is... 

In this article, effects of magnetic fields induced by a finite length solenoid on the forced-convection heat transfer in a pipe partially filled with porous medium have been investigated. In this regard, two-dimensional steady-state fluid flow in the pipe was considered and the Darcy–Brinkman equation of motion was applied to model the fluid flow in the porous medium, as well as the thermal equilibrium was assumed between the solid phase and the magnetic nanofluid. Effects of electric current passing through the solenoid and the solenoid dimensions (i.e.; diameter and length) on the forced-convection heat transfer were studied carefully. The combined effects of the magnetic field and the... 

In order to deal with the limitations of micro-pumps and micro-valves and meet the advantages of magnetic systems a novel plan is described here. The idea behind the plan is that magnetic particles, mixed and dispersed in a carrier liquid, can be accumulated and retained at specific sites to form pistons in a micro-tube using some external magnetic field sources along the tube. In other words, using some solenoids and switching them on and off, in a specific order and period, causes the desired external magnetic field variation through the tube. Changing the period and the mode of activation and deactivation of the solenoids, which are called switching time and switching mode, respectively,... 

The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...