A study of the effect of the deformation parameters on recrystallization behavior in the rod rolling process

Rod rolling is a process in which the deformation of the workpiece between the work rolls is quite different from the rod drawing process, but the area strains (natural logarithm of area reduction ratio) multiplied by a constant have been used in the calculation of the pass-by-pass evolution of austenite grain size in rod (or bar) rolling without any verification. Considering that the deformation parameters (strain and strain rate) at a given pass play a crucial role in determining recrystallization behavior, the calculation method for the deformation parameters associated with rod rolling should be examined. In this study, a series of numerical simulations has been carried out using an area strain model [5] and an analytic model [6] which calculate the pass-by-pass strain in the rod rolling process, focusing on the effect of the calculation method for the pass-by-pass strain on the recrystallization behavior and evolution of AGS (austenite grain size) during a given pass. These have been investigated for a six-pass rolling sequence (oval-round or round-oval) designed for this study by incorporating the recrystallization and AGS evolution model being widely used in hot rolling. It was found that the recrystallization behavior and evolution of AGS during a given pass were significantly influenced by the calculation methods for deformation parameters. The area strain model lacks mathematical grounds to be used as input to the equations for recrystallization and AGS evolution.     

High performance modules of 2.5 Gbps modulator integrated DFBlasers using new RF impedance matching technique

We report the improvement of frequency response characteristics of 2.5 Gbps modulator integrated distributed feedback (MI-DFB) laser modules using new impedance matching technique. Frequency responses for the fabricated module using the `+' shaped microstrip line for impedance matching have been significantly improved such as the RF return loss of 11 dB and the 3 dB frequency bandwidth of 4.1 GHz, compared to 6 dB return loss and 1.5 GHz bandwidth for the conventional module. These results can also be predicted by the simulation of frequency responses for the modules, From the fabricated MI-DFB laser modules, good transmission performance has been obtained up to 640 km     

Water Flow through Cover Soils Using Modeling and Experimental Methods

The vertical flow of water in cover soils is simulated using published analytical and finite-element methods. The two methods gave virtually identical pressure head and water content profiles during steady infiltration of water in a multilayer soil cover and transient infiltration in a single-layer cover. The finite-element model was then used to simulate flow in two laboratory columns packed with multilayer soils and subjected to downward drainage and conditions of evaporation and no evaporation. The model adequately predicted transient pressure heads and water contents for the first 7.5 h of drainage in a till-sand layer without evaporation. Predictions at times equal to and greater than 3 days were not as good, probably due to the formation of discontinuous water pockets in the draining sand around the residual water content, which apparently produced “locked-in” or “static” nonequilibrium pressures. These pressures are not captured by existing methods used for estimating the unsaturated hydraulic conductivity–pressure function of soils. Further modeling showed that at times greater than 8 days, the flux from the column with evaporation was all in the vapor phase.     

Fade and non-fade duration statistics for Earth-space satellitelink in Ku-band

The choice of modulation and forward error correction coding for satellite communications depends on fade dynamics and long-term fade occurrence statistics. An investigation is presented of the fade duration and inter-fade duration measured with a dual slope Ku-band radiometer as well as a Ku-band INTELSAT VI beacon receiver in Singapore which has an equatorial climate. A comparison of the results from both the measurements is presented. The normalised fade duration obtained follows a lognormal distribution with median of 1.3 and a standard deviation of 2     

Real time linear simulation and control for small aircraft turbojet engine

The performance of the aircraft gas turbine engine requires optimization because it is directly related to overall aircraft performance. In this study, a modified DYNGEN, a nolinear dynamic simulation program with component maps of the small aircraft turbojet engine, was used to predict the overall engine performance. Response characteristics of various cases, such as 6%, 5% and 3% rpm step models and the real-time linear model of the interpolation scheme within the operating range were compared. Among them, the real time linear model was selected for the turbojet engine with nonlinear characteristics. Finally control schemes such as PI (Proportional-Integral Controller) and LQR (Linear Quadratic Regulator) were applied to optimize the engine performance. The overshoot of the turbine inlet temperature was effectively eliminated by LQR controller with the proper control gain K.     

Promoting GAINs (Give Attention to Limitations in Assays) over PAINs Alerts: no PAINS,more GAINs

Many concepts and guidelines in medicinal chemistry have been introduced to aid in successful drug discovery and development. An example is the concept of Pan-Assay Interference Compounds (PAINS) and the elimination of such nuisance compounds from high-throughput screening (HTS) libraries. PAINs, along with other guidelines in medicinal chemistry, are like double-edged swords. If used appropriately, they may be beneficial for drug discovery and development. However, rigid and blind use of such concepts can hinder productivity. In this perspective, we introduce GAINS ( g ive a ttention to l i mitatio n s in assay s ) and highlight its relevance for successful drug discovery.