On the Noisy Feedback Capacity of Gaussian Broadcast Channels

It is well known that, in general, feedback may enlarge the capacity region of Gaussian broadcast channels. This has been demonstrated even when the feedback is noisy (or partial-but-perfect) and only from one of the receivers. The only case known where feedback has been shown not to enlarge the capacity region is when the channel is physically degraded (El Gamal 1978, 1981). In this paper, we show that for a class of two-user Gaussian broadcast channels (not necessarily physically degraded), passively feeding back the stronger user's signal over a link corrupted by Gaussian noise does not enlarge the capacity region if the variance of feedback noise is above a certain threshold.Comment: 5 pages, 3 figures, to appear in IEEE Information Theory Workshop 2015, Jerusale

Parametric Programming on an Analog Computer

The object of this investigation is to use the general purpose analog computer to simulate a linear programming problem and to extend the general purpose model developed by Pyne, to handle parametric programming, sensitivity analysis and post-optimum analysis. More-over, it is also intended to demonstrate how the information provided by the index row of the simplex tableau could be made available from this dynamic analog model

FIR Filter Implementation by Efficient Sharing of Horizontal and Vertical Common Sub-expressions

No abstract availabl

The effect of gravity on liquid plug propagation in a two-dimensional channel

The effect of plug propagation speed and gravity on the quasisteady motion of a liquid plug in a two-dimensional liquid-lined channel oriented at an angle αα with respect to gravity is studied. The problem is motivated by the transport of liquid plugs instilled into pulmonary airways in medical treatments such as surfactant replacement therapy, drug delivery, and liquid ventilation. The capillary number Ca is assumed to be small, while the Bond number Bo is arbitrary. Using matched asymptotic expansions and lubrication theory, expressions are obtained for the thickness of the trailing films left behind by the plug and the pressure drop across it as functions of Ca, Bo, αα and the thickness of the precursor films. When the Bond number is small it is found that the trailing film thickness and the flow contribution to the pressure drop scale as Ca2/3Ca2∕3 at leading order with coefficients that depend on Bo and αα. The first correction to the film thickness is found to occur at O(Ca)O(Ca) compared to O(Ca4/3)O(Ca4∕3) in the Bo = 0Bo=0 case. Asymmetry in the liquid distribution is quantified by calculating the ratio of liquid volumes above and below the centerline of the channel, VṘ. VR = 1VR=1 at Bo = 0Bo=0, indicating a symmetric distribution, and decreases with Bo and Ca, but increases with the plug length LpLp. The decrease of VRVR with Ca suggests that higher propagation speeds in small airways may result in less homogenous liquid distribution, which is in contrast to the expected effect in large airways. For given values of the other parameters, a maximum capillary number CacCac is identified above which the plug will eventually rupture. When the Bond number becomes equal to an orientation-dependent critical value BocBoc, it is found that the scaling of the film thickness and pressure drop change to Ca1/2Ca1∕2 and Ca1/6Ca1∕6, respectively. It is shown that this scaling is valid for small increments of the Bond number over its critical value, Bo = Boc+BCa1/6Bo=Boc+BCa1∕6, but for higher Bond numbers the asymptotic approach breaks down.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87914/2/031507_1.pd

Reproductive biology and artificial propagation of chocolate mahseer Neolissocheilus hexagonolepis (Mc Clelland) in Meghalaya, India

The chocolate mahseer Neolissocheilus hexagonolepis (Mc Clelland) is a commercially important species of mahseer group which needs immediate attention due to its reduced abundance in Meghalaya. This fish is widely recognized as a sport fish by the anglers, as ornamental fish by the hobbyists and also a priced food fish. Fishes were found to mature from May onwards and gravid fishes were available in rivers from July to September. Females were larger in size when compared to males in the same age group. The sex ratio observed was 1 female: 1.26 male. Attainment of first maturity occurred when males were 9+ months and females were 11+ months old. The minimal length and weight at first maturity of female fishes were 17.8 cm and 70 g respectively whereas males attained maturity at an average length of 17.3 cm and weight of 50 g. The Gonado-somatic Index in ripe female was 16.19 and the average fecundity factor was 70.18. The fish was bred successfully in captive condition through stripping. Fertilization percentage of eggs ranged from 80 to 85. Incubation period varied between 81-97 hours and the percentage of hatching was 75-80. Yolk-sac absorption in larvae was complete in 6+ days after hatching. The spawn was stocked in glass aquaria and on an average, 85% survival was recorded after 15 days of rearing when they attained an average length of 2.084 cm and weight of 0.195 g. The fry was subsequently reared in cement cisterns @ 1 no./l and on an average, 92% survival was recorded after 60 days of rearing. During this period, the fish attained an average length of 4.82 cm and weight of 0.856 g