Band Limited Signals Observed Over Finite Spatial and Temporal Windows: An Upper Bound to Signal Degrees of Freedom

The study of degrees of freedom of signals observed within spatially diverse broadband multipath fields is an area of ongoing investigation and has a wide range of applications, including characterising broadband MIMO and cooperative networks. However, a fundamental question arises: given a size limitation on the observation region, what is the upper bound on the degrees of freedom of signals observed within a broadband multipath field over a finite time window? In order to address this question, we characterize the multipath field as a sum of a finite number of orthogonal waveforms or spatial modes. We show that (i) the "effective observation time" is independent of spatial modes and different from actual observation time, (ii) in wideband transmission regimes, the "effective bandwidth" is spatial mode dependent and varies from the given frequency bandwidth. These findings clearly indicate the strong coupling between space and time as well as space and frequency in spatially diverse wideband multipath fields. As a result, signal degrees of freedom does not agree with the well-established degrees of freedom result as a product of spatial degrees of freedom and time-frequency degrees of freedom. Instead, analogous to Shannon's communication model where signals are encoded in only one spatial mode, the available signal degrees of freedom in spatially diverse wideband multipath fields is the time-bandwidth product result extended from one spatial mode to finite modes. We also show that the degrees of freedom is affected by the acceptable signal to noise ratio (SNR) in each spatial mode.Comment: Submitted to IEEE Transactions on Signal Processin

Preparation and characterization of mixed matrix membrane based on Polysulfone (PSF) and Lanthanum Orthoferrite (LaFeO3) for gas separation

The aim of this study is to investigate the effects of polysulfone (PSF) and lanthanum orthoferrite (LaFeO3) incorporated mixed matrix membrane (MMM) on gas permeation and selectivity properties. PSF/LaFeO3 MMMs were prepared with various weights loading of LaFeO3. The membranes obtained were characterized using scanning electron microscope (SEM), thermal gravimetric analysis (TGA) and Fourier-transform infra-red (FT-IR). The gas transport properties of MMM were measured using single gas permeation set up (CO2, CH4, O2 and N2) at ambient temperature, and feed pressure of 2, 4 and 6 bar. The permeation test showed that the mixed matrix membrane exhibited high permeability. With increasing LaFeO3 weight loading to 1.0%, the highest permeability values were 47.74 GPU for CO2, 29.85 GPU for CH4, 57.56 GPU for O2, and 40.66 GPU for N2. The results also showed that by incorporating 1.0wt% of LaFeO3 into PSF matrix, the highest CO2/CH4 and O2/N2 selectivity of 1.60 and 1.42 respectively were obtained. Overall, all the resultants MMM showed higher permeability and selectivity compared to pure PSF membrane

Contrast of Bayesian and Classical Sample Size Determination

Sample size determination is a prerequisite for statistical surveys. A comprehensive overview of the Bayesian approach for computation of the sample size, and a comparison with classical approaches, is presented. Two surveys are taken as example to illustrate the accuracy and efficiency of each approach, and to make recommendations about which method is preferred. The Bayesian approach of sample size determination may require fewer subjects if proper prior information is available

Percentage composition of Brachyuran larvae collected during 1994 in Manora Channel, Karachi, Pakistan

Brachyuran larvae are the most common zooplankton component of the Manora Channel, Karachi, Pakistan. The identification of these larvae would assist in the assessment of brachyuran species and provide information on percentage composition, occurrence, abundance and breeding habits of the brachyuran species in the Manora Channel area. However plankton caught larvae is not easily identified. An accurate identification of such material is only possible by the comparison with larvae reared under laboratory conditions and documented with illustrations. The identifications for this present study were based on the works of Gurney (1938); Atkins (1954); Chhapgar (1955); Raja Bai (1960); Hashmi (1969, 1970a, b); Baba and Miyata (1971); Kakati and Sankolli (1975); Rice (1975); Kakati (1977); Lim and Tan (1981); Yatsuzuka and Sakai (1984); Fielder, et al (1984); Amir (1989, M. Phil thesis unpublished); Ingle (1992); Siddiqui and Tirmizi (1992); Tirmizi et al (1993); Bano (1999, M. Phil thesis unpublished); Ghory and Siddiqui (2001); Ghory (2002, M. Phil thesis unpublished); Ghory and Siddiqui (2002)

Survey on Cyber Attacks and Initial methods for its avoidance

A survey paper on the cyber crime which effected so many digital systems as we are very much depending upon internet for so many things in our daily life. It describes about the various cyber attacks around the world.In the early days of personal computing, malware threats like the infamous Brain virus, was distributed using floppy disk and were easily localized and handled. But after long time because of the Internet the cybercrime was massively distributed. From there we have seen methods of attacking increased drastically which became more prevalent. One of the most difficult things to counter about all of these cyber threats is that they are now truly personal. The one such example is ransomeware which will attack the victim’s system and demand him to pay money called ransome. Unless until he pay’s the attacker will not resume the system from his control. Recently we had heard that so many banking systems were hacked due to this cyber threat ransome, In this paper I am giving some of the examples of different kinds of cyber attacks

Occurrence and abundance of brachyuran larvae in the Manora Channel (Karachi, Pakistan) during 1993

The present paper investigates the occurrence and abundance of brachyuran larvae in the Manora Channel during August- December 1993. The fortnightly planktonic sampling was carried out in Manora Channel which is bordered by mangroves, during day time from surface and subsurface waters at shallow depth using Bongo net of 300 micron mesh size. Analysis of samples revealed presence of brachyuran larvae of 12 species belonging to 6 families. Of these 4 species are confirmed: Serenella indica, Dotilla blanfordi, Metopograpsus thukuhar and Clistocoeloma lanatum, 2 provisionally identified species are: Pilumnus ?karachiensis and Pinnotheres ?pisum, 2 species are identified upto generic level: Philyra sp. and Pinnotheres sp., and 1 Ocypodid species and 3 Xanthid species are identified upto family level. This study based on identification, occurrence and abundance of brachyuran larvae in the area, also gives percentage composition of brachyuran larvae collected during 1993, in the Manora Channel

Distributional patterns of brachyuran larvae in Manora Channel (Karachi, Pakistan) collected during 1995

This study gives an account of distributional patterns of Brachyuran larvae in the Manora Channel from January to November 1995. The planktonic sampling was carried out during day time from surface and sub-surface waters of station I and II (certain sites) at shallow depths (15'-20') using Bongo net of 300 micron mesh size. In all 19527 larvae were obtained through fourteen sampling. These brachyuran larvae belonged to nine families and twenty four species: Ebalia sagittifera, Philyra sp., Philyra scabriuscula (Leucosiidae), Schizophyris aspera (Majidae), Charybdis annulata, Charybdis sp. (Portunidae), Xanthid sp A., B. and C. (Xanthidae), Pilumnus karachiensis, Pilumnus sp. (Pilumnidae), Menippe rumphii (Oziidae), Pinnotheres sp. A, and B. (Pinnotheridae), Nasima dotilliforme, Serenella indica, Macrophthalmus (Mareotis) depressus, Macrophthalmus sp., Dotilla blanfordi, Ocypodid sp. A., B. and C. (Ocypodidae), Metopograpsus thukuhar and Clistocoeloma lanatum (Grapsidae). This study is based on identification, occurrence, distributional patterns along Manora Channel and percentage composition of brachyuran larvae in the area, collected during 1995