Thursday, March 26, 2009

Bagalamukhi Yentra

‘या देवी सर्वभुतेषू विद्यारूपेण संस्थिता नमस्तस्यै नमस्तस्यै नमस्तस्यै नमो नम:।’

Bagalamukhi Yentra

Bagalamukhi means "The Crane-Headed One". This bird is thought of as the essence of deceit. She rules magic for the suppression of an enemy's gossip. These enemies also have an inner meaning, and the peg she puts through the tongue may be construed as a peg or paralysis of our own prattling talk. She rules deceit which is at the heart of most speech. She can in this sense be considered as a terrible or Bhairavi form of Matrika Devi, the mother of all speech. According to Todala Tantra, her male consort is Maharudra.

Seated on the right of Bagala is the Maharudra, with one face, who dissolves the universe.

The Bagalamukhi Mantra as per Mantra Mahodadhi:

"Om Hleem Sarva Dusthaanaam Vaacham Mukham Paadam stambhaya jihvyamkilaya buddhim vinaashaya Hleem Om Swaha"

Monday, March 16, 2009

योजकस्तत्र दुर्लभ :

अमन्त्रम् अक्षरम् नास्ति, नास्ति मूलमनौषधम् ।
अयोग्यम् पुरुषो नास्ति योजकस्तत्र दुर्लभ :।।

(मन्त्र नभएको अक्षर छैन, औषधि नहुने वनस्पति छैन, योग्यता नभएको मानिस हुँदैन, अभाव त तिनलाई सही उपयोग गर्न सक्ने व्यक्तिको मात्र हो ।)

Why TCP without Selective Acknowledgments can only recover from a single packet loss per round trip time?

Even though multiple packets lost in the same transmission window, the sender considers the fist packet that was lost from the duplicate acknowledgement it received. After retransmission of the lost packet, the sender has to wait for the acknowledgements from the receiver for the next lost packet. So, if Selective Acknowledgements is not implemented TCP can only recover from a single loss per RTT. The Selective Acknowledgment option for TCP allows each acknowledgment to specify up to three contiguous blocks of data that have been received beyond the last packet in sequence. The sender can thus infer which packets have been lost and retransmit them without waiting for additional duplicate acknowledgments.

Thursday, March 12, 2009

Shri Baglamukhi

Baglamukhi is the eighth Mahavidya in the famous series of the 10 Mahavidyas. She is identified with the second night of courage and is the power or Shakti of cruelty. She is described as the Devi with three eyes, wearing yellow clothes and gems, moon as her diadem, wearing champaka blossoms, with one hand holding the tongue of an enemy and with the left hand spiking him, thus should you meditate on the paralyser of the three worlds.

On the right of Bagala is the Maharudra, with one face, who dissolves the universe.
Jai Ma Ta Di

Tuesday, March 10, 2009

With some Split TCP schemes, a data packet can be acknowledged without first reaching its destination. Why is this a problem?

It is a problem with some split TCP scheme because it is a kind of violation of end-to-end TCP semantics. In fact, an acknowledgment originating from the wireless gateway may reach the sender before the corresponding data packet reaches its destination. In case, if the gateway crashes after the acknowledgment has been returned to the sender but before the data packet has reached the receiver, the sender will incorrectly assume that the packet has reached its destination safely. 
There is another issue with some split schemes is that wireless gateways face significant overhead as packets must undergo TCP processing twice.

Sunday, March 8, 2009

Kathmandu is 5th worst livable city in the world

Although this data is a bit old (as of 2006), the Economis says with high crime, more threat from instability or terrorism and a poorly developed transport and communications infrastructure, Kathmandu is the 5th worst liveable destinations in the world. The 5 top worst liveable cities surveyed by the Economist Intelligence Unit are Aligiers, Dhaka, Lagos, Karachi and Kathmandu. 

Saturday, March 7, 2009

Why A Unique rather than An Unique?

Why "a unique" NOT "an unique..."? When a "u" word is pronounced as though it begins with a "y" (yoo-ni-que), it's treated as a consonant sound of the y. e.g., a university, a usual day.

Thursday, March 5, 2009

Blagamukhi close view

This Bagalamukhi Mata's temple is in Patan, Nepal. There are a lot of devotees in Thursday. There are many other temples near the Bagalamukhi temple. e.g. Kumbheshwor, Dakshnkali, Kali etc. Since 5-7 years, there are many long lines of devotees. The main reason of this is devotees do puja themselves in Bagalamukhi mandir. 

May mata Bagalamukhi fulfill your dreams. 
Jai Ma Ta Di

Tuesday, March 3, 2009

Which are the main factors leading to TCP throughput degradations over wireless links?

One of the main reasons of throughput degradation over wireless links is transmission errors. Only few packets are corrected by frame error correction codes but more packet errors are assumed as a corrupted packet and discarded. These packets are considered as a lost packet by TCP and congestion window size is reduced as TCP takes packet loss as a sign of network congestion, in reality it may not be due to the congestion. This unnecessary reduction of congestion window may lead to the throughput degradation. 

Another reason of throughput degradation over wireless links is the Frame Error Rate (FER). It suffers from FER of 1.55% when transmitting 1400 byte frames over an 85 foot distance, with clustered losses. Reducing the frame size by 300 bytes halves the measured FER, but causes framing overhead to consume a larger fraction of the bandwidth. In shared medium WLANs, forward TCP traffic (data) contends with reverse traffic (acknowledgments). In the WaveLAN this can lead to undetected collisions that significantly increase the FER visible to higher layers. File transfer tests over a WaveLAN with a nominal bandwidth of 1.6 Mbps achieved a throughput of only 1.25 Mbps. This 22% throughput reduction due to a FER of only 1.55% is caused by the frequent invocations of congestion control mechanisms which repeatedly reduce TCP’s transmission rate. If errors were uniformly distributed rather than clustered, throughput would increase to 1.51 Mbps. This is consistent with other experiments showing that TCP performs worse with clustered losses.