Sunday, 15 September 2019

MoMA comes to Melbourne Part 2

Since I really can't decide what works or art to include in my post, and what works not to, I have decided to split this post (though this is something that I seem to do quite regularly when it comes to a lot of these posts on the various exhibitions that I have been to). Anyway, in the previous post we had been following the evolution of art up to the 1920s, but now we move further on, to another style, with one artist we may all be familiar with - Salvador Dali.

Inner & Outer Worlds

What seems to be happening now is that artists began to move away from a lot of the abstract art that had developed over the 1920s, particularly the styles were the artist basically only painted colours as shapes, something that had somehow grown out of cubism, as exemplified by Picasso. Now we move into another realm, one much more surreal, with the likes of Salvador Dali, Yves Tangey, and Rene Margritte.

Thus surrealism was born, a movement that basically arose out of Paris. Here the artists had become much more meticulous, and in fact were able to create imagines, and panoramas, that were not only precise, but also seemed to stretch the boundaries of reality. In a way it seems that they had not just moved forward, and away, from the works of the impressionists, but also back to the world were precision in art was much more important.

Yet Europe was racked by disorder and turmoil, and with the treat of war rising once again, many of the artists decided to move elsewhere, and suddenly found themselves over the ocean in places like the United States, Mexico, and Cuba. Here the artists would influence, and in turn be influenced by, the styles that had developed therein. Anyway, let us start with a painting that we are probably all familiar with:


And here we are, Persistence of Memory by Salvadore Dali, a painting that he describes as his most 'imperialist fury of precision'. In a way he is trying to capture the idea of memory, something that seems to be able to take solid shapes, and objects, and to be able to morph and transform them into something completely different. Here we have once solid watches, oozing off the side, as another is attacked and destroyed by ants. We also see in the distance, yellow cliffs, a memory of Dali's homeland in Catalonia, disappearing into the vague white area of forgetfulness. Yet there is something persistent about memory, and there are thing which, no matter how hard we try, or how long time passes, just always seem to remain, something that is no doubt also represented by the clocks.



This painting is called Gare Montparnasse, or the Melancholy of Departure, which was painted by Girogio de Chirico. Gare Montparnasse is a station located in Paris, which happened to be located near where Chirico would work. This is a painting of contradictions, with the vanishing points just not quite working out the way that they are supposed to work out, which causes us to feel confused, and in a way a little uncomfortable. Another thing is that the title is about a departure, yet the train seems to be arriving, and further, the clock suggests that it is midday, yet the scenery feels that it is really another time of day. Was this all done on purpose? Quite possible, and maybe it is designed to throw us off, and make us think, especially since the painting, despite it's title, does feel a lot more upbeat and warm, and melancholy and depressing.



Well, it seems that there was nothing written on the little plaque underneath this painting, except of course for the title, Mama, Papa is Wounded, and the name of the painter, Yves Tangauy. Mind you, it isn't as if they really said anything all that amazing about the meaning behind the painting, but yeah, sometimes it came be pretty difficult to understand the meaning, even if the artist actually had a meaning. Once again, like the previous paintings, there is this shifting perspective, and also appears to be an apocalyptic landscape. The suggestion is that it evokes memories of the First World War, and of course there is this dark cloud manifesting there, as if the world itself is bleak and the horrors are still hanging around. This is all despite the fact that the world was experiencing huge economic progress, but no doubt this had a lot to do with trying to escape the horrors of the war.


Sometimes it is good just to paint things and let other people try to interpret what it is all about, but I'm still one of those people that feel that a painting (or any work of art) that the artist doesn't have some personal meaning that they are trying to express really has no value, except for maybe its aesthetic value. Anyway, this painting, by Jean Viro, is called The Portrait of Mistress Mills in 1790, which is modeled after an earlier painting of Isabella Mills. Of course, this looks nothing like the original painting (which is on display in the National Gallery of England, and you can see it here). It a way the metamorphosis is almost comical, as if the artist is making a mockery of the original painting. Then again, these paintings were an attempt not only to capture the subject's youth, and beauty, but also as a means of gaining some form of immortality.


And here is another painting by the master of turning a dirty paper napkin into a priceless work of art, Pablo Picasso (though this was hardly painted on a dirty table napkin), and is called a seated bather. Well, it doesn't look like she (and I suspect that the subject is female) is wearing any clothes, though it could be that the term bather refers to taking a bath as opposed to going for a swim. Yet the head I find really interesting - it is as if it is a microcosm of the painting as a whole. It certainly does not seem to be an actual head. In fact the entire body looks disjointed, almost as if it isn't a single person, but rather a collection of objects that have been thrown together that, if we look at it from another way, we can easily say that yes, this is a person.


This artwork is called Red Head, Blue Body by the Swiss artist Meret Oppenheimer. Yeah, it's difficult to come to an understanding of the meaning of this work of art, much like many of the works that appear in this collection. Of course, it can come down to 'what you will', though many critics resort to the use of colours. Personally, I don't care, but the thing that stands out is how the head, which is clearly supposed to be a human head, is connected to the body by a piece of string. In a way, to me at least, it suggests not just the fragility of the body, but more so the fragility of the neck, as if these to parts of us are just weakly held together.


This painting, simply called Gas, is apparently an amalgamation of many gas stations into a single image. In a way it captures not only the essence of modern America, as defined by the gas station, but also in a sense an aura of loneliness. Many gas stations seem to exist by themselves out on empty country roads, and while things may seem quiet, they also symbolise the lifeblood of modern Amercia, the fuel that keeps people moving from place to place, an important cog in the wheels of commerce.

Art as Action

So, now we move into the realm of the New York Surrealists of the 1950s. The previous years, those of the surrealists, focused on introspection, no doubt exploring the world that had emerged from the tragedies of the Great War, and in turn hurtling towards another, one that no one wished to get involved in. However, now we emerged from the ashes of this second war, with Europe and Asia rebuilding while the United States was now sitting on the top of the pile.

This was the beginning of what is now known as The American Century, and it is here that we begin to see the American artists move to the foreground, particularly out of New York, America's true cultural centre (not Los Angeles, as some have suggested, since while Los Angeles may be the cradle of Hollywood, in reality it is New York from which many of the great artists and writers of this era emerge). Here we are introduced to Jackson Pollock, and down the line we also come to meet Andy Warhol.


And here we are, Jackson Pollock's Number 7. Yeah, people are going to look at this and ask themselves 'what sort of rubbish is this?'. In fact, that is what was said when the Australian Government bought a Pollock for a huge amount because, well, it is just paint splattered on a canvas. The reality is that anybody could do something like this - it really doesn't take much skill. Sure, there is the claim that the painting represents the dance that Pollock was doing around the canvas, and others admire the style, but the truth is, Pollock, like Duchamp, is challenging the art world, and in many cases it is the name to which this artwork is attached that defines it, as opposed to the art itself. The reason nobody else can do a 'Jackson Pollock' is because there is only one Jackson Pollock out there. If I were to do the same thing, no doubt people would simply laugh, and accuse me of simply trying to copy him.

Okay, a red canvas that happens to have a bright red line painted down the middle of it. Well, if Jackson Pollock can create a painting worth millions of dollars simply by dancing over a piece of canvas while pouring paint onto it, then Barnett Newman can do exactly the same thing with a simple line. In fact, the plaque next to it talked about how it was a breakthrough style of abstract expressionism with a single line both uniting, and dividing, the canvas. Sometimes I wander who came up with these ideas, though it could simply have been Newman explaining to the art critics why they should even bother taking note of something like this. Of course, an empty room could do a lot as well.

Things as they Are

Now we arrive at the 60s and the emergence of the artistic styles known as Pop-Art, Minimalism, and Post-Modernism. Peter Salz criticised many of the artists of the time, claiming that all they were doing was reproducing things as they are, but in a way these artists were capturing the essence of the modern world, and celebrating America's coming of age. Pop-Art, in a way, was taking consumerism and turning it into an artform, while Post-Modernism was helping objects understand the meaning of their existence. As for minimalism, well, I guess a line down the middle of a canvas sort of says everything you need to know about that (not that Newman was a minimalist artist).


It is interesting, in a comic book, the above image would, well, simply be part of a story, and in fact we would probably read it and pass over it without much though. What Roy Lichtenstein did was that he took this single panel, put it in a frame, and hung it on the wall. Well, that started off a huge craze, though of course Roy Lichtenstein is the one that gets all the credit for it. Look, I don't even think I need to mention the comic (Sacred Hearts) because this image no longer forms part of the comic, and is now a piece of art in and of itself. In a way it does capture the essence of modern society, where we would rather die that admit that we need the assistance of somebody that we despise. What the true meaning of this panel was is now lost to time, because all that remains is the image.


Everybody knows what the map of the map of the United States looks like, but to Jasper Johns it was something more than that. In his words, he wanted to take something that we generally only give a furtive glance towards (unless of course you happen to be a map nerd, like myself) and turn it into something that will not only grab our attention but force us to look at it more closely. Well, taking a map of the United States, putting a frame around it, and hanging it in an art gallery is certainly going to do that, especially with all the art nerds spending countless ages trying to work out what it actually means, or just simply admiring the art for arts sake. Of course, he went further than simply getting a Rand McNally's map and framing it, because he created the map himself, much in the style of the Abstract Expressionists of the not too distant past.


In a sense much of modern architecture seems to be pretty much the same, at least when we look at them in isolation. However, when Bernd and Hiller Becher traveled about West Germany documenting various scenes of a declining industry, especially the towers that stood over coal mines, it become evident, particularly when put together, that even in an industrial world, a world where function is preferred over form, that everything seems to have a unique aspect to them. This is the case when we look at what initially appears to be a collection of photographs of 'Winding Towers' only to discover that no two are actually alike.


Honestly, it wouldn't be a MoMA exhibition without something on display by Andy Warhol, the king of Pop Art (well, I might be exaggerating things a bit there though). Mind you, I've already written a piece on him, especially since the NGV had an exhibition on his works as well. So, the above work is called, not surprisingly, Marilyn. It is a collection of screen prints, a medium that Warhol quite liked working with (and in a sense is a defining medium of the modern world). What these images capture is, well, the many faces of Monroe, particularly since this beloved actress sadly died of an overdoes at a rather young age, and not long after this work was produced


The above screen prints are in a way similar to the album covers we see above. The reason I raise that is because art, in many cases, is generally seen as being unique (to an extent, since means of mass producing works of art, such as through woodcuts, have been around for quite a while). However, with the inclusion of these album covers on the walls of the MoMA indicates an idea that art does not necessarily need to be unique, in the sense of being a unique object, such as a painting. Rather it is the image, an image that can be reproduced multiple times in multiple places. In fact, for this display, the designers of the covers are also included, though it turns out that, like a lot of commercial products, there tends to be more than one mind going into idea.


Honestly, I'm not sure which direction this is supposed to go, though I suspect that I have it upside down, if we base it on the direction it is supposed to be played. Yes, I know, this is an electric guitar, and yes, it was hanging on the wall of a museum. If you are familiar with your instruments though, you will recognise this as a Fender Stratocaster - probably the most popular electric guitar on the market. In fact, the designer, Leo Fender, who was an amateur electrician, designed it to be able to have interchangeable parts, and to also be able to be customised for the user. Then again, since my ability to play a musical instrument is basically non-existent, I guess I just have to admire the product of other people's work. However, one could almost consider this to be a work of art that is used to produce works of art.



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MoMA comes to Melbourne Part 2 by David Alfred Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. This license only applies to the text and any image that is within the public domain. Any images or videos that are the subject of copyright are not covered by this license. Use of these images are for illustrative purposes only are are not intended to assert ownership. If you wish to use this work commercially please feel free to contact me

Sunday, 1 September 2019

Controlling the Flow

Once again we seem to be going over some old ground, particularly the second half of my post on the Intricacies of data transfer. However, there are a number of things that weren't discussed, and this is what we will be looking at, namely error control and flow control.

Both of these functions occur on the data link layer, which is a layer on the OSI model that exists above the physical layer. It is here that data is packaged into frames and then sent down to the physical layer where the data is then passed on to the destination. Basically, the functions that the Data Link layer looks after are addressing, packetising, error control, flow control, and access control. Now, we have already looked at error control previously, so now it is time to look at flow control.


At its basic level, flow control is a mechanism that is used so that one computer is not overwhelmed by a heap of data being sent to it by the sending computer. The process works on the sender sending a frame and then waiting for an acknowledgement before sending the next frame. This is flow control at its basic level. Further, there is a timer on both sides, so if the timer runs out on the sender's side, that indicates that the frame was not received, or if it was received, it was received with an error, so it sends it again. A similar function occurs on the sender's side, though what is being sent is an acknowledgement as opposed to the frame.

So, at the data link layer, the sender sends a series of frames each containing the data and some control information (known as the header). When the frame is received, the receiver then processes the data before passing it on to the higher level. Normally there is a buffer where frames are stored while they are being processed, and the sending entity needs to avoid sending frames at such a rate that the receiver is unable to process them in time resulting in a buffer overflow.


Stop and Wait

This is the simplest form of flow control. Basically the sender sends a frame, the receiver receives it, processes it, and then sends an acknowledgement. However, the acknowledgement will be for the next frame in the queue. So, if the sender sends frame 0, the receiver will respond with acknowledgement 1, or rather ack 1. This tells the sender that it should now send frame 1, which is the next frame in the queue. Once that is sent, received, and processed, the receiver then sends ack 0, which, once again, requests the next frame in the queue.

If the receiver is getting overwhelmed, it can stop the flow by not sending an acknowledgement, and then only send one when it is ready to receive the next frame.

Okay, time for some more maths, namely because when determining the length of the timer, we need to know a few other things, such as how long it will take for the frame to get from the sender to the receiver. So, first we have the transmission delay, or the length of time for the frame from the first bit to the last bit to leave the sender, and we get that by using the following formula:

T=L/R, or Time = Length of Frame/Transmission rate.

So, we have a frame that is the size of 12000 bits being sent along a medium that is a 100 Mbps link. The formula will then come out as follows:

T = 12000x(1s/108 bits).

We came up with that because the formula would be 12000/100 Mbps, which is 12000/108 bps, or 12000/(108/1). When we are dividing by a fraction, we actually flip the fraction and then multiply it, as such, which produces 12000x(1s/108 bits), however since 12000 x 1s is 12000, we end up with 12000/108 bits. Once again, we switch the sign of the indicie and then multiply it:

12000/10-8

We round down:

1.2 x 10-4

And plug the problem into our trusty calculator, which produces:

0.00012 seconds.

Well, let us fix this up a bit:

0.12 milliseconds

And that is the transmission delay, or the length of time it takes for the first bit to the last bit to leave the sender.

Next we go to propagation delay, which is the length of time it takes for the first bit to travel from the sender to the receiver. We get that using the following formula:

T = d/s, or distance divided by the speed that it takes for the bit to travel through the transmission medium, with the upper limit being the speed of light (and we aren't taking into account quantum entanglement here, namely because we haven't worked out how to utilise it). Signals traveling along copper wire travel at 2x 108 m/s

So, let us look at an example, namely the propagation delay between Cairns and Melbourne (which is about 4000 km).

Here it is on a map.
4x 106 m / 2x 108 m/s

4x 106 m x (1s / 2x 108 m)

4x 106 m / 2x 108 m

2 x 10-2 s or 0.02 seconds, or 20 milliseconds.

Sounds pretty slow doesn't, in the grand scheme of things. No wonder we need a proper working NBN.

The reason that we went through all of that math is basically to help us understand how long the timer should be set, because if it is set too short, then the whole flow control system will fail.

Sliding Window

The sliding window protocol is a way of speeding up this process. The stop and wait protocol can be pretty slow, because the frame has to be sent, and then the sender needs to wait for the acknowledgement, or the timer to expire, before sending the next frame. So, we solve this through the use of buffering. Basically the frames are stored in a buffer, and are held in the buffer until the acknowledgement is received, and when the acknowledgement is received, the sent frames are discarded and new frames are then loaded into the buffer. So, the receiver will have a buffer size of W, and the sender can send up to W frames without having to wait for an acknowledgement, as below:


Like the stop and wait protocol, the acknowledgement contains the number of the next frame expected. This works well for error control also, since if one of the frames received is in error, then that, and the subsequent frames, are discarded and an acknowledgement is sent for the frame that was in error. There is also the RNR, or receive not ready, which means that the frames have been received, but it is not ready to receive any further frames. So at the sending end, the sequence number of those sent is maintained, and as the acknowledgements are received, the window grows. A similar function occurs at the receiving end.

In the case of duplex system, there needs to be two sliding windows at either end. In this situation we can utilise a method called piggy backing, which means that each frame that is sent carries a frame, and an acknowledgement, as such:

When Errors Occur

Well, as mentioned, both sides need to buffer data just in case an error is received. If an error is received, the sender continues to send the data until an acknowledgement is received that the frame was received correctly. The sender needs to buffer data to resend any frames that were either lost or damaged, while the receiver needs to buffer data just in case frames are received out of order.

Also, acknowledgements may not be received, which means that after the time out, the sender will resend the frame. When the receiver receives the frame that it has already received, it just discards it and resends the acknowledgement. This diagram might be useful:

Then there is also the Go Back N ARQ, in which the size of the frame is always 1. However, the sender does have a buffer, just in case an acknowledgement is not received.


We also have the idea of the negative acknowledgement. So, if a damaged frame is received, then the receiver will send a negative acknowledgement requesting that the frame be resent. If there is no buffer at the receiving end, frames will continue to be discarded until the correct frame is received. However, if there is a buffer, then subsequent frames will be received, and when the damaged frame is resent, it can be reordered into where it was supposed to go. The greater the size of the buffer at the receiver's end, the less repeat transmissions that there are, though this makes it somewhat more complex to implement.


So, that is flow control, and error control. Next time we will look at multiplexing, or how we send multiple signals along the same channel.

Creative Commons License

Controlling the Flow by David Alfred Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. This license only applies to the text and any image that is within the public domain. Any images or videos that are the subject of copyright are not covered by this license. Use of these images are for illustrative purposes only are are not intended to assert ownership. If you wish to use this work commercially please feel free to contact me

Sunday, 25 August 2019

Intrusion Detection

Okay, we have already looked at Authentication and access control, namely where you are proving to each other who you say you are, however here we will look at authorisation, and intrusion detection - namely once you have access what can you do, and how to detect whether somebody, or something, who shouldn't have access is attempting to gain access.

So, one of the best ways to deal with authorisation is to have a spreadsheet, namely a list of names, and a list of applications, and in the boxes that intersect, whether they can read, write, or execute the file. However, this spreadsheet can become particularly large when we are dealing with something the size of, say, McDonalds, or maybe even a bank like JP Morgan.


Actually, this matrix could form a part of a database, but the thing is that before we allow somebody to access something we need to check the matrix. Say Bob accesses the system, and wants to change the accounting data. Well, we go to the column for the data, and the row for Bob, and notice that he only has read authority. As such, we basically disable any function that will enable him to write, or change, the data.

Well, we could use what are termed access control lists:

You also have the functions working in the opposite direction, with regards to capabilities. This helps when the users manage their own data, and the protection is data orientated. Further, it is easy to change the rights to a resource. With capabilities, it is easier to delegate, and easier to add and remove users, but can be pretty complicated to implement.

Inference Control

Let us consider the following question: what was the average salary of a female minister on the Abbott Government's front bench? Well, the answer is, say, $150,000.

How many women sat on the Abbott Government's front bench? Well, there is a pretty easy answer to that one, namely Julie Bishop, and that is it.

Well, that is probably a bad example because I believe that all government ministers get paid the same amount, however you can see what is happening here. We are asking for an average, but the answer that we are getting isn't an average because, well, there is only one candidate that fulls the criteria. This could be the same when it comes to asking for the average household income of a town in which there is only one household - it gives away information, in a round-a-bout way, that should actually be private (not that the salary of government ministers are private).

So, how do we solve this quandary, particularly when it comes to research? Well, one method involves not releasing information if K% or more is contributed to by less than N respondents. This is referred to as the K dominance rule. The problem is that robust control might not be sufficient, or even work, so we reach the position where weak inference control and channel protect is probably better than none, namely because it at least prevents some leaking.

However, is weak cryptography better than no cryptography? Probably not, because if you are hiding something, and it is easy to crack the code, then honestly, you might as well place it up on a billboard for everybody to see, because that is probably where it is going to end up anyway. In fact, sometimes having no encryption is better because if something is not encrypted, then nobody will consider it important - such as an open front door probably signals to a potential burgler that somebody is home, so they will go somewhere else.

I call this hiding in plain sight.

Let us look at a typical security network:


When it comes to firewalls there is no actual strict terminology. However what it does is that it provides access control to the network, and decides what to let in, and what can go out. Three common types are the packet filter, which works at the network layer, the stateful packet filter which works at the transport layer, and the application proxy, which works at the application layer (take a look at the OSI model for references to them).

The packet filter can filter out packets based on a number of factors, including the source and destination IP address, the source and destination port, as well as flag bits, and also ingress and egress (that is whether it is going in, or out). Like the access control, the functions of the packet filter can also work on a matrix, as outlined below, which is designed to limit traffic to web browsing:


There is also this concept of the DMZ, which is a military term known as the demilitarized zone. In military parlance this is an area where no military activity is supposed to occur - the most famous one being the border of North and South Korea. One of the most common uses of a DMZ is for public wifi. Starbucks, for instance, has free wifi for people who order coffee there. Basically what it does is that it partitions off a part of the network to allow a larger access than what the network would normally allow. In fact, when you try to connect to the Starbuck's wifi, you will probably note that they have two channels, one for the public, and another, more secure one, for the staff.

Preventing Intrusion

This is the more traditional form of computer security. Passwords, access control, and firewalls are all a form of intrusion prevention, as well as virus scanners. Viruses are an interesting thing because many of them are designed to circumvent such protocols, such as giving an attacker direct access to one's system. For instance, they might actually open a port that the intruder can use to completely bypass any form of password protection.

However, despite all of our attempts to keep intruders out, sometimes they do get in, so we also need systems that will detect specific activity, or attacks in process. While the traditional hacker is usually gaining access from the outside, sometimes you might have somebody inside the company accessing something that they aren't supposed to access. For instance, in one of my former jobs, if you accessed a file that you were not supposed to access, our compliance department would actually be notified.

Accessing confidential information may not be the only thing because they might also launch attacks, whether they be well known, little known, or even new. Actually, it is probably the amateurs that launch well known attacks, because this whole concept of computer security is like an arms race - every time we find a way to kill a virus, new virus are being developed to counteract that. Actually, it is sort of like biological viruses, that develop immunities to well known drugs.

Signature Detection

Intrustion detection comes down to signatures, which are generally attacks, and anomolies, which is suspicious behaviour. They can also be monitored on a host, or on a network as a whole. For instance, failed log in attempts may be a signature of an attempt to crack a password. As such, an algorithm of so many failed attempts in a certain amount of time will trigger an alert that there is an attack. My bank has something along the lines of five failed attempts, and after the fifth attempt the account is locked. My phone has a similar detection system, except instead on locking me out of my phone, it will institute a delay between attempts, that gradually gets larger and larger the more failed attempts that occur.

Obviously we want to avoid false alarms, such as me forgetting my password, so they generally incorporate a certain number of tries before implementing the intrusion prevention mechanism. Mind you, an attacker might know about this, and if the mechanism is triggered after five attempts, then an attacker might only do four, and then wait. While it isn't perfect, it will actually slow the attacker down, and make brute force attacks even more useless.

The advantages of this approach is that it is simple, it can detect known attacks, it can know which type of attack is occurring at the time of the attack, and it is efficient, though only if there is a reasonable number of signatures. The catch is that it only works on known attacks, the signature files need to be kept up to date, and the number of signatures can become inordinately large.

Anomoly Based

So, say we have Moss, who regularly uses the work system. Now, we have a pattern for how he accesses and uses files - he opens, reads, closes, opens, opens, reads, close. Now, we have a number of pairings that we can work with, such as (open, read), (read, close), (close, open). So, what we can do is we can monitors these three commands, and since we know the common pairs, we can keep an eye on abnormalities. For instance, if there is a spate of (open,open), which rarely happens, then this will trigger an anomaly warning, meaning that maybe there is an intruder using Moss' account.
This is actually a pretty basic one, and we could increase the chance of picking up an anomaly by including more commands, increase the number of commands to beyond two, and even consider the frequency of each of the pairs. Another way of detecting anomalies is the frequency, and length of time, that a file is accessed. Consider below:

On the left we have the average recording of the files being accessed, and on the right we have the current recording of the access over, say, the day. So, is there an anomaly? Well, time for some more maths.

S = (H0 - A0)2 + (H1 - A1)2 + (H2 - A2)2 + (H3 - A3)2

S =(0.1 - 0.1)2 + (0.4 - 0.4)2 + (0.4 - 0.3)2 + (0.1 - 0.2)2
S= (0)2 + (0)2 + (0.1)2 + (-0.1)2
S = 0.01 + 0.01 = 0.02.

We basically consider that an anomaly that is less than 0.1 to be normal, and since we have come out with 0.02 then we consider this to be a normal variation.

Since there are going to be variations, and changes in the usage, we do need to regularly update them, and we do so with this formula: Hi = 0.2*Ai + 0.8*Hi

In this case, it will be 0.2*0.3 + 0.8*0.4 = 0.06 + 0.32 = 0.38, which then becomes the new H2. We also do the same for H3 to generate the new H3.

So, with this method the averages regularly update to reflect changes in behaviour, and to also reduce the number of false alarms.

As for attacks, well, we will have one where the intruder attacks all of the hosts in an attempt to locate the weakest link, and then access the network through the weakest link:


And finally, we have the attack where a victim is attacked from many sectors at once.


And so, this was computer security. I no doubt will be coming back to this topic again in the future, but I shall be leaving it here now. Sure, this may have seemed like a hodge podge of stuff, but that is basically our lecture notes.


Creative Commons License

Intrusion Detection by David Alfred Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. This license only applies to the text and any image that is within the public domain. Any images or videos that are the subject of copyright are not covered by this license. Use of these images are for illustrative purposes only are are not intended to assert ownership. If you wish to use this work commercially please feel free to contact me

Saturday, 17 August 2019

The MoMA comes to Melbourne




New York is probably one of the very few places that I really really want to go to in the United States (and I'd say that Vegas is the other, but come to think of it, Vegas would probably be one of those places that I'd drive down the strip once, have a beer at the casino, and then head off to go and see the Hoover Dam). However, due to complications having a slice of New York, in the form the the Museum of Modern Art (otherwise known as the MoMA) coming to Melbourne does temper that urge somewhat, even if it is the case that most of the works here are basically what one would consider Modern Art.

Yet, when it comes to art, it really feels as if New York is pretty much the centre of the American scene. Sure, Hollywood is where all of the movies are made, and some have even suggested that Los Angeles is probably America's cultural capital, but considering that the likes of the Broadway Musical, Andy Warhol, and many others, have come out of New York, I am almost inclined to feel that this city is not only America's cultural heart, but gives the nation more of a character beyond hamburgers, Chevy's and stock market crashes.

Arcadia and Metroplis

And so, our first encounter when we walked in through the entrance was a gallery in which we find, not American artists, but French, namely those of Gaugin, Van Gogh, and Seurat. What we encounter are the post-impressionists, as we start our trek at the beginning of the 20th Century. The world has changed, yet there is a struggle with the artists, between in idyllic landscapes of the past, and the massive metropolises of the future. At this time, though, the British Empire still rules the world as the sole superpower, yet little does anybody know, that by the end of the century, that position will move to the other side of the Atlantic.

Mind you, and this is something that I have mentioned previously, and that there was one particular technological invention that changed everything: the camera. In fact, the camera was one of those majorly disruptive developments of the time, literally putting portrait painters out of business. Mind you, the cameras of the time were pretty shocking, but what they did was that they forced artists to experiment and to look for different means challenging their audience. Notice, though, how with the impressionists, the focus was very much on colour, which ironically was something that the camera couldn't produce at the time.

This painting, called Evening at Honfluer, is by the artist Georges Seurat. He was the guy that invented the style known as pointilism, which is basically creating an image by using thousands upon thousands of little dots. It is quite interesting to look at, and is actually supposed to capture a scientific idea at the time, which believed that images were generated by thousands upon thousands of beams of life penetrating the eye. The other reason behind this painting is that Seurat had been cooped up in his apartment for quite a while, and was really looking for an opportunity to get outside.


It turns out that Van Gogh painted more than just one painting of the postie while he was in Arles unsuccessfully attempting to establish an artists' commune (of which only one artist, Paul Gaugin, even bothered to come and check out). Actually, the name of the postie is Joseph Roulin, and this particular painting was once owned by Norman Rockefeller, among many, many others, but was gifted to the MoMA in 1989. However, I have already written quite a few things on Van Gogh, so I guess I'll leave it at that and move on to somebody else.


These two posters are probably best done together, and not just because they were produced by the same artist (Jules Cheret, though that is probably quite obvious). These posters were produced using lithographic techniques, which basically means stone prints, as opposed to woodcuts, where the stamps are made of wood. The style was a new technique, particularly for posters, which has certainly been borrowed from the Impressionist movement, and here we are seeing them being used in the form of advertisements. The first, Fuller, is of the American cabaret dancer Loie Fuller, and the second being an advertisement for the Theatrophone, a form of telephone that would pipe music down to the listener - an early form of radio.

In a way, this is a theme that we begin to see through this exhibition, and that is that art does not necessarily exist on the walls of galleries and homes, but it exists everywhere, in the streets, on the bill posters, and even as the designs of your lounge suite, or the album cover. However, we are getting ahead of ourselves here, and instead we will slowly move ahead.


We now move from the Impressionists to the Expressionists, this one being painted by Ernst Ludwig Kirchner, who formed the collective known as Die Brücke (or the bridge). This painting is of the fashionable Königstrasse in Dresden. Notice the difference between the paintings of the impressionists and the expressionists - the painting is much harder, the colours much more solid, and also with a darker tone. This in a way emphasises the violence of the city scenes, as people push past each other for reasons only known to them. Yet also consider the faces, which are more like masks, also suggesting that this world is a nameless, faceless, and characterless work.


We can certainly see that the art of the modern era is starting to take on different tones. In this painting by Andre Derain, called Bathers, there has been some borrowing from non-European cultures, particularly with the mask like facial features. In one sense this painting is rather abstract, but not so abstract that we start to loose all features of the subjects, three women bathing in a river. Yet, the surroundings aren't distinct, instead focusing on the style, and the nature of the event.


This is another painting by Dauvin, this one called fishing boats. The style is known as Fauvism, which is nowhere near as well known as styles such as impressionism, or even cubism (thanks no doubt to Picasso). Notice how this painting seems to emphasise the bright colours, something that fishing boats in parts of Europe are well known for. Yet even with the colours, the shapes don't stand out as much - in fact they are quite vague and indistinct. This is a characteristic of such works at the time, which focus ever more on the colour, as the artists begin to move away from the realistic nature of the subjects of their works.

Machinery & the Modern World

The twentieth century could been seen as the century of the machine. Sure, machines have been with us for centuries, even if they were as simply as something like a wheel. However, in the twentieth century machines had not only taken a life of their own, but as begun the process of displacing us. The camera had displaced the painter, and film had displaced the theatre - it was a time where one had to adapt, or perish.

Thus, artists began to take up the challenge of competing with the machine, with artists such as Picasso, whose cubist paintings would take the three dimensional and compress it into the two. We also have artists who would take elements of the machine and create art around it, or even go as far as the legendary Marcel Duchamp, who would dare, and succeed, at taking an ordinary object and make the claim that this object was art. Of course. We even have architecture, even architecture of the modern home, which had transformed itself from a dirty hovel to a machine for living.


Guess what, this is Picasso, but if you are familiar with his work then you probably already know this. Yeah, this certainly doesn't look like what you would expect from him, but the thing is Picasso was an incredibly prolific artist, and while his most famous paintings are his cubist paintings, he did an awful lot more. In fact, even his doodles could garner quite a lot of money. Sticking with the theme though, this painting, which is cubist, exemplifies the disconnect that the new technological world was bringing about. The problem is that to be able to properly appreciate the painting, you need to look at it from the angle of the wall, because looking at it on a computer screen, well, it just looks like a muddy table.


This painting, by George Grosz, is called explosion, and it certainly looks like an explosion, and also goes to demonstrate the way art has changed at this time to capture raw emotion as opposed to just, well, capturing an image of a pretty landscape, or a person. Grosz fought for the Germans in World War I, but was discharged as being unfit to fight (which sort of says something because it wasn't easy to get out of the army back then). This painting brings about the destruction that was caused by the war, both physically and psychologically. In many ways the perspective of the painting changes based on how you look at it, but in all aspects it is about destruction, and a new type of destruction brought about by modern warfare.


This is an example of a style of painting known as futurism, and is painted by Giacomo Bella, and is called Paths of Movement. In this painting Bella is attempting to capture motion, and in particular the motion created by a bird known as a swift. Here it is hard to actually see the bird, as it flies across the canvas before our eyes. However, this painting was also inspired by photography of the movement of birds, which considering the time at which it was painted, was still in its infancy. Once again, we are seeing art move away from its traditional form, and in this instance, delving into the scientific world.



This piece, called Sun and Moon, is by the abstract artist Robert Delaney. In fact Delaney was an early adopter of the concept of abstract art, and the above is an example of this. The circle represents the universe, and the merging of the various colours represents the interplay not only between the sun and the moon, but also between the night and the day. Then again, the only reason I know this is because I read the plaque that happened to be placed under the painting. Basically, if it wasn't for that plaque I probably would have no idea what this actually meant, but then again that is probably because I'm a heathen

Okay, this may not be anywhere near as famous, or as gutsy, as Fountain, but this is another example of Duchamp's readymade, that is work of art that has been created out of prefabricated materials. Actually, this is slightly more because it is what he termed as an 'assisted readymade' namely because it is made out of a bicycle wheel and a kitchen stool. Basically it is a useless machine, which not only is it challenging the concept of art, something that he basically loved to do, but it is also challenging the concept of innovation, considering a lot of innovation is, well, useless. Then again, the thing with invention is that you do have to go through a lot of useless ideas before you stumble upon something that is truly transformative.



This painting, by Ferdinand Leger, is called Propellers. In a way it is basically Picasso meets the machine world were Leger takes Picasso's cubist techniques and applies it to a world of machines. Looking at this painting we can sort of make out the propellers, and the blades, and other items such as tubing and pistons. Leger appears to be trying to capture the dynamics of this new work, but he also senses a strange, outerworld beauty to it. Mind you, most people would probably just look at it, and not even read the little plaque down the side, but it is there that one can get the most information about a painting such as this one.

A New Unity

By now art is starting to become particularly strange with the development of, well, lots of different styles. Yet in these different styles one sort of sees a unity, and that unity in a way is a break with the past. Gone are pretty decorations to be replaced by geometric form and function that arose from the avant-garde movement. He we also meet constructivism for the first time, something that arose from the ruins of the Russian Revolution. It is here that we can certainly see a break with the past as the old world of Tsarist Russia has been left behind to be replaced with the dictatorship of the proletariat. In a way what we have is a nation that is now trying to find a new identity.

In a way this seems to the be the case across Western Europe as many people seek to try to understand a world that had gone, and a new one made in the trenches of the Great War. Gone was this ideal that humanity was on the cusp of something new, and instead we have a world seeking purpose and meaning. This, of course, were to come to a head ten years later with the onset of the Great Depression, however we are still in a world where people are attempting to drink the memories of the Great War away as we head into the roaring twenties, a time still dominated by outdated ideas of class and sex.


Well, now we are starting to get strange. This is by the Russian artist Lyubov Popova and is called Purely Architectonic. Well, I probably shouldn't call it strange since it is attempting to channel to works of the cubist, but what is it a painting of? Well, I guess that is the question, isn't it? Honestly, it simply looks like a collection of shapes, and really lacks any formal meaning as it is. Still, Popova did suggest that painting is like, well, engineering, and some engineers have described engineering as being an artform. Here, we are merging the two to a point where the artist isn't creating something, but rather building something out of basic blocks.


Here is another couple of works by another Russian artist, this one Kazimir Malevich, and the work is called Supremist Elements. Actually, they are titled square and circle as well, but the collection is Supremist Elements. So, what do we make of them because all they seem to be are a couple of shapes drawn on paper with a pencil, placed in a frame, at which point they ended up an in art gallery. Apparently he consider this form of art to be supreme, at least compared to the natural world. Well, in my mind it is just a couple of pencil sketches, and there is nothing all that supreme about it. Yet, it is what you could consider constructivist, that is that the artist has constructed it with their mind, as opposed to letting nature dictate the result. Still, I have my own opinion regarding the piece, but it does show us how humanity is ever attempting to claim supremacy over the natural world.


This is a movie poster by Validmir and Georgii Stenberg and is advertising a 1926 movie called The Three Million Case. Mind you, I use the word advertising in as loose a way as possible considering that, as you can tell, this is in Russian, and in 1926 Russia was actually called The Soviet Union. Well, no doubt this is a Russian film, and no doubt the rich people are the bad guys. However, the main reason that I have posted it here is because I thought it looked cool. However, as we continue on our trek through the MoMA you will discover that a lot of the art actually involves movie posters and album covers.


Thus here we have another example, this one from a 1921 film called Pounded Cutlet. Actually, the original title is 'At the Ringside'. If this one looks strikingly similar to the one above, that is because it is also by the Stenberg brothers. You can probably figure out that I do actually appreciate their work, with the rather modernist styles. Honestly, it is a shame that they don't make posters like this anymore.



These nine drawings are by the Russian constructivist Alexandra Exter, and are from her portfolio of works called Stage Sets (or Decors de Theatre). These weren't commissioned works, but rather works that she designed that could be used for operatic, ballet, or other theatrical performances. These designs, along with numerous others, were included in her portfolio. I'm not entirely sure whether they ended up being built, however they have certainly landed up on the walls of the MoMA.


This final piece that we will look at for the time being is called Colour Structure by Joaquin Torres Garcia. He came to Paris and not really satisfied with the direction of the surrealists decided to establish his own group known as Cercle et Carre (otherwise translated to Circle and Square). As you can probably deduce from the name, this group was more interested in geometric abstraction. An example is above, where the entire painting has been divided into rectangular shapes of various sizes, each of them having a vibrant colour. While it was was suggested that they were 'primary' colours, one can tell that this is not actually the case. Mind you, it does sort of feel as if the curator really had no idea if the painting carried any meaning, and just talked about its composition (which, in some cases, is all that really can be said).


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The MoMA comes to Melbourne by David Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. This license only applies to the text and any image that is within the public domain. Any images or videos that are the subject of copyright are not covered by this license. Use of these images are for illustrative purposes only are are not intended to assert ownership. If you wish to use this work commercially please feel free to contact me