BTW, as shown on the blog top page, the submission date of this page is intentionally set 9999-12-01 00:00:00. However, the actual submission date is 2009-01-18 13:48:24 12:05.
To keep the page light, I exclude photos in individual pages from the archive page. Instead, I inserted some of them here.
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By adding third harmonic waves to base sine waves, a more squared screws can be formed. The former screw must be better in strength.
Both types of screw can be nested. In the photos below, the threads are shallower for smaller screws. That is, a smaller cylinder has a smaller thread. (The shape are similar.) However, the depth of thread can of course be made constant.
If two threaded cylinders of the same radius are connected by using a smaller threaded cylinder, they can be pretty tightly connected. The photo below shows sine-wave screws, but square-wave screws can be used in the same way.
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This topic was publishd in a book, but it was not sold well because it was very expensive book.
Self-organized 3D-printing Patterns Simulated by Cellular Automata
Although I wanted to develop applications, I did not spent much time on this issue. The researchers in MIT made something like cloth and clothes. They also developed lace-like patterns by this technique.
]]>I happened to synthesize crossing wave by vibrato (i.e., vertical waves of filaments) and very small and high-frequency waves, very complex patterns were generated. Several examples are shown by Repeater graphics.
These patterns are generated by two vibrato waves and a fine vertical deformation wave. Because the vibrato waves are difficult to see, the following figures shows eight-times larger patterns.
The lower left figure shows only the vertical deformation wave. Although there is only a vertical wave, there seems to be horizontal waves. 波数がとてもおおいので螺旋が 1 回上昇するあいだに 20 波経由するからだ. In the lower right figure, the amplitude of this wave is eight-times larger.
Finally, printed examples are shown by photos. The above graphics show only the surface shapes, but these photos show brilliance caused by transmission, reflection, and refraction of light.
P.S. (2018-4-4): If you look the above figure that draws only crossing waves, you can see moiré patterns. They are similar to the patterns with vertical waves. It probably means that the complex patterns shown above are essentially moiré patterns. Usually moiré patterns are less complex; however, sine-waved filaments generates very complex patterns.
]]>In the case photos, although the following four certainly show troubles because the goals were not achieved, they can be regarded as interesting cases because unexpectedly curious structures were created.
In the case 9 (see the lower left photo), mesh-like structures are created instead of generating supports. These structures are similar to those described in the following papers that I wrote. (I wrote several other papers on this issue too and wrote some blog articles (in Japanese) as “3D fluctuated printing”.)
The case 25 (see upper right photo) shows unexpected skewed lines. These lines are probably generated by the same cause as the case 9.
You can see similar structures in the case 27 (see left below photo). The case 30 (see lower right photo) is considered to show the same type of structures in the air.
These structures are not designed by human. However, they are too curious to be ignored and to be thrown away. I believe structures such as the above ones, which can be regarded as naturally created structures, are valuable to be used in 3D-printing.
]]>I have bought no more Printrbot since then, of course, but I have seen Printrbot products have been changed again and again. The material of gear was changed to be wood from ABS. I do not think wood blocks cut by a lazar cutter are suited for gears. Recently, they sell all-metal products. I do not think that Printrbot products change again and again because it is good for users. They seems to follow their own interest and sells immature products every time. The users who must follow them must be annoyed. What is the reason why such a selfish maker is popular, I do not understand it.
Another printer I bought is Rostock MAX by SeeMeCNC. This product has been gradually improved, but the basic design is not changed. The design of print head of Rostock MAX was not necessarily good, and it caused troubles many times, and they caused my labor. However, it was designed much more reasonably than Printrbot, and the assembly process did not cause many problems. The current product must be more improved. I support the way of SeeMeCNC.
]]>A major problem of IP/Ethernet, which is a widely-used protocol stack, is that, because the addresses are doubled (i.e., both MAC and IP addresses are included in packets), the packet sizes increase and a troublesome protocol called ARP that manages the correspondence of these addresses is required. The reason why they are doubled is that MAC addresses are used in LAN and IP addresses are used in WAN for deciding packet destinations. If destinations are decided by using IP addresses, only IP addresses can be used for both WAN and LAN.
To realize this address unification, a LAN switching function using IP addresses is implemented for this demonstration. This means, although MAC addresses are normally used for switching but they are unnecessary if IP addresses are used for switching. Switches that learns IP addresses were implemented by software on a virtual network generated in the experimentation environment of the project, and communication using a network with switches and VMs for terminals (simulated PCs) is experimented. Processes of the experiments of two communication modes, i.e., flooding and switching, were demonstrated by edited videos.
IPON utilizes the TTL field of IP to enable communication in redundant networks (networks with loops). (This avoids communication failure in a similar way to IP. IPON is functionally the same as previously proposed protocol called IPEC.) In addition, one of the three (triangularly connected) switches used in this demo was implemented using the plug-in architecture. In this time a software plug-in was used for the demo, but IPON can be implemented using a network processor or other hardware by using this plug-in architecture.
Visitors asked various questions, but the responses of the demo were mostly in favor. Recently protocols that replaces conventional protocols such as IP or Ethernet (clean-slate protocols) drew less attentions, but many people related to GENI still seem to be interested. Before the demo, I had thought that there were visitors who showed negative reaction on throwing MAC addresses away; however, I found they are mostly in favor.
Promiscuous mode of Ethernet is used for address unification, and several special techniques were required for implementing VNode and IPON. Several visitors asked about these issues.
It is very difficult to abandon IP/Ethernet in real networks; however, I believe it is necessary to point out the problem of this protocol stack, which was only historically defined (with no inevitability), and to make efforts for simplifying it.
Warning: The content of this blog article depends on the author's personal opinion, which is not from the company and collaborators.
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This video shows the facial expressions of the violinist very well. She shows both her emotion and technical issues. She seems to synchronize her performance with the orchestra by looking at the conductor (and probably by communicating with him). It is difficult to see such expressions in concerts.
]]>In this first photo, the grids are sparse. The filament seems to be stacked sometimes randomly and sometimes regularly. The yellow circles in the figure below show "randomly" stacked filament, and the green circles show "regularly" stacked filament. However, the only difference may be the amount of filament.
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This photo shows a sparse pattern. This pattern was generated by printing from right to left. ABS is used for filament. (PLA generates less interesting patterns.) The layer pitch is 0.25 mm. Grids flow from left to right, but some of them extinct and some split and merge.
This second photo shows a dense pattern. A more regular pattern is generated, but still it is non-uniform. In the more regular part (or dense grid), i.e., the center, vertical bars can be seen. They are generated because the print-head motion is not uniform.
Interesting structures in this photo are upside-down U shapes at left (see circles in the photo below). Similar shapes are repeated vertically. Smaller but similar shapes are seen at right too (see light yellow circles). Green ellipses show another vertically repeating patterns.
An upside-down U (or boot-like shape) can also be seen in the sparse pattern (see below).
The third pattern above is a medium density one. In this photo, regular patterns are fragmented. Vertically repeating upside-down U's can be seen again.
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However, an Ethernet frame contains such addresses. This enables communication between non neighbors using Ethernet. This function is similar to communication using IP.
About thirty years ago, there are big differences between IP and Etherent. When Ethernet was first designed, "repeaters" (or hubs), which simply amplituded signals, were used when communicating two distant hosts that cannot be connected by a single wire. But, now, an intelligent switch is used for such a purpose.
In addition, at that time, Ethernet could only connect hosts in short distance, usually within a building, so there was big difference from the Internet that connected world-wide hosts. However, now we can connect all-Japan hosts by Ethernet, although the number of nodes is limited, and it is not surprising even if world-wide hosts are connected by Ethernet.
Therefore, a false statement that Ethernet is a (pure) data-link layer protocol should be backed off. Furthermore, we should consider eliminating complexities, such as ARP / RARP mechanism, caused by doubled network-layer protocols, Ethernet and IP.
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