>I know this is where some people are going to go all “It’S NoT a $1,000 DoLlAr bOaT bEcAuSe YoU pAiD $5,000 fOr It!” on me. Well, the electric boat cost $1,080, which is what I paid to the factory. All the rest went to the container ship, the customs broker, taxes, US trucking, and other associated costs.
Abstract:
Lossy links are one of the fundamental characteristics of wireless sensor networks (WSNs). A large amount of work has been performed on characterizing link properties of 802.15.4 radios, in particular in the 2.4 GHz band. Unfortunately, the 2.4 GHz band has the apparent disadvantage of a crowded spectrum and considerable external interference, e. g., from WiFi, Bluetooth or even microwave ovens. We therefore investigate the performance of radios operating on the alternative 868 MHz frequency band, which is basically noise-free as determined from extensive experiments on a large-scale indoor testbed featuring more than 100 nodes. Although the lack of external interference eases protocol design, our study reveals that — and characterizes to what extent — wireless links in the 868 MHz band still show large variations in performance that must be accounted for.
Having joined may father and his friend during the process of cutting down big trees in the village neighborhood I can personally vouch that this indeed a cumbersome and very complex task for both the planning and the execution phases. However, for us the tasks are made easier by the trimming of the tree's branches since my father's friend is the expert tree climber.
From your descriptions, it seems that your tree cutting procedures do not involved precut of the tree's branches before cutting the tree down.
I've got the feeling that this cutting tree problem can be solved by constraint programming techniques [1],[2]. Alternatively generic tools for constraint programming, for example OR-Tools and MiniZinc can probably do the same if not better [3],[4].
[1] Logic, Optimization, and Constraint Programming: A Fruitful Collaboration - John Hooker - CMU (2023) [video]:
Great stuff, has been meaning to create an online library of my burgeoning ebooks collections for quite som time now, this is exactly what the doctors ordered and it's based on Postgres.
Just wondering about the encrypted collection of ebooks from Kindle for example. Are these ebooks supported and does it only supports metadata, what about the content search for these ebooks?
So, Colibri is intended to be a companion to Calibre, maybe do like 80% of what it does, but not all of it. Also, I want Colibri's core to have a fully clean collar: It handles your personal books, but will not be able to automatically de-DRM books and such. However, the way book assets work, you're of course free to just attach an encrypted AZW3 file to a book!
> Are these ebooks supported and does it only supports metadata, what about the content search for these ebooks?
Have you seen https://github.com/colibri-hq/colibri/issues/45? Content search is planned, but requires access to a book's text content, obviously. My recommendation would be to use Calibre to strip DRM and convert the books to epub/mobi files, and import those to Colibri; this has the general benefit of ensuring access to content you bought without depending on Amazon's good will :-)
This is the limited offline version of the Internet for the rural communities but what we need is the local-first version of the Internet for the rural community [1].
Fun facts, about one third or 2.6 Billions of the world's population has no or very limited Internet connectivity [2]. The main root cause is most probably power not the infrastructure.
Most of the people in authority probably don't realize that this rural connectivity does not need a fast high speed network as long as it has connectivity. It can be slow as kbps bandwidth, a kind of "sipping" Bittorent based download, but a download nonetheless.
The main problem of the Internet connectivity it's not really the infrastructure itself but the overall power budget requirements for the connectivity infrastructure.
We need to bring back the very efficient wireles modulation for the remote and rural Internet as exemplify by the DMR with its very efficient 4-FSK [3],[4]. This type of wireless modulation employed constant envelope modulation that is far more efficient (8 to 15 times more efficient) than the alternative TETRA with comparable bandwith [5]. It's reported that DMR operates on 1 kWh per day while TETRA is on 15 kWh per day thus the former can be sustained by only solar panels but not the latter.
Please note that TETRA itself is not a very efficient modulation with π⁄4 differential quadrature phase-shift keying (π⁄4-DPSK) since it requires linear amplifiers due to its non-constant envelope wireles modulation. It's even worst for typical OFDM based system (e.g Wi-Fi HaLoW, LTE, 5G, etc) [6]. This is because a similar power budget setup to DMR would have required probably around 100 times more power or more than 100 kWh per day including the air-conditioning systems for the linear power amplifier systems [7].
Thus these remote and rural base stations can be potentially powered by merely solar panels and the infrastructure does not need to be expensive since the base station structure can be made from bamboo [8].
[1] Local-first software: You own your data, in spite of the cloud:
> We believe raw data based approach will transform how we use observability data and extract value from it.
Perhaps we need to have generic database framework that properly and seamlessly cater for both raw and cooked (processed) for observability something similar to D4M [1].
[1] D4M: Dynamic Distributed Dimensional Data Model:
The extraction of raw data is the cooking or processing, and the results are ingested back into the same database. I think it's the approach described in this article.
Fun facts, before muslim migration to Yathrib (now Madinah), one of the popular and richest Christian Byzantine Roman Emperors namely Heraclius was questioning the Meccan leader Abu Sufyan at the time (who later in his life become muslim) regarding Muhammad [1].
One of the question was “Do the nobles follow him or the weak?". It's reported that Abu Sufyan answered: “The weak and poor among us follow him. As for the high born and noble, none follow him.” The Emperor after that replied “I then asked you if the noble or the weak followed him. You answered that the weak followed him. Even so has it been with all the prophets, such having followed them.” [2]
This is a very popular article that get submitted every now and then (nearly every year) [1].
I think this kind of problem would be a very nice for logic, optimization and constraint programming that probably can be solved with modern tools like Google OR-Tool or Monash University MiniZinc [1],[2],[3].
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