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Affordable as a Bus, Comfortable as a Taxi: A Promising Type of Public Transport for Large and Medium-Sized Cities.Part3

Level of difficultyMedium
Reading time32 min
Views1.5K


Translation provided by ChatGPT, link to the original article in Russian

Link to Part 1: «Preliminary Analysis» (ру / eng )
Link to Part 2: «Experiments on a Torus» (ру / eng )
Link to Part 3: «Practically Significant Solutions» (ру / eng )
Link to «Summary» (ру / eng )

1 Playing Diplomacy


1.1 What this work is about


You're reading the third and final article in a series dedicated to minibus route schemes that would allow you to travel reasonably quickly, inexpensively, and most importantly, without any transfers, from any intersection to any other within a large city. You'll see many graphs, formulas, and figures below, but before we get to the technical part, I'd like to discuss the challenge of implementing this idea and invite you to participate in solving it.

1.2 A puzzle for the talented and brave (Eccentrics are welcome: ?)


I propose an adventure,
I propose a game,
I propose that you become part of a positive change in the lifestyle of almost a billion people around the planet,
I can't do this alone.
To start, I need your help with the following:
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CI/CD for iOS-projects: device or cloud? What’s better, Doubletapp’s take

Level of difficultyMedium
Reading time6 min
Views1.5K

Hey, Habr! I’m Yaroslav Fomenko, Doubletapp iOS-developer. After our IOS department deployed our CI/CD on a Mac Mini, we got an idea of scaling and encapsulating it. So we started researching ways to do it. First we thought of Docker, but there was neither enough info about it nor any other possible ways. In this article, we’ll look at all possible solutions we found for the deployment of Gitlab CI/CD on a device and in the cloud.

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Affordable as a Bus, Comfortable as a Taxi: A Promising Type of Public Transport for Large and Medium-Sized Cities.Part2

Level of difficultyMedium
Reading time56 min
Views1.2K

(Jean-Claude Mézières)

Translation provided by ChatGPT, link to the original article in Russian

Link to Part 1: «Preliminary Analysis» (ру / eng )
Link to Part 2: «Experiments on a Torus» (ру / eng )
Link to Part 3: «Practically Significant Solutions» (ру / eng )
Link to «Summary» (ру / eng )

Experiments on the Torus


This is the second part of a study dedicated to exploring new public transportation movement schemes. In the first part, we examined the simplest non-stop scheme and a single-transfer scheme based on it, which can be implemented in a grid city on a plane. In this part, our city model will be a grid city on a «flat» torus. Unlike a rectangle, a torus has no edge, and the positions of all points on it are absolutely equivalent. Due to the absence of an edge and (transitive) symmetry, calculations for a toroidal city are simpler, and numerical results are nearly identical to those for a rectangular city on a plane. These two conditions make a toroidal grid city an ideal testing ground for new passenger transportation movement schemes. In this article, we will explore two such schemes on the torus, and in the next one, we will return to the plane and adapt the results obtained here for use under the realistic conditions of a rectangular city.

The content of this study is not standalone and presupposes familiarity with the first part of the article. To understand Chapter 2, you will need a level of mathematics that corresponds roughly to the first two years of university; for everything else, high school level should suffice. It can be helpful to have a pencil and a piece of paper at hand while reading. If your browser displays formulas incorrectly, try refreshing the page a few times.
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Uniform gravity, can it exist?

Level of difficultyMedium
Reading time3 min
Views1K

Uniform gravity, can it exist?

1. The motion of a free particle-like cat

V. Komen, I. Tikhonenkov

Good morning! You've woke up. Having prepared coffee and toasts of bread you are drifting from a kitchen to a table before a large wall TV. The left hand keeps a small plate with toasts and the right one controls coffee level within your beloved mug. The life is plotted out for ten seconds to come. But Ervin is already worried that you, as usual, made conspiracy and decided not to share your breakfast with him. So the damned cat thrusts himself across you pass, hits your legs. By the next moment the plate, toasts and the mug are falling. And – yes! All those precious things reached a floor level by the same time. Physics...It's how it shows up, unexpected. And we used to identify ourselves as physicists. The unexpected thing is that we still do. It's whence our motivation originates. We cannot pass by any falling objects quietly.

15

Affordable as a Bus, Comfortable as a Taxi: A Promising Type of Public Transport for Large and Medium-Sized Cities.Part1

Level of difficultyMedium
Reading time40 min
Views2K

(Jean-Claude Mézières)

Translation provided by ChatGPT, link to the original article in Russian

Link to Part 1: «Preliminary Analysis» (ру / eng )
Link to Part 2: «Experiments on a Torus» (ру / eng )
Link to Part 3: «Practically Significant Solutions» (ру / eng )
Link to «Summary» (ру / eng )

1. About this series of articles


1.1 Central result


If I haven't made a critical mistake, I have discovered an astonishing passenger transportation scheme with unique characteristics. Imagine this scenario: you are in a big city and need to get from point A to point B. All you need to do is walk to the nearest intersection and indicate the destination on your smartphone or a special terminal installed there. In a few minutes, a small but spacious bus will arrive for you. The bus is designed for easy entry without bending, and you can bring a stroller, bicycle, or even a cello inside. It provides comfortable seating where you can stretch your legs. This bus will take you to the nearest intersection to point B, and you will reach your destination without any transfers. The entire journey, including waiting at the stop, will take only 25-50% more time than if you were traveling by private car. Based on my estimation, in modern metropolises, this type of transportation will be widely adopted, and the cost of a trip on such buses will be similar to the fare of a regular city bus.

Surprisingly, the reasoning behind these findings is based on relatively simple mathematics, and perhaps even a talented high school student, under fortunate circumstances, could have guessed them on their own. The practical significance of the topic and the modest level of mathematical requirements prompted me to make an effort to write the article in such a way that the reader could follow the path of discoveries, learn some research techniques, and gain a successful example to explain to their children the purpose of mathematics and how it can be applied in everyday life.
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PostgreSQL 16: Part 5 or CommitFest 2023-03

Level of difficultyMedium
Reading time28 min
Views1.3K

The end of the March Commitfest concludes the acceptance of patches for PostgreSQL 16. Let’s take a look at some exciting new updates it introduced.

I hope that this review together with the previous articles in the series (2022-072022-092022-112023-01) will give you a coherent idea of the new features of PostgreSQL 16.

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Technical Game Design. Configs, balance and content in the example of PC strategy

Level of difficultyMedium
Reading time13 min
Views1.7K

One of the common tasks that both beginners and experienced game designers face is describing a large amount of content to pass its parameters to the engine. This is not an easy task, given that it is very difficult to find materials on the technical aspects of game design. Well, let’s figure out how to transfer data to the engine.

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The Power of Email Marketing: Engaging Customers for Business Growth

Level of difficultyMedium
Reading time3 min
Views1.3K


Email marketing has emerged as a vital tool for businesses to nurture customer relationships and drive growth. In this article, we will explore the immense potential of email marketing through personal experiences and examples from renowned companies. From personalization to segmentation, retargeting, and building anticipation, discover how these strategies can elevate your email campaigns and deliver remarkable results.

The Art of Personalization in Email Marketing:
Personalization is a key aspect of successful email marketing. Take, for example, Amazon's tailored recommendations and exclusive offers. By delivering personalized content that matches customers' preferences and interests, Amazon creates a sense of exclusivity and fosters customer loyalty. In my own experience, implementing personalization in email campaigns resulted in increased open rates, click-through rates, and conversions. It's clear that customers appreciate the effort put into crafting messages specifically for them.

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How to Create Effective Product Funnels with Event Tracking

Level of difficultyMedium
Reading time8 min
Views1.2K

Regardless of how mature the product is, its owner will always be curious about how it performs, what the conversion rates are, and what areas for improvement there are. One of the most important tools that product owners should get access to at some point in time is an event tracking system.

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Setting Up an Experiment Environment for Data-Driven Product Development

Level of difficultyMedium
Reading time8 min
Views1K

As a product owner, it is common to face the question of whether to proceed with option A or option B. Or, which version of the screen should be implemented to achieve better results? Making such decisions can be challenging, especially when you are under tight deadlines with limited resources. Furthermore, such decisions are made based on personal judgment or copying the approach of a competitor, which can lead to suboptimal results.

The good news is that one can avoid such pitfalls by setting up a simple experiment environment that requires relatively low effort. In this article, we will describe how you can achieve this.

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Machine Learning for price optimization

Level of difficultyMedium
Reading time27 min
Views7.6K

This is a translated and adopted article I wrote for the Aha'22 (30 May 2022) conference. It describes an approach to a marketplace prices optimisation. Here I've outlined some important definitions and tried to define the scopes and roles of ML, algorithms, and humans in optimal pricing. Although the article covers rather basic things, still, you can find out some new formulas and ideas, because these basics are somewhat "well-known only in a very closed clubs", and besides, the real gem found here is the detailed recipe for ML engineers how to build optimal pricing systems.

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On the difference between regular functions and Lambdas

Level of difficultyMedium
Reading time11 min
Views3.3K

The point of this article is to explore Lambda functions, their dirrerences from regular functions and how they are implemented, based on C++, Python and Java programming languages.

Throughout this article I will be using godbolt.org to compile code and see machine code or byte code.

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Automation in mobile QA testing

Level of difficultyMedium
Reading time7 min
Views1.3K

It takes a lot of time and effort to develop a game. Finding and fixing errors before the release is one of the most crucial stages of the whole process, and the bigger your project is, the more people are usually involved in testing. Even the most uncomplicated games require a proper and thorough examination by QAs. The processes are automated to provide high-level project maintenance by increasing testing speed and reducing the influence of the human factor.

Automated testing is done with the help of specific programs, like Selenoid and Appium (although such frameworks are rarely used in games). 

However, the chances of successful automation depend primarily on the genre. Plus, it doesn’t cover all stages. For example, while the analytical issues can be automated, the visual aspect and gameplay are still tested manually (or are they really? We’ll get back to this later). We differentiate the two most popular types of auto testing: 

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Array of weak in Swift

Level of difficultyMedium
Reading time2 min
Views6.6K

In Swift, when working with objects, it’s important to manage memory correctly. One way to do this is by using weak references to avoid retaining objects too long and causing memory leaks. In this article, we will discuss how to create an array of weak references in Swift using a generic wrapper.

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GNU radio 802.11 black box optimization

Level of difficultyMedium
Reading time5 min
Views3.1K

In this post I'll share my experience in adjustment of WiFi physical channel. The channel was implemented on a software defined radio (SDR) platform. WiFi looks like a very complicated thing standardized over hundreds of pages. Could a non-expert with a PC and a couple of 100$ devices (HackRFs) somehow improve it? Here I try to develop a WiFi optimization approach basically agnostic of protocol implementation details. There's some math and Python programming in it.

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About «free» #iam, #oidc, #saml, #etc

Level of difficultyMedium
Reading time2 min
Views1.2K

There is a task to develop a solution that allows:

- Access control to web applications via #oidc/#saml

- Access control to vanilla #Kubernetes

- SSH access control to bare-metal hosts - using SSH certificate technology if possible

- Authorizing users to other server applications such as #Vault, #PostgreSQL, #Kafka, #ClickHouse, #MongoDB

- Being able to connect users from third-party organizations to certain resources based on group membership, etc

- Ensuring that everything described above works, including the bare metal environment

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Tutorial. Onchain Analysis basics

Level of difficultyMedium
Reading time16 min
Views2.2K

Last week, I introduced you to the world of onchain analysis and explored some of the ways it can be used to gain insights into the cryptocurrency market.

Today, we're taking things up a notch with a tutorial that will guide you through running your own onchain analysis. By the end of this tutorial, you'll have the skills and knowledge you need to start analyzing blockchain data and making informed decisions about your cryptocurrency investments. So let's dive right in and see what insights we can uncover!

This tutorial is built around the Bitcoin blockchain, but many of the techniques are applicable to any other blockchains as long as they have wallets, balances, and transactions.

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Autofill input fields in Android WebView

Level of difficultyMedium
Reading time12 min
Views14K

In this article, we will learn about autofill methods for input fields/forms in WebView used inside of an android app. I’d like to stress that the main topic is the autofill in WebView, because, when filling standard EditText views in the app - no issues arise. But when we display content owned by other parties, we can’t fill the form with our data in a simple way.

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