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Modern X-ray detectors

Level of difficultyMedium
Reading time11 min
Views3.4K

Wilhelm Röntgen discovered X-ray November 8th 1895, when he did experiments with cathode rays in a vacuum tube. To capture and save images of the shadows from the X-rays, he used ordinary photoplates. Fortunately, sensitive to visible light silver based photoemulsions turned out to be sensitive to the X-ray too. These photoplates became the first X-ray detectors.

More than 100 years of scientific progress led to the creation of a number of various detectors for recording X-ray images. Developments of the microelectronics and semiconductor manufacturing technologies are crucial for development of the modern X-ray detectors. These detectors can transform the energy of the X-ray photon directly to the electrical signal. They allow capturing detailed, digital, high-resolution X-ray images.

Digital images are easy to work with. For example one can merge multiple macro images into an image of the whole object and represent monochrome images in false colors like Simon Procz did with this X-ray image of a flower he did in 2012.

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Formal verification of smart contracts in the ConCert framework

Level of difficultyMedium
Reading time11 min
Views1.2K

Hey! My name's Kirill Ziborov and I'm a member of the Distributed System Security team at Positive Technologies. In this article, I'll be continuing the discussion of methods and tools for the formal verification of smart contracts and their practical application to prevent vulnerabilities. The main focus will be on the deductive verification method, or more precisely, the ConCert framework for testing and verifying smart contracts.

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Hashicorp Vault — gcs + gcpckms

Reading time5 min
Views742

Secret Management and Why It’s Important

Hi! My name is Evgeny, and I work as a Lead DevOps at Exante. In this article, I will discuss the practical experience of setting up a high-availability HashiCorp Vault with a GCP storage backend and auto unseal in Kubernetes (K8s).

Our infrastructure used to consist of thousands of virtual and physical machines hosting our legacy services. Configuration files, including plain-text secrets, were distributed across these machines, both manually and with the help of Chef.

We decided to change the company’s strategy for several reasons: to accelerate code delivery processes, ensure continuous delivery, securely store secrets, and speed up the deployment of new applications and environments.

We decided to transition our product to a cloud-native model, which required us to change our approach to development and infrastructure. This involved refactoring our legacy services, adopting a microservices architecture, deploying services in cloud-based Kubernetes (K8s), and utilizing managed resources like Redis and PostgreSQL.

In our situation, everything needed to change—from applications and infrastructure to how we distribute configs and secrets. We chose Google as our cloud provider and HashiCorp Vault for secret storage. We've since made significant progress on this journey.

Why HashiCorp Vault?

There were several reasons:

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Top 10 Google Sheets Features to Enhance Your Productivity

Level of difficultyEasy
Reading time3 min
Views1.5K

It's been a while since my last appearance, but I'm excited to be back and to share something truly special with you. In this article, we'll explore my top 10 Google Sheets features that are guaranteed to boost your productivity, speed up your workflow, and make your data handling more efficient. So, without further ado, let's dive into these game-changing tools!

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How blocking on the Internet works: an overview of modern methods using a real example

Level of difficultyEasy
Reading time4 min
Views1.4K

A group of Indian scientists has published an overview of modern methods of Internet blocking introduced by government agencies, using the example of their own country. They studied the mechanisms used by Internet service providers restricting access to prohibited information, assessed their accuracy, and the ability to bypass such blocks. We would like to bring to your attention the main theses of this work.

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Use-Case Evolution Guide

Level of difficultyMedium
Reading time13 min
Views1.2K

Modern product development demands more and more sophisticated designs. This in turn leads to the increased complexity of both demand and implementation. Business is flooding the architecture and development teams with the new and changed requirements. Development teams are struggling to understand what the business demand is and find the best product increment strategy. One of the widely adopted conversational methods is the Use-Cases. This guide is intended to shed light on the process of the requirements development and maturing.

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Building firmware for Orange PI i96 (Orange PI 2g-iot) from scratch

Level of difficultyEasy
Reading time14 min
Views1.5K

Hellow my name is Dmitry. Once I bought "Orange PI i96", but unfortunately producer not update it firmvere very long. Last firmwere kernel version is 3.10.62 but kernel current at time this article writing (russian version) is 6.5.1. And so I decide build my own firmware from scratch, and do it from sourse completely.

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Mastering ChatGPT

Level of difficultyMedium
Reading time7 min
Views2.3K

In today's rapidly advancing technological landscape, natural language processing and comprehension have become essential components of everyday life. Leading the charge in this arena is OpenAI's ChatGPT API, renowned for its exceptional ability to understand and interact with human language. Imagine elevating ChatGPT's functionality to new heights, enabling it to carry out specific tasks based on commands given in natural language. This article aims to shed light on the potential of incorporating function calling into the ChatGPT API, thereby enhancing its utility. I will illustrate through practical examples how such extensions can unlock a myriad of opportunities and applications.

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The next steps after a good meetup on Portable SystemVerilog Examples for ASIC and FPGA

Reading time4 min
Views918

The meetup on January 14 at Hacker Dojo in Mountain View, California, went well, although not as planned - we spent almost all the time talking instead of doing hands-on exercises. The room we booked can fit 30 people and approximately 30 people did show up. The quality of participants was high: approximately half were familiar with hardware description languages and another half came from various software topics. 12 people filled out the questionnaire despite the fact that I forgot to bring 30 pens.

The discussion during and after the presentation was focused and very meaningful: microarchitecture and education, EDA infrastructure / build scripts, open-source ASIC design tools, the economics of ASIC design and manufacturing, high-level synthesis, transaction-level modeling, ASIC prototyping using FPGA boards, FPGA embedded in ASIC (Menta), new FPGA manufacturers (Gowin) and new design languages - Chisel and SpinalHDL.

Four persons came to me after the meeting to discuss their participation in working on open-source portable SystemVerilog examples, and another seven expressed this intention in the questionnaire. So we are meeting again in Hacker Dojo on Sunday, January 21, at 2 PM, this time not in the classroom area, but in the common shared area.

Generally, I am thinking of having regular meetings, probably on a weekly basis for a small team of developers of the educational materials and on a monthly basis for a wider audience, discussing various design and verification topics.

There were two correspondents of Slavic Sacramento who recorded the video of the presentation. They are going to make it available soon.

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Why x^0 = 1 visually

Reading time3 min
Views1.2K

The traditional definition for the operation of exponentiation to a natural power (or a positive integer) had introduced approximately as follows:

Exponentiation is an arithmetic operation originally defined as the result of multiple multiplications a number by itself.

But the more precise formulation is still different:

Raising a number X to an integer power N is an arithmetic operation defined as the result of multiple [N by mod times] multiplications or divisions one by number X.

Let's figure it out under the cut! >>

Wie ich ein einfaches Monitoring von Kanälen mit Benachrichtigungen an Slack ohne Erfahrung gemacht habe

Level of difficultyEasy
Reading time3 min
Views652

Arbeiten im technischen Support brachte zusätzlich zu allen Aufgaben die Pflicht mit sich, die Kommunikationskanäle zu überwachen. Dies wurde über den Grafana-Dienst realisiert, der die erforderlichen Metriken aus Zabbix bezog. Da die Art der Arbeit jedoch bedeutete, dass man nicht immer an seinem Arbeitsplatz sitzt, kam mir die Idee, dies ein wenig zu automatisieren und Benachrichtigungen auf das Telefon oder zum Beispiel in einen Messenger zu erhalten, falls ein Kommunikationskanal ausfällt. Allerdings hatte ich keinen Zugriff auf das Zabbix-System und auch keinen erweiterten Zugriff auf Grafana.

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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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GNU radio 802.11 black box optimization

Level of difficultyMedium
Reading time5 min
Views3K

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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How we designed the user interface for an enterprise analytical system

Reading time5 min
Views1K

In 2021, we were contacted by an industrial plant that was faced with the need to create a system for analyzing processes in its production. The enterprise team studied ready-made solutions, but none of the analytics system designs fully covered the required functionality. So they turned to us with a request to develop their own analytical system that would collect data from all machines and allow it to be analyzed to see bottlenecks in production. For this project, we created a data-driven UI/UX design and also developed a web-based interface for the equipment monitoring system.

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