Research

There are some research from my interests.

Latest

• Encoder-Decoder vs. Encoder-only vs. Decoder-only: Comparing the Three Transformer Architectures

  2026-09-26 ｜ #Words: 3417

  The paper "Attention Is All You Need" introduced the Transformer architecture, built from an encoder and a decoder.

• How LLMs Learn "Relationships": A word2vec Deep Dive

  2026-09-26 ｜ #Words: 4645

  The core idea behind how today's LLMs learn "relationships" from data traces all the way back to the classic word2vec.

• Reading Shannon: Notes on Information Theory

  2026-09-17 ｜ #Words: 1386

  In physics, entropy measures "disorder" or "chaos." Information theory borrows this idea. But here, "disorder" means something more specific: how surprising a piece of information is. In other words, how random it is.

• How Much Bitrate to Reduce When Converting H264 to HEVC with FFMPEG, and How to Measure Transcoding Loss Using SSIM (Structural Similarity Index)

  2025-08-09 ｜ #Words: 1287

  Recently, I’ve been organizing some videos and realized I have too many. I wanted to shrink some videos that already needed transcoding. Previously, I increased the bitrate by 10-20% to compensate for transcoding losses, but when converting from H264 to HEVC (or other formats), it might not be necessary to increase the bitrate—you might even be able to reduce it.

• Introduction to Maximum Likelihood Estimation and How to Automatically Learn Parameters with Code (ML/DL)

  2025-07-28 ｜ #Words: 4502

• Introduction to MLE: How to Automatically Learn Parameters with Code (A Sample of Machine Learning)

  2025-07-27 ｜ #Words: 4252

  Maximum Likelihood Estimation (MLE), also translated as maximum likelihood estimation, is a method for obtaining the optimal parameters of a model from sample data. For example, MLE can estimate the parameters of a probability density function (PDF). If a set of samples/datasets/statistics (likely) follow a normal distribution, we only need to find the mean and variance (or standard deviation) of the dataset to derive the probability density formula that fits the data.

• What Does the "@" Symbol Do in Python? Explaining Its Two Key Uses in D2L Code

  2025-01-22 ｜ #Words: 720

  Recently, while going through D2L (Dive into Deep Learning) code, I frequently noticed the "@" symbol appearing at the very top of classes or functions. Although Chapter 2 explains the comment `#@save` (indicating the following function is pre-defined in the package and can be used directly without redefinition), it does not explain the usage of the "@" symbol itself.

• Why Do We Need to Zero Out Gradients in PyTorch?

  2025-01-21 ｜ #Words: 319

  While reading a book today, I noticed that gradients are zeroed out at the end of the optimization algorithm. But the book didn’t provide an explanation. After checking, I found many optimizers also include this operation—why is that?

• Jekyll Not Generating HTML? Fix UTF-8 with BOM Encoding Issue

  2025-01-19 ｜ #Words: 195

  Today, while translating a blog post, I noticed Jekyll wasn’t generating HTML files as it usually does. After troubleshooting for a while, I found the cause: Jekyll cannot correctly recognize files encoded in **UTF-8 with BOM**.

• Run Ollama on GPU in Ubuntu: Direct Installation & Docker Deployment Guide

  2025-01-18 ｜ #Words: 2335

  I’ve been using Ollama on macOS for a while without issues, but recently noticed it was running on the CPU after switching to Ubuntu. At first, I thought it was out of VRAM—on macOS, Ollama automatically falls back to CPU if it runs out of memory. However, I found that Llama3.2 3B only uses 3GB of VRAM, which is far from exceeding limits. I checked the command line options but found no relevant settings, so I did some research.

• JSON Parsing Issue: Missing Commas Between Objects

  2025-01-14 ｜ #Words: 280

  When processing the returned JSON today, I encountered the following error: JSONDecodeError: Extra data: line 2 column 1 (char 134)

• FFmpeg CUDA Hardware-Accelerated Transcoding on Ubuntu

  2025-01-14 ｜ #Words: 1484

  This article uses an Ubuntu environment. The version of FFmpeg installed directly via APT on Ubuntu supports CUDA acceleration. This demonstration uses this pre-installed version—your experience may vary if you compile FFmpeg yourself or install it from other sources.

• Dell T5810 Workstation Build for Machine Learning & Gaming: A Budget-Friendly Guide with 3060 12GB or 2080Ti 22GB

  2025-01-14 ｜ #Words: 3274

  This is mostly a personal note to avoid re-researching solutions to problems I’ve already solved. However, since it took me about 20 days to write this article from start to finish, I can’t remember many details—so I may update it in the future.

• Fix: Not Implemented Error: Loading a Dataset Cached in a LocalFileSystem is Not Supported

  2025-01-05 ｜ #Words: 235

  If you check the top of the error message, you’ll find the root cause: the lookup path points to a `.cache/` directory (e.g., `xxxxxxx/.cache/`). This error persists regardless of whether you use an absolute or relative path.

• Dynamic Programming 2/n: Practicing DP with Concrete Problems (Climbing Stairs, House Robber)

  2024-11-05 ｜ #Words: 1534

• Dynamic Programming 1/n: What Is Dynamic Programming?

  2024-10-31 ｜ #Words: 1069

  Dynamic Programming (DP for short) is a programming paradigm, not a specific algorithm. It breaks down a large problem into smaller subproblems through recursion—mathematically speaking, it can be expressed as a polynomial. This allows solving problems of different scales with minimal changes to the code (a key advantage of recursion).

• What is complement graphs, isomorphic graphs, and self-complement graphs?

  2024-10-10 ｜ #Words: 539

  Many online articles lack clear explanations of complement graphs, isomorphic graphs, and self-complement graphs. Isomorphic graphs have the same points and edges but different positions, with the same degree sequence. Complement graphs share the same vertex set, with edges in one being those not in the other, forming a complete graph when combined.

• The Quirks of C printf Parameter Handling on macOS: What Happens When printf Uses %d to Print a Floating-Point Number?

  2024-07-26 ｜ #Words: 3724

  I was extremely curious about why this happens. The `0` on 32-bit systems is easy to understand, but why do we get random numbers on 64-bit systems? You can probably make a rough guess—it’s related to memory addresses (weird random numbers almost always point to address issues.

• What Is Hamming Code? A Deep Dive into Error Detection and Correction

  2024-07-22 ｜ #Words: 2622

  I first learned about Hamming codes a few yedars ago when I watched 3Blue1Brown’s video. I then looked into Hamming himself and thought he was brilliant. Later, I was impressed to discover in *The UNIX Hater’s Handbook* that Hamming was actually Brian Kernighan’s (co-author of the C language bible *The C Programming Language*, commonly known as K&R) mentor at Bell Labs and the third Turing Award winner.

• SMA (3/3) KMP (Knuth–Morris–Pratt) string matching algorithm

  2024-07-14 ｜ #Words: 4801

• SMA (2/3) Finite automaton string matching algorithm

  2024-07-12 ｜ #Words: 2160

• SMA (1/3) Naive and Rabin-Karp

  2024-07-12 ｜ #Words: 1911

  SMA (String matching algorithms) have always been my weak spot, and I happened to have a need for them recently, so I took the opportunity to catch up. String matching algorithms primarily involve identifying a substring (pattern, which is sometimes translated as pattern in other contexts, hence sometimes called pattern matching) within a larger body of text, such as finding a word in a text editor or a specific sequence in a DNA strand.

• What Are MSRs (Model-Specific Registers)?

  2024-04-22 ｜ #Words: 881

  MSRs (Model-Specific Registers) are specialized registers designed for various experimental functions, including debugging, program execution tracing, computer performance monitoring, simplified software programming, and power control.

• How to clone Raspberry Pi system disk to smaller disk/SD card

  2024-03-02 ｜ #Words: 2734

  How to clone system disk to a smaller hard drive or SD card on Raspberry Pi, including partition, set up and repair boot files.

• Solution: Missing IPv4 Address on Ethernet (eth0) in Raspberry Pi 4B (Raspbian Bookworm)

  2023-11-07 ｜ #Words: 922

  Raspbian recently upgraded from Bullseye to Bookworm last month, bringing many changes. As of writing this blog, less than 30 days have passed, so there aren’t many reference solutions available—we can only rely on previous versions or figure it out ourselves. In the future, the official team may fix this issue, or new problems may arise. If I encounter any, I’ll write a new article and link it here.

• Performance Record of Raspberry Pi 4B (CPU, Disk, FFMPEG, CV, llama2)

  2023-11-05 ｜ #Words: 1680

  This blog shares some reviews and tests of Raspberry Pi 4B. ZhongUncle compares it with Mac mini 2018 i5 in many aspects.

• APFS file system exploration

  2023-08-14 ｜ #Words: 2112

  This article aims to provide a low-level explanation of APFS, the file system used by Apple devices. Because I noticed that there was a lack of documentation on how APFS works in details, so I do some research and share my findings.

• Why hard drive lost much performance via USB?

  2023-07-19 ｜ #Words: 2150

  In hard disk performance, IOPS is a very important parameter. In terms of speed, this is the most important parameter to pay attention to, rather than the sequential read and write performance or random read and write performance that many people measure.

• How to convert BDMV (m2ts) to MKV, MP4 and other formats by ffmpeg

  2023-06-23 ｜ #Words: 1431

  BDMV is the format used by Blu-ray discs. This format cannot be played using playback software, and a hard disk player, which is a specialized device, must be used. But the most classic ffmpeg can convert it to other formats and maintain the same bit rate and definition, so that it can be viewed easily.

• What is the differences between gcc and Clang/LLVM?

  2023-06-10 ｜ #Words: 2404

  Recently, I found I was not very clear about the difference between GNU GCC and Clang. It affected implementation and learning somethings, so I spent free time in some days to research it carefully.

• How to record TikTok's live stream on macOS

  2023-05-31 ｜ #Words: 677

  Recently, I saw some live broadcasts on Douyin that were really interesting, and I wanted to record them. So I studied how to record these live broadcasts. There are two methods: recording the screen and downloading from the push source.

• How to install and use Plan 9 on Mac VM Fusion

  2023-04-21 ｜ #Words: 2545

  I encountered many problems when using VM Fusion to install Plan 9 on Mac. The official documents and some foreign blogs from the past two years were not clear, and even misleading (some situations have changed). So I am writing this article to help others who also encounter the same problem.

• What I find when using New Bing (GPT-4)

  2023-03-16 ｜ #Words: 1123

  ZhongUncle records what I find when using New Bing (GPT-4). Today New Bing called Bing Chat and can do more thing, but its mistakes are more often.

• Simple NN test implemented in Pytorch on laptop and Mac mini 2018

  2023-02-17 ｜ #Words: 570

  ZhongUncle records some performance of NN and know why bandwidth of gpu is important for Machine Learning.

• Sony A7R in 2023

  2023-02-09 ｜ #Words: 755

  I recently borrowed an A7R. This is my first time using a professional camera (not a card camera), and it is full frame tensor. So I spent some time to learn how to use it and how it works under various settings.

• Why GIF is static image rather than video?

  2023-02-03 ｜ #Words: 4222

  When I was organizing my disk, I have a question: What is GIFs classified as? Static image files or video files?Because if you put it in a video, GIF is classified as a static image usually and is composed of images; if you put it in an image, it shows animations. Then I have new problem: Why GIFs shows animations, but be classified as static images?

• How to install the Java development environment on macOS Terminal

  2023-01-10 ｜ #Words: 512

  Recently, I need to learn Java. Due to personal habits, I just want to use the terminal for development instead of using an IDE. But I never expected that I would be tricked by the official website once, and the downloaded Java could not be developed normally. So I wrote this article to explain how to configure it. It's very simple, just find the right official website.

• Introduction to Tree Selection Sorting

  2022-12-06 ｜ #Words: 797

  Maybe you like me have a question: Why heap sorting using a binary tree, but it is called heap sorting, rather than tree sorting? Because the predecessor of heap sort is called Tree Selection Sorting, it also uses a tree structure, but is slightly simpler. Finally we will talk about why invent heap sorting to replace tree sorting.

• How to use R language to draw charts and graphs (line, curves, etc.)

  2022-10-10 ｜ #Words: 1857

  If you are studying or engaged in data analysis-related, you must have used or been told to use R language. But with so many languages for data analysis, why use R? Because R can output very nice charts for publication. It may not be necessary for blogs, but it is necessary for publications such as papers and books. After all, the charts in most publications are not in color or flashy.

• Origin, Code, Performance and Differences of QuickSort algorithms(qsort)

  2022-10-04 ｜ #Words: 2899

  When I was learning quicksort algorithm, I found there are many style of code. I was very curious why. So I went to read Introduction to Algorithms to search for answer. Finally I found the reason be related to the development history of quicksort.

• Differences between index storage and hash storage in detail

  2022-09-03 ｜ #Words: 456

  There are two kinds storage structures in data structures that are easily confused, namely index storage structure* and hash storage structure (hash storage structure) You can find corresponding keyword according to address. It can be understood as a yellow pages. You can find someone's phone number based on name. So index storage is also called direct addressing

• Why Type-C in difference protocols is in difference speed

  2022-06-16 ｜ #Words: 2578

  Do you wonder why Type-C in difference protocols is in difference speed? I will tell you why the Type-C have different bandwidths under different protocols from pin definitions, protocols, etc.

• SQLite command line usage

  2022-02-13 ｜ #Words: 1425

  Recently, I plan to use the open source and free SQLite as a database to save money. And due to personal habits, I prefer the command line, so I record how to use SQLite in command line.

• How to Install (No Compilation or Brew Required) and Use FFmpeg to Convert MKV to MP4 on macOS, Including Hardware Acceleration

  2021-12-21 ｜ #Words: 1415

  Recently, I needed to convert MKV files to MP4 format. Since Apple's Compressor doesn't support MKV, I decided to use FFmpeg. However, the video files were extremely large, and basic commands were too slow—so I wanted to use hardware acceleration. Due to macOS's uniqueness, the hardware acceleration method provided on the official FFmpeg website doesn't work. After some research, I put together this quick tutorial in hopes of helping others in need.