Selected Projects — David Zhan

Search Engine

A scalable search engine featuring a Java HTTP server, query processing, distributed key-value store, and ranked retrieval over 1.28 million crawled pages.

Java, HTTP, indexing, ranking, information retrieval

Swift-edit

ML / Computer Vision

A reimplementation of the SwiftEdit paper with additional performance optimizations and architectural improvements for fast text-guided image editing.

Python, diffusion models, image editing

DavidCloud

Distributed Storage

A distributed cloud storage system backed by a key-value store, featuring coordinator-based routing, worker replication, persistent storage, and a hierarchical inode-style file system.

C++, distributed systems, KVS, replication, fault tolerance + recovery, storage systems

Instalite

Social Media Platform

An Instagram-style social platform with authentication, image uploads, personalized feeds, comments, real-time chat, vector search, and AI-assisted image and content features.

React, Express, AWS, DynamoDB, S3, ChromaDB

Trigram Viterbi POS Tagger

NLP

Implemented a trigram HMM part-of-speech tagger on Penn Treebank data with Viterbi decoding, smoothing, and suffix-tree handling for unknown words.

Python, Hidden Markov Model, Part-of-Speech Tagging, Classification

LSTM Sentiment Analysis

NLP / Empirical Analysis

Fine-tuned an LSTM on professor reviews and evaluated effects of data augmentation techniques including synonym replacement, random deletion, and back-translation.

Python, LSTM, data augmentation