Month: September 2021

Implementation of a Hybrid Simulated Annealing Algorithm for Solving the Three-Dimensional Boxing Problem MATLAB

As I need to solve a three-dimensional packing problem in mathematical modeling, I have selected the paper “Hybrid Simulated Annealing Algorithm for Solving Three-Dimensional Packing Problems” published by Prof. Zhang Defu et al. in the Journal of Computing as the theoretical basis of the problem after searching. The abstract of the paper is as follows: A hybrid simulated annealing algorithm for efficiently solving the Three Dimensional Container Loading Problem 3D-CLP is proposed . The Three Dimensional Container Loading Problem (3D-CLP) requires loading a subset of a given set of boxes into a container such that the total volume of the loaded boxes is maximized. The hybrid simulated annealing algorithm presented in this paper is based on three important algorithms: (1) the composite block generation algorithm, which differs from … Read more

TransRepair: Automatic Testing and Improvement of Machine Translation

Recently, I read a research paper called TransRepair: Automatic Testing and Improvement of Machine Translation. The paper describes a methodology called TransRepair for automated testing of machine translation models under the software testing domain. Below, I will summarize the paper in several ways and discuss the key points. Introduction to TransRepair TransRepair is a method for automatically detecting and fixing conformance problems in machine translation software. It provides both black-box and gray-box approaches to address machine translation software conformance issues.The main steps of TransRepair include generating test cases, creating test guidelines, and automating the repair process. The method provides clear, rigorous and detailed algorithms for test case generation and uses four methods for quantifying sentence differences for comparison. In addition, TransRepair utilizes the principle of structural consistency as … Read more

Structure-Invariant Testing for Machine Translation (SIT) Paper Reading Summary

I have previously read the paper Structure-Invariant Testing for Machine Translation, which proposes a method for detecting the robustness problem of machine translation software systems. Below I will detail my understanding of its contents from several aspects. thrust SIT is a method for detecting robustness problems in machine translation software systems. This method utilizes a metamorphosis relation in a metamorphosis test, i.e., “structural invariance”. By selecting original sentences, generating similar sentences, obtaining results from translation software, performing constituent parsing and quantifying sentence differences, and filtering and detecting problems according to a set threshold, SIT can efficiently detect robustness problems in machine translation software systems. According to the experimental results, SIT can process 2k+ sentences in 19 seconds and achieves 70% accuracy for Google/Bing Translate. However, there is still … Read more

Ten key points for mastering C++ right-valued references: how to properly handle pure right values and would-be dead values

Recently I have been reading a lot of material on C++ right-values due to my work. In C++, right-valued is a very important concept that is crucial to understand the internal mechanisms of C++ and to implement efficient code. In this article, I will summarize 10 practical lessons about right values. There are two types of C++ right values: pure right values, and will-be-dead values. A right-valued reference extends the life cycle of a will-be-dead value, allowing the will-be-dead value to be used normally and not released by mistake. One effect of right-value references is to extend the life cycle of right values. A right-value reference extends the life cycle of a would-be-dead value, allowing the would-be-dead value to be used normally and not released by mistake. Temporary … Read more

Exploring computer interrupt handling: understanding external interrupts, exceptions and traps under the Intel x86 processor

Processor interrupt handling is one of the must-have knowledge in computer architecture. Under Intel’s x86 processor, interrupts can be categorized as external interrupts, exceptions, and traps. External interrupts come from the hardware and occur randomly, while exceptions are the result of error conditions detected during the execution of instructions within the processor. Traps, on the other hand, are generated by the program and are usually triggered by instructions such as INT n, INTO, and so on. In x86 processors, interrupt handlers handle interrupts, exception handlers handle exceptions, and system call service programs handle traps. These handlers can be located anywhere in the memory space and can have different privilege levels.Intel processors use interrupt gates, trap gates, and task gates to define the entry addresses of handlers. Of these, … Read more

Common memory management for intel 64 systems

Memory management is a very important part of the operating system. With the continuous development of computer technology, the way of memory management is also evolving. In this article, we will introduce several common memory management methods for the Intel 64 system. Flat-page memory management is a relatively simple way of memory management. It uses page-based management to mask out segment-based management. Specifically, it maps logical addresses directly to linear addresses, defines a code segment and a data segment, and the size of both segments is 4 GB.The advantage of this approach is that it is simple and easy to understand, but its disadvantage is that it does not allow for multi-process memory isolation. In order to solve the problem of multi-process memory isolation, a protected flat memory … Read more

Segmented Memory Management Overview

In segment-page memory management, the linear address of a segment is divided into linear pages of equal size (4KB, 4MB or 2MB, etc.). Physical memory space is also divided into physical pages of equal size. The operating system maintains a page table to manage the mapping of linear pages to physical pages. The page table is divided into two levels in the IA-32 architecture, the page catalog and the page table. The page catalog is an array whose elements are called page directory entries (PDEs), and each page directory entry describes a page table. The size of the page directory is one page (4KB) and there are 1024 page directory entries in a page directory. The size of a page directory entry is 4 bytes. The size of … Read more

Segment Memory Management Overview

The IA-32 system provides a segmented page-based memory management mechanism, with segmentation followed by paging. Page-based is provided to support virtual memory. Segment: The processor’s addressable linear memory space is divided into segments of varying sizes. A segment is a contiguous interval in the linear address space. Segments can hold code, data, stacks, or other data structures. The attribute information of a segment is described by its corresponding segment descriptor. A segment descriptor is a data structure that Intel manages using a segment descriptor table. The segment descriptor table can be up to 64KB. When G is 0, segments are measured in bytes, and the maximum segment length is 1MB. when G is 1, segments are measured in pages (4kb). The maximum segment length is 4GB. DPL is … Read more

Understand the inner workings of a computer system: how do memory, I/O devices, buses, and external memory work together?

Memory is the storage space that can be directly accessed by the processor. To speed up memory access, computer systems usually provide some cache, which is usually managed by hardware. I/O devices consist of I/O controllers and physical devices, and the processor manages the physical devices through the I/O controllers.The I/O controllers are mainly composed of control and status registers (CSRs) and data registers. The processor reads CSRs to obtain device status, writes CSRs to control device actions, and reads and writes data registers to exchange data. The kernel usually abstracts I/O devices into a set of registers and gives an I/O address to a register. The processor accesses the I/O registers through the I/O address. Many device registers in modern computer systems can be mapped into the … Read more