SmartShell: Automated Shell Scripts Synthesis from Natural Language

Modern shell scripts provide interfaces with rich functionality for system administration. However, it is not easy for end-users to write correct shell scripts; misusing commands may cause unpredictable results. In this paper, we present SmartShell, an automated function-based tool for shell script synthesis, which uses natural language descriptions as input. It can help the computer system to “understand” users’ intentions. SmartShell is based on two insights: (1) natural language descriptions for system objects (such as files and processes) and operations can be recognized by natural language processing tools; (2) system-administration tasks are often completed by short shell scripts that can be automatically synthesized from natural language descriptions. SmartShell synthesizes shell scripts in three steps: (1) using natural language processing tools to convert the description of a system-administration task into a syntax tree; (2) using program-synthesis techniques to construct a SmartShell intermediate-language script from the syntax tree; (3) translating the intermediate-language script into a shell script. Experimental results show that SmartShell can successfully synthesize 53.7% of tasks collected from shell-script helping forums.

The Application of Long and Short Cylindrical Shell Solutions for Stress and Flexibility Determination in a Single Mitred Bend

The continuous pipe bend behavior is well elaborated in literature. It is characterized by local ovalization of each cross section during bending which results in enhanced flexibility of it as compared to straight pipe. When pipe bend approaches some other structural elements of a piping system the end effect take place which can be described by so called long shell solution. This long solution is, in fact, a semi-membrane Vlasov’s solution when the derivative of any geometrical or force function in axial direction is much smaller than in the circumferential one [1]. Mitred bend is formed by conjunction by welding of two oblique sections of initially straight pipes. Its behavior during loading by pressure or bending moment is not evident and poorly described in standards. The goal of this paper is to give a set of general functions within a thin cylindrical shell theory which will give the opportunity to consider the mitred bend as an element of a piping system. Here we additionally introduce the so called short solution when the derivative of any parameter in axial direction is much bigger than that in circumferential one. Its main goal is to give the local behavior of stress in the vicinity of the oblique weld. Each of these two solutions satisfy by differential equations of forth order. The complete theoretical solution for a particular mitred bend is compared with a) existing analytical solutions and formulas; b) numerical results obtained by FEM with distinction of the zones of influence of a long as well as short shell solution; c) experimental data on real mitred bends given in the literature.