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Hacking a drone
Published in Ralph DeFrangesco, Stephanie DeFrangesco, The Big Book of Drones, 2023
Ralph DeFrangesco, Stephanie DeFrangesco
Start by typing “help” at the command prompt (#). Typing help will show the built-in commands the device uses. As mentioned earlier, the Parrot AR uses BusyBox, a Linux-like operating system, and uses very similar commands. The following commands might be helpful (all commands are in lower case): cat – Short for concatenate. This command shows the contents of a text file. Windows uses the “type” command. To use this command type cat <file-name>.cd – Change directory. Used to more from one directory to another. This is similar to the Windows “cd” command. To use this command, type cd <directory>.ls – List. This can be used to list files in a directory. This is similar to the Windows “dir” command. To use this command, type ls.pwd – Print working directory. This shows the current directory you are in. There is no Windows equivalent, but looking at the prompt will show the current directory you are in. To use this command, type pwd.vi – This is one of the oldest editors in Unix. You can use this command to edit a file by typing “vi <file_name”. There are books and tutorials on how to use this editor, so it will not be covered in depth here. One of the equivalents in Windows is using “notepad <file_name>”.
Basics of the Unix System
Published in Paul W. Ross, The Handbook of Software for Engineers and Scientists, 2018
F. Sanders Alton, Pickering Robert
The basic format of Unix commands is straightforward. We shall use the “ls” command to demonstrate the format of the commands as well as our conventions for describing them. ls List contents of directory Form: ls [-aClRx] [file ..]where the options are List all entries: usually entries whose names begin with a period are not listedMulticolumn output, sorted down the columnsGives “long listing,” which includes the type of file, permissions, link/directory count, owner, group, size and date of last modificationRecursively list subdirectories encounteredMulticolumn output, sorted across the columns The square brackets delimit optional portions of the commands and may be omitted. Thus, all of the following are legitimate “ls” commands: ls ls -a ls -aCl *.doc readme.* The letters following the hyphen are command options. In the above example, as in all of our examples here, there are actually many more options than we have indicated. We have included only the most commonly used options and, since not all command options are identical across all Unix systems, only those that are most commonly available.
Introduction
Published in Randall L. Eubank, Ana Kupresanin, Statistical Computing in C++ and R, 2011
Randall L. Eubank, Ana Kupresanin
In order to copy and move files around you must have permission to use them in such operations. Information about the permissions associated with a particular file or files in a directory can be obtained through the ls -l version of the ls command. As noted above, this produces a variety of output which includes the file permissions as the first, 10 character, component of the line associated with any particular file.
Low velocity impact response and influence of parameters to improve the damage resistance of composite structures/materials: a critical review
Published in International Journal of Crashworthiness, 2022
Kiran Kaware, Mangesh Kotambkar
Improvement in the impact performance of the composite is one of the major concerns in the field of composite structures. Many works of the literature suggested a different way to enhance impact resistance to damage. Hybrid composite and or sandwich composite, changing stacking sequence, number of plies, material, stitching of fibres, inserting short rods (Z-pinning), self-healing techniques, external patching, adding recovery agents, changing/adding different matrix material, use of natural fibres like jute rubber (biomaterial), particle toughening, hybridisation, use of carbon nanotubes [10–13], etc. are the various method/technique investigated by the authors in the literature. Experimental work is done using a drop weight testing machine, compression after impact testing machine [4,14,15]. Simulation software like Abaqus/Explicit, LS-DYNA, Ansys are used for numerical analysis [6,16,17]. Comparative study between experimental, analytical, and numerical results done to identify the best solution available.
Online detection and control of car body low-frequency swaying in railway vehicles
Published in Vehicle System Dynamics, 2021
Zhanghui Xia, Jinsong Zhou, Jianying Liang, Sansan Ding, Dao Gong, Wenjing Sun, Yu Sun
This study used the MATLAB LS-SVM toolbox to classify the three categories of test signals. To achieve a good classification effect, it is necessary to preset the appropriate parameters for the LS-SVM (namely the kernel function, penalty coefficient, and distribution coefficient) and then train and test the LS-SVM. The commonly used kernel function types include linear kernel functions, polynomial kernel functions, and radial basis function (RBF) kernel [22]. The latter kernel was used in this study, due to its lucrative combination of features. For the determination of the optimal penalty coefficient and the distribution coefficient, the cross-validation method was adopted. The latter is widely used for determining various LS-SVM parameters and is described elsewhere [23].
Parametric impact performances in a new type crash cushion barrier system using an energy absorption pipe
Published in International Journal of Crashworthiness, 2020
In this study, we produced flow stress–plasticity strain hardening curves to reflect the strain rate effects of various steel materials. For the flow stress–plasticity strain relation regarding the semi-static interpretation of the normal steel material (SS400), Equation (4) and the values of C = 5 and p = 5 can be used to show the relation as in Figure 1. Figure 1 shows the static flow stress and dynamic flow stress relations in the plasticity domain. In the semi-static domain in this figure, the domain comes close to a yield strength of 245 MPa for SS400, tensile strength of 400 MPa and plasticity strain of 0.28. The hardness level increases as the strain rate increases. The numerical analysis software LS-DYNA provides the Cowper–Symonds constitutive model. For this reason, as mentioned previously, the relationship between true stress and true strain can be simplified in a linear graph. In the plasticity domain, the bilinear hardening data are used. For the semi-static data of SS400, as shown in Figure 2, it begins at 225 MPa yield strength at 0 plasticity strain and increased linearly to 400 MPa of tensile strength. In the graph, after the tensile stress (where the plastic strain is 0.28) perfect plasticity is assumed and maintains the strength until complete failure of the material occurs. As for the SM490 steel material, the semi-static yield strength is 315 MPa. Next, the tensile strength increases up to 490 MPa following a linear pattern. After the tensile strength increases, it is assumed to have perfect plasticity. This is shown in the bilinear hardening curve based on the strain rate, C = 3200 and p = 5, which are used to show the results in Figure 3.