Q. Hello! Please help me and my group with our assignment at uni! We have been asked to write a 3-page essay about x-ray microtomography. But it seems rather difficult to find information about that topic on the internet and in published texts. We would like any information available! Thanks a lot!
Answer
Microtomography, like tomography, uses x-rays to create cross-sections of a 3D-object that later can be used to recreate a virtual model without destroying the original model. The term micro is used to indicate that the pixel sizes of the cross-sections are in the micrometer range. This also means that the machine is much smaller in design compared to the human version and is used to model smaller objects.
These scanners are typically used for small animals (in-vivo scanners), biomedical samples, foods, microfossils, and other studies for which minute detail is desired.
The first X-ray microtomography system was conceived and built by Jim Elliott in the early 1980s. The first published X-ray microtomographic images were reconstructed slices of a small tropical snail, with pixel size about 50 micrometers. (JC Elliott and SD Dover. X-ray microtomography. J. Microscopy 126, 211-213, 1982.)
In 2005, Skyscan, a company that produces scientific instruments, introduced a nano-ct scanner, introducing the concept of Nanotomography. Other companies producing such scanners include Xradia for materials and semiconductor applications and Scanco Medical AG for medical applications.
Working principle
* Imaging system
Fan beam reconstruction
The fan-beam system is based on a 1-dimensional x-ray detector and an electronic x-ray source, creating 2-dimensional cross-sections of the object. Typically used in human Computed tomography systems.
Cone beam reconstruction
The cone-beam system is based on a 2-dimensional x-ray detector (camera) and an electronic x-ray source, creating projection images that later will be used to reconstruct the image cross-sections.
* Sample holder system
The sample stays still, and the camera and electronic x-ray source rotates.
This is best used for in-vivo animal scans, and other situations where the sample should remain unmoving, but is more expensive.
E.g.SkyScan-1076 or SkyScan-1078 or Scanco VivaCT 40 scanners for sample details.
The sample rotates, and the camera and electronic x-ray source stays still.
Much cheaper to build, since moving the sample requires fewer components than moving the camera and the electronic x-ray source.
* Open/Closed systems
Open x-ray system
In an open system, x-rays may escape or leak out, thus the operator must stay behind a shield, have special protective clothing, or operate the scanner from a distance or a different room. Typical examples of these scanners are the human versions, or designed for big objects.
E.g. Scanco medical XtremeCT scanner.
Closed x-ray system
In a closed system, x-ray shielding is put around the scanner so the operator can put the scanner on his desk or special table. Although the scanner is shielded, care must be taken and the operator usually carries a dose meter, since x-rays have a tendency to be absorbed by metal and then re-emitted like an antenna. Although a typical scanner will produce a relatively harmless volume of x-rays, repeated scannings in a short timeframe could pose a danger.
Closed systems tend to become very heavy because lead is used to shield the x-rays. Therefore, the smaller scanners only have a small space for samples.
E.g. SkyScan-1076 or SkyScan-1078 or Scanco mCT 40 or Scanco mCT 80 scanners
Typical use
* Biomedical
* Both dead and alive (in vivo) rat and mouse scanning.
* Human skin samples, small tumors, mice bone for osteoporosis research.
See in vivo microCT scanners for scanning examples.
* Electronics
Small electronic components. E.g. DRAM IC in plastic case.
* Microdevices
E.g. spray nozzle
* Composite materials and metallic foams
E.g. composite material with glass fibers 10 to 12 micrometres in diameter
* Polymers, plastics
E.g. plastic foam
* Diamonds
E.g. detecting defects in a diamond and finding the best way to cut it.
* Food and seeds
* E.g. piece of chocolate cake, cookies
* 3-D Imaging of Foods Using X-Ray Microtomography [1]
* Wood and paper
E.g. piece of wood to visualize year periodicity and cell structure
* Building materials
E.g. concrete after loading.
* Geology
E.g. sandstone
* Microfossils
E.g. bentonic foraminifers
* Space
E.g. Locating Stardust-like particles in aerogel using x-ray techniques [2]
* Others
E.g. cigarettes
* Stereo images
Visualizing with blue and green or blue filters to see depth
Java program, how do i remove all of a certain integer using arrays?
BB
i get arraylists but i'm completely lost when it comes to arrays
so far i have this (see code)
but it doesn't work and i don't know what i'm doing :(
how do i get the numbers into the array
i have to remove the zeroes and then reprint the array with no spaces...
import java.io.File;
import java.util.ArrayList;
import java.util.Scanner;
public class RemoveZero {
private static Scanner scan;
static int num [] = new int [100];
public static int[] readInArray(String filePath) {
try {
scan = new Scanner(new File(filePath));
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
private static int[] removeAndShift(int[] num, int index) {
int temp;
while (scan.hasNext())
temp = scan.nextInt();
int num1 [] = {temp};
return num1;
if (temp ==0)
num1.addInt(temp);
else
return num1;
}
public static void printArray(int[] num) {}
//"C:/Documents and Settings/10wangjessie/Desktop/AP COMPUTER SCIENCe/lab-5-data-file-compact.txt"
public static void main(String[] args) {
RemoveZero zero = new RemoveZero();
zero.readInArray();
zero.printArray();
}
}
how do i scan the integers into the array because it is from a file?
Answer
[EDIT] You should be able to use the Scanner class to pull in the numbers from the file in the same manner you would pull them from the keyboard, or a String.
I don't know the format of the data in the file, but you do, so select your methods in order to read appropriately based on what that input will be. Try something like this:
String filename = "C:\...";
try
{
file = new Scanner( new FileInputStream( filename ) );
for(int i=0 ; file.hasNextLine() && i<someArray.length ; i++ )
someArray[i] = Integer.parseInt( file.nextLine() );
}
catch( FileNotFoundException e)
{
System.out.println( "File not found or could not be opened.\nPress enter to continue." );
(new Scanner(System.in)).nextLine();
}
[/EDIT]
I'm a little confused about what you are shooting for, but here is an example of what I think you are asking.
public class RemoveZero
{
public static int[] removeZeros( int[] toRemove )
{
//make a copy of the provided array so as to not mutate it in case it is important
int[] temp = new int[toRemove.length];
for( int i=0 ; i<toRemove.length ; i++ ) temp[i] = toRemove[i];
toRemove = temp;
//locations in the array we are reading from and writing to
int source , destination;
//for each source index, if it is not a zero, write it to a destination index
for( source = destination = 0 ; source < toRemove.length ; source++ )
if( toRemove[source] != 0 )
toRemove[destination++] = toRemove[source];
//create a new array of the appropriate length, copy all relevant values over
int[] toReturn = new int[destination];
for( int i=0 ; i<destination ; i++ )
toReturn[i] = toRemove[i];
return toReturn;
}
//just prints the array out
public static void printArray(int[] num) { for( int i : num ) System.out.printf( "%3d," , i ); System.out.println(); }
//driver
public static void main(String[] args)
{
//random sample data
int[] toRemove = new int[]{ 48, 18, 0, 25, 52, 14, 0, 93, 90, 65, 66, 95, 81, 0, 76, 59, 79, 19, 76, 12 };
//print before and after removing zeros
System.out.print( "Pre:\t" );
printArray( toRemove );
System.out.print( "Post:\t" );
printArray( removeZeros(toRemove) );
}
}
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