Finding logged in users using computer names

param($searchstr)
$list=@()
foreach($comp in Get-ADComputer -Filter "Name -like '*$searchstr*'"){
if(test-connection -computername $comp.name -count 1 -ErrorAction SilentlyContinue){
    $obj = New-Object System.Object
    $obj | add-member -type NoteProperty -Name Computername -Value $comp.name
    $obj | add-member -type NoteProperty -Name User -Value (gwmi win32_computersystem -ComputerName $comp.name | Select-Object Username -ErrorAction SilentlyContinue).username
    $list+=$obj
    }
}
return $list | Format-table -AutoSize -HideTableHeaders