The touch trigger probe plays an important role in modern metrology because of its robust and compact design with crash protection, long life and excellent repeatability. Aside from coordinate measuring machines (CMM), touch trigger probes are used for workpiece location on a machine tool and for the accuracy assessment of the machine tools. As a result, the accuracy of the measurement is a matter of interest to the users. The touch trigger probe itself as well as the measuring surface, the machine tool, measuring environment etc. contribute to measurement inaccuracies. The paper presents the effect of surface irregularities, surface wetness due to cutting fluid and probing direction on probing accuracy on a machine tool.
The present study was aimed to establish a novel TaqMan real-time PCR (RTm-PCR) for detecting and typing bovine viral diarrhea virus (BVDV), and also to develop a diagnostic proto- col which simplifies sample collection and processing. Universal primers and TaqMan-MGB probes were designed from the known sequences of conserved 5′ - and 3′-untranslated regions (5’UTR, 3’UTR) of the NADL strain of BVDV. Prior to optimizing the assay, cDNAs were tran- scribed in vitro to make standard curves. The sensitivity, specificity and stability (reproducibility) were evaluated. The RTm-PCR was tested on the 312 feces specimens collected from persistently infected (PI) calves. The results showed the optimum conditions for RTm-PCR were 17.0 μmol/L primer, 7.5 μmol/L probe and 51.4°C annealing temperature. The established TaqMan RTm-PCR assay could specially detect BVDV without detecting any other viruses. Its detection limit was 1.55×100 copies/μL for viral RNA. It was 10000-fold higher than conventional PCR with excel- lent specificity and reproducibility. 312 samples were tested using this method and universal PCR from six dairy farms, respectively. Positive detections were found in 49 and 44 feces samples, respectively. The occurrence rate was 89.80%. In conclusion, the established TaqMan RTm-PCR could rapidly detect BVDV and effectively identify PI cattle. The detection limit of RTm-PCR was 1.55 copies/μL. It will be beneficial for enhancing diagnosis and therapy efficacy and reduce losses in cattle farms.
This paper presents a comparison of different techniques to capture nominal data for its use in later verification and kinematic parameter identification procedures for articulated arm coordinate measuring machines (AACMM). By using four different probing systems (passive spherical probe, active spherical probe, self-centering passive probe and self-centering active probe) the accuracy and repeatability of captured points has been evaluated by comparing these points to nominal points materialized by a ball-bar gauge distributed in several positions of the measurement volume. Then, by comparing these systems it is possible to characterize the influence of the force over the final results for each of the gauge and probing system configurations. The results with each of the systems studied show the advantages and original accuracy obtained by active probes, and thus their suitability in verification (active probes) and kinematic parameter identification (self-centering active probes) procedures.