Are metric parameters sufficient alone in evaluation of the patellar instability? New angular measuring parameters

Purposes: When the evaluation of patellar instability is examined from the aspect of the conical-cylindrical anatomy of the tibia, metric measurement parameters such as the tuberositas tibia (TT)–trochlear groove (TG) and patellar tendon (PT) insertion–trochlear groove (TG) distances are not sufficient. We asked whether defined angular parameters reveal the rotational movement of the tuberositas tibia on the tibia shaft, additional to the metric parameters and there is a correlation between the metric and angular parameters. Methods: 19 patients with patellar instability and 22 patients without patellar instability were evaluated. For all patients, two angle and three length parameters were evaluated on the slices taken. Evaluations were made of the TT-TG, the midpoint of the PT insertion-TG distances, the anatomic midpoint of the dome of the TT-TG, the TG-PT angle, and the TG-dome angle (DA). The Pearson correlation test was used for the statistical analysis of correlations between groups. Results: A statistically significant increase was determined in the patellar instability group in the TG-DA and TG-PT angle values compared to the group without patellar instability ( p < 0.05). In both groups, a positive and strong correlation was determined between the TT-TG and the TG-PT and dome of the TT-TG distances, but no statistically significant correlation was determined between the tuberositas TT-TG and TG-PT angle and TG-DA. Conclusion: Metric parameters may not be sufficient alone in the evaluation of patellar instability. Metric parameters should be supported by additional angular parameters which reveal the rotational movement of the TT on the tibia shaft.

Calibration of Invar Angular Interferometer Optics with Multi-Step Method

At the National Institute of Metrology (NIM), China, the Small Angle Measuring System, which is based on the sine principle, was developed as the national primary standard for the plane angle in an angular measuring range of ±5°. The measurement uncertainty of this system is dominated by the accuracy of an invar angular interferometer optical system. To calibrate this angle interferometer system, a series of known reference standards were generated with a multi-step method using a double-deck rotary table. The measurement uncertainty of the calibration is estimated to be approximately 0.05'' (k=2).

Research on Layout of Active Decoy in Antagonizing ARM

Decoying technology is an effective mean to antagonize anti-radiation missile. Based on the basic principle of active decoy in antagonizing ARM, the critical resolution angle is clearly defined at first, and the scheme of active decoys is discussed in this paper. With wind speed, angular measuring error and lateral load failure considered, tow-source, three-source and four-source deploy scheme are presented and their operation effectiveness is simulated and analyzed. And under the condition that the distance between two radiation sources is changed, the operation effectiveness also is simulated. After contrast and analysis, three-source equilateral triangle layout is proved to be the most reasonable. The optimal distance also is given in this paper.