Luminosity thresholds of colored surfaces are determined by their heuristic upper-limit luminances in the visual system

Some objects in the real world themselves emit a light, and we typically have a fairly good idea as to whether a given object is self-luminous or illuminated by a light source. However, it is not well understood how our visual system makes this judgement. This study aimed to identify determinants of luminosity threshold, a luminance level at which the surface begins to appear self-luminous. We specifically tested a hypothesis that our visual system knows a maximum luminance level that a surface can reach under the physical constraint that surface cannot reflect more lights that incident lights and apply this prior to determine the luminosity thresholds. Observers were presented a 2-degree circular test field surrounded by numerous overlapping color circles, and luminosity thresholds were measured as a function of (i) the chromaticity of the test field, (ii) the shape of surrounding color distribution and (iii) the color of illuminant lighting surrounding colors. We found that the luminosity thresholds strongly depended on test chromaticity and peaked around the chromaticity of test illuminants and decreased as the purity of the test chromaticity increased. However, the locus of luminosity thresholds over chromaticities were nearly invariant regardless of the shape of surrounding color distribution and generally well resembled the locus drawn from theoretical upper-limit luminance but also the locus drawn from the upper boundary of real objects. These trends were particularly evident for test illuminants on blue-yellow axis and curiously did not hold under atypical illuminants such as magenta or green. Based on these results, we propose a theory that our visual system empirically internalizes the gamut of surface colors under illuminants typically found in natural environments and a given surface appears self-luminous when its luminance exceeds this heuristic upper-limit luminance.

Experimental Assessment of Effect of Backlash Control Parameters on Quadrant Protrusions of Circular Tests for CNC Machine Tools

Backlash, friction, and servo lag factors often result in protrusion or segment difference phenomenon in the moving speed reversal of a machine tool’s moving table. This phenomenon can be improved by adjusting the backlash control parameters of the machine tool controller, but the control parameters must vary with the feed rate and payload of the moving table. Therefore, this study performed the circular test process for CNC machine tools, and used different feed rate, radius, and payload motion conditions to discuss the effect of backlash control parameters on quadrant protrusions. First, this study used parameter-range reduction combined with the Taguchi method and the binary search algorithm to search for the optimal backlash control parameters in the parameter setting range, so that the machine tool could have preferable quadrant protrusion performance when executing circular tests. Afterward, the correlation of the moving table feed rate, radius, and payload to the quadrant protrusion was analyzed according to the experimental results. The results indicated that the machine tool moving table feed rate had the most apparent effect on quadrant protrusions, and the relationship between the payload and quadrant protrusion was influenced by the moving table feed rate and circular radius simultaneously.

Handling performance of tractor-semitrailers equipped with hydraulically interconnected suspension

This paper focuses on the contribution of a hydraulically interconnected suspension on the handling performance of a tractor-semitrailer. A hydraulically interconnected suspension model is integrated with a traditional tractor-semitrailer suspension for the purpose of study, and the hydraulically interconnected suspension system is first investigated through the bench test simulation to study its nonlinear and damping characteristic. Then a static rollover test, a steady-state circular test, a pulse steer input test, a pulse road input test and a random road input test are simulated in order to fully investigate the performance of a tractor-semitrailer with hydraulically interconnected suspension. The comparison analyses are conducted among two vehicles which are a fully loaded tractor-semitrailer without hydraulically interconnected suspension, an unloaded tractor-semitrailer without hydraulically interconnected suspension, a fully loaded tractor-semitrailer with hydraulically interconnected suspension and an unloaded tractor-semitrailer with hydraulically interconnected suspension. The obtained results show that the fully loaded tractor-semitrailer has enhanced handling performance, an improved steady-state rollover threshold and unchanged ride performance with the assistance of hydraulically interconnected suspension.

Analysis of accuracy of 5-axis CNC milling machine through standard and modified circular test

In analysis of accuracy of 5-axis CNC milling machine measuring system with telescopic kinematic ball bar was used. Standard measuring test was made. The modified test was proposed with application of investigated inclined basis. The obtained results were compared. The accuracy of machine tool in indirect way was evaluated.

A Novel Tb@Sr-MOF as Self-Calibrating Luminescent Sensor for Nutritional Antioxidant

Sesamol, is well-known antioxidant and can reduce the rate of oxidation and prolong expiration date. It is also potentially antimutagenic and antihepatotoxic, the detection of sesamol is important and remains a huge challenge. Herein, a new 3D alkaline earth Sr metal organic framework [Sr(BDC)DMACH2O]n (BDC = benzene-1,4-dicarboxylate; DMAC = N,N-dimethylacetamide) is synthesized and a probe based on Tb3+ functionalized Sr-MOF. The Tb(3+)@Sr-MOF showed good luminescence and thermal property. Due to the energy competition between sesamol and ligand, the luminescence intensity of sesamol increases meantime luminescence intensity of Tb3+ decreases, the ratio of the emission intensities (I344/I545) linearly increases with sesamol in concentrations ranging from 1 × 10−7 to 8 × 10−4 M. Furthermore, the fluorescence-detected circular test shows that the composite Tb(3+)@Sr-MOF can serve as ratiometric sensor for sensing of sesamol. This is the first example for self-calibrated detecting sesamol based on metal-organic framework (MOF).