An observer-based approach for the projection onto a 2d-curve under movement

Standard path control laws of autonomous vehicles use the shortest distance between the vehicle’s position and the path as a control error. In order to determine this distance, the projection point onto the path needs to be determined continuously. This requires fast algorithms that feature high numerical reliability in the field of vehicle application.This paper presents two different observer-based approaches for the projection problem. The identity observer reconstructs all states of interest for path control. The second one, a reduced observer, only possesses the curve parameter as a state and calculates the other values by algebraic formulas. Both algorithms consider the continuous movement of the vehicle, the run of the curve, and work without any approximation of the curve. Furthermore, they are applicable for arbitrary parameterized smooth curves, guarantee the required numerical stability, have short calculating time, and show good statistical properties. The performance is shown in several simulations as well as under real conditions.     

Physiological cost of energy-equivalent noise exposures with a rating level of 85 dB(A):: Hearing threshold shifts associated with energetically negligible continuous and impulse noise

In industry continuous or impulse noise does not occur exclusively; rather it is a combination of both. If low-level continuous noise or impulse noise (below 120 dB) is added to an already existing high-level continuous noise this often numerically causes no essential increase in the rating level. Yet, it cannot be expected that also aural strain of these exposures is always negligible. Therefore, in a cross-over test series, ten male subjects (Ss) were exposed to white noise of 94 dB(A) for 1 h (TS I), energy-equivalent to an 8 h-rating level L_Ard of 85 dB(A). In a second test series (TS II) the same exposure was combined with 900 energetically negligible 5-ms impulses with a noise level of 113 dB(A) which increased the rating level by only 0.4 dB. The noise exposure of TS I and TS II was followed by an idealized resting phase in a soundproof cabin. In a third test series (TS III) the continuous noise of 94 dB(A) / 1 h was followed by 3 h of white noise at 70 dB(A). Such an additional load increases the L_Ard by merely 0.1 dB to 85.1 dB(A). In all three test series, the noise-induced temporary threshold shift (TTS₂) and its restitution were measured. The continuous noise exposure of 94 dB(A) for 1 h was associated with a TTS₂ of around 20 dB which disappeared completely after about 2 h. The additional impulse noise caused a small increase in the TTS₂ and a prolongation of the restitution time. The maximum mean temporary threshold shift for the group increased only slightly (from 22.5 to 25.9 dB, which nevertheless can be statistically proven at a significance level of p 0.99). Yet, more importantly, the restitution time increased from 126 to 175 min, i. e. 3 h, which can be statistically proven at a significance level of p0.95. The TTS₂-values of TS III did not differ significantly from those resulting from TS I. That was expected as the conditions up to that point in time were identical. But due to the additional subsequent exposure, the mean restitution time increased considerably from 126 min up to 240 min (4 h). The mean total physiological cost represented by the integrated restitution temporary threshold shift (IRTTS) increased in TS II by approximately 40% and in TS III even by 140%.

Relevance to industry

The results of the study show that levels of noise which have no influence on the rating level which traditionally is calculated according to the energy-equivalence principle are often of great importance, as they can lead to considerably prolonged restitution times. Therefore, the purely energy-equivalent determination of the rating level of both impulse noise and low sound levels can lead to an underestimation of latent problems so that over time a reversible TTS can evolve into a permanent threshold shift. The results are also of importance for the acoustic design of break rooms for noise-exposed workers. There should be conditions that allow an undisturbed restitution of hearing.     

商用车涂料为水性聚氨酯涂料拓展更广泛的应用领域

随着环保重要性的不断增加以及法规压力的不断加大,西欧地区形成了各种低排放交通工具涂料的概念.本文着重介绍了双组分水性聚氨酯体系的应用情况,以及相关的原材料、技术和原理.     

Conceptualization without specific training in squirrel monkeys (Saimiri sciureus): A test using the non-match-to-sample procedure.

We report evidence that monkeys are able to categorize various pictures into conceptual classes without specific training for most of the conceptual classes involved. This was shown with a variation of the non-match-to-sample procedure: Each squirrel monkey was shown one picture as sample and, thereafter, two other pictures, one of which belonged to the same conceptual class as the sample and the other of which did not. To solve a trial, it was necessary to make a same–different judgment between the stimuli, that is, to view the sample and one response stimulus as "same." The conceptual classes tested included humans, monkeys, some nonprimate animal species, apples, bananas, trees, letters, telephones, various geometrical forms, and the concepts of sameness and numerousness. On the average, all monkeys performed with only few errors on the task. Their errors compare well in number and in quality with those performed by 3 human subjects tested under comparable conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of prefrontal lesions and combined prefrontal and limbic lesions on subsequent learning performance in the cat.

15 cats were given lesions in either the prefrontal cortex alone (n?=?7) or in the prefrontal cortex, anterior thalamus, mamillary bodies, and subiculum (n?=?8) before being tested in the acquisition of visual-reversal, delayed-alternation, and 2-way active-avoidance tasks. Lesioned Ss were compared to 6 unoperated and 4 sham-operated controls. As an extension of E. Irle and H. J. Markowitsch's (see record 1984-19842-001) study, in which triple limbic lesions failed to impair learning behavior of cats, the present study examined the effects of a lesion in the 4th brain structure (in addition to the original triple lesions). Results indicate that, compared with controls, Ss with prefrontal lesions were impaired in the acquisition of the avoidance task. In contrast, Ss with combined lesions were unimpaired in the acquisition of the visual-reversal task, facilitated in the acquisition of the avoidance task, but impaired in the acquisition of the delayed-alternation task. The superior performance Ss with combined lesions is interpreted as due to a lesion-induced functional shift acting on intact brain structures which, prior to massive limbic lesions, remained inhibited. (56 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychopathologic symptoms and cognitive test performance in schizophrenic patients

Psychopathological symptoms and cognitive test performance were examined in 34 acute schizophrenic patients. The results of a clusteranalytic approach in order to distinguish groups of patients with different syndromes were disappointing. Three dimensions of negative, hallucinatory-delusional, and disorganised symptoms could be established by factor analysis. The disorganised symptom dimension showed strong and significant relations to mnestic and intellectual impairments of the patients. Hallucinatory-delusional symptoms were related to deficits in tests of visual memory and visual search. Negative symptoms were not related to cognitive impairments of the patients. The results are discussed in respect of other studies reporting correlations of schizophrenic symptoms and cognitive disturbances, and with regard to hypotheses of brain dysfunction in schizophrenia. In future research, consideration of the three main dimensions of schizophrenic symptoms could be useful to reduce the heterogeneity of schizophrenic samples.     

Quantum chemical molecular dynamics study of "shrinking" of hot giant fullerenes

We present a detailed analysis of size-down trajectories of the "Shrinking Hot Giant" road of fullerene formation, revealed before by our quantum chemical molecular dynamics simulations. It is found that shrinkage of giant fullerenes occurs in two stages, fall-off and pop-out stage, respectively, and that it is an irreversible process occurring naturally at high temperatures. The driving force behind the energetically unfavorable C2 evaporation is the increase in entropy and pi-conjugation stabilization of the increasingly more spherical fullerene cages. A comparison of the theoretical results with existing experimental data shows the importance of annealing for the synthesis of smaller (C60, C70) fullerenes.     

Influence of a reduced wearing time on the attenuation of hearing protectors assessed via temporary threshold shifts

Valuable recommendations for the choice, utilization, care, and maintenance, and for the measurement of sound attenuation of hearing-protective devices have been laid down in international standards. Yet, by considering the wearing time of a hearing protector, the standard DIN EN 458 assumes a scarcely understandable drastic reduction in the effective attenuation even when the device is not used for only a short time in a noise-filled area. A 30 dB sound attenuation of such a protective device would, e.g., decrease to 12 dB if it were unused for only 30 min of an 8 h shift. Thus, the actual influence of a shortened wearing time on the protection of earmuffs was tested in a laboratory study using audiometric measurements of the temporary threshold shift (TTS₂) and its recovery after exposure to noise. For that purpose, the effectiveness of a hearing-protective device depending on the amount of time worn as prognosticated by DIN EN 458 was compared with the actual physiological effect of the earmuffs. Ten test subjects (Ss) participated in three test series (TS), each. In the first of the TS, the Ss were exposed to a sound pressure of 106 dB(A) for 1 h, during which the Ss wore noise-insulating earmuffs with an attenuation of 30 dB. The Ss were exposed to the same sound pressure in TS II; however, after 30 min, the earmuffs were removed for a duration of  min. Mathematically, this reduced the sound attenuation of the earmuffs to 12 dB, i.e., the average noise level over 1 h is 94 dB, which is equivalent to 85 dB(A) over 8 h. In order to evaluate the actual additional physiological cost of TS II, the Ss were exposed to 94 dB(A)/1 h without earmuffs in a third TS. This acoustic load, which is energy equivalent to the load in TS II, is also equivalent to 85 dB(A)/8 h. The results show that the continuous wearing of the earmuffs offers secure protection. However, the energetic approach and the levelling of differently structured noise loads according to the principle of energy equivalence leads to misconceiving results. The drastic reduction of the sound attenuation of the earmuffs predicted from the energetic point of view must be regarded as exaggerated. The TTS values show that TS II – which, according to the principle of energy-damage-equivalence, should result in the same effects as TS III – represents significantly less auditory fatigue. Thus, if the earmuffs are taken off briefly, a drastic reduction in the protection – as predicted in DIN EN 458 — does not result.

Relevance to industry

The results of this study demonstrate that the standards and regulations for noise rating do not correspond with the actual physiological facts and, therefore, can only be used in a very limited manner. Utilization of the principle of energy equivalence has proven problematic not only for rating noise. This principle also leads to an essential underestimation of the attenuation of hearing protectors when these devices are taken off for only a short time in a noise-filled area.     

The influence of measuring resolution on the subsequent roughness parameters of sanded wood surfaces

No recommendation was found in the literature with regard to which measuring resolution should be used when measuring wood surfaces and requirements in the general standard ISO 3274 (1996) appear too stringent. Due to its variability, wood requires longer evaluation length than recommended by ISO 4288 (1996) and combined with a high resolution will increase the matrix of data and so the time for scanning and data processing. A study was conducted on roughness profiles from sanded surfaces of oak, beech and spruce measured at different resolutions to see which is the lowest resolution that still allows accurate evaluation of the roughness parameters in real time. The effect of decreasing the resolution on roughness parameters was examined as compared with a resolution of 1 μm, which was taken as a reference. Results showed that a measuring resolution of 5 μm seems reliable for all species sanded with common grit sizes.