State-constrained controllability of linear reaction-diffusion systems

We study the controllability of a coupled system of linear parabolic equations, with nonnegativity constraint on the state. We establish two results of controllability to trajectories in large time: one for diagonal diffusion matrices with an “approximate” nonnegativity constraint, and a another stronger one, with “exact” nonnegativity constraint, when all the diffusion coefficients are equal. The proofs are based on a “staircase” method. Finally, we show that state-constrained controllability admits a positive minimal time, even with weaker unilateral constraint on the state.

S235JRC+C Steel Response Analysis Subjected to Uniaxial Stress Tests in the Area of High Temperatures and Material Fatigue

Knowledge of the properties and behavior of materials under certain working conditions is the basis for the selection of the proper material for the design of a new structure. This paper deals with experimental investigations of the mechanical properties of unalloyed high quality steel S235JRC + C (1.0122) and its behavior under conditions of high temperatures, creep and mechanical fatigue. The response of the material at high temperatures (20–700 °C) is shown in the form of engineering stress-strain diagrams while that at creep behavior (400–600 °C) is shown in the form of creep curves. Furthermore, based on uniaxial fully reversed mechanical fatigue tests (R=−1), a stress-life (S-N) fatigue diagram has been constructed and the fatigue (endurance) limit of the material is calculated The experimentally determined value of tensile strength at room temperature is 534 MPa. The calculated value of the fatigue limit, also at room temperature, using the modified staircase method and based on the mechanical fatigue tests data, is 202 MPa. With regard to creep resistance, steel 1.0122 can be considered creep-resistant only at a temperature of 400 °C and at an applied stress not exceeding 50% of the yield strength corresponding to this temperature.

Temporal enhancement of cross-adaptation between density and size perception based on the theory of magnitude

The estimation of spatial distances is one of the most important perceptual outputs of vision and can easily be deduced even with detached objects. However, how the visual system encodes distances between objects and object sizes is unclear. Hisakata, Nishida, and Johnston (2016) reported a new adaptation effect, in which the perceived distance between objects and the size of an object shrink after adaptation to a dense texture. They proposed that the internal representation of density plays a role in a spatial metric system that measures distance and size. According to the theory of magnitude (Walsh, 2003), the estimation of spatial extent (distance and size) shares common metrics with the estimation of temporal length and numerosity magnitudes and is processed at the same stage. Here, we show the existence of temporal enhancement in cross-adaptation between density and size perception. We used the staircase method to measure the temporal property. The test stimuli were two circles, and the adapting stimulus had a dotted texture. The adapting texture refreshed every 100 or 300 ms, or not at all (static), during the adaptation. The results showed that the aftereffects from a refreshing stimulus were larger than those under the static condition. On the other hand, density adaptation lacked such enhancement. This result indicates that repetitive presentation of an adapting texture enhanced the density–size cross-aftereffect. According to the theory of magnitude, a common mechanism encodes spatial and temporal magnitude estimation and the adaptation to temporal density explains this cross-adaptation enhancement.

The Using of Stochastic Modeling Methods in Criminological Forecasting of Individual Criminal Behavior of Serial Killers

The article considers the stochastic modeling method used in criminology, which is understood as predicting changes in a system with variables ranging randomly with individual probabilities, which allows us to describe the state and probabilistic development of crime, its determinants, individual types, as well as the identity of criminals. The author investigates the possibilities of using this method for criminological purposes, when modeling and predicting the individual criminal behavior of serial killers. The hypothesis and the main conclusions obtained by M. V. Simkin and V. Roychowdhury in stochastic modeling of murders committed by A. R. Chikatilo, in particular, the possibility of using the Cantor`s or «devil's staircase» are checked. Thus, the author analyzed the data on 60 murders committed by M. V. Popkov, also known as the «Angarsk maniac», on the territory of the Irkutsk region in the period from 1992 to 2006. It is suggested that the total number of crimes committed by the «Angarsk maniac» also resembles the «devil's staircase», and the method used can indeed be extended to similar crimes. The author focuses on the fragment of the «Popkov staircase» in the period 1997-1998 as an abnormal surge in the activity of the criminal: an attempt is made to explain the number and frequency of murders by the Kantor staircase method and the pathological drive to kill people diagnosed in the criminal (homicidomania with sadistic elements). Investigation of the actual data on the probabilities of murders committed by M. V. Popkov, obtained by calculation and the theoretical model R. Lange is almost identical, which allows us to model the daily probability of murder as a function of the number of days that have passed since the last crime.

The Orofacial Somatosensory System Is Modulated During Speech Planning and Production

Purpose In our previous studies, we showed that the brain modulates the auditory system, and the modulation starts during speech planning. However, it remained unknown whether the brain uses similar mechanisms to modulate the orofacial somatosensory system. Here, we developed a novel behavioral paradigm to (a) examine whether the somatosensory system is modulated during speech planning and (b) determine the somatosensory modulation's time course during planning and production. Method Participants ( N = 20) completed two experiments in which we applied electrical current stimulation to the lower lip to induce somatosensory sensation. In the first experiment, we used a staircase method (one-up, four-down) to determine each participant's perceptual threshold at rest (i.e., the stimulus that the participant detected on 85% of trials). In the second experiment, we estimated each participant's detection ratio of electrical stimuli (with a magnitude equivalent of their perceptual threshold) delivered at various time points before speaking and during a control condition (silent reading). Results We found that the overall detection ratio in the silent reading condition remained unchanged relative to the detection ratio at rest. Approximately 536 ms before speech onset, the detection ratio in the speaking condition was similar to that in the silent reading condition; however, the detection ratio in the speaking condition gradually started to decrease and reached its lowest level at 58 ms before speech onset. Conclusions Overall, we provided compelling behavioral evidence that, as the speech motor system prepares speech movements, it also modulates the orofacial somatosensory system in a temporally specific manner.

Fatigue Strength Analysis of S34MnV Steel by Accelerated Staircase Test

This paper presents the reliability estimation of fatigue strength of the material used for crank throw components. The material used for crank throw components is forged S34MnV steel and subsequently heat-treated by normalising and tempering. High cycle fatigue testing under fully reversed cycling (R = −1) was performed to determine the fatigue limit of the material. The staircase test method is used to obtain accurate values of the mean fatigue limit stress until a number of cycles up to 1E7 cycles. Subsequently, the fatigue test results depend strongly on the stress step and are evaluated by the Dixon-Mood formula. The values of mean fatigue strength and standard deviation predicted by the staircase method are 282 MPa and 10.6MPa, respectively. Finally, the reliability of the design fatigue strength in some selected probability of failure is calculated. Results indicate that the fatigue strength determined from accelerated staircase test is consistent with conventional fatigue testing. Furthermore, the proposed method can be applied for the determination of fatigue strength and standard deviation for design optimisation of S34MnV steel.

Enamel Etching for Universal Adhesives: Examination of Enamel Etching Protocols for Optimization of Bonding Effectiveness

SUMMARY Objective: The purpose of this study was to evaluate whether different enamel etching methods with reduced etching times would improve the bonding effectiveness of universal adhesives. Methods and Materials: Three enamel etching methods, phosphoric acid ester monomer (PPM) etching, phosphoric acid (PPA) etching, and polyalkenoic acid (PLA) etching, and three universal adhesives, G-Premio Bond (GP), Prime&Bond elect (PE), and Scotchbond Universal Adhesive (SU), were evaluated. Initial bond strengths and fatigue strengths of universal adhesives to ground enamel and ground enamel etched for less than one, five, 10, and 15 seconds using different etching methods were determined. The bonded fatigue specimens were loaded using a sine wave at a frequency of 20 Hz for 50,000 cycles or until failure occurred with a staircase method. Atomic force micrograph (AFM) observations along with measurements of surface Ra roughness and modified surface area of enamel with different etching protocols were also conducted. Results: The bond fatigue durability of universal adhesives to enamel with PPA etching from less than one to 15 seconds and PLA etching for 15 seconds was significantly higher than that to ground enamel. The bond fatigue durability to enamel with PPM etching was not increased compared with ground enamel. The surface Ra roughness and surface area obtained with AFM of enamel increased after PPA and PLA etching, and those values were significantly higher than those of ground enamel. Furthermore, surface Ra roughness and surface area with PPA etching were significantly higher than those with PLA etching. However, surface Ra roughness and surface area of enamel with PPM etching were similar to those of ground enamel regardless of etching time. Conclusion: PPA etching for less than one to 15 seconds and PLA etching for 15 seconds improve universal adhesive bonding, surface Ra roughness, and surface area of enamel. However, PPM etching is not effective, regardless of etching time, in improving bonds strengths, increasing surface roughness, and increasing surface area.