Effect of relaxation on pressure sensitivity index in a Zr-based metallic glass

Shear-banding features of as-cast and annealed Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 bulk metallic glass were investigated through Rockwell indentation tests. Isothermal annealing of the as-cast samples was conducted at temperatures below its glass transition temperature, Tg. The exothermal enthalpy during continuous heating below Tg decreases with increasing annealing temperature, indicating the gradual reduction of free-volume upon annealing. The observation on the morphology of shear-banding pattern around the indents implies a reduced shear bands activity in the annealed samples. The included angles (2θ) between two families of shear bands emanating from the edge of Rockwell indent decrease from 88° for the as-cast sample to 79° for the sample annealed at 633 K for 1 h, indicating a pressure sensitive plasticity. By Mohr–Coulomb criterion, the pressure sensitive index can be obtained on the basis of the measured 2θ, which increases with increasing annealing temperature, indicating an increase of “atomistic friction” due to the reduction of the free volume upon annealing.

Indentation study on the pressure sensitivity of a ZR-based bulk metallic glass

Spherical indentation test was conducted on as-cast and annealed Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 bulk metallic glass, and the evolution of the morphology of the deformation zone of indents upon annealing was investigated. The DSC traces of the as-cast and annealed samples show that the enthalpy change at the glass transition, ΔH, decreases with the increasing of annealing temperature, indicating the reduction of the free volume upon annealing. The morphology of the indents implies a reduced shear band activity in the annealed samples. The included angles (2θ) between two families of shear bands emanating from the edge of spherical indent in the as-cast and the annealed samples were measured to be in the range of 88-79°, which decrease with the increasing of annealing temperature, indicating pressure sensitive plasticity in the as-cast and annealed samples. By Mohr–Coulomb criterion, the pressure sensitive index, α, can be obtained on the basis of the measured 2θ. The sensitivity index increases with increasing temperature, implying an increase of 'atomistic friction' due to the reduction of the free volume upon annealing.

Cathodal transcranial Direct Current Stimulation (tDCS) to the right cerebellar hemisphere affects motor adaptation during gait

The cerebellum appears to play a key role in the development of internal rules that allow fast, predictive adjustments to novel stimuli. This is crucial for adaptive motor processes, such as those involved in walking, where cerebellar dysfunction has been found to increase variability in gait parameters. Motor adaptation is a process that results in a progressive reduction in errors as movements are adjusted to meet demands, and within the cerebellum, this seems to be localised primarily within the right hemisphere. To examine the role of the right cerebellar hemisphere in adaptive gait, cathodal transcranial direct current stimulation (tDCS) was administered to the right cerebellar hemisphere of 14 healthy adults in a randomised, double-blind, crossover study. Adaptation to a series of distinct spatial and temporal templates was assessed across tDCS condition via a pressure-sensitive gait mat (ProtoKinetics Zeno walkway), on which participants walked with an induced 'limp' at a non-preferred pace. Variability was assessed across key spatial-temporal gait parameters. It was hypothesised that cathodal tDCS to the right cerebellar hemisphere would disrupt adaptation to the templates, reflected in a failure to reduce variability following stimulation. In partial support, adaptation was disrupted following tDCS on one of the four spatial-temporal templates used. However, there was no evidence for general effects on either the spatial or temporal domain. This suggests, under specific conditions, a coupling of spatial and temporal processing in the right cerebellar hemisphere and highlights the potential importance of task complexity in cerebellar function.

Driver recognition based on dynamic handgrip pattern on steeling wheel

This paper proposes a novel biometric authentication method based on the recognition of drivers' dynamic handgrip on steering wheel. A pressure sensitive mat mounted on a steering wheel is employed to collect handgrip data exerted by the hands of drivers who intend to start the vehicle. Then, the likelihood-ratio-based classifier is designed to distinguish rightful driver of a car after analyzing their inherent dynamic features of grasping. The experimental results obtained in this study show that mean acceptance rates of 85.4% for the trained subjects and mean rejection rates of 82.65% for the un-trained ones are achieved by the classifier in the two batches of testing. It can be concluded that the driver verification approach based on dynamic handgrip recognition on steering wheel is a promising biometric technology and will be further explored in the near future in smart car design.

Driver verification based on handgrip recognition on steering wheel

This paper presents a novel driver verification algorithm based on the recognition of handgrip patterns on steering wheel. A pressure sensitive mat mounted on a steering wheel is employed to collect a series of pressure images exerted by the hands of the drivers who intend to start the vehicle. Then, feature extraction from those images is carried out through two major steps: Quad-Tree-based multi-resolution decomposition on the images and Principle Component Analysis (PCA)-based dimension reduction, followed by implementing a likelihood-ratio classifier to distinguish drivers into known or unknown ones. The experimental results obtained in this study show that the mean acceptance rates of 78.15% and 78.22% for the trained subjects and the mean rejection rates of 93.92% and 90.93% to the un-trained ones are achieved in two trials, respectively. It can be concluded that the driver verification approach based on the handgrip recognition on steering wheel is promising and will be further explored in the near future.

Authenticating the identity of computer users with typing biometrics and the fuzzy min-max neural network

In this paper, typing biometrics is applied as an additional security measure to the password-based or Personal Identification Number (PIN)-based systems to authenticate the identity of computer users. In particular, keystroke pressure and latency signals are analyzed using the Fuzzy Min-Max (FMM) neural network for authentication purposes. A special pressure-sensitive keyboard is designed to collect keystroke pressure signals, in addition to the latency signals, from computer users when they type their passwords. Based on the keystroke pressure and latency signals, the FMM network is employed to classify the computer users into two categories, i.e., genuine users or impostors. To assess the effectiveness of the proposed approach, two sets of experiments are conducted, and the results are compared with those from statistical methods and neural network models. The experimental outcomes positively demonstrate the potentials of using typing biometrics and the FMM network to provide an additional security layer for the current password-based or PIN-based methods in authenticating the identity of computer users.

Institutional investors in Australia: do they play a homogenous monitoring role?

This paper examines whether the presence of institutional investors in Australian publicly listed firms has an impact on firm performance. Our findings provide evidence that institutional investors are not a homogenous group of investors and that it is important to distinguish them by investment objective and their monitoring ability to exert influence. Results show that while institutional investors taken as a homogenous group appear to play an important governance role in terms of future firm performance, our analyses of the three broad typologies of institutional investors and by their respective sub-categories reveal differing conclusions. While pressure-resistant institutional investors (i.e., independent and having only investment relationship) significantly improve the short-term performance of Australian listed firms, they do not show any long-term monitoring ability. The impact of pressure-sensitive institutional investors is less clear, which is consistent with the view that these investors have some existing and potential business ties with the investee firms. More interestingly, we find that "faceless" investors via nominee and trustee institutions play an important monitoring role in creating a long-term firm value. Results have policy implications on the monitoring abilities of institutional investors in Australia.

Thermal control of high pressure die casting using computational fluid dynamics

The quality of high pressure die castings is a function of many interdependent parameters. It has been observed that many defects detected in the HPDC castings can be tracked back to poor die temperature distribution in the critical areas. It has therefore been recommended that the development of a technique to directly control the critical features - making them less sensitive to thermal related parameters - be very beneficial to the HPDC industry. From the information obtained from thermal image (processing), computational fluid dynamics has been applied to design the layout of internal cooling system and assign the flow conditions such as flow rate and pressure of the cooling water. it is observed that CFD prediction provides an excellent insight into the thermal balance of the high pressure die casting.

High pressure measurements of the refractive indices of two nematic liquid crystals

The refractive indices of two nematogens, 4-methoxy-benzylidene-4 prime -n-butylaniline (MBBA) and 4-n-pentyl-4 prime -cyanobiphenyl (5CB), were measured throughout their nematic ranges at pressures up to 2 kbar and temperatures up to 70 degree C in the first substance and up to 5 kbar and 145 degree C in the second. Measurements were made at lambda equals 5,890 A, using a sensitive interference fringe technique. Results are presented in the form of functions n//e(P, T) for the extraordinary index and n//o (P, T) for the ordinary index, obtained by least squares fits to the experimental data.

Blood pressure and cognitive function: the role of central aortic and brachial pressures

Central (aortic) blood pressures differ from brachial pressures and may be more relevant to the study of cognitive function, given that blood is delivered to the brain through the central large arteries. Pulse-pressure amplification reflects the augmentation of blood pressure between the central and peripheral arteries, which diminishes with aging. We aimed to determine the association between central blood pressure and cognitive function in independently living adults aged 20 to 82 years (N = 493). In adjusted regression models, higher central systolic pressure and higher central pulse pressure were each associated with poorer processing speed, Stroop processing, and recognition memory. Lower amplification was associated with poorer Stroop processing, working memory, and recognition memory. Higher brachial systolic pressure and brachial pulse pressure were both associated with poorer Stroop processing. In summary, central pressures and amplification were sensitive indicators of cognitive aging, predicting aspects of cognitive performance not predicted by brachial blood pressure.

Evaluating the usefulness of continuous leaf turgor pressure measurements for the assessment of Persimmon tree water status

Continuous plant water status monitoring is crucial in order to improve irrigation management. The noninvasive Yara ZIM-probe was assessed for detecting plant water stress in Persimmon trees (Diospyros kaki L.f.). The probe measures the pressure transfer function (Pp) through a patch of an intact leaf, which is inversely correlated with the turgor pressure. This technology was evaluated in two parallel experiments involving either distinct watering regimes or rootstocks with different drought tolerance [Diospyros lotus (L) and Diospyros virginiana (V)]. Concomitant measurements of midday stem water potential (Ψstem) and trunk diameter variations were taken throughout the experiments. Pp was highly correlated with Ψstem. Persimmon leaves exhibited the inversed Pp curve phenomena under water stress, which enabled the association of a particular range of Ψstem to each of the three leaf turgor states defined. Persimmon trees with no sign of initial or total inversion ensured Ψstem above −0.8 MPa, values considered of a well-watered Persimmon tree. Yara ZIM-probe readings as well as Ψstem and trunk diameter variation measurements pointed L as a more sensitive rootstock to drought than V. In conclusion, results showed that the Yara ZIM-probe can be used to continuously monitor water status in Persimmon trees although further research would be needed to ensure their feasibility for scheduling irrigation.