Need For Exact Knowledge Research Articles

Electric-Field Induced Shift in the Plasmon Resonance Due to the Interfacial Pockels Effect of Water on a Silver Surface

In the research on application of an optical modulator used for information communication, materials having a large Pockels effect, a refractive index change proportional to the electric-field, are required. It is known that the interfacial water on the surface of transparent oxide electrodes has a giant Pockels coefficient, which is an order of magnitude larger than the solid Pockels crystals practically used. It is important to know the Pockels coefficient of water on not only an oxide surface, but also a metal surface to understand the mechanism of the interfacial Pockels effect of water. However, a method has not yet been established for evaluating the coefficient of water–metal interface. Here we present an evaluation method of the Pockels coefficient of interfacial water on a metal (silver) surface from the spectral shift of the surface plasmon polariton resonance due to electric-field induced refractive index change of the interfacial water. The Pockels coefficient of interfacial water on Ag was evaluated as |r33|=5±1 pm/V, without need for exact knowledge of the thickness of the interfacial layer (electric double layer of water) as long as the penetration depth of the plasmon is larger than the thickness.

Physical Human–Robot Cooperation Based on Robust Motion Intention Estimation

SUMMARYCooperative transportation by human and robotic coworkers constitutes a challenging research field that could lead to promising technological achievements. Toward this direction, the present work demonstrates that, under a leader–follower architecture, where the human determines the object’s desired trajectory, complex cooperative object manipulation with minimal human effort may be achieved. More specifically, the robot estimates the object’s desired motion via a prescribed performance estimation law that drives the estimation error to an arbitrarily small residual set. Subsequently, the motion intention estimation is utilized in the object dynamics to determine the interaction force between the human and the object. Human effort reduction is then achieved via an impedance control scheme that employs the aforementioned estimations. The feedback relies exclusively on the robot’s force/torque, position as well as velocity measurements at its end effector, without incorporating any other information on the task. Moreover, an adaptive control scheme is adopted to relax the need for exact knowledge of the object dynamics. Finally, an extension for multiple robotic coworkers is studied and verified via simulation, while extensive experimental results for the single robot case clarify the proposed method and corroborate its efficiency.

Blind direction-of-arrival estimation algorithm for conformal array antenna with respect to polarisation diversity

Owing to the curvature of the conformal carrier, the polarisation diversity of element patterns is one of the most distinct characteristics of conformal array manifolds. Consequently, direction-of-arrival (DOA) estimation with conformal array antennas always couples with the estimation of the polarisation. Based on the fourth-order cumulants of the array outputs and an elaborately designed array structure, an estimation of signal parameters via rotational invariance techniques-based blind DOA estimation algorithm with respect to polarisation diversity is proposed for conformal array antennas, in which the displacement vectors required by ESPRIT are acquired by utilising ‘virtual array elements’ derived from actual array elements by ‘virtual cross-correlation computation’. Owing to the fact that these distance vectors used in algorithm implementation are not affected by element patterns and source polarisation, the 2D DOA estimates are decoupled from polarisation and obtained with no need for exact knowledge of array element polarised patterns. The proposed method achieves high-resolution 2D DOA estimation and is applicable to cylindrical, conical and spherical conformal carriers. The array set-up examples of conical, cylindrical and spherical carriers are presented for demonstration and the Monte-Carlo simulation results of DOA estimation with cylindrical conformal array are also provided to illustrate the effectiveness of the proposed algorithm.

MRI verified STN stimulation site – gait improvement and clinical outcome

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is effective in alleviating Parkinson's disease (PD) symptoms (tremor, rigidity and bradykinesia) and may improve gait and postural impairment associated with the disease. However, improvement of gait is not always as predictable as the clinical outcome. This may relate to the type of gait impairment or localization of the active DBS contact. The active contact was visualized on peri-operative magnetic resonance imaging in 22 patients with idiopathic PD, consecutively treated with bilateral STN DBS. Stimulation site was grouped as either in the dorsal/ventral STN or medial/lateral hereof and anterior/posterior STN or medial/lateral hereof. The localization was compared with relative improvement of clinical outcome (UPDRS-III). In 10 patients, quantitative gait analyses were performed, and the improvement in gait performance was compared with stimulation site in the STN. Of 44 active contacts, 77% were inside the nucleus, 23% were medial hereof. Stimulation of the dorsal half improved UPDRS-III significantly more than ventral STN DBS (P = 0.02). However, there were no differences between anterior and posterior stimulation in the dorsal STN. Step velocity and length improved significantly more with dorsal stimulation compared with ventral stimulation (P = 0.03 and P = 0.02). Balance during gait was also more improved with dorsal stimulation compared with ventral stimulation. Deep brain stimulation of the dorsal STN is superior to stimulation of the ventral STN. Possible different effects of stimulation inside the nucleus underline the need for exact knowledge of the active stimulation site position to target the most effective area.

Artificial Neural Network (ANN) Based Modeling for Karstic Groundwater Level Simulation

A relatively new method of addressing different hydrological problems is the use of artificial neural networks (ANN). In groundwater management ANNs are usually used to predict the hydraulic head at a well location. ANNs can prove to be very useful because, unlike numerical groundwater models, they are very easy to implement in karstic regions without the need of explicit knowledge of the exact flow conduit geometry and they avoid the creation of extremely complex models in the rare cases when all the necessary information is available. With hydrological parameters like rainfall and temperature, as well as with hydrogeological parameters like pumping rates from nearby wells as input, the ANN applies a black box approach and yields the simulated hydraulic head. During the calibration process the network is trained using a set of available field data and its performance is evaluated with a different set. Available measured data from Edward’s aquifer in Texas, USA are used in this work to train and evaluate the proposed ANN. The Edwards Aquifer is a unique groundwater system and one of the most prolific artesian aquifers in the world. The present work focuses on simulation of hydraulic head change at an observation well in the area. The adopted ANN is a classic fully connected multilayer perceptron, with two hidden layers. All input parameters are directly or indirectly connected to the aquatic equilibrium and the ANN is treated as a sophisticated analogue to empirical models of the past. A correlation analysis of the measured data is used to determine the time lag between the current day and the day used for input of the measured rainfall levels. After the calibration process the testing data were used in order to check the ability of the ANN to interpolate or extrapolate in other regions, not used in the training procedure. The results show that there is a need for exact knowledge of pumping from each well in karstic aquifers as it is difficult to simulate the sudden drops and rises, which in this case can be more than 6 ft (approx. 2 m). That aside, the ANN is still a useful way to simulate karstic aquifers that are difficult to be simulated by numerical groundwater models.

An acoustooptic method for sound velocity measurements in strongly sound-absorbing materials

An acoustooptic method for determining the velocities of longitudinal ultrasonic waves in a 105 to 108-Hz range in strongly absorbing (scattering) materials, when methods based on the sound transmission through a sample are unfit, is described. This method employs the acoustooptic determination of the acoustic impedance of the studied sample by measuring the reflection coefficient from the boundary between two contacting substances, namely, a liquid with the known (or measured) acoustic impedance and the studied solid sample. The method features the following advantages: (i) it is acceptable, when standard methods do not work due to the sound attenuation (scattering); (ii) there is no need for exact knowledge of sample sizes, the operating frequency, and the electromechanical coupling factor, and also for using reference samples; and (iii) the sound attenuation in a liquid and the distance from the sample surface to measurement points (required for calculations of the sound velocity) are easily measured. In this case, the velocity measurement error is usually 5–10%.

The application of gel permeation chromatography in the paint and allied industries. Part 4

Harmon has reported the use of GPC and differential scanning calorimetry in order to select hydrocarbon waxes from a possible thirty samples as replacements for five waxes that were used in the formulation of elastomers. Hydrocarbon resins of the type used in paint production were fractionated by GPC according to Christakundes et al. who measured the molecular weights of the individually‐collected fractions by VPO. By employing further analytical techniques such as infrared and NMR spectroscopy, these authors were able to study the distribution of chemical composition and ring content as a function of molecular weight in the resins. The average degree of polymerisation of the samples was then determined from the ring content without the need for exact knowledge of the chemical composition.

A Technique for the Description of Projections of Internal Organs Onto the Exposed Surface of Animals

The need for exact knowledge of the projections of internal organs onto the surface of animals is emphasized, for clinical veterinary medicine as well as for hunting purposes. A method is described for outlining the projections of dissected anatomical structures onto the exposed surface, on a photograph of the undisturbed animal in a natural standing position.

Some mineralogical and chemical changes induced by progressive metamorphism in the Green Bed group of the Scottish Dalradian

The petrology of the igneous rocks has for the last quarter of a century been established,on a sound quantitative basis, largely as a result of the body of experimental work available on silicate melts. In the field of metamorphism, however, progress has been much less marked, and the difficulties of the laboratory development of stresses comparable with those acting during regional metamorphism must for some time leave our knowledge of the crystalline schists far behind that even of the hornfelses. A quantitative approach, however, is not confined to the experimental side. The introduction of the conceptions of facies and grade raises a new need for exact knowledge of the compositions of the various minerals, both of those constituting the different isophysical assemblages of a given grade, and of the isochemical assemblages representing a given rock under the grade-conditions of the various facies established.