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This paper aims to report an enhanced mechanistic analytical model to account for the geometry of a concentric cylinder structure, the effect of an elastic bonding layer, and mechanical boundary co...

Bones self-optimize their mechanical behavior in response to mechanical stimulus. The objective of this research was to develop an integrated bone remodeling and stress binning algorithms into a finite element environment to elucidate the evolution of the bone properties as a function of loading. The bone remodeling algorithm was used to calculate the change in the density and elastic modulus based on the strain energy stimulus. The stress-binning procedure seeks to assign the properties to each element based on the levels of stress from the previous cycle, eliminating pseudo-lazy-zoning and stress dilation effects. The developed algorithms were used to analyze the response skull to loading associated with orthodontic devices. Specifically, a load was applied between the roots of the canine teeth and the first premolars while constraining the foramen magnum. Full-field contours of the displacement, strain, and strain energy were extracted after each remodeling cycle at nine commonly cephalometric landmarks. The results indicate that the overall mechanical response and the associated properties reached a steady-state behavior after nearly 50 cycles of applying the algorithm, where different zones within the skull exhibited unique evolution based on the locations from the loading and boundary sites. When approaching this steady-state condition, it was found that the upper incisor displacement is reduced by 72%, and the density is reduced by almost 7.5%. The finite element approach can be used in defining the treatment process by dynamically changing the loads. Future research will focus on integrating the time-dependent behavior of the bone.

Strain-mediated magnetoelectric composites have experienced a recent influx of research and transitional interests since they are hypothesized to hold the potential for further miniaturization of e...

Using lower limb exoskeletons in healthcare sector like for rehabilitation is an important application. Lower limb exoskeletons can help in performing specific functions like gait assistance, and physical therapy support for patients who are lost their ability to walk again. Since active lower limb exoskeletons require more complicated control instrumentation and according to the limitations of the power/weight ratio that arises in such exoskeletons, many quasi-passive systems have developed and employed. This paper presents the design and testing of lightweight and adjustable two degree of freedom quasi-passive lower limb exoskeleton for improving gait rehabilitation. The exoskeleton consists of a high torque DC motor mounted on a metal plate above the hip joint, and a link that transmit assistance torque from the motor to the thigh. The knee joint is passively actuated with spring. The action of the passive component (spring) is combined with mechanical output of the motor to provide a good control on the designed exoskeleton during walking. The results show that muscles' efforts on both the front and the back sides of the user's leg were decreased when walking using the exoskeleton with the motor and spring.

Strain-mediated multiferroic composite structures are gaining scientific and technological attractions because of the promise of low power consumption and greater flexibility in material and geometry choices. In here, the direct magnetoelectric coupling coefficient (DME) of composite multiferroic cylinders, consisted of two mechanically bonded concentric cylinders, was analytically modeled under the influence of a radially emanating magnetic field. The analysis framework emphasized the effects of shear lag and demagnetization on the overall performance. The shear lag effect was analytically proven to have no bearing on the DME since it has no effect on the induced radial displacement due to the conditions imposed on the composite cylinder. The demagnetization effect was also thoroughly considered as a function of the imposed mechanical boundary conditions, geometrical dimensions of the composite cylinder, and the introduction of a thin elastic layer at the interface between the inner piezomagnetic and outer piezoelectric cylinders. The results indicate that the demagnetization effect adversely impacted the DME coefficient between 70% and 86%. In a trial to compensate for the reduction in peak DME coefficient due to the presence of demagnetization, non-dimensional geometrical analysis was carried out to identify the geometrical attributes corresponding to the maximum DME. It was observed that the peak DME coefficient is nearly unaffected by varying the inner radius of the composite cylinder, while it approaches its maximum value when the thickness of the piezoelectric cylinder is almost 60% of the total thickness of the composite cylinder. The latter conclusion was true for all of the considered boundary conditions.

Emerging polymeric foams exhibiting unique microstructure of microspherical shells with reinforcing dense microspheres creates a new opportunity for impact-tolerant foam paddings in sport gears applications. This paper describes the static response of reinforced microcell consisting of an outer spherical shell and uniformly distributed microspheres while quantifying the stiffening effect. The distribution of the microspheres is illustrated using the Fourier series, allowing tuning of the reinforcing strategy. Expressions of the external and internal works are derived, whereas the Ritz energy method is adopted to calculate the deformations due to a compressive load distributed over a range of areas. Emphasis is given to the effect of the geometrical attributes of the microcell and the reinforcing microspheres on the resulting deformation response and stiffening effect. The framework is used to investigate the response of several case studies to elucidate the effects of relative radii ratio, reinforcement density, microcell wall thickness, and loading configurations on the stiffness. A new normalized strain energy parameter is introduced to simplify and accelerate the analysis while providing insights on the underpinnings of the observed buckling response. The results strongly suggest the viability of the newly discovered foam microstructure in managing static loads while providing an opportunity to strategically tune the mechanical response using the analytical framework presented herein.

This paper reports the unique microstructure of polyurea foams that combines the advantages of open and closed cell polymeric foams, which were synthesized through a self-foaming process. The latter was the result of aggressive mechanical mixing of diamine curative, isocyanate, and deionized water at ambient conditions, which can be adjusted on-demand to produce variable density polyurea foam. The spherical, semi-closed microcellular structure has large perforations on the cell surface resulting from the concurrent expansion of neighboring cells and small holes at the bottom surface of the cells. This resulted in a partially perforated microcellular structure of polyurea foam. As a byproduct of the manufacturing process, polyurea microspheres nucleate and deposit on the inner cell walls of the foam, acting as a reinforcement. Since cell walls and the microspheres are made of polyurea, the resulting reinforcement effect overcomes the fundamental interfacial issue of different adjacent materials. The partially perforated, self-reinforced polyurea foam is compared to the performance of traditional counterparts in biomechanical impact scenarios. An analytical model was developed to explicate the stiffening effect associated with the reinforcing microspheres. The model results indicate that the reinforced microcell exhibited, on average, ~30% higher stiffness than its barren counterpart.

This paper comprises a study of the grasping stability for an underactuated robotic manipulator under the condition of varying the position of different sizes cylindrical grasped objects. Grasping forces were calculated both theoretically and Via a CAD model for a 3-DOF underactuated robotic manipulator. The experimental part comprises the fabrication of the manipulator and performing the required tests on this manipulator by changing the position and size of the grasped object. Contact forces were observed experimentally by using the Force Sensing Resistors (FSR). Maps of stability and ejection for three different cylindrical object diameters (160, 200, 240) mm were presented. As a result, it was found that stable grasping is greatly affected by the size and location of the grasped object, where stable grasping is achieved for objects located near the actuator position.

Background and objective Transfer functions could model biomechanical parameters to conveniently analyze the system dynamics of the lower limb during daily activities, e.g., walking. The current study evaluates the feasibility of transfer functions as a means of predicting surface electromyography (sEMG) of lower limb muscles based on axial tibial (ATA) and femoral (FA) accelerations. Since the transfer functions are comparable in accuracy to commonly used long short-term memory models (LSTM), the transfer function-based methodology can assist in the design of novel prostheses while being competitive with mainstream models. Methods Data were collected from eight participants with no medical history that would alter their gait cycles. The data included the sEMG of four primary muscle groups, ATA and FA, and heel-strike triggering signal, while the subjects walked at 5.28 km/h on a treadmill. A fast Fourier transform (FFT) was performed on the filtered ensemble averages of the ATA, FA and normalized average rectified sEMG signals, which were used to approximate the time domain Fourier series. Transfer functions relating ATA-to-sEMG and FA-to-sEMG were derived from the Fourier series equations to generate time-domain intra-subject predictions of sEMG signals. With respect to predictive accuracy, these transfer functions were compared with sEMG-to-sEMG LSTM models trained on sEMG data from some of the participants. It was hypothesized that the transfer functions would be at least comparable to the LSTM models. Results The results indicate that the predicted sEMG signals were able to capture the temporal characteristics of the measured sEMG signal based on either ATA or FA. The muscle activities and acceleration were in good agreement with the walking gait cycle events. Only 13 Fourier terms were needed to effectively predict the sEMG from the acceleration signals, indicating the computational efficiency of the investigated analysis framework. For the ATA-to-sEMG transfer functions, the mean square difference (MSD) between the predicted and measured sEMG signals was low and comparable to the LSTM models. Conclusions Overall, the feasibility and competitiveness of the transfer functions with LSTM models was confirmed with respect to predictive accuracy. Potential applications of the transfer functions include the control of powered prosthetics and the detection of gait pathologies.

This paper presents an artificial neural network (ANN) trained on the patterns of slip signals; these patterns were generated by using conventional sensors with a novel design of fingertip mechanism for detecting the slippage of a grasped object under different types of dynamic loads. This design is to be used with an underactuated triple finger artificial hand based on the pulleys-tendon mechanism. The grasped object is designed in a prism shape with three direct current motors with unbalance rotating mass to generate excitation in the object. Also, this object is covered with different types of surface materials, namely, spongy rubber, glass, and wood. Three types of external loads are used to disturb the grasping process represented by quasi-static pulling on the object, the dynamic load on the object, and on the artificial arm in separate form. The mathematical modeling has been derived for the proposed design to generate the signal of contact force components ratio through using the conventional sensor signals with the aid of Matlab-Simulink software. The ANN has been trained on the basis of the patterns of force component ratio signals at slippage occurrence, in order to detect slippage and then prevent it without the need for any knowledge about the surface properties of the grasped object. The experimental results are discussed in comparison with the physical aspect of the slippage phenomenon, and they show good agreement with the physical definition of the slippage phenomenon. In addition, the network evaluation results are discussed with different parameters that govern the controller operation, such as network error, classification efficiency, and delay in response time.

SUMMARYHuman fingers possess mechanical characteristics, which enable them to manipulate objects. In robotics, the study of soft fingertip materials for manipulation has been going on for a while; however, almost all previous researches have been carried on hemispherical shapes whereas this study concentrates on the use of hemicylindrical shapes. These shapes were found to be more resistant to elastic deformations for the same materials. The purpose of this work is to generate a modified nonlinear contact-mechanics theory for modeling soft fingertips, which is proposed as a power-law equation. The contact area of a hemicylindrical soft fingertip is proportional to the normal force raised to the power of γcy, which ranges from 0 to 1/2. Subsuming the Timoshenko and Goodier (S. P. Timoshenko and J. N. Goodier, Theory of Elasticity, 3rd ed. (McGraw-Hill, New York, 1970) pp. 414–420) linear contact theory for cylinders confirms the proposed power equation. We applied a weighted least-squares curve fitting to analyze the experimental data for different types of silicone (RTV 23, RTV 1701, and RTV 240). Our experimental results supported the proposed theoretical prediction. Results for human fingers and hemispherical soft fingers were also compared.

The efficiency of strain-mediated magnetoelectric composites is heavily reliant on the effectiveness of strain transfer between the different constituents. Many analytical and experimental studies have trialed various materials, geometries, and boundary conditions reporting the effect of these attributes on the magnetoelectric response. However, a more sophisticated, but not yet pursued, approach is to investigate the strain distribution in order to discern the factors that are most influential and to provide insight on how these factors should be manipulated to optimize the coupling efficacy. In this study, a mathematical model is developed to observe the radial and tangential strains in a concentric cylinder composite structure consisting of a piezoelectric outer layer bonded with a thin elastic layer to an inner piezomagnetic layer. Results from the study elucidate that the strain distribution behavior was dependent on the mechanical properties of the constituents as well as the bonding condition. Remarkably, analytical results showed that the direct magnetoelectric coefficient can be substantially enhanced, if probing takes place at strategic locations, i.e. , leveraging strain localization, on the piezoelectric layer that maximize the difference between the radial displacements giving rise to higher magnetoelectric response.

The effect of several mechanical boundary conditions on the dynamic magnetoelectric (ME) effect is analytically investigated for layered cylindrical composites. The study consists of deriving a mechanics-based model for two concentric cylinders made of lead-zirconate-titanate (PZT) and cobalt ferrite (CoFe2O4), separated by a thin elastic layer, which is treated as strain mediator with no effect on the functional behavior of the system. Different thicknesses of the cylindrical composites and the elastic layer are considered in this study. For each case, nine sets of boundary conditions, four traditional and five non-traditional, were applied. Results show the dependence of the ME effect on the boundary conditions as well as on the inclusion of the elastic layer between the two cylinders, where both affect the strain transduction between the active layers; namely the piezomagnetic (CoFe2O4) and piezoelectric (PZT) layers. It was found that the maximum ME effect is attained for conditions in which the outer boundary is subjected to a uniform mechanical pressure. The inclusion of a thin elastic bonding layer was found to increase the ME response, the thickness of which was further investigated to establish limits of applicability of the reported model.

This study reports an alternative route for obtaining crystalline metal boride composite powders at low temperatures using various chemical reactions. The ternary system of Co-Ni-B was studied by using anhydrous metal chlorides and sodium borohydride powder mixtures. The reactions were carried out in a sealed reactor under autogenic pressure, placed in a chamber furnace. The unwanted chloride phases were removed by hot water leaching after reaction. Some of the purified powders were annealed at 1100 degrees C to improve the crystallinity. Effects of different reaction conditions on the formation and microstructure of the final powders were investigated. Phase, chemical and microstructurel characterizations and particle size measurements of the synthesized and annealed powders were conducted using X-ray diffractometer (XRD), X-ray fluorescence spectrometer (XRF), scanning electron microscope (SEM/EDX) and dynamic light scattering technique. The results revealed the positive effect of inorganic molten salt mixture (LiCl/KCI eutectic mixture) on the formed phases during the reaction between CoCl2, NiCl2 and NaBH4 powder blends. After their reaction at 750 degrees C in a sealed reactor under autogenic pressure, crystalline cobalt-nickel-boron based composite powders were achieved with an average particle size of 60 nm.

This paper deals with the determination of stresses and deflections of clamped circular diaphragm strengthened by one or two ring-shaped concentric ribs, under uniform static and dynamic pressures. The simulation has been achieved by using the well-known engineering software finite element package MSC/NASTRAN. As a design study, the effect of using a clamped ring, and the effect of using a ring-shaped rib on both surfaces of diaphragm instead of one, has been discussed in this work. To show the effectiveness of this study, results of this work have been compared with published data [1]. In the conclusion, the authors underline the validity of the considered design study, and the optimization of strengthened diaphragms.

The construction industry has seen a proliferation of continuous and discontinuous fiber-reinforced polymer composites due to their high strength-to-weight and stiffness-to-weight ratios while being resilience to harsh environmental and operating conditions. This paper reports a comparative experimental investigation of field-deployed E-glass/Epoxy composite panels with those freshly manufactured to elucidate the effect of deployment conditions on the performance of these panels. Samples extracted from underground vault after power-line explosion due to arcing fault were examined using optical and atomic force microscopes to assess the extent of the damage. The samples were also characterized using a dynamic mechanical analyzer to explain the change in the properties post-explosion quantitatively. Microscopy investigations show no significant change in morphology or topography of the panels as well as the absence of failure modes such as delamination, fiber-failure or core-failure. Nonetheless, surface contaminations due to service conditions were found to exaggerate the surface burn marks despite the fire retardation properties of the composite panels. The dynamic mechanical properties of the panels were found to change as a function of temperature and loading frequency slightly. A shift in transition temperatures (Tβ and Tg) was found to be within a few degrees Celsius. The storage modulus was reduced by 21%, while the overall complex modulus remained relatively constant when comparing fresh and field-deployed samples. A frequency and temperature dependent model was used to fit the dynamic data and found to provide insights into the microstructure evolution of the polymer matrix.

A novel europium (III) nitridoborate, Eu3[B3N6], was successfully synthesized by oxidation of Eu3II[BN2]2 with Br2 at 1073 K. The compound crystallizes in the trigonal space group R3c (No:167) with a=11.9370(4) Å, c=6.8073(4) Å, and Z=6. The crystal structure of Eu3[B3N6] consists of isolated, planar cyclic [B3N6]9- units which are charge-balanced by Eu3+ cations. The oxidation state of Eu was investigated by Mössbauer spectroscopy, electron spin resonance (ESR) spectroscopy, and quantum chemical calculations. The 151Eu Mössbauer spectroscopic measurement at 77 K reveals that the main signal at δ=0.93(7) mm/s is originating from trivalent Europium. Eu3[B3N6] showed no ESR signal in accordance with a non-magnetic (J=0) 7F0 ground state of the 4f6 configuration. Quantum chemical calculations find six electrons in the 4f subshell (4f6) of Eu indicating an oxidation state of +3. We present for the first time the vibrational spectra of a compound with cyclic trimer [B3N6]9- moieties. The Raman spectrum of Eu3[B3N6] is in good agreement with the predicted number of modes for the spectroscopically relevant cyclic [B3N6]9- group with D3h symmetry.

Tactile detection and two-point discrimination tests are commonly used in neurological examinations. However, questions remain about the influence of both body and patient characteristics on test thresholds. The left side of the body has sometimes been reported more tactilely sensitive than the right, and females are said to be more sensitive than males. We measured tactile detection and two-point discrimination thresholds on the finger, palm, and forehead of a large sample of young adults (N=171), examining laterality and sex differences, and the effects of body surface area (BSA) and body fat ratio (BFR). In tactile detection, there were no effects of laterality, BSA, or BFR, although females had lower thresholds than males. In two-point discrimination, there was an effect of laterality, with lower thresholds on the left side. This probably reflects hemispheric spatial processing differences. A significant BFR effect implies that subcutaneous fat affects skin deformation, but there were no effects of sex or BSA. The two-point discrimination findings differ in several respects from recent findings using grating orientation discriminations. A small positive correlation between the tasks, falling far short of test-retest reliabilities, indicates that they use largely disjoint but partially overlapping processes.

Gaps remain in our understanding of the contribution of bypass-related practices associated with red blood cell (RBC) transfusions after cardiac surgery. Variability exists in the reporting of bypass-related practices in the peer-reviewed literature. In an effort to create uniformity in reporting, a draft statement outlining proposed minimal criteria for reporting cardiopulmonary bypass (CPB)-related contributions (i.e., RBC data collection/documentation, clinical considerations for transfusions, equipment details, and clinical endpoints) was presented in conjunction with the American Society of ExtraCorporeal Technology’s (AmSECT’s) 2014 Quality and Outcomes Meeting (Baltimore, MD). Based on presentations and feedback from the conference, coauthors (n = 14) developed and subsequently voted on each proposed data element. Data elements receiving a total of ≤4 votes were dropped from further consideration, 5–9 votes were considered as “Recommended,” and elements receiving ≥10 votes were considered as “Mandatory.” A total of 52 elements were classified as mandatory, 16 recommended, and 14 dropped. There are 8 mandatory data elements for RBC data collection/documentation, 24 for clinical considerations for transfusions, 13 for equipment details, and 7 for clinical endpoints. We present 52 mandatory data elements reflecting CPB-related contributions to RBC transfusions. Consistency of such reporting would offer our community an increased opportunity to shed light on the relationship between intra-operative practices and RBC transfusions.

Robotics manipulators with structural flexibility provide an attractive alternative to rigid robotics manipulators for many of the new and evolving applications in robotics. In certain applications their use is unavoidable. The increased complexity in modeling and control of such manipulators is offset by desirable performance enhancements in some respects. In this paperthe single- link flexible robotics manipulator was designed and implemented from Perspex and designed with 0.5 m length , 0.02 m width and with 0.004 m thickness with mass located at the tip. There are four subsystems; motion, control, accelerometer and gyro and a host computer subsystem. The work principle of single-link robotics manipulator is the base servomotor. It rotates a hub with the link on it and measure the tip deflection. the deflection was measured for three cases without load, with 27.5 and with 59.4 gram at the end of the flexible link . During each of the above cases I rotated the base servo motor at an angular velocity equals to 90 deg./s using control card based on ATMEGA640 microcontroller. the deflection was measured for the three cases and the deflection measured by MMA7631 Accelerometer and Gyro . This accelerometer controlled by using MEGA Arduino board . Then the dataI collected collected from accelerometer and plot it using MATLAB software and compared between theoretical results obtained from MATLAB program that based on Lagrange equation of motion and experimental results and we found the maximum deflection occurred when V=180 deg/sec and tip load=59.5 gram. Keywords: Flexible Link Manipulator , Industrial robotics , Robotics Manipulator ,Beam Deflection.

This paper reviews the incidence of precedent-based practices in the Court of Justice of the European Union's (CJEU) case law on family reunification immigration. Particular attention is paid to the use of fundamental rights considerations, and the extent to which they guide the Court's judicial deliberations in this sovereignty-sensitive area of law. Our review of de facto 'precedents', and the extent to which they interact with fundamental rights-related concerns enables us to take stock of the long-term development of the Court's judicial authority. This longitudinal exercise also enables us to transcend the traditional dichotomy of 'the CJEU vis-a-vis the member states' that typically characterizes academic discussions on the role of the Court in processes of EU integration. The paper first considers the relevance of reviewing precedent in the context of the EU legal order. Next, we provide a novel dataset of the CJEU's jurisprudence in the area of family reunification immigration, as it evolved from 1974 up until today. We deal with the methodological implications of studying 'precedent' by presenting a model which numerically structures the incidence of precedent-based patterns. This numerical information allows us to organize our data for a subsequent qualitative in-depth analysis of those precedent-based patterns with the strongest discursive influence on the overall evolution of the case law. Our analysis demonstrates that fundamental rights-based arguments exerted a strong influence on the ideational course of the Court's jurisprudence in this area, albeit in a non-linear manner.

This paper deals with the determination of stresses and deflections of clamped circular diaphragm strengthened by one or two ring-shaped concentric ribs, under uniform static and dynamic pressures. The simulation has been achieved by using the well-known engineering software finite element package MSC/NASTRAN. As a design study, the effect of using a clamped ring, and the effect of using a ring-shaped rib on both surfaces of diaphragm instead of one, has been discussed in this work. To show the effectiveness of this study, results of this work have been compared with published data [1].In the conclusion, the authors underline the validity of the considered design study, and the optimization of strengthened diaphragms.

This paper presents a novel design of a fingertip mechanism for detecting the slippage of the grasped object under two different types of dynamic load. This design is to be used with an underactuated triple finger artificial hand based on pulleys-tendon mechanism and the grasped object is designed in a prism shape with three DC motors with unbalance rotating mass to generate the excitation in the object, these motors are distributed symmetrically on the faces of the object. This prism shaped object is connected to a rope type pulling system to force the object to slip under quasi-static load condition. The mathematical modeling has been derived for the proposed design to generate the signal of contact force components ratio through using the conventional sensors signals with the aid of matlab–simulink software. The experimental results are discussed in comparison with the physical aspect of slippage phenomenon and they show good agreement with the physical definition of the slippage phenomenon.

Normal function of the thyroid gland is the cornerstone of a child's mental development and physical growth. We describe a Finnish family, in which the diagnosis of three brothers became clear after investigations that lasted for more than 30 years. Two of the sons have already died. DNA analysis of the third one, a 16-year-old boy, revealed in exome sequencing of the complete X chromosome a mutation in the SLC16A2 gene, i.e. MCT8, coding for a thyroid hormone transport protein. Allan-Herndon-Dudley syndrome was thus shown to be the cause of multiple disabilities.

This paper represents a new concept to be used in journal bearings. A chamfer is machines circumferentially at both sides of the bearing inner surface, thus minimizing or almost preventing the side-leakage flow rate in lightly loaded journal bearings. This new concept eliminates the need for sealing and collecting this leakage. The circumferential flow is found to be sufficient to achieve cooling of the bearing. An investigation is carried out both theoretically and experimentally. Solutions are given for chamfered bearings with different length to diameter ratios, different chamfer length to bearing length ratios and finally different chamfer angles.

In this paper a moderate technique has been developed to improve an electromagnetic actuation principle for pumping systems, thus obtaining pulsating flow. This work consists of two parts, namely, a numerical part, in which ANSYS software is adopted to simulate the pumping process, while the experimental part consists of the fabrication and testing of the computer controlled electromagnetic pumping system. The objective of this work is to enhance both flow rate and outlet pressure. This was achieved via two main parameters, namely, the electromagnetic pulse duration and the width of each electromagnet. Results show that flow rate and outlet pressure increase with decreasing the pulse duration and with increasing each electromagnet width.Copyright © 2012 by ASME

Experimental and theoretical studies are presented dealing with the effect of solid additives in lubricating oils on the steady state performance of conical journal bearings using the mass transfer theory. Both studies showed an increase in the load capacity and the side-leakage flow, and a decrease in the friction coefficient with increasing percentage volume concentration of the solid additive. The great dependence of the bearing performance on the non-dimensional diffusion coefficient obtained gives support for the minimum friction coefficient obtained in the experimental results.

In two studies, we found that dot enumeration tasks resulted in shallow-sloped response time (RT) functions for displays of 1–4 dots and steep-sloped functions for displays of 5–8 dots, replicating results implicating subitizing and counting processes for low and high ranges of dots, respectively. Extracting number from a specific type of bar graph within the same numerical range produced a shallow-sloped but scallop-shaped RT function. Factor analysis confirmed two independent subranges for dots, but all bar graph values defined a unitary factor. Significantly, factor scores and asymmetries both showed correlations of bar graph recognition to dot subitizing but not to dot counting, strongly suggesting that subitizing was used in both enumeration of low numbers of dots and bar graph recognition. According to these results, subitizing appears to be a nonverbal process operating flexibly in either additive or subtractive fashion on analog quantities having spatial extent, a conclusion consistent with a fast-counting model of subitizing but not with other models of the subitizing process.

An analytical hydrodynamic model was developed to predict the behaviour of a simple two-phase (liquid-solid) lubricant. An experimental study was also carried out with such lubricants using conventional full-film hydrodynamic bearings. Both the analytical and the experimental results showed that the presence of suspended solid particles in a newtonian lubricant enhanced the load-carrying capacity and reduced friction.

Yttria stabilized zirconia powders were synthesized by the reverse microemulsion method. Powders were calcined from 600 degrees C to 1000 degrees C and sintered at 1450 degrees C. Crystalline properties and microstructure of samples were characterized by X-ray diffraction and scanning electron microscopy, respectively. Oxygen ionic conductivity was measured by electrochemical impedance spectroscopy. Sizes of yttria stabilized zirconia particles calcined at 1000 degrees C are lower than 100 nm, and approximately, 1 mu m grain was obtained after sintering at 1450 degrees C.

This paper provides an overview of the experimental work performed in our research group on the synthesis, spectroscopic investigation, and laser characterization of chromium-doped zinc selenide (Cr(2+):ZnSe). By using diffusion doping, 40 polycrystalline Cr(2+):ZnSe samples with ion concentration in the range of 0.8 x 10(18) to 66 x 10(18)ions/cm(3) were prepared. From the absorption data, temperature-dependent diffusion coefficient of chromium and losses at the lasing wavelength were measured. In luminescence measurements, the concentration dependence of the fluorescence lifetime and fluorescence quantum efficiency was determined. During continuous-wave operation, the optimum concentration for lasing was determined to be 8.5 x 10(18) ions/cm(3) at an incident pump power of 2.1 W for 1800-nm pumping. During gain switched operation, intra-cavity pumping with a 1570-nm optical parametric oscillator resulted in continuous tuning between 1880 and 3100 nm. By employing dispersion compensation with a MgF(2) prism pair, Kerrlens mode-locked operation was also demonstrated at 2420 nm, resulting in the generation of 95-fs pulses with an average output power of 40 mW and spectral bandwidth of 69 nm. The time-bandwidth product of the pulses was further measured to be 0.335 close to the expected value of 0.315 for sech(2) pulses., Network of Excellence in Micro-Optics (NEMO) - European Union; Scientific and Technological Research Council of Turkey (TÜBİTAK)