Use of a Reflectance Spectroscopy Accessory for Optical Characterization of ZnO-Bi(2)O(3)-TiO(2) Ceramics

The optical band-gap energy (E(g)) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. E(g) of the ceramic ZnO + xBi(2)O(3) + xTiO(2), where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. E(g) was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.     

Investigation of electromagnetic shielding effectiveness of needle punched nonwoven fabrics with staple polypropylene and carbon fibres

Conductive needle punched nonwoven fabrics are developed from staple polypropylene (PP) and varying weight fractions (10, 20 and 30 wt.%) of staple carbon fibres. A fibrous webs of staple PP and carbon fibres were formed at a wool-type carding machine, and these webs subsequently bonded on needle punching machine with 132 punches/cm² and 13.5 mm needle penetration depth. The electromagnetic shielding effectiveness (EMSE), absorption and reflection characteristics of as-produced needle punched nonwoven fabrics were determined using a network analyser as specified in ASTM D4935-10 in the frequency range 15–3000 MHz. The surface resistivity measurements were carried out in accordance with ASTM D 257-07 standard. These results indicate that the EMSE values increase incrementally with frequency in the 15–3000 MHz range. The nonwoven sample with 30 wt.% carbon fibre showed the lowest surface resistivity of 3.348 kΩ and corresponding highest EMSE of ~42.1 dB in the 3000 MHz frequency range. In comparison, the highest EMSE values from 10 to 20 wt.% staple carbon fibre were found to be 15.6 and 32.2 dB in the 3000 MHz frequency, respectively. It was observed that the absorbance and reflectance curves of each nonwoven fabric move at opposite directions to each other. It was found that as the amount of carbon fibre in the nonwoven fabric increases, absorbance values decrease, but reflectance values increase. The resultant nonwoven fabric samples are expected to be used as garment interlining after thermal bonding and wall interlayer in the future.     

A statistical tolerance analysis approach for over-constrained mechanism based on optimization and Monte Carlo simulation

Tolerancing decisions can profoundly impact the quality and cost of the mechanism. To evaluate the impact of tolerance on mechanism quality, designers need to simulate the influences of tolerances with respect to the functional requirements. This paper proposes a mathematical formulation of tolerance analysis which integrates the notion of quantifier: “For allacceptable deviations (deviations which are inside tolerances),there existsa gap configurationsuch asthe assembly requirements and the behavior constraints are verified” & “For allacceptable deviations (deviations which are inside tolerances), andfor alladmissible gap configurations, the assembly and functional requirements and the behavior constraints are verified”. The quantifiers provide a univocal expression of the condition corresponding to a geometrical product requirement. This opens a wide area for research in tolerance analysis. To solve the mechanical problem, an approach based on optimization is proposed. Monte Carlo simulation is implemented for the statistical analysis. The proposed approach is tested on an over-constrained mechanism.     

Dissolution kinetics of an oxidized copper ore in water saturated by chlorine

Dissolution kinetics of an oxidized copper ore (mainly malachite) in water saturated by Cl₂ has been studied. The effect of particle size, flow rate of the gas, temperature and solid-liquid ratio has been determined. The dissolution rate increased with decrease in particle size and solid-liquid ratio and with increase in the gas flow rate and temperature. It has been found that the dissolution proceeds in two stages and is controlled by diffusion through the ash layer in each stage. The activation energies for the first and second stage are 27.15 and 20.21 kJ mol^?1, respectively.     

HR 720, a novel angiotensin receptor antagonist inhibits the angiotensin II-induced trophic effects, fibronectin release and fibronectin-EIIIA+ expression in rat aortic vascular smooth muscle cells in vitro

The aim of this study was to evaluate the direct trophic effects of angiotensin II (AII) on rat vascular smooth muscle cells obtained from a single cellular isolate. Cell volume, protein synthesis, fibronectin (FN) release and FN-EIIIA+ mRNA isoform expression were analyzed in parallel. The effects of HR 720, a novel AT1 angiotensin receptor antagonist with some AT2 receptor affinity, were compared with those of selective AT1 antagonist EXP 3174. Both HR 720 and EXP 3174 inhibited in a concentration-dependent manner the maximum increase in cell volume induced by 10(-9) M Sar1-All (IC50 = 0.49 x 10(-9) M and 0.79 x 10(-9) M, respectively). Maximum [3H]leucine incorporation was also achieved at 10(-9) M All. HR 720 blocked the increase in protein synthesis with potency similar to EXP 3174; the respective IC50 values were 1.04 x 10(-9) M and 1.36 x 10(-9) M. All dose-dependently increased FN release, which was also equally inhibited by about 50% with both compounds at 10(-6) M. Furthermore, All enhanced FN-EIIIA+ mRNA in rat vascular smooth muscle cells (VSMC), which indicated a modulation of FN isoform expression which was inhibited by angiotensin II antagonists. In conclusion, All induced parallel and concentration-dependent increases in cell volume, protein synthesis, FN release and FN-EIIIA+ mRNA expression in vascular smooth muscle cells. These effects appeared to be essentially mediated by AT1 receptor stimulation as indicated by the equal inhibitory effects of HR 720 and EXP 3174.     

System Reliability with Multiple Failure Modes and Time Scales

Lifetime of some systems can be measured based on multiple time scales. For instance, the lifetime of an airplane may be affected by its mileage or number of landings. Furthermore, most systems are exposed to competing risks. In this regard, time scales can accelerate the failure mechanism of these systems. In this paper, the behavior of systems is investigated under competing risks and multiple time scales. The time scales follow independent Poisson processes. As it is not straight forward obtaining closed‐form relations for the system reliability, we have provided a parametric upper bound. Also, the upper bound can be tightened by considering an error function. The error function can be built by regression on a sample containing real values of system reliability for given time units. Performance of the upper bound is studied in two numerical examples and a case study. Results show that the obtained upper bound is very tight. Copyright © 2015 John Wiley & Sons, Ltd.     

Input Displacement Neuro-fuzzy Control and Object Recognition by Compliant Multi-fingered Passively Adaptive Robotic Gripper

The requirement for new flexible adaptive grippers is the ability to detect and recognize objects in their environments. It is known that robotic manipulators are highly nonlinear systems, and an accurate mathematical model is difficult to obtain, thus making it difficult make decision strategies using conventional techniques. Here, an adaptive neuro fuzzy inference system (ANFIS) for controlling input displacement and object recognition of a new adaptive compliant gripper is presented. The grasping function of the proposed adaptive multi-fingered gripper relies on the physical contact of the finger with an object. This design of the each finger has embedded sensors as part of its structure. The use of embedded sensors in a robot gripper gives the control system the ability to control input displacement of the gripper and to recognize particular shapes of the grasping objects. Fuzzy based controllers develop a control signal according to grasping object shape which yields on the firing of the rule base. The selection of the proper rule base depending on the situation can be achieved by using an ANFIS strategy, which becomes an integrated method of approach for the control purposes. In the designed ANFIS scheme, neural network techniques are used to select a proper rule base, which is achieved using the back propagation algorithm. The simulation results presented in this paper show the effectiveness of the developed method.     

Bit Impact Factor: Towards making fair vulnerability comparison

Reliability is becoming a major design concern in contemporary microprocessors since soft error rate is increasing due to technology scaling. Therefore, design time system vulnerability estimation is of paramount importance. Architectural Vulnerability Factor (AVF) is an early vulnerability estimation methodology. However, AVF considers that the value of a bit in a clock cycle is either required for Architecturally Correct Execution (i.e. ACE-bit) or not (i.e. unACE-bit); therefore, AVF cannot distinguish the vulnerability impact level of an ACE-bit. In this study, we present a new dimension which takes into account the vulnerability impact level of a bit. We introduce Bit Impact Factor metric which, we believe, will be helpful for extending AVF evaluation to provide a more accurate vulnerability analysis.     

OPTIMIZATION OF LEACHING OF COPPER FROM OXIDIZED COPPER ORE IN NH3-(NH4)2SO4 MEDIUM

Studies were carried out for selective leaching of Cu with simultaneous avoidance of iron dissolution during leaching of oxidized copper ore in an aqueous NH₃-(NH₄)₂SO₄ system. The effects of leaching parameters, such as ammonia concentration, ammonium sulphate concentration, leaching time, and solid-to-liquid ratio, were investigated on leaching of copper. A 2ⁿ factorial experimental design method in the dissolution experiments was used. In addition, the “Steepest Ascent” method was also applied to determine the optimum leaching conditions. It was observed that the most effective parameters on the leaching of copper were ammonia concentration and leaching time. Only 0.17% of iron in ore was dissolved in ammonia and ammonium sulphate medium. The optimum conditions established for maximum copper recovery were: ammonia concentration 2.824 mol L^-1, ammonium sulphate concentration 0.236 mol L^-1, solid-to-liquid ratio 0.167 g mL^-1, leaching time 2 h. Fixed parameters chosen in the experiments were: room temperature, average particle size 2.8 mm, stirring speed 500 rpm. Under the optimum conditions established for maximum copper recovery, the percentage of leached copper was 98.87.