Force sensor based on discrete optoelectronic components and compliant frames

In this paper, a novel force sensor based on commercial discrete optoelectronic components mounted on a compliant frame is described. The compliant frame has been designed through an optimization procedure to achieve a desired relation between the applied force and the angular displacement of the optical axes of the optoelectronic components. The narrow-angle characteristics of Light Emitting Diode (LED) and PhotoDetector (PD) couples have been exploited for the generation of a signal proportional to very limited deformation of the compliant frame caused by the external traction force. This sensor is suitable for applications in the field of tendon driven robots, and in particular the use of this sensor for the measurement of the actuator side tendon force in a robotic hand is reported. The design procedure of the sensor is presented together with the sensor prototype, the experimental verification of the calibration curve and of the frame deformation and the testing in a force feedback control system. The main advantages of this sensor are the simplified conditioning electronics, the very high noise-to-signal ratio and the immunity to electromagnetic fields.     

Selective doping of silicon by rapid thermal and laser assisted processes

The selective doping technique, made by the combination of spin-on dopant (SOD) source deposition, rapid thermal annealing (RTA) and laser treatments is proposed as an innovative process for large area devices, like silicon solar cells.Rapid thermal diffusion (RTD) is first carried out from phosphorus SOD layers to form a lightly doped junction followed by pulsed laser irradiation to induce overdoping in selectively chosen regions.Here we present extensive study on the dependence of selective doping efficiency through different working variables, such as dopant source dilution, diffusion temperature and time for RTPs, and power and translation velocity for lasers. Electrical and structural characterizations have been performed by using several techniques: SIMS, stripping-Hall, four-point probe resistivity, SEM and TEM analysis.The combined use of these processes has been applied to the realization of selective emitter structures for silicon solar cells.     

Designing and upgrading model of pre-denitrification systems

This paper reports a three-substrate steady-state integrated model, whose unknowns are expressed in explicit terms once concentrations of nitrogen compounds in the effluent flow are fixed. The model can be applied both to design and to upgrade wastewater treatment plants. The model is also able to evaluate the flexibility of existing wastewater treatment plants, which represents the capacity of the system to operate under different working conditions caused by increases in influent load or reductions in effluent quality standards. In this case the admissible variation of influent load or effluent concentration can be measured using suitable dimensionless flexibility indexes.List of symbols Q influent flow [L³ T^–1] - R₁ sludge recycle flow ratio - R₂ aerated mixed liquor recycle flow ratio - V_D denitrification reactor volume [L³] - V_N nitrification reactor volume [L³] - S biodegradable organic substrate concentration [M L^–3] - N-NH₄ ammonia nitrogen concentration [M L^–3] - N-NO₃ nitrate nitrogen concentration [M L^–3] - N_tot total nitrogen concentration [M L^–3] - O₂ oxygen concentration in the nitrification reactor [M L^–3] - X_H heterotrophic biomass concentration [M L^–3] - X_AUT autotrophic biomass concentration [M L^–3] - maximum removal rate of biodegradable organic substrate for an assigned value of temperature [T^–1] - maximum removal rate of nitrate for an assigned value of temperature [T^–1] - maximum removal rate of ammonia nitrogen for assigned values of pH and temperature [T^–1] - _S removal rate of biodegradable organic substrate [T^–1] - _D removal rate of nitrate [T^–1] - _N removal rate of ammonia nitrogen [T^–1] - K_S saturation coefficient for biodegradable organic substrate [M L^–3] - K_D saturation coefficient for nitrate [M L^–3] - K_SD saturation coefficient for organic substrate in the denitrification kinetic [M L^–3] - K_N saturation coefficient for ammonia nitrogen [M L^–3] - saturation coefficient for oxygen [M L^–3] - Y_H yield coefficient for heterotrophic microorganisms in the biodegradable organic substrate removal process - Y_D yield coefficient for heterotrophic microorganisms in the nitrate nitrogen removal process - Y_AUT yield coefficient for autotrophic microorganisms in the ammonia nitrogen removal process - (X_H)_r heterotrophic biomass concentration in the recycle sludge [M L^–3] - (X_AUT)_r autotrophic biomass concentration in the recycle sludge [M L^–3] - biodegradable organic mass consumption for unitary nitrate nitrogen mass reduction in the denitrification reactor - nitrogen consumption in the biodegradable organic oxidation process by mean of heterotrophic biomass     

Numerical models for the simulation of currents in naples gulf

Two numerical hydrodynamic models of wind-driven water circulation in a basin are considered.Some results from their application to the Gulf of Naples are described.     

Selective emitters in buried contact silicon solar cells: Some low-cost solutions

We present the results of our study on the formation of selective emitter structures in buried contact cells. In particular, our attention has been focused on those processes that seem to be scalable to industry. To this aim, specific dopant sources and fabrication steps have been selected.Two different kinds of dopants have been considered: the P-doped SOD and the screen-printed dopant paste. For both sources we have tested the feasibility of the selective diffusion formation in a single step, together with the application of suitable techniques to get selective doping, such as laser enhanced diffusion into the grooves, or selective deposition of screen printed paste in buried grid pattern. SEM and SEM-EBIC analyses have been used to investigate the occurrence of doping. Several batches of buried contact, mechanically grooved cells have prepared and tested.     

On boundary conditions for the numerical solution of fluid dynamic problems

The stability and accuracy of various boundary treatments are analyzed for a finite difference scheme proposed by the author for the numerical solution of problems in fluid dynamics. The theory of Gustafsson, Kreiss and Sundstrom is used to establish stability and the theory of Skollermo is used to compare the accuracy of the various methods. The accuracy preductions are compared with computed results.     

Estimation of biodegradation kinetic constants for aromatic derivates through aerobic batch experiments.

The kinetics of aerobic biodegradation were studied for 20 aromatic species by using sludges taken from a municipal sewage treatment plant. The reproducibility of the results is tested with respect to the period of collection of the sludges and the wastewater treatment plant where they were taken. The comparison of kinetic constants estimated for investigated chemicals allows evaluation of the effect on the reactivity due to the presence of single groups (i.e. -OH, -CH3, -Cl, -NO2) into the aromatic structures. The search for easy structure-reactivity relations is also attempted by using some group contributing methods.     

Polymerization in magnetic field: XVIII. Influence of surfactant nature on the synthesis and thermal properties of poly(methyl methacrylate) and poly[(methyl methacrylate)‐co‐(epoxypropyl methacrylate)]

BACKGROUND: The possibility to use β‐cyclodextrin as biodegradable tensioactive and an electromagnetic field in order to improve the kinetic parameters of radical emulsion polymerization is of interest. Thus, the influence of different surfactants—sodium lauryl sulfate (SLS) and β‐cyclodextrin (CD)—on the pathway of emulsion polymerization of methyl methacrylate (MMA) and emulsion copolymerization of MMA with 2,3‐epoxypropyl methacrylate (GMA) performed with or without the presence of a continuous electromagnetic field (MF) was studied. RESULTS: The presence of the MF leads to a considerable increase of the conversion during the first part of the reaction if the classic surfactant (SLS) is used. The reactions performed without MF and with CD exhibit a decrease of the conversion and of the polymerization rate as compared with the variants using SLS. The swelling rate and the maximum degree of swelling vary with the surfactant nature and with the reaction conditions and MF presence. Data from thermogravimetry and differential scanning calorimetry evidence the dependences between the polymer characteristics and the preparation conditions. CONCLUSION: This research underlines the coupling possibilities of the influence of a MF—growth of the reaction rate and conversion explained through radical pairs mechanism—with a combination of the ‘cage’ effect and ‘conformational control’ afforded by CD. The presence of MF and CD during the syntheses leads to an increase of T_g and an increase of PMMA and P(MMA‐co‐GMA) thermal stability. Copyright © 2007 Society of Chemical Industry     

Annealing of solution-grown single crystals of ethylene-butadiene copolymers

The annealing behaviour of solution-grown single crystals of ethylene-butadiene copolymers of differing compositions is examined and compared with that of linear polyethylene. From the plot of melting temperature against the reciprocal of the long spacing features such as the equilibrium melting point T⁰_m and the free energy of folding σ_e have been calculated. Both σ_e and T⁰_m increase with almost a linear trend with the percentage of butadiene along the chain. It is concluded that the surface of single crystals of ethylene-butadiene copolymers is rougher than that of linear polyethylene.