Fatty acid oxadiazoles as corrosion inhibitors for mild steel in formic acid

Selected oxadiazoles of fatty acids; namely 2-hepta decene-5-mercapto-1-oxa-3,4-diazole (HMOD); 2-undecane-5-mercapto-1-oxa-3,4-diazole (UMOD); and 2-decene-5-mercapto-1-oxa-3,4-diazole (DMOD), were synthesized. Their influence on the inhibition of corrosion of mild steel in 20% formic acid (HCOOH) was investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency of the compounds was found to vary with concentration, immersion time and temperature. All the compounds showed good inhibition efficiency (e _IE) in formic acid solution. Adsorption on mild steel obeyed the Langmuir adsorption isotherm. Potentiodynamic polarization revealed that all three inhibitors, HMOD, UMOD, and DMOD are mixed inhibitors. Electrochemical impedance spectroscopy was also used to investigate the inhibition mechanism.     

A framework to design 3D interaction assistance in constraints-based virtual environments

The equilibrium of complex systems often depends on a set of constraints. Thus, credible virtual reality modeling of these systems must respect these constraints, in particular for 3D interactions. In this paper, we propose a generic framework for designing assistance to 3D user interaction in constraints-based virtual environment that associates constraints, interaction tasks and assistance tools, such as virtual fixtures (VFs). This framework is applied to design assistance tools for molecular biology analysis. Evaluation shows that VF designed using our framework improve effectiveness of the manipulation task.     

Chemical disinfection of Legionella in hot water systems biofilm: a pilot-scale 1 study

Legionella bacteria encounter optimum growing conditions in hot water systems and cooling towers. A pilot-scale 1 unit was built in order to study the biofilm disinfection. It consisted of two identical loops, one used as a control and the other as a 'Test Loop'. A combination of a bio-detergent and a biocide (hydrogen peroxide + peracetic acid) was applied in the Test Loop three times under the same conditions at 100 and 1,000 mg/L with a contact time of 24 and 3-6 hours, respectively. Each treatment test was preceded by a three week period of biofilm re-colonization. Initial concentrations of culturable Legionella into biofilm were close to 10(3) CFU/cm2. Results showed that culturable Legionella spp. in biofilm were no longer detectable three days following each treatment. evertheless, initial Legionella spp. concentrations were recovered 7 days after the treatments (in two cases). Before the tests, Legionella spp. and L. pneumophila PCR counts were both about 10(4) GU/cm2 in biofilm and they both decreased by 1 to 2 log units 72 hours after each treatment. The three tests had a good but transient efficiency on Legionella disinfection in biofilm.     

Study of geophysical parameters associated with the Orissa super cyclone using active and passive microwave remote sensing measurements

A detailed study of the Orissa super cyclone over the Bay of Bengal from 25 to 29 October 1999 has been carried out using various spaceborne sensors, namely VHRR, SSM/I, TMI, MSMR, TOPEX‐RA and TMR. The raining areas are delineated using dual frequency TOPEX altimeter and coaligned three‐frequency TOPEX microwave radiometer (TMR) in addition to DMSP SSM/I, TRMM TMI and IRS‐P4 MSMR. Various oceanic parameters like rain rate (RR), cloud liquid water (CLW), integrated water vapour (IWV), ocean surface wind speed (OWS), and wave conditions on the ocean surface near and within the cyclonic vicinity were studied. This paper has two innovative aspects: (1) it indirectly validates the empirically developed MSMR algorithms for water vapour and wind speed under moderate cloud water conditions, and (2) it makes non‐conventional use of TOPEX altimeter and TMR, especially for rain rate and cloud liquid water over the cyclone. Results and significance of the synergistic measurements from various active and passive microwave and infrared observations from satellites have been discussed. The combined capabilities of these measurements portray the several important features associated with cyclones in a more informative way than any individual satellite component.     

Broadcasting on Networks of Workstations

Broadcasting and multicasting are fundamental operations. In this work we develop algorithms for performing broadcast and multicast in clusters of workstations. In this model, sending a message to a machine in the same cluster takes 1 time unit, and sending a message to a machine in a different cluster takes C(≥1) time units. The clusters may have arbitrary sizes. Lowekamp and Beguelin proposed heuristics for this model, but their algorithms may produce broadcast times that are arbitrarily worse than optimal. We develop the first constant factor approximation algorithms for this model. Algorithm LCF (Largest Cluster First) for the basic model is simple, efficient and has a worst case approximation guarantee of 2. We then extend these models to more complex models where we remove the assumption that an unbounded amount of communication may happen using the global network. The algorithms for these models build on the LCF method developed for the basic problem. Finally, we develop broadcasting algorithms for the postal model where the sending node does not block for C time units when the message is in transit.     

Reconstruction of cylinder pressure for SI engine using recurrent neural network

Model predictive control (MPC) frequently uses online identification to overcome model mismatch. However, repeated online identification does not suit the real-time controller, due to its heavy computational burden. This work presents a computationally efficient constrained MPC scheme using nonlinear prediction and online linearization based on neural models for controlling air–fuel ratio of spark ignition engine to its stoichiometric value. The neural model for AFR identification has been trained offline. The model mismatch is taken care of by incorporating a PID feedback correction scheme. Quadratic programming using active set method has been applied for nonlinear optimization. The control scheme has been tested on mean value engine model simulations. It has been shown that neural predictive control with online linearization using PID feedback correction gives satisfactory performance and also adapts to the change in engine systems very quickly.     

From the Test Benches to the First Prototype of the muFly Micro Helicopter

The goal of the European project muFly is to build a fully autonomous micro helicopter, which is comparable to a small bird in size and mass. The rigorous size and mass constraints infer various problems related to energy efficiency, flight stability and overall system design. In this research, aerodynamics and flight dynamics are investigated experimentally to gather information for the design of the helicopter’s propulsion group and steering system. Several test benches are designed and built for these investigations. A coaxial rotor test bench is used to measure the thrust and drag torque of different rotor blade designs. The effects of cyclic pitching of the swash plate and the passive stabilizer bar are studied on a test bench measuring rotor forces and moments with a 6–axis force sensor. The gathered knowledge is used to design a first prototype of the muFly helicopter. The prototype is described in terms of rotor configuration, structure, actuator and sensor selection according to the project demands, and a first version of the helicopter is shown. As a safety measure for the flight tests and to analyze the helicopter dynamics, a 6DoF vehicle test bench for tethered helicopter flight is used.     

3D object recognition technique using multiple 2D views for Arabic sign language

Some objects in specific poses cannot be distinguished using a single view. A model is proposed and developed for 3D object recognition based on multiple-views; it was applied on hand postures recognition. A pulse-coupled neural network is used to generate features vector for single view. Two views with different view angles are used; each view generates its features’ vector. The two 2D-vectors are then linearly combined into one 3D vector. The hand postures are then combined to construct a dynamic gesture (word). The reconstruction is performed using best-match search algorithm. The experiment was conducted on 50 words and the result was 96% recognition accuracy confirming objects dataset offline extendibility.     

A Simplified Analytical Model for a Current-Fed Force-Commutated Converter

The current-fed force-commutated converter (CFFCC) has recently received considerable attention in the electric drives area. It may also have future power conversion applications in electric utility systems. In order to facilitate the study of CFFCC systems a simplified converter model is developed and investigated in this paper. The simplified model is a quasi-steady-state representation based on an average value and fundamental frequency formulation of the circuit equations. Comparisons with exact circuit solutions and a detailed analog computer simulation demonstrate the validity of the simplified model under steady-state and transient conditions.