Surface Activation of Diamond Particles in the Process of Chemical Coppering

The effect of the composition of sensitizing–activating solutions on the activation efficiency and the chemical coppering of diamond powders is studied. The results demonstrate that stabilizing additives improve the stability of the solutions, influence the average coppering rate, and play a key role in determining the morphology and quality of the resultant coatings. The most effective stabilizing additive is synthamid-10, which ensures the deposition of high-quality copper coatings.     

An integrated system to remote monitor and control anaerobic wastewater treatment plants through the internet.

The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem.     

Sensory analysis of polystyrene packaging material taint in cocoa powder for drinks and chocolate flakes

Polystyrene packaging material taint was sensorily evaluated in cocoa powder for drinks and chocolate flakes using short-cut signal detection measures on differences between control and test samples and on recognition of styrene. No differences were observed in cocoa powder for drinks and plain chocolate flakes treated with 0.5 dm2 polystyrene of 1 mm thickness. However, differences were detected in milk chocolate flakes and plain chocolate flakes, which were in contact with a larger area or thicker polystyrene packaging material. The latter results were confirmed by the styrene recognition test, so polystyrene is a potential source of off-flavour for chocolate products. The amount of residual styrene in the polystyrene used was about 320 ppm, while the amounts of styrene ranged from 7 to 132 ppb in cocoa drinks and from 414 to 1447 ppb in chocolate flakes.     

Noise–Power Optimization of Incremental Data Converters

Incremental data converters (IDCs) are useful in instrumentation and measurement applications, where low-frequency analog signals need to be converted into digital form with high accuracy and low power dissipation. They are particularly well suited for applications where a single analog-digital converter is multiplexed between many channels. This paper proposes an exact design methodology for IDCs, which optimizes the signal-to-noise ratio of the converter under practical design constraints. The process also allows the designer to apportion the noise budget in an arbitrary manner between thermal and quantization noise. The design process is illustrated by an example which describes the optimization of a third-order multiplexed IDC.     

Cost-Efficient SHA Hardware Accelerators

This paper presents a new set of techniques for hardware implementations of Secure Hash Algorithm (SHA) hash functions. These techniques consist mostly in operation rescheduling and hardware reutilization, therefore, significantly decreasing the critical path and required area. Throughputs from 1.3 Gbit/s to 1.8 Gbit/s were obtained for the SHA implementations on a Xilinx VIRTEX II Pro. Compared to commercial cores and previously published research, these figures correspond to an improvement in throughput/slice in the range of 29% to 59% for SHA-1 and 54% to 100% for SHA-2. Experimental results on hybrid hardware/software implementations of the SHA cores, have shown speedups up to 150 times for the proposed cores, compared to pure software implementations.      

Enhancing Chaotic Communication Performances by Manchester Coding

A numerical analysis of an optical chaotic transmission system, based on the synchronization of two chaotic lasers, in a master-slave closed loop configuration is presented. At the transmitter, the master chaotic wave is superposed on the information message; at the receiver, the message is recovered by subtracting the synchronized slave chaotic wave from the received signal. The performances are analyzed in terms of the Q-factor, considering two different message modulation formats: the nonreturn-to-zero and the Manchester coding. The Manchester coding shows enhanced performances due to the shift of the signal spectrum to higher frequencies.     

Mechanisms of rectification of a high-frequency signal by a field-effect heterotransistor with a short channel

The effect of nonlinearity of the drift velocity of free charge carriers and the gradient-and concentration-related nonlinearities in the power-voltage sensitivity of a field-effect transistor with a short channel are studied theoretically. Theoretical results are compared with experimental data on the detection of terahertz radiation. It follows from the comparison that, in order to gain deeper insight into observed systematic features in the analysis of high-frequency characteristics of the transistor, one has to take into account some other mechanisms of the current nonlinearity, in addition to the plasma-related nonlinearity.     

Investigation into Polarization of Unloaded and Loaded Microstrip Square-Ring Antennas

The polarization characteristic of unloaded and loaded square-ring microstrip antennas is investigated. Several different loading types like single-stub, dual-stub, notch, gap and shorting-pin are considered and their effects are studied. Loading enables feeding using a 50-Omega probe. The simulation and measurement results show that the loading techniques excite a loaded TMy ₁₁ mode that is orthogonal to the unloaded TMx ₁₁ mode. This indicates that by loading the ring antenna its polarization can be switched adaptively. However, the purity of the loaded and unloaded modes depends on the loading type. For some loading types like gap and shorting-pin, the excitation of the unloaded mode seems negligible, in comparison to the loadings by stub and notch. For the stub and notch loaded antennas the unloaded mode is also present, and its excitation efficiency is frequency dependent. Thus, their polarization plane, which is due to both loaded TMy ₁₁ and unloaded TMx ₁₁ modes, also becomes frequency dependant. The results of this investigation can be useful in selecting the loading methods for high-impedance microstrip ring antennas, and control of their impedance and polarization. The knowledge of the antenna polarization is essential in communications, and its dependence on the loading type can be used as an important parameter in design of adaptive antennas and sensors.     

Online and Offline Rotary Regression Analysis of Torque Estimator for Switched Reluctance Motor Drives

A new torque estimator for switched reluctance motor (SRM) drives based on 2-D rotary regression analysis is presented in this paper. The proposed torque estimator is composed of a bicubic regressive polynomial as a function of rotor position and input current. The regressive coefficients can be computed offline or online from the torque characteristics acquired either experimentally or from numerical computation. Furthermore, a torque estimation method by taking mutual coupling into consideration is proposed. It can be seen that the estimated and experimentally obtained self-coupling and mutual-coupling torque characteristics are in good agreement with each other. In addition, the dynamic torque waveforms with and without the mutual coupling, estimated by the proposed estimator, are found to be virtually the same as those obtained from the bicubic spline interpolation for SRM drives with single-pulse voltage, hysteresis current chopping, as well as with voltage pulse width modulation control. The success of all the case studies being reported is a good validation of the usefulness and accuracy of the proposed real-time torque estimator that, as described in this paper, can be used to quickly estimate the instantaneous output torque of SRM drives.