Ivan Popovic

Dynamic Voltage-Current Characteristics of Unipolar Pulse Glow Discharge

Introduction of pulse plasma power supply is one of the major contributions to plasma surface engineering. The voltage and current waveforms of nitrogen and nitrogen/hydrogen glow discharges in the vacuum total pressure range from 0.1 to 15 mbar were recorded and analyzed concerning the shape, typical operating values and the influence of surface treatment process parameters. It was found that the waveform shape of the voltage and current contains information on pulse generator output parameters and vacuum system properties during normal glow, hollow cathode discharge and arcing. We have also performed the scoping of dynamic parameters and static characteristic, in order to obtain information for the generator and chamber modeling, to be used in a future plasma materials treatment processes control. The influence of process parameters such as total pressure, cathode temperature and biasing voltage on current-voltage characteristics was also considered.

Virtual transducers in service-oriented smart transducers network

Implementation of the Service Oriented Architecture (SOA) in the IEEE 1451 smart transducers network enables efficient data exchange and simple integration of new devices. The existing IEEE 1451 Web service implementation prototypes are normally developed using a general purpose platform. This paper presents a model of service-oriented network relying on the embedded smart transducers with integrated IEEE 1451 Web services. New entities such as algorithms and data displays are integrated in the network in a form of virtual transducers, and they also act as service providers. Network configuration and data exchange are controlled by the central server, while support for the configuration of individual devices is provided by the service-oriented content modification of Transducer Electronic Data Sheets (TEDS). A configuration example is demonstrated in a form of the service-oriented display presenting the same set of measured data using three different instances of the format-customized presentation TEDS.

Service-oriented sensor network for environmental monitoring

This paper describes a service-oriented architecture implementation in the smart transducers network for environmental monitoring. Web service provider is defined using Web Service Description Language (WSDL) and implemented on the ARM microcontroller that is Internet enabled. Given solution represents an advanced Smart Transducer Web Services (STWS) concept realization, which typically requires a general purpose computer. For testing purposes a client application is developed, communication with server is demonstrated, and sensor measurements are shown. Described services are useful for the distributed sensor application development where efficient access to the IEEE 1451.0 physical devices is needed.

Frequency scaling for low-power embedded system

In this paper concept for dynamic frequency scaling algorithm implementation for low-power embedded systems is proposed. The algorithm is based on systems power consumption analysis in different operating modes. Depending on clock module settings, parameters for minimal power consumption are found. In this paper concept of a software module that would allow automatic frequency control in order to reduce power consumption and sastisfy timing constraints of program tasks is proposed.

Structural, Mechanical and Optical Properties of TiN and (Ti,AI)N Coatings

The TiN and (Ti,Al)N coatings were deposited onto HSS substrates of different surface roughness in a double magnetron deposition system in order to investigate their optical and some mechanical properties. The spectral reflectivity of the samples was measured in the range from 300-2500 nm, and the coating optical properties were modeled by the screened Drude model and semiclassical model which includes both the intraband and interband electron transitions. It has been demonstrated that the optical reflectivity of the (Ti,Al)N coating may successfully be modeled by the semiclassical relations. Mechanical and structural properties of coatings were investigated by Vickers microhardness measurement, calotest, scratch test, and SEM analysis. One wavelength ellipsometry was applied to measure the optical constants of the TiN coating.

Service-oriented implementation model for smart transducers network

This paper describes a new implementation model for the service-oriented smart transducers network based on the IEEE 1451 Web Services. The model enables simple service dislocation and addition of new functionalities in Service Oriented Architecture (SOA) network. Presented architectural organization supports new service-oriented network entities in addition to standard IEEE 1451 smart transducers. The entities such as particular transducer services and functionalities, processing applications and algorithms, and set of I/O devices are supported in the form of service providers managed by a central server. The entities are modeled as virtual transducers incorporated in the service-oriented network, and analysis on how this architectural change affects the smart transducer design constraints is given. The case study of a smart transducer network design in form of automated configuration and data exchange between ARM-based smart transducer interface module, central server and dislocated virtual transducer is presented. Implementation model for service-oriented smart transducers network is developed.IEEE 1451 Web services are implemented on embedded platform.Data processing applications are presented in form of Web service providers.Central server support for network configuration and data exchange is provided.

Multiprocessor architecture of smart transducer module

This paper presents concept of smart transducer module implementation on heteregonus multiprocessor platform, enabling design of low power, modular, and flexible embedded systems. Design concept rely on communication task embedded in each microcontroler in the system and connected to inter processor communication bus. Concept of implementation and communication protocol are explained in details.

Influence of Time Domain Parameters on Unipolar Pulse Plasma System Transition State

Plasma surface treatment of large components like wind turbine parts require large vacuum vessels and high power supplies. Our analysis of the electrical response of a unipolar pulse plasma system has shown that the transition of the gas discharge to the stationary state is related not only to the gas discharge properties but also to switching circuit and interconnection line characteristics. As a consequence the same power supply connected to different working chambers may perform in different way. We found that the gas discharge transition state depends on the switching transistor properties, gas mixture, operating pressure, cathode temperature, cathode physical properties, etc. The time domain parameters are in relation with the gas discharge equivalent dynamic resistance, equivalent capacitance, parasitic interconnection inductance, etc. Pulse plasma provides reliable operation but also a new type of unhomogeneity due to the gas discharge periodical transition to the stationary state. The designs of a pulse power supply and its connection to the process chamber are found of importance for homogeneous surface treatment in processes like plasma nitriding. From modeling and simulation of a pulse plasma system based on the measurements, the important electrical parameters of the system were obtained.

Electrical and Optical Signal Analysis of Pulse Powered Glow Discharge System

The electrical and optical signal waveforms of nitrogen/hydrogen glow discharges used for plasma nitriding process were recorded and analyzed. The shape of the discharge voltage and current signals is dependent on the process parameters, pulse plasma generator properties and cathode geometry. It has been found that the dynamic parameters of the electrical signal waveforms contain information related to the charged particles generation, which is relevant to the homogeneity of different gas discharge surface treatment processes. On the other hand, information related to the active species generation responsible for thermochemical processes at the cathode surface is stored in the optical emission waveforms. The generation and quenching of the active ingredients during the voltage pulses switch on and off influence the shape of the emitted light signals. From the optical signal analysis it was found that the thermochemical processes are influenced by the plasma generator properties such as pulse duty cycle, frequency, applied discharge voltage level and process parameters like working gas composition, operating temperature and pressure.

Methodology for detection of photovoltaic systems underperformance operation based on the correlation of irradiance estimates of neighboring systems

The methodology for the detection of under-performance operation of neighbouring photovoltaic systems is presented. The methodology compares the estimations of the total horizontal solar irradiance...