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Open access

V. Lakov, E. Chorukova and I. Simeonov

Abstract

A mathematical model of a cascade of two continuously stirred anaerobic bioreactors is presented in this paper and the extremum seeking control is applied on it. The dilution rate of the first bioreactor is chosen as control action and the joint biogas flow rate both bioreactors is the measured output to be maximized. The concentration of inlet organics is accepted as the disturbance. The correction of the working volume of the second bioreactor is studied as the inner loop of the cascade control system. The outer control loop is represented by the extremum seeking controller, which finds the optimum control action and reacts to the disturbance. Computer simulation studies show the feasibility of this scheme.

Open access

V. Dimitrov

Abstract

Systems for remote monitoring and control on energy consumption, efficiency and proper operation of the controlled objects are very often used in different spheres of industry, building automation, electricity distribution network etc. Various types of intelligent energy meters, PLCs and other control devices are involved in such systems. On the other hand, soft starters are widely used in industry and building automation for control on asynchronous drives when the speed regulation is not a mandatory requirement. They are cheaper than inverters and frequency converters and allow temporal reduction of the torque and current surge during start-up, as well as smooth deceleration. This is why the study of the principles of operation and setting up of intelligent energy meters, soft starters and PLC is very important. A laboratory system has been designed and built. An asynchronous motor is controlled by a soft starter and remote monitoring and control by contemporary devices has been provided. A methodology of design and setting up has been developed.

Open access

P. Vasilev and V. Filipov

Abstract

Facility Management is an important part in the commercial buildings and installations lifecycle, which includes permanent checks and monitoring of all systems and installations, helping to achieve the organizational objectives. The execution of activities of Maintenance and Inspection is often redistributed to contracted service providers which raises the issue of managing and supervising the results of work done. The major factor for proper execution of distributed tasks is the formalization of the activities in manner of who-what-when-why-how has to be done to accomplish the work. These rules have to be used as guidelines during the tasks execution and for the purpose of managing and supervising the overall progress of maintenance activities.

Open access

Dongha Shim and Jason Yi

Abstract

This paper presents a wireless endoscope with an ultra-wide FOV (Field of View) of 130° and HD resolution (1280×720 pixels). The proposed endoscope consists of a camera head, cable, camera controller, and wireless handle. The lens module with a 150° degrees AOV (Angle of View) is achieved using the plastic injection-molding process to reduce manufacturing costs. A serial CMOS image sensor using the MIPI (Mobile Industry Processor Interface) CSI-2 (Camera Serial Interface-2) interface physically separates the camera processor from the camera head. The camera head and the cable have a compact structure due to the BCC (Backend-Camera-Controller) architecture. The size of the camera head and the camera controller is 8×8×26 mm and 7×55 mm, respectively. The wireless handle supports a UWB (Ultra-Wide-Band) or a Wi-Fi communication to transmit video data. The UWB link supports a maximum data transfer rate of ~37 Mbps to transmit video data with a resolution of 1280×720 pixels at a frame rate of 30 fps in the MJPEG (Motion JPEG) format. Although the Wi-Fi link provides a lower data transfer rate (~8 Mbps Max.), it has the advantage of flexible interoperability with various mobile devices. The latency of the UWB link is measured to be ~0.1 sec. The Wi-Fi link has a larger latency (~0.5 sec) due to its lower data transfer rate. The proposed endoscope demonstrates the feasibility of a high-performance yet low-cost wireless endoscope using the BCC architecture. To the best of the author’s knowledge, the proposed endoscope has the largest FOV among all presently existing wireless endoscopes.

Open access

K. Ormandzhiev, S. Yordanov and S. Stoyanov

Abstract

The paper deals with a developed mathematical model describing the operation of automatic system for controlling of cross-flow water turbine in laboratory conditions. Fuzzy governor is synthesized and the transient processes in the system are compared toward these ones during utilization of classical PD controller. The results from numerical experiment are presented in graphical form.

Open access

Łukasz Chruszczyk

Abstract

This paper presents statistical analysis of RSSI read-outs recorded in indoor environment. Many papers concerning indoor location, based on RSSI measurement, assume its normal probability density function (PDF). This is partially excused by relation to PDF of radio-receiver's noise and/or together with influence of AWGN (average white Gaussian noise) radio-channel – generally modelled by normal PDF. Unfortunately, commercial (usually unknown) methods of RSSI calculations, typically as “side-effect” function of receiver's AGC (automatic gain control), results in PDF being far different from Gaussian PDF. This paper presents results of RSSI measurements in selected ISM bands: 433/868 MHz and 2.4/5 GHz. The measurements have been recorded using low-cost integrated RF modules (at 433/868 MHz and 2.4 GHz) and 802.11 WLAN access points (at 2.4/5 GHz). Then estimated PDF of collected data is shown and compared to normal (Gaussian) PDF.

Open access

Andrzej Borys

Abstract

The so-called Saleh’s representation for description of the AM/AM and AM/PM conversions, occurring in communication power amplifiers, consists of two expressions that describe them as functions of a real-valued baseband signal modulating the carrier amplitude. It is a common view that this description forms a model without memory. We show here that the above belief is not correct; just the opposite is true. To prove this, we take into account an equivalent description of the Saleh’s model called the quadrature model of bandpass nonlinearities and express it in a form of a nonlinear operator. Afterwards, we check whether this operator possesses a zero memory. To this end, we use an appropriate theorem of the nonlinear systems theory. Finally, as a result of this investigation, we observe that the memory of the above operator is nonzero.

Open access

Qun Li and Ding Xu

Abstract

This paper considers a fading cognitive multiple access channel (CMAC), where multiple secondary users (SUs), who share the spectrum with a primary user (PU), transmit to a cognitive base station (CBS). A power station is assumed to harvest energy from the nature and then provide power to the SUs. We investigate the power allocation problems for such a CMAC to maximize the SU sum rate under the interference power constraint, the sum transmit power constraint and the peak transmit power constraint of each individual SU. In particular, two scenarios are considered: with successive interference cancellation (SIC) and without SIC. For the first scenario, the optimal power allocation algorithm is derived. For the second scenario, a heuristic algorithm is proposed. We show that the proposed algorithm with SIC outperforms the algorithm without SIC in terms of the SU sum rate, while the algorithm without SIC outperforms the algorithm with SIC in terms of the number of admitted SUs for a high sum transmit power limit and a low peak transmit power limit of each individual SU.

Open access

Y. Aleksieva and H. Valchanov

Abstract

The most serious appearance of modern malware is Botnet. Botnet is a fast growing problem that is still not well understood and studied. One widely spreading variant of the botnet attacks is an IRC botnet. There are a number of techniques to detect botnet attacks and infections, but they do not have the functionality to prevent malicious botnet activity. The development of a quality equipment to detect and remove botnet infection needs a good simulation environment that is safe and fully meets the functionality of botnet DoS attacks. The paper presents the features of the implementation of network simulator for DoS attacks. The simulator allows creating different attacks with various parameters. Some performance experiences are performed and the obtained results are shown.

Open access

Ryszard Kopka, Wiesław Tarczyński and Sławomir Pluta

Abstract

The paper presents results related to assessment of the repeatability and reproducibility of the measurement test setup for determination the relative value of the shielding effectiveness coefficient of the industrial connectors. The construction of the proposed test setup, the measurement method and the procedure for the analysis of measurement results were described. To determine the value of the repeatability and reproducibility coefficient, the two–way analysis of variance was used, which additionally allows for an assessment of the influence of individual sources of variance. The measurements and their analysis were conducted for several frequencies in the range up to 1 GHz. Additionally, the expanded measurement uncertainty, including the test setup and instruments uncertainty was estimated.