Electrical And Electronic Engineering

The observation of spatial and frequency instability of an intense laser wave in sodium vapor at low-frequency laser detuning with respect to the D1 sodium transition is reported. It is shown that the observed picture of the scattering (cone radiation, generation of shifted sidebands, formation of filaments) in general is analogous to that at high-frequency detuning. A theory of resonance four-wave mixing in a three-level atomic medium is presented which is in qualitative agreement with the experimental results.

In this paper we describe a system designed to be used on a shop floor of a factory that produces non-flat ceramic products, where an extensive mixture of human and automatic labour is present. Today manufacturing setups rely increasingly on technology. It is common to have all sources of equipment on the shop floor, commanded by industrial PCs or PLCs connected by an industrial network to other factory resources. Also, the production systems are becoming more and more autonomous requiring less operator intervention in every day normal operation. That means using computers for controlling and supervision of the production systems, industrial networks and distributed software architectures [I]. It means also designing application software that is really distributed in the shop floor, taking advantage of the flexibility installed by using programmable equipment. Non-flat ceramic products are commonly used in ow homes and are mainly associated with personal care tasks. The industrial production of those ceramic products poses several problems to industrial automation, namely if robots are to be used. Basically, those problems arise from the characteristics of the ceramic pieces: non flat objects with high reflective surfaces, very difficult to grasp and handle due to the external configuration, very heavy and fragile, extensive surface sensitive to damage, high demand of quality on surface smoothness, etc. Also, the production setups for this type of products require very high quality and low cycle times, since this is a large scale industry that will only remain competitive if production rates are kept. Another restriction is related with the fact that this industry changes products very frequently, due to fashion tendencies in home decoration, etc. Also, there is an extensive mixture between automatic and human labour production, which is a difficult problem since Human-Machine Interfaces (HMI) are very demanding and a key issue in modem industrial automation systems.

Homogeneous emitter solar cells with Gaussian profiles have been optimized based on a one-dimensional theoretical model with analytical solutions. A complete n þ pp þ structure was optimized considering the shadowing factor F m ffi 3%, typical for laboratory processes. The studies demonstrate the high quality of the homogeneous emitters, presenting high emitter collection efficiencies and low recombination current densities. Since the fabrication technology for these emitters is simple, their physical limitations in industrial processes are analyzed, showing that Ag screen printing (typical for industrial cell contacts), requires Gaussian profile emitters with a surface doping level greater than N s ¼ 1 Â 10 20 cm À3 in order to minimize the metal-semiconductor contact resistance. A comparison between the electrical output parameters of homogeneous emitter silicon solar cells with shadowing factors F m ffi 3% and F m ffi 7% has been made. A decrease of @2.5% in the solar cell maximum efficiency was found when the shadowing factor was increased and the industrial requirements were satisfied. However, if new technologies that allow selective or nonhomogeneous emitters are considered, efficiencies up to @20% may be reached, being only 1.6% lower than the optimized laboratory solar cells.

An in-line and real time chromatic sensor for liquids based on plastic optical fiber was developed. It uses an air gap, fiber to fiber, transmission principle. Its dependency to turbidity and refractive index is studied and characterized. This information will provide the necessary knowledge for future implementation of more complex auto-compensations routines. Due to the predictable behavior of the sensor to variations of turbidity and refractive index, it is shown that a posterior compensation could be applied for the discrimination of color. The real-time color sensor can be used in different turbid liquids and contain different refractive indices.

A theoretical analysis for a new high sensitivity pressure sensor based on the surface plasmon resonance (SPR) phenomenon is presented. The device consists in a thin metal film deposited on the cladding of a U-shaped optical fiber probe embedded in a silicon rubber block. When the block is under pressure, the bending radius will vary and consequently a shift on the SPR wavelength can be noticed and converted to pressure units. Theoretical simulations using the transfer matrix formalism and the N-layer U-shaped fiber model were developed and implemented for three different metals: gold, copper and silver. A resolution of 5.9x10 -4 , 6.3x10 -4 and 1.3x10 -3 kPa can be expected for gold, copper and silver, respectively for a working range up to 0.12 MPa. The proposed structure reveals to be suitable to high sensitivity pressure measurements, including industrial operating machinery and R&D applications. RESSURE measurements using conventional electrical gauges for high temperature, explosive and/or corrosive environments have high failure rates. This problem attracted the attention of academic and industrial researchers to develop optical fiber based pressure sensors for applications like compressors, turbines and other operating machinery, high intensity sound, turbulence and downhole environments, where the pressure monitoring is essential New concepts based on the surface plasmon resonance (SPR) technology has shown to attain high refractive index (RI) sensitivities, being a research motivation to develop SPR based sensors. The light interaction between a metal-dielectric Manuscript

This work reports the development of a low cost in-line color sensor for turbid liquids based on the transmission and scattering phenomena of light from RGB and IR LED sources, gathering multidimensional data. Three different methodologies to discriminate color from the turbidity influence are presented as a proof of concept approach. They are based in regression models, expectation maximization Gaussian mixtures and artificial neural networks applied to labeled measurements. Each methodology presents advantages and disadvantages which will depend on the intended implementation. Regression models revealed to be best suited for standard or occasional measurements, the EM Gaussian mixture will perform better for well-known controlled range of colors and turbidities and the neural networks have easy implementation and potential suited for real-time IoT platforms.

We introduce and analyse the problem of encoding classical information into different resources of a quantum state. More precisely, we consider a general class of communication scenarios characterised by encoding operations that commute with a unique resource destroying map and leave free states invariant. Our motivating example is given by encoding information into coherences of a quantum system with respect to a fixed basis (with unitaries diagonal in that basis as encodings and the decoherence channel as a resource destroying map), but the generality of the framework allows us to explore applications ranging from super-dense coding to thermodynamics. For any state, we find that the number of messages that can be encoded into it using such operations in a one-shot scenario is upper bounded in terms of the information spectrum relative entropy between the given state and its version with erased resources. Furthermore, if the resource destroying map is the twirling channel over some unitary group, we find matching one-shot lower bounds as well. In the asymptotic setting where we encode into many copies of the resource state, our bounds yield an operational interpretation of resource monotones such as the relative entropy of coherence and its corresponding relative entropy variance.

Optical spectroscopy can provide useful diagnostic information about the morphological and biochemical changes related to the progression of precancer in epithelial tissue. As precancerous lesions develop, the optical properties of both the superficial epithelium and underlying stroma are altered; measuring spectral data as a function of depth has the potential to improve diagnostic performance. We describe a clinical spectroscopy system with a depth-sensitive, ball lens coupled fiber-optic probe for noninvasive in vivo measurement of oral autofluorescence and diffuse reflectance spectra. We report results of spectroscopic measurements from oral sites in normal volunteers and in patients with neoplastic lesions of the oral mucosa; results indicate that the addition of depth selectivity can enhance the detection of optical changes associated with precancer.

Recently, video surveillance systems have evolved from expensive, human-operated monitoring systems that were only useful after the crime was committed to systems that monitor 24/7, in real time, and with less and less human involvement. This is partly due to the use of smart cameras, the improvement of the Internet, and AI-based algorithms that allow the classifying and tracking of objects in images and in some cases identifying them as threats. Threats are often associated with abnormal or unexpected situations such as the presence of unauthorized persons in a given place or time, the manifestation of a different behavior by one or more persons compared to the behavior of the majority, or simply an unexpected number of people in the place, which depends largely on the available information of their context, i.e., place, date, and time of capture. In this work, we propose a model to automatically contextualize video capture scenarios, generating data such as location, date, time, and flow of people in the scene. A strategy to measure the accuracy of the data generated for such contextualization is also proposed. The pre-trained YOLO11n algorithm and the Bot-SORT algorithm gave the best results in person detection and tracking, respectively.

We prove the existence of positive singular solutions for the semi-linear parabolic equation and μ is in a general class of signed Radon measures on D covering the elliptic Kato class of potentials adopted by Zhang and Zhao. A new proof of the result based on a simple fixed point theorem is also given.

This paper presents an improvement of a classic Dijkstra algorithm to the domain of sampling based motion. The algorithm uses an image, obtained by a camera. The algorithm processes the image to convert it into a matrix, presenting the labyrinth with obstacles and walls. Afterwards the algorithm finds the shortest path to a final target in the labyrinth. In contrast to the classical Dijkstra's algorithm, the presented algorithm compares the size of the robot to the size of the obstacles on the way. A simulation of the algorithm is developed to visualize the movement of the robot. Experimental results, obtained by the simulation, are presented. The potential of the proposed results is apparent both in terms of reliability and quality of solutions found.

This paper describes a method for voltage control towards optimal power flow (OPF) operation of radial distribution systems through reactive power (Q) control of distributed energy resources (DERs). A two-level control system consisting of an upper-level centralized controller and lower-level local controllers is proposed. First, a stable local control scheme and a criteria for its voltage stability via a discrete-time state-space model are presented. Second, the local control scheme is combined with a centralized AC OPF optimization to minimize delivery losses in the distribution system while maintaining bus voltages at optimal levels. The control system is modeled and simulated in Matlab/OpenDSS considering real world input data. In a simulation study of the IEEE 123-bus test system with historical load and solar generation data for a 24-h period, the proposed method is compared to other Q modes of DERs, specifically the volt-var droop control mode and a centralized OPF control mode. Furthermore, the control system is used in a scenario with an on-load tap changer and in unbalanced loading conditions. Overall, the proposed control method enhances existing local controllers with faster convergence and reduced voltage variations while ensuring stability, particularly in cases with highly intermittent renewable generation. In addition, it can reduce system voltage unbalance and transformer tap changer operations.

In this paper, a new generation control strategy is proposed based on combined use of different resources including large hydroelectric power plants and directly controlled industrial responsive loads. Water pumping in water storage systems is modeled as a virtual power plant (VPP) in transmission system. The balance model is in the economic dispatch (ED) time frame and loads are scheduled to be dispatched optimally along with the swing hydroelectric plant, which realizes load-following and frequency regulation. The model is implemented on the IEEE 24 bus reliability test system with hydroelectric generation units. Real-field data of responsive loads are used and the results show the value of flexibility of responsive loads in increasing generation efficiency of hydroelectric power plants operated in swing mode.

An autonomous deterministic non-linear epidemic model SEQIHRS is proposed for the transmission dynamics of an infectious disease with quarantine and isolation control strategies in a community with pre-existing immunity. The model exhibits two equilibria, namely, the disease-free and a unique endemic equilibrium. The existence and local stability of the disease free and endemic equilibria are explored in terms of the effective reproduction number R C . It is observed that media coverage does not affect the effective reproduction number, but it helps to mitigate disease burden by lowering the number of infectious individuals at the endemic steady state and also lowering the infection peak. A new approach is proposed to estimate the coefficient of media coverage. Using the results of central manifold theory, it is established that as R C passes through unity, transcritical bifurcation occurs in the system and the unique endemic equilibrium is asymptotically stable. It is observed that the population level impact of quarantine and isolation depend on the level of transmission by the isolated individuals. Moreover, the higher level of pre-existing immunity in the population decreases the infection peak and causes its early arrival. Theoretical findings are supported by numerical simulation. Sensitivity analysis is performed for R C and state variables at endemic steady state with respect to model parameters.

We present and evaluate a lightweight and effective approach for the management of prosumer communities through the synergistic control of the power electronic converters acting therein. These controllable elements are the utility interface (UI), installed at the point of common coupling with the electrical utility, and the energy gateways (EGs), interfacing distributed generation units and energy storage devices with the distribution grid. The UI acts as the control master for the microgrid, collecting information on generators and power demand and dispatching a control parameter that regulates both energy storage devices and generators. An islanded operation mode is considered, and the control strategy aims at leveling peaks in the energy drained from or injected into the UI. The proposed control strategy is tested on a residential microgrid model, 100 kVA rated, which has been developed and utilized to analyze selected performance metrics in the presence of realistic and time varying power demand and energy generation processes. This model allows a fine-grained analysis of a) the energy storage state at each residential unit, b) the amount of energy required at the UI, and c) the locally generated energy injected into the micro grid by each EG. As a further result, our framework returns the amount of distributed storage required to achieve a target peak-shaving performance level, according to the number of residential users with generation capability and their storage capacity.

Smart micro-grids offer a new and wide application domain for power electronics. In fact, every distributed energy resource (DER) includes an electronic power processor (EPP) capable to control the active and reactive power flow from/to the distribution grid. If such EPPs perform cooperatively, they have the capability to fully exploit every local energy source while improving both power quality and distribution efficiency. This is of particular relevance in low-voltage residential micro-grids, where a plethora of small DERs may be active at the same time and the co-ordination of their operation can greatly improve the micro-grid performance. A simple and effective solution to achieve cooperative operation of EPPs is described in the paper. It makes use of a control method which requires power data exchange within the micro-grid and provides quasiminimum distribution losses and local voltage support. Streszczenie. Inteligentne mikro-sieci są obszarem nowych zastosowań energoelektroniki. Każde źródło rozproszonej energii (ang.: distributed energy resource -DER) zawiera procesor energoelektroniczny (ang.: electronic power processor -EPP) zdolny kontrolować przepływ mocy czynnej i mocy biernej ze źródła do sieci rozdzielczej i w kierunku odwrotnym. Jeśli EPP działają kooperatywnie mają wówczas zdolność pełnego wykorzystania każdego źródła, poprawiając jednocześnie jakość energii i sprawność jej rozdziału. Jest to szczególnie ważne w mikro-sieciach osiedlowych niskiego napięcia, w których może być jednocześnie czynnych wiele małych DER i koordynacja ich pracy może właściwości mikro-sieci znacząco poprawić. Niniejszy artykuł przedstawia proste i skuteczne rozwiązanie kooperatywnej współpracy EPP. Rozwiązanie to wykorzystuje metody sterowania, wymagające wymiany informacji wewnątrz mikro-sieci. Zapewnia ono niemal minimalne dystrybucyjne straty energii i lokalną kontrolę napięcia. (Kooperacyjne sterowanie inteligentnych mikro-sieci oparte na kontroli mocy zachowawczej)

In this paper, a general-purpose fuzzy controller for dc-dc converters is investigated. Based on a qualitative description of the system to be controlled, fuzzy controllers are capable of good performances, even for those systems where linear control techniques fail, e.g., when a mathematical description is not available or is in the presence of wide parameter variations. The presented approach is general and can be applied to any dc-dc converter topologies. Controller implementation is relatively simple and can guarantee a small-signal response as fast and stable as other standard regulators and an improved large-signal response. Simulation results of Buck-Boost and Sepic converters show control potentialities.

Smart microgrids offer a new challenging domain for power theories and compensation techniques, because they include a variety of intermittent power sources, which can have dynamic impact on power flow, voltage regulation, and distribution losses. When operating in the islanded mode, low-voltage smart microgrids can also exhibit considerable variation of amplitude and frequency of the voltage supplied to the loads, thus affecting power quality and network stability. Due to limited power capability in smart microgrids, the voltage distortion can also get worse, affecting measurement accuracy, and possibly causing tripping of protections. In such context, a reconsideration of power theories is required, since they form the basis for supply and load characterization, and accountability. A revision of control techniques for harmonic and reactive compensators is also required, because they operate in a strongly interconnected environment and must perform cooperatively to face system dynamics, ensure power quality, and limit distribution losses. This paper shows that the conservative power theory provides a suitable background to cope with smart microgrids characterization needs, and a platform for the development of cooperative control techniques for distributed switching power processors and static reactive compensators. Index Terms-Conservative power theory (CPT), distributed control, electronic power processors, power measurement, revenue metering, smart microgrids. S MART grids represent one of the grand challenges at plane- tary level. The infusion of information technology throughout the electric grid creates new capabilities, with potential impact on environment, science and technology, economics, and lifestyle. The term "smart grid" outlines the evolution of electrical grids and a change of paradigm in the electric market organization and management [30], . In a global perspective, implementation of smart grids and microgrids on a large scale will result in dramatic improvement of electrical services and considerable market increase.

This paper surveys the results of an extended research activity concerning the effects of radio frequency interference (RFI) on integrated circuits (IC's). Initially, the possible injection methods for conducted and radiated interference are presented, discussing their applicability and limitations. Then, the basic results of the susceptibility analysis of operational amplifiers and smart power integrated circuits are briefly discussed. Finally, experimental data describing some effects of RFI direct injection on switch mode power supply integrated controllers are presented.

This paper proposes a technique to control distributed energy resources in low-voltage microgrids aiming at (i) allowing power flow control at the point of connection with the upstream grid, (ii) keeping voltage profiles within the operational limits. The first feature is crucial in smart low-voltage power systems. In fact, it enables both demand-responses, which is extremely valuable from the point of view of distribution system operators and for energy trading, and the autonomous operation of the microgrid. The latter can be achieved by regulating to zero the power exchanged with the main grid. The second feature allows to limit voltage increases due to active power injection by distributed energy resources and, thus, to limit stresses on the electrical infrastructure and the served loads, which is a concrete issue as renewables become widely deployed in the low-voltage scenario. The proposed approach is firstly described in detail, then a systematic analysis of its local and glob...

Common problems with Oxide-based Resistive RAM are related to high variability in operating conditions and high programming currents during FORMING, SET and RESET operations. Although research has taken steps to resolve these issues, variability combined with high programming currents remains an important characteristic for RRAMs. In a conventional write scheme with fixed duration and amplitude, the programming current is not controlled, which degrades the cell performance (power consumption and variability) due to over-programming. In this paper, a self-adaptive write driver is proposed to control the write current. A feedback mechanism based on current comparison is used to switch off the write stimulus as soon as the preferred write current is reached. Compared to conventional write schemes, in the proposed write-assist circuit, the write energy per bit is reduced by 27% and the standard deviation of post-FORMING distributions is reduced by 57%.

Physical Layer Security (PLS) has emerged as a promising solution for small and resource-limited wireless communications devices, to reduce the overhead associated with the required security resources and latency. In contrast to traditional security schemes, PLS relies on and benefits from the random nature of physical channels. However, the majority of PLS schemes in the literature lack the notion of secrecy and dynamicity, and employ static keys to generate fixed cipher primitives. In this paper, a dynamic key generation scheme that combines a pre-shared/stored secret key with a dynamic nonce extracted from channel information (for each new session) is proposed. The main advantage of this approach is that it achieves a highsecurity level with minimal overhead. Moreover, the obtained dynamic key can be changed frequently upon any change in channel parameters. Using the produced dynamic keys, cipher primitives are generated (permutation operations), which get updated for each frame symbol. This process ensures different and unique encryption layers for each new input frame and for each symbol in the input frame. Equally important, the proposed encryption algorithm operates at the modulation symbol level in order to attain performance by limiting the effect of error propagation and by realizing parallel encryption/decryption for each frame symbol. In addition, a preamble encryption scheme is also proposed to prevent unauthorized synchronization or channel estimation by illegitimate users. The security level of the proposed cipher scheme mainly depends on a secret key and the dynamicity of the channel to update the cipher primitives used for each frame symbol. Finally, security and performance analyses validate the efficiency and the robustness of the proposed approach.