Constrained and unconstrained evolution of “ LCR” low-pass filters with oscillating length representation

The unconstrained evolution has already been applied in the past towards design of digital circuits, and extraordinary results have been obtained, including generation of circuits with smaller number of electronic components. In this paper both constrained and unconstrained evolutions, blended with oscillating length genotype sweeping strategy, are applied towards design of analogue “ LCR” circuits. The comparison of both evolutions is made and the promising results are obtained. The new algorithm has produced the best results in terms of quality of the circuits evolved and evolutionary resources required. It differs from previous ones by its simplicity and represents one of the first attempts to apply Evolutionary Strategy towards the analogue circuit design. The obtained results are compared in details with low-pass filters previously designed

Unconstrained evolution of close-to-ideal "LCR" low-pass filter

The unconstrained evolution has already been applied in the past towards design of digital circuits, and extraordinary results have been obtained, including generation of more compact circuits with smaller number of electronic components. In this paper the unconstrained evolution method is developed for analogue circuits. At first, the method is probed on the design of analogue low-pass filter with standard transition band. The algorithm produced the best results in terms of quality of the circuits evolved and evolutionary resources required. Then, the new methodology is applied towards more sophisticated task, the close-to-ideal low-pass filter. The new methodology developed differs from previous ones by its simplicity and represents one of the first attempts to apply evolutionary strategy towards the analogue circuit design. The obtained results are compared in details with low-pass filters previously designed

Absolutely free extrinsic evolution of passive low-pass filter

Evolutionary electronics is a brunch of evolvable hardware, where the evolutionary algorithm is applied towards electronic circuits. The success of evolutionary search most of all depends on variable length representation methodology. The low-pass filter is a standard task in evolutionary electronics to start with. The results of evolution enable one to qualify whether the methodology is good for further experiments. In this paper the maximum freedom for evolutionary search has been proclaimed as a main target during development of new VLR methodology. The introduction of R-support elements enables to perform an unconstrained evolution of analogue circuits for the first time. The proposed algorithm has been tested on the example of analogue low-pass filter. The experimental results demonstrate that the evolved filter is comparable with filters evolved previously using genetic programming and genetic algorithms techniques. The obtained results are compared in details with low-pass filters previously designed

Challenging the evolutionary strategy for synthesis of analogue computational circuits

There are very few reports in the past on applications of Evolutionary Strategy (ES) towards the synthesis of analogue circuits. Moreover, even fewer reports are on the synthesis of computational circuits. Last fact is mainly due to the dif-ficulty in designing of the complex nonlinear functions that these circuits perform. In this paper, the evolving power of the ES is challenged to design four computational circuits: cube root, cubing, square root and squaring functions. The synthesis succeeded due to the usage of oscillating length genotype strategy and the substructure reuse. The approach is characterized by its simplicity and represents one of the first attempts of application of ES towards the synthesis of “QR” circuits. The obtained experimental results significantly exceed the results published before in terms of the circuit quality, economy in components and computing resources utilized, revealing the great potential of the technique pro-posed to design large scale analog circuits

Automatic design of analogue circuits

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Evolvable Hardware (EHW) is a promising area in electronics today. Evolutionary Algorithms (EA), together with a circuit simulation tool or real hardware, automatically designs a circuit for a given problem. The circuits evolved may have unconventional designs and be less dependent on the personal knowledge of a designer. Nowadays, EA are represented by Genetic Algorithms (GA), Genetic Programming (GP) and Evolutionary Strategy (ES). While GA is definitely the most popular tool, GP has rapidly developed in recent years and is notable by its outstanding results. However, to date the use of ES for analogue circuit synthesis has been limited to a few applications. This work is devoted to exploring the potential of ES to create novel analogue designs. The narrative of the thesis starts with a framework of an ES-based system generating simple circuits, such as low pass filters. Then it continues with a step-by-step progression to increasingly sophisticated designs that require additional strength from the system. Finally, it describes the modernization of the system using novel techniques that enable the synthesis of complex multi-pin circuits that are newly evolved. It has been discovered that ES has strong power to synthesize analogue circuits. The circuits evolved in the first part of the thesis exceed similar results made previously using other techniques in a component economy, in the better functioning of the evolved circuits and in the computing power spent to reach the results. The target circuits for evolution in the second half are chosen by the author to challenge the capability of the developed system. By functioning, they do not belong to the conventional analogue domain but to applications that are usually adopted by digital circuits. To solve the design tasks, the system has been gradually developed to support the ability of evolving increasingly complex circuits. As a final result, a state-of-the-art ES-based system has been developed that possesses a novel mutation paradigm, with an ability to create, store and reuse substructures, to adapt the mutation, selection parameters and population size, utilize automatic incremental evolution and use the power of parallel computing. It has been discovered that with the ability to synthesis the most up-to-date multi-pin complex analogue circuits that have ever been automatically synthesized before, the system is capable of synthesizing circuits that are problematic for conventional design with application domains that lay beyond the conventional application domain for analogue circuits

Automatic design of analogue circuits

Evolvable Hardware (EHW) is a promising area in electronics today. Evolutionary Algorithms (EA), together with a circuit simulation tool or real hardware, automatically designs a circuit for a given problem. The circuits evolved may have unconventional designs and be less dependent on the personal knowledge of a designer. Nowadays, EA are represented by Genetic Algorithms (GA), Genetic Programming (GP) and Evolutionary Strategy (ES). While GA is definitely the most popular tool, GP has rapidly developed in recent years and is notable by its outstanding results. However, to date the use of ES for analogue circuit synthesis has been limited to a few applications. This work is devoted to exploring the potential of ES to create novel analogue designs. The narrative of the thesis starts with a framework of an ES-based system generating simple circuits, such as low pass filters. Then it continues with a step-by-step progression to increasingly sophisticated designs that require additional strength from the system. Finally, it describes the modernization of the system using novel techniques that enable the synthesis of complex multi-pin circuits that are newly evolved. It has been discovered that ES has strong power to synthesize analogue circuits. The circuits evolved in the first part of the thesis exceed similar results made previously using other techniques in a component economy, in the better functioning of the evolved circuits and in the computing power spent to reach the results. The target circuits for evolution in the second half are chosen by the author to challenge the capability of the developed system. By functioning, they do not belong to the conventional analogue domain but to applications that are usually adopted by digital circuits. To solve the design tasks, the system has been gradually developed to support the ability of evolving increasingly complex circuits. As a final result, a state-of-the-art ES-based system has been developed that possesses a novel mutation paradigm, with an ability to create, store and reuse substructures, to adapt the mutation, selection parameters and population size, utilize automatic incremental evolution and use the power of parallel computing. It has been discovered that with the ability to synthesis the most up-to-date multi-pin complex analogue circuits that have ever been automatically synthesized before, the system is capable of synthesizing circuits that are problematic for conventional design with application domains that lay beyond the conventional application domain for analogue circuits.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Unconstrained evolution of analogue computational “QR” circuit with oscillating length representation

The unconstrained evolution has already been applied in the past towards the design of digital circuits, and extraordinary results have been obtained, including generation of circuits with smaller number of electronic components. In this paper unconstrained evolution, blended with oscillating length genotype sweeping strategy, is applied towards the design of "QR" analogue circuit on the example of circuit that performs the cube root function. The promising results are obtained. The new algorithm has produced the excellent result in terms of quality of the circuit evolved and evolutionary resources required. It differs from previous ones by its simplicity and represents one of the first attempts to apply Evolutionary Strategy towards the analogue circuit design. The obtained result is compared with previous designs

Next Generation of Magneto-Dielectric Antennas and Optimum Flux Channels

abstract: There is an ever-growing need for broadband conformal antennas to not only reduce the number of antennas utilized to cover a broad range of frequencies (VHF-UHF) but also to reduce visual and RF signatures associated with communication systems. In many applications antennas needs to be very close to low-impedance mediums or embedded inside low-impedance mediums. However, for conventional metal and dielectric antennas to operate efficiently in such environments either a very narrow bandwidth must be tolerated, or enough loss added to expand the bandwidth, or they must be placed one quarter of a wavelength above the conducting surface. The latter is not always possible since in the HF through low UHF bands, critical to Military and Security functions, this quarter-wavelength requirement would result in impractically large antennas. Despite an error based on a false assumption in the 1950’s, which had severely underestimated the efficiency of magneto-dielectric antennas, recently demonstrated magnetic-antennas have been shown to exhibit extraordinary efficiency in conformal applications. Whereas conventional metal-and-dielectric antennas carrying radiating electric currents suffer a significant disadvantage when placed conformal to the conducting surface of a platform, because they induce opposing image currents in the surface, magnetic-antennas carrying magnetic radiating currents have no such limitation. Their magnetic currents produce co-linear image currents in electrically conducting surfaces. However, the permeable antennas built to date have not yet attained the wide bandwidth expected because the magnetic-flux-channels carrying the wave have not been designed to guide the wave near the speed of light at all frequencies. Instead, they tend to lose the wave by a leaky fast-wave mechanism at low frequencies or they over-bind a slow-wave at high frequencies. In this dissertation, we have studied magnetic antennas in detail and presented the design approach and apparatus required to implement a flux-channel carrying the magnetic current wave near the speed of light over a very broad frequency range which also makes the design of a frequency independent antenna (spiral) possible. We will learn how to construct extremely thin conformal antennas, frequency-independent permeable antennas, and even micron-sized antennas that can be embedded inside the brain without damaging the tissue.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Active nematic turbulence: An experimental study

[eng] One of the most striking phenomena of active fluids, i.e., fluids composed of self-propelled constituents, is the emergence of chaotic spatiotemporal flows. "This regime, reminiscent of inertial turbulence but happening at low Reynolds numbers, has become to be known as active turbulence. It has been observed in a variety of systems, such as bacterial suspensions or epithelial tissues. Despite the visual similarities, active turbulent flows possess fundamental differences from classical turbulent flows. The differences essentially emanate from the fact that active turbulence originates at vanishing Reynolds numbers from the self-organization of the fluid constituents, which move coordinately at distances much larger than their own size. As a result, active chaotic flows are endowed with a characteristic length scale. In this thesis, working with an experimental active system displaying nematic order, i.e., head-to- tail orientational order, and composed of proteins from the cytoskeleton, we address some still- standing open questions regarding active turbulence. More specifically, since our experimental system is two-dimensional and has nematic order, we study 2D active nematic turbulence. We begin this thesis by unveiling the pathway followed by the active fluid with an imposed radial alignment to its final characteristic chaotic state. More in particular, we demonstrate that the AN in the aster configuration is intrinsically unstable to buckling. In turn, a characteristic length scale already emerges at the instability's early stages. Interestingly, the instability of the aligned active nematic can be characterized in terms of a growth rate that exhibits a quadratic or quasi-quadratic dependence on the leading wavenumber. Our experimental results are then compared with predictions obtained from linear stability analysis. This enables us to see that the coupling of the active nematic with adjacent fluid layers precludes long wavelength fluctuations, imposing in this way a genuine wavelength selection mechanism. In the second project, we measure the active liquid crystal's flow field and the associated kinetic energy spectrum. In this way, we verify the existence of scaling regimes, some of which feature exponents previously predicted through theory and simulations , together with new ones. To understand the newly-discovered scaling regimes, we exploit a theory that includes the hydrodynamic coupling of the active nematic with the two contacting passive fluid layers. This theory assesses the range of validity of the identified scaling regimes, and permits to extract information on important rheological parameters of the active fluid In the final project, still in progress, we address the presence of energy cascades in active nematic turbulence. Preliminary experimental results, supported with simulations, suggest that even though the free energy balance does not entirely vanish at all length scales, we cannot indeed conclude that there is energy transfer between scales. A significant limitation we encounter when computing the free energy balance of the active nematic is that most of the material parameters still need to be determined. Therefore, further research research devoted to the evaluation of such parameters may shed light on this respect. On top of the above fundamental studies, we also demonstrate two implementations of polarimetry measurements coupled with fluorescence imaging, with which we can simultaneously measure the director and velocity fields of the active nematic . The first arrangement is based on a liquid crystal slab, whose retardance can be easily commanded with a computer. By measuring the light intensity reaching the detector at different configurations of the liquid crystal retarder, we can unequivocally and continuously know the sample's local orientation. The alternative implementation incorporates a polarization camera, a device composed of subpixels with different polarizations. This arrangement allows us to obtain exceptional birefringence measurements at significantly high frame rates, even with very low-birefringent samples, as the active nematic.[cat] Els fluids actius, com les suspensions de bacteris o els teixits, són fluids compostos per moltes unitats capaces de propulsar-se contínuament. Aquests fluids presenten propietats molt interessants i radicalment oposades a les que s’observen quan una d’aquestes unitats actives es mou individualment. Un exemple és el que es coneix com a turbulència activa, on els fluids actius es mouen caòticament i que emergeix inclús a números de Reynolds baixos, quan la inèrcia es menyspreable. Aquest fenomen es diu així perquè visualment recorda a la turbulència inercial clàssica. Tot i així, hi ha diferències fonamentals entre aquests dos tipus de turbulència, els quals ens interessa discernir. En aquesta tesi es presenten estudis experimentals, duts a terme amb una suspensió de proteïnes del citoesquelet, i amb els quals abordem algunes qüestions encara obertes sobre la turbulència activa i les seves similituds i diferències amb la turbulència inercial. Més concretament, com el nostre sistema experimental és 2D i presenta simetria nemàtica, nosaltres estudiem la turbulència nemàtica activa. En primer lloc, revelem el camí que segueix el nemàtic actiu alineat radialment fins que arriba al seu estat turbulent. Més concretament, demostrem que la geometria d’àster és inestable; en conseqüència, el fluid actiu comença a deformar-se i llavors emergeix una escala de longitud característica. Després duem a terme estudis on l’actiu nemàtic ja es troba plenament en el seu estat turbulent. En aquest sentit, demostrem l’existència de règims d’escala en l’espectre d’energia cinètica del nemàtic actiu i abordem la presència o no presència de cascades d’energia en el context de la turbulència nemàtica activa. Finalment, descrivim dues tècniques de polarimetria acoblades a fluorescència amb les quals podem mesurar simultàniament la orientació i el camp de velocitats del nemàtic actiu i que ens permeten dur a terme les mesures experimentals presentades en aquesta tesi