A new method to localize partial discharges on power cables using time reversal and TLM numerical method – A review

The file attached to this record is the author's final peer reviewed version.Insulation deterioration is often caused by partial discharge (PD) events. The adoption of on-line PD location methods is one of the most suitable methods to perform the power networks condition monitoring to improve their resilience and to guarantee electricity supply security. This paper reviews the results obtained in the design process of a new on-line PD location method based on the use of the electromagnetic time reversal (EMTR) theory and the Transmission Line Matrix (TLM) numerical method. Building on the work previously presented at the IWCS, where the method had been presented using two observation points, this paper shows further progress in this research and as a proof of its effectiveness, shows its ability in locating PDs using only one observation point. The procedure of the method is briefly described and its performance that overcomes the shortcomings of the traditional PD location methods are summarized. Finally, future related activities are described

Recent Topics in Electromagnetic Compatibility

Recent Topics in Electromagnetic Compatability discusses several topics in electromagnetic compatibility (EMC) and electromagnetic interference (EMI), including measurements, shielding, emission, interference, biomedical devices, and numerical modeling. Over five sections, chapters address the electromagnetic spectrum of corona discharge, life cycle assessment of flexible electromagnetic shields, EMC requirements for implantable medical devices, analysis and design of absorbers for EMC applications, artificial surfaces, and media for EMC and EMI shielding, and much more

Electronic Devices for the Combination of Electrically Controlled Drug Release, Electrostimulation, and Optogenetic Stimulation for Nerve Tissue Regeneration

[ES] La capacidad de las células madre para proliferar formando distintas células especializadas les otorga la potencialidad de servir de base para terapias efectivas para patologías cuyo tratamiento era inimaginable hasta hace apenas dos décadas. Sin embargo, esta capacidad se encuentra mediada por estímulos fisiológicos, químicos, y eléctricos, específicos y complejos, que dificultan su traslación a la rutina clínica. Por ello, las células madre representan un campo de estudio en el que se invierten amplios esfuerzos por parte de la comunidad científica. En el ámbito de la regeneración nerviosa, para modular su desarrollo y diferenciación el tratamiento farmacológico, la electroestimulación, y la estimulación optogenética son técnicas que están consiguiendo prometedores resultados. Es por ello por lo que en la presente tesis se ha desarrollado un conjunto de sistemas electrónicos para permitir la aplicación combinada de estas técnicas in vitro, con perspectiva a su aplicación in vivo. Hemos diseñado una novedosa tecnología para la liberación eléctricamente controlada de fármacos. Esta tecnología está basada en nanopartículas de sílice mesoporosa y puertas moleculares de bipiridina-heparina. Las puertas moleculares son electroquímicamente reactivas, y encierran los fármacos en el interior de las nanopartículas, liberándolos ante un estímulo eléctrico. Hemos caracterizado esta tecnología, y la hemos validado mediante la liberación controlada de rodamina en cultivos celulares de HeLa. Para la combinación de liberación controlada de fármacos y electroestimulación hemos desarrollado dispositivos que permiten aplicar los estímulos eléctricos de forma configurable desde una interfaz gráfica de usuario. Además, hemos diseñado un módulo de expansión que permite multiplexar las señales eléctricas a diferentes cultivos celulares. Además, hemos diseñado un dispositivo de estimulación optogenética. Este tipo de estimulación consiste en la modificación genética de las células para que sean sensibles a la radiación lumínica de determinada longitud de onda. En el ámbito de la regeneración de tejido mediante células precursoras neurales, es de interés poder inducir ondas de calcio, favoreciendo su diferenciación en neuronas y la formación de circuitos sinápticos. El dispositivo diseñado permite obtener imágenes en tiempo real mediante microscopía confocal de las respuestas transitorias de las células al ser irradiadas. El dispositivo se ha validado irradiando neuronas modificadas con luz pulsada de 100 ms. También hemos diseñado un dispositivo electrónico complementario de medida de irradiancia con el doble fin de permitir la calibración del equipo de irradiancia y medir la irradiancia en tiempo real durante los experimentos in vitro. Los resultados del uso de los bioactuadores en procesos complejos y dinámicos, como la regeneración de tejido nervioso, son limitados en lazo abierto. Uno de los principales aspectos analizados es el desarrollo de biosensores que permitiesen la cuantización de ciertas biomoléculas para ajustar la estimulación suministrada en tiempo real. Por ejemplo, la segregación de serotonina es una respuesta identificada en la elongación de células precursoras neurales, pero hay otras biomoléculas de interés para la implementación de un control en lazo cerrado. Entre las tecnologías en el estado del arte, los biosensores basados en transistores de efecto de campo (FET) funcionalizados con aptámeros son realmente prometedores para esta aplicación. Sin embargo, esta tecnología no permitía la medición simultánea de más de una biomolécula objetivo en un volumen reducido debido a las interferencias entre los distintos FETs, cuyos terminales se encuentran inmersos en la solución. Por ello, hemos desarrollado instrumentación electrónica capaz de medir simultáneamente varios de estos biosensores, y la hemos validado mediante la medición simultánea de pH y la detección preliminar de serotonina y glutamato.[CA] La capacitat de les cèl·lules mare per a proliferar formant diferents cèl·lules especialitzades els atorga la potencialitat de servir de base per a teràpies efectives per a patologies el tractament de les quals era inimaginable fins fa a penes dues dècades. No obstant això, aquesta capacitat es troba mediada per estímuls fisiològics, químics, i elèctrics, específics i complexos, que dificulten la seua translació a la rutina clínica. Per això, les cèl·lules mare representen un camp d'estudi en el qual s'inverteixen amplis esforços per part de la comunitat científica. En l'àmbit de la regeneració nerviosa, per a modular el seu desenvolupament i diferenciació el tractament farmacològic, l'electroestimulació, i l'estimulació optogenética són tècniques que estan aconseguint prometedors resultats. És per això que en la present tesi s'ha desenvolupat un conjunt de sistemes electrònics per a permetre l'aplicació combinada d'aquestes tècniques in vitro, amb perspectiva a la seua aplicació in vivo. Hem dissenyat una nova tecnologia per a l'alliberament elèctricament controlat de fàrmacs. Aquesta tecnologia està basada en nanopartícules de sílice mesoporosa i portes moleculars de bipiridina-heparina. Les portes moleculars són electroquímicament reactives, i tanquen els fàrmacs a l'interior de les nanopartícules, alliberant-los davant un estímul elèctric. Hem caracteritzat aquesta tecnologia, i l'hem validada mitjançant l'alliberament controlat de rodamina en cultius cel·lulars de HeLa. Per a la combinació d'alliberament controlat de fàrmacs i electroestimulació hem desenvolupat dispositius que permeten aplicar els estímuls elèctrics de manera configurable des d'una interfície gràfica d'usuari. A més, hem dissenyat un mòdul d'expansió que permet multiplexar els senyals elèctrics a diferents cultius cel·lulars. A més, hem dissenyat un dispositiu d'estimulació optogenètica. Aquest tipus d'estimulació consisteix en la modificació genètica de les cèl·lules perquè siguen sensibles a la radiació lumínica de determinada longitud d'ona. En l'àmbit de la regeneració de teixit mitjançant cèl·lules precursores neurals, és d'interés poder induir ones de calci, afavorint la seua diferenciació en neurones i la formació de circuits sinàptics. El dispositiu dissenyat permet obtindré imatges en temps real mitjançant microscòpia confocal de les respostes transitòries de les cèl·lules en ser irradiades. El dispositiu s'ha validat irradiant neurones modificades amb llum polsada de 100 ms. També hem dissenyat un dispositiu electrònic complementari de mesura d'irradiància amb el doble fi de permetre el calibratge de l'equip d'irradiància i mesurar la irradiància en temps real durant els experiments in vitro. Els resultats de l'ús dels bioactuadors en processos complexos i dinàmics, com la regeneració de teixit nerviós, són limitats en llaç obert. Un dels principals aspectes analitzats és el desenvolupament de biosensors que permeteren la quantització de certes biomolècules per a ajustar l'estimulació subministrada en temps real. Per exemple, la segregació de serotonina és una resposta identificada amb l'elongació de les cèl·lules precursores neurals, però hi ha altres biomolècules d'interés per a la implementació d'un control en llaç tancat. Entre les tecnologies en l'estat de l'art, els biosensors basats en transistors d'efecte de camp (FET) funcionalitzats amb aptàmers són realment prometedors per a aquesta aplicació. No obstant això, aquesta tecnologia no permetia el mesurament simultani de més d'una biomolècula objectiu en un volum reduït a causa de les interferències entre els diferents FETs, els terminals dels quals es troben immersos en la solució. Per això, hem desenvolupat instrumentació electrònica capaç de mesurar simultàniament diversos d'aquests biosensors i els hem validat amb mesurament simultani del pH i la detecció preliminar de serotonina i glutamat.[EN] The stem cells' ability to proliferate to form different specialized cells gives them the potential to serve as the basis for effective therapies for pathologies whose treatment was unimaginable until just two decades ago. However, this capacity is mediated by specific and complex physiological, chemical, and electrical stimuli that complicate their translation to clinical routine. For this reason, stem cells represent a field of study in which the scientific community is investing a great deal of effort. In the field of nerve regeneration, to modulate their development and differentiation, pharmacological treatment, electrostimulation, and optogenetic stimulation are techniques that are achieving promising results. For this reason, we have developed a set of electronic systems to allow the combined application of these techniques in vitro, with a view to their application in vivo. We have designed a novel technology for the electrically controlled release of drugs. This technology is based on mesoporous silica nanoparticles and bipyridine-heparin molecular gates. The molecular gates are electrochemically reactive and entrap the drugs inside the nanoparticles, releasing them upon electrical stimulus. We have characterized this technology and validated it by controlled release of rhodamine in HeLa cell cultures. For combining electrostimulation and controlled drug release we have developed devices that allow applying the different electrical stimuli in a configurable way from a graphical user interface. In addition, we have designed an expansion module that allows multiplexing electrical signals to different cell cultures. In addition, we have designed an optogenetic stimulation device. This type of stimulation consists of genetically modifying cells to make them sensitive to light radiation of a specific wavelength. In tissue regeneration using neural precursor cells, it is interesting to be able to induce calcium waves, favoring the cell differentiation into neurons and the formation of synaptic circuits. The designed device enable the obtention of real-time images through confocal microscopy of the transient responses of cells upon irradiation. The device has been validated by irradiating modified neurons with 100 ms pulsed light stimulation. We have also designed a complementary electronic irradiance measurement device to allow calibration of the irradiator equipment and measuring irradiance in real time during in vitro experiments. The results of using bioactuators in complex and dynamic processes, such as nerve tissue regeneration, are limited in an open loop. One of the main aspects analyzed is the development of biosensors that would allow quantifying of specific biomolecules to adjust the stimulation provided in real time. For instance, serotonin secretion is an identified response of neural precursor cells elongation, among other biomolecules of interest for the implementation of a closed-loop control. Among the state-of-the-art technologies, biosensors based on field effect transistors (FETs) functionalized with aptamers are promising for this application. However, this technology did not allow the simultaneous measurement of more than one target biomolecule in a small volume due to interferences between the different FETs, whose terminals are immersed in the solution. This is why we have developed electronic instrumentation capable of simultaneously measuring several of these biosensors, and we have validated it with the simultaneous pH measurement and the preliminary detection of serotonin and glutamate.Monreal Trigo, J. (2023). Electronic Devices for the Combination of Electrically Controlled Drug Release, Electrostimulation, and Optogenetic Stimulation for Nerve Tissue Regeneration [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19384

Fast Simulation of Electromagnetic Transients in Power Systems:Numerical Solvers and their Coupling with the Electromagnetic Time Reversal Process

The development of modern and future power systems is associated with the definition of new approaches for their simulation, control, and protection. To give an example, the increasing connection of massive renewable energy conversion systems is justifying the integration of DC infrastructures (eventually, multi-terminal HVDC) in the current AC power grids. Furthermore, the existing passive distribution networks are evolving by integration of decentralized and intermittent generation units which results in Active Distribution Networks (ADNs). As a consequence, complex power system topologies are emerging requiring adequate simulation tools capable to reproduce, possibly in real-time, their dynamic behavior. In this context, future operation/protection practices of power networks might rely on the availability of chip-scale real-time simulators (RTS) that will enable the implementation of efficient protection/fault location processes that, in principle, should be capable to comply with the restrictive constraints associated with these complex systems. Within this context, the work presented in the thesis contributes to the integration of new concepts of the fault location in AC/DC systems that can be deployed in chip-scale real-time simulation hardware represented by Field Programmable Gate Arrays (FPGAs). The development of the proposed fault location platform is done in two steps. First, an original fault location method based on the Electromagnetic Time Reversal (EMTR) theory is proposed. The proposed method is validated for the case of various power networks topologies and its performance is assessed. Compared to the existing fault location methods, the proposed approach is suitably applicable to different topologies including MTDCs and ADNs. Next, a new automated FPGA-based solver for RTS is proposed. The developed FPGA-RTS uses a specific automated procedure to couple the simulation platform with an offline simulation environment (EMTR-RV) without the need for Hardware Description Language (HDL). It is able to simulate both power electronics converters and power system grids and thanks to the use of particular parallel computational algorithms, it can accurately simulate, in real-time, Electromagnetic Transient (EMT) phenomena taking place in power converters and travelling wave propagation along multi-conductor transmission lines within very small simulation time steps (in the order of some hundreds of nanoseconds). To overcome the limitations associated with the Fixed Admittance Matrix Nodal Method (FAMNM), a method to assess the optimal value of the parameter of the Associated Discrete Circuit (ADC) switch model used by FAMNM is proposed. Finally, a specific application of the developed FPGA-RTS is explored for the development of a fault location platform by leveraging the EMTR theory. To this end, the proposed EMTR-based fault location method is integrated with the FPGA-RTS to develop an efficient fault location platform. Thanks to the fast EMT simulation capability of the FPGA-RTS, the developed fault location platform is able to estimate the accurate fault location within very short time scales. Moreover, the developed platform is compatible with the constraints characterizing complex topologies such as MTDC networks (e.g., the ultra-fast operation of the protection systems). The developed fault location platform is validated by making reference to an MTDC grid and an ADN, and it is shown to exhibit remarkable fault location accuracy as well as robustness against uncertainties such as fault type, the presence of noise, measurement systems delay, and fault impedance

Locating transient disturbance sources and modelling their interaction with transmission lines:use of electromagnetic time reversal and asymptotic theory

This thesis deals with the application of electromagnetic time reversal to locating transient disturbance sources and the use of the asymptotic theory for the modelling of their interaction with transmission lines. We demonstrate that the time-of-arrival, which is one of the most commonly used methods to locate lightning discharges, can be seen as a special case of time reversal. The problem of a lossy ground that affects the propagation of electromagnetic transient fields generated by a lightning strike is addressed by proposing three different back-propagation models and comparing their performances in terms of location accuracy. Two sets of simulations are carried out to evaluate the accuracy of the proposed approaches. The first set of simulations is performed using numerically-generated fields and the proposed algorithm is shown to yield very good results even if the soil is not perfectly conducting. In particular, it is shown that considering a model in which losses are inverted in the back-propagation yields theoretically exact results for the source location. We also show that a lack of access to the complete recorded waveforms may lead to higher location errors, although the computed errors are found to be within the range of performance of the present LLSs. A second set of simulations is performed using the sensor data reported by the Austrian Lightning Location System (ALDIS). The locations obtained by way of the EMTR method using only the available sensor data (amplitude, arrival time and time-to-peak), are observed to be within a few kilometres of the locations supplied by the LLS. The possible sources of this discrepancy are discussed in the thesis. The second part of this document deals with the computation of the current induced in a line due to an external electromagnetic field. We derive high-frequency expressions for the current induced along a multiconductor line by an external plane wave, in which the effects of the terminals of the line are modelled by matrices of scattering and reflection coefficients. Different approaches are proposed to compute the coefficients that feed the analytical expression for the current induced along the line. Using an iterative method, mathematical expressions are derived, for the particular case of open-circuit lines. For the general case of arbitrary line terminations, an approach using auxiliary short lines, solved with a numerical solver is proposed. At low frequencies, the proposed three-term formulation can be adapted to lossy lines and analytical expressions for the coefficients, providing a new and elegant formulation for the classical transmission line theory. The proposed theory is validated through numerical simulations and experiments and is found to be much more effective than the traditional full-wave approaches in terms of memory requirements and computational times. The asymptotic theory is also applied to a lumped source excitation, according to a procedure analogous to the one for a plane wave excitation. A method for the determination of matrices of coefficients is also presented

Electronics Emulation for Real-Time Fault Location in Power Systems

This research presents a high-speed hardware platform dedicated to emulate electrical power networks for the fault location. The solution implements an algorithm based on the Electromagnetic Time-Reversal (EMTR) principle, which allows locating faults in various network types and topologies. Although the technique is highly robust and accurate, its processing is complex and time consuming if solved with classical digital approaches. Therefore, a dedicated computation platform optimized on the processing speed was developed in order to allow its real-time implementation and make it compatible with smart-grids. Two different power network modelling approaches are presented. The first one is based on a finite element representation of the distributed parameters transmission line. The lossless line, initially characterized by a per-unit length inductance and capacitance, is replaced by a series of identical ladder connected inductor-capacitor (LC) elements. The second model is based on the general solution of the telegrapher's equations describing the signals propagated along the transmission line. In this method, the travelling waves' propagation taking place in the line is simulated with cascaded discrete-time delay elements. A possible implementation by means of analog circuits is then presented for each line model. The discretized parameters LC line is simulated by transconductance-capacitor, also called gyrator-C or gm-C topologies, more suitable for microelectronic implementation. On the other hand, the discrete-time delay element of the second method is implemented by switched-capacitor (SC) circuits. The processing time associated to each method can be scaled down according to the microelectronic parameters of the LC line, or by increasing the sampling frequency of the discrete-time model. Through this time scaling, the hardware emulation allows a fault location within duration of up to a hundred times shorter than with classical digital implementations of similar accuracy. The impact of non-ideal effects associated to the microelectronic implementation, such as the CMOS active elements finite gain, offset and dynamic range, or the switched-capacitor charge injection, etc., is evaluated for each model. Associated design constraints are then derived in order to ensure a given fault location accuracy, similarly to that of classical digital methods. Since the switched-capacitor model is characterized by higher robustness and accuracy than the LC line, it is therefore preferred for a silicon implementation. Results obtained after a CMOS AMS 0.35um process implementation have shown that the discrete-time model allows a fault location within 160ms, versus 6s in a classical digital method, with similar resolution (1%). The speed improvement obtained through the presented method is essential, potentially allowing real-time fault management in power grids. Finally, the impact of the magnitude quantization on the line model, offering perspectives of full digital implementations, is evaluated. A possible extension of the model for the simulation of interconnected or multi-conductor lines is also discussed

Implementation-level analysis of cryptographic protocols and their applications to e-voting systems

Formal verification of security properties of both cryptographic operations, such as encryption, and protocols based on them, such as TLS, has been the goal of a substantial research effort in the last three decades. One fundamental limitation in the verification of these security properties is that analyses are typically carried out at the design level and hence they do not provide reliable guarantees on the implementations of these operations/protocols. To overcome this limitation, in this thesis we aim at establishing formally justified cryptographic guarantees directly at the implementation level for systems that are coded in Java and use cryptography. Our approach is based on a general framework for the cryptographic verification of Java programs (the CVJ framework) which formally links cryptographic indistinguishability properties and noninterference properties. In this way, it enables existing tools that can check standard noninterference properties, but a priori cannot deal with cryptography, to also establish cryptographic privacy properties for Java systems. The CVJ framework is stated and proven for a Java-like formal language which however does not cover all the data types and features commonly used in Java programs. Moreover, the framework originally supports only one cryptographic operation, namely public-key encryption. The first contribution of this thesis is hence to extend and to instantiate the CVJ framework in order to make it more widely applicable. We extend the underlying formal language with some features of Java which have not been captured yet, such as concurrency, and we restate and prove all the results of the framework to carry them over into this extended language. We then further instantiate the framework with additional cryptographic operations: digital signatures and public-key encryption, both now also including a public-key infrastructure, (private) symmetric encryption, and nonce generation. The methods and techniques developed within the CVJ framework are relevant and applicable independently of any specific tool employed. However, to illustrate the usefulness of this approach, we apply the framework along with two verification tools for Java programs, namely the fully automated static checker Joana and the interactive theorem prover KeY, to establish strong cryptographic privacy properties for systems which use cryptography, such as client-server applications and e-voting systems. In this context, the second major contribution of this thesis is the design, the implementation, and the deployment of a novel remote voting system called sElect (secure/simple elections). sElect is designed to be particularly simple and lightweight in terms of its structure, the cryptography it uses, and the user experience. One of its unique features is a fully automated procedure which does not require any user interaction and it is triggered as soon as voters look at the election result, allowing them to verify that their vote has been properly counted. The component of sElect which provides vote privacy is implemented in Java such that we can establish cryptographic guarantees directly on its implementation: by combining the techniques of the CVJ framework with a hybrid approach for proving noninterference, we are able to show that the Java implementation ensures strong cryptographic privacy of the votes cast with our proposed voting system. sElect is therefore the first full-fledged e-voting system with strong cryptographic security guarantees not only at the design level, but also on its implementation

New Zealand Working For Families programme: Methodological considerations for evaluating MSD programmes

The methodological review is the second part of the evaluation research commissioned by the Ministry of Social Development (MSD) in 2005 to help in the preparation of the evaluation of the Working for Families (WFF) programme. This review enumerates the key evaluation questions identified by MSD as central to their policy concerns and considers how the features of WFF could affect evaluation. It details the methodological and data requirements that must be addressed in order to meet the four key evaluation objectives, namely: (1) tracking and evaluating the implementation and delivery of WFF (2) identifying changes in entitlement take-up and reasons for it (3) establishing the impact of WFF on employment-related outcomes (4) assessing WFF’s effect on net income and quality of life more generally. The methodological review complements the literature review by reviewing evaluations from around the world that are pertinent to WFF. An overview of evaluation methods is provided, concentrating on particular issues that arise within the WFF context. Section 2 focuses on implementation and delivery. Section 3 covers the issues related to take-up and entitlement and their evaluation. Section 4 discusses the evaluation methodologies that can be used in evaluating programmes such as WFF and introduces the data requirements they entail. Making work pay is the focus of section 5. Finally, section 6 examines hardship and poverty, living standards and wellbeing.

WDM optical access network for full-duplex and reconfigurable capacity assignement based on Polmux technique

[EN] We present a novel bidirectional WDM-based optical access network featuring reconfigurable capacity assignment. The architecture relies on the PolMUX technique allowing a compact, flexible, and bandwidth-efficient router in addition to source-free ONUs and color-less ONUs for cost/complexity minimization. Moreover, the centralized architecture contemplates remote management and control of polarization. High-quality transmission of digital signals is demonstrated through different routing scenarios where all channels are dynamically assigned in both downlink and uplink directions.This work was supported by the national project TEC2011-26642 funded by the Ministerio de Economía y Competitividad. Also, The authors wish to acknowledge the financial support given by the Generalitat Valenciana under the Research Excellency Award Program GVA PROMETEO 2013/012 Next Generation Microwave Photonic technologies.Mora Almerich, J.; Ortega Tamarit, B.; Grassi Marangione, F.; Capmany Francoy, J. (2014). WDM optical access network for full-duplex and reconfigurable capacity assignement based on Polmux technique. Photonics. 1:503-515. https://doi.org/10.3390/photonics/1040503S503515

Eficiência da recuperação de embriões e os efeitos de consecutivas colheitas sobre o aparelho reprodutor de doadoras da espécie caprina

The purpose of this trial was to compare the efficiency and effect of consecutive embryo recoveries by three different methods (T1 - transcervical; T2 laparoscopy and T3 laparotomy) on the reproductive activity of goat donors. Ten goats were allocated into each treatment (T1, T2 and T3) and submitted to three consecutive embryo recoveries. These were performed 56 days apart. The superovulation begun on 8th day of oestrus synchronization and all goats received 250 UI of porcine FSH splited into eight decreasing dosages at 12 hours intervals. The embryo recovery took place on the 5th or 6th day from the last mating. Fifty-six days after the third recovery of embryos, the animals were sacrified and the genital tract was evaluated. The time spent to recovery the embryos was 21min 32sec; 37min 14sec and 56min 22sec, respectively to T1; T2 and T3 (p<0.01). T3 showed the highest recovery rate of washing solution (83.7%), followed by T2 (72.2%) and T1 (64.3%) (p<0.05). Embryo recovery rate had as mean values, 57.1; 81.1 and 27.3%, respectivily to T1, T2 and T3. The variation ranged between 0 and 100%. Several factors affected the embryo recovery rate, such as the presence of demised corpora lutea, the ovulation rate and the presence of adhesions in the genital tract. Nonetheless, embryo recevery rate was acceptable in all treatments. The T1 caused eversion of endometrium and adherence between the uterine horn and epiploon in one animal, the T2 caused 30, 40 and 60% of endometrium eversion and 10, 10 and 70% adherence on genital tract, respectively, for the first, second and third embryo recovery. The T3 caused 80% of adherence on genital tract after the first embryo recovery and 100% after the second. It is possible to use the methods T1 and T2 to recovery embryos in goats.O objetivo deste experimento foi comparar a eficiência e o efeito de consecutivas colheitas de embriões, por três diferentes métodos (transcervical-T1, laparoscopia-T2 e laparotomia-T3), sobre a atividade reprodutiva de doadoras da espécie caprina. Utilizaram-se 10 cabras em cada método (T1, T2 e T3), sendo as colheitas de embriões repetidas três vezes consecutivas, nas mesmas fêmeas, com intervalo de 56 dias. As fêmeas foram sincronizadas com esponjas vaginais impregnadas com 60 mg de acetato de medroxiprogesterona durante 10 dias e 100 µg de cloprostenol aplicados pela via IM no oitavo dia da sincronização. No 8º dia, iniciou-se a superovulação com 250 UI de FSH de origem suína, divididas em oito doses decrescentes, aplicadas em intervalo de 12 horas. As fêmeas foram acasaladas e as colheitas de embriões realizadas no 5º ou 6º dia após a última cobertura. Após 56 dias da terceira colheita de embriões, foram realizados o abate e a necrópsia das doadoras. O tempo necessário para a colheita de embriões em cada método foi de 21 minutos e 32 segundos; 37 minutos e 14 segundos e 56 minutos e 22 segundos, respectivamente, para T1, T2 e T3 (p<0,01). A maior taxa de recuperação da solução de lavagem foi no T3 (83,7%), seguido por T2 (72,2%) e T1 (64,3%) (p<0,05). As taxas médias de recuperação dos embriões foram 57,1; 81,1 e 27,3% para T1, T2 e T3, respectivamente, com variação entre 0-100%. A taxa de recuperação de embriões sofreu influência de vários fatores, como a presença de corpos lúteos regredidos, a taxa de ovulação e a presença de aderências no sistema genital, mas, isoladamente, a taxa de recuperação de embriões foi satisfatória nos três métodos. O T1 causou eversão do endométrio e aderência entre o corno uterino e o epíploo em uma única fêmea, o T2 causou eversão do endométrio em 30%, 40% e 60% e aderências do sistema genital em 10%, 10% e 70% das fêmeas à 1ª, 2ª e 3ª colheitas, respectivamente. O T3 causou aderências no sistema genital em 80% das doadoras após a primeira e 100% após a segunda colheita. O T1 e o T2 permitem o uso de doadoras em repetidas colheitas de embriões, o que não ocorre com o T3, que causa aderências no sistema genital e órgãos circunvizinhos em 100% dos casos