A series of impedance-mismatch experiments with aluminum-gold targets has been performed. These experiments are used to probe the equation of state (EOS) of gold at high pressure. By measuring the shock breakout time from the target rear surface, the shock trajectory is determined and found to be in good agreement with equation of state predictions. In addition, temperatures derived from temporally resolved luminescence measurements of the shocked target rear surface are compared with two different equation of state theoretical models. Our results indicate that whereas the SESAME (from Los Alamos National Laboratory) EOS seems to overestimate the shock temperature, the equation of state of gold which incoporated both the solid and liquid phases gives much closer agreement with observations. The measurements of gold at a shock pressure of ~ 6 Mbar and temperature of ~ 17500 K also represent the first study of gold under shock melting. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Orientador: Sandra dos Santos Padula / Banca:Eduardo de Moraes Gregores / Banca: Fernando Silveira Navarra / Banca: Lauro Tomio / Banca: Marcelo Gameiro Munhoz / Resumo: Apresentamos resultados de um estudo sistemático do papel das equações de estado no modelo hidrodinâmico. Simulamos colisões Au+Au para duas energias do Relativistic Heavy Ion Collider (RHIC), 130 e 200 GeV por nucleon, para compararmos os nossos resultados aos dados experimentais desse acelerador. Utilizando as mesmas condições iniciais e mecanismo de desacoplamento, analisamos os efeitos de diferentes equações de estado sobre alguns observáveis físicos através dos resultados de suas respectivas evoluções hidrodinâmicas. Os observáveis de interesse nesse trabalho são o espectro de partículas, o fluxo elíptico, usado para estudar o impacto das equações de estado nas anisotropias do estado final, e os parâmetros de raio estimados através do efeito Hambury-Brown-Twiss (HBT). São estudadas três diferentes equações de estado, cada uma enfocando diferentes características do sistema formado, tais como a natureza da transição de fase, densidades de estranheza e bariônica. Essas diferentes equações de estado implicam em diferentes respostas hidrodinâmicas sobre os observáveis. Embora as três equações de estado utilizadas no cálculo descrevam razoavelmente bem os dados experimentais, as diferenças observadas são pequenas, demonstrando pouca sensibilidade dos resultados finais a cada escolha particular de equação de estado / Abstract: We present results of a systematic study of the role of the equation of state in the hydrodynamic model. We simulate Au+Au collisions for two energies of the Relativistic Heavy Ion Collider (RHIC), 130 and 200 GeV per nucleon, in order to compare our results to the collider data. By using the same initial conditions and freeze-out scenario, we analysed the effects of different equations of state on some physical observables trough the results of their respective hydrodynamical evolution. The observables of interest investigate here are particle spectra, elliptic flow, used to study the impact of the equations of state on final state anisotropies, and radii parameters estimated by the Hambury-Brown-Twiss effect (HBT). Three different types of equation of state are studied, each focusing on different features of the system, such as the nature of the phase transition, strangeness and baryon densities. These different equations of state imply different hydrodynamic responses on the observables. Although the three equations of state used in the calculations describe the data reasonably well, some small differences are observed, showing weak sensitivity of the results on the particular choice of equation of state / Doutor

Thesis (MSc (Physics))--Stellenbosch University, 2008. / Nuclear physics can be applied in various ways to the study of neutron stars. This thesis reports on one such application, where the relativistic mean-field approximation has been employed to calculate the equations of state of matter in the neutron star interior. In particular the equations of state of nuclear and neutron star matter of the NL3, PK1 and FSUGold parameter sets were derived. A survey of available literature on neutron stars is presented and we use the derived equations of state to reproduce the properties of saturated nuclear matter as well as the mass-radius relationship of a static, spherical symmetric neutron star. Results are compared to published values of the properties of saturated nuclear matter and to available observational data of the mass-radius relationship of neutron stars.

La connaissance des propriétés thermodynamiques et des diagrammes de phases des composés fluorés est indispensable pour le dimensionnement et l'optimisation des systèmes thermodynamiques. Les applications sont nombreuses : réfrigération, récupération de chaleur (ORC), pompe à chaleur, climatisation automobile. Du fait des contraintes environnementales (la F-gaz pour l'UE) liées au fait que les fluides actuellement utilisés doivent être inoffensifs vis-à-vis de la couche d'ozone mais aussi posséder un pouvoir de réchauffement climatique bas (GWP CO2=1, valeur de référence), les chimistes doivent développer de nouvelles molécules qui répondent à ce nouveau cahier des charges. Actuellement, ils ont mis au point des fluides de la famille des HFO dont le plus célèbre est le HFO1234yf. Son GWP est faible (4) tout comme celui de ses principaux isomères, le HFO1234ze et le HFO1234zd. Si le fluide pur ne convient, des mélanges (blends) doivent être élaborés. Si le fluide pur ne convient pas pour les applications souhaitées, des mélanges doivent être élaborés.L'objectif de cette thèse est d'étudier plusieurs HFOs en corps purs et en mélanges et de développer/comparer des modèles thermodynamiques permettant de prédire les diagrammes de phases et les densités de ces fluides. Ces modèles doivent pouvoir être transposables vers l'industrie. Le CTP dispose de plusieurs équipements permettant d'acquérir des données expérimentales. Le densimètre à tube vibrant sera utilisé pour acquérir des données de masse volumique, et une cellule d'équilibre entre phase (technique statique-analytique) pour acquérir des données d'équilibre liquide vapeur. Les équations d'état cubiques seront utilisées pour le traitement des données. Une nouvelle équation d'état plus précise pour la prédiction des masses volumiques sera présentée. Une comparaison en termes de description des diagrammes de phases et des propriétés volumétriques sera également effectuée. / The knowledge of the thermodynamic properties and phase diagrams of fluorinated compounds is essential for the design and optimization of thermodynamic systems. There are many applications: refrigeration, organic Rankine cycle (ORC), heat pump, and air conditioning systems. Due to the environmental constraints (F-gaz for the EU) related to the fact that the fluids being used must be harmless to the ozone layer, but also with a low global warming potential (GWP CO2 = 1 reference value), the chemists must develop new molecules responding to these constraints. Today, they have developed fluids called HFOs whose most famous is the HFO1234yf, with a low GWP (4), along with his isomers HFO1234ze and HFO1234zd. If the pure fluid is not suitable for the applications, blends should be developed instead. The objective of these theses is to study several HFOs, in pure compounds and mixtures and develop / compare thermodynamic models in order to predict the phase diagram and density of these fluids. These models should be transferable to industry. The CTP has several equipments to acquire experimental data. The vibrating-tube densimeter will be used to acquire density data, and equilibrium cell (static-analytic method) to acquire liquid-vapor equilibrium data. The cubic equations of state will be used for data treatment. A new equation of state more accurate for density prediction will be presented. A comparison in terms of phase diagrams and density prediction will be carried out.

Orientador: Denis José Schiozer / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-18T02:24:49Z (GMT). No. of bitstreams: 1 Mello_SamuelFerreirade_M.pdf: 5532119 bytes, checksum: bd96341bedac10788b77f2035e64d4b3 (MD5) Previous issue date: 2011 / Resumo: O aumento significativo do volume potencial de petróleo se deve às descobertas recentes de reservatórios de petróleo localizados em profundidades de camada pré-sal que contém CO2, em alguns casos, em quantidade superior a 10% e frações voláteis, em condições de grande desvio do comportamento dos gases ideais. A literatura sugere que nesses casos é necessário o uso de modelos composicionais de simulação de reservatórios. Neste trabalho procurou-se através de estudos do comportamento de fluidos diagnosticar fatores decisivos do tratamento de fluidos para a aplicação confiável da simulação composicional em reservatórios de petróleo similares aos da camada pré-sal. Ênfase especial foi dada ao estudo do comportamento de fases e à simulação de método de recuperação melhorada de óleo baseados na injeção de CO2. Para isto, foram obtidos da literatura um modelo geológico de reservatório heterogêneo, dados de permeabilidade relativa e dados PVT da caracterização de óleos leves (acima de 20º API de densidade) e ricos em CO2 (3% a 20% da fração molar). Foi feita uma modelagem pelo ajuste termodinâmico de equações de estado aplicadas ao petróleo, onde foram testadas diferentes representações termodinâmicas (de 5 a 24 componentes), dois diferentes métodos de ajustes de equações de estado e dois modelos geológicos. Os resultados obtidos foram analisados e comparados em diferentes combinações para o estudo da sensibilidade de parâmetros críticos de fluido para a simulação composicional, como a escolha de pseudocomponentes, a escolha de equações de estado e a escolha de técnicas de ajuste de equações de estado. Os resultados ressaltam a importância não só da qualidade de dados experimentais adequados, como da escolha cautelosa de modelos teóricos termodinâmicos adequados, de técnicas de ajuste de dados experimentais e do uso cuidadoso da pseudoização. O estudo conclui que a alteração indiscriminada em qualquer uma destas variáveis pode comprometer a confiabilidade de um modelo de simulação de reservatórios. O estudo conclui que diferentes técnicas de regressão de equações de estado não são equivalentes e também mostra que a relação entre a pseudoização e a redução do tempo computacional não é direta. Os resultados deste trabalho são importantes para estudos futuros de simulação composicional / Abstract: The Brazilian expected oil potential has increased substantially after the discoveries of subsalt located deep oil reservoirs and they are regarded with huge economic importance for Brazil. Some of these fields contain above 10% molar CO2 and volatile fractions, submitted to conditions that differ greatly from that described by ideal gas models. Compositional reservoir simulation is fundamental for the description of these phenomena. Although this technique improves the reservoir management, the modeling of fluid data is needed due to computational limitation and it adds uncertainties that affect the quality of the compositional simulation and are not studied very often. The objective of this work is to identify key factors in order to allow the reliable application of compositional simulation to petroleum reservoir analogous to the Brazilian subsalt reservoirs. Special highlighting was given to the phase behavior and simulation of enhanced oil recovery methods based on the CO2 injection applied to heterogeneous reservoirs. This required the acquisition from literature of a heterogeneous reservoir geological model, of a singular set of relative permeability data and of several sets of PVT data characterizing light oils (over 20º API gravity) that are also CO2 enriched (from 3% to 20% of molar fraction). From these PVT sets of data it was necessary to perform the thermodynamic match of equations of state applied to complex hydrocarbons mixtures. An oil with different extended and lumped thermodynamic versions was tested with two different equations of state matching methods from literature and two different geological models. The results obtained were analyzed and compared under different combinations for the sensitivity study of critical fluid parameters for the compositional simulation. This work emphasizes the importance not only of experimental data quality, but also of the equation of state choice, regression method choice and the careful use of lumping. The study concludes that the indiscriminate alteration in any of these variables may harm the model reliability of reservoir simulation. The study concludes that different PVT tuning techniques are not equivalent and also shows that the relation between lumping and computational time reduction is not direct. The results of this work are important for future compositional simulation studies / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

Orientadores: Antonio José de Almeida Meirelles, Marcelo Lanza / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T03:18:50Z (GMT). No. of bitstreams: 1 FollegattiRomero_LuisAlberto_D.pdf: 1459960 bytes, checksum: 156264e9c23b646b44f0d820a5df70c7 (MD5) Previous issue date: 2011 / Resumo: Os esteres etilicos de acidos graxos (biodiesel) podem ser produzidos atraves da reacao da transesterificacao ou etanolise. Os reagentes (oleo vegetal e etanol), normalmente com o alcool adicionado em excesso para garantir uma maior conversao em esteres etilicos de acidos graxos (FAEEs), formam um mistura heterogenea com miscibilidade parcial, sendo necessario nesta etapa realizar agitacao no interior do reator para melhorar a difusao de componentes entre as fases formadas. Durante a reacao, a mistura inicial e transformada em outras duas fases, uma rica em esteres etilicos e outra rica em glicerina, com o etanol em excesso distribuindo¿se entre as duas fases. Finalmente, os esteres resultantes devem ser separados da glicerina, do alcool em excesso e do catalisador, via decantacao ou centrifugacao, seguido de um processo de lavagem com agua (purificacao) para eliminar os saboes, componentes graxos, restos de catalisador, alcool e glicerina. Algumas das dificuldades da producao industrial de biodiesel etilico estao associadas ao desconhecimento das composicoes das fases durante o processo reacional e a problemas adicionais na separacao de fases em funcao da maior presenca de etanol em ambas as fases resultantes da reacao. Por esta razao, torna¿se necessario o estudo do equilibrio liquido¿liquido das misturas envolvidas nas diferentes etapas do processo de producao deste biocombustivel. O presente trabalho teve como objetivo a determinacao de dados de equilibrio liquido¿liquido para uma serie de sistemas pseudo¿binarios e multicomponentes envolvendo oleos vegetais, FAEEs, etanol, glicerol e agua e a modelagem do equilibrio de fases destes sistemas empregando a equacao de estado CPA EoS (Cubic¿Plus¿Association Equation of State) e o modelo NRTL. Em uma primeira etapa, foi estudada a solubilidade dos reagentes: oleos vegetais + etanol em uma faixa de temperatura de 298,15 a 333,15 K. Estes dados foram correlacionados satisfatoriamente usando o modelo NRTL. Nesta modelagem, o oleo vegetal foi tratado como um pseudocomponente. A validade desta hipotese foi demonstrada em um trabalho subsequente sobre a particao dos triacilglicerois nas fases de equilibrio (oleosa e alcoolica) em misturas compostas de oleos vegetais + etanol para a producao de biodiesel. Na segunda etapa desta tese foram investigados sistemas ternarios relacionados com o periodo intermediario do processo reacional de producao de biodiesel: FAEEs + etanol + glicerol a 323,15 e 353,15 K. Estes dados foram correlacionados corretamente com a CPA EoS, aproveitando¿se a transferencia dos parametros usados num trabalho anterior na predicao do equilibrio liquido¿vapor de sistemas binarios compostos por esteres etilicos ou esteres metilicos de acidos graxos em uma faixa de pressao de 5332,9¿13332,23 Pa. Sistemas relacionados com a etapa de lavagem do biodiesel tambem foram investigados: FAEEs + etanol + agua a temperaturas entre 298,15 e 333,15 K. Os resultados mostraram que a lavagem com agua e uma maneira muito eficaz de recuperacao de etanol da fase rica em esteres gerados. Estes dados de equilibrio tambem foram correlacionados com a CPA EoS e os desvios medios apresentaram valores menores que 3,0 % / Abstract: Fatty acid ethyl esters (biodiesel) are produced through the transesterification reaction or ethanolysis. Reagents (vegetable oil and ethanol), usually with alcohol in excess to ensure a higher conversion into fatty acid ethyl esters (FAEEs), form a heterogeneous mixture with partial miscibility; in this step it is necessary to carry out agitation inside the reactor to improve component diffusion between the phases formed. During the course of the reaction, the initial mixture is transformed into two phases: an ethyl esters¿rich phase and the other a glycerin¿rich phase, with excess ethanol distributed in both phases. Finally, the esters must be separated from the glycerin, excess alcohol and catalyst, via decanting or centrifuging, followed by a washing process with water (purification) to remove the soaps, fatty compounds, residual catalyst, glycerin and alcohol. Some of the difficulties of industrial production of ethyl biodiesel are associated to the limited information about the phase compositions during the reaction process and additional problems during phase separations due to the high presence of ethanol in the two phases resulting of the reaction. For this reason, it becomes necessary studying the liquid¿liquid phase equilibrium of the mixtures involved in different steps of the production of this biofuel. The objective of this work was to determine the liquid-liquid equilibria data for several pseudo¿binary and multicomponent systems containing vegetable oils, FAEEs, ethanol, glycerol and water and the phase equilibrium modeling using the CPA EoS (Cubic¿Plus¿Association Equation of State) and NRTL model. In a first stage, the solubility of reagents (vegetable oil + ethanol) was studied in the temperature range from 298.15 to 333.15 K. These data were satisfactorily correlated using the NRTL model. In this model, the vegetable oil was treated as a pseudocomponent. The validity of this hypothesis was demonstrated in a subsequent work about the partition data of triacylglycerols between the two immiscible liquid equilibrium phases (oil and alcoholic) in vegetable oil + ethanol mixtures for biodiesel production. In the second stage of this thesis were investigated ternary systems related with the reaction process intermediate step of biodiesel production: FAEEs + ethanol + glycerol at 323.15 and 353.15 K. These data were correlated correctly with the CPA EoS, taking advantage of the transferability of the CPA parameters used in a previous work for predicting the vapor¿liquid equilibrium of binary systems composed of fatty acid ethyl or methyl esters in the pressure range 5332.9 ¿ 13332.23 Pa. Ternary systems related with the biodiesel washing process were also investigated: FAEEs + ethanol + water within the temperature range of 298.15 and 333.15 K. These results indicate that washing with water is a very effective way of extracting ethanol from the ester phase generated. These equilibrium data were also correlated with the CPA EoS and the mean deviation values were lower than 3.0 % / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

La demande en énergies fossiles a connu une forte croissance au cours du vingtième siècle et représente aujourd'hui 80% de la consommation énergétique mondiale. Pour répondre à la demande, les industries pétrolières et gazières s'orientent vers de nouvelles sources. 40% des réserves de gaz contiennent un pourcentage important (jusqu'à 20%) de gaz acides (dioxyde de carbone et sulfure d'hydrogène). La production de ces gaz à forte teneur en gaz acides représente un défi pour les industries, étant donné la toxicité du sulfure d'hydrogène et la forte probabilité de corrosion des pipelines en présence d'eau (naturellement produite avec le gaz naturel). D'autre part, l'utilisation des énergies fossiles conduit au changement climatique avec des émissions importantes de dioxyde de carbone dans l'atmosphère. Le captage et le stockage du CO2 semble être un procédé prometteur. De l'eau est souvent présente lors du transport du gaz naturel et du CO2 capturé. Lors des étapes de production et de transport, les conditions de température et de pression sont sujettes au changement. La condensation de l'eau (à l'origine de la corrosion et donc d'une rupture possible des pipelines) et à la formation de glace et/ou d'hydrates en sont les conséquences principales. Or la formation d'hydrates est un sérieux problème avec un risque de blocage des pipelines. Pour éviter la formation des hydrates, des inhibiteurs chimiques sont utilisés. Il est donc indispensable de bien connaitre les équilibres entre phases pour les différents mélanges considérés pour un fonctionnement et une production en toute sécurité. / The twentieth century has seen an important increase of the fossil energy demand, representing today 80% of world energy consumption. To meet the request, oil and gas companies are interested in new gas fields. 40% of these reserves are acid and sour gases, i.e. the percentage of carbon dioxide and hydrogen sulphide is significant, sometimes over 20% of CO2 or H2S. Natural gas production with high content of acid gases can be a challenge, due to their corrosiveness potential in pipelines in the presence of water and H2S toxicity. On another hand, as a result of world's dependence on fossil energies, the release of carbon into atmosphere is increasing and leads to climate changes. Carbon Capture and Storage (CCS) is one of the most promising ways to reduce CO2 emissions in the atmosphere. Whether in natural gas or carbon dioxide transport, water may be present. During production, transportation and processing, changes in temperature and pressure can lead to water condensation (cause of corrosion, and consequently a possible pipeline rupture), ice and/or gas hydrates formation. Hydrates are a serious flow assurance problem and may block pipelines. To avoid hydrates formation, chemical inhibitors are used. Therefore accurate knowledge of mixtures phase equilibria are important for safe operation of pipelines and production/processing facilities.

No description available.

O fator de compressibilidade (Z) de gás natural é utilizado em vários cálculos na engenharia de petróleo (avaliação de formações, perda de carga em tubulações, gradiente de pressão em poços de gás, cálculos de balanço de massa, medição de gás, compressão e processamento de gás). As fontes mais comuns de valores de Z são medições experimentais, caras e demoradas. Essa propriedade também é estimada por correlações empíricas, modelos baseados no princípio dos estados correspondentes ou equações de estado (EOS). Foram avaliadas as capacidades das EOS de Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), Patel-Teja (PT), Patel-Teja-Valderrama (PTV), Schmidt-Wenzel (SW), Lawal-Lake-Silberberg (LLS) e AGA-8 para previsão desta propriedade em aproximadamente 2200 pontos de dados experimentais. Estes pontos foram divididos em quatro grupos: Grupo 1 (Presença de frações C7+, Grupo 2 (temperaturas inferiores a 258,15 K), Grupo 3 (pressões superiores a 10000 kPa) e Grupo 4 (pressões inferiores a 10000 kPa). Os cálculos utilizando as equações de estado sob diferentes esquemas de previsão de coeficientes binários de interação foram cuidadosamente investigados. Os resultados sugerem que a EOS AGA-8 apresenta os menores erros para pressões de até 70000 kPa. Entretanto, observou-se uma tendência de aumento nos desvios médios absolutos em função das concentrações de CO2 e H2S. As EOS PTV e a EOS SW são capazes de predizer o fator de compressibilidade (Z) com desvios médios absolutos entre os valores calculados e experimentais com precisão satisfatória para a maioria das aplicações, para uma variada faixa de temperatura e pressão. Este estudo também apresenta uma avaliação de 224 métodos de cálculo de Z onde foram utilizadas 8 correlações combinadas com 4 regras de mistura para estimativa de temperaturas e pressões pseudorreduzidas das amostras, junto com 7 métodos de caracterização das propriedades críticas da fração C7+, quando presente na composição do gás. Em função dos resultados são sugeridas, para diferentes tipos de sistemas, as melhores combinações de correlações com regras de mistura capazes de predizer fatores de compressibilidade (Z) com os menores erros absolutos médios relativos / The compressibility factor (Z-factor) of natural gases is necessary in many petroleum engineering calculations (evaluation of formation, pressure drop through a pipe, pressure gradient in gas wells, material balance calculations, gas metering, gas compression and processing). The most common sources of Z-factor values are experimental measurements, which are expensive and time consuming. This property is also estimated from empirical correlations, corresponding state models or equations of state (EOS) when experimental data is unavailable. Capabilities of Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), Patel-Teja (PT), Patel-Teja-Valderrama (PTV), Schmidt-Wenzel (SW), Lawal-Lake-Silberberg (LLS) and AGA-8 to predict this property of 2200 data points under various schemes of binary interaction numbers are thoroughly investigated. This database was split on four groups: Group 1 (presence of hydrocarbon plus fraction - C7+), Group 2 (temperatures lower than 258.15 K), Group 3 (pressures higher than 10000 kPa) e Group 4 (pressures lower than 10000 kPa). The best results were obtained from EOS AGA-8 for pressures up to 70000 kPa. However, an increasing trend in average absolute deviations was observed as a function of CO2 e H2S concentrations. EOS PTV and EOS SW are capable to predict the compressibility factor (Z) with average absolute deviation between calculated and experimental values with satisfactory accuracy for most applications for a wide range of temperature and pressure. This study also presents an evaluation of 224 possible methods of calculating the gas compressibility factor, based on 8 correlations and corresponding state models, combined with 4 mixing rule that predict the pseudo-reduced pressure and temperatures of the mixture, that were combined with 7 methods of characterizing the plus fraction critical properties when present in the gas composition. Results suggest for different systems conditions, the best correlation and mixing rule combination capable of predicting Z-factor with the least average absolute relative error

In this thesis, we study periodic solutions and stability of differential equations with piecewise constant argument of generalized type. These equations can be divided into three main classes: differential equations with retarded, alternately advanced-retarded, and state-dependent piecewise constant argument of generalized type. First, using the method of small parameter due to Poincar&eacute / , the existence and stability of periodic solutions of quasilinear differential equations with retarded piecewise constant argument of generalized type in noncritical case, that is, the unperturbed linear ordinary differential equation has not any nontrivial periodic solution, are investigated. The continuous and differential dependence of the solutions on an initial value and a parameter is considered. A new Gronwall-Bellmann type lemma is proved. Next, quasilinear differential equations with alternately advanced-retarded piecewise constant argument of generalized type is addressed. The critical case, when associated linear homogeneous system admits nontrivial periodic solutions, is considered. Using the technique of Poincar&eacute / -Malkin, criteria of existence of periodic solutions of such equations are obtained. One of the main auxiliary results is an analogue of Gronwall-Bellmann Lemma for functions with alternately advanced-retarded piecewise constant argument. Dependence of solutions on an initial value and a parameter is investigated. Finally, a new class of differential equations with state-dependent piecewise constant argument is introduced. It is an extension of systems with piecewise constant argument. Fundamental theoretical results for the equations: existence and uniqueness of solutions, the existence of the periodic solutions, the stability of the zero solution are obtained. Appropriate examples are constructed.