Repositorio Ciencia Abierta Universidad del Bío-Bío

Las nuevas tecnologías generan una necesidad de modernización y los sistemas de tributación no están exentos de esto. Los contribuyentes más pequeños tienden a ser los que más problemas tienen para enfrentar este tipo de cambios, ya sea por una falta de alfabetización digital o por necesidad de nuevo equipamiento que genera la modernización. Es fundamental generar un entendimiento de las modificaciones generadas por la implementación de la boleta electrónica con el fin de no incurrir en errores al momento de efectuar la tributación, para eso es fundamental comprender el marco legal al que se atiene este documento electrónico. También se debe comprender los distintos medios por los cuales se puede emitir una boleta electrónica, determinando de esta manera sus diferencias con el fin de estipular cual es mejor para cada empresa. Cabe señalar que entender las diferencias entre los sistemas antiguos el nuevo sistema de emisión electrónica ayuda a mejorar la comprensión de los procedimientos y de esta manera evitar incurrir en errores al momento de tributar, por lo cual analizar las diferencias generadas entre la boleta electrónica y sus métodos predecesores es recomendable. Por todo lo anterior, es relevante generar una guía de emisión básica que cualquier contribuyente sea capaz de entender de forma fácil y sencilla en la cual se explique las diferencias entre los sistemas de emisión de boletas electrónicas y como implementarlos. La presente investigación se basa en un enfoque cualitativo realizando una revisión documental de las normas, resoluciones y leyes pertinentes a la emisión de boletas electrónicas con un alcance exploratorio/descriptivo al desarrollar un tema nuevo en Chile por el poco tiempo que lleva en vigencia, al mismo tiempo se persigue un alcance descriptivo con la confección de una guía de boleta electrónica. Por último, se busca un análisis longitudinal al comparar la situación antes y después de las nuevas regulaciones exigidas por el Servicio de Impuestos Internos para la emisión. En conclusión, si bien la boleta electrónica fue un cambio complicado para los pequeños contribuyentes, se dispusieron métodos para solventar las brechas y problemas con tal de acelerar la incorporación de los medios de emisión electrónicos en las empresas dando una amplia variedad de opciones a conveniencia del contribuyente y sus necesidades al mismo tiempo que se bajaron las exigencias para poder ser emisor de boletas electrónicas.

PYROLYSIS REPRESENTS A PROMISING ROUTE FOR THE VALORISATION OF LIGNOCELLULOSIC WASTE AND A POTENTIAL SUBSTITUTE FOR FOSSIL FUELS. THIS STUDY INVESTIGATED, THROUGH A FACTORIAL ANALYTICAL SCREENING APPROACH, THE CATALYTIC CO- HYDROPYROLYSIS OF RICE HUSK (RH) AND COFFEE HUSK (CH) USING A GALLIUM-MODIFIED NATURAL ZEOLITE CATALYST (GA5/H2NHZ) IN A PY-GC/MS SYSTEM. AS AN ANALYTICAL SCREENING STUDY, THE OBJECTIVE WAS TO IDENTIFY THE OPERATING CONDITIONS AND BIOMASS COMPOSITIONS THAT FAVOUR THE FORMATION OF VALUE-ADDED CONDENSABLE PRODUCTS. THE REPORTED PERCENTAGES REPRESENT RELATIVE SELECTIVITIES OF GC-DETECTABLE PRODUCTS. THE EFFECTS OF REACTION ATMOSPHERE (H2 AND HE), TEMPERATURES, HEATING RATES, AND BIOMASS MIXTURES ON PRODUCT COMPOSITION WERE EVALUATED. THE ATMOSPHERE WAS THE VARIABLE WITH THE GREATEST IMPACT. UNDER INERT CONDITIONS (HE), MAXIMUM APPARENT SELEC- TIVITIES OF 48.92% FOR ACIDS AND 28.82% FOR ALDEHYDES WERE OBTAINED, WHEREAS HYDROPYROLYSIS REACHED 37.02% FOR KETONES, 22.10% FOR ALIPHATIC HYDROCARBONS, 16.24% FOR FURANS, 13.45% FOR PHENOLS, AND 10.31% FOR AROMATIC HYDROCARBONS. CH SHOWED A GREATER TENDENCY TOWARD KETONE AND ALIPHATIC HYDROCARBON FORMATION, WHEREAS AROMATIC HYDROCARBONS WERE ENHANCED AT 3:1 RH:CH RATIO. CO-PYROLYSIS SHOWED VARIABLE SYNERGISTIC EFFECTS ON ALIPHATIC AND AROMATIC HYDROCARBONS IN THE PRESENCE OF A CATALYST, PROMOTING DEOXYGENATION AND CRACKING, REDUCING THE OXYGEN CONTENT IN THE PRODUCTS. THE USE OF ISOCONVERSIONAL METHODS (FWO, KAS, AND FR) ALLOWED ESTIMATION OF THE KINETIC TRIPLET (APPARENT ACTIVATION ENERGY, PRE-EXPONENTIAL FACTOR, AND REACTION MODEL); THERMODYNAMIC PARAMETERS WERE LIKEWISE CALCULATED. FINALLY, A REACTION PATHWAY SCHEME FOR LIGNOCELLULOSIC MATERIALS WAS PROPOSED. THESE RESULTS PROVIDE MECHANISTIC INSIGHTS INTO PRODUCT FORMATION TRENDS DURING CATALYTIC CO-HYDROPYROLYSIS AND SUPPORT THE POTENTIAL OF RH AND CH AS FEEDSTOCKS FOR FUTURE VALORISATION STUDIES.

SATELLITE CHLOROPHYLL–A (CHLA) PRODUCTS ARE WIDELY USED TO STUDY COASTAL PRODUCTIVITY, BUT THEIR PERFORMANCE OFTEN DEGRADES IN RIVER-INFLUENCED AND OPTICALLY COMPLEX WATERS. WE EVALUATED MODIS-AQUA CHLA RETRIEVALS IN THE COASTAL UPWELLING AREA OFF CENTRAL-SOUTHERN CHILE, A REGION STRONGLY AFFECTED BY SEASONAL RIVER PLUMES, USING MONTHLY IN SITU CHLA AND HYDROGRAPHIC OBSERVATIONS FROM STATION 18 (AUGUST 2002 TO SEPTEMBER 2011), DAILY MODIS PRODUCTS, AND MATCHUP ANALYSES BASED ON 3 × 3 PIXEL WINDOWS AND 1-, 3-, 5-, AND 7-DAY COMPOSITES. MODIS CHLA AND NORMALIZED FLUORESCENCE LINE HEIGHT (NFLH) REPRODUCED THE BROAD SEASONAL CYCLE, WITH MAXIMA DURING SPRING–SUMMER, BUT DEFAULT MODIS CHLA SYSTEMATICALLY EXCEEDED IN SITU OBSERVATIONS, PARTICULARLY DURING PERIODS OF ENHANCED TURBIDITY AND RIVER-INFLUENCED OPTICAL COMPLEXITY. AMONG THE RAW SATELLITE PRODUCTS, 1-DAY MODIS CHLA MATCHUPS SHOWED THE STRONGEST AGREEMENT WITH IN SITU CHLA (R = 0.77, RMSE = 8.5 MG M−3), WHEREAS 5-DAY COMPOSITES INCREASED MATCHUP AVAILABILITY TO 95% BUT REDUCED THE CORRELATION (R = 0.46, RMSE = 10.5 MG M−3). IN CONTRAST, NFLH SHOWED MORE STABLE PERFORMANCE ACROSS COMPOSITE LENGTHS, ALTHOUGH IT UNDERESTIMATED HIGH CHLA VALUES AND SHOULD THEREFORE BE INTERPRETED AS A COMPLEMENTARY FLUORESCENCE-BASED DIAGNOSTIC RATHER THAN AS A DIRECT SUBSTITUTE FOR LOCALLY VALIDATED CHLA RETRIEVALS. A GRADIENT BOOSTING MODEL TRAINED WITH MODIS REMOTE-SENSING REFLECTANCES IMPROVED THE CORRESPONDENCE BETWEEN SATELLITE AND IN SITU CHLA RELATIVE TO THE DEFAULT MODIS PRODUCT WITHIN THE AVAILABLE STATION 18 MATCHUP DATASET. BECAUSE THIS MODEL WAS EVALUATED USING CROSS-VALIDATION RATHER THAN AN INDEPENDENT REGIONAL VALIDATION DATASET, THE MACHINE-LEARNING RESULTS SHOULD BE INTERPRETED AS A LOCAL PROOF OF CONCEPT RATHER THAN A FULLY VALIDATED REGIONAL ALGORITHM. THESE RESULTS INDICATE THAT STANDARD MODIS ALGORITHMS OVERESTIMATE CHLA IN THIS RIVER-INFLUENCED UPWELLING SYSTEM AND HIGHLIGHT THE VALUE OF LOCAL CORRECTION APPROAC

CONTINUOUS MEDIUM-DENSITY FIBERBOARD (MDF) PRODUCTION PRESENTS A PERSISTENT QUALITY-ASSURANCE PROBLEM: DESTRUCTIVE LABORATORY TESTS RETURN RESULTS TOO LATE TO PREVENT OFF-SPECIFICATION MATERIAL FROM ACCUMULATING BEFORE A CORRECTIVE RESPONSE IS POSSIBLE. THIS STUDY DEVELOPS AN INSPECTION-ORIENTED PREDICTIVE QUALITY FRAMEWORK USING INDUSTRIAL DISTRIBUTED CONTROL SYSTEM (DCS) DATA AND AUTOMATED MACHINE LEARNING, TREATING THE PRODUCTION LINE AS AN INTEGRATED NINE-STAGE SYSTEM IN WHICH UPSTREAM PROCESS DISTURBANCES PROPAGATE THROUGH COUPLED THERMOMECHANICAL AND CHEMICAL OPERATIONS BEFORE BECOMING VISIBLE IN FINAL PANEL PROPERTIES. TWO QUALITY TARGETS WERE MODELED ACROSS ULTRALIGHT (UL) AND STANDARD THIN (STD) PANELS USING 3365 PRODUCTION BATCHES AND 327 DCS PROCESS VARIABLES. THE PIPELINE COMBINED RANDOM FOREST IMPUTATION, PEARSON COLLINEARITY FILTERING (|𝑟|≥0.8 ), TARGET-SPECIFIC FEATURE SELECTION, AND STACKED ENSEMBLE REGRESSION VIA H2O AUTOML. THE VERTICAL DENSITY PROFILE INDEX (VSC), A PLANT-REPORTED SCALAR DERIVED FROM X-RAY DENSITY PROFILING, WAS PREDICTED ACCURATELY IN BOTH PRODUCT FAMILIES (TEST RMSE: 1.39 AND 1.78, INDEX UNITS FOR UL AND STD RESPECTIVELY), REFLECTING ITS CLOSE COUPLING TO DRYING STABILITY, RESIN DOSING, AND THERMAL CONDITIONS. INTERNAL BOND STRENGTH (IB) WAS HARDER TO PREDICT, ESPECIALLY FOR THIN STD PANELS (TEST RMSE: 78.93 KPA VS. 27.41 KPA FOR UL), AS CORE-LAYER BONDING MECHANISMS ARE ONLY INDIRECTLY OBSERVABLE THROUGH STANDARD DCS INSTRUMENTATION. MODEL-AGNOSTIC FEATURE IMPORTANCE RANKINGS WERE PHYSICALLY COHERENT ACROSS BOTH PRODUCT FAMILIES, WITH DOMINANT PREDICTORS CONCENTRATED IN DRYING, RESIN APPLICATION, FORMING, AND HOT PRESSING, CONSISTENT WITH THE COUPLED-SUBSYSTEM NATURE OF MDF QUALITY FORMATION. THE HISTORICAL DATASET WAS DOMINATED BY ACCEPTABLE AND OVER-QUALITY IB PRODUCTION, WHICH PRECLUDED CONFORMITY CLASSIFICATION AND SAMPLING-REDUCTION ANALYSIS; A PROSPECTIVE DATASET WITH NEAR-THRESHOLD OBSERVATIONS IS REQUIRED FOR THOSE EVA